/*
   * 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-debugfs.h"

  #include "blk-mq-tag.h"

  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;
  }

  #define QUEUE_FLAG_NAME(name) [QUEUE_FLAG_##name] = #name

  static const char *const blk_queue_flag_name[] = {

  	QUEUE_FLAG_NAME(QUEUED),
  	QUEUE_FLAG_NAME(STOPPED),

  	QUEUE_FLAG_NAME(DYING),
  	QUEUE_FLAG_NAME(BYPASS),
  	QUEUE_FLAG_NAME(BIDI),
  	QUEUE_FLAG_NAME(NOMERGES),
  	QUEUE_FLAG_NAME(SAME_COMP),
  	QUEUE_FLAG_NAME(FAIL_IO),
  	QUEUE_FLAG_NAME(STACKABLE),
  	QUEUE_FLAG_NAME(NONROT),
  	QUEUE_FLAG_NAME(IO_STAT),
  	QUEUE_FLAG_NAME(DISCARD),
  	QUEUE_FLAG_NAME(NOXMERGES),
  	QUEUE_FLAG_NAME(ADD_RANDOM),
  	QUEUE_FLAG_NAME(SECERASE),
  	QUEUE_FLAG_NAME(SAME_FORCE),
  	QUEUE_FLAG_NAME(DEAD),
  	QUEUE_FLAG_NAME(INIT_DONE),
  	QUEUE_FLAG_NAME(NO_SG_MERGE),
  	QUEUE_FLAG_NAME(POLL),
  	QUEUE_FLAG_NAME(WC),
  	QUEUE_FLAG_NAME(FUA),
  	QUEUE_FLAG_NAME(FLUSH_NQ),
  	QUEUE_FLAG_NAME(DAX),
  	QUEUE_FLAG_NAME(STATS),
  	QUEUE_FLAG_NAME(POLL_STATS),
  	QUEUE_FLAG_NAME(REGISTERED),

  	QUEUE_FLAG_NAME(SCSI_PASSTHROUGH),
  	QUEUE_FLAG_NAME(QUIESCED),

  };

  #undef QUEUE_FLAG_NAME

  static int queue_state_show(void *data, struct seq_file *m)

  {

  	struct request_queue *q = data;

  
  	blk_flags_show(m, q->queue_flags, blk_queue_flag_name,
  		       ARRAY_SIZE(blk_queue_flag_name));

  	seq_puts(m, "
  ");

  	return 0;
  }

  static ssize_t queue_state_write(void *data, const char __user *buf,
  				 size_t count, loff_t *ppos)

  {

  	struct request_queue *q = data;

  	char opbuf[16] = { }, *op;

  	/*
  	 * The "state" attribute is removed after blk_cleanup_queue() has called
  	 * blk_mq_free_queue(). Return if QUEUE_FLAG_DEAD has been set to avoid
  	 * triggering a use-after-free.
  	 */
  	if (blk_queue_dead(q))
  		return -ENOENT;

  	if (count >= sizeof(opbuf)) {

  		pr_err("%s: operation too long
  ", __func__);
  		goto inval;
  	}

  	if (copy_from_user(opbuf, buf, count))

  		return -EFAULT;

  	op = strstrip(opbuf);

  	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 if (strcmp(op, "kick") == 0) {
  		blk_mq_kick_requeue_list(q);

  	} else {

  		pr_err("%s: unsupported operation '%s'
  ", __func__, op);
  inval:

  		pr_err("%s: use 'run', 'start' or 'kick'
  ", __func__);

  		return -EINVAL;
  	}

  	return count;

  }

  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_write_hint_show(void *data, struct seq_file *m)
  {
  	struct request_queue *q = data;
  	int i;
  
  	for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
  		seq_printf(m, "hint%d: %llu
  ", i, q->write_hints[i]);
  
  	return 0;
  }
  
  static ssize_t queue_write_hint_store(void *data, const char __user *buf,
  				      size_t count, loff_t *ppos)
  {
  	struct request_queue *q = data;
  	int i;
  
  	for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
  		q->write_hints[i] = 0;
  
  	return count;
  }

  static int queue_poll_stat_show(void *data, struct seq_file *m)

  {

  	struct request_queue *q = data;

  	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, "
  ");

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

  	return 0;
  }

  #define HCTX_STATE_NAME(name) [BLK_MQ_S_##name] = #name

  static const char *const hctx_state_name[] = {

  	HCTX_STATE_NAME(STOPPED),
  	HCTX_STATE_NAME(TAG_ACTIVE),
  	HCTX_STATE_NAME(SCHED_RESTART),
  	HCTX_STATE_NAME(TAG_WAITING),
  	HCTX_STATE_NAME(START_ON_RUN),

  };

  #undef HCTX_STATE_NAME

  static int hctx_state_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  	blk_flags_show(m, hctx->state, hctx_state_name,
  		       ARRAY_SIZE(hctx_state_name));

  	seq_puts(m, "
  ");

  	return 0;
  }

  #define BLK_TAG_ALLOC_NAME(name) [BLK_TAG_ALLOC_##name] = #name

  static const char *const alloc_policy_name[] = {

  	BLK_TAG_ALLOC_NAME(FIFO),
  	BLK_TAG_ALLOC_NAME(RR),

  };

  #undef BLK_TAG_ALLOC_NAME

  #define HCTX_FLAG_NAME(name) [ilog2(BLK_MQ_F_##name)] = #name

  static const char *const hctx_flag_name[] = {

  	HCTX_FLAG_NAME(SHOULD_MERGE),
  	HCTX_FLAG_NAME(TAG_SHARED),
  	HCTX_FLAG_NAME(SG_MERGE),
  	HCTX_FLAG_NAME(BLOCKING),
  	HCTX_FLAG_NAME(NO_SCHED),

  };

  #undef HCTX_FLAG_NAME

  static int hctx_flags_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  	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, "
  ");

  	return 0;
  }

  #define REQ_OP_NAME(name) [REQ_OP_##name] = #name

  static const char *const op_name[] = {

  	REQ_OP_NAME(READ),
  	REQ_OP_NAME(WRITE),
  	REQ_OP_NAME(FLUSH),
  	REQ_OP_NAME(DISCARD),
  	REQ_OP_NAME(ZONE_REPORT),
  	REQ_OP_NAME(SECURE_ERASE),
  	REQ_OP_NAME(ZONE_RESET),
  	REQ_OP_NAME(WRITE_SAME),
  	REQ_OP_NAME(WRITE_ZEROES),
  	REQ_OP_NAME(SCSI_IN),
  	REQ_OP_NAME(SCSI_OUT),
  	REQ_OP_NAME(DRV_IN),
  	REQ_OP_NAME(DRV_OUT),

  };

  #undef REQ_OP_NAME

  #define CMD_FLAG_NAME(name) [__REQ_##name] = #name

  static const char *const cmd_flag_name[] = {

  	CMD_FLAG_NAME(FAILFAST_DEV),
  	CMD_FLAG_NAME(FAILFAST_TRANSPORT),
  	CMD_FLAG_NAME(FAILFAST_DRIVER),
  	CMD_FLAG_NAME(SYNC),
  	CMD_FLAG_NAME(META),
  	CMD_FLAG_NAME(PRIO),
  	CMD_FLAG_NAME(NOMERGE),
  	CMD_FLAG_NAME(IDLE),
  	CMD_FLAG_NAME(INTEGRITY),
  	CMD_FLAG_NAME(FUA),
  	CMD_FLAG_NAME(PREFLUSH),
  	CMD_FLAG_NAME(RAHEAD),
  	CMD_FLAG_NAME(BACKGROUND),
  	CMD_FLAG_NAME(NOUNMAP),

  	CMD_FLAG_NAME(NOWAIT),

  };

  #undef CMD_FLAG_NAME

  #define RQF_NAME(name) [ilog2((__force u32)RQF_##name)] = #name

  static const char *const rqf_name[] = {

  	RQF_NAME(SORTED),
  	RQF_NAME(STARTED),
  	RQF_NAME(QUEUED),
  	RQF_NAME(SOFTBARRIER),
  	RQF_NAME(FLUSH_SEQ),
  	RQF_NAME(MIXED_MERGE),
  	RQF_NAME(MQ_INFLIGHT),
  	RQF_NAME(DONTPREP),
  	RQF_NAME(PREEMPT),
  	RQF_NAME(COPY_USER),
  	RQF_NAME(FAILED),
  	RQF_NAME(QUIET),
  	RQF_NAME(ELVPRIV),
  	RQF_NAME(IO_STAT),
  	RQF_NAME(ALLOCED),
  	RQF_NAME(PM),
  	RQF_NAME(HASHED),
  	RQF_NAME(STATS),
  	RQF_NAME(SPECIAL_PAYLOAD),

  };

  #undef RQF_NAME

  #define RQAF_NAME(name) [REQ_ATOM_##name] = #name
  static const char *const rqaf_name[] = {
  	RQAF_NAME(COMPLETE),
  	RQAF_NAME(STARTED),
  	RQAF_NAME(POLL_SLEPT),
  };
  #undef RQAF_NAME

  int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq)

  {

  	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_puts(m, ", .atomic_flags=");
  	blk_flags_show(m, rq->atomic_flags, rqaf_name, ARRAY_SIZE(rqaf_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, "}
  ");

  	return 0;
  }

  EXPORT_SYMBOL_GPL(__blk_mq_debugfs_rq_show);
  
  int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
  {
  	return __blk_mq_debugfs_rq_show(m, list_entry_rq(v));
  }

  EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);

  static void *queue_requeue_list_start(struct seq_file *m, loff_t *pos)
  	__acquires(&q->requeue_lock)
  {
  	struct request_queue *q = m->private;
  
  	spin_lock_irq(&q->requeue_lock);
  	return seq_list_start(&q->requeue_list, *pos);
  }
  
  static void *queue_requeue_list_next(struct seq_file *m, void *v, loff_t *pos)
  {
  	struct request_queue *q = m->private;
  
  	return seq_list_next(v, &q->requeue_list, pos);
  }
  
  static void queue_requeue_list_stop(struct seq_file *m, void *v)
  	__releases(&q->requeue_lock)
  {
  	struct request_queue *q = m->private;
  
  	spin_unlock_irq(&q->requeue_lock);
  }
  
  static const struct seq_operations queue_requeue_list_seq_ops = {
  	.start	= queue_requeue_list_start,
  	.next	= queue_requeue_list_next,
  	.stop	= queue_requeue_list_stop,
  	.show	= blk_mq_debugfs_rq_show,
  };

  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,
  };

  struct show_busy_params {
  	struct seq_file		*m;
  	struct blk_mq_hw_ctx	*hctx;
  };
  
  /*
   * Note: the state of a request may change while this function is in progress,
   * e.g. due to a concurrent blk_mq_finish_request() call.
   */
  static void hctx_show_busy_rq(struct request *rq, void *data, bool reserved)
  {
  	const struct show_busy_params *params = data;
  
  	if (blk_mq_map_queue(rq->q, rq->mq_ctx->cpu) == params->hctx &&
  	    test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
  		__blk_mq_debugfs_rq_show(params->m,
  					 list_entry_rq(&rq->queuelist));
  }
  
  static int hctx_busy_show(void *data, struct seq_file *m)
  {
  	struct blk_mq_hw_ctx *hctx = data;
  	struct show_busy_params params = { .m = m, .hctx = hctx };
  
  	blk_mq_tagset_busy_iter(hctx->queue->tag_set, hctx_show_busy_rq,
  				&params);
  
  	return 0;
  }

  static int hctx_ctx_map_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static void blk_mq_debugfs_tags_show(struct seq_file *m,
  				     struct blk_mq_tags *tags)
  {
  	seq_printf(m, "nr_tags=%u
  ", tags->nr_tags);
  	seq_printf(m, "nr_reserved_tags=%u
  ", tags->nr_reserved_tags);
  	seq_printf(m, "active_queues=%d
  ",
  		   atomic_read(&tags->active_queues));
  
  	seq_puts(m, "
  bitmap_tags:
  ");
  	sbitmap_queue_show(&tags->bitmap_tags, m);
  
  	if (tags->nr_reserved_tags) {
  		seq_puts(m, "
  breserved_tags:
  ");
  		sbitmap_queue_show(&tags->breserved_tags, m);
  	}
  }

  static int hctx_tags_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  	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_bitmap_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  	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_sched_tags_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  	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_bitmap_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  	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_io_poll_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static ssize_t hctx_io_poll_write(void *data, const char __user *buf,

  				  size_t count, loff_t *ppos)
  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static int hctx_dispatched_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static ssize_t hctx_dispatched_write(void *data, const char __user *buf,

  				     size_t count, loff_t *ppos)
  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static int hctx_queued_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static ssize_t hctx_queued_write(void *data, const char __user *buf,

  				 size_t count, loff_t *ppos)
  {

  	struct blk_mq_hw_ctx *hctx = data;

  
  	hctx->queued = 0;
  	return count;
  }

  static int hctx_run_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  static ssize_t hctx_run_write(void *data, const char __user *buf, size_t count,
  			      loff_t *ppos)

  {

  	struct blk_mq_hw_ctx *hctx = data;

  
  	hctx->run = 0;
  	return count;
  }

  static int hctx_active_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_hw_ctx *hctx = data;

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

  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_dispatched_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_ctx *ctx = data;

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

  static ssize_t ctx_dispatched_write(void *data, const char __user *buf,

  				    size_t count, loff_t *ppos)
  {

  	struct blk_mq_ctx *ctx = data;

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

  static int ctx_merged_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_ctx *ctx = data;

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

  static ssize_t ctx_merged_write(void *data, const char __user *buf,
  				size_t count, loff_t *ppos)

  {

  	struct blk_mq_ctx *ctx = data;

  
  	ctx->rq_merged = 0;
  	return count;
  }

  static int ctx_completed_show(void *data, struct seq_file *m)

  {

  	struct blk_mq_ctx *ctx = data;

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

  static ssize_t ctx_completed_write(void *data, const char __user *buf,
  				   size_t count, loff_t *ppos)

  {

  	struct blk_mq_ctx *ctx = data;
  
  	ctx->rq_completed[0] = ctx->rq_completed[1] = 0;
  	return count;

  }

  static int blk_mq_debugfs_show(struct seq_file *m, void *v)
  {
  	const struct blk_mq_debugfs_attr *attr = m->private;
  	void *data = d_inode(m->file->f_path.dentry->d_parent)->i_private;
  
  	return attr->show(data, m);
  }
  
  static ssize_t blk_mq_debugfs_write(struct file *file, const char __user *buf,
  				    size_t count, loff_t *ppos)

  {
  	struct seq_file *m = file->private_data;

  	const struct blk_mq_debugfs_attr *attr = m->private;
  	void *data = d_inode(file->f_path.dentry->d_parent)->i_private;

  	/*
  	 * Attributes that only implement .seq_ops are read-only and 'attr' is
  	 * the same with 'data' in this case.
  	 */
  	if (attr == data || !attr->write)

  		return -EPERM;
  
  	return attr->write(data, buf, count, ppos);
  }
  
  static int blk_mq_debugfs_open(struct inode *inode, struct file *file)
  {
  	const struct blk_mq_debugfs_attr *attr = inode->i_private;
  	void *data = d_inode(file->f_path.dentry->d_parent)->i_private;
  	struct seq_file *m;
  	int ret;
  
  	if (attr->seq_ops) {
  		ret = seq_open(file, attr->seq_ops);
  		if (!ret) {
  			m = file->private_data;
  			m->private = data;
  		}
  		return ret;
  	}
  
  	if (WARN_ON_ONCE(!attr->show))
  		return -EPERM;
  
  	return single_open(file, blk_mq_debugfs_show, inode->i_private);

  }

  static int blk_mq_debugfs_release(struct inode *inode, struct file *file)
  {
  	const struct blk_mq_debugfs_attr *attr = inode->i_private;
  
  	if (attr->show)
  		return single_release(inode, file);
  	else
  		return seq_release(inode, file);
  }

  static const struct file_operations blk_mq_debugfs_fops = {

  	.open		= blk_mq_debugfs_open,

  	.read		= seq_read,

  	.write		= blk_mq_debugfs_write,

  	.llseek		= seq_lseek,

  	.release	= blk_mq_debugfs_release,

  };

  static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {

  	{"poll_stat", 0400, queue_poll_stat_show},

  	{"requeue_list", 0400, .seq_ops = &queue_requeue_list_seq_ops},

  	{"state", 0600, queue_state_show, queue_state_write},

  	{"write_hints", 0600, queue_write_hint_show, queue_write_hint_store},

  	{},
  };

  static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {

  	{"state", 0400, hctx_state_show},
  	{"flags", 0400, hctx_flags_show},
  	{"dispatch", 0400, .seq_ops = &hctx_dispatch_seq_ops},

  	{"busy", 0400, hctx_busy_show},

  	{"ctx_map", 0400, hctx_ctx_map_show},
  	{"tags", 0400, hctx_tags_show},
  	{"tags_bitmap", 0400, hctx_tags_bitmap_show},
  	{"sched_tags", 0400, hctx_sched_tags_show},
  	{"sched_tags_bitmap", 0400, hctx_sched_tags_bitmap_show},
  	{"io_poll", 0600, hctx_io_poll_show, hctx_io_poll_write},
  	{"dispatched", 0600, hctx_dispatched_show, hctx_dispatched_write},
  	{"queued", 0600, hctx_queued_show, hctx_queued_write},
  	{"run", 0600, hctx_run_show, hctx_run_write},
  	{"active", 0400, hctx_active_show},

  	{},

  };
  
  static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {

  	{"rq_list", 0400, .seq_ops = &ctx_rq_list_seq_ops},
  	{"dispatched", 0600, ctx_dispatched_show, ctx_dispatched_write},
  	{"merged", 0600, ctx_merged_show, ctx_merged_write},
  	{"completed", 0600, ctx_completed_show, ctx_completed_write},

  	{},

  };

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

  int blk_mq_debugfs_register(struct request_queue *q)

  {

  	struct blk_mq_hw_ctx *hctx;
  	int i;

  	if (!blk_debugfs_root)

  		return -ENOENT;

  	q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent),
  					    blk_debugfs_root);

  	if (!q->debugfs_dir)

  		return -ENOMEM;

  	if (!debugfs_create_files(q->debugfs_dir, q,
  				  blk_mq_debugfs_queue_attrs))

  		goto err;

  	/*

  	 * blk_mq_init_sched() attempted to do this already, but q->debugfs_dir

  	 * didn't exist yet (because we don't know what to name the directory
  	 * until the queue is registered to a gendisk).
  	 */

  	if (q->elevator && !q->sched_debugfs_dir)
  		blk_mq_debugfs_register_sched(q);
  
  	/* Similarly, blk_mq_init_hctx() couldn't do this previously. */

  	queue_for_each_hw_ctx(q, hctx, i) {
  		if (!hctx->debugfs_dir && blk_mq_debugfs_register_hctx(q, hctx))
  			goto err;

  		if (q->elevator && !hctx->sched_debugfs_dir &&
  		    blk_mq_debugfs_register_sched_hctx(q, hctx))
  			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->sched_debugfs_dir = NULL;

  	q->debugfs_dir = NULL;
  }

  static int blk_mq_debugfs_register_ctx(struct blk_mq_hw_ctx *hctx,
  				       struct blk_mq_ctx *ctx)

  {
  	struct dentry *ctx_dir;
  	char name[20];

  
  	snprintf(name, sizeof(name), "cpu%u", ctx->cpu);

  	ctx_dir = debugfs_create_dir(name, hctx->debugfs_dir);

  	if (!ctx_dir)
  		return -ENOMEM;

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

  
  	return 0;
  }

  int blk_mq_debugfs_register_hctx(struct request_queue *q,
  				 struct blk_mq_hw_ctx *hctx)

  {
  	struct blk_mq_ctx *ctx;

  	char name[20];
  	int i;

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

  	snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);

  	hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);
  	if (!hctx->debugfs_dir)

  		return -ENOMEM;

  	if (!debugfs_create_files(hctx->debugfs_dir, hctx,
  				  blk_mq_debugfs_hctx_attrs))
  		goto err;

  
  	hctx_for_each_ctx(hctx, ctx, i) {

  		if (blk_mq_debugfs_register_ctx(hctx, ctx))
  			goto err;

  	}
  
  	return 0;

  
  err:
  	blk_mq_debugfs_unregister_hctx(hctx);
  	return -ENOMEM;
  }
  
  void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
  {
  	debugfs_remove_recursive(hctx->debugfs_dir);

  	hctx->sched_debugfs_dir = NULL;

  	hctx->debugfs_dir = NULL;

  }

  int blk_mq_debugfs_register_hctxs(struct request_queue *q)

  {
  	struct blk_mq_hw_ctx *hctx;
  	int i;

  	queue_for_each_hw_ctx(q, hctx, i) {
  		if (blk_mq_debugfs_register_hctx(q, hctx))

  			return -ENOMEM;

  	}
  
  	return 0;

  }

  void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)

  {

  	struct blk_mq_hw_ctx *hctx;
  	int i;
  
  	queue_for_each_hw_ctx(q, hctx, i)
  		blk_mq_debugfs_unregister_hctx(hctx);

  }

  
  int blk_mq_debugfs_register_sched(struct request_queue *q)
  {
  	struct elevator_type *e = q->elevator->type;
  
  	if (!q->debugfs_dir)
  		return -ENOENT;
  
  	if (!e->queue_debugfs_attrs)
  		return 0;
  
  	q->sched_debugfs_dir = debugfs_create_dir("sched", q->debugfs_dir);
  	if (!q->sched_debugfs_dir)
  		return -ENOMEM;
  
  	if (!debugfs_create_files(q->sched_debugfs_dir, q,
  				  e->queue_debugfs_attrs))
  		goto err;
  
  	return 0;
  
  err:
  	blk_mq_debugfs_unregister_sched(q);
  	return -ENOMEM;
  }
  
  void blk_mq_debugfs_unregister_sched(struct request_queue *q)
  {
  	debugfs_remove_recursive(q->sched_debugfs_dir);
  	q->sched_debugfs_dir = NULL;
  }
  
  int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
  				       struct blk_mq_hw_ctx *hctx)
  {
  	struct elevator_type *e = q->elevator->type;
  
  	if (!hctx->debugfs_dir)
  		return -ENOENT;
  
  	if (!e->hctx_debugfs_attrs)
  		return 0;
  
  	hctx->sched_debugfs_dir = debugfs_create_dir("sched",
  						     hctx->debugfs_dir);
  	if (!hctx->sched_debugfs_dir)
  		return -ENOMEM;
  
  	if (!debugfs_create_files(hctx->sched_debugfs_dir, hctx,
  				  e->hctx_debugfs_attrs))
  		return -ENOMEM;
  
  	return 0;
  }
  
  void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
  {
  	debugfs_remove_recursive(hctx->sched_debugfs_dir);
  	hctx->sched_debugfs_dir = NULL;
  }