Merge branch 'for-4.12/post-merge' of git://git.kernel.dk/linux-block

[mirror_ubuntu-artful-kernel.git] / block / blk-mq-debugfs.c

/*
 * Copyright (C) 2017 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/debugfs.h>

#include <linux/blk-mq.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"

struct blk_mq_debugfs_attr {
        const char *name;
        umode_t mode;
        const struct file_operations *fops;
};

static int blk_mq_debugfs_seq_open(struct inode *inode, struct file *file,
                                   const struct seq_operations *ops)
{
        struct seq_file *m;
        int ret;

        ret = seq_open(file, ops);
        if (!ret) {
                m = file->private_data;
                m->private = inode->i_private;
        }
        return ret;
}

static int blk_flags_show(struct seq_file *m, const unsigned long flags,
                          const char *const *flag_name, int flag_name_count)
{
        bool sep = false;
        int i;

        for (i = 0; i < sizeof(flags) * BITS_PER_BYTE; i++) {
                if (!(flags & BIT(i)))
                        continue;
                if (sep)
                        seq_puts(m, " ");
                sep = true;
                if (i < flag_name_count && flag_name[i])
                        seq_puts(m, flag_name[i]);
                else
                        seq_printf(m, "%d", i);
        }
        return 0;
}

static const char *const blk_queue_flag_name[] = {
        [QUEUE_FLAG_QUEUED]      = "QUEUED",
        [QUEUE_FLAG_STOPPED]     = "STOPPED",
        [QUEUE_FLAG_SYNCFULL]    = "SYNCFULL",
        [QUEUE_FLAG_ASYNCFULL]   = "ASYNCFULL",
        [QUEUE_FLAG_DYING]       = "DYING",
        [QUEUE_FLAG_BYPASS]      = "BYPASS",
        [QUEUE_FLAG_BIDI]        = "BIDI",
        [QUEUE_FLAG_NOMERGES]    = "NOMERGES",
        [QUEUE_FLAG_SAME_COMP]   = "SAME_COMP",
        [QUEUE_FLAG_FAIL_IO]     = "FAIL_IO",
        [QUEUE_FLAG_STACKABLE]   = "STACKABLE",
        [QUEUE_FLAG_NONROT]      = "NONROT",
        [QUEUE_FLAG_IO_STAT]     = "IO_STAT",
        [QUEUE_FLAG_DISCARD]     = "DISCARD",
        [QUEUE_FLAG_NOXMERGES]   = "NOXMERGES",
        [QUEUE_FLAG_ADD_RANDOM]  = "ADD_RANDOM",
        [QUEUE_FLAG_SECERASE]    = "SECERASE",
        [QUEUE_FLAG_SAME_FORCE]  = "SAME_FORCE",
        [QUEUE_FLAG_DEAD]        = "DEAD",
        [QUEUE_FLAG_INIT_DONE]   = "INIT_DONE",
        [QUEUE_FLAG_NO_SG_MERGE] = "NO_SG_MERGE",
        [QUEUE_FLAG_POLL]        = "POLL",
        [QUEUE_FLAG_WC]          = "WC",
        [QUEUE_FLAG_FUA]         = "FUA",
        [QUEUE_FLAG_FLUSH_NQ]    = "FLUSH_NQ",
        [QUEUE_FLAG_DAX]         = "DAX",
        [QUEUE_FLAG_STATS]       = "STATS",
        [QUEUE_FLAG_POLL_STATS]  = "POLL_STATS",
        [QUEUE_FLAG_REGISTERED]  = "REGISTERED",
};

static int blk_queue_flags_show(struct seq_file *m, void *v)
{
        struct request_queue *q = m->private;

        blk_flags_show(m, q->queue_flags, blk_queue_flag_name,
                       ARRAY_SIZE(blk_queue_flag_name));
        seq_puts(m, "\n");
        return 0;
}

static ssize_t blk_queue_flags_store(struct file *file, const char __user *ubuf,
                                     size_t len, loff_t *offp)
{
        struct request_queue *q = file_inode(file)->i_private;
        char op[16] = { }, *s;

        len = min(len, sizeof(op) - 1);
        if (copy_from_user(op, ubuf, len))
                return -EFAULT;
        s = op;
        strsep(&s, " \t\n"); /* strip trailing whitespace */
        if (strcmp(op, "run") == 0) {
                blk_mq_run_hw_queues(q, true);
        } else if (strcmp(op, "start") == 0) {
                blk_mq_start_stopped_hw_queues(q, true);
        } else {
                pr_err("%s: unsupported operation %s. Use either 'run' or 'start'\n",
                       __func__, op);
                return -EINVAL;
        }
        return len;
}

static int blk_queue_flags_open(struct inode *inode, struct file *file)
{
        return single_open(file, blk_queue_flags_show, inode->i_private);
}

static const struct file_operations blk_queue_flags_fops = {
        .open           = blk_queue_flags_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
        .write          = blk_queue_flags_store,
};

static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
{
        if (stat->nr_samples) {
                seq_printf(m, "samples=%d, mean=%lld, min=%llu, max=%llu",
                           stat->nr_samples, stat->mean, stat->min, stat->max);
        } else {
                seq_puts(m, "samples=0");
        }
}

static int queue_poll_stat_show(struct seq_file *m, void *v)
{
        struct request_queue *q = m->private;
        int bucket;

        for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS/2; bucket++) {
                seq_printf(m, "read  (%d Bytes): ", 1 << (9+bucket));
                print_stat(m, &q->poll_stat[2*bucket]);
                seq_puts(m, "\n");

                seq_printf(m, "write (%d Bytes): ",  1 << (9+bucket));
                print_stat(m, &q->poll_stat[2*bucket+1]);
                seq_puts(m, "\n");
        }
        return 0;
}

static int queue_poll_stat_open(struct inode *inode, struct file *file)
{
        return single_open(file, queue_poll_stat_show, inode->i_private);
}

static const struct file_operations queue_poll_stat_fops = {
        .open           = queue_poll_stat_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static const char *const hctx_state_name[] = {
        [BLK_MQ_S_STOPPED]       = "STOPPED",
        [BLK_MQ_S_TAG_ACTIVE]    = "TAG_ACTIVE",
        [BLK_MQ_S_SCHED_RESTART] = "SCHED_RESTART",
        [BLK_MQ_S_TAG_WAITING]   = "TAG_WAITING",

};
static int hctx_state_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        blk_flags_show(m, hctx->state, hctx_state_name,
                       ARRAY_SIZE(hctx_state_name));
        seq_puts(m, "\n");
        return 0;
}

static int hctx_state_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_state_show, inode->i_private);
}

static const struct file_operations hctx_state_fops = {
        .open           = hctx_state_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static const char *const alloc_policy_name[] = {
        [BLK_TAG_ALLOC_FIFO]    = "fifo",
        [BLK_TAG_ALLOC_RR]      = "rr",
};

static const char *const hctx_flag_name[] = {
        [ilog2(BLK_MQ_F_SHOULD_MERGE)]  = "SHOULD_MERGE",
        [ilog2(BLK_MQ_F_TAG_SHARED)]    = "TAG_SHARED",
        [ilog2(BLK_MQ_F_SG_MERGE)]      = "SG_MERGE",
        [ilog2(BLK_MQ_F_BLOCKING)]      = "BLOCKING",
        [ilog2(BLK_MQ_F_NO_SCHED)]      = "NO_SCHED",
};

static int hctx_flags_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;
        const int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(hctx->flags);

        seq_puts(m, "alloc_policy=");
        if (alloc_policy < ARRAY_SIZE(alloc_policy_name) &&
            alloc_policy_name[alloc_policy])
                seq_puts(m, alloc_policy_name[alloc_policy]);
        else
                seq_printf(m, "%d", alloc_policy);
        seq_puts(m, " ");
        blk_flags_show(m,
                       hctx->flags ^ BLK_ALLOC_POLICY_TO_MQ_FLAG(alloc_policy),
                       hctx_flag_name, ARRAY_SIZE(hctx_flag_name));
        seq_puts(m, "\n");
        return 0;
}

static int hctx_flags_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_flags_show, inode->i_private);
}

static const struct file_operations hctx_flags_fops = {
        .open           = hctx_flags_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static const char *const op_name[] = {
        [REQ_OP_READ]           = "READ",
        [REQ_OP_WRITE]          = "WRITE",
        [REQ_OP_FLUSH]          = "FLUSH",
        [REQ_OP_DISCARD]        = "DISCARD",
        [REQ_OP_ZONE_REPORT]    = "ZONE_REPORT",
        [REQ_OP_SECURE_ERASE]   = "SECURE_ERASE",
        [REQ_OP_ZONE_RESET]     = "ZONE_RESET",
        [REQ_OP_WRITE_SAME]     = "WRITE_SAME",
        [REQ_OP_WRITE_ZEROES]   = "WRITE_ZEROES",
        [REQ_OP_SCSI_IN]        = "SCSI_IN",
        [REQ_OP_SCSI_OUT]       = "SCSI_OUT",
        [REQ_OP_DRV_IN]         = "DRV_IN",
        [REQ_OP_DRV_OUT]        = "DRV_OUT",
};

static const char *const cmd_flag_name[] = {
        [__REQ_FAILFAST_DEV]            = "FAILFAST_DEV",
        [__REQ_FAILFAST_TRANSPORT]      = "FAILFAST_TRANSPORT",
        [__REQ_FAILFAST_DRIVER]         = "FAILFAST_DRIVER",
        [__REQ_SYNC]                    = "SYNC",
        [__REQ_META]                    = "META",
        [__REQ_PRIO]                    = "PRIO",
        [__REQ_NOMERGE]                 = "NOMERGE",
        [__REQ_IDLE]                    = "IDLE",
        [__REQ_INTEGRITY]               = "INTEGRITY",
        [__REQ_FUA]                     = "FUA",
        [__REQ_PREFLUSH]                = "PREFLUSH",
        [__REQ_RAHEAD]                  = "RAHEAD",
        [__REQ_BACKGROUND]              = "BACKGROUND",
        [__REQ_NR_BITS]                 = "NR_BITS",
};

static const char *const rqf_name[] = {
        [ilog2((__force u32)RQF_SORTED)]                = "SORTED",
        [ilog2((__force u32)RQF_STARTED)]               = "STARTED",
        [ilog2((__force u32)RQF_QUEUED)]                = "QUEUED",
        [ilog2((__force u32)RQF_SOFTBARRIER)]           = "SOFTBARRIER",
        [ilog2((__force u32)RQF_FLUSH_SEQ)]             = "FLUSH_SEQ",
        [ilog2((__force u32)RQF_MIXED_MERGE)]           = "MIXED_MERGE",
        [ilog2((__force u32)RQF_MQ_INFLIGHT)]           = "MQ_INFLIGHT",
        [ilog2((__force u32)RQF_DONTPREP)]              = "DONTPREP",
        [ilog2((__force u32)RQF_PREEMPT)]               = "PREEMPT",
        [ilog2((__force u32)RQF_COPY_USER)]             = "COPY_USER",
        [ilog2((__force u32)RQF_FAILED)]                = "FAILED",
        [ilog2((__force u32)RQF_QUIET)]                 = "QUIET",
        [ilog2((__force u32)RQF_ELVPRIV)]               = "ELVPRIV",
        [ilog2((__force u32)RQF_IO_STAT)]               = "IO_STAT",
        [ilog2((__force u32)RQF_ALLOCED)]               = "ALLOCED",
        [ilog2((__force u32)RQF_PM)]                    = "PM",
        [ilog2((__force u32)RQF_HASHED)]                = "HASHED",
        [ilog2((__force u32)RQF_STATS)]                 = "STATS",
        [ilog2((__force u32)RQF_SPECIAL_PAYLOAD)]       = "SPECIAL_PAYLOAD",
};

static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
{
        struct request *rq = list_entry_rq(v);
        const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
        const unsigned int op = rq->cmd_flags & REQ_OP_MASK;

        seq_printf(m, "%p {.op=", rq);
        if (op < ARRAY_SIZE(op_name) && op_name[op])
                seq_printf(m, "%s", op_name[op]);
        else
                seq_printf(m, "%d", op);
        seq_puts(m, ", .cmd_flags=");
        blk_flags_show(m, rq->cmd_flags & ~REQ_OP_MASK, cmd_flag_name,
                       ARRAY_SIZE(cmd_flag_name));
        seq_puts(m, ", .rq_flags=");
        blk_flags_show(m, (__force unsigned int)rq->rq_flags, rqf_name,
                       ARRAY_SIZE(rqf_name));
        seq_printf(m, ", .tag=%d, .internal_tag=%d", rq->tag,
                   rq->internal_tag);
        if (mq_ops->show_rq)
                mq_ops->show_rq(m, rq);
        seq_puts(m, "}\n");
        return 0;
}

static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
        __acquires(&hctx->lock)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        spin_lock(&hctx->lock);
        return seq_list_start(&hctx->dispatch, *pos);
}

static void *hctx_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        return seq_list_next(v, &hctx->dispatch, pos);
}

static void hctx_dispatch_stop(struct seq_file *m, void *v)
        __releases(&hctx->lock)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        spin_unlock(&hctx->lock);
}

static const struct seq_operations hctx_dispatch_seq_ops = {
        .start  = hctx_dispatch_start,
        .next   = hctx_dispatch_next,
        .stop   = hctx_dispatch_stop,
        .show   = blk_mq_debugfs_rq_show,
};

static int hctx_dispatch_open(struct inode *inode, struct file *file)
{
        return blk_mq_debugfs_seq_open(inode, file, &hctx_dispatch_seq_ops);
}

static const struct file_operations hctx_dispatch_fops = {
        .open           = hctx_dispatch_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int hctx_ctx_map_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        sbitmap_bitmap_show(&hctx->ctx_map, m);
        return 0;
}

static int hctx_ctx_map_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_ctx_map_show, inode->i_private);
}

static const struct file_operations hctx_ctx_map_fops = {
        .open           = hctx_ctx_map_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void blk_mq_debugfs_tags_show(struct seq_file *m,
                                     struct blk_mq_tags *tags)
{
        seq_printf(m, "nr_tags=%u\n", tags->nr_tags);
        seq_printf(m, "nr_reserved_tags=%u\n", tags->nr_reserved_tags);
        seq_printf(m, "active_queues=%d\n",
                   atomic_read(&tags->active_queues));

        seq_puts(m, "\nbitmap_tags:\n");
        sbitmap_queue_show(&tags->bitmap_tags, m);

        if (tags->nr_reserved_tags) {
                seq_puts(m, "\nbreserved_tags:\n");
                sbitmap_queue_show(&tags->breserved_tags, m);
        }
}

static int hctx_tags_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;
        struct request_queue *q = hctx->queue;
        int res;

        res = mutex_lock_interruptible(&q->sysfs_lock);
        if (res)
                goto out;
        if (hctx->tags)
                blk_mq_debugfs_tags_show(m, hctx->tags);
        mutex_unlock(&q->sysfs_lock);

out:
        return res;
}

static int hctx_tags_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_tags_show, inode->i_private);
}

static const struct file_operations hctx_tags_fops = {
        .open           = hctx_tags_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_tags_bitmap_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;
        struct request_queue *q = hctx->queue;
        int res;

        res = mutex_lock_interruptible(&q->sysfs_lock);
        if (res)
                goto out;
        if (hctx->tags)
                sbitmap_bitmap_show(&hctx->tags->bitmap_tags.sb, m);
        mutex_unlock(&q->sysfs_lock);

out:
        return res;
}

static int hctx_tags_bitmap_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_tags_bitmap_show, inode->i_private);
}

static const struct file_operations hctx_tags_bitmap_fops = {
        .open           = hctx_tags_bitmap_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_sched_tags_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;
        struct request_queue *q = hctx->queue;
        int res;

        res = mutex_lock_interruptible(&q->sysfs_lock);
        if (res)
                goto out;
        if (hctx->sched_tags)
                blk_mq_debugfs_tags_show(m, hctx->sched_tags);
        mutex_unlock(&q->sysfs_lock);

out:
        return res;
}

static int hctx_sched_tags_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_sched_tags_show, inode->i_private);
}

static const struct file_operations hctx_sched_tags_fops = {
        .open           = hctx_sched_tags_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_sched_tags_bitmap_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;
        struct request_queue *q = hctx->queue;
        int res;

        res = mutex_lock_interruptible(&q->sysfs_lock);
        if (res)
                goto out;
        if (hctx->sched_tags)
                sbitmap_bitmap_show(&hctx->sched_tags->bitmap_tags.sb, m);
        mutex_unlock(&q->sysfs_lock);

out:
        return res;
}

static int hctx_sched_tags_bitmap_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_sched_tags_bitmap_show, inode->i_private);
}

static const struct file_operations hctx_sched_tags_bitmap_fops = {
        .open           = hctx_sched_tags_bitmap_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_io_poll_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        seq_printf(m, "considered=%lu\n", hctx->poll_considered);
        seq_printf(m, "invoked=%lu\n", hctx->poll_invoked);
        seq_printf(m, "success=%lu\n", hctx->poll_success);
        return 0;
}

static int hctx_io_poll_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_io_poll_show, inode->i_private);
}

static ssize_t hctx_io_poll_write(struct file *file, const char __user *buf,
                                  size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_hw_ctx *hctx = m->private;

        hctx->poll_considered = hctx->poll_invoked = hctx->poll_success = 0;
        return count;
}

static const struct file_operations hctx_io_poll_fops = {
        .open           = hctx_io_poll_open,
        .read           = seq_read,
        .write          = hctx_io_poll_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_dispatched_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;
        int i;

        seq_printf(m, "%8u\t%lu\n", 0U, hctx->dispatched[0]);

        for (i = 1; i < BLK_MQ_MAX_DISPATCH_ORDER - 1; i++) {
                unsigned int d = 1U << (i - 1);

                seq_printf(m, "%8u\t%lu\n", d, hctx->dispatched[i]);
        }

        seq_printf(m, "%8u+\t%lu\n", 1U << (i - 1), hctx->dispatched[i]);
        return 0;
}

static int hctx_dispatched_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_dispatched_show, inode->i_private);
}

static ssize_t hctx_dispatched_write(struct file *file, const char __user *buf,
                                     size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_hw_ctx *hctx = m->private;
        int i;

        for (i = 0; i < BLK_MQ_MAX_DISPATCH_ORDER; i++)
                hctx->dispatched[i] = 0;
        return count;
}

static const struct file_operations hctx_dispatched_fops = {
        .open           = hctx_dispatched_open,
        .read           = seq_read,
        .write          = hctx_dispatched_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_queued_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        seq_printf(m, "%lu\n", hctx->queued);
        return 0;
}

static int hctx_queued_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_queued_show, inode->i_private);
}

static ssize_t hctx_queued_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_hw_ctx *hctx = m->private;

        hctx->queued = 0;
        return count;
}

static const struct file_operations hctx_queued_fops = {
        .open           = hctx_queued_open,
        .read           = seq_read,
        .write          = hctx_queued_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_run_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        seq_printf(m, "%lu\n", hctx->run);
        return 0;
}

static int hctx_run_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_run_show, inode->i_private);
}

static ssize_t hctx_run_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_hw_ctx *hctx = m->private;

        hctx->run = 0;
        return count;
}

static const struct file_operations hctx_run_fops = {
        .open           = hctx_run_open,
        .read           = seq_read,
        .write          = hctx_run_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int hctx_active_show(struct seq_file *m, void *v)
{
        struct blk_mq_hw_ctx *hctx = m->private;

        seq_printf(m, "%d\n", atomic_read(&hctx->nr_active));
        return 0;
}

static int hctx_active_open(struct inode *inode, struct file *file)
{
        return single_open(file, hctx_active_show, inode->i_private);
}

static const struct file_operations hctx_active_fops = {
        .open           = hctx_active_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void *ctx_rq_list_start(struct seq_file *m, loff_t *pos)
        __acquires(&ctx->lock)
{
        struct blk_mq_ctx *ctx = m->private;

        spin_lock(&ctx->lock);
        return seq_list_start(&ctx->rq_list, *pos);
}

static void *ctx_rq_list_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct blk_mq_ctx *ctx = m->private;

        return seq_list_next(v, &ctx->rq_list, pos);
}

static void ctx_rq_list_stop(struct seq_file *m, void *v)
        __releases(&ctx->lock)
{
        struct blk_mq_ctx *ctx = m->private;

        spin_unlock(&ctx->lock);
}

static const struct seq_operations ctx_rq_list_seq_ops = {
        .start  = ctx_rq_list_start,
        .next   = ctx_rq_list_next,
        .stop   = ctx_rq_list_stop,
        .show   = blk_mq_debugfs_rq_show,
};

static int ctx_rq_list_open(struct inode *inode, struct file *file)
{
        return blk_mq_debugfs_seq_open(inode, file, &ctx_rq_list_seq_ops);
}

static const struct file_operations ctx_rq_list_fops = {
        .open           = ctx_rq_list_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int ctx_dispatched_show(struct seq_file *m, void *v)
{
        struct blk_mq_ctx *ctx = m->private;

        seq_printf(m, "%lu %lu\n", ctx->rq_dispatched[1], ctx->rq_dispatched[0]);
        return 0;
}

static int ctx_dispatched_open(struct inode *inode, struct file *file)
{
        return single_open(file, ctx_dispatched_show, inode->i_private);
}

static ssize_t ctx_dispatched_write(struct file *file, const char __user *buf,
                                    size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_ctx *ctx = m->private;

        ctx->rq_dispatched[0] = ctx->rq_dispatched[1] = 0;
        return count;
}

static const struct file_operations ctx_dispatched_fops = {
        .open           = ctx_dispatched_open,
        .read           = seq_read,
        .write          = ctx_dispatched_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int ctx_merged_show(struct seq_file *m, void *v)
{
        struct blk_mq_ctx *ctx = m->private;

        seq_printf(m, "%lu\n", ctx->rq_merged);
        return 0;
}

static int ctx_merged_open(struct inode *inode, struct file *file)
{
        return single_open(file, ctx_merged_show, inode->i_private);
}

static ssize_t ctx_merged_write(struct file *file, const char __user *buf,
                                    size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_ctx *ctx = m->private;

        ctx->rq_merged = 0;
        return count;
}

static const struct file_operations ctx_merged_fops = {
        .open           = ctx_merged_open,
        .read           = seq_read,
        .write          = ctx_merged_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int ctx_completed_show(struct seq_file *m, void *v)
{
        struct blk_mq_ctx *ctx = m->private;

        seq_printf(m, "%lu %lu\n", ctx->rq_completed[1], ctx->rq_completed[0]);
        return 0;
}

static int ctx_completed_open(struct inode *inode, struct file *file)
{
        return single_open(file, ctx_completed_show, inode->i_private);
}

static ssize_t ctx_completed_write(struct file *file, const char __user *buf,
                                   size_t count, loff_t *ppos)
{
        struct seq_file *m = file->private_data;
        struct blk_mq_ctx *ctx = m->private;

        ctx->rq_completed[0] = ctx->rq_completed[1] = 0;
        return count;
}

static const struct file_operations ctx_completed_fops = {
        .open           = ctx_completed_open,
        .read           = seq_read,
        .write          = ctx_completed_write,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
        {"poll_stat", 0400, &queue_poll_stat_fops},
        {"state", 0600, &blk_queue_flags_fops},
        {},
};

static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
        {"state", 0400, &hctx_state_fops},
        {"flags", 0400, &hctx_flags_fops},
        {"dispatch", 0400, &hctx_dispatch_fops},
        {"ctx_map", 0400, &hctx_ctx_map_fops},
        {"tags", 0400, &hctx_tags_fops},
        {"tags_bitmap", 0400, &hctx_tags_bitmap_fops},
        {"sched_tags", 0400, &hctx_sched_tags_fops},
        {"sched_tags_bitmap", 0400, &hctx_sched_tags_bitmap_fops},
        {"io_poll", 0600, &hctx_io_poll_fops},
        {"dispatched", 0600, &hctx_dispatched_fops},
        {"queued", 0600, &hctx_queued_fops},
        {"run", 0600, &hctx_run_fops},
        {"active", 0400, &hctx_active_fops},
        {},
};

static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
        {"rq_list", 0400, &ctx_rq_list_fops},
        {"dispatched", 0600, &ctx_dispatched_fops},
        {"merged", 0600, &ctx_merged_fops},
        {"completed", 0600, &ctx_completed_fops},
        {},
};

int blk_mq_debugfs_register(struct request_queue *q)
{
        if (!blk_debugfs_root)
                return -ENOENT;

        q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent),
                                            blk_debugfs_root);
        if (!q->debugfs_dir)
                goto err;

        if (blk_mq_debugfs_register_mq(q))
                goto err;

        return 0;

err:
        blk_mq_debugfs_unregister(q);
        return -ENOMEM;
}

void blk_mq_debugfs_unregister(struct request_queue *q)
{
        debugfs_remove_recursive(q->debugfs_dir);
        q->mq_debugfs_dir = NULL;
        q->debugfs_dir = NULL;
}

static bool debugfs_create_files(struct dentry *parent, void *data,
                                const struct blk_mq_debugfs_attr *attr)
{
        for (; attr->name; attr++) {
                if (!debugfs_create_file(attr->name, attr->mode, parent,
                                         data, attr->fops))
                        return false;
        }
        return true;
}

static int blk_mq_debugfs_register_ctx(struct request_queue *q,
                                       struct blk_mq_ctx *ctx,
                                       struct dentry *hctx_dir)
{
        struct dentry *ctx_dir;
        char name[20];

        snprintf(name, sizeof(name), "cpu%u", ctx->cpu);
        ctx_dir = debugfs_create_dir(name, hctx_dir);
        if (!ctx_dir)
                return -ENOMEM;

        if (!debugfs_create_files(ctx_dir, ctx, blk_mq_debugfs_ctx_attrs))
                return -ENOMEM;

        return 0;
}

static int blk_mq_debugfs_register_hctx(struct request_queue *q,
                                        struct blk_mq_hw_ctx *hctx)
{
        struct blk_mq_ctx *ctx;
        struct dentry *hctx_dir;
        char name[20];
        int i;

        snprintf(name, sizeof(name), "%u", hctx->queue_num);
        hctx_dir = debugfs_create_dir(name, q->mq_debugfs_dir);
        if (!hctx_dir)
                return -ENOMEM;

        if (!debugfs_create_files(hctx_dir, hctx, blk_mq_debugfs_hctx_attrs))
                return -ENOMEM;

        hctx_for_each_ctx(hctx, ctx, i) {
                if (blk_mq_debugfs_register_ctx(q, ctx, hctx_dir))
                        return -ENOMEM;
        }

        return 0;
}

int blk_mq_debugfs_register_mq(struct request_queue *q)
{
        struct blk_mq_hw_ctx *hctx;
        int i;

        if (!q->debugfs_dir)
                return -ENOENT;

        q->mq_debugfs_dir = debugfs_create_dir("mq", q->debugfs_dir);
        if (!q->mq_debugfs_dir)
                goto err;

        if (!debugfs_create_files(q->mq_debugfs_dir, q, blk_mq_debugfs_queue_attrs))
                goto err;

        queue_for_each_hw_ctx(q, hctx, i) {
                if (blk_mq_debugfs_register_hctx(q, hctx))
                        goto err;
        }

        return 0;

err:
        blk_mq_debugfs_unregister_mq(q);
        return -ENOMEM;
}

void blk_mq_debugfs_unregister_mq(struct request_queue *q)
{
        debugfs_remove_recursive(q->mq_debugfs_dir);
        q->mq_debugfs_dir = NULL;
}