// SPDX-License-Identifier: GPL-2.0

  /*
   *  MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
   *  for the blk-mq scheduling framework
   *
   *  Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
   */
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/blkdev.h>
  #include <linux/blk-mq.h>
  #include <linux/elevator.h>
  #include <linux/bio.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <linux/compiler.h>
  #include <linux/rbtree.h>
  #include <linux/sbitmap.h>

  #include <trace/events/block.h>

  #include "blk.h"
  #include "blk-mq.h"

  #include "blk-mq-debugfs.h"

  #include "blk-mq-tag.h"
  #include "blk-mq-sched.h"
  
  /*

   * See Documentation/block/deadline-iosched.rst

   */
  static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  static const int writes_starved = 2;    /* max times reads can starve a write */
  static const int fifo_batch = 16;       /* # of sequential requests treated as one
  				     by the above parameters. For throughput. */

  enum dd_data_dir {
  	DD_READ		= READ,
  	DD_WRITE	= WRITE,
  };
  
  enum { DD_DIR_COUNT = 2 };

  enum dd_prio {
  	DD_RT_PRIO	= 0,
  	DD_BE_PRIO	= 1,
  	DD_IDLE_PRIO	= 2,
  	DD_PRIO_MAX	= 2,
  };
  
  enum { DD_PRIO_COUNT = 3 };

  /* I/O statistics per I/O priority. */
  struct io_stats_per_prio {
  	local_t inserted;
  	local_t merged;
  	local_t dispatched;
  	local_t completed;
  };

  /* I/O statistics for all I/O priorities (enum dd_prio). */
  struct io_stats {
  	struct io_stats_per_prio stats[DD_PRIO_COUNT];
  };

  /*
   * Deadline scheduler data per I/O priority (enum dd_prio). Requests are
   * present on both sort_list[] and fifo_list[].
   */
  struct dd_per_prio {
  	struct list_head dispatch;
  	struct rb_root sort_list[DD_DIR_COUNT];
  	struct list_head fifo_list[DD_DIR_COUNT];
  	/* Next request in FIFO order. Read, write or both are NULL. */
  	struct request *next_rq[DD_DIR_COUNT];
  };

  struct deadline_data {
  	/*
  	 * run time data
  	 */

  	struct dd_per_prio per_prio[DD_PRIO_COUNT];

  	/* Data direction of latest dispatched request. */
  	enum dd_data_dir last_dir;

  	unsigned int batching;		/* number of sequential requests made */
  	unsigned int starved;		/* times reads have starved writes */

  	struct io_stats __percpu *stats;

  	/*
  	 * settings that change how the i/o scheduler behaves
  	 */

  	int fifo_expire[DD_DIR_COUNT];

  	int fifo_batch;
  	int writes_starved;
  	int front_merges;

  	u32 async_depth;

  
  	spinlock_t lock;

  	spinlock_t zone_lock;

  };

  /* Count one event of type 'event_type' and with I/O priority 'prio' */
  #define dd_count(dd, event_type, prio) do {				\
  	struct io_stats *io_stats = get_cpu_ptr((dd)->stats);		\
  									\
  	BUILD_BUG_ON(!__same_type((dd), struct deadline_data *));	\
  	BUILD_BUG_ON(!__same_type((prio), enum dd_prio));		\
  	local_inc(&io_stats->stats[(prio)].event_type);			\
  	put_cpu_ptr(io_stats);						\
  } while (0)
  
  /*
   * Returns the total number of dd_count(dd, event_type, prio) calls across all
   * CPUs. No locking or barriers since it is fine if the returned sum is slightly
   * outdated.
   */
  #define dd_sum(dd, event_type, prio) ({					\
  	unsigned int cpu;						\
  	u32 sum = 0;							\
  									\
  	BUILD_BUG_ON(!__same_type((dd), struct deadline_data *));	\
  	BUILD_BUG_ON(!__same_type((prio), enum dd_prio));		\
  	for_each_present_cpu(cpu)					\
  		sum += local_read(&per_cpu_ptr((dd)->stats, cpu)->	\
  				  stats[(prio)].event_type);		\
  	sum;								\
  })

  /* Maps an I/O priority class to a deadline scheduler priority. */
  static const enum dd_prio ioprio_class_to_prio[] = {
  	[IOPRIO_CLASS_NONE]	= DD_BE_PRIO,
  	[IOPRIO_CLASS_RT]	= DD_RT_PRIO,
  	[IOPRIO_CLASS_BE]	= DD_BE_PRIO,
  	[IOPRIO_CLASS_IDLE]	= DD_IDLE_PRIO,

  };
  
  static inline struct rb_root *

  deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)

  {

  	return &per_prio->sort_list[rq_data_dir(rq)];
  }
  
  /*
   * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
   * request.
   */
  static u8 dd_rq_ioclass(struct request *rq)
  {
  	return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));

  }
  
  /*
   * get the request after `rq' in sector-sorted order
   */
  static inline struct request *
  deadline_latter_request(struct request *rq)
  {
  	struct rb_node *node = rb_next(&rq->rb_node);
  
  	if (node)
  		return rb_entry_rq(node);
  
  	return NULL;
  }
  
  static void

  deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)

  {

  	struct rb_root *root = deadline_rb_root(per_prio, rq);

  
  	elv_rb_add(root, rq);
  }
  
  static inline void

  deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)

  {

  	const enum dd_data_dir data_dir = rq_data_dir(rq);

  	if (per_prio->next_rq[data_dir] == rq)
  		per_prio->next_rq[data_dir] = deadline_latter_request(rq);

  	elv_rb_del(deadline_rb_root(per_prio, rq), rq);

  }
  
  /*
   * remove rq from rbtree and fifo.
   */

  static void deadline_remove_request(struct request_queue *q,
  				    struct dd_per_prio *per_prio,
  				    struct request *rq)

  {

  	list_del_init(&rq->queuelist);
  
  	/*
  	 * We might not be on the rbtree, if we are doing an insert merge
  	 */
  	if (!RB_EMPTY_NODE(&rq->rb_node))

  		deadline_del_rq_rb(per_prio, rq);

  
  	elv_rqhash_del(q, rq);
  	if (q->last_merge == rq)
  		q->last_merge = NULL;
  }
  
  static void dd_request_merged(struct request_queue *q, struct request *req,

  			      enum elv_merge type)

  {
  	struct deadline_data *dd = q->elevator->elevator_data;

  	const u8 ioprio_class = dd_rq_ioclass(req);
  	const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
  	struct dd_per_prio *per_prio = &dd->per_prio[prio];

  
  	/*
  	 * if the merge was a front merge, we need to reposition request
  	 */
  	if (type == ELEVATOR_FRONT_MERGE) {

  		elv_rb_del(deadline_rb_root(per_prio, req), req);
  		deadline_add_rq_rb(per_prio, req);

  	}
  }

  /*
   * Callback function that is invoked after @next has been merged into @req.
   */

  static void dd_merged_requests(struct request_queue *q, struct request *req,
  			       struct request *next)
  {

  	struct deadline_data *dd = q->elevator->elevator_data;

  	const u8 ioprio_class = dd_rq_ioclass(next);
  	const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];

  	dd_count(dd, merged, prio);

  	/*
  	 * if next expires before rq, assign its expire time to rq
  	 * and move into next position (next will be deleted) in fifo
  	 */
  	if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
  		if (time_before((unsigned long)next->fifo_time,
  				(unsigned long)req->fifo_time)) {
  			list_move(&req->queuelist, &next->queuelist);
  			req->fifo_time = next->fifo_time;
  		}
  	}
  
  	/*
  	 * kill knowledge of next, this one is a goner
  	 */

  	deadline_remove_request(q, &dd->per_prio[prio], next);

  }
  
  /*
   * move an entry to dispatch queue
   */
  static void

  deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
  		      struct request *rq)

  {

  	const enum dd_data_dir data_dir = rq_data_dir(rq);

  	per_prio->next_rq[data_dir] = deadline_latter_request(rq);

  
  	/*
  	 * take it off the sort and fifo list
  	 */

  	deadline_remove_request(rq->q, per_prio, rq);

  }
  
  /*
   * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
   * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
   */

  static inline int deadline_check_fifo(struct dd_per_prio *per_prio,

  				      enum dd_data_dir data_dir)

  {

  	struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);

  
  	/*
  	 * rq is expired!
  	 */
  	if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
  		return 1;
  
  	return 0;
  }
  
  /*

   * For the specified data direction, return the next request to
   * dispatch using arrival ordered lists.
   */
  static struct request *

  deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
  		      enum dd_data_dir data_dir)

  {

  	struct request *rq;
  	unsigned long flags;

  	if (list_empty(&per_prio->fifo_list[data_dir]))

  		return NULL;

  	rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);

  	if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))

  		return rq;
  
  	/*
  	 * Look for a write request that can be dispatched, that is one with
  	 * an unlocked target zone.
  	 */
  	spin_lock_irqsave(&dd->zone_lock, flags);

  	list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {

  		if (blk_req_can_dispatch_to_zone(rq))
  			goto out;
  	}
  	rq = NULL;
  out:
  	spin_unlock_irqrestore(&dd->zone_lock, flags);
  
  	return rq;

  }
  
  /*
   * For the specified data direction, return the next request to
   * dispatch using sector position sorted lists.
   */
  static struct request *

  deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
  		      enum dd_data_dir data_dir)

  {

  	struct request *rq;
  	unsigned long flags;

  	rq = per_prio->next_rq[data_dir];

  	if (!rq)
  		return NULL;

  	if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))

  		return rq;
  
  	/*
  	 * Look for a write request that can be dispatched, that is one with
  	 * an unlocked target zone.
  	 */
  	spin_lock_irqsave(&dd->zone_lock, flags);
  	while (rq) {
  		if (blk_req_can_dispatch_to_zone(rq))
  			break;
  		rq = deadline_latter_request(rq);
  	}
  	spin_unlock_irqrestore(&dd->zone_lock, flags);
  
  	return rq;

  }
  
  /*

   * deadline_dispatch_requests selects the best request according to

   * read/write expire, fifo_batch, etc

   */

  static struct request *__dd_dispatch_request(struct deadline_data *dd,

  					     struct dd_per_prio *per_prio)

  {

  	struct request *rq, *next_rq;

  	enum dd_data_dir data_dir;

  	enum dd_prio prio;
  	u8 ioprio_class;

  	lockdep_assert_held(&dd->lock);

  	if (!list_empty(&per_prio->dispatch)) {
  		rq = list_first_entry(&per_prio->dispatch, struct request,
  				      queuelist);

  		list_del_init(&rq->queuelist);
  		goto done;
  	}

  	/*
  	 * batches are currently reads XOR writes
  	 */

  	rq = deadline_next_request(dd, per_prio, dd->last_dir);

  	if (rq && dd->batching < dd->fifo_batch)
  		/* we have a next request are still entitled to batch */
  		goto dispatch_request;
  
  	/*
  	 * at this point we are not running a batch. select the appropriate
  	 * data direction (read / write)
  	 */

  	if (!list_empty(&per_prio->fifo_list[DD_READ])) {
  		BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));

  		if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&

  		    (dd->starved++ >= dd->writes_starved))

  			goto dispatch_writes;

  		data_dir = DD_READ;

  
  		goto dispatch_find_request;
  	}
  
  	/*
  	 * there are either no reads or writes have been starved
  	 */

  	if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {

  dispatch_writes:

  		BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));

  
  		dd->starved = 0;

  		data_dir = DD_WRITE;

  
  		goto dispatch_find_request;
  	}
  
  	return NULL;
  
  dispatch_find_request:
  	/*
  	 * we are not running a batch, find best request for selected data_dir
  	 */

  	next_rq = deadline_next_request(dd, per_prio, data_dir);
  	if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {

  		/*
  		 * A deadline has expired, the last request was in the other
  		 * direction, or we have run out of higher-sectored requests.
  		 * Start again from the request with the earliest expiry time.
  		 */

  		rq = deadline_fifo_request(dd, per_prio, data_dir);

  	} else {
  		/*
  		 * The last req was the same dir and we have a next request in
  		 * sort order. No expired requests so continue on from here.
  		 */

  		rq = next_rq;

  	}

  	/*
  	 * For a zoned block device, if we only have writes queued and none of
  	 * them can be dispatched, rq will be NULL.
  	 */
  	if (!rq)
  		return NULL;

  	dd->last_dir = data_dir;

  	dd->batching = 0;
  
  dispatch_request:
  	/*
  	 * rq is the selected appropriate request.
  	 */
  	dd->batching++;

  	deadline_move_request(dd, per_prio, rq);

  done:

  	ioprio_class = dd_rq_ioclass(rq);
  	prio = ioprio_class_to_prio[ioprio_class];
  	dd_count(dd, dispatched, prio);

  	/*
  	 * If the request needs its target zone locked, do it.
  	 */
  	blk_req_zone_write_lock(rq);

  	rq->rq_flags |= RQF_STARTED;
  	return rq;
  }

  /*

   * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
   *

   * One confusing aspect here is that we get called for a specific

   * hardware queue, but we may return a request that is for a

   * different hardware queue. This is because mq-deadline has shared
   * state for all hardware queues, in terms of sorting, FIFOs, etc.
   */

  static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)

  {
  	struct deadline_data *dd = hctx->queue->elevator->elevator_data;

  	struct request *rq;

  	enum dd_prio prio;

  
  	spin_lock(&dd->lock);

  	for (prio = 0; prio <= DD_PRIO_MAX; prio++) {

  		rq = __dd_dispatch_request(dd, &dd->per_prio[prio]);
  		if (rq)

  			break;
  	}

  	spin_unlock(&dd->lock);

  
  	return rq;

  }

  /*
   * Called by __blk_mq_alloc_request(). The shallow_depth value set by this
   * function is used by __blk_mq_get_tag().
   */
  static void dd_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
  {
  	struct deadline_data *dd = data->q->elevator->elevator_data;
  
  	/* Do not throttle synchronous reads. */
  	if (op_is_sync(op) && !op_is_write(op))
  		return;
  
  	/*
  	 * Throttle asynchronous requests and writes such that these requests
  	 * do not block the allocation of synchronous requests.
  	 */
  	data->shallow_depth = dd->async_depth;
  }
  
  /* Called by blk_mq_update_nr_requests(). */
  static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
  {
  	struct request_queue *q = hctx->queue;
  	struct deadline_data *dd = q->elevator->elevator_data;
  	struct blk_mq_tags *tags = hctx->sched_tags;
  
  	dd->async_depth = max(1UL, 3 * q->nr_requests / 4);
  
  	sbitmap_queue_min_shallow_depth(tags->bitmap_tags, dd->async_depth);
  }
  
  /* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
  static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
  {
  	dd_depth_updated(hctx);
  	return 0;
  }

  static void dd_exit_sched(struct elevator_queue *e)

  {
  	struct deadline_data *dd = e->elevator_data;

  	enum dd_prio prio;

  	for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
  		struct dd_per_prio *per_prio = &dd->per_prio[prio];
  
  		WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
  		WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
  	}

  	free_percpu(dd->stats);

  	kfree(dd);
  }
  
  /*

   * initialize elevator private data (deadline_data).

   */

  static int dd_init_sched(struct request_queue *q, struct elevator_type *e)

  {
  	struct deadline_data *dd;
  	struct elevator_queue *eq;

  	enum dd_prio prio;
  	int ret = -ENOMEM;

  
  	eq = elevator_alloc(q, e);
  	if (!eq)

  		return ret;

  
  	dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);

  	if (!dd)
  		goto put_eq;

  	eq->elevator_data = dd;

  	dd->stats = alloc_percpu_gfp(typeof(*dd->stats),
  				     GFP_KERNEL | __GFP_ZERO);
  	if (!dd->stats)
  		goto free_dd;

  	for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
  		struct dd_per_prio *per_prio = &dd->per_prio[prio];
  
  		INIT_LIST_HEAD(&per_prio->dispatch);
  		INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]);
  		INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]);
  		per_prio->sort_list[DD_READ] = RB_ROOT;
  		per_prio->sort_list[DD_WRITE] = RB_ROOT;
  	}

  	dd->fifo_expire[DD_READ] = read_expire;
  	dd->fifo_expire[DD_WRITE] = write_expire;

  	dd->writes_starved = writes_starved;
  	dd->front_merges = 1;

  	dd->last_dir = DD_WRITE;

  	dd->fifo_batch = fifo_batch;
  	spin_lock_init(&dd->lock);

  	spin_lock_init(&dd->zone_lock);

  
  	q->elevator = eq;
  	return 0;

  free_dd:
  	kfree(dd);

  put_eq:
  	kobject_put(&eq->kobj);
  	return ret;

  }

  /*
   * Try to merge @bio into an existing request. If @bio has been merged into
   * an existing request, store the pointer to that request into *@rq.
   */

  static int dd_request_merge(struct request_queue *q, struct request **rq,
  			    struct bio *bio)
  {
  	struct deadline_data *dd = q->elevator->elevator_data;

  	const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
  	const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
  	struct dd_per_prio *per_prio = &dd->per_prio[prio];

  	sector_t sector = bio_end_sector(bio);
  	struct request *__rq;
  
  	if (!dd->front_merges)
  		return ELEVATOR_NO_MERGE;

  	__rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector);

  	if (__rq) {
  		BUG_ON(sector != blk_rq_pos(__rq));
  
  		if (elv_bio_merge_ok(__rq, bio)) {
  			*rq = __rq;

  			if (blk_discard_mergable(__rq))
  				return ELEVATOR_DISCARD_MERGE;

  			return ELEVATOR_FRONT_MERGE;
  		}
  	}
  
  	return ELEVATOR_NO_MERGE;
  }

  /*
   * Attempt to merge a bio into an existing request. This function is called
   * before @bio is associated with a request.
   */

  static bool dd_bio_merge(struct request_queue *q, struct bio *bio,

  		unsigned int nr_segs)

  {

  	struct deadline_data *dd = q->elevator->elevator_data;

  	struct request *free = NULL;
  	bool ret;

  
  	spin_lock(&dd->lock);

  	ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);

  	spin_unlock(&dd->lock);

  	if (free)
  		blk_mq_free_request(free);

  	return ret;
  }
  
  /*
   * add rq to rbtree and fifo
   */
  static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
  			      bool at_head)
  {
  	struct request_queue *q = hctx->queue;
  	struct deadline_data *dd = q->elevator->elevator_data;

  	const enum dd_data_dir data_dir = rq_data_dir(rq);

  	u16 ioprio = req_get_ioprio(rq);
  	u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
  	struct dd_per_prio *per_prio;
  	enum dd_prio prio;

  	LIST_HEAD(free);

  	lockdep_assert_held(&dd->lock);

  	/*
  	 * This may be a requeue of a write request that has locked its
  	 * target zone. If it is the case, this releases the zone lock.
  	 */
  	blk_req_zone_write_unlock(rq);

  	prio = ioprio_class_to_prio[ioprio_class];

  	dd_count(dd, inserted, prio);

  	rq->elv.priv[0] = (void *)(uintptr_t)1;

  	if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
  		blk_mq_free_requests(&free);

  		return;

  	}

  	trace_block_rq_insert(rq);

  	per_prio = &dd->per_prio[prio];

  	if (at_head) {

  		list_add(&rq->queuelist, &per_prio->dispatch);

  	} else {

  		deadline_add_rq_rb(per_prio, rq);

  
  		if (rq_mergeable(rq)) {
  			elv_rqhash_add(q, rq);
  			if (!q->last_merge)
  				q->last_merge = rq;
  		}
  
  		/*
  		 * set expire time and add to fifo list
  		 */
  		rq->fifo_time = jiffies + dd->fifo_expire[data_dir];

  		list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);

  	}
  }

  /*
   * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests().
   */

  static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
  			       struct list_head *list, bool at_head)
  {
  	struct request_queue *q = hctx->queue;
  	struct deadline_data *dd = q->elevator->elevator_data;
  
  	spin_lock(&dd->lock);
  	while (!list_empty(list)) {
  		struct request *rq;
  
  		rq = list_first_entry(list, struct request, queuelist);
  		list_del_init(&rq->queuelist);
  		dd_insert_request(hctx, rq, at_head);
  	}
  	spin_unlock(&dd->lock);
  }

  /* Callback from inside blk_mq_rq_ctx_init(). */

  static void dd_prepare_request(struct request *rq)

  {

  	rq->elv.priv[0] = NULL;

  }
  
  /*

   * Callback from inside blk_mq_free_request().
   *

   * For zoned block devices, write unlock the target zone of
   * completed write requests. Do this while holding the zone lock
   * spinlock so that the zone is never unlocked while deadline_fifo_request()

   * or deadline_next_request() are executing. This function is called for
   * all requests, whether or not these requests complete successfully.

   *
   * For a zoned block device, __dd_dispatch_request() may have stopped
   * dispatching requests if all the queued requests are write requests directed
   * at zones that are already locked due to on-going write requests. To ensure
   * write request dispatch progress in this case, mark the queue as needing a
   * restart to ensure that the queue is run again after completion of the
   * request and zones being unlocked.

   */

  static void dd_finish_request(struct request *rq)

  {
  	struct request_queue *q = rq->q;

  	struct deadline_data *dd = q->elevator->elevator_data;
  	const u8 ioprio_class = dd_rq_ioclass(rq);
  	const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
  	struct dd_per_prio *per_prio = &dd->per_prio[prio];

  	/*
  	 * The block layer core may call dd_finish_request() without having
  	 * called dd_insert_requests(). Hence only update statistics for
  	 * requests for which dd_insert_requests() has been called. See also
  	 * blk_mq_request_bypass_insert().
  	 */
  	if (rq->elv.priv[0])
  		dd_count(dd, completed, prio);

  	if (blk_queue_is_zoned(q)) {

  		unsigned long flags;
  
  		spin_lock_irqsave(&dd->zone_lock, flags);
  		blk_req_zone_write_unlock(rq);

  		if (!list_empty(&per_prio->fifo_list[DD_WRITE]))

  			blk_mq_sched_mark_restart_hctx(rq->mq_hctx);

  		spin_unlock_irqrestore(&dd->zone_lock, flags);
  	}
  }

  static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
  {
  	return !list_empty_careful(&per_prio->dispatch) ||
  		!list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
  		!list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
  }

  static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
  {
  	struct deadline_data *dd = hctx->queue->elevator->elevator_data;

  	enum dd_prio prio;
  
  	for (prio = 0; prio <= DD_PRIO_MAX; prio++)
  		if (dd_has_work_for_prio(&dd->per_prio[prio]))
  			return true;

  	return false;

  }
  
  /*
   * sysfs parts below
   */

  #define SHOW_INT(__FUNC, __VAR)						\

  static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
  {									\
  	struct deadline_data *dd = e->elevator_data;			\

  									\
  	return sysfs_emit(page, "%d
  ", __VAR);				\

  }

  #define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
  SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
  SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
  SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
  SHOW_INT(deadline_front_merges_show, dd->front_merges);

  SHOW_INT(deadline_async_depth_show, dd->async_depth);

  SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
  #undef SHOW_INT
  #undef SHOW_JIFFIES

  
  #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
  static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)	\
  {									\
  	struct deadline_data *dd = e->elevator_data;			\

  	int __data, __ret;						\
  									\
  	__ret = kstrtoint(page, 0, &__data);				\
  	if (__ret < 0)							\
  		return __ret;						\

  	if (__data < (MIN))						\
  		__data = (MIN);						\
  	else if (__data > (MAX))					\
  		__data = (MAX);						\

  	*(__PTR) = __CONV(__data);					\

  	return count;							\

  }

  #define STORE_INT(__FUNC, __PTR, MIN, MAX)				\
  	STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
  #define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX)				\
  	STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
  STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
  STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
  STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
  STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);

  STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX);

  STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);

  #undef STORE_FUNCTION

  #undef STORE_INT
  #undef STORE_JIFFIES

  
  #define DD_ATTR(name) \

  	__ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)

  
  static struct elv_fs_entry deadline_attrs[] = {
  	DD_ATTR(read_expire),
  	DD_ATTR(write_expire),
  	DD_ATTR(writes_starved),
  	DD_ATTR(front_merges),

  	DD_ATTR(async_depth),

  	DD_ATTR(fifo_batch),
  	__ATTR_NULL
  };

  #ifdef CONFIG_BLK_DEBUG_FS

  #define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name)		\

  static void *deadline_##name##_fifo_start(struct seq_file *m,		\
  					  loff_t *pos)			\
  	__acquires(&dd->lock)						\
  {									\
  	struct request_queue *q = m->private;				\
  	struct deadline_data *dd = q->elevator->elevator_data;		\

  	struct dd_per_prio *per_prio = &dd->per_prio[prio];		\

  									\
  	spin_lock(&dd->lock);						\

  	return seq_list_start(&per_prio->fifo_list[data_dir], *pos);	\

  }									\
  									\
  static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,	\
  					 loff_t *pos)			\
  {									\
  	struct request_queue *q = m->private;				\
  	struct deadline_data *dd = q->elevator->elevator_data;		\

  	struct dd_per_prio *per_prio = &dd->per_prio[prio];		\

  									\

  	return seq_list_next(v, &per_prio->fifo_list[data_dir], pos);	\

  }									\
  									\
  static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)	\
  	__releases(&dd->lock)						\
  {									\
  	struct request_queue *q = m->private;				\
  	struct deadline_data *dd = q->elevator->elevator_data;		\
  									\
  	spin_unlock(&dd->lock);						\
  }									\
  									\
  static const struct seq_operations deadline_##name##_fifo_seq_ops = {	\
  	.start	= deadline_##name##_fifo_start,				\
  	.next	= deadline_##name##_fifo_next,				\
  	.stop	= deadline_##name##_fifo_stop,				\
  	.show	= blk_mq_debugfs_rq_show,				\
  };									\
  									\
  static int deadline_##name##_next_rq_show(void *data,			\
  					  struct seq_file *m)		\
  {									\
  	struct request_queue *q = data;					\
  	struct deadline_data *dd = q->elevator->elevator_data;		\

  	struct dd_per_prio *per_prio = &dd->per_prio[prio];		\
  	struct request *rq = per_prio->next_rq[data_dir];		\

  									\
  	if (rq)								\
  		__blk_mq_debugfs_rq_show(m, rq);			\
  	return 0;							\
  }

  
  DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
  DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
  DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
  DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
  DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
  DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);

  #undef DEADLINE_DEBUGFS_DDIR_ATTRS
  
  static int deadline_batching_show(void *data, struct seq_file *m)
  {
  	struct request_queue *q = data;
  	struct deadline_data *dd = q->elevator->elevator_data;
  
  	seq_printf(m, "%u
  ", dd->batching);
  	return 0;
  }
  
  static int deadline_starved_show(void *data, struct seq_file *m)
  {
  	struct request_queue *q = data;
  	struct deadline_data *dd = q->elevator->elevator_data;
  
  	seq_printf(m, "%u
  ", dd->starved);
  	return 0;
  }

  static int dd_async_depth_show(void *data, struct seq_file *m)
  {
  	struct request_queue *q = data;
  	struct deadline_data *dd = q->elevator->elevator_data;
  
  	seq_printf(m, "%u
  ", dd->async_depth);
  	return 0;
  }

  /* Number of requests queued for a given priority level. */
  static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
  {
  	return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
  }

  static int dd_queued_show(void *data, struct seq_file *m)
  {
  	struct request_queue *q = data;
  	struct deadline_data *dd = q->elevator->elevator_data;
  
  	seq_printf(m, "%u %u %u
  ", dd_queued(dd, DD_RT_PRIO),
  		   dd_queued(dd, DD_BE_PRIO),
  		   dd_queued(dd, DD_IDLE_PRIO));
  	return 0;
  }
  
  /* Number of requests owned by the block driver for a given priority. */
  static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
  {
  	return dd_sum(dd, dispatched, prio) + dd_sum(dd, merged, prio)
  		- dd_sum(dd, completed, prio);
  }
  
  static int dd_owned_by_driver_show(void *data, struct seq_file *m)
  {
  	struct request_queue *q = data;
  	struct deadline_data *dd = q->elevator->elevator_data;
  
  	seq_printf(m, "%u %u %u
  ", dd_owned_by_driver(dd, DD_RT_PRIO),
  		   dd_owned_by_driver(dd, DD_BE_PRIO),
  		   dd_owned_by_driver(dd, DD_IDLE_PRIO));
  	return 0;
  }

  #define DEADLINE_DISPATCH_ATTR(prio)					\
  static void *deadline_dispatch##prio##_start(struct seq_file *m,	\
  					     loff_t *pos)		\
  	__acquires(&dd->lock)						\
  {									\
  	struct request_queue *q = m->private;				\
  	struct deadline_data *dd = q->elevator->elevator_data;		\
  	struct dd_per_prio *per_prio = &dd->per_prio[prio];		\
  									\
  	spin_lock(&dd->lock);						\
  	return seq_list_start(&per_prio->dispatch, *pos);		\
  }									\
  									\
  static void *deadline_dispatch##prio##_next(struct seq_file *m,		\
  					    void *v, loff_t *pos)	\
  {									\
  	struct request_queue *q = m->private;				\
  	struct deadline_data *dd = q->elevator->elevator_data;		\
  	struct dd_per_prio *per_prio = &dd->per_prio[prio];		\
  									\
  	return seq_list_next(v, &per_prio->dispatch, pos);		\
  }									\
  									\
  static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v)	\
  	__releases(&dd->lock)						\
  {									\
  	struct request_queue *q = m->private;				\
  	struct deadline_data *dd = q->elevator->elevator_data;		\
  									\
  	spin_unlock(&dd->lock);						\
  }									\
  									\
  static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
  	.start	= deadline_dispatch##prio##_start,			\
  	.next	= deadline_dispatch##prio##_next,			\
  	.stop	= deadline_dispatch##prio##_stop,			\
  	.show	= blk_mq_debugfs_rq_show,				\

  }

  DEADLINE_DISPATCH_ATTR(0);
  DEADLINE_DISPATCH_ATTR(1);
  DEADLINE_DISPATCH_ATTR(2);
  #undef DEADLINE_DISPATCH_ATTR

  #define DEADLINE_QUEUE_DDIR_ATTRS(name)					\
  	{#name "_fifo_list", 0400,					\
  			.seq_ops = &deadline_##name##_fifo_seq_ops}
  #define DEADLINE_NEXT_RQ_ATTR(name)					\

  	{#name "_next_rq", 0400, deadline_##name##_next_rq_show}
  static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {

  	DEADLINE_QUEUE_DDIR_ATTRS(read0),
  	DEADLINE_QUEUE_DDIR_ATTRS(write0),
  	DEADLINE_QUEUE_DDIR_ATTRS(read1),
  	DEADLINE_QUEUE_DDIR_ATTRS(write1),
  	DEADLINE_QUEUE_DDIR_ATTRS(read2),
  	DEADLINE_QUEUE_DDIR_ATTRS(write2),
  	DEADLINE_NEXT_RQ_ATTR(read0),
  	DEADLINE_NEXT_RQ_ATTR(write0),
  	DEADLINE_NEXT_RQ_ATTR(read1),
  	DEADLINE_NEXT_RQ_ATTR(write1),
  	DEADLINE_NEXT_RQ_ATTR(read2),
  	DEADLINE_NEXT_RQ_ATTR(write2),

  	{"batching", 0400, deadline_batching_show},
  	{"starved", 0400, deadline_starved_show},

  	{"async_depth", 0400, dd_async_depth_show},

  	{"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
  	{"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
  	{"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},

  	{"owned_by_driver", 0400, dd_owned_by_driver_show},
  	{"queued", 0400, dd_queued_show},

  	{},
  };
  #undef DEADLINE_QUEUE_DDIR_ATTRS
  #endif

  static struct elevator_type mq_deadline = {

  	.ops = {

  		.depth_updated		= dd_depth_updated,
  		.limit_depth		= dd_limit_depth,

  		.insert_requests	= dd_insert_requests,

  		.dispatch_request	= dd_dispatch_request,

  		.prepare_request	= dd_prepare_request,
  		.finish_request		= dd_finish_request,

  		.next_request		= elv_rb_latter_request,
  		.former_request		= elv_rb_former_request,
  		.bio_merge		= dd_bio_merge,
  		.request_merge		= dd_request_merge,
  		.requests_merged	= dd_merged_requests,
  		.request_merged		= dd_request_merged,
  		.has_work		= dd_has_work,

  		.init_sched		= dd_init_sched,
  		.exit_sched		= dd_exit_sched,

  		.init_hctx		= dd_init_hctx,

  	},

  #ifdef CONFIG_BLK_DEBUG_FS
  	.queue_debugfs_attrs = deadline_queue_debugfs_attrs,
  #endif

  	.elevator_attrs = deadline_attrs,
  	.elevator_name = "mq-deadline",

  	.elevator_alias = "deadline",

  	.elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,

  	.elevator_owner = THIS_MODULE,
  };

  MODULE_ALIAS("mq-deadline-iosched");

  
  static int __init deadline_init(void)
  {

  	return elv_register(&mq_deadline);

  }
  
  static void __exit deadline_exit(void)
  {
  	elv_unregister(&mq_deadline);
  }
  
  module_init(deadline_init);
  module_exit(deadline_exit);

  MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");

  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("MQ deadline IO scheduler");