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-debugfs.h"
35 #include "blk-mq-tag.h"
38 #include "blk-mq-sched.h"
40 static bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
);
41 static void blk_mq_poll_stats_start(struct request_queue
*q
);
42 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
44 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
46 int ddir
, bytes
, bucket
;
48 ddir
= rq_data_dir(rq
);
49 bytes
= blk_rq_bytes(rq
);
51 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
55 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
56 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
62 * Check if any of the ctx's have pending work in this hardware queue
64 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
66 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
67 !list_empty_careful(&hctx
->dispatch
) ||
68 blk_mq_sched_has_work(hctx
);
72 * Mark this ctx as having pending work in this hardware queue
74 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
75 struct blk_mq_ctx
*ctx
)
77 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
78 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
81 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
82 struct blk_mq_ctx
*ctx
)
84 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
88 struct hd_struct
*part
;
89 unsigned int *inflight
;
92 static void blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
93 struct request
*rq
, void *priv
,
96 struct mq_inflight
*mi
= priv
;
98 if (test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
) &&
99 !test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
)) {
101 * index[0] counts the specific partition that was asked
102 * for. index[1] counts the ones that are active on the
103 * whole device, so increment that if mi->part is indeed
104 * a partition, and not a whole device.
106 if (rq
->part
== mi
->part
)
108 if (mi
->part
->partno
)
113 void blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
,
114 unsigned int inflight
[2])
116 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
118 inflight
[0] = inflight
[1] = 0;
119 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
122 void blk_freeze_queue_start(struct request_queue
*q
)
126 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
127 if (freeze_depth
== 1) {
128 percpu_ref_kill(&q
->q_usage_counter
);
129 blk_mq_run_hw_queues(q
, false);
132 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
134 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
136 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
138 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
140 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
141 unsigned long timeout
)
143 return wait_event_timeout(q
->mq_freeze_wq
,
144 percpu_ref_is_zero(&q
->q_usage_counter
),
147 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
150 * Guarantee no request is in use, so we can change any data structure of
151 * the queue afterward.
153 void blk_freeze_queue(struct request_queue
*q
)
156 * In the !blk_mq case we are only calling this to kill the
157 * q_usage_counter, otherwise this increases the freeze depth
158 * and waits for it to return to zero. For this reason there is
159 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
160 * exported to drivers as the only user for unfreeze is blk_mq.
162 blk_freeze_queue_start(q
);
163 blk_mq_freeze_queue_wait(q
);
166 void blk_mq_freeze_queue(struct request_queue
*q
)
169 * ...just an alias to keep freeze and unfreeze actions balanced
170 * in the blk_mq_* namespace
174 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
176 void blk_mq_unfreeze_queue(struct request_queue
*q
)
180 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
181 WARN_ON_ONCE(freeze_depth
< 0);
183 percpu_ref_reinit(&q
->q_usage_counter
);
184 wake_up_all(&q
->mq_freeze_wq
);
187 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
190 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
191 * mpt3sas driver such that this function can be removed.
193 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
197 spin_lock_irqsave(q
->queue_lock
, flags
);
198 queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
199 spin_unlock_irqrestore(q
->queue_lock
, flags
);
201 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
204 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
207 * Note: this function does not prevent that the struct request end_io()
208 * callback function is invoked. Once this function is returned, we make
209 * sure no dispatch can happen until the queue is unquiesced via
210 * blk_mq_unquiesce_queue().
212 void blk_mq_quiesce_queue(struct request_queue
*q
)
214 struct blk_mq_hw_ctx
*hctx
;
218 blk_mq_quiesce_queue_nowait(q
);
220 queue_for_each_hw_ctx(q
, hctx
, i
) {
221 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
222 synchronize_srcu(hctx
->queue_rq_srcu
);
229 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
232 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
235 * This function recovers queue into the state before quiescing
236 * which is done by blk_mq_quiesce_queue.
238 void blk_mq_unquiesce_queue(struct request_queue
*q
)
242 spin_lock_irqsave(q
->queue_lock
, flags
);
243 queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
244 spin_unlock_irqrestore(q
->queue_lock
, flags
);
246 /* dispatch requests which are inserted during quiescing */
247 blk_mq_run_hw_queues(q
, true);
249 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
251 void blk_mq_wake_waiters(struct request_queue
*q
)
253 struct blk_mq_hw_ctx
*hctx
;
256 queue_for_each_hw_ctx(q
, hctx
, i
)
257 if (blk_mq_hw_queue_mapped(hctx
))
258 blk_mq_tag_wakeup_all(hctx
->tags
, true);
261 * If we are called because the queue has now been marked as
262 * dying, we need to ensure that processes currently waiting on
263 * the queue are notified as well.
265 wake_up_all(&q
->mq_freeze_wq
);
268 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
270 return blk_mq_has_free_tags(hctx
->tags
);
272 EXPORT_SYMBOL(blk_mq_can_queue
);
274 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
275 unsigned int tag
, unsigned int op
)
277 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
278 struct request
*rq
= tags
->static_rqs
[tag
];
282 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
284 rq
->internal_tag
= tag
;
286 if (blk_mq_tag_busy(data
->hctx
)) {
287 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
288 atomic_inc(&data
->hctx
->nr_active
);
291 rq
->internal_tag
= -1;
292 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
295 INIT_LIST_HEAD(&rq
->queuelist
);
296 /* csd/requeue_work/fifo_time is initialized before use */
298 rq
->mq_ctx
= data
->ctx
;
300 if (blk_queue_io_stat(data
->q
))
301 rq
->rq_flags
|= RQF_IO_STAT
;
302 /* do not touch atomic flags, it needs atomic ops against the timer */
304 INIT_HLIST_NODE(&rq
->hash
);
305 RB_CLEAR_NODE(&rq
->rb_node
);
308 rq
->start_time
= jiffies
;
309 #ifdef CONFIG_BLK_CGROUP
311 set_start_time_ns(rq
);
312 rq
->io_start_time_ns
= 0;
314 rq
->nr_phys_segments
= 0;
315 #if defined(CONFIG_BLK_DEV_INTEGRITY)
316 rq
->nr_integrity_segments
= 0;
319 /* tag was already set */
322 INIT_LIST_HEAD(&rq
->timeout_list
);
326 rq
->end_io_data
= NULL
;
329 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
333 static struct request
*blk_mq_get_request(struct request_queue
*q
,
334 struct bio
*bio
, unsigned int op
,
335 struct blk_mq_alloc_data
*data
)
337 struct elevator_queue
*e
= q
->elevator
;
340 bool put_ctx_on_error
= false;
342 blk_queue_enter_live(q
);
344 if (likely(!data
->ctx
)) {
345 data
->ctx
= blk_mq_get_ctx(q
);
346 put_ctx_on_error
= true;
348 if (likely(!data
->hctx
))
349 data
->hctx
= blk_mq_map_queue(q
, data
->ctx
->cpu
);
351 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
354 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
357 * Flush requests are special and go directly to the
360 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
361 e
->type
->ops
.mq
.limit_depth(op
, data
);
364 tag
= blk_mq_get_tag(data
);
365 if (tag
== BLK_MQ_TAG_FAIL
) {
366 if (put_ctx_on_error
) {
367 blk_mq_put_ctx(data
->ctx
);
374 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
375 if (!op_is_flush(op
)) {
377 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
378 if (e
->type
->icq_cache
&& rq_ioc(bio
))
379 blk_mq_sched_assign_ioc(rq
, bio
);
381 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
382 rq
->rq_flags
|= RQF_ELVPRIV
;
385 data
->hctx
->queued
++;
389 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
392 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
396 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
400 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
404 return ERR_PTR(-EWOULDBLOCK
);
406 blk_mq_put_ctx(alloc_data
.ctx
);
409 rq
->__sector
= (sector_t
) -1;
410 rq
->bio
= rq
->biotail
= NULL
;
413 EXPORT_SYMBOL(blk_mq_alloc_request
);
415 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
416 unsigned int op
, unsigned int flags
, unsigned int hctx_idx
)
418 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
424 * If the tag allocator sleeps we could get an allocation for a
425 * different hardware context. No need to complicate the low level
426 * allocator for this for the rare use case of a command tied to
429 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
430 return ERR_PTR(-EINVAL
);
432 if (hctx_idx
>= q
->nr_hw_queues
)
433 return ERR_PTR(-EIO
);
435 ret
= blk_queue_enter(q
, true);
440 * Check if the hardware context is actually mapped to anything.
441 * If not tell the caller that it should skip this queue.
443 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
444 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
446 return ERR_PTR(-EXDEV
);
448 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
449 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
451 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
455 return ERR_PTR(-EWOULDBLOCK
);
459 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
461 void blk_mq_free_request(struct request
*rq
)
463 struct request_queue
*q
= rq
->q
;
464 struct elevator_queue
*e
= q
->elevator
;
465 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
466 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
467 const int sched_tag
= rq
->internal_tag
;
469 if (rq
->rq_flags
& RQF_ELVPRIV
) {
470 if (e
&& e
->type
->ops
.mq
.finish_request
)
471 e
->type
->ops
.mq
.finish_request(rq
);
473 put_io_context(rq
->elv
.icq
->ioc
);
478 ctx
->rq_completed
[rq_is_sync(rq
)]++;
479 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
480 atomic_dec(&hctx
->nr_active
);
482 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
483 laptop_io_completion(q
->backing_dev_info
);
485 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
488 blk_put_rl(blk_rq_rl(rq
));
490 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
491 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
493 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
495 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
496 blk_mq_sched_restart(hctx
);
499 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
501 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
503 blk_account_io_done(rq
);
506 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
507 rq
->end_io(rq
, error
);
509 if (unlikely(blk_bidi_rq(rq
)))
510 blk_mq_free_request(rq
->next_rq
);
511 blk_mq_free_request(rq
);
514 EXPORT_SYMBOL(__blk_mq_end_request
);
516 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
518 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
520 __blk_mq_end_request(rq
, error
);
522 EXPORT_SYMBOL(blk_mq_end_request
);
524 static void __blk_mq_complete_request_remote(void *data
)
526 struct request
*rq
= data
;
528 rq
->q
->softirq_done_fn(rq
);
531 static void __blk_mq_complete_request(struct request
*rq
)
533 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
537 if (rq
->internal_tag
!= -1)
538 blk_mq_sched_completed_request(rq
);
539 if (rq
->rq_flags
& RQF_STATS
) {
540 blk_mq_poll_stats_start(rq
->q
);
544 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
545 rq
->q
->softirq_done_fn(rq
);
550 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
551 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
553 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
554 rq
->csd
.func
= __blk_mq_complete_request_remote
;
557 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
559 rq
->q
->softirq_done_fn(rq
);
565 * blk_mq_complete_request - end I/O on a request
566 * @rq: the request being processed
569 * Ends all I/O on a request. It does not handle partial completions.
570 * The actual completion happens out-of-order, through a IPI handler.
572 void blk_mq_complete_request(struct request
*rq
)
574 struct request_queue
*q
= rq
->q
;
576 if (unlikely(blk_should_fake_timeout(q
)))
578 if (!blk_mark_rq_complete(rq
))
579 __blk_mq_complete_request(rq
);
581 EXPORT_SYMBOL(blk_mq_complete_request
);
583 int blk_mq_request_started(struct request
*rq
)
585 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
587 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
589 void blk_mq_start_request(struct request
*rq
)
591 struct request_queue
*q
= rq
->q
;
593 blk_mq_sched_started_request(rq
);
595 trace_block_rq_issue(q
, rq
);
597 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
598 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
599 rq
->rq_flags
|= RQF_STATS
;
600 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
605 WARN_ON_ONCE(test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
));
608 * Mark us as started and clear complete. Complete might have been
609 * set if requeue raced with timeout, which then marked it as
610 * complete. So be sure to clear complete again when we start
611 * the request, otherwise we'll ignore the completion event.
613 * Ensure that ->deadline is visible before we set STARTED, such that
614 * blk_mq_check_expired() is guaranteed to observe our ->deadline when
615 * it observes STARTED.
618 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
619 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
)) {
621 * Coherence order guarantees these consecutive stores to a
622 * single variable propagate in the specified order. Thus the
623 * clear_bit() is ordered _after_ the set bit. See
624 * blk_mq_check_expired().
626 * (the bits must be part of the same byte for this to be
629 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
632 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
634 * Make sure space for the drain appears. We know we can do
635 * this because max_hw_segments has been adjusted to be one
636 * fewer than the device can handle.
638 rq
->nr_phys_segments
++;
641 EXPORT_SYMBOL(blk_mq_start_request
);
644 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
645 * flag isn't set yet, so there may be race with timeout handler,
646 * but given rq->deadline is just set in .queue_rq() under
647 * this situation, the race won't be possible in reality because
648 * rq->timeout should be set as big enough to cover the window
649 * between blk_mq_start_request() called from .queue_rq() and
650 * clearing REQ_ATOM_STARTED here.
652 static void __blk_mq_requeue_request(struct request
*rq
)
654 struct request_queue
*q
= rq
->q
;
656 trace_block_rq_requeue(q
, rq
);
657 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
658 blk_mq_sched_requeue_request(rq
);
660 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
661 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
662 rq
->nr_phys_segments
--;
666 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
668 __blk_mq_requeue_request(rq
);
670 BUG_ON(blk_queued_rq(rq
));
671 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
673 EXPORT_SYMBOL(blk_mq_requeue_request
);
675 static void blk_mq_requeue_work(struct work_struct
*work
)
677 struct request_queue
*q
=
678 container_of(work
, struct request_queue
, requeue_work
.work
);
680 struct request
*rq
, *next
;
682 spin_lock_irq(&q
->requeue_lock
);
683 list_splice_init(&q
->requeue_list
, &rq_list
);
684 spin_unlock_irq(&q
->requeue_lock
);
686 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
687 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
690 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
691 list_del_init(&rq
->queuelist
);
692 blk_mq_sched_insert_request(rq
, true, false, false, true);
695 while (!list_empty(&rq_list
)) {
696 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
697 list_del_init(&rq
->queuelist
);
698 blk_mq_sched_insert_request(rq
, false, false, false, true);
701 blk_mq_run_hw_queues(q
, false);
704 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
705 bool kick_requeue_list
)
707 struct request_queue
*q
= rq
->q
;
711 * We abuse this flag that is otherwise used by the I/O scheduler to
712 * request head insertation from the workqueue.
714 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
716 spin_lock_irqsave(&q
->requeue_lock
, flags
);
718 rq
->rq_flags
|= RQF_SOFTBARRIER
;
719 list_add(&rq
->queuelist
, &q
->requeue_list
);
721 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
723 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
725 if (kick_requeue_list
)
726 blk_mq_kick_requeue_list(q
);
728 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
730 void blk_mq_kick_requeue_list(struct request_queue
*q
)
732 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
734 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
736 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
739 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
740 msecs_to_jiffies(msecs
));
742 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
744 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
746 if (tag
< tags
->nr_tags
) {
747 prefetch(tags
->rqs
[tag
]);
748 return tags
->rqs
[tag
];
753 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
755 struct blk_mq_timeout_data
{
757 unsigned int next_set
;
760 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
762 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
763 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
766 * We know that complete is set at this point. If STARTED isn't set
767 * anymore, then the request isn't active and the "timeout" should
768 * just be ignored. This can happen due to the bitflag ordering.
769 * Timeout first checks if STARTED is set, and if it is, assumes
770 * the request is active. But if we race with completion, then
771 * both flags will get cleared. So check here again, and ignore
772 * a timeout event with a request that isn't active.
774 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
778 ret
= ops
->timeout(req
, reserved
);
782 __blk_mq_complete_request(req
);
784 case BLK_EH_RESET_TIMER
:
786 blk_clear_rq_complete(req
);
788 case BLK_EH_NOT_HANDLED
:
791 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
796 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
797 struct request
*rq
, void *priv
, bool reserved
)
799 struct blk_mq_timeout_data
*data
= priv
;
800 unsigned long deadline
;
802 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
806 * Ensures that if we see STARTED we must also see our
807 * up-to-date deadline, see blk_mq_start_request().
811 deadline
= READ_ONCE(rq
->deadline
);
814 * The rq being checked may have been freed and reallocated
815 * out already here, we avoid this race by checking rq->deadline
816 * and REQ_ATOM_COMPLETE flag together:
818 * - if rq->deadline is observed as new value because of
819 * reusing, the rq won't be timed out because of timing.
820 * - if rq->deadline is observed as previous value,
821 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
822 * because we put a barrier between setting rq->deadline
823 * and clearing the flag in blk_mq_start_request(), so
824 * this rq won't be timed out too.
826 if (time_after_eq(jiffies
, deadline
)) {
827 if (!blk_mark_rq_complete(rq
)) {
829 * Again coherence order ensures that consecutive reads
830 * from the same variable must be in that order. This
831 * ensures that if we see COMPLETE clear, we must then
832 * see STARTED set and we'll ignore this timeout.
834 * (There's also the MB implied by the test_and_clear())
836 blk_mq_rq_timed_out(rq
, reserved
);
838 } else if (!data
->next_set
|| time_after(data
->next
, deadline
)) {
839 data
->next
= deadline
;
844 static void blk_mq_timeout_work(struct work_struct
*work
)
846 struct request_queue
*q
=
847 container_of(work
, struct request_queue
, timeout_work
);
848 struct blk_mq_timeout_data data
= {
854 /* A deadlock might occur if a request is stuck requiring a
855 * timeout at the same time a queue freeze is waiting
856 * completion, since the timeout code would not be able to
857 * acquire the queue reference here.
859 * That's why we don't use blk_queue_enter here; instead, we use
860 * percpu_ref_tryget directly, because we need to be able to
861 * obtain a reference even in the short window between the queue
862 * starting to freeze, by dropping the first reference in
863 * blk_freeze_queue_start, and the moment the last request is
864 * consumed, marked by the instant q_usage_counter reaches
867 if (!percpu_ref_tryget(&q
->q_usage_counter
))
870 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
873 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
874 mod_timer(&q
->timeout
, data
.next
);
876 struct blk_mq_hw_ctx
*hctx
;
878 queue_for_each_hw_ctx(q
, hctx
, i
) {
879 /* the hctx may be unmapped, so check it here */
880 if (blk_mq_hw_queue_mapped(hctx
))
881 blk_mq_tag_idle(hctx
);
887 struct flush_busy_ctx_data
{
888 struct blk_mq_hw_ctx
*hctx
;
889 struct list_head
*list
;
892 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
894 struct flush_busy_ctx_data
*flush_data
= data
;
895 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
896 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
898 sbitmap_clear_bit(sb
, bitnr
);
899 spin_lock(&ctx
->lock
);
900 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
901 spin_unlock(&ctx
->lock
);
906 * Process software queues that have been marked busy, splicing them
907 * to the for-dispatch
909 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
911 struct flush_busy_ctx_data data
= {
916 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
918 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
920 struct dispatch_rq_data
{
921 struct blk_mq_hw_ctx
*hctx
;
925 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
928 struct dispatch_rq_data
*dispatch_data
= data
;
929 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
930 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
932 spin_lock(&ctx
->lock
);
933 if (unlikely(!list_empty(&ctx
->rq_list
))) {
934 dispatch_data
->rq
= list_entry_rq(ctx
->rq_list
.next
);
935 list_del_init(&dispatch_data
->rq
->queuelist
);
936 if (list_empty(&ctx
->rq_list
))
937 sbitmap_clear_bit(sb
, bitnr
);
939 spin_unlock(&ctx
->lock
);
941 return !dispatch_data
->rq
;
944 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
945 struct blk_mq_ctx
*start
)
947 unsigned off
= start
? start
->index_hw
: 0;
948 struct dispatch_rq_data data
= {
953 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
954 dispatch_rq_from_ctx
, &data
);
959 static inline unsigned int queued_to_index(unsigned int queued
)
964 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
967 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
970 struct blk_mq_alloc_data data
= {
972 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
973 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
976 might_sleep_if(wait
);
981 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
982 data
.flags
|= BLK_MQ_REQ_RESERVED
;
984 rq
->tag
= blk_mq_get_tag(&data
);
986 if (blk_mq_tag_busy(data
.hctx
)) {
987 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
988 atomic_inc(&data
.hctx
->nr_active
);
990 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
996 return rq
->tag
!= -1;
999 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
1002 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
1005 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
1006 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
1007 atomic_dec(&hctx
->nr_active
);
1011 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
1014 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
1017 __blk_mq_put_driver_tag(hctx
, rq
);
1020 static void blk_mq_put_driver_tag(struct request
*rq
)
1022 struct blk_mq_hw_ctx
*hctx
;
1024 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
1027 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
1028 __blk_mq_put_driver_tag(hctx
, rq
);
1032 * If we fail getting a driver tag because all the driver tags are already
1033 * assigned and on the dispatch list, BUT the first entry does not have a
1034 * tag, then we could deadlock. For that case, move entries with assigned
1035 * driver tags to the front, leaving the set of tagged requests in the
1036 * same order, and the untagged set in the same order.
1038 static bool reorder_tags_to_front(struct list_head
*list
)
1040 struct request
*rq
, *tmp
, *first
= NULL
;
1042 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
1045 if (rq
->tag
!= -1) {
1046 list_move(&rq
->queuelist
, list
);
1052 return first
!= NULL
;
1055 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
, int flags
,
1058 struct blk_mq_hw_ctx
*hctx
;
1060 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1062 list_del(&wait
->entry
);
1063 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
1064 blk_mq_run_hw_queue(hctx
, true);
1068 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
1070 struct sbq_wait_state
*ws
;
1073 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
1074 * The thread which wins the race to grab this bit adds the hardware
1075 * queue to the wait queue.
1077 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
1078 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1081 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
1082 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
1085 * As soon as this returns, it's no longer safe to fiddle with
1086 * hctx->dispatch_wait, since a completion can wake up the wait queue
1087 * and unlock the bit.
1089 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
1093 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1096 struct blk_mq_hw_ctx
*hctx
;
1097 struct request
*rq
, *nxt
;
1100 if (list_empty(list
))
1103 WARN_ON(!list_is_singular(list
) && got_budget
);
1106 * Now process all the entries, sending them to the driver.
1108 errors
= queued
= 0;
1110 struct blk_mq_queue_data bd
;
1113 rq
= list_first_entry(list
, struct request
, queuelist
);
1114 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
1115 if (!queued
&& reorder_tags_to_front(list
))
1119 * The initial allocation attempt failed, so we need to
1120 * rerun the hardware queue when a tag is freed.
1122 if (!blk_mq_dispatch_wait_add(hctx
)) {
1124 blk_mq_put_dispatch_budget(hctx
);
1129 * It's possible that a tag was freed in the window
1130 * between the allocation failure and adding the
1131 * hardware queue to the wait queue.
1133 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
1135 blk_mq_put_dispatch_budget(hctx
);
1140 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1143 list_del_init(&rq
->queuelist
);
1148 * Flag last if we have no more requests, or if we have more
1149 * but can't assign a driver tag to it.
1151 if (list_empty(list
))
1154 nxt
= list_first_entry(list
, struct request
, queuelist
);
1155 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1158 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1159 if (ret
== BLK_STS_RESOURCE
) {
1161 * If an I/O scheduler has been configured and we got a
1162 * driver tag for the next request already, free it again.
1164 if (!list_empty(list
)) {
1165 nxt
= list_first_entry(list
, struct request
, queuelist
);
1166 blk_mq_put_driver_tag(nxt
);
1168 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1169 list_add(&rq
->queuelist
, list
);
1170 __blk_mq_requeue_request(rq
);
1174 if (unlikely(ret
!= BLK_STS_OK
)) {
1176 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1181 } while (!list_empty(list
));
1183 hctx
->dispatched
[queued_to_index(queued
)]++;
1186 * Any items that need requeuing? Stuff them into hctx->dispatch,
1187 * that is where we will continue on next queue run.
1189 if (!list_empty(list
)) {
1190 spin_lock(&hctx
->lock
);
1191 list_splice_init(list
, &hctx
->dispatch
);
1192 spin_unlock(&hctx
->lock
);
1195 * If SCHED_RESTART was set by the caller of this function and
1196 * it is no longer set that means that it was cleared by another
1197 * thread and hence that a queue rerun is needed.
1199 * If TAG_WAITING is set that means that an I/O scheduler has
1200 * been configured and another thread is waiting for a driver
1201 * tag. To guarantee fairness, do not rerun this hardware queue
1202 * but let the other thread grab the driver tag.
1204 * If no I/O scheduler has been configured it is possible that
1205 * the hardware queue got stopped and restarted before requests
1206 * were pushed back onto the dispatch list. Rerun the queue to
1207 * avoid starvation. Notes:
1208 * - blk_mq_run_hw_queue() checks whether or not a queue has
1209 * been stopped before rerunning a queue.
1210 * - Some but not all block drivers stop a queue before
1211 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1214 if (!blk_mq_sched_needs_restart(hctx
) &&
1215 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1216 blk_mq_run_hw_queue(hctx
, true);
1219 return (queued
+ errors
) != 0;
1222 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1227 * We should be running this queue from one of the CPUs that
1230 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1231 cpu_online(hctx
->next_cpu
));
1234 * We can't run the queue inline with ints disabled. Ensure that
1235 * we catch bad users of this early.
1237 WARN_ON_ONCE(in_interrupt());
1239 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1241 blk_mq_sched_dispatch_requests(hctx
);
1246 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1247 blk_mq_sched_dispatch_requests(hctx
);
1248 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1253 * It'd be great if the workqueue API had a way to pass
1254 * in a mask and had some smarts for more clever placement.
1255 * For now we just round-robin here, switching for every
1256 * BLK_MQ_CPU_WORK_BATCH queued items.
1258 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1260 if (hctx
->queue
->nr_hw_queues
== 1)
1261 return WORK_CPU_UNBOUND
;
1263 if (--hctx
->next_cpu_batch
<= 0) {
1266 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1267 if (next_cpu
>= nr_cpu_ids
)
1268 next_cpu
= cpumask_first(hctx
->cpumask
);
1270 hctx
->next_cpu
= next_cpu
;
1271 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1274 return hctx
->next_cpu
;
1277 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1278 unsigned long msecs
)
1280 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1283 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1286 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1287 int cpu
= get_cpu();
1288 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1289 __blk_mq_run_hw_queue(hctx
);
1297 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1299 msecs_to_jiffies(msecs
));
1302 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1304 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1306 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1308 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1310 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1312 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1314 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1316 struct blk_mq_hw_ctx
*hctx
;
1319 queue_for_each_hw_ctx(q
, hctx
, i
) {
1320 if (!blk_mq_hctx_has_pending(hctx
) ||
1321 blk_mq_hctx_stopped(hctx
))
1324 blk_mq_run_hw_queue(hctx
, async
);
1327 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1330 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1331 * @q: request queue.
1333 * The caller is responsible for serializing this function against
1334 * blk_mq_{start,stop}_hw_queue().
1336 bool blk_mq_queue_stopped(struct request_queue
*q
)
1338 struct blk_mq_hw_ctx
*hctx
;
1341 queue_for_each_hw_ctx(q
, hctx
, i
)
1342 if (blk_mq_hctx_stopped(hctx
))
1347 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1350 * This function is often used for pausing .queue_rq() by driver when
1351 * there isn't enough resource or some conditions aren't satisfied, and
1352 * BLK_STS_RESOURCE is usually returned.
1354 * We do not guarantee that dispatch can be drained or blocked
1355 * after blk_mq_stop_hw_queue() returns. Please use
1356 * blk_mq_quiesce_queue() for that requirement.
1358 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1360 cancel_delayed_work(&hctx
->run_work
);
1362 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1364 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1367 * This function is often used for pausing .queue_rq() by driver when
1368 * there isn't enough resource or some conditions aren't satisfied, and
1369 * BLK_STS_RESOURCE is usually returned.
1371 * We do not guarantee that dispatch can be drained or blocked
1372 * after blk_mq_stop_hw_queues() returns. Please use
1373 * blk_mq_quiesce_queue() for that requirement.
1375 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1377 struct blk_mq_hw_ctx
*hctx
;
1380 queue_for_each_hw_ctx(q
, hctx
, i
)
1381 blk_mq_stop_hw_queue(hctx
);
1383 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1385 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1387 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1389 blk_mq_run_hw_queue(hctx
, false);
1391 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1393 void blk_mq_start_hw_queues(struct request_queue
*q
)
1395 struct blk_mq_hw_ctx
*hctx
;
1398 queue_for_each_hw_ctx(q
, hctx
, i
)
1399 blk_mq_start_hw_queue(hctx
);
1401 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1403 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1405 if (!blk_mq_hctx_stopped(hctx
))
1408 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1409 blk_mq_run_hw_queue(hctx
, async
);
1411 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1413 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1415 struct blk_mq_hw_ctx
*hctx
;
1418 queue_for_each_hw_ctx(q
, hctx
, i
)
1419 blk_mq_start_stopped_hw_queue(hctx
, async
);
1421 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1423 static void blk_mq_run_work_fn(struct work_struct
*work
)
1425 struct blk_mq_hw_ctx
*hctx
;
1427 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1430 * If we are stopped, don't run the queue. The exception is if
1431 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1432 * the STOPPED bit and run it.
1434 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1435 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1438 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1439 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1442 __blk_mq_run_hw_queue(hctx
);
1446 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1448 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1452 * Stop the hw queue, then modify currently delayed work.
1453 * This should prevent us from running the queue prematurely.
1454 * Mark the queue as auto-clearing STOPPED when it runs.
1456 blk_mq_stop_hw_queue(hctx
);
1457 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1458 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1460 msecs_to_jiffies(msecs
));
1462 EXPORT_SYMBOL(blk_mq_delay_queue
);
1464 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1468 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1470 lockdep_assert_held(&ctx
->lock
);
1472 trace_block_rq_insert(hctx
->queue
, rq
);
1475 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1477 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1480 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1483 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1485 lockdep_assert_held(&ctx
->lock
);
1487 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1488 blk_mq_hctx_mark_pending(hctx
, ctx
);
1492 * Should only be used carefully, when the caller knows we want to
1493 * bypass a potential IO scheduler on the target device.
1495 void blk_mq_request_bypass_insert(struct request
*rq
)
1497 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1498 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(rq
->q
, ctx
->cpu
);
1500 spin_lock(&hctx
->lock
);
1501 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1502 spin_unlock(&hctx
->lock
);
1504 blk_mq_run_hw_queue(hctx
, false);
1507 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1508 struct list_head
*list
)
1512 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1515 spin_lock(&ctx
->lock
);
1516 while (!list_empty(list
)) {
1519 rq
= list_first_entry(list
, struct request
, queuelist
);
1520 BUG_ON(rq
->mq_ctx
!= ctx
);
1521 list_del_init(&rq
->queuelist
);
1522 __blk_mq_insert_req_list(hctx
, rq
, false);
1524 blk_mq_hctx_mark_pending(hctx
, ctx
);
1525 spin_unlock(&ctx
->lock
);
1528 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1530 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1531 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1533 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1534 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1535 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1538 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1540 struct blk_mq_ctx
*this_ctx
;
1541 struct request_queue
*this_q
;
1544 LIST_HEAD(ctx_list
);
1547 list_splice_init(&plug
->mq_list
, &list
);
1549 list_sort(NULL
, &list
, plug_ctx_cmp
);
1555 while (!list_empty(&list
)) {
1556 rq
= list_entry_rq(list
.next
);
1557 list_del_init(&rq
->queuelist
);
1559 if (rq
->mq_ctx
!= this_ctx
) {
1561 trace_block_unplug(this_q
, depth
, from_schedule
);
1562 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1567 this_ctx
= rq
->mq_ctx
;
1573 list_add_tail(&rq
->queuelist
, &ctx_list
);
1577 * If 'this_ctx' is set, we know we have entries to complete
1578 * on 'ctx_list'. Do those.
1581 trace_block_unplug(this_q
, depth
, from_schedule
);
1582 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1587 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1589 blk_init_request_from_bio(rq
, bio
);
1591 blk_rq_set_rl(rq
, blk_get_rl(rq
->q
, bio
));
1593 blk_account_io_start(rq
, true);
1596 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1597 struct blk_mq_ctx
*ctx
,
1600 spin_lock(&ctx
->lock
);
1601 __blk_mq_insert_request(hctx
, rq
, false);
1602 spin_unlock(&ctx
->lock
);
1605 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1608 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1610 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1613 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1615 blk_qc_t
*cookie
, bool may_sleep
)
1617 struct request_queue
*q
= rq
->q
;
1618 struct blk_mq_queue_data bd
= {
1622 blk_qc_t new_cookie
;
1624 bool run_queue
= true;
1626 /* RCU or SRCU read lock is needed before checking quiesced flag */
1627 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1635 if (!blk_mq_get_driver_tag(rq
, NULL
, false))
1638 if (!blk_mq_get_dispatch_budget(hctx
)) {
1639 blk_mq_put_driver_tag(rq
);
1643 new_cookie
= request_to_qc_t(hctx
, rq
);
1646 * For OK queue, we are done. For error, kill it. Any other
1647 * error (busy), just add it to our list as we previously
1650 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1653 *cookie
= new_cookie
;
1655 case BLK_STS_RESOURCE
:
1656 __blk_mq_requeue_request(rq
);
1659 *cookie
= BLK_QC_T_NONE
;
1660 blk_mq_end_request(rq
, ret
);
1665 blk_mq_sched_insert_request(rq
, false, run_queue
, false, may_sleep
);
1668 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1669 struct request
*rq
, blk_qc_t
*cookie
)
1671 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1673 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1676 unsigned int srcu_idx
;
1680 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1681 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, true);
1682 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1686 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1688 const int is_sync
= op_is_sync(bio
->bi_opf
);
1689 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1690 struct blk_mq_alloc_data data
= { .flags
= 0 };
1692 unsigned int request_count
= 0;
1693 struct blk_plug
*plug
;
1694 struct request
*same_queue_rq
= NULL
;
1696 unsigned int wb_acct
;
1698 blk_queue_bounce(q
, &bio
);
1700 blk_queue_split(q
, &bio
);
1702 if (!bio_integrity_prep(bio
))
1703 return BLK_QC_T_NONE
;
1705 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1706 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1707 return BLK_QC_T_NONE
;
1709 if (blk_mq_sched_bio_merge(q
, bio
))
1710 return BLK_QC_T_NONE
;
1712 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1714 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1716 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1717 if (unlikely(!rq
)) {
1718 __wbt_done(q
->rq_wb
, wb_acct
);
1719 if (bio
->bi_opf
& REQ_NOWAIT
)
1720 bio_wouldblock_error(bio
);
1721 return BLK_QC_T_NONE
;
1724 wbt_track(&rq
->issue_stat
, wb_acct
);
1726 cookie
= request_to_qc_t(data
.hctx
, rq
);
1728 plug
= current
->plug
;
1729 if (unlikely(is_flush_fua
)) {
1730 blk_mq_put_ctx(data
.ctx
);
1731 blk_mq_bio_to_request(rq
, bio
);
1733 blk_mq_sched_insert_request(rq
, false, true, true,
1736 blk_insert_flush(rq
);
1737 blk_mq_run_hw_queue(data
.hctx
, true);
1739 } else if (plug
&& q
->nr_hw_queues
== 1) {
1740 struct request
*last
= NULL
;
1742 blk_mq_put_ctx(data
.ctx
);
1743 blk_mq_bio_to_request(rq
, bio
);
1746 * @request_count may become stale because of schedule
1747 * out, so check the list again.
1749 if (list_empty(&plug
->mq_list
))
1751 else if (blk_queue_nomerges(q
))
1752 request_count
= blk_plug_queued_count(q
);
1755 trace_block_plug(q
);
1757 last
= list_entry_rq(plug
->mq_list
.prev
);
1759 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1760 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1761 blk_flush_plug_list(plug
, false);
1762 trace_block_plug(q
);
1765 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1766 } else if (plug
&& !blk_queue_nomerges(q
)) {
1767 blk_mq_bio_to_request(rq
, bio
);
1770 * We do limited plugging. If the bio can be merged, do that.
1771 * Otherwise the existing request in the plug list will be
1772 * issued. So the plug list will have one request at most
1773 * The plug list might get flushed before this. If that happens,
1774 * the plug list is empty, and same_queue_rq is invalid.
1776 if (list_empty(&plug
->mq_list
))
1777 same_queue_rq
= NULL
;
1779 list_del_init(&same_queue_rq
->queuelist
);
1780 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1782 blk_mq_put_ctx(data
.ctx
);
1784 if (same_queue_rq
) {
1785 data
.hctx
= blk_mq_map_queue(q
,
1786 same_queue_rq
->mq_ctx
->cpu
);
1787 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1790 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1791 blk_mq_put_ctx(data
.ctx
);
1792 blk_mq_bio_to_request(rq
, bio
);
1793 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1794 } else if (q
->elevator
) {
1795 blk_mq_put_ctx(data
.ctx
);
1796 blk_mq_bio_to_request(rq
, bio
);
1797 blk_mq_sched_insert_request(rq
, false, true, true, true);
1799 blk_mq_put_ctx(data
.ctx
);
1800 blk_mq_bio_to_request(rq
, bio
);
1801 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1802 blk_mq_run_hw_queue(data
.hctx
, true);
1808 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1809 unsigned int hctx_idx
)
1813 if (tags
->rqs
&& set
->ops
->exit_request
) {
1816 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1817 struct request
*rq
= tags
->static_rqs
[i
];
1821 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1822 tags
->static_rqs
[i
] = NULL
;
1826 while (!list_empty(&tags
->page_list
)) {
1827 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1828 list_del_init(&page
->lru
);
1830 * Remove kmemleak object previously allocated in
1831 * blk_mq_init_rq_map().
1833 kmemleak_free(page_address(page
));
1834 __free_pages(page
, page
->private);
1838 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1842 kfree(tags
->static_rqs
);
1843 tags
->static_rqs
= NULL
;
1845 blk_mq_free_tags(tags
);
1848 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1849 unsigned int hctx_idx
,
1850 unsigned int nr_tags
,
1851 unsigned int reserved_tags
)
1853 struct blk_mq_tags
*tags
;
1856 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1857 if (node
== NUMA_NO_NODE
)
1858 node
= set
->numa_node
;
1860 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1861 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1865 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1866 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1869 blk_mq_free_tags(tags
);
1873 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1874 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1876 if (!tags
->static_rqs
) {
1878 blk_mq_free_tags(tags
);
1885 static size_t order_to_size(unsigned int order
)
1887 return (size_t)PAGE_SIZE
<< order
;
1890 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1891 unsigned int hctx_idx
, unsigned int depth
)
1893 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1894 size_t rq_size
, left
;
1897 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1898 if (node
== NUMA_NO_NODE
)
1899 node
= set
->numa_node
;
1901 INIT_LIST_HEAD(&tags
->page_list
);
1904 * rq_size is the size of the request plus driver payload, rounded
1905 * to the cacheline size
1907 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1909 left
= rq_size
* depth
;
1911 for (i
= 0; i
< depth
; ) {
1912 int this_order
= max_order
;
1917 while (this_order
&& left
< order_to_size(this_order
- 1))
1921 page
= alloc_pages_node(node
,
1922 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1928 if (order_to_size(this_order
) < rq_size
)
1935 page
->private = this_order
;
1936 list_add_tail(&page
->lru
, &tags
->page_list
);
1938 p
= page_address(page
);
1940 * Allow kmemleak to scan these pages as they contain pointers
1941 * to additional allocations like via ops->init_request().
1943 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1944 entries_per_page
= order_to_size(this_order
) / rq_size
;
1945 to_do
= min(entries_per_page
, depth
- i
);
1946 left
-= to_do
* rq_size
;
1947 for (j
= 0; j
< to_do
; j
++) {
1948 struct request
*rq
= p
;
1950 tags
->static_rqs
[i
] = rq
;
1951 if (set
->ops
->init_request
) {
1952 if (set
->ops
->init_request(set
, rq
, hctx_idx
,
1954 tags
->static_rqs
[i
] = NULL
;
1966 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1971 * 'cpu' is going away. splice any existing rq_list entries from this
1972 * software queue to the hw queue dispatch list, and ensure that it
1975 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1977 struct blk_mq_hw_ctx
*hctx
;
1978 struct blk_mq_ctx
*ctx
;
1981 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1982 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1984 spin_lock(&ctx
->lock
);
1985 if (!list_empty(&ctx
->rq_list
)) {
1986 list_splice_init(&ctx
->rq_list
, &tmp
);
1987 blk_mq_hctx_clear_pending(hctx
, ctx
);
1989 spin_unlock(&ctx
->lock
);
1991 if (list_empty(&tmp
))
1994 spin_lock(&hctx
->lock
);
1995 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1996 spin_unlock(&hctx
->lock
);
1998 blk_mq_run_hw_queue(hctx
, true);
2002 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2004 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2008 /* hctx->ctxs will be freed in queue's release handler */
2009 static void blk_mq_exit_hctx(struct request_queue
*q
,
2010 struct blk_mq_tag_set
*set
,
2011 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2013 blk_mq_debugfs_unregister_hctx(hctx
);
2015 blk_mq_tag_idle(hctx
);
2017 if (set
->ops
->exit_request
)
2018 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2020 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2022 if (set
->ops
->exit_hctx
)
2023 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2025 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2026 cleanup_srcu_struct(hctx
->queue_rq_srcu
);
2028 blk_mq_remove_cpuhp(hctx
);
2029 blk_free_flush_queue(hctx
->fq
);
2030 sbitmap_free(&hctx
->ctx_map
);
2033 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2034 struct blk_mq_tag_set
*set
, int nr_queue
)
2036 struct blk_mq_hw_ctx
*hctx
;
2039 queue_for_each_hw_ctx(q
, hctx
, i
) {
2042 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2046 static int blk_mq_init_hctx(struct request_queue
*q
,
2047 struct blk_mq_tag_set
*set
,
2048 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2052 node
= hctx
->numa_node
;
2053 if (node
== NUMA_NO_NODE
)
2054 node
= hctx
->numa_node
= set
->numa_node
;
2056 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2057 spin_lock_init(&hctx
->lock
);
2058 INIT_LIST_HEAD(&hctx
->dispatch
);
2060 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2062 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2064 hctx
->tags
= set
->tags
[hctx_idx
];
2067 * Allocate space for all possible cpus to avoid allocation at
2070 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
2073 goto unregister_cpu_notifier
;
2075 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
2081 if (set
->ops
->init_hctx
&&
2082 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2085 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
2088 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
2090 goto sched_exit_hctx
;
2092 if (set
->ops
->init_request
&&
2093 set
->ops
->init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2097 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2098 init_srcu_struct(hctx
->queue_rq_srcu
);
2100 blk_mq_debugfs_register_hctx(q
, hctx
);
2107 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2109 if (set
->ops
->exit_hctx
)
2110 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2112 sbitmap_free(&hctx
->ctx_map
);
2115 unregister_cpu_notifier
:
2116 blk_mq_remove_cpuhp(hctx
);
2120 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2121 unsigned int nr_hw_queues
)
2125 for_each_possible_cpu(i
) {
2126 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2127 struct blk_mq_hw_ctx
*hctx
;
2130 spin_lock_init(&__ctx
->lock
);
2131 INIT_LIST_HEAD(&__ctx
->rq_list
);
2134 /* If the cpu isn't present, the cpu is mapped to first hctx */
2135 if (!cpu_present(i
))
2138 hctx
= blk_mq_map_queue(q
, i
);
2141 * Set local node, IFF we have more than one hw queue. If
2142 * not, we remain on the home node of the device
2144 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2145 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2149 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2153 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2154 set
->queue_depth
, set
->reserved_tags
);
2155 if (!set
->tags
[hctx_idx
])
2158 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2163 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2164 set
->tags
[hctx_idx
] = NULL
;
2168 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2169 unsigned int hctx_idx
)
2171 if (set
->tags
[hctx_idx
]) {
2172 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2173 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2174 set
->tags
[hctx_idx
] = NULL
;
2178 static void blk_mq_map_swqueue(struct request_queue
*q
)
2180 unsigned int i
, hctx_idx
;
2181 struct blk_mq_hw_ctx
*hctx
;
2182 struct blk_mq_ctx
*ctx
;
2183 struct blk_mq_tag_set
*set
= q
->tag_set
;
2186 * Avoid others reading imcomplete hctx->cpumask through sysfs
2188 mutex_lock(&q
->sysfs_lock
);
2190 queue_for_each_hw_ctx(q
, hctx
, i
) {
2191 cpumask_clear(hctx
->cpumask
);
2196 * Map software to hardware queues.
2198 * If the cpu isn't present, the cpu is mapped to first hctx.
2200 for_each_present_cpu(i
) {
2201 hctx_idx
= q
->mq_map
[i
];
2202 /* unmapped hw queue can be remapped after CPU topo changed */
2203 if (!set
->tags
[hctx_idx
] &&
2204 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2206 * If tags initialization fail for some hctx,
2207 * that hctx won't be brought online. In this
2208 * case, remap the current ctx to hctx[0] which
2209 * is guaranteed to always have tags allocated
2214 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2215 hctx
= blk_mq_map_queue(q
, i
);
2217 cpumask_set_cpu(i
, hctx
->cpumask
);
2218 ctx
->index_hw
= hctx
->nr_ctx
;
2219 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2222 mutex_unlock(&q
->sysfs_lock
);
2224 queue_for_each_hw_ctx(q
, hctx
, i
) {
2226 * If no software queues are mapped to this hardware queue,
2227 * disable it and free the request entries.
2229 if (!hctx
->nr_ctx
) {
2230 /* Never unmap queue 0. We need it as a
2231 * fallback in case of a new remap fails
2234 if (i
&& set
->tags
[i
])
2235 blk_mq_free_map_and_requests(set
, i
);
2241 hctx
->tags
= set
->tags
[i
];
2242 WARN_ON(!hctx
->tags
);
2245 * Set the map size to the number of mapped software queues.
2246 * This is more accurate and more efficient than looping
2247 * over all possibly mapped software queues.
2249 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2252 * Initialize batch roundrobin counts
2254 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2255 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2260 * Caller needs to ensure that we're either frozen/quiesced, or that
2261 * the queue isn't live yet.
2263 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2265 struct blk_mq_hw_ctx
*hctx
;
2268 queue_for_each_hw_ctx(q
, hctx
, i
) {
2270 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2271 atomic_inc(&q
->shared_hctx_restart
);
2272 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2274 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2275 atomic_dec(&q
->shared_hctx_restart
);
2276 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2281 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2284 struct request_queue
*q
;
2286 lockdep_assert_held(&set
->tag_list_lock
);
2288 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2289 blk_mq_freeze_queue(q
);
2290 queue_set_hctx_shared(q
, shared
);
2291 blk_mq_unfreeze_queue(q
);
2295 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2297 struct blk_mq_tag_set
*set
= q
->tag_set
;
2299 mutex_lock(&set
->tag_list_lock
);
2300 list_del_rcu(&q
->tag_set_list
);
2301 INIT_LIST_HEAD(&q
->tag_set_list
);
2302 if (list_is_singular(&set
->tag_list
)) {
2303 /* just transitioned to unshared */
2304 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2305 /* update existing queue */
2306 blk_mq_update_tag_set_depth(set
, false);
2308 mutex_unlock(&set
->tag_list_lock
);
2313 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2314 struct request_queue
*q
)
2318 mutex_lock(&set
->tag_list_lock
);
2320 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2321 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2322 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2323 /* update existing queue */
2324 blk_mq_update_tag_set_depth(set
, true);
2326 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2327 queue_set_hctx_shared(q
, true);
2328 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2330 mutex_unlock(&set
->tag_list_lock
);
2334 * It is the actual release handler for mq, but we do it from
2335 * request queue's release handler for avoiding use-after-free
2336 * and headache because q->mq_kobj shouldn't have been introduced,
2337 * but we can't group ctx/kctx kobj without it.
2339 void blk_mq_release(struct request_queue
*q
)
2341 struct blk_mq_hw_ctx
*hctx
;
2344 /* hctx kobj stays in hctx */
2345 queue_for_each_hw_ctx(q
, hctx
, i
) {
2348 kobject_put(&hctx
->kobj
);
2353 kfree(q
->queue_hw_ctx
);
2356 * release .mq_kobj and sw queue's kobject now because
2357 * both share lifetime with request queue.
2359 blk_mq_sysfs_deinit(q
);
2361 free_percpu(q
->queue_ctx
);
2364 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2366 struct request_queue
*uninit_q
, *q
;
2368 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2370 return ERR_PTR(-ENOMEM
);
2372 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2374 blk_cleanup_queue(uninit_q
);
2378 EXPORT_SYMBOL(blk_mq_init_queue
);
2380 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2382 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2384 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, queue_rq_srcu
),
2385 __alignof__(struct blk_mq_hw_ctx
)) !=
2386 sizeof(struct blk_mq_hw_ctx
));
2388 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2389 hw_ctx_size
+= sizeof(struct srcu_struct
);
2394 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2395 struct request_queue
*q
)
2398 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2400 blk_mq_sysfs_unregister(q
);
2401 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2407 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2408 hctxs
[i
] = kzalloc_node(blk_mq_hw_ctx_size(set
),
2413 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2420 atomic_set(&hctxs
[i
]->nr_active
, 0);
2421 hctxs
[i
]->numa_node
= node
;
2422 hctxs
[i
]->queue_num
= i
;
2424 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2425 free_cpumask_var(hctxs
[i
]->cpumask
);
2430 blk_mq_hctx_kobj_init(hctxs
[i
]);
2432 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2433 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2437 blk_mq_free_map_and_requests(set
, j
);
2438 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2439 kobject_put(&hctx
->kobj
);
2444 q
->nr_hw_queues
= i
;
2445 blk_mq_sysfs_register(q
);
2448 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2449 struct request_queue
*q
)
2451 /* mark the queue as mq asap */
2452 q
->mq_ops
= set
->ops
;
2454 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2455 blk_mq_poll_stats_bkt
,
2456 BLK_MQ_POLL_STATS_BKTS
, q
);
2460 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2464 /* init q->mq_kobj and sw queues' kobjects */
2465 blk_mq_sysfs_init(q
);
2467 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2468 GFP_KERNEL
, set
->numa_node
);
2469 if (!q
->queue_hw_ctx
)
2472 q
->mq_map
= set
->mq_map
;
2474 blk_mq_realloc_hw_ctxs(set
, q
);
2475 if (!q
->nr_hw_queues
)
2478 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2479 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2481 q
->nr_queues
= nr_cpu_ids
;
2483 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2485 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2486 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2488 q
->sg_reserved_size
= INT_MAX
;
2490 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2491 INIT_LIST_HEAD(&q
->requeue_list
);
2492 spin_lock_init(&q
->requeue_lock
);
2494 blk_queue_make_request(q
, blk_mq_make_request
);
2495 if (q
->mq_ops
->poll
)
2496 q
->poll_fn
= blk_mq_poll
;
2499 * Do this after blk_queue_make_request() overrides it...
2501 q
->nr_requests
= set
->queue_depth
;
2504 * Default to classic polling
2508 if (set
->ops
->complete
)
2509 blk_queue_softirq_done(q
, set
->ops
->complete
);
2511 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2512 blk_mq_add_queue_tag_set(set
, q
);
2513 blk_mq_map_swqueue(q
);
2515 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2518 ret
= blk_mq_sched_init(q
);
2520 return ERR_PTR(ret
);
2526 kfree(q
->queue_hw_ctx
);
2528 free_percpu(q
->queue_ctx
);
2531 return ERR_PTR(-ENOMEM
);
2533 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2535 void blk_mq_free_queue(struct request_queue
*q
)
2537 struct blk_mq_tag_set
*set
= q
->tag_set
;
2539 blk_mq_del_queue_tag_set(q
);
2540 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2543 /* Basically redo blk_mq_init_queue with queue frozen */
2544 static void blk_mq_queue_reinit(struct request_queue
*q
)
2546 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2548 blk_mq_debugfs_unregister_hctxs(q
);
2549 blk_mq_sysfs_unregister(q
);
2552 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2553 * we should change hctx numa_node according to new topology (this
2554 * involves free and re-allocate memory, worthy doing?)
2557 blk_mq_map_swqueue(q
);
2559 blk_mq_sysfs_register(q
);
2560 blk_mq_debugfs_register_hctxs(q
);
2563 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2567 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2568 if (!__blk_mq_alloc_rq_map(set
, i
))
2575 blk_mq_free_rq_map(set
->tags
[i
]);
2581 * Allocate the request maps associated with this tag_set. Note that this
2582 * may reduce the depth asked for, if memory is tight. set->queue_depth
2583 * will be updated to reflect the allocated depth.
2585 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2590 depth
= set
->queue_depth
;
2592 err
= __blk_mq_alloc_rq_maps(set
);
2596 set
->queue_depth
>>= 1;
2597 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2601 } while (set
->queue_depth
);
2603 if (!set
->queue_depth
|| err
) {
2604 pr_err("blk-mq: failed to allocate request map\n");
2608 if (depth
!= set
->queue_depth
)
2609 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2610 depth
, set
->queue_depth
);
2615 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2617 if (set
->ops
->map_queues
)
2618 return set
->ops
->map_queues(set
);
2620 return blk_mq_map_queues(set
);
2624 * Alloc a tag set to be associated with one or more request queues.
2625 * May fail with EINVAL for various error conditions. May adjust the
2626 * requested depth down, if if it too large. In that case, the set
2627 * value will be stored in set->queue_depth.
2629 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2633 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2635 if (!set
->nr_hw_queues
)
2637 if (!set
->queue_depth
)
2639 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2642 if (!set
->ops
->queue_rq
)
2645 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
2648 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2649 pr_info("blk-mq: reduced tag depth to %u\n",
2651 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2655 * If a crashdump is active, then we are potentially in a very
2656 * memory constrained environment. Limit us to 1 queue and
2657 * 64 tags to prevent using too much memory.
2659 if (is_kdump_kernel()) {
2660 set
->nr_hw_queues
= 1;
2661 set
->queue_depth
= min(64U, set
->queue_depth
);
2664 * There is no use for more h/w queues than cpus.
2666 if (set
->nr_hw_queues
> nr_cpu_ids
)
2667 set
->nr_hw_queues
= nr_cpu_ids
;
2669 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2670 GFP_KERNEL
, set
->numa_node
);
2675 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2676 GFP_KERNEL
, set
->numa_node
);
2680 ret
= blk_mq_update_queue_map(set
);
2682 goto out_free_mq_map
;
2684 ret
= blk_mq_alloc_rq_maps(set
);
2686 goto out_free_mq_map
;
2688 mutex_init(&set
->tag_list_lock
);
2689 INIT_LIST_HEAD(&set
->tag_list
);
2701 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2703 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2707 for (i
= 0; i
< nr_cpu_ids
; i
++)
2708 blk_mq_free_map_and_requests(set
, i
);
2716 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2718 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2720 struct blk_mq_tag_set
*set
= q
->tag_set
;
2721 struct blk_mq_hw_ctx
*hctx
;
2727 blk_mq_freeze_queue(q
);
2730 queue_for_each_hw_ctx(q
, hctx
, i
) {
2734 * If we're using an MQ scheduler, just update the scheduler
2735 * queue depth. This is similar to what the old code would do.
2737 if (!hctx
->sched_tags
) {
2738 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
2741 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2749 q
->nr_requests
= nr
;
2751 blk_mq_unfreeze_queue(q
);
2756 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2759 struct request_queue
*q
;
2761 lockdep_assert_held(&set
->tag_list_lock
);
2763 if (nr_hw_queues
> nr_cpu_ids
)
2764 nr_hw_queues
= nr_cpu_ids
;
2765 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2768 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2769 blk_mq_freeze_queue(q
);
2771 set
->nr_hw_queues
= nr_hw_queues
;
2772 blk_mq_update_queue_map(set
);
2773 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2774 blk_mq_realloc_hw_ctxs(set
, q
);
2775 blk_mq_queue_reinit(q
);
2778 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2779 blk_mq_unfreeze_queue(q
);
2782 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2784 mutex_lock(&set
->tag_list_lock
);
2785 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2786 mutex_unlock(&set
->tag_list_lock
);
2788 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2790 /* Enable polling stats and return whether they were already enabled. */
2791 static bool blk_poll_stats_enable(struct request_queue
*q
)
2793 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2794 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2796 blk_stat_add_callback(q
, q
->poll_cb
);
2800 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2803 * We don't arm the callback if polling stats are not enabled or the
2804 * callback is already active.
2806 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2807 blk_stat_is_active(q
->poll_cb
))
2810 blk_stat_activate_msecs(q
->poll_cb
, 100);
2813 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2815 struct request_queue
*q
= cb
->data
;
2818 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
2819 if (cb
->stat
[bucket
].nr_samples
)
2820 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
2824 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2825 struct blk_mq_hw_ctx
*hctx
,
2828 unsigned long ret
= 0;
2832 * If stats collection isn't on, don't sleep but turn it on for
2835 if (!blk_poll_stats_enable(q
))
2839 * As an optimistic guess, use half of the mean service time
2840 * for this type of request. We can (and should) make this smarter.
2841 * For instance, if the completion latencies are tight, we can
2842 * get closer than just half the mean. This is especially
2843 * important on devices where the completion latencies are longer
2844 * than ~10 usec. We do use the stats for the relevant IO size
2845 * if available which does lead to better estimates.
2847 bucket
= blk_mq_poll_stats_bkt(rq
);
2851 if (q
->poll_stat
[bucket
].nr_samples
)
2852 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
2857 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2858 struct blk_mq_hw_ctx
*hctx
,
2861 struct hrtimer_sleeper hs
;
2862 enum hrtimer_mode mode
;
2866 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2872 * -1: don't ever hybrid sleep
2873 * 0: use half of prev avg
2874 * >0: use this specific value
2876 if (q
->poll_nsec
== -1)
2878 else if (q
->poll_nsec
> 0)
2879 nsecs
= q
->poll_nsec
;
2881 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2886 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2889 * This will be replaced with the stats tracking code, using
2890 * 'avg_completion_time / 2' as the pre-sleep target.
2894 mode
= HRTIMER_MODE_REL
;
2895 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2896 hrtimer_set_expires(&hs
.timer
, kt
);
2898 hrtimer_init_sleeper(&hs
, current
);
2900 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2902 set_current_state(TASK_UNINTERRUPTIBLE
);
2903 hrtimer_start_expires(&hs
.timer
, mode
);
2906 hrtimer_cancel(&hs
.timer
);
2907 mode
= HRTIMER_MODE_ABS
;
2908 } while (hs
.task
&& !signal_pending(current
));
2910 __set_current_state(TASK_RUNNING
);
2911 destroy_hrtimer_on_stack(&hs
.timer
);
2915 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2917 struct request_queue
*q
= hctx
->queue
;
2921 * If we sleep, have the caller restart the poll loop to reset
2922 * the state. Like for the other success return cases, the
2923 * caller is responsible for checking if the IO completed. If
2924 * the IO isn't complete, we'll get called again and will go
2925 * straight to the busy poll loop.
2927 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2930 hctx
->poll_considered
++;
2932 state
= current
->state
;
2933 while (!need_resched()) {
2936 hctx
->poll_invoked
++;
2938 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2940 hctx
->poll_success
++;
2941 set_current_state(TASK_RUNNING
);
2945 if (signal_pending_state(state
, current
))
2946 set_current_state(TASK_RUNNING
);
2948 if (current
->state
== TASK_RUNNING
)
2958 static bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2960 struct blk_mq_hw_ctx
*hctx
;
2963 if (!test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2966 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2967 if (!blk_qc_t_is_internal(cookie
))
2968 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2970 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2972 * With scheduling, if the request has completed, we'll
2973 * get a NULL return here, as we clear the sched tag when
2974 * that happens. The request still remains valid, like always,
2975 * so we should be safe with just the NULL check.
2981 return __blk_mq_poll(hctx
, rq
);
2984 static int __init
blk_mq_init(void)
2987 * See comment in block/blk.h rq_atomic_flags enum
2989 BUILD_BUG_ON((REQ_ATOM_STARTED
/ BITS_PER_BYTE
) !=
2990 (REQ_ATOM_COMPLETE
/ BITS_PER_BYTE
));
2992 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2993 blk_mq_hctx_notify_dead
);
2996 subsys_initcall(blk_mq_init
);