2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/delay.h>
24 #include <linux/crash_dump.h>
25 #include <linux/prefetch.h>
27 #include <trace/events/block.h>
29 #include <linux/blk-mq.h>
32 #include "blk-mq-tag.h"
34 static DEFINE_MUTEX(all_q_mutex
);
35 static LIST_HEAD(all_q_list
);
38 * Check if any of the ctx's have pending work in this hardware queue
40 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
42 return sbitmap_any_bit_set(&hctx
->ctx_map
);
46 * Mark this ctx as having pending work in this hardware queue
48 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
49 struct blk_mq_ctx
*ctx
)
51 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
52 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
55 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
56 struct blk_mq_ctx
*ctx
)
58 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
61 void blk_mq_freeze_queue_start(struct request_queue
*q
)
65 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
66 if (freeze_depth
== 1) {
67 percpu_ref_kill(&q
->q_usage_counter
);
68 blk_mq_run_hw_queues(q
, false);
71 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
73 static void blk_mq_freeze_queue_wait(struct request_queue
*q
)
75 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
79 * Guarantee no request is in use, so we can change any data structure of
80 * the queue afterward.
82 void blk_freeze_queue(struct request_queue
*q
)
85 * In the !blk_mq case we are only calling this to kill the
86 * q_usage_counter, otherwise this increases the freeze depth
87 * and waits for it to return to zero. For this reason there is
88 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
89 * exported to drivers as the only user for unfreeze is blk_mq.
91 blk_mq_freeze_queue_start(q
);
92 blk_mq_freeze_queue_wait(q
);
95 void blk_mq_freeze_queue(struct request_queue
*q
)
98 * ...just an alias to keep freeze and unfreeze actions balanced
99 * in the blk_mq_* namespace
103 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
105 void blk_mq_unfreeze_queue(struct request_queue
*q
)
109 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
110 WARN_ON_ONCE(freeze_depth
< 0);
112 percpu_ref_reinit(&q
->q_usage_counter
);
113 wake_up_all(&q
->mq_freeze_wq
);
116 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
118 void blk_mq_wake_waiters(struct request_queue
*q
)
120 struct blk_mq_hw_ctx
*hctx
;
123 queue_for_each_hw_ctx(q
, hctx
, i
)
124 if (blk_mq_hw_queue_mapped(hctx
))
125 blk_mq_tag_wakeup_all(hctx
->tags
, true);
128 * If we are called because the queue has now been marked as
129 * dying, we need to ensure that processes currently waiting on
130 * the queue are notified as well.
132 wake_up_all(&q
->mq_freeze_wq
);
135 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
137 return blk_mq_has_free_tags(hctx
->tags
);
139 EXPORT_SYMBOL(blk_mq_can_queue
);
141 static void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
142 struct request
*rq
, unsigned int op
)
144 INIT_LIST_HEAD(&rq
->queuelist
);
145 /* csd/requeue_work/fifo_time is initialized before use */
149 if (blk_queue_io_stat(q
))
150 rq
->rq_flags
|= RQF_IO_STAT
;
151 /* do not touch atomic flags, it needs atomic ops against the timer */
153 INIT_HLIST_NODE(&rq
->hash
);
154 RB_CLEAR_NODE(&rq
->rb_node
);
157 rq
->start_time
= jiffies
;
158 #ifdef CONFIG_BLK_CGROUP
160 set_start_time_ns(rq
);
161 rq
->io_start_time_ns
= 0;
163 rq
->nr_phys_segments
= 0;
164 #if defined(CONFIG_BLK_DEV_INTEGRITY)
165 rq
->nr_integrity_segments
= 0;
168 /* tag was already set */
178 INIT_LIST_HEAD(&rq
->timeout_list
);
182 rq
->end_io_data
= NULL
;
185 ctx
->rq_dispatched
[op_is_sync(op
)]++;
188 static struct request
*
189 __blk_mq_alloc_request(struct blk_mq_alloc_data
*data
, unsigned int op
)
194 tag
= blk_mq_get_tag(data
);
195 if (tag
!= BLK_MQ_TAG_FAIL
) {
196 rq
= data
->hctx
->tags
->rqs
[tag
];
198 if (blk_mq_tag_busy(data
->hctx
)) {
199 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
200 atomic_inc(&data
->hctx
->nr_active
);
204 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
);
211 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
214 struct blk_mq_ctx
*ctx
;
215 struct blk_mq_hw_ctx
*hctx
;
217 struct blk_mq_alloc_data alloc_data
;
220 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
224 ctx
= blk_mq_get_ctx(q
);
225 hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
226 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
227 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
232 return ERR_PTR(-EWOULDBLOCK
);
236 rq
->__sector
= (sector_t
) -1;
237 rq
->bio
= rq
->biotail
= NULL
;
240 EXPORT_SYMBOL(blk_mq_alloc_request
);
242 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
243 unsigned int flags
, unsigned int hctx_idx
)
245 struct blk_mq_hw_ctx
*hctx
;
246 struct blk_mq_ctx
*ctx
;
248 struct blk_mq_alloc_data alloc_data
;
252 * If the tag allocator sleeps we could get an allocation for a
253 * different hardware context. No need to complicate the low level
254 * allocator for this for the rare use case of a command tied to
257 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
258 return ERR_PTR(-EINVAL
);
260 if (hctx_idx
>= q
->nr_hw_queues
)
261 return ERR_PTR(-EIO
);
263 ret
= blk_queue_enter(q
, true);
268 * Check if the hardware context is actually mapped to anything.
269 * If not tell the caller that it should skip this queue.
271 hctx
= q
->queue_hw_ctx
[hctx_idx
];
272 if (!blk_mq_hw_queue_mapped(hctx
)) {
276 ctx
= __blk_mq_get_ctx(q
, cpumask_first(hctx
->cpumask
));
278 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
279 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
291 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
293 static void __blk_mq_free_request(struct blk_mq_hw_ctx
*hctx
,
294 struct blk_mq_ctx
*ctx
, struct request
*rq
)
296 const int tag
= rq
->tag
;
297 struct request_queue
*q
= rq
->q
;
299 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
300 atomic_dec(&hctx
->nr_active
);
303 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
304 blk_mq_put_tag(hctx
, ctx
, tag
);
308 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
310 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
312 ctx
->rq_completed
[rq_is_sync(rq
)]++;
313 __blk_mq_free_request(hctx
, ctx
, rq
);
316 EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request
);
318 void blk_mq_free_request(struct request
*rq
)
320 blk_mq_free_hctx_request(blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
), rq
);
322 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
324 inline void __blk_mq_end_request(struct request
*rq
, int error
)
326 blk_account_io_done(rq
);
329 rq
->end_io(rq
, error
);
331 if (unlikely(blk_bidi_rq(rq
)))
332 blk_mq_free_request(rq
->next_rq
);
333 blk_mq_free_request(rq
);
336 EXPORT_SYMBOL(__blk_mq_end_request
);
338 void blk_mq_end_request(struct request
*rq
, int error
)
340 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
342 __blk_mq_end_request(rq
, error
);
344 EXPORT_SYMBOL(blk_mq_end_request
);
346 static void __blk_mq_complete_request_remote(void *data
)
348 struct request
*rq
= data
;
350 rq
->q
->softirq_done_fn(rq
);
353 static void blk_mq_ipi_complete_request(struct request
*rq
)
355 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
359 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
360 rq
->q
->softirq_done_fn(rq
);
365 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
366 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
368 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
369 rq
->csd
.func
= __blk_mq_complete_request_remote
;
372 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
374 rq
->q
->softirq_done_fn(rq
);
379 static void __blk_mq_complete_request(struct request
*rq
)
381 struct request_queue
*q
= rq
->q
;
383 if (!q
->softirq_done_fn
)
384 blk_mq_end_request(rq
, rq
->errors
);
386 blk_mq_ipi_complete_request(rq
);
390 * blk_mq_complete_request - end I/O on a request
391 * @rq: the request being processed
394 * Ends all I/O on a request. It does not handle partial completions.
395 * The actual completion happens out-of-order, through a IPI handler.
397 void blk_mq_complete_request(struct request
*rq
, int error
)
399 struct request_queue
*q
= rq
->q
;
401 if (unlikely(blk_should_fake_timeout(q
)))
403 if (!blk_mark_rq_complete(rq
)) {
405 __blk_mq_complete_request(rq
);
408 EXPORT_SYMBOL(blk_mq_complete_request
);
410 int blk_mq_request_started(struct request
*rq
)
412 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
414 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
416 void blk_mq_start_request(struct request
*rq
)
418 struct request_queue
*q
= rq
->q
;
420 trace_block_rq_issue(q
, rq
);
422 rq
->resid_len
= blk_rq_bytes(rq
);
423 if (unlikely(blk_bidi_rq(rq
)))
424 rq
->next_rq
->resid_len
= blk_rq_bytes(rq
->next_rq
);
429 * Ensure that ->deadline is visible before set the started
430 * flag and clear the completed flag.
432 smp_mb__before_atomic();
435 * Mark us as started and clear complete. Complete might have been
436 * set if requeue raced with timeout, which then marked it as
437 * complete. So be sure to clear complete again when we start
438 * the request, otherwise we'll ignore the completion event.
440 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
441 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
442 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
443 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
445 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
447 * Make sure space for the drain appears. We know we can do
448 * this because max_hw_segments has been adjusted to be one
449 * fewer than the device can handle.
451 rq
->nr_phys_segments
++;
454 EXPORT_SYMBOL(blk_mq_start_request
);
456 static void __blk_mq_requeue_request(struct request
*rq
)
458 struct request_queue
*q
= rq
->q
;
460 trace_block_rq_requeue(q
, rq
);
462 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
463 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
464 rq
->nr_phys_segments
--;
468 void blk_mq_requeue_request(struct request
*rq
)
470 __blk_mq_requeue_request(rq
);
472 BUG_ON(blk_queued_rq(rq
));
473 blk_mq_add_to_requeue_list(rq
, true);
475 EXPORT_SYMBOL(blk_mq_requeue_request
);
477 static void blk_mq_requeue_work(struct work_struct
*work
)
479 struct request_queue
*q
=
480 container_of(work
, struct request_queue
, requeue_work
.work
);
482 struct request
*rq
, *next
;
485 spin_lock_irqsave(&q
->requeue_lock
, flags
);
486 list_splice_init(&q
->requeue_list
, &rq_list
);
487 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
489 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
490 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
493 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
494 list_del_init(&rq
->queuelist
);
495 blk_mq_insert_request(rq
, true, false, false);
498 while (!list_empty(&rq_list
)) {
499 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
500 list_del_init(&rq
->queuelist
);
501 blk_mq_insert_request(rq
, false, false, false);
505 * Use the start variant of queue running here, so that running
506 * the requeue work will kick stopped queues.
508 blk_mq_start_hw_queues(q
);
511 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
)
513 struct request_queue
*q
= rq
->q
;
517 * We abuse this flag that is otherwise used by the I/O scheduler to
518 * request head insertation from the workqueue.
520 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
522 spin_lock_irqsave(&q
->requeue_lock
, flags
);
524 rq
->rq_flags
|= RQF_SOFTBARRIER
;
525 list_add(&rq
->queuelist
, &q
->requeue_list
);
527 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
529 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
531 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
533 void blk_mq_cancel_requeue_work(struct request_queue
*q
)
535 cancel_delayed_work_sync(&q
->requeue_work
);
537 EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work
);
539 void blk_mq_kick_requeue_list(struct request_queue
*q
)
541 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
543 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
545 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
548 kblockd_schedule_delayed_work(&q
->requeue_work
,
549 msecs_to_jiffies(msecs
));
551 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
553 void blk_mq_abort_requeue_list(struct request_queue
*q
)
558 spin_lock_irqsave(&q
->requeue_lock
, flags
);
559 list_splice_init(&q
->requeue_list
, &rq_list
);
560 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
562 while (!list_empty(&rq_list
)) {
565 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
566 list_del_init(&rq
->queuelist
);
568 blk_mq_end_request(rq
, rq
->errors
);
571 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
573 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
575 if (tag
< tags
->nr_tags
) {
576 prefetch(tags
->rqs
[tag
]);
577 return tags
->rqs
[tag
];
582 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
584 struct blk_mq_timeout_data
{
586 unsigned int next_set
;
589 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
591 struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
592 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
595 * We know that complete is set at this point. If STARTED isn't set
596 * anymore, then the request isn't active and the "timeout" should
597 * just be ignored. This can happen due to the bitflag ordering.
598 * Timeout first checks if STARTED is set, and if it is, assumes
599 * the request is active. But if we race with completion, then
600 * we both flags will get cleared. So check here again, and ignore
601 * a timeout event with a request that isn't active.
603 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
607 ret
= ops
->timeout(req
, reserved
);
611 __blk_mq_complete_request(req
);
613 case BLK_EH_RESET_TIMER
:
615 blk_clear_rq_complete(req
);
617 case BLK_EH_NOT_HANDLED
:
620 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
625 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
626 struct request
*rq
, void *priv
, bool reserved
)
628 struct blk_mq_timeout_data
*data
= priv
;
630 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
632 * If a request wasn't started before the queue was
633 * marked dying, kill it here or it'll go unnoticed.
635 if (unlikely(blk_queue_dying(rq
->q
))) {
637 blk_mq_end_request(rq
, rq
->errors
);
642 if (time_after_eq(jiffies
, rq
->deadline
)) {
643 if (!blk_mark_rq_complete(rq
))
644 blk_mq_rq_timed_out(rq
, reserved
);
645 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
646 data
->next
= rq
->deadline
;
651 static void blk_mq_timeout_work(struct work_struct
*work
)
653 struct request_queue
*q
=
654 container_of(work
, struct request_queue
, timeout_work
);
655 struct blk_mq_timeout_data data
= {
661 /* A deadlock might occur if a request is stuck requiring a
662 * timeout at the same time a queue freeze is waiting
663 * completion, since the timeout code would not be able to
664 * acquire the queue reference here.
666 * That's why we don't use blk_queue_enter here; instead, we use
667 * percpu_ref_tryget directly, because we need to be able to
668 * obtain a reference even in the short window between the queue
669 * starting to freeze, by dropping the first reference in
670 * blk_mq_freeze_queue_start, and the moment the last request is
671 * consumed, marked by the instant q_usage_counter reaches
674 if (!percpu_ref_tryget(&q
->q_usage_counter
))
677 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
680 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
681 mod_timer(&q
->timeout
, data
.next
);
683 struct blk_mq_hw_ctx
*hctx
;
685 queue_for_each_hw_ctx(q
, hctx
, i
) {
686 /* the hctx may be unmapped, so check it here */
687 if (blk_mq_hw_queue_mapped(hctx
))
688 blk_mq_tag_idle(hctx
);
695 * Reverse check our software queue for entries that we could potentially
696 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
697 * too much time checking for merges.
699 static bool blk_mq_attempt_merge(struct request_queue
*q
,
700 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
705 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
711 if (!blk_rq_merge_ok(rq
, bio
))
714 el_ret
= blk_try_merge(rq
, bio
);
715 if (el_ret
== ELEVATOR_BACK_MERGE
) {
716 if (bio_attempt_back_merge(q
, rq
, bio
)) {
721 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
722 if (bio_attempt_front_merge(q
, rq
, bio
)) {
733 struct flush_busy_ctx_data
{
734 struct blk_mq_hw_ctx
*hctx
;
735 struct list_head
*list
;
738 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
740 struct flush_busy_ctx_data
*flush_data
= data
;
741 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
742 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
744 sbitmap_clear_bit(sb
, bitnr
);
745 spin_lock(&ctx
->lock
);
746 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
747 spin_unlock(&ctx
->lock
);
752 * Process software queues that have been marked busy, splicing them
753 * to the for-dispatch
755 static void flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
757 struct flush_busy_ctx_data data
= {
762 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
765 static inline unsigned int queued_to_index(unsigned int queued
)
770 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
774 * Run this hardware queue, pulling any software queues mapped to it in.
775 * Note that this function currently has various problems around ordering
776 * of IO. In particular, we'd like FIFO behaviour on handling existing
777 * items on the hctx->dispatch list. Ignore that for now.
779 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
781 struct request_queue
*q
= hctx
->queue
;
784 LIST_HEAD(driver_list
);
785 struct list_head
*dptr
;
788 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)))
791 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
792 cpu_online(hctx
->next_cpu
));
797 * Touch any software queue that has pending entries.
799 flush_busy_ctxs(hctx
, &rq_list
);
802 * If we have previous entries on our dispatch list, grab them
803 * and stuff them at the front for more fair dispatch.
805 if (!list_empty_careful(&hctx
->dispatch
)) {
806 spin_lock(&hctx
->lock
);
807 if (!list_empty(&hctx
->dispatch
))
808 list_splice_init(&hctx
->dispatch
, &rq_list
);
809 spin_unlock(&hctx
->lock
);
813 * Start off with dptr being NULL, so we start the first request
814 * immediately, even if we have more pending.
819 * Now process all the entries, sending them to the driver.
822 while (!list_empty(&rq_list
)) {
823 struct blk_mq_queue_data bd
;
826 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
827 list_del_init(&rq
->queuelist
);
831 bd
.last
= list_empty(&rq_list
);
833 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
835 case BLK_MQ_RQ_QUEUE_OK
:
838 case BLK_MQ_RQ_QUEUE_BUSY
:
839 list_add(&rq
->queuelist
, &rq_list
);
840 __blk_mq_requeue_request(rq
);
843 pr_err("blk-mq: bad return on queue: %d\n", ret
);
844 case BLK_MQ_RQ_QUEUE_ERROR
:
846 blk_mq_end_request(rq
, rq
->errors
);
850 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
854 * We've done the first request. If we have more than 1
855 * left in the list, set dptr to defer issue.
857 if (!dptr
&& rq_list
.next
!= rq_list
.prev
)
861 hctx
->dispatched
[queued_to_index(queued
)]++;
864 * Any items that need requeuing? Stuff them into hctx->dispatch,
865 * that is where we will continue on next queue run.
867 if (!list_empty(&rq_list
)) {
868 spin_lock(&hctx
->lock
);
869 list_splice(&rq_list
, &hctx
->dispatch
);
870 spin_unlock(&hctx
->lock
);
872 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
873 * it's possible the queue is stopped and restarted again
874 * before this. Queue restart will dispatch requests. And since
875 * requests in rq_list aren't added into hctx->dispatch yet,
876 * the requests in rq_list might get lost.
878 * blk_mq_run_hw_queue() already checks the STOPPED bit
880 blk_mq_run_hw_queue(hctx
, true);
885 * It'd be great if the workqueue API had a way to pass
886 * in a mask and had some smarts for more clever placement.
887 * For now we just round-robin here, switching for every
888 * BLK_MQ_CPU_WORK_BATCH queued items.
890 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
892 if (hctx
->queue
->nr_hw_queues
== 1)
893 return WORK_CPU_UNBOUND
;
895 if (--hctx
->next_cpu_batch
<= 0) {
896 int cpu
= hctx
->next_cpu
, next_cpu
;
898 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
899 if (next_cpu
>= nr_cpu_ids
)
900 next_cpu
= cpumask_first(hctx
->cpumask
);
902 hctx
->next_cpu
= next_cpu
;
903 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
908 return hctx
->next_cpu
;
911 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
913 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
) ||
914 !blk_mq_hw_queue_mapped(hctx
)))
917 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
919 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
920 __blk_mq_run_hw_queue(hctx
);
928 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
);
931 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
933 struct blk_mq_hw_ctx
*hctx
;
936 queue_for_each_hw_ctx(q
, hctx
, i
) {
937 if ((!blk_mq_hctx_has_pending(hctx
) &&
938 list_empty_careful(&hctx
->dispatch
)) ||
939 test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
942 blk_mq_run_hw_queue(hctx
, async
);
945 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
947 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
949 cancel_work(&hctx
->run_work
);
950 cancel_delayed_work(&hctx
->delay_work
);
951 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
953 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
955 void blk_mq_stop_hw_queues(struct request_queue
*q
)
957 struct blk_mq_hw_ctx
*hctx
;
960 queue_for_each_hw_ctx(q
, hctx
, i
)
961 blk_mq_stop_hw_queue(hctx
);
963 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
965 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
967 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
969 blk_mq_run_hw_queue(hctx
, false);
971 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
973 void blk_mq_start_hw_queues(struct request_queue
*q
)
975 struct blk_mq_hw_ctx
*hctx
;
978 queue_for_each_hw_ctx(q
, hctx
, i
)
979 blk_mq_start_hw_queue(hctx
);
981 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
983 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
985 struct blk_mq_hw_ctx
*hctx
;
988 queue_for_each_hw_ctx(q
, hctx
, i
) {
989 if (!test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
992 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
993 blk_mq_run_hw_queue(hctx
, async
);
996 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
998 static void blk_mq_run_work_fn(struct work_struct
*work
)
1000 struct blk_mq_hw_ctx
*hctx
;
1002 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
);
1004 __blk_mq_run_hw_queue(hctx
);
1007 static void blk_mq_delay_work_fn(struct work_struct
*work
)
1009 struct blk_mq_hw_ctx
*hctx
;
1011 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
1013 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1014 __blk_mq_run_hw_queue(hctx
);
1017 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1019 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1022 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1023 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
1025 EXPORT_SYMBOL(blk_mq_delay_queue
);
1027 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1031 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1033 trace_block_rq_insert(hctx
->queue
, rq
);
1036 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1038 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1041 static void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
,
1042 struct request
*rq
, bool at_head
)
1044 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1046 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1047 blk_mq_hctx_mark_pending(hctx
, ctx
);
1050 void blk_mq_insert_request(struct request
*rq
, bool at_head
, bool run_queue
,
1053 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1054 struct request_queue
*q
= rq
->q
;
1055 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
1057 spin_lock(&ctx
->lock
);
1058 __blk_mq_insert_request(hctx
, rq
, at_head
);
1059 spin_unlock(&ctx
->lock
);
1062 blk_mq_run_hw_queue(hctx
, async
);
1065 static void blk_mq_insert_requests(struct request_queue
*q
,
1066 struct blk_mq_ctx
*ctx
,
1067 struct list_head
*list
,
1072 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
1074 trace_block_unplug(q
, depth
, !from_schedule
);
1077 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1080 spin_lock(&ctx
->lock
);
1081 while (!list_empty(list
)) {
1084 rq
= list_first_entry(list
, struct request
, queuelist
);
1085 BUG_ON(rq
->mq_ctx
!= ctx
);
1086 list_del_init(&rq
->queuelist
);
1087 __blk_mq_insert_req_list(hctx
, rq
, false);
1089 blk_mq_hctx_mark_pending(hctx
, ctx
);
1090 spin_unlock(&ctx
->lock
);
1092 blk_mq_run_hw_queue(hctx
, from_schedule
);
1095 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1097 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1098 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1100 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1101 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1102 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1105 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1107 struct blk_mq_ctx
*this_ctx
;
1108 struct request_queue
*this_q
;
1111 LIST_HEAD(ctx_list
);
1114 list_splice_init(&plug
->mq_list
, &list
);
1116 list_sort(NULL
, &list
, plug_ctx_cmp
);
1122 while (!list_empty(&list
)) {
1123 rq
= list_entry_rq(list
.next
);
1124 list_del_init(&rq
->queuelist
);
1126 if (rq
->mq_ctx
!= this_ctx
) {
1128 blk_mq_insert_requests(this_q
, this_ctx
,
1133 this_ctx
= rq
->mq_ctx
;
1139 list_add_tail(&rq
->queuelist
, &ctx_list
);
1143 * If 'this_ctx' is set, we know we have entries to complete
1144 * on 'ctx_list'. Do those.
1147 blk_mq_insert_requests(this_q
, this_ctx
, &ctx_list
, depth
,
1152 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1154 init_request_from_bio(rq
, bio
);
1156 blk_account_io_start(rq
, 1);
1159 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1161 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1162 !blk_queue_nomerges(hctx
->queue
);
1165 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1166 struct blk_mq_ctx
*ctx
,
1167 struct request
*rq
, struct bio
*bio
)
1169 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1170 blk_mq_bio_to_request(rq
, bio
);
1171 spin_lock(&ctx
->lock
);
1173 __blk_mq_insert_request(hctx
, rq
, false);
1174 spin_unlock(&ctx
->lock
);
1177 struct request_queue
*q
= hctx
->queue
;
1179 spin_lock(&ctx
->lock
);
1180 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1181 blk_mq_bio_to_request(rq
, bio
);
1185 spin_unlock(&ctx
->lock
);
1186 __blk_mq_free_request(hctx
, ctx
, rq
);
1191 static struct request
*blk_mq_map_request(struct request_queue
*q
,
1193 struct blk_mq_alloc_data
*data
)
1195 struct blk_mq_hw_ctx
*hctx
;
1196 struct blk_mq_ctx
*ctx
;
1199 blk_queue_enter_live(q
);
1200 ctx
= blk_mq_get_ctx(q
);
1201 hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
1203 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1204 blk_mq_set_alloc_data(data
, q
, 0, ctx
, hctx
);
1205 rq
= __blk_mq_alloc_request(data
, bio
->bi_opf
);
1207 data
->hctx
->queued
++;
1211 static int blk_mq_direct_issue_request(struct request
*rq
, blk_qc_t
*cookie
)
1214 struct request_queue
*q
= rq
->q
;
1215 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, rq
->mq_ctx
->cpu
);
1216 struct blk_mq_queue_data bd
= {
1221 blk_qc_t new_cookie
= blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
);
1224 * For OK queue, we are done. For error, kill it. Any other
1225 * error (busy), just add it to our list as we previously
1228 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1229 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1230 *cookie
= new_cookie
;
1234 __blk_mq_requeue_request(rq
);
1236 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1237 *cookie
= BLK_QC_T_NONE
;
1239 blk_mq_end_request(rq
, rq
->errors
);
1247 * Multiple hardware queue variant. This will not use per-process plugs,
1248 * but will attempt to bypass the hctx queueing if we can go straight to
1249 * hardware for SYNC IO.
1251 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1253 const int is_sync
= op_is_sync(bio
->bi_opf
);
1254 const int is_flush_fua
= bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
);
1255 struct blk_mq_alloc_data data
;
1257 unsigned int request_count
= 0;
1258 struct blk_plug
*plug
;
1259 struct request
*same_queue_rq
= NULL
;
1262 blk_queue_bounce(q
, &bio
);
1264 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1266 return BLK_QC_T_NONE
;
1269 blk_queue_split(q
, &bio
, q
->bio_split
);
1271 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1272 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1273 return BLK_QC_T_NONE
;
1275 rq
= blk_mq_map_request(q
, bio
, &data
);
1277 return BLK_QC_T_NONE
;
1279 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1281 if (unlikely(is_flush_fua
)) {
1282 blk_mq_bio_to_request(rq
, bio
);
1283 blk_insert_flush(rq
);
1287 plug
= current
->plug
;
1289 * If the driver supports defer issued based on 'last', then
1290 * queue it up like normal since we can potentially save some
1293 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1294 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1295 struct request
*old_rq
= NULL
;
1297 blk_mq_bio_to_request(rq
, bio
);
1300 * We do limited pluging. If the bio can be merged, do that.
1301 * Otherwise the existing request in the plug list will be
1302 * issued. So the plug list will have one request at most
1306 * The plug list might get flushed before this. If that
1307 * happens, same_queue_rq is invalid and plug list is
1310 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1311 old_rq
= same_queue_rq
;
1312 list_del_init(&old_rq
->queuelist
);
1314 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1315 } else /* is_sync */
1317 blk_mq_put_ctx(data
.ctx
);
1320 if (!blk_mq_direct_issue_request(old_rq
, &cookie
))
1322 blk_mq_insert_request(old_rq
, false, true, true);
1326 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1328 * For a SYNC request, send it to the hardware immediately. For
1329 * an ASYNC request, just ensure that we run it later on. The
1330 * latter allows for merging opportunities and more efficient
1334 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1336 blk_mq_put_ctx(data
.ctx
);
1342 * Single hardware queue variant. This will attempt to use any per-process
1343 * plug for merging and IO deferral.
1345 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1347 const int is_sync
= op_is_sync(bio
->bi_opf
);
1348 const int is_flush_fua
= bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
);
1349 struct blk_plug
*plug
;
1350 unsigned int request_count
= 0;
1351 struct blk_mq_alloc_data data
;
1355 blk_queue_bounce(q
, &bio
);
1357 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1359 return BLK_QC_T_NONE
;
1362 blk_queue_split(q
, &bio
, q
->bio_split
);
1364 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1365 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1366 return BLK_QC_T_NONE
;
1368 request_count
= blk_plug_queued_count(q
);
1370 rq
= blk_mq_map_request(q
, bio
, &data
);
1372 return BLK_QC_T_NONE
;
1374 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1376 if (unlikely(is_flush_fua
)) {
1377 blk_mq_bio_to_request(rq
, bio
);
1378 blk_insert_flush(rq
);
1383 * A task plug currently exists. Since this is completely lockless,
1384 * utilize that to temporarily store requests until the task is
1385 * either done or scheduled away.
1387 plug
= current
->plug
;
1389 blk_mq_bio_to_request(rq
, bio
);
1391 trace_block_plug(q
);
1393 blk_mq_put_ctx(data
.ctx
);
1395 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1396 blk_flush_plug_list(plug
, false);
1397 trace_block_plug(q
);
1400 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1404 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1406 * For a SYNC request, send it to the hardware immediately. For
1407 * an ASYNC request, just ensure that we run it later on. The
1408 * latter allows for merging opportunities and more efficient
1412 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1415 blk_mq_put_ctx(data
.ctx
);
1419 static void blk_mq_free_rq_map(struct blk_mq_tag_set
*set
,
1420 struct blk_mq_tags
*tags
, unsigned int hctx_idx
)
1424 if (tags
->rqs
&& set
->ops
->exit_request
) {
1427 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1430 set
->ops
->exit_request(set
->driver_data
, tags
->rqs
[i
],
1432 tags
->rqs
[i
] = NULL
;
1436 while (!list_empty(&tags
->page_list
)) {
1437 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1438 list_del_init(&page
->lru
);
1440 * Remove kmemleak object previously allocated in
1441 * blk_mq_init_rq_map().
1443 kmemleak_free(page_address(page
));
1444 __free_pages(page
, page
->private);
1449 blk_mq_free_tags(tags
);
1452 static size_t order_to_size(unsigned int order
)
1454 return (size_t)PAGE_SIZE
<< order
;
1457 static struct blk_mq_tags
*blk_mq_init_rq_map(struct blk_mq_tag_set
*set
,
1458 unsigned int hctx_idx
)
1460 struct blk_mq_tags
*tags
;
1461 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1462 size_t rq_size
, left
;
1464 tags
= blk_mq_init_tags(set
->queue_depth
, set
->reserved_tags
,
1466 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1470 INIT_LIST_HEAD(&tags
->page_list
);
1472 tags
->rqs
= kzalloc_node(set
->queue_depth
* sizeof(struct request
*),
1473 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
,
1476 blk_mq_free_tags(tags
);
1481 * rq_size is the size of the request plus driver payload, rounded
1482 * to the cacheline size
1484 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1486 left
= rq_size
* set
->queue_depth
;
1488 for (i
= 0; i
< set
->queue_depth
; ) {
1489 int this_order
= max_order
;
1494 while (this_order
&& left
< order_to_size(this_order
- 1))
1498 page
= alloc_pages_node(set
->numa_node
,
1499 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1505 if (order_to_size(this_order
) < rq_size
)
1512 page
->private = this_order
;
1513 list_add_tail(&page
->lru
, &tags
->page_list
);
1515 p
= page_address(page
);
1517 * Allow kmemleak to scan these pages as they contain pointers
1518 * to additional allocations like via ops->init_request().
1520 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_KERNEL
);
1521 entries_per_page
= order_to_size(this_order
) / rq_size
;
1522 to_do
= min(entries_per_page
, set
->queue_depth
- i
);
1523 left
-= to_do
* rq_size
;
1524 for (j
= 0; j
< to_do
; j
++) {
1526 if (set
->ops
->init_request
) {
1527 if (set
->ops
->init_request(set
->driver_data
,
1528 tags
->rqs
[i
], hctx_idx
, i
,
1530 tags
->rqs
[i
] = NULL
;
1542 blk_mq_free_rq_map(set
, tags
, hctx_idx
);
1547 * 'cpu' is going away. splice any existing rq_list entries from this
1548 * software queue to the hw queue dispatch list, and ensure that it
1551 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1553 struct blk_mq_hw_ctx
*hctx
;
1554 struct blk_mq_ctx
*ctx
;
1557 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1558 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1560 spin_lock(&ctx
->lock
);
1561 if (!list_empty(&ctx
->rq_list
)) {
1562 list_splice_init(&ctx
->rq_list
, &tmp
);
1563 blk_mq_hctx_clear_pending(hctx
, ctx
);
1565 spin_unlock(&ctx
->lock
);
1567 if (list_empty(&tmp
))
1570 spin_lock(&hctx
->lock
);
1571 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1572 spin_unlock(&hctx
->lock
);
1574 blk_mq_run_hw_queue(hctx
, true);
1578 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1580 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1584 /* hctx->ctxs will be freed in queue's release handler */
1585 static void blk_mq_exit_hctx(struct request_queue
*q
,
1586 struct blk_mq_tag_set
*set
,
1587 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1589 unsigned flush_start_tag
= set
->queue_depth
;
1591 blk_mq_tag_idle(hctx
);
1593 if (set
->ops
->exit_request
)
1594 set
->ops
->exit_request(set
->driver_data
,
1595 hctx
->fq
->flush_rq
, hctx_idx
,
1596 flush_start_tag
+ hctx_idx
);
1598 if (set
->ops
->exit_hctx
)
1599 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1601 blk_mq_remove_cpuhp(hctx
);
1602 blk_free_flush_queue(hctx
->fq
);
1603 sbitmap_free(&hctx
->ctx_map
);
1606 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1607 struct blk_mq_tag_set
*set
, int nr_queue
)
1609 struct blk_mq_hw_ctx
*hctx
;
1612 queue_for_each_hw_ctx(q
, hctx
, i
) {
1615 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1619 static void blk_mq_free_hw_queues(struct request_queue
*q
,
1620 struct blk_mq_tag_set
*set
)
1622 struct blk_mq_hw_ctx
*hctx
;
1625 queue_for_each_hw_ctx(q
, hctx
, i
)
1626 free_cpumask_var(hctx
->cpumask
);
1629 static int blk_mq_init_hctx(struct request_queue
*q
,
1630 struct blk_mq_tag_set
*set
,
1631 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1634 unsigned flush_start_tag
= set
->queue_depth
;
1636 node
= hctx
->numa_node
;
1637 if (node
== NUMA_NO_NODE
)
1638 node
= hctx
->numa_node
= set
->numa_node
;
1640 INIT_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1641 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1642 spin_lock_init(&hctx
->lock
);
1643 INIT_LIST_HEAD(&hctx
->dispatch
);
1645 hctx
->queue_num
= hctx_idx
;
1646 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1648 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1650 hctx
->tags
= set
->tags
[hctx_idx
];
1653 * Allocate space for all possible cpus to avoid allocation at
1656 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1659 goto unregister_cpu_notifier
;
1661 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1667 if (set
->ops
->init_hctx
&&
1668 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1671 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1675 if (set
->ops
->init_request
&&
1676 set
->ops
->init_request(set
->driver_data
,
1677 hctx
->fq
->flush_rq
, hctx_idx
,
1678 flush_start_tag
+ hctx_idx
, node
))
1686 if (set
->ops
->exit_hctx
)
1687 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1689 sbitmap_free(&hctx
->ctx_map
);
1692 unregister_cpu_notifier
:
1693 blk_mq_remove_cpuhp(hctx
);
1697 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1698 unsigned int nr_hw_queues
)
1702 for_each_possible_cpu(i
) {
1703 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1704 struct blk_mq_hw_ctx
*hctx
;
1706 memset(__ctx
, 0, sizeof(*__ctx
));
1708 spin_lock_init(&__ctx
->lock
);
1709 INIT_LIST_HEAD(&__ctx
->rq_list
);
1712 /* If the cpu isn't online, the cpu is mapped to first hctx */
1716 hctx
= blk_mq_map_queue(q
, i
);
1719 * Set local node, IFF we have more than one hw queue. If
1720 * not, we remain on the home node of the device
1722 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1723 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
1727 static void blk_mq_map_swqueue(struct request_queue
*q
,
1728 const struct cpumask
*online_mask
)
1731 struct blk_mq_hw_ctx
*hctx
;
1732 struct blk_mq_ctx
*ctx
;
1733 struct blk_mq_tag_set
*set
= q
->tag_set
;
1736 * Avoid others reading imcomplete hctx->cpumask through sysfs
1738 mutex_lock(&q
->sysfs_lock
);
1740 queue_for_each_hw_ctx(q
, hctx
, i
) {
1741 cpumask_clear(hctx
->cpumask
);
1746 * Map software to hardware queues
1748 for_each_possible_cpu(i
) {
1749 /* If the cpu isn't online, the cpu is mapped to first hctx */
1750 if (!cpumask_test_cpu(i
, online_mask
))
1753 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1754 hctx
= blk_mq_map_queue(q
, i
);
1756 cpumask_set_cpu(i
, hctx
->cpumask
);
1757 ctx
->index_hw
= hctx
->nr_ctx
;
1758 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
1761 mutex_unlock(&q
->sysfs_lock
);
1763 queue_for_each_hw_ctx(q
, hctx
, i
) {
1765 * If no software queues are mapped to this hardware queue,
1766 * disable it and free the request entries.
1768 if (!hctx
->nr_ctx
) {
1770 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
1771 set
->tags
[i
] = NULL
;
1777 /* unmapped hw queue can be remapped after CPU topo changed */
1779 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
1780 hctx
->tags
= set
->tags
[i
];
1781 WARN_ON(!hctx
->tags
);
1784 * Set the map size to the number of mapped software queues.
1785 * This is more accurate and more efficient than looping
1786 * over all possibly mapped software queues.
1788 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
1791 * Initialize batch roundrobin counts
1793 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
1794 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1798 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
1800 struct blk_mq_hw_ctx
*hctx
;
1803 queue_for_each_hw_ctx(q
, hctx
, i
) {
1805 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
1807 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1811 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
1813 struct request_queue
*q
;
1815 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
1816 blk_mq_freeze_queue(q
);
1817 queue_set_hctx_shared(q
, shared
);
1818 blk_mq_unfreeze_queue(q
);
1822 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
1824 struct blk_mq_tag_set
*set
= q
->tag_set
;
1826 mutex_lock(&set
->tag_list_lock
);
1827 list_del_init(&q
->tag_set_list
);
1828 if (list_is_singular(&set
->tag_list
)) {
1829 /* just transitioned to unshared */
1830 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1831 /* update existing queue */
1832 blk_mq_update_tag_set_depth(set
, false);
1834 mutex_unlock(&set
->tag_list_lock
);
1837 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
1838 struct request_queue
*q
)
1842 mutex_lock(&set
->tag_list_lock
);
1844 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1845 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1846 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
1847 /* update existing queue */
1848 blk_mq_update_tag_set_depth(set
, true);
1850 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
1851 queue_set_hctx_shared(q
, true);
1852 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
1854 mutex_unlock(&set
->tag_list_lock
);
1858 * It is the actual release handler for mq, but we do it from
1859 * request queue's release handler for avoiding use-after-free
1860 * and headache because q->mq_kobj shouldn't have been introduced,
1861 * but we can't group ctx/kctx kobj without it.
1863 void blk_mq_release(struct request_queue
*q
)
1865 struct blk_mq_hw_ctx
*hctx
;
1868 /* hctx kobj stays in hctx */
1869 queue_for_each_hw_ctx(q
, hctx
, i
) {
1878 kfree(q
->queue_hw_ctx
);
1880 /* ctx kobj stays in queue_ctx */
1881 free_percpu(q
->queue_ctx
);
1884 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
1886 struct request_queue
*uninit_q
, *q
;
1888 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
1890 return ERR_PTR(-ENOMEM
);
1892 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
1894 blk_cleanup_queue(uninit_q
);
1898 EXPORT_SYMBOL(blk_mq_init_queue
);
1900 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
1901 struct request_queue
*q
)
1904 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
1906 blk_mq_sysfs_unregister(q
);
1907 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
1913 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
1914 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
1919 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
1926 atomic_set(&hctxs
[i
]->nr_active
, 0);
1927 hctxs
[i
]->numa_node
= node
;
1928 hctxs
[i
]->queue_num
= i
;
1930 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
1931 free_cpumask_var(hctxs
[i
]->cpumask
);
1936 blk_mq_hctx_kobj_init(hctxs
[i
]);
1938 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
1939 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
1943 blk_mq_free_rq_map(set
, hctx
->tags
, j
);
1944 set
->tags
[j
] = NULL
;
1946 blk_mq_exit_hctx(q
, set
, hctx
, j
);
1947 free_cpumask_var(hctx
->cpumask
);
1948 kobject_put(&hctx
->kobj
);
1955 q
->nr_hw_queues
= i
;
1956 blk_mq_sysfs_register(q
);
1959 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
1960 struct request_queue
*q
)
1962 /* mark the queue as mq asap */
1963 q
->mq_ops
= set
->ops
;
1965 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
1969 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
1970 GFP_KERNEL
, set
->numa_node
);
1971 if (!q
->queue_hw_ctx
)
1974 q
->mq_map
= set
->mq_map
;
1976 blk_mq_realloc_hw_ctxs(set
, q
);
1977 if (!q
->nr_hw_queues
)
1980 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
1981 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
1983 q
->nr_queues
= nr_cpu_ids
;
1985 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
1987 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
1988 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
1990 q
->sg_reserved_size
= INT_MAX
;
1992 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
1993 INIT_LIST_HEAD(&q
->requeue_list
);
1994 spin_lock_init(&q
->requeue_lock
);
1996 if (q
->nr_hw_queues
> 1)
1997 blk_queue_make_request(q
, blk_mq_make_request
);
1999 blk_queue_make_request(q
, blk_sq_make_request
);
2002 * Do this after blk_queue_make_request() overrides it...
2004 q
->nr_requests
= set
->queue_depth
;
2006 if (set
->ops
->complete
)
2007 blk_queue_softirq_done(q
, set
->ops
->complete
);
2009 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2012 mutex_lock(&all_q_mutex
);
2014 list_add_tail(&q
->all_q_node
, &all_q_list
);
2015 blk_mq_add_queue_tag_set(set
, q
);
2016 blk_mq_map_swqueue(q
, cpu_online_mask
);
2018 mutex_unlock(&all_q_mutex
);
2024 kfree(q
->queue_hw_ctx
);
2026 free_percpu(q
->queue_ctx
);
2029 return ERR_PTR(-ENOMEM
);
2031 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2033 void blk_mq_free_queue(struct request_queue
*q
)
2035 struct blk_mq_tag_set
*set
= q
->tag_set
;
2037 mutex_lock(&all_q_mutex
);
2038 list_del_init(&q
->all_q_node
);
2039 mutex_unlock(&all_q_mutex
);
2041 blk_mq_del_queue_tag_set(q
);
2043 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2044 blk_mq_free_hw_queues(q
, set
);
2047 /* Basically redo blk_mq_init_queue with queue frozen */
2048 static void blk_mq_queue_reinit(struct request_queue
*q
,
2049 const struct cpumask
*online_mask
)
2051 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2053 blk_mq_sysfs_unregister(q
);
2056 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2057 * we should change hctx numa_node according to new topology (this
2058 * involves free and re-allocate memory, worthy doing?)
2061 blk_mq_map_swqueue(q
, online_mask
);
2063 blk_mq_sysfs_register(q
);
2067 * New online cpumask which is going to be set in this hotplug event.
2068 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2069 * one-by-one and dynamically allocating this could result in a failure.
2071 static struct cpumask cpuhp_online_new
;
2073 static void blk_mq_queue_reinit_work(void)
2075 struct request_queue
*q
;
2077 mutex_lock(&all_q_mutex
);
2079 * We need to freeze and reinit all existing queues. Freezing
2080 * involves synchronous wait for an RCU grace period and doing it
2081 * one by one may take a long time. Start freezing all queues in
2082 * one swoop and then wait for the completions so that freezing can
2083 * take place in parallel.
2085 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2086 blk_mq_freeze_queue_start(q
);
2087 list_for_each_entry(q
, &all_q_list
, all_q_node
) {
2088 blk_mq_freeze_queue_wait(q
);
2091 * timeout handler can't touch hw queue during the
2094 del_timer_sync(&q
->timeout
);
2097 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2098 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2100 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2101 blk_mq_unfreeze_queue(q
);
2103 mutex_unlock(&all_q_mutex
);
2106 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2108 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2109 blk_mq_queue_reinit_work();
2114 * Before hotadded cpu starts handling requests, new mappings must be
2115 * established. Otherwise, these requests in hw queue might never be
2118 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2119 * for CPU0, and ctx1 for CPU1).
2121 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2122 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2124 * And then while running hw queue, flush_busy_ctxs() finds bit0 is set in
2125 * pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2126 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list
2129 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2131 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2132 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2133 blk_mq_queue_reinit_work();
2137 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2141 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2142 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
2151 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2157 * Allocate the request maps associated with this tag_set. Note that this
2158 * may reduce the depth asked for, if memory is tight. set->queue_depth
2159 * will be updated to reflect the allocated depth.
2161 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2166 depth
= set
->queue_depth
;
2168 err
= __blk_mq_alloc_rq_maps(set
);
2172 set
->queue_depth
>>= 1;
2173 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2177 } while (set
->queue_depth
);
2179 if (!set
->queue_depth
|| err
) {
2180 pr_err("blk-mq: failed to allocate request map\n");
2184 if (depth
!= set
->queue_depth
)
2185 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2186 depth
, set
->queue_depth
);
2192 * Alloc a tag set to be associated with one or more request queues.
2193 * May fail with EINVAL for various error conditions. May adjust the
2194 * requested depth down, if if it too large. In that case, the set
2195 * value will be stored in set->queue_depth.
2197 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2201 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2203 if (!set
->nr_hw_queues
)
2205 if (!set
->queue_depth
)
2207 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2210 if (!set
->ops
->queue_rq
)
2213 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2214 pr_info("blk-mq: reduced tag depth to %u\n",
2216 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2220 * If a crashdump is active, then we are potentially in a very
2221 * memory constrained environment. Limit us to 1 queue and
2222 * 64 tags to prevent using too much memory.
2224 if (is_kdump_kernel()) {
2225 set
->nr_hw_queues
= 1;
2226 set
->queue_depth
= min(64U, set
->queue_depth
);
2229 * There is no use for more h/w queues than cpus.
2231 if (set
->nr_hw_queues
> nr_cpu_ids
)
2232 set
->nr_hw_queues
= nr_cpu_ids
;
2234 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2235 GFP_KERNEL
, set
->numa_node
);
2240 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2241 GFP_KERNEL
, set
->numa_node
);
2245 if (set
->ops
->map_queues
)
2246 ret
= set
->ops
->map_queues(set
);
2248 ret
= blk_mq_map_queues(set
);
2250 goto out_free_mq_map
;
2252 ret
= blk_mq_alloc_rq_maps(set
);
2254 goto out_free_mq_map
;
2256 mutex_init(&set
->tag_list_lock
);
2257 INIT_LIST_HEAD(&set
->tag_list
);
2269 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2271 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2275 for (i
= 0; i
< nr_cpu_ids
; i
++) {
2277 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2286 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2288 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2290 struct blk_mq_tag_set
*set
= q
->tag_set
;
2291 struct blk_mq_hw_ctx
*hctx
;
2294 if (!set
|| nr
> set
->queue_depth
)
2298 queue_for_each_hw_ctx(q
, hctx
, i
) {
2301 ret
= blk_mq_tag_update_depth(hctx
->tags
, nr
);
2307 q
->nr_requests
= nr
;
2312 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2314 struct request_queue
*q
;
2316 if (nr_hw_queues
> nr_cpu_ids
)
2317 nr_hw_queues
= nr_cpu_ids
;
2318 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2321 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2322 blk_mq_freeze_queue(q
);
2324 set
->nr_hw_queues
= nr_hw_queues
;
2325 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2326 blk_mq_realloc_hw_ctxs(set
, q
);
2328 if (q
->nr_hw_queues
> 1)
2329 blk_queue_make_request(q
, blk_mq_make_request
);
2331 blk_queue_make_request(q
, blk_sq_make_request
);
2333 blk_mq_queue_reinit(q
, cpu_online_mask
);
2336 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2337 blk_mq_unfreeze_queue(q
);
2339 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2341 void blk_mq_disable_hotplug(void)
2343 mutex_lock(&all_q_mutex
);
2346 void blk_mq_enable_hotplug(void)
2348 mutex_unlock(&all_q_mutex
);
2351 static int __init
blk_mq_init(void)
2353 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2354 blk_mq_hctx_notify_dead
);
2356 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2357 blk_mq_queue_reinit_prepare
,
2358 blk_mq_queue_reinit_dead
);
2361 subsys_initcall(blk_mq_init
);