[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 *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)) {
			if (!attempt_back_merge(q, rq))
				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)) {
			if (!attempt_front_merge(q, rq))
				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
	237	bool blk_mq_sched_try_merge(struct request_queue q, struct bio bio)
	238	{
	239	struct request *rq;
	240	int ret;
	241
	242	ret = elv_merge(q, &rq, bio);
	243	if (ret == ELEVATOR_BACK_MERGE) {
	244	if (!blk_mq_sched_allow_merge(q, rq, bio))
	245	return false;
	246	if (bio_attempt_back_merge(q, rq, bio)) {
	247	if (!attempt_back_merge(q, rq))
	248	elv_merged_request(q, rq, ret);
	249	return true;
	250	}
	251	} else if (ret == ELEVATOR_FRONT_MERGE) {
	252	if (!blk_mq_sched_allow_merge(q, rq, bio))
	253	return false;
	254	if (bio_attempt_front_merge(q, rq, bio)) {
	255	if (!attempt_front_merge(q, rq))
	256	elv_merged_request(q, rq, ret);
	257	return true;
	258	}
	259	}
	260
	261	return false;
	262	}
	263	EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
	264
	265	bool __blk_mq_sched_bio_merge(struct request_queue q, struct bio bio)
	266	{
	267	struct elevator_queue *e = q->elevator;
	268
	269	if (e->type->ops.mq.bio_merge) {
	270	struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
	271	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	272
	273	blk_mq_put_ctx(ctx);
	274	return e->type->ops.mq.bio_merge(hctx, bio);
	275	}
	276
	277	return false;
	278	}
	279
	280	bool blk_mq_sched_try_insert_merge(struct request_queue q, struct request rq)
	281	{
	282	return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
283	}
284	EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
285
286	void blk_mq_sched_request_inserted(struct request *rq)
287	{
288	trace_block_rq_insert(rq->q, rq);
289	}
290	EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
291
0cacba6c OS	292	static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
0cacba6c OS	293	struct request *rq)
bd166ef1 JA	294	{
	295	if (rq->tag == -1) {
	296	rq->rq_flags \|= RQF_SORTED;
	297	return false;
	298	}
	299
	300	/*
	301	* If we already have a real request tag, send directly to
	302	* the dispatch list.
	303	*/
	304	spin_lock(&hctx->lock);
	305	list_add(&rq->queuelist, &hctx->dispatch);
	306	spin_unlock(&hctx->lock);
	307	return true;
	308	}
bd166ef1	309
50e1dab8 JA	310	static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
	311	{
	312	if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
	313	clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
	314	if (blk_mq_hctx_has_pending(hctx))
	315	blk_mq_run_hw_queue(hctx, true);
	316	}
	317	}
	318
	319	void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
	320	{
	321	unsigned int i;
	322
	323	if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
	324	blk_mq_sched_restart_hctx(hctx);
	325	else {
	326	struct request_queue *q = hctx->queue;
	327
	328	if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
	329	return;
	330
	331	clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
	332
	333	queue_for_each_hw_ctx(q, hctx, i)
	334	blk_mq_sched_restart_hctx(hctx);
	335	}
	336	}
	337
bd6737f1 JA	338	/*
	339	* Add flush/fua to the queue. If we fail getting a driver tag, then
	340	* punt to the requeue list. Requeue will re-invoke us from a context
	341	* that's safe to block from.
	342	*/
	343	static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
	344	struct request *rq, bool can_block)
	345	{
	346	if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
	347	blk_insert_flush(rq);
	348	blk_mq_run_hw_queue(hctx, true);
	349	} else
	350	blk_mq_add_to_requeue_list(rq, true, true);
	351	}
	352
	353	void blk_mq_sched_insert_request(struct request *rq, bool at_head,
	354	bool run_queue, bool async, bool can_block)
	355	{
	356	struct request_queue *q = rq->q;
	357	struct elevator_queue *e = q->elevator;
	358	struct blk_mq_ctx *ctx = rq->mq_ctx;
	359	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	360
f3a8ab7d	361	if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
bd6737f1 JA	362	blk_mq_sched_insert_flush(hctx, rq, can_block);
	363	return;
	364	}
	365
0cacba6c OS	366	if (e && blk_mq_sched_bypass_insert(hctx, rq))
	367	goto run;
	368
bd6737f1 JA	369	if (e && e->type->ops.mq.insert_requests) {
	370	LIST_HEAD(list);
	371
	372	list_add(&rq->queuelist, &list);
	373	e->type->ops.mq.insert_requests(hctx, &list, at_head);
	374	} else {
	375	spin_lock(&ctx->lock);
	376	__blk_mq_insert_request(hctx, rq, at_head);
	377	spin_unlock(&ctx->lock);
	378	}
	379
0cacba6c	380	run:
bd6737f1 JA	381	if (run_queue)
	382	blk_mq_run_hw_queue(hctx, async);
	383	}
	384
	385	void blk_mq_sched_insert_requests(struct request_queue *q,
	386	struct blk_mq_ctx *ctx,
	387	struct list_head *list, bool run_queue_async)
	388	{
	389	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
	390	struct elevator_queue *e = hctx->queue->elevator;
	391
0cacba6c OS	392	if (e) {
	393	struct request rq, next;
	394
	395	/*
	396	* We bypass requests that already have a driver tag assigned,
	397	* which should only be flushes. Flushes are only ever inserted
	398	* as single requests, so we shouldn't ever hit the
	399	* WARN_ON_ONCE() below (but let's handle it just in case).
	400	*/
	401	list_for_each_entry_safe(rq, next, list, queuelist) {
	402	if (WARN_ON_ONCE(rq->tag != -1)) {
	403	list_del_init(&rq->queuelist);
	404	blk_mq_sched_bypass_insert(hctx, rq);
	405	}
	406	}
	407	}
	408
bd6737f1 JA	409	if (e && e->type->ops.mq.insert_requests)
	410	e->type->ops.mq.insert_requests(hctx, list, false);
	411	else
	412	blk_mq_insert_requests(hctx, ctx, list);
	413
	414	blk_mq_run_hw_queue(hctx, run_queue_async);
	415	}
	416
bd166ef1 JA	417	static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
	418	struct blk_mq_hw_ctx *hctx,
	419	unsigned int hctx_idx)
	420	{
	421	if (hctx->sched_tags) {
	422	blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
	423	blk_mq_free_rq_map(hctx->sched_tags);
	424	hctx->sched_tags = NULL;
	425	}
	426	}
	427
	428	int blk_mq_sched_setup(struct request_queue *q)
	429	{
	430	struct blk_mq_tag_set *set = q->tag_set;
	431	struct blk_mq_hw_ctx *hctx;
	432	int ret, i;
	433
	434	/*
	435	* Default to 256, since we don't split into sync/async like the
	436	* old code did. Additionally, this is a per-hw queue depth.
	437	*/
	438	q->nr_requests = 2 * BLKDEV_MAX_RQ;
	439
	440	/*
	441	* We're switching to using an IO scheduler, so setup the hctx
	442	* scheduler tags and switch the request map from the regular
	443	* tags to scheduler tags. First allocate what we need, so we
	444	* can safely fail and fallback, if needed.
	445	*/
	446	ret = 0;
	447	queue_for_each_hw_ctx(q, hctx, i) {
	448	hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
	449	if (!hctx->sched_tags) {
	450	ret = -ENOMEM;
	451	break;
	452	}
	453	ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
	454	if (ret)
	455	break;
	456	}
	457
	458	/*
	459	* If we failed, free what we did allocate
	460	*/
	461	if (ret) {
	462	queue_for_each_hw_ctx(q, hctx, i) {
	463	if (!hctx->sched_tags)
	464	continue;
	465	blk_mq_sched_free_tags(set, hctx, i);
	466	}
	467
	468	return ret;
	469	}
	470
	471	return 0;
	472	}
	473
	474	void blk_mq_sched_teardown(struct request_queue *q)
	475	{
	476	struct blk_mq_tag_set *set = q->tag_set;
	477	struct blk_mq_hw_ctx *hctx;
	478	int i;
	479
	480	queue_for_each_hw_ctx(q, hctx, i)
481	blk_mq_sched_free_tags(set, hctx, i);
482	}
d3484991 JA	483
	484	int blk_mq_sched_init(struct request_queue *q)
	485	{
	486	int ret;
	487
	488	#if defined(CONFIG_DEFAULT_SQ_NONE)
	489	if (q->nr_hw_queues == 1)
	490	return 0;
	491	#endif
	492	#if defined(CONFIG_DEFAULT_MQ_NONE)
	493	if (q->nr_hw_queues > 1)
	494	return 0;
	495	#endif
	496
	497	mutex_lock(&q->sysfs_lock);
	498	ret = elevator_init(q, NULL);
	499	mutex_unlock(&q->sysfs_lock);
	500
	501	return ret;
	502	}