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)
147 mutex_lock(&q->mq_freeze_lock);
148 if (++q->mq_freeze_depth == 1) {
149 percpu_ref_kill(&q->q_usage_counter);
150 mutex_unlock(&q->mq_freeze_lock);
152 blk_mq_run_hw_queues(q, false);
154 mutex_unlock(&q->mq_freeze_lock);
157 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
159 void blk_mq_freeze_queue_wait(struct request_queue *q)
161 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
163 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
165 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
166 unsigned long timeout)
168 return wait_event_timeout(q->mq_freeze_wq,
169 percpu_ref_is_zero(&q->q_usage_counter),
172 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
175 * Guarantee no request is in use, so we can change any data structure of
176 * the queue afterward.
178 void blk_freeze_queue(struct request_queue *q)
181 * In the !blk_mq case we are only calling this to kill the
182 * q_usage_counter, otherwise this increases the freeze depth
183 * and waits for it to return to zero. For this reason there is
184 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
185 * exported to drivers as the only user for unfreeze is blk_mq.
187 blk_freeze_queue_start(q);
188 blk_mq_freeze_queue_wait(q);
191 void blk_mq_freeze_queue(struct request_queue *q)
194 * ...just an alias to keep freeze and unfreeze actions balanced
195 * in the blk_mq_* namespace
199 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
201 void blk_mq_unfreeze_queue(struct request_queue *q)
203 mutex_lock(&q->mq_freeze_lock);
204 q->mq_freeze_depth--;
205 WARN_ON_ONCE(q->mq_freeze_depth < 0);
206 if (!q->mq_freeze_depth) {
207 percpu_ref_resurrect(&q->q_usage_counter);
208 wake_up_all(&q->mq_freeze_wq);
210 mutex_unlock(&q->mq_freeze_lock);
212 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
215 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
216 * mpt3sas driver such that this function can be removed.
218 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
220 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
222 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
225 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
228 * Note: this function does not prevent that the struct request end_io()
229 * callback function is invoked. Once this function is returned, we make
230 * sure no dispatch can happen until the queue is unquiesced via
231 * blk_mq_unquiesce_queue().
233 void blk_mq_quiesce_queue(struct request_queue *q)
235 struct blk_mq_hw_ctx *hctx;
239 blk_mq_quiesce_queue_nowait(q);
241 queue_for_each_hw_ctx(q, hctx, i) {
242 if (hctx->flags & BLK_MQ_F_BLOCKING)
243 synchronize_srcu(hctx->srcu);
250 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
253 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
256 * This function recovers queue into the state before quiescing
257 * which is done by blk_mq_quiesce_queue.
259 void blk_mq_unquiesce_queue(struct request_queue *q)
261 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
263 /* dispatch requests which are inserted during quiescing */
264 blk_mq_run_hw_queues(q, true);
266 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
268 void blk_mq_wake_waiters(struct request_queue *q)
270 struct blk_mq_hw_ctx *hctx;
273 queue_for_each_hw_ctx(q, hctx, i)
274 if (blk_mq_hw_queue_mapped(hctx))
275 blk_mq_tag_wakeup_all(hctx->tags, true);
278 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
280 return blk_mq_has_free_tags(hctx->tags);
282 EXPORT_SYMBOL(blk_mq_can_queue);
285 * Only need start/end time stamping if we have stats enabled, or using
288 static inline bool blk_mq_need_time_stamp(struct request *rq)
290 return (rq->rq_flags & RQF_IO_STAT) || rq->q->elevator;
293 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
294 unsigned int tag, unsigned int op, u64 alloc_time_ns)
296 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
297 struct request *rq = tags->static_rqs[tag];
298 req_flags_t rq_flags = 0;
300 if (data->flags & BLK_MQ_REQ_INTERNAL) {
302 rq->internal_tag = tag;
304 if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) {
305 rq_flags = RQF_MQ_INFLIGHT;
306 atomic_inc(&data->hctx->nr_active);
309 rq->internal_tag = -1;
310 data->hctx->tags->rqs[rq->tag] = rq;
313 /* csd/requeue_work/fifo_time is initialized before use */
315 rq->mq_ctx = data->ctx;
316 rq->mq_hctx = data->hctx;
317 rq->rq_flags = rq_flags;
319 if (data->flags & BLK_MQ_REQ_PREEMPT)
320 rq->rq_flags |= RQF_PREEMPT;
321 if (blk_queue_io_stat(data->q))
322 rq->rq_flags |= RQF_IO_STAT;
323 INIT_LIST_HEAD(&rq->queuelist);
324 INIT_HLIST_NODE(&rq->hash);
325 RB_CLEAR_NODE(&rq->rb_node);
328 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
329 rq->alloc_time_ns = alloc_time_ns;
331 if (blk_mq_need_time_stamp(rq))
332 rq->start_time_ns = ktime_get_ns();
334 rq->start_time_ns = 0;
335 rq->io_start_time_ns = 0;
336 rq->nr_phys_segments = 0;
337 #if defined(CONFIG_BLK_DEV_INTEGRITY)
338 rq->nr_integrity_segments = 0;
340 /* tag was already set */
342 WRITE_ONCE(rq->deadline, 0);
347 rq->end_io_data = NULL;
349 data->ctx->rq_dispatched[op_is_sync(op)]++;
350 refcount_set(&rq->ref, 1);
354 static struct request *blk_mq_get_request(struct request_queue *q,
356 struct blk_mq_alloc_data *data)
358 struct elevator_queue *e = q->elevator;
361 bool clear_ctx_on_error = false;
362 u64 alloc_time_ns = 0;
364 blk_queue_enter_live(q);
366 /* alloc_time includes depth and tag waits */
367 if (blk_queue_rq_alloc_time(q))
368 alloc_time_ns = ktime_get_ns();
371 if (likely(!data->ctx)) {
372 data->ctx = blk_mq_get_ctx(q);
373 clear_ctx_on_error = true;
375 if (likely(!data->hctx))
376 data->hctx = blk_mq_map_queue(q, data->cmd_flags,
378 if (data->cmd_flags & REQ_NOWAIT)
379 data->flags |= BLK_MQ_REQ_NOWAIT;
382 data->flags |= BLK_MQ_REQ_INTERNAL;
385 * Flush requests are special and go directly to the
386 * dispatch list. Don't include reserved tags in the
387 * limiting, as it isn't useful.
389 if (!op_is_flush(data->cmd_flags) &&
390 e->type->ops.limit_depth &&
391 !(data->flags & BLK_MQ_REQ_RESERVED))
392 e->type->ops.limit_depth(data->cmd_flags, data);
394 blk_mq_tag_busy(data->hctx);
397 tag = blk_mq_get_tag(data);
398 if (tag == BLK_MQ_TAG_FAIL) {
399 if (clear_ctx_on_error)
405 rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags, alloc_time_ns);
406 if (!op_is_flush(data->cmd_flags)) {
408 if (e && e->type->ops.prepare_request) {
409 if (e->type->icq_cache)
410 blk_mq_sched_assign_ioc(rq);
412 e->type->ops.prepare_request(rq, bio);
413 rq->rq_flags |= RQF_ELVPRIV;
416 data->hctx->queued++;
420 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
421 blk_mq_req_flags_t flags)
423 struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
427 ret = blk_queue_enter(q, flags);
431 rq = blk_mq_get_request(q, NULL, &alloc_data);
435 return ERR_PTR(-EWOULDBLOCK);
438 rq->__sector = (sector_t) -1;
439 rq->bio = rq->biotail = NULL;
442 EXPORT_SYMBOL(blk_mq_alloc_request);
444 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
445 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
447 struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
453 * If the tag allocator sleeps we could get an allocation for a
454 * different hardware context. No need to complicate the low level
455 * allocator for this for the rare use case of a command tied to
458 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
459 return ERR_PTR(-EINVAL);
461 if (hctx_idx >= q->nr_hw_queues)
462 return ERR_PTR(-EIO);
464 ret = blk_queue_enter(q, flags);
469 * Check if the hardware context is actually mapped to anything.
470 * If not tell the caller that it should skip this queue.
472 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
473 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
475 return ERR_PTR(-EXDEV);
477 cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
478 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
480 rq = blk_mq_get_request(q, NULL, &alloc_data);
484 return ERR_PTR(-EWOULDBLOCK);
488 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
490 static void __blk_mq_free_request(struct request *rq)
492 struct request_queue *q = rq->q;
493 struct blk_mq_ctx *ctx = rq->mq_ctx;
494 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
495 const int sched_tag = rq->internal_tag;
497 blk_pm_mark_last_busy(rq);
500 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
502 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
503 blk_mq_sched_restart(hctx);
507 void blk_mq_free_request(struct request *rq)
509 struct request_queue *q = rq->q;
510 struct elevator_queue *e = q->elevator;
511 struct blk_mq_ctx *ctx = rq->mq_ctx;
512 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
514 if (rq->rq_flags & RQF_ELVPRIV) {
515 if (e && e->type->ops.finish_request)
516 e->type->ops.finish_request(rq);
518 put_io_context(rq->elv.icq->ioc);
523 ctx->rq_completed[rq_is_sync(rq)]++;
524 if (rq->rq_flags & RQF_MQ_INFLIGHT)
525 atomic_dec(&hctx->nr_active);
527 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
528 laptop_io_completion(q->backing_dev_info);
532 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
533 if (refcount_dec_and_test(&rq->ref))
534 __blk_mq_free_request(rq);
536 EXPORT_SYMBOL_GPL(blk_mq_free_request);
538 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
542 if (blk_mq_need_time_stamp(rq))
543 now = ktime_get_ns();
545 if (rq->rq_flags & RQF_STATS) {
546 blk_mq_poll_stats_start(rq->q);
547 blk_stat_add(rq, now);
550 if (rq->internal_tag != -1)
551 blk_mq_sched_completed_request(rq, now);
553 blk_account_io_done(rq, now);
556 rq_qos_done(rq->q, rq);
557 rq->end_io(rq, error);
559 blk_mq_free_request(rq);
562 EXPORT_SYMBOL(__blk_mq_end_request);
564 void blk_mq_end_request(struct request *rq, blk_status_t error)
566 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
568 __blk_mq_end_request(rq, error);
570 EXPORT_SYMBOL(blk_mq_end_request);
572 static void __blk_mq_complete_request_remote(void *data)
574 struct request *rq = data;
575 struct request_queue *q = rq->q;
577 q->mq_ops->complete(rq);
580 static void __blk_mq_complete_request(struct request *rq)
582 struct blk_mq_ctx *ctx = rq->mq_ctx;
583 struct request_queue *q = rq->q;
587 WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
589 * Most of single queue controllers, there is only one irq vector
590 * for handling IO completion, and the only irq's affinity is set
591 * as all possible CPUs. On most of ARCHs, this affinity means the
592 * irq is handled on one specific CPU.
594 * So complete IO reqeust in softirq context in case of single queue
595 * for not degrading IO performance by irqsoff latency.
597 if (q->nr_hw_queues == 1) {
598 __blk_complete_request(rq);
603 * For a polled request, always complete locallly, it's pointless
604 * to redirect the completion.
606 if ((rq->cmd_flags & REQ_HIPRI) ||
607 !test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
608 q->mq_ops->complete(rq);
613 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
614 shared = cpus_share_cache(cpu, ctx->cpu);
616 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
617 rq->csd.func = __blk_mq_complete_request_remote;
620 smp_call_function_single_async(ctx->cpu, &rq->csd);
622 q->mq_ops->complete(rq);
627 static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
628 __releases(hctx->srcu)
630 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
633 srcu_read_unlock(hctx->srcu, srcu_idx);
636 static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
637 __acquires(hctx->srcu)
639 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
640 /* shut up gcc false positive */
644 *srcu_idx = srcu_read_lock(hctx->srcu);
648 * blk_mq_complete_request - end I/O on a request
649 * @rq: the request being processed
652 * Ends all I/O on a request. It does not handle partial completions.
653 * The actual completion happens out-of-order, through a IPI handler.
655 bool blk_mq_complete_request(struct request *rq)
657 if (unlikely(blk_should_fake_timeout(rq->q)))
659 __blk_mq_complete_request(rq);
662 EXPORT_SYMBOL(blk_mq_complete_request);
664 int blk_mq_request_started(struct request *rq)
666 return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
668 EXPORT_SYMBOL_GPL(blk_mq_request_started);
670 int blk_mq_request_completed(struct request *rq)
672 return blk_mq_rq_state(rq) == MQ_RQ_COMPLETE;
674 EXPORT_SYMBOL_GPL(blk_mq_request_completed);
676 void blk_mq_start_request(struct request *rq)
678 struct request_queue *q = rq->q;
680 trace_block_rq_issue(q, rq);
682 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
683 rq->io_start_time_ns = ktime_get_ns();
684 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
685 rq->throtl_size = blk_rq_sectors(rq);
687 rq->rq_flags |= RQF_STATS;
691 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
694 WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
696 if (q->dma_drain_size && blk_rq_bytes(rq)) {
698 * Make sure space for the drain appears. We know we can do
699 * this because max_hw_segments has been adjusted to be one
700 * fewer than the device can handle.
702 rq->nr_phys_segments++;
705 EXPORT_SYMBOL(blk_mq_start_request);
707 static void __blk_mq_requeue_request(struct request *rq)
709 struct request_queue *q = rq->q;
711 blk_mq_put_driver_tag(rq);
713 trace_block_rq_requeue(q, rq);
714 rq_qos_requeue(q, rq);
716 if (blk_mq_request_started(rq)) {
717 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
718 rq->rq_flags &= ~RQF_TIMED_OUT;
719 if (q->dma_drain_size && blk_rq_bytes(rq))
720 rq->nr_phys_segments--;
724 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
726 __blk_mq_requeue_request(rq);
728 /* this request will be re-inserted to io scheduler queue */
729 blk_mq_sched_requeue_request(rq);
731 BUG_ON(!list_empty(&rq->queuelist));
732 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
734 EXPORT_SYMBOL(blk_mq_requeue_request);
736 static void blk_mq_requeue_work(struct work_struct *work)
738 struct request_queue *q =
739 container_of(work, struct request_queue, requeue_work.work);
741 struct request *rq, *next;
743 spin_lock_irq(&q->requeue_lock);
744 list_splice_init(&q->requeue_list, &rq_list);
745 spin_unlock_irq(&q->requeue_lock);
747 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
748 if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP)))
751 rq->rq_flags &= ~RQF_SOFTBARRIER;
752 list_del_init(&rq->queuelist);
754 * If RQF_DONTPREP, rq has contained some driver specific
755 * data, so insert it to hctx dispatch list to avoid any
758 if (rq->rq_flags & RQF_DONTPREP)
759 blk_mq_request_bypass_insert(rq, false);
761 blk_mq_sched_insert_request(rq, true, false, false);
764 while (!list_empty(&rq_list)) {
765 rq = list_entry(rq_list.next, struct request, queuelist);
766 list_del_init(&rq->queuelist);
767 blk_mq_sched_insert_request(rq, false, false, false);
770 blk_mq_run_hw_queues(q, false);
773 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
774 bool kick_requeue_list)
776 struct request_queue *q = rq->q;
780 * We abuse this flag that is otherwise used by the I/O scheduler to
781 * request head insertion from the workqueue.
783 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
785 spin_lock_irqsave(&q->requeue_lock, flags);
787 rq->rq_flags |= RQF_SOFTBARRIER;
788 list_add(&rq->queuelist, &q->requeue_list);
790 list_add_tail(&rq->queuelist, &q->requeue_list);
792 spin_unlock_irqrestore(&q->requeue_lock, flags);
794 if (kick_requeue_list)
795 blk_mq_kick_requeue_list(q);
798 void blk_mq_kick_requeue_list(struct request_queue *q)
800 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
802 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
804 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
807 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
808 msecs_to_jiffies(msecs));
810 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
812 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
814 if (tag < tags->nr_tags) {
815 prefetch(tags->rqs[tag]);
816 return tags->rqs[tag];
821 EXPORT_SYMBOL(blk_mq_tag_to_rq);
823 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq,
824 void *priv, bool reserved)
827 * If we find a request that is inflight and the queue matches,
828 * we know the queue is busy. Return false to stop the iteration.
830 if (rq->state == MQ_RQ_IN_FLIGHT && rq->q == hctx->queue) {
840 bool blk_mq_queue_inflight(struct request_queue *q)
844 blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
847 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
849 static void blk_mq_rq_timed_out(struct request *req, bool reserved)
851 req->rq_flags |= RQF_TIMED_OUT;
852 if (req->q->mq_ops->timeout) {
853 enum blk_eh_timer_return ret;
855 ret = req->q->mq_ops->timeout(req, reserved);
856 if (ret == BLK_EH_DONE)
858 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
864 static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
866 unsigned long deadline;
868 if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
870 if (rq->rq_flags & RQF_TIMED_OUT)
873 deadline = READ_ONCE(rq->deadline);
874 if (time_after_eq(jiffies, deadline))
879 else if (time_after(*next, deadline))
884 static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
885 struct request *rq, void *priv, bool reserved)
887 unsigned long *next = priv;
890 * Just do a quick check if it is expired before locking the request in
891 * so we're not unnecessarilly synchronizing across CPUs.
893 if (!blk_mq_req_expired(rq, next))
897 * We have reason to believe the request may be expired. Take a
898 * reference on the request to lock this request lifetime into its
899 * currently allocated context to prevent it from being reallocated in
900 * the event the completion by-passes this timeout handler.
902 * If the reference was already released, then the driver beat the
903 * timeout handler to posting a natural completion.
905 if (!refcount_inc_not_zero(&rq->ref))
909 * The request is now locked and cannot be reallocated underneath the
910 * timeout handler's processing. Re-verify this exact request is truly
911 * expired; if it is not expired, then the request was completed and
912 * reallocated as a new request.
914 if (blk_mq_req_expired(rq, next))
915 blk_mq_rq_timed_out(rq, reserved);
916 if (refcount_dec_and_test(&rq->ref))
917 __blk_mq_free_request(rq);
922 static void blk_mq_timeout_work(struct work_struct *work)
924 struct request_queue *q =
925 container_of(work, struct request_queue, timeout_work);
926 unsigned long next = 0;
927 struct blk_mq_hw_ctx *hctx;
930 /* A deadlock might occur if a request is stuck requiring a
931 * timeout at the same time a queue freeze is waiting
932 * completion, since the timeout code would not be able to
933 * acquire the queue reference here.
935 * That's why we don't use blk_queue_enter here; instead, we use
936 * percpu_ref_tryget directly, because we need to be able to
937 * obtain a reference even in the short window between the queue
938 * starting to freeze, by dropping the first reference in
939 * blk_freeze_queue_start, and the moment the last request is
940 * consumed, marked by the instant q_usage_counter reaches
943 if (!percpu_ref_tryget(&q->q_usage_counter))
946 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
949 mod_timer(&q->timeout, next);
952 * Request timeouts are handled as a forward rolling timer. If
953 * we end up here it means that no requests are pending and
954 * also that no request has been pending for a while. Mark
957 queue_for_each_hw_ctx(q, hctx, i) {
958 /* the hctx may be unmapped, so check it here */
959 if (blk_mq_hw_queue_mapped(hctx))
960 blk_mq_tag_idle(hctx);
966 struct flush_busy_ctx_data {
967 struct blk_mq_hw_ctx *hctx;
968 struct list_head *list;
971 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
973 struct flush_busy_ctx_data *flush_data = data;
974 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
975 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
976 enum hctx_type type = hctx->type;
978 spin_lock(&ctx->lock);
979 list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
980 sbitmap_clear_bit(sb, bitnr);
981 spin_unlock(&ctx->lock);
986 * Process software queues that have been marked busy, splicing them
987 * to the for-dispatch
989 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
991 struct flush_busy_ctx_data data = {
996 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
998 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1000 struct dispatch_rq_data {
1001 struct blk_mq_hw_ctx *hctx;
1005 static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1008 struct dispatch_rq_data *dispatch_data = data;
1009 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1010 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1011 enum hctx_type type = hctx->type;
1013 spin_lock(&ctx->lock);
1014 if (!list_empty(&ctx->rq_lists[type])) {
1015 dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
1016 list_del_init(&dispatch_data->rq->queuelist);
1017 if (list_empty(&ctx->rq_lists[type]))
1018 sbitmap_clear_bit(sb, bitnr);
1020 spin_unlock(&ctx->lock);
1022 return !dispatch_data->rq;
1025 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1026 struct blk_mq_ctx *start)
1028 unsigned off = start ? start->index_hw[hctx->type] : 0;
1029 struct dispatch_rq_data data = {
1034 __sbitmap_for_each_set(&hctx->ctx_map, off,
1035 dispatch_rq_from_ctx, &data);
1040 static inline unsigned int queued_to_index(unsigned int queued)
1045 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1048 bool blk_mq_get_driver_tag(struct request *rq)
1050 struct blk_mq_alloc_data data = {
1052 .hctx = rq->mq_hctx,
1053 .flags = BLK_MQ_REQ_NOWAIT,
1054 .cmd_flags = rq->cmd_flags,
1061 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
1062 data.flags |= BLK_MQ_REQ_RESERVED;
1064 shared = blk_mq_tag_busy(data.hctx);
1065 rq->tag = blk_mq_get_tag(&data);
1068 rq->rq_flags |= RQF_MQ_INFLIGHT;
1069 atomic_inc(&data.hctx->nr_active);
1071 data.hctx->tags->rqs[rq->tag] = rq;
1075 return rq->tag != -1;
1078 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1079 int flags, void *key)
1081 struct blk_mq_hw_ctx *hctx;
1083 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1085 spin_lock(&hctx->dispatch_wait_lock);
1086 if (!list_empty(&wait->entry)) {
1087 struct sbitmap_queue *sbq;
1089 list_del_init(&wait->entry);
1090 sbq = &hctx->tags->bitmap_tags;
1091 atomic_dec(&sbq->ws_active);
1093 spin_unlock(&hctx->dispatch_wait_lock);
1095 blk_mq_run_hw_queue(hctx, true);
1100 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1101 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1102 * restart. For both cases, take care to check the condition again after
1103 * marking us as waiting.
1105 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
1108 struct sbitmap_queue *sbq = &hctx->tags->bitmap_tags;
1109 struct wait_queue_head *wq;
1110 wait_queue_entry_t *wait;
1113 if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) {
1114 blk_mq_sched_mark_restart_hctx(hctx);
1117 * It's possible that a tag was freed in the window between the
1118 * allocation failure and adding the hardware queue to the wait
1121 * Don't clear RESTART here, someone else could have set it.
1122 * At most this will cost an extra queue run.
1124 return blk_mq_get_driver_tag(rq);
1127 wait = &hctx->dispatch_wait;
1128 if (!list_empty_careful(&wait->entry))
1131 wq = &bt_wait_ptr(sbq, hctx)->wait;
1133 spin_lock_irq(&wq->lock);
1134 spin_lock(&hctx->dispatch_wait_lock);
1135 if (!list_empty(&wait->entry)) {
1136 spin_unlock(&hctx->dispatch_wait_lock);
1137 spin_unlock_irq(&wq->lock);
1141 atomic_inc(&sbq->ws_active);
1142 wait->flags &= ~WQ_FLAG_EXCLUSIVE;
1143 __add_wait_queue(wq, wait);
1146 * It's possible that a tag was freed in the window between the
1147 * allocation failure and adding the hardware queue to the wait
1150 ret = blk_mq_get_driver_tag(rq);
1152 spin_unlock(&hctx->dispatch_wait_lock);
1153 spin_unlock_irq(&wq->lock);
1158 * We got a tag, remove ourselves from the wait queue to ensure
1159 * someone else gets the wakeup.
1161 list_del_init(&wait->entry);
1162 atomic_dec(&sbq->ws_active);
1163 spin_unlock(&hctx->dispatch_wait_lock);
1164 spin_unlock_irq(&wq->lock);
1169 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1170 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1172 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1173 * - EWMA is one simple way to compute running average value
1174 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1175 * - take 4 as factor for avoiding to get too small(0) result, and this
1176 * factor doesn't matter because EWMA decreases exponentially
1178 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
1182 if (hctx->queue->elevator)
1185 ewma = hctx->dispatch_busy;
1190 ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
1192 ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
1193 ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
1195 hctx->dispatch_busy = ewma;
1198 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1201 * Returns true if we did some work AND can potentially do more.
1203 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
1206 struct blk_mq_hw_ctx *hctx;
1207 struct request *rq, *nxt;
1208 bool no_tag = false;
1210 blk_status_t ret = BLK_STS_OK;
1212 if (list_empty(list))
1215 WARN_ON(!list_is_singular(list) && got_budget);
1218 * Now process all the entries, sending them to the driver.
1220 errors = queued = 0;
1222 struct blk_mq_queue_data bd;
1224 rq = list_first_entry(list, struct request, queuelist);
1227 if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
1230 if (!blk_mq_get_driver_tag(rq)) {
1232 * The initial allocation attempt failed, so we need to
1233 * rerun the hardware queue when a tag is freed. The
1234 * waitqueue takes care of that. If the queue is run
1235 * before we add this entry back on the dispatch list,
1236 * we'll re-run it below.
1238 if (!blk_mq_mark_tag_wait(hctx, rq)) {
1239 blk_mq_put_dispatch_budget(hctx);
1241 * For non-shared tags, the RESTART check
1244 if (hctx->flags & BLK_MQ_F_TAG_SHARED)
1250 list_del_init(&rq->queuelist);
1255 * Flag last if we have no more requests, or if we have more
1256 * but can't assign a driver tag to it.
1258 if (list_empty(list))
1261 nxt = list_first_entry(list, struct request, queuelist);
1262 bd.last = !blk_mq_get_driver_tag(nxt);
1265 ret = q->mq_ops->queue_rq(hctx, &bd);
1266 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
1268 * If an I/O scheduler has been configured and we got a
1269 * driver tag for the next request already, free it
1272 if (!list_empty(list)) {
1273 nxt = list_first_entry(list, struct request, queuelist);
1274 blk_mq_put_driver_tag(nxt);
1276 list_add(&rq->queuelist, list);
1277 __blk_mq_requeue_request(rq);
1281 if (unlikely(ret != BLK_STS_OK)) {
1283 blk_mq_end_request(rq, BLK_STS_IOERR);
1288 } while (!list_empty(list));
1290 hctx->dispatched[queued_to_index(queued)]++;
1293 * Any items that need requeuing? Stuff them into hctx->dispatch,
1294 * that is where we will continue on next queue run.
1296 if (!list_empty(list)) {
1300 * If we didn't flush the entire list, we could have told
1301 * the driver there was more coming, but that turned out to
1304 if (q->mq_ops->commit_rqs)
1305 q->mq_ops->commit_rqs(hctx);
1307 spin_lock(&hctx->lock);
1308 list_splice_init(list, &hctx->dispatch);
1309 spin_unlock(&hctx->lock);
1312 * If SCHED_RESTART was set by the caller of this function and
1313 * it is no longer set that means that it was cleared by another
1314 * thread and hence that a queue rerun is needed.
1316 * If 'no_tag' is set, that means that we failed getting
1317 * a driver tag with an I/O scheduler attached. If our dispatch
1318 * waitqueue is no longer active, ensure that we run the queue
1319 * AFTER adding our entries back to the list.
1321 * If no I/O scheduler has been configured it is possible that
1322 * the hardware queue got stopped and restarted before requests
1323 * were pushed back onto the dispatch list. Rerun the queue to
1324 * avoid starvation. Notes:
1325 * - blk_mq_run_hw_queue() checks whether or not a queue has
1326 * been stopped before rerunning a queue.
1327 * - Some but not all block drivers stop a queue before
1328 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1331 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1332 * bit is set, run queue after a delay to avoid IO stalls
1333 * that could otherwise occur if the queue is idle.
1335 needs_restart = blk_mq_sched_needs_restart(hctx);
1336 if (!needs_restart ||
1337 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1338 blk_mq_run_hw_queue(hctx, true);
1339 else if (needs_restart && (ret == BLK_STS_RESOURCE))
1340 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1342 blk_mq_update_dispatch_busy(hctx, true);
1345 blk_mq_update_dispatch_busy(hctx, false);
1348 * If the host/device is unable to accept more work, inform the
1351 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1354 return (queued + errors) != 0;
1357 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1362 * We should be running this queue from one of the CPUs that
1365 * There are at least two related races now between setting
1366 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1367 * __blk_mq_run_hw_queue():
1369 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1370 * but later it becomes online, then this warning is harmless
1373 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1374 * but later it becomes offline, then the warning can't be
1375 * triggered, and we depend on blk-mq timeout handler to
1376 * handle dispatched requests to this hctx
1378 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1379 cpu_online(hctx->next_cpu)) {
1380 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1381 raw_smp_processor_id(),
1382 cpumask_empty(hctx->cpumask) ? "inactive": "active");
1387 * We can't run the queue inline with ints disabled. Ensure that
1388 * we catch bad users of this early.
1390 WARN_ON_ONCE(in_interrupt());
1392 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1394 hctx_lock(hctx, &srcu_idx);
1395 blk_mq_sched_dispatch_requests(hctx);
1396 hctx_unlock(hctx, srcu_idx);
1399 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1401 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1403 if (cpu >= nr_cpu_ids)
1404 cpu = cpumask_first(hctx->cpumask);
1409 * It'd be great if the workqueue API had a way to pass
1410 * in a mask and had some smarts for more clever placement.
1411 * For now we just round-robin here, switching for every
1412 * BLK_MQ_CPU_WORK_BATCH queued items.
1414 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1417 int next_cpu = hctx->next_cpu;
1419 if (hctx->queue->nr_hw_queues == 1)
1420 return WORK_CPU_UNBOUND;
1422 if (--hctx->next_cpu_batch <= 0) {
1424 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1426 if (next_cpu >= nr_cpu_ids)
1427 next_cpu = blk_mq_first_mapped_cpu(hctx);
1428 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1432 * Do unbound schedule if we can't find a online CPU for this hctx,
1433 * and it should only happen in the path of handling CPU DEAD.
1435 if (!cpu_online(next_cpu)) {
1442 * Make sure to re-select CPU next time once after CPUs
1443 * in hctx->cpumask become online again.
1445 hctx->next_cpu = next_cpu;
1446 hctx->next_cpu_batch = 1;
1447 return WORK_CPU_UNBOUND;
1450 hctx->next_cpu = next_cpu;
1454 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1455 unsigned long msecs)
1457 if (unlikely(blk_mq_hctx_stopped(hctx)))
1460 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1461 int cpu = get_cpu();
1462 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1463 __blk_mq_run_hw_queue(hctx);
1471 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1472 msecs_to_jiffies(msecs));
1475 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1477 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1479 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1481 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1487 * When queue is quiesced, we may be switching io scheduler, or
1488 * updating nr_hw_queues, or other things, and we can't run queue
1489 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1491 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1494 hctx_lock(hctx, &srcu_idx);
1495 need_run = !blk_queue_quiesced(hctx->queue) &&
1496 blk_mq_hctx_has_pending(hctx);
1497 hctx_unlock(hctx, srcu_idx);
1500 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1506 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1508 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1510 struct blk_mq_hw_ctx *hctx;
1513 queue_for_each_hw_ctx(q, hctx, i) {
1514 if (blk_mq_hctx_stopped(hctx))
1517 blk_mq_run_hw_queue(hctx, async);
1520 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1523 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1524 * @q: request queue.
1526 * The caller is responsible for serializing this function against
1527 * blk_mq_{start,stop}_hw_queue().
1529 bool blk_mq_queue_stopped(struct request_queue *q)
1531 struct blk_mq_hw_ctx *hctx;
1534 queue_for_each_hw_ctx(q, hctx, i)
1535 if (blk_mq_hctx_stopped(hctx))
1540 EXPORT_SYMBOL(blk_mq_queue_stopped);
1543 * This function is often used for pausing .queue_rq() by driver when
1544 * there isn't enough resource or some conditions aren't satisfied, and
1545 * BLK_STS_RESOURCE is usually returned.
1547 * We do not guarantee that dispatch can be drained or blocked
1548 * after blk_mq_stop_hw_queue() returns. Please use
1549 * blk_mq_quiesce_queue() for that requirement.
1551 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1553 cancel_delayed_work(&hctx->run_work);
1555 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1557 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1560 * This function is often used for pausing .queue_rq() by driver when
1561 * there isn't enough resource or some conditions aren't satisfied, and
1562 * BLK_STS_RESOURCE is usually returned.
1564 * We do not guarantee that dispatch can be drained or blocked
1565 * after blk_mq_stop_hw_queues() returns. Please use
1566 * blk_mq_quiesce_queue() for that requirement.
1568 void blk_mq_stop_hw_queues(struct request_queue *q)
1570 struct blk_mq_hw_ctx *hctx;
1573 queue_for_each_hw_ctx(q, hctx, i)
1574 blk_mq_stop_hw_queue(hctx);
1576 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1578 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1580 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1582 blk_mq_run_hw_queue(hctx, false);
1584 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1586 void blk_mq_start_hw_queues(struct request_queue *q)
1588 struct blk_mq_hw_ctx *hctx;
1591 queue_for_each_hw_ctx(q, hctx, i)
1592 blk_mq_start_hw_queue(hctx);
1594 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1596 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1598 if (!blk_mq_hctx_stopped(hctx))
1601 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1602 blk_mq_run_hw_queue(hctx, async);
1604 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1606 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1608 struct blk_mq_hw_ctx *hctx;
1611 queue_for_each_hw_ctx(q, hctx, i)
1612 blk_mq_start_stopped_hw_queue(hctx, async);
1614 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1616 static void blk_mq_run_work_fn(struct work_struct *work)
1618 struct blk_mq_hw_ctx *hctx;
1620 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1623 * If we are stopped, don't run the queue.
1625 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1628 __blk_mq_run_hw_queue(hctx);
1631 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1635 struct blk_mq_ctx *ctx = rq->mq_ctx;
1636 enum hctx_type type = hctx->type;
1638 lockdep_assert_held(&ctx->lock);
1640 trace_block_rq_insert(hctx->queue, rq);
1643 list_add(&rq->queuelist, &ctx->rq_lists[type]);
1645 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
1648 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1651 struct blk_mq_ctx *ctx = rq->mq_ctx;
1653 lockdep_assert_held(&ctx->lock);
1655 __blk_mq_insert_req_list(hctx, rq, at_head);
1656 blk_mq_hctx_mark_pending(hctx, ctx);
1660 * Should only be used carefully, when the caller knows we want to
1661 * bypass a potential IO scheduler on the target device.
1663 void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
1665 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1667 spin_lock(&hctx->lock);
1668 list_add_tail(&rq->queuelist, &hctx->dispatch);
1669 spin_unlock(&hctx->lock);
1672 blk_mq_run_hw_queue(hctx, false);
1675 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1676 struct list_head *list)
1680 enum hctx_type type = hctx->type;
1683 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1686 list_for_each_entry(rq, list, queuelist) {
1687 BUG_ON(rq->mq_ctx != ctx);
1688 trace_block_rq_insert(hctx->queue, rq);
1691 spin_lock(&ctx->lock);
1692 list_splice_tail_init(list, &ctx->rq_lists[type]);
1693 blk_mq_hctx_mark_pending(hctx, ctx);
1694 spin_unlock(&ctx->lock);
1697 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
1699 struct request *rqa = container_of(a, struct request, queuelist);
1700 struct request *rqb = container_of(b, struct request, queuelist);
1702 if (rqa->mq_ctx < rqb->mq_ctx)
1704 else if (rqa->mq_ctx > rqb->mq_ctx)
1706 else if (rqa->mq_hctx < rqb->mq_hctx)
1708 else if (rqa->mq_hctx > rqb->mq_hctx)
1711 return blk_rq_pos(rqa) > blk_rq_pos(rqb);
1714 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1716 struct blk_mq_hw_ctx *this_hctx;
1717 struct blk_mq_ctx *this_ctx;
1718 struct request_queue *this_q;
1724 list_splice_init(&plug->mq_list, &list);
1726 if (plug->rq_count > 2 && plug->multiple_queues)
1727 list_sort(NULL, &list, plug_rq_cmp);
1736 while (!list_empty(&list)) {
1737 rq = list_entry_rq(list.next);
1738 list_del_init(&rq->queuelist);
1740 if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx) {
1742 trace_block_unplug(this_q, depth, !from_schedule);
1743 blk_mq_sched_insert_requests(this_hctx, this_ctx,
1749 this_ctx = rq->mq_ctx;
1750 this_hctx = rq->mq_hctx;
1755 list_add_tail(&rq->queuelist, &rq_list);
1759 * If 'this_hctx' is set, we know we have entries to complete
1760 * on 'rq_list'. Do those.
1763 trace_block_unplug(this_q, depth, !from_schedule);
1764 blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
1769 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
1770 unsigned int nr_segs)
1772 if (bio->bi_opf & REQ_RAHEAD)
1773 rq->cmd_flags |= REQ_FAILFAST_MASK;
1775 rq->__sector = bio->bi_iter.bi_sector;
1776 rq->write_hint = bio->bi_write_hint;
1777 blk_rq_bio_prep(rq, bio, nr_segs);
1779 blk_account_io_start(rq, true);
1782 static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1784 blk_qc_t *cookie, bool last)
1786 struct request_queue *q = rq->q;
1787 struct blk_mq_queue_data bd = {
1791 blk_qc_t new_cookie;
1794 new_cookie = request_to_qc_t(hctx, rq);
1797 * For OK queue, we are done. For error, caller may kill it.
1798 * Any other error (busy), just add it to our list as we
1799 * previously would have done.
1801 ret = q->mq_ops->queue_rq(hctx, &bd);
1804 blk_mq_update_dispatch_busy(hctx, false);
1805 *cookie = new_cookie;
1807 case BLK_STS_RESOURCE:
1808 case BLK_STS_DEV_RESOURCE:
1809 blk_mq_update_dispatch_busy(hctx, true);
1810 __blk_mq_requeue_request(rq);
1813 blk_mq_update_dispatch_busy(hctx, false);
1814 *cookie = BLK_QC_T_NONE;
1821 static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1824 bool bypass_insert, bool last)
1826 struct request_queue *q = rq->q;
1827 bool run_queue = true;
1830 * RCU or SRCU read lock is needed before checking quiesced flag.
1832 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1833 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1834 * and avoid driver to try to dispatch again.
1836 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1838 bypass_insert = false;
1842 if (q->elevator && !bypass_insert)
1845 if (!blk_mq_get_dispatch_budget(hctx))
1848 if (!blk_mq_get_driver_tag(rq)) {
1849 blk_mq_put_dispatch_budget(hctx);
1853 return __blk_mq_issue_directly(hctx, rq, cookie, last);
1856 return BLK_STS_RESOURCE;
1858 blk_mq_request_bypass_insert(rq, run_queue);
1862 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1863 struct request *rq, blk_qc_t *cookie)
1868 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1870 hctx_lock(hctx, &srcu_idx);
1872 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
1873 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1874 blk_mq_request_bypass_insert(rq, true);
1875 else if (ret != BLK_STS_OK)
1876 blk_mq_end_request(rq, ret);
1878 hctx_unlock(hctx, srcu_idx);
1881 blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
1885 blk_qc_t unused_cookie;
1886 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1888 hctx_lock(hctx, &srcu_idx);
1889 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
1890 hctx_unlock(hctx, srcu_idx);
1895 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
1896 struct list_head *list)
1898 while (!list_empty(list)) {
1900 struct request *rq = list_first_entry(list, struct request,
1903 list_del_init(&rq->queuelist);
1904 ret = blk_mq_request_issue_directly(rq, list_empty(list));
1905 if (ret != BLK_STS_OK) {
1906 if (ret == BLK_STS_RESOURCE ||
1907 ret == BLK_STS_DEV_RESOURCE) {
1908 blk_mq_request_bypass_insert(rq,
1912 blk_mq_end_request(rq, ret);
1917 * If we didn't flush the entire list, we could have told
1918 * the driver there was more coming, but that turned out to
1921 if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs)
1922 hctx->queue->mq_ops->commit_rqs(hctx);
1925 static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
1927 list_add_tail(&rq->queuelist, &plug->mq_list);
1929 if (!plug->multiple_queues && !list_is_singular(&plug->mq_list)) {
1930 struct request *tmp;
1932 tmp = list_first_entry(&plug->mq_list, struct request,
1934 if (tmp->q != rq->q)
1935 plug->multiple_queues = true;
1939 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1941 const int is_sync = op_is_sync(bio->bi_opf);
1942 const int is_flush_fua = op_is_flush(bio->bi_opf);
1943 struct blk_mq_alloc_data data = { .flags = 0};
1945 struct blk_plug *plug;
1946 struct request *same_queue_rq = NULL;
1947 unsigned int nr_segs;
1950 blk_queue_bounce(q, &bio);
1951 __blk_queue_split(q, &bio, &nr_segs);
1953 if (!bio_integrity_prep(bio))
1954 return BLK_QC_T_NONE;
1956 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1957 blk_attempt_plug_merge(q, bio, nr_segs, &same_queue_rq))
1958 return BLK_QC_T_NONE;
1960 if (blk_mq_sched_bio_merge(q, bio, nr_segs))
1961 return BLK_QC_T_NONE;
1963 rq_qos_throttle(q, bio);
1965 data.cmd_flags = bio->bi_opf;
1966 rq = blk_mq_get_request(q, bio, &data);
1967 if (unlikely(!rq)) {
1968 rq_qos_cleanup(q, bio);
1970 cookie = BLK_QC_T_NONE;
1971 if (bio->bi_opf & REQ_NOWAIT_INLINE)
1972 cookie = BLK_QC_T_EAGAIN;
1973 else if (bio->bi_opf & REQ_NOWAIT)
1974 bio_wouldblock_error(bio);
1978 trace_block_getrq(q, bio, bio->bi_opf);
1980 rq_qos_track(q, rq, bio);
1982 cookie = request_to_qc_t(data.hctx, rq);
1984 blk_mq_bio_to_request(rq, bio, nr_segs);
1986 plug = blk_mq_plug(q, bio);
1987 if (unlikely(is_flush_fua)) {
1988 /* bypass scheduler for flush rq */
1989 blk_insert_flush(rq);
1990 blk_mq_run_hw_queue(data.hctx, true);
1991 } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) {
1993 * Use plugging if we have a ->commit_rqs() hook as well, as
1994 * we know the driver uses bd->last in a smart fashion.
1996 unsigned int request_count = plug->rq_count;
1997 struct request *last = NULL;
2000 trace_block_plug(q);
2002 last = list_entry_rq(plug->mq_list.prev);
2004 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
2005 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
2006 blk_flush_plug_list(plug, false);
2007 trace_block_plug(q);
2010 blk_add_rq_to_plug(plug, rq);
2011 } else if (plug && !blk_queue_nomerges(q)) {
2013 * We do limited plugging. If the bio can be merged, do that.
2014 * Otherwise the existing request in the plug list will be
2015 * issued. So the plug list will have one request at most
2016 * The plug list might get flushed before this. If that happens,
2017 * the plug list is empty, and same_queue_rq is invalid.
2019 if (list_empty(&plug->mq_list))
2020 same_queue_rq = NULL;
2021 if (same_queue_rq) {
2022 list_del_init(&same_queue_rq->queuelist);
2025 blk_add_rq_to_plug(plug, rq);
2026 trace_block_plug(q);
2028 if (same_queue_rq) {
2029 data.hctx = same_queue_rq->mq_hctx;
2030 trace_block_unplug(q, 1, true);
2031 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
2034 } else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
2035 !data.hctx->dispatch_busy)) {
2036 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
2038 blk_mq_sched_insert_request(rq, false, true, true);
2044 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2045 unsigned int hctx_idx)
2049 if (tags->rqs && set->ops->exit_request) {
2052 for (i = 0; i < tags->nr_tags; i++) {
2053 struct request *rq = tags->static_rqs[i];
2057 set->ops->exit_request(set, rq, hctx_idx);
2058 tags->static_rqs[i] = NULL;
2062 while (!list_empty(&tags->page_list)) {
2063 page = list_first_entry(&tags->page_list, struct page, lru);
2064 list_del_init(&page->lru);
2066 * Remove kmemleak object previously allocated in
2067 * blk_mq_alloc_rqs().
2069 kmemleak_free(page_address(page));
2070 __free_pages(page, page->private);
2074 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
2078 kfree(tags->static_rqs);
2079 tags->static_rqs = NULL;
2081 blk_mq_free_tags(tags);
2084 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2085 unsigned int hctx_idx,
2086 unsigned int nr_tags,
2087 unsigned int reserved_tags)
2089 struct blk_mq_tags *tags;
2092 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2093 if (node == NUMA_NO_NODE)
2094 node = set->numa_node;
2096 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
2097 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
2101 tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2102 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2105 blk_mq_free_tags(tags);
2109 tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2110 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2112 if (!tags->static_rqs) {
2114 blk_mq_free_tags(tags);
2121 static size_t order_to_size(unsigned int order)
2123 return (size_t)PAGE_SIZE << order;
2126 static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2127 unsigned int hctx_idx, int node)
2131 if (set->ops->init_request) {
2132 ret = set->ops->init_request(set, rq, hctx_idx, node);
2137 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
2141 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2142 unsigned int hctx_idx, unsigned int depth)
2144 unsigned int i, j, entries_per_page, max_order = 4;
2145 size_t rq_size, left;
2148 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2149 if (node == NUMA_NO_NODE)
2150 node = set->numa_node;
2152 INIT_LIST_HEAD(&tags->page_list);
2155 * rq_size is the size of the request plus driver payload, rounded
2156 * to the cacheline size
2158 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2160 left = rq_size * depth;
2162 for (i = 0; i < depth; ) {
2163 int this_order = max_order;
2168 while (this_order && left < order_to_size(this_order - 1))
2172 page = alloc_pages_node(node,
2173 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2179 if (order_to_size(this_order) < rq_size)
2186 page->private = this_order;
2187 list_add_tail(&page->lru, &tags->page_list);
2189 p = page_address(page);
2191 * Allow kmemleak to scan these pages as they contain pointers
2192 * to additional allocations like via ops->init_request().
2194 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2195 entries_per_page = order_to_size(this_order) / rq_size;
2196 to_do = min(entries_per_page, depth - i);
2197 left -= to_do * rq_size;
2198 for (j = 0; j < to_do; j++) {
2199 struct request *rq = p;
2201 tags->static_rqs[i] = rq;
2202 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2203 tags->static_rqs[i] = NULL;
2214 blk_mq_free_rqs(set, tags, hctx_idx);
2219 * 'cpu' is going away. splice any existing rq_list entries from this
2220 * software queue to the hw queue dispatch list, and ensure that it
2223 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2225 struct blk_mq_hw_ctx *hctx;
2226 struct blk_mq_ctx *ctx;
2228 enum hctx_type type;
2230 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2231 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2234 spin_lock(&ctx->lock);
2235 if (!list_empty(&ctx->rq_lists[type])) {
2236 list_splice_init(&ctx->rq_lists[type], &tmp);
2237 blk_mq_hctx_clear_pending(hctx, ctx);
2239 spin_unlock(&ctx->lock);
2241 if (list_empty(&tmp))
2244 spin_lock(&hctx->lock);
2245 list_splice_tail_init(&tmp, &hctx->dispatch);
2246 spin_unlock(&hctx->lock);
2248 blk_mq_run_hw_queue(hctx, true);
2252 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2254 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2258 /* hctx->ctxs will be freed in queue's release handler */
2259 static void blk_mq_exit_hctx(struct request_queue *q,
2260 struct blk_mq_tag_set *set,
2261 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2263 if (blk_mq_hw_queue_mapped(hctx))
2264 blk_mq_tag_idle(hctx);
2266 if (set->ops->exit_request)
2267 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2269 if (set->ops->exit_hctx)
2270 set->ops->exit_hctx(hctx, hctx_idx);
2272 blk_mq_remove_cpuhp(hctx);
2274 spin_lock(&q->unused_hctx_lock);
2275 list_add(&hctx->hctx_list, &q->unused_hctx_list);
2276 spin_unlock(&q->unused_hctx_lock);
2279 static void blk_mq_exit_hw_queues(struct request_queue *q,
2280 struct blk_mq_tag_set *set, int nr_queue)
2282 struct blk_mq_hw_ctx *hctx;
2285 queue_for_each_hw_ctx(q, hctx, i) {
2288 blk_mq_debugfs_unregister_hctx(hctx);
2289 blk_mq_exit_hctx(q, set, hctx, i);
2293 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2295 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2297 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2298 __alignof__(struct blk_mq_hw_ctx)) !=
2299 sizeof(struct blk_mq_hw_ctx));
2301 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2302 hw_ctx_size += sizeof(struct srcu_struct);
2307 static int blk_mq_init_hctx(struct request_queue *q,
2308 struct blk_mq_tag_set *set,
2309 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2311 hctx->queue_num = hctx_idx;
2313 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2315 hctx->tags = set->tags[hctx_idx];
2317 if (set->ops->init_hctx &&
2318 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2319 goto unregister_cpu_notifier;
2321 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
2327 if (set->ops->exit_hctx)
2328 set->ops->exit_hctx(hctx, hctx_idx);
2329 unregister_cpu_notifier:
2330 blk_mq_remove_cpuhp(hctx);
2334 static struct blk_mq_hw_ctx *
2335 blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
2338 struct blk_mq_hw_ctx *hctx;
2339 gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
2341 hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
2343 goto fail_alloc_hctx;
2345 if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
2348 atomic_set(&hctx->nr_active, 0);
2349 if (node == NUMA_NO_NODE)
2350 node = set->numa_node;
2351 hctx->numa_node = node;
2353 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2354 spin_lock_init(&hctx->lock);
2355 INIT_LIST_HEAD(&hctx->dispatch);
2357 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
2359 INIT_LIST_HEAD(&hctx->hctx_list);
2362 * Allocate space for all possible cpus to avoid allocation at
2365 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2370 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
2375 spin_lock_init(&hctx->dispatch_wait_lock);
2376 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2377 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2379 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size,
2384 if (hctx->flags & BLK_MQ_F_BLOCKING)
2385 init_srcu_struct(hctx->srcu);
2386 blk_mq_hctx_kobj_init(hctx);
2391 sbitmap_free(&hctx->ctx_map);
2395 free_cpumask_var(hctx->cpumask);
2402 static void blk_mq_init_cpu_queues(struct request_queue *q,
2403 unsigned int nr_hw_queues)
2405 struct blk_mq_tag_set *set = q->tag_set;
2408 for_each_possible_cpu(i) {
2409 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2410 struct blk_mq_hw_ctx *hctx;
2414 spin_lock_init(&__ctx->lock);
2415 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
2416 INIT_LIST_HEAD(&__ctx->rq_lists[k]);
2421 * Set local node, IFF we have more than one hw queue. If
2422 * not, we remain on the home node of the device
2424 for (j = 0; j < set->nr_maps; j++) {
2425 hctx = blk_mq_map_queue_type(q, j, i);
2426 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2427 hctx->numa_node = local_memory_node(cpu_to_node(i));
2432 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2436 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2437 set->queue_depth, set->reserved_tags);
2438 if (!set->tags[hctx_idx])
2441 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2446 blk_mq_free_rq_map(set->tags[hctx_idx]);
2447 set->tags[hctx_idx] = NULL;
2451 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2452 unsigned int hctx_idx)
2454 if (set->tags && set->tags[hctx_idx]) {
2455 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2456 blk_mq_free_rq_map(set->tags[hctx_idx]);
2457 set->tags[hctx_idx] = NULL;
2461 static void blk_mq_map_swqueue(struct request_queue *q)
2463 unsigned int i, j, hctx_idx;
2464 struct blk_mq_hw_ctx *hctx;
2465 struct blk_mq_ctx *ctx;
2466 struct blk_mq_tag_set *set = q->tag_set;
2468 queue_for_each_hw_ctx(q, hctx, i) {
2469 cpumask_clear(hctx->cpumask);
2471 hctx->dispatch_from = NULL;
2475 * Map software to hardware queues.
2477 * If the cpu isn't present, the cpu is mapped to first hctx.
2479 for_each_possible_cpu(i) {
2480 hctx_idx = set->map[HCTX_TYPE_DEFAULT].mq_map[i];
2481 /* unmapped hw queue can be remapped after CPU topo changed */
2482 if (!set->tags[hctx_idx] &&
2483 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2485 * If tags initialization fail for some hctx,
2486 * that hctx won't be brought online. In this
2487 * case, remap the current ctx to hctx[0] which
2488 * is guaranteed to always have tags allocated
2490 set->map[HCTX_TYPE_DEFAULT].mq_map[i] = 0;
2493 ctx = per_cpu_ptr(q->queue_ctx, i);
2494 for (j = 0; j < set->nr_maps; j++) {
2495 if (!set->map[j].nr_queues) {
2496 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2497 HCTX_TYPE_DEFAULT, i);
2501 hctx = blk_mq_map_queue_type(q, j, i);
2502 ctx->hctxs[j] = hctx;
2504 * If the CPU is already set in the mask, then we've
2505 * mapped this one already. This can happen if
2506 * devices share queues across queue maps.
2508 if (cpumask_test_cpu(i, hctx->cpumask))
2511 cpumask_set_cpu(i, hctx->cpumask);
2513 ctx->index_hw[hctx->type] = hctx->nr_ctx;
2514 hctx->ctxs[hctx->nr_ctx++] = ctx;
2517 * If the nr_ctx type overflows, we have exceeded the
2518 * amount of sw queues we can support.
2520 BUG_ON(!hctx->nr_ctx);
2523 for (; j < HCTX_MAX_TYPES; j++)
2524 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2525 HCTX_TYPE_DEFAULT, i);
2528 queue_for_each_hw_ctx(q, hctx, i) {
2530 * If no software queues are mapped to this hardware queue,
2531 * disable it and free the request entries.
2533 if (!hctx->nr_ctx) {
2534 /* Never unmap queue 0. We need it as a
2535 * fallback in case of a new remap fails
2538 if (i && set->tags[i])
2539 blk_mq_free_map_and_requests(set, i);
2545 hctx->tags = set->tags[i];
2546 WARN_ON(!hctx->tags);
2549 * Set the map size to the number of mapped software queues.
2550 * This is more accurate and more efficient than looping
2551 * over all possibly mapped software queues.
2553 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2556 * Initialize batch roundrobin counts
2558 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2559 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2564 * Caller needs to ensure that we're either frozen/quiesced, or that
2565 * the queue isn't live yet.
2567 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2569 struct blk_mq_hw_ctx *hctx;
2572 queue_for_each_hw_ctx(q, hctx, i) {
2574 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2576 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2580 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2583 struct request_queue *q;
2585 lockdep_assert_held(&set->tag_list_lock);
2587 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2588 blk_mq_freeze_queue(q);
2589 queue_set_hctx_shared(q, shared);
2590 blk_mq_unfreeze_queue(q);
2594 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2596 struct blk_mq_tag_set *set = q->tag_set;
2598 mutex_lock(&set->tag_list_lock);
2599 list_del_rcu(&q->tag_set_list);
2600 if (list_is_singular(&set->tag_list)) {
2601 /* just transitioned to unshared */
2602 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2603 /* update existing queue */
2604 blk_mq_update_tag_set_depth(set, false);
2606 mutex_unlock(&set->tag_list_lock);
2607 INIT_LIST_HEAD(&q->tag_set_list);
2610 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2611 struct request_queue *q)
2613 mutex_lock(&set->tag_list_lock);
2616 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2618 if (!list_empty(&set->tag_list) &&
2619 !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2620 set->flags |= BLK_MQ_F_TAG_SHARED;
2621 /* update existing queue */
2622 blk_mq_update_tag_set_depth(set, true);
2624 if (set->flags & BLK_MQ_F_TAG_SHARED)
2625 queue_set_hctx_shared(q, true);
2626 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2628 mutex_unlock(&set->tag_list_lock);
2631 /* All allocations will be freed in release handler of q->mq_kobj */
2632 static int blk_mq_alloc_ctxs(struct request_queue *q)
2634 struct blk_mq_ctxs *ctxs;
2637 ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
2641 ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2642 if (!ctxs->queue_ctx)
2645 for_each_possible_cpu(cpu) {
2646 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
2650 q->mq_kobj = &ctxs->kobj;
2651 q->queue_ctx = ctxs->queue_ctx;
2660 * It is the actual release handler for mq, but we do it from
2661 * request queue's release handler for avoiding use-after-free
2662 * and headache because q->mq_kobj shouldn't have been introduced,
2663 * but we can't group ctx/kctx kobj without it.
2665 void blk_mq_release(struct request_queue *q)
2667 struct blk_mq_hw_ctx *hctx, *next;
2670 cancel_delayed_work_sync(&q->requeue_work);
2672 queue_for_each_hw_ctx(q, hctx, i)
2673 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
2675 /* all hctx are in .unused_hctx_list now */
2676 list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
2677 list_del_init(&hctx->hctx_list);
2678 kobject_put(&hctx->kobj);
2681 kfree(q->queue_hw_ctx);
2684 * release .mq_kobj and sw queue's kobject now because
2685 * both share lifetime with request queue.
2687 blk_mq_sysfs_deinit(q);
2690 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2692 struct request_queue *uninit_q, *q;
2694 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2696 return ERR_PTR(-ENOMEM);
2699 * Initialize the queue without an elevator. device_add_disk() will do
2700 * the initialization.
2702 q = blk_mq_init_allocated_queue(set, uninit_q, false);
2704 blk_cleanup_queue(uninit_q);
2708 EXPORT_SYMBOL(blk_mq_init_queue);
2711 * Helper for setting up a queue with mq ops, given queue depth, and
2712 * the passed in mq ops flags.
2714 struct request_queue *blk_mq_init_sq_queue(struct blk_mq_tag_set *set,
2715 const struct blk_mq_ops *ops,
2716 unsigned int queue_depth,
2717 unsigned int set_flags)
2719 struct request_queue *q;
2722 memset(set, 0, sizeof(*set));
2724 set->nr_hw_queues = 1;
2726 set->queue_depth = queue_depth;
2727 set->numa_node = NUMA_NO_NODE;
2728 set->flags = set_flags;
2730 ret = blk_mq_alloc_tag_set(set);
2732 return ERR_PTR(ret);
2734 q = blk_mq_init_queue(set);
2736 blk_mq_free_tag_set(set);
2742 EXPORT_SYMBOL(blk_mq_init_sq_queue);
2744 static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
2745 struct blk_mq_tag_set *set, struct request_queue *q,
2746 int hctx_idx, int node)
2748 struct blk_mq_hw_ctx *hctx = NULL, *tmp;
2750 /* reuse dead hctx first */
2751 spin_lock(&q->unused_hctx_lock);
2752 list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
2753 if (tmp->numa_node == node) {
2759 list_del_init(&hctx->hctx_list);
2760 spin_unlock(&q->unused_hctx_lock);
2763 hctx = blk_mq_alloc_hctx(q, set, node);
2767 if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
2773 kobject_put(&hctx->kobj);
2778 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2779 struct request_queue *q)
2782 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2784 /* protect against switching io scheduler */
2785 mutex_lock(&q->sysfs_lock);
2786 for (i = 0; i < set->nr_hw_queues; i++) {
2788 struct blk_mq_hw_ctx *hctx;
2790 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], i);
2792 * If the hw queue has been mapped to another numa node,
2793 * we need to realloc the hctx. If allocation fails, fallback
2794 * to use the previous one.
2796 if (hctxs[i] && (hctxs[i]->numa_node == node))
2799 hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
2802 blk_mq_exit_hctx(q, set, hctxs[i], i);
2806 pr_warn("Allocate new hctx on node %d fails,\
2807 fallback to previous one on node %d\n",
2808 node, hctxs[i]->numa_node);
2814 * Increasing nr_hw_queues fails. Free the newly allocated
2815 * hctxs and keep the previous q->nr_hw_queues.
2817 if (i != set->nr_hw_queues) {
2818 j = q->nr_hw_queues;
2822 end = q->nr_hw_queues;
2823 q->nr_hw_queues = set->nr_hw_queues;
2826 for (; j < end; j++) {
2827 struct blk_mq_hw_ctx *hctx = hctxs[j];
2831 blk_mq_free_map_and_requests(set, j);
2832 blk_mq_exit_hctx(q, set, hctx, j);
2836 mutex_unlock(&q->sysfs_lock);
2840 * Maximum number of hardware queues we support. For single sets, we'll never
2841 * have more than the CPUs (software queues). For multiple sets, the tag_set
2842 * user may have set ->nr_hw_queues larger.
2844 static unsigned int nr_hw_queues(struct blk_mq_tag_set *set)
2846 if (set->nr_maps == 1)
2849 return max(set->nr_hw_queues, nr_cpu_ids);
2852 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2853 struct request_queue *q,
2856 /* mark the queue as mq asap */
2857 q->mq_ops = set->ops;
2859 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2860 blk_mq_poll_stats_bkt,
2861 BLK_MQ_POLL_STATS_BKTS, q);
2865 if (blk_mq_alloc_ctxs(q))
2868 /* init q->mq_kobj and sw queues' kobjects */
2869 blk_mq_sysfs_init(q);
2871 q->nr_queues = nr_hw_queues(set);
2872 q->queue_hw_ctx = kcalloc_node(q->nr_queues, sizeof(*(q->queue_hw_ctx)),
2873 GFP_KERNEL, set->numa_node);
2874 if (!q->queue_hw_ctx)
2877 INIT_LIST_HEAD(&q->unused_hctx_list);
2878 spin_lock_init(&q->unused_hctx_lock);
2880 blk_mq_realloc_hw_ctxs(set, q);
2881 if (!q->nr_hw_queues)
2884 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2885 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2889 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2890 if (set->nr_maps > HCTX_TYPE_POLL &&
2891 set->map[HCTX_TYPE_POLL].nr_queues)
2892 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
2894 q->sg_reserved_size = INT_MAX;
2896 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2897 INIT_LIST_HEAD(&q->requeue_list);
2898 spin_lock_init(&q->requeue_lock);
2900 blk_queue_make_request(q, blk_mq_make_request);
2903 * Do this after blk_queue_make_request() overrides it...
2905 q->nr_requests = set->queue_depth;
2908 * Default to classic polling
2910 q->poll_nsec = BLK_MQ_POLL_CLASSIC;
2912 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2913 blk_mq_add_queue_tag_set(set, q);
2914 blk_mq_map_swqueue(q);
2917 elevator_init_mq(q);
2922 kfree(q->queue_hw_ctx);
2923 q->nr_hw_queues = 0;
2925 blk_mq_sysfs_deinit(q);
2927 blk_stat_free_callback(q->poll_cb);
2931 return ERR_PTR(-ENOMEM);
2933 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2935 /* tags can _not_ be used after returning from blk_mq_exit_queue */
2936 void blk_mq_exit_queue(struct request_queue *q)
2938 struct blk_mq_tag_set *set = q->tag_set;
2940 blk_mq_del_queue_tag_set(q);
2941 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2944 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2948 for (i = 0; i < set->nr_hw_queues; i++)
2949 if (!__blk_mq_alloc_rq_map(set, i))
2956 blk_mq_free_rq_map(set->tags[i]);
2962 * Allocate the request maps associated with this tag_set. Note that this
2963 * may reduce the depth asked for, if memory is tight. set->queue_depth
2964 * will be updated to reflect the allocated depth.
2966 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2971 depth = set->queue_depth;
2973 err = __blk_mq_alloc_rq_maps(set);
2977 set->queue_depth >>= 1;
2978 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2982 } while (set->queue_depth);
2984 if (!set->queue_depth || err) {
2985 pr_err("blk-mq: failed to allocate request map\n");
2989 if (depth != set->queue_depth)
2990 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2991 depth, set->queue_depth);
2996 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2998 if (set->ops->map_queues && !is_kdump_kernel()) {
3002 * transport .map_queues is usually done in the following
3005 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3006 * mask = get_cpu_mask(queue)
3007 * for_each_cpu(cpu, mask)
3008 * set->map[x].mq_map[cpu] = queue;
3011 * When we need to remap, the table has to be cleared for
3012 * killing stale mapping since one CPU may not be mapped
3015 for (i = 0; i < set->nr_maps; i++)
3016 blk_mq_clear_mq_map(&set->map[i]);
3018 return set->ops->map_queues(set);
3020 BUG_ON(set->nr_maps > 1);
3021 return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3026 * Alloc a tag set to be associated with one or more request queues.
3027 * May fail with EINVAL for various error conditions. May adjust the
3028 * requested depth down, if it's too large. In that case, the set
3029 * value will be stored in set->queue_depth.
3031 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
3035 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
3037 if (!set->nr_hw_queues)
3039 if (!set->queue_depth)
3041 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
3044 if (!set->ops->queue_rq)
3047 if (!set->ops->get_budget ^ !set->ops->put_budget)
3050 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
3051 pr_info("blk-mq: reduced tag depth to %u\n",
3053 set->queue_depth = BLK_MQ_MAX_DEPTH;
3058 else if (set->nr_maps > HCTX_MAX_TYPES)
3062 * If a crashdump is active, then we are potentially in a very
3063 * memory constrained environment. Limit us to 1 queue and
3064 * 64 tags to prevent using too much memory.
3066 if (is_kdump_kernel()) {
3067 set->nr_hw_queues = 1;
3069 set->queue_depth = min(64U, set->queue_depth);
3072 * There is no use for more h/w queues than cpus if we just have
3075 if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
3076 set->nr_hw_queues = nr_cpu_ids;
3078 set->tags = kcalloc_node(nr_hw_queues(set), sizeof(struct blk_mq_tags *),
3079 GFP_KERNEL, set->numa_node);
3084 for (i = 0; i < set->nr_maps; i++) {
3085 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
3086 sizeof(set->map[i].mq_map[0]),
3087 GFP_KERNEL, set->numa_node);
3088 if (!set->map[i].mq_map)
3089 goto out_free_mq_map;
3090 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
3093 ret = blk_mq_update_queue_map(set);
3095 goto out_free_mq_map;
3097 ret = blk_mq_alloc_rq_maps(set);
3099 goto out_free_mq_map;
3101 mutex_init(&set->tag_list_lock);
3102 INIT_LIST_HEAD(&set->tag_list);
3107 for (i = 0; i < set->nr_maps; i++) {
3108 kfree(set->map[i].mq_map);
3109 set->map[i].mq_map = NULL;
3115 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
3117 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
3121 for (i = 0; i < nr_hw_queues(set); i++)
3122 blk_mq_free_map_and_requests(set, i);
3124 for (j = 0; j < set->nr_maps; j++) {
3125 kfree(set->map[j].mq_map);
3126 set->map[j].mq_map = NULL;
3132 EXPORT_SYMBOL(blk_mq_free_tag_set);
3134 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
3136 struct blk_mq_tag_set *set = q->tag_set;
3137 struct blk_mq_hw_ctx *hctx;
3143 if (q->nr_requests == nr)
3146 blk_mq_freeze_queue(q);
3147 blk_mq_quiesce_queue(q);
3150 queue_for_each_hw_ctx(q, hctx, i) {
3154 * If we're using an MQ scheduler, just update the scheduler
3155 * queue depth. This is similar to what the old code would do.
3157 if (!hctx->sched_tags) {
3158 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
3161 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
3166 if (q->elevator && q->elevator->type->ops.depth_updated)
3167 q->elevator->type->ops.depth_updated(hctx);
3171 q->nr_requests = nr;
3173 blk_mq_unquiesce_queue(q);
3174 blk_mq_unfreeze_queue(q);
3180 * request_queue and elevator_type pair.
3181 * It is just used by __blk_mq_update_nr_hw_queues to cache
3182 * the elevator_type associated with a request_queue.
3184 struct blk_mq_qe_pair {
3185 struct list_head node;
3186 struct request_queue *q;
3187 struct elevator_type *type;
3191 * Cache the elevator_type in qe pair list and switch the
3192 * io scheduler to 'none'
3194 static bool blk_mq_elv_switch_none(struct list_head *head,
3195 struct request_queue *q)
3197 struct blk_mq_qe_pair *qe;
3202 qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
3206 INIT_LIST_HEAD(&qe->node);
3208 qe->type = q->elevator->type;
3209 list_add(&qe->node, head);
3211 mutex_lock(&q->sysfs_lock);
3213 * After elevator_switch_mq, the previous elevator_queue will be
3214 * released by elevator_release. The reference of the io scheduler
3215 * module get by elevator_get will also be put. So we need to get
3216 * a reference of the io scheduler module here to prevent it to be
3219 __module_get(qe->type->elevator_owner);
3220 elevator_switch_mq(q, NULL);
3221 mutex_unlock(&q->sysfs_lock);
3226 static void blk_mq_elv_switch_back(struct list_head *head,
3227 struct request_queue *q)
3229 struct blk_mq_qe_pair *qe;
3230 struct elevator_type *t = NULL;
3232 list_for_each_entry(qe, head, node)
3241 list_del(&qe->node);
3244 mutex_lock(&q->sysfs_lock);
3245 elevator_switch_mq(q, t);
3246 mutex_unlock(&q->sysfs_lock);
3249 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
3252 struct request_queue *q;
3254 int prev_nr_hw_queues;
3256 lockdep_assert_held(&set->tag_list_lock);
3258 if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
3259 nr_hw_queues = nr_cpu_ids;
3260 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
3263 list_for_each_entry(q, &set->tag_list, tag_set_list)
3264 blk_mq_freeze_queue(q);
3266 * Sync with blk_mq_queue_tag_busy_iter.
3270 * Switch IO scheduler to 'none', cleaning up the data associated
3271 * with the previous scheduler. We will switch back once we are done
3272 * updating the new sw to hw queue mappings.
3274 list_for_each_entry(q, &set->tag_list, tag_set_list)
3275 if (!blk_mq_elv_switch_none(&head, q))
3278 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3279 blk_mq_debugfs_unregister_hctxs(q);
3280 blk_mq_sysfs_unregister(q);
3283 prev_nr_hw_queues = set->nr_hw_queues;
3284 set->nr_hw_queues = nr_hw_queues;
3285 blk_mq_update_queue_map(set);
3287 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3288 blk_mq_realloc_hw_ctxs(set, q);
3289 if (q->nr_hw_queues != set->nr_hw_queues) {
3290 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3291 nr_hw_queues, prev_nr_hw_queues);
3292 set->nr_hw_queues = prev_nr_hw_queues;
3293 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3296 blk_mq_map_swqueue(q);
3299 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3300 blk_mq_sysfs_register(q);
3301 blk_mq_debugfs_register_hctxs(q);
3305 list_for_each_entry(q, &set->tag_list, tag_set_list)
3306 blk_mq_elv_switch_back(&head, q);
3308 list_for_each_entry(q, &set->tag_list, tag_set_list)
3309 blk_mq_unfreeze_queue(q);
3312 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
3314 mutex_lock(&set->tag_list_lock);
3315 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
3316 mutex_unlock(&set->tag_list_lock);
3318 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
3320 /* Enable polling stats and return whether they were already enabled. */
3321 static bool blk_poll_stats_enable(struct request_queue *q)
3323 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3324 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
3326 blk_stat_add_callback(q, q->poll_cb);
3330 static void blk_mq_poll_stats_start(struct request_queue *q)
3333 * We don't arm the callback if polling stats are not enabled or the
3334 * callback is already active.
3336 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3337 blk_stat_is_active(q->poll_cb))
3340 blk_stat_activate_msecs(q->poll_cb, 100);
3343 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3345 struct request_queue *q = cb->data;
3348 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3349 if (cb->stat[bucket].nr_samples)
3350 q->poll_stat[bucket] = cb->stat[bucket];
3354 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3355 struct blk_mq_hw_ctx *hctx,
3358 unsigned long ret = 0;
3362 * If stats collection isn't on, don't sleep but turn it on for
3365 if (!blk_poll_stats_enable(q))
3369 * As an optimistic guess, use half of the mean service time
3370 * for this type of request. We can (and should) make this smarter.
3371 * For instance, if the completion latencies are tight, we can
3372 * get closer than just half the mean. This is especially
3373 * important on devices where the completion latencies are longer
3374 * than ~10 usec. We do use the stats for the relevant IO size
3375 * if available which does lead to better estimates.
3377 bucket = blk_mq_poll_stats_bkt(rq);
3381 if (q->poll_stat[bucket].nr_samples)
3382 ret = (q->poll_stat[bucket].mean + 1) / 2;
3387 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3388 struct blk_mq_hw_ctx *hctx,
3391 struct hrtimer_sleeper hs;
3392 enum hrtimer_mode mode;
3396 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3400 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3402 * 0: use half of prev avg
3403 * >0: use this specific value
3405 if (q->poll_nsec > 0)
3406 nsecs = q->poll_nsec;
3408 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
3413 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3416 * This will be replaced with the stats tracking code, using
3417 * 'avg_completion_time / 2' as the pre-sleep target.
3421 mode = HRTIMER_MODE_REL;
3422 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
3423 hrtimer_set_expires(&hs.timer, kt);
3425 hrtimer_init_sleeper(&hs, current);
3427 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3429 set_current_state(TASK_UNINTERRUPTIBLE);
3430 hrtimer_start_expires(&hs.timer, mode);
3433 hrtimer_cancel(&hs.timer);
3434 mode = HRTIMER_MODE_ABS;
3435 } while (hs.task && !signal_pending(current));
3437 __set_current_state(TASK_RUNNING);
3438 destroy_hrtimer_on_stack(&hs.timer);
3442 static bool blk_mq_poll_hybrid(struct request_queue *q,
3443 struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
3447 if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
3450 if (!blk_qc_t_is_internal(cookie))
3451 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3453 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3455 * With scheduling, if the request has completed, we'll
3456 * get a NULL return here, as we clear the sched tag when
3457 * that happens. The request still remains valid, like always,
3458 * so we should be safe with just the NULL check.
3464 return blk_mq_poll_hybrid_sleep(q, hctx, rq);
3468 * blk_poll - poll for IO completions
3470 * @cookie: cookie passed back at IO submission time
3471 * @spin: whether to spin for completions
3474 * Poll for completions on the passed in queue. Returns number of
3475 * completed entries found. If @spin is true, then blk_poll will continue
3476 * looping until at least one completion is found, unless the task is
3477 * otherwise marked running (or we need to reschedule).
3479 int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
3481 struct blk_mq_hw_ctx *hctx;
3484 if (!blk_qc_t_valid(cookie) ||
3485 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3489 blk_flush_plug_list(current->plug, false);
3491 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3494 * If we sleep, have the caller restart the poll loop to reset
3495 * the state. Like for the other success return cases, the
3496 * caller is responsible for checking if the IO completed. If
3497 * the IO isn't complete, we'll get called again and will go
3498 * straight to the busy poll loop.
3500 if (blk_mq_poll_hybrid(q, hctx, cookie))
3503 hctx->poll_considered++;
3505 state = current->state;
3509 hctx->poll_invoked++;
3511 ret = q->mq_ops->poll(hctx);
3513 hctx->poll_success++;
3514 __set_current_state(TASK_RUNNING);
3518 if (signal_pending_state(state, current))
3519 __set_current_state(TASK_RUNNING);
3521 if (current->state == TASK_RUNNING)
3523 if (ret < 0 || !spin)
3526 } while (!need_resched());
3528 __set_current_state(TASK_RUNNING);
3531 EXPORT_SYMBOL_GPL(blk_poll);
3533 unsigned int blk_mq_rq_cpu(struct request *rq)
3535 return rq->mq_ctx->cpu;
3537 EXPORT_SYMBOL(blk_mq_rq_cpu);
3539 static int __init blk_mq_init(void)
3541 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3542 blk_mq_hctx_notify_dead);
3545 subsys_initcall(blk_mq_init);