block: use rcu_work instead of call_rcu to avoid sleep in softirq

[mirror_ubuntu-bionic-kernel.git] / block / partition-generic.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Code extracted from drivers/block/genhd.c
 *  Copyright (C) 1991-1998  Linus Torvalds
 *  Re-organised Feb 1998 Russell King
 *
 *  We now have independent partition support from the
 *  block drivers, which allows all the partition code to
 *  be grouped in one location, and it to be mostly self
 *  contained.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/ctype.h>
#include <linux/genhd.h>
#include <linux/blktrace_api.h>

#include "partitions/check.h"

#ifdef CONFIG_BLK_DEV_MD
extern void md_autodetect_dev(dev_t dev);
#endif
 
/*
 * disk_name() is used by partition check code and the genhd driver.
 * It formats the devicename of the indicated disk into
 * the supplied buffer (of size at least 32), and returns
 * a pointer to that same buffer (for convenience).
 */

char *disk_name(struct gendisk *hd, int partno, char *buf)
{
        if (!partno)
                snprintf(buf, BDEVNAME_SIZE, "%s", hd->disk_name);
        else if (isdigit(hd->disk_name[strlen(hd->disk_name)-1]))
                snprintf(buf, BDEVNAME_SIZE, "%sp%d", hd->disk_name, partno);
        else
                snprintf(buf, BDEVNAME_SIZE, "%s%d", hd->disk_name, partno);

        return buf;
}

const char *bdevname(struct block_device *bdev, char *buf)
{
        return disk_name(bdev->bd_disk, bdev->bd_part->partno, buf);
}

EXPORT_SYMBOL(bdevname);

const char *bio_devname(struct bio *bio, char *buf)
{
        return disk_name(bio->bi_disk, bio->bi_partno, buf);
}
EXPORT_SYMBOL(bio_devname);

/*
 * There's very little reason to use this, you should really
 * have a struct block_device just about everywhere and use
 * bdevname() instead.
 */
const char *__bdevname(dev_t dev, char *buffer)
{
        scnprintf(buffer, BDEVNAME_SIZE, "unknown-block(%u,%u)",
                                MAJOR(dev), MINOR(dev));
        return buffer;
}

EXPORT_SYMBOL(__bdevname);

static ssize_t part_partition_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);

        return sprintf(buf, "%d\n", p->partno);
}

static ssize_t part_start_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);

        return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect);
}

ssize_t part_size_show(struct device *dev,
                       struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);
        return sprintf(buf, "%llu\n",(unsigned long long)part_nr_sects_read(p));
}

static ssize_t part_ro_show(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);
        return sprintf(buf, "%d\n", p->policy ? 1 : 0);
}

static ssize_t part_alignment_offset_show(struct device *dev,
                                          struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);
        return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset);
}

static ssize_t part_discard_alignment_show(struct device *dev,
                                           struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);
        return sprintf(buf, "%u\n", p->discard_alignment);
}

ssize_t part_stat_show(struct device *dev,
                       struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);
        struct request_queue *q = part_to_disk(p)->queue;
        unsigned int inflight[2];
        int cpu;

        cpu = part_stat_lock();
        part_round_stats(q, cpu, p);
        part_stat_unlock();
        part_in_flight(q, p, inflight);
        return sprintf(buf,
                "%8lu %8lu %8llu %8u "
                "%8lu %8lu %8llu %8u "
                "%8u %8u %8u"
                "\n",
                part_stat_read(p, ios[READ]),
                part_stat_read(p, merges[READ]),
                (unsigned long long)part_stat_read(p, sectors[READ]),
                jiffies_to_msecs(part_stat_read(p, ticks[READ])),
                part_stat_read(p, ios[WRITE]),
                part_stat_read(p, merges[WRITE]),
                (unsigned long long)part_stat_read(p, sectors[WRITE]),
                jiffies_to_msecs(part_stat_read(p, ticks[WRITE])),
                inflight[0],
                jiffies_to_msecs(part_stat_read(p, io_ticks)),
                jiffies_to_msecs(part_stat_read(p, time_in_queue)));
}

ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct hd_struct *p = dev_to_part(dev);
        struct request_queue *q = part_to_disk(p)->queue;
        unsigned int inflight[2];

        part_in_flight_rw(q, p, inflight);
        return sprintf(buf, "%8u %8u\n", inflight[0], inflight[1]);
}

#ifdef CONFIG_FAIL_MAKE_REQUEST
ssize_t part_fail_show(struct device *dev,
                       struct device_attribute *attr, char *buf)
{
        struct hd_struct *p = dev_to_part(dev);

        return sprintf(buf, "%d\n", p->make_it_fail);
}

ssize_t part_fail_store(struct device *dev,
                        struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct hd_struct *p = dev_to_part(dev);
        int i;

        if (count > 0 && sscanf(buf, "%d", &i) > 0)
                p->make_it_fail = (i == 0) ? 0 : 1;

        return count;
}
#endif

static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL);
static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL);
static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
static DEVICE_ATTR(ro, S_IRUGO, part_ro_show, NULL);
static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL);
static DEVICE_ATTR(discard_alignment, S_IRUGO, part_discard_alignment_show,
                   NULL);
static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
#ifdef CONFIG_FAIL_MAKE_REQUEST
static struct device_attribute dev_attr_fail =
        __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
#endif

static struct attribute *part_attrs[] = {
        &dev_attr_partition.attr,
        &dev_attr_start.attr,
        &dev_attr_size.attr,
        &dev_attr_ro.attr,
        &dev_attr_alignment_offset.attr,
        &dev_attr_discard_alignment.attr,
        &dev_attr_stat.attr,
        &dev_attr_inflight.attr,
#ifdef CONFIG_FAIL_MAKE_REQUEST
        &dev_attr_fail.attr,
#endif
        NULL
};

static struct attribute_group part_attr_group = {
        .attrs = part_attrs,
};

static const struct attribute_group *part_attr_groups[] = {
        &part_attr_group,
#ifdef CONFIG_BLK_DEV_IO_TRACE
        &blk_trace_attr_group,
#endif
        NULL
};

static void part_release(struct device *dev)
{
        struct hd_struct *p = dev_to_part(dev);
        blk_free_devt(dev->devt);
        hd_free_part(p);
        kfree(p);
}

static int part_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct hd_struct *part = dev_to_part(dev);

        add_uevent_var(env, "PARTN=%u", part->partno);
        if (part->info && part->info->volname[0])
                add_uevent_var(env, "PARTNAME=%s", part->info->volname);
        return 0;
}

struct device_type part_type = {
        .name           = "partition",
        .groups         = part_attr_groups,
        .release        = part_release,
        .uevent         = part_uevent,
};

static void delete_partition_work_fn(struct work_struct *work)
{
        struct hd_struct *part = container_of(to_rcu_work(work), struct hd_struct,
                                        rcu_work);

        part->start_sect = 0;
        part->nr_sects = 0;
        part_stat_set_all(part, 0);
        put_device(part_to_dev(part));
}

void __delete_partition(struct percpu_ref *ref)
{
        struct hd_struct *part = container_of(ref, struct hd_struct, ref);
        INIT_RCU_WORK(&part->rcu_work, delete_partition_work_fn);
        queue_rcu_work(system_wq, &part->rcu_work);
}

/*
 * Must be called either with bd_mutex held, before a disk can be opened or
 * after all disk users are gone.
 */
void delete_partition(struct gendisk *disk, int partno)
{
        struct disk_part_tbl *ptbl =
                rcu_dereference_protected(disk->part_tbl, 1);
        struct hd_struct *part;

        if (partno >= ptbl->len)
                return;

        part = rcu_dereference_protected(ptbl->part[partno], 1);
        if (!part)
                return;

        rcu_assign_pointer(ptbl->part[partno], NULL);
        rcu_assign_pointer(ptbl->last_lookup, NULL);
        kobject_put(part->holder_dir);
        device_del(part_to_dev(part));

        hd_struct_kill(part);
}

static ssize_t whole_disk_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        return 0;
}
static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH,
                   whole_disk_show, NULL);

/*
 * Must be called either with bd_mutex held, before a disk can be opened or
 * after all disk users are gone.
 */
struct hd_struct *add_partition(struct gendisk *disk, int partno,
                                sector_t start, sector_t len, int flags,
                                struct partition_meta_info *info)
{
        struct hd_struct *p;
        dev_t devt = MKDEV(0, 0);
        struct device *ddev = disk_to_dev(disk);
        struct device *pdev;
        struct disk_part_tbl *ptbl;
        const char *dname;
        int err;

        err = disk_expand_part_tbl(disk, partno);
        if (err)
                return ERR_PTR(err);
        ptbl = rcu_dereference_protected(disk->part_tbl, 1);

        if (ptbl->part[partno])
                return ERR_PTR(-EBUSY);

        p = kzalloc(sizeof(*p), GFP_KERNEL);
        if (!p)
                return ERR_PTR(-EBUSY);

        if (!init_part_stats(p)) {
                err = -ENOMEM;
                goto out_free;
        }

        seqcount_init(&p->nr_sects_seq);
        pdev = part_to_dev(p);

        p->start_sect = start;
        p->alignment_offset =
                queue_limit_alignment_offset(&disk->queue->limits, start);
        p->discard_alignment =
                queue_limit_discard_alignment(&disk->queue->limits, start);
        p->nr_sects = len;
        p->partno = partno;
        p->policy = get_disk_ro(disk);

        if (info) {
                struct partition_meta_info *pinfo = alloc_part_info(disk);
                if (!pinfo) {
                        err = -ENOMEM;
                        goto out_free_stats;
                }
                memcpy(pinfo, info, sizeof(*info));
                p->info = pinfo;
        }

        dname = dev_name(ddev);
        if (isdigit(dname[strlen(dname) - 1]))
                dev_set_name(pdev, "%sp%d", dname, partno);
        else
                dev_set_name(pdev, "%s%d", dname, partno);

        device_initialize(pdev);
        pdev->class = &block_class;
        pdev->type = &part_type;
        pdev->parent = ddev;

        err = blk_alloc_devt(p, &devt);
        if (err)
                goto out_free_info;
        pdev->devt = devt;

        /* delay uevent until 'holders' subdir is created */
        dev_set_uevent_suppress(pdev, 1);
        err = device_add(pdev);
        if (err)
                goto out_put;

        err = -ENOMEM;
        p->holder_dir = kobject_create_and_add("holders", &pdev->kobj);
        if (!p->holder_dir)
                goto out_del;

        dev_set_uevent_suppress(pdev, 0);
        if (flags & ADDPART_FLAG_WHOLEDISK) {
                err = device_create_file(pdev, &dev_attr_whole_disk);
                if (err)
                        goto out_del;
        }

        err = hd_ref_init(p);
        if (err) {
                if (flags & ADDPART_FLAG_WHOLEDISK)
                        goto out_remove_file;
                goto out_del;
        }

        /* everything is up and running, commence */
        rcu_assign_pointer(ptbl->part[partno], p);

        /* suppress uevent if the disk suppresses it */
        if (!dev_get_uevent_suppress(ddev))
                kobject_uevent(&pdev->kobj, KOBJ_ADD);
        return p;

out_free_info:
        free_part_info(p);
out_free_stats:
        free_part_stats(p);
out_free:
        kfree(p);
        return ERR_PTR(err);
out_remove_file:
        device_remove_file(pdev, &dev_attr_whole_disk);
out_del:
        kobject_put(p->holder_dir);
        device_del(pdev);
out_put:
        put_device(pdev);
        return ERR_PTR(err);
}

static bool disk_unlock_native_capacity(struct gendisk *disk)
{
        const struct block_device_operations *bdops = disk->fops;

        if (bdops->unlock_native_capacity &&
            !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) {
                printk(KERN_CONT "enabling native capacity\n");
                bdops->unlock_native_capacity(disk);
                disk->flags |= GENHD_FL_NATIVE_CAPACITY;
                return true;
        } else {
                printk(KERN_CONT "truncated\n");
                return false;
        }
}

static int drop_partitions(struct gendisk *disk, struct block_device *bdev)
{
        struct disk_part_iter piter;
        struct hd_struct *part;
        int res;

        if (bdev->bd_part_count || bdev->bd_super)
                return -EBUSY;
        res = invalidate_partition(disk, 0);
        if (res)
                return res;

        disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
        while ((part = disk_part_iter_next(&piter)))
                delete_partition(disk, part->partno);
        disk_part_iter_exit(&piter);

        return 0;
}

static bool part_zone_aligned(struct gendisk *disk,
                              struct block_device *bdev,
                              sector_t from, sector_t size)
{
        unsigned int zone_sectors = bdev_zone_sectors(bdev);

        /*
         * If this function is called, then the disk is a zoned block device
         * (host-aware or host-managed). This can be detected even if the
         * zoned block device support is disabled (CONFIG_BLK_DEV_ZONED not
         * set). In this case, however, only host-aware devices will be seen
         * as a block device is not created for host-managed devices. Without
         * zoned block device support, host-aware drives can still be used as
         * regular block devices (no zone operation) and their zone size will
         * be reported as 0. Allow this case.
         */
        if (!zone_sectors)
                return true;

        /*
         * Check partition start and size alignement. If the drive has a
         * smaller last runt zone, ignore it and allow the partition to
         * use it. Check the zone size too: it should be a power of 2 number
         * of sectors.
         */
        if (WARN_ON_ONCE(!is_power_of_2(zone_sectors))) {
                u32 rem;

                div_u64_rem(from, zone_sectors, &rem);
                if (rem)
                        return false;
                if ((from + size) < get_capacity(disk)) {
                        div_u64_rem(size, zone_sectors, &rem);
                        if (rem)
                                return false;
                }

        } else {

                if (from & (zone_sectors - 1))
                        return false;
                if ((from + size) < get_capacity(disk) &&
                    (size & (zone_sectors - 1)))
                        return false;

        }

        return true;
}

int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
{
        struct parsed_partitions *state = NULL;
        struct hd_struct *part;
        int p, highest, res;
rescan:
        if (state && !IS_ERR(state)) {
                free_partitions(state);
                state = NULL;
        }

        res = drop_partitions(disk, bdev);
        if (res)
                return res;

        if (disk->fops->revalidate_disk)
                disk->fops->revalidate_disk(disk);
        check_disk_size_change(disk, bdev);
        bdev->bd_invalidated = 0;
        if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
                return 0;
        if (IS_ERR(state)) {
                /*
                 * I/O error reading the partition table.  If any
                 * partition code tried to read beyond EOD, retry
                 * after unlocking native capacity.
                 */
                if (PTR_ERR(state) == -ENOSPC) {
                        printk(KERN_WARNING "%s: partition table beyond EOD, ",
                               disk->disk_name);
                        if (disk_unlock_native_capacity(disk))
                                goto rescan;
                }
                return -EIO;
        }
        /*
         * If any partition code tried to read beyond EOD, try
         * unlocking native capacity even if partition table is
         * successfully read as we could be missing some partitions.
         */
        if (state->access_beyond_eod) {
                printk(KERN_WARNING
                       "%s: partition table partially beyond EOD, ",
                       disk->disk_name);
                if (disk_unlock_native_capacity(disk))
                        goto rescan;
        }

        /* tell userspace that the media / partition table may have changed */
        kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);

        /* Detect the highest partition number and preallocate
         * disk->part_tbl.  This is an optimization and not strictly
         * necessary.
         */
        for (p = 1, highest = 0; p < state->limit; p++)
                if (state->parts[p].size)
                        highest = p;

        disk_expand_part_tbl(disk, highest);

        /* add partitions */
        for (p = 1; p < state->limit; p++) {
                sector_t size, from;

                size = state->parts[p].size;
                if (!size)
                        continue;

                from = state->parts[p].from;
                if (from >= get_capacity(disk)) {
                        printk(KERN_WARNING
                               "%s: p%d start %llu is beyond EOD, ",
                               disk->disk_name, p, (unsigned long long) from);
                        if (disk_unlock_native_capacity(disk))
                                goto rescan;
                        continue;
                }

                if (from + size > get_capacity(disk)) {
                        printk(KERN_WARNING
                               "%s: p%d size %llu extends beyond EOD, ",
                               disk->disk_name, p, (unsigned long long) size);

                        if (disk_unlock_native_capacity(disk)) {
                                /* free state and restart */
                                goto rescan;
                        } else {
                                /*
                                 * we can not ignore partitions of broken tables
                                 * created by for example camera firmware, but
                                 * we limit them to the end of the disk to avoid
                                 * creating invalid block devices
                                 */
                                size = get_capacity(disk) - from;
                        }
                }

                /*
                 * On a zoned block device, partitions should be aligned on the
                 * device zone size (i.e. zone boundary crossing not allowed).
                 * Otherwise, resetting the write pointer of the last zone of
                 * one partition may impact the following partition.
                 */
                if (bdev_is_zoned(bdev) &&
                    !part_zone_aligned(disk, bdev, from, size)) {
                        printk(KERN_WARNING
                               "%s: p%d start %llu+%llu is not zone aligned\n",
                               disk->disk_name, p, (unsigned long long) from,
                               (unsigned long long) size);
                        continue;
                }

                part = add_partition(disk, p, from, size,
                                     state->parts[p].flags,
                                     &state->parts[p].info);
                if (IS_ERR(part)) {
                        printk(KERN_ERR " %s: p%d could not be added: %ld\n",
                               disk->disk_name, p, -PTR_ERR(part));
                        continue;
                }
#ifdef CONFIG_BLK_DEV_MD
                if (state->parts[p].flags & ADDPART_FLAG_RAID)
                        md_autodetect_dev(part_to_dev(part)->devt);
#endif
        }
        free_partitions(state);
        return 0;
}

int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
{
        int res;

        if (!bdev->bd_invalidated)
                return 0;

        res = drop_partitions(disk, bdev);
        if (res)
                return res;

        set_capacity(disk, 0);
        check_disk_size_change(disk, bdev);
        bdev->bd_invalidated = 0;
        /* tell userspace that the media / partition table may have changed */
        kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);

        return 0;
}

unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
{
        struct address_space *mapping = bdev->bd_inode->i_mapping;
        struct page *page;

        page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)), NULL);
        if (!IS_ERR(page)) {
                if (PageError(page))
                        goto fail;
                p->v = page;
                return (unsigned char *)page_address(page) +  ((n & ((1 << (PAGE_SHIFT - 9)) - 1)) << 9);
fail:
                put_page(page);
        }
        p->v = NULL;
        return NULL;
}

EXPORT_SYMBOL(read_dev_sector);