2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/sched/topology.h>
24 #include <linux/sched/signal.h>
25 #include <linux/delay.h>
26 #include <linux/crash_dump.h>
27 #include <linux/prefetch.h>
29 #include <trace/events/block.h>
31 #include <linux/blk-mq.h>
34 #include "blk-mq-tag.h"
37 #include "blk-mq-sched.h"
39 static DEFINE_MUTEX(all_q_mutex
);
40 static LIST_HEAD(all_q_list
);
43 * Check if any of the ctx's have pending work in this hardware queue
45 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
47 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
48 !list_empty_careful(&hctx
->dispatch
) ||
49 blk_mq_sched_has_work(hctx
);
53 * Mark this ctx as having pending work in this hardware queue
55 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
56 struct blk_mq_ctx
*ctx
)
58 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
59 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
62 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
63 struct blk_mq_ctx
*ctx
)
65 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
68 void blk_mq_freeze_queue_start(struct request_queue
*q
)
72 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
73 if (freeze_depth
== 1) {
74 percpu_ref_kill(&q
->q_usage_counter
);
75 blk_mq_run_hw_queues(q
, false);
78 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
80 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
82 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
84 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
86 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
87 unsigned long timeout
)
89 return wait_event_timeout(q
->mq_freeze_wq
,
90 percpu_ref_is_zero(&q
->q_usage_counter
),
93 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
96 * Guarantee no request is in use, so we can change any data structure of
97 * the queue afterward.
99 void blk_freeze_queue(struct request_queue
*q
)
102 * In the !blk_mq case we are only calling this to kill the
103 * q_usage_counter, otherwise this increases the freeze depth
104 * and waits for it to return to zero. For this reason there is
105 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
106 * exported to drivers as the only user for unfreeze is blk_mq.
108 blk_mq_freeze_queue_start(q
);
109 blk_mq_freeze_queue_wait(q
);
112 void blk_mq_freeze_queue(struct request_queue
*q
)
115 * ...just an alias to keep freeze and unfreeze actions balanced
116 * in the blk_mq_* namespace
120 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
122 void blk_mq_unfreeze_queue(struct request_queue
*q
)
126 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
127 WARN_ON_ONCE(freeze_depth
< 0);
129 percpu_ref_reinit(&q
->q_usage_counter
);
130 wake_up_all(&q
->mq_freeze_wq
);
133 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
136 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
139 * Note: this function does not prevent that the struct request end_io()
140 * callback function is invoked. Additionally, it is not prevented that
141 * new queue_rq() calls occur unless the queue has been stopped first.
143 void blk_mq_quiesce_queue(struct request_queue
*q
)
145 struct blk_mq_hw_ctx
*hctx
;
149 blk_mq_stop_hw_queues(q
);
151 queue_for_each_hw_ctx(q
, hctx
, i
) {
152 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
153 synchronize_srcu(&hctx
->queue_rq_srcu
);
160 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
162 void blk_mq_wake_waiters(struct request_queue
*q
)
164 struct blk_mq_hw_ctx
*hctx
;
167 queue_for_each_hw_ctx(q
, hctx
, i
)
168 if (blk_mq_hw_queue_mapped(hctx
))
169 blk_mq_tag_wakeup_all(hctx
->tags
, true);
172 * If we are called because the queue has now been marked as
173 * dying, we need to ensure that processes currently waiting on
174 * the queue are notified as well.
176 wake_up_all(&q
->mq_freeze_wq
);
179 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
181 return blk_mq_has_free_tags(hctx
->tags
);
183 EXPORT_SYMBOL(blk_mq_can_queue
);
185 void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
186 struct request
*rq
, unsigned int op
)
188 INIT_LIST_HEAD(&rq
->queuelist
);
189 /* csd/requeue_work/fifo_time is initialized before use */
193 if (blk_queue_io_stat(q
))
194 rq
->rq_flags
|= RQF_IO_STAT
;
195 /* do not touch atomic flags, it needs atomic ops against the timer */
197 INIT_HLIST_NODE(&rq
->hash
);
198 RB_CLEAR_NODE(&rq
->rb_node
);
201 rq
->start_time
= jiffies
;
202 #ifdef CONFIG_BLK_CGROUP
204 set_start_time_ns(rq
);
205 rq
->io_start_time_ns
= 0;
207 rq
->nr_phys_segments
= 0;
208 #if defined(CONFIG_BLK_DEV_INTEGRITY)
209 rq
->nr_integrity_segments
= 0;
212 /* tag was already set */
216 INIT_LIST_HEAD(&rq
->timeout_list
);
220 rq
->end_io_data
= NULL
;
223 ctx
->rq_dispatched
[op_is_sync(op
)]++;
225 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init
);
227 struct request
*__blk_mq_alloc_request(struct blk_mq_alloc_data
*data
,
233 tag
= blk_mq_get_tag(data
);
234 if (tag
!= BLK_MQ_TAG_FAIL
) {
235 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
237 rq
= tags
->static_rqs
[tag
];
239 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
241 rq
->internal_tag
= tag
;
243 if (blk_mq_tag_busy(data
->hctx
)) {
244 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
245 atomic_inc(&data
->hctx
->nr_active
);
248 rq
->internal_tag
= -1;
249 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
252 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
);
258 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request
);
260 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
263 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
267 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
271 rq
= blk_mq_sched_get_request(q
, NULL
, rw
, &alloc_data
);
273 blk_mq_put_ctx(alloc_data
.ctx
);
277 return ERR_PTR(-EWOULDBLOCK
);
280 rq
->__sector
= (sector_t
) -1;
281 rq
->bio
= rq
->biotail
= NULL
;
284 EXPORT_SYMBOL(blk_mq_alloc_request
);
286 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
287 unsigned int flags
, unsigned int hctx_idx
)
289 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
295 * If the tag allocator sleeps we could get an allocation for a
296 * different hardware context. No need to complicate the low level
297 * allocator for this for the rare use case of a command tied to
300 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
301 return ERR_PTR(-EINVAL
);
303 if (hctx_idx
>= q
->nr_hw_queues
)
304 return ERR_PTR(-EIO
);
306 ret
= blk_queue_enter(q
, true);
311 * Check if the hardware context is actually mapped to anything.
312 * If not tell the caller that it should skip this queue.
314 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
315 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
317 return ERR_PTR(-EXDEV
);
319 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
320 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
322 rq
= blk_mq_sched_get_request(q
, NULL
, rw
, &alloc_data
);
327 return ERR_PTR(-EWOULDBLOCK
);
331 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
333 void __blk_mq_finish_request(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
336 const int sched_tag
= rq
->internal_tag
;
337 struct request_queue
*q
= rq
->q
;
339 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
340 atomic_dec(&hctx
->nr_active
);
342 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
345 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
346 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
348 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
350 blk_mq_sched_completed_request(hctx
, rq
);
351 blk_mq_sched_restart_queues(hctx
);
355 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx
*hctx
,
358 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
360 ctx
->rq_completed
[rq_is_sync(rq
)]++;
361 __blk_mq_finish_request(hctx
, ctx
, rq
);
364 void blk_mq_finish_request(struct request
*rq
)
366 blk_mq_finish_hctx_request(blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
), rq
);
369 void blk_mq_free_request(struct request
*rq
)
371 blk_mq_sched_put_request(rq
);
373 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
375 inline void __blk_mq_end_request(struct request
*rq
, int error
)
377 blk_account_io_done(rq
);
380 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
381 rq
->end_io(rq
, error
);
383 if (unlikely(blk_bidi_rq(rq
)))
384 blk_mq_free_request(rq
->next_rq
);
385 blk_mq_free_request(rq
);
388 EXPORT_SYMBOL(__blk_mq_end_request
);
390 void blk_mq_end_request(struct request
*rq
, int error
)
392 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
394 __blk_mq_end_request(rq
, error
);
396 EXPORT_SYMBOL(blk_mq_end_request
);
398 static void __blk_mq_complete_request_remote(void *data
)
400 struct request
*rq
= data
;
402 rq
->q
->softirq_done_fn(rq
);
405 static void blk_mq_ipi_complete_request(struct request
*rq
)
407 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
411 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
412 rq
->q
->softirq_done_fn(rq
);
417 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
418 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
420 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
421 rq
->csd
.func
= __blk_mq_complete_request_remote
;
424 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
426 rq
->q
->softirq_done_fn(rq
);
431 static void blk_mq_stat_add(struct request
*rq
)
433 if (rq
->rq_flags
& RQF_STATS
) {
435 * We could rq->mq_ctx here, but there's less of a risk
436 * of races if we have the completion event add the stats
437 * to the local software queue.
439 struct blk_mq_ctx
*ctx
;
441 ctx
= __blk_mq_get_ctx(rq
->q
, raw_smp_processor_id());
442 blk_stat_add(&ctx
->stat
[rq_data_dir(rq
)], rq
);
446 static void __blk_mq_complete_request(struct request
*rq
)
448 struct request_queue
*q
= rq
->q
;
452 if (!q
->softirq_done_fn
)
453 blk_mq_end_request(rq
, rq
->errors
);
455 blk_mq_ipi_complete_request(rq
);
459 * blk_mq_complete_request - end I/O on a request
460 * @rq: the request being processed
463 * Ends all I/O on a request. It does not handle partial completions.
464 * The actual completion happens out-of-order, through a IPI handler.
466 void blk_mq_complete_request(struct request
*rq
, int error
)
468 struct request_queue
*q
= rq
->q
;
470 if (unlikely(blk_should_fake_timeout(q
)))
472 if (!blk_mark_rq_complete(rq
)) {
474 __blk_mq_complete_request(rq
);
477 EXPORT_SYMBOL(blk_mq_complete_request
);
479 int blk_mq_request_started(struct request
*rq
)
481 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
483 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
485 void blk_mq_start_request(struct request
*rq
)
487 struct request_queue
*q
= rq
->q
;
489 blk_mq_sched_started_request(rq
);
491 trace_block_rq_issue(q
, rq
);
493 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
494 blk_stat_set_issue_time(&rq
->issue_stat
);
495 rq
->rq_flags
|= RQF_STATS
;
496 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
502 * Ensure that ->deadline is visible before set the started
503 * flag and clear the completed flag.
505 smp_mb__before_atomic();
508 * Mark us as started and clear complete. Complete might have been
509 * set if requeue raced with timeout, which then marked it as
510 * complete. So be sure to clear complete again when we start
511 * the request, otherwise we'll ignore the completion event.
513 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
514 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
515 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
516 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
518 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
520 * Make sure space for the drain appears. We know we can do
521 * this because max_hw_segments has been adjusted to be one
522 * fewer than the device can handle.
524 rq
->nr_phys_segments
++;
527 EXPORT_SYMBOL(blk_mq_start_request
);
529 static void __blk_mq_requeue_request(struct request
*rq
)
531 struct request_queue
*q
= rq
->q
;
533 trace_block_rq_requeue(q
, rq
);
534 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
535 blk_mq_sched_requeue_request(rq
);
537 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
538 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
539 rq
->nr_phys_segments
--;
543 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
545 __blk_mq_requeue_request(rq
);
547 BUG_ON(blk_queued_rq(rq
));
548 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
550 EXPORT_SYMBOL(blk_mq_requeue_request
);
552 static void blk_mq_requeue_work(struct work_struct
*work
)
554 struct request_queue
*q
=
555 container_of(work
, struct request_queue
, requeue_work
.work
);
557 struct request
*rq
, *next
;
560 spin_lock_irqsave(&q
->requeue_lock
, flags
);
561 list_splice_init(&q
->requeue_list
, &rq_list
);
562 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
564 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
565 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
568 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
569 list_del_init(&rq
->queuelist
);
570 blk_mq_sched_insert_request(rq
, true, false, false, true);
573 while (!list_empty(&rq_list
)) {
574 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
575 list_del_init(&rq
->queuelist
);
576 blk_mq_sched_insert_request(rq
, false, false, false, true);
579 blk_mq_run_hw_queues(q
, false);
582 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
583 bool kick_requeue_list
)
585 struct request_queue
*q
= rq
->q
;
589 * We abuse this flag that is otherwise used by the I/O scheduler to
590 * request head insertation from the workqueue.
592 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
594 spin_lock_irqsave(&q
->requeue_lock
, flags
);
596 rq
->rq_flags
|= RQF_SOFTBARRIER
;
597 list_add(&rq
->queuelist
, &q
->requeue_list
);
599 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
601 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
603 if (kick_requeue_list
)
604 blk_mq_kick_requeue_list(q
);
606 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
608 void blk_mq_kick_requeue_list(struct request_queue
*q
)
610 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
612 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
614 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
617 kblockd_schedule_delayed_work(&q
->requeue_work
,
618 msecs_to_jiffies(msecs
));
620 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
622 void blk_mq_abort_requeue_list(struct request_queue
*q
)
627 spin_lock_irqsave(&q
->requeue_lock
, flags
);
628 list_splice_init(&q
->requeue_list
, &rq_list
);
629 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
631 while (!list_empty(&rq_list
)) {
634 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
635 list_del_init(&rq
->queuelist
);
637 blk_mq_end_request(rq
, rq
->errors
);
640 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
642 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
644 if (tag
< tags
->nr_tags
) {
645 prefetch(tags
->rqs
[tag
]);
646 return tags
->rqs
[tag
];
651 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
653 struct blk_mq_timeout_data
{
655 unsigned int next_set
;
658 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
660 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
661 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
664 * We know that complete is set at this point. If STARTED isn't set
665 * anymore, then the request isn't active and the "timeout" should
666 * just be ignored. This can happen due to the bitflag ordering.
667 * Timeout first checks if STARTED is set, and if it is, assumes
668 * the request is active. But if we race with completion, then
669 * we both flags will get cleared. So check here again, and ignore
670 * a timeout event with a request that isn't active.
672 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
676 ret
= ops
->timeout(req
, reserved
);
680 __blk_mq_complete_request(req
);
682 case BLK_EH_RESET_TIMER
:
684 blk_clear_rq_complete(req
);
686 case BLK_EH_NOT_HANDLED
:
689 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
694 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
695 struct request
*rq
, void *priv
, bool reserved
)
697 struct blk_mq_timeout_data
*data
= priv
;
699 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
702 if (time_after_eq(jiffies
, rq
->deadline
)) {
703 if (!blk_mark_rq_complete(rq
))
704 blk_mq_rq_timed_out(rq
, reserved
);
705 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
706 data
->next
= rq
->deadline
;
711 static void blk_mq_timeout_work(struct work_struct
*work
)
713 struct request_queue
*q
=
714 container_of(work
, struct request_queue
, timeout_work
);
715 struct blk_mq_timeout_data data
= {
721 /* A deadlock might occur if a request is stuck requiring a
722 * timeout at the same time a queue freeze is waiting
723 * completion, since the timeout code would not be able to
724 * acquire the queue reference here.
726 * That's why we don't use blk_queue_enter here; instead, we use
727 * percpu_ref_tryget directly, because we need to be able to
728 * obtain a reference even in the short window between the queue
729 * starting to freeze, by dropping the first reference in
730 * blk_mq_freeze_queue_start, and the moment the last request is
731 * consumed, marked by the instant q_usage_counter reaches
734 if (!percpu_ref_tryget(&q
->q_usage_counter
))
737 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
740 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
741 mod_timer(&q
->timeout
, data
.next
);
743 struct blk_mq_hw_ctx
*hctx
;
745 queue_for_each_hw_ctx(q
, hctx
, i
) {
746 /* the hctx may be unmapped, so check it here */
747 if (blk_mq_hw_queue_mapped(hctx
))
748 blk_mq_tag_idle(hctx
);
755 * Reverse check our software queue for entries that we could potentially
756 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
757 * too much time checking for merges.
759 static bool blk_mq_attempt_merge(struct request_queue
*q
,
760 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
765 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
771 if (!blk_rq_merge_ok(rq
, bio
))
774 switch (blk_try_merge(rq
, bio
)) {
775 case ELEVATOR_BACK_MERGE
:
776 if (blk_mq_sched_allow_merge(q
, rq
, bio
))
777 merged
= bio_attempt_back_merge(q
, rq
, bio
);
779 case ELEVATOR_FRONT_MERGE
:
780 if (blk_mq_sched_allow_merge(q
, rq
, bio
))
781 merged
= bio_attempt_front_merge(q
, rq
, bio
);
783 case ELEVATOR_DISCARD_MERGE
:
784 merged
= bio_attempt_discard_merge(q
, rq
, bio
);
798 struct flush_busy_ctx_data
{
799 struct blk_mq_hw_ctx
*hctx
;
800 struct list_head
*list
;
803 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
805 struct flush_busy_ctx_data
*flush_data
= data
;
806 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
807 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
809 sbitmap_clear_bit(sb
, bitnr
);
810 spin_lock(&ctx
->lock
);
811 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
812 spin_unlock(&ctx
->lock
);
817 * Process software queues that have been marked busy, splicing them
818 * to the for-dispatch
820 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
822 struct flush_busy_ctx_data data
= {
827 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
829 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
831 static inline unsigned int queued_to_index(unsigned int queued
)
836 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
839 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
842 struct blk_mq_alloc_data data
= {
844 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
845 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
851 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
852 data
.flags
|= BLK_MQ_REQ_RESERVED
;
854 rq
->tag
= blk_mq_get_tag(&data
);
856 if (blk_mq_tag_busy(data
.hctx
)) {
857 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
858 atomic_inc(&data
.hctx
->nr_active
);
860 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
866 return rq
->tag
!= -1;
869 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
872 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
875 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
876 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
877 atomic_dec(&hctx
->nr_active
);
881 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
884 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
887 __blk_mq_put_driver_tag(hctx
, rq
);
890 static void blk_mq_put_driver_tag(struct request
*rq
)
892 struct blk_mq_hw_ctx
*hctx
;
894 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
897 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
898 __blk_mq_put_driver_tag(hctx
, rq
);
902 * If we fail getting a driver tag because all the driver tags are already
903 * assigned and on the dispatch list, BUT the first entry does not have a
904 * tag, then we could deadlock. For that case, move entries with assigned
905 * driver tags to the front, leaving the set of tagged requests in the
906 * same order, and the untagged set in the same order.
908 static bool reorder_tags_to_front(struct list_head
*list
)
910 struct request
*rq
, *tmp
, *first
= NULL
;
912 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
916 list_move(&rq
->queuelist
, list
);
922 return first
!= NULL
;
925 static int blk_mq_dispatch_wake(wait_queue_t
*wait
, unsigned mode
, int flags
,
928 struct blk_mq_hw_ctx
*hctx
;
930 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
932 list_del(&wait
->task_list
);
933 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
934 blk_mq_run_hw_queue(hctx
, true);
938 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
940 struct sbq_wait_state
*ws
;
943 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
944 * The thread which wins the race to grab this bit adds the hardware
945 * queue to the wait queue.
947 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
948 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
951 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
952 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
955 * As soon as this returns, it's no longer safe to fiddle with
956 * hctx->dispatch_wait, since a completion can wake up the wait queue
957 * and unlock the bit.
959 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
963 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
)
965 struct blk_mq_hw_ctx
*hctx
;
967 LIST_HEAD(driver_list
);
968 struct list_head
*dptr
;
969 int errors
, queued
, ret
= BLK_MQ_RQ_QUEUE_OK
;
971 if (list_empty(list
))
975 * Start off with dptr being NULL, so we start the first request
976 * immediately, even if we have more pending.
981 * Now process all the entries, sending them to the driver.
985 struct blk_mq_queue_data bd
;
987 rq
= list_first_entry(list
, struct request
, queuelist
);
988 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
989 if (!queued
&& reorder_tags_to_front(list
))
993 * The initial allocation attempt failed, so we need to
994 * rerun the hardware queue when a tag is freed.
996 if (blk_mq_dispatch_wait_add(hctx
)) {
998 * It's possible that a tag was freed in the
999 * window between the allocation failure and
1000 * adding the hardware queue to the wait queue.
1002 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1009 list_del_init(&rq
->queuelist
);
1015 * Flag last if we have no more requests, or if we have more
1016 * but can't assign a driver tag to it.
1018 if (list_empty(list
))
1021 struct request
*nxt
;
1023 nxt
= list_first_entry(list
, struct request
, queuelist
);
1024 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1027 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1029 case BLK_MQ_RQ_QUEUE_OK
:
1032 case BLK_MQ_RQ_QUEUE_BUSY
:
1033 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1034 list_add(&rq
->queuelist
, list
);
1035 __blk_mq_requeue_request(rq
);
1038 pr_err("blk-mq: bad return on queue: %d\n", ret
);
1039 case BLK_MQ_RQ_QUEUE_ERROR
:
1042 blk_mq_end_request(rq
, rq
->errors
);
1046 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
1050 * We've done the first request. If we have more than 1
1051 * left in the list, set dptr to defer issue.
1053 if (!dptr
&& list
->next
!= list
->prev
)
1054 dptr
= &driver_list
;
1055 } while (!list_empty(list
));
1057 hctx
->dispatched
[queued_to_index(queued
)]++;
1060 * Any items that need requeuing? Stuff them into hctx->dispatch,
1061 * that is where we will continue on next queue run.
1063 if (!list_empty(list
)) {
1065 * If we got a driver tag for the next request already,
1068 rq
= list_first_entry(list
, struct request
, queuelist
);
1069 blk_mq_put_driver_tag(rq
);
1071 spin_lock(&hctx
->lock
);
1072 list_splice_init(list
, &hctx
->dispatch
);
1073 spin_unlock(&hctx
->lock
);
1076 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1077 * it's possible the queue is stopped and restarted again
1078 * before this. Queue restart will dispatch requests. And since
1079 * requests in rq_list aren't added into hctx->dispatch yet,
1080 * the requests in rq_list might get lost.
1082 * blk_mq_run_hw_queue() already checks the STOPPED bit
1084 * If RESTART or TAG_WAITING is set, then let completion restart
1085 * the queue instead of potentially looping here.
1087 if (!blk_mq_sched_needs_restart(hctx
) &&
1088 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1089 blk_mq_run_hw_queue(hctx
, true);
1092 return (queued
+ errors
) != 0;
1095 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1099 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1100 cpu_online(hctx
->next_cpu
));
1102 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1104 blk_mq_sched_dispatch_requests(hctx
);
1107 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1108 blk_mq_sched_dispatch_requests(hctx
);
1109 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1114 * It'd be great if the workqueue API had a way to pass
1115 * in a mask and had some smarts for more clever placement.
1116 * For now we just round-robin here, switching for every
1117 * BLK_MQ_CPU_WORK_BATCH queued items.
1119 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1121 if (hctx
->queue
->nr_hw_queues
== 1)
1122 return WORK_CPU_UNBOUND
;
1124 if (--hctx
->next_cpu_batch
<= 0) {
1127 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1128 if (next_cpu
>= nr_cpu_ids
)
1129 next_cpu
= cpumask_first(hctx
->cpumask
);
1131 hctx
->next_cpu
= next_cpu
;
1132 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1135 return hctx
->next_cpu
;
1138 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1140 if (unlikely(blk_mq_hctx_stopped(hctx
) ||
1141 !blk_mq_hw_queue_mapped(hctx
)))
1144 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1145 int cpu
= get_cpu();
1146 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1147 __blk_mq_run_hw_queue(hctx
);
1155 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
);
1158 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1160 struct blk_mq_hw_ctx
*hctx
;
1163 queue_for_each_hw_ctx(q
, hctx
, i
) {
1164 if (!blk_mq_hctx_has_pending(hctx
) ||
1165 blk_mq_hctx_stopped(hctx
))
1168 blk_mq_run_hw_queue(hctx
, async
);
1171 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1174 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1175 * @q: request queue.
1177 * The caller is responsible for serializing this function against
1178 * blk_mq_{start,stop}_hw_queue().
1180 bool blk_mq_queue_stopped(struct request_queue
*q
)
1182 struct blk_mq_hw_ctx
*hctx
;
1185 queue_for_each_hw_ctx(q
, hctx
, i
)
1186 if (blk_mq_hctx_stopped(hctx
))
1191 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1193 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1195 cancel_work(&hctx
->run_work
);
1196 cancel_delayed_work(&hctx
->delay_work
);
1197 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1199 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1201 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1203 struct blk_mq_hw_ctx
*hctx
;
1206 queue_for_each_hw_ctx(q
, hctx
, i
)
1207 blk_mq_stop_hw_queue(hctx
);
1209 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1211 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1213 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1215 blk_mq_run_hw_queue(hctx
, false);
1217 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1219 void blk_mq_start_hw_queues(struct request_queue
*q
)
1221 struct blk_mq_hw_ctx
*hctx
;
1224 queue_for_each_hw_ctx(q
, hctx
, i
)
1225 blk_mq_start_hw_queue(hctx
);
1227 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1229 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1231 if (!blk_mq_hctx_stopped(hctx
))
1234 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1235 blk_mq_run_hw_queue(hctx
, async
);
1237 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1239 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1241 struct blk_mq_hw_ctx
*hctx
;
1244 queue_for_each_hw_ctx(q
, hctx
, i
)
1245 blk_mq_start_stopped_hw_queue(hctx
, async
);
1247 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1249 static void blk_mq_run_work_fn(struct work_struct
*work
)
1251 struct blk_mq_hw_ctx
*hctx
;
1253 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
);
1255 __blk_mq_run_hw_queue(hctx
);
1258 static void blk_mq_delay_work_fn(struct work_struct
*work
)
1260 struct blk_mq_hw_ctx
*hctx
;
1262 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
1264 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1265 __blk_mq_run_hw_queue(hctx
);
1268 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1270 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1273 blk_mq_stop_hw_queue(hctx
);
1274 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1275 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
1277 EXPORT_SYMBOL(blk_mq_delay_queue
);
1279 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1283 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1285 trace_block_rq_insert(hctx
->queue
, rq
);
1288 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1290 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1293 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1296 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1298 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1299 blk_mq_hctx_mark_pending(hctx
, ctx
);
1302 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1303 struct list_head
*list
)
1307 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1310 spin_lock(&ctx
->lock
);
1311 while (!list_empty(list
)) {
1314 rq
= list_first_entry(list
, struct request
, queuelist
);
1315 BUG_ON(rq
->mq_ctx
!= ctx
);
1316 list_del_init(&rq
->queuelist
);
1317 __blk_mq_insert_req_list(hctx
, rq
, false);
1319 blk_mq_hctx_mark_pending(hctx
, ctx
);
1320 spin_unlock(&ctx
->lock
);
1323 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1325 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1326 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1328 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1329 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1330 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1333 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1335 struct blk_mq_ctx
*this_ctx
;
1336 struct request_queue
*this_q
;
1339 LIST_HEAD(ctx_list
);
1342 list_splice_init(&plug
->mq_list
, &list
);
1344 list_sort(NULL
, &list
, plug_ctx_cmp
);
1350 while (!list_empty(&list
)) {
1351 rq
= list_entry_rq(list
.next
);
1352 list_del_init(&rq
->queuelist
);
1354 if (rq
->mq_ctx
!= this_ctx
) {
1356 trace_block_unplug(this_q
, depth
, from_schedule
);
1357 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1362 this_ctx
= rq
->mq_ctx
;
1368 list_add_tail(&rq
->queuelist
, &ctx_list
);
1372 * If 'this_ctx' is set, we know we have entries to complete
1373 * on 'ctx_list'. Do those.
1376 trace_block_unplug(this_q
, depth
, from_schedule
);
1377 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1382 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1384 init_request_from_bio(rq
, bio
);
1386 blk_account_io_start(rq
, true);
1389 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1391 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1392 !blk_queue_nomerges(hctx
->queue
);
1395 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1396 struct blk_mq_ctx
*ctx
,
1397 struct request
*rq
, struct bio
*bio
)
1399 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1400 blk_mq_bio_to_request(rq
, bio
);
1401 spin_lock(&ctx
->lock
);
1403 __blk_mq_insert_request(hctx
, rq
, false);
1404 spin_unlock(&ctx
->lock
);
1407 struct request_queue
*q
= hctx
->queue
;
1409 spin_lock(&ctx
->lock
);
1410 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1411 blk_mq_bio_to_request(rq
, bio
);
1415 spin_unlock(&ctx
->lock
);
1416 __blk_mq_finish_request(hctx
, ctx
, rq
);
1421 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1424 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1426 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1429 static void blk_mq_try_issue_directly(struct request
*rq
, blk_qc_t
*cookie
,
1432 struct request_queue
*q
= rq
->q
;
1433 struct blk_mq_queue_data bd
= {
1438 struct blk_mq_hw_ctx
*hctx
;
1439 blk_qc_t new_cookie
;
1445 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1448 new_cookie
= request_to_qc_t(hctx
, rq
);
1451 * For OK queue, we are done. For error, kill it. Any other
1452 * error (busy), just add it to our list as we previously
1455 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1456 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1457 *cookie
= new_cookie
;
1461 __blk_mq_requeue_request(rq
);
1463 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1464 *cookie
= BLK_QC_T_NONE
;
1466 blk_mq_end_request(rq
, rq
->errors
);
1471 blk_mq_sched_insert_request(rq
, false, true, false, may_sleep
);
1475 * Multiple hardware queue variant. This will not use per-process plugs,
1476 * but will attempt to bypass the hctx queueing if we can go straight to
1477 * hardware for SYNC IO.
1479 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1481 const int is_sync
= op_is_sync(bio
->bi_opf
);
1482 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1483 struct blk_mq_alloc_data data
= { .flags
= 0 };
1485 unsigned int request_count
= 0, srcu_idx
;
1486 struct blk_plug
*plug
;
1487 struct request
*same_queue_rq
= NULL
;
1489 unsigned int wb_acct
;
1491 blk_queue_bounce(q
, &bio
);
1493 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1495 return BLK_QC_T_NONE
;
1498 blk_queue_split(q
, &bio
, q
->bio_split
);
1500 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1501 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1502 return BLK_QC_T_NONE
;
1504 if (blk_mq_sched_bio_merge(q
, bio
))
1505 return BLK_QC_T_NONE
;
1507 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1509 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1511 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1512 if (unlikely(!rq
)) {
1513 __wbt_done(q
->rq_wb
, wb_acct
);
1514 return BLK_QC_T_NONE
;
1517 wbt_track(&rq
->issue_stat
, wb_acct
);
1519 cookie
= request_to_qc_t(data
.hctx
, rq
);
1521 if (unlikely(is_flush_fua
)) {
1524 blk_mq_bio_to_request(rq
, bio
);
1525 blk_insert_flush(rq
);
1529 plug
= current
->plug
;
1531 * If the driver supports defer issued based on 'last', then
1532 * queue it up like normal since we can potentially save some
1535 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1536 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1537 struct request
*old_rq
= NULL
;
1539 blk_mq_bio_to_request(rq
, bio
);
1542 * We do limited plugging. If the bio can be merged, do that.
1543 * Otherwise the existing request in the plug list will be
1544 * issued. So the plug list will have one request at most
1548 * The plug list might get flushed before this. If that
1549 * happens, same_queue_rq is invalid and plug list is
1552 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1553 old_rq
= same_queue_rq
;
1554 list_del_init(&old_rq
->queuelist
);
1556 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1557 } else /* is_sync */
1559 blk_mq_put_ctx(data
.ctx
);
1563 if (!(data
.hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1565 blk_mq_try_issue_directly(old_rq
, &cookie
, false);
1568 srcu_idx
= srcu_read_lock(&data
.hctx
->queue_rq_srcu
);
1569 blk_mq_try_issue_directly(old_rq
, &cookie
, true);
1570 srcu_read_unlock(&data
.hctx
->queue_rq_srcu
, srcu_idx
);
1577 blk_mq_put_ctx(data
.ctx
);
1578 blk_mq_bio_to_request(rq
, bio
);
1579 blk_mq_sched_insert_request(rq
, false, true,
1580 !is_sync
|| is_flush_fua
, true);
1583 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1585 * For a SYNC request, send it to the hardware immediately. For
1586 * an ASYNC request, just ensure that we run it later on. The
1587 * latter allows for merging opportunities and more efficient
1591 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1593 blk_mq_put_ctx(data
.ctx
);
1599 * Single hardware queue variant. This will attempt to use any per-process
1600 * plug for merging and IO deferral.
1602 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1604 const int is_sync
= op_is_sync(bio
->bi_opf
);
1605 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1606 struct blk_plug
*plug
;
1607 unsigned int request_count
= 0;
1608 struct blk_mq_alloc_data data
= { .flags
= 0 };
1611 unsigned int wb_acct
;
1613 blk_queue_bounce(q
, &bio
);
1615 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1617 return BLK_QC_T_NONE
;
1620 blk_queue_split(q
, &bio
, q
->bio_split
);
1622 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1623 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1624 return BLK_QC_T_NONE
;
1626 request_count
= blk_plug_queued_count(q
);
1628 if (blk_mq_sched_bio_merge(q
, bio
))
1629 return BLK_QC_T_NONE
;
1631 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1633 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1635 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1636 if (unlikely(!rq
)) {
1637 __wbt_done(q
->rq_wb
, wb_acct
);
1638 return BLK_QC_T_NONE
;
1641 wbt_track(&rq
->issue_stat
, wb_acct
);
1643 cookie
= request_to_qc_t(data
.hctx
, rq
);
1645 if (unlikely(is_flush_fua
)) {
1648 blk_mq_bio_to_request(rq
, bio
);
1649 blk_insert_flush(rq
);
1654 * A task plug currently exists. Since this is completely lockless,
1655 * utilize that to temporarily store requests until the task is
1656 * either done or scheduled away.
1658 plug
= current
->plug
;
1660 struct request
*last
= NULL
;
1662 blk_mq_bio_to_request(rq
, bio
);
1665 * @request_count may become stale because of schedule
1666 * out, so check the list again.
1668 if (list_empty(&plug
->mq_list
))
1671 trace_block_plug(q
);
1673 last
= list_entry_rq(plug
->mq_list
.prev
);
1675 blk_mq_put_ctx(data
.ctx
);
1677 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1678 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1679 blk_flush_plug_list(plug
, false);
1680 trace_block_plug(q
);
1683 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1689 blk_mq_put_ctx(data
.ctx
);
1690 blk_mq_bio_to_request(rq
, bio
);
1691 blk_mq_sched_insert_request(rq
, false, true,
1692 !is_sync
|| is_flush_fua
, true);
1695 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1697 * For a SYNC request, send it to the hardware immediately. For
1698 * an ASYNC request, just ensure that we run it later on. The
1699 * latter allows for merging opportunities and more efficient
1703 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1706 blk_mq_put_ctx(data
.ctx
);
1711 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1712 unsigned int hctx_idx
)
1716 if (tags
->rqs
&& set
->ops
->exit_request
) {
1719 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1720 struct request
*rq
= tags
->static_rqs
[i
];
1724 set
->ops
->exit_request(set
->driver_data
, rq
,
1726 tags
->static_rqs
[i
] = NULL
;
1730 while (!list_empty(&tags
->page_list
)) {
1731 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1732 list_del_init(&page
->lru
);
1734 * Remove kmemleak object previously allocated in
1735 * blk_mq_init_rq_map().
1737 kmemleak_free(page_address(page
));
1738 __free_pages(page
, page
->private);
1742 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1746 kfree(tags
->static_rqs
);
1747 tags
->static_rqs
= NULL
;
1749 blk_mq_free_tags(tags
);
1752 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1753 unsigned int hctx_idx
,
1754 unsigned int nr_tags
,
1755 unsigned int reserved_tags
)
1757 struct blk_mq_tags
*tags
;
1760 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1761 if (node
== NUMA_NO_NODE
)
1762 node
= set
->numa_node
;
1764 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1765 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1769 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1770 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1773 blk_mq_free_tags(tags
);
1777 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1778 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1780 if (!tags
->static_rqs
) {
1782 blk_mq_free_tags(tags
);
1789 static size_t order_to_size(unsigned int order
)
1791 return (size_t)PAGE_SIZE
<< order
;
1794 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1795 unsigned int hctx_idx
, unsigned int depth
)
1797 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1798 size_t rq_size
, left
;
1801 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1802 if (node
== NUMA_NO_NODE
)
1803 node
= set
->numa_node
;
1805 INIT_LIST_HEAD(&tags
->page_list
);
1808 * rq_size is the size of the request plus driver payload, rounded
1809 * to the cacheline size
1811 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1813 left
= rq_size
* depth
;
1815 for (i
= 0; i
< depth
; ) {
1816 int this_order
= max_order
;
1821 while (this_order
&& left
< order_to_size(this_order
- 1))
1825 page
= alloc_pages_node(node
,
1826 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1832 if (order_to_size(this_order
) < rq_size
)
1839 page
->private = this_order
;
1840 list_add_tail(&page
->lru
, &tags
->page_list
);
1842 p
= page_address(page
);
1844 * Allow kmemleak to scan these pages as they contain pointers
1845 * to additional allocations like via ops->init_request().
1847 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1848 entries_per_page
= order_to_size(this_order
) / rq_size
;
1849 to_do
= min(entries_per_page
, depth
- i
);
1850 left
-= to_do
* rq_size
;
1851 for (j
= 0; j
< to_do
; j
++) {
1852 struct request
*rq
= p
;
1854 tags
->static_rqs
[i
] = rq
;
1855 if (set
->ops
->init_request
) {
1856 if (set
->ops
->init_request(set
->driver_data
,
1859 tags
->static_rqs
[i
] = NULL
;
1871 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1876 * 'cpu' is going away. splice any existing rq_list entries from this
1877 * software queue to the hw queue dispatch list, and ensure that it
1880 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1882 struct blk_mq_hw_ctx
*hctx
;
1883 struct blk_mq_ctx
*ctx
;
1886 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1887 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1889 spin_lock(&ctx
->lock
);
1890 if (!list_empty(&ctx
->rq_list
)) {
1891 list_splice_init(&ctx
->rq_list
, &tmp
);
1892 blk_mq_hctx_clear_pending(hctx
, ctx
);
1894 spin_unlock(&ctx
->lock
);
1896 if (list_empty(&tmp
))
1899 spin_lock(&hctx
->lock
);
1900 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1901 spin_unlock(&hctx
->lock
);
1903 blk_mq_run_hw_queue(hctx
, true);
1907 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1909 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1913 /* hctx->ctxs will be freed in queue's release handler */
1914 static void blk_mq_exit_hctx(struct request_queue
*q
,
1915 struct blk_mq_tag_set
*set
,
1916 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1918 unsigned flush_start_tag
= set
->queue_depth
;
1920 blk_mq_tag_idle(hctx
);
1922 if (set
->ops
->exit_request
)
1923 set
->ops
->exit_request(set
->driver_data
,
1924 hctx
->fq
->flush_rq
, hctx_idx
,
1925 flush_start_tag
+ hctx_idx
);
1927 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1929 if (set
->ops
->exit_hctx
)
1930 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1932 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1933 cleanup_srcu_struct(&hctx
->queue_rq_srcu
);
1935 blk_mq_remove_cpuhp(hctx
);
1936 blk_free_flush_queue(hctx
->fq
);
1937 sbitmap_free(&hctx
->ctx_map
);
1940 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1941 struct blk_mq_tag_set
*set
, int nr_queue
)
1943 struct blk_mq_hw_ctx
*hctx
;
1946 queue_for_each_hw_ctx(q
, hctx
, i
) {
1949 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1953 static int blk_mq_init_hctx(struct request_queue
*q
,
1954 struct blk_mq_tag_set
*set
,
1955 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1958 unsigned flush_start_tag
= set
->queue_depth
;
1960 node
= hctx
->numa_node
;
1961 if (node
== NUMA_NO_NODE
)
1962 node
= hctx
->numa_node
= set
->numa_node
;
1964 INIT_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1965 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1966 spin_lock_init(&hctx
->lock
);
1967 INIT_LIST_HEAD(&hctx
->dispatch
);
1969 hctx
->queue_num
= hctx_idx
;
1970 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1972 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1974 hctx
->tags
= set
->tags
[hctx_idx
];
1977 * Allocate space for all possible cpus to avoid allocation at
1980 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1983 goto unregister_cpu_notifier
;
1985 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1991 if (set
->ops
->init_hctx
&&
1992 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1995 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
1998 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
2000 goto sched_exit_hctx
;
2002 if (set
->ops
->init_request
&&
2003 set
->ops
->init_request(set
->driver_data
,
2004 hctx
->fq
->flush_rq
, hctx_idx
,
2005 flush_start_tag
+ hctx_idx
, node
))
2008 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2009 init_srcu_struct(&hctx
->queue_rq_srcu
);
2016 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2018 if (set
->ops
->exit_hctx
)
2019 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2021 sbitmap_free(&hctx
->ctx_map
);
2024 unregister_cpu_notifier
:
2025 blk_mq_remove_cpuhp(hctx
);
2029 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2030 unsigned int nr_hw_queues
)
2034 for_each_possible_cpu(i
) {
2035 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2036 struct blk_mq_hw_ctx
*hctx
;
2039 spin_lock_init(&__ctx
->lock
);
2040 INIT_LIST_HEAD(&__ctx
->rq_list
);
2042 blk_stat_init(&__ctx
->stat
[BLK_STAT_READ
]);
2043 blk_stat_init(&__ctx
->stat
[BLK_STAT_WRITE
]);
2045 /* If the cpu isn't online, the cpu is mapped to first hctx */
2049 hctx
= blk_mq_map_queue(q
, i
);
2052 * Set local node, IFF we have more than one hw queue. If
2053 * not, we remain on the home node of the device
2055 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2056 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2060 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2064 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2065 set
->queue_depth
, set
->reserved_tags
);
2066 if (!set
->tags
[hctx_idx
])
2069 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2074 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2075 set
->tags
[hctx_idx
] = NULL
;
2079 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2080 unsigned int hctx_idx
)
2082 if (set
->tags
[hctx_idx
]) {
2083 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2084 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2085 set
->tags
[hctx_idx
] = NULL
;
2089 static void blk_mq_map_swqueue(struct request_queue
*q
,
2090 const struct cpumask
*online_mask
)
2092 unsigned int i
, hctx_idx
;
2093 struct blk_mq_hw_ctx
*hctx
;
2094 struct blk_mq_ctx
*ctx
;
2095 struct blk_mq_tag_set
*set
= q
->tag_set
;
2098 * Avoid others reading imcomplete hctx->cpumask through sysfs
2100 mutex_lock(&q
->sysfs_lock
);
2102 queue_for_each_hw_ctx(q
, hctx
, i
) {
2103 cpumask_clear(hctx
->cpumask
);
2108 * Map software to hardware queues
2110 for_each_possible_cpu(i
) {
2111 /* If the cpu isn't online, the cpu is mapped to first hctx */
2112 if (!cpumask_test_cpu(i
, online_mask
))
2115 hctx_idx
= q
->mq_map
[i
];
2116 /* unmapped hw queue can be remapped after CPU topo changed */
2117 if (!set
->tags
[hctx_idx
] &&
2118 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2120 * If tags initialization fail for some hctx,
2121 * that hctx won't be brought online. In this
2122 * case, remap the current ctx to hctx[0] which
2123 * is guaranteed to always have tags allocated
2128 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2129 hctx
= blk_mq_map_queue(q
, i
);
2131 cpumask_set_cpu(i
, hctx
->cpumask
);
2132 ctx
->index_hw
= hctx
->nr_ctx
;
2133 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2136 mutex_unlock(&q
->sysfs_lock
);
2138 queue_for_each_hw_ctx(q
, hctx
, i
) {
2140 * If no software queues are mapped to this hardware queue,
2141 * disable it and free the request entries.
2143 if (!hctx
->nr_ctx
) {
2144 /* Never unmap queue 0. We need it as a
2145 * fallback in case of a new remap fails
2148 if (i
&& set
->tags
[i
])
2149 blk_mq_free_map_and_requests(set
, i
);
2155 hctx
->tags
= set
->tags
[i
];
2156 WARN_ON(!hctx
->tags
);
2159 * Set the map size to the number of mapped software queues.
2160 * This is more accurate and more efficient than looping
2161 * over all possibly mapped software queues.
2163 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2166 * Initialize batch roundrobin counts
2168 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2169 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2173 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2175 struct blk_mq_hw_ctx
*hctx
;
2178 queue_for_each_hw_ctx(q
, hctx
, i
) {
2180 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2182 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2186 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
2188 struct request_queue
*q
;
2190 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2191 blk_mq_freeze_queue(q
);
2192 queue_set_hctx_shared(q
, shared
);
2193 blk_mq_unfreeze_queue(q
);
2197 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2199 struct blk_mq_tag_set
*set
= q
->tag_set
;
2201 mutex_lock(&set
->tag_list_lock
);
2202 list_del_init(&q
->tag_set_list
);
2203 if (list_is_singular(&set
->tag_list
)) {
2204 /* just transitioned to unshared */
2205 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2206 /* update existing queue */
2207 blk_mq_update_tag_set_depth(set
, false);
2209 mutex_unlock(&set
->tag_list_lock
);
2212 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2213 struct request_queue
*q
)
2217 mutex_lock(&set
->tag_list_lock
);
2219 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2220 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2221 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2222 /* update existing queue */
2223 blk_mq_update_tag_set_depth(set
, true);
2225 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2226 queue_set_hctx_shared(q
, true);
2227 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
2229 mutex_unlock(&set
->tag_list_lock
);
2233 * It is the actual release handler for mq, but we do it from
2234 * request queue's release handler for avoiding use-after-free
2235 * and headache because q->mq_kobj shouldn't have been introduced,
2236 * but we can't group ctx/kctx kobj without it.
2238 void blk_mq_release(struct request_queue
*q
)
2240 struct blk_mq_hw_ctx
*hctx
;
2243 /* hctx kobj stays in hctx */
2244 queue_for_each_hw_ctx(q
, hctx
, i
) {
2247 kobject_put(&hctx
->kobj
);
2252 kfree(q
->queue_hw_ctx
);
2255 * release .mq_kobj and sw queue's kobject now because
2256 * both share lifetime with request queue.
2258 blk_mq_sysfs_deinit(q
);
2260 free_percpu(q
->queue_ctx
);
2263 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2265 struct request_queue
*uninit_q
, *q
;
2267 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2269 return ERR_PTR(-ENOMEM
);
2271 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2273 blk_cleanup_queue(uninit_q
);
2277 EXPORT_SYMBOL(blk_mq_init_queue
);
2279 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2280 struct request_queue
*q
)
2283 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2285 blk_mq_sysfs_unregister(q
);
2286 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2292 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2293 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2298 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2305 atomic_set(&hctxs
[i
]->nr_active
, 0);
2306 hctxs
[i
]->numa_node
= node
;
2307 hctxs
[i
]->queue_num
= i
;
2309 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2310 free_cpumask_var(hctxs
[i
]->cpumask
);
2315 blk_mq_hctx_kobj_init(hctxs
[i
]);
2317 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2318 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2322 blk_mq_free_map_and_requests(set
, j
);
2323 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2324 kobject_put(&hctx
->kobj
);
2329 q
->nr_hw_queues
= i
;
2330 blk_mq_sysfs_register(q
);
2333 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2334 struct request_queue
*q
)
2336 /* mark the queue as mq asap */
2337 q
->mq_ops
= set
->ops
;
2339 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2343 /* init q->mq_kobj and sw queues' kobjects */
2344 blk_mq_sysfs_init(q
);
2346 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2347 GFP_KERNEL
, set
->numa_node
);
2348 if (!q
->queue_hw_ctx
)
2351 q
->mq_map
= set
->mq_map
;
2353 blk_mq_realloc_hw_ctxs(set
, q
);
2354 if (!q
->nr_hw_queues
)
2357 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2358 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2360 q
->nr_queues
= nr_cpu_ids
;
2362 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2364 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2365 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2367 q
->sg_reserved_size
= INT_MAX
;
2369 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2370 INIT_LIST_HEAD(&q
->requeue_list
);
2371 spin_lock_init(&q
->requeue_lock
);
2373 if (q
->nr_hw_queues
> 1)
2374 blk_queue_make_request(q
, blk_mq_make_request
);
2376 blk_queue_make_request(q
, blk_sq_make_request
);
2379 * Do this after blk_queue_make_request() overrides it...
2381 q
->nr_requests
= set
->queue_depth
;
2384 * Default to classic polling
2388 if (set
->ops
->complete
)
2389 blk_queue_softirq_done(q
, set
->ops
->complete
);
2391 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2394 mutex_lock(&all_q_mutex
);
2396 list_add_tail(&q
->all_q_node
, &all_q_list
);
2397 blk_mq_add_queue_tag_set(set
, q
);
2398 blk_mq_map_swqueue(q
, cpu_online_mask
);
2400 mutex_unlock(&all_q_mutex
);
2403 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2406 ret
= blk_mq_sched_init(q
);
2408 return ERR_PTR(ret
);
2414 kfree(q
->queue_hw_ctx
);
2416 free_percpu(q
->queue_ctx
);
2419 return ERR_PTR(-ENOMEM
);
2421 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2423 void blk_mq_free_queue(struct request_queue
*q
)
2425 struct blk_mq_tag_set
*set
= q
->tag_set
;
2427 mutex_lock(&all_q_mutex
);
2428 list_del_init(&q
->all_q_node
);
2429 mutex_unlock(&all_q_mutex
);
2433 blk_mq_del_queue_tag_set(q
);
2435 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2438 /* Basically redo blk_mq_init_queue with queue frozen */
2439 static void blk_mq_queue_reinit(struct request_queue
*q
,
2440 const struct cpumask
*online_mask
)
2442 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2444 blk_mq_sysfs_unregister(q
);
2447 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2448 * we should change hctx numa_node according to new topology (this
2449 * involves free and re-allocate memory, worthy doing?)
2452 blk_mq_map_swqueue(q
, online_mask
);
2454 blk_mq_sysfs_register(q
);
2458 * New online cpumask which is going to be set in this hotplug event.
2459 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2460 * one-by-one and dynamically allocating this could result in a failure.
2462 static struct cpumask cpuhp_online_new
;
2464 static void blk_mq_queue_reinit_work(void)
2466 struct request_queue
*q
;
2468 mutex_lock(&all_q_mutex
);
2470 * We need to freeze and reinit all existing queues. Freezing
2471 * involves synchronous wait for an RCU grace period and doing it
2472 * one by one may take a long time. Start freezing all queues in
2473 * one swoop and then wait for the completions so that freezing can
2474 * take place in parallel.
2476 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2477 blk_mq_freeze_queue_start(q
);
2478 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2479 blk_mq_freeze_queue_wait(q
);
2481 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2482 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2484 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2485 blk_mq_unfreeze_queue(q
);
2487 mutex_unlock(&all_q_mutex
);
2490 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2492 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2493 blk_mq_queue_reinit_work();
2498 * Before hotadded cpu starts handling requests, new mappings must be
2499 * established. Otherwise, these requests in hw queue might never be
2502 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2503 * for CPU0, and ctx1 for CPU1).
2505 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2506 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2508 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2509 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2510 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2513 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2515 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2516 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2517 blk_mq_queue_reinit_work();
2521 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2525 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2526 if (!__blk_mq_alloc_rq_map(set
, i
))
2533 blk_mq_free_rq_map(set
->tags
[i
]);
2539 * Allocate the request maps associated with this tag_set. Note that this
2540 * may reduce the depth asked for, if memory is tight. set->queue_depth
2541 * will be updated to reflect the allocated depth.
2543 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2548 depth
= set
->queue_depth
;
2550 err
= __blk_mq_alloc_rq_maps(set
);
2554 set
->queue_depth
>>= 1;
2555 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2559 } while (set
->queue_depth
);
2561 if (!set
->queue_depth
|| err
) {
2562 pr_err("blk-mq: failed to allocate request map\n");
2566 if (depth
!= set
->queue_depth
)
2567 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2568 depth
, set
->queue_depth
);
2574 * Alloc a tag set to be associated with one or more request queues.
2575 * May fail with EINVAL for various error conditions. May adjust the
2576 * requested depth down, if if it too large. In that case, the set
2577 * value will be stored in set->queue_depth.
2579 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2583 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2585 if (!set
->nr_hw_queues
)
2587 if (!set
->queue_depth
)
2589 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2592 if (!set
->ops
->queue_rq
)
2595 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2596 pr_info("blk-mq: reduced tag depth to %u\n",
2598 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2602 * If a crashdump is active, then we are potentially in a very
2603 * memory constrained environment. Limit us to 1 queue and
2604 * 64 tags to prevent using too much memory.
2606 if (is_kdump_kernel()) {
2607 set
->nr_hw_queues
= 1;
2608 set
->queue_depth
= min(64U, set
->queue_depth
);
2611 * There is no use for more h/w queues than cpus.
2613 if (set
->nr_hw_queues
> nr_cpu_ids
)
2614 set
->nr_hw_queues
= nr_cpu_ids
;
2616 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2617 GFP_KERNEL
, set
->numa_node
);
2622 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2623 GFP_KERNEL
, set
->numa_node
);
2627 if (set
->ops
->map_queues
)
2628 ret
= set
->ops
->map_queues(set
);
2630 ret
= blk_mq_map_queues(set
);
2632 goto out_free_mq_map
;
2634 ret
= blk_mq_alloc_rq_maps(set
);
2636 goto out_free_mq_map
;
2638 mutex_init(&set
->tag_list_lock
);
2639 INIT_LIST_HEAD(&set
->tag_list
);
2651 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2653 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2657 for (i
= 0; i
< nr_cpu_ids
; i
++)
2658 blk_mq_free_map_and_requests(set
, i
);
2666 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2668 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2670 struct blk_mq_tag_set
*set
= q
->tag_set
;
2671 struct blk_mq_hw_ctx
*hctx
;
2677 blk_mq_freeze_queue(q
);
2678 blk_mq_quiesce_queue(q
);
2681 queue_for_each_hw_ctx(q
, hctx
, i
) {
2685 * If we're using an MQ scheduler, just update the scheduler
2686 * queue depth. This is similar to what the old code would do.
2688 if (!hctx
->sched_tags
) {
2689 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2690 min(nr
, set
->queue_depth
),
2693 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2701 q
->nr_requests
= nr
;
2703 blk_mq_unfreeze_queue(q
);
2704 blk_mq_start_stopped_hw_queues(q
, true);
2709 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2711 struct request_queue
*q
;
2713 if (nr_hw_queues
> nr_cpu_ids
)
2714 nr_hw_queues
= nr_cpu_ids
;
2715 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2718 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2719 blk_mq_freeze_queue(q
);
2721 set
->nr_hw_queues
= nr_hw_queues
;
2722 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2723 blk_mq_realloc_hw_ctxs(set
, q
);
2726 * Manually set the make_request_fn as blk_queue_make_request
2727 * resets a lot of the queue settings.
2729 if (q
->nr_hw_queues
> 1)
2730 q
->make_request_fn
= blk_mq_make_request
;
2732 q
->make_request_fn
= blk_sq_make_request
;
2734 blk_mq_queue_reinit(q
, cpu_online_mask
);
2737 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2738 blk_mq_unfreeze_queue(q
);
2740 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2742 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2743 struct blk_mq_hw_ctx
*hctx
,
2746 struct blk_rq_stat stat
[2];
2747 unsigned long ret
= 0;
2750 * If stats collection isn't on, don't sleep but turn it on for
2753 if (!blk_stat_enable(q
))
2757 * We don't have to do this once per IO, should optimize this
2758 * to just use the current window of stats until it changes
2760 memset(&stat
, 0, sizeof(stat
));
2761 blk_hctx_stat_get(hctx
, stat
);
2764 * As an optimistic guess, use half of the mean service time
2765 * for this type of request. We can (and should) make this smarter.
2766 * For instance, if the completion latencies are tight, we can
2767 * get closer than just half the mean. This is especially
2768 * important on devices where the completion latencies are longer
2771 if (req_op(rq
) == REQ_OP_READ
&& stat
[BLK_STAT_READ
].nr_samples
)
2772 ret
= (stat
[BLK_STAT_READ
].mean
+ 1) / 2;
2773 else if (req_op(rq
) == REQ_OP_WRITE
&& stat
[BLK_STAT_WRITE
].nr_samples
)
2774 ret
= (stat
[BLK_STAT_WRITE
].mean
+ 1) / 2;
2779 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2780 struct blk_mq_hw_ctx
*hctx
,
2783 struct hrtimer_sleeper hs
;
2784 enum hrtimer_mode mode
;
2788 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2794 * -1: don't ever hybrid sleep
2795 * 0: use half of prev avg
2796 * >0: use this specific value
2798 if (q
->poll_nsec
== -1)
2800 else if (q
->poll_nsec
> 0)
2801 nsecs
= q
->poll_nsec
;
2803 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2808 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2811 * This will be replaced with the stats tracking code, using
2812 * 'avg_completion_time / 2' as the pre-sleep target.
2816 mode
= HRTIMER_MODE_REL
;
2817 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2818 hrtimer_set_expires(&hs
.timer
, kt
);
2820 hrtimer_init_sleeper(&hs
, current
);
2822 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2824 set_current_state(TASK_UNINTERRUPTIBLE
);
2825 hrtimer_start_expires(&hs
.timer
, mode
);
2828 hrtimer_cancel(&hs
.timer
);
2829 mode
= HRTIMER_MODE_ABS
;
2830 } while (hs
.task
&& !signal_pending(current
));
2832 __set_current_state(TASK_RUNNING
);
2833 destroy_hrtimer_on_stack(&hs
.timer
);
2837 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2839 struct request_queue
*q
= hctx
->queue
;
2843 * If we sleep, have the caller restart the poll loop to reset
2844 * the state. Like for the other success return cases, the
2845 * caller is responsible for checking if the IO completed. If
2846 * the IO isn't complete, we'll get called again and will go
2847 * straight to the busy poll loop.
2849 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2852 hctx
->poll_considered
++;
2854 state
= current
->state
;
2855 while (!need_resched()) {
2858 hctx
->poll_invoked
++;
2860 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2862 hctx
->poll_success
++;
2863 set_current_state(TASK_RUNNING
);
2867 if (signal_pending_state(state
, current
))
2868 set_current_state(TASK_RUNNING
);
2870 if (current
->state
== TASK_RUNNING
)
2880 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2882 struct blk_mq_hw_ctx
*hctx
;
2883 struct blk_plug
*plug
;
2886 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2887 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2890 plug
= current
->plug
;
2892 blk_flush_plug_list(plug
, false);
2894 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2895 if (!blk_qc_t_is_internal(cookie
))
2896 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2898 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2900 return __blk_mq_poll(hctx
, rq
);
2902 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2904 void blk_mq_disable_hotplug(void)
2906 mutex_lock(&all_q_mutex
);
2909 void blk_mq_enable_hotplug(void)
2911 mutex_unlock(&all_q_mutex
);
2914 static int __init
blk_mq_init(void)
2916 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2917 blk_mq_hctx_notify_dead
);
2919 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2920 blk_mq_queue_reinit_prepare
,
2921 blk_mq_queue_reinit_dead
);
2924 subsys_initcall(blk_mq_init
);