2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/delay.h>
24 #include <linux/crash_dump.h>
25 #include <linux/prefetch.h>
27 #include <trace/events/block.h>
29 #include <linux/blk-mq.h>
32 #include "blk-mq-tag.h"
35 #include "blk-mq-sched.h"
37 static DEFINE_MUTEX(all_q_mutex);
38 static LIST_HEAD(all_q_list);
41 * Check if any of the ctx's have pending work in this hardware queue
43 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
45 return sbitmap_any_bit_set(&hctx->ctx_map) ||
46 !list_empty_careful(&hctx->dispatch) ||
47 blk_mq_sched_has_work(hctx);
51 * Mark this ctx as having pending work in this hardware queue
53 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
54 struct blk_mq_ctx *ctx)
56 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
57 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
60 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
61 struct blk_mq_ctx *ctx)
63 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
66 void blk_mq_freeze_queue_start(struct request_queue *q)
70 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
71 if (freeze_depth == 1) {
72 percpu_ref_kill(&q->q_usage_counter);
73 blk_mq_run_hw_queues(q, false);
76 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
78 static void blk_mq_freeze_queue_wait(struct request_queue *q)
80 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
84 * Guarantee no request is in use, so we can change any data structure of
85 * the queue afterward.
87 void blk_freeze_queue(struct request_queue *q)
90 * In the !blk_mq case we are only calling this to kill the
91 * q_usage_counter, otherwise this increases the freeze depth
92 * and waits for it to return to zero. For this reason there is
93 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
94 * exported to drivers as the only user for unfreeze is blk_mq.
96 blk_mq_freeze_queue_start(q);
97 blk_mq_freeze_queue_wait(q);
100 void blk_mq_freeze_queue(struct request_queue *q)
103 * ...just an alias to keep freeze and unfreeze actions balanced
104 * in the blk_mq_* namespace
108 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
110 void blk_mq_unfreeze_queue(struct request_queue *q)
114 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
115 WARN_ON_ONCE(freeze_depth < 0);
117 percpu_ref_reinit(&q->q_usage_counter);
118 wake_up_all(&q->mq_freeze_wq);
121 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
124 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
127 * Note: this function does not prevent that the struct request end_io()
128 * callback function is invoked. Additionally, it is not prevented that
129 * new queue_rq() calls occur unless the queue has been stopped first.
131 void blk_mq_quiesce_queue(struct request_queue *q)
133 struct blk_mq_hw_ctx *hctx;
137 blk_mq_stop_hw_queues(q);
139 queue_for_each_hw_ctx(q, hctx, i) {
140 if (hctx->flags & BLK_MQ_F_BLOCKING)
141 synchronize_srcu(&hctx->queue_rq_srcu);
148 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
150 void blk_mq_wake_waiters(struct request_queue *q)
152 struct blk_mq_hw_ctx *hctx;
155 queue_for_each_hw_ctx(q, hctx, i)
156 if (blk_mq_hw_queue_mapped(hctx))
157 blk_mq_tag_wakeup_all(hctx->tags, true);
160 * If we are called because the queue has now been marked as
161 * dying, we need to ensure that processes currently waiting on
162 * the queue are notified as well.
164 wake_up_all(&q->mq_freeze_wq);
167 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
169 return blk_mq_has_free_tags(hctx->tags);
171 EXPORT_SYMBOL(blk_mq_can_queue);
173 void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
174 struct request *rq, unsigned int op)
176 INIT_LIST_HEAD(&rq->queuelist);
177 /* csd/requeue_work/fifo_time is initialized before use */
181 if (blk_queue_io_stat(q))
182 rq->rq_flags |= RQF_IO_STAT;
183 /* do not touch atomic flags, it needs atomic ops against the timer */
185 INIT_HLIST_NODE(&rq->hash);
186 RB_CLEAR_NODE(&rq->rb_node);
189 rq->start_time = jiffies;
190 #ifdef CONFIG_BLK_CGROUP
192 set_start_time_ns(rq);
193 rq->io_start_time_ns = 0;
195 rq->nr_phys_segments = 0;
196 #if defined(CONFIG_BLK_DEV_INTEGRITY)
197 rq->nr_integrity_segments = 0;
200 /* tag was already set */
204 INIT_LIST_HEAD(&rq->timeout_list);
208 rq->end_io_data = NULL;
211 ctx->rq_dispatched[op_is_sync(op)]++;
213 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
215 struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
221 tag = blk_mq_get_tag(data);
222 if (tag != BLK_MQ_TAG_FAIL) {
223 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
225 rq = tags->static_rqs[tag];
227 if (data->flags & BLK_MQ_REQ_INTERNAL) {
229 rq->internal_tag = tag;
231 if (blk_mq_tag_busy(data->hctx)) {
232 rq->rq_flags = RQF_MQ_INFLIGHT;
233 atomic_inc(&data->hctx->nr_active);
236 rq->internal_tag = -1;
239 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
245 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
247 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
250 struct blk_mq_alloc_data alloc_data = { .flags = flags };
254 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
258 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
260 blk_mq_put_ctx(alloc_data.ctx);
264 return ERR_PTR(-EWOULDBLOCK);
267 rq->__sector = (sector_t) -1;
268 rq->bio = rq->biotail = NULL;
271 EXPORT_SYMBOL(blk_mq_alloc_request);
273 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
274 unsigned int flags, unsigned int hctx_idx)
276 struct blk_mq_hw_ctx *hctx;
277 struct blk_mq_ctx *ctx;
279 struct blk_mq_alloc_data alloc_data;
283 * If the tag allocator sleeps we could get an allocation for a
284 * different hardware context. No need to complicate the low level
285 * allocator for this for the rare use case of a command tied to
288 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
289 return ERR_PTR(-EINVAL);
291 if (hctx_idx >= q->nr_hw_queues)
292 return ERR_PTR(-EIO);
294 ret = blk_queue_enter(q, true);
299 * Check if the hardware context is actually mapped to anything.
300 * If not tell the caller that it should skip this queue.
302 hctx = q->queue_hw_ctx[hctx_idx];
303 if (!blk_mq_hw_queue_mapped(hctx)) {
307 ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
309 blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
310 rq = __blk_mq_alloc_request(&alloc_data, rw);
322 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
324 void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
327 const int sched_tag = rq->internal_tag;
328 struct request_queue *q = rq->q;
330 if (rq->rq_flags & RQF_MQ_INFLIGHT)
331 atomic_dec(&hctx->nr_active);
333 wbt_done(q->rq_wb, &rq->issue_stat);
336 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
337 clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
339 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
341 blk_mq_sched_completed_request(hctx, rq);
342 blk_mq_sched_restart_queues(hctx);
346 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
349 struct blk_mq_ctx *ctx = rq->mq_ctx;
351 ctx->rq_completed[rq_is_sync(rq)]++;
352 __blk_mq_finish_request(hctx, ctx, rq);
355 void blk_mq_finish_request(struct request *rq)
357 blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
360 void blk_mq_free_request(struct request *rq)
362 blk_mq_sched_put_request(rq);
364 EXPORT_SYMBOL_GPL(blk_mq_free_request);
366 inline void __blk_mq_end_request(struct request *rq, int error)
368 blk_account_io_done(rq);
371 wbt_done(rq->q->rq_wb, &rq->issue_stat);
372 rq->end_io(rq, error);
374 if (unlikely(blk_bidi_rq(rq)))
375 blk_mq_free_request(rq->next_rq);
376 blk_mq_free_request(rq);
379 EXPORT_SYMBOL(__blk_mq_end_request);
381 void blk_mq_end_request(struct request *rq, int error)
383 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
385 __blk_mq_end_request(rq, error);
387 EXPORT_SYMBOL(blk_mq_end_request);
389 static void __blk_mq_complete_request_remote(void *data)
391 struct request *rq = data;
393 rq->q->softirq_done_fn(rq);
396 static void blk_mq_ipi_complete_request(struct request *rq)
398 struct blk_mq_ctx *ctx = rq->mq_ctx;
402 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
403 rq->q->softirq_done_fn(rq);
408 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
409 shared = cpus_share_cache(cpu, ctx->cpu);
411 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
412 rq->csd.func = __blk_mq_complete_request_remote;
415 smp_call_function_single_async(ctx->cpu, &rq->csd);
417 rq->q->softirq_done_fn(rq);
422 static void blk_mq_stat_add(struct request *rq)
424 if (rq->rq_flags & RQF_STATS) {
426 * We could rq->mq_ctx here, but there's less of a risk
427 * of races if we have the completion event add the stats
428 * to the local software queue.
430 struct blk_mq_ctx *ctx;
432 ctx = __blk_mq_get_ctx(rq->q, raw_smp_processor_id());
433 blk_stat_add(&ctx->stat[rq_data_dir(rq)], rq);
437 static void __blk_mq_complete_request(struct request *rq)
439 struct request_queue *q = rq->q;
443 if (!q->softirq_done_fn)
444 blk_mq_end_request(rq, rq->errors);
446 blk_mq_ipi_complete_request(rq);
450 * blk_mq_complete_request - end I/O on a request
451 * @rq: the request being processed
454 * Ends all I/O on a request. It does not handle partial completions.
455 * The actual completion happens out-of-order, through a IPI handler.
457 void blk_mq_complete_request(struct request *rq, int error)
459 struct request_queue *q = rq->q;
461 if (unlikely(blk_should_fake_timeout(q)))
463 if (!blk_mark_rq_complete(rq)) {
465 __blk_mq_complete_request(rq);
468 EXPORT_SYMBOL(blk_mq_complete_request);
470 int blk_mq_request_started(struct request *rq)
472 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
474 EXPORT_SYMBOL_GPL(blk_mq_request_started);
476 void blk_mq_start_request(struct request *rq)
478 struct request_queue *q = rq->q;
480 blk_mq_sched_started_request(rq);
482 trace_block_rq_issue(q, rq);
484 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
485 blk_stat_set_issue_time(&rq->issue_stat);
486 rq->rq_flags |= RQF_STATS;
487 wbt_issue(q->rq_wb, &rq->issue_stat);
493 * Ensure that ->deadline is visible before set the started
494 * flag and clear the completed flag.
496 smp_mb__before_atomic();
499 * Mark us as started and clear complete. Complete might have been
500 * set if requeue raced with timeout, which then marked it as
501 * complete. So be sure to clear complete again when we start
502 * the request, otherwise we'll ignore the completion event.
504 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
505 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
506 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
507 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
509 if (q->dma_drain_size && blk_rq_bytes(rq)) {
511 * Make sure space for the drain appears. We know we can do
512 * this because max_hw_segments has been adjusted to be one
513 * fewer than the device can handle.
515 rq->nr_phys_segments++;
518 EXPORT_SYMBOL(blk_mq_start_request);
520 static void __blk_mq_requeue_request(struct request *rq)
522 struct request_queue *q = rq->q;
524 trace_block_rq_requeue(q, rq);
525 wbt_requeue(q->rq_wb, &rq->issue_stat);
526 blk_mq_sched_requeue_request(rq);
528 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
529 if (q->dma_drain_size && blk_rq_bytes(rq))
530 rq->nr_phys_segments--;
534 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
536 __blk_mq_requeue_request(rq);
538 BUG_ON(blk_queued_rq(rq));
539 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
541 EXPORT_SYMBOL(blk_mq_requeue_request);
543 static void blk_mq_requeue_work(struct work_struct *work)
545 struct request_queue *q =
546 container_of(work, struct request_queue, requeue_work.work);
548 struct request *rq, *next;
551 spin_lock_irqsave(&q->requeue_lock, flags);
552 list_splice_init(&q->requeue_list, &rq_list);
553 spin_unlock_irqrestore(&q->requeue_lock, flags);
555 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
556 if (!(rq->rq_flags & RQF_SOFTBARRIER))
559 rq->rq_flags &= ~RQF_SOFTBARRIER;
560 list_del_init(&rq->queuelist);
561 blk_mq_sched_insert_request(rq, true, false, false, true);
564 while (!list_empty(&rq_list)) {
565 rq = list_entry(rq_list.next, struct request, queuelist);
566 list_del_init(&rq->queuelist);
567 blk_mq_sched_insert_request(rq, false, false, false, true);
570 blk_mq_run_hw_queues(q, false);
573 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
574 bool kick_requeue_list)
576 struct request_queue *q = rq->q;
580 * We abuse this flag that is otherwise used by the I/O scheduler to
581 * request head insertation from the workqueue.
583 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
585 spin_lock_irqsave(&q->requeue_lock, flags);
587 rq->rq_flags |= RQF_SOFTBARRIER;
588 list_add(&rq->queuelist, &q->requeue_list);
590 list_add_tail(&rq->queuelist, &q->requeue_list);
592 spin_unlock_irqrestore(&q->requeue_lock, flags);
594 if (kick_requeue_list)
595 blk_mq_kick_requeue_list(q);
597 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
599 void blk_mq_kick_requeue_list(struct request_queue *q)
601 kblockd_schedule_delayed_work(&q->requeue_work, 0);
603 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
605 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
608 kblockd_schedule_delayed_work(&q->requeue_work,
609 msecs_to_jiffies(msecs));
611 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
613 void blk_mq_abort_requeue_list(struct request_queue *q)
618 spin_lock_irqsave(&q->requeue_lock, flags);
619 list_splice_init(&q->requeue_list, &rq_list);
620 spin_unlock_irqrestore(&q->requeue_lock, flags);
622 while (!list_empty(&rq_list)) {
625 rq = list_first_entry(&rq_list, struct request, queuelist);
626 list_del_init(&rq->queuelist);
628 blk_mq_end_request(rq, rq->errors);
631 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
633 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
635 if (tag < tags->nr_tags) {
636 prefetch(tags->rqs[tag]);
637 return tags->rqs[tag];
642 EXPORT_SYMBOL(blk_mq_tag_to_rq);
644 struct blk_mq_timeout_data {
646 unsigned int next_set;
649 void blk_mq_rq_timed_out(struct request *req, bool reserved)
651 const struct blk_mq_ops *ops = req->q->mq_ops;
652 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
655 * We know that complete is set at this point. If STARTED isn't set
656 * anymore, then the request isn't active and the "timeout" should
657 * just be ignored. This can happen due to the bitflag ordering.
658 * Timeout first checks if STARTED is set, and if it is, assumes
659 * the request is active. But if we race with completion, then
660 * we both flags will get cleared. So check here again, and ignore
661 * a timeout event with a request that isn't active.
663 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
667 ret = ops->timeout(req, reserved);
671 __blk_mq_complete_request(req);
673 case BLK_EH_RESET_TIMER:
675 blk_clear_rq_complete(req);
677 case BLK_EH_NOT_HANDLED:
680 printk(KERN_ERR "block: bad eh return: %d\n", ret);
685 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
686 struct request *rq, void *priv, bool reserved)
688 struct blk_mq_timeout_data *data = priv;
690 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
692 * If a request wasn't started before the queue was
693 * marked dying, kill it here or it'll go unnoticed.
695 if (unlikely(blk_queue_dying(rq->q))) {
697 blk_mq_end_request(rq, rq->errors);
702 if (time_after_eq(jiffies, rq->deadline)) {
703 if (!blk_mark_rq_complete(rq))
704 blk_mq_rq_timed_out(rq, reserved);
705 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
706 data->next = rq->deadline;
711 static void blk_mq_timeout_work(struct work_struct *work)
713 struct request_queue *q =
714 container_of(work, struct request_queue, timeout_work);
715 struct blk_mq_timeout_data data = {
721 /* A deadlock might occur if a request is stuck requiring a
722 * timeout at the same time a queue freeze is waiting
723 * completion, since the timeout code would not be able to
724 * acquire the queue reference here.
726 * That's why we don't use blk_queue_enter here; instead, we use
727 * percpu_ref_tryget directly, because we need to be able to
728 * obtain a reference even in the short window between the queue
729 * starting to freeze, by dropping the first reference in
730 * blk_mq_freeze_queue_start, and the moment the last request is
731 * consumed, marked by the instant q_usage_counter reaches
734 if (!percpu_ref_tryget(&q->q_usage_counter))
737 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
740 data.next = blk_rq_timeout(round_jiffies_up(data.next));
741 mod_timer(&q->timeout, data.next);
743 struct blk_mq_hw_ctx *hctx;
745 queue_for_each_hw_ctx(q, hctx, i) {
746 /* the hctx may be unmapped, so check it here */
747 if (blk_mq_hw_queue_mapped(hctx))
748 blk_mq_tag_idle(hctx);
755 * Reverse check our software queue for entries that we could potentially
756 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
757 * too much time checking for merges.
759 static bool blk_mq_attempt_merge(struct request_queue *q,
760 struct blk_mq_ctx *ctx, struct bio *bio)
765 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
771 if (!blk_rq_merge_ok(rq, bio))
774 switch (blk_try_merge(rq, bio)) {
775 case ELEVATOR_BACK_MERGE:
776 if (blk_mq_sched_allow_merge(q, rq, bio))
777 merged = bio_attempt_back_merge(q, rq, bio);
779 case ELEVATOR_FRONT_MERGE:
780 if (blk_mq_sched_allow_merge(q, rq, bio))
781 merged = bio_attempt_front_merge(q, rq, bio);
783 case ELEVATOR_DISCARD_MERGE:
784 merged = bio_attempt_discard_merge(q, rq, bio);
798 struct flush_busy_ctx_data {
799 struct blk_mq_hw_ctx *hctx;
800 struct list_head *list;
803 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
805 struct flush_busy_ctx_data *flush_data = data;
806 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
807 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
809 sbitmap_clear_bit(sb, bitnr);
810 spin_lock(&ctx->lock);
811 list_splice_tail_init(&ctx->rq_list, flush_data->list);
812 spin_unlock(&ctx->lock);
817 * Process software queues that have been marked busy, splicing them
818 * to the for-dispatch
820 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
822 struct flush_busy_ctx_data data = {
827 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
829 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
831 static inline unsigned int queued_to_index(unsigned int queued)
836 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
839 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
842 struct blk_mq_alloc_data data = {
844 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
845 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
855 rq->tag = blk_mq_get_tag(&data);
857 if (blk_mq_tag_busy(data.hctx)) {
858 rq->rq_flags |= RQF_MQ_INFLIGHT;
859 atomic_inc(&data.hctx->nr_active);
861 data.hctx->tags->rqs[rq->tag] = rq;
868 static void blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
871 if (rq->tag == -1 || rq->internal_tag == -1)
874 blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
877 if (rq->rq_flags & RQF_MQ_INFLIGHT) {
878 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
879 atomic_dec(&hctx->nr_active);
884 * If we fail getting a driver tag because all the driver tags are already
885 * assigned and on the dispatch list, BUT the first entry does not have a
886 * tag, then we could deadlock. For that case, move entries with assigned
887 * driver tags to the front, leaving the set of tagged requests in the
888 * same order, and the untagged set in the same order.
890 static bool reorder_tags_to_front(struct list_head *list)
892 struct request *rq, *tmp, *first = NULL;
894 list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
898 list_move(&rq->queuelist, list);
904 return first != NULL;
907 static int blk_mq_dispatch_wake(wait_queue_t *wait, unsigned mode, int flags,
910 struct blk_mq_hw_ctx *hctx;
912 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
914 list_del(&wait->task_list);
915 clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
916 blk_mq_run_hw_queue(hctx, true);
920 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
922 struct sbq_wait_state *ws;
925 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
926 * The thread which wins the race to grab this bit adds the hardware
927 * queue to the wait queue.
929 if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
930 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
933 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
934 ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
937 * As soon as this returns, it's no longer safe to fiddle with
938 * hctx->dispatch_wait, since a completion can wake up the wait queue
939 * and unlock the bit.
941 add_wait_queue(&ws->wait, &hctx->dispatch_wait);
945 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
947 struct request_queue *q = hctx->queue;
949 LIST_HEAD(driver_list);
950 struct list_head *dptr;
951 int queued, ret = BLK_MQ_RQ_QUEUE_OK;
954 * Start off with dptr being NULL, so we start the first request
955 * immediately, even if we have more pending.
960 * Now process all the entries, sending them to the driver.
963 while (!list_empty(list)) {
964 struct blk_mq_queue_data bd;
966 rq = list_first_entry(list, struct request, queuelist);
967 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
968 if (!queued && reorder_tags_to_front(list))
972 * The initial allocation attempt failed, so we need to
973 * rerun the hardware queue when a tag is freed.
975 if (blk_mq_dispatch_wait_add(hctx)) {
977 * It's possible that a tag was freed in the
978 * window between the allocation failure and
979 * adding the hardware queue to the wait queue.
981 if (!blk_mq_get_driver_tag(rq, &hctx, false))
988 list_del_init(&rq->queuelist);
992 bd.last = list_empty(list);
994 ret = q->mq_ops->queue_rq(hctx, &bd);
996 case BLK_MQ_RQ_QUEUE_OK:
999 case BLK_MQ_RQ_QUEUE_BUSY:
1000 blk_mq_put_driver_tag(hctx, rq);
1001 list_add(&rq->queuelist, list);
1002 __blk_mq_requeue_request(rq);
1005 pr_err("blk-mq: bad return on queue: %d\n", ret);
1006 case BLK_MQ_RQ_QUEUE_ERROR:
1008 blk_mq_end_request(rq, rq->errors);
1012 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
1016 * We've done the first request. If we have more than 1
1017 * left in the list, set dptr to defer issue.
1019 if (!dptr && list->next != list->prev)
1020 dptr = &driver_list;
1023 hctx->dispatched[queued_to_index(queued)]++;
1026 * Any items that need requeuing? Stuff them into hctx->dispatch,
1027 * that is where we will continue on next queue run.
1029 if (!list_empty(list)) {
1030 spin_lock(&hctx->lock);
1031 list_splice_init(list, &hctx->dispatch);
1032 spin_unlock(&hctx->lock);
1035 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1036 * it's possible the queue is stopped and restarted again
1037 * before this. Queue restart will dispatch requests. And since
1038 * requests in rq_list aren't added into hctx->dispatch yet,
1039 * the requests in rq_list might get lost.
1041 * blk_mq_run_hw_queue() already checks the STOPPED bit
1043 * If RESTART or TAG_WAITING is set, then let completion restart
1044 * the queue instead of potentially looping here.
1046 if (!blk_mq_sched_needs_restart(hctx) &&
1047 !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1048 blk_mq_run_hw_queue(hctx, true);
1054 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1058 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1059 cpu_online(hctx->next_cpu));
1061 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1063 blk_mq_sched_dispatch_requests(hctx);
1066 srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1067 blk_mq_sched_dispatch_requests(hctx);
1068 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1073 * It'd be great if the workqueue API had a way to pass
1074 * in a mask and had some smarts for more clever placement.
1075 * For now we just round-robin here, switching for every
1076 * BLK_MQ_CPU_WORK_BATCH queued items.
1078 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1080 if (hctx->queue->nr_hw_queues == 1)
1081 return WORK_CPU_UNBOUND;
1083 if (--hctx->next_cpu_batch <= 0) {
1086 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1087 if (next_cpu >= nr_cpu_ids)
1088 next_cpu = cpumask_first(hctx->cpumask);
1090 hctx->next_cpu = next_cpu;
1091 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1094 return hctx->next_cpu;
1097 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1099 if (unlikely(blk_mq_hctx_stopped(hctx) ||
1100 !blk_mq_hw_queue_mapped(hctx)))
1103 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1104 int cpu = get_cpu();
1105 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1106 __blk_mq_run_hw_queue(hctx);
1114 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
1117 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1119 struct blk_mq_hw_ctx *hctx;
1122 queue_for_each_hw_ctx(q, hctx, i) {
1123 if (!blk_mq_hctx_has_pending(hctx) ||
1124 blk_mq_hctx_stopped(hctx))
1127 blk_mq_run_hw_queue(hctx, async);
1130 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1133 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1134 * @q: request queue.
1136 * The caller is responsible for serializing this function against
1137 * blk_mq_{start,stop}_hw_queue().
1139 bool blk_mq_queue_stopped(struct request_queue *q)
1141 struct blk_mq_hw_ctx *hctx;
1144 queue_for_each_hw_ctx(q, hctx, i)
1145 if (blk_mq_hctx_stopped(hctx))
1150 EXPORT_SYMBOL(blk_mq_queue_stopped);
1152 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1154 cancel_work(&hctx->run_work);
1155 cancel_delayed_work(&hctx->delay_work);
1156 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1158 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1160 void blk_mq_stop_hw_queues(struct request_queue *q)
1162 struct blk_mq_hw_ctx *hctx;
1165 queue_for_each_hw_ctx(q, hctx, i)
1166 blk_mq_stop_hw_queue(hctx);
1168 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1170 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1172 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1174 blk_mq_run_hw_queue(hctx, false);
1176 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1178 void blk_mq_start_hw_queues(struct request_queue *q)
1180 struct blk_mq_hw_ctx *hctx;
1183 queue_for_each_hw_ctx(q, hctx, i)
1184 blk_mq_start_hw_queue(hctx);
1186 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1188 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1190 if (!blk_mq_hctx_stopped(hctx))
1193 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1194 blk_mq_run_hw_queue(hctx, async);
1196 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1198 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1200 struct blk_mq_hw_ctx *hctx;
1203 queue_for_each_hw_ctx(q, hctx, i)
1204 blk_mq_start_stopped_hw_queue(hctx, async);
1206 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1208 static void blk_mq_run_work_fn(struct work_struct *work)
1210 struct blk_mq_hw_ctx *hctx;
1212 hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
1214 __blk_mq_run_hw_queue(hctx);
1217 static void blk_mq_delay_work_fn(struct work_struct *work)
1219 struct blk_mq_hw_ctx *hctx;
1221 hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1223 if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1224 __blk_mq_run_hw_queue(hctx);
1227 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1229 if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1232 blk_mq_stop_hw_queue(hctx);
1233 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1234 &hctx->delay_work, msecs_to_jiffies(msecs));
1236 EXPORT_SYMBOL(blk_mq_delay_queue);
1238 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1242 struct blk_mq_ctx *ctx = rq->mq_ctx;
1244 trace_block_rq_insert(hctx->queue, rq);
1247 list_add(&rq->queuelist, &ctx->rq_list);
1249 list_add_tail(&rq->queuelist, &ctx->rq_list);
1252 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1255 struct blk_mq_ctx *ctx = rq->mq_ctx;
1257 __blk_mq_insert_req_list(hctx, rq, at_head);
1258 blk_mq_hctx_mark_pending(hctx, ctx);
1261 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1262 struct list_head *list)
1266 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1269 spin_lock(&ctx->lock);
1270 while (!list_empty(list)) {
1273 rq = list_first_entry(list, struct request, queuelist);
1274 BUG_ON(rq->mq_ctx != ctx);
1275 list_del_init(&rq->queuelist);
1276 __blk_mq_insert_req_list(hctx, rq, false);
1278 blk_mq_hctx_mark_pending(hctx, ctx);
1279 spin_unlock(&ctx->lock);
1282 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1284 struct request *rqa = container_of(a, struct request, queuelist);
1285 struct request *rqb = container_of(b, struct request, queuelist);
1287 return !(rqa->mq_ctx < rqb->mq_ctx ||
1288 (rqa->mq_ctx == rqb->mq_ctx &&
1289 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1292 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1294 struct blk_mq_ctx *this_ctx;
1295 struct request_queue *this_q;
1298 LIST_HEAD(ctx_list);
1301 list_splice_init(&plug->mq_list, &list);
1303 list_sort(NULL, &list, plug_ctx_cmp);
1309 while (!list_empty(&list)) {
1310 rq = list_entry_rq(list.next);
1311 list_del_init(&rq->queuelist);
1313 if (rq->mq_ctx != this_ctx) {
1315 trace_block_unplug(this_q, depth, from_schedule);
1316 blk_mq_sched_insert_requests(this_q, this_ctx,
1321 this_ctx = rq->mq_ctx;
1327 list_add_tail(&rq->queuelist, &ctx_list);
1331 * If 'this_ctx' is set, we know we have entries to complete
1332 * on 'ctx_list'. Do those.
1335 trace_block_unplug(this_q, depth, from_schedule);
1336 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1341 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1343 init_request_from_bio(rq, bio);
1345 blk_account_io_start(rq, true);
1348 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1350 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1351 !blk_queue_nomerges(hctx->queue);
1354 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1355 struct blk_mq_ctx *ctx,
1356 struct request *rq, struct bio *bio)
1358 if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1359 blk_mq_bio_to_request(rq, bio);
1360 spin_lock(&ctx->lock);
1362 __blk_mq_insert_request(hctx, rq, false);
1363 spin_unlock(&ctx->lock);
1366 struct request_queue *q = hctx->queue;
1368 spin_lock(&ctx->lock);
1369 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1370 blk_mq_bio_to_request(rq, bio);
1374 spin_unlock(&ctx->lock);
1375 __blk_mq_finish_request(hctx, ctx, rq);
1380 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1383 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1385 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1388 static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
1390 struct request_queue *q = rq->q;
1391 struct blk_mq_queue_data bd = {
1396 struct blk_mq_hw_ctx *hctx;
1397 blk_qc_t new_cookie;
1403 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1406 new_cookie = request_to_qc_t(hctx, rq);
1409 * For OK queue, we are done. For error, kill it. Any other
1410 * error (busy), just add it to our list as we previously
1413 ret = q->mq_ops->queue_rq(hctx, &bd);
1414 if (ret == BLK_MQ_RQ_QUEUE_OK) {
1415 *cookie = new_cookie;
1419 __blk_mq_requeue_request(rq);
1421 if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1422 *cookie = BLK_QC_T_NONE;
1424 blk_mq_end_request(rq, rq->errors);
1429 blk_mq_sched_insert_request(rq, false, true, true, false);
1433 * Multiple hardware queue variant. This will not use per-process plugs,
1434 * but will attempt to bypass the hctx queueing if we can go straight to
1435 * hardware for SYNC IO.
1437 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1439 const int is_sync = op_is_sync(bio->bi_opf);
1440 const int is_flush_fua = op_is_flush(bio->bi_opf);
1441 struct blk_mq_alloc_data data = { .flags = 0 };
1443 unsigned int request_count = 0, srcu_idx;
1444 struct blk_plug *plug;
1445 struct request *same_queue_rq = NULL;
1447 unsigned int wb_acct;
1449 blk_queue_bounce(q, &bio);
1451 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1453 return BLK_QC_T_NONE;
1456 blk_queue_split(q, &bio, q->bio_split);
1458 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1459 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1460 return BLK_QC_T_NONE;
1462 if (blk_mq_sched_bio_merge(q, bio))
1463 return BLK_QC_T_NONE;
1465 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1467 trace_block_getrq(q, bio, bio->bi_opf);
1469 rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1470 if (unlikely(!rq)) {
1471 __wbt_done(q->rq_wb, wb_acct);
1472 return BLK_QC_T_NONE;
1475 wbt_track(&rq->issue_stat, wb_acct);
1477 cookie = request_to_qc_t(data.hctx, rq);
1479 if (unlikely(is_flush_fua)) {
1482 blk_mq_bio_to_request(rq, bio);
1483 blk_insert_flush(rq);
1487 plug = current->plug;
1489 * If the driver supports defer issued based on 'last', then
1490 * queue it up like normal since we can potentially save some
1493 if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1494 !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1495 struct request *old_rq = NULL;
1497 blk_mq_bio_to_request(rq, bio);
1500 * We do limited plugging. If the bio can be merged, do that.
1501 * Otherwise the existing request in the plug list will be
1502 * issued. So the plug list will have one request at most
1506 * The plug list might get flushed before this. If that
1507 * happens, same_queue_rq is invalid and plug list is
1510 if (same_queue_rq && !list_empty(&plug->mq_list)) {
1511 old_rq = same_queue_rq;
1512 list_del_init(&old_rq->queuelist);
1514 list_add_tail(&rq->queuelist, &plug->mq_list);
1515 } else /* is_sync */
1517 blk_mq_put_ctx(data.ctx);
1521 if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
1523 blk_mq_try_issue_directly(old_rq, &cookie);
1526 srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
1527 blk_mq_try_issue_directly(old_rq, &cookie);
1528 srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
1535 blk_mq_put_ctx(data.ctx);
1536 blk_mq_bio_to_request(rq, bio);
1537 blk_mq_sched_insert_request(rq, false, true,
1538 !is_sync || is_flush_fua, true);
1541 if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1543 * For a SYNC request, send it to the hardware immediately. For
1544 * an ASYNC request, just ensure that we run it later on. The
1545 * latter allows for merging opportunities and more efficient
1549 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1551 blk_mq_put_ctx(data.ctx);
1557 * Single hardware queue variant. This will attempt to use any per-process
1558 * plug for merging and IO deferral.
1560 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1562 const int is_sync = op_is_sync(bio->bi_opf);
1563 const int is_flush_fua = op_is_flush(bio->bi_opf);
1564 struct blk_plug *plug;
1565 unsigned int request_count = 0;
1566 struct blk_mq_alloc_data data = { .flags = 0 };
1569 unsigned int wb_acct;
1571 blk_queue_bounce(q, &bio);
1573 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1575 return BLK_QC_T_NONE;
1578 blk_queue_split(q, &bio, q->bio_split);
1580 if (!is_flush_fua && !blk_queue_nomerges(q)) {
1581 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1582 return BLK_QC_T_NONE;
1584 request_count = blk_plug_queued_count(q);
1586 if (blk_mq_sched_bio_merge(q, bio))
1587 return BLK_QC_T_NONE;
1589 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1591 trace_block_getrq(q, bio, bio->bi_opf);
1593 rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1594 if (unlikely(!rq)) {
1595 __wbt_done(q->rq_wb, wb_acct);
1596 return BLK_QC_T_NONE;
1599 wbt_track(&rq->issue_stat, wb_acct);
1601 cookie = request_to_qc_t(data.hctx, rq);
1603 if (unlikely(is_flush_fua)) {
1606 blk_mq_bio_to_request(rq, bio);
1607 blk_insert_flush(rq);
1612 * A task plug currently exists. Since this is completely lockless,
1613 * utilize that to temporarily store requests until the task is
1614 * either done or scheduled away.
1616 plug = current->plug;
1618 struct request *last = NULL;
1620 blk_mq_bio_to_request(rq, bio);
1623 * @request_count may become stale because of schedule
1624 * out, so check the list again.
1626 if (list_empty(&plug->mq_list))
1629 trace_block_plug(q);
1631 last = list_entry_rq(plug->mq_list.prev);
1633 blk_mq_put_ctx(data.ctx);
1635 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1636 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1637 blk_flush_plug_list(plug, false);
1638 trace_block_plug(q);
1641 list_add_tail(&rq->queuelist, &plug->mq_list);
1647 blk_mq_put_ctx(data.ctx);
1648 blk_mq_bio_to_request(rq, bio);
1649 blk_mq_sched_insert_request(rq, false, true,
1650 !is_sync || is_flush_fua, true);
1653 if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1655 * For a SYNC request, send it to the hardware immediately. For
1656 * an ASYNC request, just ensure that we run it later on. The
1657 * latter allows for merging opportunities and more efficient
1661 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1664 blk_mq_put_ctx(data.ctx);
1669 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1670 unsigned int hctx_idx)
1674 if (tags->rqs && set->ops->exit_request) {
1677 for (i = 0; i < tags->nr_tags; i++) {
1678 struct request *rq = tags->static_rqs[i];
1682 set->ops->exit_request(set->driver_data, rq,
1684 tags->static_rqs[i] = NULL;
1688 while (!list_empty(&tags->page_list)) {
1689 page = list_first_entry(&tags->page_list, struct page, lru);
1690 list_del_init(&page->lru);
1692 * Remove kmemleak object previously allocated in
1693 * blk_mq_init_rq_map().
1695 kmemleak_free(page_address(page));
1696 __free_pages(page, page->private);
1700 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1704 kfree(tags->static_rqs);
1705 tags->static_rqs = NULL;
1707 blk_mq_free_tags(tags);
1710 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1711 unsigned int hctx_idx,
1712 unsigned int nr_tags,
1713 unsigned int reserved_tags)
1715 struct blk_mq_tags *tags;
1717 tags = blk_mq_init_tags(nr_tags, reserved_tags,
1719 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1723 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1724 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1727 blk_mq_free_tags(tags);
1731 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1732 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1734 if (!tags->static_rqs) {
1736 blk_mq_free_tags(tags);
1743 static size_t order_to_size(unsigned int order)
1745 return (size_t)PAGE_SIZE << order;
1748 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1749 unsigned int hctx_idx, unsigned int depth)
1751 unsigned int i, j, entries_per_page, max_order = 4;
1752 size_t rq_size, left;
1754 INIT_LIST_HEAD(&tags->page_list);
1757 * rq_size is the size of the request plus driver payload, rounded
1758 * to the cacheline size
1760 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1762 left = rq_size * depth;
1764 for (i = 0; i < depth; ) {
1765 int this_order = max_order;
1770 while (this_order && left < order_to_size(this_order - 1))
1774 page = alloc_pages_node(set->numa_node,
1775 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1781 if (order_to_size(this_order) < rq_size)
1788 page->private = this_order;
1789 list_add_tail(&page->lru, &tags->page_list);
1791 p = page_address(page);
1793 * Allow kmemleak to scan these pages as they contain pointers
1794 * to additional allocations like via ops->init_request().
1796 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1797 entries_per_page = order_to_size(this_order) / rq_size;
1798 to_do = min(entries_per_page, depth - i);
1799 left -= to_do * rq_size;
1800 for (j = 0; j < to_do; j++) {
1801 struct request *rq = p;
1803 tags->static_rqs[i] = rq;
1804 if (set->ops->init_request) {
1805 if (set->ops->init_request(set->driver_data,
1808 tags->static_rqs[i] = NULL;
1820 blk_mq_free_rqs(set, tags, hctx_idx);
1825 * 'cpu' is going away. splice any existing rq_list entries from this
1826 * software queue to the hw queue dispatch list, and ensure that it
1829 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1831 struct blk_mq_hw_ctx *hctx;
1832 struct blk_mq_ctx *ctx;
1835 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1836 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1838 spin_lock(&ctx->lock);
1839 if (!list_empty(&ctx->rq_list)) {
1840 list_splice_init(&ctx->rq_list, &tmp);
1841 blk_mq_hctx_clear_pending(hctx, ctx);
1843 spin_unlock(&ctx->lock);
1845 if (list_empty(&tmp))
1848 spin_lock(&hctx->lock);
1849 list_splice_tail_init(&tmp, &hctx->dispatch);
1850 spin_unlock(&hctx->lock);
1852 blk_mq_run_hw_queue(hctx, true);
1856 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1858 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1862 /* hctx->ctxs will be freed in queue's release handler */
1863 static void blk_mq_exit_hctx(struct request_queue *q,
1864 struct blk_mq_tag_set *set,
1865 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1867 unsigned flush_start_tag = set->queue_depth;
1869 blk_mq_tag_idle(hctx);
1871 if (set->ops->exit_request)
1872 set->ops->exit_request(set->driver_data,
1873 hctx->fq->flush_rq, hctx_idx,
1874 flush_start_tag + hctx_idx);
1876 if (set->ops->exit_hctx)
1877 set->ops->exit_hctx(hctx, hctx_idx);
1879 if (hctx->flags & BLK_MQ_F_BLOCKING)
1880 cleanup_srcu_struct(&hctx->queue_rq_srcu);
1882 blk_mq_remove_cpuhp(hctx);
1883 blk_free_flush_queue(hctx->fq);
1884 sbitmap_free(&hctx->ctx_map);
1887 static void blk_mq_exit_hw_queues(struct request_queue *q,
1888 struct blk_mq_tag_set *set, int nr_queue)
1890 struct blk_mq_hw_ctx *hctx;
1893 queue_for_each_hw_ctx(q, hctx, i) {
1896 blk_mq_exit_hctx(q, set, hctx, i);
1900 static void blk_mq_free_hw_queues(struct request_queue *q,
1901 struct blk_mq_tag_set *set)
1903 struct blk_mq_hw_ctx *hctx;
1906 queue_for_each_hw_ctx(q, hctx, i)
1907 free_cpumask_var(hctx->cpumask);
1910 static int blk_mq_init_hctx(struct request_queue *q,
1911 struct blk_mq_tag_set *set,
1912 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1915 unsigned flush_start_tag = set->queue_depth;
1917 node = hctx->numa_node;
1918 if (node == NUMA_NO_NODE)
1919 node = hctx->numa_node = set->numa_node;
1921 INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1922 INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1923 spin_lock_init(&hctx->lock);
1924 INIT_LIST_HEAD(&hctx->dispatch);
1926 hctx->queue_num = hctx_idx;
1927 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1929 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1931 hctx->tags = set->tags[hctx_idx];
1934 * Allocate space for all possible cpus to avoid allocation at
1937 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1940 goto unregister_cpu_notifier;
1942 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1948 if (set->ops->init_hctx &&
1949 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1952 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1956 if (set->ops->init_request &&
1957 set->ops->init_request(set->driver_data,
1958 hctx->fq->flush_rq, hctx_idx,
1959 flush_start_tag + hctx_idx, node))
1962 if (hctx->flags & BLK_MQ_F_BLOCKING)
1963 init_srcu_struct(&hctx->queue_rq_srcu);
1970 if (set->ops->exit_hctx)
1971 set->ops->exit_hctx(hctx, hctx_idx);
1973 sbitmap_free(&hctx->ctx_map);
1976 unregister_cpu_notifier:
1977 blk_mq_remove_cpuhp(hctx);
1981 static void blk_mq_init_cpu_queues(struct request_queue *q,
1982 unsigned int nr_hw_queues)
1986 for_each_possible_cpu(i) {
1987 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1988 struct blk_mq_hw_ctx *hctx;
1990 memset(__ctx, 0, sizeof(*__ctx));
1992 spin_lock_init(&__ctx->lock);
1993 INIT_LIST_HEAD(&__ctx->rq_list);
1995 blk_stat_init(&__ctx->stat[BLK_STAT_READ]);
1996 blk_stat_init(&__ctx->stat[BLK_STAT_WRITE]);
1998 /* If the cpu isn't online, the cpu is mapped to first hctx */
2002 hctx = blk_mq_map_queue(q, i);
2005 * Set local node, IFF we have more than one hw queue. If
2006 * not, we remain on the home node of the device
2008 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2009 hctx->numa_node = local_memory_node(cpu_to_node(i));
2013 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2017 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2018 set->queue_depth, set->reserved_tags);
2019 if (!set->tags[hctx_idx])
2022 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2027 blk_mq_free_rq_map(set->tags[hctx_idx]);
2028 set->tags[hctx_idx] = NULL;
2032 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2033 unsigned int hctx_idx)
2035 if (set->tags[hctx_idx]) {
2036 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2037 blk_mq_free_rq_map(set->tags[hctx_idx]);
2038 set->tags[hctx_idx] = NULL;
2042 static void blk_mq_map_swqueue(struct request_queue *q,
2043 const struct cpumask *online_mask)
2045 unsigned int i, hctx_idx;
2046 struct blk_mq_hw_ctx *hctx;
2047 struct blk_mq_ctx *ctx;
2048 struct blk_mq_tag_set *set = q->tag_set;
2051 * Avoid others reading imcomplete hctx->cpumask through sysfs
2053 mutex_lock(&q->sysfs_lock);
2055 queue_for_each_hw_ctx(q, hctx, i) {
2056 cpumask_clear(hctx->cpumask);
2061 * Map software to hardware queues
2063 for_each_possible_cpu(i) {
2064 /* If the cpu isn't online, the cpu is mapped to first hctx */
2065 if (!cpumask_test_cpu(i, online_mask))
2068 hctx_idx = q->mq_map[i];
2069 /* unmapped hw queue can be remapped after CPU topo changed */
2070 if (!set->tags[hctx_idx] &&
2071 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2073 * If tags initialization fail for some hctx,
2074 * that hctx won't be brought online. In this
2075 * case, remap the current ctx to hctx[0] which
2076 * is guaranteed to always have tags allocated
2081 ctx = per_cpu_ptr(q->queue_ctx, i);
2082 hctx = blk_mq_map_queue(q, i);
2084 cpumask_set_cpu(i, hctx->cpumask);
2085 ctx->index_hw = hctx->nr_ctx;
2086 hctx->ctxs[hctx->nr_ctx++] = ctx;
2089 mutex_unlock(&q->sysfs_lock);
2091 queue_for_each_hw_ctx(q, hctx, i) {
2093 * If no software queues are mapped to this hardware queue,
2094 * disable it and free the request entries.
2096 if (!hctx->nr_ctx) {
2097 /* Never unmap queue 0. We need it as a
2098 * fallback in case of a new remap fails
2101 if (i && set->tags[i])
2102 blk_mq_free_map_and_requests(set, i);
2108 hctx->tags = set->tags[i];
2109 WARN_ON(!hctx->tags);
2112 * Set the map size to the number of mapped software queues.
2113 * This is more accurate and more efficient than looping
2114 * over all possibly mapped software queues.
2116 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2119 * Initialize batch roundrobin counts
2121 hctx->next_cpu = cpumask_first(hctx->cpumask);
2122 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2126 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2128 struct blk_mq_hw_ctx *hctx;
2131 queue_for_each_hw_ctx(q, hctx, i) {
2133 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2135 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2139 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
2141 struct request_queue *q;
2143 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2144 blk_mq_freeze_queue(q);
2145 queue_set_hctx_shared(q, shared);
2146 blk_mq_unfreeze_queue(q);
2150 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2152 struct blk_mq_tag_set *set = q->tag_set;
2154 mutex_lock(&set->tag_list_lock);
2155 list_del_init(&q->tag_set_list);
2156 if (list_is_singular(&set->tag_list)) {
2157 /* just transitioned to unshared */
2158 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2159 /* update existing queue */
2160 blk_mq_update_tag_set_depth(set, false);
2162 mutex_unlock(&set->tag_list_lock);
2165 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2166 struct request_queue *q)
2170 mutex_lock(&set->tag_list_lock);
2172 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2173 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2174 set->flags |= BLK_MQ_F_TAG_SHARED;
2175 /* update existing queue */
2176 blk_mq_update_tag_set_depth(set, true);
2178 if (set->flags & BLK_MQ_F_TAG_SHARED)
2179 queue_set_hctx_shared(q, true);
2180 list_add_tail(&q->tag_set_list, &set->tag_list);
2182 mutex_unlock(&set->tag_list_lock);
2186 * It is the actual release handler for mq, but we do it from
2187 * request queue's release handler for avoiding use-after-free
2188 * and headache because q->mq_kobj shouldn't have been introduced,
2189 * but we can't group ctx/kctx kobj without it.
2191 void blk_mq_release(struct request_queue *q)
2193 struct blk_mq_hw_ctx *hctx;
2196 blk_mq_sched_teardown(q);
2198 /* hctx kobj stays in hctx */
2199 queue_for_each_hw_ctx(q, hctx, i) {
2208 kfree(q->queue_hw_ctx);
2210 /* ctx kobj stays in queue_ctx */
2211 free_percpu(q->queue_ctx);
2214 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2216 struct request_queue *uninit_q, *q;
2218 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2220 return ERR_PTR(-ENOMEM);
2222 q = blk_mq_init_allocated_queue(set, uninit_q);
2224 blk_cleanup_queue(uninit_q);
2228 EXPORT_SYMBOL(blk_mq_init_queue);
2230 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2231 struct request_queue *q)
2234 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2236 blk_mq_sysfs_unregister(q);
2237 for (i = 0; i < set->nr_hw_queues; i++) {
2243 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2244 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
2249 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2256 atomic_set(&hctxs[i]->nr_active, 0);
2257 hctxs[i]->numa_node = node;
2258 hctxs[i]->queue_num = i;
2260 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2261 free_cpumask_var(hctxs[i]->cpumask);
2266 blk_mq_hctx_kobj_init(hctxs[i]);
2268 for (j = i; j < q->nr_hw_queues; j++) {
2269 struct blk_mq_hw_ctx *hctx = hctxs[j];
2273 blk_mq_free_map_and_requests(set, j);
2274 blk_mq_exit_hctx(q, set, hctx, j);
2275 free_cpumask_var(hctx->cpumask);
2276 kobject_put(&hctx->kobj);
2283 q->nr_hw_queues = i;
2284 blk_mq_sysfs_register(q);
2287 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2288 struct request_queue *q)
2290 /* mark the queue as mq asap */
2291 q->mq_ops = set->ops;
2293 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2297 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2298 GFP_KERNEL, set->numa_node);
2299 if (!q->queue_hw_ctx)
2302 q->mq_map = set->mq_map;
2304 blk_mq_realloc_hw_ctxs(set, q);
2305 if (!q->nr_hw_queues)
2308 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2309 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2311 q->nr_queues = nr_cpu_ids;
2313 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2315 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2316 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2318 q->sg_reserved_size = INT_MAX;
2320 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2321 INIT_LIST_HEAD(&q->requeue_list);
2322 spin_lock_init(&q->requeue_lock);
2324 if (q->nr_hw_queues > 1)
2325 blk_queue_make_request(q, blk_mq_make_request);
2327 blk_queue_make_request(q, blk_sq_make_request);
2330 * Do this after blk_queue_make_request() overrides it...
2332 q->nr_requests = set->queue_depth;
2335 * Default to classic polling
2339 if (set->ops->complete)
2340 blk_queue_softirq_done(q, set->ops->complete);
2342 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2345 mutex_lock(&all_q_mutex);
2347 list_add_tail(&q->all_q_node, &all_q_list);
2348 blk_mq_add_queue_tag_set(set, q);
2349 blk_mq_map_swqueue(q, cpu_online_mask);
2351 mutex_unlock(&all_q_mutex);
2354 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2357 ret = blk_mq_sched_init(q);
2359 return ERR_PTR(ret);
2365 kfree(q->queue_hw_ctx);
2367 free_percpu(q->queue_ctx);
2370 return ERR_PTR(-ENOMEM);
2372 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2374 void blk_mq_free_queue(struct request_queue *q)
2376 struct blk_mq_tag_set *set = q->tag_set;
2378 mutex_lock(&all_q_mutex);
2379 list_del_init(&q->all_q_node);
2380 mutex_unlock(&all_q_mutex);
2384 blk_mq_del_queue_tag_set(q);
2386 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2387 blk_mq_free_hw_queues(q, set);
2390 /* Basically redo blk_mq_init_queue with queue frozen */
2391 static void blk_mq_queue_reinit(struct request_queue *q,
2392 const struct cpumask *online_mask)
2394 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2396 blk_mq_sysfs_unregister(q);
2399 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2400 * we should change hctx numa_node according to new topology (this
2401 * involves free and re-allocate memory, worthy doing?)
2404 blk_mq_map_swqueue(q, online_mask);
2406 blk_mq_sysfs_register(q);
2410 * New online cpumask which is going to be set in this hotplug event.
2411 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2412 * one-by-one and dynamically allocating this could result in a failure.
2414 static struct cpumask cpuhp_online_new;
2416 static void blk_mq_queue_reinit_work(void)
2418 struct request_queue *q;
2420 mutex_lock(&all_q_mutex);
2422 * We need to freeze and reinit all existing queues. Freezing
2423 * involves synchronous wait for an RCU grace period and doing it
2424 * one by one may take a long time. Start freezing all queues in
2425 * one swoop and then wait for the completions so that freezing can
2426 * take place in parallel.
2428 list_for_each_entry(q, &all_q_list, all_q_node)
2429 blk_mq_freeze_queue_start(q);
2430 list_for_each_entry(q, &all_q_list, all_q_node)
2431 blk_mq_freeze_queue_wait(q);
2433 list_for_each_entry(q, &all_q_list, all_q_node)
2434 blk_mq_queue_reinit(q, &cpuhp_online_new);
2436 list_for_each_entry(q, &all_q_list, all_q_node)
2437 blk_mq_unfreeze_queue(q);
2439 mutex_unlock(&all_q_mutex);
2442 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2444 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2445 blk_mq_queue_reinit_work();
2450 * Before hotadded cpu starts handling requests, new mappings must be
2451 * established. Otherwise, these requests in hw queue might never be
2454 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2455 * for CPU0, and ctx1 for CPU1).
2457 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2458 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2460 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2461 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2462 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2465 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2467 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2468 cpumask_set_cpu(cpu, &cpuhp_online_new);
2469 blk_mq_queue_reinit_work();
2473 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2477 for (i = 0; i < set->nr_hw_queues; i++)
2478 if (!__blk_mq_alloc_rq_map(set, i))
2485 blk_mq_free_rq_map(set->tags[i]);
2491 * Allocate the request maps associated with this tag_set. Note that this
2492 * may reduce the depth asked for, if memory is tight. set->queue_depth
2493 * will be updated to reflect the allocated depth.
2495 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2500 depth = set->queue_depth;
2502 err = __blk_mq_alloc_rq_maps(set);
2506 set->queue_depth >>= 1;
2507 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2511 } while (set->queue_depth);
2513 if (!set->queue_depth || err) {
2514 pr_err("blk-mq: failed to allocate request map\n");
2518 if (depth != set->queue_depth)
2519 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2520 depth, set->queue_depth);
2526 * Alloc a tag set to be associated with one or more request queues.
2527 * May fail with EINVAL for various error conditions. May adjust the
2528 * requested depth down, if if it too large. In that case, the set
2529 * value will be stored in set->queue_depth.
2531 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2535 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2537 if (!set->nr_hw_queues)
2539 if (!set->queue_depth)
2541 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2544 if (!set->ops->queue_rq)
2547 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2548 pr_info("blk-mq: reduced tag depth to %u\n",
2550 set->queue_depth = BLK_MQ_MAX_DEPTH;
2554 * If a crashdump is active, then we are potentially in a very
2555 * memory constrained environment. Limit us to 1 queue and
2556 * 64 tags to prevent using too much memory.
2558 if (is_kdump_kernel()) {
2559 set->nr_hw_queues = 1;
2560 set->queue_depth = min(64U, set->queue_depth);
2563 * There is no use for more h/w queues than cpus.
2565 if (set->nr_hw_queues > nr_cpu_ids)
2566 set->nr_hw_queues = nr_cpu_ids;
2568 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2569 GFP_KERNEL, set->numa_node);
2574 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2575 GFP_KERNEL, set->numa_node);
2579 if (set->ops->map_queues)
2580 ret = set->ops->map_queues(set);
2582 ret = blk_mq_map_queues(set);
2584 goto out_free_mq_map;
2586 ret = blk_mq_alloc_rq_maps(set);
2588 goto out_free_mq_map;
2590 mutex_init(&set->tag_list_lock);
2591 INIT_LIST_HEAD(&set->tag_list);
2603 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2605 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2609 for (i = 0; i < nr_cpu_ids; i++)
2610 blk_mq_free_map_and_requests(set, i);
2618 EXPORT_SYMBOL(blk_mq_free_tag_set);
2620 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2622 struct blk_mq_tag_set *set = q->tag_set;
2623 struct blk_mq_hw_ctx *hctx;
2629 blk_mq_freeze_queue(q);
2630 blk_mq_quiesce_queue(q);
2633 queue_for_each_hw_ctx(q, hctx, i) {
2637 * If we're using an MQ scheduler, just update the scheduler
2638 * queue depth. This is similar to what the old code would do.
2640 if (!hctx->sched_tags) {
2641 ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2642 min(nr, set->queue_depth),
2645 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2653 q->nr_requests = nr;
2655 blk_mq_unfreeze_queue(q);
2656 blk_mq_start_stopped_hw_queues(q, true);
2661 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2663 struct request_queue *q;
2665 if (nr_hw_queues > nr_cpu_ids)
2666 nr_hw_queues = nr_cpu_ids;
2667 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2670 list_for_each_entry(q, &set->tag_list, tag_set_list)
2671 blk_mq_freeze_queue(q);
2673 set->nr_hw_queues = nr_hw_queues;
2674 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2675 blk_mq_realloc_hw_ctxs(set, q);
2678 * Manually set the make_request_fn as blk_queue_make_request
2679 * resets a lot of the queue settings.
2681 if (q->nr_hw_queues > 1)
2682 q->make_request_fn = blk_mq_make_request;
2684 q->make_request_fn = blk_sq_make_request;
2686 blk_mq_queue_reinit(q, cpu_online_mask);
2689 list_for_each_entry(q, &set->tag_list, tag_set_list)
2690 blk_mq_unfreeze_queue(q);
2692 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2694 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2695 struct blk_mq_hw_ctx *hctx,
2698 struct blk_rq_stat stat[2];
2699 unsigned long ret = 0;
2702 * If stats collection isn't on, don't sleep but turn it on for
2705 if (!blk_stat_enable(q))
2709 * We don't have to do this once per IO, should optimize this
2710 * to just use the current window of stats until it changes
2712 memset(&stat, 0, sizeof(stat));
2713 blk_hctx_stat_get(hctx, stat);
2716 * As an optimistic guess, use half of the mean service time
2717 * for this type of request. We can (and should) make this smarter.
2718 * For instance, if the completion latencies are tight, we can
2719 * get closer than just half the mean. This is especially
2720 * important on devices where the completion latencies are longer
2723 if (req_op(rq) == REQ_OP_READ && stat[BLK_STAT_READ].nr_samples)
2724 ret = (stat[BLK_STAT_READ].mean + 1) / 2;
2725 else if (req_op(rq) == REQ_OP_WRITE && stat[BLK_STAT_WRITE].nr_samples)
2726 ret = (stat[BLK_STAT_WRITE].mean + 1) / 2;
2731 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2732 struct blk_mq_hw_ctx *hctx,
2735 struct hrtimer_sleeper hs;
2736 enum hrtimer_mode mode;
2740 if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2746 * -1: don't ever hybrid sleep
2747 * 0: use half of prev avg
2748 * >0: use this specific value
2750 if (q->poll_nsec == -1)
2752 else if (q->poll_nsec > 0)
2753 nsecs = q->poll_nsec;
2755 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2760 set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2763 * This will be replaced with the stats tracking code, using
2764 * 'avg_completion_time / 2' as the pre-sleep target.
2768 mode = HRTIMER_MODE_REL;
2769 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2770 hrtimer_set_expires(&hs.timer, kt);
2772 hrtimer_init_sleeper(&hs, current);
2774 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2776 set_current_state(TASK_UNINTERRUPTIBLE);
2777 hrtimer_start_expires(&hs.timer, mode);
2780 hrtimer_cancel(&hs.timer);
2781 mode = HRTIMER_MODE_ABS;
2782 } while (hs.task && !signal_pending(current));
2784 __set_current_state(TASK_RUNNING);
2785 destroy_hrtimer_on_stack(&hs.timer);
2789 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2791 struct request_queue *q = hctx->queue;
2795 * If we sleep, have the caller restart the poll loop to reset
2796 * the state. Like for the other success return cases, the
2797 * caller is responsible for checking if the IO completed. If
2798 * the IO isn't complete, we'll get called again and will go
2799 * straight to the busy poll loop.
2801 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2804 hctx->poll_considered++;
2806 state = current->state;
2807 while (!need_resched()) {
2810 hctx->poll_invoked++;
2812 ret = q->mq_ops->poll(hctx, rq->tag);
2814 hctx->poll_success++;
2815 set_current_state(TASK_RUNNING);
2819 if (signal_pending_state(state, current))
2820 set_current_state(TASK_RUNNING);
2822 if (current->state == TASK_RUNNING)
2832 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2834 struct blk_mq_hw_ctx *hctx;
2835 struct blk_plug *plug;
2838 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2839 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2842 plug = current->plug;
2844 blk_flush_plug_list(plug, false);
2846 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2847 if (!blk_qc_t_is_internal(cookie))
2848 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2850 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2852 return __blk_mq_poll(hctx, rq);
2854 EXPORT_SYMBOL_GPL(blk_mq_poll);
2856 void blk_mq_disable_hotplug(void)
2858 mutex_lock(&all_q_mutex);
2861 void blk_mq_enable_hotplug(void)
2863 mutex_unlock(&all_q_mutex);
2866 static int __init blk_mq_init(void)
2868 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2869 blk_mq_hctx_notify_dead);
2871 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2872 blk_mq_queue_reinit_prepare,
2873 blk_mq_queue_reinit_dead);
2876 subsys_initcall(blk_mq_init);