md: split mddev_find

[mirror_ubuntu-jammy-kernel.git] / drivers / md / md.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
   md.c : Multiple Devices driver for Linux
     Copyright (C) 1998, 1999, 2000 Ingo Molnar

     completely rewritten, based on the MD driver code from Marc Zyngier

   Changes:

   - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
   - RAID-6 extensions by H. Peter Anvin <hpa@zytor.com>
   - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
   - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
   - kmod support by: Cyrus Durgin
   - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
   - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>

   - lots of fixes and improvements to the RAID1/RAID5 and generic
     RAID code (such as request based resynchronization):

     Neil Brown <neilb@cse.unsw.edu.au>.

   - persistent bitmap code
     Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.


   Errors, Warnings, etc.
   Please use:
     pr_crit() for error conditions that risk data loss
     pr_err() for error conditions that are unexpected, like an IO error
         or internal inconsistency
     pr_warn() for error conditions that could have been predicated, like
         adding a device to an array when it has incompatible metadata
     pr_info() for every interesting, very rare events, like an array starting
         or stopping, or resync starting or stopping
     pr_debug() for everything else.

*/

#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/kthread.h>
#include <linux/blkdev.h>
#include <linux/badblocks.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/hdreg.h>
#include <linux/proc_fs.h>
#include <linux/random.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/file.h>
#include <linux/compat.h>
#include <linux/delay.h>
#include <linux/raid/md_p.h>
#include <linux/raid/md_u.h>
#include <linux/raid/detect.h>
#include <linux/slab.h>
#include <linux/percpu-refcount.h>
#include <linux/part_stat.h>

#include <trace/events/block.h>
#include "md.h"
#include "md-bitmap.h"
#include "md-cluster.h"

/* pers_list is a list of registered personalities protected
 * by pers_lock.
 * pers_lock does extra service to protect accesses to
 * mddev->thread when the mutex cannot be held.
 */
static LIST_HEAD(pers_list);
static DEFINE_SPINLOCK(pers_lock);

static struct kobj_type md_ktype;

struct md_cluster_operations *md_cluster_ops;
EXPORT_SYMBOL(md_cluster_ops);
static struct module *md_cluster_mod;

static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
static struct workqueue_struct *md_wq;
static struct workqueue_struct *md_misc_wq;
static struct workqueue_struct *md_rdev_misc_wq;

static int remove_and_add_spares(struct mddev *mddev,
                                 struct md_rdev *this);
static void mddev_detach(struct mddev *mddev);

/*
 * Default number of read corrections we'll attempt on an rdev
 * before ejecting it from the array. We divide the read error
 * count by 2 for every hour elapsed between read errors.
 */
#define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
/* Default safemode delay: 200 msec */
#define DEFAULT_SAFEMODE_DELAY ((200 * HZ)/1000 +1)
/*
 * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
 * is 1000 KB/sec, so the extra system load does not show up that much.
 * Increase it if you want to have more _guaranteed_ speed. Note that
 * the RAID driver will use the maximum available bandwidth if the IO
 * subsystem is idle. There is also an 'absolute maximum' reconstruction
 * speed limit - in case reconstruction slows down your system despite
 * idle IO detection.
 *
 * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
 * or /sys/block/mdX/md/sync_speed_{min,max}
 */

static int sysctl_speed_limit_min = 1000;
static int sysctl_speed_limit_max = 200000;
static inline int speed_min(struct mddev *mddev)
{
        return mddev->sync_speed_min ?
                mddev->sync_speed_min : sysctl_speed_limit_min;
}

static inline int speed_max(struct mddev *mddev)
{
        return mddev->sync_speed_max ?
                mddev->sync_speed_max : sysctl_speed_limit_max;
}

static void rdev_uninit_serial(struct md_rdev *rdev)
{
        if (!test_and_clear_bit(CollisionCheck, &rdev->flags))
                return;

        kvfree(rdev->serial);
        rdev->serial = NULL;
}

static void rdevs_uninit_serial(struct mddev *mddev)
{
        struct md_rdev *rdev;

        rdev_for_each(rdev, mddev)
                rdev_uninit_serial(rdev);
}

static int rdev_init_serial(struct md_rdev *rdev)
{
        /* serial_nums equals with BARRIER_BUCKETS_NR */
        int i, serial_nums = 1 << ((PAGE_SHIFT - ilog2(sizeof(atomic_t))));
        struct serial_in_rdev *serial = NULL;

        if (test_bit(CollisionCheck, &rdev->flags))
                return 0;

        serial = kvmalloc(sizeof(struct serial_in_rdev) * serial_nums,
                          GFP_KERNEL);
        if (!serial)
                return -ENOMEM;

        for (i = 0; i < serial_nums; i++) {
                struct serial_in_rdev *serial_tmp = &serial[i];

                spin_lock_init(&serial_tmp->serial_lock);
                serial_tmp->serial_rb = RB_ROOT_CACHED;
                init_waitqueue_head(&serial_tmp->serial_io_wait);
        }

        rdev->serial = serial;
        set_bit(CollisionCheck, &rdev->flags);

        return 0;
}

static int rdevs_init_serial(struct mddev *mddev)
{
        struct md_rdev *rdev;
        int ret = 0;

        rdev_for_each(rdev, mddev) {
                ret = rdev_init_serial(rdev);
                if (ret)
                        break;
        }

        /* Free all resources if pool is not existed */
        if (ret && !mddev->serial_info_pool)
                rdevs_uninit_serial(mddev);

        return ret;
}

/*
 * rdev needs to enable serial stuffs if it meets the conditions:
 * 1. it is multi-queue device flaged with writemostly.
 * 2. the write-behind mode is enabled.
 */
static int rdev_need_serial(struct md_rdev *rdev)
{
        return (rdev && rdev->mddev->bitmap_info.max_write_behind > 0 &&
                rdev->bdev->bd_disk->queue->nr_hw_queues != 1 &&
                test_bit(WriteMostly, &rdev->flags));
}

/*
 * Init resource for rdev(s), then create serial_info_pool if:
 * 1. rdev is the first device which return true from rdev_enable_serial.
 * 2. rdev is NULL, means we want to enable serialization for all rdevs.
 */
void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
                              bool is_suspend)
{
        int ret = 0;

        if (rdev && !rdev_need_serial(rdev) &&
            !test_bit(CollisionCheck, &rdev->flags))
                return;

        if (!is_suspend)
                mddev_suspend(mddev);

        if (!rdev)
                ret = rdevs_init_serial(mddev);
        else
                ret = rdev_init_serial(rdev);
        if (ret)
                goto abort;

        if (mddev->serial_info_pool == NULL) {
                /*
                 * already in memalloc noio context by
                 * mddev_suspend()
                 */
                mddev->serial_info_pool =
                        mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
                                                sizeof(struct serial_info));
                if (!mddev->serial_info_pool) {
                        rdevs_uninit_serial(mddev);
                        pr_err("can't alloc memory pool for serialization\n");
                }
        }

abort:
        if (!is_suspend)
                mddev_resume(mddev);
}

/*
 * Free resource from rdev(s), and destroy serial_info_pool under conditions:
 * 1. rdev is the last device flaged with CollisionCheck.
 * 2. when bitmap is destroyed while policy is not enabled.
 * 3. for disable policy, the pool is destroyed only when no rdev needs it.
 */
void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
                               bool is_suspend)
{
        if (rdev && !test_bit(CollisionCheck, &rdev->flags))
                return;

        if (mddev->serial_info_pool) {
                struct md_rdev *temp;
                int num = 0; /* used to track if other rdevs need the pool */

                if (!is_suspend)
                        mddev_suspend(mddev);
                rdev_for_each(temp, mddev) {
                        if (!rdev) {
                                if (!mddev->serialize_policy ||
                                    !rdev_need_serial(temp))
                                        rdev_uninit_serial(temp);
                                else
                                        num++;
                        } else if (temp != rdev &&
                                   test_bit(CollisionCheck, &temp->flags))
                                num++;
                }

                if (rdev)
                        rdev_uninit_serial(rdev);

                if (num)
                        pr_info("The mempool could be used by other devices\n");
                else {
                        mempool_destroy(mddev->serial_info_pool);
                        mddev->serial_info_pool = NULL;
                }
                if (!is_suspend)
                        mddev_resume(mddev);
        }
}

static struct ctl_table_header *raid_table_header;

static struct ctl_table raid_table[] = {
        {
                .procname       = "speed_limit_min",
                .data           = &sysctl_speed_limit_min,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = proc_dointvec,
        },
        {
                .procname       = "speed_limit_max",
                .data           = &sysctl_speed_limit_max,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO|S_IWUSR,
                .proc_handler   = proc_dointvec,
        },
        { }
};

static struct ctl_table raid_dir_table[] = {
        {
                .procname       = "raid",
                .maxlen         = 0,
                .mode           = S_IRUGO|S_IXUGO,
                .child          = raid_table,
        },
        { }
};

static struct ctl_table raid_root_table[] = {
        {
                .procname       = "dev",
                .maxlen         = 0,
                .mode           = 0555,
                .child          = raid_dir_table,
        },
        {  }
};

static int start_readonly;

/*
 * The original mechanism for creating an md device is to create
 * a device node in /dev and to open it.  This causes races with device-close.
 * The preferred method is to write to the "new_array" module parameter.
 * This can avoid races.
 * Setting create_on_open to false disables the original mechanism
 * so all the races disappear.
 */
static bool create_on_open = true;

/*
 * We have a system wide 'event count' that is incremented
 * on any 'interesting' event, and readers of /proc/mdstat
 * can use 'poll' or 'select' to find out when the event
 * count increases.
 *
 * Events are:
 *  start array, stop array, error, add device, remove device,
 *  start build, activate spare
 */
static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
static atomic_t md_event_count;
void md_new_event(struct mddev *mddev)
{
        atomic_inc(&md_event_count);
        wake_up(&md_event_waiters);
}
EXPORT_SYMBOL_GPL(md_new_event);

/*
 * Enables to iterate over all existing md arrays
 * all_mddevs_lock protects this list.
 */
static LIST_HEAD(all_mddevs);
static DEFINE_SPINLOCK(all_mddevs_lock);

/*
 * iterates through all used mddevs in the system.
 * We take care to grab the all_mddevs_lock whenever navigating
 * the list, and to always hold a refcount when unlocked.
 * Any code which breaks out of this loop while own
 * a reference to the current mddev and must mddev_put it.
 */
#define for_each_mddev(_mddev,_tmp)                                     \
                                                                        \
        for (({ spin_lock(&all_mddevs_lock);                            \
                _tmp = all_mddevs.next;                                 \
                _mddev = NULL;});                                       \
             ({ if (_tmp != &all_mddevs)                                \
                        mddev_get(list_entry(_tmp, struct mddev, all_mddevs));\
                spin_unlock(&all_mddevs_lock);                          \
                if (_mddev) mddev_put(_mddev);                          \
                _mddev = list_entry(_tmp, struct mddev, all_mddevs);    \
                _tmp != &all_mddevs;});                                 \
             ({ spin_lock(&all_mddevs_lock);                            \
                _tmp = _tmp->next;})                                    \
                )

/* Rather than calling directly into the personality make_request function,
 * IO requests come here first so that we can check if the device is
 * being suspended pending a reconfiguration.
 * We hold a refcount over the call to ->make_request.  By the time that
 * call has finished, the bio has been linked into some internal structure
 * and so is visible to ->quiesce(), so we don't need the refcount any more.
 */
static bool is_suspended(struct mddev *mddev, struct bio *bio)
{
        if (mddev->suspended)
                return true;
        if (bio_data_dir(bio) != WRITE)
                return false;
        if (mddev->suspend_lo >= mddev->suspend_hi)
                return false;
        if (bio->bi_iter.bi_sector >= mddev->suspend_hi)
                return false;
        if (bio_end_sector(bio) < mddev->suspend_lo)
                return false;
        return true;
}

void md_handle_request(struct mddev *mddev, struct bio *bio)
{
check_suspended:
        rcu_read_lock();
        if (is_suspended(mddev, bio)) {
                DEFINE_WAIT(__wait);
                for (;;) {
                        prepare_to_wait(&mddev->sb_wait, &__wait,
                                        TASK_UNINTERRUPTIBLE);
                        if (!is_suspended(mddev, bio))
                                break;
                        rcu_read_unlock();
                        schedule();
                        rcu_read_lock();
                }
                finish_wait(&mddev->sb_wait, &__wait);
        }
        atomic_inc(&mddev->active_io);
        rcu_read_unlock();

        if (!mddev->pers->make_request(mddev, bio)) {
                atomic_dec(&mddev->active_io);
                wake_up(&mddev->sb_wait);
                goto check_suspended;
        }

        if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
                wake_up(&mddev->sb_wait);
}
EXPORT_SYMBOL(md_handle_request);

struct md_io {
        struct mddev *mddev;
        bio_end_io_t *orig_bi_end_io;
        void *orig_bi_private;
        struct block_device *orig_bi_bdev;
        unsigned long start_time;
};

static void md_end_io(struct bio *bio)
{
        struct md_io *md_io = bio->bi_private;
        struct mddev *mddev = md_io->mddev;

        bio_end_io_acct_remapped(bio, md_io->start_time, md_io->orig_bi_bdev);

        bio->bi_end_io = md_io->orig_bi_end_io;
        bio->bi_private = md_io->orig_bi_private;

        mempool_free(md_io, &mddev->md_io_pool);

        if (bio->bi_end_io)
                bio->bi_end_io(bio);
}

static blk_qc_t md_submit_bio(struct bio *bio)
{
        const int rw = bio_data_dir(bio);
        struct mddev *mddev = bio->bi_bdev->bd_disk->private_data;

        if (mddev == NULL || mddev->pers == NULL) {
                bio_io_error(bio);
                return BLK_QC_T_NONE;
        }

        if (unlikely(test_bit(MD_BROKEN, &mddev->flags)) && (rw == WRITE)) {
                bio_io_error(bio);
                return BLK_QC_T_NONE;
        }

        blk_queue_split(&bio);

        if (mddev->ro == 1 && unlikely(rw == WRITE)) {
                if (bio_sectors(bio) != 0)
                        bio->bi_status = BLK_STS_IOERR;
                bio_endio(bio);
                return BLK_QC_T_NONE;
        }

        if (bio->bi_end_io != md_end_io) {
                struct md_io *md_io;

                md_io = mempool_alloc(&mddev->md_io_pool, GFP_NOIO);
                md_io->mddev = mddev;
                md_io->orig_bi_end_io = bio->bi_end_io;
                md_io->orig_bi_private = bio->bi_private;
                md_io->orig_bi_bdev = bio->bi_bdev;

                bio->bi_end_io = md_end_io;
                bio->bi_private = md_io;

                md_io->start_time = bio_start_io_acct(bio);
        }

        /* bio could be mergeable after passing to underlayer */
        bio->bi_opf &= ~REQ_NOMERGE;

        md_handle_request(mddev, bio);

        return BLK_QC_T_NONE;
}

/* mddev_suspend makes sure no new requests are submitted
 * to the device, and that any requests that have been submitted
 * are completely handled.
 * Once mddev_detach() is called and completes, the module will be
 * completely unused.
 */
void mddev_suspend(struct mddev *mddev)
{
        WARN_ON_ONCE(mddev->thread && current == mddev->thread->tsk);
        lockdep_assert_held(&mddev->reconfig_mutex);
        if (mddev->suspended++)
                return;
        synchronize_rcu();
        wake_up(&mddev->sb_wait);
        set_bit(MD_ALLOW_SB_UPDATE, &mddev->flags);
        smp_mb__after_atomic();
        wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
        mddev->pers->quiesce(mddev, 1);
        clear_bit_unlock(MD_ALLOW_SB_UPDATE, &mddev->flags);
        wait_event(mddev->sb_wait, !test_bit(MD_UPDATING_SB, &mddev->flags));

        del_timer_sync(&mddev->safemode_timer);
        /* restrict memory reclaim I/O during raid array is suspend */
        mddev->noio_flag = memalloc_noio_save();
}
EXPORT_SYMBOL_GPL(mddev_suspend);

void mddev_resume(struct mddev *mddev)
{
        /* entred the memalloc scope from mddev_suspend() */
        memalloc_noio_restore(mddev->noio_flag);
        lockdep_assert_held(&mddev->reconfig_mutex);
        if (--mddev->suspended)
                return;
        wake_up(&mddev->sb_wait);
        mddev->pers->quiesce(mddev, 0);

        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
}
EXPORT_SYMBOL_GPL(mddev_resume);

/*
 * Generic flush handling for md
 */

static void md_end_flush(struct bio *bio)
{
        struct md_rdev *rdev = bio->bi_private;
        struct mddev *mddev = rdev->mddev;

        rdev_dec_pending(rdev, mddev);

        if (atomic_dec_and_test(&mddev->flush_pending)) {
                /* The pre-request flush has finished */
                queue_work(md_wq, &mddev->flush_work);
        }
        bio_put(bio);
}

static void md_submit_flush_data(struct work_struct *ws);

static void submit_flushes(struct work_struct *ws)
{
        struct mddev *mddev = container_of(ws, struct mddev, flush_work);
        struct md_rdev *rdev;

        mddev->start_flush = ktime_get_boottime();
        INIT_WORK(&mddev->flush_work, md_submit_flush_data);
        atomic_set(&mddev->flush_pending, 1);
        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev)
                if (rdev->raid_disk >= 0 &&
                    !test_bit(Faulty, &rdev->flags)) {
                        /* Take two references, one is dropped
                         * when request finishes, one after
                         * we reclaim rcu_read_lock
                         */
                        struct bio *bi;
                        atomic_inc(&rdev->nr_pending);
                        atomic_inc(&rdev->nr_pending);
                        rcu_read_unlock();
                        bi = bio_alloc_bioset(GFP_NOIO, 0, &mddev->bio_set);
                        bi->bi_end_io = md_end_flush;
                        bi->bi_private = rdev;
                        bio_set_dev(bi, rdev->bdev);
                        bi->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
                        atomic_inc(&mddev->flush_pending);
                        submit_bio(bi);
                        rcu_read_lock();
                        rdev_dec_pending(rdev, mddev);
                }
        rcu_read_unlock();
        if (atomic_dec_and_test(&mddev->flush_pending))
                queue_work(md_wq, &mddev->flush_work);
}

static void md_submit_flush_data(struct work_struct *ws)
{
        struct mddev *mddev = container_of(ws, struct mddev, flush_work);
        struct bio *bio = mddev->flush_bio;

        /*
         * must reset flush_bio before calling into md_handle_request to avoid a
         * deadlock, because other bios passed md_handle_request suspend check
         * could wait for this and below md_handle_request could wait for those
         * bios because of suspend check
         */
        spin_lock_irq(&mddev->lock);
        mddev->prev_flush_start = mddev->start_flush;
        mddev->flush_bio = NULL;
        spin_unlock_irq(&mddev->lock);
        wake_up(&mddev->sb_wait);

        if (bio->bi_iter.bi_size == 0) {
                /* an empty barrier - all done */
                bio_endio(bio);
        } else {
                bio->bi_opf &= ~REQ_PREFLUSH;
                md_handle_request(mddev, bio);
        }
}

/*
 * Manages consolidation of flushes and submitting any flushes needed for
 * a bio with REQ_PREFLUSH.  Returns true if the bio is finished or is
 * being finished in another context.  Returns false if the flushing is
 * complete but still needs the I/O portion of the bio to be processed.
 */
bool md_flush_request(struct mddev *mddev, struct bio *bio)
{
        ktime_t req_start = ktime_get_boottime();
        spin_lock_irq(&mddev->lock);
        /* flush requests wait until ongoing flush completes,
         * hence coalescing all the pending requests.
         */
        wait_event_lock_irq(mddev->sb_wait,
                            !mddev->flush_bio ||
                            ktime_before(req_start, mddev->prev_flush_start),
                            mddev->lock);
        /* new request after previous flush is completed */
        if (ktime_after(req_start, mddev->prev_flush_start)) {
                WARN_ON(mddev->flush_bio);
                mddev->flush_bio = bio;
                bio = NULL;
        }
        spin_unlock_irq(&mddev->lock);

        if (!bio) {
                INIT_WORK(&mddev->flush_work, submit_flushes);
                queue_work(md_wq, &mddev->flush_work);
        } else {
                /* flush was performed for some other bio while we waited. */
                if (bio->bi_iter.bi_size == 0)
                        /* an empty barrier - all done */
                        bio_endio(bio);
                else {
                        bio->bi_opf &= ~REQ_PREFLUSH;
                        return false;
                }
        }
        return true;
}
EXPORT_SYMBOL(md_flush_request);

static inline struct mddev *mddev_get(struct mddev *mddev)
{
        atomic_inc(&mddev->active);
        return mddev;
}

static void mddev_delayed_delete(struct work_struct *ws);

static void mddev_put(struct mddev *mddev)
{
        if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
                return;
        if (!mddev->raid_disks && list_empty(&mddev->disks) &&
            mddev->ctime == 0 && !mddev->hold_active) {
                /* Array is not configured at all, and not held active,
                 * so destroy it */
                list_del_init(&mddev->all_mddevs);

                /*
                 * Call queue_work inside the spinlock so that
                 * flush_workqueue() after mddev_find will succeed in waiting
                 * for the work to be done.
                 */
                INIT_WORK(&mddev->del_work, mddev_delayed_delete);
                queue_work(md_misc_wq, &mddev->del_work);
        }
        spin_unlock(&all_mddevs_lock);
}

static void md_safemode_timeout(struct timer_list *t);

void mddev_init(struct mddev *mddev)
{
        kobject_init(&mddev->kobj, &md_ktype);
        mutex_init(&mddev->open_mutex);
        mutex_init(&mddev->reconfig_mutex);
        mutex_init(&mddev->bitmap_info.mutex);
        INIT_LIST_HEAD(&mddev->disks);
        INIT_LIST_HEAD(&mddev->all_mddevs);
        timer_setup(&mddev->safemode_timer, md_safemode_timeout, 0);
        atomic_set(&mddev->active, 1);
        atomic_set(&mddev->openers, 0);
        atomic_set(&mddev->active_io, 0);
        spin_lock_init(&mddev->lock);
        atomic_set(&mddev->flush_pending, 0);
        init_waitqueue_head(&mddev->sb_wait);
        init_waitqueue_head(&mddev->recovery_wait);
        mddev->reshape_position = MaxSector;
        mddev->reshape_backwards = 0;
        mddev->last_sync_action = "none";
        mddev->resync_min = 0;
        mddev->resync_max = MaxSector;
        mddev->level = LEVEL_NONE;
}
EXPORT_SYMBOL_GPL(mddev_init);

static struct mddev *mddev_find_locked(dev_t unit)
{
        struct mddev *mddev;

        list_for_each_entry(mddev, &all_mddevs, all_mddevs)
                if (mddev->unit == unit)
                        return mddev;

        return NULL;
}

static struct mddev *mddev_find(dev_t unit)
{
        struct mddev *mddev;

        if (MAJOR(unit) != MD_MAJOR)
                unit &= ~((1 << MdpMinorShift) - 1);

        spin_lock(&all_mddevs_lock);
        mddev = mddev_find_locked(unit);
        if (mddev)
                mddev_get(mddev);
        spin_unlock(&all_mddevs_lock);

        return mddev;
}

static struct mddev *mddev_find_or_alloc(dev_t unit)
{
        struct mddev *mddev, *new = NULL;

        if (unit && MAJOR(unit) != MD_MAJOR)
                unit &= ~((1<<MdpMinorShift)-1);

 retry:
        spin_lock(&all_mddevs_lock);

        if (unit) {
                mddev = mddev_find_locked(unit);
                if (mddev) {
                        mddev_get(mddev);
                        spin_unlock(&all_mddevs_lock);
                        kfree(new);
                        return mddev;
                }

                if (new) {
                        list_add(&new->all_mddevs, &all_mddevs);
                        spin_unlock(&all_mddevs_lock);
                        new->hold_active = UNTIL_IOCTL;
                        return new;
                }
        } else if (new) {
                /* find an unused unit number */
                static int next_minor = 512;
                int start = next_minor;
                int is_free = 0;
                int dev = 0;
                while (!is_free) {
                        dev = MKDEV(MD_MAJOR, next_minor);
                        next_minor++;
                        if (next_minor > MINORMASK)
                                next_minor = 0;
                        if (next_minor == start) {
                                /* Oh dear, all in use. */
                                spin_unlock(&all_mddevs_lock);
                                kfree(new);
                                return NULL;
                        }

                        is_free = !mddev_find_locked(dev);
                }
                new->unit = dev;
                new->md_minor = MINOR(dev);
                new->hold_active = UNTIL_STOP;
                list_add(&new->all_mddevs, &all_mddevs);
                spin_unlock(&all_mddevs_lock);
                return new;
        }
        spin_unlock(&all_mddevs_lock);

        new = kzalloc(sizeof(*new), GFP_KERNEL);
        if (!new)
                return NULL;

        new->unit = unit;
        if (MAJOR(unit) == MD_MAJOR)
                new->md_minor = MINOR(unit);
        else
                new->md_minor = MINOR(unit) >> MdpMinorShift;

        mddev_init(new);

        goto retry;
}

static struct attribute_group md_redundancy_group;

void mddev_unlock(struct mddev *mddev)
{
        if (mddev->to_remove) {
                /* These cannot be removed under reconfig_mutex as
                 * an access to the files will try to take reconfig_mutex
                 * while holding the file unremovable, which leads to
                 * a deadlock.
                 * So hold set sysfs_active while the remove in happeing,
                 * and anything else which might set ->to_remove or my
                 * otherwise change the sysfs namespace will fail with
                 * -EBUSY if sysfs_active is still set.
                 * We set sysfs_active under reconfig_mutex and elsewhere
                 * test it under the same mutex to ensure its correct value
                 * is seen.
                 */
                struct attribute_group *to_remove = mddev->to_remove;
                mddev->to_remove = NULL;
                mddev->sysfs_active = 1;
                mutex_unlock(&mddev->reconfig_mutex);

                if (mddev->kobj.sd) {
                        if (to_remove != &md_redundancy_group)
                                sysfs_remove_group(&mddev->kobj, to_remove);
                        if (mddev->pers == NULL ||
                            mddev->pers->sync_request == NULL) {
                                sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
                                if (mddev->sysfs_action)
                                        sysfs_put(mddev->sysfs_action);
                                if (mddev->sysfs_completed)
                                        sysfs_put(mddev->sysfs_completed);
                                if (mddev->sysfs_degraded)
                                        sysfs_put(mddev->sysfs_degraded);
                                mddev->sysfs_action = NULL;
                                mddev->sysfs_completed = NULL;
                                mddev->sysfs_degraded = NULL;
                        }
                }
                mddev->sysfs_active = 0;
        } else
                mutex_unlock(&mddev->reconfig_mutex);

        /* As we've dropped the mutex we need a spinlock to
         * make sure the thread doesn't disappear
         */
        spin_lock(&pers_lock);
        md_wakeup_thread(mddev->thread);
        wake_up(&mddev->sb_wait);
        spin_unlock(&pers_lock);
}
EXPORT_SYMBOL_GPL(mddev_unlock);

struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr)
{
        struct md_rdev *rdev;

        rdev_for_each_rcu(rdev, mddev)
                if (rdev->desc_nr == nr)
                        return rdev;

        return NULL;
}
EXPORT_SYMBOL_GPL(md_find_rdev_nr_rcu);

static struct md_rdev *find_rdev(struct mddev *mddev, dev_t dev)
{
        struct md_rdev *rdev;

        rdev_for_each(rdev, mddev)
                if (rdev->bdev->bd_dev == dev)
                        return rdev;

        return NULL;
}

struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev)
{
        struct md_rdev *rdev;

        rdev_for_each_rcu(rdev, mddev)
                if (rdev->bdev->bd_dev == dev)
                        return rdev;

        return NULL;
}
EXPORT_SYMBOL_GPL(md_find_rdev_rcu);

static struct md_personality *find_pers(int level, char *clevel)
{
        struct md_personality *pers;
        list_for_each_entry(pers, &pers_list, list) {
                if (level != LEVEL_NONE && pers->level == level)
                        return pers;
                if (strcmp(pers->name, clevel)==0)
                        return pers;
        }
        return NULL;
}

/* return the offset of the super block in 512byte sectors */
static inline sector_t calc_dev_sboffset(struct md_rdev *rdev)
{
        sector_t num_sectors = i_size_read(rdev->bdev->bd_inode) / 512;
        return MD_NEW_SIZE_SECTORS(num_sectors);
}

static int alloc_disk_sb(struct md_rdev *rdev)
{
        rdev->sb_page = alloc_page(GFP_KERNEL);
        if (!rdev->sb_page)
                return -ENOMEM;
        return 0;
}

void md_rdev_clear(struct md_rdev *rdev)
{
        if (rdev->sb_page) {
                put_page(rdev->sb_page);
                rdev->sb_loaded = 0;
                rdev->sb_page = NULL;
                rdev->sb_start = 0;
                rdev->sectors = 0;
        }
        if (rdev->bb_page) {
                put_page(rdev->bb_page);
                rdev->bb_page = NULL;
        }
        badblocks_exit(&rdev->badblocks);
}
EXPORT_SYMBOL_GPL(md_rdev_clear);

static void super_written(struct bio *bio)
{
        struct md_rdev *rdev = bio->bi_private;
        struct mddev *mddev = rdev->mddev;

        if (bio->bi_status) {
                pr_err("md: %s gets error=%d\n", __func__,
                       blk_status_to_errno(bio->bi_status));
                md_error(mddev, rdev);
                if (!test_bit(Faulty, &rdev->flags)
                    && (bio->bi_opf & MD_FAILFAST)) {
                        set_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags);
                        set_bit(LastDev, &rdev->flags);
                }
        } else
                clear_bit(LastDev, &rdev->flags);

        if (atomic_dec_and_test(&mddev->pending_writes))
                wake_up(&mddev->sb_wait);
        rdev_dec_pending(rdev, mddev);
        bio_put(bio);
}

void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
                   sector_t sector, int size, struct page *page)
{
        /* write first size bytes of page to sector of rdev
         * Increment mddev->pending_writes before returning
         * and decrement it on completion, waking up sb_wait
         * if zero is reached.
         * If an error occurred, call md_error
         */
        struct bio *bio;
        int ff = 0;

        if (!page)
                return;

        if (test_bit(Faulty, &rdev->flags))
                return;

        bio = bio_alloc_bioset(GFP_NOIO, 1, &mddev->sync_set);

        atomic_inc(&rdev->nr_pending);

        bio_set_dev(bio, rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev);
        bio->bi_iter.bi_sector = sector;
        bio_add_page(bio, page, size, 0);
        bio->bi_private = rdev;
        bio->bi_end_io = super_written;

        if (test_bit(MD_FAILFAST_SUPPORTED, &mddev->flags) &&
            test_bit(FailFast, &rdev->flags) &&
            !test_bit(LastDev, &rdev->flags))
                ff = MD_FAILFAST;
        bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH | REQ_FUA | ff;

        atomic_inc(&mddev->pending_writes);
        submit_bio(bio);
}

int md_super_wait(struct mddev *mddev)
{
        /* wait for all superblock writes that were scheduled to complete */
        wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
        if (test_and_clear_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags))
                return -EAGAIN;
        return 0;
}

int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
                 struct page *page, int op, int op_flags, bool metadata_op)
{
        struct bio bio;
        struct bio_vec bvec;

        bio_init(&bio, &bvec, 1);

        if (metadata_op && rdev->meta_bdev)
                bio_set_dev(&bio, rdev->meta_bdev);
        else
                bio_set_dev(&bio, rdev->bdev);
        bio.bi_opf = op | op_flags;
        if (metadata_op)
                bio.bi_iter.bi_sector = sector + rdev->sb_start;
        else if (rdev->mddev->reshape_position != MaxSector &&
                 (rdev->mddev->reshape_backwards ==
                  (sector >= rdev->mddev->reshape_position)))
                bio.bi_iter.bi_sector = sector + rdev->new_data_offset;
        else
                bio.bi_iter.bi_sector = sector + rdev->data_offset;
        bio_add_page(&bio, page, size, 0);

        submit_bio_wait(&bio);

        return !bio.bi_status;
}
EXPORT_SYMBOL_GPL(sync_page_io);

static int read_disk_sb(struct md_rdev *rdev, int size)
{
        char b[BDEVNAME_SIZE];

        if (rdev->sb_loaded)
                return 0;

        if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, 0, true))
                goto fail;
        rdev->sb_loaded = 1;
        return 0;

fail:
        pr_err("md: disabled device %s, could not read superblock.\n",
               bdevname(rdev->bdev,b));
        return -EINVAL;
}

static int md_uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
        return  sb1->set_uuid0 == sb2->set_uuid0 &&
                sb1->set_uuid1 == sb2->set_uuid1 &&
                sb1->set_uuid2 == sb2->set_uuid2 &&
                sb1->set_uuid3 == sb2->set_uuid3;
}

static int md_sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
        int ret;
        mdp_super_t *tmp1, *tmp2;

        tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
        tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);

        if (!tmp1 || !tmp2) {
                ret = 0;
                goto abort;
        }

        *tmp1 = *sb1;
        *tmp2 = *sb2;

        /*
         * nr_disks is not constant
         */
        tmp1->nr_disks = 0;
        tmp2->nr_disks = 0;

        ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
abort:
        kfree(tmp1);
        kfree(tmp2);
        return ret;
}

static u32 md_csum_fold(u32 csum)
{
        csum = (csum & 0xffff) + (csum >> 16);
        return (csum & 0xffff) + (csum >> 16);
}

static unsigned int calc_sb_csum(mdp_super_t *sb)
{
        u64 newcsum = 0;
        u32 *sb32 = (u32*)sb;
        int i;
        unsigned int disk_csum, csum;

        disk_csum = sb->sb_csum;
        sb->sb_csum = 0;

        for (i = 0; i < MD_SB_BYTES/4 ; i++)
                newcsum += sb32[i];
        csum = (newcsum & 0xffffffff) + (newcsum>>32);

#ifdef CONFIG_ALPHA
        /* This used to use csum_partial, which was wrong for several
         * reasons including that different results are returned on
         * different architectures.  It isn't critical that we get exactly
         * the same return value as before (we always csum_fold before
         * testing, and that removes any differences).  However as we
         * know that csum_partial always returned a 16bit value on
         * alphas, do a fold to maximise conformity to previous behaviour.
         */
        sb->sb_csum = md_csum_fold(disk_csum);
#else
        sb->sb_csum = disk_csum;
#endif
        return csum;
}

/*
 * Handle superblock details.
 * We want to be able to handle multiple superblock formats
 * so we have a common interface to them all, and an array of
 * different handlers.
 * We rely on user-space to write the initial superblock, and support
 * reading and updating of superblocks.
 * Interface methods are:
 *   int load_super(struct md_rdev *dev, struct md_rdev *refdev, int minor_version)
 *      loads and validates a superblock on dev.
 *      if refdev != NULL, compare superblocks on both devices
 *    Return:
 *      0 - dev has a superblock that is compatible with refdev
 *      1 - dev has a superblock that is compatible and newer than refdev
 *          so dev should be used as the refdev in future
 *     -EINVAL superblock incompatible or invalid
 *     -othererror e.g. -EIO
 *
 *   int validate_super(struct mddev *mddev, struct md_rdev *dev)
 *      Verify that dev is acceptable into mddev.
 *       The first time, mddev->raid_disks will be 0, and data from
 *       dev should be merged in.  Subsequent calls check that dev
 *       is new enough.  Return 0 or -EINVAL
 *
 *   void sync_super(struct mddev *mddev, struct md_rdev *dev)
 *     Update the superblock for rdev with data in mddev
 *     This does not write to disc.
 *
 */

struct super_type  {
        char                *name;
        struct module       *owner;
        int                 (*load_super)(struct md_rdev *rdev,
                                          struct md_rdev *refdev,
                                          int minor_version);
        int                 (*validate_super)(struct mddev *mddev,
                                              struct md_rdev *rdev);
        void                (*sync_super)(struct mddev *mddev,
                                          struct md_rdev *rdev);
        unsigned long long  (*rdev_size_change)(struct md_rdev *rdev,
                                                sector_t num_sectors);
        int                 (*allow_new_offset)(struct md_rdev *rdev,
                                                unsigned long long new_offset);
};

/*
 * Check that the given mddev has no bitmap.
 *
 * This function is called from the run method of all personalities that do not
 * support bitmaps. It prints an error message and returns non-zero if mddev
 * has a bitmap. Otherwise, it returns 0.
 *
 */
int md_check_no_bitmap(struct mddev *mddev)
{
        if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
                return 0;
        pr_warn("%s: bitmaps are not supported for %s\n",
                mdname(mddev), mddev->pers->name);
        return 1;
}
EXPORT_SYMBOL(md_check_no_bitmap);

/*
 * load_super for 0.90.0
 */
static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
{
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        mdp_super_t *sb;
        int ret;
        bool spare_disk = true;

        /*
         * Calculate the position of the superblock (512byte sectors),
         * it's at the end of the disk.
         *
         * It also happens to be a multiple of 4Kb.
         */
        rdev->sb_start = calc_dev_sboffset(rdev);

        ret = read_disk_sb(rdev, MD_SB_BYTES);
        if (ret)
                return ret;

        ret = -EINVAL;

        bdevname(rdev->bdev, b);
        sb = page_address(rdev->sb_page);

        if (sb->md_magic != MD_SB_MAGIC) {
                pr_warn("md: invalid raid superblock magic on %s\n", b);
                goto abort;
        }

        if (sb->major_version != 0 ||
            sb->minor_version < 90 ||
            sb->minor_version > 91) {
                pr_warn("Bad version number %d.%d on %s\n",
                        sb->major_version, sb->minor_version, b);
                goto abort;
        }

        if (sb->raid_disks <= 0)
                goto abort;

        if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
                pr_warn("md: invalid superblock checksum on %s\n", b);
                goto abort;
        }

        rdev->preferred_minor = sb->md_minor;
        rdev->data_offset = 0;
        rdev->new_data_offset = 0;
        rdev->sb_size = MD_SB_BYTES;
        rdev->badblocks.shift = -1;

        if (sb->level == LEVEL_MULTIPATH)
                rdev->desc_nr = -1;
        else
                rdev->desc_nr = sb->this_disk.number;

        /* not spare disk, or LEVEL_MULTIPATH */
        if (sb->level == LEVEL_MULTIPATH ||
                (rdev->desc_nr >= 0 &&
                 rdev->desc_nr < MD_SB_DISKS &&
                 sb->disks[rdev->desc_nr].state &
                 ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE))))
                spare_disk = false;

        if (!refdev) {
                if (!spare_disk)
                        ret = 1;
                else
                        ret = 0;
        } else {
                __u64 ev1, ev2;
                mdp_super_t *refsb = page_address(refdev->sb_page);
                if (!md_uuid_equal(refsb, sb)) {
                        pr_warn("md: %s has different UUID to %s\n",
                                b, bdevname(refdev->bdev,b2));
                        goto abort;
                }
                if (!md_sb_equal(refsb, sb)) {
                        pr_warn("md: %s has same UUID but different superblock to %s\n",
                                b, bdevname(refdev->bdev, b2));
                        goto abort;
                }
                ev1 = md_event(sb);
                ev2 = md_event(refsb);

                if (!spare_disk && ev1 > ev2)
                        ret = 1;
                else
                        ret = 0;
        }
        rdev->sectors = rdev->sb_start;
        /* Limit to 4TB as metadata cannot record more than that.
         * (not needed for Linear and RAID0 as metadata doesn't
         * record this size)
         */
        if ((u64)rdev->sectors >= (2ULL << 32) && sb->level >= 1)
                rdev->sectors = (sector_t)(2ULL << 32) - 2;

        if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
                /* "this cannot possibly happen" ... */
                ret = -EINVAL;

 abort:
        return ret;
}

/*
 * validate_super for 0.90.0
 */
static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)
{
        mdp_disk_t *desc;
        mdp_super_t *sb = page_address(rdev->sb_page);
        __u64 ev1 = md_event(sb);

        rdev->raid_disk = -1;
        clear_bit(Faulty, &rdev->flags);
        clear_bit(In_sync, &rdev->flags);
        clear_bit(Bitmap_sync, &rdev->flags);
        clear_bit(WriteMostly, &rdev->flags);

        if (mddev->raid_disks == 0) {
                mddev->major_version = 0;
                mddev->minor_version = sb->minor_version;
                mddev->patch_version = sb->patch_version;
                mddev->external = 0;
                mddev->chunk_sectors = sb->chunk_size >> 9;
                mddev->ctime = sb->ctime;
                mddev->utime = sb->utime;
                mddev->level = sb->level;
                mddev->clevel[0] = 0;
                mddev->layout = sb->layout;
                mddev->raid_disks = sb->raid_disks;
                mddev->dev_sectors = ((sector_t)sb->size) * 2;
                mddev->events = ev1;
                mddev->bitmap_info.offset = 0;
                mddev->bitmap_info.space = 0;
                /* bitmap can use 60 K after the 4K superblocks */
                mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
                mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
                mddev->reshape_backwards = 0;

                if (mddev->minor_version >= 91) {
                        mddev->reshape_position = sb->reshape_position;
                        mddev->delta_disks = sb->delta_disks;
                        mddev->new_level = sb->new_level;
                        mddev->new_layout = sb->new_layout;
                        mddev->new_chunk_sectors = sb->new_chunk >> 9;
                        if (mddev->delta_disks < 0)
                                mddev->reshape_backwards = 1;
                } else {
                        mddev->reshape_position = MaxSector;
                        mddev->delta_disks = 0;
                        mddev->new_level = mddev->level;
                        mddev->new_layout = mddev->layout;
                        mddev->new_chunk_sectors = mddev->chunk_sectors;
                }
                if (mddev->level == 0)
                        mddev->layout = -1;

                if (sb->state & (1<<MD_SB_CLEAN))
                        mddev->recovery_cp = MaxSector;
                else {
                        if (sb->events_hi == sb->cp_events_hi &&
                                sb->events_lo == sb->cp_events_lo) {
                                mddev->recovery_cp = sb->recovery_cp;
                        } else
                                mddev->recovery_cp = 0;
                }

                memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
                memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
                memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
                memcpy(mddev->uuid+12,&sb->set_uuid3, 4);

                mddev->max_disks = MD_SB_DISKS;

                if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
                    mddev->bitmap_info.file == NULL) {
                        mddev->bitmap_info.offset =
                                mddev->bitmap_info.default_offset;
                        mddev->bitmap_info.space =
                                mddev->bitmap_info.default_space;
                }

        } else if (mddev->pers == NULL) {
                /* Insist on good event counter while assembling, except
                 * for spares (which don't need an event count) */
                ++ev1;
                if (sb->disks[rdev->desc_nr].state & (
                            (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
                        if (ev1 < mddev->events)
                                return -EINVAL;
        } else if (mddev->bitmap) {
                /* if adding to array with a bitmap, then we can accept an
                 * older device ... but not too old.
                 */
                if (ev1 < mddev->bitmap->events_cleared)
                        return 0;
                if (ev1 < mddev->events)
                        set_bit(Bitmap_sync, &rdev->flags);
        } else {
                if (ev1 < mddev->events)
                        /* just a hot-add of a new device, leave raid_disk at -1 */
                        return 0;
        }

        if (mddev->level != LEVEL_MULTIPATH) {
                desc = sb->disks + rdev->desc_nr;

                if (desc->state & (1<<MD_DISK_FAULTY))
                        set_bit(Faulty, &rdev->flags);
                else if (desc->state & (1<<MD_DISK_SYNC) /* &&
                            desc->raid_disk < mddev->raid_disks */) {
                        set_bit(In_sync, &rdev->flags);
                        rdev->raid_disk = desc->raid_disk;
                        rdev->saved_raid_disk = desc->raid_disk;
                } else if (desc->state & (1<<MD_DISK_ACTIVE)) {
                        /* active but not in sync implies recovery up to
                         * reshape position.  We don't know exactly where
                         * that is, so set to zero for now */
                        if (mddev->minor_version >= 91) {
                                rdev->recovery_offset = 0;
                                rdev->raid_disk = desc->raid_disk;
                        }
                }
                if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
                        set_bit(WriteMostly, &rdev->flags);
                if (desc->state & (1<<MD_DISK_FAILFAST))
                        set_bit(FailFast, &rdev->flags);
        } else /* MULTIPATH are always insync */
                set_bit(In_sync, &rdev->flags);
        return 0;
}

/*
 * sync_super for 0.90.0
 */
static void super_90_sync(struct mddev *mddev, struct md_rdev *rdev)
{
        mdp_super_t *sb;
        struct md_rdev *rdev2;
        int next_spare = mddev->raid_disks;

        /* make rdev->sb match mddev data..
         *
         * 1/ zero out disks
         * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
         * 3/ any empty disks < next_spare become removed
         *
         * disks[0] gets initialised to REMOVED because
         * we cannot be sure from other fields if it has
         * been initialised or not.
         */
        int i;
        int active=0, working=0,failed=0,spare=0,nr_disks=0;

        rdev->sb_size = MD_SB_BYTES;

        sb = page_address(rdev->sb_page);

        memset(sb, 0, sizeof(*sb));

        sb->md_magic = MD_SB_MAGIC;
        sb->major_version = mddev->major_version;
        sb->patch_version = mddev->patch_version;
        sb->gvalid_words  = 0; /* ignored */
        memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
        memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
        memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
        memcpy(&sb->set_uuid3, mddev->uuid+12,4);

        sb->ctime = clamp_t(time64_t, mddev->ctime, 0, U32_MAX);
        sb->level = mddev->level;
        sb->size = mddev->dev_sectors / 2;
        sb->raid_disks = mddev->raid_disks;
        sb->md_minor = mddev->md_minor;
        sb->not_persistent = 0;
        sb->utime = clamp_t(time64_t, mddev->utime, 0, U32_MAX);
        sb->state = 0;
        sb->events_hi = (mddev->events>>32);
        sb->events_lo = (u32)mddev->events;

        if (mddev->reshape_position == MaxSector)
                sb->minor_version = 90;
        else {
                sb->minor_version = 91;
                sb->reshape_position = mddev->reshape_position;
                sb->new_level = mddev->new_level;
                sb->delta_disks = mddev->delta_disks;
                sb->new_layout = mddev->new_layout;
                sb->new_chunk = mddev->new_chunk_sectors << 9;
        }
        mddev->minor_version = sb->minor_version;
        if (mddev->in_sync)
        {
                sb->recovery_cp = mddev->recovery_cp;
                sb->cp_events_hi = (mddev->events>>32);
                sb->cp_events_lo = (u32)mddev->events;
                if (mddev->recovery_cp == MaxSector)
                        sb->state = (1<< MD_SB_CLEAN);
        } else
                sb->recovery_cp = 0;

        sb->layout = mddev->layout;
        sb->chunk_size = mddev->chunk_sectors << 9;

        if (mddev->bitmap && mddev->bitmap_info.file == NULL)
                sb->state |= (1<<MD_SB_BITMAP_PRESENT);

        sb->disks[0].state = (1<<MD_DISK_REMOVED);
        rdev_for_each(rdev2, mddev) {
                mdp_disk_t *d;
                int desc_nr;
                int is_active = test_bit(In_sync, &rdev2->flags);

                if (rdev2->raid_disk >= 0 &&
                    sb->minor_version >= 91)
                        /* we have nowhere to store the recovery_offset,
                         * but if it is not below the reshape_position,
                         * we can piggy-back on that.
                         */
                        is_active = 1;
                if (rdev2->raid_disk < 0 ||
                    test_bit(Faulty, &rdev2->flags))
                        is_active = 0;
                if (is_active)
                        desc_nr = rdev2->raid_disk;
                else
                        desc_nr = next_spare++;
                rdev2->desc_nr = desc_nr;
                d = &sb->disks[rdev2->desc_nr];
                nr_disks++;
                d->number = rdev2->desc_nr;
                d->major = MAJOR(rdev2->bdev->bd_dev);
                d->minor = MINOR(rdev2->bdev->bd_dev);
                if (is_active)
                        d->raid_disk = rdev2->raid_disk;
                else
                        d->raid_disk = rdev2->desc_nr; /* compatibility */
                if (test_bit(Faulty, &rdev2->flags))
                        d->state = (1<<MD_DISK_FAULTY);
                else if (is_active) {
                        d->state = (1<<MD_DISK_ACTIVE);
                        if (test_bit(In_sync, &rdev2->flags))
                                d->state |= (1<<MD_DISK_SYNC);
                        active++;
                        working++;
                } else {
                        d->state = 0;
                        spare++;
                        working++;
                }
                if (test_bit(WriteMostly, &rdev2->flags))
                        d->state |= (1<<MD_DISK_WRITEMOSTLY);
                if (test_bit(FailFast, &rdev2->flags))
                        d->state |= (1<<MD_DISK_FAILFAST);
        }
        /* now set the "removed" and "faulty" bits on any missing devices */
        for (i=0 ; i < mddev->raid_disks ; i++) {
                mdp_disk_t *d = &sb->disks[i];
                if (d->state == 0 && d->number == 0) {
                        d->number = i;
                        d->raid_disk = i;
                        d->state = (1<<MD_DISK_REMOVED);
                        d->state |= (1<<MD_DISK_FAULTY);
                        failed++;
                }
        }
        sb->nr_disks = nr_disks;
        sb->active_disks = active;
        sb->working_disks = working;
        sb->failed_disks = failed;
        sb->spare_disks = spare;

        sb->this_disk = sb->disks[rdev->desc_nr];
        sb->sb_csum = calc_sb_csum(sb);
}

/*
 * rdev_size_change for 0.90.0
 */
static unsigned long long
super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
{
        if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
                return 0; /* component must fit device */
        if (rdev->mddev->bitmap_info.offset)
                return 0; /* can't move bitmap */
        rdev->sb_start = calc_dev_sboffset(rdev);
        if (!num_sectors || num_sectors > rdev->sb_start)
                num_sectors = rdev->sb_start;
        /* Limit to 4TB as metadata cannot record more than that.
         * 4TB == 2^32 KB, or 2*2^32 sectors.
         */
        if ((u64)num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
                num_sectors = (sector_t)(2ULL << 32) - 2;
        do {
                md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
                       rdev->sb_page);
        } while (md_super_wait(rdev->mddev) < 0);
        return num_sectors;
}

static int
super_90_allow_new_offset(struct md_rdev *rdev, unsigned long long new_offset)
{
        /* non-zero offset changes not possible with v0.90 */
        return new_offset == 0;
}

/*
 * version 1 superblock
 */

static __le32 calc_sb_1_csum(struct mdp_superblock_1 *sb)
{
        __le32 disk_csum;
        u32 csum;
        unsigned long long newcsum;
        int size = 256 + le32_to_cpu(sb->max_dev)*2;
        __le32 *isuper = (__le32*)sb;

        disk_csum = sb->sb_csum;
        sb->sb_csum = 0;
        newcsum = 0;
        for (; size >= 4; size -= 4)
                newcsum += le32_to_cpu(*isuper++);

        if (size == 2)
                newcsum += le16_to_cpu(*(__le16*) isuper);

        csum = (newcsum & 0xffffffff) + (newcsum >> 32);
        sb->sb_csum = disk_csum;
        return cpu_to_le32(csum);
}

static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
{
        struct mdp_superblock_1 *sb;
        int ret;
        sector_t sb_start;
        sector_t sectors;
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        int bmask;
        bool spare_disk = true;

        /*
         * Calculate the position of the superblock in 512byte sectors.
         * It is always aligned to a 4K boundary and
         * depeding on minor_version, it can be:
         * 0: At least 8K, but less than 12K, from end of device
         * 1: At start of device
         * 2: 4K from start of device.
         */
        switch(minor_version) {
        case 0:
                sb_start = i_size_read(rdev->bdev->bd_inode) >> 9;
                sb_start -= 8*2;
                sb_start &= ~(sector_t)(4*2-1);
                break;
        case 1:
                sb_start = 0;
                break;
        case 2:
                sb_start = 8;
                break;
        default:
                return -EINVAL;
        }
        rdev->sb_start = sb_start;

        /* superblock is rarely larger than 1K, but it can be larger,
         * and it is safe to read 4k, so we do that
         */
        ret = read_disk_sb(rdev, 4096);
        if (ret) return ret;

        sb = page_address(rdev->sb_page);

        if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
            sb->major_version != cpu_to_le32(1) ||
            le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
            le64_to_cpu(sb->super_offset) != rdev->sb_start ||
            (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
                return -EINVAL;

        if (calc_sb_1_csum(sb) != sb->sb_csum) {
                pr_warn("md: invalid superblock checksum on %s\n",
                        bdevname(rdev->bdev,b));
                return -EINVAL;
        }
        if (le64_to_cpu(sb->data_size) < 10) {
                pr_warn("md: data_size too small on %s\n",
                        bdevname(rdev->bdev,b));
                return -EINVAL;
        }
        if (sb->pad0 ||
            sb->pad3[0] ||
            memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1])))
                /* Some padding is non-zero, might be a new feature */
                return -EINVAL;

        rdev->preferred_minor = 0xffff;
        rdev->data_offset = le64_to_cpu(sb->data_offset);
        rdev->new_data_offset = rdev->data_offset;
        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE) &&
            (le32_to_cpu(sb->feature_map) & MD_FEATURE_NEW_OFFSET))
                rdev->new_data_offset += (s32)le32_to_cpu(sb->new_offset);
        atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));

        rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
        bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
        if (rdev->sb_size & bmask)
                rdev->sb_size = (rdev->sb_size | bmask) + 1;

        if (minor_version
            && rdev->data_offset < sb_start + (rdev->sb_size/512))
                return -EINVAL;
        if (minor_version
            && rdev->new_data_offset < sb_start + (rdev->sb_size/512))
                return -EINVAL;

        if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
                rdev->desc_nr = -1;
        else
                rdev->desc_nr = le32_to_cpu(sb->dev_number);

        if (!rdev->bb_page) {
                rdev->bb_page = alloc_page(GFP_KERNEL);
                if (!rdev->bb_page)
                        return -ENOMEM;
        }
        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BAD_BLOCKS) &&
            rdev->badblocks.count == 0) {
                /* need to load the bad block list.
                 * Currently we limit it to one page.
                 */
                s32 offset;
                sector_t bb_sector;
                __le64 *bbp;
                int i;
                int sectors = le16_to_cpu(sb->bblog_size);
                if (sectors > (PAGE_SIZE / 512))
                        return -EINVAL;
                offset = le32_to_cpu(sb->bblog_offset);
                if (offset == 0)
                        return -EINVAL;
                bb_sector = (long long)offset;
                if (!sync_page_io(rdev, bb_sector, sectors << 9,
                                  rdev->bb_page, REQ_OP_READ, 0, true))
                        return -EIO;
                bbp = (__le64 *)page_address(rdev->bb_page);
                rdev->badblocks.shift = sb->bblog_shift;
                for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {
                        u64 bb = le64_to_cpu(*bbp);
                        int count = bb & (0x3ff);
                        u64 sector = bb >> 10;
                        sector <<= sb->bblog_shift;
                        count <<= sb->bblog_shift;
                        if (bb + 1 == 0)
                                break;
                        if (badblocks_set(&rdev->badblocks, sector, count, 1))
                                return -EINVAL;
                }
        } else if (sb->bblog_offset != 0)
                rdev->badblocks.shift = 0;

        if ((le32_to_cpu(sb->feature_map) &
            (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS))) {
                rdev->ppl.offset = (__s16)le16_to_cpu(sb->ppl.offset);
                rdev->ppl.size = le16_to_cpu(sb->ppl.size);
                rdev->ppl.sector = rdev->sb_start + rdev->ppl.offset;
        }

        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RAID0_LAYOUT) &&
            sb->level != 0)
                return -EINVAL;

        /* not spare disk, or LEVEL_MULTIPATH */
        if (sb->level == cpu_to_le32(LEVEL_MULTIPATH) ||
                (rdev->desc_nr >= 0 &&
                rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
                (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
                 le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL)))
                spare_disk = false;

        if (!refdev) {
                if (!spare_disk)
                        ret = 1;
                else
                        ret = 0;
        } else {
                __u64 ev1, ev2;
                struct mdp_superblock_1 *refsb = page_address(refdev->sb_page);

                if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
                    sb->level != refsb->level ||
                    sb->layout != refsb->layout ||
                    sb->chunksize != refsb->chunksize) {
                        pr_warn("md: %s has strangely different superblock to %s\n",
                                bdevname(rdev->bdev,b),
                                bdevname(refdev->bdev,b2));
                        return -EINVAL;
                }
                ev1 = le64_to_cpu(sb->events);
                ev2 = le64_to_cpu(refsb->events);

                if (!spare_disk && ev1 > ev2)
                        ret = 1;
                else
                        ret = 0;
        }
        if (minor_version) {
                sectors = (i_size_read(rdev->bdev->bd_inode) >> 9);
                sectors -= rdev->data_offset;
        } else
                sectors = rdev->sb_start;
        if (sectors < le64_to_cpu(sb->data_size))
                return -EINVAL;
        rdev->sectors = le64_to_cpu(sb->data_size);
        return ret;
}

static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
{
        struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
        __u64 ev1 = le64_to_cpu(sb->events);

        rdev->raid_disk = -1;
        clear_bit(Faulty, &rdev->flags);
        clear_bit(In_sync, &rdev->flags);
        clear_bit(Bitmap_sync, &rdev->flags);
        clear_bit(WriteMostly, &rdev->flags);

        if (mddev->raid_disks == 0) {
                mddev->major_version = 1;
                mddev->patch_version = 0;
                mddev->external = 0;
                mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
                mddev->ctime = le64_to_cpu(sb->ctime);
                mddev->utime = le64_to_cpu(sb->utime);
                mddev->level = le32_to_cpu(sb->level);
                mddev->clevel[0] = 0;
                mddev->layout = le32_to_cpu(sb->layout);
                mddev->raid_disks = le32_to_cpu(sb->raid_disks);
                mddev->dev_sectors = le64_to_cpu(sb->size);
                mddev->events = ev1;
                mddev->bitmap_info.offset = 0;
                mddev->bitmap_info.space = 0;
                /* Default location for bitmap is 1K after superblock
                 * using 3K - total of 4K
                 */
                mddev->bitmap_info.default_offset = 1024 >> 9;
                mddev->bitmap_info.default_space = (4096-1024) >> 9;
                mddev->reshape_backwards = 0;

                mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
                memcpy(mddev->uuid, sb->set_uuid, 16);

                mddev->max_disks =  (4096-256)/2;

                if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
                    mddev->bitmap_info.file == NULL) {
                        mddev->bitmap_info.offset =
                                (__s32)le32_to_cpu(sb->bitmap_offset);
                        /* Metadata doesn't record how much space is available.
                         * For 1.0, we assume we can use up to the superblock
                         * if before, else to 4K beyond superblock.
                         * For others, assume no change is possible.
                         */
                        if (mddev->minor_version > 0)
                                mddev->bitmap_info.space = 0;
                        else if (mddev->bitmap_info.offset > 0)
                                mddev->bitmap_info.space =
                                        8 - mddev->bitmap_info.offset;
                        else
                                mddev->bitmap_info.space =
                                        -mddev->bitmap_info.offset;
                }

                if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
                        mddev->reshape_position = le64_to_cpu(sb->reshape_position);
                        mddev->delta_disks = le32_to_cpu(sb->delta_disks);
                        mddev->new_level = le32_to_cpu(sb->new_level);
                        mddev->new_layout = le32_to_cpu(sb->new_layout);
                        mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
                        if (mddev->delta_disks < 0 ||
                            (mddev->delta_disks == 0 &&
                             (le32_to_cpu(sb->feature_map)
                              & MD_FEATURE_RESHAPE_BACKWARDS)))
                                mddev->reshape_backwards = 1;
                } else {
                        mddev->reshape_position = MaxSector;
                        mddev->delta_disks = 0;
                        mddev->new_level = mddev->level;
                        mddev->new_layout = mddev->layout;
                        mddev->new_chunk_sectors = mddev->chunk_sectors;
                }

                if (mddev->level == 0 &&
                    !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RAID0_LAYOUT))
                        mddev->layout = -1;

                if (le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)
                        set_bit(MD_HAS_JOURNAL, &mddev->flags);

                if (le32_to_cpu(sb->feature_map) &
                    (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS)) {
                        if (le32_to_cpu(sb->feature_map) &
                            (MD_FEATURE_BITMAP_OFFSET | MD_FEATURE_JOURNAL))
                                return -EINVAL;
                        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_PPL) &&
                            (le32_to_cpu(sb->feature_map) &
                                            MD_FEATURE_MULTIPLE_PPLS))
                                return -EINVAL;
                        set_bit(MD_HAS_PPL, &mddev->flags);
                }
        } else if (mddev->pers == NULL) {
                /* Insist of good event counter while assembling, except for
                 * spares (which don't need an event count) */
                ++ev1;
                if (rdev->desc_nr >= 0 &&
                    rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
                    (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
                     le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL))
                        if (ev1 < mddev->events)
                                return -EINVAL;
        } else if (mddev->bitmap) {
                /* If adding to array with a bitmap, then we can accept an
                 * older device, but not too old.
                 */
                if (ev1 < mddev->bitmap->events_cleared)
                        return 0;
                if (ev1 < mddev->events)
                        set_bit(Bitmap_sync, &rdev->flags);
        } else {
                if (ev1 < mddev->events)
                        /* just a hot-add of a new device, leave raid_disk at -1 */
                        return 0;
        }
        if (mddev->level != LEVEL_MULTIPATH) {
                int role;
                if (rdev->desc_nr < 0 ||
                    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
                        role = MD_DISK_ROLE_SPARE;
                        rdev->desc_nr = -1;
                } else
                        role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
                switch(role) {
                case MD_DISK_ROLE_SPARE: /* spare */
                        break;
                case MD_DISK_ROLE_FAULTY: /* faulty */
                        set_bit(Faulty, &rdev->flags);
                        break;
                case MD_DISK_ROLE_JOURNAL: /* journal device */
                        if (!(le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)) {
                                /* journal device without journal feature */
                                pr_warn("md: journal device provided without journal feature, ignoring the device\n");
                                return -EINVAL;
                        }
                        set_bit(Journal, &rdev->flags);
                        rdev->journal_tail = le64_to_cpu(sb->journal_tail);
                        rdev->raid_disk = 0;
                        break;
                default:
                        rdev->saved_raid_disk = role;
                        if ((le32_to_cpu(sb->feature_map) &
                             MD_FEATURE_RECOVERY_OFFSET)) {
                                rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
                                if (!(le32_to_cpu(sb->feature_map) &
                                      MD_FEATURE_RECOVERY_BITMAP))
                                        rdev->saved_raid_disk = -1;
                        } else {
                                /*
                                 * If the array is FROZEN, then the device can't
                                 * be in_sync with rest of array.
                                 */
                                if (!test_bit(MD_RECOVERY_FROZEN,
                                              &mddev->recovery))
                                        set_bit(In_sync, &rdev->flags);
                        }
                        rdev->raid_disk = role;
                        break;
                }
                if (sb->devflags & WriteMostly1)
                        set_bit(WriteMostly, &rdev->flags);
                if (sb->devflags & FailFast1)
                        set_bit(FailFast, &rdev->flags);
                if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
                        set_bit(Replacement, &rdev->flags);
        } else /* MULTIPATH are always insync */
                set_bit(In_sync, &rdev->flags);

        return 0;
}

static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
{
        struct mdp_superblock_1 *sb;
        struct md_rdev *rdev2;
        int max_dev, i;
        /* make rdev->sb match mddev and rdev data. */

        sb = page_address(rdev->sb_page);

        sb->feature_map = 0;
        sb->pad0 = 0;
        sb->recovery_offset = cpu_to_le64(0);
        memset(sb->pad3, 0, sizeof(sb->pad3));

        sb->utime = cpu_to_le64((__u64)mddev->utime);
        sb->events = cpu_to_le64(mddev->events);
        if (mddev->in_sync)
                sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
        else if (test_bit(MD_JOURNAL_CLEAN, &mddev->flags))
                sb->resync_offset = cpu_to_le64(MaxSector);
        else
                sb->resync_offset = cpu_to_le64(0);

        sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));

        sb->raid_disks = cpu_to_le32(mddev->raid_disks);
        sb->size = cpu_to_le64(mddev->dev_sectors);
        sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
        sb->level = cpu_to_le32(mddev->level);
        sb->layout = cpu_to_le32(mddev->layout);
        if (test_bit(FailFast, &rdev->flags))
                sb->devflags |= FailFast1;
        else
                sb->devflags &= ~FailFast1;

        if (test_bit(WriteMostly, &rdev->flags))
                sb->devflags |= WriteMostly1;
        else
                sb->devflags &= ~WriteMostly1;
        sb->data_offset = cpu_to_le64(rdev->data_offset);
        sb->data_size = cpu_to_le64(rdev->sectors);

        if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
                sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
        }

        if (rdev->raid_disk >= 0 && !test_bit(Journal, &rdev->flags) &&
            !test_bit(In_sync, &rdev->flags)) {
                sb->feature_map |=
                        cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
                sb->recovery_offset =
                        cpu_to_le64(rdev->recovery_offset);
                if (rdev->saved_raid_disk >= 0 && mddev->bitmap)
                        sb->feature_map |=
                                cpu_to_le32(MD_FEATURE_RECOVERY_BITMAP);
        }
        /* Note: recovery_offset and journal_tail share space  */
        if (test_bit(Journal, &rdev->flags))
                sb->journal_tail = cpu_to_le64(rdev->journal_tail);
        if (test_bit(Replacement, &rdev->flags))
                sb->feature_map |=
                        cpu_to_le32(MD_FEATURE_REPLACEMENT);

        if (mddev->reshape_position != MaxSector) {
                sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
                sb->reshape_position = cpu_to_le64(mddev->reshape_position);
                sb->new_layout = cpu_to_le32(mddev->new_layout);
                sb->delta_disks = cpu_to_le32(mddev->delta_disks);
                sb->new_level = cpu_to_le32(mddev->new_level);
                sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
                if (mddev->delta_disks == 0 &&
                    mddev->reshape_backwards)
                        sb->feature_map
                                |= cpu_to_le32(MD_FEATURE_RESHAPE_BACKWARDS);
                if (rdev->new_data_offset != rdev->data_offset) {
                        sb->feature_map
                                |= cpu_to_le32(MD_FEATURE_NEW_OFFSET);
                        sb->new_offset = cpu_to_le32((__u32)(rdev->new_data_offset
                                                             - rdev->data_offset));
                }
        }

        if (mddev_is_clustered(mddev))
                sb->feature_map |= cpu_to_le32(MD_FEATURE_CLUSTERED);

        if (rdev->badblocks.count == 0)
                /* Nothing to do for bad blocks*/ ;
        else if (sb->bblog_offset == 0)
                /* Cannot record bad blocks on this device */
                md_error(mddev, rdev);
        else {
                struct badblocks *bb = &rdev->badblocks;
                __le64 *bbp = (__le64 *)page_address(rdev->bb_page);
                u64 *p = bb->page;
                sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
                if (bb->changed) {
                        unsigned seq;

retry:
                        seq = read_seqbegin(&bb->lock);

                        memset(bbp, 0xff, PAGE_SIZE);

                        for (i = 0 ; i < bb->count ; i++) {
                                u64 internal_bb = p[i];
                                u64 store_bb = ((BB_OFFSET(internal_bb) << 10)
                                                | BB_LEN(internal_bb));
                                bbp[i] = cpu_to_le64(store_bb);
                        }
                        bb->changed = 0;
                        if (read_seqretry(&bb->lock, seq))
                                goto retry;

                        bb->sector = (rdev->sb_start +
                                      (int)le32_to_cpu(sb->bblog_offset));
                        bb->size = le16_to_cpu(sb->bblog_size);
                }
        }

        max_dev = 0;
        rdev_for_each(rdev2, mddev)
                if (rdev2->desc_nr+1 > max_dev)
                        max_dev = rdev2->desc_nr+1;

        if (max_dev > le32_to_cpu(sb->max_dev)) {
                int bmask;
                sb->max_dev = cpu_to_le32(max_dev);
                rdev->sb_size = max_dev * 2 + 256;
                bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
                if (rdev->sb_size & bmask)
                        rdev->sb_size = (rdev->sb_size | bmask) + 1;
        } else
                max_dev = le32_to_cpu(sb->max_dev);

        for (i=0; i<max_dev;i++)
                sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_SPARE);

        if (test_bit(MD_HAS_JOURNAL, &mddev->flags))
                sb->feature_map |= cpu_to_le32(MD_FEATURE_JOURNAL);

        if (test_bit(MD_HAS_PPL, &mddev->flags)) {
                if (test_bit(MD_HAS_MULTIPLE_PPLS, &mddev->flags))
                        sb->feature_map |=
                            cpu_to_le32(MD_FEATURE_MULTIPLE_PPLS);
                else
                        sb->feature_map |= cpu_to_le32(MD_FEATURE_PPL);
                sb->ppl.offset = cpu_to_le16(rdev->ppl.offset);
                sb->ppl.size = cpu_to_le16(rdev->ppl.size);
        }

        rdev_for_each(rdev2, mddev) {
                i = rdev2->desc_nr;
                if (test_bit(Faulty, &rdev2->flags))
                        sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_FAULTY);
                else if (test_bit(In_sync, &rdev2->flags))
                        sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
                else if (test_bit(Journal, &rdev2->flags))
                        sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_JOURNAL);
                else if (rdev2->raid_disk >= 0)
                        sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
                else
                        sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_SPARE);
        }

        sb->sb_csum = calc_sb_1_csum(sb);
}

static sector_t super_1_choose_bm_space(sector_t dev_size)
{
        sector_t bm_space;

        /* if the device is bigger than 8Gig, save 64k for bitmap
         * usage, if bigger than 200Gig, save 128k
         */
        if (dev_size < 64*2)
                bm_space = 0;
        else if (dev_size - 64*2 >= 200*1024*1024*2)
                bm_space = 128*2;
        else if (dev_size - 4*2 > 8*1024*1024*2)
                bm_space = 64*2;
        else
                bm_space = 4*2;
        return bm_space;
}

static unsigned long long
super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
{
        struct mdp_superblock_1 *sb;
        sector_t max_sectors;
        if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
                return 0; /* component must fit device */
        if (rdev->data_offset != rdev->new_data_offset)
                return 0; /* too confusing */
        if (rdev->sb_start < rdev->data_offset) {
                /* minor versions 1 and 2; superblock before data */
                max_sectors = i_size_read(rdev->bdev->bd_inode) >> 9;
                max_sectors -= rdev->data_offset;
                if (!num_sectors || num_sectors > max_sectors)
                        num_sectors = max_sectors;
        } else if (rdev->mddev->bitmap_info.offset) {
                /* minor version 0 with bitmap we can't move */
                return 0;
        } else {
                /* minor version 0; superblock after data */
                sector_t sb_start, bm_space;
                sector_t dev_size = i_size_read(rdev->bdev->bd_inode) >> 9;

                /* 8K is for superblock */
                sb_start = dev_size - 8*2;
                sb_start &= ~(sector_t)(4*2 - 1);

                bm_space = super_1_choose_bm_space(dev_size);

                /* Space that can be used to store date needs to decrease
                 * superblock bitmap space and bad block space(4K)
                 */
                max_sectors = sb_start - bm_space - 4*2;

                if (!num_sectors || num_sectors > max_sectors)
                        num_sectors = max_sectors;
        }
        sb = page_address(rdev->sb_page);
        sb->data_size = cpu_to_le64(num_sectors);
        sb->super_offset = cpu_to_le64(rdev->sb_start);
        sb->sb_csum = calc_sb_1_csum(sb);
        do {
                md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
                               rdev->sb_page);
        } while (md_super_wait(rdev->mddev) < 0);
        return num_sectors;

}

static int
super_1_allow_new_offset(struct md_rdev *rdev,
                         unsigned long long new_offset)
{
        /* All necessary checks on new >= old have been done */
        struct bitmap *bitmap;
        if (new_offset >= rdev->data_offset)
                return 1;

        /* with 1.0 metadata, there is no metadata to tread on
         * so we can always move back */
        if (rdev->mddev->minor_version == 0)
                return 1;

        /* otherwise we must be sure not to step on
         * any metadata, so stay:
         * 36K beyond start of superblock
         * beyond end of badblocks
         * beyond write-intent bitmap
         */
        if (rdev->sb_start + (32+4)*2 > new_offset)
                return 0;
        bitmap = rdev->mddev->bitmap;
        if (bitmap && !rdev->mddev->bitmap_info.file &&
            rdev->sb_start + rdev->mddev->bitmap_info.offset +
            bitmap->storage.file_pages * (PAGE_SIZE>>9) > new_offset)
                return 0;
        if (rdev->badblocks.sector + rdev->badblocks.size > new_offset)
                return 0;

        return 1;
}

static struct super_type super_types[] = {
        [0] = {
                .name   = "0.90.0",
                .owner  = THIS_MODULE,
                .load_super         = super_90_load,
                .validate_super     = super_90_validate,
                .sync_super         = super_90_sync,
                .rdev_size_change   = super_90_rdev_size_change,
                .allow_new_offset   = super_90_allow_new_offset,
        },
        [1] = {
                .name   = "md-1",
                .owner  = THIS_MODULE,
                .load_super         = super_1_load,
                .validate_super     = super_1_validate,
                .sync_super         = super_1_sync,
                .rdev_size_change   = super_1_rdev_size_change,
                .allow_new_offset   = super_1_allow_new_offset,
        },
};

static void sync_super(struct mddev *mddev, struct md_rdev *rdev)
{
        if (mddev->sync_super) {
                mddev->sync_super(mddev, rdev);
                return;
        }

        BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));

        super_types[mddev->major_version].sync_super(mddev, rdev);
}

static int match_mddev_units(struct mddev *mddev1, struct mddev *mddev2)
{
        struct md_rdev *rdev, *rdev2;

        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev1) {
                if (test_bit(Faulty, &rdev->flags) ||
                    test_bit(Journal, &rdev->flags) ||
                    rdev->raid_disk == -1)
                        continue;
                rdev_for_each_rcu(rdev2, mddev2) {
                        if (test_bit(Faulty, &rdev2->flags) ||
                            test_bit(Journal, &rdev2->flags) ||
                            rdev2->raid_disk == -1)
                                continue;
                        if (rdev->bdev->bd_disk == rdev2->bdev->bd_disk) {
                                rcu_read_unlock();
                                return 1;
                        }
                }
        }
        rcu_read_unlock();
        return 0;
}

static LIST_HEAD(pending_raid_disks);

/*
 * Try to register data integrity profile for an mddev
 *
 * This is called when an array is started and after a disk has been kicked
 * from the array. It only succeeds if all working and active component devices
 * are integrity capable with matching profiles.
 */
int md_integrity_register(struct mddev *mddev)
{
        struct md_rdev *rdev, *reference = NULL;

        if (list_empty(&mddev->disks))
                return 0; /* nothing to do */
        if (!mddev->gendisk || blk_get_integrity(mddev->gendisk))
                return 0; /* shouldn't register, or already is */
        rdev_for_each(rdev, mddev) {
                /* skip spares and non-functional disks */
                if (test_bit(Faulty, &rdev->flags))
                        continue;
                if (rdev->raid_disk < 0)
                        continue;
                if (!reference) {
                        /* Use the first rdev as the reference */
                        reference = rdev;
                        continue;
                }
                /* does this rdev's profile match the reference profile? */
                if (blk_integrity_compare(reference->bdev->bd_disk,
                                rdev->bdev->bd_disk) < 0)
                        return -EINVAL;
        }
        if (!reference || !bdev_get_integrity(reference->bdev))
                return 0;
        /*
         * All component devices are integrity capable and have matching
         * profiles, register the common profile for the md device.
         */
        blk_integrity_register(mddev->gendisk,
                               bdev_get_integrity(reference->bdev));

        pr_debug("md: data integrity enabled on %s\n", mdname(mddev));
        if (bioset_integrity_create(&mddev->bio_set, BIO_POOL_SIZE)) {
                pr_err("md: failed to create integrity pool for %s\n",
                       mdname(mddev));
                return -EINVAL;
        }
        return 0;
}
EXPORT_SYMBOL(md_integrity_register);

/*
 * Attempt to add an rdev, but only if it is consistent with the current
 * integrity profile
 */
int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev)
{
        struct blk_integrity *bi_mddev;
        char name[BDEVNAME_SIZE];

        if (!mddev->gendisk)
                return 0;

        bi_mddev = blk_get_integrity(mddev->gendisk);

        if (!bi_mddev) /* nothing to do */
                return 0;

        if (blk_integrity_compare(mddev->gendisk, rdev->bdev->bd_disk) != 0) {
                pr_err("%s: incompatible integrity profile for %s\n",
                       mdname(mddev), bdevname(rdev->bdev, name));
                return -ENXIO;
        }

        return 0;
}
EXPORT_SYMBOL(md_integrity_add_rdev);

static bool rdev_read_only(struct md_rdev *rdev)
{
        return bdev_read_only(rdev->bdev) ||
                (rdev->meta_bdev && bdev_read_only(rdev->meta_bdev));
}

static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
{
        char b[BDEVNAME_SIZE];
        int err;

        /* prevent duplicates */
        if (find_rdev(mddev, rdev->bdev->bd_dev))
                return -EEXIST;

        if (rdev_read_only(rdev) && mddev->pers)
                return -EROFS;

        /* make sure rdev->sectors exceeds mddev->dev_sectors */
        if (!test_bit(Journal, &rdev->flags) &&
            rdev->sectors &&
            (mddev->dev_sectors == 0 || rdev->sectors < mddev->dev_sectors)) {
                if (mddev->pers) {
                        /* Cannot change size, so fail
                         * If mddev->level <= 0, then we don't care
                         * about aligning sizes (e.g. linear)
                         */
                        if (mddev->level > 0)
                                return -ENOSPC;
                } else
                        mddev->dev_sectors = rdev->sectors;
        }

        /* Verify rdev->desc_nr is unique.
         * If it is -1, assign a free number, else
         * check number is not in use
         */
        rcu_read_lock();
        if (rdev->desc_nr < 0) {
                int choice = 0;
                if (mddev->pers)
                        choice = mddev->raid_disks;
                while (md_find_rdev_nr_rcu(mddev, choice))
                        choice++;
                rdev->desc_nr = choice;
        } else {
                if (md_find_rdev_nr_rcu(mddev, rdev->desc_nr)) {
                        rcu_read_unlock();
                        return -EBUSY;
                }
        }
        rcu_read_unlock();
        if (!test_bit(Journal, &rdev->flags) &&
            mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
                pr_warn("md: %s: array is limited to %d devices\n",
                        mdname(mddev), mddev->max_disks);
                return -EBUSY;
        }
        bdevname(rdev->bdev,b);
        strreplace(b, '/', '!');

        rdev->mddev = mddev;
        pr_debug("md: bind<%s>\n", b);

        if (mddev->raid_disks)
                mddev_create_serial_pool(mddev, rdev, false);

        if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
                goto fail;

        /* failure here is OK */
        err = sysfs_create_link(&rdev->kobj, bdev_kobj(rdev->bdev), "block");
        rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
        rdev->sysfs_unack_badblocks =
                sysfs_get_dirent_safe(rdev->kobj.sd, "unacknowledged_bad_blocks");
        rdev->sysfs_badblocks =
                sysfs_get_dirent_safe(rdev->kobj.sd, "bad_blocks");

        list_add_rcu(&rdev->same_set, &mddev->disks);
        bd_link_disk_holder(rdev->bdev, mddev->gendisk);

        /* May as well allow recovery to be retried once */
        mddev->recovery_disabled++;

        return 0;

 fail:
        pr_warn("md: failed to register dev-%s for %s\n",
                b, mdname(mddev));
        return err;
}

static void rdev_delayed_delete(struct work_struct *ws)
{
        struct md_rdev *rdev = container_of(ws, struct md_rdev, del_work);
        kobject_del(&rdev->kobj);
        kobject_put(&rdev->kobj);
}

static void unbind_rdev_from_array(struct md_rdev *rdev)
{
        char b[BDEVNAME_SIZE];

        bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
        list_del_rcu(&rdev->same_set);
        pr_debug("md: unbind<%s>\n", bdevname(rdev->bdev,b));
        mddev_destroy_serial_pool(rdev->mddev, rdev, false);
        rdev->mddev = NULL;
        sysfs_remove_link(&rdev->kobj, "block");
        sysfs_put(rdev->sysfs_state);
        sysfs_put(rdev->sysfs_unack_badblocks);
        sysfs_put(rdev->sysfs_badblocks);
        rdev->sysfs_state = NULL;
        rdev->sysfs_unack_badblocks = NULL;
        rdev->sysfs_badblocks = NULL;
        rdev->badblocks.count = 0;
        /* We need to delay this, otherwise we can deadlock when
         * writing to 'remove' to "dev/state".  We also need
         * to delay it due to rcu usage.
         */
        synchronize_rcu();
        INIT_WORK(&rdev->del_work, rdev_delayed_delete);
        kobject_get(&rdev->kobj);
        queue_work(md_rdev_misc_wq, &rdev->del_work);
}

/*
 * prevent the device from being mounted, repartitioned or
 * otherwise reused by a RAID array (or any other kernel
 * subsystem), by bd_claiming the device.
 */
static int lock_rdev(struct md_rdev *rdev, dev_t dev, int shared)
{
        int err = 0;
        struct block_device *bdev;

        bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
                                 shared ? (struct md_rdev *)lock_rdev : rdev);
        if (IS_ERR(bdev)) {
                pr_warn("md: could not open device unknown-block(%u,%u).\n",
                        MAJOR(dev), MINOR(dev));
                return PTR_ERR(bdev);
        }
        rdev->bdev = bdev;
        return err;
}

static void unlock_rdev(struct md_rdev *rdev)
{
        struct block_device *bdev = rdev->bdev;
        rdev->bdev = NULL;
        blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
}

void md_autodetect_dev(dev_t dev);

static void export_rdev(struct md_rdev *rdev)
{
        char b[BDEVNAME_SIZE];

        pr_debug("md: export_rdev(%s)\n", bdevname(rdev->bdev,b));
        md_rdev_clear(rdev);
#ifndef MODULE
        if (test_bit(AutoDetected, &rdev->flags))
                md_autodetect_dev(rdev->bdev->bd_dev);
#endif
        unlock_rdev(rdev);
        kobject_put(&rdev->kobj);
}

void md_kick_rdev_from_array(struct md_rdev *rdev)
{
        unbind_rdev_from_array(rdev);
        export_rdev(rdev);
}
EXPORT_SYMBOL_GPL(md_kick_rdev_from_array);

static void export_array(struct mddev *mddev)
{
        struct md_rdev *rdev;

        while (!list_empty(&mddev->disks)) {
                rdev = list_first_entry(&mddev->disks, struct md_rdev,
                                        same_set);
                md_kick_rdev_from_array(rdev);
        }
        mddev->raid_disks = 0;
        mddev->major_version = 0;
}

static bool set_in_sync(struct mddev *mddev)
{
        lockdep_assert_held(&mddev->lock);
        if (!mddev->in_sync) {
                mddev->sync_checkers++;
                spin_unlock(&mddev->lock);
                percpu_ref_switch_to_atomic_sync(&mddev->writes_pending);
                spin_lock(&mddev->lock);
                if (!mddev->in_sync &&
                    percpu_ref_is_zero(&mddev->writes_pending)) {
                        mddev->in_sync = 1;
                        /*
                         * Ensure ->in_sync is visible before we clear
                         * ->sync_checkers.
                         */
                        smp_mb();
                        set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
                        sysfs_notify_dirent_safe(mddev->sysfs_state);
                }
                if (--mddev->sync_checkers == 0)
                        percpu_ref_switch_to_percpu(&mddev->writes_pending);
        }
        if (mddev->safemode == 1)
                mddev->safemode = 0;
        return mddev->in_sync;
}

static void sync_sbs(struct mddev *mddev, int nospares)
{
        /* Update each superblock (in-memory image), but
         * if we are allowed to, skip spares which already
         * have the right event counter, or have one earlier
         * (which would mean they aren't being marked as dirty
         * with the rest of the array)
         */
        struct md_rdev *rdev;
        rdev_for_each(rdev, mddev) {
                if (rdev->sb_events == mddev->events ||
                    (nospares &&
                     rdev->raid_disk < 0 &&
                     rdev->sb_events+1 == mddev->events)) {
                        /* Don't update this superblock */
                        rdev->sb_loaded = 2;
                } else {
                        sync_super(mddev, rdev);
                        rdev->sb_loaded = 1;
                }
        }
}

static bool does_sb_need_changing(struct mddev *mddev)
{
        struct md_rdev *rdev;
        struct mdp_superblock_1 *sb;
        int role;

        /* Find a good rdev */
        rdev_for_each(rdev, mddev)
                if ((rdev->raid_disk >= 0) && !test_bit(Faulty, &rdev->flags))
                        break;

        /* No good device found. */
        if (!rdev)
                return false;

        sb = page_address(rdev->sb_page);
        /* Check if a device has become faulty or a spare become active */
        rdev_for_each(rdev, mddev) {
                role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
                /* Device activated? */
                if (role == 0xffff && rdev->raid_disk >=0 &&
                    !test_bit(Faulty, &rdev->flags))
                        return true;
                /* Device turned faulty? */
                if (test_bit(Faulty, &rdev->flags) && (role < 0xfffd))
                        return true;
        }

        /* Check if any mddev parameters have changed */
        if ((mddev->dev_sectors != le64_to_cpu(sb->size)) ||
            (mddev->reshape_position != le64_to_cpu(sb->reshape_position)) ||
            (mddev->layout != le32_to_cpu(sb->layout)) ||
            (mddev->raid_disks != le32_to_cpu(sb->raid_disks)) ||
            (mddev->chunk_sectors != le32_to_cpu(sb->chunksize)))
                return true;

        return false;
}

void md_update_sb(struct mddev *mddev, int force_change)
{
        struct md_rdev *rdev;
        int sync_req;
        int nospares = 0;
        int any_badblocks_changed = 0;
        int ret = -1;

        if (mddev->ro) {
                if (force_change)
                        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
                return;
        }

repeat:
        if (mddev_is_clustered(mddev)) {
                if (test_and_clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags))
                        force_change = 1;
                if (test_and_clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags))
                        nospares = 1;
                ret = md_cluster_ops->metadata_update_start(mddev);
                /* Has someone else has updated the sb */
                if (!does_sb_need_changing(mddev)) {
                        if (ret == 0)
                                md_cluster_ops->metadata_update_cancel(mddev);
                        bit_clear_unless(&mddev->sb_flags, BIT(MD_SB_CHANGE_PENDING),
                                                         BIT(MD_SB_CHANGE_DEVS) |
                                                         BIT(MD_SB_CHANGE_CLEAN));
                        return;
                }
        }

        /*
         * First make sure individual recovery_offsets are correct
         * curr_resync_completed can only be used during recovery.
         * During reshape/resync it might use array-addresses rather
         * that device addresses.
         */
        rdev_for_each(rdev, mddev) {
                if (rdev->raid_disk >= 0 &&
                    mddev->delta_disks >= 0 &&
                    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
                    test_bit(MD_RECOVERY_RECOVER, &mddev->recovery) &&
                    !test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
                    !test_bit(Journal, &rdev->flags) &&
                    !test_bit(In_sync, &rdev->flags) &&
                    mddev->curr_resync_completed > rdev->recovery_offset)
                                rdev->recovery_offset = mddev->curr_resync_completed;

        }
        if (!mddev->persistent) {
                clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
                clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
                if (!mddev->external) {
                        clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
                        rdev_for_each(rdev, mddev) {
                                if (rdev->badblocks.changed) {
                                        rdev->badblocks.changed = 0;
                                        ack_all_badblocks(&rdev->badblocks);
                                        md_error(mddev, rdev);
                                }
                                clear_bit(Blocked, &rdev->flags);
                                clear_bit(BlockedBadBlocks, &rdev->flags);
                                wake_up(&rdev->blocked_wait);
                        }
                }
                wake_up(&mddev->sb_wait);
                return;
        }

        spin_lock(&mddev->lock);

        mddev->utime = ktime_get_real_seconds();

        if (test_and_clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags))
                force_change = 1;
        if (test_and_clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags))
                /* just a clean<-> dirty transition, possibly leave spares alone,
                 * though if events isn't the right even/odd, we will have to do
                 * spares after all
                 */
                nospares = 1;
        if (force_change)
                nospares = 0;
        if (mddev->degraded)
                /* If the array is degraded, then skipping spares is both
                 * dangerous and fairly pointless.
                 * Dangerous because a device that was removed from the array
                 * might have a event_count that still looks up-to-date,
                 * so it can be re-added without a resync.
                 * Pointless because if there are any spares to skip,
                 * then a recovery will happen and soon that array won't
                 * be degraded any more and the spare can go back to sleep then.
                 */
                nospares = 0;

        sync_req = mddev->in_sync;

        /* If this is just a dirty<->clean transition, and the array is clean
         * and 'events' is odd, we can roll back to the previous clean state */
        if (nospares
            && (mddev->in_sync && mddev->recovery_cp == MaxSector)
            && mddev->can_decrease_events
            && mddev->events != 1) {
                mddev->events--;
                mddev->can_decrease_events = 0;
        } else {
                /* otherwise we have to go forward and ... */
                mddev->events ++;
                mddev->can_decrease_events = nospares;
        }

        /*
         * This 64-bit counter should never wrap.
         * Either we are in around ~1 trillion A.C., assuming
         * 1 reboot per second, or we have a bug...
         */
        WARN_ON(mddev->events == 0);

        rdev_for_each(rdev, mddev) {
                if (rdev->badblocks.changed)
                        any_badblocks_changed++;
                if (test_bit(Faulty, &rdev->flags))
                        set_bit(FaultRecorded, &rdev->flags);
        }

        sync_sbs(mddev, nospares);
        spin_unlock(&mddev->lock);

        pr_debug("md: updating %s RAID superblock on device (in sync %d)\n",
                 mdname(mddev), mddev->in_sync);

        if (mddev->queue)
                blk_add_trace_msg(mddev->queue, "md md_update_sb");
rewrite:
        md_bitmap_update_sb(mddev->bitmap);
        rdev_for_each(rdev, mddev) {
                char b[BDEVNAME_SIZE];

                if (rdev->sb_loaded != 1)
                        continue; /* no noise on spare devices */

                if (!test_bit(Faulty, &rdev->flags)) {
                        md_super_write(mddev,rdev,
                                       rdev->sb_start, rdev->sb_size,
                                       rdev->sb_page);
                        pr_debug("md: (write) %s's sb offset: %llu\n",
                                 bdevname(rdev->bdev, b),
                                 (unsigned long long)rdev->sb_start);
                        rdev->sb_events = mddev->events;
                        if (rdev->badblocks.size) {
                                md_super_write(mddev, rdev,
                                               rdev->badblocks.sector,
                                               rdev->badblocks.size << 9,
                                               rdev->bb_page);
                                rdev->badblocks.size = 0;
                        }

                } else
                        pr_debug("md: %s (skipping faulty)\n",
                                 bdevname(rdev->bdev, b));

                if (mddev->level == LEVEL_MULTIPATH)
                        /* only need to write one superblock... */
                        break;
        }
        if (md_super_wait(mddev) < 0)
                goto rewrite;
        /* if there was a failure, MD_SB_CHANGE_DEVS was set, and we re-write super */

        if (mddev_is_clustered(mddev) && ret == 0)
                md_cluster_ops->metadata_update_finish(mddev);

        if (mddev->in_sync != sync_req ||
            !bit_clear_unless(&mddev->sb_flags, BIT(MD_SB_CHANGE_PENDING),
                               BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_CLEAN)))
                /* have to write it out again */
                goto repeat;
        wake_up(&mddev->sb_wait);
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                sysfs_notify_dirent_safe(mddev->sysfs_completed);

        rdev_for_each(rdev, mddev) {
                if (test_and_clear_bit(FaultRecorded, &rdev->flags))
                        clear_bit(Blocked, &rdev->flags);

                if (any_badblocks_changed)
                        ack_all_badblocks(&rdev->badblocks);
                clear_bit(BlockedBadBlocks, &rdev->flags);
                wake_up(&rdev->blocked_wait);
        }
}
EXPORT_SYMBOL(md_update_sb);

static int add_bound_rdev(struct md_rdev *rdev)
{
        struct mddev *mddev = rdev->mddev;
        int err = 0;
        bool add_journal = test_bit(Journal, &rdev->flags);

        if (!mddev->pers->hot_remove_disk || add_journal) {
                /* If there is hot_add_disk but no hot_remove_disk
                 * then added disks for geometry changes,
                 * and should be added immediately.
                 */
                super_types[mddev->major_version].
                        validate_super(mddev, rdev);
                if (add_journal)
                        mddev_suspend(mddev);
                err = mddev->pers->hot_add_disk(mddev, rdev);
                if (add_journal)
                        mddev_resume(mddev);
                if (err) {
                        md_kick_rdev_from_array(rdev);
                        return err;
                }
        }
        sysfs_notify_dirent_safe(rdev->sysfs_state);

        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
        if (mddev->degraded)
                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_new_event(mddev);
        md_wakeup_thread(mddev->thread);
        return 0;
}

/* words written to sysfs files may, or may not, be \n terminated.
 * We want to accept with case. For this we use cmd_match.
 */
static int cmd_match(const char *cmd, const char *str)
{
        /* See if cmd, written into a sysfs file, matches
         * str.  They must either be the same, or cmd can
         * have a trailing newline
         */
        while (*cmd && *str && *cmd == *str) {
                cmd++;
                str++;
        }
        if (*cmd == '\n')
                cmd++;
        if (*str || *cmd)
                return 0;
        return 1;
}

struct rdev_sysfs_entry {
        struct attribute attr;
        ssize_t (*show)(struct md_rdev *, char *);
        ssize_t (*store)(struct md_rdev *, const char *, size_t);
};

static ssize_t
state_show(struct md_rdev *rdev, char *page)
{
        char *sep = ",";
        size_t len = 0;
        unsigned long flags = READ_ONCE(rdev->flags);

        if (test_bit(Faulty, &flags) ||
            (!test_bit(ExternalBbl, &flags) &&
            rdev->badblocks.unacked_exist))
                len += sprintf(page+len, "faulty%s", sep);
        if (test_bit(In_sync, &flags))
                len += sprintf(page+len, "in_sync%s", sep);
        if (test_bit(Journal, &flags))
                len += sprintf(page+len, "journal%s", sep);
        if (test_bit(WriteMostly, &flags))
                len += sprintf(page+len, "write_mostly%s", sep);
        if (test_bit(Blocked, &flags) ||
            (rdev->badblocks.unacked_exist
             && !test_bit(Faulty, &flags)))
                len += sprintf(page+len, "blocked%s", sep);
        if (!test_bit(Faulty, &flags) &&
            !test_bit(Journal, &flags) &&
            !test_bit(In_sync, &flags))
                len += sprintf(page+len, "spare%s", sep);
        if (test_bit(WriteErrorSeen, &flags))
                len += sprintf(page+len, "write_error%s", sep);
        if (test_bit(WantReplacement, &flags))
                len += sprintf(page+len, "want_replacement%s", sep);
        if (test_bit(Replacement, &flags))
                len += sprintf(page+len, "replacement%s", sep);
        if (test_bit(ExternalBbl, &flags))
                len += sprintf(page+len, "external_bbl%s", sep);
        if (test_bit(FailFast, &flags))
                len += sprintf(page+len, "failfast%s", sep);

        if (len)
                len -= strlen(sep);

        return len+sprintf(page+len, "\n");
}

static ssize_t
state_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        /* can write
         *  faulty  - simulates an error
         *  remove  - disconnects the device
         *  writemostly - sets write_mostly
         *  -writemostly - clears write_mostly
         *  blocked - sets the Blocked flags
         *  -blocked - clears the Blocked and possibly simulates an error
         *  insync - sets Insync providing device isn't active
         *  -insync - clear Insync for a device with a slot assigned,
         *            so that it gets rebuilt based on bitmap
         *  write_error - sets WriteErrorSeen
         *  -write_error - clears WriteErrorSeen
         *  {,-}failfast - set/clear FailFast
         */
        int err = -EINVAL;
        if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
                md_error(rdev->mddev, rdev);
                if (test_bit(Faulty, &rdev->flags))
                        err = 0;
                else
                        err = -EBUSY;
        } else if (cmd_match(buf, "remove")) {
                if (rdev->mddev->pers) {
                        clear_bit(Blocked, &rdev->flags);
                        remove_and_add_spares(rdev->mddev, rdev);
                }
                if (rdev->raid_disk >= 0)
                        err = -EBUSY;
                else {
                        struct mddev *mddev = rdev->mddev;
                        err = 0;
                        if (mddev_is_clustered(mddev))
                                err = md_cluster_ops->remove_disk(mddev, rdev);

                        if (err == 0) {
                                md_kick_rdev_from_array(rdev);
                                if (mddev->pers) {
                                        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
                                        md_wakeup_thread(mddev->thread);
                                }
                                md_new_event(mddev);
                        }
                }
        } else if (cmd_match(buf, "writemostly")) {
                set_bit(WriteMostly, &rdev->flags);
                mddev_create_serial_pool(rdev->mddev, rdev, false);
                err = 0;
        } else if (cmd_match(buf, "-writemostly")) {
                mddev_destroy_serial_pool(rdev->mddev, rdev, false);
                clear_bit(WriteMostly, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "blocked")) {
                set_bit(Blocked, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "-blocked")) {
                if (!test_bit(Faulty, &rdev->flags) &&
                    !test_bit(ExternalBbl, &rdev->flags) &&
                    rdev->badblocks.unacked_exist) {
                        /* metadata handler doesn't understand badblocks,
                         * so we need to fail the device
                         */
                        md_error(rdev->mddev, rdev);
                }
                clear_bit(Blocked, &rdev->flags);
                clear_bit(BlockedBadBlocks, &rdev->flags);
                wake_up(&rdev->blocked_wait);
                set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                md_wakeup_thread(rdev->mddev->thread);

                err = 0;
        } else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
                set_bit(In_sync, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "failfast")) {
                set_bit(FailFast, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "-failfast")) {
                clear_bit(FailFast, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "-insync") && rdev->raid_disk >= 0 &&
                   !test_bit(Journal, &rdev->flags)) {
                if (rdev->mddev->pers == NULL) {
                        clear_bit(In_sync, &rdev->flags);
                        rdev->saved_raid_disk = rdev->raid_disk;
                        rdev->raid_disk = -1;
                        err = 0;
                }
        } else if (cmd_match(buf, "write_error")) {
                set_bit(WriteErrorSeen, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "-write_error")) {
                clear_bit(WriteErrorSeen, &rdev->flags);
                err = 0;
        } else if (cmd_match(buf, "want_replacement")) {
                /* Any non-spare device that is not a replacement can
                 * become want_replacement at any time, but we then need to
                 * check if recovery is needed.
                 */
                if (rdev->raid_disk >= 0 &&
                    !test_bit(Journal, &rdev->flags) &&
                    !test_bit(Replacement, &rdev->flags))
                        set_bit(WantReplacement, &rdev->flags);
                set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                md_wakeup_thread(rdev->mddev->thread);
                err = 0;
        } else if (cmd_match(buf, "-want_replacement")) {
                /* Clearing 'want_replacement' is always allowed.
                 * Once replacements starts it is too late though.
                 */
                err = 0;
                clear_bit(WantReplacement, &rdev->flags);
        } else if (cmd_match(buf, "replacement")) {
                /* Can only set a device as a replacement when array has not
                 * yet been started.  Once running, replacement is automatic
                 * from spares, or by assigning 'slot'.
                 */
                if (rdev->mddev->pers)
                        err = -EBUSY;
                else {
                        set_bit(Replacement, &rdev->flags);
                        err = 0;
                }
        } else if (cmd_match(buf, "-replacement")) {
                /* Similarly, can only clear Replacement before start */
                if (rdev->mddev->pers)
                        err = -EBUSY;
                else {
                        clear_bit(Replacement, &rdev->flags);
                        err = 0;
                }
        } else if (cmd_match(buf, "re-add")) {
                if (!rdev->mddev->pers)
                        err = -EINVAL;
                else if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
                                rdev->saved_raid_disk >= 0) {
                        /* clear_bit is performed _after_ all the devices
                         * have their local Faulty bit cleared. If any writes
                         * happen in the meantime in the local node, they
                         * will land in the local bitmap, which will be synced
                         * by this node eventually
                         */
                        if (!mddev_is_clustered(rdev->mddev) ||
                            (err = md_cluster_ops->gather_bitmaps(rdev)) == 0) {
                                clear_bit(Faulty, &rdev->flags);
                                err = add_bound_rdev(rdev);
                        }
                } else
                        err = -EBUSY;
        } else if (cmd_match(buf, "external_bbl") && (rdev->mddev->external)) {
                set_bit(ExternalBbl, &rdev->flags);
                rdev->badblocks.shift = 0;
                err = 0;
        } else if (cmd_match(buf, "-external_bbl") && (rdev->mddev->external)) {
                clear_bit(ExternalBbl, &rdev->flags);
                err = 0;
        }
        if (!err)
                sysfs_notify_dirent_safe(rdev->sysfs_state);
        return err ? err : len;
}
static struct rdev_sysfs_entry rdev_state =
__ATTR_PREALLOC(state, S_IRUGO|S_IWUSR, state_show, state_store);

static ssize_t
errors_show(struct md_rdev *rdev, char *page)
{
        return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
}

static ssize_t
errors_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        unsigned int n;
        int rv;

        rv = kstrtouint(buf, 10, &n);
        if (rv < 0)
                return rv;
        atomic_set(&rdev->corrected_errors, n);
        return len;
}
static struct rdev_sysfs_entry rdev_errors =
__ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);

static ssize_t
slot_show(struct md_rdev *rdev, char *page)
{
        if (test_bit(Journal, &rdev->flags))
                return sprintf(page, "journal\n");
        else if (rdev->raid_disk < 0)
                return sprintf(page, "none\n");
        else
                return sprintf(page, "%d\n", rdev->raid_disk);
}

static ssize_t
slot_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        int slot;
        int err;

        if (test_bit(Journal, &rdev->flags))
                return -EBUSY;
        if (strncmp(buf, "none", 4)==0)
                slot = -1;
        else {
                err = kstrtouint(buf, 10, (unsigned int *)&slot);
                if (err < 0)
                        return err;
        }
        if (rdev->mddev->pers && slot == -1) {
                /* Setting 'slot' on an active array requires also
                 * updating the 'rd%d' link, and communicating
                 * with the personality with ->hot_*_disk.
                 * For now we only support removing
                 * failed/spare devices.  This normally happens automatically,
                 * but not when the metadata is externally managed.
                 */
                if (rdev->raid_disk == -1)
                        return -EEXIST;
                /* personality does all needed checks */
                if (rdev->mddev->pers->hot_remove_disk == NULL)
                        return -EINVAL;
                clear_bit(Blocked, &rdev->flags);
                remove_and_add_spares(rdev->mddev, rdev);
                if (rdev->raid_disk >= 0)
                        return -EBUSY;
                set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
                md_wakeup_thread(rdev->mddev->thread);
        } else if (rdev->mddev->pers) {
                /* Activating a spare .. or possibly reactivating
                 * if we ever get bitmaps working here.
                 */
                int err;

                if (rdev->raid_disk != -1)
                        return -EBUSY;

                if (test_bit(MD_RECOVERY_RUNNING, &rdev->mddev->recovery))
                        return -EBUSY;

                if (rdev->mddev->pers->hot_add_disk == NULL)
                        return -EINVAL;

                if (slot >= rdev->mddev->raid_disks &&
                    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
                        return -ENOSPC;

                rdev->raid_disk = slot;
                if (test_bit(In_sync, &rdev->flags))
                        rdev->saved_raid_disk = slot;
                else
                        rdev->saved_raid_disk = -1;
                clear_bit(In_sync, &rdev->flags);
                clear_bit(Bitmap_sync, &rdev->flags);
                err = rdev->mddev->pers->hot_add_disk(rdev->mddev, rdev);
                if (err) {
                        rdev->raid_disk = -1;
                        return err;
                } else
                        sysfs_notify_dirent_safe(rdev->sysfs_state);
                /* failure here is OK */;
                sysfs_link_rdev(rdev->mddev, rdev);
                /* don't wakeup anyone, leave that to userspace. */
        } else {
                if (slot >= rdev->mddev->raid_disks &&
                    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
                        return -ENOSPC;
                rdev->raid_disk = slot;
                /* assume it is working */
                clear_bit(Faulty, &rdev->flags);
                clear_bit(WriteMostly, &rdev->flags);
                set_bit(In_sync, &rdev->flags);
                sysfs_notify_dirent_safe(rdev->sysfs_state);
        }
        return len;
}

static struct rdev_sysfs_entry rdev_slot =
__ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);

static ssize_t
offset_show(struct md_rdev *rdev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
}

static ssize_t
offset_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        unsigned long long offset;
        if (kstrtoull(buf, 10, &offset) < 0)
                return -EINVAL;
        if (rdev->mddev->pers && rdev->raid_disk >= 0)
                return -EBUSY;
        if (rdev->sectors && rdev->mddev->external)
                /* Must set offset before size, so overlap checks
                 * can be sane */
                return -EBUSY;
        rdev->data_offset = offset;
        rdev->new_data_offset = offset;
        return len;
}

static struct rdev_sysfs_entry rdev_offset =
__ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);

static ssize_t new_offset_show(struct md_rdev *rdev, char *page)
{
        return sprintf(page, "%llu\n",
                       (unsigned long long)rdev->new_data_offset);
}

static ssize_t new_offset_store(struct md_rdev *rdev,
                                const char *buf, size_t len)
{
        unsigned long long new_offset;
        struct mddev *mddev = rdev->mddev;

        if (kstrtoull(buf, 10, &new_offset) < 0)
                return -EINVAL;

        if (mddev->sync_thread ||
            test_bit(MD_RECOVERY_RUNNING,&mddev->recovery))
                return -EBUSY;
        if (new_offset == rdev->data_offset)
                /* reset is always permitted */
                ;
        else if (new_offset > rdev->data_offset) {
                /* must not push array size beyond rdev_sectors */
                if (new_offset - rdev->data_offset
                    + mddev->dev_sectors > rdev->sectors)
                                return -E2BIG;
        }
        /* Metadata worries about other space details. */

        /* decreasing the offset is inconsistent with a backwards
         * reshape.
         */
        if (new_offset < rdev->data_offset &&
            mddev->reshape_backwards)
                return -EINVAL;
        /* Increasing offset is inconsistent with forwards
         * reshape.  reshape_direction should be set to
         * 'backwards' first.
         */
        if (new_offset > rdev->data_offset &&
            !mddev->reshape_backwards)
                return -EINVAL;

        if (mddev->pers && mddev->persistent &&
            !super_types[mddev->major_version]
            .allow_new_offset(rdev, new_offset))
                return -E2BIG;
        rdev->new_data_offset = new_offset;
        if (new_offset > rdev->data_offset)
                mddev->reshape_backwards = 1;
        else if (new_offset < rdev->data_offset)
                mddev->reshape_backwards = 0;

        return len;
}
static struct rdev_sysfs_entry rdev_new_offset =
__ATTR(new_offset, S_IRUGO|S_IWUSR, new_offset_show, new_offset_store);

static ssize_t
rdev_size_show(struct md_rdev *rdev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
}

static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
{
        /* check if two start/length pairs overlap */
        if (s1+l1 <= s2)
                return 0;
        if (s2+l2 <= s1)
                return 0;
        return 1;
}

static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
{
        unsigned long long blocks;
        sector_t new;

        if (kstrtoull(buf, 10, &blocks) < 0)
                return -EINVAL;

        if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
                return -EINVAL; /* sector conversion overflow */

        new = blocks * 2;
        if (new != blocks * 2)
                return -EINVAL; /* unsigned long long to sector_t overflow */

        *sectors = new;
        return 0;
}

static ssize_t
rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        struct mddev *my_mddev = rdev->mddev;
        sector_t oldsectors = rdev->sectors;
        sector_t sectors;

        if (test_bit(Journal, &rdev->flags))
                return -EBUSY;
        if (strict_blocks_to_sectors(buf, &sectors) < 0)
                return -EINVAL;
        if (rdev->data_offset != rdev->new_data_offset)
                return -EINVAL; /* too confusing */
        if (my_mddev->pers && rdev->raid_disk >= 0) {
                if (my_mddev->persistent) {
                        sectors = super_types[my_mddev->major_version].
                                rdev_size_change(rdev, sectors);
                        if (!sectors)
                                return -EBUSY;
                } else if (!sectors)
                        sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
                                rdev->data_offset;
                if (!my_mddev->pers->resize)
                        /* Cannot change size for RAID0 or Linear etc */
                        return -EINVAL;
        }
        if (sectors < my_mddev->dev_sectors)
                return -EINVAL; /* component must fit device */

        rdev->sectors = sectors;
        if (sectors > oldsectors && my_mddev->external) {
                /* Need to check that all other rdevs with the same
                 * ->bdev do not overlap.  'rcu' is sufficient to walk
                 * the rdev lists safely.
                 * This check does not provide a hard guarantee, it
                 * just helps avoid dangerous mistakes.
                 */
                struct mddev *mddev;
                int overlap = 0;
                struct list_head *tmp;

                rcu_read_lock();
                for_each_mddev(mddev, tmp) {
                        struct md_rdev *rdev2;

                        rdev_for_each(rdev2, mddev)
                                if (rdev->bdev == rdev2->bdev &&
                                    rdev != rdev2 &&
                                    overlaps(rdev->data_offset, rdev->sectors,
                                             rdev2->data_offset,
                                             rdev2->sectors)) {
                                        overlap = 1;
                                        break;
                                }
                        if (overlap) {
                                mddev_put(mddev);
                                break;
                        }
                }
                rcu_read_unlock();
                if (overlap) {
                        /* Someone else could have slipped in a size
                         * change here, but doing so is just silly.
                         * We put oldsectors back because we *know* it is
                         * safe, and trust userspace not to race with
                         * itself
                         */
                        rdev->sectors = oldsectors;
                        return -EBUSY;
                }
        }
        return len;
}

static struct rdev_sysfs_entry rdev_size =
__ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);

static ssize_t recovery_start_show(struct md_rdev *rdev, char *page)
{
        unsigned long long recovery_start = rdev->recovery_offset;

        if (test_bit(In_sync, &rdev->flags) ||
            recovery_start == MaxSector)
                return sprintf(page, "none\n");

        return sprintf(page, "%llu\n", recovery_start);
}

static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        unsigned long long recovery_start;

        if (cmd_match(buf, "none"))
                recovery_start = MaxSector;
        else if (kstrtoull(buf, 10, &recovery_start))
                return -EINVAL;

        if (rdev->mddev->pers &&
            rdev->raid_disk >= 0)
                return -EBUSY;

        rdev->recovery_offset = recovery_start;
        if (recovery_start == MaxSector)
                set_bit(In_sync, &rdev->flags);
        else
                clear_bit(In_sync, &rdev->flags);
        return len;
}

static struct rdev_sysfs_entry rdev_recovery_start =
__ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);

/* sysfs access to bad-blocks list.
 * We present two files.
 * 'bad-blocks' lists sector numbers and lengths of ranges that
 *    are recorded as bad.  The list is truncated to fit within
 *    the one-page limit of sysfs.
 *    Writing "sector length" to this file adds an acknowledged
 *    bad block list.
 * 'unacknowledged-bad-blocks' lists bad blocks that have not yet
 *    been acknowledged.  Writing to this file adds bad blocks
 *    without acknowledging them.  This is largely for testing.
 */
static ssize_t bb_show(struct md_rdev *rdev, char *page)
{
        return badblocks_show(&rdev->badblocks, page, 0);
}
static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)
{
        int rv = badblocks_store(&rdev->badblocks, page, len, 0);
        /* Maybe that ack was all we needed */
        if (test_and_clear_bit(BlockedBadBlocks, &rdev->flags))
                wake_up(&rdev->blocked_wait);
        return rv;
}
static struct rdev_sysfs_entry rdev_bad_blocks =
__ATTR(bad_blocks, S_IRUGO|S_IWUSR, bb_show, bb_store);

static ssize_t ubb_show(struct md_rdev *rdev, char *page)
{
        return badblocks_show(&rdev->badblocks, page, 1);
}
static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
{
        return badblocks_store(&rdev->badblocks, page, len, 1);
}
static struct rdev_sysfs_entry rdev_unack_bad_blocks =
__ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);

static ssize_t
ppl_sector_show(struct md_rdev *rdev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)rdev->ppl.sector);
}

static ssize_t
ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        unsigned long long sector;

        if (kstrtoull(buf, 10, &sector) < 0)
                return -EINVAL;
        if (sector != (sector_t)sector)
                return -EINVAL;

        if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
            rdev->raid_disk >= 0)
                return -EBUSY;

        if (rdev->mddev->persistent) {
                if (rdev->mddev->major_version == 0)
                        return -EINVAL;
                if ((sector > rdev->sb_start &&
                     sector - rdev->sb_start > S16_MAX) ||
                    (sector < rdev->sb_start &&
                     rdev->sb_start - sector > -S16_MIN))
                        return -EINVAL;
                rdev->ppl.offset = sector - rdev->sb_start;
        } else if (!rdev->mddev->external) {
                return -EBUSY;
        }
        rdev->ppl.sector = sector;
        return len;
}

static struct rdev_sysfs_entry rdev_ppl_sector =
__ATTR(ppl_sector, S_IRUGO|S_IWUSR, ppl_sector_show, ppl_sector_store);

static ssize_t
ppl_size_show(struct md_rdev *rdev, char *page)
{
        return sprintf(page, "%u\n", rdev->ppl.size);
}

static ssize_t
ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len)
{
        unsigned int size;

        if (kstrtouint(buf, 10, &size) < 0)
                return -EINVAL;

        if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
            rdev->raid_disk >= 0)
                return -EBUSY;

        if (rdev->mddev->persistent) {
                if (rdev->mddev->major_version == 0)
                        return -EINVAL;
                if (size > U16_MAX)
                        return -EINVAL;
        } else if (!rdev->mddev->external) {
                return -EBUSY;
        }
        rdev->ppl.size = size;
        return len;
}

static struct rdev_sysfs_entry rdev_ppl_size =
__ATTR(ppl_size, S_IRUGO|S_IWUSR, ppl_size_show, ppl_size_store);

static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_errors.attr,
        &rdev_slot.attr,
        &rdev_offset.attr,
        &rdev_new_offset.attr,
        &rdev_size.attr,
        &rdev_recovery_start.attr,
        &rdev_bad_blocks.attr,
        &rdev_unack_bad_blocks.attr,
        &rdev_ppl_sector.attr,
        &rdev_ppl_size.attr,
        NULL,
};
static ssize_t
rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
        struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
        struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);

        if (!entry->show)
                return -EIO;
        if (!rdev->mddev)
                return -ENODEV;
        return entry->show(rdev, page);
}

static ssize_t
rdev_attr_store(struct kobject *kobj, struct attribute *attr,
              const char *page, size_t length)
{
        struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
        struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
        ssize_t rv;
        struct mddev *mddev = rdev->mddev;

        if (!entry->store)
                return -EIO;
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        rv = mddev ? mddev_lock(mddev) : -ENODEV;
        if (!rv) {
                if (rdev->mddev == NULL)
                        rv = -ENODEV;
                else
                        rv = entry->store(rdev, page, length);
                mddev_unlock(mddev);
        }
        return rv;
}

static void rdev_free(struct kobject *ko)
{
        struct md_rdev *rdev = container_of(ko, struct md_rdev, kobj);
        kfree(rdev);
}
static const struct sysfs_ops rdev_sysfs_ops = {
        .show           = rdev_attr_show,
        .store          = rdev_attr_store,
};
static struct kobj_type rdev_ktype = {
        .release        = rdev_free,
        .sysfs_ops      = &rdev_sysfs_ops,
        .default_attrs  = rdev_default_attrs,
};

int md_rdev_init(struct md_rdev *rdev)
{
        rdev->desc_nr = -1;
        rdev->saved_raid_disk = -1;
        rdev->raid_disk = -1;
        rdev->flags = 0;
        rdev->data_offset = 0;
        rdev->new_data_offset = 0;
        rdev->sb_events = 0;
        rdev->last_read_error = 0;
        rdev->sb_loaded = 0;
        rdev->bb_page = NULL;
        atomic_set(&rdev->nr_pending, 0);
        atomic_set(&rdev->read_errors, 0);
        atomic_set(&rdev->corrected_errors, 0);

        INIT_LIST_HEAD(&rdev->same_set);
        init_waitqueue_head(&rdev->blocked_wait);

        /* Add space to store bad block list.
         * This reserves the space even on arrays where it cannot
         * be used - I wonder if that matters
         */
        return badblocks_init(&rdev->badblocks, 0);
}
EXPORT_SYMBOL_GPL(md_rdev_init);
/*
 * Import a device. If 'super_format' >= 0, then sanity check the superblock
 *
 * mark the device faulty if:
 *
 *   - the device is nonexistent (zero size)
 *   - the device has no valid superblock
 *
 * a faulty rdev _never_ has rdev->sb set.
 */
static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
{
        char b[BDEVNAME_SIZE];
        int err;
        struct md_rdev *rdev;
        sector_t size;

        rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
        if (!rdev)
                return ERR_PTR(-ENOMEM);

        err = md_rdev_init(rdev);
        if (err)
                goto abort_free;
        err = alloc_disk_sb(rdev);
        if (err)
                goto abort_free;

        err = lock_rdev(rdev, newdev, super_format == -2);
        if (err)
                goto abort_free;

        kobject_init(&rdev->kobj, &rdev_ktype);

        size = i_size_read(rdev->bdev->bd_inode) >> BLOCK_SIZE_BITS;
        if (!size) {
                pr_warn("md: %s has zero or unknown size, marking faulty!\n",
                        bdevname(rdev->bdev,b));
                err = -EINVAL;
                goto abort_free;
        }

        if (super_format >= 0) {
                err = super_types[super_format].
                        load_super(rdev, NULL, super_minor);
                if (err == -EINVAL) {
                        pr_warn("md: %s does not have a valid v%d.%d superblock, not importing!\n",
                                bdevname(rdev->bdev,b),
                                super_format, super_minor);
                        goto abort_free;
                }
                if (err < 0) {
                        pr_warn("md: could not read %s's sb, not importing!\n",
                                bdevname(rdev->bdev,b));
                        goto abort_free;
                }
        }

        return rdev;

abort_free:
        if (rdev->bdev)
                unlock_rdev(rdev);
        md_rdev_clear(rdev);
        kfree(rdev);
        return ERR_PTR(err);
}

/*
 * Check a full RAID array for plausibility
 */

static int analyze_sbs(struct mddev *mddev)
{
        int i;
        struct md_rdev *rdev, *freshest, *tmp;
        char b[BDEVNAME_SIZE];

        freshest = NULL;
        rdev_for_each_safe(rdev, tmp, mddev)
                switch (super_types[mddev->major_version].
                        load_super(rdev, freshest, mddev->minor_version)) {
                case 1:
                        freshest = rdev;
                        break;
                case 0:
                        break;
                default:
                        pr_warn("md: fatal superblock inconsistency in %s -- removing from array\n",
                                bdevname(rdev->bdev,b));
                        md_kick_rdev_from_array(rdev);
                }

        /* Cannot find a valid fresh disk */
        if (!freshest) {
                pr_warn("md: cannot find a valid disk\n");
                return -EINVAL;
        }

        super_types[mddev->major_version].
                validate_super(mddev, freshest);

        i = 0;
        rdev_for_each_safe(rdev, tmp, mddev) {
                if (mddev->max_disks &&
                    (rdev->desc_nr >= mddev->max_disks ||
                     i > mddev->max_disks)) {
                        pr_warn("md: %s: %s: only %d devices permitted\n",
                                mdname(mddev), bdevname(rdev->bdev, b),
                                mddev->max_disks);
                        md_kick_rdev_from_array(rdev);
                        continue;
                }
                if (rdev != freshest) {
                        if (super_types[mddev->major_version].
                            validate_super(mddev, rdev)) {
                                pr_warn("md: kicking non-fresh %s from array!\n",
                                        bdevname(rdev->bdev,b));
                                md_kick_rdev_from_array(rdev);
                                continue;
                        }
                }
                if (mddev->level == LEVEL_MULTIPATH) {
                        rdev->desc_nr = i++;
                        rdev->raid_disk = rdev->desc_nr;
                        set_bit(In_sync, &rdev->flags);
                } else if (rdev->raid_disk >=
                            (mddev->raid_disks - min(0, mddev->delta_disks)) &&
                           !test_bit(Journal, &rdev->flags)) {
                        rdev->raid_disk = -1;
                        clear_bit(In_sync, &rdev->flags);
                }
        }

        return 0;
}

/* Read a fixed-point number.
 * Numbers in sysfs attributes should be in "standard" units where
 * possible, so time should be in seconds.
 * However we internally use a a much smaller unit such as
 * milliseconds or jiffies.
 * This function takes a decimal number with a possible fractional
 * component, and produces an integer which is the result of
 * multiplying that number by 10^'scale'.
 * all without any floating-point arithmetic.
 */
int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
{
        unsigned long result = 0;
        long decimals = -1;
        while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
                if (*cp == '.')
                        decimals = 0;
                else if (decimals < scale) {
                        unsigned int value;
                        value = *cp - '0';
                        result = result * 10 + value;
                        if (decimals >= 0)
                                decimals++;
                }
                cp++;
        }
        if (*cp == '\n')
                cp++;
        if (*cp)
                return -EINVAL;
        if (decimals < 0)
                decimals = 0;
        *res = result * int_pow(10, scale - decimals);
        return 0;
}

static ssize_t
safe_delay_show(struct mddev *mddev, char *page)
{
        int msec = (mddev->safemode_delay*1000)/HZ;
        return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
}
static ssize_t
safe_delay_store(struct mddev *mddev, const char *cbuf, size_t len)
{
        unsigned long msec;

        if (mddev_is_clustered(mddev)) {
                pr_warn("md: Safemode is disabled for clustered mode\n");
                return -EINVAL;
        }

        if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
                return -EINVAL;
        if (msec == 0)
                mddev->safemode_delay = 0;
        else {
                unsigned long old_delay = mddev->safemode_delay;
                unsigned long new_delay = (msec*HZ)/1000;

                if (new_delay == 0)
                        new_delay = 1;
                mddev->safemode_delay = new_delay;
                if (new_delay < old_delay || old_delay == 0)
                        mod_timer(&mddev->safemode_timer, jiffies+1);
        }
        return len;
}
static struct md_sysfs_entry md_safe_delay =
__ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);

static ssize_t
level_show(struct mddev *mddev, char *page)
{
        struct md_personality *p;
        int ret;
        spin_lock(&mddev->lock);
        p = mddev->pers;
        if (p)
                ret = sprintf(page, "%s\n", p->name);
        else if (mddev->clevel[0])
                ret = sprintf(page, "%s\n", mddev->clevel);
        else if (mddev->level != LEVEL_NONE)
                ret = sprintf(page, "%d\n", mddev->level);
        else
                ret = 0;
        spin_unlock(&mddev->lock);
        return ret;
}

static ssize_t
level_store(struct mddev *mddev, const char *buf, size_t len)
{
        char clevel[16];
        ssize_t rv;
        size_t slen = len;
        struct md_personality *pers, *oldpers;
        long level;
        void *priv, *oldpriv;
        struct md_rdev *rdev;

        if (slen == 0 || slen >= sizeof(clevel))
                return -EINVAL;

        rv = mddev_lock(mddev);
        if (rv)
                return rv;

        if (mddev->pers == NULL) {
                strncpy(mddev->clevel, buf, slen);
                if (mddev->clevel[slen-1] == '\n')
                        slen--;
                mddev->clevel[slen] = 0;
                mddev->level = LEVEL_NONE;
                rv = len;
                goto out_unlock;
        }
        rv = -EROFS;
        if (mddev->ro)
                goto out_unlock;

        /* request to change the personality.  Need to ensure:
         *  - array is not engaged in resync/recovery/reshape
         *  - old personality can be suspended
         *  - new personality will access other array.
         */

        rv = -EBUSY;
        if (mddev->sync_thread ||
            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
            mddev->reshape_position != MaxSector ||
            mddev->sysfs_active)
                goto out_unlock;

        rv = -EINVAL;
        if (!mddev->pers->quiesce) {
                pr_warn("md: %s: %s does not support online personality change\n",
                        mdname(mddev), mddev->pers->name);
                goto out_unlock;
        }

        /* Now find the new personality */
        strncpy(clevel, buf, slen);
        if (clevel[slen-1] == '\n')
                slen--;
        clevel[slen] = 0;
        if (kstrtol(clevel, 10, &level))
                level = LEVEL_NONE;

        if (request_module("md-%s", clevel) != 0)
                request_module("md-level-%s", clevel);
        spin_lock(&pers_lock);
        pers = find_pers(level, clevel);
        if (!pers || !try_module_get(pers->owner)) {
                spin_unlock(&pers_lock);
                pr_warn("md: personality %s not loaded\n", clevel);
                rv = -EINVAL;
                goto out_unlock;
        }
        spin_unlock(&pers_lock);

        if (pers == mddev->pers) {
                /* Nothing to do! */
                module_put(pers->owner);
                rv = len;
                goto out_unlock;
        }
        if (!pers->takeover) {
                module_put(pers->owner);
                pr_warn("md: %s: %s does not support personality takeover\n",
                        mdname(mddev), clevel);
                rv = -EINVAL;
                goto out_unlock;
        }

        rdev_for_each(rdev, mddev)
                rdev->new_raid_disk = rdev->raid_disk;

        /* ->takeover must set new_* and/or delta_disks
         * if it succeeds, and may set them when it fails.
         */
        priv = pers->takeover(mddev);
        if (IS_ERR(priv)) {
                mddev->new_level = mddev->level;
                mddev->new_layout = mddev->layout;
                mddev->new_chunk_sectors = mddev->chunk_sectors;
                mddev->raid_disks -= mddev->delta_disks;
                mddev->delta_disks = 0;
                mddev->reshape_backwards = 0;
                module_put(pers->owner);
                pr_warn("md: %s: %s would not accept array\n",
                        mdname(mddev), clevel);
                rv = PTR_ERR(priv);
                goto out_unlock;
        }

        /* Looks like we have a winner */
        mddev_suspend(mddev);
        mddev_detach(mddev);

        spin_lock(&mddev->lock);
        oldpers = mddev->pers;
        oldpriv = mddev->private;
        mddev->pers = pers;
        mddev->private = priv;
        strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
        mddev->level = mddev->new_level;
        mddev->layout = mddev->new_layout;
        mddev->chunk_sectors = mddev->new_chunk_sectors;
        mddev->delta_disks = 0;
        mddev->reshape_backwards = 0;
        mddev->degraded = 0;
        spin_unlock(&mddev->lock);

        if (oldpers->sync_request == NULL &&
            mddev->external) {
                /* We are converting from a no-redundancy array
                 * to a redundancy array and metadata is managed
                 * externally so we need to be sure that writes
                 * won't block due to a need to transition
                 *      clean->dirty
                 * until external management is started.
                 */
                mddev->in_sync = 0;
                mddev->safemode_delay = 0;
                mddev->safemode = 0;
        }

        oldpers->free(mddev, oldpriv);

        if (oldpers->sync_request == NULL &&
            pers->sync_request != NULL) {
                /* need to add the md_redundancy_group */
                if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
                        pr_warn("md: cannot register extra attributes for %s\n",
                                mdname(mddev));
                mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, "sync_action");
                mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
                mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
        }
        if (oldpers->sync_request != NULL &&
            pers->sync_request == NULL) {
                /* need to remove the md_redundancy_group */
                if (mddev->to_remove == NULL)
                        mddev->to_remove = &md_redundancy_group;
        }

        module_put(oldpers->owner);

        rdev_for_each(rdev, mddev) {
                if (rdev->raid_disk < 0)
                        continue;
                if (rdev->new_raid_disk >= mddev->raid_disks)
                        rdev->new_raid_disk = -1;
                if (rdev->new_raid_disk == rdev->raid_disk)
                        continue;
                sysfs_unlink_rdev(mddev, rdev);
        }
        rdev_for_each(rdev, mddev) {
                if (rdev->raid_disk < 0)
                        continue;
                if (rdev->new_raid_disk == rdev->raid_disk)
                        continue;
                rdev->raid_disk = rdev->new_raid_disk;
                if (rdev->raid_disk < 0)
                        clear_bit(In_sync, &rdev->flags);
                else {
                        if (sysfs_link_rdev(mddev, rdev))
                                pr_warn("md: cannot register rd%d for %s after level change\n",
                                        rdev->raid_disk, mdname(mddev));
                }
        }

        if (pers->sync_request == NULL) {
                /* this is now an array without redundancy, so
                 * it must always be in_sync
                 */
                mddev->in_sync = 1;
                del_timer_sync(&mddev->safemode_timer);
        }
        blk_set_stacking_limits(&mddev->queue->limits);
        pers->run(mddev);
        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
        mddev_resume(mddev);
        if (!mddev->thread)
                md_update_sb(mddev, 1);
        sysfs_notify_dirent_safe(mddev->sysfs_level);
        md_new_event(mddev);
        rv = len;
out_unlock:
        mddev_unlock(mddev);
        return rv;
}

static struct md_sysfs_entry md_level =
__ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);

static ssize_t
layout_show(struct mddev *mddev, char *page)
{
        /* just a number, not meaningful for all levels */
        if (mddev->reshape_position != MaxSector &&
            mddev->layout != mddev->new_layout)
                return sprintf(page, "%d (%d)\n",
                               mddev->new_layout, mddev->layout);
        return sprintf(page, "%d\n", mddev->layout);
}

static ssize_t
layout_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned int n;
        int err;

        err = kstrtouint(buf, 10, &n);
        if (err < 0)
                return err;
        err = mddev_lock(mddev);
        if (err)
                return err;

        if (mddev->pers) {
                if (mddev->pers->check_reshape == NULL)
                        err = -EBUSY;
                else if (mddev->ro)
                        err = -EROFS;
                else {
                        mddev->new_layout = n;
                        err = mddev->pers->check_reshape(mddev);
                        if (err)
                                mddev->new_layout = mddev->layout;
                }
        } else {
                mddev->new_layout = n;
                if (mddev->reshape_position == MaxSector)
                        mddev->layout = n;
        }
        mddev_unlock(mddev);
        return err ?: len;
}
static struct md_sysfs_entry md_layout =
__ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);

static ssize_t
raid_disks_show(struct mddev *mddev, char *page)
{
        if (mddev->raid_disks == 0)
                return 0;
        if (mddev->reshape_position != MaxSector &&
            mddev->delta_disks != 0)
                return sprintf(page, "%d (%d)\n", mddev->raid_disks,
                               mddev->raid_disks - mddev->delta_disks);
        return sprintf(page, "%d\n", mddev->raid_disks);
}

static int update_raid_disks(struct mddev *mddev, int raid_disks);

static ssize_t
raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned int n;
        int err;

        err = kstrtouint(buf, 10, &n);
        if (err < 0)
                return err;

        err = mddev_lock(mddev);
        if (err)
                return err;
        if (mddev->pers)
                err = update_raid_disks(mddev, n);
        else if (mddev->reshape_position != MaxSector) {
                struct md_rdev *rdev;
                int olddisks = mddev->raid_disks - mddev->delta_disks;

                err = -EINVAL;
                rdev_for_each(rdev, mddev) {
                        if (olddisks < n &&
                            rdev->data_offset < rdev->new_data_offset)
                                goto out_unlock;
                        if (olddisks > n &&
                            rdev->data_offset > rdev->new_data_offset)
                                goto out_unlock;
                }
                err = 0;
                mddev->delta_disks = n - olddisks;
                mddev->raid_disks = n;
                mddev->reshape_backwards = (mddev->delta_disks < 0);
        } else
                mddev->raid_disks = n;
out_unlock:
        mddev_unlock(mddev);
        return err ? err : len;
}
static struct md_sysfs_entry md_raid_disks =
__ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);

static ssize_t
uuid_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%pU\n", mddev->uuid);
}
static struct md_sysfs_entry md_uuid =
__ATTR(uuid, S_IRUGO, uuid_show, NULL);

static ssize_t
chunk_size_show(struct mddev *mddev, char *page)
{
        if (mddev->reshape_position != MaxSector &&
            mddev->chunk_sectors != mddev->new_chunk_sectors)
                return sprintf(page, "%d (%d)\n",
                               mddev->new_chunk_sectors << 9,
                               mddev->chunk_sectors << 9);
        return sprintf(page, "%d\n", mddev->chunk_sectors << 9);
}

static ssize_t
chunk_size_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned long n;
        int err;

        err = kstrtoul(buf, 10, &n);
        if (err < 0)
                return err;

        err = mddev_lock(mddev);
        if (err)
                return err;
        if (mddev->pers) {
                if (mddev->pers->check_reshape == NULL)
                        err = -EBUSY;
                else if (mddev->ro)
                        err = -EROFS;
                else {
                        mddev->new_chunk_sectors = n >> 9;
                        err = mddev->pers->check_reshape(mddev);
                        if (err)
                                mddev->new_chunk_sectors = mddev->chunk_sectors;
                }
        } else {
                mddev->new_chunk_sectors = n >> 9;
                if (mddev->reshape_position == MaxSector)
                        mddev->chunk_sectors = n >> 9;
        }
        mddev_unlock(mddev);
        return err ?: len;
}
static struct md_sysfs_entry md_chunk_size =
__ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);

static ssize_t
resync_start_show(struct mddev *mddev, char *page)
{
        if (mddev->recovery_cp == MaxSector)
                return sprintf(page, "none\n");
        return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
}

static ssize_t
resync_start_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned long long n;
        int err;

        if (cmd_match(buf, "none"))
                n = MaxSector;
        else {
                err = kstrtoull(buf, 10, &n);
                if (err < 0)
                        return err;
                if (n != (sector_t)n)
                        return -EINVAL;
        }

        err = mddev_lock(mddev);
        if (err)
                return err;
        if (mddev->pers && !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
                err = -EBUSY;

        if (!err) {
                mddev->recovery_cp = n;
                if (mddev->pers)
                        set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
        }
        mddev_unlock(mddev);
        return err ?: len;
}
static struct md_sysfs_entry md_resync_start =
__ATTR_PREALLOC(resync_start, S_IRUGO|S_IWUSR,
                resync_start_show, resync_start_store);

/*
 * The array state can be:
 *
 * clear
 *     No devices, no size, no level
 *     Equivalent to STOP_ARRAY ioctl
 * inactive
 *     May have some settings, but array is not active
 *        all IO results in error
 *     When written, doesn't tear down array, but just stops it
 * suspended (not supported yet)
 *     All IO requests will block. The array can be reconfigured.
 *     Writing this, if accepted, will block until array is quiescent
 * readonly
 *     no resync can happen.  no superblocks get written.
 *     write requests fail
 * read-auto
 *     like readonly, but behaves like 'clean' on a write request.
 *
 * clean - no pending writes, but otherwise active.
 *     When written to inactive array, starts without resync
 *     If a write request arrives then
 *       if metadata is known, mark 'dirty' and switch to 'active'.
 *       if not known, block and switch to write-pending
 *     If written to an active array that has pending writes, then fails.
 * active
 *     fully active: IO and resync can be happening.
 *     When written to inactive array, starts with resync
 *
 * write-pending
 *     clean, but writes are blocked waiting for 'active' to be written.
 *
 * active-idle
 *     like active, but no writes have been seen for a while (100msec).
 *
 * broken
 *     RAID0/LINEAR-only: same as clean, but array is missing a member.
 *     It's useful because RAID0/LINEAR mounted-arrays aren't stopped
 *     when a member is gone, so this state will at least alert the
 *     user that something is wrong.
 */
enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
                   write_pending, active_idle, broken, bad_word};
static char *array_states[] = {
        "clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
        "write-pending", "active-idle", "broken", NULL };

static int match_word(const char *word, char **list)
{
        int n;
        for (n=0; list[n]; n++)
                if (cmd_match(word, list[n]))
                        break;
        return n;
}

static ssize_t
array_state_show(struct mddev *mddev, char *page)
{
        enum array_state st = inactive;

        if (mddev->pers && !test_bit(MD_NOT_READY, &mddev->flags)) {
                switch(mddev->ro) {
                case 1:
                        st = readonly;
                        break;
                case 2:
                        st = read_auto;
                        break;
                case 0:
                        spin_lock(&mddev->lock);
                        if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
                                st = write_pending;
                        else if (mddev->in_sync)
                                st = clean;
                        else if (mddev->safemode)
                                st = active_idle;
                        else
                                st = active;
                        spin_unlock(&mddev->lock);
                }

                if (test_bit(MD_BROKEN, &mddev->flags) && st == clean)
                        st = broken;
        } else {
                if (list_empty(&mddev->disks) &&
                    mddev->raid_disks == 0 &&
                    mddev->dev_sectors == 0)
                        st = clear;
                else
                        st = inactive;
        }
        return sprintf(page, "%s\n", array_states[st]);
}

static int do_md_stop(struct mddev *mddev, int ro, struct block_device *bdev);
static int md_set_readonly(struct mddev *mddev, struct block_device *bdev);
static int restart_array(struct mddev *mddev);

static ssize_t
array_state_store(struct mddev *mddev, const char *buf, size_t len)
{
        int err = 0;
        enum array_state st = match_word(buf, array_states);

        if (mddev->pers && (st == active || st == clean) && mddev->ro != 1) {
                /* don't take reconfig_mutex when toggling between
                 * clean and active
                 */
                spin_lock(&mddev->lock);
                if (st == active) {
                        restart_array(mddev);
                        clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
                        md_wakeup_thread(mddev->thread);
                        wake_up(&mddev->sb_wait);
                } else /* st == clean */ {
                        restart_array(mddev);
                        if (!set_in_sync(mddev))
                                err = -EBUSY;
                }
                if (!err)
                        sysfs_notify_dirent_safe(mddev->sysfs_state);
                spin_unlock(&mddev->lock);
                return err ?: len;
        }
        err = mddev_lock(mddev);
        if (err)
                return err;
        err = -EINVAL;
        switch(st) {
        case bad_word:
                break;
        case clear:
                /* stopping an active array */
                err = do_md_stop(mddev, 0, NULL);
                break;
        case inactive:
                /* stopping an active array */
                if (mddev->pers)
                        err = do_md_stop(mddev, 2, NULL);
                else
                        err = 0; /* already inactive */
                break;
        case suspended:
                break; /* not supported yet */
        case readonly:
                if (mddev->pers)
                        err = md_set_readonly(mddev, NULL);
                else {
                        mddev->ro = 1;
                        set_disk_ro(mddev->gendisk, 1);
                        err = do_md_run(mddev);
                }
                break;
        case read_auto:
                if (mddev->pers) {
                        if (mddev->ro == 0)
                                err = md_set_readonly(mddev, NULL);
                        else if (mddev->ro == 1)
                                err = restart_array(mddev);
                        if (err == 0) {
                                mddev->ro = 2;
                                set_disk_ro(mddev->gendisk, 0);
                        }
                } else {
                        mddev->ro = 2;
                        err = do_md_run(mddev);
                }
                break;
        case clean:
                if (mddev->pers) {
                        err = restart_array(mddev);
                        if (err)
                                break;
                        spin_lock(&mddev->lock);
                        if (!set_in_sync(mddev))
                                err = -EBUSY;
                        spin_unlock(&mddev->lock);
                } else
                        err = -EINVAL;
                break;
        case active:
                if (mddev->pers) {
                        err = restart_array(mddev);
                        if (err)
                                break;
                        clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
                        wake_up(&mddev->sb_wait);
                        err = 0;
                } else {
                        mddev->ro = 0;
                        set_disk_ro(mddev->gendisk, 0);
                        err = do_md_run(mddev);
                }
                break;
        case write_pending:
        case active_idle:
        case broken:
                /* these cannot be set */
                break;
        }

        if (!err) {
                if (mddev->hold_active == UNTIL_IOCTL)
                        mddev->hold_active = 0;
                sysfs_notify_dirent_safe(mddev->sysfs_state);
        }
        mddev_unlock(mddev);
        return err ?: len;
}
static struct md_sysfs_entry md_array_state =
__ATTR_PREALLOC(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);

static ssize_t
max_corrected_read_errors_show(struct mddev *mddev, char *page) {
        return sprintf(page, "%d\n",
                       atomic_read(&mddev->max_corr_read_errors));
}

static ssize_t
max_corrected_read_errors_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned int n;
        int rv;

        rv = kstrtouint(buf, 10, &n);
        if (rv < 0)
                return rv;
        atomic_set(&mddev->max_corr_read_errors, n);
        return len;
}

static struct md_sysfs_entry max_corr_read_errors =
__ATTR(max_read_errors, S_IRUGO|S_IWUSR, max_corrected_read_errors_show,
        max_corrected_read_errors_store);

static ssize_t
null_show(struct mddev *mddev, char *page)
{
        return -EINVAL;
}

/* need to ensure rdev_delayed_delete() has completed */
static void flush_rdev_wq(struct mddev *mddev)
{
        struct md_rdev *rdev;

        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev)
                if (work_pending(&rdev->del_work)) {
                        flush_workqueue(md_rdev_misc_wq);
                        break;
                }
        rcu_read_unlock();
}

static ssize_t
new_dev_store(struct mddev *mddev, const char *buf, size_t len)
{
        /* buf must be %d:%d\n? giving major and minor numbers */
        /* The new device is added to the array.
         * If the array has a persistent superblock, we read the
         * superblock to initialise info and check validity.
         * Otherwise, only checking done is that in bind_rdev_to_array,
         * which mainly checks size.
         */
        char *e;
        int major = simple_strtoul(buf, &e, 10);
        int minor;
        dev_t dev;
        struct md_rdev *rdev;
        int err;

        if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
                return -EINVAL;
        minor = simple_strtoul(e+1, &e, 10);
        if (*e && *e != '\n')
                return -EINVAL;
        dev = MKDEV(major, minor);
        if (major != MAJOR(dev) ||
            minor != MINOR(dev))
                return -EOVERFLOW;

        flush_rdev_wq(mddev);
        err = mddev_lock(mddev);
        if (err)
                return err;
        if (mddev->persistent) {
                rdev = md_import_device(dev, mddev->major_version,
                                        mddev->minor_version);
                if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
                        struct md_rdev *rdev0
                                = list_entry(mddev->disks.next,
                                             struct md_rdev, same_set);
                        err = super_types[mddev->major_version]
                                .load_super(rdev, rdev0, mddev->minor_version);
                        if (err < 0)
                                goto out;
                }
        } else if (mddev->external)
                rdev = md_import_device(dev, -2, -1);
        else
                rdev = md_import_device(dev, -1, -1);

        if (IS_ERR(rdev)) {
                mddev_unlock(mddev);
                return PTR_ERR(rdev);
        }
        err = bind_rdev_to_array(rdev, mddev);
 out:
        if (err)
                export_rdev(rdev);
        mddev_unlock(mddev);
        if (!err)
                md_new_event(mddev);
        return err ? err : len;
}

static struct md_sysfs_entry md_new_device =
__ATTR(new_dev, S_IWUSR, null_show, new_dev_store);

static ssize_t
bitmap_store(struct mddev *mddev, const char *buf, size_t len)
{
        char *end;
        unsigned long chunk, end_chunk;
        int err;

        err = mddev_lock(mddev);
        if (err)
                return err;
        if (!mddev->bitmap)
                goto out;
        /* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
        while (*buf) {
                chunk = end_chunk = simple_strtoul(buf, &end, 0);
                if (buf == end) break;
                if (*end == '-') { /* range */
                        buf = end + 1;
                        end_chunk = simple_strtoul(buf, &end, 0);
                        if (buf == end) break;
                }
                if (*end && !isspace(*end)) break;
                md_bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
                buf = skip_spaces(end);
        }
        md_bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
out:
        mddev_unlock(mddev);
        return len;
}

static struct md_sysfs_entry md_bitmap =
__ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);

static ssize_t
size_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%llu\n",
                (unsigned long long)mddev->dev_sectors / 2);
}

static int update_size(struct mddev *mddev, sector_t num_sectors);

static ssize_t
size_store(struct mddev *mddev, const char *buf, size_t len)
{
        /* If array is inactive, we can reduce the component size, but
         * not increase it (except from 0).
         * If array is active, we can try an on-line resize
         */
        sector_t sectors;
        int err = strict_blocks_to_sectors(buf, &sectors);

        if (err < 0)
                return err;
        err = mddev_lock(mddev);
        if (err)
                return err;
        if (mddev->pers) {
                err = update_size(mddev, sectors);
                if (err == 0)
                        md_update_sb(mddev, 1);
        } else {
                if (mddev->dev_sectors == 0 ||
                    mddev->dev_sectors > sectors)
                        mddev->dev_sectors = sectors;
                else
                        err = -ENOSPC;
        }
        mddev_unlock(mddev);
        return err ? err : len;
}

static struct md_sysfs_entry md_size =
__ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);

/* Metadata version.
 * This is one of
 *   'none' for arrays with no metadata (good luck...)
 *   'external' for arrays with externally managed metadata,
 * or N.M for internally known formats
 */
static ssize_t
metadata_show(struct mddev *mddev, char *page)
{
        if (mddev->persistent)
                return sprintf(page, "%d.%d\n",
                               mddev->major_version, mddev->minor_version);
        else if (mddev->external)
                return sprintf(page, "external:%s\n", mddev->metadata_type);
        else
                return sprintf(page, "none\n");
}

static ssize_t
metadata_store(struct mddev *mddev, const char *buf, size_t len)
{
        int major, minor;
        char *e;
        int err;
        /* Changing the details of 'external' metadata is
         * always permitted.  Otherwise there must be
         * no devices attached to the array.
         */

        err = mddev_lock(mddev);
        if (err)
                return err;
        err = -EBUSY;
        if (mddev->external && strncmp(buf, "external:", 9) == 0)
                ;
        else if (!list_empty(&mddev->disks))
                goto out_unlock;

        err = 0;
        if (cmd_match(buf, "none")) {
                mddev->persistent = 0;
                mddev->external = 0;
                mddev->major_version = 0;
                mddev->minor_version = 90;
                goto out_unlock;
        }
        if (strncmp(buf, "external:", 9) == 0) {
                size_t namelen = len-9;
                if (namelen >= sizeof(mddev->metadata_type))
                        namelen = sizeof(mddev->metadata_type)-1;
                strncpy(mddev->metadata_type, buf+9, namelen);
                mddev->metadata_type[namelen] = 0;
                if (namelen && mddev->metadata_type[namelen-1] == '\n')
                        mddev->metadata_type[--namelen] = 0;
                mddev->persistent = 0;
                mddev->external = 1;
                mddev->major_version = 0;
                mddev->minor_version = 90;
                goto out_unlock;
        }
        major = simple_strtoul(buf, &e, 10);
        err = -EINVAL;
        if (e==buf || *e != '.')
                goto out_unlock;
        buf = e+1;
        minor = simple_strtoul(buf, &e, 10);
        if (e==buf || (*e && *e != '\n') )
                goto out_unlock;
        err = -ENOENT;
        if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
                goto out_unlock;
        mddev->major_version = major;
        mddev->minor_version = minor;
        mddev->persistent = 1;
        mddev->external = 0;
        err = 0;
out_unlock:
        mddev_unlock(mddev);
        return err ?: len;
}

static struct md_sysfs_entry md_metadata =
__ATTR_PREALLOC(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);

static ssize_t
action_show(struct mddev *mddev, char *page)
{
        char *type = "idle";
        unsigned long recovery = mddev->recovery;
        if (test_bit(MD_RECOVERY_FROZEN, &recovery))
                type = "frozen";
        else if (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
            (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery))) {
                if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
                        type = "reshape";
                else if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
                        if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
                                type = "resync";
                        else if (test_bit(MD_RECOVERY_CHECK, &recovery))
                                type = "check";
                        else
                                type = "repair";
                } else if (test_bit(MD_RECOVERY_RECOVER, &recovery))
                        type = "recover";
                else if (mddev->reshape_position != MaxSector)
                        type = "reshape";
        }
        return sprintf(page, "%s\n", type);
}

static ssize_t
action_store(struct mddev *mddev, const char *page, size_t len)
{
        if (!mddev->pers || !mddev->pers->sync_request)
                return -EINVAL;


        if (cmd_match(page, "idle") || cmd_match(page, "frozen")) {
                if (cmd_match(page, "frozen"))
                        set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                else
                        clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
                    mddev_lock(mddev) == 0) {
                        if (work_pending(&mddev->del_work))
                                flush_workqueue(md_misc_wq);
                        if (mddev->sync_thread) {
                                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                                md_reap_sync_thread(mddev);
                        }
                        mddev_unlock(mddev);
                }
        } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                return -EBUSY;
        else if (cmd_match(page, "resync"))
                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
        else if (cmd_match(page, "recover")) {
                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        } else if (cmd_match(page, "reshape")) {
                int err;
                if (mddev->pers->start_reshape == NULL)
                        return -EINVAL;
                err = mddev_lock(mddev);
                if (!err) {
                        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                                err =  -EBUSY;
                        else {
                                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                                err = mddev->pers->start_reshape(mddev);
                        }
                        mddev_unlock(mddev);
                }
                if (err)
                        return err;
                sysfs_notify_dirent_safe(mddev->sysfs_degraded);
        } else {
                if (cmd_match(page, "check"))
                        set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
                else if (!cmd_match(page, "repair"))
                        return -EINVAL;
                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
                set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
        }
        if (mddev->ro == 2) {
                /* A write to sync_action is enough to justify
                 * canceling read-auto mode
                 */
                mddev->ro = 0;
                md_wakeup_thread(mddev->sync_thread);
        }
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        sysfs_notify_dirent_safe(mddev->sysfs_action);
        return len;
}

static struct md_sysfs_entry md_scan_mode =
__ATTR_PREALLOC(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);

static ssize_t
last_sync_action_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%s\n", mddev->last_sync_action);
}

static struct md_sysfs_entry md_last_scan_mode = __ATTR_RO(last_sync_action);

static ssize_t
mismatch_cnt_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%llu\n",
                       (unsigned long long)
                       atomic64_read(&mddev->resync_mismatches));
}

static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);

static ssize_t
sync_min_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%d (%s)\n", speed_min(mddev),
                       mddev->sync_speed_min ? "local": "system");
}

static ssize_t
sync_min_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned int min;
        int rv;

        if (strncmp(buf, "system", 6)==0) {
                min = 0;
        } else {
                rv = kstrtouint(buf, 10, &min);
                if (rv < 0)
                        return rv;
                if (min == 0)
                        return -EINVAL;
        }
        mddev->sync_speed_min = min;
        return len;
}

static struct md_sysfs_entry md_sync_min =
__ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);

static ssize_t
sync_max_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%d (%s)\n", speed_max(mddev),
                       mddev->sync_speed_max ? "local": "system");
}

static ssize_t
sync_max_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned int max;
        int rv;

        if (strncmp(buf, "system", 6)==0) {
                max = 0;
        } else {
                rv = kstrtouint(buf, 10, &max);
                if (rv < 0)
                        return rv;
                if (max == 0)
                        return -EINVAL;
        }
        mddev->sync_speed_max = max;
        return len;
}

static struct md_sysfs_entry md_sync_max =
__ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);

static ssize_t
degraded_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%d\n", mddev->degraded);
}
static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);

static ssize_t
sync_force_parallel_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%d\n", mddev->parallel_resync);
}

static ssize_t
sync_force_parallel_store(struct mddev *mddev, const char *buf, size_t len)
{
        long n;

        if (kstrtol(buf, 10, &n))
                return -EINVAL;

        if (n != 0 && n != 1)
                return -EINVAL;

        mddev->parallel_resync = n;

        if (mddev->sync_thread)
                wake_up(&resync_wait);

        return len;
}

/* force parallel resync, even with shared block devices */
static struct md_sysfs_entry md_sync_force_parallel =
__ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
       sync_force_parallel_show, sync_force_parallel_store);

static ssize_t
sync_speed_show(struct mddev *mddev, char *page)
{
        unsigned long resync, dt, db;
        if (mddev->curr_resync == 0)
                return sprintf(page, "none\n");
        resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
        dt = (jiffies - mddev->resync_mark) / HZ;
        if (!dt) dt++;
        db = resync - mddev->resync_mark_cnt;
        return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
}

static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);

static ssize_t
sync_completed_show(struct mddev *mddev, char *page)
{
        unsigned long long max_sectors, resync;

        if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                return sprintf(page, "none\n");

        if (mddev->curr_resync == 1 ||
            mddev->curr_resync == 2)
                return sprintf(page, "delayed\n");

        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
            test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                max_sectors = mddev->resync_max_sectors;
        else
                max_sectors = mddev->dev_sectors;

        resync = mddev->curr_resync_completed;
        return sprintf(page, "%llu / %llu\n", resync, max_sectors);
}

static struct md_sysfs_entry md_sync_completed =
        __ATTR_PREALLOC(sync_completed, S_IRUGO, sync_completed_show, NULL);

static ssize_t
min_sync_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%llu\n",
                       (unsigned long long)mddev->resync_min);
}
static ssize_t
min_sync_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned long long min;
        int err;

        if (kstrtoull(buf, 10, &min))
                return -EINVAL;

        spin_lock(&mddev->lock);
        err = -EINVAL;
        if (min > mddev->resync_max)
                goto out_unlock;

        err = -EBUSY;
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                goto out_unlock;

        /* Round down to multiple of 4K for safety */
        mddev->resync_min = round_down(min, 8);
        err = 0;

out_unlock:
        spin_unlock(&mddev->lock);
        return err ?: len;
}

static struct md_sysfs_entry md_min_sync =
__ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);

static ssize_t
max_sync_show(struct mddev *mddev, char *page)
{
        if (mddev->resync_max == MaxSector)
                return sprintf(page, "max\n");
        else
                return sprintf(page, "%llu\n",
                               (unsigned long long)mddev->resync_max);
}
static ssize_t
max_sync_store(struct mddev *mddev, const char *buf, size_t len)
{
        int err;
        spin_lock(&mddev->lock);
        if (strncmp(buf, "max", 3) == 0)
                mddev->resync_max = MaxSector;
        else {
                unsigned long long max;
                int chunk;

                err = -EINVAL;
                if (kstrtoull(buf, 10, &max))
                        goto out_unlock;
                if (max < mddev->resync_min)
                        goto out_unlock;

                err = -EBUSY;
                if (max < mddev->resync_max &&
                    mddev->ro == 0 &&
                    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                        goto out_unlock;

                /* Must be a multiple of chunk_size */
                chunk = mddev->chunk_sectors;
                if (chunk) {
                        sector_t temp = max;

                        err = -EINVAL;
                        if (sector_div(temp, chunk))
                                goto out_unlock;
                }
                mddev->resync_max = max;
        }
        wake_up(&mddev->recovery_wait);
        err = 0;
out_unlock:
        spin_unlock(&mddev->lock);
        return err ?: len;
}

static struct md_sysfs_entry md_max_sync =
__ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);

static ssize_t
suspend_lo_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
}

static ssize_t
suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned long long new;
        int err;

        err = kstrtoull(buf, 10, &new);
        if (err < 0)
                return err;
        if (new != (sector_t)new)
                return -EINVAL;

        err = mddev_lock(mddev);
        if (err)
                return err;
        err = -EINVAL;
        if (mddev->pers == NULL ||
            mddev->pers->quiesce == NULL)
                goto unlock;
        mddev_suspend(mddev);
        mddev->suspend_lo = new;
        mddev_resume(mddev);

        err = 0;
unlock:
        mddev_unlock(mddev);
        return err ?: len;
}
static struct md_sysfs_entry md_suspend_lo =
__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);

static ssize_t
suspend_hi_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
}

static ssize_t
suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
{
        unsigned long long new;
        int err;

        err = kstrtoull(buf, 10, &new);
        if (err < 0)
                return err;
        if (new != (sector_t)new)
                return -EINVAL;

        err = mddev_lock(mddev);
        if (err)
                return err;
        err = -EINVAL;
        if (mddev->pers == NULL)
                goto unlock;

        mddev_suspend(mddev);
        mddev->suspend_hi = new;
        mddev_resume(mddev);

        err = 0;
unlock:
        mddev_unlock(mddev);
        return err ?: len;
}
static struct md_sysfs_entry md_suspend_hi =
__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);

static ssize_t
reshape_position_show(struct mddev *mddev, char *page)
{
        if (mddev->reshape_position != MaxSector)
                return sprintf(page, "%llu\n",
                               (unsigned long long)mddev->reshape_position);
        strcpy(page, "none\n");
        return 5;
}

static ssize_t
reshape_position_store(struct mddev *mddev, const char *buf, size_t len)
{
        struct md_rdev *rdev;
        unsigned long long new;
        int err;

        err = kstrtoull(buf, 10, &new);
        if (err < 0)
                return err;
        if (new != (sector_t)new)
                return -EINVAL;
        err = mddev_lock(mddev);
        if (err)
                return err;
        err = -EBUSY;
        if (mddev->pers)
                goto unlock;
        mddev->reshape_position = new;
        mddev->delta_disks = 0;
        mddev->reshape_backwards = 0;
        mddev->new_level = mddev->level;
        mddev->new_layout = mddev->layout;
        mddev->new_chunk_sectors = mddev->chunk_sectors;
        rdev_for_each(rdev, mddev)
                rdev->new_data_offset = rdev->data_offset;
        err = 0;
unlock:
        mddev_unlock(mddev);
        return err ?: len;
}

static struct md_sysfs_entry md_reshape_position =
__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
       reshape_position_store);

static ssize_t
reshape_direction_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%s\n",
                       mddev->reshape_backwards ? "backwards" : "forwards");
}

static ssize_t
reshape_direction_store(struct mddev *mddev, const char *buf, size_t len)
{
        int backwards = 0;
        int err;

        if (cmd_match(buf, "forwards"))
                backwards = 0;
        else if (cmd_match(buf, "backwards"))
                backwards = 1;
        else
                return -EINVAL;
        if (mddev->reshape_backwards == backwards)
                return len;

        err = mddev_lock(mddev);
        if (err)
                return err;
        /* check if we are allowed to change */
        if (mddev->delta_disks)
                err = -EBUSY;
        else if (mddev->persistent &&
            mddev->major_version == 0)
                err =  -EINVAL;
        else
                mddev->reshape_backwards = backwards;
        mddev_unlock(mddev);
        return err ?: len;
}

static struct md_sysfs_entry md_reshape_direction =
__ATTR(reshape_direction, S_IRUGO|S_IWUSR, reshape_direction_show,
       reshape_direction_store);

static ssize_t
array_size_show(struct mddev *mddev, char *page)
{
        if (mddev->external_size)
                return sprintf(page, "%llu\n",
                               (unsigned long long)mddev->array_sectors/2);
        else
                return sprintf(page, "default\n");
}

static ssize_t
array_size_store(struct mddev *mddev, const char *buf, size_t len)
{
        sector_t sectors;
        int err;

        err = mddev_lock(mddev);
        if (err)
                return err;

        /* cluster raid doesn't support change array_sectors */
        if (mddev_is_clustered(mddev)) {
                mddev_unlock(mddev);
                return -EINVAL;
        }

        if (strncmp(buf, "default", 7) == 0) {
                if (mddev->pers)
                        sectors = mddev->pers->size(mddev, 0, 0);
                else
                        sectors = mddev->array_sectors;

                mddev->external_size = 0;
        } else {
                if (strict_blocks_to_sectors(buf, &sectors) < 0)
                        err = -EINVAL;
                else if (mddev->pers && mddev->pers->size(mddev, 0, 0) < sectors)
                        err = -E2BIG;
                else
                        mddev->external_size = 1;
        }

        if (!err) {
                mddev->array_sectors = sectors;
                if (mddev->pers)
                        set_capacity_and_notify(mddev->gendisk,
                                                mddev->array_sectors);
        }
        mddev_unlock(mddev);
        return err ?: len;
}

static struct md_sysfs_entry md_array_size =
__ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
       array_size_store);

static ssize_t
consistency_policy_show(struct mddev *mddev, char *page)
{
        int ret;

        if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
                ret = sprintf(page, "journal\n");
        } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
                ret = sprintf(page, "ppl\n");
        } else if (mddev->bitmap) {
                ret = sprintf(page, "bitmap\n");
        } else if (mddev->pers) {
                if (mddev->pers->sync_request)
                        ret = sprintf(page, "resync\n");
                else
                        ret = sprintf(page, "none\n");
        } else {
                ret = sprintf(page, "unknown\n");
        }

        return ret;
}

static ssize_t
consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
{
        int err = 0;

        if (mddev->pers) {
                if (mddev->pers->change_consistency_policy)
                        err = mddev->pers->change_consistency_policy(mddev, buf);
                else
                        err = -EBUSY;
        } else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
                set_bit(MD_HAS_PPL, &mddev->flags);
        } else {
                err = -EINVAL;
        }

        return err ? err : len;
}

static struct md_sysfs_entry md_consistency_policy =
__ATTR(consistency_policy, S_IRUGO | S_IWUSR, consistency_policy_show,
       consistency_policy_store);

static ssize_t fail_last_dev_show(struct mddev *mddev, char *page)
{
        return sprintf(page, "%d\n", mddev->fail_last_dev);
}

/*
 * Setting fail_last_dev to true to allow last device to be forcibly removed
 * from RAID1/RAID10.
 */
static ssize_t
fail_last_dev_store(struct mddev *mddev, const char *buf, size_t len)
{
        int ret;
        bool value;

        ret = kstrtobool(buf, &value);
        if (ret)
                return ret;

        if (value != mddev->fail_last_dev)
                mddev->fail_last_dev = value;

        return len;
}
static struct md_sysfs_entry md_fail_last_dev =
__ATTR(fail_last_dev, S_IRUGO | S_IWUSR, fail_last_dev_show,
       fail_last_dev_store);

static ssize_t serialize_policy_show(struct mddev *mddev, char *page)
{
        if (mddev->pers == NULL || (mddev->pers->level != 1))
                return sprintf(page, "n/a\n");
        else
                return sprintf(page, "%d\n", mddev->serialize_policy);
}

/*
 * Setting serialize_policy to true to enforce write IO is not reordered
 * for raid1.
 */
static ssize_t
serialize_policy_store(struct mddev *mddev, const char *buf, size_t len)
{
        int err;
        bool value;

        err = kstrtobool(buf, &value);
        if (err)
                return err;

        if (value == mddev->serialize_policy)
                return len;

        err = mddev_lock(mddev);
        if (err)
                return err;
        if (mddev->pers == NULL || (mddev->pers->level != 1)) {
                pr_err("md: serialize_policy is only effective for raid1\n");
                err = -EINVAL;
                goto unlock;
        }

        mddev_suspend(mddev);
        if (value)
                mddev_create_serial_pool(mddev, NULL, true);
        else
                mddev_destroy_serial_pool(mddev, NULL, true);
        mddev->serialize_policy = value;
        mddev_resume(mddev);
unlock:
        mddev_unlock(mddev);
        return err ?: len;
}

static struct md_sysfs_entry md_serialize_policy =
__ATTR(serialize_policy, S_IRUGO | S_IWUSR, serialize_policy_show,
       serialize_policy_store);


static struct attribute *md_default_attrs[] = {
        &md_level.attr,
        &md_layout.attr,
        &md_raid_disks.attr,
        &md_uuid.attr,
        &md_chunk_size.attr,
        &md_size.attr,
        &md_resync_start.attr,
        &md_metadata.attr,
        &md_new_device.attr,
        &md_safe_delay.attr,
        &md_array_state.attr,
        &md_reshape_position.attr,
        &md_reshape_direction.attr,
        &md_array_size.attr,
        &max_corr_read_errors.attr,
        &md_consistency_policy.attr,
        &md_fail_last_dev.attr,
        &md_serialize_policy.attr,
        NULL,
};

static struct attribute *md_redundancy_attrs[] = {
        &md_scan_mode.attr,
        &md_last_scan_mode.attr,
        &md_mismatches.attr,
        &md_sync_min.attr,
        &md_sync_max.attr,
        &md_sync_speed.attr,
        &md_sync_force_parallel.attr,
        &md_sync_completed.attr,
        &md_min_sync.attr,
        &md_max_sync.attr,
        &md_suspend_lo.attr,
        &md_suspend_hi.attr,
        &md_bitmap.attr,
        &md_degraded.attr,
        NULL,
};
static struct attribute_group md_redundancy_group = {
        .name = NULL,
        .attrs = md_redundancy_attrs,
};

static ssize_t
md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
        struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
        struct mddev *mddev = container_of(kobj, struct mddev, kobj);
        ssize_t rv;

        if (!entry->show)
                return -EIO;
        spin_lock(&all_mddevs_lock);
        if (list_empty(&mddev->all_mddevs)) {
                spin_unlock(&all_mddevs_lock);
                return -EBUSY;
        }
        mddev_get(mddev);
        spin_unlock(&all_mddevs_lock);

        rv = entry->show(mddev, page);
        mddev_put(mddev);
        return rv;
}

static ssize_t
md_attr_store(struct kobject *kobj, struct attribute *attr,
              const char *page, size_t length)
{
        struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
        struct mddev *mddev = container_of(kobj, struct mddev, kobj);
        ssize_t rv;

        if (!entry->store)
                return -EIO;
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
        spin_lock(&all_mddevs_lock);
        if (list_empty(&mddev->all_mddevs)) {
                spin_unlock(&all_mddevs_lock);
                return -EBUSY;
        }
        mddev_get(mddev);
        spin_unlock(&all_mddevs_lock);
        rv = entry->store(mddev, page, length);
        mddev_put(mddev);
        return rv;
}

static void md_free(struct kobject *ko)
{
        struct mddev *mddev = container_of(ko, struct mddev, kobj);

        if (mddev->sysfs_state)
                sysfs_put(mddev->sysfs_state);
        if (mddev->sysfs_level)
                sysfs_put(mddev->sysfs_level);

        if (mddev->gendisk)
                del_gendisk(mddev->gendisk);
        if (mddev->queue)
                blk_cleanup_queue(mddev->queue);
        if (mddev->gendisk)
                put_disk(mddev->gendisk);
        percpu_ref_exit(&mddev->writes_pending);

        bioset_exit(&mddev->bio_set);
        bioset_exit(&mddev->sync_set);
        mempool_exit(&mddev->md_io_pool);
        kfree(mddev);
}

static const struct sysfs_ops md_sysfs_ops = {
        .show   = md_attr_show,
        .store  = md_attr_store,
};
static struct kobj_type md_ktype = {
        .release        = md_free,
        .sysfs_ops      = &md_sysfs_ops,
        .default_attrs  = md_default_attrs,
};

int mdp_major = 0;

static void mddev_delayed_delete(struct work_struct *ws)
{
        struct mddev *mddev = container_of(ws, struct mddev, del_work);

        sysfs_remove_group(&mddev->kobj, &md_bitmap_group);
        kobject_del(&mddev->kobj);
        kobject_put(&mddev->kobj);
}

static void no_op(struct percpu_ref *r) {}

int mddev_init_writes_pending(struct mddev *mddev)
{
        if (mddev->writes_pending.percpu_count_ptr)
                return 0;
        if (percpu_ref_init(&mddev->writes_pending, no_op,
                            PERCPU_REF_ALLOW_REINIT, GFP_KERNEL) < 0)
                return -ENOMEM;
        /* We want to start with the refcount at zero */
        percpu_ref_put(&mddev->writes_pending);
        return 0;
}
EXPORT_SYMBOL_GPL(mddev_init_writes_pending);

static int md_alloc(dev_t dev, char *name)
{
        /*
         * If dev is zero, name is the name of a device to allocate with
         * an arbitrary minor number.  It will be "md_???"
         * If dev is non-zero it must be a device number with a MAJOR of
         * MD_MAJOR or mdp_major.  In this case, if "name" is NULL, then
         * the device is being created by opening a node in /dev.
         * If "name" is not NULL, the device is being created by
         * writing to /sys/module/md_mod/parameters/new_array.
         */
        static DEFINE_MUTEX(disks_mutex);
        struct mddev *mddev = mddev_find_or_alloc(dev);
        struct gendisk *disk;
        int partitioned;
        int shift;
        int unit;
        int error;

        if (!mddev)
                return -ENODEV;

        partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
        shift = partitioned ? MdpMinorShift : 0;
        unit = MINOR(mddev->unit) >> shift;

        /* wait for any previous instance of this device to be
         * completely removed (mddev_delayed_delete).
         */
        flush_workqueue(md_misc_wq);

        mutex_lock(&disks_mutex);
        error = -EEXIST;
        if (mddev->gendisk)
                goto abort;

        if (name && !dev) {
                /* Need to ensure that 'name' is not a duplicate.
                 */
                struct mddev *mddev2;
                spin_lock(&all_mddevs_lock);

                list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
                        if (mddev2->gendisk &&
                            strcmp(mddev2->gendisk->disk_name, name) == 0) {
                                spin_unlock(&all_mddevs_lock);
                                goto abort;
                        }
                spin_unlock(&all_mddevs_lock);
        }
        if (name && dev)
                /*
                 * Creating /dev/mdNNN via "newarray", so adjust hold_active.
                 */
                mddev->hold_active = UNTIL_STOP;

        error = mempool_init_kmalloc_pool(&mddev->md_io_pool, BIO_POOL_SIZE,
                                          sizeof(struct md_io));
        if (error)
                goto abort;

        error = -ENOMEM;
        mddev->queue = blk_alloc_queue(NUMA_NO_NODE);
        if (!mddev->queue)
                goto abort;

        blk_set_stacking_limits(&mddev->queue->limits);

        disk = alloc_disk(1 << shift);
        if (!disk) {
                blk_cleanup_queue(mddev->queue);
                mddev->queue = NULL;
                goto abort;
        }
        disk->major = MAJOR(mddev->unit);
        disk->first_minor = unit << shift;
        if (name)
                strcpy(disk->disk_name, name);
        else if (partitioned)
                sprintf(disk->disk_name, "md_d%d", unit);
        else
                sprintf(disk->disk_name, "md%d", unit);
        disk->fops = &md_fops;
        disk->private_data = mddev;
        disk->queue = mddev->queue;
        blk_queue_write_cache(mddev->queue, true, true);
        /* Allow extended partitions.  This makes the
         * 'mdp' device redundant, but we can't really
         * remove it now.
         */
        disk->flags |= GENHD_FL_EXT_DEVT;
        disk->events |= DISK_EVENT_MEDIA_CHANGE;
        mddev->gendisk = disk;
        /* As soon as we call add_disk(), another thread could get
         * through to md_open, so make sure it doesn't get too far
         */
        mutex_lock(&mddev->open_mutex);
        add_disk(disk);

        error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");
        if (error) {
                /* This isn't possible, but as kobject_init_and_add is marked
                 * __must_check, we must do something with the result
                 */
                pr_debug("md: cannot register %s/md - name in use\n",
                         disk->disk_name);
                error = 0;
        }
        if (mddev->kobj.sd &&
            sysfs_create_group(&mddev->kobj, &md_bitmap_group))
                pr_debug("pointless warning\n");
        mutex_unlock(&mddev->open_mutex);
 abort:
        mutex_unlock(&disks_mutex);
        if (!error && mddev->kobj.sd) {
                kobject_uevent(&mddev->kobj, KOBJ_ADD);
                mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
                mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
        }
        mddev_put(mddev);
        return error;
}

static void md_probe(dev_t dev)
{
        if (MAJOR(dev) == MD_MAJOR && MINOR(dev) >= 512)
                return;
        if (create_on_open)
                md_alloc(dev, NULL);
}

static int add_named_array(const char *val, const struct kernel_param *kp)
{
        /*
         * val must be "md_*" or "mdNNN".
         * For "md_*" we allocate an array with a large free minor number, and
         * set the name to val.  val must not already be an active name.
         * For "mdNNN" we allocate an array with the minor number NNN
         * which must not already be in use.
         */
        int len = strlen(val);
        char buf[DISK_NAME_LEN];
        unsigned long devnum;

        while (len && val[len-1] == '\n')
                len--;
        if (len >= DISK_NAME_LEN)
                return -E2BIG;
        strlcpy(buf, val, len+1);
        if (strncmp(buf, "md_", 3) == 0)
                return md_alloc(0, buf);
        if (strncmp(buf, "md", 2) == 0 &&
            isdigit(buf[2]) &&
            kstrtoul(buf+2, 10, &devnum) == 0 &&
            devnum <= MINORMASK)
                return md_alloc(MKDEV(MD_MAJOR, devnum), NULL);

        return -EINVAL;
}

static void md_safemode_timeout(struct timer_list *t)
{
        struct mddev *mddev = from_timer(mddev, t, safemode_timer);

        mddev->safemode = 1;
        if (mddev->external)
                sysfs_notify_dirent_safe(mddev->sysfs_state);

        md_wakeup_thread(mddev->thread);
}

static int start_dirty_degraded;

int md_run(struct mddev *mddev)
{
        int err;
        struct md_rdev *rdev;
        struct md_personality *pers;

        if (list_empty(&mddev->disks))
                /* cannot run an array with no devices.. */
                return -EINVAL;

        if (mddev->pers)
                return -EBUSY;
        /* Cannot run until previous stop completes properly */
        if (mddev->sysfs_active)
                return -EBUSY;

        /*
         * Analyze all RAID superblock(s)
         */
        if (!mddev->raid_disks) {
                if (!mddev->persistent)
                        return -EINVAL;
                err = analyze_sbs(mddev);
                if (err)
                        return -EINVAL;
        }

        if (mddev->level != LEVEL_NONE)
                request_module("md-level-%d", mddev->level);
        else if (mddev->clevel[0])
                request_module("md-%s", mddev->clevel);

        /*
         * Drop all container device buffers, from now on
         * the only valid external interface is through the md
         * device.
         */
        mddev->has_superblocks = false;
        rdev_for_each(rdev, mddev) {
                if (test_bit(Faulty, &rdev->flags))
                        continue;
                sync_blockdev(rdev->bdev);
                invalidate_bdev(rdev->bdev);
                if (mddev->ro != 1 && rdev_read_only(rdev)) {
                        mddev->ro = 1;
                        if (mddev->gendisk)
                                set_disk_ro(mddev->gendisk, 1);
                }

                if (rdev->sb_page)
                        mddev->has_superblocks = true;

                /* perform some consistency tests on the device.
                 * We don't want the data to overlap the metadata,
                 * Internal Bitmap issues have been handled elsewhere.
                 */
                if (rdev->meta_bdev) {
                        /* Nothing to check */;
                } else if (rdev->data_offset < rdev->sb_start) {
                        if (mddev->dev_sectors &&
                            rdev->data_offset + mddev->dev_sectors
                            > rdev->sb_start) {
                                pr_warn("md: %s: data overlaps metadata\n",
                                        mdname(mddev));
                                return -EINVAL;
                        }
                } else {
                        if (rdev->sb_start + rdev->sb_size/512
                            > rdev->data_offset) {
                                pr_warn("md: %s: metadata overlaps data\n",
                                        mdname(mddev));
                                return -EINVAL;
                        }
                }
                sysfs_notify_dirent_safe(rdev->sysfs_state);
        }

        if (!bioset_initialized(&mddev->bio_set)) {
                err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
                if (err)
                        return err;
        }
        if (!bioset_initialized(&mddev->sync_set)) {
                err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
                if (err)
                        return err;
        }

        spin_lock(&pers_lock);
        pers = find_pers(mddev->level, mddev->clevel);
        if (!pers || !try_module_get(pers->owner)) {
                spin_unlock(&pers_lock);
                if (mddev->level != LEVEL_NONE)
                        pr_warn("md: personality for level %d is not loaded!\n",
                                mddev->level);
                else
                        pr_warn("md: personality for level %s is not loaded!\n",
                                mddev->clevel);
                err = -EINVAL;
                goto abort;
        }
        spin_unlock(&pers_lock);
        if (mddev->level != pers->level) {
                mddev->level = pers->level;
                mddev->new_level = pers->level;
        }
        strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));

        if (mddev->reshape_position != MaxSector &&
            pers->start_reshape == NULL) {
                /* This personality cannot handle reshaping... */
                module_put(pers->owner);
                err = -EINVAL;
                goto abort;
        }

        if (pers->sync_request) {
                /* Warn if this is a potentially silly
                 * configuration.
                 */
                char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
                struct md_rdev *rdev2;
                int warned = 0;

                rdev_for_each(rdev, mddev)
                        rdev_for_each(rdev2, mddev) {
                                if (rdev < rdev2 &&
                                    rdev->bdev->bd_disk ==
                                    rdev2->bdev->bd_disk) {
                                        pr_warn("%s: WARNING: %s appears to be on the same physical disk as %s.\n",
                                                mdname(mddev),
                                                bdevname(rdev->bdev,b),
                                                bdevname(rdev2->bdev,b2));
                                        warned = 1;
                                }
                        }

                if (warned)
                        pr_warn("True protection against single-disk failure might be compromised.\n");
        }

        mddev->recovery = 0;
        /* may be over-ridden by personality */
        mddev->resync_max_sectors = mddev->dev_sectors;

        mddev->ok_start_degraded = start_dirty_degraded;

        if (start_readonly && mddev->ro == 0)
                mddev->ro = 2; /* read-only, but switch on first write */

        err = pers->run(mddev);
        if (err)
                pr_warn("md: pers->run() failed ...\n");
        else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {
                WARN_ONCE(!mddev->external_size,
                          "%s: default size too small, but 'external_size' not in effect?\n",
                          __func__);
                pr_warn("md: invalid array_size %llu > default size %llu\n",
                        (unsigned long long)mddev->array_sectors / 2,
                        (unsigned long long)pers->size(mddev, 0, 0) / 2);
                err = -EINVAL;
        }
        if (err == 0 && pers->sync_request &&
            (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
                struct bitmap *bitmap;

                bitmap = md_bitmap_create(mddev, -1);
                if (IS_ERR(bitmap)) {
                        err = PTR_ERR(bitmap);
                        pr_warn("%s: failed to create bitmap (%d)\n",
                                mdname(mddev), err);
                } else
                        mddev->bitmap = bitmap;

        }
        if (err)
                goto bitmap_abort;

        if (mddev->bitmap_info.max_write_behind > 0) {
                bool create_pool = false;

                rdev_for_each(rdev, mddev) {
                        if (test_bit(WriteMostly, &rdev->flags) &&
                            rdev_init_serial(rdev))
                                create_pool = true;
                }
                if (create_pool && mddev->serial_info_pool == NULL) {
                        mddev->serial_info_pool =
                                mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
                                                    sizeof(struct serial_info));
                        if (!mddev->serial_info_pool) {
                                err = -ENOMEM;
                                goto bitmap_abort;
                        }
                }
        }

        if (mddev->queue) {
                bool nonrot = true;

                rdev_for_each(rdev, mddev) {
                        if (rdev->raid_disk >= 0 &&
                            !blk_queue_nonrot(bdev_get_queue(rdev->bdev))) {
                                nonrot = false;
                                break;
                        }
                }
                if (mddev->degraded)
                        nonrot = false;
                if (nonrot)
                        blk_queue_flag_set(QUEUE_FLAG_NONROT, mddev->queue);
                else
                        blk_queue_flag_clear(QUEUE_FLAG_NONROT, mddev->queue);
        }
        if (pers->sync_request) {
                if (mddev->kobj.sd &&
                    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
                        pr_warn("md: cannot register extra attributes for %s\n",
                                mdname(mddev));
                mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
                mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
                mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
        } else if (mddev->ro == 2) /* auto-readonly not meaningful */
                mddev->ro = 0;

        atomic_set(&mddev->max_corr_read_errors,
                   MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
        mddev->safemode = 0;
        if (mddev_is_clustered(mddev))
                mddev->safemode_delay = 0;
        else
                mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
        mddev->in_sync = 1;
        smp_wmb();
        spin_lock(&mddev->lock);
        mddev->pers = pers;
        spin_unlock(&mddev->lock);
        rdev_for_each(rdev, mddev)
                if (rdev->raid_disk >= 0)
                        sysfs_link_rdev(mddev, rdev); /* failure here is OK */

        if (mddev->degraded && !mddev->ro)
                /* This ensures that recovering status is reported immediately
                 * via sysfs - until a lack of spares is confirmed.
                 */
                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

        if (mddev->sb_flags)
                md_update_sb(mddev, 0);

        md_new_event(mddev);
        return 0;

bitmap_abort:
        mddev_detach(mddev);
        if (mddev->private)
                pers->free(mddev, mddev->private);
        mddev->private = NULL;
        module_put(pers->owner);
        md_bitmap_destroy(mddev);
abort:
        bioset_exit(&mddev->bio_set);
        bioset_exit(&mddev->sync_set);
        return err;
}
EXPORT_SYMBOL_GPL(md_run);

int do_md_run(struct mddev *mddev)
{
        int err;

        set_bit(MD_NOT_READY, &mddev->flags);
        err = md_run(mddev);
        if (err)
                goto out;
        err = md_bitmap_load(mddev);
        if (err) {
                md_bitmap_destroy(mddev);
                goto out;
        }

        if (mddev_is_clustered(mddev))
                md_allow_write(mddev);

        /* run start up tasks that require md_thread */
        md_start(mddev);

        md_wakeup_thread(mddev->thread);
        md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */

        set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
        clear_bit(MD_NOT_READY, &mddev->flags);
        mddev->changed = 1;
        kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
        sysfs_notify_dirent_safe(mddev->sysfs_state);
        sysfs_notify_dirent_safe(mddev->sysfs_action);
        sysfs_notify_dirent_safe(mddev->sysfs_degraded);
out:
        clear_bit(MD_NOT_READY, &mddev->flags);
        return err;
}

int md_start(struct mddev *mddev)
{
        int ret = 0;

        if (mddev->pers->start) {
                set_bit(MD_RECOVERY_WAIT, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
                ret = mddev->pers->start(mddev);
                clear_bit(MD_RECOVERY_WAIT, &mddev->recovery);
                md_wakeup_thread(mddev->sync_thread);
        }
        return ret;
}
EXPORT_SYMBOL_GPL(md_start);

static int restart_array(struct mddev *mddev)
{
        struct gendisk *disk = mddev->gendisk;
        struct md_rdev *rdev;
        bool has_journal = false;
        bool has_readonly = false;

        /* Complain if it has no devices */
        if (list_empty(&mddev->disks))
                return -ENXIO;
        if (!mddev->pers)
                return -EINVAL;
        if (!mddev->ro)
                return -EBUSY;

        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev) {
                if (test_bit(Journal, &rdev->flags) &&
                    !test_bit(Faulty, &rdev->flags))
                        has_journal = true;
                if (rdev_read_only(rdev))
                        has_readonly = true;
        }
        rcu_read_unlock();
        if (test_bit(MD_HAS_JOURNAL, &mddev->flags) && !has_journal)
                /* Don't restart rw with journal missing/faulty */
                        return -EINVAL;
        if (has_readonly)
                return -EROFS;

        mddev->safemode = 0;
        mddev->ro = 0;
        set_disk_ro(disk, 0);
        pr_debug("md: %s switched to read-write mode.\n", mdname(mddev));
        /* Kick recovery or resync if necessary */
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        md_wakeup_thread(mddev->sync_thread);
        sysfs_notify_dirent_safe(mddev->sysfs_state);
        return 0;
}

static void md_clean(struct mddev *mddev)
{
        mddev->array_sectors = 0;
        mddev->external_size = 0;
        mddev->dev_sectors = 0;
        mddev->raid_disks = 0;
        mddev->recovery_cp = 0;
        mddev->resync_min = 0;
        mddev->resync_max = MaxSector;
        mddev->reshape_position = MaxSector;
        mddev->external = 0;
        mddev->persistent = 0;
        mddev->level = LEVEL_NONE;
        mddev->clevel[0] = 0;
        mddev->flags = 0;
        mddev->sb_flags = 0;
        mddev->ro = 0;
        mddev->metadata_type[0] = 0;
        mddev->chunk_sectors = 0;
        mddev->ctime = mddev->utime = 0;
        mddev->layout = 0;
        mddev->max_disks = 0;
        mddev->events = 0;
        mddev->can_decrease_events = 0;
        mddev->delta_disks = 0;
        mddev->reshape_backwards = 0;
        mddev->new_level = LEVEL_NONE;
        mddev->new_layout = 0;
        mddev->new_chunk_sectors = 0;
        mddev->curr_resync = 0;
        atomic64_set(&mddev->resync_mismatches, 0);
        mddev->suspend_lo = mddev->suspend_hi = 0;
        mddev->sync_speed_min = mddev->sync_speed_max = 0;
        mddev->recovery = 0;
        mddev->in_sync = 0;
        mddev->changed = 0;
        mddev->degraded = 0;
        mddev->safemode = 0;
        mddev->private = NULL;
        mddev->cluster_info = NULL;
        mddev->bitmap_info.offset = 0;
        mddev->bitmap_info.default_offset = 0;
        mddev->bitmap_info.default_space = 0;
        mddev->bitmap_info.chunksize = 0;
        mddev->bitmap_info.daemon_sleep = 0;
        mddev->bitmap_info.max_write_behind = 0;
        mddev->bitmap_info.nodes = 0;
}

static void __md_stop_writes(struct mddev *mddev)
{
        set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
        if (work_pending(&mddev->del_work))
                flush_workqueue(md_misc_wq);
        if (mddev->sync_thread) {
                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                md_reap_sync_thread(mddev);
        }

        del_timer_sync(&mddev->safemode_timer);

        if (mddev->pers && mddev->pers->quiesce) {
                mddev->pers->quiesce(mddev, 1);
                mddev->pers->quiesce(mddev, 0);
        }
        md_bitmap_flush(mddev);

        if (mddev->ro == 0 &&
            ((!mddev->in_sync && !mddev_is_clustered(mddev)) ||
             mddev->sb_flags)) {
                /* mark array as shutdown cleanly */
                if (!mddev_is_clustered(mddev))
                        mddev->in_sync = 1;
                md_update_sb(mddev, 1);
        }
        /* disable policy to guarantee rdevs free resources for serialization */
        mddev->serialize_policy = 0;
        mddev_destroy_serial_pool(mddev, NULL, true);
}

void md_stop_writes(struct mddev *mddev)
{
        mddev_lock_nointr(mddev);
        __md_stop_writes(mddev);
        mddev_unlock(mddev);
}
EXPORT_SYMBOL_GPL(md_stop_writes);

static void mddev_detach(struct mddev *mddev)
{
        md_bitmap_wait_behind_writes(mddev);
        if (mddev->pers && mddev->pers->quiesce && !mddev->suspended) {
                mddev->pers->quiesce(mddev, 1);
                mddev->pers->quiesce(mddev, 0);
        }
        md_unregister_thread(&mddev->thread);
        if (mddev->queue)
                blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
}

static void __md_stop(struct mddev *mddev)
{
        struct md_personality *pers = mddev->pers;
        md_bitmap_destroy(mddev);
        mddev_detach(mddev);
        /* Ensure ->event_work is done */
        if (mddev->event_work.func)
                flush_workqueue(md_misc_wq);
        spin_lock(&mddev->lock);
        mddev->pers = NULL;
        spin_unlock(&mddev->lock);
        pers->free(mddev, mddev->private);
        mddev->private = NULL;
        if (pers->sync_request && mddev->to_remove == NULL)
                mddev->to_remove = &md_redundancy_group;
        module_put(pers->owner);
        clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
}

void md_stop(struct mddev *mddev)
{
        /* stop the array and free an attached data structures.
         * This is called from dm-raid
         */
        __md_stop(mddev);
        bioset_exit(&mddev->bio_set);
        bioset_exit(&mddev->sync_set);
}

EXPORT_SYMBOL_GPL(md_stop);

static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
{
        int err = 0;
        int did_freeze = 0;

        if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
                did_freeze = 1;
                set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
        }
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
        if (mddev->sync_thread)
                /* Thread might be blocked waiting for metadata update
                 * which will now never happen */
                wake_up_process(mddev->sync_thread->tsk);

        if (mddev->external && test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
                return -EBUSY;
        mddev_unlock(mddev);
        wait_event(resync_wait, !test_bit(MD_RECOVERY_RUNNING,
                                          &mddev->recovery));
        wait_event(mddev->sb_wait,
                   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
        mddev_lock_nointr(mddev);

        mutex_lock(&mddev->open_mutex);
        if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
            mddev->sync_thread ||
            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
                pr_warn("md: %s still in use.\n",mdname(mddev));
                if (did_freeze) {
                        clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        md_wakeup_thread(mddev->thread);
                }
                err = -EBUSY;
                goto out;
        }
        if (mddev->pers) {
                __md_stop_writes(mddev);

                err  = -ENXIO;
                if (mddev->ro==1)
                        goto out;
                mddev->ro = 1;
                set_disk_ro(mddev->gendisk, 1);
                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
                sysfs_notify_dirent_safe(mddev->sysfs_state);
                err = 0;
        }
out:
        mutex_unlock(&mddev->open_mutex);
        return err;
}

/* mode:
 *   0 - completely stop and dis-assemble array
 *   2 - stop but do not disassemble array
 */
static int do_md_stop(struct mddev *mddev, int mode,
                      struct block_device *bdev)
{
        struct gendisk *disk = mddev->gendisk;
        struct md_rdev *rdev;
        int did_freeze = 0;

        if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
                did_freeze = 1;
                set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
        }
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
        if (mddev->sync_thread)
                /* Thread might be blocked waiting for metadata update
                 * which will now never happen */
                wake_up_process(mddev->sync_thread->tsk);

        mddev_unlock(mddev);
        wait_event(resync_wait, (mddev->sync_thread == NULL &&
                                 !test_bit(MD_RECOVERY_RUNNING,
                                           &mddev->recovery)));
        mddev_lock_nointr(mddev);

        mutex_lock(&mddev->open_mutex);
        if ((mddev->pers && atomic_read(&mddev->openers) > !!bdev) ||
            mddev->sysfs_active ||
            mddev->sync_thread ||
            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
                pr_warn("md: %s still in use.\n",mdname(mddev));
                mutex_unlock(&mddev->open_mutex);
                if (did_freeze) {
                        clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        md_wakeup_thread(mddev->thread);
                }
                return -EBUSY;
        }
        if (mddev->pers) {
                if (mddev->ro)
                        set_disk_ro(disk, 0);

                __md_stop_writes(mddev);
                __md_stop(mddev);

                /* tell userspace to handle 'inactive' */
                sysfs_notify_dirent_safe(mddev->sysfs_state);

                rdev_for_each(rdev, mddev)
                        if (rdev->raid_disk >= 0)
                                sysfs_unlink_rdev(mddev, rdev);

                set_capacity_and_notify(disk, 0);
                mutex_unlock(&mddev->open_mutex);
                mddev->changed = 1;

                if (mddev->ro)
                        mddev->ro = 0;
        } else
                mutex_unlock(&mddev->open_mutex);
        /*
         * Free resources if final stop
         */
        if (mode == 0) {
                pr_info("md: %s stopped.\n", mdname(mddev));

                if (mddev->bitmap_info.file) {
                        struct file *f = mddev->bitmap_info.file;
                        spin_lock(&mddev->lock);
                        mddev->bitmap_info.file = NULL;
                        spin_unlock(&mddev->lock);
                        fput(f);
                }
                mddev->bitmap_info.offset = 0;

                export_array(mddev);

                md_clean(mddev);
                if (mddev->hold_active == UNTIL_STOP)
                        mddev->hold_active = 0;
        }
        md_new_event(mddev);
        sysfs_notify_dirent_safe(mddev->sysfs_state);
        return 0;
}

#ifndef MODULE
static void autorun_array(struct mddev *mddev)
{
        struct md_rdev *rdev;
        int err;

        if (list_empty(&mddev->disks))
                return;

        pr_info("md: running: ");

        rdev_for_each(rdev, mddev) {
                char b[BDEVNAME_SIZE];
                pr_cont("<%s>", bdevname(rdev->bdev,b));
        }
        pr_cont("\n");

        err = do_md_run(mddev);
        if (err) {
                pr_warn("md: do_md_run() returned %d\n", err);
                do_md_stop(mddev, 0, NULL);
        }
}

/*
 * lets try to run arrays based on all disks that have arrived
 * until now. (those are in pending_raid_disks)
 *
 * the method: pick the first pending disk, collect all disks with
 * the same UUID, remove all from the pending list and put them into
 * the 'same_array' list. Then order this list based on superblock
 * update time (freshest comes first), kick out 'old' disks and
 * compare superblocks. If everything's fine then run it.
 *
 * If "unit" is allocated, then bump its reference count
 */
static void autorun_devices(int part)
{
        struct md_rdev *rdev0, *rdev, *tmp;
        struct mddev *mddev;
        char b[BDEVNAME_SIZE];

        pr_info("md: autorun ...\n");
        while (!list_empty(&pending_raid_disks)) {
                int unit;
                dev_t dev;
                LIST_HEAD(candidates);
                rdev0 = list_entry(pending_raid_disks.next,
                                         struct md_rdev, same_set);

                pr_debug("md: considering %s ...\n", bdevname(rdev0->bdev,b));
                INIT_LIST_HEAD(&candidates);
                rdev_for_each_list(rdev, tmp, &pending_raid_disks)
                        if (super_90_load(rdev, rdev0, 0) >= 0) {
                                pr_debug("md:  adding %s ...\n",
                                         bdevname(rdev->bdev,b));
                                list_move(&rdev->same_set, &candidates);
                        }
                /*
                 * now we have a set of devices, with all of them having
                 * mostly sane superblocks. It's time to allocate the
                 * mddev.
                 */
                if (part) {
                        dev = MKDEV(mdp_major,
                                    rdev0->preferred_minor << MdpMinorShift);
                        unit = MINOR(dev) >> MdpMinorShift;
                } else {
                        dev = MKDEV(MD_MAJOR, rdev0->preferred_minor);
                        unit = MINOR(dev);
                }
                if (rdev0->preferred_minor != unit) {
                        pr_warn("md: unit number in %s is bad: %d\n",
                                bdevname(rdev0->bdev, b), rdev0->preferred_minor);
                        break;
                }

                md_probe(dev);
                mddev = mddev_find(dev);
                if (!mddev)
                        break;

                if (mddev_lock(mddev))
                        pr_warn("md: %s locked, cannot run\n", mdname(mddev));
                else if (mddev->raid_disks || mddev->major_version
                         || !list_empty(&mddev->disks)) {
                        pr_warn("md: %s already running, cannot run %s\n",
                                mdname(mddev), bdevname(rdev0->bdev,b));
                        mddev_unlock(mddev);
                } else {
                        pr_debug("md: created %s\n", mdname(mddev));
                        mddev->persistent = 1;
                        rdev_for_each_list(rdev, tmp, &candidates) {
                                list_del_init(&rdev->same_set);
                                if (bind_rdev_to_array(rdev, mddev))
                                        export_rdev(rdev);
                        }
                        autorun_array(mddev);
                        mddev_unlock(mddev);
                }
                /* on success, candidates will be empty, on error
                 * it won't...
                 */
                rdev_for_each_list(rdev, tmp, &candidates) {
                        list_del_init(&rdev->same_set);
                        export_rdev(rdev);
                }
                mddev_put(mddev);
        }
        pr_info("md: ... autorun DONE.\n");
}
#endif /* !MODULE */

static int get_version(void __user *arg)
{
        mdu_version_t ver;

        ver.major = MD_MAJOR_VERSION;
        ver.minor = MD_MINOR_VERSION;
        ver.patchlevel = MD_PATCHLEVEL_VERSION;

        if (copy_to_user(arg, &ver, sizeof(ver)))
                return -EFAULT;

        return 0;
}

static int get_array_info(struct mddev *mddev, void __user *arg)
{
        mdu_array_info_t info;
        int nr,working,insync,failed,spare;
        struct md_rdev *rdev;

        nr = working = insync = failed = spare = 0;
        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev) {
                nr++;
                if (test_bit(Faulty, &rdev->flags))
                        failed++;
                else {
                        working++;
                        if (test_bit(In_sync, &rdev->flags))
                                insync++;
                        else if (test_bit(Journal, &rdev->flags))
                                /* TODO: add journal count to md_u.h */
                                ;
                        else
                                spare++;
                }
        }
        rcu_read_unlock();

        info.major_version = mddev->major_version;
        info.minor_version = mddev->minor_version;
        info.patch_version = MD_PATCHLEVEL_VERSION;
        info.ctime         = clamp_t(time64_t, mddev->ctime, 0, U32_MAX);
        info.level         = mddev->level;
        info.size          = mddev->dev_sectors / 2;
        if (info.size != mddev->dev_sectors / 2) /* overflow */
                info.size = -1;
        info.nr_disks      = nr;
        info.raid_disks    = mddev->raid_disks;
        info.md_minor      = mddev->md_minor;
        info.not_persistent= !mddev->persistent;

        info.utime         = clamp_t(time64_t, mddev->utime, 0, U32_MAX);
        info.state         = 0;
        if (mddev->in_sync)
                info.state = (1<<MD_SB_CLEAN);
        if (mddev->bitmap && mddev->bitmap_info.offset)
                info.state |= (1<<MD_SB_BITMAP_PRESENT);
        if (mddev_is_clustered(mddev))
                info.state |= (1<<MD_SB_CLUSTERED);
        info.active_disks  = insync;
        info.working_disks = working;
        info.failed_disks  = failed;
        info.spare_disks   = spare;

        info.layout        = mddev->layout;
        info.chunk_size    = mddev->chunk_sectors << 9;

        if (copy_to_user(arg, &info, sizeof(info)))
                return -EFAULT;

        return 0;
}

static int get_bitmap_file(struct mddev *mddev, void __user * arg)
{
        mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
        char *ptr;
        int err;

        file = kzalloc(sizeof(*file), GFP_NOIO);
        if (!file)
                return -ENOMEM;

        err = 0;
        spin_lock(&mddev->lock);
        /* bitmap enabled */
        if (mddev->bitmap_info.file) {
                ptr = file_path(mddev->bitmap_info.file, file->pathname,
                                sizeof(file->pathname));
                if (IS_ERR(ptr))
                        err = PTR_ERR(ptr);
                else
                        memmove(file->pathname, ptr,
                                sizeof(file->pathname)-(ptr-file->pathname));
        }
        spin_unlock(&mddev->lock);

        if (err == 0 &&
            copy_to_user(arg, file, sizeof(*file)))
                err = -EFAULT;

        kfree(file);
        return err;
}

static int get_disk_info(struct mddev *mddev, void __user * arg)
{
        mdu_disk_info_t info;
        struct md_rdev *rdev;

        if (copy_from_user(&info, arg, sizeof(info)))
                return -EFAULT;

        rcu_read_lock();
        rdev = md_find_rdev_nr_rcu(mddev, info.number);
        if (rdev) {
                info.major = MAJOR(rdev->bdev->bd_dev);
                info.minor = MINOR(rdev->bdev->bd_dev);
                info.raid_disk = rdev->raid_disk;
                info.state = 0;
                if (test_bit(Faulty, &rdev->flags))
                        info.state |= (1<<MD_DISK_FAULTY);
                else if (test_bit(In_sync, &rdev->flags)) {
                        info.state |= (1<<MD_DISK_ACTIVE);
                        info.state |= (1<<MD_DISK_SYNC);
                }
                if (test_bit(Journal, &rdev->flags))
                        info.state |= (1<<MD_DISK_JOURNAL);
                if (test_bit(WriteMostly, &rdev->flags))
                        info.state |= (1<<MD_DISK_WRITEMOSTLY);
                if (test_bit(FailFast, &rdev->flags))
                        info.state |= (1<<MD_DISK_FAILFAST);
        } else {
                info.major = info.minor = 0;
                info.raid_disk = -1;
                info.state = (1<<MD_DISK_REMOVED);
        }
        rcu_read_unlock();

        if (copy_to_user(arg, &info, sizeof(info)))
                return -EFAULT;

        return 0;
}

int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info)
{
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
        struct md_rdev *rdev;
        dev_t dev = MKDEV(info->major,info->minor);

        if (mddev_is_clustered(mddev) &&
                !(info->state & ((1 << MD_DISK_CLUSTER_ADD) | (1 << MD_DISK_CANDIDATE)))) {
                pr_warn("%s: Cannot add to clustered mddev.\n",
                        mdname(mddev));
                return -EINVAL;
        }

        if (info->major != MAJOR(dev) || info->minor != MINOR(dev))
                return -EOVERFLOW;

        if (!mddev->raid_disks) {
                int err;
                /* expecting a device which has a superblock */
                rdev = md_import_device(dev, mddev->major_version, mddev->minor_version);
                if (IS_ERR(rdev)) {
                        pr_warn("md: md_import_device returned %ld\n",
                                PTR_ERR(rdev));
                        return PTR_ERR(rdev);
                }
                if (!list_empty(&mddev->disks)) {
                        struct md_rdev *rdev0
                                = list_entry(mddev->disks.next,
                                             struct md_rdev, same_set);
                        err = super_types[mddev->major_version]
                                .load_super(rdev, rdev0, mddev->minor_version);
                        if (err < 0) {
                                pr_warn("md: %s has different UUID to %s\n",
                                        bdevname(rdev->bdev,b),
                                        bdevname(rdev0->bdev,b2));
                                export_rdev(rdev);
                                return -EINVAL;
                        }
                }
                err = bind_rdev_to_array(rdev, mddev);
                if (err)
                        export_rdev(rdev);
                return err;
        }

        /*
         * md_add_new_disk can be used once the array is assembled
         * to add "hot spares".  They must already have a superblock
         * written
         */
        if (mddev->pers) {
                int err;
                if (!mddev->pers->hot_add_disk) {
                        pr_warn("%s: personality does not support diskops!\n",
                                mdname(mddev));
                        return -EINVAL;
                }
                if (mddev->persistent)
                        rdev = md_import_device(dev, mddev->major_version,
                                                mddev->minor_version);
                else
                        rdev = md_import_device(dev, -1, -1);
                if (IS_ERR(rdev)) {
                        pr_warn("md: md_import_device returned %ld\n",
                                PTR_ERR(rdev));
                        return PTR_ERR(rdev);
                }
                /* set saved_raid_disk if appropriate */
                if (!mddev->persistent) {
                        if (info->state & (1<<MD_DISK_SYNC)  &&
                            info->raid_disk < mddev->raid_disks) {
                                rdev->raid_disk = info->raid_disk;
                                set_bit(In_sync, &rdev->flags);
                                clear_bit(Bitmap_sync, &rdev->flags);
                        } else
                                rdev->raid_disk = -1;
                        rdev->saved_raid_disk = rdev->raid_disk;
                } else
                        super_types[mddev->major_version].
                                validate_super(mddev, rdev);
                if ((info->state & (1<<MD_DISK_SYNC)) &&
                     rdev->raid_disk != info->raid_disk) {
                        /* This was a hot-add request, but events doesn't
                         * match, so reject it.
                         */
                        export_rdev(rdev);
                        return -EINVAL;
                }

                clear_bit(In_sync, &rdev->flags); /* just to be sure */
                if (info->state & (1<<MD_DISK_WRITEMOSTLY))
                        set_bit(WriteMostly, &rdev->flags);
                else
                        clear_bit(WriteMostly, &rdev->flags);
                if (info->state & (1<<MD_DISK_FAILFAST))
                        set_bit(FailFast, &rdev->flags);
                else
                        clear_bit(FailFast, &rdev->flags);

                if (info->state & (1<<MD_DISK_JOURNAL)) {
                        struct md_rdev *rdev2;
                        bool has_journal = false;

                        /* make sure no existing journal disk */
                        rdev_for_each(rdev2, mddev) {
                                if (test_bit(Journal, &rdev2->flags)) {
                                        has_journal = true;
                                        break;
                                }
                        }
                        if (has_journal || mddev->bitmap) {
                                export_rdev(rdev);
                                return -EBUSY;
                        }
                        set_bit(Journal, &rdev->flags);
                }
                /*
                 * check whether the device shows up in other nodes
                 */
                if (mddev_is_clustered(mddev)) {
                        if (info->state & (1 << MD_DISK_CANDIDATE))
                                set_bit(Candidate, &rdev->flags);
                        else if (info->state & (1 << MD_DISK_CLUSTER_ADD)) {
                                /* --add initiated by this node */
                                err = md_cluster_ops->add_new_disk(mddev, rdev);
                                if (err) {
                                        export_rdev(rdev);
                                        return err;
                                }
                        }
                }

                rdev->raid_disk = -1;
                err = bind_rdev_to_array(rdev, mddev);

                if (err)
                        export_rdev(rdev);

                if (mddev_is_clustered(mddev)) {
                        if (info->state & (1 << MD_DISK_CANDIDATE)) {
                                if (!err) {
                                        err = md_cluster_ops->new_disk_ack(mddev,
                                                err == 0);
                                        if (err)
                                                md_kick_rdev_from_array(rdev);
                                }
                        } else {
                                if (err)
                                        md_cluster_ops->add_new_disk_cancel(mddev);
                                else
                                        err = add_bound_rdev(rdev);
                        }

                } else if (!err)
                        err = add_bound_rdev(rdev);

                return err;
        }

        /* otherwise, md_add_new_disk is only allowed
         * for major_version==0 superblocks
         */
        if (mddev->major_version != 0) {
                pr_warn("%s: ADD_NEW_DISK not supported\n", mdname(mddev));
                return -EINVAL;
        }

        if (!(info->state & (1<<MD_DISK_FAULTY))) {
                int err;
                rdev = md_import_device(dev, -1, 0);
                if (IS_ERR(rdev)) {
                        pr_warn("md: error, md_import_device() returned %ld\n",
                                PTR_ERR(rdev));
                        return PTR_ERR(rdev);
                }
                rdev->desc_nr = info->number;
                if (info->raid_disk < mddev->raid_disks)
                        rdev->raid_disk = info->raid_disk;
                else
                        rdev->raid_disk = -1;

                if (rdev->raid_disk < mddev->raid_disks)
                        if (info->state & (1<<MD_DISK_SYNC))
                                set_bit(In_sync, &rdev->flags);

                if (info->state & (1<<MD_DISK_WRITEMOSTLY))
                        set_bit(WriteMostly, &rdev->flags);
                if (info->state & (1<<MD_DISK_FAILFAST))
                        set_bit(FailFast, &rdev->flags);

                if (!mddev->persistent) {
                        pr_debug("md: nonpersistent superblock ...\n");
                        rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
                } else
                        rdev->sb_start = calc_dev_sboffset(rdev);
                rdev->sectors = rdev->sb_start;

                err = bind_rdev_to_array(rdev, mddev);
                if (err) {
                        export_rdev(rdev);
                        return err;
                }
        }

        return 0;
}

static int hot_remove_disk(struct mddev *mddev, dev_t dev)
{
        char b[BDEVNAME_SIZE];
        struct md_rdev *rdev;

        if (!mddev->pers)
                return -ENODEV;

        rdev = find_rdev(mddev, dev);
        if (!rdev)
                return -ENXIO;

        if (rdev->raid_disk < 0)
                goto kick_rdev;

        clear_bit(Blocked, &rdev->flags);
        remove_and_add_spares(mddev, rdev);

        if (rdev->raid_disk >= 0)
                goto busy;

kick_rdev:
        if (mddev_is_clustered(mddev)) {
                if (md_cluster_ops->remove_disk(mddev, rdev))
                        goto busy;
        }

        md_kick_rdev_from_array(rdev);
        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
        if (mddev->thread)
                md_wakeup_thread(mddev->thread);
        else
                md_update_sb(mddev, 1);
        md_new_event(mddev);

        return 0;
busy:
        pr_debug("md: cannot remove active disk %s from %s ...\n",
                 bdevname(rdev->bdev,b), mdname(mddev));
        return -EBUSY;
}

static int hot_add_disk(struct mddev *mddev, dev_t dev)
{
        char b[BDEVNAME_SIZE];
        int err;
        struct md_rdev *rdev;

        if (!mddev->pers)
                return -ENODEV;

        if (mddev->major_version != 0) {
                pr_warn("%s: HOT_ADD may only be used with version-0 superblocks.\n",
                        mdname(mddev));
                return -EINVAL;
        }
        if (!mddev->pers->hot_add_disk) {
                pr_warn("%s: personality does not support diskops!\n",
                        mdname(mddev));
                return -EINVAL;
        }

        rdev = md_import_device(dev, -1, 0);
        if (IS_ERR(rdev)) {
                pr_warn("md: error, md_import_device() returned %ld\n",
                        PTR_ERR(rdev));
                return -EINVAL;
        }

        if (mddev->persistent)
                rdev->sb_start = calc_dev_sboffset(rdev);
        else
                rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;

        rdev->sectors = rdev->sb_start;

        if (test_bit(Faulty, &rdev->flags)) {
                pr_warn("md: can not hot-add faulty %s disk to %s!\n",
                        bdevname(rdev->bdev,b), mdname(mddev));
                err = -EINVAL;
                goto abort_export;
        }

        clear_bit(In_sync, &rdev->flags);
        rdev->desc_nr = -1;
        rdev->saved_raid_disk = -1;
        err = bind_rdev_to_array(rdev, mddev);
        if (err)
                goto abort_export;

        /*
         * The rest should better be atomic, we can have disk failures
         * noticed in interrupt contexts ...
         */

        rdev->raid_disk = -1;

        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
        if (!mddev->thread)
                md_update_sb(mddev, 1);
        /*
         * Kick recovery, maybe this spare has to be added to the
         * array immediately.
         */
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        md_new_event(mddev);
        return 0;

abort_export:
        export_rdev(rdev);
        return err;
}

static int set_bitmap_file(struct mddev *mddev, int fd)
{
        int err = 0;

        if (mddev->pers) {
                if (!mddev->pers->quiesce || !mddev->thread)
                        return -EBUSY;
                if (mddev->recovery || mddev->sync_thread)
                        return -EBUSY;
                /* we should be able to change the bitmap.. */
        }

        if (fd >= 0) {
                struct inode *inode;
                struct file *f;

                if (mddev->bitmap || mddev->bitmap_info.file)
                        return -EEXIST; /* cannot add when bitmap is present */
                f = fget(fd);

                if (f == NULL) {
                        pr_warn("%s: error: failed to get bitmap file\n",
                                mdname(mddev));
                        return -EBADF;
                }

                inode = f->f_mapping->host;
                if (!S_ISREG(inode->i_mode)) {
                        pr_warn("%s: error: bitmap file must be a regular file\n",
                                mdname(mddev));
                        err = -EBADF;
                } else if (!(f->f_mode & FMODE_WRITE)) {
                        pr_warn("%s: error: bitmap file must open for write\n",
                                mdname(mddev));
                        err = -EBADF;
                } else if (atomic_read(&inode->i_writecount) != 1) {
                        pr_warn("%s: error: bitmap file is already in use\n",
                                mdname(mddev));
                        err = -EBUSY;
                }
                if (err) {
                        fput(f);
                        return err;
                }
                mddev->bitmap_info.file = f;
                mddev->bitmap_info.offset = 0; /* file overrides offset */
        } else if (mddev->bitmap == NULL)
                return -ENOENT; /* cannot remove what isn't there */
        err = 0;
        if (mddev->pers) {
                if (fd >= 0) {
                        struct bitmap *bitmap;

                        bitmap = md_bitmap_create(mddev, -1);
                        mddev_suspend(mddev);
                        if (!IS_ERR(bitmap)) {
                                mddev->bitmap = bitmap;
                                err = md_bitmap_load(mddev);
                        } else
                                err = PTR_ERR(bitmap);
                        if (err) {
                                md_bitmap_destroy(mddev);
                                fd = -1;
                        }
                        mddev_resume(mddev);
                } else if (fd < 0) {
                        mddev_suspend(mddev);
                        md_bitmap_destroy(mddev);
                        mddev_resume(mddev);
                }
        }
        if (fd < 0) {
                struct file *f = mddev->bitmap_info.file;
                if (f) {
                        spin_lock(&mddev->lock);
                        mddev->bitmap_info.file = NULL;
                        spin_unlock(&mddev->lock);
                        fput(f);
                }
        }

        return err;
}

/*
 * md_set_array_info is used two different ways
 * The original usage is when creating a new array.
 * In this usage, raid_disks is > 0 and it together with
 *  level, size, not_persistent,layout,chunksize determine the
 *  shape of the array.
 *  This will always create an array with a type-0.90.0 superblock.
 * The newer usage is when assembling an array.
 *  In this case raid_disks will be 0, and the major_version field is
 *  use to determine which style super-blocks are to be found on the devices.
 *  The minor and patch _version numbers are also kept incase the
 *  super_block handler wishes to interpret them.
 */
int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info)
{
        if (info->raid_disks == 0) {
                /* just setting version number for superblock loading */
                if (info->major_version < 0 ||
                    info->major_version >= ARRAY_SIZE(super_types) ||
                    super_types[info->major_version].name == NULL) {
                        /* maybe try to auto-load a module? */
                        pr_warn("md: superblock version %d not known\n",
                                info->major_version);
                        return -EINVAL;
                }
                mddev->major_version = info->major_version;
                mddev->minor_version = info->minor_version;
                mddev->patch_version = info->patch_version;
                mddev->persistent = !info->not_persistent;
                /* ensure mddev_put doesn't delete this now that there
                 * is some minimal configuration.
                 */
                mddev->ctime         = ktime_get_real_seconds();
                return 0;
        }
        mddev->major_version = MD_MAJOR_VERSION;
        mddev->minor_version = MD_MINOR_VERSION;
        mddev->patch_version = MD_PATCHLEVEL_VERSION;
        mddev->ctime         = ktime_get_real_seconds();

        mddev->level         = info->level;
        mddev->clevel[0]     = 0;
        mddev->dev_sectors   = 2 * (sector_t)info->size;
        mddev->raid_disks    = info->raid_disks;
        /* don't set md_minor, it is determined by which /dev/md* was
         * openned
         */
        if (info->state & (1<<MD_SB_CLEAN))
                mddev->recovery_cp = MaxSector;
        else
                mddev->recovery_cp = 0;
        mddev->persistent    = ! info->not_persistent;
        mddev->external      = 0;

        mddev->layout        = info->layout;
        if (mddev->level == 0)
                /* Cannot trust RAID0 layout info here */
                mddev->layout = -1;
        mddev->chunk_sectors = info->chunk_size >> 9;

        if (mddev->persistent) {
                mddev->max_disks = MD_SB_DISKS;
                mddev->flags = 0;
                mddev->sb_flags = 0;
        }
        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);

        mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
        mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
        mddev->bitmap_info.offset = 0;

        mddev->reshape_position = MaxSector;

        /*
         * Generate a 128 bit UUID
         */
        get_random_bytes(mddev->uuid, 16);

        mddev->new_level = mddev->level;
        mddev->new_chunk_sectors = mddev->chunk_sectors;
        mddev->new_layout = mddev->layout;
        mddev->delta_disks = 0;
        mddev->reshape_backwards = 0;

        return 0;
}

void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors)
{
        lockdep_assert_held(&mddev->reconfig_mutex);

        if (mddev->external_size)
                return;

        mddev->array_sectors = array_sectors;
}
EXPORT_SYMBOL(md_set_array_sectors);

static int update_size(struct mddev *mddev, sector_t num_sectors)
{
        struct md_rdev *rdev;
        int rv;
        int fit = (num_sectors == 0);
        sector_t old_dev_sectors = mddev->dev_sectors;

        if (mddev->pers->resize == NULL)
                return -EINVAL;
        /* The "num_sectors" is the number of sectors of each device that
         * is used.  This can only make sense for arrays with redundancy.
         * linear and raid0 always use whatever space is available. We can only
         * consider changing this number if no resync or reconstruction is
         * happening, and if the new size is acceptable. It must fit before the
         * sb_start or, if that is <data_offset, it must fit before the size
         * of each device.  If num_sectors is zero, we find the largest size
         * that fits.
         */
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
            mddev->sync_thread)
                return -EBUSY;
        if (mddev->ro)
                return -EROFS;

        rdev_for_each(rdev, mddev) {
                sector_t avail = rdev->sectors;

                if (fit && (num_sectors == 0 || num_sectors > avail))
                        num_sectors = avail;
                if (avail < num_sectors)
                        return -ENOSPC;
        }
        rv = mddev->pers->resize(mddev, num_sectors);
        if (!rv) {
                if (mddev_is_clustered(mddev))
                        md_cluster_ops->update_size(mddev, old_dev_sectors);
                else if (mddev->queue) {
                        set_capacity_and_notify(mddev->gendisk,
                                                mddev->array_sectors);
                }
        }
        return rv;
}

static int update_raid_disks(struct mddev *mddev, int raid_disks)
{
        int rv;
        struct md_rdev *rdev;
        /* change the number of raid disks */
        if (mddev->pers->check_reshape == NULL)
                return -EINVAL;
        if (mddev->ro)
                return -EROFS;
        if (raid_disks <= 0 ||
            (mddev->max_disks && raid_disks >= mddev->max_disks))
                return -EINVAL;
        if (mddev->sync_thread ||
            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
            test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) ||
            mddev->reshape_position != MaxSector)
                return -EBUSY;

        rdev_for_each(rdev, mddev) {
                if (mddev->raid_disks < raid_disks &&
                    rdev->data_offset < rdev->new_data_offset)
                        return -EINVAL;
                if (mddev->raid_disks > raid_disks &&
                    rdev->data_offset > rdev->new_data_offset)
                        return -EINVAL;
        }

        mddev->delta_disks = raid_disks - mddev->raid_disks;
        if (mddev->delta_disks < 0)
                mddev->reshape_backwards = 1;
        else if (mddev->delta_disks > 0)
                mddev->reshape_backwards = 0;

        rv = mddev->pers->check_reshape(mddev);
        if (rv < 0) {
                mddev->delta_disks = 0;
                mddev->reshape_backwards = 0;
        }
        return rv;
}

/*
 * update_array_info is used to change the configuration of an
 * on-line array.
 * The version, ctime,level,size,raid_disks,not_persistent, layout,chunk_size
 * fields in the info are checked against the array.
 * Any differences that cannot be handled will cause an error.
 * Normally, only one change can be managed at a time.
 */
static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
{
        int rv = 0;
        int cnt = 0;
        int state = 0;

        /* calculate expected state,ignoring low bits */
        if (mddev->bitmap && mddev->bitmap_info.offset)
                state |= (1 << MD_SB_BITMAP_PRESENT);

        if (mddev->major_version != info->major_version ||
            mddev->minor_version != info->minor_version ||
/*          mddev->patch_version != info->patch_version || */
            mddev->ctime         != info->ctime         ||
            mddev->level         != info->level         ||
/*          mddev->layout        != info->layout        || */
            mddev->persistent    != !info->not_persistent ||
            mddev->chunk_sectors != info->chunk_size >> 9 ||
            /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
            ((state^info->state) & 0xfffffe00)
                )
                return -EINVAL;
        /* Check there is only one change */
        if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
                cnt++;
        if (mddev->raid_disks != info->raid_disks)
                cnt++;
        if (mddev->layout != info->layout)
                cnt++;
        if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT))
                cnt++;
        if (cnt == 0)
                return 0;
        if (cnt > 1)
                return -EINVAL;

        if (mddev->layout != info->layout) {
                /* Change layout
                 * we don't need to do anything at the md level, the
                 * personality will take care of it all.
                 */
                if (mddev->pers->check_reshape == NULL)
                        return -EINVAL;
                else {
                        mddev->new_layout = info->layout;
                        rv = mddev->pers->check_reshape(mddev);
                        if (rv)
                                mddev->new_layout = mddev->layout;
                        return rv;
                }
        }
        if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
                rv = update_size(mddev, (sector_t)info->size * 2);

        if (mddev->raid_disks    != info->raid_disks)
                rv = update_raid_disks(mddev, info->raid_disks);

        if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
                if (mddev->pers->quiesce == NULL || mddev->thread == NULL) {
                        rv = -EINVAL;
                        goto err;
                }
                if (mddev->recovery || mddev->sync_thread) {
                        rv = -EBUSY;
                        goto err;
                }
                if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
                        struct bitmap *bitmap;
                        /* add the bitmap */
                        if (mddev->bitmap) {
                                rv = -EEXIST;
                                goto err;
                        }
                        if (mddev->bitmap_info.default_offset == 0) {
                                rv = -EINVAL;
                                goto err;
                        }
                        mddev->bitmap_info.offset =
                                mddev->bitmap_info.default_offset;
                        mddev->bitmap_info.space =
                                mddev->bitmap_info.default_space;
                        bitmap = md_bitmap_create(mddev, -1);
                        mddev_suspend(mddev);
                        if (!IS_ERR(bitmap)) {
                                mddev->bitmap = bitmap;
                                rv = md_bitmap_load(mddev);
                        } else
                                rv = PTR_ERR(bitmap);
                        if (rv)
                                md_bitmap_destroy(mddev);
                        mddev_resume(mddev);
                } else {
                        /* remove the bitmap */
                        if (!mddev->bitmap) {
                                rv = -ENOENT;
                                goto err;
                        }
                        if (mddev->bitmap->storage.file) {
                                rv = -EINVAL;
                                goto err;
                        }
                        if (mddev->bitmap_info.nodes) {
                                /* hold PW on all the bitmap lock */
                                if (md_cluster_ops->lock_all_bitmaps(mddev) <= 0) {
                                        pr_warn("md: can't change bitmap to none since the array is in use by more than one node\n");
                                        rv = -EPERM;
                                        md_cluster_ops->unlock_all_bitmaps(mddev);
                                        goto err;
                                }

                                mddev->bitmap_info.nodes = 0;
                                md_cluster_ops->leave(mddev);
                                module_put(md_cluster_mod);
                                mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
                        }
                        mddev_suspend(mddev);
                        md_bitmap_destroy(mddev);
                        mddev_resume(mddev);
                        mddev->bitmap_info.offset = 0;
                }
        }
        md_update_sb(mddev, 1);
        return rv;
err:
        return rv;
}

static int set_disk_faulty(struct mddev *mddev, dev_t dev)
{
        struct md_rdev *rdev;
        int err = 0;

        if (mddev->pers == NULL)
                return -ENODEV;

        rcu_read_lock();
        rdev = md_find_rdev_rcu(mddev, dev);
        if (!rdev)
                err =  -ENODEV;
        else {
                md_error(mddev, rdev);
                if (!test_bit(Faulty, &rdev->flags))
                        err = -EBUSY;
        }
        rcu_read_unlock();
        return err;
}

/*
 * We have a problem here : there is no easy way to give a CHS
 * virtual geometry. We currently pretend that we have a 2 heads
 * 4 sectors (with a BIG number of cylinders...). This drives
 * dosfs just mad... ;-)
 */
static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
        struct mddev *mddev = bdev->bd_disk->private_data;

        geo->heads = 2;
        geo->sectors = 4;
        geo->cylinders = mddev->array_sectors / 8;
        return 0;
}

static inline bool md_ioctl_valid(unsigned int cmd)
{
        switch (cmd) {
        case ADD_NEW_DISK:
        case GET_ARRAY_INFO:
        case GET_BITMAP_FILE:
        case GET_DISK_INFO:
        case HOT_ADD_DISK:
        case HOT_REMOVE_DISK:
        case RAID_VERSION:
        case RESTART_ARRAY_RW:
        case RUN_ARRAY:
        case SET_ARRAY_INFO:
        case SET_BITMAP_FILE:
        case SET_DISK_FAULTY:
        case STOP_ARRAY:
        case STOP_ARRAY_RO:
        case CLUSTERED_DISK_NACK:
                return true;
        default:
                return false;
        }
}

static int md_ioctl(struct block_device *bdev, fmode_t mode,
                        unsigned int cmd, unsigned long arg)
{
        int err = 0;
        void __user *argp = (void __user *)arg;
        struct mddev *mddev = NULL;
        bool did_set_md_closing = false;

        if (!md_ioctl_valid(cmd))
                return -ENOTTY;

        switch (cmd) {
        case RAID_VERSION:
        case GET_ARRAY_INFO:
        case GET_DISK_INFO:
                break;
        default:
                if (!capable(CAP_SYS_ADMIN))
                        return -EACCES;
        }

        /*
         * Commands dealing with the RAID driver but not any
         * particular array:
         */
        switch (cmd) {
        case RAID_VERSION:
                err = get_version(argp);
                goto out;
        default:;
        }

        /*
         * Commands creating/starting a new array:
         */

        mddev = bdev->bd_disk->private_data;

        if (!mddev) {
                BUG();
                goto out;
        }

        /* Some actions do not requires the mutex */
        switch (cmd) {
        case GET_ARRAY_INFO:
                if (!mddev->raid_disks && !mddev->external)
                        err = -ENODEV;
                else
                        err = get_array_info(mddev, argp);
                goto out;

        case GET_DISK_INFO:
                if (!mddev->raid_disks && !mddev->external)
                        err = -ENODEV;
                else
                        err = get_disk_info(mddev, argp);
                goto out;

        case SET_DISK_FAULTY:
                err = set_disk_faulty(mddev, new_decode_dev(arg));
                goto out;

        case GET_BITMAP_FILE:
                err = get_bitmap_file(mddev, argp);
                goto out;

        }

        if (cmd == ADD_NEW_DISK || cmd == HOT_ADD_DISK)
                flush_rdev_wq(mddev);

        if (cmd == HOT_REMOVE_DISK)
                /* need to ensure recovery thread has run */
                wait_event_interruptible_timeout(mddev->sb_wait,
                                                 !test_bit(MD_RECOVERY_NEEDED,
                                                           &mddev->recovery),
                                                 msecs_to_jiffies(5000));
        if (cmd == STOP_ARRAY || cmd == STOP_ARRAY_RO) {
                /* Need to flush page cache, and ensure no-one else opens
                 * and writes
                 */
                mutex_lock(&mddev->open_mutex);
                if (mddev->pers && atomic_read(&mddev->openers) > 1) {
                        mutex_unlock(&mddev->open_mutex);
                        err = -EBUSY;
                        goto out;
                }
                if (test_and_set_bit(MD_CLOSING, &mddev->flags)) {
                        mutex_unlock(&mddev->open_mutex);
                        err = -EBUSY;
                        goto out;
                }
                did_set_md_closing = true;
                mutex_unlock(&mddev->open_mutex);
                sync_blockdev(bdev);
        }
        err = mddev_lock(mddev);
        if (err) {
                pr_debug("md: ioctl lock interrupted, reason %d, cmd %d\n",
                         err, cmd);
                goto out;
        }

        if (cmd == SET_ARRAY_INFO) {
                mdu_array_info_t info;
                if (!arg)
                        memset(&info, 0, sizeof(info));
                else if (copy_from_user(&info, argp, sizeof(info))) {
                        err = -EFAULT;
                        goto unlock;
                }
                if (mddev->pers) {
                        err = update_array_info(mddev, &info);
                        if (err) {
                                pr_warn("md: couldn't update array info. %d\n", err);
                                goto unlock;
                        }
                        goto unlock;
                }
                if (!list_empty(&mddev->disks)) {
                        pr_warn("md: array %s already has disks!\n", mdname(mddev));
                        err = -EBUSY;
                        goto unlock;
                }
                if (mddev->raid_disks) {
                        pr_warn("md: array %s already initialised!\n", mdname(mddev));
                        err = -EBUSY;
                        goto unlock;
                }
                err = md_set_array_info(mddev, &info);
                if (err) {
                        pr_warn("md: couldn't set array info. %d\n", err);
                        goto unlock;
                }
                goto unlock;
        }

        /*
         * Commands querying/configuring an existing array:
         */
        /* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
         * RUN_ARRAY, and GET_ and SET_BITMAP_FILE are allowed */
        if ((!mddev->raid_disks && !mddev->external)
            && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
            && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE
            && cmd != GET_BITMAP_FILE) {
                err = -ENODEV;
                goto unlock;
        }

        /*
         * Commands even a read-only array can execute:
         */
        switch (cmd) {
        case RESTART_ARRAY_RW:
                err = restart_array(mddev);
                goto unlock;

        case STOP_ARRAY:
                err = do_md_stop(mddev, 0, bdev);
                goto unlock;

        case STOP_ARRAY_RO:
                err = md_set_readonly(mddev, bdev);
                goto unlock;

        case HOT_REMOVE_DISK:
                err = hot_remove_disk(mddev, new_decode_dev(arg));
                goto unlock;

        case ADD_NEW_DISK:
                /* We can support ADD_NEW_DISK on read-only arrays
                 * only if we are re-adding a preexisting device.
                 * So require mddev->pers and MD_DISK_SYNC.
                 */
                if (mddev->pers) {
                        mdu_disk_info_t info;
                        if (copy_from_user(&info, argp, sizeof(info)))
                                err = -EFAULT;
                        else if (!(info.state & (1<<MD_DISK_SYNC)))
                                /* Need to clear read-only for this */
                                break;
                        else
                                err = md_add_new_disk(mddev, &info);
                        goto unlock;
                }
                break;
        }

        /*
         * The remaining ioctls are changing the state of the
         * superblock, so we do not allow them on read-only arrays.
         */
        if (mddev->ro && mddev->pers) {
                if (mddev->ro == 2) {
                        mddev->ro = 0;
                        sysfs_notify_dirent_safe(mddev->sysfs_state);
                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        /* mddev_unlock will wake thread */
                        /* If a device failed while we were read-only, we
                         * need to make sure the metadata is updated now.
                         */
                        if (test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)) {
                                mddev_unlock(mddev);
                                wait_event(mddev->sb_wait,
                                           !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags) &&
                                           !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
                                mddev_lock_nointr(mddev);
                        }
                } else {
                        err = -EROFS;
                        goto unlock;
                }
        }

        switch (cmd) {
        case ADD_NEW_DISK:
        {
                mdu_disk_info_t info;
                if (copy_from_user(&info, argp, sizeof(info)))
                        err = -EFAULT;
                else
                        err = md_add_new_disk(mddev, &info);
                goto unlock;
        }

        case CLUSTERED_DISK_NACK:
                if (mddev_is_clustered(mddev))
                        md_cluster_ops->new_disk_ack(mddev, false);
                else
                        err = -EINVAL;
                goto unlock;

        case HOT_ADD_DISK:
                err = hot_add_disk(mddev, new_decode_dev(arg));
                goto unlock;

        case RUN_ARRAY:
                err = do_md_run(mddev);
                goto unlock;

        case SET_BITMAP_FILE:
                err = set_bitmap_file(mddev, (int)arg);
                goto unlock;

        default:
                err = -EINVAL;
                goto unlock;
        }

unlock:
        if (mddev->hold_active == UNTIL_IOCTL &&
            err != -EINVAL)
                mddev->hold_active = 0;
        mddev_unlock(mddev);
out:
        if(did_set_md_closing)
                clear_bit(MD_CLOSING, &mddev->flags);
        return err;
}
#ifdef CONFIG_COMPAT
static int md_compat_ioctl(struct block_device *bdev, fmode_t mode,
                    unsigned int cmd, unsigned long arg)
{
        switch (cmd) {
        case HOT_REMOVE_DISK:
        case HOT_ADD_DISK:
        case SET_DISK_FAULTY:
        case SET_BITMAP_FILE:
                /* These take in integer arg, do not convert */
                break;
        default:
                arg = (unsigned long)compat_ptr(arg);
                break;
        }

        return md_ioctl(bdev, mode, cmd, arg);
}
#endif /* CONFIG_COMPAT */

static int md_set_read_only(struct block_device *bdev, bool ro)
{
        struct mddev *mddev = bdev->bd_disk->private_data;
        int err;

        err = mddev_lock(mddev);
        if (err)
                return err;

        if (!mddev->raid_disks && !mddev->external) {
                err = -ENODEV;
                goto out_unlock;
        }

        /*
         * Transitioning to read-auto need only happen for arrays that call
         * md_write_start and which are not ready for writes yet.
         */
        if (!ro && mddev->ro == 1 && mddev->pers) {
                err = restart_array(mddev);
                if (err)
                        goto out_unlock;
                mddev->ro = 2;
        }

out_unlock:
        mddev_unlock(mddev);
        return err;
}

static int md_open(struct block_device *bdev, fmode_t mode)
{
        /*
         * Succeed if we can lock the mddev, which confirms that
         * it isn't being stopped right now.
         */
        struct mddev *mddev = mddev_find(bdev->bd_dev);
        int err;

        if (!mddev)
                return -ENODEV;

        if (mddev->gendisk != bdev->bd_disk) {
                /* we are racing with mddev_put which is discarding this
                 * bd_disk.
                 */
                mddev_put(mddev);
                /* Wait until bdev->bd_disk is definitely gone */
                if (work_pending(&mddev->del_work))
                        flush_workqueue(md_misc_wq);
                return -EBUSY;
        }
        BUG_ON(mddev != bdev->bd_disk->private_data);

        if ((err = mutex_lock_interruptible(&mddev->open_mutex)))
                goto out;

        if (test_bit(MD_CLOSING, &mddev->flags)) {
                mutex_unlock(&mddev->open_mutex);
                err = -ENODEV;
                goto out;
        }

        err = 0;
        atomic_inc(&mddev->openers);
        mutex_unlock(&mddev->open_mutex);

        bdev_check_media_change(bdev);
 out:
        if (err)
                mddev_put(mddev);
        return err;
}

static void md_release(struct gendisk *disk, fmode_t mode)
{
        struct mddev *mddev = disk->private_data;

        BUG_ON(!mddev);
        atomic_dec(&mddev->openers);
        mddev_put(mddev);
}

static unsigned int md_check_events(struct gendisk *disk, unsigned int clearing)
{
        struct mddev *mddev = disk->private_data;
        unsigned int ret = 0;

        if (mddev->changed)
                ret = DISK_EVENT_MEDIA_CHANGE;
        mddev->changed = 0;
        return ret;
}

const struct block_device_operations md_fops =
{
        .owner          = THIS_MODULE,
        .submit_bio     = md_submit_bio,
        .open           = md_open,
        .release        = md_release,
        .ioctl          = md_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = md_compat_ioctl,
#endif
        .getgeo         = md_getgeo,
        .check_events   = md_check_events,
        .set_read_only  = md_set_read_only,
};

static int md_thread(void *arg)
{
        struct md_thread *thread = arg;

        /*
         * md_thread is a 'system-thread', it's priority should be very
         * high. We avoid resource deadlocks individually in each
         * raid personality. (RAID5 does preallocation) We also use RR and
         * the very same RT priority as kswapd, thus we will never get
         * into a priority inversion deadlock.
         *
         * we definitely have to have equal or higher priority than
         * bdflush, otherwise bdflush will deadlock if there are too
         * many dirty RAID5 blocks.
         */

        allow_signal(SIGKILL);
        while (!kthread_should_stop()) {

                /* We need to wait INTERRUPTIBLE so that
                 * we don't add to the load-average.
                 * That means we need to be sure no signals are
                 * pending
                 */
                if (signal_pending(current))
                        flush_signals(current);

                wait_event_interruptible_timeout
                        (thread->wqueue,
                         test_bit(THREAD_WAKEUP, &thread->flags)
                         || kthread_should_stop() || kthread_should_park(),
                         thread->timeout);

                clear_bit(THREAD_WAKEUP, &thread->flags);
                if (kthread_should_park())
                        kthread_parkme();
                if (!kthread_should_stop())
                        thread->run(thread);
        }

        return 0;
}

void md_wakeup_thread(struct md_thread *thread)
{
        if (thread) {
                pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm);
                set_bit(THREAD_WAKEUP, &thread->flags);
                wake_up(&thread->wqueue);
        }
}
EXPORT_SYMBOL(md_wakeup_thread);

struct md_thread *md_register_thread(void (*run) (struct md_thread *),
                struct mddev *mddev, const char *name)
{
        struct md_thread *thread;

        thread = kzalloc(sizeof(struct md_thread), GFP_KERNEL);
        if (!thread)
                return NULL;

        init_waitqueue_head(&thread->wqueue);

        thread->run = run;
        thread->mddev = mddev;
        thread->timeout = MAX_SCHEDULE_TIMEOUT;
        thread->tsk = kthread_run(md_thread, thread,
                                  "%s_%s",
                                  mdname(thread->mddev),
                                  name);
        if (IS_ERR(thread->tsk)) {
                kfree(thread);
                return NULL;
        }
        return thread;
}
EXPORT_SYMBOL(md_register_thread);

void md_unregister_thread(struct md_thread **threadp)
{
        struct md_thread *thread = *threadp;
        if (!thread)
                return;
        pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
        /* Locking ensures that mddev_unlock does not wake_up a
         * non-existent thread
         */
        spin_lock(&pers_lock);
        *threadp = NULL;
        spin_unlock(&pers_lock);

        kthread_stop(thread->tsk);
        kfree(thread);
}
EXPORT_SYMBOL(md_unregister_thread);

void md_error(struct mddev *mddev, struct md_rdev *rdev)
{
        if (!rdev || test_bit(Faulty, &rdev->flags))
                return;

        if (!mddev->pers || !mddev->pers->error_handler)
                return;
        mddev->pers->error_handler(mddev,rdev);
        if (mddev->degraded)
                set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
        sysfs_notify_dirent_safe(rdev->sysfs_state);
        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
        if (mddev->event_work.func)
                queue_work(md_misc_wq, &mddev->event_work);
        md_new_event(mddev);
}
EXPORT_SYMBOL(md_error);

/* seq_file implementation /proc/mdstat */

static void status_unused(struct seq_file *seq)
{
        int i = 0;
        struct md_rdev *rdev;

        seq_printf(seq, "unused devices: ");

        list_for_each_entry(rdev, &pending_raid_disks, same_set) {
                char b[BDEVNAME_SIZE];
                i++;
                seq_printf(seq, "%s ",
                              bdevname(rdev->bdev,b));
        }
        if (!i)
                seq_printf(seq, "<none>");

        seq_printf(seq, "\n");
}

static int status_resync(struct seq_file *seq, struct mddev *mddev)
{
        sector_t max_sectors, resync, res;
        unsigned long dt, db = 0;
        sector_t rt, curr_mark_cnt, resync_mark_cnt;
        int scale, recovery_active;
        unsigned int per_milli;

        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
            test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                max_sectors = mddev->resync_max_sectors;
        else
                max_sectors = mddev->dev_sectors;

        resync = mddev->curr_resync;
        if (resync <= 3) {
                if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
                        /* Still cleaning up */
                        resync = max_sectors;
        } else if (resync > max_sectors)
                resync = max_sectors;
        else
                resync -= atomic_read(&mddev->recovery_active);

        if (resync == 0) {
                if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery)) {
                        struct md_rdev *rdev;

                        rdev_for_each(rdev, mddev)
                                if (rdev->raid_disk >= 0 &&
                                    !test_bit(Faulty, &rdev->flags) &&
                                    rdev->recovery_offset != MaxSector &&
                                    rdev->recovery_offset) {
                                        seq_printf(seq, "\trecover=REMOTE");
                                        return 1;
                                }
                        if (mddev->reshape_position != MaxSector)
                                seq_printf(seq, "\treshape=REMOTE");
                        else
                                seq_printf(seq, "\tresync=REMOTE");
                        return 1;
                }
                if (mddev->recovery_cp < MaxSector) {
                        seq_printf(seq, "\tresync=PENDING");
                        return 1;
                }
                return 0;
        }
        if (resync < 3) {
                seq_printf(seq, "\tresync=DELAYED");
                return 1;
        }

        WARN_ON(max_sectors == 0);
        /* Pick 'scale' such that (resync>>scale)*1000 will fit
         * in a sector_t, and (max_sectors>>scale) will fit in a
         * u32, as those are the requirements for sector_div.
         * Thus 'scale' must be at least 10
         */
        scale = 10;
        if (sizeof(sector_t) > sizeof(unsigned long)) {
                while ( max_sectors/2 > (1ULL<<(scale+32)))
                        scale++;
        }
        res = (resync>>scale)*1000;
        sector_div(res, (u32)((max_sectors>>scale)+1));

        per_milli = res;
        {
                int i, x = per_milli/50, y = 20-x;
                seq_printf(seq, "[");
                for (i = 0; i < x; i++)
                        seq_printf(seq, "=");
                seq_printf(seq, ">");
                for (i = 0; i < y; i++)
                        seq_printf(seq, ".");
                seq_printf(seq, "] ");
        }
        seq_printf(seq, " %s =%3u.%u%% (%llu/%llu)",
                   (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)?
                    "reshape" :
                    (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)?
                     "check" :
                     (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ?
                      "resync" : "recovery"))),
                   per_milli/10, per_milli % 10,
                   (unsigned long long) resync/2,
                   (unsigned long long) max_sectors/2);

        /*
         * dt: time from mark until now
         * db: blocks written from mark until now
         * rt: remaining time
         *
         * rt is a sector_t, which is always 64bit now. We are keeping
         * the original algorithm, but it is not really necessary.
         *
         * Original algorithm:
         *   So we divide before multiply in case it is 32bit and close
         *   to the limit.
         *   We scale the divisor (db) by 32 to avoid losing precision
         *   near the end of resync when the number of remaining sectors
         *   is close to 'db'.
         *   We then divide rt by 32 after multiplying by db to compensate.
         *   The '+1' avoids division by zero if db is very small.
         */
        dt = ((jiffies - mddev->resync_mark) / HZ);
        if (!dt) dt++;

        curr_mark_cnt = mddev->curr_mark_cnt;
        recovery_active = atomic_read(&mddev->recovery_active);
        resync_mark_cnt = mddev->resync_mark_cnt;

        if (curr_mark_cnt >= (recovery_active + resync_mark_cnt))
                db = curr_mark_cnt - (recovery_active + resync_mark_cnt);

        rt = max_sectors - resync;    /* number of remaining sectors */
        rt = div64_u64(rt, db/32+1);
        rt *= dt;
        rt >>= 5;

        seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60,
                   ((unsigned long)rt % 60)/6);

        seq_printf(seq, " speed=%ldK/sec", db/2/dt);
        return 1;
}

static void *md_seq_start(struct seq_file *seq, loff_t *pos)
{
        struct list_head *tmp;
        loff_t l = *pos;
        struct mddev *mddev;

        if (l == 0x10000) {
                ++*pos;
                return (void *)2;
        }
        if (l > 0x10000)
                return NULL;
        if (!l--)
                /* header */
                return (void*)1;

        spin_lock(&all_mddevs_lock);
        list_for_each(tmp,&all_mddevs)
                if (!l--) {
                        mddev = list_entry(tmp, struct mddev, all_mddevs);
                        mddev_get(mddev);
                        spin_unlock(&all_mddevs_lock);
                        return mddev;
                }
        spin_unlock(&all_mddevs_lock);
        if (!l--)
                return (void*)2;/* tail */
        return NULL;
}

static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct list_head *tmp;
        struct mddev *next_mddev, *mddev = v;

        ++*pos;
        if (v == (void*)2)
                return NULL;

        spin_lock(&all_mddevs_lock);
        if (v == (void*)1)
                tmp = all_mddevs.next;
        else
                tmp = mddev->all_mddevs.next;
        if (tmp != &all_mddevs)
                next_mddev = mddev_get(list_entry(tmp,struct mddev,all_mddevs));
        else {
                next_mddev = (void*)2;
                *pos = 0x10000;
        }
        spin_unlock(&all_mddevs_lock);

        if (v != (void*)1)
                mddev_put(mddev);
        return next_mddev;

}

static void md_seq_stop(struct seq_file *seq, void *v)
{
        struct mddev *mddev = v;

        if (mddev && v != (void*)1 && v != (void*)2)
                mddev_put(mddev);
}

static int md_seq_show(struct seq_file *seq, void *v)
{
        struct mddev *mddev = v;
        sector_t sectors;
        struct md_rdev *rdev;

        if (v == (void*)1) {
                struct md_personality *pers;
                seq_printf(seq, "Personalities : ");
                spin_lock(&pers_lock);
                list_for_each_entry(pers, &pers_list, list)
                        seq_printf(seq, "[%s] ", pers->name);

                spin_unlock(&pers_lock);
                seq_printf(seq, "\n");
                seq->poll_event = atomic_read(&md_event_count);
                return 0;
        }
        if (v == (void*)2) {
                status_unused(seq);
                return 0;
        }

        spin_lock(&mddev->lock);
        if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
                seq_printf(seq, "%s : %sactive", mdname(mddev),
                                                mddev->pers ? "" : "in");
                if (mddev->pers) {
                        if (mddev->ro==1)
                                seq_printf(seq, " (read-only)");
                        if (mddev->ro==2)
                                seq_printf(seq, " (auto-read-only)");
                        seq_printf(seq, " %s", mddev->pers->name);
                }

                sectors = 0;
                rcu_read_lock();
                rdev_for_each_rcu(rdev, mddev) {
                        char b[BDEVNAME_SIZE];
                        seq_printf(seq, " %s[%d]",
                                bdevname(rdev->bdev,b), rdev->desc_nr);
                        if (test_bit(WriteMostly, &rdev->flags))
                                seq_printf(seq, "(W)");
                        if (test_bit(Journal, &rdev->flags))
                                seq_printf(seq, "(J)");
                        if (test_bit(Faulty, &rdev->flags)) {
                                seq_printf(seq, "(F)");
                                continue;
                        }
                        if (rdev->raid_disk < 0)
                                seq_printf(seq, "(S)"); /* spare */
                        if (test_bit(Replacement, &rdev->flags))
                                seq_printf(seq, "(R)");
                        sectors += rdev->sectors;
                }
                rcu_read_unlock();

                if (!list_empty(&mddev->disks)) {
                        if (mddev->pers)
                                seq_printf(seq, "\n      %llu blocks",
                                           (unsigned long long)
                                           mddev->array_sectors / 2);
                        else
                                seq_printf(seq, "\n      %llu blocks",
                                           (unsigned long long)sectors / 2);
                }
                if (mddev->persistent) {
                        if (mddev->major_version != 0 ||
                            mddev->minor_version != 90) {
                                seq_printf(seq," super %d.%d",
                                           mddev->major_version,
                                           mddev->minor_version);
                        }
                } else if (mddev->external)
                        seq_printf(seq, " super external:%s",
                                   mddev->metadata_type);
                else
                        seq_printf(seq, " super non-persistent");

                if (mddev->pers) {
                        mddev->pers->status(seq, mddev);
                        seq_printf(seq, "\n      ");
                        if (mddev->pers->sync_request) {
                                if (status_resync(seq, mddev))
                                        seq_printf(seq, "\n      ");
                        }
                } else
                        seq_printf(seq, "\n       ");

                md_bitmap_status(seq, mddev->bitmap);

                seq_printf(seq, "\n");
        }
        spin_unlock(&mddev->lock);

        return 0;
}

static const struct seq_operations md_seq_ops = {
        .start  = md_seq_start,
        .next   = md_seq_next,
        .stop   = md_seq_stop,
        .show   = md_seq_show,
};

static int md_seq_open(struct inode *inode, struct file *file)
{
        struct seq_file *seq;
        int error;

        error = seq_open(file, &md_seq_ops);
        if (error)
                return error;

        seq = file->private_data;
        seq->poll_event = atomic_read(&md_event_count);
        return error;
}

static int md_unloading;
static __poll_t mdstat_poll(struct file *filp, poll_table *wait)
{
        struct seq_file *seq = filp->private_data;
        __poll_t mask;

        if (md_unloading)
                return EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
        poll_wait(filp, &md_event_waiters, wait);

        /* always allow read */
        mask = EPOLLIN | EPOLLRDNORM;

        if (seq->poll_event != atomic_read(&md_event_count))
                mask |= EPOLLERR | EPOLLPRI;
        return mask;
}

static const struct proc_ops mdstat_proc_ops = {
        .proc_open      = md_seq_open,
        .proc_read      = seq_read,
        .proc_lseek     = seq_lseek,
        .proc_release   = seq_release,
        .proc_poll      = mdstat_poll,
};

int register_md_personality(struct md_personality *p)
{
        pr_debug("md: %s personality registered for level %d\n",
                 p->name, p->level);
        spin_lock(&pers_lock);
        list_add_tail(&p->list, &pers_list);
        spin_unlock(&pers_lock);
        return 0;
}
EXPORT_SYMBOL(register_md_personality);

int unregister_md_personality(struct md_personality *p)
{
        pr_debug("md: %s personality unregistered\n", p->name);
        spin_lock(&pers_lock);
        list_del_init(&p->list);
        spin_unlock(&pers_lock);
        return 0;
}
EXPORT_SYMBOL(unregister_md_personality);

int register_md_cluster_operations(struct md_cluster_operations *ops,
                                   struct module *module)
{
        int ret = 0;
        spin_lock(&pers_lock);
        if (md_cluster_ops != NULL)
                ret = -EALREADY;
        else {
                md_cluster_ops = ops;
                md_cluster_mod = module;
        }
        spin_unlock(&pers_lock);
        return ret;
}
EXPORT_SYMBOL(register_md_cluster_operations);

int unregister_md_cluster_operations(void)
{
        spin_lock(&pers_lock);
        md_cluster_ops = NULL;
        spin_unlock(&pers_lock);
        return 0;
}
EXPORT_SYMBOL(unregister_md_cluster_operations);

int md_setup_cluster(struct mddev *mddev, int nodes)
{
        int ret;
        if (!md_cluster_ops)
                request_module("md-cluster");
        spin_lock(&pers_lock);
        /* ensure module won't be unloaded */
        if (!md_cluster_ops || !try_module_get(md_cluster_mod)) {
                pr_warn("can't find md-cluster module or get it's reference.\n");
                spin_unlock(&pers_lock);
                return -ENOENT;
        }
        spin_unlock(&pers_lock);

        ret = md_cluster_ops->join(mddev, nodes);
        if (!ret)
                mddev->safemode_delay = 0;
        return ret;
}

void md_cluster_stop(struct mddev *mddev)
{
        if (!md_cluster_ops)
                return;
        md_cluster_ops->leave(mddev);
        module_put(md_cluster_mod);
}

static int is_mddev_idle(struct mddev *mddev, int init)
{
        struct md_rdev *rdev;
        int idle;
        int curr_events;

        idle = 1;
        rcu_read_lock();
        rdev_for_each_rcu(rdev, mddev) {
                struct gendisk *disk = rdev->bdev->bd_disk;
                curr_events = (int)part_stat_read_accum(disk->part0, sectors) -
                              atomic_read(&disk->sync_io);
                /* sync IO will cause sync_io to increase before the disk_stats
                 * as sync_io is counted when a request starts, and
                 * disk_stats is counted when it completes.
                 * So resync activity will cause curr_events to be smaller than
                 * when there was no such activity.
                 * non-sync IO will cause disk_stat to increase without
                 * increasing sync_io so curr_events will (eventually)
                 * be larger than it was before.  Once it becomes
                 * substantially larger, the test below will cause
                 * the array to appear non-idle, and resync will slow
                 * down.
                 * If there is a lot of outstanding resync activity when
                 * we set last_event to curr_events, then all that activity
                 * completing might cause the array to appear non-idle
                 * and resync will be slowed down even though there might
                 * not have been non-resync activity.  This will only
                 * happen once though.  'last_events' will soon reflect
                 * the state where there is little or no outstanding
                 * resync requests, and further resync activity will
                 * always make curr_events less than last_events.
                 *
                 */
                if (init || curr_events - rdev->last_events > 64) {
                        rdev->last_events = curr_events;
                        idle = 0;
                }
        }
        rcu_read_unlock();
        return idle;
}

void md_done_sync(struct mddev *mddev, int blocks, int ok)
{
        /* another "blocks" (512byte) blocks have been synced */
        atomic_sub(blocks, &mddev->recovery_active);
        wake_up(&mddev->recovery_wait);
        if (!ok) {
                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                set_bit(MD_RECOVERY_ERROR, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
                // stop recovery, signal do_sync ....
        }
}
EXPORT_SYMBOL(md_done_sync);

/* md_write_start(mddev, bi)
 * If we need to update some array metadata (e.g. 'active' flag
 * in superblock) before writing, schedule a superblock update
 * and wait for it to complete.
 * A return value of 'false' means that the write wasn't recorded
 * and cannot proceed as the array is being suspend.
 */
bool md_write_start(struct mddev *mddev, struct bio *bi)
{
        int did_change = 0;

        if (bio_data_dir(bi) != WRITE)
                return true;

        BUG_ON(mddev->ro == 1);
        if (mddev->ro == 2) {
                /* need to switch to read/write */
                mddev->ro = 0;
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
                md_wakeup_thread(mddev->sync_thread);
                did_change = 1;
        }
        rcu_read_lock();
        percpu_ref_get(&mddev->writes_pending);
        smp_mb(); /* Match smp_mb in set_in_sync() */
        if (mddev->safemode == 1)
                mddev->safemode = 0;
        /* sync_checkers is always 0 when writes_pending is in per-cpu mode */
        if (mddev->in_sync || mddev->sync_checkers) {
                spin_lock(&mddev->lock);
                if (mddev->in_sync) {
                        mddev->in_sync = 0;
                        set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
                        set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
                        md_wakeup_thread(mddev->thread);
                        did_change = 1;
                }
                spin_unlock(&mddev->lock);
        }
        rcu_read_unlock();
        if (did_change)
                sysfs_notify_dirent_safe(mddev->sysfs_state);
        if (!mddev->has_superblocks)
                return true;
        wait_event(mddev->sb_wait,
                   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
                   mddev->suspended);
        if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
                percpu_ref_put(&mddev->writes_pending);
                return false;
        }
        return true;
}
EXPORT_SYMBOL(md_write_start);

/* md_write_inc can only be called when md_write_start() has
 * already been called at least once of the current request.
 * It increments the counter and is useful when a single request
 * is split into several parts.  Each part causes an increment and
 * so needs a matching md_write_end().
 * Unlike md_write_start(), it is safe to call md_write_inc() inside
 * a spinlocked region.
 */
void md_write_inc(struct mddev *mddev, struct bio *bi)
{
        if (bio_data_dir(bi) != WRITE)
                return;
        WARN_ON_ONCE(mddev->in_sync || mddev->ro);
        percpu_ref_get(&mddev->writes_pending);
}
EXPORT_SYMBOL(md_write_inc);

void md_write_end(struct mddev *mddev)
{
        percpu_ref_put(&mddev->writes_pending);

        if (mddev->safemode == 2)
                md_wakeup_thread(mddev->thread);
        else if (mddev->safemode_delay)
                /* The roundup() ensures this only performs locking once
                 * every ->safemode_delay jiffies
                 */
                mod_timer(&mddev->safemode_timer,
                          roundup(jiffies, mddev->safemode_delay) +
                          mddev->safemode_delay);
}

EXPORT_SYMBOL(md_write_end);

/* This is used by raid0 and raid10 */
void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
                        struct bio *bio, sector_t start, sector_t size)
{
        struct bio *discard_bio = NULL;

        if (__blkdev_issue_discard(rdev->bdev, start, size, GFP_NOIO, 0,
                        &discard_bio) || !discard_bio)
                return;

        bio_chain(discard_bio, bio);
        bio_clone_blkg_association(discard_bio, bio);
        if (mddev->gendisk)
                trace_block_bio_remap(discard_bio,
                                disk_devt(mddev->gendisk),
                                bio->bi_iter.bi_sector);
        submit_bio_noacct(discard_bio);
}
EXPORT_SYMBOL_GPL(md_submit_discard_bio);

/* md_allow_write(mddev)
 * Calling this ensures that the array is marked 'active' so that writes
 * may proceed without blocking.  It is important to call this before
 * attempting a GFP_KERNEL allocation while holding the mddev lock.
 * Must be called with mddev_lock held.
 */
void md_allow_write(struct mddev *mddev)
{
        if (!mddev->pers)
                return;
        if (mddev->ro)
                return;
        if (!mddev->pers->sync_request)
                return;

        spin_lock(&mddev->lock);
        if (mddev->in_sync) {
                mddev->in_sync = 0;
                set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
                set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
                if (mddev->safemode_delay &&
                    mddev->safemode == 0)
                        mddev->safemode = 1;
                spin_unlock(&mddev->lock);
                md_update_sb(mddev, 0);
                sysfs_notify_dirent_safe(mddev->sysfs_state);
                /* wait for the dirty state to be recorded in the metadata */
                wait_event(mddev->sb_wait,
                           !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
        } else
                spin_unlock(&mddev->lock);
}
EXPORT_SYMBOL_GPL(md_allow_write);

#define SYNC_MARKS      10
#define SYNC_MARK_STEP  (3*HZ)
#define UPDATE_FREQUENCY (5*60*HZ)
void md_do_sync(struct md_thread *thread)
{
        struct mddev *mddev = thread->mddev;
        struct mddev *mddev2;
        unsigned int currspeed = 0, window;
        sector_t max_sectors,j, io_sectors, recovery_done;
        unsigned long mark[SYNC_MARKS];
        unsigned long update_time;
        sector_t mark_cnt[SYNC_MARKS];
        int last_mark,m;
        struct list_head *tmp;
        sector_t last_check;
        int skipped = 0;
        struct md_rdev *rdev;
        char *desc, *action = NULL;
        struct blk_plug plug;
        int ret;

        /* just incase thread restarts... */
        if (test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
            test_bit(MD_RECOVERY_WAIT, &mddev->recovery))
                return;
        if (mddev->ro) {/* never try to sync a read-only array */
                set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                return;
        }

        if (mddev_is_clustered(mddev)) {
                ret = md_cluster_ops->resync_start(mddev);
                if (ret)
                        goto skip;

                set_bit(MD_CLUSTER_RESYNC_LOCKED, &mddev->flags);
                if (!(test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
                        test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ||
                        test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
                     && ((unsigned long long)mddev->curr_resync_completed
                         < (unsigned long long)mddev->resync_max_sectors))
                        goto skip;
        }

        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
                if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
                        desc = "data-check";
                        action = "check";
                } else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
                        desc = "requested-resync";
                        action = "repair";
                } else
                        desc = "resync";
        } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                desc = "reshape";
        else
                desc = "recovery";

        mddev->last_sync_action = action ?: desc;

        /* we overload curr_resync somewhat here.
         * 0 == not engaged in resync at all
         * 2 == checking that there is no conflict with another sync
         * 1 == like 2, but have yielded to allow conflicting resync to
         *              commence
         * other == active in resync - this many blocks
         *
         * Before starting a resync we must have set curr_resync to
         * 2, and then checked that every "conflicting" array has curr_resync
         * less than ours.  When we find one that is the same or higher
         * we wait on resync_wait.  To avoid deadlock, we reduce curr_resync
         * to 1 if we choose to yield (based arbitrarily on address of mddev structure).
         * This will mean we have to start checking from the beginning again.
         *
         */

        do {
                int mddev2_minor = -1;
                mddev->curr_resync = 2;

        try_again:
                if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                        goto skip;
                for_each_mddev(mddev2, tmp) {
                        if (mddev2 == mddev)
                                continue;
                        if (!mddev->parallel_resync
                        &&  mddev2->curr_resync
                        &&  match_mddev_units(mddev, mddev2)) {
                                DEFINE_WAIT(wq);
                                if (mddev < mddev2 && mddev->curr_resync == 2) {
                                        /* arbitrarily yield */
                                        mddev->curr_resync = 1;
                                        wake_up(&resync_wait);
                                }
                                if (mddev > mddev2 && mddev->curr_resync == 1)
                                        /* no need to wait here, we can wait the next
                                         * time 'round when curr_resync == 2
                                         */
                                        continue;
                                /* We need to wait 'interruptible' so as not to
                                 * contribute to the load average, and not to
                                 * be caught by 'softlockup'
                                 */
                                prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
                                if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
                                    mddev2->curr_resync >= mddev->curr_resync) {
                                        if (mddev2_minor != mddev2->md_minor) {
                                                mddev2_minor = mddev2->md_minor;
                                                pr_info("md: delaying %s of %s until %s has finished (they share one or more physical units)\n",
                                                        desc, mdname(mddev),
                                                        mdname(mddev2));
                                        }
                                        mddev_put(mddev2);
                                        if (signal_pending(current))
                                                flush_signals(current);
                                        schedule();
                                        finish_wait(&resync_wait, &wq);
                                        goto try_again;
                                }
                                finish_wait(&resync_wait, &wq);
                        }
                }
        } while (mddev->curr_resync < 2);

        j = 0;
        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
                /* resync follows the size requested by the personality,
                 * which defaults to physical size, but can be virtual size
                 */
                max_sectors = mddev->resync_max_sectors;
                atomic64_set(&mddev->resync_mismatches, 0);
                /* we don't use the checkpoint if there's a bitmap */
                if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                        j = mddev->resync_min;
                else if (!mddev->bitmap)
                        j = mddev->recovery_cp;

        } else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
                max_sectors = mddev->resync_max_sectors;
                /*
                 * If the original node aborts reshaping then we continue the
                 * reshaping, so set j again to avoid restart reshape from the
                 * first beginning
                 */
                if (mddev_is_clustered(mddev) &&
                    mddev->reshape_position != MaxSector)
                        j = mddev->reshape_position;
        } else {
                /* recovery follows the physical size of devices */
                max_sectors = mddev->dev_sectors;
                j = MaxSector;
                rcu_read_lock();
                rdev_for_each_rcu(rdev, mddev)
                        if (rdev->raid_disk >= 0 &&
                            !test_bit(Journal, &rdev->flags) &&
                            !test_bit(Faulty, &rdev->flags) &&
                            !test_bit(In_sync, &rdev->flags) &&
                            rdev->recovery_offset < j)
                                j = rdev->recovery_offset;
                rcu_read_unlock();

                /* If there is a bitmap, we need to make sure all
                 * writes that started before we added a spare
                 * complete before we start doing a recovery.
                 * Otherwise the write might complete and (via
                 * bitmap_endwrite) set a bit in the bitmap after the
                 * recovery has checked that bit and skipped that
                 * region.
                 */
                if (mddev->bitmap) {
                        mddev->pers->quiesce(mddev, 1);
                        mddev->pers->quiesce(mddev, 0);
                }
        }

        pr_info("md: %s of RAID array %s\n", desc, mdname(mddev));
        pr_debug("md: minimum _guaranteed_  speed: %d KB/sec/disk.\n", speed_min(mddev));
        pr_debug("md: using maximum available idle IO bandwidth (but not more than %d KB/sec) for %s.\n",
                 speed_max(mddev), desc);

        is_mddev_idle(mddev, 1); /* this initializes IO event counters */

        io_sectors = 0;
        for (m = 0; m < SYNC_MARKS; m++) {
                mark[m] = jiffies;
                mark_cnt[m] = io_sectors;
        }
        last_mark = 0;
        mddev->resync_mark = mark[last_mark];
        mddev->resync_mark_cnt = mark_cnt[last_mark];

        /*
         * Tune reconstruction:
         */
        window = 32 * (PAGE_SIZE / 512);
        pr_debug("md: using %dk window, over a total of %lluk.\n",
                 window/2, (unsigned long long)max_sectors/2);

        atomic_set(&mddev->recovery_active, 0);
        last_check = 0;

        if (j>2) {
                pr_debug("md: resuming %s of %s from checkpoint.\n",
                         desc, mdname(mddev));
                mddev->curr_resync = j;
        } else
                mddev->curr_resync = 3; /* no longer delayed */
        mddev->curr_resync_completed = j;
        sysfs_notify_dirent_safe(mddev->sysfs_completed);
        md_new_event(mddev);
        update_time = jiffies;

        blk_start_plug(&plug);
        while (j < max_sectors) {
                sector_t sectors;

                skipped = 0;

                if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
                    ((mddev->curr_resync > mddev->curr_resync_completed &&
                      (mddev->curr_resync - mddev->curr_resync_completed)
                      > (max_sectors >> 4)) ||
                     time_after_eq(jiffies, update_time + UPDATE_FREQUENCY) ||
                     (j - mddev->curr_resync_completed)*2
                     >= mddev->resync_max - mddev->curr_resync_completed ||
                     mddev->curr_resync_completed > mddev->resync_max
                            )) {
                        /* time to update curr_resync_completed */
                        wait_event(mddev->recovery_wait,
                                   atomic_read(&mddev->recovery_active) == 0);
                        mddev->curr_resync_completed = j;
                        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
                            j > mddev->recovery_cp)
                                mddev->recovery_cp = j;
                        update_time = jiffies;
                        set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
                        sysfs_notify_dirent_safe(mddev->sysfs_completed);
                }

                while (j >= mddev->resync_max &&
                       !test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                        /* As this condition is controlled by user-space,
                         * we can block indefinitely, so use '_interruptible'
                         * to avoid triggering warnings.
                         */
                        flush_signals(current); /* just in case */
                        wait_event_interruptible(mddev->recovery_wait,
                                                 mddev->resync_max > j
                                                 || test_bit(MD_RECOVERY_INTR,
                                                             &mddev->recovery));
                }

                if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                        break;

                sectors = mddev->pers->sync_request(mddev, j, &skipped);
                if (sectors == 0) {
                        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                        break;
                }

                if (!skipped) { /* actual IO requested */
                        io_sectors += sectors;
                        atomic_add(sectors, &mddev->recovery_active);
                }

                if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                        break;

                j += sectors;
                if (j > max_sectors)
                        /* when skipping, extra large numbers can be returned. */
                        j = max_sectors;
                if (j > 2)
                        mddev->curr_resync = j;
                mddev->curr_mark_cnt = io_sectors;
                if (last_check == 0)
                        /* this is the earliest that rebuild will be
                         * visible in /proc/mdstat
                         */
                        md_new_event(mddev);

                if (last_check + window > io_sectors || j == max_sectors)
                        continue;

                last_check = io_sectors;
        repeat:
                if (time_after_eq(jiffies, mark[last_mark] + SYNC_MARK_STEP )) {
                        /* step marks */
                        int next = (last_mark+1) % SYNC_MARKS;

                        mddev->resync_mark = mark[next];
                        mddev->resync_mark_cnt = mark_cnt[next];
                        mark[next] = jiffies;
                        mark_cnt[next] = io_sectors - atomic_read(&mddev->recovery_active);
                        last_mark = next;
                }

                if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                        break;

                /*
                 * this loop exits only if either when we are slower than
                 * the 'hard' speed limit, or the system was IO-idle for
                 * a jiffy.
                 * the system might be non-idle CPU-wise, but we only care
                 * about not overloading the IO subsystem. (things like an
                 * e2fsck being done on the RAID array should execute fast)
                 */
                cond_resched();

                recovery_done = io_sectors - atomic_read(&mddev->recovery_active);
                currspeed = ((unsigned long)(recovery_done - mddev->resync_mark_cnt))/2
                        /((jiffies-mddev->resync_mark)/HZ +1) +1;

                if (currspeed > speed_min(mddev)) {
                        if (currspeed > speed_max(mddev)) {
                                msleep(500);
                                goto repeat;
                        }
                        if (!is_mddev_idle(mddev, 0)) {
                                /*
                                 * Give other IO more of a chance.
                                 * The faster the devices, the less we wait.
                                 */
                                wait_event(mddev->recovery_wait,
                                           !atomic_read(&mddev->recovery_active));
                        }
                }
        }
        pr_info("md: %s: %s %s.\n",mdname(mddev), desc,
                test_bit(MD_RECOVERY_INTR, &mddev->recovery)
                ? "interrupted" : "done");
        /*
         * this also signals 'finished resyncing' to md_stop
         */
        blk_finish_plug(&plug);
        wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));

        if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
            !test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
            mddev->curr_resync > 3) {
                mddev->curr_resync_completed = mddev->curr_resync;
                sysfs_notify_dirent_safe(mddev->sysfs_completed);
        }
        mddev->pers->sync_request(mddev, max_sectors, &skipped);

        if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
            mddev->curr_resync > 3) {
                if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
                        if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                                if (mddev->curr_resync >= mddev->recovery_cp) {
                                        pr_debug("md: checkpointing %s of %s.\n",
                                                 desc, mdname(mddev));
                                        if (test_bit(MD_RECOVERY_ERROR,
                                                &mddev->recovery))
                                                mddev->recovery_cp =
                                                        mddev->curr_resync_completed;
                                        else
                                                mddev->recovery_cp =
                                                        mddev->curr_resync;
                                }
                        } else
                                mddev->recovery_cp = MaxSector;
                } else {
                        if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
                                mddev->curr_resync = MaxSector;
                        if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
                            test_bit(MD_RECOVERY_RECOVER, &mddev->recovery)) {
                                rcu_read_lock();
                                rdev_for_each_rcu(rdev, mddev)
                                        if (rdev->raid_disk >= 0 &&
                                            mddev->delta_disks >= 0 &&
                                            !test_bit(Journal, &rdev->flags) &&
                                            !test_bit(Faulty, &rdev->flags) &&
                                            !test_bit(In_sync, &rdev->flags) &&
                                            rdev->recovery_offset < mddev->curr_resync)
                                                rdev->recovery_offset = mddev->curr_resync;
                                rcu_read_unlock();
                        }
                }
        }
 skip:
        /* set CHANGE_PENDING here since maybe another update is needed,
         * so other nodes are informed. It should be harmless for normal
         * raid */
        set_mask_bits(&mddev->sb_flags, 0,
                      BIT(MD_SB_CHANGE_PENDING) | BIT(MD_SB_CHANGE_DEVS));

        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
                        !test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
                        mddev->delta_disks > 0 &&
                        mddev->pers->finish_reshape &&
                        mddev->pers->size &&
                        mddev->queue) {
                mddev_lock_nointr(mddev);
                md_set_array_sectors(mddev, mddev->pers->size(mddev, 0, 0));
                mddev_unlock(mddev);
                if (!mddev_is_clustered(mddev))
                        set_capacity_and_notify(mddev->gendisk,
                                                mddev->array_sectors);
        }

        spin_lock(&mddev->lock);
        if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                /* We completed so min/max setting can be forgotten if used. */
                if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                        mddev->resync_min = 0;
                mddev->resync_max = MaxSector;
        } else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                mddev->resync_min = mddev->curr_resync_completed;
        set_bit(MD_RECOVERY_DONE, &mddev->recovery);
        mddev->curr_resync = 0;
        spin_unlock(&mddev->lock);

        wake_up(&resync_wait);
        md_wakeup_thread(mddev->thread);
        return;
}
EXPORT_SYMBOL_GPL(md_do_sync);

static int remove_and_add_spares(struct mddev *mddev,
                                 struct md_rdev *this)
{
        struct md_rdev *rdev;
        int spares = 0;
        int removed = 0;
        bool remove_some = false;

        if (this && test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                /* Mustn't remove devices when resync thread is running */
                return 0;

        rdev_for_each(rdev, mddev) {
                if ((this == NULL || rdev == this) &&
                    rdev->raid_disk >= 0 &&
                    !test_bit(Blocked, &rdev->flags) &&
                    test_bit(Faulty, &rdev->flags) &&
                    atomic_read(&rdev->nr_pending)==0) {
                        /* Faulty non-Blocked devices with nr_pending == 0
                         * never get nr_pending incremented,
                         * never get Faulty cleared, and never get Blocked set.
                         * So we can synchronize_rcu now rather than once per device
                         */
                        remove_some = true;
                        set_bit(RemoveSynchronized, &rdev->flags);
                }
        }

        if (remove_some)
                synchronize_rcu();
        rdev_for_each(rdev, mddev) {
                if ((this == NULL || rdev == this) &&
                    rdev->raid_disk >= 0 &&
                    !test_bit(Blocked, &rdev->flags) &&
                    ((test_bit(RemoveSynchronized, &rdev->flags) ||
                     (!test_bit(In_sync, &rdev->flags) &&
                      !test_bit(Journal, &rdev->flags))) &&
                    atomic_read(&rdev->nr_pending)==0)) {
                        if (mddev->pers->hot_remove_disk(
                                    mddev, rdev) == 0) {
                                sysfs_unlink_rdev(mddev, rdev);
                                rdev->saved_raid_disk = rdev->raid_disk;
                                rdev->raid_disk = -1;
                                removed++;
                        }
                }
                if (remove_some && test_bit(RemoveSynchronized, &rdev->flags))
                        clear_bit(RemoveSynchronized, &rdev->flags);
        }

        if (removed && mddev->kobj.sd)
                sysfs_notify_dirent_safe(mddev->sysfs_degraded);

        if (this && removed)
                goto no_add;

        rdev_for_each(rdev, mddev) {
                if (this && this != rdev)
                        continue;
                if (test_bit(Candidate, &rdev->flags))
                        continue;
                if (rdev->raid_disk >= 0 &&
                    !test_bit(In_sync, &rdev->flags) &&
                    !test_bit(Journal, &rdev->flags) &&
                    !test_bit(Faulty, &rdev->flags))
                        spares++;
                if (rdev->raid_disk >= 0)
                        continue;
                if (test_bit(Faulty, &rdev->flags))
                        continue;
                if (!test_bit(Journal, &rdev->flags)) {
                        if (mddev->ro &&
                            ! (rdev->saved_raid_disk >= 0 &&
                               !test_bit(Bitmap_sync, &rdev->flags)))
                                continue;

                        rdev->recovery_offset = 0;
                }
                if (mddev->pers->hot_add_disk(mddev, rdev) == 0) {
                        /* failure here is OK */
                        sysfs_link_rdev(mddev, rdev);
                        if (!test_bit(Journal, &rdev->flags))
                                spares++;
                        md_new_event(mddev);
                        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
                }
        }
no_add:
        if (removed)
                set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
        return spares;
}

static void md_start_sync(struct work_struct *ws)
{
        struct mddev *mddev = container_of(ws, struct mddev, del_work);

        mddev->sync_thread = md_register_thread(md_do_sync,
                                                mddev,
                                                "resync");
        if (!mddev->sync_thread) {
                pr_warn("%s: could not start resync thread...\n",
                        mdname(mddev));
                /* leave the spares where they are, it shouldn't hurt */
                clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
                clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
                clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
                clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                wake_up(&resync_wait);
                if (test_and_clear_bit(MD_RECOVERY_RECOVER,
                                       &mddev->recovery))
                        if (mddev->sysfs_action)
                                sysfs_notify_dirent_safe(mddev->sysfs_action);
        } else
                md_wakeup_thread(mddev->sync_thread);
        sysfs_notify_dirent_safe(mddev->sysfs_action);
        md_new_event(mddev);
}

/*
 * This routine is regularly called by all per-raid-array threads to
 * deal with generic issues like resync and super-block update.
 * Raid personalities that don't have a thread (linear/raid0) do not
 * need this as they never do any recovery or update the superblock.
 *
 * It does not do any resync itself, but rather "forks" off other threads
 * to do that as needed.
 * When it is determined that resync is needed, we set MD_RECOVERY_RUNNING in
 * "->recovery" and create a thread at ->sync_thread.
 * When the thread finishes it sets MD_RECOVERY_DONE
 * and wakeups up this thread which will reap the thread and finish up.
 * This thread also removes any faulty devices (with nr_pending == 0).
 *
 * The overall approach is:
 *  1/ if the superblock needs updating, update it.
 *  2/ If a recovery thread is running, don't do anything else.
 *  3/ If recovery has finished, clean up, possibly marking spares active.
 *  4/ If there are any faulty devices, remove them.
 *  5/ If array is degraded, try to add spares devices
 *  6/ If array has spares or is not in-sync, start a resync thread.
 */
void md_check_recovery(struct mddev *mddev)
{
        if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags) && mddev->sb_flags) {
                /* Write superblock - thread that called mddev_suspend()
                 * holds reconfig_mutex for us.
                 */
                set_bit(MD_UPDATING_SB, &mddev->flags);
                smp_mb__after_atomic();
                if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags))
                        md_update_sb(mddev, 0);
                clear_bit_unlock(MD_UPDATING_SB, &mddev->flags);
                wake_up(&mddev->sb_wait);
        }

        if (mddev->suspended)
                return;

        if (mddev->bitmap)
                md_bitmap_daemon_work(mddev);

        if (signal_pending(current)) {
                if (mddev->pers->sync_request && !mddev->external) {
                        pr_debug("md: %s in immediate safe mode\n",
                                 mdname(mddev));
                        mddev->safemode = 2;
                }
                flush_signals(current);
        }

        if (mddev->ro && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
                return;
        if ( ! (
                (mddev->sb_flags & ~ (1<<MD_SB_CHANGE_PENDING)) ||
                test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
                test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
                (mddev->external == 0 && mddev->safemode == 1) ||
                (mddev->safemode == 2
                 && !mddev->in_sync && mddev->recovery_cp == MaxSector)
                ))
                return;

        if (mddev_trylock(mddev)) {
                int spares = 0;
                bool try_set_sync = mddev->safemode != 0;

                if (!mddev->external && mddev->safemode == 1)
                        mddev->safemode = 0;

                if (mddev->ro) {
                        struct md_rdev *rdev;
                        if (!mddev->external && mddev->in_sync)
                                /* 'Blocked' flag not needed as failed devices
                                 * will be recorded if array switched to read/write.
                                 * Leaving it set will prevent the device
                                 * from being removed.
                                 */
                                rdev_for_each(rdev, mddev)
                                        clear_bit(Blocked, &rdev->flags);
                        /* On a read-only array we can:
                         * - remove failed devices
                         * - add already-in_sync devices if the array itself
                         *   is in-sync.
                         * As we only add devices that are already in-sync,
                         * we can activate the spares immediately.
                         */
                        remove_and_add_spares(mddev, NULL);
                        /* There is no thread, but we need to call
                         * ->spare_active and clear saved_raid_disk
                         */
                        set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                        md_reap_sync_thread(mddev);
                        clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                        clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
                        goto unlock;
                }

                if (mddev_is_clustered(mddev)) {
                        struct md_rdev *rdev;
                        /* kick the device if another node issued a
                         * remove disk.
                         */
                        rdev_for_each(rdev, mddev) {
                                if (test_and_clear_bit(ClusterRemove, &rdev->flags) &&
                                                rdev->raid_disk < 0)
                                        md_kick_rdev_from_array(rdev);
                        }
                }

                if (try_set_sync && !mddev->external && !mddev->in_sync) {
                        spin_lock(&mddev->lock);
                        set_in_sync(mddev);
                        spin_unlock(&mddev->lock);
                }

                if (mddev->sb_flags)
                        md_update_sb(mddev, 0);

                if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
                    !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
                        /* resync/recovery still happening */
                        clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        goto unlock;
                }
                if (mddev->sync_thread) {
                        md_reap_sync_thread(mddev);
                        goto unlock;
                }
                /* Set RUNNING before clearing NEEDED to avoid
                 * any transients in the value of "sync_action".
                 */
                mddev->curr_resync_completed = 0;
                spin_lock(&mddev->lock);
                set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                spin_unlock(&mddev->lock);
                /* Clear some bits that don't mean anything, but
                 * might be left set
                 */
                clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
                clear_bit(MD_RECOVERY_DONE, &mddev->recovery);

                if (!test_and_clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
                    test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
                        goto not_running;
                /* no recovery is running.
                 * remove any failed drives, then
                 * add spares if possible.
                 * Spares are also removed and re-added, to allow
                 * the personality to fail the re-add.
                 */

                if (mddev->reshape_position != MaxSector) {
                        if (mddev->pers->check_reshape == NULL ||
                            mddev->pers->check_reshape(mddev) != 0)
                                /* Cannot proceed */
                                goto not_running;
                        set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
                        clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                } else if ((spares = remove_and_add_spares(mddev, NULL))) {
                        clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                        clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
                        clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
                        set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                } else if (mddev->recovery_cp < MaxSector) {
                        set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
                        clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
                } else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                        /* nothing to be done ... */
                        goto not_running;

                if (mddev->pers->sync_request) {
                        if (spares) {
                                /* We are adding a device or devices to an array
                                 * which has the bitmap stored on all devices.
                                 * So make sure all bitmap pages get written
                                 */
                                md_bitmap_write_all(mddev->bitmap);
                        }
                        INIT_WORK(&mddev->del_work, md_start_sync);
                        queue_work(md_misc_wq, &mddev->del_work);
                        goto unlock;
                }
        not_running:
                if (!mddev->sync_thread) {
                        clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                        wake_up(&resync_wait);
                        if (test_and_clear_bit(MD_RECOVERY_RECOVER,
                                               &mddev->recovery))
                                if (mddev->sysfs_action)
                                        sysfs_notify_dirent_safe(mddev->sysfs_action);
                }
        unlock:
                wake_up(&mddev->sb_wait);
                mddev_unlock(mddev);
        }
}
EXPORT_SYMBOL(md_check_recovery);

void md_reap_sync_thread(struct mddev *mddev)
{
        struct md_rdev *rdev;
        sector_t old_dev_sectors = mddev->dev_sectors;
        bool is_reshaped = false;

        /* resync has finished, collect result */
        md_unregister_thread(&mddev->sync_thread);
        if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
            !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
            mddev->degraded != mddev->raid_disks) {
                /* success...*/
                /* activate any spares */
                if (mddev->pers->spare_active(mddev)) {
                        sysfs_notify_dirent_safe(mddev->sysfs_degraded);
                        set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
                }
        }
        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
            mddev->pers->finish_reshape) {
                mddev->pers->finish_reshape(mddev);
                if (mddev_is_clustered(mddev))
                        is_reshaped = true;
        }

        /* If array is no-longer degraded, then any saved_raid_disk
         * information must be scrapped.
         */
        if (!mddev->degraded)
                rdev_for_each(rdev, mddev)
                        rdev->saved_raid_disk = -1;

        md_update_sb(mddev, 1);
        /* MD_SB_CHANGE_PENDING should be cleared by md_update_sb, so we can
         * call resync_finish here if MD_CLUSTER_RESYNC_LOCKED is set by
         * clustered raid */
        if (test_and_clear_bit(MD_CLUSTER_RESYNC_LOCKED, &mddev->flags))
                md_cluster_ops->resync_finish(mddev);
        clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
        clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
        clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
        clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
        clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
        clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
        /*
         * We call md_cluster_ops->update_size here because sync_size could
         * be changed by md_update_sb, and MD_RECOVERY_RESHAPE is cleared,
         * so it is time to update size across cluster.
         */
        if (mddev_is_clustered(mddev) && is_reshaped
                                      && !test_bit(MD_CLOSING, &mddev->flags))
                md_cluster_ops->update_size(mddev, old_dev_sectors);
        wake_up(&resync_wait);
        /* flag recovery needed just to double check */
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        sysfs_notify_dirent_safe(mddev->sysfs_action);
        md_new_event(mddev);
        if (mddev->event_work.func)
                queue_work(md_misc_wq, &mddev->event_work);
}
EXPORT_SYMBOL(md_reap_sync_thread);

void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev)
{
        sysfs_notify_dirent_safe(rdev->sysfs_state);
        wait_event_timeout(rdev->blocked_wait,
                           !test_bit(Blocked, &rdev->flags) &&
                           !test_bit(BlockedBadBlocks, &rdev->flags),
                           msecs_to_jiffies(5000));
        rdev_dec_pending(rdev, mddev);
}
EXPORT_SYMBOL(md_wait_for_blocked_rdev);

void md_finish_reshape(struct mddev *mddev)
{
        /* called be personality module when reshape completes. */
        struct md_rdev *rdev;

        rdev_for_each(rdev, mddev) {
                if (rdev->data_offset > rdev->new_data_offset)
                        rdev->sectors += rdev->data_offset - rdev->new_data_offset;
                else
                        rdev->sectors -= rdev->new_data_offset - rdev->data_offset;
                rdev->data_offset = rdev->new_data_offset;
        }
}
EXPORT_SYMBOL(md_finish_reshape);

/* Bad block management */

/* Returns 1 on success, 0 on failure */
int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                       int is_new)
{
        struct mddev *mddev = rdev->mddev;
        int rv;
        if (is_new)
                s += rdev->new_data_offset;
        else
                s += rdev->data_offset;
        rv = badblocks_set(&rdev->badblocks, s, sectors, 0);
        if (rv == 0) {
                /* Make sure they get written out promptly */
                if (test_bit(ExternalBbl, &rdev->flags))
                        sysfs_notify_dirent_safe(rdev->sysfs_unack_badblocks);
                sysfs_notify_dirent_safe(rdev->sysfs_state);
                set_mask_bits(&mddev->sb_flags, 0,
                              BIT(MD_SB_CHANGE_CLEAN) | BIT(MD_SB_CHANGE_PENDING));
                md_wakeup_thread(rdev->mddev->thread);
                return 1;
        } else
                return 0;
}
EXPORT_SYMBOL_GPL(rdev_set_badblocks);

int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                         int is_new)
{
        int rv;
        if (is_new)
                s += rdev->new_data_offset;
        else
                s += rdev->data_offset;
        rv = badblocks_clear(&rdev->badblocks, s, sectors);
        if ((rv == 0) && test_bit(ExternalBbl, &rdev->flags))
                sysfs_notify_dirent_safe(rdev->sysfs_badblocks);
        return rv;
}
EXPORT_SYMBOL_GPL(rdev_clear_badblocks);

static int md_notify_reboot(struct notifier_block *this,
                            unsigned long code, void *x)
{
        struct list_head *tmp;
        struct mddev *mddev;
        int need_delay = 0;

        for_each_mddev(mddev, tmp) {
                if (mddev_trylock(mddev)) {
                        if (mddev->pers)
                                __md_stop_writes(mddev);
                        if (mddev->persistent)
                                mddev->safemode = 2;
                        mddev_unlock(mddev);
                }
                need_delay = 1;
        }
        /*
         * certain more exotic SCSI devices are known to be
         * volatile wrt too early system reboots. While the
         * right place to handle this issue is the given
         * driver, we do want to have a safe RAID driver ...
         */
        if (need_delay)
                mdelay(1000*1);

        return NOTIFY_DONE;
}

static struct notifier_block md_notifier = {
        .notifier_call  = md_notify_reboot,
        .next           = NULL,
        .priority       = INT_MAX, /* before any real devices */
};

static void md_geninit(void)
{
        pr_debug("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));

        proc_create("mdstat", S_IRUGO, NULL, &mdstat_proc_ops);
}

static int __init md_init(void)
{
        int ret = -ENOMEM;

        md_wq = alloc_workqueue("md", WQ_MEM_RECLAIM, 0);
        if (!md_wq)
                goto err_wq;

        md_misc_wq = alloc_workqueue("md_misc", 0, 0);
        if (!md_misc_wq)
                goto err_misc_wq;

        md_rdev_misc_wq = alloc_workqueue("md_rdev_misc", 0, 0);
        if (!md_rdev_misc_wq)
                goto err_rdev_misc_wq;

        ret = __register_blkdev(MD_MAJOR, "md", md_probe);
        if (ret < 0)
                goto err_md;

        ret = __register_blkdev(0, "mdp", md_probe);
        if (ret < 0)
                goto err_mdp;
        mdp_major = ret;

        register_reboot_notifier(&md_notifier);
        raid_table_header = register_sysctl_table(raid_root_table);

        md_geninit();
        return 0;

err_mdp:
        unregister_blkdev(MD_MAJOR, "md");
err_md:
        destroy_workqueue(md_rdev_misc_wq);
err_rdev_misc_wq:
        destroy_workqueue(md_misc_wq);
err_misc_wq:
        destroy_workqueue(md_wq);
err_wq:
        return ret;
}

static void check_sb_changes(struct mddev *mddev, struct md_rdev *rdev)
{
        struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
        struct md_rdev *rdev2;
        int role, ret;
        char b[BDEVNAME_SIZE];

        /*
         * If size is changed in another node then we need to
         * do resize as well.
         */
        if (mddev->dev_sectors != le64_to_cpu(sb->size)) {
                ret = mddev->pers->resize(mddev, le64_to_cpu(sb->size));
                if (ret)
                        pr_info("md-cluster: resize failed\n");
                else
                        md_bitmap_update_sb(mddev->bitmap);
        }

        /* Check for change of roles in the active devices */
        rdev_for_each(rdev2, mddev) {
                if (test_bit(Faulty, &rdev2->flags))
                        continue;

                /* Check if the roles changed */
                role = le16_to_cpu(sb->dev_roles[rdev2->desc_nr]);

                if (test_bit(Candidate, &rdev2->flags)) {
                        if (role == 0xfffe) {
                                pr_info("md: Removing Candidate device %s because add failed\n", bdevname(rdev2->bdev,b));
                                md_kick_rdev_from_array(rdev2);
                                continue;
                        }
                        else
                                clear_bit(Candidate, &rdev2->flags);
                }

                if (role != rdev2->raid_disk) {
                        /*
                         * got activated except reshape is happening.
                         */
                        if (rdev2->raid_disk == -1 && role != 0xffff &&
                            !(le32_to_cpu(sb->feature_map) &
                              MD_FEATURE_RESHAPE_ACTIVE)) {
                                rdev2->saved_raid_disk = role;
                                ret = remove_and_add_spares(mddev, rdev2);
                                pr_info("Activated spare: %s\n",
                                        bdevname(rdev2->bdev,b));
                                /* wakeup mddev->thread here, so array could
                                 * perform resync with the new activated disk */
                                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                                md_wakeup_thread(mddev->thread);
                        }
                        /* device faulty
                         * We just want to do the minimum to mark the disk
                         * as faulty. The recovery is performed by the
                         * one who initiated the error.
                         */
                        if ((role == 0xfffe) || (role == 0xfffd)) {
                                md_error(mddev, rdev2);
                                clear_bit(Blocked, &rdev2->flags);
                        }
                }
        }

        if (mddev->raid_disks != le32_to_cpu(sb->raid_disks)) {
                ret = update_raid_disks(mddev, le32_to_cpu(sb->raid_disks));
                if (ret)
                        pr_warn("md: updating array disks failed. %d\n", ret);
        }

        /*
         * Since mddev->delta_disks has already updated in update_raid_disks,
         * so it is time to check reshape.
         */
        if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
            (le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
                /*
                 * reshape is happening in the remote node, we need to
                 * update reshape_position and call start_reshape.
                 */
                mddev->reshape_position = le64_to_cpu(sb->reshape_position);
                if (mddev->pers->update_reshape_pos)
                        mddev->pers->update_reshape_pos(mddev);
                if (mddev->pers->start_reshape)
                        mddev->pers->start_reshape(mddev);
        } else if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
                   mddev->reshape_position != MaxSector &&
                   !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
                /* reshape is just done in another node. */
                mddev->reshape_position = MaxSector;
                if (mddev->pers->update_reshape_pos)
                        mddev->pers->update_reshape_pos(mddev);
        }

        /* Finally set the event to be up to date */
        mddev->events = le64_to_cpu(sb->events);
}

static int read_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
        int err;
        struct page *swapout = rdev->sb_page;
        struct mdp_superblock_1 *sb;

        /* Store the sb page of the rdev in the swapout temporary
         * variable in case we err in the future
         */
        rdev->sb_page = NULL;
        err = alloc_disk_sb(rdev);
        if (err == 0) {
                ClearPageUptodate(rdev->sb_page);
                rdev->sb_loaded = 0;
                err = super_types[mddev->major_version].
                        load_super(rdev, NULL, mddev->minor_version);
        }
        if (err < 0) {
                pr_warn("%s: %d Could not reload rdev(%d) err: %d. Restoring old values\n",
                                __func__, __LINE__, rdev->desc_nr, err);
                if (rdev->sb_page)
                        put_page(rdev->sb_page);
                rdev->sb_page = swapout;
                rdev->sb_loaded = 1;
                return err;
        }

        sb = page_address(rdev->sb_page);
        /* Read the offset unconditionally, even if MD_FEATURE_RECOVERY_OFFSET
         * is not set
         */

        if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RECOVERY_OFFSET))
                rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);

        /* The other node finished recovery, call spare_active to set
         * device In_sync and mddev->degraded
         */
        if (rdev->recovery_offset == MaxSector &&
            !test_bit(In_sync, &rdev->flags) &&
            mddev->pers->spare_active(mddev))
                sysfs_notify_dirent_safe(mddev->sysfs_degraded);

        put_page(swapout);
        return 0;
}

void md_reload_sb(struct mddev *mddev, int nr)
{
        struct md_rdev *rdev;
        int err;

        /* Find the rdev */
        rdev_for_each_rcu(rdev, mddev) {
                if (rdev->desc_nr == nr)
                        break;
        }

        if (!rdev || rdev->desc_nr != nr) {
                pr_warn("%s: %d Could not find rdev with nr %d\n", __func__, __LINE__, nr);
                return;
        }

        err = read_rdev(mddev, rdev);
        if (err < 0)
                return;

        check_sb_changes(mddev, rdev);

        /* Read all rdev's to update recovery_offset */
        rdev_for_each_rcu(rdev, mddev) {
                if (!test_bit(Faulty, &rdev->flags))
                        read_rdev(mddev, rdev);
        }
}
EXPORT_SYMBOL(md_reload_sb);

#ifndef MODULE

/*
 * Searches all registered partitions for autorun RAID arrays
 * at boot time.
 */

static DEFINE_MUTEX(detected_devices_mutex);
static LIST_HEAD(all_detected_devices);
struct detected_devices_node {
        struct list_head list;
        dev_t dev;
};

void md_autodetect_dev(dev_t dev)
{
        struct detected_devices_node *node_detected_dev;

        node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
        if (node_detected_dev) {
                node_detected_dev->dev = dev;
                mutex_lock(&detected_devices_mutex);
                list_add_tail(&node_detected_dev->list, &all_detected_devices);
                mutex_unlock(&detected_devices_mutex);
        }
}

void md_autostart_arrays(int part)
{
        struct md_rdev *rdev;
        struct detected_devices_node *node_detected_dev;
        dev_t dev;
        int i_scanned, i_passed;

        i_scanned = 0;
        i_passed = 0;

        pr_info("md: Autodetecting RAID arrays.\n");

        mutex_lock(&detected_devices_mutex);
        while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
                i_scanned++;
                node_detected_dev = list_entry(all_detected_devices.next,
                                        struct detected_devices_node, list);
                list_del(&node_detected_dev->list);
                dev = node_detected_dev->dev;
                kfree(node_detected_dev);
                mutex_unlock(&detected_devices_mutex);
                rdev = md_import_device(dev,0, 90);
                mutex_lock(&detected_devices_mutex);
                if (IS_ERR(rdev))
                        continue;

                if (test_bit(Faulty, &rdev->flags))
                        continue;

                set_bit(AutoDetected, &rdev->flags);
                list_add(&rdev->same_set, &pending_raid_disks);
                i_passed++;
        }
        mutex_unlock(&detected_devices_mutex);

        pr_debug("md: Scanned %d and added %d devices.\n", i_scanned, i_passed);

        autorun_devices(part);
}

#endif /* !MODULE */

static __exit void md_exit(void)
{
        struct mddev *mddev;
        struct list_head *tmp;
        int delay = 1;

        unregister_blkdev(MD_MAJOR,"md");
        unregister_blkdev(mdp_major, "mdp");
        unregister_reboot_notifier(&md_notifier);
        unregister_sysctl_table(raid_table_header);

        /* We cannot unload the modules while some process is
         * waiting for us in select() or poll() - wake them up
         */
        md_unloading = 1;
        while (waitqueue_active(&md_event_waiters)) {
                /* not safe to leave yet */
                wake_up(&md_event_waiters);
                msleep(delay);
                delay += delay;
        }
        remove_proc_entry("mdstat", NULL);

        for_each_mddev(mddev, tmp) {
                export_array(mddev);
                mddev->ctime = 0;
                mddev->hold_active = 0;
                /*
                 * for_each_mddev() will call mddev_put() at the end of each
                 * iteration.  As the mddev is now fully clear, this will
                 * schedule the mddev for destruction by a workqueue, and the
                 * destroy_workqueue() below will wait for that to complete.
                 */
        }
        destroy_workqueue(md_rdev_misc_wq);
        destroy_workqueue(md_misc_wq);
        destroy_workqueue(md_wq);
}

subsys_initcall(md_init);
module_exit(md_exit)

static int get_ro(char *buffer, const struct kernel_param *kp)
{
        return sprintf(buffer, "%d\n", start_readonly);
}
static int set_ro(const char *val, const struct kernel_param *kp)
{
        return kstrtouint(val, 10, (unsigned int *)&start_readonly);
}

module_param_call(start_ro, set_ro, get_ro, NULL, S_IRUSR|S_IWUSR);
module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR);
module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);
module_param(create_on_open, bool, S_IRUSR|S_IWUSR);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MD RAID framework");
MODULE_ALIAS("md");
MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);