gpio: of: Reflect decoupling of open collector and active low/high
[linux/fpc-iii.git] / block / blk-mq.c
bloba69ad122ed66c6b93385f1b3959a893b407b9d05
1 /*
2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
6 */
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>
13 #include <linux/mm.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>
32 #include "blk.h"
33 #include "blk-mq.h"
34 #include "blk-mq-debugfs.h"
35 #include "blk-mq-tag.h"
36 #include "blk-stat.h"
37 #include "blk-wbt.h"
38 #include "blk-mq-sched.h"
40 static DEFINE_MUTEX(all_q_mutex);
41 static LIST_HEAD(all_q_list);
43 static void blk_mq_poll_stats_start(struct request_queue *q);
44 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
45 static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync);
47 static int blk_mq_poll_stats_bkt(const struct request *rq)
49 int ddir, bytes, bucket;
51 ddir = rq_data_dir(rq);
52 bytes = blk_rq_bytes(rq);
54 bucket = ddir + 2*(ilog2(bytes) - 9);
56 if (bucket < 0)
57 return -1;
58 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
59 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
61 return bucket;
65 * Check if any of the ctx's have pending work in this hardware queue
67 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
69 return sbitmap_any_bit_set(&hctx->ctx_map) ||
70 !list_empty_careful(&hctx->dispatch) ||
71 blk_mq_sched_has_work(hctx);
75 * Mark this ctx as having pending work in this hardware queue
77 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
78 struct blk_mq_ctx *ctx)
80 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
81 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
84 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
85 struct blk_mq_ctx *ctx)
87 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
90 void blk_freeze_queue_start(struct request_queue *q)
92 int freeze_depth;
94 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
95 if (freeze_depth == 1) {
96 percpu_ref_kill(&q->q_usage_counter);
97 blk_mq_run_hw_queues(q, false);
100 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
102 void blk_mq_freeze_queue_wait(struct request_queue *q)
104 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
106 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
108 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
109 unsigned long timeout)
111 return wait_event_timeout(q->mq_freeze_wq,
112 percpu_ref_is_zero(&q->q_usage_counter),
113 timeout);
115 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
118 * Guarantee no request is in use, so we can change any data structure of
119 * the queue afterward.
121 void blk_freeze_queue(struct request_queue *q)
124 * In the !blk_mq case we are only calling this to kill the
125 * q_usage_counter, otherwise this increases the freeze depth
126 * and waits for it to return to zero. For this reason there is
127 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
128 * exported to drivers as the only user for unfreeze is blk_mq.
130 blk_freeze_queue_start(q);
131 blk_mq_freeze_queue_wait(q);
134 void blk_mq_freeze_queue(struct request_queue *q)
137 * ...just an alias to keep freeze and unfreeze actions balanced
138 * in the blk_mq_* namespace
140 blk_freeze_queue(q);
142 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
144 void blk_mq_unfreeze_queue(struct request_queue *q)
146 int freeze_depth;
148 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
149 WARN_ON_ONCE(freeze_depth < 0);
150 if (!freeze_depth) {
151 percpu_ref_reinit(&q->q_usage_counter);
152 wake_up_all(&q->mq_freeze_wq);
155 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
158 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
159 * @q: request queue.
161 * Note: this function does not prevent that the struct request end_io()
162 * callback function is invoked. Additionally, it is not prevented that
163 * new queue_rq() calls occur unless the queue has been stopped first.
165 void blk_mq_quiesce_queue(struct request_queue *q)
167 struct blk_mq_hw_ctx *hctx;
168 unsigned int i;
169 bool rcu = false;
171 __blk_mq_stop_hw_queues(q, true);
173 queue_for_each_hw_ctx(q, hctx, i) {
174 if (hctx->flags & BLK_MQ_F_BLOCKING)
175 synchronize_srcu(&hctx->queue_rq_srcu);
176 else
177 rcu = true;
179 if (rcu)
180 synchronize_rcu();
182 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
184 void blk_mq_wake_waiters(struct request_queue *q)
186 struct blk_mq_hw_ctx *hctx;
187 unsigned int i;
189 queue_for_each_hw_ctx(q, hctx, i)
190 if (blk_mq_hw_queue_mapped(hctx))
191 blk_mq_tag_wakeup_all(hctx->tags, true);
194 * If we are called because the queue has now been marked as
195 * dying, we need to ensure that processes currently waiting on
196 * the queue are notified as well.
198 wake_up_all(&q->mq_freeze_wq);
201 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
203 return blk_mq_has_free_tags(hctx->tags);
205 EXPORT_SYMBOL(blk_mq_can_queue);
207 void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
208 struct request *rq, unsigned int op)
210 INIT_LIST_HEAD(&rq->queuelist);
211 /* csd/requeue_work/fifo_time is initialized before use */
212 rq->q = q;
213 rq->mq_ctx = ctx;
214 rq->cmd_flags = op;
215 if (blk_queue_io_stat(q))
216 rq->rq_flags |= RQF_IO_STAT;
217 /* do not touch atomic flags, it needs atomic ops against the timer */
218 rq->cpu = -1;
219 INIT_HLIST_NODE(&rq->hash);
220 RB_CLEAR_NODE(&rq->rb_node);
221 rq->rq_disk = NULL;
222 rq->part = NULL;
223 rq->start_time = jiffies;
224 #ifdef CONFIG_BLK_CGROUP
225 rq->rl = NULL;
226 set_start_time_ns(rq);
227 rq->io_start_time_ns = 0;
228 #endif
229 rq->nr_phys_segments = 0;
230 #if defined(CONFIG_BLK_DEV_INTEGRITY)
231 rq->nr_integrity_segments = 0;
232 #endif
233 rq->special = NULL;
234 /* tag was already set */
235 rq->extra_len = 0;
237 INIT_LIST_HEAD(&rq->timeout_list);
238 rq->timeout = 0;
240 rq->end_io = NULL;
241 rq->end_io_data = NULL;
242 rq->next_rq = NULL;
244 ctx->rq_dispatched[op_is_sync(op)]++;
246 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
248 struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
249 unsigned int op)
251 struct request *rq;
252 unsigned int tag;
254 tag = blk_mq_get_tag(data);
255 if (tag != BLK_MQ_TAG_FAIL) {
256 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
258 rq = tags->static_rqs[tag];
260 if (data->flags & BLK_MQ_REQ_INTERNAL) {
261 rq->tag = -1;
262 rq->internal_tag = tag;
263 } else {
264 if (blk_mq_tag_busy(data->hctx)) {
265 rq->rq_flags = RQF_MQ_INFLIGHT;
266 atomic_inc(&data->hctx->nr_active);
268 rq->tag = tag;
269 rq->internal_tag = -1;
270 data->hctx->tags->rqs[rq->tag] = rq;
273 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
274 return rq;
277 return NULL;
279 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
281 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
282 unsigned int flags)
284 struct blk_mq_alloc_data alloc_data = { .flags = flags };
285 struct request *rq;
286 int ret;
288 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
289 if (ret)
290 return ERR_PTR(ret);
292 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
294 blk_mq_put_ctx(alloc_data.ctx);
295 blk_queue_exit(q);
297 if (!rq)
298 return ERR_PTR(-EWOULDBLOCK);
300 rq->__data_len = 0;
301 rq->__sector = (sector_t) -1;
302 rq->bio = rq->biotail = NULL;
303 return rq;
305 EXPORT_SYMBOL(blk_mq_alloc_request);
307 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
308 unsigned int flags, unsigned int hctx_idx)
310 struct blk_mq_alloc_data alloc_data = { .flags = flags };
311 struct request *rq;
312 unsigned int cpu;
313 int ret;
316 * If the tag allocator sleeps we could get an allocation for a
317 * different hardware context. No need to complicate the low level
318 * allocator for this for the rare use case of a command tied to
319 * a specific queue.
321 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
322 return ERR_PTR(-EINVAL);
324 if (hctx_idx >= q->nr_hw_queues)
325 return ERR_PTR(-EIO);
327 ret = blk_queue_enter(q, true);
328 if (ret)
329 return ERR_PTR(ret);
332 * Check if the hardware context is actually mapped to anything.
333 * If not tell the caller that it should skip this queue.
335 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
336 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
337 blk_queue_exit(q);
338 return ERR_PTR(-EXDEV);
340 cpu = cpumask_first(alloc_data.hctx->cpumask);
341 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
343 rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
345 blk_queue_exit(q);
347 if (!rq)
348 return ERR_PTR(-EWOULDBLOCK);
350 return rq;
352 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
354 void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
355 struct request *rq)
357 const int sched_tag = rq->internal_tag;
358 struct request_queue *q = rq->q;
360 if (rq->rq_flags & RQF_MQ_INFLIGHT)
361 atomic_dec(&hctx->nr_active);
363 wbt_done(q->rq_wb, &rq->issue_stat);
364 rq->rq_flags = 0;
366 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
367 clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
368 if (rq->tag != -1)
369 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
370 if (sched_tag != -1)
371 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
372 blk_mq_sched_restart(hctx);
373 blk_queue_exit(q);
376 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
377 struct request *rq)
379 struct blk_mq_ctx *ctx = rq->mq_ctx;
381 ctx->rq_completed[rq_is_sync(rq)]++;
382 __blk_mq_finish_request(hctx, ctx, rq);
385 void blk_mq_finish_request(struct request *rq)
387 blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
389 EXPORT_SYMBOL_GPL(blk_mq_finish_request);
391 void blk_mq_free_request(struct request *rq)
393 blk_mq_sched_put_request(rq);
395 EXPORT_SYMBOL_GPL(blk_mq_free_request);
397 inline void __blk_mq_end_request(struct request *rq, int error)
399 blk_account_io_done(rq);
401 if (rq->end_io) {
402 wbt_done(rq->q->rq_wb, &rq->issue_stat);
403 rq->end_io(rq, error);
404 } else {
405 if (unlikely(blk_bidi_rq(rq)))
406 blk_mq_free_request(rq->next_rq);
407 blk_mq_free_request(rq);
410 EXPORT_SYMBOL(__blk_mq_end_request);
412 void blk_mq_end_request(struct request *rq, int error)
414 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
415 BUG();
416 __blk_mq_end_request(rq, error);
418 EXPORT_SYMBOL(blk_mq_end_request);
420 static void __blk_mq_complete_request_remote(void *data)
422 struct request *rq = data;
424 rq->q->softirq_done_fn(rq);
427 static void __blk_mq_complete_request(struct request *rq)
429 struct blk_mq_ctx *ctx = rq->mq_ctx;
430 bool shared = false;
431 int cpu;
433 if (rq->internal_tag != -1)
434 blk_mq_sched_completed_request(rq);
435 if (rq->rq_flags & RQF_STATS) {
436 blk_mq_poll_stats_start(rq->q);
437 blk_stat_add(rq);
440 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
441 rq->q->softirq_done_fn(rq);
442 return;
445 cpu = get_cpu();
446 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
447 shared = cpus_share_cache(cpu, ctx->cpu);
449 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
450 rq->csd.func = __blk_mq_complete_request_remote;
451 rq->csd.info = rq;
452 rq->csd.flags = 0;
453 smp_call_function_single_async(ctx->cpu, &rq->csd);
454 } else {
455 rq->q->softirq_done_fn(rq);
457 put_cpu();
461 * blk_mq_complete_request - end I/O on a request
462 * @rq: the request being processed
464 * Description:
465 * Ends all I/O on a request. It does not handle partial completions.
466 * The actual completion happens out-of-order, through a IPI handler.
468 void blk_mq_complete_request(struct request *rq)
470 struct request_queue *q = rq->q;
472 if (unlikely(blk_should_fake_timeout(q)))
473 return;
474 if (!blk_mark_rq_complete(rq))
475 __blk_mq_complete_request(rq);
477 EXPORT_SYMBOL(blk_mq_complete_request);
479 int blk_mq_request_started(struct request *rq)
481 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
483 EXPORT_SYMBOL_GPL(blk_mq_request_started);
485 void blk_mq_start_request(struct request *rq)
487 struct request_queue *q = rq->q;
489 blk_mq_sched_started_request(rq);
491 trace_block_rq_issue(q, rq);
493 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
494 blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
495 rq->rq_flags |= RQF_STATS;
496 wbt_issue(q->rq_wb, &rq->issue_stat);
499 blk_add_timer(rq);
502 * Ensure that ->deadline is visible before set the started
503 * flag and clear the completed flag.
505 smp_mb__before_atomic();
508 * Mark us as started and clear complete. Complete might have been
509 * set if requeue raced with timeout, which then marked it as
510 * complete. So be sure to clear complete again when we start
511 * the request, otherwise we'll ignore the completion event.
513 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
514 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
515 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
516 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
518 if (q->dma_drain_size && blk_rq_bytes(rq)) {
520 * Make sure space for the drain appears. We know we can do
521 * this because max_hw_segments has been adjusted to be one
522 * fewer than the device can handle.
524 rq->nr_phys_segments++;
527 EXPORT_SYMBOL(blk_mq_start_request);
530 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
531 * flag isn't set yet, so there may be race with timeout handler,
532 * but given rq->deadline is just set in .queue_rq() under
533 * this situation, the race won't be possible in reality because
534 * rq->timeout should be set as big enough to cover the window
535 * between blk_mq_start_request() called from .queue_rq() and
536 * clearing REQ_ATOM_STARTED here.
538 static void __blk_mq_requeue_request(struct request *rq)
540 struct request_queue *q = rq->q;
542 trace_block_rq_requeue(q, rq);
543 wbt_requeue(q->rq_wb, &rq->issue_stat);
544 blk_mq_sched_requeue_request(rq);
546 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
547 if (q->dma_drain_size && blk_rq_bytes(rq))
548 rq->nr_phys_segments--;
552 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
554 __blk_mq_requeue_request(rq);
556 BUG_ON(blk_queued_rq(rq));
557 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
559 EXPORT_SYMBOL(blk_mq_requeue_request);
561 static void blk_mq_requeue_work(struct work_struct *work)
563 struct request_queue *q =
564 container_of(work, struct request_queue, requeue_work.work);
565 LIST_HEAD(rq_list);
566 struct request *rq, *next;
567 unsigned long flags;
569 spin_lock_irqsave(&q->requeue_lock, flags);
570 list_splice_init(&q->requeue_list, &rq_list);
571 spin_unlock_irqrestore(&q->requeue_lock, flags);
573 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
574 if (!(rq->rq_flags & RQF_SOFTBARRIER))
575 continue;
577 rq->rq_flags &= ~RQF_SOFTBARRIER;
578 list_del_init(&rq->queuelist);
579 blk_mq_sched_insert_request(rq, true, false, false, true);
582 while (!list_empty(&rq_list)) {
583 rq = list_entry(rq_list.next, struct request, queuelist);
584 list_del_init(&rq->queuelist);
585 blk_mq_sched_insert_request(rq, false, false, false, true);
588 blk_mq_run_hw_queues(q, false);
591 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
592 bool kick_requeue_list)
594 struct request_queue *q = rq->q;
595 unsigned long flags;
598 * We abuse this flag that is otherwise used by the I/O scheduler to
599 * request head insertation from the workqueue.
601 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
603 spin_lock_irqsave(&q->requeue_lock, flags);
604 if (at_head) {
605 rq->rq_flags |= RQF_SOFTBARRIER;
606 list_add(&rq->queuelist, &q->requeue_list);
607 } else {
608 list_add_tail(&rq->queuelist, &q->requeue_list);
610 spin_unlock_irqrestore(&q->requeue_lock, flags);
612 if (kick_requeue_list)
613 blk_mq_kick_requeue_list(q);
615 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
617 void blk_mq_kick_requeue_list(struct request_queue *q)
619 kblockd_schedule_delayed_work(&q->requeue_work, 0);
621 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
623 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
624 unsigned long msecs)
626 kblockd_schedule_delayed_work(&q->requeue_work,
627 msecs_to_jiffies(msecs));
629 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
631 void blk_mq_abort_requeue_list(struct request_queue *q)
633 unsigned long flags;
634 LIST_HEAD(rq_list);
636 spin_lock_irqsave(&q->requeue_lock, flags);
637 list_splice_init(&q->requeue_list, &rq_list);
638 spin_unlock_irqrestore(&q->requeue_lock, flags);
640 while (!list_empty(&rq_list)) {
641 struct request *rq;
643 rq = list_first_entry(&rq_list, struct request, queuelist);
644 list_del_init(&rq->queuelist);
645 blk_mq_end_request(rq, -EIO);
648 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
650 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
652 if (tag < tags->nr_tags) {
653 prefetch(tags->rqs[tag]);
654 return tags->rqs[tag];
657 return NULL;
659 EXPORT_SYMBOL(blk_mq_tag_to_rq);
661 struct blk_mq_timeout_data {
662 unsigned long next;
663 unsigned int next_set;
666 void blk_mq_rq_timed_out(struct request *req, bool reserved)
668 const struct blk_mq_ops *ops = req->q->mq_ops;
669 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
672 * We know that complete is set at this point. If STARTED isn't set
673 * anymore, then the request isn't active and the "timeout" should
674 * just be ignored. This can happen due to the bitflag ordering.
675 * Timeout first checks if STARTED is set, and if it is, assumes
676 * the request is active. But if we race with completion, then
677 * both flags will get cleared. So check here again, and ignore
678 * a timeout event with a request that isn't active.
680 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
681 return;
683 if (ops->timeout)
684 ret = ops->timeout(req, reserved);
686 switch (ret) {
687 case BLK_EH_HANDLED:
688 __blk_mq_complete_request(req);
689 break;
690 case BLK_EH_RESET_TIMER:
691 blk_add_timer(req);
692 blk_clear_rq_complete(req);
693 break;
694 case BLK_EH_NOT_HANDLED:
695 break;
696 default:
697 printk(KERN_ERR "block: bad eh return: %d\n", ret);
698 break;
702 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
703 struct request *rq, void *priv, bool reserved)
705 struct blk_mq_timeout_data *data = priv;
707 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
708 return;
711 * The rq being checked may have been freed and reallocated
712 * out already here, we avoid this race by checking rq->deadline
713 * and REQ_ATOM_COMPLETE flag together:
715 * - if rq->deadline is observed as new value because of
716 * reusing, the rq won't be timed out because of timing.
717 * - if rq->deadline is observed as previous value,
718 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
719 * because we put a barrier between setting rq->deadline
720 * and clearing the flag in blk_mq_start_request(), so
721 * this rq won't be timed out too.
723 if (time_after_eq(jiffies, rq->deadline)) {
724 if (!blk_mark_rq_complete(rq))
725 blk_mq_rq_timed_out(rq, reserved);
726 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
727 data->next = rq->deadline;
728 data->next_set = 1;
732 static void blk_mq_timeout_work(struct work_struct *work)
734 struct request_queue *q =
735 container_of(work, struct request_queue, timeout_work);
736 struct blk_mq_timeout_data data = {
737 .next = 0,
738 .next_set = 0,
740 int i;
742 /* A deadlock might occur if a request is stuck requiring a
743 * timeout at the same time a queue freeze is waiting
744 * completion, since the timeout code would not be able to
745 * acquire the queue reference here.
747 * That's why we don't use blk_queue_enter here; instead, we use
748 * percpu_ref_tryget directly, because we need to be able to
749 * obtain a reference even in the short window between the queue
750 * starting to freeze, by dropping the first reference in
751 * blk_freeze_queue_start, and the moment the last request is
752 * consumed, marked by the instant q_usage_counter reaches
753 * zero.
755 if (!percpu_ref_tryget(&q->q_usage_counter))
756 return;
758 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
760 if (data.next_set) {
761 data.next = blk_rq_timeout(round_jiffies_up(data.next));
762 mod_timer(&q->timeout, data.next);
763 } else {
764 struct blk_mq_hw_ctx *hctx;
766 queue_for_each_hw_ctx(q, hctx, i) {
767 /* the hctx may be unmapped, so check it here */
768 if (blk_mq_hw_queue_mapped(hctx))
769 blk_mq_tag_idle(hctx);
772 blk_queue_exit(q);
776 * Reverse check our software queue for entries that we could potentially
777 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
778 * too much time checking for merges.
780 static bool blk_mq_attempt_merge(struct request_queue *q,
781 struct blk_mq_ctx *ctx, struct bio *bio)
783 struct request *rq;
784 int checked = 8;
786 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
787 bool merged = false;
789 if (!checked--)
790 break;
792 if (!blk_rq_merge_ok(rq, bio))
793 continue;
795 switch (blk_try_merge(rq, bio)) {
796 case ELEVATOR_BACK_MERGE:
797 if (blk_mq_sched_allow_merge(q, rq, bio))
798 merged = bio_attempt_back_merge(q, rq, bio);
799 break;
800 case ELEVATOR_FRONT_MERGE:
801 if (blk_mq_sched_allow_merge(q, rq, bio))
802 merged = bio_attempt_front_merge(q, rq, bio);
803 break;
804 case ELEVATOR_DISCARD_MERGE:
805 merged = bio_attempt_discard_merge(q, rq, bio);
806 break;
807 default:
808 continue;
811 if (merged)
812 ctx->rq_merged++;
813 return merged;
816 return false;
819 struct flush_busy_ctx_data {
820 struct blk_mq_hw_ctx *hctx;
821 struct list_head *list;
824 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
826 struct flush_busy_ctx_data *flush_data = data;
827 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
828 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
830 sbitmap_clear_bit(sb, bitnr);
831 spin_lock(&ctx->lock);
832 list_splice_tail_init(&ctx->rq_list, flush_data->list);
833 spin_unlock(&ctx->lock);
834 return true;
838 * Process software queues that have been marked busy, splicing them
839 * to the for-dispatch
841 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
843 struct flush_busy_ctx_data data = {
844 .hctx = hctx,
845 .list = list,
848 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
850 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
852 static inline unsigned int queued_to_index(unsigned int queued)
854 if (!queued)
855 return 0;
857 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
860 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
861 bool wait)
863 struct blk_mq_alloc_data data = {
864 .q = rq->q,
865 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
866 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
869 might_sleep_if(wait);
871 if (rq->tag != -1)
872 goto done;
874 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
875 data.flags |= BLK_MQ_REQ_RESERVED;
877 rq->tag = blk_mq_get_tag(&data);
878 if (rq->tag >= 0) {
879 if (blk_mq_tag_busy(data.hctx)) {
880 rq->rq_flags |= RQF_MQ_INFLIGHT;
881 atomic_inc(&data.hctx->nr_active);
883 data.hctx->tags->rqs[rq->tag] = rq;
886 done:
887 if (hctx)
888 *hctx = data.hctx;
889 return rq->tag != -1;
892 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
893 struct request *rq)
895 blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
896 rq->tag = -1;
898 if (rq->rq_flags & RQF_MQ_INFLIGHT) {
899 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
900 atomic_dec(&hctx->nr_active);
904 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
905 struct request *rq)
907 if (rq->tag == -1 || rq->internal_tag == -1)
908 return;
910 __blk_mq_put_driver_tag(hctx, rq);
913 static void blk_mq_put_driver_tag(struct request *rq)
915 struct blk_mq_hw_ctx *hctx;
917 if (rq->tag == -1 || rq->internal_tag == -1)
918 return;
920 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
921 __blk_mq_put_driver_tag(hctx, rq);
925 * If we fail getting a driver tag because all the driver tags are already
926 * assigned and on the dispatch list, BUT the first entry does not have a
927 * tag, then we could deadlock. For that case, move entries with assigned
928 * driver tags to the front, leaving the set of tagged requests in the
929 * same order, and the untagged set in the same order.
931 static bool reorder_tags_to_front(struct list_head *list)
933 struct request *rq, *tmp, *first = NULL;
935 list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
936 if (rq == first)
937 break;
938 if (rq->tag != -1) {
939 list_move(&rq->queuelist, list);
940 if (!first)
941 first = rq;
945 return first != NULL;
948 static int blk_mq_dispatch_wake(wait_queue_t *wait, unsigned mode, int flags,
949 void *key)
951 struct blk_mq_hw_ctx *hctx;
953 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
955 list_del(&wait->task_list);
956 clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
957 blk_mq_run_hw_queue(hctx, true);
958 return 1;
961 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
963 struct sbq_wait_state *ws;
966 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
967 * The thread which wins the race to grab this bit adds the hardware
968 * queue to the wait queue.
970 if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
971 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
972 return false;
974 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
975 ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
978 * As soon as this returns, it's no longer safe to fiddle with
979 * hctx->dispatch_wait, since a completion can wake up the wait queue
980 * and unlock the bit.
982 add_wait_queue(&ws->wait, &hctx->dispatch_wait);
983 return true;
986 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
988 struct blk_mq_hw_ctx *hctx;
989 struct request *rq;
990 int errors, queued, ret = BLK_MQ_RQ_QUEUE_OK;
992 if (list_empty(list))
993 return false;
996 * Now process all the entries, sending them to the driver.
998 errors = queued = 0;
999 do {
1000 struct blk_mq_queue_data bd;
1002 rq = list_first_entry(list, struct request, queuelist);
1003 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
1004 if (!queued && reorder_tags_to_front(list))
1005 continue;
1008 * The initial allocation attempt failed, so we need to
1009 * rerun the hardware queue when a tag is freed.
1011 if (!blk_mq_dispatch_wait_add(hctx))
1012 break;
1015 * It's possible that a tag was freed in the window
1016 * between the allocation failure and adding the
1017 * hardware queue to the wait queue.
1019 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1020 break;
1023 list_del_init(&rq->queuelist);
1025 bd.rq = rq;
1028 * Flag last if we have no more requests, or if we have more
1029 * but can't assign a driver tag to it.
1031 if (list_empty(list))
1032 bd.last = true;
1033 else {
1034 struct request *nxt;
1036 nxt = list_first_entry(list, struct request, queuelist);
1037 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1040 ret = q->mq_ops->queue_rq(hctx, &bd);
1041 switch (ret) {
1042 case BLK_MQ_RQ_QUEUE_OK:
1043 queued++;
1044 break;
1045 case BLK_MQ_RQ_QUEUE_BUSY:
1046 blk_mq_put_driver_tag_hctx(hctx, rq);
1047 list_add(&rq->queuelist, list);
1048 __blk_mq_requeue_request(rq);
1049 break;
1050 default:
1051 pr_err("blk-mq: bad return on queue: %d\n", ret);
1052 case BLK_MQ_RQ_QUEUE_ERROR:
1053 errors++;
1054 blk_mq_end_request(rq, -EIO);
1055 break;
1058 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
1059 break;
1060 } while (!list_empty(list));
1062 hctx->dispatched[queued_to_index(queued)]++;
1065 * Any items that need requeuing? Stuff them into hctx->dispatch,
1066 * that is where we will continue on next queue run.
1068 if (!list_empty(list)) {
1070 * If an I/O scheduler has been configured and we got a driver
1071 * tag for the next request already, free it again.
1073 rq = list_first_entry(list, struct request, queuelist);
1074 blk_mq_put_driver_tag(rq);
1076 spin_lock(&hctx->lock);
1077 list_splice_init(list, &hctx->dispatch);
1078 spin_unlock(&hctx->lock);
1081 * If SCHED_RESTART was set by the caller of this function and
1082 * it is no longer set that means that it was cleared by another
1083 * thread and hence that a queue rerun is needed.
1085 * If TAG_WAITING is set that means that an I/O scheduler has
1086 * been configured and another thread is waiting for a driver
1087 * tag. To guarantee fairness, do not rerun this hardware queue
1088 * but let the other thread grab the driver tag.
1090 * If no I/O scheduler has been configured it is possible that
1091 * the hardware queue got stopped and restarted before requests
1092 * were pushed back onto the dispatch list. Rerun the queue to
1093 * avoid starvation. Notes:
1094 * - blk_mq_run_hw_queue() checks whether or not a queue has
1095 * been stopped before rerunning a queue.
1096 * - Some but not all block drivers stop a queue before
1097 * returning BLK_MQ_RQ_QUEUE_BUSY. Two exceptions are scsi-mq
1098 * and dm-rq.
1100 if (!blk_mq_sched_needs_restart(hctx) &&
1101 !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1102 blk_mq_run_hw_queue(hctx, true);
1105 return (queued + errors) != 0;
1108 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1110 int srcu_idx;
1112 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1113 cpu_online(hctx->next_cpu));
1115 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1116 rcu_read_lock();
1117 blk_mq_sched_dispatch_requests(hctx);
1118 rcu_read_unlock();
1119 } else {
1120 might_sleep();
1122 srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1123 blk_mq_sched_dispatch_requests(hctx);
1124 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1129 * It'd be great if the workqueue API had a way to pass
1130 * in a mask and had some smarts for more clever placement.
1131 * For now we just round-robin here, switching for every
1132 * BLK_MQ_CPU_WORK_BATCH queued items.
1134 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1136 if (hctx->queue->nr_hw_queues == 1)
1137 return WORK_CPU_UNBOUND;
1139 if (--hctx->next_cpu_batch <= 0) {
1140 int next_cpu;
1142 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1143 if (next_cpu >= nr_cpu_ids)
1144 next_cpu = cpumask_first(hctx->cpumask);
1146 hctx->next_cpu = next_cpu;
1147 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1150 return hctx->next_cpu;
1153 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1154 unsigned long msecs)
1156 if (unlikely(blk_mq_hctx_stopped(hctx) ||
1157 !blk_mq_hw_queue_mapped(hctx)))
1158 return;
1160 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1161 int cpu = get_cpu();
1162 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1163 __blk_mq_run_hw_queue(hctx);
1164 put_cpu();
1165 return;
1168 put_cpu();
1171 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1172 &hctx->run_work,
1173 msecs_to_jiffies(msecs));
1176 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1178 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1180 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1182 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1184 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1186 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1188 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1190 struct blk_mq_hw_ctx *hctx;
1191 int i;
1193 queue_for_each_hw_ctx(q, hctx, i) {
1194 if (!blk_mq_hctx_has_pending(hctx) ||
1195 blk_mq_hctx_stopped(hctx))
1196 continue;
1198 blk_mq_run_hw_queue(hctx, async);
1201 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1204 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1205 * @q: request queue.
1207 * The caller is responsible for serializing this function against
1208 * blk_mq_{start,stop}_hw_queue().
1210 bool blk_mq_queue_stopped(struct request_queue *q)
1212 struct blk_mq_hw_ctx *hctx;
1213 int i;
1215 queue_for_each_hw_ctx(q, hctx, i)
1216 if (blk_mq_hctx_stopped(hctx))
1217 return true;
1219 return false;
1221 EXPORT_SYMBOL(blk_mq_queue_stopped);
1223 static void __blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx, bool sync)
1225 if (sync)
1226 cancel_delayed_work_sync(&hctx->run_work);
1227 else
1228 cancel_delayed_work(&hctx->run_work);
1230 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1233 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1235 __blk_mq_stop_hw_queue(hctx, false);
1237 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1239 static void __blk_mq_stop_hw_queues(struct request_queue *q, bool sync)
1241 struct blk_mq_hw_ctx *hctx;
1242 int i;
1244 queue_for_each_hw_ctx(q, hctx, i)
1245 __blk_mq_stop_hw_queue(hctx, sync);
1248 void blk_mq_stop_hw_queues(struct request_queue *q)
1250 __blk_mq_stop_hw_queues(q, false);
1252 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1254 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1256 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1258 blk_mq_run_hw_queue(hctx, false);
1260 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1262 void blk_mq_start_hw_queues(struct request_queue *q)
1264 struct blk_mq_hw_ctx *hctx;
1265 int i;
1267 queue_for_each_hw_ctx(q, hctx, i)
1268 blk_mq_start_hw_queue(hctx);
1270 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1272 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1274 if (!blk_mq_hctx_stopped(hctx))
1275 return;
1277 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1278 blk_mq_run_hw_queue(hctx, async);
1280 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1282 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1284 struct blk_mq_hw_ctx *hctx;
1285 int i;
1287 queue_for_each_hw_ctx(q, hctx, i)
1288 blk_mq_start_stopped_hw_queue(hctx, async);
1290 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1292 static void blk_mq_run_work_fn(struct work_struct *work)
1294 struct blk_mq_hw_ctx *hctx;
1296 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1299 * If we are stopped, don't run the queue. The exception is if
1300 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1301 * the STOPPED bit and run it.
1303 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) {
1304 if (!test_bit(BLK_MQ_S_START_ON_RUN, &hctx->state))
1305 return;
1307 clear_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
1308 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1311 __blk_mq_run_hw_queue(hctx);
1315 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1317 if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1318 return;
1321 * Stop the hw queue, then modify currently delayed work.
1322 * This should prevent us from running the queue prematurely.
1323 * Mark the queue as auto-clearing STOPPED when it runs.
1325 blk_mq_stop_hw_queue(hctx);
1326 set_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
1327 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1328 &hctx->run_work,
1329 msecs_to_jiffies(msecs));
1331 EXPORT_SYMBOL(blk_mq_delay_queue);
1333 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1334 struct request *rq,
1335 bool at_head)
1337 struct blk_mq_ctx *ctx = rq->mq_ctx;
1339 trace_block_rq_insert(hctx->queue, rq);
1341 if (at_head)
1342 list_add(&rq->queuelist, &ctx->rq_list);
1343 else
1344 list_add_tail(&rq->queuelist, &ctx->rq_list);
1347 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1348 bool at_head)
1350 struct blk_mq_ctx *ctx = rq->mq_ctx;
1352 __blk_mq_insert_req_list(hctx, rq, at_head);
1353 blk_mq_hctx_mark_pending(hctx, ctx);
1356 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1357 struct list_head *list)
1361 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1362 * offline now
1364 spin_lock(&ctx->lock);
1365 while (!list_empty(list)) {
1366 struct request *rq;
1368 rq = list_first_entry(list, struct request, queuelist);
1369 BUG_ON(rq->mq_ctx != ctx);
1370 list_del_init(&rq->queuelist);
1371 __blk_mq_insert_req_list(hctx, rq, false);
1373 blk_mq_hctx_mark_pending(hctx, ctx);
1374 spin_unlock(&ctx->lock);
1377 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1379 struct request *rqa = container_of(a, struct request, queuelist);
1380 struct request *rqb = container_of(b, struct request, queuelist);
1382 return !(rqa->mq_ctx < rqb->mq_ctx ||
1383 (rqa->mq_ctx == rqb->mq_ctx &&
1384 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1387 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1389 struct blk_mq_ctx *this_ctx;
1390 struct request_queue *this_q;
1391 struct request *rq;
1392 LIST_HEAD(list);
1393 LIST_HEAD(ctx_list);
1394 unsigned int depth;
1396 list_splice_init(&plug->mq_list, &list);
1398 list_sort(NULL, &list, plug_ctx_cmp);
1400 this_q = NULL;
1401 this_ctx = NULL;
1402 depth = 0;
1404 while (!list_empty(&list)) {
1405 rq = list_entry_rq(list.next);
1406 list_del_init(&rq->queuelist);
1407 BUG_ON(!rq->q);
1408 if (rq->mq_ctx != this_ctx) {
1409 if (this_ctx) {
1410 trace_block_unplug(this_q, depth, from_schedule);
1411 blk_mq_sched_insert_requests(this_q, this_ctx,
1412 &ctx_list,
1413 from_schedule);
1416 this_ctx = rq->mq_ctx;
1417 this_q = rq->q;
1418 depth = 0;
1421 depth++;
1422 list_add_tail(&rq->queuelist, &ctx_list);
1426 * If 'this_ctx' is set, we know we have entries to complete
1427 * on 'ctx_list'. Do those.
1429 if (this_ctx) {
1430 trace_block_unplug(this_q, depth, from_schedule);
1431 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1432 from_schedule);
1436 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1438 blk_init_request_from_bio(rq, bio);
1440 blk_account_io_start(rq, true);
1443 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1445 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1446 !blk_queue_nomerges(hctx->queue);
1449 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1450 struct blk_mq_ctx *ctx,
1451 struct request *rq, struct bio *bio)
1453 if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1454 blk_mq_bio_to_request(rq, bio);
1455 spin_lock(&ctx->lock);
1456 insert_rq:
1457 __blk_mq_insert_request(hctx, rq, false);
1458 spin_unlock(&ctx->lock);
1459 return false;
1460 } else {
1461 struct request_queue *q = hctx->queue;
1463 spin_lock(&ctx->lock);
1464 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1465 blk_mq_bio_to_request(rq, bio);
1466 goto insert_rq;
1469 spin_unlock(&ctx->lock);
1470 __blk_mq_finish_request(hctx, ctx, rq);
1471 return true;
1475 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1477 if (rq->tag != -1)
1478 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1480 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1483 static void __blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
1484 bool may_sleep)
1486 struct request_queue *q = rq->q;
1487 struct blk_mq_queue_data bd = {
1488 .rq = rq,
1489 .last = true,
1491 struct blk_mq_hw_ctx *hctx;
1492 blk_qc_t new_cookie;
1493 int ret;
1495 if (q->elevator)
1496 goto insert;
1498 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1499 goto insert;
1501 new_cookie = request_to_qc_t(hctx, rq);
1504 * For OK queue, we are done. For error, kill it. Any other
1505 * error (busy), just add it to our list as we previously
1506 * would have done
1508 ret = q->mq_ops->queue_rq(hctx, &bd);
1509 if (ret == BLK_MQ_RQ_QUEUE_OK) {
1510 *cookie = new_cookie;
1511 return;
1514 if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1515 *cookie = BLK_QC_T_NONE;
1516 blk_mq_end_request(rq, -EIO);
1517 return;
1520 __blk_mq_requeue_request(rq);
1521 insert:
1522 blk_mq_sched_insert_request(rq, false, true, false, may_sleep);
1525 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1526 struct request *rq, blk_qc_t *cookie)
1528 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1529 rcu_read_lock();
1530 __blk_mq_try_issue_directly(rq, cookie, false);
1531 rcu_read_unlock();
1532 } else {
1533 unsigned int srcu_idx;
1535 might_sleep();
1537 srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1538 __blk_mq_try_issue_directly(rq, cookie, true);
1539 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1543 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1545 const int is_sync = op_is_sync(bio->bi_opf);
1546 const int is_flush_fua = op_is_flush(bio->bi_opf);
1547 struct blk_mq_alloc_data data = { .flags = 0 };
1548 struct request *rq;
1549 unsigned int request_count = 0;
1550 struct blk_plug *plug;
1551 struct request *same_queue_rq = NULL;
1552 blk_qc_t cookie;
1553 unsigned int wb_acct;
1555 blk_queue_bounce(q, &bio);
1557 blk_queue_split(q, &bio, q->bio_split);
1559 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1560 bio_io_error(bio);
1561 return BLK_QC_T_NONE;
1564 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1565 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1566 return BLK_QC_T_NONE;
1568 if (blk_mq_sched_bio_merge(q, bio))
1569 return BLK_QC_T_NONE;
1571 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1573 trace_block_getrq(q, bio, bio->bi_opf);
1575 rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1576 if (unlikely(!rq)) {
1577 __wbt_done(q->rq_wb, wb_acct);
1578 return BLK_QC_T_NONE;
1581 wbt_track(&rq->issue_stat, wb_acct);
1583 cookie = request_to_qc_t(data.hctx, rq);
1585 plug = current->plug;
1586 if (unlikely(is_flush_fua)) {
1587 blk_mq_put_ctx(data.ctx);
1588 blk_mq_bio_to_request(rq, bio);
1589 if (q->elevator) {
1590 blk_mq_sched_insert_request(rq, false, true, true,
1591 true);
1592 } else {
1593 blk_insert_flush(rq);
1594 blk_mq_run_hw_queue(data.hctx, true);
1596 } else if (plug && q->nr_hw_queues == 1) {
1597 struct request *last = NULL;
1599 blk_mq_put_ctx(data.ctx);
1600 blk_mq_bio_to_request(rq, bio);
1603 * @request_count may become stale because of schedule
1604 * out, so check the list again.
1606 if (list_empty(&plug->mq_list))
1607 request_count = 0;
1608 else if (blk_queue_nomerges(q))
1609 request_count = blk_plug_queued_count(q);
1611 if (!request_count)
1612 trace_block_plug(q);
1613 else
1614 last = list_entry_rq(plug->mq_list.prev);
1616 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1617 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1618 blk_flush_plug_list(plug, false);
1619 trace_block_plug(q);
1622 list_add_tail(&rq->queuelist, &plug->mq_list);
1623 } else if (plug && !blk_queue_nomerges(q)) {
1624 blk_mq_bio_to_request(rq, bio);
1627 * We do limited plugging. If the bio can be merged, do that.
1628 * Otherwise the existing request in the plug list will be
1629 * issued. So the plug list will have one request at most
1630 * The plug list might get flushed before this. If that happens,
1631 * the plug list is empty, and same_queue_rq is invalid.
1633 if (list_empty(&plug->mq_list))
1634 same_queue_rq = NULL;
1635 if (same_queue_rq)
1636 list_del_init(&same_queue_rq->queuelist);
1637 list_add_tail(&rq->queuelist, &plug->mq_list);
1639 blk_mq_put_ctx(data.ctx);
1641 if (same_queue_rq)
1642 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1643 &cookie);
1644 } else if (q->nr_hw_queues > 1 && is_sync) {
1645 blk_mq_put_ctx(data.ctx);
1646 blk_mq_bio_to_request(rq, bio);
1647 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1648 } else if (q->elevator) {
1649 blk_mq_put_ctx(data.ctx);
1650 blk_mq_bio_to_request(rq, bio);
1651 blk_mq_sched_insert_request(rq, false, true, true, true);
1652 } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1653 blk_mq_put_ctx(data.ctx);
1654 blk_mq_run_hw_queue(data.hctx, true);
1655 } else
1656 blk_mq_put_ctx(data.ctx);
1658 return cookie;
1661 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1662 unsigned int hctx_idx)
1664 struct page *page;
1666 if (tags->rqs && set->ops->exit_request) {
1667 int i;
1669 for (i = 0; i < tags->nr_tags; i++) {
1670 struct request *rq = tags->static_rqs[i];
1672 if (!rq)
1673 continue;
1674 set->ops->exit_request(set, rq, hctx_idx);
1675 tags->static_rqs[i] = NULL;
1679 while (!list_empty(&tags->page_list)) {
1680 page = list_first_entry(&tags->page_list, struct page, lru);
1681 list_del_init(&page->lru);
1683 * Remove kmemleak object previously allocated in
1684 * blk_mq_init_rq_map().
1686 kmemleak_free(page_address(page));
1687 __free_pages(page, page->private);
1691 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1693 kfree(tags->rqs);
1694 tags->rqs = NULL;
1695 kfree(tags->static_rqs);
1696 tags->static_rqs = NULL;
1698 blk_mq_free_tags(tags);
1701 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1702 unsigned int hctx_idx,
1703 unsigned int nr_tags,
1704 unsigned int reserved_tags)
1706 struct blk_mq_tags *tags;
1707 int node;
1709 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1710 if (node == NUMA_NO_NODE)
1711 node = set->numa_node;
1713 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1714 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1715 if (!tags)
1716 return NULL;
1718 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1719 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1720 node);
1721 if (!tags->rqs) {
1722 blk_mq_free_tags(tags);
1723 return NULL;
1726 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1727 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1728 node);
1729 if (!tags->static_rqs) {
1730 kfree(tags->rqs);
1731 blk_mq_free_tags(tags);
1732 return NULL;
1735 return tags;
1738 static size_t order_to_size(unsigned int order)
1740 return (size_t)PAGE_SIZE << order;
1743 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1744 unsigned int hctx_idx, unsigned int depth)
1746 unsigned int i, j, entries_per_page, max_order = 4;
1747 size_t rq_size, left;
1748 int node;
1750 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1751 if (node == NUMA_NO_NODE)
1752 node = set->numa_node;
1754 INIT_LIST_HEAD(&tags->page_list);
1757 * rq_size is the size of the request plus driver payload, rounded
1758 * to the cacheline size
1760 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1761 cache_line_size());
1762 left = rq_size * depth;
1764 for (i = 0; i < depth; ) {
1765 int this_order = max_order;
1766 struct page *page;
1767 int to_do;
1768 void *p;
1770 while (this_order && left < order_to_size(this_order - 1))
1771 this_order--;
1773 do {
1774 page = alloc_pages_node(node,
1775 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1776 this_order);
1777 if (page)
1778 break;
1779 if (!this_order--)
1780 break;
1781 if (order_to_size(this_order) < rq_size)
1782 break;
1783 } while (1);
1785 if (!page)
1786 goto fail;
1788 page->private = this_order;
1789 list_add_tail(&page->lru, &tags->page_list);
1791 p = page_address(page);
1793 * Allow kmemleak to scan these pages as they contain pointers
1794 * to additional allocations like via ops->init_request().
1796 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1797 entries_per_page = order_to_size(this_order) / rq_size;
1798 to_do = min(entries_per_page, depth - i);
1799 left -= to_do * rq_size;
1800 for (j = 0; j < to_do; j++) {
1801 struct request *rq = p;
1803 tags->static_rqs[i] = rq;
1804 if (set->ops->init_request) {
1805 if (set->ops->init_request(set, rq, hctx_idx,
1806 node)) {
1807 tags->static_rqs[i] = NULL;
1808 goto fail;
1812 p += rq_size;
1813 i++;
1816 return 0;
1818 fail:
1819 blk_mq_free_rqs(set, tags, hctx_idx);
1820 return -ENOMEM;
1824 * 'cpu' is going away. splice any existing rq_list entries from this
1825 * software queue to the hw queue dispatch list, and ensure that it
1826 * gets run.
1828 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1830 struct blk_mq_hw_ctx *hctx;
1831 struct blk_mq_ctx *ctx;
1832 LIST_HEAD(tmp);
1834 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1835 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1837 spin_lock(&ctx->lock);
1838 if (!list_empty(&ctx->rq_list)) {
1839 list_splice_init(&ctx->rq_list, &tmp);
1840 blk_mq_hctx_clear_pending(hctx, ctx);
1842 spin_unlock(&ctx->lock);
1844 if (list_empty(&tmp))
1845 return 0;
1847 spin_lock(&hctx->lock);
1848 list_splice_tail_init(&tmp, &hctx->dispatch);
1849 spin_unlock(&hctx->lock);
1851 blk_mq_run_hw_queue(hctx, true);
1852 return 0;
1855 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1857 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1858 &hctx->cpuhp_dead);
1861 /* hctx->ctxs will be freed in queue's release handler */
1862 static void blk_mq_exit_hctx(struct request_queue *q,
1863 struct blk_mq_tag_set *set,
1864 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1866 blk_mq_debugfs_unregister_hctx(hctx);
1868 blk_mq_tag_idle(hctx);
1870 if (set->ops->exit_request)
1871 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
1873 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
1875 if (set->ops->exit_hctx)
1876 set->ops->exit_hctx(hctx, hctx_idx);
1878 if (hctx->flags & BLK_MQ_F_BLOCKING)
1879 cleanup_srcu_struct(&hctx->queue_rq_srcu);
1881 blk_mq_remove_cpuhp(hctx);
1882 blk_free_flush_queue(hctx->fq);
1883 sbitmap_free(&hctx->ctx_map);
1886 static void blk_mq_exit_hw_queues(struct request_queue *q,
1887 struct blk_mq_tag_set *set, int nr_queue)
1889 struct blk_mq_hw_ctx *hctx;
1890 unsigned int i;
1892 queue_for_each_hw_ctx(q, hctx, i) {
1893 if (i == nr_queue)
1894 break;
1895 blk_mq_exit_hctx(q, set, hctx, i);
1899 static int blk_mq_init_hctx(struct request_queue *q,
1900 struct blk_mq_tag_set *set,
1901 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1903 int node;
1905 node = hctx->numa_node;
1906 if (node == NUMA_NO_NODE)
1907 node = hctx->numa_node = set->numa_node;
1909 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
1910 spin_lock_init(&hctx->lock);
1911 INIT_LIST_HEAD(&hctx->dispatch);
1912 hctx->queue = q;
1913 hctx->queue_num = hctx_idx;
1914 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1916 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1918 hctx->tags = set->tags[hctx_idx];
1921 * Allocate space for all possible cpus to avoid allocation at
1922 * runtime
1924 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1925 GFP_KERNEL, node);
1926 if (!hctx->ctxs)
1927 goto unregister_cpu_notifier;
1929 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1930 node))
1931 goto free_ctxs;
1933 hctx->nr_ctx = 0;
1935 if (set->ops->init_hctx &&
1936 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1937 goto free_bitmap;
1939 if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
1940 goto exit_hctx;
1942 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1943 if (!hctx->fq)
1944 goto sched_exit_hctx;
1946 if (set->ops->init_request &&
1947 set->ops->init_request(set, hctx->fq->flush_rq, hctx_idx,
1948 node))
1949 goto free_fq;
1951 if (hctx->flags & BLK_MQ_F_BLOCKING)
1952 init_srcu_struct(&hctx->queue_rq_srcu);
1954 blk_mq_debugfs_register_hctx(q, hctx);
1956 return 0;
1958 free_fq:
1959 kfree(hctx->fq);
1960 sched_exit_hctx:
1961 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
1962 exit_hctx:
1963 if (set->ops->exit_hctx)
1964 set->ops->exit_hctx(hctx, hctx_idx);
1965 free_bitmap:
1966 sbitmap_free(&hctx->ctx_map);
1967 free_ctxs:
1968 kfree(hctx->ctxs);
1969 unregister_cpu_notifier:
1970 blk_mq_remove_cpuhp(hctx);
1971 return -1;
1974 static void blk_mq_init_cpu_queues(struct request_queue *q,
1975 unsigned int nr_hw_queues)
1977 unsigned int i;
1979 for_each_possible_cpu(i) {
1980 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1981 struct blk_mq_hw_ctx *hctx;
1983 __ctx->cpu = i;
1984 spin_lock_init(&__ctx->lock);
1985 INIT_LIST_HEAD(&__ctx->rq_list);
1986 __ctx->queue = q;
1988 /* If the cpu isn't online, the cpu is mapped to first hctx */
1989 if (!cpu_online(i))
1990 continue;
1992 hctx = blk_mq_map_queue(q, i);
1995 * Set local node, IFF we have more than one hw queue. If
1996 * not, we remain on the home node of the device
1998 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1999 hctx->numa_node = local_memory_node(cpu_to_node(i));
2003 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2005 int ret = 0;
2007 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2008 set->queue_depth, set->reserved_tags);
2009 if (!set->tags[hctx_idx])
2010 return false;
2012 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2013 set->queue_depth);
2014 if (!ret)
2015 return true;
2017 blk_mq_free_rq_map(set->tags[hctx_idx]);
2018 set->tags[hctx_idx] = NULL;
2019 return false;
2022 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2023 unsigned int hctx_idx)
2025 if (set->tags[hctx_idx]) {
2026 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2027 blk_mq_free_rq_map(set->tags[hctx_idx]);
2028 set->tags[hctx_idx] = NULL;
2032 static void blk_mq_map_swqueue(struct request_queue *q,
2033 const struct cpumask *online_mask)
2035 unsigned int i, hctx_idx;
2036 struct blk_mq_hw_ctx *hctx;
2037 struct blk_mq_ctx *ctx;
2038 struct blk_mq_tag_set *set = q->tag_set;
2041 * Avoid others reading imcomplete hctx->cpumask through sysfs
2043 mutex_lock(&q->sysfs_lock);
2045 queue_for_each_hw_ctx(q, hctx, i) {
2046 cpumask_clear(hctx->cpumask);
2047 hctx->nr_ctx = 0;
2051 * Map software to hardware queues
2053 for_each_possible_cpu(i) {
2054 /* If the cpu isn't online, the cpu is mapped to first hctx */
2055 if (!cpumask_test_cpu(i, online_mask))
2056 continue;
2058 hctx_idx = q->mq_map[i];
2059 /* unmapped hw queue can be remapped after CPU topo changed */
2060 if (!set->tags[hctx_idx] &&
2061 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2063 * If tags initialization fail for some hctx,
2064 * that hctx won't be brought online. In this
2065 * case, remap the current ctx to hctx[0] which
2066 * is guaranteed to always have tags allocated
2068 q->mq_map[i] = 0;
2071 ctx = per_cpu_ptr(q->queue_ctx, i);
2072 hctx = blk_mq_map_queue(q, i);
2074 cpumask_set_cpu(i, hctx->cpumask);
2075 ctx->index_hw = hctx->nr_ctx;
2076 hctx->ctxs[hctx->nr_ctx++] = ctx;
2079 mutex_unlock(&q->sysfs_lock);
2081 queue_for_each_hw_ctx(q, hctx, i) {
2083 * If no software queues are mapped to this hardware queue,
2084 * disable it and free the request entries.
2086 if (!hctx->nr_ctx) {
2087 /* Never unmap queue 0. We need it as a
2088 * fallback in case of a new remap fails
2089 * allocation
2091 if (i && set->tags[i])
2092 blk_mq_free_map_and_requests(set, i);
2094 hctx->tags = NULL;
2095 continue;
2098 hctx->tags = set->tags[i];
2099 WARN_ON(!hctx->tags);
2102 * Set the map size to the number of mapped software queues.
2103 * This is more accurate and more efficient than looping
2104 * over all possibly mapped software queues.
2106 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2109 * Initialize batch roundrobin counts
2111 hctx->next_cpu = cpumask_first(hctx->cpumask);
2112 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2116 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2118 struct blk_mq_hw_ctx *hctx;
2119 int i;
2121 queue_for_each_hw_ctx(q, hctx, i) {
2122 if (shared)
2123 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2124 else
2125 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2129 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
2131 struct request_queue *q;
2133 lockdep_assert_held(&set->tag_list_lock);
2135 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2136 blk_mq_freeze_queue(q);
2137 queue_set_hctx_shared(q, shared);
2138 blk_mq_unfreeze_queue(q);
2142 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2144 struct blk_mq_tag_set *set = q->tag_set;
2146 mutex_lock(&set->tag_list_lock);
2147 list_del_rcu(&q->tag_set_list);
2148 INIT_LIST_HEAD(&q->tag_set_list);
2149 if (list_is_singular(&set->tag_list)) {
2150 /* just transitioned to unshared */
2151 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2152 /* update existing queue */
2153 blk_mq_update_tag_set_depth(set, false);
2155 mutex_unlock(&set->tag_list_lock);
2157 synchronize_rcu();
2160 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2161 struct request_queue *q)
2163 q->tag_set = set;
2165 mutex_lock(&set->tag_list_lock);
2167 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2168 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2169 set->flags |= BLK_MQ_F_TAG_SHARED;
2170 /* update existing queue */
2171 blk_mq_update_tag_set_depth(set, true);
2173 if (set->flags & BLK_MQ_F_TAG_SHARED)
2174 queue_set_hctx_shared(q, true);
2175 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2177 mutex_unlock(&set->tag_list_lock);
2181 * It is the actual release handler for mq, but we do it from
2182 * request queue's release handler for avoiding use-after-free
2183 * and headache because q->mq_kobj shouldn't have been introduced,
2184 * but we can't group ctx/kctx kobj without it.
2186 void blk_mq_release(struct request_queue *q)
2188 struct blk_mq_hw_ctx *hctx;
2189 unsigned int i;
2191 /* hctx kobj stays in hctx */
2192 queue_for_each_hw_ctx(q, hctx, i) {
2193 if (!hctx)
2194 continue;
2195 kobject_put(&hctx->kobj);
2198 q->mq_map = NULL;
2200 kfree(q->queue_hw_ctx);
2203 * release .mq_kobj and sw queue's kobject now because
2204 * both share lifetime with request queue.
2206 blk_mq_sysfs_deinit(q);
2208 free_percpu(q->queue_ctx);
2211 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2213 struct request_queue *uninit_q, *q;
2215 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2216 if (!uninit_q)
2217 return ERR_PTR(-ENOMEM);
2219 q = blk_mq_init_allocated_queue(set, uninit_q);
2220 if (IS_ERR(q))
2221 blk_cleanup_queue(uninit_q);
2223 return q;
2225 EXPORT_SYMBOL(blk_mq_init_queue);
2227 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2228 struct request_queue *q)
2230 int i, j;
2231 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2233 blk_mq_sysfs_unregister(q);
2234 for (i = 0; i < set->nr_hw_queues; i++) {
2235 int node;
2237 if (hctxs[i])
2238 continue;
2240 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2241 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
2242 GFP_KERNEL, node);
2243 if (!hctxs[i])
2244 break;
2246 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2247 node)) {
2248 kfree(hctxs[i]);
2249 hctxs[i] = NULL;
2250 break;
2253 atomic_set(&hctxs[i]->nr_active, 0);
2254 hctxs[i]->numa_node = node;
2255 hctxs[i]->queue_num = i;
2257 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2258 free_cpumask_var(hctxs[i]->cpumask);
2259 kfree(hctxs[i]);
2260 hctxs[i] = NULL;
2261 break;
2263 blk_mq_hctx_kobj_init(hctxs[i]);
2265 for (j = i; j < q->nr_hw_queues; j++) {
2266 struct blk_mq_hw_ctx *hctx = hctxs[j];
2268 if (hctx) {
2269 if (hctx->tags)
2270 blk_mq_free_map_and_requests(set, j);
2271 blk_mq_exit_hctx(q, set, hctx, j);
2272 kobject_put(&hctx->kobj);
2273 hctxs[j] = NULL;
2277 q->nr_hw_queues = i;
2278 blk_mq_sysfs_register(q);
2281 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2282 struct request_queue *q)
2284 /* mark the queue as mq asap */
2285 q->mq_ops = set->ops;
2287 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2288 blk_mq_poll_stats_bkt,
2289 BLK_MQ_POLL_STATS_BKTS, q);
2290 if (!q->poll_cb)
2291 goto err_exit;
2293 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2294 if (!q->queue_ctx)
2295 goto err_exit;
2297 /* init q->mq_kobj and sw queues' kobjects */
2298 blk_mq_sysfs_init(q);
2300 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2301 GFP_KERNEL, set->numa_node);
2302 if (!q->queue_hw_ctx)
2303 goto err_percpu;
2305 q->mq_map = set->mq_map;
2307 blk_mq_realloc_hw_ctxs(set, q);
2308 if (!q->nr_hw_queues)
2309 goto err_hctxs;
2311 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2312 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2314 q->nr_queues = nr_cpu_ids;
2316 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2318 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2319 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2321 q->sg_reserved_size = INT_MAX;
2323 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2324 INIT_LIST_HEAD(&q->requeue_list);
2325 spin_lock_init(&q->requeue_lock);
2327 blk_queue_make_request(q, blk_mq_make_request);
2330 * Do this after blk_queue_make_request() overrides it...
2332 q->nr_requests = set->queue_depth;
2335 * Default to classic polling
2337 q->poll_nsec = -1;
2339 if (set->ops->complete)
2340 blk_queue_softirq_done(q, set->ops->complete);
2342 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2344 get_online_cpus();
2345 mutex_lock(&all_q_mutex);
2347 list_add_tail(&q->all_q_node, &all_q_list);
2348 blk_mq_add_queue_tag_set(set, q);
2349 blk_mq_map_swqueue(q, cpu_online_mask);
2351 mutex_unlock(&all_q_mutex);
2352 put_online_cpus();
2354 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2355 int ret;
2357 ret = blk_mq_sched_init(q);
2358 if (ret)
2359 return ERR_PTR(ret);
2362 return q;
2364 err_hctxs:
2365 kfree(q->queue_hw_ctx);
2366 err_percpu:
2367 free_percpu(q->queue_ctx);
2368 err_exit:
2369 q->mq_ops = NULL;
2370 return ERR_PTR(-ENOMEM);
2372 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2374 void blk_mq_free_queue(struct request_queue *q)
2376 struct blk_mq_tag_set *set = q->tag_set;
2378 mutex_lock(&all_q_mutex);
2379 list_del_init(&q->all_q_node);
2380 mutex_unlock(&all_q_mutex);
2382 blk_mq_del_queue_tag_set(q);
2384 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2387 /* Basically redo blk_mq_init_queue with queue frozen */
2388 static void blk_mq_queue_reinit(struct request_queue *q,
2389 const struct cpumask *online_mask)
2391 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2393 blk_mq_debugfs_unregister_hctxs(q);
2394 blk_mq_sysfs_unregister(q);
2397 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2398 * we should change hctx numa_node according to new topology (this
2399 * involves free and re-allocate memory, worthy doing?)
2402 blk_mq_map_swqueue(q, online_mask);
2404 blk_mq_sysfs_register(q);
2405 blk_mq_debugfs_register_hctxs(q);
2409 * New online cpumask which is going to be set in this hotplug event.
2410 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2411 * one-by-one and dynamically allocating this could result in a failure.
2413 static struct cpumask cpuhp_online_new;
2415 static void blk_mq_queue_reinit_work(void)
2417 struct request_queue *q;
2419 mutex_lock(&all_q_mutex);
2421 * We need to freeze and reinit all existing queues. Freezing
2422 * involves synchronous wait for an RCU grace period and doing it
2423 * one by one may take a long time. Start freezing all queues in
2424 * one swoop and then wait for the completions so that freezing can
2425 * take place in parallel.
2427 list_for_each_entry(q, &all_q_list, all_q_node)
2428 blk_freeze_queue_start(q);
2429 list_for_each_entry(q, &all_q_list, all_q_node)
2430 blk_mq_freeze_queue_wait(q);
2432 list_for_each_entry(q, &all_q_list, all_q_node)
2433 blk_mq_queue_reinit(q, &cpuhp_online_new);
2435 list_for_each_entry(q, &all_q_list, all_q_node)
2436 blk_mq_unfreeze_queue(q);
2438 mutex_unlock(&all_q_mutex);
2441 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2443 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2444 blk_mq_queue_reinit_work();
2445 return 0;
2449 * Before hotadded cpu starts handling requests, new mappings must be
2450 * established. Otherwise, these requests in hw queue might never be
2451 * dispatched.
2453 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2454 * for CPU0, and ctx1 for CPU1).
2456 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2457 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2459 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2460 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2461 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2462 * ignored.
2464 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2466 cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2467 cpumask_set_cpu(cpu, &cpuhp_online_new);
2468 blk_mq_queue_reinit_work();
2469 return 0;
2472 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2474 int i;
2476 for (i = 0; i < set->nr_hw_queues; i++)
2477 if (!__blk_mq_alloc_rq_map(set, i))
2478 goto out_unwind;
2480 return 0;
2482 out_unwind:
2483 while (--i >= 0)
2484 blk_mq_free_rq_map(set->tags[i]);
2486 return -ENOMEM;
2490 * Allocate the request maps associated with this tag_set. Note that this
2491 * may reduce the depth asked for, if memory is tight. set->queue_depth
2492 * will be updated to reflect the allocated depth.
2494 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2496 unsigned int depth;
2497 int err;
2499 depth = set->queue_depth;
2500 do {
2501 err = __blk_mq_alloc_rq_maps(set);
2502 if (!err)
2503 break;
2505 set->queue_depth >>= 1;
2506 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2507 err = -ENOMEM;
2508 break;
2510 } while (set->queue_depth);
2512 if (!set->queue_depth || err) {
2513 pr_err("blk-mq: failed to allocate request map\n");
2514 return -ENOMEM;
2517 if (depth != set->queue_depth)
2518 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2519 depth, set->queue_depth);
2521 return 0;
2524 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2526 if (set->ops->map_queues)
2527 return set->ops->map_queues(set);
2528 else
2529 return blk_mq_map_queues(set);
2533 * Alloc a tag set to be associated with one or more request queues.
2534 * May fail with EINVAL for various error conditions. May adjust the
2535 * requested depth down, if if it too large. In that case, the set
2536 * value will be stored in set->queue_depth.
2538 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2540 int ret;
2542 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2544 if (!set->nr_hw_queues)
2545 return -EINVAL;
2546 if (!set->queue_depth)
2547 return -EINVAL;
2548 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2549 return -EINVAL;
2551 if (!set->ops->queue_rq)
2552 return -EINVAL;
2554 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2555 pr_info("blk-mq: reduced tag depth to %u\n",
2556 BLK_MQ_MAX_DEPTH);
2557 set->queue_depth = BLK_MQ_MAX_DEPTH;
2561 * If a crashdump is active, then we are potentially in a very
2562 * memory constrained environment. Limit us to 1 queue and
2563 * 64 tags to prevent using too much memory.
2565 if (is_kdump_kernel()) {
2566 set->nr_hw_queues = 1;
2567 set->queue_depth = min(64U, set->queue_depth);
2570 * There is no use for more h/w queues than cpus.
2572 if (set->nr_hw_queues > nr_cpu_ids)
2573 set->nr_hw_queues = nr_cpu_ids;
2575 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2576 GFP_KERNEL, set->numa_node);
2577 if (!set->tags)
2578 return -ENOMEM;
2580 ret = -ENOMEM;
2581 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2582 GFP_KERNEL, set->numa_node);
2583 if (!set->mq_map)
2584 goto out_free_tags;
2586 ret = blk_mq_update_queue_map(set);
2587 if (ret)
2588 goto out_free_mq_map;
2590 ret = blk_mq_alloc_rq_maps(set);
2591 if (ret)
2592 goto out_free_mq_map;
2594 mutex_init(&set->tag_list_lock);
2595 INIT_LIST_HEAD(&set->tag_list);
2597 return 0;
2599 out_free_mq_map:
2600 kfree(set->mq_map);
2601 set->mq_map = NULL;
2602 out_free_tags:
2603 kfree(set->tags);
2604 set->tags = NULL;
2605 return ret;
2607 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2609 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2611 int i;
2613 for (i = 0; i < nr_cpu_ids; i++)
2614 blk_mq_free_map_and_requests(set, i);
2616 kfree(set->mq_map);
2617 set->mq_map = NULL;
2619 kfree(set->tags);
2620 set->tags = NULL;
2622 EXPORT_SYMBOL(blk_mq_free_tag_set);
2624 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2626 struct blk_mq_tag_set *set = q->tag_set;
2627 struct blk_mq_hw_ctx *hctx;
2628 int i, ret;
2630 if (!set)
2631 return -EINVAL;
2633 blk_mq_freeze_queue(q);
2635 ret = 0;
2636 queue_for_each_hw_ctx(q, hctx, i) {
2637 if (!hctx->tags)
2638 continue;
2640 * If we're using an MQ scheduler, just update the scheduler
2641 * queue depth. This is similar to what the old code would do.
2643 if (!hctx->sched_tags) {
2644 ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2645 min(nr, set->queue_depth),
2646 false);
2647 } else {
2648 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2649 nr, true);
2651 if (ret)
2652 break;
2655 if (!ret)
2656 q->nr_requests = nr;
2658 blk_mq_unfreeze_queue(q);
2660 return ret;
2663 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2665 struct request_queue *q;
2667 lockdep_assert_held(&set->tag_list_lock);
2669 if (nr_hw_queues > nr_cpu_ids)
2670 nr_hw_queues = nr_cpu_ids;
2671 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2672 return;
2674 list_for_each_entry(q, &set->tag_list, tag_set_list)
2675 blk_mq_freeze_queue(q);
2677 set->nr_hw_queues = nr_hw_queues;
2678 blk_mq_update_queue_map(set);
2679 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2680 blk_mq_realloc_hw_ctxs(set, q);
2681 blk_mq_queue_reinit(q, cpu_online_mask);
2684 list_for_each_entry(q, &set->tag_list, tag_set_list)
2685 blk_mq_unfreeze_queue(q);
2687 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2689 /* Enable polling stats and return whether they were already enabled. */
2690 static bool blk_poll_stats_enable(struct request_queue *q)
2692 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2693 test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
2694 return true;
2695 blk_stat_add_callback(q, q->poll_cb);
2696 return false;
2699 static void blk_mq_poll_stats_start(struct request_queue *q)
2702 * We don't arm the callback if polling stats are not enabled or the
2703 * callback is already active.
2705 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2706 blk_stat_is_active(q->poll_cb))
2707 return;
2709 blk_stat_activate_msecs(q->poll_cb, 100);
2712 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
2714 struct request_queue *q = cb->data;
2715 int bucket;
2717 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
2718 if (cb->stat[bucket].nr_samples)
2719 q->poll_stat[bucket] = cb->stat[bucket];
2723 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2724 struct blk_mq_hw_ctx *hctx,
2725 struct request *rq)
2727 unsigned long ret = 0;
2728 int bucket;
2731 * If stats collection isn't on, don't sleep but turn it on for
2732 * future users
2734 if (!blk_poll_stats_enable(q))
2735 return 0;
2738 * As an optimistic guess, use half of the mean service time
2739 * for this type of request. We can (and should) make this smarter.
2740 * For instance, if the completion latencies are tight, we can
2741 * get closer than just half the mean. This is especially
2742 * important on devices where the completion latencies are longer
2743 * than ~10 usec. We do use the stats for the relevant IO size
2744 * if available which does lead to better estimates.
2746 bucket = blk_mq_poll_stats_bkt(rq);
2747 if (bucket < 0)
2748 return ret;
2750 if (q->poll_stat[bucket].nr_samples)
2751 ret = (q->poll_stat[bucket].mean + 1) / 2;
2753 return ret;
2756 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2757 struct blk_mq_hw_ctx *hctx,
2758 struct request *rq)
2760 struct hrtimer_sleeper hs;
2761 enum hrtimer_mode mode;
2762 unsigned int nsecs;
2763 ktime_t kt;
2765 if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2766 return false;
2769 * poll_nsec can be:
2771 * -1: don't ever hybrid sleep
2772 * 0: use half of prev avg
2773 * >0: use this specific value
2775 if (q->poll_nsec == -1)
2776 return false;
2777 else if (q->poll_nsec > 0)
2778 nsecs = q->poll_nsec;
2779 else
2780 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2782 if (!nsecs)
2783 return false;
2785 set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2788 * This will be replaced with the stats tracking code, using
2789 * 'avg_completion_time / 2' as the pre-sleep target.
2791 kt = nsecs;
2793 mode = HRTIMER_MODE_REL;
2794 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2795 hrtimer_set_expires(&hs.timer, kt);
2797 hrtimer_init_sleeper(&hs, current);
2798 do {
2799 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2800 break;
2801 set_current_state(TASK_UNINTERRUPTIBLE);
2802 hrtimer_start_expires(&hs.timer, mode);
2803 if (hs.task)
2804 io_schedule();
2805 hrtimer_cancel(&hs.timer);
2806 mode = HRTIMER_MODE_ABS;
2807 } while (hs.task && !signal_pending(current));
2809 __set_current_state(TASK_RUNNING);
2810 destroy_hrtimer_on_stack(&hs.timer);
2811 return true;
2814 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2816 struct request_queue *q = hctx->queue;
2817 long state;
2820 * If we sleep, have the caller restart the poll loop to reset
2821 * the state. Like for the other success return cases, the
2822 * caller is responsible for checking if the IO completed. If
2823 * the IO isn't complete, we'll get called again and will go
2824 * straight to the busy poll loop.
2826 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2827 return true;
2829 hctx->poll_considered++;
2831 state = current->state;
2832 while (!need_resched()) {
2833 int ret;
2835 hctx->poll_invoked++;
2837 ret = q->mq_ops->poll(hctx, rq->tag);
2838 if (ret > 0) {
2839 hctx->poll_success++;
2840 set_current_state(TASK_RUNNING);
2841 return true;
2844 if (signal_pending_state(state, current))
2845 set_current_state(TASK_RUNNING);
2847 if (current->state == TASK_RUNNING)
2848 return true;
2849 if (ret < 0)
2850 break;
2851 cpu_relax();
2854 return false;
2857 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2859 struct blk_mq_hw_ctx *hctx;
2860 struct blk_plug *plug;
2861 struct request *rq;
2863 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2864 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2865 return false;
2867 plug = current->plug;
2868 if (plug)
2869 blk_flush_plug_list(plug, false);
2871 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2872 if (!blk_qc_t_is_internal(cookie))
2873 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2874 else {
2875 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2877 * With scheduling, if the request has completed, we'll
2878 * get a NULL return here, as we clear the sched tag when
2879 * that happens. The request still remains valid, like always,
2880 * so we should be safe with just the NULL check.
2882 if (!rq)
2883 return false;
2886 return __blk_mq_poll(hctx, rq);
2888 EXPORT_SYMBOL_GPL(blk_mq_poll);
2890 void blk_mq_disable_hotplug(void)
2892 mutex_lock(&all_q_mutex);
2895 void blk_mq_enable_hotplug(void)
2897 mutex_unlock(&all_q_mutex);
2900 static int __init blk_mq_init(void)
2902 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2903 blk_mq_hctx_notify_dead);
2905 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2906 blk_mq_queue_reinit_prepare,
2907 blk_mq_queue_reinit_dead);
2908 return 0;
2910 subsys_initcall(blk_mq_init);