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"
39 #include "blk-rq-qos.h"
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 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
66 return !list_empty_careful(&hctx
->dispatch
) ||
67 sbitmap_any_bit_set(&hctx
->ctx_map
) ||
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 const int bit
= ctx
->index_hw
[hctx
->type
];
79 if (!sbitmap_test_bit(&hctx
->ctx_map
, bit
))
80 sbitmap_set_bit(&hctx
->ctx_map
, bit
);
83 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
84 struct blk_mq_ctx
*ctx
)
86 const int bit
= ctx
->index_hw
[hctx
->type
];
88 sbitmap_clear_bit(&hctx
->ctx_map
, bit
);
92 struct hd_struct
*part
;
93 unsigned int *inflight
;
96 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
97 struct request
*rq
, void *priv
,
100 struct mq_inflight
*mi
= priv
;
103 * index[0] counts the specific partition that was asked for.
105 if (rq
->part
== mi
->part
)
111 unsigned int blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
)
113 unsigned inflight
[2];
114 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
116 inflight
[0] = inflight
[1] = 0;
117 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
122 static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx
*hctx
,
123 struct request
*rq
, void *priv
,
126 struct mq_inflight
*mi
= priv
;
128 if (rq
->part
== mi
->part
)
129 mi
->inflight
[rq_data_dir(rq
)]++;
134 void blk_mq_in_flight_rw(struct request_queue
*q
, struct hd_struct
*part
,
135 unsigned int inflight
[2])
137 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
139 inflight
[0] = inflight
[1] = 0;
140 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight_rw
, &mi
);
143 void blk_freeze_queue_start(struct request_queue
*q
)
147 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
148 if (freeze_depth
== 1) {
149 percpu_ref_kill(&q
->q_usage_counter
);
151 blk_mq_run_hw_queues(q
, false);
154 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
156 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
158 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
160 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
162 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
163 unsigned long timeout
)
165 return wait_event_timeout(q
->mq_freeze_wq
,
166 percpu_ref_is_zero(&q
->q_usage_counter
),
169 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
172 * Guarantee no request is in use, so we can change any data structure of
173 * the queue afterward.
175 void blk_freeze_queue(struct request_queue
*q
)
178 * In the !blk_mq case we are only calling this to kill the
179 * q_usage_counter, otherwise this increases the freeze depth
180 * and waits for it to return to zero. For this reason there is
181 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
182 * exported to drivers as the only user for unfreeze is blk_mq.
184 blk_freeze_queue_start(q
);
185 blk_mq_freeze_queue_wait(q
);
188 void blk_mq_freeze_queue(struct request_queue
*q
)
191 * ...just an alias to keep freeze and unfreeze actions balanced
192 * in the blk_mq_* namespace
196 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
198 void blk_mq_unfreeze_queue(struct request_queue
*q
)
202 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
203 WARN_ON_ONCE(freeze_depth
< 0);
205 percpu_ref_resurrect(&q
->q_usage_counter
);
206 wake_up_all(&q
->mq_freeze_wq
);
209 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
212 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
213 * mpt3sas driver such that this function can be removed.
215 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
217 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
219 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
222 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
225 * Note: this function does not prevent that the struct request end_io()
226 * callback function is invoked. Once this function is returned, we make
227 * sure no dispatch can happen until the queue is unquiesced via
228 * blk_mq_unquiesce_queue().
230 void blk_mq_quiesce_queue(struct request_queue
*q
)
232 struct blk_mq_hw_ctx
*hctx
;
236 blk_mq_quiesce_queue_nowait(q
);
238 queue_for_each_hw_ctx(q
, hctx
, i
) {
239 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
240 synchronize_srcu(hctx
->srcu
);
247 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
250 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
253 * This function recovers queue into the state before quiescing
254 * which is done by blk_mq_quiesce_queue.
256 void blk_mq_unquiesce_queue(struct request_queue
*q
)
258 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
260 /* dispatch requests which are inserted during quiescing */
261 blk_mq_run_hw_queues(q
, true);
263 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
265 void blk_mq_wake_waiters(struct request_queue
*q
)
267 struct blk_mq_hw_ctx
*hctx
;
270 queue_for_each_hw_ctx(q
, hctx
, i
)
271 if (blk_mq_hw_queue_mapped(hctx
))
272 blk_mq_tag_wakeup_all(hctx
->tags
, true);
275 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
277 return blk_mq_has_free_tags(hctx
->tags
);
279 EXPORT_SYMBOL(blk_mq_can_queue
);
282 * Only need start/end time stamping if we have stats enabled, or using
285 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
287 return (rq
->rq_flags
& RQF_IO_STAT
) || rq
->q
->elevator
;
290 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
291 unsigned int tag
, unsigned int op
)
293 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
294 struct request
*rq
= tags
->static_rqs
[tag
];
295 req_flags_t rq_flags
= 0;
297 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
299 rq
->internal_tag
= tag
;
301 if (data
->hctx
->flags
& BLK_MQ_F_TAG_SHARED
) {
302 rq_flags
= RQF_MQ_INFLIGHT
;
303 atomic_inc(&data
->hctx
->nr_active
);
306 rq
->internal_tag
= -1;
307 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
310 /* csd/requeue_work/fifo_time is initialized before use */
312 rq
->mq_ctx
= data
->ctx
;
313 rq
->mq_hctx
= data
->hctx
;
314 rq
->rq_flags
= rq_flags
;
316 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
317 rq
->rq_flags
|= RQF_PREEMPT
;
318 if (blk_queue_io_stat(data
->q
))
319 rq
->rq_flags
|= RQF_IO_STAT
;
320 INIT_LIST_HEAD(&rq
->queuelist
);
321 INIT_HLIST_NODE(&rq
->hash
);
322 RB_CLEAR_NODE(&rq
->rb_node
);
325 if (blk_mq_need_time_stamp(rq
))
326 rq
->start_time_ns
= ktime_get_ns();
328 rq
->start_time_ns
= 0;
329 rq
->io_start_time_ns
= 0;
330 rq
->nr_phys_segments
= 0;
331 #if defined(CONFIG_BLK_DEV_INTEGRITY)
332 rq
->nr_integrity_segments
= 0;
335 /* tag was already set */
337 WRITE_ONCE(rq
->deadline
, 0);
342 rq
->end_io_data
= NULL
;
345 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
346 refcount_set(&rq
->ref
, 1);
350 static struct request
*blk_mq_get_request(struct request_queue
*q
,
352 struct blk_mq_alloc_data
*data
)
354 struct elevator_queue
*e
= q
->elevator
;
357 bool put_ctx_on_error
= false;
359 blk_queue_enter_live(q
);
361 if (likely(!data
->ctx
)) {
362 data
->ctx
= blk_mq_get_ctx(q
);
363 put_ctx_on_error
= true;
365 if (likely(!data
->hctx
))
366 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
,
368 if (data
->cmd_flags
& REQ_NOWAIT
)
369 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
372 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
375 * Flush requests are special and go directly to the
376 * dispatch list. Don't include reserved tags in the
377 * limiting, as it isn't useful.
379 if (!op_is_flush(data
->cmd_flags
) &&
380 e
->type
->ops
.limit_depth
&&
381 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
382 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
384 blk_mq_tag_busy(data
->hctx
);
387 tag
= blk_mq_get_tag(data
);
388 if (tag
== BLK_MQ_TAG_FAIL
) {
389 if (put_ctx_on_error
) {
390 blk_mq_put_ctx(data
->ctx
);
397 rq
= blk_mq_rq_ctx_init(data
, tag
, data
->cmd_flags
);
398 if (!op_is_flush(data
->cmd_flags
)) {
400 if (e
&& e
->type
->ops
.prepare_request
) {
401 if (e
->type
->icq_cache
)
402 blk_mq_sched_assign_ioc(rq
);
404 e
->type
->ops
.prepare_request(rq
, bio
);
405 rq
->rq_flags
|= RQF_ELVPRIV
;
408 data
->hctx
->queued
++;
412 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
413 blk_mq_req_flags_t flags
)
415 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
419 ret
= blk_queue_enter(q
, flags
);
423 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
427 return ERR_PTR(-EWOULDBLOCK
);
429 blk_mq_put_ctx(alloc_data
.ctx
);
432 rq
->__sector
= (sector_t
) -1;
433 rq
->bio
= rq
->biotail
= NULL
;
436 EXPORT_SYMBOL(blk_mq_alloc_request
);
438 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
439 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
441 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
447 * If the tag allocator sleeps we could get an allocation for a
448 * different hardware context. No need to complicate the low level
449 * allocator for this for the rare use case of a command tied to
452 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
453 return ERR_PTR(-EINVAL
);
455 if (hctx_idx
>= q
->nr_hw_queues
)
456 return ERR_PTR(-EIO
);
458 ret
= blk_queue_enter(q
, flags
);
463 * Check if the hardware context is actually mapped to anything.
464 * If not tell the caller that it should skip this queue.
466 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
467 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
469 return ERR_PTR(-EXDEV
);
471 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
472 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
474 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
478 return ERR_PTR(-EWOULDBLOCK
);
482 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
484 static void __blk_mq_free_request(struct request
*rq
)
486 struct request_queue
*q
= rq
->q
;
487 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
488 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
489 const int sched_tag
= rq
->internal_tag
;
491 blk_pm_mark_last_busy(rq
);
494 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
496 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
497 blk_mq_sched_restart(hctx
);
501 void blk_mq_free_request(struct request
*rq
)
503 struct request_queue
*q
= rq
->q
;
504 struct elevator_queue
*e
= q
->elevator
;
505 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
506 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
508 if (rq
->rq_flags
& RQF_ELVPRIV
) {
509 if (e
&& e
->type
->ops
.finish_request
)
510 e
->type
->ops
.finish_request(rq
);
512 put_io_context(rq
->elv
.icq
->ioc
);
517 ctx
->rq_completed
[rq_is_sync(rq
)]++;
518 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
519 atomic_dec(&hctx
->nr_active
);
521 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
522 laptop_io_completion(q
->backing_dev_info
);
526 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
527 if (refcount_dec_and_test(&rq
->ref
))
528 __blk_mq_free_request(rq
);
530 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
532 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
536 if (blk_mq_need_time_stamp(rq
))
537 now
= ktime_get_ns();
539 if (rq
->rq_flags
& RQF_STATS
) {
540 blk_mq_poll_stats_start(rq
->q
);
541 blk_stat_add(rq
, now
);
544 if (rq
->internal_tag
!= -1)
545 blk_mq_sched_completed_request(rq
, now
);
547 blk_account_io_done(rq
, now
);
550 rq_qos_done(rq
->q
, rq
);
551 rq
->end_io(rq
, error
);
553 if (unlikely(blk_bidi_rq(rq
)))
554 blk_mq_free_request(rq
->next_rq
);
555 blk_mq_free_request(rq
);
558 EXPORT_SYMBOL(__blk_mq_end_request
);
560 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
562 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
564 __blk_mq_end_request(rq
, error
);
566 EXPORT_SYMBOL(blk_mq_end_request
);
568 static void __blk_mq_complete_request_remote(void *data
)
570 struct request
*rq
= data
;
571 struct request_queue
*q
= rq
->q
;
573 q
->mq_ops
->complete(rq
);
576 static void __blk_mq_complete_request(struct request
*rq
)
578 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
579 struct request_queue
*q
= rq
->q
;
583 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
585 * Most of single queue controllers, there is only one irq vector
586 * for handling IO completion, and the only irq's affinity is set
587 * as all possible CPUs. On most of ARCHs, this affinity means the
588 * irq is handled on one specific CPU.
590 * So complete IO reqeust in softirq context in case of single queue
591 * for not degrading IO performance by irqsoff latency.
593 if (q
->nr_hw_queues
== 1) {
594 __blk_complete_request(rq
);
599 * For a polled request, always complete locallly, it's pointless
600 * to redirect the completion.
602 if ((rq
->cmd_flags
& REQ_HIPRI
) ||
603 !test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
)) {
604 q
->mq_ops
->complete(rq
);
609 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &q
->queue_flags
))
610 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
612 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
613 rq
->csd
.func
= __blk_mq_complete_request_remote
;
616 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
618 q
->mq_ops
->complete(rq
);
623 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
624 __releases(hctx
->srcu
)
626 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
629 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
632 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
633 __acquires(hctx
->srcu
)
635 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
636 /* shut up gcc false positive */
640 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
644 * blk_mq_complete_request - end I/O on a request
645 * @rq: the request being processed
648 * Ends all I/O on a request. It does not handle partial completions.
649 * The actual completion happens out-of-order, through a IPI handler.
651 bool blk_mq_complete_request(struct request
*rq
)
653 if (unlikely(blk_should_fake_timeout(rq
->q
)))
655 __blk_mq_complete_request(rq
);
658 EXPORT_SYMBOL(blk_mq_complete_request
);
660 int blk_mq_request_started(struct request
*rq
)
662 return blk_mq_rq_state(rq
) != MQ_RQ_IDLE
;
664 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
666 void blk_mq_start_request(struct request
*rq
)
668 struct request_queue
*q
= rq
->q
;
670 blk_mq_sched_started_request(rq
);
672 trace_block_rq_issue(q
, rq
);
674 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
675 rq
->io_start_time_ns
= ktime_get_ns();
676 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
677 rq
->throtl_size
= blk_rq_sectors(rq
);
679 rq
->rq_flags
|= RQF_STATS
;
683 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
686 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
688 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
690 * Make sure space for the drain appears. We know we can do
691 * this because max_hw_segments has been adjusted to be one
692 * fewer than the device can handle.
694 rq
->nr_phys_segments
++;
697 EXPORT_SYMBOL(blk_mq_start_request
);
699 static void __blk_mq_requeue_request(struct request
*rq
)
701 struct request_queue
*q
= rq
->q
;
703 blk_mq_put_driver_tag(rq
);
705 trace_block_rq_requeue(q
, rq
);
706 rq_qos_requeue(q
, rq
);
708 if (blk_mq_request_started(rq
)) {
709 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
710 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
711 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
712 rq
->nr_phys_segments
--;
716 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
718 __blk_mq_requeue_request(rq
);
720 /* this request will be re-inserted to io scheduler queue */
721 blk_mq_sched_requeue_request(rq
);
723 BUG_ON(!list_empty(&rq
->queuelist
));
724 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
726 EXPORT_SYMBOL(blk_mq_requeue_request
);
728 static void blk_mq_requeue_work(struct work_struct
*work
)
730 struct request_queue
*q
=
731 container_of(work
, struct request_queue
, requeue_work
.work
);
733 struct request
*rq
, *next
;
735 spin_lock_irq(&q
->requeue_lock
);
736 list_splice_init(&q
->requeue_list
, &rq_list
);
737 spin_unlock_irq(&q
->requeue_lock
);
739 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
740 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
743 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
744 list_del_init(&rq
->queuelist
);
745 blk_mq_sched_insert_request(rq
, true, false, false);
748 while (!list_empty(&rq_list
)) {
749 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
750 list_del_init(&rq
->queuelist
);
751 blk_mq_sched_insert_request(rq
, false, false, false);
754 blk_mq_run_hw_queues(q
, false);
757 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
758 bool kick_requeue_list
)
760 struct request_queue
*q
= rq
->q
;
764 * We abuse this flag that is otherwise used by the I/O scheduler to
765 * request head insertion from the workqueue.
767 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
769 spin_lock_irqsave(&q
->requeue_lock
, flags
);
771 rq
->rq_flags
|= RQF_SOFTBARRIER
;
772 list_add(&rq
->queuelist
, &q
->requeue_list
);
774 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
776 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
778 if (kick_requeue_list
)
779 blk_mq_kick_requeue_list(q
);
781 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
783 void blk_mq_kick_requeue_list(struct request_queue
*q
)
785 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
787 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
789 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
792 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
793 msecs_to_jiffies(msecs
));
795 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
797 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
799 if (tag
< tags
->nr_tags
) {
800 prefetch(tags
->rqs
[tag
]);
801 return tags
->rqs
[tag
];
806 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
808 static bool blk_mq_check_busy(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
809 void *priv
, bool reserved
)
812 * If we find a request, we know the queue is busy. Return false
813 * to stop the iteration.
815 if (rq
->q
== hctx
->queue
) {
825 bool blk_mq_queue_busy(struct request_queue
*q
)
829 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_busy
, &busy
);
832 EXPORT_SYMBOL_GPL(blk_mq_queue_busy
);
834 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
836 req
->rq_flags
|= RQF_TIMED_OUT
;
837 if (req
->q
->mq_ops
->timeout
) {
838 enum blk_eh_timer_return ret
;
840 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
841 if (ret
== BLK_EH_DONE
)
843 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
849 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
851 unsigned long deadline
;
853 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
855 if (rq
->rq_flags
& RQF_TIMED_OUT
)
858 deadline
= READ_ONCE(rq
->deadline
);
859 if (time_after_eq(jiffies
, deadline
))
864 else if (time_after(*next
, deadline
))
869 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
870 struct request
*rq
, void *priv
, bool reserved
)
872 unsigned long *next
= priv
;
875 * Just do a quick check if it is expired before locking the request in
876 * so we're not unnecessarilly synchronizing across CPUs.
878 if (!blk_mq_req_expired(rq
, next
))
882 * We have reason to believe the request may be expired. Take a
883 * reference on the request to lock this request lifetime into its
884 * currently allocated context to prevent it from being reallocated in
885 * the event the completion by-passes this timeout handler.
887 * If the reference was already released, then the driver beat the
888 * timeout handler to posting a natural completion.
890 if (!refcount_inc_not_zero(&rq
->ref
))
894 * The request is now locked and cannot be reallocated underneath the
895 * timeout handler's processing. Re-verify this exact request is truly
896 * expired; if it is not expired, then the request was completed and
897 * reallocated as a new request.
899 if (blk_mq_req_expired(rq
, next
))
900 blk_mq_rq_timed_out(rq
, reserved
);
901 if (refcount_dec_and_test(&rq
->ref
))
902 __blk_mq_free_request(rq
);
907 static void blk_mq_timeout_work(struct work_struct
*work
)
909 struct request_queue
*q
=
910 container_of(work
, struct request_queue
, timeout_work
);
911 unsigned long next
= 0;
912 struct blk_mq_hw_ctx
*hctx
;
915 /* A deadlock might occur if a request is stuck requiring a
916 * timeout at the same time a queue freeze is waiting
917 * completion, since the timeout code would not be able to
918 * acquire the queue reference here.
920 * That's why we don't use blk_queue_enter here; instead, we use
921 * percpu_ref_tryget directly, because we need to be able to
922 * obtain a reference even in the short window between the queue
923 * starting to freeze, by dropping the first reference in
924 * blk_freeze_queue_start, and the moment the last request is
925 * consumed, marked by the instant q_usage_counter reaches
928 if (!percpu_ref_tryget(&q
->q_usage_counter
))
931 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
934 mod_timer(&q
->timeout
, next
);
937 * Request timeouts are handled as a forward rolling timer. If
938 * we end up here it means that no requests are pending and
939 * also that no request has been pending for a while. Mark
942 queue_for_each_hw_ctx(q
, hctx
, i
) {
943 /* the hctx may be unmapped, so check it here */
944 if (blk_mq_hw_queue_mapped(hctx
))
945 blk_mq_tag_idle(hctx
);
951 struct flush_busy_ctx_data
{
952 struct blk_mq_hw_ctx
*hctx
;
953 struct list_head
*list
;
956 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
958 struct flush_busy_ctx_data
*flush_data
= data
;
959 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
960 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
962 spin_lock(&ctx
->lock
);
963 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
964 sbitmap_clear_bit(sb
, bitnr
);
965 spin_unlock(&ctx
->lock
);
970 * Process software queues that have been marked busy, splicing them
971 * to the for-dispatch
973 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
975 struct flush_busy_ctx_data data
= {
980 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
982 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
984 struct dispatch_rq_data
{
985 struct blk_mq_hw_ctx
*hctx
;
989 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
992 struct dispatch_rq_data
*dispatch_data
= data
;
993 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
994 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
996 spin_lock(&ctx
->lock
);
997 if (!list_empty(&ctx
->rq_list
)) {
998 dispatch_data
->rq
= list_entry_rq(ctx
->rq_list
.next
);
999 list_del_init(&dispatch_data
->rq
->queuelist
);
1000 if (list_empty(&ctx
->rq_list
))
1001 sbitmap_clear_bit(sb
, bitnr
);
1003 spin_unlock(&ctx
->lock
);
1005 return !dispatch_data
->rq
;
1008 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1009 struct blk_mq_ctx
*start
)
1011 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1012 struct dispatch_rq_data data
= {
1017 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1018 dispatch_rq_from_ctx
, &data
);
1023 static inline unsigned int queued_to_index(unsigned int queued
)
1028 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1031 bool blk_mq_get_driver_tag(struct request
*rq
)
1033 struct blk_mq_alloc_data data
= {
1035 .hctx
= rq
->mq_hctx
,
1036 .flags
= BLK_MQ_REQ_NOWAIT
,
1037 .cmd_flags
= rq
->cmd_flags
,
1044 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
1045 data
.flags
|= BLK_MQ_REQ_RESERVED
;
1047 shared
= blk_mq_tag_busy(data
.hctx
);
1048 rq
->tag
= blk_mq_get_tag(&data
);
1051 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1052 atomic_inc(&data
.hctx
->nr_active
);
1054 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
1058 return rq
->tag
!= -1;
1061 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1062 int flags
, void *key
)
1064 struct blk_mq_hw_ctx
*hctx
;
1066 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1068 spin_lock(&hctx
->dispatch_wait_lock
);
1069 list_del_init(&wait
->entry
);
1070 spin_unlock(&hctx
->dispatch_wait_lock
);
1072 blk_mq_run_hw_queue(hctx
, true);
1077 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1078 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1079 * restart. For both cases, take care to check the condition again after
1080 * marking us as waiting.
1082 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1085 struct wait_queue_head
*wq
;
1086 wait_queue_entry_t
*wait
;
1089 if (!(hctx
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1090 if (!test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
1091 set_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
);
1094 * It's possible that a tag was freed in the window between the
1095 * allocation failure and adding the hardware queue to the wait
1098 * Don't clear RESTART here, someone else could have set it.
1099 * At most this will cost an extra queue run.
1101 return blk_mq_get_driver_tag(rq
);
1104 wait
= &hctx
->dispatch_wait
;
1105 if (!list_empty_careful(&wait
->entry
))
1108 wq
= &bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
)->wait
;
1110 spin_lock_irq(&wq
->lock
);
1111 spin_lock(&hctx
->dispatch_wait_lock
);
1112 if (!list_empty(&wait
->entry
)) {
1113 spin_unlock(&hctx
->dispatch_wait_lock
);
1114 spin_unlock_irq(&wq
->lock
);
1118 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1119 __add_wait_queue(wq
, wait
);
1122 * It's possible that a tag was freed in the window between the
1123 * allocation failure and adding the hardware queue to the wait
1126 ret
= blk_mq_get_driver_tag(rq
);
1128 spin_unlock(&hctx
->dispatch_wait_lock
);
1129 spin_unlock_irq(&wq
->lock
);
1134 * We got a tag, remove ourselves from the wait queue to ensure
1135 * someone else gets the wakeup.
1137 list_del_init(&wait
->entry
);
1138 spin_unlock(&hctx
->dispatch_wait_lock
);
1139 spin_unlock_irq(&wq
->lock
);
1144 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1145 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1147 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1148 * - EWMA is one simple way to compute running average value
1149 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1150 * - take 4 as factor for avoiding to get too small(0) result, and this
1151 * factor doesn't matter because EWMA decreases exponentially
1153 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1157 if (hctx
->queue
->elevator
)
1160 ewma
= hctx
->dispatch_busy
;
1165 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1167 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1168 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1170 hctx
->dispatch_busy
= ewma
;
1173 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1176 * Returns true if we did some work AND can potentially do more.
1178 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1181 struct blk_mq_hw_ctx
*hctx
;
1182 struct request
*rq
, *nxt
;
1183 bool no_tag
= false;
1185 blk_status_t ret
= BLK_STS_OK
;
1187 if (list_empty(list
))
1190 WARN_ON(!list_is_singular(list
) && got_budget
);
1193 * Now process all the entries, sending them to the driver.
1195 errors
= queued
= 0;
1197 struct blk_mq_queue_data bd
;
1199 rq
= list_first_entry(list
, struct request
, queuelist
);
1202 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1205 if (!blk_mq_get_driver_tag(rq
)) {
1207 * The initial allocation attempt failed, so we need to
1208 * rerun the hardware queue when a tag is freed. The
1209 * waitqueue takes care of that. If the queue is run
1210 * before we add this entry back on the dispatch list,
1211 * we'll re-run it below.
1213 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1214 blk_mq_put_dispatch_budget(hctx
);
1216 * For non-shared tags, the RESTART check
1219 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1225 list_del_init(&rq
->queuelist
);
1230 * Flag last if we have no more requests, or if we have more
1231 * but can't assign a driver tag to it.
1233 if (list_empty(list
))
1236 nxt
= list_first_entry(list
, struct request
, queuelist
);
1237 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1240 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1241 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
) {
1243 * If an I/O scheduler has been configured and we got a
1244 * driver tag for the next request already, free it
1247 if (!list_empty(list
)) {
1248 nxt
= list_first_entry(list
, struct request
, queuelist
);
1249 blk_mq_put_driver_tag(nxt
);
1251 list_add(&rq
->queuelist
, list
);
1252 __blk_mq_requeue_request(rq
);
1256 if (unlikely(ret
!= BLK_STS_OK
)) {
1258 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1263 } while (!list_empty(list
));
1265 hctx
->dispatched
[queued_to_index(queued
)]++;
1268 * Any items that need requeuing? Stuff them into hctx->dispatch,
1269 * that is where we will continue on next queue run.
1271 if (!list_empty(list
)) {
1275 * If we didn't flush the entire list, we could have told
1276 * the driver there was more coming, but that turned out to
1279 if (q
->mq_ops
->commit_rqs
)
1280 q
->mq_ops
->commit_rqs(hctx
);
1282 spin_lock(&hctx
->lock
);
1283 list_splice_init(list
, &hctx
->dispatch
);
1284 spin_unlock(&hctx
->lock
);
1287 * If SCHED_RESTART was set by the caller of this function and
1288 * it is no longer set that means that it was cleared by another
1289 * thread and hence that a queue rerun is needed.
1291 * If 'no_tag' is set, that means that we failed getting
1292 * a driver tag with an I/O scheduler attached. If our dispatch
1293 * waitqueue is no longer active, ensure that we run the queue
1294 * AFTER adding our entries back to the list.
1296 * If no I/O scheduler has been configured it is possible that
1297 * the hardware queue got stopped and restarted before requests
1298 * were pushed back onto the dispatch list. Rerun the queue to
1299 * avoid starvation. Notes:
1300 * - blk_mq_run_hw_queue() checks whether or not a queue has
1301 * been stopped before rerunning a queue.
1302 * - Some but not all block drivers stop a queue before
1303 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1306 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1307 * bit is set, run queue after a delay to avoid IO stalls
1308 * that could otherwise occur if the queue is idle.
1310 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1311 if (!needs_restart
||
1312 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1313 blk_mq_run_hw_queue(hctx
, true);
1314 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
))
1315 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1317 blk_mq_update_dispatch_busy(hctx
, true);
1320 blk_mq_update_dispatch_busy(hctx
, false);
1323 * If the host/device is unable to accept more work, inform the
1326 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1329 return (queued
+ errors
) != 0;
1332 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1337 * We should be running this queue from one of the CPUs that
1340 * There are at least two related races now between setting
1341 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1342 * __blk_mq_run_hw_queue():
1344 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1345 * but later it becomes online, then this warning is harmless
1348 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1349 * but later it becomes offline, then the warning can't be
1350 * triggered, and we depend on blk-mq timeout handler to
1351 * handle dispatched requests to this hctx
1353 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1354 cpu_online(hctx
->next_cpu
)) {
1355 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1356 raw_smp_processor_id(),
1357 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1362 * We can't run the queue inline with ints disabled. Ensure that
1363 * we catch bad users of this early.
1365 WARN_ON_ONCE(in_interrupt());
1367 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1369 hctx_lock(hctx
, &srcu_idx
);
1370 blk_mq_sched_dispatch_requests(hctx
);
1371 hctx_unlock(hctx
, srcu_idx
);
1374 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1376 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1378 if (cpu
>= nr_cpu_ids
)
1379 cpu
= cpumask_first(hctx
->cpumask
);
1384 * It'd be great if the workqueue API had a way to pass
1385 * in a mask and had some smarts for more clever placement.
1386 * For now we just round-robin here, switching for every
1387 * BLK_MQ_CPU_WORK_BATCH queued items.
1389 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1392 int next_cpu
= hctx
->next_cpu
;
1394 if (hctx
->queue
->nr_hw_queues
== 1)
1395 return WORK_CPU_UNBOUND
;
1397 if (--hctx
->next_cpu_batch
<= 0) {
1399 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1401 if (next_cpu
>= nr_cpu_ids
)
1402 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1403 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1407 * Do unbound schedule if we can't find a online CPU for this hctx,
1408 * and it should only happen in the path of handling CPU DEAD.
1410 if (!cpu_online(next_cpu
)) {
1417 * Make sure to re-select CPU next time once after CPUs
1418 * in hctx->cpumask become online again.
1420 hctx
->next_cpu
= next_cpu
;
1421 hctx
->next_cpu_batch
= 1;
1422 return WORK_CPU_UNBOUND
;
1425 hctx
->next_cpu
= next_cpu
;
1429 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1430 unsigned long msecs
)
1432 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1435 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1436 int cpu
= get_cpu();
1437 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1438 __blk_mq_run_hw_queue(hctx
);
1446 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1447 msecs_to_jiffies(msecs
));
1450 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1452 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1454 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1456 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1462 * When queue is quiesced, we may be switching io scheduler, or
1463 * updating nr_hw_queues, or other things, and we can't run queue
1464 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1466 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1469 hctx_lock(hctx
, &srcu_idx
);
1470 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1471 blk_mq_hctx_has_pending(hctx
);
1472 hctx_unlock(hctx
, srcu_idx
);
1475 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1481 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1483 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1485 struct blk_mq_hw_ctx
*hctx
;
1488 queue_for_each_hw_ctx(q
, hctx
, i
) {
1489 if (blk_mq_hctx_stopped(hctx
))
1492 blk_mq_run_hw_queue(hctx
, async
);
1495 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1498 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1499 * @q: request queue.
1501 * The caller is responsible for serializing this function against
1502 * blk_mq_{start,stop}_hw_queue().
1504 bool blk_mq_queue_stopped(struct request_queue
*q
)
1506 struct blk_mq_hw_ctx
*hctx
;
1509 queue_for_each_hw_ctx(q
, hctx
, i
)
1510 if (blk_mq_hctx_stopped(hctx
))
1515 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1518 * This function is often used for pausing .queue_rq() by driver when
1519 * there isn't enough resource or some conditions aren't satisfied, and
1520 * BLK_STS_RESOURCE is usually returned.
1522 * We do not guarantee that dispatch can be drained or blocked
1523 * after blk_mq_stop_hw_queue() returns. Please use
1524 * blk_mq_quiesce_queue() for that requirement.
1526 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1528 cancel_delayed_work(&hctx
->run_work
);
1530 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1532 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1535 * This function is often used for pausing .queue_rq() by driver when
1536 * there isn't enough resource or some conditions aren't satisfied, and
1537 * BLK_STS_RESOURCE is usually returned.
1539 * We do not guarantee that dispatch can be drained or blocked
1540 * after blk_mq_stop_hw_queues() returns. Please use
1541 * blk_mq_quiesce_queue() for that requirement.
1543 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1545 struct blk_mq_hw_ctx
*hctx
;
1548 queue_for_each_hw_ctx(q
, hctx
, i
)
1549 blk_mq_stop_hw_queue(hctx
);
1551 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1553 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1555 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1557 blk_mq_run_hw_queue(hctx
, false);
1559 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1561 void blk_mq_start_hw_queues(struct request_queue
*q
)
1563 struct blk_mq_hw_ctx
*hctx
;
1566 queue_for_each_hw_ctx(q
, hctx
, i
)
1567 blk_mq_start_hw_queue(hctx
);
1569 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1571 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1573 if (!blk_mq_hctx_stopped(hctx
))
1576 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1577 blk_mq_run_hw_queue(hctx
, async
);
1579 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1581 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1583 struct blk_mq_hw_ctx
*hctx
;
1586 queue_for_each_hw_ctx(q
, hctx
, i
)
1587 blk_mq_start_stopped_hw_queue(hctx
, async
);
1589 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1591 static void blk_mq_run_work_fn(struct work_struct
*work
)
1593 struct blk_mq_hw_ctx
*hctx
;
1595 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1598 * If we are stopped, don't run the queue.
1600 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1603 __blk_mq_run_hw_queue(hctx
);
1606 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1610 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1612 lockdep_assert_held(&ctx
->lock
);
1614 trace_block_rq_insert(hctx
->queue
, rq
);
1617 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1619 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1622 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1625 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1627 lockdep_assert_held(&ctx
->lock
);
1629 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1630 blk_mq_hctx_mark_pending(hctx
, ctx
);
1634 * Should only be used carefully, when the caller knows we want to
1635 * bypass a potential IO scheduler on the target device.
1637 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1639 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1641 spin_lock(&hctx
->lock
);
1642 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1643 spin_unlock(&hctx
->lock
);
1646 blk_mq_run_hw_queue(hctx
, false);
1649 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1650 struct list_head
*list
)
1656 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1659 list_for_each_entry(rq
, list
, queuelist
) {
1660 BUG_ON(rq
->mq_ctx
!= ctx
);
1661 trace_block_rq_insert(hctx
->queue
, rq
);
1664 spin_lock(&ctx
->lock
);
1665 list_splice_tail_init(list
, &ctx
->rq_list
);
1666 blk_mq_hctx_mark_pending(hctx
, ctx
);
1667 spin_unlock(&ctx
->lock
);
1670 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1672 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1673 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1675 if (rqa
->mq_ctx
< rqb
->mq_ctx
)
1677 else if (rqa
->mq_ctx
> rqb
->mq_ctx
)
1679 else if (rqa
->mq_hctx
< rqb
->mq_hctx
)
1681 else if (rqa
->mq_hctx
> rqb
->mq_hctx
)
1684 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1687 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1689 struct blk_mq_hw_ctx
*this_hctx
;
1690 struct blk_mq_ctx
*this_ctx
;
1691 struct request_queue
*this_q
;
1697 list_splice_init(&plug
->mq_list
, &list
);
1700 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1701 list_sort(NULL
, &list
, plug_rq_cmp
);
1708 while (!list_empty(&list
)) {
1709 rq
= list_entry_rq(list
.next
);
1710 list_del_init(&rq
->queuelist
);
1712 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
) {
1714 trace_block_unplug(this_q
, depth
, !from_schedule
);
1715 blk_mq_sched_insert_requests(this_hctx
, this_ctx
,
1721 this_ctx
= rq
->mq_ctx
;
1722 this_hctx
= rq
->mq_hctx
;
1727 list_add_tail(&rq
->queuelist
, &rq_list
);
1731 * If 'this_hctx' is set, we know we have entries to complete
1732 * on 'rq_list'. Do those.
1735 trace_block_unplug(this_q
, depth
, !from_schedule
);
1736 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1741 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1743 blk_init_request_from_bio(rq
, bio
);
1745 blk_account_io_start(rq
, true);
1748 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1751 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1753 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1756 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1758 blk_qc_t
*cookie
, bool last
)
1760 struct request_queue
*q
= rq
->q
;
1761 struct blk_mq_queue_data bd
= {
1765 blk_qc_t new_cookie
;
1768 new_cookie
= request_to_qc_t(hctx
, rq
);
1771 * For OK queue, we are done. For error, caller may kill it.
1772 * Any other error (busy), just add it to our list as we
1773 * previously would have done.
1775 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1778 blk_mq_update_dispatch_busy(hctx
, false);
1779 *cookie
= new_cookie
;
1781 case BLK_STS_RESOURCE
:
1782 case BLK_STS_DEV_RESOURCE
:
1783 blk_mq_update_dispatch_busy(hctx
, true);
1784 __blk_mq_requeue_request(rq
);
1787 blk_mq_update_dispatch_busy(hctx
, false);
1788 *cookie
= BLK_QC_T_NONE
;
1795 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1798 bool bypass_insert
, bool last
)
1800 struct request_queue
*q
= rq
->q
;
1801 bool run_queue
= true;
1804 * RCU or SRCU read lock is needed before checking quiesced flag.
1806 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1807 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1808 * and avoid driver to try to dispatch again.
1810 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1812 bypass_insert
= false;
1816 if (q
->elevator
&& !bypass_insert
)
1819 if (!blk_mq_get_dispatch_budget(hctx
))
1822 if (!blk_mq_get_driver_tag(rq
)) {
1823 blk_mq_put_dispatch_budget(hctx
);
1827 return __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
1830 return BLK_STS_RESOURCE
;
1832 blk_mq_request_bypass_insert(rq
, run_queue
);
1836 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1837 struct request
*rq
, blk_qc_t
*cookie
)
1842 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1844 hctx_lock(hctx
, &srcu_idx
);
1846 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false, true);
1847 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1848 blk_mq_request_bypass_insert(rq
, true);
1849 else if (ret
!= BLK_STS_OK
)
1850 blk_mq_end_request(rq
, ret
);
1852 hctx_unlock(hctx
, srcu_idx
);
1855 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
, bool last
)
1859 blk_qc_t unused_cookie
;
1860 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1862 hctx_lock(hctx
, &srcu_idx
);
1863 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true, last
);
1864 hctx_unlock(hctx
, srcu_idx
);
1869 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
1870 struct list_head
*list
)
1872 while (!list_empty(list
)) {
1874 struct request
*rq
= list_first_entry(list
, struct request
,
1877 list_del_init(&rq
->queuelist
);
1878 ret
= blk_mq_request_issue_directly(rq
, list_empty(list
));
1879 if (ret
!= BLK_STS_OK
) {
1880 if (ret
== BLK_STS_RESOURCE
||
1881 ret
== BLK_STS_DEV_RESOURCE
) {
1882 blk_mq_request_bypass_insert(rq
,
1886 blk_mq_end_request(rq
, ret
);
1891 * If we didn't flush the entire list, we could have told
1892 * the driver there was more coming, but that turned out to
1895 if (!list_empty(list
) && hctx
->queue
->mq_ops
->commit_rqs
)
1896 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
1899 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
1901 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1903 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
1904 struct request
*tmp
;
1906 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
1908 if (tmp
->q
!= rq
->q
)
1909 plug
->multiple_queues
= true;
1913 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1915 const int is_sync
= op_is_sync(bio
->bi_opf
);
1916 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1917 struct blk_mq_alloc_data data
= { .flags
= 0, .cmd_flags
= bio
->bi_opf
};
1919 struct blk_plug
*plug
;
1920 struct request
*same_queue_rq
= NULL
;
1923 blk_queue_bounce(q
, &bio
);
1925 blk_queue_split(q
, &bio
);
1927 if (!bio_integrity_prep(bio
))
1928 return BLK_QC_T_NONE
;
1930 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1931 blk_attempt_plug_merge(q
, bio
, &same_queue_rq
))
1932 return BLK_QC_T_NONE
;
1934 if (blk_mq_sched_bio_merge(q
, bio
))
1935 return BLK_QC_T_NONE
;
1937 rq_qos_throttle(q
, bio
);
1939 rq
= blk_mq_get_request(q
, bio
, &data
);
1940 if (unlikely(!rq
)) {
1941 rq_qos_cleanup(q
, bio
);
1942 if (bio
->bi_opf
& REQ_NOWAIT
)
1943 bio_wouldblock_error(bio
);
1944 return BLK_QC_T_NONE
;
1947 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1949 rq_qos_track(q
, rq
, bio
);
1951 cookie
= request_to_qc_t(data
.hctx
, rq
);
1953 plug
= current
->plug
;
1954 if (unlikely(is_flush_fua
)) {
1955 blk_mq_put_ctx(data
.ctx
);
1956 blk_mq_bio_to_request(rq
, bio
);
1958 /* bypass scheduler for flush rq */
1959 blk_insert_flush(rq
);
1960 blk_mq_run_hw_queue(data
.hctx
, true);
1961 } else if (plug
&& (q
->nr_hw_queues
== 1 || q
->mq_ops
->commit_rqs
)) {
1963 * Use plugging if we have a ->commit_rqs() hook as well, as
1964 * we know the driver uses bd->last in a smart fashion.
1966 unsigned int request_count
= plug
->rq_count
;
1967 struct request
*last
= NULL
;
1969 blk_mq_put_ctx(data
.ctx
);
1970 blk_mq_bio_to_request(rq
, bio
);
1973 trace_block_plug(q
);
1975 last
= list_entry_rq(plug
->mq_list
.prev
);
1977 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1978 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1979 blk_flush_plug_list(plug
, false);
1980 trace_block_plug(q
);
1983 blk_add_rq_to_plug(plug
, rq
);
1984 } else if (plug
&& !blk_queue_nomerges(q
)) {
1985 blk_mq_bio_to_request(rq
, bio
);
1988 * We do limited plugging. If the bio can be merged, do that.
1989 * Otherwise the existing request in the plug list will be
1990 * issued. So the plug list will have one request at most
1991 * The plug list might get flushed before this. If that happens,
1992 * the plug list is empty, and same_queue_rq is invalid.
1994 if (list_empty(&plug
->mq_list
))
1995 same_queue_rq
= NULL
;
1996 if (same_queue_rq
) {
1997 list_del_init(&same_queue_rq
->queuelist
);
2000 blk_add_rq_to_plug(plug
, rq
);
2002 blk_mq_put_ctx(data
.ctx
);
2004 if (same_queue_rq
) {
2005 data
.hctx
= same_queue_rq
->mq_hctx
;
2006 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2009 } else if ((q
->nr_hw_queues
> 1 && is_sync
) || (!q
->elevator
&&
2010 !data
.hctx
->dispatch_busy
)) {
2011 blk_mq_put_ctx(data
.ctx
);
2012 blk_mq_bio_to_request(rq
, bio
);
2013 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
2015 blk_mq_put_ctx(data
.ctx
);
2016 blk_mq_bio_to_request(rq
, bio
);
2017 blk_mq_sched_insert_request(rq
, false, true, true);
2023 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2024 unsigned int hctx_idx
)
2028 if (tags
->rqs
&& set
->ops
->exit_request
) {
2031 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2032 struct request
*rq
= tags
->static_rqs
[i
];
2036 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2037 tags
->static_rqs
[i
] = NULL
;
2041 while (!list_empty(&tags
->page_list
)) {
2042 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2043 list_del_init(&page
->lru
);
2045 * Remove kmemleak object previously allocated in
2046 * blk_mq_init_rq_map().
2048 kmemleak_free(page_address(page
));
2049 __free_pages(page
, page
->private);
2053 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
2057 kfree(tags
->static_rqs
);
2058 tags
->static_rqs
= NULL
;
2060 blk_mq_free_tags(tags
);
2063 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2064 unsigned int hctx_idx
,
2065 unsigned int nr_tags
,
2066 unsigned int reserved_tags
)
2068 struct blk_mq_tags
*tags
;
2071 node
= blk_mq_hw_queue_to_node(&set
->map
[0], hctx_idx
);
2072 if (node
== NUMA_NO_NODE
)
2073 node
= set
->numa_node
;
2075 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
2076 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
2080 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2081 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2084 blk_mq_free_tags(tags
);
2088 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2089 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2091 if (!tags
->static_rqs
) {
2093 blk_mq_free_tags(tags
);
2100 static size_t order_to_size(unsigned int order
)
2102 return (size_t)PAGE_SIZE
<< order
;
2105 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2106 unsigned int hctx_idx
, int node
)
2110 if (set
->ops
->init_request
) {
2111 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2116 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2120 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2121 unsigned int hctx_idx
, unsigned int depth
)
2123 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2124 size_t rq_size
, left
;
2127 node
= blk_mq_hw_queue_to_node(&set
->map
[0], hctx_idx
);
2128 if (node
== NUMA_NO_NODE
)
2129 node
= set
->numa_node
;
2131 INIT_LIST_HEAD(&tags
->page_list
);
2134 * rq_size is the size of the request plus driver payload, rounded
2135 * to the cacheline size
2137 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2139 left
= rq_size
* depth
;
2141 for (i
= 0; i
< depth
; ) {
2142 int this_order
= max_order
;
2147 while (this_order
&& left
< order_to_size(this_order
- 1))
2151 page
= alloc_pages_node(node
,
2152 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2158 if (order_to_size(this_order
) < rq_size
)
2165 page
->private = this_order
;
2166 list_add_tail(&page
->lru
, &tags
->page_list
);
2168 p
= page_address(page
);
2170 * Allow kmemleak to scan these pages as they contain pointers
2171 * to additional allocations like via ops->init_request().
2173 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2174 entries_per_page
= order_to_size(this_order
) / rq_size
;
2175 to_do
= min(entries_per_page
, depth
- i
);
2176 left
-= to_do
* rq_size
;
2177 for (j
= 0; j
< to_do
; j
++) {
2178 struct request
*rq
= p
;
2180 tags
->static_rqs
[i
] = rq
;
2181 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2182 tags
->static_rqs
[i
] = NULL
;
2193 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2198 * 'cpu' is going away. splice any existing rq_list entries from this
2199 * software queue to the hw queue dispatch list, and ensure that it
2202 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2204 struct blk_mq_hw_ctx
*hctx
;
2205 struct blk_mq_ctx
*ctx
;
2208 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2209 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2211 spin_lock(&ctx
->lock
);
2212 if (!list_empty(&ctx
->rq_list
)) {
2213 list_splice_init(&ctx
->rq_list
, &tmp
);
2214 blk_mq_hctx_clear_pending(hctx
, ctx
);
2216 spin_unlock(&ctx
->lock
);
2218 if (list_empty(&tmp
))
2221 spin_lock(&hctx
->lock
);
2222 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2223 spin_unlock(&hctx
->lock
);
2225 blk_mq_run_hw_queue(hctx
, true);
2229 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2231 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2235 /* hctx->ctxs will be freed in queue's release handler */
2236 static void blk_mq_exit_hctx(struct request_queue
*q
,
2237 struct blk_mq_tag_set
*set
,
2238 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2240 if (blk_mq_hw_queue_mapped(hctx
))
2241 blk_mq_tag_idle(hctx
);
2243 if (set
->ops
->exit_request
)
2244 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2246 if (set
->ops
->exit_hctx
)
2247 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2249 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2250 cleanup_srcu_struct(hctx
->srcu
);
2252 blk_mq_remove_cpuhp(hctx
);
2253 blk_free_flush_queue(hctx
->fq
);
2254 sbitmap_free(&hctx
->ctx_map
);
2257 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2258 struct blk_mq_tag_set
*set
, int nr_queue
)
2260 struct blk_mq_hw_ctx
*hctx
;
2263 queue_for_each_hw_ctx(q
, hctx
, i
) {
2266 blk_mq_debugfs_unregister_hctx(hctx
);
2267 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2271 static int blk_mq_init_hctx(struct request_queue
*q
,
2272 struct blk_mq_tag_set
*set
,
2273 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2277 node
= hctx
->numa_node
;
2278 if (node
== NUMA_NO_NODE
)
2279 node
= hctx
->numa_node
= set
->numa_node
;
2281 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2282 spin_lock_init(&hctx
->lock
);
2283 INIT_LIST_HEAD(&hctx
->dispatch
);
2285 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2287 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2289 hctx
->tags
= set
->tags
[hctx_idx
];
2292 * Allocate space for all possible cpus to avoid allocation at
2295 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2296 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
, node
);
2298 goto unregister_cpu_notifier
;
2300 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2301 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
, node
))
2306 spin_lock_init(&hctx
->dispatch_wait_lock
);
2307 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2308 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2310 if (set
->ops
->init_hctx
&&
2311 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2314 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
,
2315 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
2319 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
, node
))
2322 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2323 init_srcu_struct(hctx
->srcu
);
2330 if (set
->ops
->exit_hctx
)
2331 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2333 sbitmap_free(&hctx
->ctx_map
);
2336 unregister_cpu_notifier
:
2337 blk_mq_remove_cpuhp(hctx
);
2341 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2342 unsigned int nr_hw_queues
)
2344 struct blk_mq_tag_set
*set
= q
->tag_set
;
2347 for_each_possible_cpu(i
) {
2348 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2349 struct blk_mq_hw_ctx
*hctx
;
2352 spin_lock_init(&__ctx
->lock
);
2353 INIT_LIST_HEAD(&__ctx
->rq_list
);
2357 * Set local node, IFF we have more than one hw queue. If
2358 * not, we remain on the home node of the device
2360 for (j
= 0; j
< set
->nr_maps
; j
++) {
2361 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2362 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2363 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2368 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2372 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2373 set
->queue_depth
, set
->reserved_tags
);
2374 if (!set
->tags
[hctx_idx
])
2377 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2382 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2383 set
->tags
[hctx_idx
] = NULL
;
2387 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2388 unsigned int hctx_idx
)
2390 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2391 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2392 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2393 set
->tags
[hctx_idx
] = NULL
;
2397 static void blk_mq_map_swqueue(struct request_queue
*q
)
2399 unsigned int i
, j
, hctx_idx
;
2400 struct blk_mq_hw_ctx
*hctx
;
2401 struct blk_mq_ctx
*ctx
;
2402 struct blk_mq_tag_set
*set
= q
->tag_set
;
2405 * Avoid others reading imcomplete hctx->cpumask through sysfs
2407 mutex_lock(&q
->sysfs_lock
);
2409 queue_for_each_hw_ctx(q
, hctx
, i
) {
2410 cpumask_clear(hctx
->cpumask
);
2412 hctx
->dispatch_from
= NULL
;
2416 * Map software to hardware queues.
2418 * If the cpu isn't present, the cpu is mapped to first hctx.
2420 for_each_possible_cpu(i
) {
2421 hctx_idx
= set
->map
[0].mq_map
[i
];
2422 /* unmapped hw queue can be remapped after CPU topo changed */
2423 if (!set
->tags
[hctx_idx
] &&
2424 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2426 * If tags initialization fail for some hctx,
2427 * that hctx won't be brought online. In this
2428 * case, remap the current ctx to hctx[0] which
2429 * is guaranteed to always have tags allocated
2431 set
->map
[0].mq_map
[i
] = 0;
2434 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2435 for (j
= 0; j
< set
->nr_maps
; j
++) {
2436 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2439 * If the CPU is already set in the mask, then we've
2440 * mapped this one already. This can happen if
2441 * devices share queues across queue maps.
2443 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2446 cpumask_set_cpu(i
, hctx
->cpumask
);
2448 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2449 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2452 * If the nr_ctx type overflows, we have exceeded the
2453 * amount of sw queues we can support.
2455 BUG_ON(!hctx
->nr_ctx
);
2459 mutex_unlock(&q
->sysfs_lock
);
2461 queue_for_each_hw_ctx(q
, hctx
, i
) {
2463 * If no software queues are mapped to this hardware queue,
2464 * disable it and free the request entries.
2466 if (!hctx
->nr_ctx
) {
2467 /* Never unmap queue 0. We need it as a
2468 * fallback in case of a new remap fails
2471 if (i
&& set
->tags
[i
])
2472 blk_mq_free_map_and_requests(set
, i
);
2478 hctx
->tags
= set
->tags
[i
];
2479 WARN_ON(!hctx
->tags
);
2482 * Set the map size to the number of mapped software queues.
2483 * This is more accurate and more efficient than looping
2484 * over all possibly mapped software queues.
2486 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2489 * Initialize batch roundrobin counts
2491 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2492 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2497 * Caller needs to ensure that we're either frozen/quiesced, or that
2498 * the queue isn't live yet.
2500 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2502 struct blk_mq_hw_ctx
*hctx
;
2505 queue_for_each_hw_ctx(q
, hctx
, i
) {
2507 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2509 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2513 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2516 struct request_queue
*q
;
2518 lockdep_assert_held(&set
->tag_list_lock
);
2520 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2521 blk_mq_freeze_queue(q
);
2522 queue_set_hctx_shared(q
, shared
);
2523 blk_mq_unfreeze_queue(q
);
2527 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2529 struct blk_mq_tag_set
*set
= q
->tag_set
;
2531 mutex_lock(&set
->tag_list_lock
);
2532 list_del_rcu(&q
->tag_set_list
);
2533 if (list_is_singular(&set
->tag_list
)) {
2534 /* just transitioned to unshared */
2535 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2536 /* update existing queue */
2537 blk_mq_update_tag_set_depth(set
, false);
2539 mutex_unlock(&set
->tag_list_lock
);
2540 INIT_LIST_HEAD(&q
->tag_set_list
);
2543 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2544 struct request_queue
*q
)
2546 mutex_lock(&set
->tag_list_lock
);
2549 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2551 if (!list_empty(&set
->tag_list
) &&
2552 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2553 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2554 /* update existing queue */
2555 blk_mq_update_tag_set_depth(set
, true);
2557 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2558 queue_set_hctx_shared(q
, true);
2559 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2561 mutex_unlock(&set
->tag_list_lock
);
2564 /* All allocations will be freed in release handler of q->mq_kobj */
2565 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
2567 struct blk_mq_ctxs
*ctxs
;
2570 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
2574 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2575 if (!ctxs
->queue_ctx
)
2578 for_each_possible_cpu(cpu
) {
2579 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
2583 q
->mq_kobj
= &ctxs
->kobj
;
2584 q
->queue_ctx
= ctxs
->queue_ctx
;
2593 * It is the actual release handler for mq, but we do it from
2594 * request queue's release handler for avoiding use-after-free
2595 * and headache because q->mq_kobj shouldn't have been introduced,
2596 * but we can't group ctx/kctx kobj without it.
2598 void blk_mq_release(struct request_queue
*q
)
2600 struct blk_mq_hw_ctx
*hctx
;
2603 /* hctx kobj stays in hctx */
2604 queue_for_each_hw_ctx(q
, hctx
, i
) {
2607 kobject_put(&hctx
->kobj
);
2610 kfree(q
->queue_hw_ctx
);
2613 * release .mq_kobj and sw queue's kobject now because
2614 * both share lifetime with request queue.
2616 blk_mq_sysfs_deinit(q
);
2619 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2621 struct request_queue
*uninit_q
, *q
;
2623 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2625 return ERR_PTR(-ENOMEM
);
2627 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2629 blk_cleanup_queue(uninit_q
);
2633 EXPORT_SYMBOL(blk_mq_init_queue
);
2636 * Helper for setting up a queue with mq ops, given queue depth, and
2637 * the passed in mq ops flags.
2639 struct request_queue
*blk_mq_init_sq_queue(struct blk_mq_tag_set
*set
,
2640 const struct blk_mq_ops
*ops
,
2641 unsigned int queue_depth
,
2642 unsigned int set_flags
)
2644 struct request_queue
*q
;
2647 memset(set
, 0, sizeof(*set
));
2649 set
->nr_hw_queues
= 1;
2651 set
->queue_depth
= queue_depth
;
2652 set
->numa_node
= NUMA_NO_NODE
;
2653 set
->flags
= set_flags
;
2655 ret
= blk_mq_alloc_tag_set(set
);
2657 return ERR_PTR(ret
);
2659 q
= blk_mq_init_queue(set
);
2661 blk_mq_free_tag_set(set
);
2667 EXPORT_SYMBOL(blk_mq_init_sq_queue
);
2669 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2671 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2673 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2674 __alignof__(struct blk_mq_hw_ctx
)) !=
2675 sizeof(struct blk_mq_hw_ctx
));
2677 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2678 hw_ctx_size
+= sizeof(struct srcu_struct
);
2683 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
2684 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
2685 int hctx_idx
, int node
)
2687 struct blk_mq_hw_ctx
*hctx
;
2689 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
),
2690 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2695 if (!zalloc_cpumask_var_node(&hctx
->cpumask
,
2696 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2702 atomic_set(&hctx
->nr_active
, 0);
2703 hctx
->numa_node
= node
;
2704 hctx
->queue_num
= hctx_idx
;
2706 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
)) {
2707 free_cpumask_var(hctx
->cpumask
);
2711 blk_mq_hctx_kobj_init(hctx
);
2716 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2717 struct request_queue
*q
)
2720 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2722 /* protect against switching io scheduler */
2723 mutex_lock(&q
->sysfs_lock
);
2724 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2726 struct blk_mq_hw_ctx
*hctx
;
2728 node
= blk_mq_hw_queue_to_node(&set
->map
[0], i
);
2730 * If the hw queue has been mapped to another numa node,
2731 * we need to realloc the hctx. If allocation fails, fallback
2732 * to use the previous one.
2734 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
2737 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
2740 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
2741 kobject_put(&hctxs
[i
]->kobj
);
2746 pr_warn("Allocate new hctx on node %d fails,\
2747 fallback to previous one on node %d\n",
2748 node
, hctxs
[i
]->numa_node
);
2754 * Increasing nr_hw_queues fails. Free the newly allocated
2755 * hctxs and keep the previous q->nr_hw_queues.
2757 if (i
!= set
->nr_hw_queues
) {
2758 j
= q
->nr_hw_queues
;
2762 end
= q
->nr_hw_queues
;
2763 q
->nr_hw_queues
= set
->nr_hw_queues
;
2766 for (; j
< end
; j
++) {
2767 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2771 blk_mq_free_map_and_requests(set
, j
);
2772 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2773 kobject_put(&hctx
->kobj
);
2778 mutex_unlock(&q
->sysfs_lock
);
2782 * Maximum number of hardware queues we support. For single sets, we'll never
2783 * have more than the CPUs (software queues). For multiple sets, the tag_set
2784 * user may have set ->nr_hw_queues larger.
2786 static unsigned int nr_hw_queues(struct blk_mq_tag_set
*set
)
2788 if (set
->nr_maps
== 1)
2791 return max(set
->nr_hw_queues
, nr_cpu_ids
);
2794 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2795 struct request_queue
*q
)
2797 /* mark the queue as mq asap */
2798 q
->mq_ops
= set
->ops
;
2800 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2801 blk_mq_poll_stats_bkt
,
2802 BLK_MQ_POLL_STATS_BKTS
, q
);
2806 if (blk_mq_alloc_ctxs(q
))
2809 /* init q->mq_kobj and sw queues' kobjects */
2810 blk_mq_sysfs_init(q
);
2812 q
->nr_queues
= nr_hw_queues(set
);
2813 q
->queue_hw_ctx
= kcalloc_node(q
->nr_queues
, sizeof(*(q
->queue_hw_ctx
)),
2814 GFP_KERNEL
, set
->numa_node
);
2815 if (!q
->queue_hw_ctx
)
2818 blk_mq_realloc_hw_ctxs(set
, q
);
2819 if (!q
->nr_hw_queues
)
2822 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2823 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2827 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2828 if (set
->nr_maps
> HCTX_TYPE_POLL
)
2829 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
2831 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2832 blk_queue_flag_set(QUEUE_FLAG_NO_SG_MERGE
, q
);
2834 q
->sg_reserved_size
= INT_MAX
;
2836 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2837 INIT_LIST_HEAD(&q
->requeue_list
);
2838 spin_lock_init(&q
->requeue_lock
);
2840 blk_queue_make_request(q
, blk_mq_make_request
);
2843 * Do this after blk_queue_make_request() overrides it...
2845 q
->nr_requests
= set
->queue_depth
;
2848 * Default to classic polling
2852 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2853 blk_mq_add_queue_tag_set(set
, q
);
2854 blk_mq_map_swqueue(q
);
2856 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2859 ret
= elevator_init_mq(q
);
2861 return ERR_PTR(ret
);
2867 kfree(q
->queue_hw_ctx
);
2869 blk_mq_sysfs_deinit(q
);
2872 return ERR_PTR(-ENOMEM
);
2874 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2876 void blk_mq_free_queue(struct request_queue
*q
)
2878 struct blk_mq_tag_set
*set
= q
->tag_set
;
2880 blk_mq_del_queue_tag_set(q
);
2881 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2884 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2888 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2889 if (!__blk_mq_alloc_rq_map(set
, i
))
2896 blk_mq_free_rq_map(set
->tags
[i
]);
2902 * Allocate the request maps associated with this tag_set. Note that this
2903 * may reduce the depth asked for, if memory is tight. set->queue_depth
2904 * will be updated to reflect the allocated depth.
2906 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2911 depth
= set
->queue_depth
;
2913 err
= __blk_mq_alloc_rq_maps(set
);
2917 set
->queue_depth
>>= 1;
2918 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2922 } while (set
->queue_depth
);
2924 if (!set
->queue_depth
|| err
) {
2925 pr_err("blk-mq: failed to allocate request map\n");
2929 if (depth
!= set
->queue_depth
)
2930 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2931 depth
, set
->queue_depth
);
2936 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2938 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
2942 * transport .map_queues is usually done in the following
2945 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2946 * mask = get_cpu_mask(queue)
2947 * for_each_cpu(cpu, mask)
2948 * set->map[x].mq_map[cpu] = queue;
2951 * When we need to remap, the table has to be cleared for
2952 * killing stale mapping since one CPU may not be mapped
2955 for (i
= 0; i
< set
->nr_maps
; i
++)
2956 blk_mq_clear_mq_map(&set
->map
[i
]);
2958 return set
->ops
->map_queues(set
);
2960 BUG_ON(set
->nr_maps
> 1);
2961 return blk_mq_map_queues(&set
->map
[0]);
2966 * Alloc a tag set to be associated with one or more request queues.
2967 * May fail with EINVAL for various error conditions. May adjust the
2968 * requested depth down, if it's too large. In that case, the set
2969 * value will be stored in set->queue_depth.
2971 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2975 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2977 if (!set
->nr_hw_queues
)
2979 if (!set
->queue_depth
)
2981 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2984 if (!set
->ops
->queue_rq
)
2987 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
2990 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2991 pr_info("blk-mq: reduced tag depth to %u\n",
2993 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2998 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3002 * If a crashdump is active, then we are potentially in a very
3003 * memory constrained environment. Limit us to 1 queue and
3004 * 64 tags to prevent using too much memory.
3006 if (is_kdump_kernel()) {
3007 set
->nr_hw_queues
= 1;
3009 set
->queue_depth
= min(64U, set
->queue_depth
);
3012 * There is no use for more h/w queues than cpus if we just have
3015 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3016 set
->nr_hw_queues
= nr_cpu_ids
;
3018 set
->tags
= kcalloc_node(nr_hw_queues(set
), sizeof(struct blk_mq_tags
*),
3019 GFP_KERNEL
, set
->numa_node
);
3024 for (i
= 0; i
< set
->nr_maps
; i
++) {
3025 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3026 sizeof(struct blk_mq_queue_map
),
3027 GFP_KERNEL
, set
->numa_node
);
3028 if (!set
->map
[i
].mq_map
)
3029 goto out_free_mq_map
;
3030 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3033 ret
= blk_mq_update_queue_map(set
);
3035 goto out_free_mq_map
;
3037 ret
= blk_mq_alloc_rq_maps(set
);
3039 goto out_free_mq_map
;
3041 mutex_init(&set
->tag_list_lock
);
3042 INIT_LIST_HEAD(&set
->tag_list
);
3047 for (i
= 0; i
< set
->nr_maps
; i
++) {
3048 kfree(set
->map
[i
].mq_map
);
3049 set
->map
[i
].mq_map
= NULL
;
3055 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3057 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3061 for (i
= 0; i
< nr_hw_queues(set
); i
++)
3062 blk_mq_free_map_and_requests(set
, i
);
3064 for (j
= 0; j
< set
->nr_maps
; j
++) {
3065 kfree(set
->map
[j
].mq_map
);
3066 set
->map
[j
].mq_map
= NULL
;
3072 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3074 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3076 struct blk_mq_tag_set
*set
= q
->tag_set
;
3077 struct blk_mq_hw_ctx
*hctx
;
3083 blk_mq_freeze_queue(q
);
3084 blk_mq_quiesce_queue(q
);
3087 queue_for_each_hw_ctx(q
, hctx
, i
) {
3091 * If we're using an MQ scheduler, just update the scheduler
3092 * queue depth. This is similar to what the old code would do.
3094 if (!hctx
->sched_tags
) {
3095 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3098 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3106 q
->nr_requests
= nr
;
3108 blk_mq_unquiesce_queue(q
);
3109 blk_mq_unfreeze_queue(q
);
3115 * request_queue and elevator_type pair.
3116 * It is just used by __blk_mq_update_nr_hw_queues to cache
3117 * the elevator_type associated with a request_queue.
3119 struct blk_mq_qe_pair
{
3120 struct list_head node
;
3121 struct request_queue
*q
;
3122 struct elevator_type
*type
;
3126 * Cache the elevator_type in qe pair list and switch the
3127 * io scheduler to 'none'
3129 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3130 struct request_queue
*q
)
3132 struct blk_mq_qe_pair
*qe
;
3137 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3141 INIT_LIST_HEAD(&qe
->node
);
3143 qe
->type
= q
->elevator
->type
;
3144 list_add(&qe
->node
, head
);
3146 mutex_lock(&q
->sysfs_lock
);
3148 * After elevator_switch_mq, the previous elevator_queue will be
3149 * released by elevator_release. The reference of the io scheduler
3150 * module get by elevator_get will also be put. So we need to get
3151 * a reference of the io scheduler module here to prevent it to be
3154 __module_get(qe
->type
->elevator_owner
);
3155 elevator_switch_mq(q
, NULL
);
3156 mutex_unlock(&q
->sysfs_lock
);
3161 static void blk_mq_elv_switch_back(struct list_head
*head
,
3162 struct request_queue
*q
)
3164 struct blk_mq_qe_pair
*qe
;
3165 struct elevator_type
*t
= NULL
;
3167 list_for_each_entry(qe
, head
, node
)
3176 list_del(&qe
->node
);
3179 mutex_lock(&q
->sysfs_lock
);
3180 elevator_switch_mq(q
, t
);
3181 mutex_unlock(&q
->sysfs_lock
);
3184 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3187 struct request_queue
*q
;
3189 int prev_nr_hw_queues
;
3191 lockdep_assert_held(&set
->tag_list_lock
);
3193 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3194 nr_hw_queues
= nr_cpu_ids
;
3195 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
3198 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3199 blk_mq_freeze_queue(q
);
3201 * Sync with blk_mq_queue_tag_busy_iter.
3205 * Switch IO scheduler to 'none', cleaning up the data associated
3206 * with the previous scheduler. We will switch back once we are done
3207 * updating the new sw to hw queue mappings.
3209 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3210 if (!blk_mq_elv_switch_none(&head
, q
))
3213 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3214 blk_mq_debugfs_unregister_hctxs(q
);
3215 blk_mq_sysfs_unregister(q
);
3218 prev_nr_hw_queues
= set
->nr_hw_queues
;
3219 set
->nr_hw_queues
= nr_hw_queues
;
3220 blk_mq_update_queue_map(set
);
3222 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3223 blk_mq_realloc_hw_ctxs(set
, q
);
3224 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3225 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3226 nr_hw_queues
, prev_nr_hw_queues
);
3227 set
->nr_hw_queues
= prev_nr_hw_queues
;
3228 blk_mq_map_queues(&set
->map
[0]);
3231 blk_mq_map_swqueue(q
);
3234 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3235 blk_mq_sysfs_register(q
);
3236 blk_mq_debugfs_register_hctxs(q
);
3240 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3241 blk_mq_elv_switch_back(&head
, q
);
3243 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3244 blk_mq_unfreeze_queue(q
);
3247 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3249 mutex_lock(&set
->tag_list_lock
);
3250 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3251 mutex_unlock(&set
->tag_list_lock
);
3253 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3255 /* Enable polling stats and return whether they were already enabled. */
3256 static bool blk_poll_stats_enable(struct request_queue
*q
)
3258 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3259 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3261 blk_stat_add_callback(q
, q
->poll_cb
);
3265 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3268 * We don't arm the callback if polling stats are not enabled or the
3269 * callback is already active.
3271 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3272 blk_stat_is_active(q
->poll_cb
))
3275 blk_stat_activate_msecs(q
->poll_cb
, 100);
3278 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3280 struct request_queue
*q
= cb
->data
;
3283 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3284 if (cb
->stat
[bucket
].nr_samples
)
3285 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3289 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3290 struct blk_mq_hw_ctx
*hctx
,
3293 unsigned long ret
= 0;
3297 * If stats collection isn't on, don't sleep but turn it on for
3300 if (!blk_poll_stats_enable(q
))
3304 * As an optimistic guess, use half of the mean service time
3305 * for this type of request. We can (and should) make this smarter.
3306 * For instance, if the completion latencies are tight, we can
3307 * get closer than just half the mean. This is especially
3308 * important on devices where the completion latencies are longer
3309 * than ~10 usec. We do use the stats for the relevant IO size
3310 * if available which does lead to better estimates.
3312 bucket
= blk_mq_poll_stats_bkt(rq
);
3316 if (q
->poll_stat
[bucket
].nr_samples
)
3317 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3322 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3323 struct blk_mq_hw_ctx
*hctx
,
3326 struct hrtimer_sleeper hs
;
3327 enum hrtimer_mode mode
;
3331 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3335 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3337 * 0: use half of prev avg
3338 * >0: use this specific value
3340 if (q
->poll_nsec
> 0)
3341 nsecs
= q
->poll_nsec
;
3343 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
3348 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3351 * This will be replaced with the stats tracking code, using
3352 * 'avg_completion_time / 2' as the pre-sleep target.
3356 mode
= HRTIMER_MODE_REL
;
3357 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
3358 hrtimer_set_expires(&hs
.timer
, kt
);
3360 hrtimer_init_sleeper(&hs
, current
);
3362 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3364 set_current_state(TASK_UNINTERRUPTIBLE
);
3365 hrtimer_start_expires(&hs
.timer
, mode
);
3368 hrtimer_cancel(&hs
.timer
);
3369 mode
= HRTIMER_MODE_ABS
;
3370 } while (hs
.task
&& !signal_pending(current
));
3372 __set_current_state(TASK_RUNNING
);
3373 destroy_hrtimer_on_stack(&hs
.timer
);
3377 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3378 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3382 if (q
->poll_nsec
== -1)
3385 if (!blk_qc_t_is_internal(cookie
))
3386 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3388 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3390 * With scheduling, if the request has completed, we'll
3391 * get a NULL return here, as we clear the sched tag when
3392 * that happens. The request still remains valid, like always,
3393 * so we should be safe with just the NULL check.
3399 return blk_mq_poll_hybrid_sleep(q
, hctx
, rq
);
3403 * blk_poll - poll for IO completions
3405 * @cookie: cookie passed back at IO submission time
3406 * @spin: whether to spin for completions
3409 * Poll for completions on the passed in queue. Returns number of
3410 * completed entries found. If @spin is true, then blk_poll will continue
3411 * looping until at least one completion is found, unless the task is
3412 * otherwise marked running (or we need to reschedule).
3414 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3416 struct blk_mq_hw_ctx
*hctx
;
3419 if (!blk_qc_t_valid(cookie
) ||
3420 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3424 blk_flush_plug_list(current
->plug
, false);
3426 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3429 * If we sleep, have the caller restart the poll loop to reset
3430 * the state. Like for the other success return cases, the
3431 * caller is responsible for checking if the IO completed. If
3432 * the IO isn't complete, we'll get called again and will go
3433 * straight to the busy poll loop.
3435 if (blk_mq_poll_hybrid(q
, hctx
, cookie
))
3438 hctx
->poll_considered
++;
3440 state
= current
->state
;
3444 hctx
->poll_invoked
++;
3446 ret
= q
->mq_ops
->poll(hctx
);
3448 hctx
->poll_success
++;
3449 __set_current_state(TASK_RUNNING
);
3453 if (signal_pending_state(state
, current
))
3454 __set_current_state(TASK_RUNNING
);
3456 if (current
->state
== TASK_RUNNING
)
3458 if (ret
< 0 || !spin
)
3461 } while (!need_resched());
3463 __set_current_state(TASK_RUNNING
);
3466 EXPORT_SYMBOL_GPL(blk_poll
);
3468 unsigned int blk_mq_rq_cpu(struct request
*rq
)
3470 return rq
->mq_ctx
->cpu
;
3472 EXPORT_SYMBOL(blk_mq_rq_cpu
);
3474 static int __init
blk_mq_init(void)
3476 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3477 blk_mq_hctx_notify_dead
);
3480 subsys_initcall(blk_mq_init
);