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/delay.h>
25 #include <linux/crash_dump.h>
26 #include <linux/prefetch.h>
28 #include <trace/events/block.h>
30 #include <linux/blk-mq.h>
33 #include "blk-mq-tag.h"
36 #include "blk-mq-sched.h"
38 static DEFINE_MUTEX(all_q_mutex
);
39 static LIST_HEAD(all_q_list
);
42 * Check if any of the ctx's have pending work in this hardware queue
44 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
46 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
47 !list_empty_careful(&hctx
->dispatch
) ||
48 blk_mq_sched_has_work(hctx
);
52 * Mark this ctx as having pending work in this hardware queue
54 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
55 struct blk_mq_ctx
*ctx
)
57 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
58 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
61 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
62 struct blk_mq_ctx
*ctx
)
64 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
67 void blk_mq_freeze_queue_start(struct request_queue
*q
)
71 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
72 if (freeze_depth
== 1) {
73 percpu_ref_kill(&q
->q_usage_counter
);
74 blk_mq_run_hw_queues(q
, false);
77 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
79 static void blk_mq_freeze_queue_wait(struct request_queue
*q
)
81 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
85 * Guarantee no request is in use, so we can change any data structure of
86 * the queue afterward.
88 void blk_freeze_queue(struct request_queue
*q
)
91 * In the !blk_mq case we are only calling this to kill the
92 * q_usage_counter, otherwise this increases the freeze depth
93 * and waits for it to return to zero. For this reason there is
94 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
95 * exported to drivers as the only user for unfreeze is blk_mq.
97 blk_mq_freeze_queue_start(q
);
98 blk_mq_freeze_queue_wait(q
);
101 void blk_mq_freeze_queue(struct request_queue
*q
)
104 * ...just an alias to keep freeze and unfreeze actions balanced
105 * in the blk_mq_* namespace
109 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
111 void blk_mq_unfreeze_queue(struct request_queue
*q
)
115 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
116 WARN_ON_ONCE(freeze_depth
< 0);
118 percpu_ref_reinit(&q
->q_usage_counter
);
119 wake_up_all(&q
->mq_freeze_wq
);
122 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
125 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
128 * Note: this function does not prevent that the struct request end_io()
129 * callback function is invoked. Additionally, it is not prevented that
130 * new queue_rq() calls occur unless the queue has been stopped first.
132 void blk_mq_quiesce_queue(struct request_queue
*q
)
134 struct blk_mq_hw_ctx
*hctx
;
138 blk_mq_stop_hw_queues(q
);
140 queue_for_each_hw_ctx(q
, hctx
, i
) {
141 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
142 synchronize_srcu(&hctx
->queue_rq_srcu
);
149 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
151 void blk_mq_wake_waiters(struct request_queue
*q
)
153 struct blk_mq_hw_ctx
*hctx
;
156 queue_for_each_hw_ctx(q
, hctx
, i
)
157 if (blk_mq_hw_queue_mapped(hctx
))
158 blk_mq_tag_wakeup_all(hctx
->tags
, true);
161 * If we are called because the queue has now been marked as
162 * dying, we need to ensure that processes currently waiting on
163 * the queue are notified as well.
165 wake_up_all(&q
->mq_freeze_wq
);
168 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
170 return blk_mq_has_free_tags(hctx
->tags
);
172 EXPORT_SYMBOL(blk_mq_can_queue
);
174 void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
175 struct request
*rq
, unsigned int op
)
177 INIT_LIST_HEAD(&rq
->queuelist
);
178 /* csd/requeue_work/fifo_time is initialized before use */
182 if (blk_queue_io_stat(q
))
183 rq
->rq_flags
|= RQF_IO_STAT
;
184 /* do not touch atomic flags, it needs atomic ops against the timer */
186 INIT_HLIST_NODE(&rq
->hash
);
187 RB_CLEAR_NODE(&rq
->rb_node
);
190 rq
->start_time
= jiffies
;
191 #ifdef CONFIG_BLK_CGROUP
193 set_start_time_ns(rq
);
194 rq
->io_start_time_ns
= 0;
196 rq
->nr_phys_segments
= 0;
197 #if defined(CONFIG_BLK_DEV_INTEGRITY)
198 rq
->nr_integrity_segments
= 0;
201 /* tag was already set */
205 INIT_LIST_HEAD(&rq
->timeout_list
);
209 rq
->end_io_data
= NULL
;
212 ctx
->rq_dispatched
[op_is_sync(op
)]++;
214 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init
);
216 struct request
*__blk_mq_alloc_request(struct blk_mq_alloc_data
*data
,
222 tag
= blk_mq_get_tag(data
);
223 if (tag
!= BLK_MQ_TAG_FAIL
) {
224 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
226 rq
= tags
->static_rqs
[tag
];
228 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
230 rq
->internal_tag
= tag
;
232 if (blk_mq_tag_busy(data
->hctx
)) {
233 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
234 atomic_inc(&data
->hctx
->nr_active
);
237 rq
->internal_tag
= -1;
240 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
);
246 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request
);
248 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
251 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
255 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
259 rq
= blk_mq_sched_get_request(q
, NULL
, rw
, &alloc_data
);
261 blk_mq_put_ctx(alloc_data
.ctx
);
265 return ERR_PTR(-EWOULDBLOCK
);
268 rq
->__sector
= (sector_t
) -1;
269 rq
->bio
= rq
->biotail
= NULL
;
272 EXPORT_SYMBOL(blk_mq_alloc_request
);
274 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
275 unsigned int flags
, unsigned int hctx_idx
)
277 struct blk_mq_hw_ctx
*hctx
;
278 struct blk_mq_ctx
*ctx
;
280 struct blk_mq_alloc_data alloc_data
;
284 * If the tag allocator sleeps we could get an allocation for a
285 * different hardware context. No need to complicate the low level
286 * allocator for this for the rare use case of a command tied to
289 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
290 return ERR_PTR(-EINVAL
);
292 if (hctx_idx
>= q
->nr_hw_queues
)
293 return ERR_PTR(-EIO
);
295 ret
= blk_queue_enter(q
, true);
300 * Check if the hardware context is actually mapped to anything.
301 * If not tell the caller that it should skip this queue.
303 hctx
= q
->queue_hw_ctx
[hctx_idx
];
304 if (!blk_mq_hw_queue_mapped(hctx
)) {
308 ctx
= __blk_mq_get_ctx(q
, cpumask_first(hctx
->cpumask
));
310 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
311 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
323 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
325 void __blk_mq_finish_request(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
328 const int sched_tag
= rq
->internal_tag
;
329 struct request_queue
*q
= rq
->q
;
331 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
332 atomic_dec(&hctx
->nr_active
);
334 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
337 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
338 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
340 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
342 blk_mq_sched_completed_request(hctx
, rq
);
343 blk_mq_sched_restart_queues(hctx
);
347 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx
*hctx
,
350 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
352 ctx
->rq_completed
[rq_is_sync(rq
)]++;
353 __blk_mq_finish_request(hctx
, ctx
, rq
);
356 void blk_mq_finish_request(struct request
*rq
)
358 blk_mq_finish_hctx_request(blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
), rq
);
361 void blk_mq_free_request(struct request
*rq
)
363 blk_mq_sched_put_request(rq
);
365 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
367 inline void __blk_mq_end_request(struct request
*rq
, int error
)
369 blk_account_io_done(rq
);
372 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
373 rq
->end_io(rq
, error
);
375 if (unlikely(blk_bidi_rq(rq
)))
376 blk_mq_free_request(rq
->next_rq
);
377 blk_mq_free_request(rq
);
380 EXPORT_SYMBOL(__blk_mq_end_request
);
382 void blk_mq_end_request(struct request
*rq
, int error
)
384 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
386 __blk_mq_end_request(rq
, error
);
388 EXPORT_SYMBOL(blk_mq_end_request
);
390 static void __blk_mq_complete_request_remote(void *data
)
392 struct request
*rq
= data
;
394 rq
->q
->softirq_done_fn(rq
);
397 static void blk_mq_ipi_complete_request(struct request
*rq
)
399 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
403 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
404 rq
->q
->softirq_done_fn(rq
);
409 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
410 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
412 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
413 rq
->csd
.func
= __blk_mq_complete_request_remote
;
416 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
418 rq
->q
->softirq_done_fn(rq
);
423 static void blk_mq_stat_add(struct request
*rq
)
425 if (rq
->rq_flags
& RQF_STATS
) {
427 * We could rq->mq_ctx here, but there's less of a risk
428 * of races if we have the completion event add the stats
429 * to the local software queue.
431 struct blk_mq_ctx
*ctx
;
433 ctx
= __blk_mq_get_ctx(rq
->q
, raw_smp_processor_id());
434 blk_stat_add(&ctx
->stat
[rq_data_dir(rq
)], rq
);
438 static void __blk_mq_complete_request(struct request
*rq
)
440 struct request_queue
*q
= rq
->q
;
444 if (!q
->softirq_done_fn
)
445 blk_mq_end_request(rq
, rq
->errors
);
447 blk_mq_ipi_complete_request(rq
);
451 * blk_mq_complete_request - end I/O on a request
452 * @rq: the request being processed
455 * Ends all I/O on a request. It does not handle partial completions.
456 * The actual completion happens out-of-order, through a IPI handler.
458 void blk_mq_complete_request(struct request
*rq
, int error
)
460 struct request_queue
*q
= rq
->q
;
462 if (unlikely(blk_should_fake_timeout(q
)))
464 if (!blk_mark_rq_complete(rq
)) {
466 __blk_mq_complete_request(rq
);
469 EXPORT_SYMBOL(blk_mq_complete_request
);
471 int blk_mq_request_started(struct request
*rq
)
473 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
475 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
477 void blk_mq_start_request(struct request
*rq
)
479 struct request_queue
*q
= rq
->q
;
481 blk_mq_sched_started_request(rq
);
483 trace_block_rq_issue(q
, rq
);
485 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
486 blk_stat_set_issue_time(&rq
->issue_stat
);
487 rq
->rq_flags
|= RQF_STATS
;
488 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
494 * Ensure that ->deadline is visible before set the started
495 * flag and clear the completed flag.
497 smp_mb__before_atomic();
500 * Mark us as started and clear complete. Complete might have been
501 * set if requeue raced with timeout, which then marked it as
502 * complete. So be sure to clear complete again when we start
503 * the request, otherwise we'll ignore the completion event.
505 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
506 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
507 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
508 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
510 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
512 * Make sure space for the drain appears. We know we can do
513 * this because max_hw_segments has been adjusted to be one
514 * fewer than the device can handle.
516 rq
->nr_phys_segments
++;
519 EXPORT_SYMBOL(blk_mq_start_request
);
521 static void __blk_mq_requeue_request(struct request
*rq
)
523 struct request_queue
*q
= rq
->q
;
525 trace_block_rq_requeue(q
, rq
);
526 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
527 blk_mq_sched_requeue_request(rq
);
529 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
530 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
531 rq
->nr_phys_segments
--;
535 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
537 __blk_mq_requeue_request(rq
);
539 BUG_ON(blk_queued_rq(rq
));
540 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
542 EXPORT_SYMBOL(blk_mq_requeue_request
);
544 static void blk_mq_requeue_work(struct work_struct
*work
)
546 struct request_queue
*q
=
547 container_of(work
, struct request_queue
, requeue_work
.work
);
549 struct request
*rq
, *next
;
552 spin_lock_irqsave(&q
->requeue_lock
, flags
);
553 list_splice_init(&q
->requeue_list
, &rq_list
);
554 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
556 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
557 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
560 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
561 list_del_init(&rq
->queuelist
);
562 blk_mq_sched_insert_request(rq
, true, false, false, true);
565 while (!list_empty(&rq_list
)) {
566 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
567 list_del_init(&rq
->queuelist
);
568 blk_mq_sched_insert_request(rq
, false, false, false, true);
571 blk_mq_run_hw_queues(q
, false);
574 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
575 bool kick_requeue_list
)
577 struct request_queue
*q
= rq
->q
;
581 * We abuse this flag that is otherwise used by the I/O scheduler to
582 * request head insertation from the workqueue.
584 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
586 spin_lock_irqsave(&q
->requeue_lock
, flags
);
588 rq
->rq_flags
|= RQF_SOFTBARRIER
;
589 list_add(&rq
->queuelist
, &q
->requeue_list
);
591 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
593 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
595 if (kick_requeue_list
)
596 blk_mq_kick_requeue_list(q
);
598 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
600 void blk_mq_kick_requeue_list(struct request_queue
*q
)
602 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
604 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
606 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
609 kblockd_schedule_delayed_work(&q
->requeue_work
,
610 msecs_to_jiffies(msecs
));
612 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
614 void blk_mq_abort_requeue_list(struct request_queue
*q
)
619 spin_lock_irqsave(&q
->requeue_lock
, flags
);
620 list_splice_init(&q
->requeue_list
, &rq_list
);
621 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
623 while (!list_empty(&rq_list
)) {
626 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
627 list_del_init(&rq
->queuelist
);
629 blk_mq_end_request(rq
, rq
->errors
);
632 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
634 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
636 if (tag
< tags
->nr_tags
) {
637 prefetch(tags
->rqs
[tag
]);
638 return tags
->rqs
[tag
];
643 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
645 struct blk_mq_timeout_data
{
647 unsigned int next_set
;
650 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
652 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
653 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
656 * We know that complete is set at this point. If STARTED isn't set
657 * anymore, then the request isn't active and the "timeout" should
658 * just be ignored. This can happen due to the bitflag ordering.
659 * Timeout first checks if STARTED is set, and if it is, assumes
660 * the request is active. But if we race with completion, then
661 * we both flags will get cleared. So check here again, and ignore
662 * a timeout event with a request that isn't active.
664 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
668 ret
= ops
->timeout(req
, reserved
);
672 __blk_mq_complete_request(req
);
674 case BLK_EH_RESET_TIMER
:
676 blk_clear_rq_complete(req
);
678 case BLK_EH_NOT_HANDLED
:
681 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
686 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
687 struct request
*rq
, void *priv
, bool reserved
)
689 struct blk_mq_timeout_data
*data
= priv
;
691 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
693 * If a request wasn't started before the queue was
694 * marked dying, kill it here or it'll go unnoticed.
696 if (unlikely(blk_queue_dying(rq
->q
))) {
698 blk_mq_end_request(rq
, rq
->errors
);
703 if (time_after_eq(jiffies
, rq
->deadline
)) {
704 if (!blk_mark_rq_complete(rq
))
705 blk_mq_rq_timed_out(rq
, reserved
);
706 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
707 data
->next
= rq
->deadline
;
712 static void blk_mq_timeout_work(struct work_struct
*work
)
714 struct request_queue
*q
=
715 container_of(work
, struct request_queue
, timeout_work
);
716 struct blk_mq_timeout_data data
= {
722 /* A deadlock might occur if a request is stuck requiring a
723 * timeout at the same time a queue freeze is waiting
724 * completion, since the timeout code would not be able to
725 * acquire the queue reference here.
727 * That's why we don't use blk_queue_enter here; instead, we use
728 * percpu_ref_tryget directly, because we need to be able to
729 * obtain a reference even in the short window between the queue
730 * starting to freeze, by dropping the first reference in
731 * blk_mq_freeze_queue_start, and the moment the last request is
732 * consumed, marked by the instant q_usage_counter reaches
735 if (!percpu_ref_tryget(&q
->q_usage_counter
))
738 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
741 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
742 mod_timer(&q
->timeout
, data
.next
);
744 struct blk_mq_hw_ctx
*hctx
;
746 queue_for_each_hw_ctx(q
, hctx
, i
) {
747 /* the hctx may be unmapped, so check it here */
748 if (blk_mq_hw_queue_mapped(hctx
))
749 blk_mq_tag_idle(hctx
);
756 * Reverse check our software queue for entries that we could potentially
757 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
758 * too much time checking for merges.
760 static bool blk_mq_attempt_merge(struct request_queue
*q
,
761 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
766 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
772 if (!blk_rq_merge_ok(rq
, bio
))
775 switch (blk_try_merge(rq
, bio
)) {
776 case ELEVATOR_BACK_MERGE
:
777 if (blk_mq_sched_allow_merge(q
, rq
, bio
))
778 merged
= bio_attempt_back_merge(q
, rq
, bio
);
780 case ELEVATOR_FRONT_MERGE
:
781 if (blk_mq_sched_allow_merge(q
, rq
, bio
))
782 merged
= bio_attempt_front_merge(q
, rq
, bio
);
784 case ELEVATOR_DISCARD_MERGE
:
785 merged
= bio_attempt_discard_merge(q
, rq
, bio
);
799 struct flush_busy_ctx_data
{
800 struct blk_mq_hw_ctx
*hctx
;
801 struct list_head
*list
;
804 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
806 struct flush_busy_ctx_data
*flush_data
= data
;
807 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
808 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
810 sbitmap_clear_bit(sb
, bitnr
);
811 spin_lock(&ctx
->lock
);
812 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
813 spin_unlock(&ctx
->lock
);
818 * Process software queues that have been marked busy, splicing them
819 * to the for-dispatch
821 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
823 struct flush_busy_ctx_data data
= {
828 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
830 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
832 static inline unsigned int queued_to_index(unsigned int queued
)
837 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
840 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
843 struct blk_mq_alloc_data data
= {
845 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
846 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
856 rq
->tag
= blk_mq_get_tag(&data
);
858 if (blk_mq_tag_busy(data
.hctx
)) {
859 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
860 atomic_inc(&data
.hctx
->nr_active
);
862 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
869 static void blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
872 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
875 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
878 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
879 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
880 atomic_dec(&hctx
->nr_active
);
885 * If we fail getting a driver tag because all the driver tags are already
886 * assigned and on the dispatch list, BUT the first entry does not have a
887 * tag, then we could deadlock. For that case, move entries with assigned
888 * driver tags to the front, leaving the set of tagged requests in the
889 * same order, and the untagged set in the same order.
891 static bool reorder_tags_to_front(struct list_head
*list
)
893 struct request
*rq
, *tmp
, *first
= NULL
;
895 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
899 list_move(&rq
->queuelist
, list
);
905 return first
!= NULL
;
908 static int blk_mq_dispatch_wake(wait_queue_t
*wait
, unsigned mode
, int flags
,
911 struct blk_mq_hw_ctx
*hctx
;
913 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
915 list_del(&wait
->task_list
);
916 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
917 blk_mq_run_hw_queue(hctx
, true);
921 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
923 struct sbq_wait_state
*ws
;
926 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
927 * The thread which wins the race to grab this bit adds the hardware
928 * queue to the wait queue.
930 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
931 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
934 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
935 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
938 * As soon as this returns, it's no longer safe to fiddle with
939 * hctx->dispatch_wait, since a completion can wake up the wait queue
940 * and unlock the bit.
942 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
946 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
948 struct request_queue
*q
= hctx
->queue
;
950 LIST_HEAD(driver_list
);
951 struct list_head
*dptr
;
952 int queued
, ret
= BLK_MQ_RQ_QUEUE_OK
;
955 * Start off with dptr being NULL, so we start the first request
956 * immediately, even if we have more pending.
961 * Now process all the entries, sending them to the driver.
964 while (!list_empty(list
)) {
965 struct blk_mq_queue_data bd
;
967 rq
= list_first_entry(list
, struct request
, queuelist
);
968 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
969 if (!queued
&& reorder_tags_to_front(list
))
973 * The initial allocation attempt failed, so we need to
974 * rerun the hardware queue when a tag is freed.
976 if (blk_mq_dispatch_wait_add(hctx
)) {
978 * It's possible that a tag was freed in the
979 * window between the allocation failure and
980 * adding the hardware queue to the wait queue.
982 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
989 list_del_init(&rq
->queuelist
);
993 bd
.last
= list_empty(list
);
995 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
997 case BLK_MQ_RQ_QUEUE_OK
:
1000 case BLK_MQ_RQ_QUEUE_BUSY
:
1001 blk_mq_put_driver_tag(hctx
, rq
);
1002 list_add(&rq
->queuelist
, list
);
1003 __blk_mq_requeue_request(rq
);
1006 pr_err("blk-mq: bad return on queue: %d\n", ret
);
1007 case BLK_MQ_RQ_QUEUE_ERROR
:
1009 blk_mq_end_request(rq
, rq
->errors
);
1013 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
1017 * We've done the first request. If we have more than 1
1018 * left in the list, set dptr to defer issue.
1020 if (!dptr
&& list
->next
!= list
->prev
)
1021 dptr
= &driver_list
;
1024 hctx
->dispatched
[queued_to_index(queued
)]++;
1027 * Any items that need requeuing? Stuff them into hctx->dispatch,
1028 * that is where we will continue on next queue run.
1030 if (!list_empty(list
)) {
1031 spin_lock(&hctx
->lock
);
1032 list_splice_init(list
, &hctx
->dispatch
);
1033 spin_unlock(&hctx
->lock
);
1036 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1037 * it's possible the queue is stopped and restarted again
1038 * before this. Queue restart will dispatch requests. And since
1039 * requests in rq_list aren't added into hctx->dispatch yet,
1040 * the requests in rq_list might get lost.
1042 * blk_mq_run_hw_queue() already checks the STOPPED bit
1044 * If RESTART or TAG_WAITING is set, then let completion restart
1045 * the queue instead of potentially looping here.
1047 if (!blk_mq_sched_needs_restart(hctx
) &&
1048 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1049 blk_mq_run_hw_queue(hctx
, true);
1055 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1059 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1060 cpu_online(hctx
->next_cpu
));
1062 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1064 blk_mq_sched_dispatch_requests(hctx
);
1067 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1068 blk_mq_sched_dispatch_requests(hctx
);
1069 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1074 * It'd be great if the workqueue API had a way to pass
1075 * in a mask and had some smarts for more clever placement.
1076 * For now we just round-robin here, switching for every
1077 * BLK_MQ_CPU_WORK_BATCH queued items.
1079 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1081 if (hctx
->queue
->nr_hw_queues
== 1)
1082 return WORK_CPU_UNBOUND
;
1084 if (--hctx
->next_cpu_batch
<= 0) {
1087 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1088 if (next_cpu
>= nr_cpu_ids
)
1089 next_cpu
= cpumask_first(hctx
->cpumask
);
1091 hctx
->next_cpu
= next_cpu
;
1092 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1095 return hctx
->next_cpu
;
1098 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1100 if (unlikely(blk_mq_hctx_stopped(hctx
) ||
1101 !blk_mq_hw_queue_mapped(hctx
)))
1104 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1105 int cpu
= get_cpu();
1106 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1107 __blk_mq_run_hw_queue(hctx
);
1115 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
);
1118 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1120 struct blk_mq_hw_ctx
*hctx
;
1123 queue_for_each_hw_ctx(q
, hctx
, i
) {
1124 if (!blk_mq_hctx_has_pending(hctx
) ||
1125 blk_mq_hctx_stopped(hctx
))
1128 blk_mq_run_hw_queue(hctx
, async
);
1131 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1134 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1135 * @q: request queue.
1137 * The caller is responsible for serializing this function against
1138 * blk_mq_{start,stop}_hw_queue().
1140 bool blk_mq_queue_stopped(struct request_queue
*q
)
1142 struct blk_mq_hw_ctx
*hctx
;
1145 queue_for_each_hw_ctx(q
, hctx
, i
)
1146 if (blk_mq_hctx_stopped(hctx
))
1151 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1153 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1155 cancel_work(&hctx
->run_work
);
1156 cancel_delayed_work(&hctx
->delay_work
);
1157 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1159 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1161 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1163 struct blk_mq_hw_ctx
*hctx
;
1166 queue_for_each_hw_ctx(q
, hctx
, i
)
1167 blk_mq_stop_hw_queue(hctx
);
1169 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1171 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1173 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1175 blk_mq_run_hw_queue(hctx
, false);
1177 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1179 void blk_mq_start_hw_queues(struct request_queue
*q
)
1181 struct blk_mq_hw_ctx
*hctx
;
1184 queue_for_each_hw_ctx(q
, hctx
, i
)
1185 blk_mq_start_hw_queue(hctx
);
1187 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1189 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1191 if (!blk_mq_hctx_stopped(hctx
))
1194 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1195 blk_mq_run_hw_queue(hctx
, async
);
1197 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1199 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1201 struct blk_mq_hw_ctx
*hctx
;
1204 queue_for_each_hw_ctx(q
, hctx
, i
)
1205 blk_mq_start_stopped_hw_queue(hctx
, async
);
1207 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1209 static void blk_mq_run_work_fn(struct work_struct
*work
)
1211 struct blk_mq_hw_ctx
*hctx
;
1213 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
);
1215 __blk_mq_run_hw_queue(hctx
);
1218 static void blk_mq_delay_work_fn(struct work_struct
*work
)
1220 struct blk_mq_hw_ctx
*hctx
;
1222 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
1224 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1225 __blk_mq_run_hw_queue(hctx
);
1228 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1230 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1233 blk_mq_stop_hw_queue(hctx
);
1234 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1235 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
1237 EXPORT_SYMBOL(blk_mq_delay_queue
);
1239 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1243 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1245 trace_block_rq_insert(hctx
->queue
, rq
);
1248 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1250 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1253 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1256 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1258 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1259 blk_mq_hctx_mark_pending(hctx
, ctx
);
1262 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1263 struct list_head
*list
)
1267 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1270 spin_lock(&ctx
->lock
);
1271 while (!list_empty(list
)) {
1274 rq
= list_first_entry(list
, struct request
, queuelist
);
1275 BUG_ON(rq
->mq_ctx
!= ctx
);
1276 list_del_init(&rq
->queuelist
);
1277 __blk_mq_insert_req_list(hctx
, rq
, false);
1279 blk_mq_hctx_mark_pending(hctx
, ctx
);
1280 spin_unlock(&ctx
->lock
);
1283 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1285 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1286 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1288 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1289 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1290 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1293 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1295 struct blk_mq_ctx
*this_ctx
;
1296 struct request_queue
*this_q
;
1299 LIST_HEAD(ctx_list
);
1302 list_splice_init(&plug
->mq_list
, &list
);
1304 list_sort(NULL
, &list
, plug_ctx_cmp
);
1310 while (!list_empty(&list
)) {
1311 rq
= list_entry_rq(list
.next
);
1312 list_del_init(&rq
->queuelist
);
1314 if (rq
->mq_ctx
!= this_ctx
) {
1316 trace_block_unplug(this_q
, depth
, from_schedule
);
1317 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1322 this_ctx
= rq
->mq_ctx
;
1328 list_add_tail(&rq
->queuelist
, &ctx_list
);
1332 * If 'this_ctx' is set, we know we have entries to complete
1333 * on 'ctx_list'. Do those.
1336 trace_block_unplug(this_q
, depth
, from_schedule
);
1337 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1342 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1344 init_request_from_bio(rq
, bio
);
1346 blk_account_io_start(rq
, true);
1349 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1351 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1352 !blk_queue_nomerges(hctx
->queue
);
1355 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1356 struct blk_mq_ctx
*ctx
,
1357 struct request
*rq
, struct bio
*bio
)
1359 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1360 blk_mq_bio_to_request(rq
, bio
);
1361 spin_lock(&ctx
->lock
);
1363 __blk_mq_insert_request(hctx
, rq
, false);
1364 spin_unlock(&ctx
->lock
);
1367 struct request_queue
*q
= hctx
->queue
;
1369 spin_lock(&ctx
->lock
);
1370 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1371 blk_mq_bio_to_request(rq
, bio
);
1375 spin_unlock(&ctx
->lock
);
1376 __blk_mq_finish_request(hctx
, ctx
, rq
);
1381 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1384 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1386 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1389 static void blk_mq_try_issue_directly(struct request
*rq
, blk_qc_t
*cookie
)
1391 struct request_queue
*q
= rq
->q
;
1392 struct blk_mq_queue_data bd
= {
1397 struct blk_mq_hw_ctx
*hctx
;
1398 blk_qc_t new_cookie
;
1404 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1407 new_cookie
= request_to_qc_t(hctx
, rq
);
1410 * For OK queue, we are done. For error, kill it. Any other
1411 * error (busy), just add it to our list as we previously
1414 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1415 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1416 *cookie
= new_cookie
;
1420 __blk_mq_requeue_request(rq
);
1422 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1423 *cookie
= BLK_QC_T_NONE
;
1425 blk_mq_end_request(rq
, rq
->errors
);
1430 blk_mq_sched_insert_request(rq
, false, true, true, false);
1434 * Multiple hardware queue variant. This will not use per-process plugs,
1435 * but will attempt to bypass the hctx queueing if we can go straight to
1436 * hardware for SYNC IO.
1438 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1440 const int is_sync
= op_is_sync(bio
->bi_opf
);
1441 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1442 struct blk_mq_alloc_data data
= { .flags
= 0 };
1444 unsigned int request_count
= 0, srcu_idx
;
1445 struct blk_plug
*plug
;
1446 struct request
*same_queue_rq
= NULL
;
1448 unsigned int wb_acct
;
1450 blk_queue_bounce(q
, &bio
);
1452 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1454 return BLK_QC_T_NONE
;
1457 blk_queue_split(q
, &bio
, q
->bio_split
);
1459 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1460 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1461 return BLK_QC_T_NONE
;
1463 if (blk_mq_sched_bio_merge(q
, bio
))
1464 return BLK_QC_T_NONE
;
1466 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1468 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1470 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1471 if (unlikely(!rq
)) {
1472 __wbt_done(q
->rq_wb
, wb_acct
);
1473 return BLK_QC_T_NONE
;
1476 wbt_track(&rq
->issue_stat
, wb_acct
);
1478 cookie
= request_to_qc_t(data
.hctx
, rq
);
1480 if (unlikely(is_flush_fua
)) {
1483 blk_mq_bio_to_request(rq
, bio
);
1484 blk_insert_flush(rq
);
1488 plug
= current
->plug
;
1490 * If the driver supports defer issued based on 'last', then
1491 * queue it up like normal since we can potentially save some
1494 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1495 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1496 struct request
*old_rq
= NULL
;
1498 blk_mq_bio_to_request(rq
, bio
);
1501 * We do limited plugging. If the bio can be merged, do that.
1502 * Otherwise the existing request in the plug list will be
1503 * issued. So the plug list will have one request at most
1507 * The plug list might get flushed before this. If that
1508 * happens, same_queue_rq is invalid and plug list is
1511 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1512 old_rq
= same_queue_rq
;
1513 list_del_init(&old_rq
->queuelist
);
1515 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1516 } else /* is_sync */
1518 blk_mq_put_ctx(data
.ctx
);
1522 if (!(data
.hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1524 blk_mq_try_issue_directly(old_rq
, &cookie
);
1527 srcu_idx
= srcu_read_lock(&data
.hctx
->queue_rq_srcu
);
1528 blk_mq_try_issue_directly(old_rq
, &cookie
);
1529 srcu_read_unlock(&data
.hctx
->queue_rq_srcu
, srcu_idx
);
1536 blk_mq_put_ctx(data
.ctx
);
1537 blk_mq_bio_to_request(rq
, bio
);
1538 blk_mq_sched_insert_request(rq
, false, true,
1539 !is_sync
|| is_flush_fua
, true);
1542 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1544 * For a SYNC request, send it to the hardware immediately. For
1545 * an ASYNC request, just ensure that we run it later on. The
1546 * latter allows for merging opportunities and more efficient
1550 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1552 blk_mq_put_ctx(data
.ctx
);
1558 * Single hardware queue variant. This will attempt to use any per-process
1559 * plug for merging and IO deferral.
1561 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1563 const int is_sync
= op_is_sync(bio
->bi_opf
);
1564 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1565 struct blk_plug
*plug
;
1566 unsigned int request_count
= 0;
1567 struct blk_mq_alloc_data data
= { .flags
= 0 };
1570 unsigned int wb_acct
;
1572 blk_queue_bounce(q
, &bio
);
1574 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1576 return BLK_QC_T_NONE
;
1579 blk_queue_split(q
, &bio
, q
->bio_split
);
1581 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1582 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1583 return BLK_QC_T_NONE
;
1585 request_count
= blk_plug_queued_count(q
);
1587 if (blk_mq_sched_bio_merge(q
, bio
))
1588 return BLK_QC_T_NONE
;
1590 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1592 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1594 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1595 if (unlikely(!rq
)) {
1596 __wbt_done(q
->rq_wb
, wb_acct
);
1597 return BLK_QC_T_NONE
;
1600 wbt_track(&rq
->issue_stat
, wb_acct
);
1602 cookie
= request_to_qc_t(data
.hctx
, rq
);
1604 if (unlikely(is_flush_fua
)) {
1607 blk_mq_bio_to_request(rq
, bio
);
1608 blk_insert_flush(rq
);
1613 * A task plug currently exists. Since this is completely lockless,
1614 * utilize that to temporarily store requests until the task is
1615 * either done or scheduled away.
1617 plug
= current
->plug
;
1619 struct request
*last
= NULL
;
1621 blk_mq_bio_to_request(rq
, bio
);
1624 * @request_count may become stale because of schedule
1625 * out, so check the list again.
1627 if (list_empty(&plug
->mq_list
))
1630 trace_block_plug(q
);
1632 last
= list_entry_rq(plug
->mq_list
.prev
);
1634 blk_mq_put_ctx(data
.ctx
);
1636 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1637 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1638 blk_flush_plug_list(plug
, false);
1639 trace_block_plug(q
);
1642 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1648 blk_mq_put_ctx(data
.ctx
);
1649 blk_mq_bio_to_request(rq
, bio
);
1650 blk_mq_sched_insert_request(rq
, false, true,
1651 !is_sync
|| is_flush_fua
, true);
1654 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1656 * For a SYNC request, send it to the hardware immediately. For
1657 * an ASYNC request, just ensure that we run it later on. The
1658 * latter allows for merging opportunities and more efficient
1662 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1665 blk_mq_put_ctx(data
.ctx
);
1670 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1671 unsigned int hctx_idx
)
1675 if (tags
->rqs
&& set
->ops
->exit_request
) {
1678 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1679 struct request
*rq
= tags
->static_rqs
[i
];
1683 set
->ops
->exit_request(set
->driver_data
, rq
,
1685 tags
->static_rqs
[i
] = NULL
;
1689 while (!list_empty(&tags
->page_list
)) {
1690 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1691 list_del_init(&page
->lru
);
1693 * Remove kmemleak object previously allocated in
1694 * blk_mq_init_rq_map().
1696 kmemleak_free(page_address(page
));
1697 __free_pages(page
, page
->private);
1701 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1705 kfree(tags
->static_rqs
);
1706 tags
->static_rqs
= NULL
;
1708 blk_mq_free_tags(tags
);
1711 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1712 unsigned int hctx_idx
,
1713 unsigned int nr_tags
,
1714 unsigned int reserved_tags
)
1716 struct blk_mq_tags
*tags
;
1718 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
,
1720 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1724 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1725 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1728 blk_mq_free_tags(tags
);
1732 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1733 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1735 if (!tags
->static_rqs
) {
1737 blk_mq_free_tags(tags
);
1744 static size_t order_to_size(unsigned int order
)
1746 return (size_t)PAGE_SIZE
<< order
;
1749 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1750 unsigned int hctx_idx
, unsigned int depth
)
1752 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1753 size_t rq_size
, left
;
1755 INIT_LIST_HEAD(&tags
->page_list
);
1758 * rq_size is the size of the request plus driver payload, rounded
1759 * to the cacheline size
1761 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1763 left
= rq_size
* depth
;
1765 for (i
= 0; i
< depth
; ) {
1766 int this_order
= max_order
;
1771 while (this_order
&& left
< order_to_size(this_order
- 1))
1775 page
= alloc_pages_node(set
->numa_node
,
1776 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1782 if (order_to_size(this_order
) < rq_size
)
1789 page
->private = this_order
;
1790 list_add_tail(&page
->lru
, &tags
->page_list
);
1792 p
= page_address(page
);
1794 * Allow kmemleak to scan these pages as they contain pointers
1795 * to additional allocations like via ops->init_request().
1797 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1798 entries_per_page
= order_to_size(this_order
) / rq_size
;
1799 to_do
= min(entries_per_page
, depth
- i
);
1800 left
-= to_do
* rq_size
;
1801 for (j
= 0; j
< to_do
; j
++) {
1802 struct request
*rq
= p
;
1804 tags
->static_rqs
[i
] = rq
;
1805 if (set
->ops
->init_request
) {
1806 if (set
->ops
->init_request(set
->driver_data
,
1809 tags
->static_rqs
[i
] = NULL
;
1821 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1826 * 'cpu' is going away. splice any existing rq_list entries from this
1827 * software queue to the hw queue dispatch list, and ensure that it
1830 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1832 struct blk_mq_hw_ctx
*hctx
;
1833 struct blk_mq_ctx
*ctx
;
1836 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1837 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1839 spin_lock(&ctx
->lock
);
1840 if (!list_empty(&ctx
->rq_list
)) {
1841 list_splice_init(&ctx
->rq_list
, &tmp
);
1842 blk_mq_hctx_clear_pending(hctx
, ctx
);
1844 spin_unlock(&ctx
->lock
);
1846 if (list_empty(&tmp
))
1849 spin_lock(&hctx
->lock
);
1850 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1851 spin_unlock(&hctx
->lock
);
1853 blk_mq_run_hw_queue(hctx
, true);
1857 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1859 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1863 /* hctx->ctxs will be freed in queue's release handler */
1864 static void blk_mq_exit_hctx(struct request_queue
*q
,
1865 struct blk_mq_tag_set
*set
,
1866 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1868 unsigned flush_start_tag
= set
->queue_depth
;
1870 blk_mq_tag_idle(hctx
);
1872 if (set
->ops
->exit_request
)
1873 set
->ops
->exit_request(set
->driver_data
,
1874 hctx
->fq
->flush_rq
, hctx_idx
,
1875 flush_start_tag
+ hctx_idx
);
1877 if (set
->ops
->exit_hctx
)
1878 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1880 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1881 cleanup_srcu_struct(&hctx
->queue_rq_srcu
);
1883 blk_mq_remove_cpuhp(hctx
);
1884 blk_free_flush_queue(hctx
->fq
);
1885 sbitmap_free(&hctx
->ctx_map
);
1888 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1889 struct blk_mq_tag_set
*set
, int nr_queue
)
1891 struct blk_mq_hw_ctx
*hctx
;
1894 queue_for_each_hw_ctx(q
, hctx
, i
) {
1897 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1901 static void blk_mq_free_hw_queues(struct request_queue
*q
,
1902 struct blk_mq_tag_set
*set
)
1904 struct blk_mq_hw_ctx
*hctx
;
1907 queue_for_each_hw_ctx(q
, hctx
, i
)
1908 free_cpumask_var(hctx
->cpumask
);
1911 static int blk_mq_init_hctx(struct request_queue
*q
,
1912 struct blk_mq_tag_set
*set
,
1913 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1916 unsigned flush_start_tag
= set
->queue_depth
;
1918 node
= hctx
->numa_node
;
1919 if (node
== NUMA_NO_NODE
)
1920 node
= hctx
->numa_node
= set
->numa_node
;
1922 INIT_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1923 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1924 spin_lock_init(&hctx
->lock
);
1925 INIT_LIST_HEAD(&hctx
->dispatch
);
1927 hctx
->queue_num
= hctx_idx
;
1928 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1930 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1932 hctx
->tags
= set
->tags
[hctx_idx
];
1935 * Allocate space for all possible cpus to avoid allocation at
1938 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1941 goto unregister_cpu_notifier
;
1943 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1949 if (set
->ops
->init_hctx
&&
1950 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1953 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1957 if (set
->ops
->init_request
&&
1958 set
->ops
->init_request(set
->driver_data
,
1959 hctx
->fq
->flush_rq
, hctx_idx
,
1960 flush_start_tag
+ hctx_idx
, node
))
1963 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1964 init_srcu_struct(&hctx
->queue_rq_srcu
);
1971 if (set
->ops
->exit_hctx
)
1972 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1974 sbitmap_free(&hctx
->ctx_map
);
1977 unregister_cpu_notifier
:
1978 blk_mq_remove_cpuhp(hctx
);
1982 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1983 unsigned int nr_hw_queues
)
1987 for_each_possible_cpu(i
) {
1988 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1989 struct blk_mq_hw_ctx
*hctx
;
1991 memset(__ctx
, 0, sizeof(*__ctx
));
1993 spin_lock_init(&__ctx
->lock
);
1994 INIT_LIST_HEAD(&__ctx
->rq_list
);
1996 blk_stat_init(&__ctx
->stat
[BLK_STAT_READ
]);
1997 blk_stat_init(&__ctx
->stat
[BLK_STAT_WRITE
]);
1999 /* If the cpu isn't online, the cpu is mapped to first hctx */
2003 hctx
= blk_mq_map_queue(q
, i
);
2006 * Set local node, IFF we have more than one hw queue. If
2007 * not, we remain on the home node of the device
2009 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2010 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2014 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2018 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2019 set
->queue_depth
, set
->reserved_tags
);
2020 if (!set
->tags
[hctx_idx
])
2023 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2028 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2029 set
->tags
[hctx_idx
] = NULL
;
2033 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2034 unsigned int hctx_idx
)
2036 if (set
->tags
[hctx_idx
]) {
2037 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2038 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2039 set
->tags
[hctx_idx
] = NULL
;
2043 static void blk_mq_map_swqueue(struct request_queue
*q
,
2044 const struct cpumask
*online_mask
)
2046 unsigned int i
, hctx_idx
;
2047 struct blk_mq_hw_ctx
*hctx
;
2048 struct blk_mq_ctx
*ctx
;
2049 struct blk_mq_tag_set
*set
= q
->tag_set
;
2052 * Avoid others reading imcomplete hctx->cpumask through sysfs
2054 mutex_lock(&q
->sysfs_lock
);
2056 queue_for_each_hw_ctx(q
, hctx
, i
) {
2057 cpumask_clear(hctx
->cpumask
);
2062 * Map software to hardware queues
2064 for_each_possible_cpu(i
) {
2065 /* If the cpu isn't online, the cpu is mapped to first hctx */
2066 if (!cpumask_test_cpu(i
, online_mask
))
2069 hctx_idx
= q
->mq_map
[i
];
2070 /* unmapped hw queue can be remapped after CPU topo changed */
2071 if (!set
->tags
[hctx_idx
] &&
2072 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2074 * If tags initialization fail for some hctx,
2075 * that hctx won't be brought online. In this
2076 * case, remap the current ctx to hctx[0] which
2077 * is guaranteed to always have tags allocated
2082 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2083 hctx
= blk_mq_map_queue(q
, i
);
2085 cpumask_set_cpu(i
, hctx
->cpumask
);
2086 ctx
->index_hw
= hctx
->nr_ctx
;
2087 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2090 mutex_unlock(&q
->sysfs_lock
);
2092 queue_for_each_hw_ctx(q
, hctx
, i
) {
2094 * If no software queues are mapped to this hardware queue,
2095 * disable it and free the request entries.
2097 if (!hctx
->nr_ctx
) {
2098 /* Never unmap queue 0. We need it as a
2099 * fallback in case of a new remap fails
2102 if (i
&& set
->tags
[i
])
2103 blk_mq_free_map_and_requests(set
, i
);
2109 hctx
->tags
= set
->tags
[i
];
2110 WARN_ON(!hctx
->tags
);
2113 * Set the map size to the number of mapped software queues.
2114 * This is more accurate and more efficient than looping
2115 * over all possibly mapped software queues.
2117 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2120 * Initialize batch roundrobin counts
2122 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2123 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2127 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2129 struct blk_mq_hw_ctx
*hctx
;
2132 queue_for_each_hw_ctx(q
, hctx
, i
) {
2134 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2136 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2140 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
2142 struct request_queue
*q
;
2144 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2145 blk_mq_freeze_queue(q
);
2146 queue_set_hctx_shared(q
, shared
);
2147 blk_mq_unfreeze_queue(q
);
2151 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2153 struct blk_mq_tag_set
*set
= q
->tag_set
;
2155 mutex_lock(&set
->tag_list_lock
);
2156 list_del_init(&q
->tag_set_list
);
2157 if (list_is_singular(&set
->tag_list
)) {
2158 /* just transitioned to unshared */
2159 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2160 /* update existing queue */
2161 blk_mq_update_tag_set_depth(set
, false);
2163 mutex_unlock(&set
->tag_list_lock
);
2166 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2167 struct request_queue
*q
)
2171 mutex_lock(&set
->tag_list_lock
);
2173 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2174 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2175 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2176 /* update existing queue */
2177 blk_mq_update_tag_set_depth(set
, true);
2179 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2180 queue_set_hctx_shared(q
, true);
2181 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
2183 mutex_unlock(&set
->tag_list_lock
);
2187 * It is the actual release handler for mq, but we do it from
2188 * request queue's release handler for avoiding use-after-free
2189 * and headache because q->mq_kobj shouldn't have been introduced,
2190 * but we can't group ctx/kctx kobj without it.
2192 void blk_mq_release(struct request_queue
*q
)
2194 struct blk_mq_hw_ctx
*hctx
;
2197 blk_mq_sched_teardown(q
);
2199 /* hctx kobj stays in hctx */
2200 queue_for_each_hw_ctx(q
, hctx
, i
) {
2209 kfree(q
->queue_hw_ctx
);
2211 /* ctx kobj stays in queue_ctx */
2212 free_percpu(q
->queue_ctx
);
2215 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2217 struct request_queue
*uninit_q
, *q
;
2219 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2221 return ERR_PTR(-ENOMEM
);
2223 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2225 blk_cleanup_queue(uninit_q
);
2229 EXPORT_SYMBOL(blk_mq_init_queue
);
2231 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2232 struct request_queue
*q
)
2235 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2237 blk_mq_sysfs_unregister(q
);
2238 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2244 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2245 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2250 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2257 atomic_set(&hctxs
[i
]->nr_active
, 0);
2258 hctxs
[i
]->numa_node
= node
;
2259 hctxs
[i
]->queue_num
= i
;
2261 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2262 free_cpumask_var(hctxs
[i
]->cpumask
);
2267 blk_mq_hctx_kobj_init(hctxs
[i
]);
2269 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2270 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2274 blk_mq_free_map_and_requests(set
, j
);
2275 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2276 free_cpumask_var(hctx
->cpumask
);
2277 kobject_put(&hctx
->kobj
);
2284 q
->nr_hw_queues
= i
;
2285 blk_mq_sysfs_register(q
);
2288 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2289 struct request_queue
*q
)
2291 /* mark the queue as mq asap */
2292 q
->mq_ops
= set
->ops
;
2294 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2298 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2299 GFP_KERNEL
, set
->numa_node
);
2300 if (!q
->queue_hw_ctx
)
2303 q
->mq_map
= set
->mq_map
;
2305 blk_mq_realloc_hw_ctxs(set
, q
);
2306 if (!q
->nr_hw_queues
)
2309 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2310 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2312 q
->nr_queues
= nr_cpu_ids
;
2314 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2316 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2317 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2319 q
->sg_reserved_size
= INT_MAX
;
2321 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2322 INIT_LIST_HEAD(&q
->requeue_list
);
2323 spin_lock_init(&q
->requeue_lock
);
2325 if (q
->nr_hw_queues
> 1)
2326 blk_queue_make_request(q
, blk_mq_make_request
);
2328 blk_queue_make_request(q
, blk_sq_make_request
);
2331 * Do this after blk_queue_make_request() overrides it...
2333 q
->nr_requests
= set
->queue_depth
;
2336 * Default to classic polling
2340 if (set
->ops
->complete
)
2341 blk_queue_softirq_done(q
, set
->ops
->complete
);
2343 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2346 mutex_lock(&all_q_mutex
);
2348 list_add_tail(&q
->all_q_node
, &all_q_list
);
2349 blk_mq_add_queue_tag_set(set
, q
);
2350 blk_mq_map_swqueue(q
, cpu_online_mask
);
2352 mutex_unlock(&all_q_mutex
);
2355 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2358 ret
= blk_mq_sched_init(q
);
2360 return ERR_PTR(ret
);
2366 kfree(q
->queue_hw_ctx
);
2368 free_percpu(q
->queue_ctx
);
2371 return ERR_PTR(-ENOMEM
);
2373 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2375 void blk_mq_free_queue(struct request_queue
*q
)
2377 struct blk_mq_tag_set
*set
= q
->tag_set
;
2379 mutex_lock(&all_q_mutex
);
2380 list_del_init(&q
->all_q_node
);
2381 mutex_unlock(&all_q_mutex
);
2385 blk_mq_del_queue_tag_set(q
);
2387 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2388 blk_mq_free_hw_queues(q
, set
);
2391 /* Basically redo blk_mq_init_queue with queue frozen */
2392 static void blk_mq_queue_reinit(struct request_queue
*q
,
2393 const struct cpumask
*online_mask
)
2395 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2397 blk_mq_sysfs_unregister(q
);
2400 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2401 * we should change hctx numa_node according to new topology (this
2402 * involves free and re-allocate memory, worthy doing?)
2405 blk_mq_map_swqueue(q
, online_mask
);
2407 blk_mq_sysfs_register(q
);
2411 * New online cpumask which is going to be set in this hotplug event.
2412 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2413 * one-by-one and dynamically allocating this could result in a failure.
2415 static struct cpumask cpuhp_online_new
;
2417 static void blk_mq_queue_reinit_work(void)
2419 struct request_queue
*q
;
2421 mutex_lock(&all_q_mutex
);
2423 * We need to freeze and reinit all existing queues. Freezing
2424 * involves synchronous wait for an RCU grace period and doing it
2425 * one by one may take a long time. Start freezing all queues in
2426 * one swoop and then wait for the completions so that freezing can
2427 * take place in parallel.
2429 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2430 blk_mq_freeze_queue_start(q
);
2431 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2432 blk_mq_freeze_queue_wait(q
);
2434 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2435 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2437 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2438 blk_mq_unfreeze_queue(q
);
2440 mutex_unlock(&all_q_mutex
);
2443 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2445 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2446 blk_mq_queue_reinit_work();
2451 * Before hotadded cpu starts handling requests, new mappings must be
2452 * established. Otherwise, these requests in hw queue might never be
2455 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2456 * for CPU0, and ctx1 for CPU1).
2458 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2459 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2461 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2462 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2463 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2466 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2468 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2469 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2470 blk_mq_queue_reinit_work();
2474 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2478 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2479 if (!__blk_mq_alloc_rq_map(set
, i
))
2486 blk_mq_free_rq_map(set
->tags
[i
]);
2492 * Allocate the request maps associated with this tag_set. Note that this
2493 * may reduce the depth asked for, if memory is tight. set->queue_depth
2494 * will be updated to reflect the allocated depth.
2496 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2501 depth
= set
->queue_depth
;
2503 err
= __blk_mq_alloc_rq_maps(set
);
2507 set
->queue_depth
>>= 1;
2508 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2512 } while (set
->queue_depth
);
2514 if (!set
->queue_depth
|| err
) {
2515 pr_err("blk-mq: failed to allocate request map\n");
2519 if (depth
!= set
->queue_depth
)
2520 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2521 depth
, set
->queue_depth
);
2527 * Alloc a tag set to be associated with one or more request queues.
2528 * May fail with EINVAL for various error conditions. May adjust the
2529 * requested depth down, if if it too large. In that case, the set
2530 * value will be stored in set->queue_depth.
2532 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2536 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2538 if (!set
->nr_hw_queues
)
2540 if (!set
->queue_depth
)
2542 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2545 if (!set
->ops
->queue_rq
)
2548 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2549 pr_info("blk-mq: reduced tag depth to %u\n",
2551 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2555 * If a crashdump is active, then we are potentially in a very
2556 * memory constrained environment. Limit us to 1 queue and
2557 * 64 tags to prevent using too much memory.
2559 if (is_kdump_kernel()) {
2560 set
->nr_hw_queues
= 1;
2561 set
->queue_depth
= min(64U, set
->queue_depth
);
2564 * There is no use for more h/w queues than cpus.
2566 if (set
->nr_hw_queues
> nr_cpu_ids
)
2567 set
->nr_hw_queues
= nr_cpu_ids
;
2569 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2570 GFP_KERNEL
, set
->numa_node
);
2575 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2576 GFP_KERNEL
, set
->numa_node
);
2580 if (set
->ops
->map_queues
)
2581 ret
= set
->ops
->map_queues(set
);
2583 ret
= blk_mq_map_queues(set
);
2585 goto out_free_mq_map
;
2587 ret
= blk_mq_alloc_rq_maps(set
);
2589 goto out_free_mq_map
;
2591 mutex_init(&set
->tag_list_lock
);
2592 INIT_LIST_HEAD(&set
->tag_list
);
2604 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2606 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2610 for (i
= 0; i
< nr_cpu_ids
; i
++)
2611 blk_mq_free_map_and_requests(set
, i
);
2619 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2621 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2623 struct blk_mq_tag_set
*set
= q
->tag_set
;
2624 struct blk_mq_hw_ctx
*hctx
;
2630 blk_mq_freeze_queue(q
);
2631 blk_mq_quiesce_queue(q
);
2634 queue_for_each_hw_ctx(q
, hctx
, i
) {
2638 * If we're using an MQ scheduler, just update the scheduler
2639 * queue depth. This is similar to what the old code would do.
2641 if (!hctx
->sched_tags
) {
2642 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2643 min(nr
, set
->queue_depth
),
2646 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2654 q
->nr_requests
= nr
;
2656 blk_mq_unfreeze_queue(q
);
2657 blk_mq_start_stopped_hw_queues(q
, true);
2662 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2664 struct request_queue
*q
;
2666 if (nr_hw_queues
> nr_cpu_ids
)
2667 nr_hw_queues
= nr_cpu_ids
;
2668 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2671 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2672 blk_mq_freeze_queue(q
);
2674 set
->nr_hw_queues
= nr_hw_queues
;
2675 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2676 blk_mq_realloc_hw_ctxs(set
, q
);
2679 * Manually set the make_request_fn as blk_queue_make_request
2680 * resets a lot of the queue settings.
2682 if (q
->nr_hw_queues
> 1)
2683 q
->make_request_fn
= blk_mq_make_request
;
2685 q
->make_request_fn
= blk_sq_make_request
;
2687 blk_mq_queue_reinit(q
, cpu_online_mask
);
2690 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2691 blk_mq_unfreeze_queue(q
);
2693 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2695 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2696 struct blk_mq_hw_ctx
*hctx
,
2699 struct blk_rq_stat stat
[2];
2700 unsigned long ret
= 0;
2703 * If stats collection isn't on, don't sleep but turn it on for
2706 if (!blk_stat_enable(q
))
2710 * We don't have to do this once per IO, should optimize this
2711 * to just use the current window of stats until it changes
2713 memset(&stat
, 0, sizeof(stat
));
2714 blk_hctx_stat_get(hctx
, stat
);
2717 * As an optimistic guess, use half of the mean service time
2718 * for this type of request. We can (and should) make this smarter.
2719 * For instance, if the completion latencies are tight, we can
2720 * get closer than just half the mean. This is especially
2721 * important on devices where the completion latencies are longer
2724 if (req_op(rq
) == REQ_OP_READ
&& stat
[BLK_STAT_READ
].nr_samples
)
2725 ret
= (stat
[BLK_STAT_READ
].mean
+ 1) / 2;
2726 else if (req_op(rq
) == REQ_OP_WRITE
&& stat
[BLK_STAT_WRITE
].nr_samples
)
2727 ret
= (stat
[BLK_STAT_WRITE
].mean
+ 1) / 2;
2732 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2733 struct blk_mq_hw_ctx
*hctx
,
2736 struct hrtimer_sleeper hs
;
2737 enum hrtimer_mode mode
;
2741 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2747 * -1: don't ever hybrid sleep
2748 * 0: use half of prev avg
2749 * >0: use this specific value
2751 if (q
->poll_nsec
== -1)
2753 else if (q
->poll_nsec
> 0)
2754 nsecs
= q
->poll_nsec
;
2756 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2761 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2764 * This will be replaced with the stats tracking code, using
2765 * 'avg_completion_time / 2' as the pre-sleep target.
2769 mode
= HRTIMER_MODE_REL
;
2770 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2771 hrtimer_set_expires(&hs
.timer
, kt
);
2773 hrtimer_init_sleeper(&hs
, current
);
2775 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2777 set_current_state(TASK_UNINTERRUPTIBLE
);
2778 hrtimer_start_expires(&hs
.timer
, mode
);
2781 hrtimer_cancel(&hs
.timer
);
2782 mode
= HRTIMER_MODE_ABS
;
2783 } while (hs
.task
&& !signal_pending(current
));
2785 __set_current_state(TASK_RUNNING
);
2786 destroy_hrtimer_on_stack(&hs
.timer
);
2790 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2792 struct request_queue
*q
= hctx
->queue
;
2796 * If we sleep, have the caller restart the poll loop to reset
2797 * the state. Like for the other success return cases, the
2798 * caller is responsible for checking if the IO completed. If
2799 * the IO isn't complete, we'll get called again and will go
2800 * straight to the busy poll loop.
2802 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2805 hctx
->poll_considered
++;
2807 state
= current
->state
;
2808 while (!need_resched()) {
2811 hctx
->poll_invoked
++;
2813 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2815 hctx
->poll_success
++;
2816 set_current_state(TASK_RUNNING
);
2820 if (signal_pending_state(state
, current
))
2821 set_current_state(TASK_RUNNING
);
2823 if (current
->state
== TASK_RUNNING
)
2833 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2835 struct blk_mq_hw_ctx
*hctx
;
2836 struct blk_plug
*plug
;
2839 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2840 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2843 plug
= current
->plug
;
2845 blk_flush_plug_list(plug
, false);
2847 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2848 if (!blk_qc_t_is_internal(cookie
))
2849 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2851 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2853 return __blk_mq_poll(hctx
, rq
);
2855 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2857 void blk_mq_disable_hotplug(void)
2859 mutex_lock(&all_q_mutex
);
2862 void blk_mq_enable_hotplug(void)
2864 mutex_unlock(&all_q_mutex
);
2867 static int __init
blk_mq_init(void)
2869 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2870 blk_mq_hctx_notify_dead
);
2872 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2873 blk_mq_queue_reinit_prepare
,
2874 blk_mq_queue_reinit_dead
);
2877 subsys_initcall(blk_mq_init
);