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/sched/topology.h>
24 #include <linux/sched/signal.h>
25 #include <linux/delay.h>
26 #include <linux/crash_dump.h>
27 #include <linux/prefetch.h>
29 #include <trace/events/block.h>
31 #include <linux/blk-mq.h>
34 #include "blk-mq-tag.h"
37 #include "blk-mq-sched.h"
39 static DEFINE_MUTEX(all_q_mutex);
40 static LIST_HEAD(all_q_list);
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);
46 * Check if any of the ctx's have pending work in this hardware queue
48 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
50 return sbitmap_any_bit_set(&hctx->ctx_map) ||
51 !list_empty_careful(&hctx->dispatch) ||
52 blk_mq_sched_has_work(hctx);
56 * Mark this ctx as having pending work in this hardware queue
58 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
59 struct blk_mq_ctx *ctx)
61 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
62 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
65 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
66 struct blk_mq_ctx *ctx)
68 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
71 void blk_freeze_queue_start(struct request_queue *q)
75 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
76 if (freeze_depth == 1) {
77 percpu_ref_kill(&q->q_usage_counter);
78 blk_mq_run_hw_queues(q, false);
81 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
83 void blk_mq_freeze_queue_wait(struct request_queue *q)
85 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
87 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
89 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
90 unsigned long timeout)
92 return wait_event_timeout(q->mq_freeze_wq,
93 percpu_ref_is_zero(&q->q_usage_counter),
96 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
99 * Guarantee no request is in use, so we can change any data structure of
100 * the queue afterward.
102 void blk_freeze_queue(struct request_queue *q)
105 * In the !blk_mq case we are only calling this to kill the
106 * q_usage_counter, otherwise this increases the freeze depth
107 * and waits for it to return to zero. For this reason there is
108 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
109 * exported to drivers as the only user for unfreeze is blk_mq.
111 blk_freeze_queue_start(q);
112 blk_mq_freeze_queue_wait(q);
115 void blk_mq_freeze_queue(struct request_queue *q)
118 * ...just an alias to keep freeze and unfreeze actions balanced
119 * in the blk_mq_* namespace
123 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
125 void blk_mq_unfreeze_queue(struct request_queue *q)
129 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
130 WARN_ON_ONCE(freeze_depth < 0);
132 percpu_ref_reinit(&q->q_usage_counter);
133 wake_up_all(&q->mq_freeze_wq);
136 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
139 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
142 * Note: this function does not prevent that the struct request end_io()
143 * callback function is invoked. Additionally, it is not prevented that
144 * new queue_rq() calls occur unless the queue has been stopped first.
146 void blk_mq_quiesce_queue(struct request_queue *q)
148 struct blk_mq_hw_ctx *hctx;
152 blk_mq_stop_hw_queues(q);
154 queue_for_each_hw_ctx(q, hctx, i) {
155 if (hctx->flags & BLK_MQ_F_BLOCKING)
156 synchronize_srcu(&hctx->queue_rq_srcu);
163 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
165 void blk_mq_wake_waiters(struct request_queue *q)
167 struct blk_mq_hw_ctx *hctx;
170 queue_for_each_hw_ctx(q, hctx, i)
171 if (blk_mq_hw_queue_mapped(hctx))
172 blk_mq_tag_wakeup_all(hctx->tags, true);
175 * If we are called because the queue has now been marked as
176 * dying, we need to ensure that processes currently waiting on
177 * the queue are notified as well.
179 wake_up_all(&q->mq_freeze_wq);
182 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
184 return blk_mq_has_free_tags(hctx->tags);
186 EXPORT_SYMBOL(blk_mq_can_queue);
188 void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
189 struct request *rq, unsigned int op)
191 INIT_LIST_HEAD(&rq->queuelist);
192 /* csd/requeue_work/fifo_time is initialized before use */
196 if (blk_queue_io_stat(q))
197 rq->rq_flags |= RQF_IO_STAT;
198 /* do not touch atomic flags, it needs atomic ops against the timer */
200 INIT_HLIST_NODE(&rq->hash);
201 RB_CLEAR_NODE(&rq->rb_node);
204 rq->start_time = jiffies;
205 #ifdef CONFIG_BLK_CGROUP
207 set_start_time_ns(rq);
208 rq->io_start_time_ns = 0;
210 rq->nr_phys_segments = 0;
211 #if defined(CONFIG_BLK_DEV_INTEGRITY)
212 rq->nr_integrity_segments = 0;
215 /* tag was already set */
219 INIT_LIST_HEAD(&rq->timeout_list);
223 rq->end_io_data = NULL;
226 ctx->rq_dispatched[op_is_sync(op)]++;
228 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
230 struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
236 tag = blk_mq_get_tag(data);
237 if (tag != BLK_MQ_TAG_FAIL) {
238 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
240 rq = tags->static_rqs[tag];
242 if (data->flags & BLK_MQ_REQ_INTERNAL) {
244 rq->internal_tag = tag;
246 if (blk_mq_tag_busy(data->hctx)) {
247 rq->rq_flags = RQF_MQ_INFLIGHT;
248 atomic_inc(&data->hctx->nr_active);
251 rq->internal_tag = -1;
252 data->hctx->tags->rqs[rq->tag] = rq;
255 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
261 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
263 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
266 struct blk_mq_alloc_data alloc_data = { .flags = flags };
270 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
274 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
276 blk_mq_put_ctx(alloc_data.ctx);
280 return ERR_PTR(-EWOULDBLOCK);
283 rq->__sector = (sector_t) -1;
284 rq->bio = rq->biotail = NULL;
287 EXPORT_SYMBOL(blk_mq_alloc_request);
289 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
290 unsigned int flags, unsigned int hctx_idx)
292 struct blk_mq_alloc_data alloc_data = { .flags = flags };
298 * If the tag allocator sleeps we could get an allocation for a
299 * different hardware context. No need to complicate the low level
300 * allocator for this for the rare use case of a command tied to
303 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
304 return ERR_PTR(-EINVAL);
306 if (hctx_idx >= q->nr_hw_queues)
307 return ERR_PTR(-EIO);
309 ret = blk_queue_enter(q, true);
314 * Check if the hardware context is actually mapped to anything.
315 * If not tell the caller that it should skip this queue.
317 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
318 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
320 return ERR_PTR(-EXDEV);
322 cpu = cpumask_first(alloc_data.hctx->cpumask);
323 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
325 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
327 blk_mq_put_ctx(alloc_data.ctx);
331 return ERR_PTR(-EWOULDBLOCK);
335 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
337 void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
340 const int sched_tag = rq->internal_tag;
341 struct request_queue *q = rq->q;
343 if (rq->rq_flags & RQF_MQ_INFLIGHT)
344 atomic_dec(&hctx->nr_active);
346 wbt_done(q->rq_wb, &rq->issue_stat);
349 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
350 clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
352 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
354 blk_mq_sched_completed_request(hctx, rq);
355 blk_mq_sched_restart_queues(hctx);
359 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
362 struct blk_mq_ctx *ctx = rq->mq_ctx;
364 ctx->rq_completed[rq_is_sync(rq)]++;
365 __blk_mq_finish_request(hctx, ctx, rq);
368 void blk_mq_finish_request(struct request *rq)
370 blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
373 void blk_mq_free_request(struct request *rq)
375 blk_mq_sched_put_request(rq);
377 EXPORT_SYMBOL_GPL(blk_mq_free_request);
379 inline void __blk_mq_end_request(struct request *rq, int error)
381 blk_account_io_done(rq);
384 wbt_done(rq->q->rq_wb, &rq->issue_stat);
385 rq->end_io(rq, error);
387 if (unlikely(blk_bidi_rq(rq)))
388 blk_mq_free_request(rq->next_rq);
389 blk_mq_free_request(rq);
392 EXPORT_SYMBOL(__blk_mq_end_request);
394 void blk_mq_end_request(struct request *rq, int error)
396 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
398 __blk_mq_end_request(rq, error);
400 EXPORT_SYMBOL(blk_mq_end_request);
402 static void __blk_mq_complete_request_remote(void *data)
404 struct request *rq = data;
406 rq->q->softirq_done_fn(rq);
409 static void blk_mq_ipi_complete_request(struct request *rq)
411 struct blk_mq_ctx *ctx = rq->mq_ctx;
415 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
416 rq->q->softirq_done_fn(rq);
421 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
422 shared = cpus_share_cache(cpu, ctx->cpu);
424 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
425 rq->csd.func = __blk_mq_complete_request_remote;
428 smp_call_function_single_async(ctx->cpu, &rq->csd);
430 rq->q->softirq_done_fn(rq);
435 static void blk_mq_stat_add(struct request *rq)
437 if (rq->rq_flags & RQF_STATS) {
438 blk_mq_poll_stats_start(rq->q);
443 static void __blk_mq_complete_request(struct request *rq)
445 struct request_queue *q = rq->q;
449 if (!q->softirq_done_fn)
450 blk_mq_end_request(rq, rq->errors);
452 blk_mq_ipi_complete_request(rq);
456 * blk_mq_complete_request - end I/O on a request
457 * @rq: the request being processed
460 * Ends all I/O on a request. It does not handle partial completions.
461 * The actual completion happens out-of-order, through a IPI handler.
463 void blk_mq_complete_request(struct request *rq, int error)
465 struct request_queue *q = rq->q;
467 if (unlikely(blk_should_fake_timeout(q)))
469 if (!blk_mark_rq_complete(rq)) {
471 __blk_mq_complete_request(rq);
474 EXPORT_SYMBOL(blk_mq_complete_request);
476 int blk_mq_request_started(struct request *rq)
478 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
480 EXPORT_SYMBOL_GPL(blk_mq_request_started);
482 void blk_mq_start_request(struct request *rq)
484 struct request_queue *q = rq->q;
486 blk_mq_sched_started_request(rq);
488 trace_block_rq_issue(q, rq);
490 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
491 blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
492 rq->rq_flags |= RQF_STATS;
493 wbt_issue(q->rq_wb, &rq->issue_stat);
499 * Ensure that ->deadline is visible before set the started
500 * flag and clear the completed flag.
502 smp_mb__before_atomic();
505 * Mark us as started and clear complete. Complete might have been
506 * set if requeue raced with timeout, which then marked it as
507 * complete. So be sure to clear complete again when we start
508 * the request, otherwise we'll ignore the completion event.
510 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
511 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
512 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
513 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
515 if (q->dma_drain_size && blk_rq_bytes(rq)) {
517 * Make sure space for the drain appears. We know we can do
518 * this because max_hw_segments has been adjusted to be one
519 * fewer than the device can handle.
521 rq->nr_phys_segments++;
524 EXPORT_SYMBOL(blk_mq_start_request);
527 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
528 * flag isn't set yet, so there may be race with timeout handler,
529 * but given rq->deadline is just set in .queue_rq() under
530 * this situation, the race won't be possible in reality because
531 * rq->timeout should be set as big enough to cover the window
532 * between blk_mq_start_request() called from .queue_rq() and
533 * clearing REQ_ATOM_STARTED here.
535 static void __blk_mq_requeue_request(struct request *rq)
537 struct request_queue *q = rq->q;
539 trace_block_rq_requeue(q, rq);
540 wbt_requeue(q->rq_wb, &rq->issue_stat);
541 blk_mq_sched_requeue_request(rq);
543 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
544 if (q->dma_drain_size && blk_rq_bytes(rq))
545 rq->nr_phys_segments--;
549 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
551 __blk_mq_requeue_request(rq);
553 BUG_ON(blk_queued_rq(rq));
554 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
556 EXPORT_SYMBOL(blk_mq_requeue_request);
558 static void blk_mq_requeue_work(struct work_struct *work)
560 struct request_queue *q =
561 container_of(work, struct request_queue, requeue_work.work);
563 struct request *rq, *next;
566 spin_lock_irqsave(&q->requeue_lock, flags);
567 list_splice_init(&q->requeue_list, &rq_list);
568 spin_unlock_irqrestore(&q->requeue_lock, flags);
570 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
571 if (!(rq->rq_flags & RQF_SOFTBARRIER))
574 rq->rq_flags &= ~RQF_SOFTBARRIER;
575 list_del_init(&rq->queuelist);
576 blk_mq_sched_insert_request(rq, true, false, false, true);
579 while (!list_empty(&rq_list)) {
580 rq = list_entry(rq_list.next, struct request, queuelist);
581 list_del_init(&rq->queuelist);
582 blk_mq_sched_insert_request(rq, false, false, false, true);
585 blk_mq_run_hw_queues(q, false);
588 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
589 bool kick_requeue_list)
591 struct request_queue *q = rq->q;
595 * We abuse this flag that is otherwise used by the I/O scheduler to
596 * request head insertation from the workqueue.
598 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
600 spin_lock_irqsave(&q->requeue_lock, flags);
602 rq->rq_flags |= RQF_SOFTBARRIER;
603 list_add(&rq->queuelist, &q->requeue_list);
605 list_add_tail(&rq->queuelist, &q->requeue_list);
607 spin_unlock_irqrestore(&q->requeue_lock, flags);
609 if (kick_requeue_list)
610 blk_mq_kick_requeue_list(q);
612 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
614 void blk_mq_kick_requeue_list(struct request_queue *q)
616 kblockd_schedule_delayed_work(&q->requeue_work, 0);
618 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
620 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
623 kblockd_schedule_delayed_work(&q->requeue_work,
624 msecs_to_jiffies(msecs));
626 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
628 void blk_mq_abort_requeue_list(struct request_queue *q)
633 spin_lock_irqsave(&q->requeue_lock, flags);
634 list_splice_init(&q->requeue_list, &rq_list);
635 spin_unlock_irqrestore(&q->requeue_lock, flags);
637 while (!list_empty(&rq_list)) {
640 rq = list_first_entry(&rq_list, struct request, queuelist);
641 list_del_init(&rq->queuelist);
643 blk_mq_end_request(rq, rq->errors);
646 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
648 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
650 if (tag < tags->nr_tags) {
651 prefetch(tags->rqs[tag]);
652 return tags->rqs[tag];
657 EXPORT_SYMBOL(blk_mq_tag_to_rq);
659 struct blk_mq_timeout_data {
661 unsigned int next_set;
664 void blk_mq_rq_timed_out(struct request *req, bool reserved)
666 const struct blk_mq_ops *ops = req->q->mq_ops;
667 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
670 * We know that complete is set at this point. If STARTED isn't set
671 * anymore, then the request isn't active and the "timeout" should
672 * just be ignored. This can happen due to the bitflag ordering.
673 * Timeout first checks if STARTED is set, and if it is, assumes
674 * the request is active. But if we race with completion, then
675 * both flags will get cleared. So check here again, and ignore
676 * a timeout event with a request that isn't active.
678 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
682 ret = ops->timeout(req, reserved);
686 __blk_mq_complete_request(req);
688 case BLK_EH_RESET_TIMER:
690 blk_clear_rq_complete(req);
692 case BLK_EH_NOT_HANDLED:
695 printk(KERN_ERR "block: bad eh return: %d\n", ret);
700 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
701 struct request *rq, void *priv, bool reserved)
703 struct blk_mq_timeout_data *data = priv;
705 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
709 * The rq being checked may have been freed and reallocated
710 * out already here, we avoid this race by checking rq->deadline
711 * and REQ_ATOM_COMPLETE flag together:
713 * - if rq->deadline is observed as new value because of
714 * reusing, the rq won't be timed out because of timing.
715 * - if rq->deadline is observed as previous value,
716 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
717 * because we put a barrier between setting rq->deadline
718 * and clearing the flag in blk_mq_start_request(), so
719 * this rq won't be timed out too.
721 if (time_after_eq(jiffies, rq->deadline)) {
722 if (!blk_mark_rq_complete(rq))
723 blk_mq_rq_timed_out(rq, reserved);
724 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
725 data->next = rq->deadline;
730 static void blk_mq_timeout_work(struct work_struct *work)
732 struct request_queue *q =
733 container_of(work, struct request_queue, timeout_work);
734 struct blk_mq_timeout_data data = {
740 /* A deadlock might occur if a request is stuck requiring a
741 * timeout at the same time a queue freeze is waiting
742 * completion, since the timeout code would not be able to
743 * acquire the queue reference here.
745 * That's why we don't use blk_queue_enter here; instead, we use
746 * percpu_ref_tryget directly, because we need to be able to
747 * obtain a reference even in the short window between the queue
748 * starting to freeze, by dropping the first reference in
749 * blk_freeze_queue_start, and the moment the last request is
750 * consumed, marked by the instant q_usage_counter reaches
753 if (!percpu_ref_tryget(&q->q_usage_counter))
756 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
759 data.next = blk_rq_timeout(round_jiffies_up(data.next));
760 mod_timer(&q->timeout, data.next);
762 struct blk_mq_hw_ctx *hctx;
764 queue_for_each_hw_ctx(q, hctx, i) {
765 /* the hctx may be unmapped, so check it here */
766 if (blk_mq_hw_queue_mapped(hctx))
767 blk_mq_tag_idle(hctx);
774 * Reverse check our software queue for entries that we could potentially
775 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
776 * too much time checking for merges.
778 static bool blk_mq_attempt_merge(struct request_queue *q,
779 struct blk_mq_ctx *ctx, struct bio *bio)
784 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
790 if (!blk_rq_merge_ok(rq, bio))
793 switch (blk_try_merge(rq, bio)) {
794 case ELEVATOR_BACK_MERGE:
795 if (blk_mq_sched_allow_merge(q, rq, bio))
796 merged = bio_attempt_back_merge(q, rq, bio);
798 case ELEVATOR_FRONT_MERGE:
799 if (blk_mq_sched_allow_merge(q, rq, bio))
800 merged = bio_attempt_front_merge(q, rq, bio);
802 case ELEVATOR_DISCARD_MERGE:
803 merged = bio_attempt_discard_merge(q, rq, bio);
817 struct flush_busy_ctx_data {
818 struct blk_mq_hw_ctx *hctx;
819 struct list_head *list;
822 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
824 struct flush_busy_ctx_data *flush_data = data;
825 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
826 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
828 sbitmap_clear_bit(sb, bitnr);
829 spin_lock(&ctx->lock);
830 list_splice_tail_init(&ctx->rq_list, flush_data->list);
831 spin_unlock(&ctx->lock);
836 * Process software queues that have been marked busy, splicing them
837 * to the for-dispatch
839 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
841 struct flush_busy_ctx_data data = {
846 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
848 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
850 static inline unsigned int queued_to_index(unsigned int queued)
855 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
858 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
861 struct blk_mq_alloc_data data = {
863 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
864 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
874 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
875 data.flags |= BLK_MQ_REQ_RESERVED;
877 rq->tag = blk_mq_get_tag(&data);
879 if (blk_mq_tag_busy(data.hctx)) {
880 rq->rq_flags |= RQF_MQ_INFLIGHT;
881 atomic_inc(&data.hctx->nr_active);
883 data.hctx->tags->rqs[rq->tag] = rq;
890 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
893 blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
896 if (rq->rq_flags & RQF_MQ_INFLIGHT) {
897 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
898 atomic_dec(&hctx->nr_active);
902 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
905 if (rq->tag == -1 || rq->internal_tag == -1)
908 __blk_mq_put_driver_tag(hctx, rq);
911 static void blk_mq_put_driver_tag(struct request *rq)
913 struct blk_mq_hw_ctx *hctx;
915 if (rq->tag == -1 || rq->internal_tag == -1)
918 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
919 __blk_mq_put_driver_tag(hctx, rq);
923 * If we fail getting a driver tag because all the driver tags are already
924 * assigned and on the dispatch list, BUT the first entry does not have a
925 * tag, then we could deadlock. For that case, move entries with assigned
926 * driver tags to the front, leaving the set of tagged requests in the
927 * same order, and the untagged set in the same order.
929 static bool reorder_tags_to_front(struct list_head *list)
931 struct request *rq, *tmp, *first = NULL;
933 list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
937 list_move(&rq->queuelist, list);
943 return first != NULL;
946 static int blk_mq_dispatch_wake(wait_queue_t *wait, unsigned mode, int flags,
949 struct blk_mq_hw_ctx *hctx;
951 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
953 list_del(&wait->task_list);
954 clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
955 blk_mq_run_hw_queue(hctx, true);
959 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
961 struct sbq_wait_state *ws;
964 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
965 * The thread which wins the race to grab this bit adds the hardware
966 * queue to the wait queue.
968 if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
969 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
972 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
973 ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
976 * As soon as this returns, it's no longer safe to fiddle with
977 * hctx->dispatch_wait, since a completion can wake up the wait queue
978 * and unlock the bit.
980 add_wait_queue(&ws->wait, &hctx->dispatch_wait);
984 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
986 struct request_queue *q = hctx->queue;
988 LIST_HEAD(driver_list);
989 struct list_head *dptr;
990 int errors, queued, ret = BLK_MQ_RQ_QUEUE_OK;
993 * Start off with dptr being NULL, so we start the first request
994 * immediately, even if we have more pending.
999 * Now process all the entries, sending them to the driver.
1001 errors = queued = 0;
1002 while (!list_empty(list)) {
1003 struct blk_mq_queue_data bd;
1005 rq = list_first_entry(list, struct request, queuelist);
1006 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
1007 if (!queued && reorder_tags_to_front(list))
1011 * The initial allocation attempt failed, so we need to
1012 * rerun the hardware queue when a tag is freed.
1014 if (blk_mq_dispatch_wait_add(hctx)) {
1016 * It's possible that a tag was freed in the
1017 * window between the allocation failure and
1018 * adding the hardware queue to the wait queue.
1020 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1027 list_del_init(&rq->queuelist);
1033 * Flag last if we have no more requests, or if we have more
1034 * but can't assign a driver tag to it.
1036 if (list_empty(list))
1039 struct request *nxt;
1041 nxt = list_first_entry(list, struct request, queuelist);
1042 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1045 ret = q->mq_ops->queue_rq(hctx, &bd);
1047 case BLK_MQ_RQ_QUEUE_OK:
1050 case BLK_MQ_RQ_QUEUE_BUSY:
1051 blk_mq_put_driver_tag_hctx(hctx, rq);
1052 list_add(&rq->queuelist, list);
1053 __blk_mq_requeue_request(rq);
1056 pr_err("blk-mq: bad return on queue: %d\n", ret);
1057 case BLK_MQ_RQ_QUEUE_ERROR:
1060 blk_mq_end_request(rq, rq->errors);
1064 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
1068 * We've done the first request. If we have more than 1
1069 * left in the list, set dptr to defer issue.
1071 if (!dptr && list->next != list->prev)
1072 dptr = &driver_list;
1075 hctx->dispatched[queued_to_index(queued)]++;
1078 * Any items that need requeuing? Stuff them into hctx->dispatch,
1079 * that is where we will continue on next queue run.
1081 if (!list_empty(list)) {
1083 * If we got a driver tag for the next request already,
1086 rq = list_first_entry(list, struct request, queuelist);
1087 blk_mq_put_driver_tag(rq);
1089 spin_lock(&hctx->lock);
1090 list_splice_init(list, &hctx->dispatch);
1091 spin_unlock(&hctx->lock);
1094 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1095 * it's possible the queue is stopped and restarted again
1096 * before this. Queue restart will dispatch requests. And since
1097 * requests in rq_list aren't added into hctx->dispatch yet,
1098 * the requests in rq_list might get lost.
1100 * blk_mq_run_hw_queue() already checks the STOPPED bit
1102 * If RESTART or TAG_WAITING is set, then let completion restart
1103 * the queue instead of potentially looping here.
1105 if (!blk_mq_sched_needs_restart(hctx) &&
1106 !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1107 blk_mq_run_hw_queue(hctx, true);
1110 return (queued + errors) != 0;
1113 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1117 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1118 cpu_online(hctx->next_cpu));
1120 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1122 blk_mq_sched_dispatch_requests(hctx);
1125 srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1126 blk_mq_sched_dispatch_requests(hctx);
1127 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1132 * It'd be great if the workqueue API had a way to pass
1133 * in a mask and had some smarts for more clever placement.
1134 * For now we just round-robin here, switching for every
1135 * BLK_MQ_CPU_WORK_BATCH queued items.
1137 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1139 if (hctx->queue->nr_hw_queues == 1)
1140 return WORK_CPU_UNBOUND;
1142 if (--hctx->next_cpu_batch <= 0) {
1145 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1146 if (next_cpu >= nr_cpu_ids)
1147 next_cpu = cpumask_first(hctx->cpumask);
1149 hctx->next_cpu = next_cpu;
1150 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1153 return hctx->next_cpu;
1156 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1158 if (unlikely(blk_mq_hctx_stopped(hctx) ||
1159 !blk_mq_hw_queue_mapped(hctx)))
1162 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1163 int cpu = get_cpu();
1164 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1165 __blk_mq_run_hw_queue(hctx);
1173 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
1176 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1178 struct blk_mq_hw_ctx *hctx;
1181 queue_for_each_hw_ctx(q, hctx, i) {
1182 if (!blk_mq_hctx_has_pending(hctx) ||
1183 blk_mq_hctx_stopped(hctx))
1186 blk_mq_run_hw_queue(hctx, async);
1189 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1192 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1193 * @q: request queue.
1195 * The caller is responsible for serializing this function against
1196 * blk_mq_{start,stop}_hw_queue().
1198 bool blk_mq_queue_stopped(struct request_queue *q)
1200 struct blk_mq_hw_ctx *hctx;
1203 queue_for_each_hw_ctx(q, hctx, i)
1204 if (blk_mq_hctx_stopped(hctx))
1209 EXPORT_SYMBOL(blk_mq_queue_stopped);
1211 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1213 cancel_work(&hctx->run_work);
1214 cancel_delayed_work(&hctx->delay_work);
1215 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1217 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1219 void blk_mq_stop_hw_queues(struct request_queue *q)
1221 struct blk_mq_hw_ctx *hctx;
1224 queue_for_each_hw_ctx(q, hctx, i)
1225 blk_mq_stop_hw_queue(hctx);
1227 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1229 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1231 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1233 blk_mq_run_hw_queue(hctx, false);
1235 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1237 void blk_mq_start_hw_queues(struct request_queue *q)
1239 struct blk_mq_hw_ctx *hctx;
1242 queue_for_each_hw_ctx(q, hctx, i)
1243 blk_mq_start_hw_queue(hctx);
1245 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1247 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1249 if (!blk_mq_hctx_stopped(hctx))
1252 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1253 blk_mq_run_hw_queue(hctx, async);
1255 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1257 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1259 struct blk_mq_hw_ctx *hctx;
1262 queue_for_each_hw_ctx(q, hctx, i)
1263 blk_mq_start_stopped_hw_queue(hctx, async);
1265 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1267 static void blk_mq_run_work_fn(struct work_struct *work)
1269 struct blk_mq_hw_ctx *hctx;
1271 hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
1273 __blk_mq_run_hw_queue(hctx);
1276 static void blk_mq_delay_work_fn(struct work_struct *work)
1278 struct blk_mq_hw_ctx *hctx;
1280 hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1282 if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1283 __blk_mq_run_hw_queue(hctx);
1286 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1288 if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1291 blk_mq_stop_hw_queue(hctx);
1292 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1293 &hctx->delay_work, msecs_to_jiffies(msecs));
1295 EXPORT_SYMBOL(blk_mq_delay_queue);
1297 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1301 struct blk_mq_ctx *ctx = rq->mq_ctx;
1303 trace_block_rq_insert(hctx->queue, rq);
1306 list_add(&rq->queuelist, &ctx->rq_list);
1308 list_add_tail(&rq->queuelist, &ctx->rq_list);
1311 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1314 struct blk_mq_ctx *ctx = rq->mq_ctx;
1316 __blk_mq_insert_req_list(hctx, rq, at_head);
1317 blk_mq_hctx_mark_pending(hctx, ctx);
1320 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1321 struct list_head *list)
1325 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1328 spin_lock(&ctx->lock);
1329 while (!list_empty(list)) {
1332 rq = list_first_entry(list, struct request, queuelist);
1333 BUG_ON(rq->mq_ctx != ctx);
1334 list_del_init(&rq->queuelist);
1335 __blk_mq_insert_req_list(hctx, rq, false);
1337 blk_mq_hctx_mark_pending(hctx, ctx);
1338 spin_unlock(&ctx->lock);
1341 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1343 struct request *rqa = container_of(a, struct request, queuelist);
1344 struct request *rqb = container_of(b, struct request, queuelist);
1346 return !(rqa->mq_ctx < rqb->mq_ctx ||
1347 (rqa->mq_ctx == rqb->mq_ctx &&
1348 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1351 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1353 struct blk_mq_ctx *this_ctx;
1354 struct request_queue *this_q;
1357 LIST_HEAD(ctx_list);
1360 list_splice_init(&plug->mq_list, &list);
1362 list_sort(NULL, &list, plug_ctx_cmp);
1368 while (!list_empty(&list)) {
1369 rq = list_entry_rq(list.next);
1370 list_del_init(&rq->queuelist);
1372 if (rq->mq_ctx != this_ctx) {
1374 trace_block_unplug(this_q, depth, from_schedule);
1375 blk_mq_sched_insert_requests(this_q, this_ctx,
1380 this_ctx = rq->mq_ctx;
1386 list_add_tail(&rq->queuelist, &ctx_list);
1390 * If 'this_ctx' is set, we know we have entries to complete
1391 * on 'ctx_list'. Do those.
1394 trace_block_unplug(this_q, depth, from_schedule);
1395 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1400 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1402 init_request_from_bio(rq, bio);
1404 blk_account_io_start(rq, true);
1407 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1409 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1410 !blk_queue_nomerges(hctx->queue);
1413 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1414 struct blk_mq_ctx *ctx,
1415 struct request *rq, struct bio *bio)
1417 if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1418 blk_mq_bio_to_request(rq, bio);
1419 spin_lock(&ctx->lock);
1421 __blk_mq_insert_request(hctx, rq, false);
1422 spin_unlock(&ctx->lock);
1425 struct request_queue *q = hctx->queue;
1427 spin_lock(&ctx->lock);
1428 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1429 blk_mq_bio_to_request(rq, bio);
1433 spin_unlock(&ctx->lock);
1434 __blk_mq_finish_request(hctx, ctx, rq);
1439 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1442 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1444 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1447 static void __blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
1450 struct request_queue *q = rq->q;
1451 struct blk_mq_queue_data bd = {
1456 struct blk_mq_hw_ctx *hctx;
1457 blk_qc_t new_cookie;
1463 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1466 new_cookie = request_to_qc_t(hctx, rq);
1469 * For OK queue, we are done. For error, kill it. Any other
1470 * error (busy), just add it to our list as we previously
1473 ret = q->mq_ops->queue_rq(hctx, &bd);
1474 if (ret == BLK_MQ_RQ_QUEUE_OK) {
1475 *cookie = new_cookie;
1479 if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1480 *cookie = BLK_QC_T_NONE;
1482 blk_mq_end_request(rq, rq->errors);
1486 __blk_mq_requeue_request(rq);
1488 blk_mq_sched_insert_request(rq, false, true, false, may_sleep);
1491 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1492 struct request *rq, blk_qc_t *cookie)
1494 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1496 __blk_mq_try_issue_directly(rq, cookie, false);
1499 unsigned int srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1500 __blk_mq_try_issue_directly(rq, cookie, true);
1501 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1505 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1507 const int is_sync = op_is_sync(bio->bi_opf);
1508 const int is_flush_fua = op_is_flush(bio->bi_opf);
1509 struct blk_mq_alloc_data data = { .flags = 0 };
1511 unsigned int request_count = 0;
1512 struct blk_plug *plug;
1513 struct request *same_queue_rq = NULL;
1515 unsigned int wb_acct;
1517 blk_queue_bounce(q, &bio);
1519 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1521 return BLK_QC_T_NONE;
1524 blk_queue_split(q, &bio, q->bio_split);
1526 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1527 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1528 return BLK_QC_T_NONE;
1530 if (blk_mq_sched_bio_merge(q, bio))
1531 return BLK_QC_T_NONE;
1533 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1535 trace_block_getrq(q, bio, bio->bi_opf);
1537 rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1538 if (unlikely(!rq)) {
1539 __wbt_done(q->rq_wb, wb_acct);
1540 return BLK_QC_T_NONE;
1543 wbt_track(&rq->issue_stat, wb_acct);
1545 cookie = request_to_qc_t(data.hctx, rq);
1547 plug = current->plug;
1548 if (unlikely(is_flush_fua)) {
1549 blk_mq_bio_to_request(rq, bio);
1551 blk_mq_sched_insert_request(rq, false, true, true,
1554 blk_insert_flush(rq);
1555 blk_mq_run_hw_queue(data.hctx, true);
1557 } else if (plug && q->nr_hw_queues == 1) {
1558 struct request *last = NULL;
1560 blk_mq_bio_to_request(rq, bio);
1563 * @request_count may become stale because of schedule
1564 * out, so check the list again.
1566 if (list_empty(&plug->mq_list))
1568 else if (blk_queue_nomerges(q))
1569 request_count = blk_plug_queued_count(q);
1572 trace_block_plug(q);
1574 last = list_entry_rq(plug->mq_list.prev);
1576 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1577 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1578 blk_flush_plug_list(plug, false);
1579 trace_block_plug(q);
1582 list_add_tail(&rq->queuelist, &plug->mq_list);
1583 } else if (plug && !blk_queue_nomerges(q)) {
1584 blk_mq_bio_to_request(rq, bio);
1587 * We do limited plugging. If the bio can be merged, do that.
1588 * Otherwise the existing request in the plug list will be
1589 * issued. So the plug list will have one request at most
1590 * The plug list might get flushed before this. If that happens,
1591 * the plug list is empty, and same_queue_rq is invalid.
1593 if (list_empty(&plug->mq_list))
1594 same_queue_rq = NULL;
1596 list_del_init(&same_queue_rq->queuelist);
1597 list_add_tail(&rq->queuelist, &plug->mq_list);
1600 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1602 } else if (q->nr_hw_queues > 1 && is_sync) {
1603 blk_mq_bio_to_request(rq, bio);
1604 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1605 } else if (q->elevator) {
1606 blk_mq_bio_to_request(rq, bio);
1607 blk_mq_sched_insert_request(rq, false, true, true, true);
1608 } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1609 blk_mq_run_hw_queue(data.hctx, true);
1612 blk_mq_put_ctx(data.ctx);
1616 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1617 unsigned int hctx_idx)
1621 if (tags->rqs && set->ops->exit_request) {
1624 for (i = 0; i < tags->nr_tags; i++) {
1625 struct request *rq = tags->static_rqs[i];
1629 set->ops->exit_request(set->driver_data, rq,
1631 tags->static_rqs[i] = NULL;
1635 while (!list_empty(&tags->page_list)) {
1636 page = list_first_entry(&tags->page_list, struct page, lru);
1637 list_del_init(&page->lru);
1639 * Remove kmemleak object previously allocated in
1640 * blk_mq_init_rq_map().
1642 kmemleak_free(page_address(page));
1643 __free_pages(page, page->private);
1647 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1651 kfree(tags->static_rqs);
1652 tags->static_rqs = NULL;
1654 blk_mq_free_tags(tags);
1657 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1658 unsigned int hctx_idx,
1659 unsigned int nr_tags,
1660 unsigned int reserved_tags)
1662 struct blk_mq_tags *tags;
1665 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1666 if (node == NUMA_NO_NODE)
1667 node = set->numa_node;
1669 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1670 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1674 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1675 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1678 blk_mq_free_tags(tags);
1682 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1683 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1685 if (!tags->static_rqs) {
1687 blk_mq_free_tags(tags);
1694 static size_t order_to_size(unsigned int order)
1696 return (size_t)PAGE_SIZE << order;
1699 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1700 unsigned int hctx_idx, unsigned int depth)
1702 unsigned int i, j, entries_per_page, max_order = 4;
1703 size_t rq_size, left;
1706 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1707 if (node == NUMA_NO_NODE)
1708 node = set->numa_node;
1710 INIT_LIST_HEAD(&tags->page_list);
1713 * rq_size is the size of the request plus driver payload, rounded
1714 * to the cacheline size
1716 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1718 left = rq_size * depth;
1720 for (i = 0; i < depth; ) {
1721 int this_order = max_order;
1726 while (this_order && left < order_to_size(this_order - 1))
1730 page = alloc_pages_node(node,
1731 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1737 if (order_to_size(this_order) < rq_size)
1744 page->private = this_order;
1745 list_add_tail(&page->lru, &tags->page_list);
1747 p = page_address(page);
1749 * Allow kmemleak to scan these pages as they contain pointers
1750 * to additional allocations like via ops->init_request().
1752 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1753 entries_per_page = order_to_size(this_order) / rq_size;
1754 to_do = min(entries_per_page, depth - i);
1755 left -= to_do * rq_size;
1756 for (j = 0; j < to_do; j++) {
1757 struct request *rq = p;
1759 tags->static_rqs[i] = rq;
1760 if (set->ops->init_request) {
1761 if (set->ops->init_request(set->driver_data,
1764 tags->static_rqs[i] = NULL;
1776 blk_mq_free_rqs(set, tags, hctx_idx);
1781 * 'cpu' is going away. splice any existing rq_list entries from this
1782 * software queue to the hw queue dispatch list, and ensure that it
1785 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1787 struct blk_mq_hw_ctx *hctx;
1788 struct blk_mq_ctx *ctx;
1791 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1792 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1794 spin_lock(&ctx->lock);
1795 if (!list_empty(&ctx->rq_list)) {
1796 list_splice_init(&ctx->rq_list, &tmp);
1797 blk_mq_hctx_clear_pending(hctx, ctx);
1799 spin_unlock(&ctx->lock);
1801 if (list_empty(&tmp))
1804 spin_lock(&hctx->lock);
1805 list_splice_tail_init(&tmp, &hctx->dispatch);
1806 spin_unlock(&hctx->lock);
1808 blk_mq_run_hw_queue(hctx, true);
1812 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1814 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1818 /* hctx->ctxs will be freed in queue's release handler */
1819 static void blk_mq_exit_hctx(struct request_queue *q,
1820 struct blk_mq_tag_set *set,
1821 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1823 unsigned flush_start_tag = set->queue_depth;
1825 blk_mq_tag_idle(hctx);
1827 if (set->ops->exit_request)
1828 set->ops->exit_request(set->driver_data,
1829 hctx->fq->flush_rq, hctx_idx,
1830 flush_start_tag + hctx_idx);
1832 if (set->ops->exit_hctx)
1833 set->ops->exit_hctx(hctx, hctx_idx);
1835 if (hctx->flags & BLK_MQ_F_BLOCKING)
1836 cleanup_srcu_struct(&hctx->queue_rq_srcu);
1838 blk_mq_remove_cpuhp(hctx);
1839 blk_free_flush_queue(hctx->fq);
1840 sbitmap_free(&hctx->ctx_map);
1843 static void blk_mq_exit_hw_queues(struct request_queue *q,
1844 struct blk_mq_tag_set *set, int nr_queue)
1846 struct blk_mq_hw_ctx *hctx;
1849 queue_for_each_hw_ctx(q, hctx, i) {
1852 blk_mq_exit_hctx(q, set, hctx, i);
1856 static int blk_mq_init_hctx(struct request_queue *q,
1857 struct blk_mq_tag_set *set,
1858 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1861 unsigned flush_start_tag = set->queue_depth;
1863 node = hctx->numa_node;
1864 if (node == NUMA_NO_NODE)
1865 node = hctx->numa_node = set->numa_node;
1867 INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1868 INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1869 spin_lock_init(&hctx->lock);
1870 INIT_LIST_HEAD(&hctx->dispatch);
1872 hctx->queue_num = hctx_idx;
1873 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1875 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1877 hctx->tags = set->tags[hctx_idx];
1880 * Allocate space for all possible cpus to avoid allocation at
1883 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1886 goto unregister_cpu_notifier;
1888 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1894 if (set->ops->init_hctx &&
1895 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1898 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1902 if (set->ops->init_request &&
1903 set->ops->init_request(set->driver_data,
1904 hctx->fq->flush_rq, hctx_idx,
1905 flush_start_tag + hctx_idx, node))
1908 if (hctx->flags & BLK_MQ_F_BLOCKING)
1909 init_srcu_struct(&hctx->queue_rq_srcu);
1916 if (set->ops->exit_hctx)
1917 set->ops->exit_hctx(hctx, hctx_idx);
1919 sbitmap_free(&hctx->ctx_map);
1922 unregister_cpu_notifier:
1923 blk_mq_remove_cpuhp(hctx);
1927 static void blk_mq_init_cpu_queues(struct request_queue *q,
1928 unsigned int nr_hw_queues)
1932 for_each_possible_cpu(i) {
1933 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1934 struct blk_mq_hw_ctx *hctx;
1937 spin_lock_init(&__ctx->lock);
1938 INIT_LIST_HEAD(&__ctx->rq_list);
1941 /* If the cpu isn't online, the cpu is mapped to first hctx */
1945 hctx = blk_mq_map_queue(q, i);
1948 * Set local node, IFF we have more than one hw queue. If
1949 * not, we remain on the home node of the device
1951 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1952 hctx->numa_node = local_memory_node(cpu_to_node(i));
1956 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
1960 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
1961 set->queue_depth, set->reserved_tags);
1962 if (!set->tags[hctx_idx])
1965 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
1970 blk_mq_free_rq_map(set->tags[hctx_idx]);
1971 set->tags[hctx_idx] = NULL;
1975 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
1976 unsigned int hctx_idx)
1978 if (set->tags[hctx_idx]) {
1979 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
1980 blk_mq_free_rq_map(set->tags[hctx_idx]);
1981 set->tags[hctx_idx] = NULL;
1985 static void blk_mq_map_swqueue(struct request_queue *q,
1986 const struct cpumask *online_mask)
1988 unsigned int i, hctx_idx;
1989 struct blk_mq_hw_ctx *hctx;
1990 struct blk_mq_ctx *ctx;
1991 struct blk_mq_tag_set *set = q->tag_set;
1994 * Avoid others reading imcomplete hctx->cpumask through sysfs
1996 mutex_lock(&q->sysfs_lock);
1998 queue_for_each_hw_ctx(q, hctx, i) {
1999 cpumask_clear(hctx->cpumask);
2004 * Map software to hardware queues
2006 for_each_possible_cpu(i) {
2007 /* If the cpu isn't online, the cpu is mapped to first hctx */
2008 if (!cpumask_test_cpu(i, online_mask))
2011 hctx_idx = q->mq_map[i];
2012 /* unmapped hw queue can be remapped after CPU topo changed */
2013 if (!set->tags[hctx_idx] &&
2014 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2016 * If tags initialization fail for some hctx,
2017 * that hctx won't be brought online. In this
2018 * case, remap the current ctx to hctx[0] which
2019 * is guaranteed to always have tags allocated
2024 ctx = per_cpu_ptr(q->queue_ctx, i);
2025 hctx = blk_mq_map_queue(q, i);
2027 cpumask_set_cpu(i, hctx->cpumask);
2028 ctx->index_hw = hctx->nr_ctx;
2029 hctx->ctxs[hctx->nr_ctx++] = ctx;
2032 mutex_unlock(&q->sysfs_lock);
2034 queue_for_each_hw_ctx(q, hctx, i) {
2036 * If no software queues are mapped to this hardware queue,
2037 * disable it and free the request entries.
2039 if (!hctx->nr_ctx) {
2040 /* Never unmap queue 0. We need it as a
2041 * fallback in case of a new remap fails
2044 if (i && set->tags[i])
2045 blk_mq_free_map_and_requests(set, i);
2051 hctx->tags = set->tags[i];
2052 WARN_ON(!hctx->tags);
2055 * Set the map size to the number of mapped software queues.
2056 * This is more accurate and more efficient than looping
2057 * over all possibly mapped software queues.
2059 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2062 * Initialize batch roundrobin counts
2064 hctx->next_cpu = cpumask_first(hctx->cpumask);
2065 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2069 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2071 struct blk_mq_hw_ctx *hctx;
2074 queue_for_each_hw_ctx(q, hctx, i) {
2076 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2078 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2082 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
2084 struct request_queue *q;
2086 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2087 blk_mq_freeze_queue(q);
2088 queue_set_hctx_shared(q, shared);
2089 blk_mq_unfreeze_queue(q);
2093 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2095 struct blk_mq_tag_set *set = q->tag_set;
2097 mutex_lock(&set->tag_list_lock);
2098 list_del_init(&q->tag_set_list);
2099 if (list_is_singular(&set->tag_list)) {
2100 /* just transitioned to unshared */
2101 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2102 /* update existing queue */
2103 blk_mq_update_tag_set_depth(set, false);
2105 mutex_unlock(&set->tag_list_lock);
2108 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2109 struct request_queue *q)
2113 mutex_lock(&set->tag_list_lock);
2115 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2116 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2117 set->flags |= BLK_MQ_F_TAG_SHARED;
2118 /* update existing queue */
2119 blk_mq_update_tag_set_depth(set, true);
2121 if (set->flags & BLK_MQ_F_TAG_SHARED)
2122 queue_set_hctx_shared(q, true);
2123 list_add_tail(&q->tag_set_list, &set->tag_list);
2125 mutex_unlock(&set->tag_list_lock);
2129 * It is the actual release handler for mq, but we do it from
2130 * request queue's release handler for avoiding use-after-free
2131 * and headache because q->mq_kobj shouldn't have been introduced,
2132 * but we can't group ctx/kctx kobj without it.
2134 void blk_mq_release(struct request_queue *q)
2136 struct blk_mq_hw_ctx *hctx;
2139 blk_mq_sched_teardown(q);
2141 /* hctx kobj stays in hctx */
2142 queue_for_each_hw_ctx(q, hctx, i) {
2145 kobject_put(&hctx->kobj);
2150 kfree(q->queue_hw_ctx);
2153 * release .mq_kobj and sw queue's kobject now because
2154 * both share lifetime with request queue.
2156 blk_mq_sysfs_deinit(q);
2158 free_percpu(q->queue_ctx);
2161 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2163 struct request_queue *uninit_q, *q;
2165 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2167 return ERR_PTR(-ENOMEM);
2169 q = blk_mq_init_allocated_queue(set, uninit_q);
2171 blk_cleanup_queue(uninit_q);
2175 EXPORT_SYMBOL(blk_mq_init_queue);
2177 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2178 struct request_queue *q)
2181 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2183 blk_mq_sysfs_unregister(q);
2184 for (i = 0; i < set->nr_hw_queues; i++) {
2190 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2191 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
2196 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2203 atomic_set(&hctxs[i]->nr_active, 0);
2204 hctxs[i]->numa_node = node;
2205 hctxs[i]->queue_num = i;
2207 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2208 free_cpumask_var(hctxs[i]->cpumask);
2213 blk_mq_hctx_kobj_init(hctxs[i]);
2215 for (j = i; j < q->nr_hw_queues; j++) {
2216 struct blk_mq_hw_ctx *hctx = hctxs[j];
2220 blk_mq_free_map_and_requests(set, j);
2221 blk_mq_exit_hctx(q, set, hctx, j);
2222 kobject_put(&hctx->kobj);
2227 q->nr_hw_queues = i;
2228 blk_mq_sysfs_register(q);
2231 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2232 struct request_queue *q)
2234 /* mark the queue as mq asap */
2235 q->mq_ops = set->ops;
2237 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2238 blk_stat_rq_ddir, 2, q);
2242 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2246 /* init q->mq_kobj and sw queues' kobjects */
2247 blk_mq_sysfs_init(q);
2249 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2250 GFP_KERNEL, set->numa_node);
2251 if (!q->queue_hw_ctx)
2254 q->mq_map = set->mq_map;
2256 blk_mq_realloc_hw_ctxs(set, q);
2257 if (!q->nr_hw_queues)
2260 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2261 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2263 q->nr_queues = nr_cpu_ids;
2265 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2267 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2268 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2270 q->sg_reserved_size = INT_MAX;
2272 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2273 INIT_LIST_HEAD(&q->requeue_list);
2274 spin_lock_init(&q->requeue_lock);
2276 blk_queue_make_request(q, blk_mq_make_request);
2279 * Do this after blk_queue_make_request() overrides it...
2281 q->nr_requests = set->queue_depth;
2284 * Default to classic polling
2288 if (set->ops->complete)
2289 blk_queue_softirq_done(q, set->ops->complete);
2291 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2294 mutex_lock(&all_q_mutex);
2296 list_add_tail(&q->all_q_node, &all_q_list);
2297 blk_mq_add_queue_tag_set(set, q);
2298 blk_mq_map_swqueue(q, cpu_online_mask);
2300 mutex_unlock(&all_q_mutex);
2303 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2306 ret = blk_mq_sched_init(q);
2308 return ERR_PTR(ret);
2314 kfree(q->queue_hw_ctx);
2316 free_percpu(q->queue_ctx);
2319 return ERR_PTR(-ENOMEM);
2321 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2323 void blk_mq_free_queue(struct request_queue *q)
2325 struct blk_mq_tag_set *set = q->tag_set;
2327 mutex_lock(&all_q_mutex);
2328 list_del_init(&q->all_q_node);
2329 mutex_unlock(&all_q_mutex);
2331 blk_mq_del_queue_tag_set(q);
2333 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2336 /* Basically redo blk_mq_init_queue with queue frozen */
2337 static void blk_mq_queue_reinit(struct request_queue *q,
2338 const struct cpumask *online_mask)
2340 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2342 blk_mq_sysfs_unregister(q);
2345 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2346 * we should change hctx numa_node according to new topology (this
2347 * involves free and re-allocate memory, worthy doing?)
2350 blk_mq_map_swqueue(q, online_mask);
2352 blk_mq_sysfs_register(q);
2356 * New online cpumask which is going to be set in this hotplug event.
2357 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2358 * one-by-one and dynamically allocating this could result in a failure.
2360 static struct cpumask cpuhp_online_new;
2362 static void blk_mq_queue_reinit_work(void)
2364 struct request_queue *q;
2366 mutex_lock(&all_q_mutex);
2368 * We need to freeze and reinit all existing queues. Freezing
2369 * involves synchronous wait for an RCU grace period and doing it
2370 * one by one may take a long time. Start freezing all queues in
2371 * one swoop and then wait for the completions so that freezing can
2372 * take place in parallel.
2374 list_for_each_entry(q, &all_q_list, all_q_node)
2375 blk_freeze_queue_start(q);
2376 list_for_each_entry(q, &all_q_list, all_q_node)
2377 blk_mq_freeze_queue_wait(q);
2379 list_for_each_entry(q, &all_q_list, all_q_node)
2380 blk_mq_queue_reinit(q, &cpuhp_online_new);
2382 list_for_each_entry(q, &all_q_list, all_q_node)
2383 blk_mq_unfreeze_queue(q);
2385 mutex_unlock(&all_q_mutex);
2388 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2390 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2391 blk_mq_queue_reinit_work();
2396 * Before hotadded cpu starts handling requests, new mappings must be
2397 * established. Otherwise, these requests in hw queue might never be
2400 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2401 * for CPU0, and ctx1 for CPU1).
2403 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2404 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2406 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2407 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2408 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2411 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2413 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2414 cpumask_set_cpu(cpu, &cpuhp_online_new);
2415 blk_mq_queue_reinit_work();
2419 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2423 for (i = 0; i < set->nr_hw_queues; i++)
2424 if (!__blk_mq_alloc_rq_map(set, i))
2431 blk_mq_free_rq_map(set->tags[i]);
2437 * Allocate the request maps associated with this tag_set. Note that this
2438 * may reduce the depth asked for, if memory is tight. set->queue_depth
2439 * will be updated to reflect the allocated depth.
2441 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2446 depth = set->queue_depth;
2448 err = __blk_mq_alloc_rq_maps(set);
2452 set->queue_depth >>= 1;
2453 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2457 } while (set->queue_depth);
2459 if (!set->queue_depth || err) {
2460 pr_err("blk-mq: failed to allocate request map\n");
2464 if (depth != set->queue_depth)
2465 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2466 depth, set->queue_depth);
2472 * Alloc a tag set to be associated with one or more request queues.
2473 * May fail with EINVAL for various error conditions. May adjust the
2474 * requested depth down, if if it too large. In that case, the set
2475 * value will be stored in set->queue_depth.
2477 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2481 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2483 if (!set->nr_hw_queues)
2485 if (!set->queue_depth)
2487 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2490 if (!set->ops->queue_rq)
2493 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2494 pr_info("blk-mq: reduced tag depth to %u\n",
2496 set->queue_depth = BLK_MQ_MAX_DEPTH;
2500 * If a crashdump is active, then we are potentially in a very
2501 * memory constrained environment. Limit us to 1 queue and
2502 * 64 tags to prevent using too much memory.
2504 if (is_kdump_kernel()) {
2505 set->nr_hw_queues = 1;
2506 set->queue_depth = min(64U, set->queue_depth);
2509 * There is no use for more h/w queues than cpus.
2511 if (set->nr_hw_queues > nr_cpu_ids)
2512 set->nr_hw_queues = nr_cpu_ids;
2514 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2515 GFP_KERNEL, set->numa_node);
2520 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2521 GFP_KERNEL, set->numa_node);
2525 if (set->ops->map_queues)
2526 ret = set->ops->map_queues(set);
2528 ret = blk_mq_map_queues(set);
2530 goto out_free_mq_map;
2532 ret = blk_mq_alloc_rq_maps(set);
2534 goto out_free_mq_map;
2536 mutex_init(&set->tag_list_lock);
2537 INIT_LIST_HEAD(&set->tag_list);
2549 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2551 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2555 for (i = 0; i < nr_cpu_ids; i++)
2556 blk_mq_free_map_and_requests(set, i);
2564 EXPORT_SYMBOL(blk_mq_free_tag_set);
2566 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2568 struct blk_mq_tag_set *set = q->tag_set;
2569 struct blk_mq_hw_ctx *hctx;
2575 blk_mq_freeze_queue(q);
2576 blk_mq_quiesce_queue(q);
2579 queue_for_each_hw_ctx(q, hctx, i) {
2583 * If we're using an MQ scheduler, just update the scheduler
2584 * queue depth. This is similar to what the old code would do.
2586 if (!hctx->sched_tags) {
2587 ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2588 min(nr, set->queue_depth),
2591 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2599 q->nr_requests = nr;
2601 blk_mq_unfreeze_queue(q);
2602 blk_mq_start_stopped_hw_queues(q, true);
2607 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2609 struct request_queue *q;
2611 if (nr_hw_queues > nr_cpu_ids)
2612 nr_hw_queues = nr_cpu_ids;
2613 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2616 list_for_each_entry(q, &set->tag_list, tag_set_list)
2617 blk_mq_freeze_queue(q);
2619 set->nr_hw_queues = nr_hw_queues;
2620 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2621 blk_mq_realloc_hw_ctxs(set, q);
2622 blk_mq_queue_reinit(q, cpu_online_mask);
2625 list_for_each_entry(q, &set->tag_list, tag_set_list)
2626 blk_mq_unfreeze_queue(q);
2628 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2630 /* Enable polling stats and return whether they were already enabled. */
2631 static bool blk_poll_stats_enable(struct request_queue *q)
2633 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2634 test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
2636 blk_stat_add_callback(q, q->poll_cb);
2640 static void blk_mq_poll_stats_start(struct request_queue *q)
2643 * We don't arm the callback if polling stats are not enabled or the
2644 * callback is already active.
2646 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2647 blk_stat_is_active(q->poll_cb))
2650 blk_stat_activate_msecs(q->poll_cb, 100);
2653 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
2655 struct request_queue *q = cb->data;
2657 if (cb->stat[READ].nr_samples)
2658 q->poll_stat[READ] = cb->stat[READ];
2659 if (cb->stat[WRITE].nr_samples)
2660 q->poll_stat[WRITE] = cb->stat[WRITE];
2663 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2664 struct blk_mq_hw_ctx *hctx,
2667 unsigned long ret = 0;
2670 * If stats collection isn't on, don't sleep but turn it on for
2673 if (!blk_poll_stats_enable(q))
2677 * As an optimistic guess, use half of the mean service time
2678 * for this type of request. We can (and should) make this smarter.
2679 * For instance, if the completion latencies are tight, we can
2680 * get closer than just half the mean. This is especially
2681 * important on devices where the completion latencies are longer
2684 if (req_op(rq) == REQ_OP_READ && q->poll_stat[READ].nr_samples)
2685 ret = (q->poll_stat[READ].mean + 1) / 2;
2686 else if (req_op(rq) == REQ_OP_WRITE && q->poll_stat[WRITE].nr_samples)
2687 ret = (q->poll_stat[WRITE].mean + 1) / 2;
2692 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2693 struct blk_mq_hw_ctx *hctx,
2696 struct hrtimer_sleeper hs;
2697 enum hrtimer_mode mode;
2701 if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2707 * -1: don't ever hybrid sleep
2708 * 0: use half of prev avg
2709 * >0: use this specific value
2711 if (q->poll_nsec == -1)
2713 else if (q->poll_nsec > 0)
2714 nsecs = q->poll_nsec;
2716 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2721 set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2724 * This will be replaced with the stats tracking code, using
2725 * 'avg_completion_time / 2' as the pre-sleep target.
2729 mode = HRTIMER_MODE_REL;
2730 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2731 hrtimer_set_expires(&hs.timer, kt);
2733 hrtimer_init_sleeper(&hs, current);
2735 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2737 set_current_state(TASK_UNINTERRUPTIBLE);
2738 hrtimer_start_expires(&hs.timer, mode);
2741 hrtimer_cancel(&hs.timer);
2742 mode = HRTIMER_MODE_ABS;
2743 } while (hs.task && !signal_pending(current));
2745 __set_current_state(TASK_RUNNING);
2746 destroy_hrtimer_on_stack(&hs.timer);
2750 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2752 struct request_queue *q = hctx->queue;
2756 * If we sleep, have the caller restart the poll loop to reset
2757 * the state. Like for the other success return cases, the
2758 * caller is responsible for checking if the IO completed. If
2759 * the IO isn't complete, we'll get called again and will go
2760 * straight to the busy poll loop.
2762 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2765 hctx->poll_considered++;
2767 state = current->state;
2768 while (!need_resched()) {
2771 hctx->poll_invoked++;
2773 ret = q->mq_ops->poll(hctx, rq->tag);
2775 hctx->poll_success++;
2776 set_current_state(TASK_RUNNING);
2780 if (signal_pending_state(state, current))
2781 set_current_state(TASK_RUNNING);
2783 if (current->state == TASK_RUNNING)
2793 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2795 struct blk_mq_hw_ctx *hctx;
2796 struct blk_plug *plug;
2799 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2800 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2803 plug = current->plug;
2805 blk_flush_plug_list(plug, false);
2807 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2808 if (!blk_qc_t_is_internal(cookie))
2809 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2811 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2813 return __blk_mq_poll(hctx, rq);
2815 EXPORT_SYMBOL_GPL(blk_mq_poll);
2817 void blk_mq_disable_hotplug(void)
2819 mutex_lock(&all_q_mutex);
2822 void blk_mq_enable_hotplug(void)
2824 mutex_unlock(&all_q_mutex);
2827 static int __init blk_mq_init(void)
2829 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2830 blk_mq_hctx_notify_dead);
2832 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2833 blk_mq_queue_reinit_prepare,
2834 blk_mq_queue_reinit_dead);
2837 subsys_initcall(blk_mq_init);