[mirror_ubuntu-bionic-kernel.git] / block / blk-mq-sched.c

/*
 * blk-mq scheduling framework
 *
 * Copyright (C) 2016 Jens Axboe
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/blk-mq.h>

#include <trace/events/block.h>

#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-sched.h"
#include "blk-mq-tag.h"
#include "blk-wbt.h"

void blk_mq_sched_free_hctx_data(struct request_queue *q,
				 void (*exit)(struct blk_mq_hw_ctx *))
{
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i) {
		if (exit && hctx->sched_data)
			exit(hctx);
		kfree(hctx->sched_data);
		hctx->sched_data = NULL;
	}
}
EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);

int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
				int (*init)(struct blk_mq_hw_ctx *),
				void (*exit)(struct blk_mq_hw_ctx *))
{
	struct blk_mq_hw_ctx *hctx;
	int ret;
	int i;

	queue_for_each_hw_ctx(q, hctx, i) {
		hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node);
		if (!hctx->sched_data) {
			ret = -ENOMEM;
			goto error;
		}

		if (init) {
			ret = init(hctx);
			if (ret) {
				/*
				 * We don't want to give exit() a partially
				 * initialized sched_data. init() must clean up
				 * if it fails.
				 */
				kfree(hctx->sched_data);
				hctx->sched_data = NULL;
				goto error;
			}
		}
	}

	return 0;
error:
	blk_mq_sched_free_hctx_data(q, exit);
	return ret;
}
EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data);

static void __blk_mq_sched_assign_ioc(struct request_queue *q,
				      struct request *rq, struct io_context *ioc)
{
	struct io_cq *icq;

	spin_lock_irq(q->queue_lock);
	icq = ioc_lookup_icq(ioc, q);
	spin_unlock_irq(q->queue_lock);

	if (!icq) {
		icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
		if (!icq)
			return;
	}

	rq->elv.icq = icq;
	if (!blk_mq_sched_get_rq_priv(q, rq)) {
		rq->rq_flags |= RQF_ELVPRIV;
		get_io_context(icq->ioc);
		return;
	}

	rq->elv.icq = NULL;
}

static void blk_mq_sched_assign_ioc(struct request_queue *q,
				    struct request *rq, struct bio *bio)
{
	struct io_context *ioc;

	ioc = rq_ioc(bio);
	if (ioc)
		__blk_mq_sched_assign_ioc(q, rq, ioc);
}

struct request *blk_mq_sched_get_request(struct request_queue *q,
					 struct bio *bio,
					 unsigned int op,
					 struct blk_mq_alloc_data *data)
{
	struct elevator_queue *e = q->elevator;
	struct blk_mq_hw_ctx *hctx;
	struct blk_mq_ctx *ctx;
	struct request *rq;

	blk_queue_enter_live(q);
	ctx = blk_mq_get_ctx(q);
	hctx = blk_mq_map_queue(q, ctx->cpu);

	blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);

	if (e) {
		data->flags |= BLK_MQ_REQ_INTERNAL;

		/*
		 * Flush requests are special and go directly to the
		 * dispatch list.
		 */
		if (!op_is_flush(op) && e->type->ops.mq.get_request) {
			rq = e->type->ops.mq.get_request(q, op, data);
			if (rq)
				rq->rq_flags |= RQF_QUEUED;
		} else
			rq = __blk_mq_alloc_request(data, op);
	} else {
		rq = __blk_mq_alloc_request(data, op);
		if (rq)
			data->hctx->tags->rqs[rq->tag] = rq;
	}

	if (rq) {
		if (!op_is_flush(op)) {
			rq->elv.icq = NULL;
			if (e && e->type->icq_cache)
				blk_mq_sched_assign_ioc(q, rq, bio);
		}
		data->hctx->queued++;
		return rq;
	}

	blk_queue_exit(q);
	return NULL;
}

void blk_mq_sched_put_request(struct request *rq)
{
	struct request_queue *q = rq->q;
	struct elevator_queue *e = q->elevator;

	if (rq->rq_flags & RQF_ELVPRIV) {
		blk_mq_sched_put_rq_priv(rq->q, rq);
		if (rq->elv.icq) {
			put_io_context(rq->elv.icq->ioc);
			rq->elv.icq = NULL;
		}
	}

	if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request)
		e->type->ops.mq.put_request(rq);
	else
		blk_mq_finish_request(rq);
}

void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
{
	struct elevator_queue *e = hctx->queue->elevator;
	LIST_HEAD(rq_list);

	if (unlikely(blk_mq_hctx_stopped(hctx)))
		return;

	hctx->run++;

	/*
	 * If we have previous entries on our dispatch list, grab them first for
	 * more fair dispatch.
	 */
	if (!list_empty_careful(&hctx->dispatch)) {
		spin_lock(&hctx->lock);
		if (!list_empty(&hctx->dispatch))
			list_splice_init(&hctx->dispatch, &rq_list);
		spin_unlock(&hctx->lock);
	}

	/*
	 * Only ask the scheduler for requests, if we didn't have residual
	 * requests from the dispatch list. This is to avoid the case where
	 * we only ever dispatch a fraction of the requests available because
	 * of low device queue depth. Once we pull requests out of the IO
	 * scheduler, we can no longer merge or sort them. So it's best to
	 * leave them there for as long as we can. Mark the hw queue as
	 * needing a restart in that case.
	 */
	if (!list_empty(&rq_list)) {
		blk_mq_sched_mark_restart(hctx);
		blk_mq_dispatch_rq_list(hctx, &rq_list);
	} else if (!e || !e->type->ops.mq.dispatch_request) {
		blk_mq_flush_busy_ctxs(hctx, &rq_list);
		blk_mq_dispatch_rq_list(hctx, &rq_list);
	} else {
		do {
			struct request *rq;

			rq = e->type->ops.mq.dispatch_request(hctx);
			if (!rq)
				break;
			list_add(&rq->queuelist, &rq_list);
		} while (blk_mq_dispatch_rq_list(hctx, &rq_list));
	}
}

void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
				   struct list_head *rq_list,
				   struct request *(*get_rq)(struct blk_mq_hw_ctx *))
{
	do {
		struct request *rq;

		rq = get_rq(hctx);
		if (!rq)
			break;

		list_add_tail(&rq->queuelist, rq_list);
	} while (1);
}
EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);

bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
			    struct request **merged_request)
{
	struct request *rq;
	int ret;

	ret = elv_merge(q, &rq, bio);
	if (ret == ELEVATOR_BACK_MERGE) {
		if (!blk_mq_sched_allow_merge(q, rq, bio))
			return false;
		if (bio_attempt_back_merge(q, rq, bio)) {
			*merged_request = attempt_back_merge(q, rq);
			if (!*merged_request)
				elv_merged_request(q, rq, ret);
			return true;
		}
	} else if (ret == ELEVATOR_FRONT_MERGE) {
		if (!blk_mq_sched_allow_merge(q, rq, bio))
			return false;
		if (bio_attempt_front_merge(q, rq, bio)) {
			*merged_request = attempt_front_merge(q, rq);
			if (!*merged_request)
				elv_merged_request(q, rq, ret);
			return true;
		}
	}

	return false;
}
EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);

bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
{
	struct elevator_queue *e = q->elevator;

	if (e->type->ops.mq.bio_merge) {
		struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
		struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);

		blk_mq_put_ctx(ctx);
		return e->type->ops.mq.bio_merge(hctx, bio);
	}

	return false;
}

bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
{
	return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
}
EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);

void blk_mq_sched_request_inserted(struct request *rq)
{
	trace_block_rq_insert(rq->q, rq);
}
EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);

static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
				       struct request *rq)
{
	if (rq->tag == -1) {
		rq->rq_flags |= RQF_SORTED;
		return false;
	}

	/*
	 * If we already have a real request tag, send directly to
	 * the dispatch list.
	 */
	spin_lock(&hctx->lock);
	list_add(&rq->queuelist, &hctx->dispatch);
	spin_unlock(&hctx->lock);
	return true;
}

static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
{
	if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
		clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
		if (blk_mq_hctx_has_pending(hctx))
			blk_mq_run_hw_queue(hctx, true);
	}
}

void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
{
	unsigned int i;

	if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
		blk_mq_sched_restart_hctx(hctx);
	else {
		struct request_queue *q = hctx->queue;

		if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
			return;

		clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags);

		queue_for_each_hw_ctx(q, hctx, i)
			blk_mq_sched_restart_hctx(hctx);
	}
}

/*
 * Add flush/fua to the queue. If we fail getting a driver tag, then
 * punt to the requeue list. Requeue will re-invoke us from a context
 * that's safe to block from.
 */
static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
				      struct request *rq, bool can_block)
{
	if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
		blk_insert_flush(rq);
		blk_mq_run_hw_queue(hctx, true);
	} else
		blk_mq_add_to_requeue_list(rq, true, true);
}

void blk_mq_sched_insert_request(struct request *rq, bool at_head,
				 bool run_queue, bool async, bool can_block)
{
	struct request_queue *q = rq->q;
	struct elevator_queue *e = q->elevator;
	struct blk_mq_ctx *ctx = rq->mq_ctx;
	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);

	if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
		blk_mq_sched_insert_flush(hctx, rq, can_block);
		return;
	}

	if (e && blk_mq_sched_bypass_insert(hctx, rq))
		goto run;

	if (e && e->type->ops.mq.insert_requests) {
		LIST_HEAD(list);

		list_add(&rq->queuelist, &list);
		e->type->ops.mq.insert_requests(hctx, &list, at_head);
	} else {
		spin_lock(&ctx->lock);
		__blk_mq_insert_request(hctx, rq, at_head);
		spin_unlock(&ctx->lock);
	}

run:
	if (run_queue)
		blk_mq_run_hw_queue(hctx, async);
}

void blk_mq_sched_insert_requests(struct request_queue *q,
				  struct blk_mq_ctx *ctx,
				  struct list_head *list, bool run_queue_async)
{
	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	struct elevator_queue *e = hctx->queue->elevator;

	if (e) {
		struct request *rq, *next;

		/*
		 * We bypass requests that already have a driver tag assigned,
		 * which should only be flushes. Flushes are only ever inserted
		 * as single requests, so we shouldn't ever hit the
		 * WARN_ON_ONCE() below (but let's handle it just in case).
		 */
		list_for_each_entry_safe(rq, next, list, queuelist) {
			if (WARN_ON_ONCE(rq->tag != -1)) {
				list_del_init(&rq->queuelist);
				blk_mq_sched_bypass_insert(hctx, rq);
			}
		}
	}

	if (e && e->type->ops.mq.insert_requests)
		e->type->ops.mq.insert_requests(hctx, list, false);
	else
		blk_mq_insert_requests(hctx, ctx, list);

	blk_mq_run_hw_queue(hctx, run_queue_async);
}

static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
				   struct blk_mq_hw_ctx *hctx,
				   unsigned int hctx_idx)
{
	if (hctx->sched_tags) {
		blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
		blk_mq_free_rq_map(hctx->sched_tags);
		hctx->sched_tags = NULL;
	}
}

int blk_mq_sched_setup(struct request_queue *q)
{
	struct blk_mq_tag_set *set = q->tag_set;
	struct blk_mq_hw_ctx *hctx;
	int ret, i;

	/*
	 * Default to 256, since we don't split into sync/async like the
	 * old code did. Additionally, this is a per-hw queue depth.
	 */
	q->nr_requests = 2 * BLKDEV_MAX_RQ;

	/*
	 * We're switching to using an IO scheduler, so setup the hctx
	 * scheduler tags and switch the request map from the regular
	 * tags to scheduler tags. First allocate what we need, so we
	 * can safely fail and fallback, if needed.
	 */
	ret = 0;
	queue_for_each_hw_ctx(q, hctx, i) {
		hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
		if (!hctx->sched_tags) {
			ret = -ENOMEM;
			break;
		}
		ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
		if (ret)
			break;
	}

	/*
	 * If we failed, free what we did allocate
	 */
	if (ret) {
		queue_for_each_hw_ctx(q, hctx, i) {
			if (!hctx->sched_tags)
				continue;
			blk_mq_sched_free_tags(set, hctx, i);
		}

		return ret;
	}

	return 0;
}

void blk_mq_sched_teardown(struct request_queue *q)
{
	struct blk_mq_tag_set *set = q->tag_set;
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i)
		blk_mq_sched_free_tags(set, hctx, i);
}

int blk_mq_sched_init(struct request_queue *q)
{
	int ret;

#if defined(CONFIG_DEFAULT_SQ_NONE)
	if (q->nr_hw_queues == 1)
		return 0;
#endif
#if defined(CONFIG_DEFAULT_MQ_NONE)
	if (q->nr_hw_queues > 1)
		return 0;
#endif

	mutex_lock(&q->sysfs_lock);
	ret = elevator_init(q, NULL);
	mutex_unlock(&q->sysfs_lock);

	return ret;
}
Commit	Line	Data
bd166ef1 JA	1	/*
	2	* blk-mq scheduling framework
	3	*
	4	* Copyright (C) 2016 Jens Axboe
	5	*/
	6	#include <linux/kernel.h>
	7	#include <linux/module.h>
	8	#include <linux/blk-mq.h>
	9
	10	#include <trace/events/block.h>
	11
	12	#include "blk.h"
	13	#include "blk-mq.h"
	14	#include "blk-mq-sched.h"
	15	#include "blk-mq-tag.h"
	16	#include "blk-wbt.h"
	17
	18	void blk_mq_sched_free_hctx_data(struct request_queue *q,
	19	void (exit)(struct blk_mq_hw_ctx ))
	20	{
	21	struct blk_mq_hw_ctx *hctx;
	22	int i;
	23
	24	queue_for_each_hw_ctx(q, hctx, i) {
	25	if (exit && hctx->sched_data)
	26	exit(hctx);
	27	kfree(hctx->sched_data);
	28	hctx->sched_data = NULL;
	29	}
	30	}
	31	EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
	32
	33	int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
	34	int (init)(struct blk_mq_hw_ctx ),
	35	void (exit)(struct blk_mq_hw_ctx ))
	36	{
	37	struct blk_mq_hw_ctx *hctx;
	38	int ret;
	39	int i;
	40
	41	queue_for_each_hw_ctx(q, hctx, i) {
	42	hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node);
	43	if (!hctx->sched_data) {
	44	ret = -ENOMEM;
	45	goto error;
	46	}
	47
	48	if (init) {
	49	ret = init(hctx);
	50	if (ret) {
	51	/*
	52	* We don't want to give exit() a partially
	53	* initialized sched_data. init() must clean up
	54	* if it fails.
	55	*/
	56	kfree(hctx->sched_data);
	57	hctx->sched_data = NULL;
	58	goto error;
	59	}
	60	}
	61	}
	62
	63	return 0;
	64	error:
65	blk_mq_sched_free_hctx_data(q, exit);
66	return ret;
67	}
68	EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data);
69
70	static void __blk_mq_sched_assign_ioc(struct request_queue *q,
71	struct request rq, struct io_context ioc)
72	{
73	struct io_cq *icq;
74
75	spin_lock_irq(q->queue_lock);
76	icq = ioc_lookup_icq(ioc, q);
77	spin_unlock_irq(q->queue_lock);
78
79	if (!icq) {
80	icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
81	if (!icq)
82	return;
83	}
84
85	rq->elv.icq = icq;
86	if (!blk_mq_sched_get_rq_priv(q, rq)) {
87	rq->rq_flags \|= RQF_ELVPRIV;
88	get_io_context(icq->ioc);
89	return;
90	}
91
92	rq->elv.icq = NULL;
93	}
94
95	static void blk_mq_sched_assign_ioc(struct request_queue *q,
96	struct request rq, struct bio bio)
97	{
98	struct io_context *ioc;
99
100	ioc = rq_ioc(bio);
101	if (ioc)
102	__blk_mq_sched_assign_ioc(q, rq, ioc);
103	}
104
105	struct request blk_mq_sched_get_request(struct request_queue q,
106	struct bio *bio,
107	unsigned int op,
108	struct blk_mq_alloc_data *data)
109	{
110	struct elevator_queue *e = q->elevator;
111	struct blk_mq_hw_ctx *hctx;
112	struct blk_mq_ctx *ctx;
113	struct request *rq;
bd166ef1 JA	114
	115	blk_queue_enter_live(q);
	116	ctx = blk_mq_get_ctx(q);
	117	hctx = blk_mq_map_queue(q, ctx->cpu);
	118
5a797e00	119	blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);
bd166ef1 JA	120
	121	if (e) {
	122	data->flags \|= BLK_MQ_REQ_INTERNAL;
	123
	124	/*
	125	* Flush requests are special and go directly to the
	126	* dispatch list.
	127	*/
f73f44eb	128	if (!op_is_flush(op) && e->type->ops.mq.get_request) {
bd166ef1 JA	129	rq = e->type->ops.mq.get_request(q, op, data);
	130	if (rq)
	131	rq->rq_flags \|= RQF_QUEUED;
	132	} else
	133	rq = __blk_mq_alloc_request(data, op);
	134	} else {
	135	rq = __blk_mq_alloc_request(data, op);
b48fda09 JA	136	if (rq)
b48fda09 JA	137	data->hctx->tags->rqs[rq->tag] = rq;
bd166ef1 JA	138	}
	139
	140	if (rq) {
f73f44eb	141	if (!op_is_flush(op)) {
bd166ef1 JA	142	rq->elv.icq = NULL;
	143	if (e && e->type->icq_cache)
	144	blk_mq_sched_assign_ioc(q, rq, bio);
	145	}
	146	data->hctx->queued++;
	147	return rq;
	148	}
	149
	150	blk_queue_exit(q);
	151	return NULL;
	152	}
	153
	154	void blk_mq_sched_put_request(struct request *rq)
	155	{
	156	struct request_queue *q = rq->q;
	157	struct elevator_queue *e = q->elevator;
	158
	159	if (rq->rq_flags & RQF_ELVPRIV) {
	160	blk_mq_sched_put_rq_priv(rq->q, rq);
	161	if (rq->elv.icq) {
	162	put_io_context(rq->elv.icq->ioc);
	163	rq->elv.icq = NULL;
	164	}
	165	}
	166
	167	if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request)
	168	e->type->ops.mq.put_request(rq);
	169	else
	170	blk_mq_finish_request(rq);
	171	}
	172
	173	void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
	174	{
	175	struct elevator_queue *e = hctx->queue->elevator;
	176	LIST_HEAD(rq_list);
	177
	178	if (unlikely(blk_mq_hctx_stopped(hctx)))
	179	return;
	180
	181	hctx->run++;
	182
	183	/*
	184	* If we have previous entries on our dispatch list, grab them first for
	185	* more fair dispatch.
	186	*/
	187	if (!list_empty_careful(&hctx->dispatch)) {
	188	spin_lock(&hctx->lock);
	189	if (!list_empty(&hctx->dispatch))
	190	list_splice_init(&hctx->dispatch, &rq_list);
	191	spin_unlock(&hctx->lock);
	192	}
	193
	194	/*
	195	* Only ask the scheduler for requests, if we didn't have residual
	196	* requests from the dispatch list. This is to avoid the case where
	197	* we only ever dispatch a fraction of the requests available because
	198	* of low device queue depth. Once we pull requests out of the IO
	199	* scheduler, we can no longer merge or sort them. So it's best to
	200	* leave them there for as long as we can. Mark the hw queue as
	201	* needing a restart in that case.
	202	*/
c13660a0	203	if (!list_empty(&rq_list)) {
bd166ef1	204	blk_mq_sched_mark_restart(hctx);
c13660a0 JA	205	blk_mq_dispatch_rq_list(hctx, &rq_list);
	206	} else if (!e \|\| !e->type->ops.mq.dispatch_request) {
	207	blk_mq_flush_busy_ctxs(hctx, &rq_list);
	208	blk_mq_dispatch_rq_list(hctx, &rq_list);
	209	} else {
	210	do {
	211	struct request *rq;
	212
	213	rq = e->type->ops.mq.dispatch_request(hctx);
	214	if (!rq)
	215	break;
	216	list_add(&rq->queuelist, &rq_list);
	217	} while (blk_mq_dispatch_rq_list(hctx, &rq_list));
	218	}
bd166ef1 JA	219	}
	220
	221	void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
	222	struct list_head *rq_list,
	223	struct request (get_rq)(struct blk_mq_hw_ctx *))
	224	{
	225	do {
	226	struct request *rq;
	227
	228	rq = get_rq(hctx);
	229	if (!rq)
	230	break;
	231
	232	list_add_tail(&rq->queuelist, rq_list);
	233	} while (1);
	234	}
	235	EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);
	236
e4d750c9 JA	237	bool blk_mq_sched_try_merge(struct request_queue q, struct bio bio,
e4d750c9 JA	238	struct request **merged_request)
bd166ef1 JA	239	{
	240	struct request *rq;
	241	int ret;
	242
	243	ret = elv_merge(q, &rq, bio);
	244	if (ret == ELEVATOR_BACK_MERGE) {
	245	if (!blk_mq_sched_allow_merge(q, rq, bio))
	246	return false;
	247	if (bio_attempt_back_merge(q, rq, bio)) {
e4d750c9 JA	248	*merged_request = attempt_back_merge(q, rq);
e4d750c9 JA	249	if (!*merged_request)
bd166ef1 JA	250	elv_merged_request(q, rq, ret);
	251	return true;
	252	}
	253	} else if (ret == ELEVATOR_FRONT_MERGE) {
	254	if (!blk_mq_sched_allow_merge(q, rq, bio))
	255	return false;
	256	if (bio_attempt_front_merge(q, rq, bio)) {
e4d750c9 JA	257	*merged_request = attempt_front_merge(q, rq);
e4d750c9 JA	258	if (!*merged_request)
bd166ef1 JA	259	elv_merged_request(q, rq, ret);
	260	return true;
	261	}
	262	}
	263
	264	return false;
	265	}
	266	EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
	267
	268	bool __blk_mq_sched_bio_merge(struct request_queue q, struct bio bio)
	269	{
	270	struct elevator_queue *e = q->elevator;
	271
	272	if (e->type->ops.mq.bio_merge) {
	273	struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
	274	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	275
	276	blk_mq_put_ctx(ctx);
	277	return e->type->ops.mq.bio_merge(hctx, bio);
	278	}
	279
	280	return false;
	281	}
	282
	283	bool blk_mq_sched_try_insert_merge(struct request_queue q, struct request rq)
	284	{
	285	return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
	286	}
	287	EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
	288
	289	void blk_mq_sched_request_inserted(struct request *rq)
	290	{
	291	trace_block_rq_insert(rq->q, rq);
	292	}
	293	EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
	294
0cacba6c OS	295	static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
0cacba6c OS	296	struct request *rq)
bd166ef1 JA	297	{
	298	if (rq->tag == -1) {
	299	rq->rq_flags \|= RQF_SORTED;
	300	return false;
	301	}
	302
	303	/*
	304	* If we already have a real request tag, send directly to
	305	* the dispatch list.
	306	*/
	307	spin_lock(&hctx->lock);
	308	list_add(&rq->queuelist, &hctx->dispatch);
	309	spin_unlock(&hctx->lock);
	310	return true;
	311	}
bd166ef1	312
50e1dab8 JA	313	static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
	314	{
	315	if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
	316	clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
	317	if (blk_mq_hctx_has_pending(hctx))
	318	blk_mq_run_hw_queue(hctx, true);
	319	}
	320	}
	321
	322	void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
	323	{
	324	unsigned int i;
	325
	326	if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
	327	blk_mq_sched_restart_hctx(hctx);
	328	else {
	329	struct request_queue *q = hctx->queue;
	330
	331	if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
	332	return;
	333
	334	clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
	335
	336	queue_for_each_hw_ctx(q, hctx, i)
	337	blk_mq_sched_restart_hctx(hctx);
	338	}
	339	}
	340
bd6737f1 JA	341	/*
	342	* Add flush/fua to the queue. If we fail getting a driver tag, then
	343	* punt to the requeue list. Requeue will re-invoke us from a context
	344	* that's safe to block from.
	345	*/
	346	static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
	347	struct request *rq, bool can_block)
	348	{
	349	if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
	350	blk_insert_flush(rq);
	351	blk_mq_run_hw_queue(hctx, true);
	352	} else
	353	blk_mq_add_to_requeue_list(rq, true, true);
	354	}
	355
	356	void blk_mq_sched_insert_request(struct request *rq, bool at_head,
	357	bool run_queue, bool async, bool can_block)
	358	{
	359	struct request_queue *q = rq->q;
	360	struct elevator_queue *e = q->elevator;
	361	struct blk_mq_ctx *ctx = rq->mq_ctx;
	362	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	363
f3a8ab7d	364	if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
bd6737f1 JA	365	blk_mq_sched_insert_flush(hctx, rq, can_block);
	366	return;
	367	}
	368
0cacba6c OS	369	if (e && blk_mq_sched_bypass_insert(hctx, rq))
	370	goto run;
	371
bd6737f1 JA	372	if (e && e->type->ops.mq.insert_requests) {
	373	LIST_HEAD(list);
	374
	375	list_add(&rq->queuelist, &list);
	376	e->type->ops.mq.insert_requests(hctx, &list, at_head);
	377	} else {
	378	spin_lock(&ctx->lock);
	379	__blk_mq_insert_request(hctx, rq, at_head);
	380	spin_unlock(&ctx->lock);
	381	}
	382
0cacba6c	383	run:
bd6737f1 JA	384	if (run_queue)
	385	blk_mq_run_hw_queue(hctx, async);
	386	}
	387
	388	void blk_mq_sched_insert_requests(struct request_queue *q,
	389	struct blk_mq_ctx *ctx,
	390	struct list_head *list, bool run_queue_async)
	391	{
	392	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	393	struct elevator_queue *e = hctx->queue->elevator;
	394
0cacba6c OS	395	if (e) {
	396	struct request rq, next;
	397
	398	/*
	399	* We bypass requests that already have a driver tag assigned,
	400	* which should only be flushes. Flushes are only ever inserted
	401	* as single requests, so we shouldn't ever hit the
	402	* WARN_ON_ONCE() below (but let's handle it just in case).
	403	*/
	404	list_for_each_entry_safe(rq, next, list, queuelist) {
	405	if (WARN_ON_ONCE(rq->tag != -1)) {
	406	list_del_init(&rq->queuelist);
	407	blk_mq_sched_bypass_insert(hctx, rq);
	408	}
	409	}
	410	}
	411
bd6737f1 JA	412	if (e && e->type->ops.mq.insert_requests)
	413	e->type->ops.mq.insert_requests(hctx, list, false);
	414	else
	415	blk_mq_insert_requests(hctx, ctx, list);
	416
	417	blk_mq_run_hw_queue(hctx, run_queue_async);
	418	}
	419
bd166ef1 JA	420	static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
	421	struct blk_mq_hw_ctx *hctx,
	422	unsigned int hctx_idx)
	423	{
	424	if (hctx->sched_tags) {
	425	blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
	426	blk_mq_free_rq_map(hctx->sched_tags);
	427	hctx->sched_tags = NULL;
	428	}
	429	}
	430
	431	int blk_mq_sched_setup(struct request_queue *q)
	432	{
	433	struct blk_mq_tag_set *set = q->tag_set;
	434	struct blk_mq_hw_ctx *hctx;
	435	int ret, i;
	436
	437	/*
	438	* Default to 256, since we don't split into sync/async like the
	439	* old code did. Additionally, this is a per-hw queue depth.
	440	*/
	441	q->nr_requests = 2 * BLKDEV_MAX_RQ;
	442
	443	/*
	444	* We're switching to using an IO scheduler, so setup the hctx
	445	* scheduler tags and switch the request map from the regular
	446	* tags to scheduler tags. First allocate what we need, so we
	447	* can safely fail and fallback, if needed.
	448	*/
	449	ret = 0;
	450	queue_for_each_hw_ctx(q, hctx, i) {
	451	hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
	452	if (!hctx->sched_tags) {
	453	ret = -ENOMEM;
	454	break;
	455	}
	456	ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
	457	if (ret)
	458	break;
	459	}
	460
	461	/*
	462	* If we failed, free what we did allocate
	463	*/
	464	if (ret) {
	465	queue_for_each_hw_ctx(q, hctx, i) {
	466	if (!hctx->sched_tags)
	467	continue;
	468	blk_mq_sched_free_tags(set, hctx, i);
	469	}
	470
	471	return ret;
	472	}
	473
	474	return 0;
	475	}
	476
	477	void blk_mq_sched_teardown(struct request_queue *q)
	478	{
	479	struct blk_mq_tag_set *set = q->tag_set;
	480	struct blk_mq_hw_ctx *hctx;
	481	int i;
	482
	483	queue_for_each_hw_ctx(q, hctx, i)
484	blk_mq_sched_free_tags(set, hctx, i);
485	}
d3484991 JA	486
	487	int blk_mq_sched_init(struct request_queue *q)
	488	{
	489	int ret;
	490
	491	#if defined(CONFIG_DEFAULT_SQ_NONE)
	492	if (q->nr_hw_queues == 1)
	493	return 0;
	494	#endif
	495	#if defined(CONFIG_DEFAULT_MQ_NONE)
	496	if (q->nr_hw_queues > 1)
	497	return 0;
	498	#endif
	499
	500	mutex_lock(&q->sysfs_lock);
	501	ret = elevator_init(q, NULL);
	502	mutex_unlock(&q->sysfs_lock);
	503
	504	return ret;
	505	}