1 // SPDX-License-Identifier: GPL-2.0
3 * Block multiqueue core code
5 * Copyright (C) 2013-2014 Jens Axboe
6 * Copyright (C) 2013-2014 Christoph Hellwig
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/backing-dev.h>
11 #include <linux/bio.h>
12 #include <linux/blkdev.h>
13 #include <linux/kmemleak.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/workqueue.h>
18 #include <linux/smp.h>
19 #include <linux/llist.h>
20 #include <linux/list_sort.h>
21 #include <linux/cpu.h>
22 #include <linux/cache.h>
23 #include <linux/sched/sysctl.h>
24 #include <linux/sched/topology.h>
25 #include <linux/sched/signal.h>
26 #include <linux/delay.h>
27 #include <linux/crash_dump.h>
28 #include <linux/prefetch.h>
30 #include <trace/events/block.h>
32 #include <linux/blk-mq.h>
35 #include "blk-mq-debugfs.h"
36 #include "blk-mq-tag.h"
39 #include "blk-mq-sched.h"
40 #include "blk-rq-qos.h"
42 static void blk_mq_poll_stats_start(struct request_queue *q);
43 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
45 static int blk_mq_poll_stats_bkt(const struct request *rq)
47 int ddir, bytes, bucket;
49 ddir = rq_data_dir(rq);
50 bytes = blk_rq_bytes(rq);
52 bucket = ddir + 2*(ilog2(bytes) - 9);
56 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
57 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
63 * Check if any of the ctx, dispatch list or elevator
64 * have pending work in this hardware queue.
66 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
68 return !list_empty_careful(&hctx->dispatch) ||
69 sbitmap_any_bit_set(&hctx->ctx_map) ||
70 blk_mq_sched_has_work(hctx);
74 * Mark this ctx as having pending work in this hardware queue
76 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
77 struct blk_mq_ctx *ctx)
79 const int bit = ctx->index_hw[hctx->type];
81 if (!sbitmap_test_bit(&hctx->ctx_map, bit))
82 sbitmap_set_bit(&hctx->ctx_map, bit);
85 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
86 struct blk_mq_ctx *ctx)
88 const int bit = ctx->index_hw[hctx->type];
90 sbitmap_clear_bit(&hctx->ctx_map, bit);
94 struct hd_struct *part;
95 unsigned int *inflight;
98 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
99 struct request *rq, void *priv,
102 struct mq_inflight *mi = priv;
105 * index[0] counts the specific partition that was asked for.
107 if (rq->part == mi->part)
113 unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part)
115 unsigned inflight[2];
116 struct mq_inflight mi = { .part = part, .inflight = inflight, };
118 inflight[0] = inflight[1] = 0;
119 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
124 static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
125 struct request *rq, void *priv,
128 struct mq_inflight *mi = priv;
130 if (rq->part == mi->part)
131 mi->inflight[rq_data_dir(rq)]++;
136 void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
137 unsigned int inflight[2])
139 struct mq_inflight mi = { .part = part, .inflight = inflight, };
141 inflight[0] = inflight[1] = 0;
142 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
145 void blk_freeze_queue_start(struct request_queue *q)
149 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
150 if (freeze_depth == 1) {
151 percpu_ref_kill(&q->q_usage_counter);
153 blk_mq_run_hw_queues(q, false);
156 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
158 void blk_mq_freeze_queue_wait(struct request_queue *q)
160 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
162 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
164 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
165 unsigned long timeout)
167 return wait_event_timeout(q->mq_freeze_wq,
168 percpu_ref_is_zero(&q->q_usage_counter),
171 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
174 * Guarantee no request is in use, so we can change any data structure of
175 * the queue afterward.
177 void blk_freeze_queue(struct request_queue *q)
180 * In the !blk_mq case we are only calling this to kill the
181 * q_usage_counter, otherwise this increases the freeze depth
182 * and waits for it to return to zero. For this reason there is
183 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
184 * exported to drivers as the only user for unfreeze is blk_mq.
186 blk_freeze_queue_start(q);
187 blk_mq_freeze_queue_wait(q);
190 void blk_mq_freeze_queue(struct request_queue *q)
193 * ...just an alias to keep freeze and unfreeze actions balanced
194 * in the blk_mq_* namespace
198 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
200 void blk_mq_unfreeze_queue(struct request_queue *q)
204 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
205 WARN_ON_ONCE(freeze_depth < 0);
207 percpu_ref_resurrect(&q->q_usage_counter);
208 wake_up_all(&q->mq_freeze_wq);
211 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
214 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
215 * mpt3sas driver such that this function can be removed.
217 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
219 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
221 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
224 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
227 * Note: this function does not prevent that the struct request end_io()
228 * callback function is invoked. Once this function is returned, we make
229 * sure no dispatch can happen until the queue is unquiesced via
230 * blk_mq_unquiesce_queue().
232 void blk_mq_quiesce_queue(struct request_queue *q)
234 struct blk_mq_hw_ctx *hctx;
238 blk_mq_quiesce_queue_nowait(q);
240 queue_for_each_hw_ctx(q, hctx, i) {
241 if (hctx->flags & BLK_MQ_F_BLOCKING)
242 synchronize_srcu(hctx->srcu);
249 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
252 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
255 * This function recovers queue into the state before quiescing
256 * which is done by blk_mq_quiesce_queue.
258 void blk_mq_unquiesce_queue(struct request_queue *q)
260 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
262 /* dispatch requests which are inserted during quiescing */
263 blk_mq_run_hw_queues(q, true);
265 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
267 void blk_mq_wake_waiters(struct request_queue *q)
269 struct blk_mq_hw_ctx *hctx;
272 queue_for_each_hw_ctx(q, hctx, i)
273 if (blk_mq_hw_queue_mapped(hctx))
274 blk_mq_tag_wakeup_all(hctx->tags, true);
277 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
279 return blk_mq_has_free_tags(hctx->tags);
281 EXPORT_SYMBOL(blk_mq_can_queue);
284 * Only need start/end time stamping if we have stats enabled, or using
287 static inline bool blk_mq_need_time_stamp(struct request *rq)
289 return (rq->rq_flags & RQF_IO_STAT) || rq->q->elevator;
292 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
293 unsigned int tag, unsigned int op)
295 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
296 struct request *rq = tags->static_rqs[tag];
297 req_flags_t rq_flags = 0;
299 if (data->flags & BLK_MQ_REQ_INTERNAL) {
301 rq->internal_tag = tag;
303 if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) {
304 rq_flags = RQF_MQ_INFLIGHT;
305 atomic_inc(&data->hctx->nr_active);
308 rq->internal_tag = -1;
309 data->hctx->tags->rqs[rq->tag] = rq;
312 /* csd/requeue_work/fifo_time is initialized before use */
314 rq->mq_ctx = data->ctx;
315 rq->mq_hctx = data->hctx;
316 rq->rq_flags = rq_flags;
318 if (data->flags & BLK_MQ_REQ_PREEMPT)
319 rq->rq_flags |= RQF_PREEMPT;
320 if (blk_queue_io_stat(data->q))
321 rq->rq_flags |= RQF_IO_STAT;
322 INIT_LIST_HEAD(&rq->queuelist);
323 INIT_HLIST_NODE(&rq->hash);
324 RB_CLEAR_NODE(&rq->rb_node);
327 if (blk_mq_need_time_stamp(rq))
328 rq->start_time_ns = ktime_get_ns();
330 rq->start_time_ns = 0;
331 rq->io_start_time_ns = 0;
332 rq->nr_phys_segments = 0;
333 #if defined(CONFIG_BLK_DEV_INTEGRITY)
334 rq->nr_integrity_segments = 0;
336 /* tag was already set */
338 WRITE_ONCE(rq->deadline, 0);
343 rq->end_io_data = NULL;
345 data->ctx->rq_dispatched[op_is_sync(op)]++;
346 refcount_set(&rq->ref, 1);
350 static struct request *blk_mq_get_request(struct request_queue *q,
352 struct blk_mq_alloc_data *data)
354 struct elevator_queue *e = q->elevator;
357 bool put_ctx_on_error = false;
359 blk_queue_enter_live(q);
361 if (likely(!data->ctx)) {
362 data->ctx = blk_mq_get_ctx(q);
363 put_ctx_on_error = true;
365 if (likely(!data->hctx))
366 data->hctx = blk_mq_map_queue(q, data->cmd_flags,
368 if (data->cmd_flags & REQ_NOWAIT)
369 data->flags |= BLK_MQ_REQ_NOWAIT;
372 data->flags |= BLK_MQ_REQ_INTERNAL;
375 * Flush requests are special and go directly to the
376 * dispatch list. Don't include reserved tags in the
377 * limiting, as it isn't useful.
379 if (!op_is_flush(data->cmd_flags) &&
380 e->type->ops.limit_depth &&
381 !(data->flags & BLK_MQ_REQ_RESERVED))
382 e->type->ops.limit_depth(data->cmd_flags, data);
384 blk_mq_tag_busy(data->hctx);
387 tag = blk_mq_get_tag(data);
388 if (tag == BLK_MQ_TAG_FAIL) {
389 if (put_ctx_on_error) {
390 blk_mq_put_ctx(data->ctx);
397 rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags);
398 if (!op_is_flush(data->cmd_flags)) {
400 if (e && e->type->ops.prepare_request) {
401 if (e->type->icq_cache)
402 blk_mq_sched_assign_ioc(rq);
404 e->type->ops.prepare_request(rq, bio);
405 rq->rq_flags |= RQF_ELVPRIV;
408 data->hctx->queued++;
412 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
413 blk_mq_req_flags_t flags)
415 struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
419 ret = blk_queue_enter(q, flags);
423 rq = blk_mq_get_request(q, NULL, &alloc_data);
427 return ERR_PTR(-EWOULDBLOCK);
429 blk_mq_put_ctx(alloc_data.ctx);
432 rq->__sector = (sector_t) -1;
433 rq->bio = rq->biotail = NULL;
436 EXPORT_SYMBOL(blk_mq_alloc_request);
438 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
439 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
441 struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
447 * If the tag allocator sleeps we could get an allocation for a
448 * different hardware context. No need to complicate the low level
449 * allocator for this for the rare use case of a command tied to
452 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
453 return ERR_PTR(-EINVAL);
455 if (hctx_idx >= q->nr_hw_queues)
456 return ERR_PTR(-EIO);
458 ret = blk_queue_enter(q, flags);
463 * Check if the hardware context is actually mapped to anything.
464 * If not tell the caller that it should skip this queue.
466 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
467 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
469 return ERR_PTR(-EXDEV);
471 cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
472 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
474 rq = blk_mq_get_request(q, NULL, &alloc_data);
478 return ERR_PTR(-EWOULDBLOCK);
482 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
484 static void __blk_mq_free_request(struct request *rq)
486 struct request_queue *q = rq->q;
487 struct blk_mq_ctx *ctx = rq->mq_ctx;
488 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
489 const int sched_tag = rq->internal_tag;
491 blk_pm_mark_last_busy(rq);
494 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
496 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
497 blk_mq_sched_restart(hctx);
501 void blk_mq_free_request(struct request *rq)
503 struct request_queue *q = rq->q;
504 struct elevator_queue *e = q->elevator;
505 struct blk_mq_ctx *ctx = rq->mq_ctx;
506 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
508 if (rq->rq_flags & RQF_ELVPRIV) {
509 if (e && e->type->ops.finish_request)
510 e->type->ops.finish_request(rq);
512 put_io_context(rq->elv.icq->ioc);
517 ctx->rq_completed[rq_is_sync(rq)]++;
518 if (rq->rq_flags & RQF_MQ_INFLIGHT)
519 atomic_dec(&hctx->nr_active);
521 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
522 laptop_io_completion(q->backing_dev_info);
526 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
527 if (refcount_dec_and_test(&rq->ref))
528 __blk_mq_free_request(rq);
530 EXPORT_SYMBOL_GPL(blk_mq_free_request);
532 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
536 if (blk_mq_need_time_stamp(rq))
537 now = ktime_get_ns();
539 if (rq->rq_flags & RQF_STATS) {
540 blk_mq_poll_stats_start(rq->q);
541 blk_stat_add(rq, now);
544 if (rq->internal_tag != -1)
545 blk_mq_sched_completed_request(rq, now);
547 blk_account_io_done(rq, now);
550 rq_qos_done(rq->q, rq);
551 rq->end_io(rq, error);
553 blk_mq_free_request(rq);
556 EXPORT_SYMBOL(__blk_mq_end_request);
558 void blk_mq_end_request(struct request *rq, blk_status_t error)
560 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
562 __blk_mq_end_request(rq, error);
564 EXPORT_SYMBOL(blk_mq_end_request);
566 static void __blk_mq_complete_request_remote(void *data)
568 struct request *rq = data;
569 struct request_queue *q = rq->q;
571 q->mq_ops->complete(rq);
574 static void __blk_mq_complete_request(struct request *rq)
576 struct blk_mq_ctx *ctx = rq->mq_ctx;
577 struct request_queue *q = rq->q;
581 WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
583 * Most of single queue controllers, there is only one irq vector
584 * for handling IO completion, and the only irq's affinity is set
585 * as all possible CPUs. On most of ARCHs, this affinity means the
586 * irq is handled on one specific CPU.
588 * So complete IO reqeust in softirq context in case of single queue
589 * for not degrading IO performance by irqsoff latency.
591 if (q->nr_hw_queues == 1) {
592 __blk_complete_request(rq);
597 * For a polled request, always complete locallly, it's pointless
598 * to redirect the completion.
600 if ((rq->cmd_flags & REQ_HIPRI) ||
601 !test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
602 q->mq_ops->complete(rq);
607 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
608 shared = cpus_share_cache(cpu, ctx->cpu);
610 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
611 rq->csd.func = __blk_mq_complete_request_remote;
614 smp_call_function_single_async(ctx->cpu, &rq->csd);
616 q->mq_ops->complete(rq);
621 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
622 __releases(hctx->srcu)
624 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
627 srcu_read_unlock(hctx->srcu, srcu_idx);
630 static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
631 __acquires(hctx->srcu)
633 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
634 /* shut up gcc false positive */
638 *srcu_idx = srcu_read_lock(hctx->srcu);
642 * blk_mq_complete_request - end I/O on a request
643 * @rq: the request being processed
646 * Ends all I/O on a request. It does not handle partial completions.
647 * The actual completion happens out-of-order, through a IPI handler.
649 bool blk_mq_complete_request(struct request *rq)
651 if (unlikely(blk_should_fake_timeout(rq->q)))
653 __blk_mq_complete_request(rq);
656 EXPORT_SYMBOL(blk_mq_complete_request);
658 void blk_mq_complete_request_sync(struct request *rq)
660 WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
661 rq->q->mq_ops->complete(rq);
663 EXPORT_SYMBOL_GPL(blk_mq_complete_request_sync);
665 int blk_mq_request_started(struct request *rq)
667 return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
669 EXPORT_SYMBOL_GPL(blk_mq_request_started);
671 void blk_mq_start_request(struct request *rq)
673 struct request_queue *q = rq->q;
675 blk_mq_sched_started_request(rq);
677 trace_block_rq_issue(q, rq);
679 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
680 rq->io_start_time_ns = ktime_get_ns();
681 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
682 rq->throtl_size = blk_rq_sectors(rq);
684 rq->rq_flags |= RQF_STATS;
688 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
691 WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
693 if (q->dma_drain_size && blk_rq_bytes(rq)) {
695 * Make sure space for the drain appears. We know we can do
696 * this because max_hw_segments has been adjusted to be one
697 * fewer than the device can handle.
699 rq->nr_phys_segments++;
702 EXPORT_SYMBOL(blk_mq_start_request);
704 static void __blk_mq_requeue_request(struct request *rq)
706 struct request_queue *q = rq->q;
708 blk_mq_put_driver_tag(rq);
710 trace_block_rq_requeue(q, rq);
711 rq_qos_requeue(q, rq);
713 if (blk_mq_request_started(rq)) {
714 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
715 rq->rq_flags &= ~RQF_TIMED_OUT;
716 if (q->dma_drain_size && blk_rq_bytes(rq))
717 rq->nr_phys_segments--;
721 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
723 __blk_mq_requeue_request(rq);
725 /* this request will be re-inserted to io scheduler queue */
726 blk_mq_sched_requeue_request(rq);
728 BUG_ON(!list_empty(&rq->queuelist));
729 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
731 EXPORT_SYMBOL(blk_mq_requeue_request);
733 static void blk_mq_requeue_work(struct work_struct *work)
735 struct request_queue *q =
736 container_of(work, struct request_queue, requeue_work.work);
738 struct request *rq, *next;
740 spin_lock_irq(&q->requeue_lock);
741 list_splice_init(&q->requeue_list, &rq_list);
742 spin_unlock_irq(&q->requeue_lock);
744 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
745 if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP)))
748 rq->rq_flags &= ~RQF_SOFTBARRIER;
749 list_del_init(&rq->queuelist);
751 * If RQF_DONTPREP, rq has contained some driver specific
752 * data, so insert it to hctx dispatch list to avoid any
755 if (rq->rq_flags & RQF_DONTPREP)
756 blk_mq_request_bypass_insert(rq, false);
758 blk_mq_sched_insert_request(rq, true, false, false);
761 while (!list_empty(&rq_list)) {
762 rq = list_entry(rq_list.next, struct request, queuelist);
763 list_del_init(&rq->queuelist);
764 blk_mq_sched_insert_request(rq, false, false, false);
767 blk_mq_run_hw_queues(q, false);
770 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
771 bool kick_requeue_list)
773 struct request_queue *q = rq->q;
777 * We abuse this flag that is otherwise used by the I/O scheduler to
778 * request head insertion from the workqueue.
780 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
782 spin_lock_irqsave(&q->requeue_lock, flags);
784 rq->rq_flags |= RQF_SOFTBARRIER;
785 list_add(&rq->queuelist, &q->requeue_list);
787 list_add_tail(&rq->queuelist, &q->requeue_list);
789 spin_unlock_irqrestore(&q->requeue_lock, flags);
791 if (kick_requeue_list)
792 blk_mq_kick_requeue_list(q);
795 void blk_mq_kick_requeue_list(struct request_queue *q)
797 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
799 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
801 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
804 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
805 msecs_to_jiffies(msecs));
807 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
809 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
811 if (tag < tags->nr_tags) {
812 prefetch(tags->rqs[tag]);
813 return tags->rqs[tag];
818 EXPORT_SYMBOL(blk_mq_tag_to_rq);
820 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq,
821 void *priv, bool reserved)
824 * If we find a request that is inflight and the queue matches,
825 * we know the queue is busy. Return false to stop the iteration.
827 if (rq->state == MQ_RQ_IN_FLIGHT && rq->q == hctx->queue) {
837 bool blk_mq_queue_inflight(struct request_queue *q)
841 blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
844 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
846 static void blk_mq_rq_timed_out(struct request *req, bool reserved)
848 req->rq_flags |= RQF_TIMED_OUT;
849 if (req->q->mq_ops->timeout) {
850 enum blk_eh_timer_return ret;
852 ret = req->q->mq_ops->timeout(req, reserved);
853 if (ret == BLK_EH_DONE)
855 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
861 static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
863 unsigned long deadline;
865 if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
867 if (rq->rq_flags & RQF_TIMED_OUT)
870 deadline = READ_ONCE(rq->deadline);
871 if (time_after_eq(jiffies, deadline))
876 else if (time_after(*next, deadline))
881 static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
882 struct request *rq, void *priv, bool reserved)
884 unsigned long *next = priv;
887 * Just do a quick check if it is expired before locking the request in
888 * so we're not unnecessarilly synchronizing across CPUs.
890 if (!blk_mq_req_expired(rq, next))
894 * We have reason to believe the request may be expired. Take a
895 * reference on the request to lock this request lifetime into its
896 * currently allocated context to prevent it from being reallocated in
897 * the event the completion by-passes this timeout handler.
899 * If the reference was already released, then the driver beat the
900 * timeout handler to posting a natural completion.
902 if (!refcount_inc_not_zero(&rq->ref))
906 * The request is now locked and cannot be reallocated underneath the
907 * timeout handler's processing. Re-verify this exact request is truly
908 * expired; if it is not expired, then the request was completed and
909 * reallocated as a new request.
911 if (blk_mq_req_expired(rq, next))
912 blk_mq_rq_timed_out(rq, reserved);
913 if (refcount_dec_and_test(&rq->ref))
914 __blk_mq_free_request(rq);
919 static void blk_mq_timeout_work(struct work_struct *work)
921 struct request_queue *q =
922 container_of(work, struct request_queue, timeout_work);
923 unsigned long next = 0;
924 struct blk_mq_hw_ctx *hctx;
927 /* A deadlock might occur if a request is stuck requiring a
928 * timeout at the same time a queue freeze is waiting
929 * completion, since the timeout code would not be able to
930 * acquire the queue reference here.
932 * That's why we don't use blk_queue_enter here; instead, we use
933 * percpu_ref_tryget directly, because we need to be able to
934 * obtain a reference even in the short window between the queue
935 * starting to freeze, by dropping the first reference in
936 * blk_freeze_queue_start, and the moment the last request is
937 * consumed, marked by the instant q_usage_counter reaches
940 if (!percpu_ref_tryget(&q->q_usage_counter))
943 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
946 mod_timer(&q->timeout, next);
949 * Request timeouts are handled as a forward rolling timer. If
950 * we end up here it means that no requests are pending and
951 * also that no request has been pending for a while. Mark
954 queue_for_each_hw_ctx(q, hctx, i) {
955 /* the hctx may be unmapped, so check it here */
956 if (blk_mq_hw_queue_mapped(hctx))
957 blk_mq_tag_idle(hctx);
963 struct flush_busy_ctx_data {
964 struct blk_mq_hw_ctx *hctx;
965 struct list_head *list;
968 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
970 struct flush_busy_ctx_data *flush_data = data;
971 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
972 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
973 enum hctx_type type = hctx->type;
975 spin_lock(&ctx->lock);
976 list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
977 sbitmap_clear_bit(sb, bitnr);
978 spin_unlock(&ctx->lock);
983 * Process software queues that have been marked busy, splicing them
984 * to the for-dispatch
986 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
988 struct flush_busy_ctx_data data = {
993 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
995 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
997 struct dispatch_rq_data {
998 struct blk_mq_hw_ctx *hctx;
1002 static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1005 struct dispatch_rq_data *dispatch_data = data;
1006 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1007 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1008 enum hctx_type type = hctx->type;
1010 spin_lock(&ctx->lock);
1011 if (!list_empty(&ctx->rq_lists[type])) {
1012 dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
1013 list_del_init(&dispatch_data->rq->queuelist);
1014 if (list_empty(&ctx->rq_lists[type]))
1015 sbitmap_clear_bit(sb, bitnr);
1017 spin_unlock(&ctx->lock);
1019 return !dispatch_data->rq;
1022 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1023 struct blk_mq_ctx *start)
1025 unsigned off = start ? start->index_hw[hctx->type] : 0;
1026 struct dispatch_rq_data data = {
1031 __sbitmap_for_each_set(&hctx->ctx_map, off,
1032 dispatch_rq_from_ctx, &data);
1037 static inline unsigned int queued_to_index(unsigned int queued)
1042 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1045 bool blk_mq_get_driver_tag(struct request *rq)
1047 struct blk_mq_alloc_data data = {
1049 .hctx = rq->mq_hctx,
1050 .flags = BLK_MQ_REQ_NOWAIT,
1051 .cmd_flags = rq->cmd_flags,
1058 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
1059 data.flags |= BLK_MQ_REQ_RESERVED;
1061 shared = blk_mq_tag_busy(data.hctx);
1062 rq->tag = blk_mq_get_tag(&data);
1065 rq->rq_flags |= RQF_MQ_INFLIGHT;
1066 atomic_inc(&data.hctx->nr_active);
1068 data.hctx->tags->rqs[rq->tag] = rq;
1072 return rq->tag != -1;
1075 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1076 int flags, void *key)
1078 struct blk_mq_hw_ctx *hctx;
1080 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1082 spin_lock(&hctx->dispatch_wait_lock);
1083 if (!list_empty(&wait->entry)) {
1084 struct sbitmap_queue *sbq;
1086 list_del_init(&wait->entry);
1087 sbq = &hctx->tags->bitmap_tags;
1088 atomic_dec(&sbq->ws_active);
1090 spin_unlock(&hctx->dispatch_wait_lock);
1092 blk_mq_run_hw_queue(hctx, true);
1097 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1098 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1099 * restart. For both cases, take care to check the condition again after
1100 * marking us as waiting.
1102 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
1105 struct sbitmap_queue *sbq = &hctx->tags->bitmap_tags;
1106 struct wait_queue_head *wq;
1107 wait_queue_entry_t *wait;
1110 if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) {
1111 blk_mq_sched_mark_restart_hctx(hctx);
1114 * It's possible that a tag was freed in the window between the
1115 * allocation failure and adding the hardware queue to the wait
1118 * Don't clear RESTART here, someone else could have set it.
1119 * At most this will cost an extra queue run.
1121 return blk_mq_get_driver_tag(rq);
1124 wait = &hctx->dispatch_wait;
1125 if (!list_empty_careful(&wait->entry))
1128 wq = &bt_wait_ptr(sbq, hctx)->wait;
1130 spin_lock_irq(&wq->lock);
1131 spin_lock(&hctx->dispatch_wait_lock);
1132 if (!list_empty(&wait->entry)) {
1133 spin_unlock(&hctx->dispatch_wait_lock);
1134 spin_unlock_irq(&wq->lock);
1138 atomic_inc(&sbq->ws_active);
1139 wait->flags &= ~WQ_FLAG_EXCLUSIVE;
1140 __add_wait_queue(wq, wait);
1143 * It's possible that a tag was freed in the window between the
1144 * allocation failure and adding the hardware queue to the wait
1147 ret = blk_mq_get_driver_tag(rq);
1149 spin_unlock(&hctx->dispatch_wait_lock);
1150 spin_unlock_irq(&wq->lock);
1155 * We got a tag, remove ourselves from the wait queue to ensure
1156 * someone else gets the wakeup.
1158 list_del_init(&wait->entry);
1159 atomic_dec(&sbq->ws_active);
1160 spin_unlock(&hctx->dispatch_wait_lock);
1161 spin_unlock_irq(&wq->lock);
1166 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1167 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1169 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1170 * - EWMA is one simple way to compute running average value
1171 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1172 * - take 4 as factor for avoiding to get too small(0) result, and this
1173 * factor doesn't matter because EWMA decreases exponentially
1175 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
1179 if (hctx->queue->elevator)
1182 ewma = hctx->dispatch_busy;
1187 ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
1189 ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
1190 ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
1192 hctx->dispatch_busy = ewma;
1195 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1198 * Returns true if we did some work AND can potentially do more.
1200 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
1203 struct blk_mq_hw_ctx *hctx;
1204 struct request *rq, *nxt;
1205 bool no_tag = false;
1207 blk_status_t ret = BLK_STS_OK;
1209 if (list_empty(list))
1212 WARN_ON(!list_is_singular(list) && got_budget);
1215 * Now process all the entries, sending them to the driver.
1217 errors = queued = 0;
1219 struct blk_mq_queue_data bd;
1221 rq = list_first_entry(list, struct request, queuelist);
1224 if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
1227 if (!blk_mq_get_driver_tag(rq)) {
1229 * The initial allocation attempt failed, so we need to
1230 * rerun the hardware queue when a tag is freed. The
1231 * waitqueue takes care of that. If the queue is run
1232 * before we add this entry back on the dispatch list,
1233 * we'll re-run it below.
1235 if (!blk_mq_mark_tag_wait(hctx, rq)) {
1236 blk_mq_put_dispatch_budget(hctx);
1238 * For non-shared tags, the RESTART check
1241 if (hctx->flags & BLK_MQ_F_TAG_SHARED)
1247 list_del_init(&rq->queuelist);
1252 * Flag last if we have no more requests, or if we have more
1253 * but can't assign a driver tag to it.
1255 if (list_empty(list))
1258 nxt = list_first_entry(list, struct request, queuelist);
1259 bd.last = !blk_mq_get_driver_tag(nxt);
1262 ret = q->mq_ops->queue_rq(hctx, &bd);
1263 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
1265 * If an I/O scheduler has been configured and we got a
1266 * driver tag for the next request already, free it
1269 if (!list_empty(list)) {
1270 nxt = list_first_entry(list, struct request, queuelist);
1271 blk_mq_put_driver_tag(nxt);
1273 list_add(&rq->queuelist, list);
1274 __blk_mq_requeue_request(rq);
1278 if (unlikely(ret != BLK_STS_OK)) {
1280 blk_mq_end_request(rq, BLK_STS_IOERR);
1285 } while (!list_empty(list));
1287 hctx->dispatched[queued_to_index(queued)]++;
1290 * Any items that need requeuing? Stuff them into hctx->dispatch,
1291 * that is where we will continue on next queue run.
1293 if (!list_empty(list)) {
1297 * If we didn't flush the entire list, we could have told
1298 * the driver there was more coming, but that turned out to
1301 if (q->mq_ops->commit_rqs)
1302 q->mq_ops->commit_rqs(hctx);
1304 spin_lock(&hctx->lock);
1305 list_splice_init(list, &hctx->dispatch);
1306 spin_unlock(&hctx->lock);
1309 * If SCHED_RESTART was set by the caller of this function and
1310 * it is no longer set that means that it was cleared by another
1311 * thread and hence that a queue rerun is needed.
1313 * If 'no_tag' is set, that means that we failed getting
1314 * a driver tag with an I/O scheduler attached. If our dispatch
1315 * waitqueue is no longer active, ensure that we run the queue
1316 * AFTER adding our entries back to the list.
1318 * If no I/O scheduler has been configured it is possible that
1319 * the hardware queue got stopped and restarted before requests
1320 * were pushed back onto the dispatch list. Rerun the queue to
1321 * avoid starvation. Notes:
1322 * - blk_mq_run_hw_queue() checks whether or not a queue has
1323 * been stopped before rerunning a queue.
1324 * - Some but not all block drivers stop a queue before
1325 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1328 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1329 * bit is set, run queue after a delay to avoid IO stalls
1330 * that could otherwise occur if the queue is idle.
1332 needs_restart = blk_mq_sched_needs_restart(hctx);
1333 if (!needs_restart ||
1334 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1335 blk_mq_run_hw_queue(hctx, true);
1336 else if (needs_restart && (ret == BLK_STS_RESOURCE))
1337 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1339 blk_mq_update_dispatch_busy(hctx, true);
1342 blk_mq_update_dispatch_busy(hctx, false);
1345 * If the host/device is unable to accept more work, inform the
1348 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1351 return (queued + errors) != 0;
1354 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1359 * We should be running this queue from one of the CPUs that
1362 * There are at least two related races now between setting
1363 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1364 * __blk_mq_run_hw_queue():
1366 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1367 * but later it becomes online, then this warning is harmless
1370 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1371 * but later it becomes offline, then the warning can't be
1372 * triggered, and we depend on blk-mq timeout handler to
1373 * handle dispatched requests to this hctx
1375 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1376 cpu_online(hctx->next_cpu)) {
1377 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1378 raw_smp_processor_id(),
1379 cpumask_empty(hctx->cpumask) ? "inactive": "active");
1384 * We can't run the queue inline with ints disabled. Ensure that
1385 * we catch bad users of this early.
1387 WARN_ON_ONCE(in_interrupt());
1389 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1391 hctx_lock(hctx, &srcu_idx);
1392 blk_mq_sched_dispatch_requests(hctx);
1393 hctx_unlock(hctx, srcu_idx);
1396 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1398 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1400 if (cpu >= nr_cpu_ids)
1401 cpu = cpumask_first(hctx->cpumask);
1406 * It'd be great if the workqueue API had a way to pass
1407 * in a mask and had some smarts for more clever placement.
1408 * For now we just round-robin here, switching for every
1409 * BLK_MQ_CPU_WORK_BATCH queued items.
1411 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1414 int next_cpu = hctx->next_cpu;
1416 if (hctx->queue->nr_hw_queues == 1)
1417 return WORK_CPU_UNBOUND;
1419 if (--hctx->next_cpu_batch <= 0) {
1421 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1423 if (next_cpu >= nr_cpu_ids)
1424 next_cpu = blk_mq_first_mapped_cpu(hctx);
1425 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1429 * Do unbound schedule if we can't find a online CPU for this hctx,
1430 * and it should only happen in the path of handling CPU DEAD.
1432 if (!cpu_online(next_cpu)) {
1439 * Make sure to re-select CPU next time once after CPUs
1440 * in hctx->cpumask become online again.
1442 hctx->next_cpu = next_cpu;
1443 hctx->next_cpu_batch = 1;
1444 return WORK_CPU_UNBOUND;
1447 hctx->next_cpu = next_cpu;
1451 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1452 unsigned long msecs)
1454 if (unlikely(blk_mq_hctx_stopped(hctx)))
1457 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1458 int cpu = get_cpu();
1459 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1460 __blk_mq_run_hw_queue(hctx);
1468 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1469 msecs_to_jiffies(msecs));
1472 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1474 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1476 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1478 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1484 * When queue is quiesced, we may be switching io scheduler, or
1485 * updating nr_hw_queues, or other things, and we can't run queue
1486 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1488 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1491 hctx_lock(hctx, &srcu_idx);
1492 need_run = !blk_queue_quiesced(hctx->queue) &&
1493 blk_mq_hctx_has_pending(hctx);
1494 hctx_unlock(hctx, srcu_idx);
1497 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1503 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1505 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1507 struct blk_mq_hw_ctx *hctx;
1510 queue_for_each_hw_ctx(q, hctx, i) {
1511 if (blk_mq_hctx_stopped(hctx))
1514 blk_mq_run_hw_queue(hctx, async);
1517 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1520 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1521 * @q: request queue.
1523 * The caller is responsible for serializing this function against
1524 * blk_mq_{start,stop}_hw_queue().
1526 bool blk_mq_queue_stopped(struct request_queue *q)
1528 struct blk_mq_hw_ctx *hctx;
1531 queue_for_each_hw_ctx(q, hctx, i)
1532 if (blk_mq_hctx_stopped(hctx))
1537 EXPORT_SYMBOL(blk_mq_queue_stopped);
1540 * This function is often used for pausing .queue_rq() by driver when
1541 * there isn't enough resource or some conditions aren't satisfied, and
1542 * BLK_STS_RESOURCE is usually returned.
1544 * We do not guarantee that dispatch can be drained or blocked
1545 * after blk_mq_stop_hw_queue() returns. Please use
1546 * blk_mq_quiesce_queue() for that requirement.
1548 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1550 cancel_delayed_work(&hctx->run_work);
1552 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1554 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1557 * This function is often used for pausing .queue_rq() by driver when
1558 * there isn't enough resource or some conditions aren't satisfied, and
1559 * BLK_STS_RESOURCE is usually returned.
1561 * We do not guarantee that dispatch can be drained or blocked
1562 * after blk_mq_stop_hw_queues() returns. Please use
1563 * blk_mq_quiesce_queue() for that requirement.
1565 void blk_mq_stop_hw_queues(struct request_queue *q)
1567 struct blk_mq_hw_ctx *hctx;
1570 queue_for_each_hw_ctx(q, hctx, i)
1571 blk_mq_stop_hw_queue(hctx);
1573 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1575 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1577 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1579 blk_mq_run_hw_queue(hctx, false);
1581 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1583 void blk_mq_start_hw_queues(struct request_queue *q)
1585 struct blk_mq_hw_ctx *hctx;
1588 queue_for_each_hw_ctx(q, hctx, i)
1589 blk_mq_start_hw_queue(hctx);
1591 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1593 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1595 if (!blk_mq_hctx_stopped(hctx))
1598 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1599 blk_mq_run_hw_queue(hctx, async);
1601 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1603 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1605 struct blk_mq_hw_ctx *hctx;
1608 queue_for_each_hw_ctx(q, hctx, i)
1609 blk_mq_start_stopped_hw_queue(hctx, async);
1611 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1613 static void blk_mq_run_work_fn(struct work_struct *work)
1615 struct blk_mq_hw_ctx *hctx;
1617 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1620 * If we are stopped, don't run the queue.
1622 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1625 __blk_mq_run_hw_queue(hctx);
1628 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1632 struct blk_mq_ctx *ctx = rq->mq_ctx;
1633 enum hctx_type type = hctx->type;
1635 lockdep_assert_held(&ctx->lock);
1637 trace_block_rq_insert(hctx->queue, rq);
1640 list_add(&rq->queuelist, &ctx->rq_lists[type]);
1642 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
1645 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1648 struct blk_mq_ctx *ctx = rq->mq_ctx;
1650 lockdep_assert_held(&ctx->lock);
1652 __blk_mq_insert_req_list(hctx, rq, at_head);
1653 blk_mq_hctx_mark_pending(hctx, ctx);
1657 * Should only be used carefully, when the caller knows we want to
1658 * bypass a potential IO scheduler on the target device.
1660 void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
1662 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1664 spin_lock(&hctx->lock);
1665 list_add_tail(&rq->queuelist, &hctx->dispatch);
1666 spin_unlock(&hctx->lock);
1669 blk_mq_run_hw_queue(hctx, false);
1672 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1673 struct list_head *list)
1677 enum hctx_type type = hctx->type;
1680 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1683 list_for_each_entry(rq, list, queuelist) {
1684 BUG_ON(rq->mq_ctx != ctx);
1685 trace_block_rq_insert(hctx->queue, rq);
1688 spin_lock(&ctx->lock);
1689 list_splice_tail_init(list, &ctx->rq_lists[type]);
1690 blk_mq_hctx_mark_pending(hctx, ctx);
1691 spin_unlock(&ctx->lock);
1694 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
1696 struct request *rqa = container_of(a, struct request, queuelist);
1697 struct request *rqb = container_of(b, struct request, queuelist);
1699 if (rqa->mq_ctx < rqb->mq_ctx)
1701 else if (rqa->mq_ctx > rqb->mq_ctx)
1703 else if (rqa->mq_hctx < rqb->mq_hctx)
1705 else if (rqa->mq_hctx > rqb->mq_hctx)
1708 return blk_rq_pos(rqa) > blk_rq_pos(rqb);
1711 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1713 struct blk_mq_hw_ctx *this_hctx;
1714 struct blk_mq_ctx *this_ctx;
1715 struct request_queue *this_q;
1721 list_splice_init(&plug->mq_list, &list);
1723 if (plug->rq_count > 2 && plug->multiple_queues)
1724 list_sort(NULL, &list, plug_rq_cmp);
1733 while (!list_empty(&list)) {
1734 rq = list_entry_rq(list.next);
1735 list_del_init(&rq->queuelist);
1737 if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx) {
1739 trace_block_unplug(this_q, depth, !from_schedule);
1740 blk_mq_sched_insert_requests(this_hctx, this_ctx,
1746 this_ctx = rq->mq_ctx;
1747 this_hctx = rq->mq_hctx;
1752 list_add_tail(&rq->queuelist, &rq_list);
1756 * If 'this_hctx' is set, we know we have entries to complete
1757 * on 'rq_list'. Do those.
1760 trace_block_unplug(this_q, depth, !from_schedule);
1761 blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
1766 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1768 blk_init_request_from_bio(rq, bio);
1770 blk_account_io_start(rq, true);
1773 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1775 blk_qc_t *cookie, bool last)
1777 struct request_queue *q = rq->q;
1778 struct blk_mq_queue_data bd = {
1782 blk_qc_t new_cookie;
1785 new_cookie = request_to_qc_t(hctx, rq);
1788 * For OK queue, we are done. For error, caller may kill it.
1789 * Any other error (busy), just add it to our list as we
1790 * previously would have done.
1792 ret = q->mq_ops->queue_rq(hctx, &bd);
1795 blk_mq_update_dispatch_busy(hctx, false);
1796 *cookie = new_cookie;
1798 case BLK_STS_RESOURCE:
1799 case BLK_STS_DEV_RESOURCE:
1800 blk_mq_update_dispatch_busy(hctx, true);
1801 __blk_mq_requeue_request(rq);
1804 blk_mq_update_dispatch_busy(hctx, false);
1805 *cookie = BLK_QC_T_NONE;
1812 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1815 bool bypass_insert, bool last)
1817 struct request_queue *q = rq->q;
1818 bool run_queue = true;
1821 * RCU or SRCU read lock is needed before checking quiesced flag.
1823 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1824 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1825 * and avoid driver to try to dispatch again.
1827 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1829 bypass_insert = false;
1833 if (q->elevator && !bypass_insert)
1836 if (!blk_mq_get_dispatch_budget(hctx))
1839 if (!blk_mq_get_driver_tag(rq)) {
1840 blk_mq_put_dispatch_budget(hctx);
1844 return __blk_mq_issue_directly(hctx, rq, cookie, last);
1847 return BLK_STS_RESOURCE;
1849 blk_mq_request_bypass_insert(rq, run_queue);
1853 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1854 struct request *rq, blk_qc_t *cookie)
1859 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1861 hctx_lock(hctx, &srcu_idx);
1863 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
1864 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1865 blk_mq_request_bypass_insert(rq, true);
1866 else if (ret != BLK_STS_OK)
1867 blk_mq_end_request(rq, ret);
1869 hctx_unlock(hctx, srcu_idx);
1872 blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
1876 blk_qc_t unused_cookie;
1877 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1879 hctx_lock(hctx, &srcu_idx);
1880 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
1881 hctx_unlock(hctx, srcu_idx);
1886 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
1887 struct list_head *list)
1889 while (!list_empty(list)) {
1891 struct request *rq = list_first_entry(list, struct request,
1894 list_del_init(&rq->queuelist);
1895 ret = blk_mq_request_issue_directly(rq, list_empty(list));
1896 if (ret != BLK_STS_OK) {
1897 if (ret == BLK_STS_RESOURCE ||
1898 ret == BLK_STS_DEV_RESOURCE) {
1899 blk_mq_request_bypass_insert(rq,
1903 blk_mq_end_request(rq, ret);
1908 * If we didn't flush the entire list, we could have told
1909 * the driver there was more coming, but that turned out to
1912 if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs)
1913 hctx->queue->mq_ops->commit_rqs(hctx);
1916 static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
1918 list_add_tail(&rq->queuelist, &plug->mq_list);
1920 if (!plug->multiple_queues && !list_is_singular(&plug->mq_list)) {
1921 struct request *tmp;
1923 tmp = list_first_entry(&plug->mq_list, struct request,
1925 if (tmp->q != rq->q)
1926 plug->multiple_queues = true;
1930 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1932 const int is_sync = op_is_sync(bio->bi_opf);
1933 const int is_flush_fua = op_is_flush(bio->bi_opf);
1934 struct blk_mq_alloc_data data = { .flags = 0};
1936 struct blk_plug *plug;
1937 struct request *same_queue_rq = NULL;
1940 blk_queue_bounce(q, &bio);
1942 blk_queue_split(q, &bio);
1944 if (!bio_integrity_prep(bio))
1945 return BLK_QC_T_NONE;
1947 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1948 blk_attempt_plug_merge(q, bio, &same_queue_rq))
1949 return BLK_QC_T_NONE;
1951 if (blk_mq_sched_bio_merge(q, bio))
1952 return BLK_QC_T_NONE;
1954 rq_qos_throttle(q, bio);
1956 data.cmd_flags = bio->bi_opf;
1957 rq = blk_mq_get_request(q, bio, &data);
1958 if (unlikely(!rq)) {
1959 rq_qos_cleanup(q, bio);
1960 if (bio->bi_opf & REQ_NOWAIT)
1961 bio_wouldblock_error(bio);
1962 return BLK_QC_T_NONE;
1965 trace_block_getrq(q, bio, bio->bi_opf);
1967 rq_qos_track(q, rq, bio);
1969 cookie = request_to_qc_t(data.hctx, rq);
1971 plug = current->plug;
1972 if (unlikely(is_flush_fua)) {
1973 blk_mq_put_ctx(data.ctx);
1974 blk_mq_bio_to_request(rq, bio);
1976 /* bypass scheduler for flush rq */
1977 blk_insert_flush(rq);
1978 blk_mq_run_hw_queue(data.hctx, true);
1979 } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) {
1981 * Use plugging if we have a ->commit_rqs() hook as well, as
1982 * we know the driver uses bd->last in a smart fashion.
1984 unsigned int request_count = plug->rq_count;
1985 struct request *last = NULL;
1987 blk_mq_put_ctx(data.ctx);
1988 blk_mq_bio_to_request(rq, bio);
1991 trace_block_plug(q);
1993 last = list_entry_rq(plug->mq_list.prev);
1995 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1996 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1997 blk_flush_plug_list(plug, false);
1998 trace_block_plug(q);
2001 blk_add_rq_to_plug(plug, rq);
2002 } else if (plug && !blk_queue_nomerges(q)) {
2003 blk_mq_bio_to_request(rq, bio);
2006 * We do limited plugging. If the bio can be merged, do that.
2007 * Otherwise the existing request in the plug list will be
2008 * issued. So the plug list will have one request at most
2009 * The plug list might get flushed before this. If that happens,
2010 * the plug list is empty, and same_queue_rq is invalid.
2012 if (list_empty(&plug->mq_list))
2013 same_queue_rq = NULL;
2014 if (same_queue_rq) {
2015 list_del_init(&same_queue_rq->queuelist);
2018 blk_add_rq_to_plug(plug, rq);
2019 trace_block_plug(q);
2021 blk_mq_put_ctx(data.ctx);
2023 if (same_queue_rq) {
2024 data.hctx = same_queue_rq->mq_hctx;
2025 trace_block_unplug(q, 1, true);
2026 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
2029 } else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
2030 !data.hctx->dispatch_busy)) {
2031 blk_mq_put_ctx(data.ctx);
2032 blk_mq_bio_to_request(rq, bio);
2033 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
2035 blk_mq_put_ctx(data.ctx);
2036 blk_mq_bio_to_request(rq, bio);
2037 blk_mq_sched_insert_request(rq, false, true, true);
2043 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2044 unsigned int hctx_idx)
2048 if (tags->rqs && set->ops->exit_request) {
2051 for (i = 0; i < tags->nr_tags; i++) {
2052 struct request *rq = tags->static_rqs[i];
2056 set->ops->exit_request(set, rq, hctx_idx);
2057 tags->static_rqs[i] = NULL;
2061 while (!list_empty(&tags->page_list)) {
2062 page = list_first_entry(&tags->page_list, struct page, lru);
2063 list_del_init(&page->lru);
2065 * Remove kmemleak object previously allocated in
2066 * blk_mq_alloc_rqs().
2068 kmemleak_free(page_address(page));
2069 __free_pages(page, page->private);
2073 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
2077 kfree(tags->static_rqs);
2078 tags->static_rqs = NULL;
2080 blk_mq_free_tags(tags);
2083 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2084 unsigned int hctx_idx,
2085 unsigned int nr_tags,
2086 unsigned int reserved_tags)
2088 struct blk_mq_tags *tags;
2091 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2092 if (node == NUMA_NO_NODE)
2093 node = set->numa_node;
2095 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
2096 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
2100 tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2101 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2104 blk_mq_free_tags(tags);
2108 tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2109 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2111 if (!tags->static_rqs) {
2113 blk_mq_free_tags(tags);
2120 static size_t order_to_size(unsigned int order)
2122 return (size_t)PAGE_SIZE << order;
2125 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2126 unsigned int hctx_idx, int node)
2130 if (set->ops->init_request) {
2131 ret = set->ops->init_request(set, rq, hctx_idx, node);
2136 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
2140 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2141 unsigned int hctx_idx, unsigned int depth)
2143 unsigned int i, j, entries_per_page, max_order = 4;
2144 size_t rq_size, left;
2147 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2148 if (node == NUMA_NO_NODE)
2149 node = set->numa_node;
2151 INIT_LIST_HEAD(&tags->page_list);
2154 * rq_size is the size of the request plus driver payload, rounded
2155 * to the cacheline size
2157 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2159 left = rq_size * depth;
2161 for (i = 0; i < depth; ) {
2162 int this_order = max_order;
2167 while (this_order && left < order_to_size(this_order - 1))
2171 page = alloc_pages_node(node,
2172 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2178 if (order_to_size(this_order) < rq_size)
2185 page->private = this_order;
2186 list_add_tail(&page->lru, &tags->page_list);
2188 p = page_address(page);
2190 * Allow kmemleak to scan these pages as they contain pointers
2191 * to additional allocations like via ops->init_request().
2193 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2194 entries_per_page = order_to_size(this_order) / rq_size;
2195 to_do = min(entries_per_page, depth - i);
2196 left -= to_do * rq_size;
2197 for (j = 0; j < to_do; j++) {
2198 struct request *rq = p;
2200 tags->static_rqs[i] = rq;
2201 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2202 tags->static_rqs[i] = NULL;
2213 blk_mq_free_rqs(set, tags, hctx_idx);
2218 * 'cpu' is going away. splice any existing rq_list entries from this
2219 * software queue to the hw queue dispatch list, and ensure that it
2222 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2224 struct blk_mq_hw_ctx *hctx;
2225 struct blk_mq_ctx *ctx;
2227 enum hctx_type type;
2229 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2230 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2233 spin_lock(&ctx->lock);
2234 if (!list_empty(&ctx->rq_lists[type])) {
2235 list_splice_init(&ctx->rq_lists[type], &tmp);
2236 blk_mq_hctx_clear_pending(hctx, ctx);
2238 spin_unlock(&ctx->lock);
2240 if (list_empty(&tmp))
2243 spin_lock(&hctx->lock);
2244 list_splice_tail_init(&tmp, &hctx->dispatch);
2245 spin_unlock(&hctx->lock);
2247 blk_mq_run_hw_queue(hctx, true);
2251 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2253 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2257 /* hctx->ctxs will be freed in queue's release handler */
2258 static void blk_mq_exit_hctx(struct request_queue *q,
2259 struct blk_mq_tag_set *set,
2260 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2262 if (blk_mq_hw_queue_mapped(hctx))
2263 blk_mq_tag_idle(hctx);
2265 if (set->ops->exit_request)
2266 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2268 if (set->ops->exit_hctx)
2269 set->ops->exit_hctx(hctx, hctx_idx);
2271 blk_mq_remove_cpuhp(hctx);
2273 spin_lock(&q->unused_hctx_lock);
2274 list_add(&hctx->hctx_list, &q->unused_hctx_list);
2275 spin_unlock(&q->unused_hctx_lock);
2278 static void blk_mq_exit_hw_queues(struct request_queue *q,
2279 struct blk_mq_tag_set *set, int nr_queue)
2281 struct blk_mq_hw_ctx *hctx;
2284 queue_for_each_hw_ctx(q, hctx, i) {
2287 blk_mq_debugfs_unregister_hctx(hctx);
2288 blk_mq_exit_hctx(q, set, hctx, i);
2292 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2294 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2296 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2297 __alignof__(struct blk_mq_hw_ctx)) !=
2298 sizeof(struct blk_mq_hw_ctx));
2300 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2301 hw_ctx_size += sizeof(struct srcu_struct);
2306 static int blk_mq_init_hctx(struct request_queue *q,
2307 struct blk_mq_tag_set *set,
2308 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2310 hctx->queue_num = hctx_idx;
2312 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2314 hctx->tags = set->tags[hctx_idx];
2316 if (set->ops->init_hctx &&
2317 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2318 goto unregister_cpu_notifier;
2320 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
2326 if (set->ops->exit_hctx)
2327 set->ops->exit_hctx(hctx, hctx_idx);
2328 unregister_cpu_notifier:
2329 blk_mq_remove_cpuhp(hctx);
2333 static struct blk_mq_hw_ctx *
2334 blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
2337 struct blk_mq_hw_ctx *hctx;
2338 gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
2340 hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
2342 goto fail_alloc_hctx;
2344 if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
2347 atomic_set(&hctx->nr_active, 0);
2348 if (node == NUMA_NO_NODE)
2349 node = set->numa_node;
2350 hctx->numa_node = node;
2352 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2353 spin_lock_init(&hctx->lock);
2354 INIT_LIST_HEAD(&hctx->dispatch);
2356 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
2358 INIT_LIST_HEAD(&hctx->hctx_list);
2361 * Allocate space for all possible cpus to avoid allocation at
2364 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2369 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
2374 spin_lock_init(&hctx->dispatch_wait_lock);
2375 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2376 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2378 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size,
2383 if (hctx->flags & BLK_MQ_F_BLOCKING)
2384 init_srcu_struct(hctx->srcu);
2385 blk_mq_hctx_kobj_init(hctx);
2390 sbitmap_free(&hctx->ctx_map);
2394 free_cpumask_var(hctx->cpumask);
2401 static void blk_mq_init_cpu_queues(struct request_queue *q,
2402 unsigned int nr_hw_queues)
2404 struct blk_mq_tag_set *set = q->tag_set;
2407 for_each_possible_cpu(i) {
2408 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2409 struct blk_mq_hw_ctx *hctx;
2413 spin_lock_init(&__ctx->lock);
2414 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
2415 INIT_LIST_HEAD(&__ctx->rq_lists[k]);
2420 * Set local node, IFF we have more than one hw queue. If
2421 * not, we remain on the home node of the device
2423 for (j = 0; j < set->nr_maps; j++) {
2424 hctx = blk_mq_map_queue_type(q, j, i);
2425 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2426 hctx->numa_node = local_memory_node(cpu_to_node(i));
2431 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2435 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2436 set->queue_depth, set->reserved_tags);
2437 if (!set->tags[hctx_idx])
2440 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2445 blk_mq_free_rq_map(set->tags[hctx_idx]);
2446 set->tags[hctx_idx] = NULL;
2450 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2451 unsigned int hctx_idx)
2453 if (set->tags && set->tags[hctx_idx]) {
2454 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2455 blk_mq_free_rq_map(set->tags[hctx_idx]);
2456 set->tags[hctx_idx] = NULL;
2460 static void blk_mq_map_swqueue(struct request_queue *q)
2462 unsigned int i, j, hctx_idx;
2463 struct blk_mq_hw_ctx *hctx;
2464 struct blk_mq_ctx *ctx;
2465 struct blk_mq_tag_set *set = q->tag_set;
2468 * Avoid others reading imcomplete hctx->cpumask through sysfs
2470 mutex_lock(&q->sysfs_lock);
2472 queue_for_each_hw_ctx(q, hctx, i) {
2473 cpumask_clear(hctx->cpumask);
2475 hctx->dispatch_from = NULL;
2479 * Map software to hardware queues.
2481 * If the cpu isn't present, the cpu is mapped to first hctx.
2483 for_each_possible_cpu(i) {
2484 hctx_idx = set->map[HCTX_TYPE_DEFAULT].mq_map[i];
2485 /* unmapped hw queue can be remapped after CPU topo changed */
2486 if (!set->tags[hctx_idx] &&
2487 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2489 * If tags initialization fail for some hctx,
2490 * that hctx won't be brought online. In this
2491 * case, remap the current ctx to hctx[0] which
2492 * is guaranteed to always have tags allocated
2494 set->map[HCTX_TYPE_DEFAULT].mq_map[i] = 0;
2497 ctx = per_cpu_ptr(q->queue_ctx, i);
2498 for (j = 0; j < set->nr_maps; j++) {
2499 if (!set->map[j].nr_queues) {
2500 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2501 HCTX_TYPE_DEFAULT, i);
2505 hctx = blk_mq_map_queue_type(q, j, i);
2506 ctx->hctxs[j] = hctx;
2508 * If the CPU is already set in the mask, then we've
2509 * mapped this one already. This can happen if
2510 * devices share queues across queue maps.
2512 if (cpumask_test_cpu(i, hctx->cpumask))
2515 cpumask_set_cpu(i, hctx->cpumask);
2517 ctx->index_hw[hctx->type] = hctx->nr_ctx;
2518 hctx->ctxs[hctx->nr_ctx++] = ctx;
2521 * If the nr_ctx type overflows, we have exceeded the
2522 * amount of sw queues we can support.
2524 BUG_ON(!hctx->nr_ctx);
2527 for (; j < HCTX_MAX_TYPES; j++)
2528 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2529 HCTX_TYPE_DEFAULT, i);
2532 mutex_unlock(&q->sysfs_lock);
2534 queue_for_each_hw_ctx(q, hctx, i) {
2536 * If no software queues are mapped to this hardware queue,
2537 * disable it and free the request entries.
2539 if (!hctx->nr_ctx) {
2540 /* Never unmap queue 0. We need it as a
2541 * fallback in case of a new remap fails
2544 if (i && set->tags[i])
2545 blk_mq_free_map_and_requests(set, i);
2551 hctx->tags = set->tags[i];
2552 WARN_ON(!hctx->tags);
2555 * Set the map size to the number of mapped software queues.
2556 * This is more accurate and more efficient than looping
2557 * over all possibly mapped software queues.
2559 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2562 * Initialize batch roundrobin counts
2564 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2565 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2570 * Caller needs to ensure that we're either frozen/quiesced, or that
2571 * the queue isn't live yet.
2573 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2575 struct blk_mq_hw_ctx *hctx;
2578 queue_for_each_hw_ctx(q, hctx, i) {
2580 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2582 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2586 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2589 struct request_queue *q;
2591 lockdep_assert_held(&set->tag_list_lock);
2593 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2594 blk_mq_freeze_queue(q);
2595 queue_set_hctx_shared(q, shared);
2596 blk_mq_unfreeze_queue(q);
2600 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2602 struct blk_mq_tag_set *set = q->tag_set;
2604 mutex_lock(&set->tag_list_lock);
2605 list_del_rcu(&q->tag_set_list);
2606 if (list_is_singular(&set->tag_list)) {
2607 /* just transitioned to unshared */
2608 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2609 /* update existing queue */
2610 blk_mq_update_tag_set_depth(set, false);
2612 mutex_unlock(&set->tag_list_lock);
2613 INIT_LIST_HEAD(&q->tag_set_list);
2616 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2617 struct request_queue *q)
2619 mutex_lock(&set->tag_list_lock);
2622 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2624 if (!list_empty(&set->tag_list) &&
2625 !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2626 set->flags |= BLK_MQ_F_TAG_SHARED;
2627 /* update existing queue */
2628 blk_mq_update_tag_set_depth(set, true);
2630 if (set->flags & BLK_MQ_F_TAG_SHARED)
2631 queue_set_hctx_shared(q, true);
2632 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2634 mutex_unlock(&set->tag_list_lock);
2637 /* All allocations will be freed in release handler of q->mq_kobj */
2638 static int blk_mq_alloc_ctxs(struct request_queue *q)
2640 struct blk_mq_ctxs *ctxs;
2643 ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
2647 ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2648 if (!ctxs->queue_ctx)
2651 for_each_possible_cpu(cpu) {
2652 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
2656 q->mq_kobj = &ctxs->kobj;
2657 q->queue_ctx = ctxs->queue_ctx;
2666 * It is the actual release handler for mq, but we do it from
2667 * request queue's release handler for avoiding use-after-free
2668 * and headache because q->mq_kobj shouldn't have been introduced,
2669 * but we can't group ctx/kctx kobj without it.
2671 void blk_mq_release(struct request_queue *q)
2673 struct blk_mq_hw_ctx *hctx, *next;
2676 cancel_delayed_work_sync(&q->requeue_work);
2678 queue_for_each_hw_ctx(q, hctx, i)
2679 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
2681 /* all hctx are in .unused_hctx_list now */
2682 list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
2683 list_del_init(&hctx->hctx_list);
2684 kobject_put(&hctx->kobj);
2687 kfree(q->queue_hw_ctx);
2690 * release .mq_kobj and sw queue's kobject now because
2691 * both share lifetime with request queue.
2693 blk_mq_sysfs_deinit(q);
2696 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2698 struct request_queue *uninit_q, *q;
2700 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2702 return ERR_PTR(-ENOMEM);
2704 q = blk_mq_init_allocated_queue(set, uninit_q);
2706 blk_cleanup_queue(uninit_q);
2710 EXPORT_SYMBOL(blk_mq_init_queue);
2713 * Helper for setting up a queue with mq ops, given queue depth, and
2714 * the passed in mq ops flags.
2716 struct request_queue *blk_mq_init_sq_queue(struct blk_mq_tag_set *set,
2717 const struct blk_mq_ops *ops,
2718 unsigned int queue_depth,
2719 unsigned int set_flags)
2721 struct request_queue *q;
2724 memset(set, 0, sizeof(*set));
2726 set->nr_hw_queues = 1;
2728 set->queue_depth = queue_depth;
2729 set->numa_node = NUMA_NO_NODE;
2730 set->flags = set_flags;
2732 ret = blk_mq_alloc_tag_set(set);
2734 return ERR_PTR(ret);
2736 q = blk_mq_init_queue(set);
2738 blk_mq_free_tag_set(set);
2744 EXPORT_SYMBOL(blk_mq_init_sq_queue);
2746 static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
2747 struct blk_mq_tag_set *set, struct request_queue *q,
2748 int hctx_idx, int node)
2750 struct blk_mq_hw_ctx *hctx = NULL, *tmp;
2752 /* reuse dead hctx first */
2753 spin_lock(&q->unused_hctx_lock);
2754 list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
2755 if (tmp->numa_node == node) {
2761 list_del_init(&hctx->hctx_list);
2762 spin_unlock(&q->unused_hctx_lock);
2765 hctx = blk_mq_alloc_hctx(q, set, node);
2769 if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
2775 kobject_put(&hctx->kobj);
2780 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2781 struct request_queue *q)
2784 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2786 /* protect against switching io scheduler */
2787 mutex_lock(&q->sysfs_lock);
2788 for (i = 0; i < set->nr_hw_queues; i++) {
2790 struct blk_mq_hw_ctx *hctx;
2792 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], i);
2794 * If the hw queue has been mapped to another numa node,
2795 * we need to realloc the hctx. If allocation fails, fallback
2796 * to use the previous one.
2798 if (hctxs[i] && (hctxs[i]->numa_node == node))
2801 hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
2804 blk_mq_exit_hctx(q, set, hctxs[i], i);
2808 pr_warn("Allocate new hctx on node %d fails,\
2809 fallback to previous one on node %d\n",
2810 node, hctxs[i]->numa_node);
2816 * Increasing nr_hw_queues fails. Free the newly allocated
2817 * hctxs and keep the previous q->nr_hw_queues.
2819 if (i != set->nr_hw_queues) {
2820 j = q->nr_hw_queues;
2824 end = q->nr_hw_queues;
2825 q->nr_hw_queues = set->nr_hw_queues;
2828 for (; j < end; j++) {
2829 struct blk_mq_hw_ctx *hctx = hctxs[j];
2833 blk_mq_free_map_and_requests(set, j);
2834 blk_mq_exit_hctx(q, set, hctx, j);
2838 mutex_unlock(&q->sysfs_lock);
2842 * Maximum number of hardware queues we support. For single sets, we'll never
2843 * have more than the CPUs (software queues). For multiple sets, the tag_set
2844 * user may have set ->nr_hw_queues larger.
2846 static unsigned int nr_hw_queues(struct blk_mq_tag_set *set)
2848 if (set->nr_maps == 1)
2851 return max(set->nr_hw_queues, nr_cpu_ids);
2854 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2855 struct request_queue *q)
2857 /* mark the queue as mq asap */
2858 q->mq_ops = set->ops;
2860 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2861 blk_mq_poll_stats_bkt,
2862 BLK_MQ_POLL_STATS_BKTS, q);
2866 if (blk_mq_alloc_ctxs(q))
2869 /* init q->mq_kobj and sw queues' kobjects */
2870 blk_mq_sysfs_init(q);
2872 q->nr_queues = nr_hw_queues(set);
2873 q->queue_hw_ctx = kcalloc_node(q->nr_queues, sizeof(*(q->queue_hw_ctx)),
2874 GFP_KERNEL, set->numa_node);
2875 if (!q->queue_hw_ctx)
2878 INIT_LIST_HEAD(&q->unused_hctx_list);
2879 spin_lock_init(&q->unused_hctx_lock);
2881 blk_mq_realloc_hw_ctxs(set, q);
2882 if (!q->nr_hw_queues)
2885 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2886 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2890 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2891 if (set->nr_maps > HCTX_TYPE_POLL &&
2892 set->map[HCTX_TYPE_POLL].nr_queues)
2893 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
2895 q->sg_reserved_size = INT_MAX;
2897 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2898 INIT_LIST_HEAD(&q->requeue_list);
2899 spin_lock_init(&q->requeue_lock);
2901 blk_queue_make_request(q, blk_mq_make_request);
2904 * Do this after blk_queue_make_request() overrides it...
2906 q->nr_requests = set->queue_depth;
2909 * Default to classic polling
2911 q->poll_nsec = BLK_MQ_POLL_CLASSIC;
2913 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2914 blk_mq_add_queue_tag_set(set, q);
2915 blk_mq_map_swqueue(q);
2917 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2920 ret = elevator_init_mq(q);
2922 return ERR_PTR(ret);
2928 kfree(q->queue_hw_ctx);
2930 blk_mq_sysfs_deinit(q);
2933 return ERR_PTR(-ENOMEM);
2935 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2937 /* tags can _not_ be used after returning from blk_mq_exit_queue */
2938 void blk_mq_exit_queue(struct request_queue *q)
2940 struct blk_mq_tag_set *set = q->tag_set;
2942 blk_mq_del_queue_tag_set(q);
2943 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2946 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2950 for (i = 0; i < set->nr_hw_queues; i++)
2951 if (!__blk_mq_alloc_rq_map(set, i))
2958 blk_mq_free_rq_map(set->tags[i]);
2964 * Allocate the request maps associated with this tag_set. Note that this
2965 * may reduce the depth asked for, if memory is tight. set->queue_depth
2966 * will be updated to reflect the allocated depth.
2968 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2973 depth = set->queue_depth;
2975 err = __blk_mq_alloc_rq_maps(set);
2979 set->queue_depth >>= 1;
2980 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2984 } while (set->queue_depth);
2986 if (!set->queue_depth || err) {
2987 pr_err("blk-mq: failed to allocate request map\n");
2991 if (depth != set->queue_depth)
2992 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2993 depth, set->queue_depth);
2998 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
3000 if (set->ops->map_queues && !is_kdump_kernel()) {
3004 * transport .map_queues is usually done in the following
3007 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3008 * mask = get_cpu_mask(queue)
3009 * for_each_cpu(cpu, mask)
3010 * set->map[x].mq_map[cpu] = queue;
3013 * When we need to remap, the table has to be cleared for
3014 * killing stale mapping since one CPU may not be mapped
3017 for (i = 0; i < set->nr_maps; i++)
3018 blk_mq_clear_mq_map(&set->map[i]);
3020 return set->ops->map_queues(set);
3022 BUG_ON(set->nr_maps > 1);
3023 return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3028 * Alloc a tag set to be associated with one or more request queues.
3029 * May fail with EINVAL for various error conditions. May adjust the
3030 * requested depth down, if it's too large. In that case, the set
3031 * value will be stored in set->queue_depth.
3033 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
3037 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
3039 if (!set->nr_hw_queues)
3041 if (!set->queue_depth)
3043 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
3046 if (!set->ops->queue_rq)
3049 if (!set->ops->get_budget ^ !set->ops->put_budget)
3052 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
3053 pr_info("blk-mq: reduced tag depth to %u\n",
3055 set->queue_depth = BLK_MQ_MAX_DEPTH;
3060 else if (set->nr_maps > HCTX_MAX_TYPES)
3064 * If a crashdump is active, then we are potentially in a very
3065 * memory constrained environment. Limit us to 1 queue and
3066 * 64 tags to prevent using too much memory.
3068 if (is_kdump_kernel()) {
3069 set->nr_hw_queues = 1;
3071 set->queue_depth = min(64U, set->queue_depth);
3074 * There is no use for more h/w queues than cpus if we just have
3077 if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
3078 set->nr_hw_queues = nr_cpu_ids;
3080 set->tags = kcalloc_node(nr_hw_queues(set), sizeof(struct blk_mq_tags *),
3081 GFP_KERNEL, set->numa_node);
3086 for (i = 0; i < set->nr_maps; i++) {
3087 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
3088 sizeof(set->map[i].mq_map[0]),
3089 GFP_KERNEL, set->numa_node);
3090 if (!set->map[i].mq_map)
3091 goto out_free_mq_map;
3092 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
3095 ret = blk_mq_update_queue_map(set);
3097 goto out_free_mq_map;
3099 ret = blk_mq_alloc_rq_maps(set);
3101 goto out_free_mq_map;
3103 mutex_init(&set->tag_list_lock);
3104 INIT_LIST_HEAD(&set->tag_list);
3109 for (i = 0; i < set->nr_maps; i++) {
3110 kfree(set->map[i].mq_map);
3111 set->map[i].mq_map = NULL;
3117 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
3119 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
3123 for (i = 0; i < nr_hw_queues(set); i++)
3124 blk_mq_free_map_and_requests(set, i);
3126 for (j = 0; j < set->nr_maps; j++) {
3127 kfree(set->map[j].mq_map);
3128 set->map[j].mq_map = NULL;
3134 EXPORT_SYMBOL(blk_mq_free_tag_set);
3136 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
3138 struct blk_mq_tag_set *set = q->tag_set;
3139 struct blk_mq_hw_ctx *hctx;
3145 if (q->nr_requests == nr)
3148 blk_mq_freeze_queue(q);
3149 blk_mq_quiesce_queue(q);
3152 queue_for_each_hw_ctx(q, hctx, i) {
3156 * If we're using an MQ scheduler, just update the scheduler
3157 * queue depth. This is similar to what the old code would do.
3159 if (!hctx->sched_tags) {
3160 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
3163 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
3168 if (q->elevator && q->elevator->type->ops.depth_updated)
3169 q->elevator->type->ops.depth_updated(hctx);
3173 q->nr_requests = nr;
3175 blk_mq_unquiesce_queue(q);
3176 blk_mq_unfreeze_queue(q);
3182 * request_queue and elevator_type pair.
3183 * It is just used by __blk_mq_update_nr_hw_queues to cache
3184 * the elevator_type associated with a request_queue.
3186 struct blk_mq_qe_pair {
3187 struct list_head node;
3188 struct request_queue *q;
3189 struct elevator_type *type;
3193 * Cache the elevator_type in qe pair list and switch the
3194 * io scheduler to 'none'
3196 static bool blk_mq_elv_switch_none(struct list_head *head,
3197 struct request_queue *q)
3199 struct blk_mq_qe_pair *qe;
3204 qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
3208 INIT_LIST_HEAD(&qe->node);
3210 qe->type = q->elevator->type;
3211 list_add(&qe->node, head);
3213 mutex_lock(&q->sysfs_lock);
3215 * After elevator_switch_mq, the previous elevator_queue will be
3216 * released by elevator_release. The reference of the io scheduler
3217 * module get by elevator_get will also be put. So we need to get
3218 * a reference of the io scheduler module here to prevent it to be
3221 __module_get(qe->type->elevator_owner);
3222 elevator_switch_mq(q, NULL);
3223 mutex_unlock(&q->sysfs_lock);
3228 static void blk_mq_elv_switch_back(struct list_head *head,
3229 struct request_queue *q)
3231 struct blk_mq_qe_pair *qe;
3232 struct elevator_type *t = NULL;
3234 list_for_each_entry(qe, head, node)
3243 list_del(&qe->node);
3246 mutex_lock(&q->sysfs_lock);
3247 elevator_switch_mq(q, t);
3248 mutex_unlock(&q->sysfs_lock);
3251 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
3254 struct request_queue *q;
3256 int prev_nr_hw_queues;
3258 lockdep_assert_held(&set->tag_list_lock);
3260 if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
3261 nr_hw_queues = nr_cpu_ids;
3262 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
3265 list_for_each_entry(q, &set->tag_list, tag_set_list)
3266 blk_mq_freeze_queue(q);
3268 * Sync with blk_mq_queue_tag_busy_iter.
3272 * Switch IO scheduler to 'none', cleaning up the data associated
3273 * with the previous scheduler. We will switch back once we are done
3274 * updating the new sw to hw queue mappings.
3276 list_for_each_entry(q, &set->tag_list, tag_set_list)
3277 if (!blk_mq_elv_switch_none(&head, q))
3280 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3281 blk_mq_debugfs_unregister_hctxs(q);
3282 blk_mq_sysfs_unregister(q);
3285 prev_nr_hw_queues = set->nr_hw_queues;
3286 set->nr_hw_queues = nr_hw_queues;
3287 blk_mq_update_queue_map(set);
3289 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3290 blk_mq_realloc_hw_ctxs(set, q);
3291 if (q->nr_hw_queues != set->nr_hw_queues) {
3292 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3293 nr_hw_queues, prev_nr_hw_queues);
3294 set->nr_hw_queues = prev_nr_hw_queues;
3295 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3298 blk_mq_map_swqueue(q);
3301 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3302 blk_mq_sysfs_register(q);
3303 blk_mq_debugfs_register_hctxs(q);
3307 list_for_each_entry(q, &set->tag_list, tag_set_list)
3308 blk_mq_elv_switch_back(&head, q);
3310 list_for_each_entry(q, &set->tag_list, tag_set_list)
3311 blk_mq_unfreeze_queue(q);
3314 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
3316 mutex_lock(&set->tag_list_lock);
3317 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
3318 mutex_unlock(&set->tag_list_lock);
3320 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
3322 /* Enable polling stats and return whether they were already enabled. */
3323 static bool blk_poll_stats_enable(struct request_queue *q)
3325 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3326 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
3328 blk_stat_add_callback(q, q->poll_cb);
3332 static void blk_mq_poll_stats_start(struct request_queue *q)
3335 * We don't arm the callback if polling stats are not enabled or the
3336 * callback is already active.
3338 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3339 blk_stat_is_active(q->poll_cb))
3342 blk_stat_activate_msecs(q->poll_cb, 100);
3345 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3347 struct request_queue *q = cb->data;
3350 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3351 if (cb->stat[bucket].nr_samples)
3352 q->poll_stat[bucket] = cb->stat[bucket];
3356 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3357 struct blk_mq_hw_ctx *hctx,
3360 unsigned long ret = 0;
3364 * If stats collection isn't on, don't sleep but turn it on for
3367 if (!blk_poll_stats_enable(q))
3371 * As an optimistic guess, use half of the mean service time
3372 * for this type of request. We can (and should) make this smarter.
3373 * For instance, if the completion latencies are tight, we can
3374 * get closer than just half the mean. This is especially
3375 * important on devices where the completion latencies are longer
3376 * than ~10 usec. We do use the stats for the relevant IO size
3377 * if available which does lead to better estimates.
3379 bucket = blk_mq_poll_stats_bkt(rq);
3383 if (q->poll_stat[bucket].nr_samples)
3384 ret = (q->poll_stat[bucket].mean + 1) / 2;
3389 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3390 struct blk_mq_hw_ctx *hctx,
3393 struct hrtimer_sleeper hs;
3394 enum hrtimer_mode mode;
3398 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3402 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3404 * 0: use half of prev avg
3405 * >0: use this specific value
3407 if (q->poll_nsec > 0)
3408 nsecs = q->poll_nsec;
3410 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
3415 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3418 * This will be replaced with the stats tracking code, using
3419 * 'avg_completion_time / 2' as the pre-sleep target.
3423 mode = HRTIMER_MODE_REL;
3424 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
3425 hrtimer_set_expires(&hs.timer, kt);
3427 hrtimer_init_sleeper(&hs, current);
3429 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3431 set_current_state(TASK_UNINTERRUPTIBLE);
3432 hrtimer_start_expires(&hs.timer, mode);
3435 hrtimer_cancel(&hs.timer);
3436 mode = HRTIMER_MODE_ABS;
3437 } while (hs.task && !signal_pending(current));
3439 __set_current_state(TASK_RUNNING);
3440 destroy_hrtimer_on_stack(&hs.timer);
3444 static bool blk_mq_poll_hybrid(struct request_queue *q,
3445 struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
3449 if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
3452 if (!blk_qc_t_is_internal(cookie))
3453 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3455 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3457 * With scheduling, if the request has completed, we'll
3458 * get a NULL return here, as we clear the sched tag when
3459 * that happens. The request still remains valid, like always,
3460 * so we should be safe with just the NULL check.
3466 return blk_mq_poll_hybrid_sleep(q, hctx, rq);
3470 * blk_poll - poll for IO completions
3472 * @cookie: cookie passed back at IO submission time
3473 * @spin: whether to spin for completions
3476 * Poll for completions on the passed in queue. Returns number of
3477 * completed entries found. If @spin is true, then blk_poll will continue
3478 * looping until at least one completion is found, unless the task is
3479 * otherwise marked running (or we need to reschedule).
3481 int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
3483 struct blk_mq_hw_ctx *hctx;
3486 if (!blk_qc_t_valid(cookie) ||
3487 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3491 blk_flush_plug_list(current->plug, false);
3493 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3496 * If we sleep, have the caller restart the poll loop to reset
3497 * the state. Like for the other success return cases, the
3498 * caller is responsible for checking if the IO completed. If
3499 * the IO isn't complete, we'll get called again and will go
3500 * straight to the busy poll loop.
3502 if (blk_mq_poll_hybrid(q, hctx, cookie))
3505 hctx->poll_considered++;
3507 state = current->state;
3511 hctx->poll_invoked++;
3513 ret = q->mq_ops->poll(hctx);
3515 hctx->poll_success++;
3516 __set_current_state(TASK_RUNNING);
3520 if (signal_pending_state(state, current))
3521 __set_current_state(TASK_RUNNING);
3523 if (current->state == TASK_RUNNING)
3525 if (ret < 0 || !spin)
3528 } while (!need_resched());
3530 __set_current_state(TASK_RUNNING);
3533 EXPORT_SYMBOL_GPL(blk_poll);
3535 unsigned int blk_mq_rq_cpu(struct request *rq)
3537 return rq->mq_ctx->cpu;
3539 EXPORT_SYMBOL(blk_mq_rq_cpu);
3541 static int __init blk_mq_init(void)
3543 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3544 blk_mq_hctx_notify_dead);
3547 subsys_initcall(blk_mq_init);