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1#include <linux/kernel.h>
2#include <linux/module.h>
3#include <linux/backing-dev.h>
4#include <linux/bio.h>
5#include <linux/blkdev.h>
6#include <linux/mm.h>
7#include <linux/init.h>
8#include <linux/slab.h>
9#include <linux/workqueue.h>
10#include <linux/smp.h>
11#include <linux/llist.h>
12#include <linux/list_sort.h>
13#include <linux/cpu.h>
14#include <linux/cache.h>
15#include <linux/sched/sysctl.h>
16#include <linux/delay.h>
17
18#include <trace/events/block.h>
19
20#include <linux/blk-mq.h>
21#include "blk.h"
22#include "blk-mq.h"
23#include "blk-mq-tag.h"
24
25static DEFINE_MUTEX(all_q_mutex);
26static LIST_HEAD(all_q_list);
27
28static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
29
30static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
31 unsigned int cpu)
32{
33 return per_cpu_ptr(q->queue_ctx, cpu);
34}
35
36/*
37 * This assumes per-cpu software queueing queues. They could be per-node
38 * as well, for instance. For now this is hardcoded as-is. Note that we don't
39 * care about preemption, since we know the ctx's are persistent. This does
40 * mean that we can't rely on ctx always matching the currently running CPU.
41 */
42static struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
43{
44 return __blk_mq_get_ctx(q, get_cpu());
45}
46
47static void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
48{
49 put_cpu();
50}
51
52/*
53 * Check if any of the ctx's have pending work in this hardware queue
54 */
55static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
56{
57 unsigned int i;
58
59 for (i = 0; i < hctx->nr_ctx_map; i++)
60 if (hctx->ctx_map[i])
61 return true;
62
63 return false;
64}
65
66/*
67 * Mark this ctx as having pending work in this hardware queue
68 */
69static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
70 struct blk_mq_ctx *ctx)
71{
72 if (!test_bit(ctx->index_hw, hctx->ctx_map))
73 set_bit(ctx->index_hw, hctx->ctx_map);
74}
75
76static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
77 gfp_t gfp, bool reserved)
78{
79 struct request *rq;
80 unsigned int tag;
81
82 tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
83 if (tag != BLK_MQ_TAG_FAIL) {
84 rq = hctx->rqs[tag];
85 rq->tag = tag;
86
87 return rq;
88 }
89
90 return NULL;
91}
92
93static int blk_mq_queue_enter(struct request_queue *q)
94{
95 int ret;
96
97 __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
98 smp_wmb();
99 /* we have problems to freeze the queue if it's initializing */
100 if (!blk_queue_bypass(q) || !blk_queue_init_done(q))
101 return 0;
102
103 __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
104
105 spin_lock_irq(q->queue_lock);
106 ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
107 !blk_queue_bypass(q) || blk_queue_dying(q),
108 *q->queue_lock);
109 /* inc usage with lock hold to avoid freeze_queue runs here */
110 if (!ret && !blk_queue_dying(q))
111 __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
112 else if (blk_queue_dying(q))
113 ret = -ENODEV;
114 spin_unlock_irq(q->queue_lock);
115
116 return ret;
117}
118
119static void blk_mq_queue_exit(struct request_queue *q)
120{
121 __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
122}
123
124static void __blk_mq_drain_queue(struct request_queue *q)
125{
126 while (true) {
127 s64 count;
128
129 spin_lock_irq(q->queue_lock);
130 count = percpu_counter_sum(&q->mq_usage_counter);
131 spin_unlock_irq(q->queue_lock);
132
133 if (count == 0)
134 break;
135 blk_mq_run_queues(q, false);
136 msleep(10);
137 }
138}
139
140/*
141 * Guarantee no request is in use, so we can change any data structure of
142 * the queue afterward.
143 */
144static void blk_mq_freeze_queue(struct request_queue *q)
145{
146 bool drain;
147
148 spin_lock_irq(q->queue_lock);
149 drain = !q->bypass_depth++;
150 queue_flag_set(QUEUE_FLAG_BYPASS, q);
151 spin_unlock_irq(q->queue_lock);
152
153 if (drain)
154 __blk_mq_drain_queue(q);
155}
156
157void blk_mq_drain_queue(struct request_queue *q)
158{
159 __blk_mq_drain_queue(q);
160}
161
162static void blk_mq_unfreeze_queue(struct request_queue *q)
163{
164 bool wake = false;
165
166 spin_lock_irq(q->queue_lock);
167 if (!--q->bypass_depth) {
168 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
169 wake = true;
170 }
171 WARN_ON_ONCE(q->bypass_depth < 0);
172 spin_unlock_irq(q->queue_lock);
173 if (wake)
174 wake_up_all(&q->mq_freeze_wq);
175}
176
177bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
178{
179 return blk_mq_has_free_tags(hctx->tags);
180}
181EXPORT_SYMBOL(blk_mq_can_queue);
182
183static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
184 struct request *rq, unsigned int rw_flags)
185{
186 if (blk_queue_io_stat(q))
187 rw_flags |= REQ_IO_STAT;
188
189 rq->mq_ctx = ctx;
190 rq->cmd_flags = rw_flags;
191 rq->start_time = jiffies;
192 set_start_time_ns(rq);
193 ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
194}
195
196static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
197 int rw, gfp_t gfp,
198 bool reserved)
199{
200 struct request *rq;
201
202 do {
203 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
204 struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
205
206 rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
207 if (rq) {
208 blk_mq_rq_ctx_init(q, ctx, rq, rw);
209 break;
210 }
211
212 blk_mq_put_ctx(ctx);
213 if (!(gfp & __GFP_WAIT))
214 break;
215
216 __blk_mq_run_hw_queue(hctx);
217 blk_mq_wait_for_tags(hctx->tags);
218 } while (1);
219
220 return rq;
221}
222
223struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp)
224{
225 struct request *rq;
226
227 if (blk_mq_queue_enter(q))
228 return NULL;
229
230 rq = blk_mq_alloc_request_pinned(q, rw, gfp, false);
231 if (rq)
232 blk_mq_put_ctx(rq->mq_ctx);
233 return rq;
234}
235
236struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
237 gfp_t gfp)
238{
239 struct request *rq;
240
241 if (blk_mq_queue_enter(q))
242 return NULL;
243
244 rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
245 if (rq)
246 blk_mq_put_ctx(rq->mq_ctx);
247 return rq;
248}
249EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
250
251/*
252 * Re-init and set pdu, if we have it
253 */
254void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
255{
256 blk_rq_init(hctx->queue, rq);
257
258 if (hctx->cmd_size)
259 rq->special = blk_mq_rq_to_pdu(rq);
260}
261
262static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
263 struct blk_mq_ctx *ctx, struct request *rq)
264{
265 const int tag = rq->tag;
266 struct request_queue *q = rq->q;
267
268 blk_mq_rq_init(hctx, rq);
269 blk_mq_put_tag(hctx->tags, tag);
270
271 blk_mq_queue_exit(q);
272}
273
274void blk_mq_free_request(struct request *rq)
275{
276 struct blk_mq_ctx *ctx = rq->mq_ctx;
277 struct blk_mq_hw_ctx *hctx;
278 struct request_queue *q = rq->q;
279
280 ctx->rq_completed[rq_is_sync(rq)]++;
281
282 hctx = q->mq_ops->map_queue(q, ctx->cpu);
283 __blk_mq_free_request(hctx, ctx, rq);
284}
285
286bool blk_mq_end_io_partial(struct request *rq, int error, unsigned int nr_bytes)
287{
288 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
289 return true;
290
291 blk_account_io_done(rq);
292
293 if (rq->end_io)
294 rq->end_io(rq, error);
295 else
296 blk_mq_free_request(rq);
297 return false;
298}
299EXPORT_SYMBOL(blk_mq_end_io_partial);
300
301static void __blk_mq_complete_request_remote(void *data)
302{
303 struct request *rq = data;
304
305 rq->q->softirq_done_fn(rq);
306}
307
308void __blk_mq_complete_request(struct request *rq)
309{
310 struct blk_mq_ctx *ctx = rq->mq_ctx;
311 int cpu;
312
313 if (!ctx->ipi_redirect) {
314 rq->q->softirq_done_fn(rq);
315 return;
316 }
317
318 cpu = get_cpu();
319 if (cpu != ctx->cpu && cpu_online(ctx->cpu)) {
320 rq->csd.func = __blk_mq_complete_request_remote;
321 rq->csd.info = rq;
322 rq->csd.flags = 0;
323 smp_call_function_single_async(ctx->cpu, &rq->csd);
324 } else {
325 rq->q->softirq_done_fn(rq);
326 }
327 put_cpu();
328}
329
330/**
331 * blk_mq_complete_request - end I/O on a request
332 * @rq: the request being processed
333 *
334 * Description:
335 * Ends all I/O on a request. It does not handle partial completions.
336 * The actual completion happens out-of-order, through a IPI handler.
337 **/
338void blk_mq_complete_request(struct request *rq)
339{
340 if (unlikely(blk_should_fake_timeout(rq->q)))
341 return;
342 if (!blk_mark_rq_complete(rq))
343 __blk_mq_complete_request(rq);
344}
345EXPORT_SYMBOL(blk_mq_complete_request);
346
347static void blk_mq_start_request(struct request *rq, bool last)
348{
349 struct request_queue *q = rq->q;
350
351 trace_block_rq_issue(q, rq);
352
353 /*
354 * Just mark start time and set the started bit. Due to memory
355 * ordering, we know we'll see the correct deadline as long as
356 * REQ_ATOMIC_STARTED is seen.
357 */
358 rq->deadline = jiffies + q->rq_timeout;
359 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
360
361 if (q->dma_drain_size && blk_rq_bytes(rq)) {
362 /*
363 * Make sure space for the drain appears. We know we can do
364 * this because max_hw_segments has been adjusted to be one
365 * fewer than the device can handle.
366 */
367 rq->nr_phys_segments++;
368 }
369
370 /*
371 * Flag the last request in the series so that drivers know when IO
372 * should be kicked off, if they don't do it on a per-request basis.
373 *
374 * Note: the flag isn't the only condition drivers should do kick off.
375 * If drive is busy, the last request might not have the bit set.
376 */
377 if (last)
378 rq->cmd_flags |= REQ_END;
379}
380
381static void blk_mq_requeue_request(struct request *rq)
382{
383 struct request_queue *q = rq->q;
384
385 trace_block_rq_requeue(q, rq);
386 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
387
388 rq->cmd_flags &= ~REQ_END;
389
390 if (q->dma_drain_size && blk_rq_bytes(rq))
391 rq->nr_phys_segments--;
392}
393
394struct blk_mq_timeout_data {
395 struct blk_mq_hw_ctx *hctx;
396 unsigned long *next;
397 unsigned int *next_set;
398};
399
400static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
401{
402 struct blk_mq_timeout_data *data = __data;
403 struct blk_mq_hw_ctx *hctx = data->hctx;
404 unsigned int tag;
405
406 /* It may not be in flight yet (this is where
407 * the REQ_ATOMIC_STARTED flag comes in). The requests are
408 * statically allocated, so we know it's always safe to access the
409 * memory associated with a bit offset into ->rqs[].
410 */
411 tag = 0;
412 do {
413 struct request *rq;
414
415 tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
416 if (tag >= hctx->queue_depth)
417 break;
418
419 rq = hctx->rqs[tag++];
420
421 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
422 continue;
423
424 blk_rq_check_expired(rq, data->next, data->next_set);
425 } while (1);
426}
427
428static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
429 unsigned long *next,
430 unsigned int *next_set)
431{
432 struct blk_mq_timeout_data data = {
433 .hctx = hctx,
434 .next = next,
435 .next_set = next_set,
436 };
437
438 /*
439 * Ask the tagging code to iterate busy requests, so we can
440 * check them for timeout.
441 */
442 blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
443}
444
445static void blk_mq_rq_timer(unsigned long data)
446{
447 struct request_queue *q = (struct request_queue *) data;
448 struct blk_mq_hw_ctx *hctx;
449 unsigned long next = 0;
450 int i, next_set = 0;
451
452 queue_for_each_hw_ctx(q, hctx, i)
453 blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
454
455 if (next_set)
456 mod_timer(&q->timeout, round_jiffies_up(next));
457}
458
459/*
460 * Reverse check our software queue for entries that we could potentially
461 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
462 * too much time checking for merges.
463 */
464static bool blk_mq_attempt_merge(struct request_queue *q,
465 struct blk_mq_ctx *ctx, struct bio *bio)
466{
467 struct request *rq;
468 int checked = 8;
469
470 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
471 int el_ret;
472
473 if (!checked--)
474 break;
475
476 if (!blk_rq_merge_ok(rq, bio))
477 continue;
478
479 el_ret = blk_try_merge(rq, bio);
480 if (el_ret == ELEVATOR_BACK_MERGE) {
481 if (bio_attempt_back_merge(q, rq, bio)) {
482 ctx->rq_merged++;
483 return true;
484 }
485 break;
486 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
487 if (bio_attempt_front_merge(q, rq, bio)) {
488 ctx->rq_merged++;
489 return true;
490 }
491 break;
492 }
493 }
494
495 return false;
496}
497
498void blk_mq_add_timer(struct request *rq)
499{
500 __blk_add_timer(rq, NULL);
501}
502
503/*
504 * Run this hardware queue, pulling any software queues mapped to it in.
505 * Note that this function currently has various problems around ordering
506 * of IO. In particular, we'd like FIFO behaviour on handling existing
507 * items on the hctx->dispatch list. Ignore that for now.
508 */
509static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
510{
511 struct request_queue *q = hctx->queue;
512 struct blk_mq_ctx *ctx;
513 struct request *rq;
514 LIST_HEAD(rq_list);
515 int bit, queued;
516
517 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
518 return;
519
520 hctx->run++;
521
522 /*
523 * Touch any software queue that has pending entries.
524 */
525 for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
526 clear_bit(bit, hctx->ctx_map);
527 ctx = hctx->ctxs[bit];
528 BUG_ON(bit != ctx->index_hw);
529
530 spin_lock(&ctx->lock);
531 list_splice_tail_init(&ctx->rq_list, &rq_list);
532 spin_unlock(&ctx->lock);
533 }
534
535 /*
536 * If we have previous entries on our dispatch list, grab them
537 * and stuff them at the front for more fair dispatch.
538 */
539 if (!list_empty_careful(&hctx->dispatch)) {
540 spin_lock(&hctx->lock);
541 if (!list_empty(&hctx->dispatch))
542 list_splice_init(&hctx->dispatch, &rq_list);
543 spin_unlock(&hctx->lock);
544 }
545
546 /*
547 * Delete and return all entries from our dispatch list
548 */
549 queued = 0;
550
551 /*
552 * Now process all the entries, sending them to the driver.
553 */
554 while (!list_empty(&rq_list)) {
555 int ret;
556
557 rq = list_first_entry(&rq_list, struct request, queuelist);
558 list_del_init(&rq->queuelist);
559
560 blk_mq_start_request(rq, list_empty(&rq_list));
561
562 ret = q->mq_ops->queue_rq(hctx, rq);
563 switch (ret) {
564 case BLK_MQ_RQ_QUEUE_OK:
565 queued++;
566 continue;
567 case BLK_MQ_RQ_QUEUE_BUSY:
568 /*
569 * FIXME: we should have a mechanism to stop the queue
570 * like blk_stop_queue, otherwise we will waste cpu
571 * time
572 */
573 list_add(&rq->queuelist, &rq_list);
574 blk_mq_requeue_request(rq);
575 break;
576 default:
577 pr_err("blk-mq: bad return on queue: %d\n", ret);
578 case BLK_MQ_RQ_QUEUE_ERROR:
579 rq->errors = -EIO;
580 blk_mq_end_io(rq, rq->errors);
581 break;
582 }
583
584 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
585 break;
586 }
587
588 if (!queued)
589 hctx->dispatched[0]++;
590 else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
591 hctx->dispatched[ilog2(queued) + 1]++;
592
593 /*
594 * Any items that need requeuing? Stuff them into hctx->dispatch,
595 * that is where we will continue on next queue run.
596 */
597 if (!list_empty(&rq_list)) {
598 spin_lock(&hctx->lock);
599 list_splice(&rq_list, &hctx->dispatch);
600 spin_unlock(&hctx->lock);
601 }
602}
603
604void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
605{
606 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
607 return;
608
609 if (!async)
610 __blk_mq_run_hw_queue(hctx);
611 else {
612 struct request_queue *q = hctx->queue;
613
614 kblockd_schedule_delayed_work(q, &hctx->delayed_work, 0);
615 }
616}
617
618void blk_mq_run_queues(struct request_queue *q, bool async)
619{
620 struct blk_mq_hw_ctx *hctx;
621 int i;
622
623 queue_for_each_hw_ctx(q, hctx, i) {
624 if ((!blk_mq_hctx_has_pending(hctx) &&
625 list_empty_careful(&hctx->dispatch)) ||
626 test_bit(BLK_MQ_S_STOPPED, &hctx->state))
627 continue;
628
629 blk_mq_run_hw_queue(hctx, async);
630 }
631}
632EXPORT_SYMBOL(blk_mq_run_queues);
633
634void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
635{
636 cancel_delayed_work(&hctx->delayed_work);
637 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
638}
639EXPORT_SYMBOL(blk_mq_stop_hw_queue);
640
641void blk_mq_stop_hw_queues(struct request_queue *q)
642{
643 struct blk_mq_hw_ctx *hctx;
644 int i;
645
646 queue_for_each_hw_ctx(q, hctx, i)
647 blk_mq_stop_hw_queue(hctx);
648}
649EXPORT_SYMBOL(blk_mq_stop_hw_queues);
650
651void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
652{
653 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
654 __blk_mq_run_hw_queue(hctx);
655}
656EXPORT_SYMBOL(blk_mq_start_hw_queue);
657
658void blk_mq_start_stopped_hw_queues(struct request_queue *q)
659{
660 struct blk_mq_hw_ctx *hctx;
661 int i;
662
663 queue_for_each_hw_ctx(q, hctx, i) {
664 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
665 continue;
666
667 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
668 blk_mq_run_hw_queue(hctx, true);
669 }
670}
671EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
672
673static void blk_mq_work_fn(struct work_struct *work)
674{
675 struct blk_mq_hw_ctx *hctx;
676
677 hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
678 __blk_mq_run_hw_queue(hctx);
679}
680
681static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
682 struct request *rq, bool at_head)
683{
684 struct blk_mq_ctx *ctx = rq->mq_ctx;
685
686 trace_block_rq_insert(hctx->queue, rq);
687
688 if (at_head)
689 list_add(&rq->queuelist, &ctx->rq_list);
690 else
691 list_add_tail(&rq->queuelist, &ctx->rq_list);
692 blk_mq_hctx_mark_pending(hctx, ctx);
693
694 /*
695 * We do this early, to ensure we are on the right CPU.
696 */
697 blk_mq_add_timer(rq);
698}
699
700void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
701 bool async)
702{
703 struct request_queue *q = rq->q;
704 struct blk_mq_hw_ctx *hctx;
705 struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
706
707 current_ctx = blk_mq_get_ctx(q);
708 if (!cpu_online(ctx->cpu))
709 rq->mq_ctx = ctx = current_ctx;
710
711 hctx = q->mq_ops->map_queue(q, ctx->cpu);
712
713 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
714 !(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
715 blk_insert_flush(rq);
716 } else {
717 spin_lock(&ctx->lock);
718 __blk_mq_insert_request(hctx, rq, at_head);
719 spin_unlock(&ctx->lock);
720 }
721
722 blk_mq_put_ctx(current_ctx);
723
724 if (run_queue)
725 blk_mq_run_hw_queue(hctx, async);
726}
727
728static void blk_mq_insert_requests(struct request_queue *q,
729 struct blk_mq_ctx *ctx,
730 struct list_head *list,
731 int depth,
732 bool from_schedule)
733
734{
735 struct blk_mq_hw_ctx *hctx;
736 struct blk_mq_ctx *current_ctx;
737
738 trace_block_unplug(q, depth, !from_schedule);
739
740 current_ctx = blk_mq_get_ctx(q);
741
742 if (!cpu_online(ctx->cpu))
743 ctx = current_ctx;
744 hctx = q->mq_ops->map_queue(q, ctx->cpu);
745
746 /*
747 * preemption doesn't flush plug list, so it's possible ctx->cpu is
748 * offline now
749 */
750 spin_lock(&ctx->lock);
751 while (!list_empty(list)) {
752 struct request *rq;
753
754 rq = list_first_entry(list, struct request, queuelist);
755 list_del_init(&rq->queuelist);
756 rq->mq_ctx = ctx;
757 __blk_mq_insert_request(hctx, rq, false);
758 }
759 spin_unlock(&ctx->lock);
760
761 blk_mq_put_ctx(current_ctx);
762
763 blk_mq_run_hw_queue(hctx, from_schedule);
764}
765
766static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
767{
768 struct request *rqa = container_of(a, struct request, queuelist);
769 struct request *rqb = container_of(b, struct request, queuelist);
770
771 return !(rqa->mq_ctx < rqb->mq_ctx ||
772 (rqa->mq_ctx == rqb->mq_ctx &&
773 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
774}
775
776void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
777{
778 struct blk_mq_ctx *this_ctx;
779 struct request_queue *this_q;
780 struct request *rq;
781 LIST_HEAD(list);
782 LIST_HEAD(ctx_list);
783 unsigned int depth;
784
785 list_splice_init(&plug->mq_list, &list);
786
787 list_sort(NULL, &list, plug_ctx_cmp);
788
789 this_q = NULL;
790 this_ctx = NULL;
791 depth = 0;
792
793 while (!list_empty(&list)) {
794 rq = list_entry_rq(list.next);
795 list_del_init(&rq->queuelist);
796 BUG_ON(!rq->q);
797 if (rq->mq_ctx != this_ctx) {
798 if (this_ctx) {
799 blk_mq_insert_requests(this_q, this_ctx,
800 &ctx_list, depth,
801 from_schedule);
802 }
803
804 this_ctx = rq->mq_ctx;
805 this_q = rq->q;
806 depth = 0;
807 }
808
809 depth++;
810 list_add_tail(&rq->queuelist, &ctx_list);
811 }
812
813 /*
814 * If 'this_ctx' is set, we know we have entries to complete
815 * on 'ctx_list'. Do those.
816 */
817 if (this_ctx) {
818 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
819 from_schedule);
820 }
821}
822
823static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
824{
825 init_request_from_bio(rq, bio);
826 blk_account_io_start(rq, 1);
827}
828
829static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
830{
831 struct blk_mq_hw_ctx *hctx;
832 struct blk_mq_ctx *ctx;
833 const int is_sync = rw_is_sync(bio->bi_rw);
834 const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
835 int rw = bio_data_dir(bio);
836 struct request *rq;
837 unsigned int use_plug, request_count = 0;
838
839 /*
840 * If we have multiple hardware queues, just go directly to
841 * one of those for sync IO.
842 */
843 use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
844
845 blk_queue_bounce(q, &bio);
846
847 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
848 bio_endio(bio, -EIO);
849 return;
850 }
851
852 if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
853 return;
854
855 if (blk_mq_queue_enter(q)) {
856 bio_endio(bio, -EIO);
857 return;
858 }
859
860 ctx = blk_mq_get_ctx(q);
861 hctx = q->mq_ops->map_queue(q, ctx->cpu);
862
863 if (is_sync)
864 rw |= REQ_SYNC;
865 trace_block_getrq(q, bio, rw);
866 rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
867 if (likely(rq))
868 blk_mq_rq_ctx_init(q, ctx, rq, rw);
869 else {
870 blk_mq_put_ctx(ctx);
871 trace_block_sleeprq(q, bio, rw);
872 rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
873 false);
874 ctx = rq->mq_ctx;
875 hctx = q->mq_ops->map_queue(q, ctx->cpu);
876 }
877
878 hctx->queued++;
879
880 if (unlikely(is_flush_fua)) {
881 blk_mq_bio_to_request(rq, bio);
882 blk_mq_put_ctx(ctx);
883 blk_insert_flush(rq);
884 goto run_queue;
885 }
886
887 /*
888 * A task plug currently exists. Since this is completely lockless,
889 * utilize that to temporarily store requests until the task is
890 * either done or scheduled away.
891 */
892 if (use_plug) {
893 struct blk_plug *plug = current->plug;
894
895 if (plug) {
896 blk_mq_bio_to_request(rq, bio);
897 if (list_empty(&plug->mq_list))
898 trace_block_plug(q);
899 else if (request_count >= BLK_MAX_REQUEST_COUNT) {
900 blk_flush_plug_list(plug, false);
901 trace_block_plug(q);
902 }
903 list_add_tail(&rq->queuelist, &plug->mq_list);
904 blk_mq_put_ctx(ctx);
905 return;
906 }
907 }
908
909 spin_lock(&ctx->lock);
910
911 if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
912 blk_mq_attempt_merge(q, ctx, bio))
913 __blk_mq_free_request(hctx, ctx, rq);
914 else {
915 blk_mq_bio_to_request(rq, bio);
916 __blk_mq_insert_request(hctx, rq, false);
917 }
918
919 spin_unlock(&ctx->lock);
920 blk_mq_put_ctx(ctx);
921
922 /*
923 * For a SYNC request, send it to the hardware immediately. For an
924 * ASYNC request, just ensure that we run it later on. The latter
925 * allows for merging opportunities and more efficient dispatching.
926 */
927run_queue:
928 blk_mq_run_hw_queue(hctx, !is_sync || is_flush_fua);
929}
930
931/*
932 * Default mapping to a software queue, since we use one per CPU.
933 */
934struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
935{
936 return q->queue_hw_ctx[q->mq_map[cpu]];
937}
938EXPORT_SYMBOL(blk_mq_map_queue);
939
940struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
941 unsigned int hctx_index)
942{
943 return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
944 GFP_KERNEL | __GFP_ZERO, reg->numa_node);
945}
946EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
947
948void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
949 unsigned int hctx_index)
950{
951 kfree(hctx);
952}
953EXPORT_SYMBOL(blk_mq_free_single_hw_queue);
954
955static void blk_mq_hctx_notify(void *data, unsigned long action,
956 unsigned int cpu)
957{
958 struct blk_mq_hw_ctx *hctx = data;
959 struct request_queue *q = hctx->queue;
960 struct blk_mq_ctx *ctx;
961 LIST_HEAD(tmp);
962
963 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
964 return;
965
966 /*
967 * Move ctx entries to new CPU, if this one is going away.
968 */
969 ctx = __blk_mq_get_ctx(q, cpu);
970
971 spin_lock(&ctx->lock);
972 if (!list_empty(&ctx->rq_list)) {
973 list_splice_init(&ctx->rq_list, &tmp);
974 clear_bit(ctx->index_hw, hctx->ctx_map);
975 }
976 spin_unlock(&ctx->lock);
977
978 if (list_empty(&tmp))
979 return;
980
981 ctx = blk_mq_get_ctx(q);
982 spin_lock(&ctx->lock);
983
984 while (!list_empty(&tmp)) {
985 struct request *rq;
986
987 rq = list_first_entry(&tmp, struct request, queuelist);
988 rq->mq_ctx = ctx;
989 list_move_tail(&rq->queuelist, &ctx->rq_list);
990 }
991
992 hctx = q->mq_ops->map_queue(q, ctx->cpu);
993 blk_mq_hctx_mark_pending(hctx, ctx);
994
995 spin_unlock(&ctx->lock);
996 blk_mq_put_ctx(ctx);
997
998 blk_mq_run_hw_queue(hctx, true);
999}
1000
1001static int blk_mq_init_hw_commands(struct blk_mq_hw_ctx *hctx,
1002 int (*init)(void *, struct blk_mq_hw_ctx *,
1003 struct request *, unsigned int),
1004 void *data)
1005{
1006 unsigned int i;
1007 int ret = 0;
1008
1009 for (i = 0; i < hctx->queue_depth; i++) {
1010 struct request *rq = hctx->rqs[i];
1011
1012 ret = init(data, hctx, rq, i);
1013 if (ret)
1014 break;
1015 }
1016
1017 return ret;
1018}
1019
1020int blk_mq_init_commands(struct request_queue *q,
1021 int (*init)(void *, struct blk_mq_hw_ctx *,
1022 struct request *, unsigned int),
1023 void *data)
1024{
1025 struct blk_mq_hw_ctx *hctx;
1026 unsigned int i;
1027 int ret = 0;
1028
1029 queue_for_each_hw_ctx(q, hctx, i) {
1030 ret = blk_mq_init_hw_commands(hctx, init, data);
1031 if (ret)
1032 break;
1033 }
1034
1035 return ret;
1036}
1037EXPORT_SYMBOL(blk_mq_init_commands);
1038
1039static void blk_mq_free_hw_commands(struct blk_mq_hw_ctx *hctx,
1040 void (*free)(void *, struct blk_mq_hw_ctx *,
1041 struct request *, unsigned int),
1042 void *data)
1043{
1044 unsigned int i;
1045
1046 for (i = 0; i < hctx->queue_depth; i++) {
1047 struct request *rq = hctx->rqs[i];
1048
1049 free(data, hctx, rq, i);
1050 }
1051}
1052
1053void blk_mq_free_commands(struct request_queue *q,
1054 void (*free)(void *, struct blk_mq_hw_ctx *,
1055 struct request *, unsigned int),
1056 void *data)
1057{
1058 struct blk_mq_hw_ctx *hctx;
1059 unsigned int i;
1060
1061 queue_for_each_hw_ctx(q, hctx, i)
1062 blk_mq_free_hw_commands(hctx, free, data);
1063}
1064EXPORT_SYMBOL(blk_mq_free_commands);
1065
1066static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx)
1067{
1068 struct page *page;
1069
1070 while (!list_empty(&hctx->page_list)) {
1071 page = list_first_entry(&hctx->page_list, struct page, lru);
1072 list_del_init(&page->lru);
1073 __free_pages(page, page->private);
1074 }
1075
1076 kfree(hctx->rqs);
1077
1078 if (hctx->tags)
1079 blk_mq_free_tags(hctx->tags);
1080}
1081
1082static size_t order_to_size(unsigned int order)
1083{
1084 size_t ret = PAGE_SIZE;
1085
1086 while (order--)
1087 ret *= 2;
1088
1089 return ret;
1090}
1091
1092static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
1093 unsigned int reserved_tags, int node)
1094{
1095 unsigned int i, j, entries_per_page, max_order = 4;
1096 size_t rq_size, left;
1097
1098 INIT_LIST_HEAD(&hctx->page_list);
1099
1100 hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
1101 GFP_KERNEL, node);
1102 if (!hctx->rqs)
1103 return -ENOMEM;
1104
1105 /*
1106 * rq_size is the size of the request plus driver payload, rounded
1107 * to the cacheline size
1108 */
1109 rq_size = round_up(sizeof(struct request) + hctx->cmd_size,
1110 cache_line_size());
1111 left = rq_size * hctx->queue_depth;
1112
1113 for (i = 0; i < hctx->queue_depth;) {
1114 int this_order = max_order;
1115 struct page *page;
1116 int to_do;
1117 void *p;
1118
1119 while (left < order_to_size(this_order - 1) && this_order)
1120 this_order--;
1121
1122 do {
1123 page = alloc_pages_node(node, GFP_KERNEL, this_order);
1124 if (page)
1125 break;
1126 if (!this_order--)
1127 break;
1128 if (order_to_size(this_order) < rq_size)
1129 break;
1130 } while (1);
1131
1132 if (!page)
1133 break;
1134
1135 page->private = this_order;
1136 list_add_tail(&page->lru, &hctx->page_list);
1137
1138 p = page_address(page);
1139 entries_per_page = order_to_size(this_order) / rq_size;
1140 to_do = min(entries_per_page, hctx->queue_depth - i);
1141 left -= to_do * rq_size;
1142 for (j = 0; j < to_do; j++) {
1143 hctx->rqs[i] = p;
1144 blk_mq_rq_init(hctx, hctx->rqs[i]);
1145 p += rq_size;
1146 i++;
1147 }
1148 }
1149
1150 if (i < (reserved_tags + BLK_MQ_TAG_MIN))
1151 goto err_rq_map;
1152 else if (i != hctx->queue_depth) {
1153 hctx->queue_depth = i;
1154 pr_warn("%s: queue depth set to %u because of low memory\n",
1155 __func__, i);
1156 }
1157
1158 hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
1159 if (!hctx->tags) {
1160err_rq_map:
1161 blk_mq_free_rq_map(hctx);
1162 return -ENOMEM;
1163 }
1164
1165 return 0;
1166}
1167
1168static int blk_mq_init_hw_queues(struct request_queue *q,
1169 struct blk_mq_reg *reg, void *driver_data)
1170{
1171 struct blk_mq_hw_ctx *hctx;
1172 unsigned int i, j;
1173
1174 /*
1175 * Initialize hardware queues
1176 */
1177 queue_for_each_hw_ctx(q, hctx, i) {
1178 unsigned int num_maps;
1179 int node;
1180
1181 node = hctx->numa_node;
1182 if (node == NUMA_NO_NODE)
1183 node = hctx->numa_node = reg->numa_node;
1184
1185 INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
1186 spin_lock_init(&hctx->lock);
1187 INIT_LIST_HEAD(&hctx->dispatch);
1188 hctx->queue = q;
1189 hctx->queue_num = i;
1190 hctx->flags = reg->flags;
1191 hctx->queue_depth = reg->queue_depth;
1192 hctx->cmd_size = reg->cmd_size;
1193
1194 blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
1195 blk_mq_hctx_notify, hctx);
1196 blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
1197
1198 if (blk_mq_init_rq_map(hctx, reg->reserved_tags, node))
1199 break;
1200
1201 /*
1202 * Allocate space for all possible cpus to avoid allocation in
1203 * runtime
1204 */
1205 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1206 GFP_KERNEL, node);
1207 if (!hctx->ctxs)
1208 break;
1209
1210 num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
1211 hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
1212 GFP_KERNEL, node);
1213 if (!hctx->ctx_map)
1214 break;
1215
1216 hctx->nr_ctx_map = num_maps;
1217 hctx->nr_ctx = 0;
1218
1219 if (reg->ops->init_hctx &&
1220 reg->ops->init_hctx(hctx, driver_data, i))
1221 break;
1222 }
1223
1224 if (i == q->nr_hw_queues)
1225 return 0;
1226
1227 /*
1228 * Init failed
1229 */
1230 queue_for_each_hw_ctx(q, hctx, j) {
1231 if (i == j)
1232 break;
1233
1234 if (reg->ops->exit_hctx)
1235 reg->ops->exit_hctx(hctx, j);
1236
1237 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1238 blk_mq_free_rq_map(hctx);
1239 kfree(hctx->ctxs);
1240 }
1241
1242 return 1;
1243}
1244
1245static void blk_mq_init_cpu_queues(struct request_queue *q,
1246 unsigned int nr_hw_queues)
1247{
1248 unsigned int i;
1249
1250 for_each_possible_cpu(i) {
1251 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1252 struct blk_mq_hw_ctx *hctx;
1253
1254 memset(__ctx, 0, sizeof(*__ctx));
1255 __ctx->cpu = i;
1256 spin_lock_init(&__ctx->lock);
1257 INIT_LIST_HEAD(&__ctx->rq_list);
1258 __ctx->queue = q;
1259
1260 /* If the cpu isn't online, the cpu is mapped to first hctx */
1261 hctx = q->mq_ops->map_queue(q, i);
1262 hctx->nr_ctx++;
1263
1264 if (!cpu_online(i))
1265 continue;
1266
1267 /*
1268 * Set local node, IFF we have more than one hw queue. If
1269 * not, we remain on the home node of the device
1270 */
1271 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1272 hctx->numa_node = cpu_to_node(i);
1273 }
1274}
1275
1276static void blk_mq_map_swqueue(struct request_queue *q)
1277{
1278 unsigned int i;
1279 struct blk_mq_hw_ctx *hctx;
1280 struct blk_mq_ctx *ctx;
1281
1282 queue_for_each_hw_ctx(q, hctx, i) {
1283 hctx->nr_ctx = 0;
1284 }
1285
1286 /*
1287 * Map software to hardware queues
1288 */
1289 queue_for_each_ctx(q, ctx, i) {
1290 /* If the cpu isn't online, the cpu is mapped to first hctx */
1291 hctx = q->mq_ops->map_queue(q, i);
1292 ctx->index_hw = hctx->nr_ctx;
1293 hctx->ctxs[hctx->nr_ctx++] = ctx;
1294 }
1295}
1296
1297struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
1298 void *driver_data)
1299{
1300 struct blk_mq_hw_ctx **hctxs;
1301 struct blk_mq_ctx *ctx;
1302 struct request_queue *q;
1303 int i;
1304
1305 if (!reg->nr_hw_queues ||
1306 !reg->ops->queue_rq || !reg->ops->map_queue ||
1307 !reg->ops->alloc_hctx || !reg->ops->free_hctx)
1308 return ERR_PTR(-EINVAL);
1309
1310 if (!reg->queue_depth)
1311 reg->queue_depth = BLK_MQ_MAX_DEPTH;
1312 else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
1313 pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
1314 reg->queue_depth = BLK_MQ_MAX_DEPTH;
1315 }
1316
1317 if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
1318 return ERR_PTR(-EINVAL);
1319
1320 ctx = alloc_percpu(struct blk_mq_ctx);
1321 if (!ctx)
1322 return ERR_PTR(-ENOMEM);
1323
1324 hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
1325 reg->numa_node);
1326
1327 if (!hctxs)
1328 goto err_percpu;
1329
1330 for (i = 0; i < reg->nr_hw_queues; i++) {
1331 hctxs[i] = reg->ops->alloc_hctx(reg, i);
1332 if (!hctxs[i])
1333 goto err_hctxs;
1334
1335 hctxs[i]->numa_node = NUMA_NO_NODE;
1336 hctxs[i]->queue_num = i;
1337 }
1338
1339 q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
1340 if (!q)
1341 goto err_hctxs;
1342
1343 q->mq_map = blk_mq_make_queue_map(reg);
1344 if (!q->mq_map)
1345 goto err_map;
1346
1347 setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
1348 blk_queue_rq_timeout(q, 30000);
1349
1350 q->nr_queues = nr_cpu_ids;
1351 q->nr_hw_queues = reg->nr_hw_queues;
1352
1353 q->queue_ctx = ctx;
1354 q->queue_hw_ctx = hctxs;
1355
1356 q->mq_ops = reg->ops;
1357 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1358
1359 q->sg_reserved_size = INT_MAX;
1360
1361 blk_queue_make_request(q, blk_mq_make_request);
1362 blk_queue_rq_timed_out(q, reg->ops->timeout);
1363 if (reg->timeout)
1364 blk_queue_rq_timeout(q, reg->timeout);
1365
1366 if (reg->ops->complete)
1367 blk_queue_softirq_done(q, reg->ops->complete);
1368
1369 blk_mq_init_flush(q);
1370 blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
1371
1372 q->flush_rq = kzalloc(round_up(sizeof(struct request) + reg->cmd_size,
1373 cache_line_size()), GFP_KERNEL);
1374 if (!q->flush_rq)
1375 goto err_hw;
1376
1377 if (blk_mq_init_hw_queues(q, reg, driver_data))
1378 goto err_flush_rq;
1379
1380 blk_mq_map_swqueue(q);
1381
1382 mutex_lock(&all_q_mutex);
1383 list_add_tail(&q->all_q_node, &all_q_list);
1384 mutex_unlock(&all_q_mutex);
1385
1386 return q;
1387
1388err_flush_rq:
1389 kfree(q->flush_rq);
1390err_hw:
1391 kfree(q->mq_map);
1392err_map:
1393 blk_cleanup_queue(q);
1394err_hctxs:
1395 for (i = 0; i < reg->nr_hw_queues; i++) {
1396 if (!hctxs[i])
1397 break;
1398 reg->ops->free_hctx(hctxs[i], i);
1399 }
1400 kfree(hctxs);
1401err_percpu:
1402 free_percpu(ctx);
1403 return ERR_PTR(-ENOMEM);
1404}
1405EXPORT_SYMBOL(blk_mq_init_queue);
1406
1407void blk_mq_free_queue(struct request_queue *q)
1408{
1409 struct blk_mq_hw_ctx *hctx;
1410 int i;
1411
1412 queue_for_each_hw_ctx(q, hctx, i) {
1413 kfree(hctx->ctx_map);
1414 kfree(hctx->ctxs);
1415 blk_mq_free_rq_map(hctx);
1416 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1417 if (q->mq_ops->exit_hctx)
1418 q->mq_ops->exit_hctx(hctx, i);
1419 q->mq_ops->free_hctx(hctx, i);
1420 }
1421
1422 free_percpu(q->queue_ctx);
1423 kfree(q->queue_hw_ctx);
1424 kfree(q->mq_map);
1425
1426 q->queue_ctx = NULL;
1427 q->queue_hw_ctx = NULL;
1428 q->mq_map = NULL;
1429
1430 mutex_lock(&all_q_mutex);
1431 list_del_init(&q->all_q_node);
1432 mutex_unlock(&all_q_mutex);
1433}
1434
1435/* Basically redo blk_mq_init_queue with queue frozen */
1436static void blk_mq_queue_reinit(struct request_queue *q)
1437{
1438 blk_mq_freeze_queue(q);
1439
1440 blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
1441
1442 /*
1443 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
1444 * we should change hctx numa_node according to new topology (this
1445 * involves free and re-allocate memory, worthy doing?)
1446 */
1447
1448 blk_mq_map_swqueue(q);
1449
1450 blk_mq_unfreeze_queue(q);
1451}
1452
1453static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
1454 unsigned long action, void *hcpu)
1455{
1456 struct request_queue *q;
1457
1458 /*
1459 * Before new mapping is established, hotadded cpu might already start
1460 * handling requests. This doesn't break anything as we map offline
1461 * CPUs to first hardware queue. We will re-init queue below to get
1462 * optimal settings.
1463 */
1464 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
1465 action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
1466 return NOTIFY_OK;
1467
1468 mutex_lock(&all_q_mutex);
1469 list_for_each_entry(q, &all_q_list, all_q_node)
1470 blk_mq_queue_reinit(q);
1471 mutex_unlock(&all_q_mutex);
1472 return NOTIFY_OK;
1473}
1474
1475void blk_mq_disable_hotplug(void)
1476{
1477 mutex_lock(&all_q_mutex);
1478}
1479
1480void blk_mq_enable_hotplug(void)
1481{
1482 mutex_unlock(&all_q_mutex);
1483}
1484
1485static int __init blk_mq_init(void)
1486{
1487 blk_mq_cpu_init();
1488
1489 /* Must be called after percpu_counter_hotcpu_callback() */
1490 hotcpu_notifier(blk_mq_queue_reinit_notify, -10);
1491
1492 return 0;
1493}
1494subsys_initcall(blk_mq_init);
1/*
2 * Block multiqueue core code
3 *
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>
28
29#include <trace/events/block.h>
30
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"
39
40static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
41static void blk_mq_poll_stats_start(struct request_queue *q);
42static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
43
44static int blk_mq_poll_stats_bkt(const struct request *rq)
45{
46 int ddir, bytes, bucket;
47
48 ddir = rq_data_dir(rq);
49 bytes = blk_rq_bytes(rq);
50
51 bucket = ddir + 2*(ilog2(bytes) - 9);
52
53 if (bucket < 0)
54 return -1;
55 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
56 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
57
58 return bucket;
59}
60
61/*
62 * Check if any of the ctx's have pending work in this hardware queue
63 */
64static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
65{
66 return !list_empty_careful(&hctx->dispatch) ||
67 sbitmap_any_bit_set(&hctx->ctx_map) ||
68 blk_mq_sched_has_work(hctx);
69}
70
71/*
72 * Mark this ctx as having pending work in this hardware queue
73 */
74static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
75 struct blk_mq_ctx *ctx)
76{
77 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
78 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
79}
80
81static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
82 struct blk_mq_ctx *ctx)
83{
84 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
85}
86
87struct mq_inflight {
88 struct hd_struct *part;
89 unsigned int *inflight;
90};
91
92static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
93 struct request *rq, void *priv,
94 bool reserved)
95{
96 struct mq_inflight *mi = priv;
97
98 /*
99 * index[0] counts the specific partition that was asked for. index[1]
100 * counts the ones that are active on the whole device, so increment
101 * that if mi->part is indeed a partition, and not a whole device.
102 */
103 if (rq->part == mi->part)
104 mi->inflight[0]++;
105 if (mi->part->partno)
106 mi->inflight[1]++;
107}
108
109void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
110 unsigned int inflight[2])
111{
112 struct mq_inflight mi = { .part = part, .inflight = inflight, };
113
114 inflight[0] = inflight[1] = 0;
115 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
116}
117
118static void blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
119 struct request *rq, void *priv,
120 bool reserved)
121{
122 struct mq_inflight *mi = priv;
123
124 if (rq->part == mi->part)
125 mi->inflight[rq_data_dir(rq)]++;
126}
127
128void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
129 unsigned int inflight[2])
130{
131 struct mq_inflight mi = { .part = part, .inflight = inflight, };
132
133 inflight[0] = inflight[1] = 0;
134 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
135}
136
137void blk_freeze_queue_start(struct request_queue *q)
138{
139 int freeze_depth;
140
141 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
142 if (freeze_depth == 1) {
143 percpu_ref_kill(&q->q_usage_counter);
144 if (q->mq_ops)
145 blk_mq_run_hw_queues(q, false);
146 }
147}
148EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
149
150void blk_mq_freeze_queue_wait(struct request_queue *q)
151{
152 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
153}
154EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
155
156int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
157 unsigned long timeout)
158{
159 return wait_event_timeout(q->mq_freeze_wq,
160 percpu_ref_is_zero(&q->q_usage_counter),
161 timeout);
162}
163EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
164
165/*
166 * Guarantee no request is in use, so we can change any data structure of
167 * the queue afterward.
168 */
169void blk_freeze_queue(struct request_queue *q)
170{
171 /*
172 * In the !blk_mq case we are only calling this to kill the
173 * q_usage_counter, otherwise this increases the freeze depth
174 * and waits for it to return to zero. For this reason there is
175 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
176 * exported to drivers as the only user for unfreeze is blk_mq.
177 */
178 blk_freeze_queue_start(q);
179 if (!q->mq_ops)
180 blk_drain_queue(q);
181 blk_mq_freeze_queue_wait(q);
182}
183
184void blk_mq_freeze_queue(struct request_queue *q)
185{
186 /*
187 * ...just an alias to keep freeze and unfreeze actions balanced
188 * in the blk_mq_* namespace
189 */
190 blk_freeze_queue(q);
191}
192EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
193
194void blk_mq_unfreeze_queue(struct request_queue *q)
195{
196 int freeze_depth;
197
198 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
199 WARN_ON_ONCE(freeze_depth < 0);
200 if (!freeze_depth) {
201 percpu_ref_reinit(&q->q_usage_counter);
202 wake_up_all(&q->mq_freeze_wq);
203 }
204}
205EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
206
207/*
208 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
209 * mpt3sas driver such that this function can be removed.
210 */
211void blk_mq_quiesce_queue_nowait(struct request_queue *q)
212{
213 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
214}
215EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
216
217/**
218 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
219 * @q: request queue.
220 *
221 * Note: this function does not prevent that the struct request end_io()
222 * callback function is invoked. Once this function is returned, we make
223 * sure no dispatch can happen until the queue is unquiesced via
224 * blk_mq_unquiesce_queue().
225 */
226void blk_mq_quiesce_queue(struct request_queue *q)
227{
228 struct blk_mq_hw_ctx *hctx;
229 unsigned int i;
230 bool rcu = false;
231
232 blk_mq_quiesce_queue_nowait(q);
233
234 queue_for_each_hw_ctx(q, hctx, i) {
235 if (hctx->flags & BLK_MQ_F_BLOCKING)
236 synchronize_srcu(hctx->srcu);
237 else
238 rcu = true;
239 }
240 if (rcu)
241 synchronize_rcu();
242}
243EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
244
245/*
246 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
247 * @q: request queue.
248 *
249 * This function recovers queue into the state before quiescing
250 * which is done by blk_mq_quiesce_queue.
251 */
252void blk_mq_unquiesce_queue(struct request_queue *q)
253{
254 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
255
256 /* dispatch requests which are inserted during quiescing */
257 blk_mq_run_hw_queues(q, true);
258}
259EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
260
261void blk_mq_wake_waiters(struct request_queue *q)
262{
263 struct blk_mq_hw_ctx *hctx;
264 unsigned int i;
265
266 queue_for_each_hw_ctx(q, hctx, i)
267 if (blk_mq_hw_queue_mapped(hctx))
268 blk_mq_tag_wakeup_all(hctx->tags, true);
269}
270
271bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
272{
273 return blk_mq_has_free_tags(hctx->tags);
274}
275EXPORT_SYMBOL(blk_mq_can_queue);
276
277static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
278 unsigned int tag, unsigned int op)
279{
280 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
281 struct request *rq = tags->static_rqs[tag];
282 req_flags_t rq_flags = 0;
283
284 if (data->flags & BLK_MQ_REQ_INTERNAL) {
285 rq->tag = -1;
286 rq->internal_tag = tag;
287 } else {
288 if (blk_mq_tag_busy(data->hctx)) {
289 rq_flags = RQF_MQ_INFLIGHT;
290 atomic_inc(&data->hctx->nr_active);
291 }
292 rq->tag = tag;
293 rq->internal_tag = -1;
294 data->hctx->tags->rqs[rq->tag] = rq;
295 }
296
297 /* csd/requeue_work/fifo_time is initialized before use */
298 rq->q = data->q;
299 rq->mq_ctx = data->ctx;
300 rq->rq_flags = rq_flags;
301 rq->cpu = -1;
302 rq->cmd_flags = op;
303 if (data->flags & BLK_MQ_REQ_PREEMPT)
304 rq->rq_flags |= RQF_PREEMPT;
305 if (blk_queue_io_stat(data->q))
306 rq->rq_flags |= RQF_IO_STAT;
307 INIT_LIST_HEAD(&rq->queuelist);
308 INIT_HLIST_NODE(&rq->hash);
309 RB_CLEAR_NODE(&rq->rb_node);
310 rq->rq_disk = NULL;
311 rq->part = NULL;
312 rq->start_time = jiffies;
313 rq->nr_phys_segments = 0;
314#if defined(CONFIG_BLK_DEV_INTEGRITY)
315 rq->nr_integrity_segments = 0;
316#endif
317 rq->special = NULL;
318 /* tag was already set */
319 rq->extra_len = 0;
320 rq->__deadline = 0;
321
322 INIT_LIST_HEAD(&rq->timeout_list);
323 rq->timeout = 0;
324
325 rq->end_io = NULL;
326 rq->end_io_data = NULL;
327 rq->next_rq = NULL;
328
329#ifdef CONFIG_BLK_CGROUP
330 rq->rl = NULL;
331 set_start_time_ns(rq);
332 rq->io_start_time_ns = 0;
333#endif
334
335 data->ctx->rq_dispatched[op_is_sync(op)]++;
336 return rq;
337}
338
339static struct request *blk_mq_get_request(struct request_queue *q,
340 struct bio *bio, unsigned int op,
341 struct blk_mq_alloc_data *data)
342{
343 struct elevator_queue *e = q->elevator;
344 struct request *rq;
345 unsigned int tag;
346 bool put_ctx_on_error = false;
347
348 blk_queue_enter_live(q);
349 data->q = q;
350 if (likely(!data->ctx)) {
351 data->ctx = blk_mq_get_ctx(q);
352 put_ctx_on_error = true;
353 }
354 if (likely(!data->hctx))
355 data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
356 if (op & REQ_NOWAIT)
357 data->flags |= BLK_MQ_REQ_NOWAIT;
358
359 if (e) {
360 data->flags |= BLK_MQ_REQ_INTERNAL;
361
362 /*
363 * Flush requests are special and go directly to the
364 * dispatch list.
365 */
366 if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
367 e->type->ops.mq.limit_depth(op, data);
368 }
369
370 tag = blk_mq_get_tag(data);
371 if (tag == BLK_MQ_TAG_FAIL) {
372 if (put_ctx_on_error) {
373 blk_mq_put_ctx(data->ctx);
374 data->ctx = NULL;
375 }
376 blk_queue_exit(q);
377 return NULL;
378 }
379
380 rq = blk_mq_rq_ctx_init(data, tag, op);
381 if (!op_is_flush(op)) {
382 rq->elv.icq = NULL;
383 if (e && e->type->ops.mq.prepare_request) {
384 if (e->type->icq_cache && rq_ioc(bio))
385 blk_mq_sched_assign_ioc(rq, bio);
386
387 e->type->ops.mq.prepare_request(rq, bio);
388 rq->rq_flags |= RQF_ELVPRIV;
389 }
390 }
391 data->hctx->queued++;
392 return rq;
393}
394
395struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
396 blk_mq_req_flags_t flags)
397{
398 struct blk_mq_alloc_data alloc_data = { .flags = flags };
399 struct request *rq;
400 int ret;
401
402 ret = blk_queue_enter(q, flags);
403 if (ret)
404 return ERR_PTR(ret);
405
406 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
407 blk_queue_exit(q);
408
409 if (!rq)
410 return ERR_PTR(-EWOULDBLOCK);
411
412 blk_mq_put_ctx(alloc_data.ctx);
413
414 rq->__data_len = 0;
415 rq->__sector = (sector_t) -1;
416 rq->bio = rq->biotail = NULL;
417 return rq;
418}
419EXPORT_SYMBOL(blk_mq_alloc_request);
420
421struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
422 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
423{
424 struct blk_mq_alloc_data alloc_data = { .flags = flags };
425 struct request *rq;
426 unsigned int cpu;
427 int ret;
428
429 /*
430 * If the tag allocator sleeps we could get an allocation for a
431 * different hardware context. No need to complicate the low level
432 * allocator for this for the rare use case of a command tied to
433 * a specific queue.
434 */
435 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
436 return ERR_PTR(-EINVAL);
437
438 if (hctx_idx >= q->nr_hw_queues)
439 return ERR_PTR(-EIO);
440
441 ret = blk_queue_enter(q, flags);
442 if (ret)
443 return ERR_PTR(ret);
444
445 /*
446 * Check if the hardware context is actually mapped to anything.
447 * If not tell the caller that it should skip this queue.
448 */
449 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
450 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
451 blk_queue_exit(q);
452 return ERR_PTR(-EXDEV);
453 }
454 cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
455 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
456
457 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
458 blk_queue_exit(q);
459
460 if (!rq)
461 return ERR_PTR(-EWOULDBLOCK);
462
463 return rq;
464}
465EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
466
467void blk_mq_free_request(struct request *rq)
468{
469 struct request_queue *q = rq->q;
470 struct elevator_queue *e = q->elevator;
471 struct blk_mq_ctx *ctx = rq->mq_ctx;
472 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
473 const int sched_tag = rq->internal_tag;
474
475 if (rq->rq_flags & RQF_ELVPRIV) {
476 if (e && e->type->ops.mq.finish_request)
477 e->type->ops.mq.finish_request(rq);
478 if (rq->elv.icq) {
479 put_io_context(rq->elv.icq->ioc);
480 rq->elv.icq = NULL;
481 }
482 }
483
484 ctx->rq_completed[rq_is_sync(rq)]++;
485 if (rq->rq_flags & RQF_MQ_INFLIGHT)
486 atomic_dec(&hctx->nr_active);
487
488 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
489 laptop_io_completion(q->backing_dev_info);
490
491 wbt_done(q->rq_wb, &rq->issue_stat);
492
493 if (blk_rq_rl(rq))
494 blk_put_rl(blk_rq_rl(rq));
495
496 blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
497 if (rq->tag != -1)
498 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
499 if (sched_tag != -1)
500 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
501 blk_mq_sched_restart(hctx);
502 blk_queue_exit(q);
503}
504EXPORT_SYMBOL_GPL(blk_mq_free_request);
505
506inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
507{
508 blk_account_io_done(rq);
509
510 if (rq->end_io) {
511 wbt_done(rq->q->rq_wb, &rq->issue_stat);
512 rq->end_io(rq, error);
513 } else {
514 if (unlikely(blk_bidi_rq(rq)))
515 blk_mq_free_request(rq->next_rq);
516 blk_mq_free_request(rq);
517 }
518}
519EXPORT_SYMBOL(__blk_mq_end_request);
520
521void blk_mq_end_request(struct request *rq, blk_status_t error)
522{
523 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
524 BUG();
525 __blk_mq_end_request(rq, error);
526}
527EXPORT_SYMBOL(blk_mq_end_request);
528
529static void __blk_mq_complete_request_remote(void *data)
530{
531 struct request *rq = data;
532
533 rq->q->softirq_done_fn(rq);
534}
535
536static void __blk_mq_complete_request(struct request *rq)
537{
538 struct blk_mq_ctx *ctx = rq->mq_ctx;
539 bool shared = false;
540 int cpu;
541
542 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT);
543 blk_mq_rq_update_state(rq, MQ_RQ_COMPLETE);
544
545 if (rq->internal_tag != -1)
546 blk_mq_sched_completed_request(rq);
547 if (rq->rq_flags & RQF_STATS) {
548 blk_mq_poll_stats_start(rq->q);
549 blk_stat_add(rq);
550 }
551
552 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
553 rq->q->softirq_done_fn(rq);
554 return;
555 }
556
557 cpu = get_cpu();
558 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
559 shared = cpus_share_cache(cpu, ctx->cpu);
560
561 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
562 rq->csd.func = __blk_mq_complete_request_remote;
563 rq->csd.info = rq;
564 rq->csd.flags = 0;
565 smp_call_function_single_async(ctx->cpu, &rq->csd);
566 } else {
567 rq->q->softirq_done_fn(rq);
568 }
569 put_cpu();
570}
571
572static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
573 __releases(hctx->srcu)
574{
575 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
576 rcu_read_unlock();
577 else
578 srcu_read_unlock(hctx->srcu, srcu_idx);
579}
580
581static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
582 __acquires(hctx->srcu)
583{
584 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
585 /* shut up gcc false positive */
586 *srcu_idx = 0;
587 rcu_read_lock();
588 } else
589 *srcu_idx = srcu_read_lock(hctx->srcu);
590}
591
592static void blk_mq_rq_update_aborted_gstate(struct request *rq, u64 gstate)
593{
594 unsigned long flags;
595
596 /*
597 * blk_mq_rq_aborted_gstate() is used from the completion path and
598 * can thus be called from irq context. u64_stats_fetch in the
599 * middle of update on the same CPU leads to lockup. Disable irq
600 * while updating.
601 */
602 local_irq_save(flags);
603 u64_stats_update_begin(&rq->aborted_gstate_sync);
604 rq->aborted_gstate = gstate;
605 u64_stats_update_end(&rq->aborted_gstate_sync);
606 local_irq_restore(flags);
607}
608
609static u64 blk_mq_rq_aborted_gstate(struct request *rq)
610{
611 unsigned int start;
612 u64 aborted_gstate;
613
614 do {
615 start = u64_stats_fetch_begin(&rq->aborted_gstate_sync);
616 aborted_gstate = rq->aborted_gstate;
617 } while (u64_stats_fetch_retry(&rq->aborted_gstate_sync, start));
618
619 return aborted_gstate;
620}
621
622/**
623 * blk_mq_complete_request - end I/O on a request
624 * @rq: the request being processed
625 *
626 * Description:
627 * Ends all I/O on a request. It does not handle partial completions.
628 * The actual completion happens out-of-order, through a IPI handler.
629 **/
630void blk_mq_complete_request(struct request *rq)
631{
632 struct request_queue *q = rq->q;
633 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
634 int srcu_idx;
635
636 if (unlikely(blk_should_fake_timeout(q)))
637 return;
638
639 /*
640 * If @rq->aborted_gstate equals the current instance, timeout is
641 * claiming @rq and we lost. This is synchronized through
642 * hctx_lock(). See blk_mq_timeout_work() for details.
643 *
644 * Completion path never blocks and we can directly use RCU here
645 * instead of hctx_lock() which can be either RCU or SRCU.
646 * However, that would complicate paths which want to synchronize
647 * against us. Let stay in sync with the issue path so that
648 * hctx_lock() covers both issue and completion paths.
649 */
650 hctx_lock(hctx, &srcu_idx);
651 if (blk_mq_rq_aborted_gstate(rq) != rq->gstate)
652 __blk_mq_complete_request(rq);
653 hctx_unlock(hctx, srcu_idx);
654}
655EXPORT_SYMBOL(blk_mq_complete_request);
656
657int blk_mq_request_started(struct request *rq)
658{
659 return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
660}
661EXPORT_SYMBOL_GPL(blk_mq_request_started);
662
663void blk_mq_start_request(struct request *rq)
664{
665 struct request_queue *q = rq->q;
666
667 blk_mq_sched_started_request(rq);
668
669 trace_block_rq_issue(q, rq);
670
671 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
672 blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
673 rq->rq_flags |= RQF_STATS;
674 wbt_issue(q->rq_wb, &rq->issue_stat);
675 }
676
677 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
678
679 /*
680 * Mark @rq in-flight which also advances the generation number,
681 * and register for timeout. Protect with a seqcount to allow the
682 * timeout path to read both @rq->gstate and @rq->deadline
683 * coherently.
684 *
685 * This is the only place where a request is marked in-flight. If
686 * the timeout path reads an in-flight @rq->gstate, the
687 * @rq->deadline it reads together under @rq->gstate_seq is
688 * guaranteed to be the matching one.
689 */
690 preempt_disable();
691 write_seqcount_begin(&rq->gstate_seq);
692
693 blk_mq_rq_update_state(rq, MQ_RQ_IN_FLIGHT);
694 blk_add_timer(rq);
695
696 write_seqcount_end(&rq->gstate_seq);
697 preempt_enable();
698
699 if (q->dma_drain_size && blk_rq_bytes(rq)) {
700 /*
701 * Make sure space for the drain appears. We know we can do
702 * this because max_hw_segments has been adjusted to be one
703 * fewer than the device can handle.
704 */
705 rq->nr_phys_segments++;
706 }
707}
708EXPORT_SYMBOL(blk_mq_start_request);
709
710/*
711 * When we reach here because queue is busy, it's safe to change the state
712 * to IDLE without checking @rq->aborted_gstate because we should still be
713 * holding the RCU read lock and thus protected against timeout.
714 */
715static void __blk_mq_requeue_request(struct request *rq)
716{
717 struct request_queue *q = rq->q;
718
719 blk_mq_put_driver_tag(rq);
720
721 trace_block_rq_requeue(q, rq);
722 wbt_requeue(q->rq_wb, &rq->issue_stat);
723
724 if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) {
725 blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
726 if (q->dma_drain_size && blk_rq_bytes(rq))
727 rq->nr_phys_segments--;
728 }
729}
730
731void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
732{
733 __blk_mq_requeue_request(rq);
734
735 /* this request will be re-inserted to io scheduler queue */
736 blk_mq_sched_requeue_request(rq);
737
738 BUG_ON(blk_queued_rq(rq));
739 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
740}
741EXPORT_SYMBOL(blk_mq_requeue_request);
742
743static void blk_mq_requeue_work(struct work_struct *work)
744{
745 struct request_queue *q =
746 container_of(work, struct request_queue, requeue_work.work);
747 LIST_HEAD(rq_list);
748 struct request *rq, *next;
749
750 spin_lock_irq(&q->requeue_lock);
751 list_splice_init(&q->requeue_list, &rq_list);
752 spin_unlock_irq(&q->requeue_lock);
753
754 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
755 if (!(rq->rq_flags & RQF_SOFTBARRIER))
756 continue;
757
758 rq->rq_flags &= ~RQF_SOFTBARRIER;
759 list_del_init(&rq->queuelist);
760 blk_mq_sched_insert_request(rq, true, false, false);
761 }
762
763 while (!list_empty(&rq_list)) {
764 rq = list_entry(rq_list.next, struct request, queuelist);
765 list_del_init(&rq->queuelist);
766 blk_mq_sched_insert_request(rq, false, false, false);
767 }
768
769 blk_mq_run_hw_queues(q, false);
770}
771
772void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
773 bool kick_requeue_list)
774{
775 struct request_queue *q = rq->q;
776 unsigned long flags;
777
778 /*
779 * We abuse this flag that is otherwise used by the I/O scheduler to
780 * request head insertion from the workqueue.
781 */
782 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
783
784 spin_lock_irqsave(&q->requeue_lock, flags);
785 if (at_head) {
786 rq->rq_flags |= RQF_SOFTBARRIER;
787 list_add(&rq->queuelist, &q->requeue_list);
788 } else {
789 list_add_tail(&rq->queuelist, &q->requeue_list);
790 }
791 spin_unlock_irqrestore(&q->requeue_lock, flags);
792
793 if (kick_requeue_list)
794 blk_mq_kick_requeue_list(q);
795}
796EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
797
798void blk_mq_kick_requeue_list(struct request_queue *q)
799{
800 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
801}
802EXPORT_SYMBOL(blk_mq_kick_requeue_list);
803
804void blk_mq_delay_kick_requeue_list(struct request_queue *q,
805 unsigned long msecs)
806{
807 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
808 msecs_to_jiffies(msecs));
809}
810EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
811
812struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
813{
814 if (tag < tags->nr_tags) {
815 prefetch(tags->rqs[tag]);
816 return tags->rqs[tag];
817 }
818
819 return NULL;
820}
821EXPORT_SYMBOL(blk_mq_tag_to_rq);
822
823struct blk_mq_timeout_data {
824 unsigned long next;
825 unsigned int next_set;
826 unsigned int nr_expired;
827};
828
829static void blk_mq_rq_timed_out(struct request *req, bool reserved)
830{
831 const struct blk_mq_ops *ops = req->q->mq_ops;
832 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
833
834 req->rq_flags |= RQF_MQ_TIMEOUT_EXPIRED;
835
836 if (ops->timeout)
837 ret = ops->timeout(req, reserved);
838
839 switch (ret) {
840 case BLK_EH_HANDLED:
841 __blk_mq_complete_request(req);
842 break;
843 case BLK_EH_RESET_TIMER:
844 /*
845 * As nothing prevents from completion happening while
846 * ->aborted_gstate is set, this may lead to ignored
847 * completions and further spurious timeouts.
848 */
849 blk_mq_rq_update_aborted_gstate(req, 0);
850 blk_add_timer(req);
851 break;
852 case BLK_EH_NOT_HANDLED:
853 break;
854 default:
855 printk(KERN_ERR "block: bad eh return: %d\n", ret);
856 break;
857 }
858}
859
860static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
861 struct request *rq, void *priv, bool reserved)
862{
863 struct blk_mq_timeout_data *data = priv;
864 unsigned long gstate, deadline;
865 int start;
866
867 might_sleep();
868
869 if (rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED)
870 return;
871
872 /* read coherent snapshots of @rq->state_gen and @rq->deadline */
873 while (true) {
874 start = read_seqcount_begin(&rq->gstate_seq);
875 gstate = READ_ONCE(rq->gstate);
876 deadline = blk_rq_deadline(rq);
877 if (!read_seqcount_retry(&rq->gstate_seq, start))
878 break;
879 cond_resched();
880 }
881
882 /* if in-flight && overdue, mark for abortion */
883 if ((gstate & MQ_RQ_STATE_MASK) == MQ_RQ_IN_FLIGHT &&
884 time_after_eq(jiffies, deadline)) {
885 blk_mq_rq_update_aborted_gstate(rq, gstate);
886 data->nr_expired++;
887 hctx->nr_expired++;
888 } else if (!data->next_set || time_after(data->next, deadline)) {
889 data->next = deadline;
890 data->next_set = 1;
891 }
892}
893
894static void blk_mq_terminate_expired(struct blk_mq_hw_ctx *hctx,
895 struct request *rq, void *priv, bool reserved)
896{
897 /*
898 * We marked @rq->aborted_gstate and waited for RCU. If there were
899 * completions that we lost to, they would have finished and
900 * updated @rq->gstate by now; otherwise, the completion path is
901 * now guaranteed to see @rq->aborted_gstate and yield. If
902 * @rq->aborted_gstate still matches @rq->gstate, @rq is ours.
903 */
904 if (!(rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED) &&
905 READ_ONCE(rq->gstate) == rq->aborted_gstate)
906 blk_mq_rq_timed_out(rq, reserved);
907}
908
909static void blk_mq_timeout_work(struct work_struct *work)
910{
911 struct request_queue *q =
912 container_of(work, struct request_queue, timeout_work);
913 struct blk_mq_timeout_data data = {
914 .next = 0,
915 .next_set = 0,
916 .nr_expired = 0,
917 };
918 struct blk_mq_hw_ctx *hctx;
919 int i;
920
921 /* A deadlock might occur if a request is stuck requiring a
922 * timeout at the same time a queue freeze is waiting
923 * completion, since the timeout code would not be able to
924 * acquire the queue reference here.
925 *
926 * That's why we don't use blk_queue_enter here; instead, we use
927 * percpu_ref_tryget directly, because we need to be able to
928 * obtain a reference even in the short window between the queue
929 * starting to freeze, by dropping the first reference in
930 * blk_freeze_queue_start, and the moment the last request is
931 * consumed, marked by the instant q_usage_counter reaches
932 * zero.
933 */
934 if (!percpu_ref_tryget(&q->q_usage_counter))
935 return;
936
937 /* scan for the expired ones and set their ->aborted_gstate */
938 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
939
940 if (data.nr_expired) {
941 bool has_rcu = false;
942
943 /*
944 * Wait till everyone sees ->aborted_gstate. The
945 * sequential waits for SRCUs aren't ideal. If this ever
946 * becomes a problem, we can add per-hw_ctx rcu_head and
947 * wait in parallel.
948 */
949 queue_for_each_hw_ctx(q, hctx, i) {
950 if (!hctx->nr_expired)
951 continue;
952
953 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
954 has_rcu = true;
955 else
956 synchronize_srcu(hctx->srcu);
957
958 hctx->nr_expired = 0;
959 }
960 if (has_rcu)
961 synchronize_rcu();
962
963 /* terminate the ones we won */
964 blk_mq_queue_tag_busy_iter(q, blk_mq_terminate_expired, NULL);
965 }
966
967 if (data.next_set) {
968 data.next = blk_rq_timeout(round_jiffies_up(data.next));
969 mod_timer(&q->timeout, data.next);
970 } else {
971 /*
972 * Request timeouts are handled as a forward rolling timer. If
973 * we end up here it means that no requests are pending and
974 * also that no request has been pending for a while. Mark
975 * each hctx as idle.
976 */
977 queue_for_each_hw_ctx(q, hctx, i) {
978 /* the hctx may be unmapped, so check it here */
979 if (blk_mq_hw_queue_mapped(hctx))
980 blk_mq_tag_idle(hctx);
981 }
982 }
983 blk_queue_exit(q);
984}
985
986struct flush_busy_ctx_data {
987 struct blk_mq_hw_ctx *hctx;
988 struct list_head *list;
989};
990
991static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
992{
993 struct flush_busy_ctx_data *flush_data = data;
994 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
995 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
996
997 spin_lock(&ctx->lock);
998 list_splice_tail_init(&ctx->rq_list, flush_data->list);
999 sbitmap_clear_bit(sb, bitnr);
1000 spin_unlock(&ctx->lock);
1001 return true;
1002}
1003
1004/*
1005 * Process software queues that have been marked busy, splicing them
1006 * to the for-dispatch
1007 */
1008void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
1009{
1010 struct flush_busy_ctx_data data = {
1011 .hctx = hctx,
1012 .list = list,
1013 };
1014
1015 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
1016}
1017EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1018
1019struct dispatch_rq_data {
1020 struct blk_mq_hw_ctx *hctx;
1021 struct request *rq;
1022};
1023
1024static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1025 void *data)
1026{
1027 struct dispatch_rq_data *dispatch_data = data;
1028 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1029 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1030
1031 spin_lock(&ctx->lock);
1032 if (unlikely(!list_empty(&ctx->rq_list))) {
1033 dispatch_data->rq = list_entry_rq(ctx->rq_list.next);
1034 list_del_init(&dispatch_data->rq->queuelist);
1035 if (list_empty(&ctx->rq_list))
1036 sbitmap_clear_bit(sb, bitnr);
1037 }
1038 spin_unlock(&ctx->lock);
1039
1040 return !dispatch_data->rq;
1041}
1042
1043struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1044 struct blk_mq_ctx *start)
1045{
1046 unsigned off = start ? start->index_hw : 0;
1047 struct dispatch_rq_data data = {
1048 .hctx = hctx,
1049 .rq = NULL,
1050 };
1051
1052 __sbitmap_for_each_set(&hctx->ctx_map, off,
1053 dispatch_rq_from_ctx, &data);
1054
1055 return data.rq;
1056}
1057
1058static inline unsigned int queued_to_index(unsigned int queued)
1059{
1060 if (!queued)
1061 return 0;
1062
1063 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1064}
1065
1066bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
1067 bool wait)
1068{
1069 struct blk_mq_alloc_data data = {
1070 .q = rq->q,
1071 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
1072 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
1073 };
1074
1075 might_sleep_if(wait);
1076
1077 if (rq->tag != -1)
1078 goto done;
1079
1080 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
1081 data.flags |= BLK_MQ_REQ_RESERVED;
1082
1083 rq->tag = blk_mq_get_tag(&data);
1084 if (rq->tag >= 0) {
1085 if (blk_mq_tag_busy(data.hctx)) {
1086 rq->rq_flags |= RQF_MQ_INFLIGHT;
1087 atomic_inc(&data.hctx->nr_active);
1088 }
1089 data.hctx->tags->rqs[rq->tag] = rq;
1090 }
1091
1092done:
1093 if (hctx)
1094 *hctx = data.hctx;
1095 return rq->tag != -1;
1096}
1097
1098static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1099 int flags, void *key)
1100{
1101 struct blk_mq_hw_ctx *hctx;
1102
1103 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1104
1105 list_del_init(&wait->entry);
1106 blk_mq_run_hw_queue(hctx, true);
1107 return 1;
1108}
1109
1110/*
1111 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1112 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1113 * restart. For both cases, take care to check the condition again after
1114 * marking us as waiting.
1115 */
1116static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
1117 struct request *rq)
1118{
1119 struct blk_mq_hw_ctx *this_hctx = *hctx;
1120 struct sbq_wait_state *ws;
1121 wait_queue_entry_t *wait;
1122 bool ret;
1123
1124 if (!(this_hctx->flags & BLK_MQ_F_TAG_SHARED)) {
1125 if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state))
1126 set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state);
1127
1128 /*
1129 * It's possible that a tag was freed in the window between the
1130 * allocation failure and adding the hardware queue to the wait
1131 * queue.
1132 *
1133 * Don't clear RESTART here, someone else could have set it.
1134 * At most this will cost an extra queue run.
1135 */
1136 return blk_mq_get_driver_tag(rq, hctx, false);
1137 }
1138
1139 wait = &this_hctx->dispatch_wait;
1140 if (!list_empty_careful(&wait->entry))
1141 return false;
1142
1143 spin_lock(&this_hctx->lock);
1144 if (!list_empty(&wait->entry)) {
1145 spin_unlock(&this_hctx->lock);
1146 return false;
1147 }
1148
1149 ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx);
1150 add_wait_queue(&ws->wait, wait);
1151
1152 /*
1153 * It's possible that a tag was freed in the window between the
1154 * allocation failure and adding the hardware queue to the wait
1155 * queue.
1156 */
1157 ret = blk_mq_get_driver_tag(rq, hctx, false);
1158 if (!ret) {
1159 spin_unlock(&this_hctx->lock);
1160 return false;
1161 }
1162
1163 /*
1164 * We got a tag, remove ourselves from the wait queue to ensure
1165 * someone else gets the wakeup.
1166 */
1167 spin_lock_irq(&ws->wait.lock);
1168 list_del_init(&wait->entry);
1169 spin_unlock_irq(&ws->wait.lock);
1170 spin_unlock(&this_hctx->lock);
1171
1172 return true;
1173}
1174
1175#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1176
1177bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
1178 bool got_budget)
1179{
1180 struct blk_mq_hw_ctx *hctx;
1181 struct request *rq, *nxt;
1182 bool no_tag = false;
1183 int errors, queued;
1184 blk_status_t ret = BLK_STS_OK;
1185
1186 if (list_empty(list))
1187 return false;
1188
1189 WARN_ON(!list_is_singular(list) && got_budget);
1190
1191 /*
1192 * Now process all the entries, sending them to the driver.
1193 */
1194 errors = queued = 0;
1195 do {
1196 struct blk_mq_queue_data bd;
1197
1198 rq = list_first_entry(list, struct request, queuelist);
1199
1200 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
1201 if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
1202 break;
1203
1204 if (!blk_mq_get_driver_tag(rq, NULL, false)) {
1205 /*
1206 * The initial allocation attempt failed, so we need to
1207 * rerun the hardware queue when a tag is freed. The
1208 * waitqueue takes care of that. If the queue is run
1209 * before we add this entry back on the dispatch list,
1210 * we'll re-run it below.
1211 */
1212 if (!blk_mq_mark_tag_wait(&hctx, rq)) {
1213 blk_mq_put_dispatch_budget(hctx);
1214 /*
1215 * For non-shared tags, the RESTART check
1216 * will suffice.
1217 */
1218 if (hctx->flags & BLK_MQ_F_TAG_SHARED)
1219 no_tag = true;
1220 break;
1221 }
1222 }
1223
1224 list_del_init(&rq->queuelist);
1225
1226 bd.rq = rq;
1227
1228 /*
1229 * Flag last if we have no more requests, or if we have more
1230 * but can't assign a driver tag to it.
1231 */
1232 if (list_empty(list))
1233 bd.last = true;
1234 else {
1235 nxt = list_first_entry(list, struct request, queuelist);
1236 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1237 }
1238
1239 ret = q->mq_ops->queue_rq(hctx, &bd);
1240 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
1241 /*
1242 * If an I/O scheduler has been configured and we got a
1243 * driver tag for the next request already, free it
1244 * again.
1245 */
1246 if (!list_empty(list)) {
1247 nxt = list_first_entry(list, struct request, queuelist);
1248 blk_mq_put_driver_tag(nxt);
1249 }
1250 list_add(&rq->queuelist, list);
1251 __blk_mq_requeue_request(rq);
1252 break;
1253 }
1254
1255 if (unlikely(ret != BLK_STS_OK)) {
1256 errors++;
1257 blk_mq_end_request(rq, BLK_STS_IOERR);
1258 continue;
1259 }
1260
1261 queued++;
1262 } while (!list_empty(list));
1263
1264 hctx->dispatched[queued_to_index(queued)]++;
1265
1266 /*
1267 * Any items that need requeuing? Stuff them into hctx->dispatch,
1268 * that is where we will continue on next queue run.
1269 */
1270 if (!list_empty(list)) {
1271 bool needs_restart;
1272
1273 spin_lock(&hctx->lock);
1274 list_splice_init(list, &hctx->dispatch);
1275 spin_unlock(&hctx->lock);
1276
1277 /*
1278 * If SCHED_RESTART was set by the caller of this function and
1279 * it is no longer set that means that it was cleared by another
1280 * thread and hence that a queue rerun is needed.
1281 *
1282 * If 'no_tag' is set, that means that we failed getting
1283 * a driver tag with an I/O scheduler attached. If our dispatch
1284 * waitqueue is no longer active, ensure that we run the queue
1285 * AFTER adding our entries back to the list.
1286 *
1287 * If no I/O scheduler has been configured it is possible that
1288 * the hardware queue got stopped and restarted before requests
1289 * were pushed back onto the dispatch list. Rerun the queue to
1290 * avoid starvation. Notes:
1291 * - blk_mq_run_hw_queue() checks whether or not a queue has
1292 * been stopped before rerunning a queue.
1293 * - Some but not all block drivers stop a queue before
1294 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1295 * and dm-rq.
1296 *
1297 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1298 * bit is set, run queue after a delay to avoid IO stalls
1299 * that could otherwise occur if the queue is idle.
1300 */
1301 needs_restart = blk_mq_sched_needs_restart(hctx);
1302 if (!needs_restart ||
1303 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1304 blk_mq_run_hw_queue(hctx, true);
1305 else if (needs_restart && (ret == BLK_STS_RESOURCE))
1306 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1307 }
1308
1309 return (queued + errors) != 0;
1310}
1311
1312static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1313{
1314 int srcu_idx;
1315
1316 /*
1317 * We should be running this queue from one of the CPUs that
1318 * are mapped to it.
1319 *
1320 * There are at least two related races now between setting
1321 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1322 * __blk_mq_run_hw_queue():
1323 *
1324 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1325 * but later it becomes online, then this warning is harmless
1326 * at all
1327 *
1328 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1329 * but later it becomes offline, then the warning can't be
1330 * triggered, and we depend on blk-mq timeout handler to
1331 * handle dispatched requests to this hctx
1332 */
1333 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1334 cpu_online(hctx->next_cpu)) {
1335 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1336 raw_smp_processor_id(),
1337 cpumask_empty(hctx->cpumask) ? "inactive": "active");
1338 dump_stack();
1339 }
1340
1341 /*
1342 * We can't run the queue inline with ints disabled. Ensure that
1343 * we catch bad users of this early.
1344 */
1345 WARN_ON_ONCE(in_interrupt());
1346
1347 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1348
1349 hctx_lock(hctx, &srcu_idx);
1350 blk_mq_sched_dispatch_requests(hctx);
1351 hctx_unlock(hctx, srcu_idx);
1352}
1353
1354static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1355{
1356 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1357
1358 if (cpu >= nr_cpu_ids)
1359 cpu = cpumask_first(hctx->cpumask);
1360 return cpu;
1361}
1362
1363/*
1364 * It'd be great if the workqueue API had a way to pass
1365 * in a mask and had some smarts for more clever placement.
1366 * For now we just round-robin here, switching for every
1367 * BLK_MQ_CPU_WORK_BATCH queued items.
1368 */
1369static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1370{
1371 bool tried = false;
1372 int next_cpu = hctx->next_cpu;
1373
1374 if (hctx->queue->nr_hw_queues == 1)
1375 return WORK_CPU_UNBOUND;
1376
1377 if (--hctx->next_cpu_batch <= 0) {
1378select_cpu:
1379 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1380 cpu_online_mask);
1381 if (next_cpu >= nr_cpu_ids)
1382 next_cpu = blk_mq_first_mapped_cpu(hctx);
1383 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1384 }
1385
1386 /*
1387 * Do unbound schedule if we can't find a online CPU for this hctx,
1388 * and it should only happen in the path of handling CPU DEAD.
1389 */
1390 if (!cpu_online(next_cpu)) {
1391 if (!tried) {
1392 tried = true;
1393 goto select_cpu;
1394 }
1395
1396 /*
1397 * Make sure to re-select CPU next time once after CPUs
1398 * in hctx->cpumask become online again.
1399 */
1400 hctx->next_cpu = next_cpu;
1401 hctx->next_cpu_batch = 1;
1402 return WORK_CPU_UNBOUND;
1403 }
1404
1405 hctx->next_cpu = next_cpu;
1406 return next_cpu;
1407}
1408
1409static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1410 unsigned long msecs)
1411{
1412 if (unlikely(blk_mq_hctx_stopped(hctx)))
1413 return;
1414
1415 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1416 int cpu = get_cpu();
1417 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1418 __blk_mq_run_hw_queue(hctx);
1419 put_cpu();
1420 return;
1421 }
1422
1423 put_cpu();
1424 }
1425
1426 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1427 msecs_to_jiffies(msecs));
1428}
1429
1430void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1431{
1432 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1433}
1434EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1435
1436bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1437{
1438 int srcu_idx;
1439 bool need_run;
1440
1441 /*
1442 * When queue is quiesced, we may be switching io scheduler, or
1443 * updating nr_hw_queues, or other things, and we can't run queue
1444 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1445 *
1446 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1447 * quiesced.
1448 */
1449 hctx_lock(hctx, &srcu_idx);
1450 need_run = !blk_queue_quiesced(hctx->queue) &&
1451 blk_mq_hctx_has_pending(hctx);
1452 hctx_unlock(hctx, srcu_idx);
1453
1454 if (need_run) {
1455 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1456 return true;
1457 }
1458
1459 return false;
1460}
1461EXPORT_SYMBOL(blk_mq_run_hw_queue);
1462
1463void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1464{
1465 struct blk_mq_hw_ctx *hctx;
1466 int i;
1467
1468 queue_for_each_hw_ctx(q, hctx, i) {
1469 if (blk_mq_hctx_stopped(hctx))
1470 continue;
1471
1472 blk_mq_run_hw_queue(hctx, async);
1473 }
1474}
1475EXPORT_SYMBOL(blk_mq_run_hw_queues);
1476
1477/**
1478 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1479 * @q: request queue.
1480 *
1481 * The caller is responsible for serializing this function against
1482 * blk_mq_{start,stop}_hw_queue().
1483 */
1484bool blk_mq_queue_stopped(struct request_queue *q)
1485{
1486 struct blk_mq_hw_ctx *hctx;
1487 int i;
1488
1489 queue_for_each_hw_ctx(q, hctx, i)
1490 if (blk_mq_hctx_stopped(hctx))
1491 return true;
1492
1493 return false;
1494}
1495EXPORT_SYMBOL(blk_mq_queue_stopped);
1496
1497/*
1498 * This function is often used for pausing .queue_rq() by driver when
1499 * there isn't enough resource or some conditions aren't satisfied, and
1500 * BLK_STS_RESOURCE is usually returned.
1501 *
1502 * We do not guarantee that dispatch can be drained or blocked
1503 * after blk_mq_stop_hw_queue() returns. Please use
1504 * blk_mq_quiesce_queue() for that requirement.
1505 */
1506void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1507{
1508 cancel_delayed_work(&hctx->run_work);
1509
1510 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1511}
1512EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1513
1514/*
1515 * This function is often used for pausing .queue_rq() by driver when
1516 * there isn't enough resource or some conditions aren't satisfied, and
1517 * BLK_STS_RESOURCE is usually returned.
1518 *
1519 * We do not guarantee that dispatch can be drained or blocked
1520 * after blk_mq_stop_hw_queues() returns. Please use
1521 * blk_mq_quiesce_queue() for that requirement.
1522 */
1523void blk_mq_stop_hw_queues(struct request_queue *q)
1524{
1525 struct blk_mq_hw_ctx *hctx;
1526 int i;
1527
1528 queue_for_each_hw_ctx(q, hctx, i)
1529 blk_mq_stop_hw_queue(hctx);
1530}
1531EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1532
1533void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1534{
1535 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1536
1537 blk_mq_run_hw_queue(hctx, false);
1538}
1539EXPORT_SYMBOL(blk_mq_start_hw_queue);
1540
1541void blk_mq_start_hw_queues(struct request_queue *q)
1542{
1543 struct blk_mq_hw_ctx *hctx;
1544 int i;
1545
1546 queue_for_each_hw_ctx(q, hctx, i)
1547 blk_mq_start_hw_queue(hctx);
1548}
1549EXPORT_SYMBOL(blk_mq_start_hw_queues);
1550
1551void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1552{
1553 if (!blk_mq_hctx_stopped(hctx))
1554 return;
1555
1556 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1557 blk_mq_run_hw_queue(hctx, async);
1558}
1559EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1560
1561void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1562{
1563 struct blk_mq_hw_ctx *hctx;
1564 int i;
1565
1566 queue_for_each_hw_ctx(q, hctx, i)
1567 blk_mq_start_stopped_hw_queue(hctx, async);
1568}
1569EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1570
1571static void blk_mq_run_work_fn(struct work_struct *work)
1572{
1573 struct blk_mq_hw_ctx *hctx;
1574
1575 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1576
1577 /*
1578 * If we are stopped, don't run the queue.
1579 */
1580 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1581 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1582
1583 __blk_mq_run_hw_queue(hctx);
1584}
1585
1586static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1587 struct request *rq,
1588 bool at_head)
1589{
1590 struct blk_mq_ctx *ctx = rq->mq_ctx;
1591
1592 lockdep_assert_held(&ctx->lock);
1593
1594 trace_block_rq_insert(hctx->queue, rq);
1595
1596 if (at_head)
1597 list_add(&rq->queuelist, &ctx->rq_list);
1598 else
1599 list_add_tail(&rq->queuelist, &ctx->rq_list);
1600}
1601
1602void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1603 bool at_head)
1604{
1605 struct blk_mq_ctx *ctx = rq->mq_ctx;
1606
1607 lockdep_assert_held(&ctx->lock);
1608
1609 __blk_mq_insert_req_list(hctx, rq, at_head);
1610 blk_mq_hctx_mark_pending(hctx, ctx);
1611}
1612
1613/*
1614 * Should only be used carefully, when the caller knows we want to
1615 * bypass a potential IO scheduler on the target device.
1616 */
1617void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
1618{
1619 struct blk_mq_ctx *ctx = rq->mq_ctx;
1620 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
1621
1622 spin_lock(&hctx->lock);
1623 list_add_tail(&rq->queuelist, &hctx->dispatch);
1624 spin_unlock(&hctx->lock);
1625
1626 if (run_queue)
1627 blk_mq_run_hw_queue(hctx, false);
1628}
1629
1630void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1631 struct list_head *list)
1632
1633{
1634 /*
1635 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1636 * offline now
1637 */
1638 spin_lock(&ctx->lock);
1639 while (!list_empty(list)) {
1640 struct request *rq;
1641
1642 rq = list_first_entry(list, struct request, queuelist);
1643 BUG_ON(rq->mq_ctx != ctx);
1644 list_del_init(&rq->queuelist);
1645 __blk_mq_insert_req_list(hctx, rq, false);
1646 }
1647 blk_mq_hctx_mark_pending(hctx, ctx);
1648 spin_unlock(&ctx->lock);
1649}
1650
1651static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1652{
1653 struct request *rqa = container_of(a, struct request, queuelist);
1654 struct request *rqb = container_of(b, struct request, queuelist);
1655
1656 return !(rqa->mq_ctx < rqb->mq_ctx ||
1657 (rqa->mq_ctx == rqb->mq_ctx &&
1658 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1659}
1660
1661void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1662{
1663 struct blk_mq_ctx *this_ctx;
1664 struct request_queue *this_q;
1665 struct request *rq;
1666 LIST_HEAD(list);
1667 LIST_HEAD(ctx_list);
1668 unsigned int depth;
1669
1670 list_splice_init(&plug->mq_list, &list);
1671
1672 list_sort(NULL, &list, plug_ctx_cmp);
1673
1674 this_q = NULL;
1675 this_ctx = NULL;
1676 depth = 0;
1677
1678 while (!list_empty(&list)) {
1679 rq = list_entry_rq(list.next);
1680 list_del_init(&rq->queuelist);
1681 BUG_ON(!rq->q);
1682 if (rq->mq_ctx != this_ctx) {
1683 if (this_ctx) {
1684 trace_block_unplug(this_q, depth, from_schedule);
1685 blk_mq_sched_insert_requests(this_q, this_ctx,
1686 &ctx_list,
1687 from_schedule);
1688 }
1689
1690 this_ctx = rq->mq_ctx;
1691 this_q = rq->q;
1692 depth = 0;
1693 }
1694
1695 depth++;
1696 list_add_tail(&rq->queuelist, &ctx_list);
1697 }
1698
1699 /*
1700 * If 'this_ctx' is set, we know we have entries to complete
1701 * on 'ctx_list'. Do those.
1702 */
1703 if (this_ctx) {
1704 trace_block_unplug(this_q, depth, from_schedule);
1705 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1706 from_schedule);
1707 }
1708}
1709
1710static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1711{
1712 blk_init_request_from_bio(rq, bio);
1713
1714 blk_rq_set_rl(rq, blk_get_rl(rq->q, bio));
1715
1716 blk_account_io_start(rq, true);
1717}
1718
1719static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,
1720 struct blk_mq_ctx *ctx,
1721 struct request *rq)
1722{
1723 spin_lock(&ctx->lock);
1724 __blk_mq_insert_request(hctx, rq, false);
1725 spin_unlock(&ctx->lock);
1726}
1727
1728static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1729{
1730 if (rq->tag != -1)
1731 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1732
1733 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1734}
1735
1736static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1737 struct request *rq,
1738 blk_qc_t *cookie)
1739{
1740 struct request_queue *q = rq->q;
1741 struct blk_mq_queue_data bd = {
1742 .rq = rq,
1743 .last = true,
1744 };
1745 blk_qc_t new_cookie;
1746 blk_status_t ret;
1747
1748 new_cookie = request_to_qc_t(hctx, rq);
1749
1750 /*
1751 * For OK queue, we are done. For error, caller may kill it.
1752 * Any other error (busy), just add it to our list as we
1753 * previously would have done.
1754 */
1755 ret = q->mq_ops->queue_rq(hctx, &bd);
1756 switch (ret) {
1757 case BLK_STS_OK:
1758 *cookie = new_cookie;
1759 break;
1760 case BLK_STS_RESOURCE:
1761 case BLK_STS_DEV_RESOURCE:
1762 __blk_mq_requeue_request(rq);
1763 break;
1764 default:
1765 *cookie = BLK_QC_T_NONE;
1766 break;
1767 }
1768
1769 return ret;
1770}
1771
1772static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1773 struct request *rq,
1774 blk_qc_t *cookie,
1775 bool bypass_insert)
1776{
1777 struct request_queue *q = rq->q;
1778 bool run_queue = true;
1779
1780 /*
1781 * RCU or SRCU read lock is needed before checking quiesced flag.
1782 *
1783 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1784 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1785 * and avoid driver to try to dispatch again.
1786 */
1787 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1788 run_queue = false;
1789 bypass_insert = false;
1790 goto insert;
1791 }
1792
1793 if (q->elevator && !bypass_insert)
1794 goto insert;
1795
1796 if (!blk_mq_get_dispatch_budget(hctx))
1797 goto insert;
1798
1799 if (!blk_mq_get_driver_tag(rq, NULL, false)) {
1800 blk_mq_put_dispatch_budget(hctx);
1801 goto insert;
1802 }
1803
1804 return __blk_mq_issue_directly(hctx, rq, cookie);
1805insert:
1806 if (bypass_insert)
1807 return BLK_STS_RESOURCE;
1808
1809 blk_mq_sched_insert_request(rq, false, run_queue, false);
1810 return BLK_STS_OK;
1811}
1812
1813static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1814 struct request *rq, blk_qc_t *cookie)
1815{
1816 blk_status_t ret;
1817 int srcu_idx;
1818
1819 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1820
1821 hctx_lock(hctx, &srcu_idx);
1822
1823 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
1824 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1825 blk_mq_sched_insert_request(rq, false, true, false);
1826 else if (ret != BLK_STS_OK)
1827 blk_mq_end_request(rq, ret);
1828
1829 hctx_unlock(hctx, srcu_idx);
1830}
1831
1832blk_status_t blk_mq_request_issue_directly(struct request *rq)
1833{
1834 blk_status_t ret;
1835 int srcu_idx;
1836 blk_qc_t unused_cookie;
1837 struct blk_mq_ctx *ctx = rq->mq_ctx;
1838 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
1839
1840 hctx_lock(hctx, &srcu_idx);
1841 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true);
1842 hctx_unlock(hctx, srcu_idx);
1843
1844 return ret;
1845}
1846
1847static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1848{
1849 const int is_sync = op_is_sync(bio->bi_opf);
1850 const int is_flush_fua = op_is_flush(bio->bi_opf);
1851 struct blk_mq_alloc_data data = { .flags = 0 };
1852 struct request *rq;
1853 unsigned int request_count = 0;
1854 struct blk_plug *plug;
1855 struct request *same_queue_rq = NULL;
1856 blk_qc_t cookie;
1857 unsigned int wb_acct;
1858
1859 blk_queue_bounce(q, &bio);
1860
1861 blk_queue_split(q, &bio);
1862
1863 if (!bio_integrity_prep(bio))
1864 return BLK_QC_T_NONE;
1865
1866 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1867 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1868 return BLK_QC_T_NONE;
1869
1870 if (blk_mq_sched_bio_merge(q, bio))
1871 return BLK_QC_T_NONE;
1872
1873 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1874
1875 trace_block_getrq(q, bio, bio->bi_opf);
1876
1877 rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
1878 if (unlikely(!rq)) {
1879 __wbt_done(q->rq_wb, wb_acct);
1880 if (bio->bi_opf & REQ_NOWAIT)
1881 bio_wouldblock_error(bio);
1882 return BLK_QC_T_NONE;
1883 }
1884
1885 wbt_track(&rq->issue_stat, wb_acct);
1886
1887 cookie = request_to_qc_t(data.hctx, rq);
1888
1889 plug = current->plug;
1890 if (unlikely(is_flush_fua)) {
1891 blk_mq_put_ctx(data.ctx);
1892 blk_mq_bio_to_request(rq, bio);
1893
1894 /* bypass scheduler for flush rq */
1895 blk_insert_flush(rq);
1896 blk_mq_run_hw_queue(data.hctx, true);
1897 } else if (plug && q->nr_hw_queues == 1) {
1898 struct request *last = NULL;
1899
1900 blk_mq_put_ctx(data.ctx);
1901 blk_mq_bio_to_request(rq, bio);
1902
1903 /*
1904 * @request_count may become stale because of schedule
1905 * out, so check the list again.
1906 */
1907 if (list_empty(&plug->mq_list))
1908 request_count = 0;
1909 else if (blk_queue_nomerges(q))
1910 request_count = blk_plug_queued_count(q);
1911
1912 if (!request_count)
1913 trace_block_plug(q);
1914 else
1915 last = list_entry_rq(plug->mq_list.prev);
1916
1917 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1918 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1919 blk_flush_plug_list(plug, false);
1920 trace_block_plug(q);
1921 }
1922
1923 list_add_tail(&rq->queuelist, &plug->mq_list);
1924 } else if (plug && !blk_queue_nomerges(q)) {
1925 blk_mq_bio_to_request(rq, bio);
1926
1927 /*
1928 * We do limited plugging. If the bio can be merged, do that.
1929 * Otherwise the existing request in the plug list will be
1930 * issued. So the plug list will have one request at most
1931 * The plug list might get flushed before this. If that happens,
1932 * the plug list is empty, and same_queue_rq is invalid.
1933 */
1934 if (list_empty(&plug->mq_list))
1935 same_queue_rq = NULL;
1936 if (same_queue_rq)
1937 list_del_init(&same_queue_rq->queuelist);
1938 list_add_tail(&rq->queuelist, &plug->mq_list);
1939
1940 blk_mq_put_ctx(data.ctx);
1941
1942 if (same_queue_rq) {
1943 data.hctx = blk_mq_map_queue(q,
1944 same_queue_rq->mq_ctx->cpu);
1945 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1946 &cookie);
1947 }
1948 } else if (q->nr_hw_queues > 1 && is_sync) {
1949 blk_mq_put_ctx(data.ctx);
1950 blk_mq_bio_to_request(rq, bio);
1951 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1952 } else if (q->elevator) {
1953 blk_mq_put_ctx(data.ctx);
1954 blk_mq_bio_to_request(rq, bio);
1955 blk_mq_sched_insert_request(rq, false, true, true);
1956 } else {
1957 blk_mq_put_ctx(data.ctx);
1958 blk_mq_bio_to_request(rq, bio);
1959 blk_mq_queue_io(data.hctx, data.ctx, rq);
1960 blk_mq_run_hw_queue(data.hctx, true);
1961 }
1962
1963 return cookie;
1964}
1965
1966void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1967 unsigned int hctx_idx)
1968{
1969 struct page *page;
1970
1971 if (tags->rqs && set->ops->exit_request) {
1972 int i;
1973
1974 for (i = 0; i < tags->nr_tags; i++) {
1975 struct request *rq = tags->static_rqs[i];
1976
1977 if (!rq)
1978 continue;
1979 set->ops->exit_request(set, rq, hctx_idx);
1980 tags->static_rqs[i] = NULL;
1981 }
1982 }
1983
1984 while (!list_empty(&tags->page_list)) {
1985 page = list_first_entry(&tags->page_list, struct page, lru);
1986 list_del_init(&page->lru);
1987 /*
1988 * Remove kmemleak object previously allocated in
1989 * blk_mq_init_rq_map().
1990 */
1991 kmemleak_free(page_address(page));
1992 __free_pages(page, page->private);
1993 }
1994}
1995
1996void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1997{
1998 kfree(tags->rqs);
1999 tags->rqs = NULL;
2000 kfree(tags->static_rqs);
2001 tags->static_rqs = NULL;
2002
2003 blk_mq_free_tags(tags);
2004}
2005
2006struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2007 unsigned int hctx_idx,
2008 unsigned int nr_tags,
2009 unsigned int reserved_tags)
2010{
2011 struct blk_mq_tags *tags;
2012 int node;
2013
2014 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
2015 if (node == NUMA_NO_NODE)
2016 node = set->numa_node;
2017
2018 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
2019 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
2020 if (!tags)
2021 return NULL;
2022
2023 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
2024 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2025 node);
2026 if (!tags->rqs) {
2027 blk_mq_free_tags(tags);
2028 return NULL;
2029 }
2030
2031 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
2032 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2033 node);
2034 if (!tags->static_rqs) {
2035 kfree(tags->rqs);
2036 blk_mq_free_tags(tags);
2037 return NULL;
2038 }
2039
2040 return tags;
2041}
2042
2043static size_t order_to_size(unsigned int order)
2044{
2045 return (size_t)PAGE_SIZE << order;
2046}
2047
2048static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2049 unsigned int hctx_idx, int node)
2050{
2051 int ret;
2052
2053 if (set->ops->init_request) {
2054 ret = set->ops->init_request(set, rq, hctx_idx, node);
2055 if (ret)
2056 return ret;
2057 }
2058
2059 seqcount_init(&rq->gstate_seq);
2060 u64_stats_init(&rq->aborted_gstate_sync);
2061 /*
2062 * start gstate with gen 1 instead of 0, otherwise it will be equal
2063 * to aborted_gstate, and be identified timed out by
2064 * blk_mq_terminate_expired.
2065 */
2066 WRITE_ONCE(rq->gstate, MQ_RQ_GEN_INC);
2067
2068 return 0;
2069}
2070
2071int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2072 unsigned int hctx_idx, unsigned int depth)
2073{
2074 unsigned int i, j, entries_per_page, max_order = 4;
2075 size_t rq_size, left;
2076 int node;
2077
2078 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
2079 if (node == NUMA_NO_NODE)
2080 node = set->numa_node;
2081
2082 INIT_LIST_HEAD(&tags->page_list);
2083
2084 /*
2085 * rq_size is the size of the request plus driver payload, rounded
2086 * to the cacheline size
2087 */
2088 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2089 cache_line_size());
2090 left = rq_size * depth;
2091
2092 for (i = 0; i < depth; ) {
2093 int this_order = max_order;
2094 struct page *page;
2095 int to_do;
2096 void *p;
2097
2098 while (this_order && left < order_to_size(this_order - 1))
2099 this_order--;
2100
2101 do {
2102 page = alloc_pages_node(node,
2103 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2104 this_order);
2105 if (page)
2106 break;
2107 if (!this_order--)
2108 break;
2109 if (order_to_size(this_order) < rq_size)
2110 break;
2111 } while (1);
2112
2113 if (!page)
2114 goto fail;
2115
2116 page->private = this_order;
2117 list_add_tail(&page->lru, &tags->page_list);
2118
2119 p = page_address(page);
2120 /*
2121 * Allow kmemleak to scan these pages as they contain pointers
2122 * to additional allocations like via ops->init_request().
2123 */
2124 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2125 entries_per_page = order_to_size(this_order) / rq_size;
2126 to_do = min(entries_per_page, depth - i);
2127 left -= to_do * rq_size;
2128 for (j = 0; j < to_do; j++) {
2129 struct request *rq = p;
2130
2131 tags->static_rqs[i] = rq;
2132 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2133 tags->static_rqs[i] = NULL;
2134 goto fail;
2135 }
2136
2137 p += rq_size;
2138 i++;
2139 }
2140 }
2141 return 0;
2142
2143fail:
2144 blk_mq_free_rqs(set, tags, hctx_idx);
2145 return -ENOMEM;
2146}
2147
2148/*
2149 * 'cpu' is going away. splice any existing rq_list entries from this
2150 * software queue to the hw queue dispatch list, and ensure that it
2151 * gets run.
2152 */
2153static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2154{
2155 struct blk_mq_hw_ctx *hctx;
2156 struct blk_mq_ctx *ctx;
2157 LIST_HEAD(tmp);
2158
2159 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2160 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2161
2162 spin_lock(&ctx->lock);
2163 if (!list_empty(&ctx->rq_list)) {
2164 list_splice_init(&ctx->rq_list, &tmp);
2165 blk_mq_hctx_clear_pending(hctx, ctx);
2166 }
2167 spin_unlock(&ctx->lock);
2168
2169 if (list_empty(&tmp))
2170 return 0;
2171
2172 spin_lock(&hctx->lock);
2173 list_splice_tail_init(&tmp, &hctx->dispatch);
2174 spin_unlock(&hctx->lock);
2175
2176 blk_mq_run_hw_queue(hctx, true);
2177 return 0;
2178}
2179
2180static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2181{
2182 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2183 &hctx->cpuhp_dead);
2184}
2185
2186/* hctx->ctxs will be freed in queue's release handler */
2187static void blk_mq_exit_hctx(struct request_queue *q,
2188 struct blk_mq_tag_set *set,
2189 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2190{
2191 blk_mq_debugfs_unregister_hctx(hctx);
2192
2193 if (blk_mq_hw_queue_mapped(hctx))
2194 blk_mq_tag_idle(hctx);
2195
2196 if (set->ops->exit_request)
2197 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2198
2199 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2200
2201 if (set->ops->exit_hctx)
2202 set->ops->exit_hctx(hctx, hctx_idx);
2203
2204 if (hctx->flags & BLK_MQ_F_BLOCKING)
2205 cleanup_srcu_struct(hctx->srcu);
2206
2207 blk_mq_remove_cpuhp(hctx);
2208 blk_free_flush_queue(hctx->fq);
2209 sbitmap_free(&hctx->ctx_map);
2210}
2211
2212static void blk_mq_exit_hw_queues(struct request_queue *q,
2213 struct blk_mq_tag_set *set, int nr_queue)
2214{
2215 struct blk_mq_hw_ctx *hctx;
2216 unsigned int i;
2217
2218 queue_for_each_hw_ctx(q, hctx, i) {
2219 if (i == nr_queue)
2220 break;
2221 blk_mq_exit_hctx(q, set, hctx, i);
2222 }
2223}
2224
2225static int blk_mq_init_hctx(struct request_queue *q,
2226 struct blk_mq_tag_set *set,
2227 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2228{
2229 int node;
2230
2231 node = hctx->numa_node;
2232 if (node == NUMA_NO_NODE)
2233 node = hctx->numa_node = set->numa_node;
2234
2235 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2236 spin_lock_init(&hctx->lock);
2237 INIT_LIST_HEAD(&hctx->dispatch);
2238 hctx->queue = q;
2239 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
2240
2241 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2242
2243 hctx->tags = set->tags[hctx_idx];
2244
2245 /*
2246 * Allocate space for all possible cpus to avoid allocation at
2247 * runtime
2248 */
2249 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2250 GFP_KERNEL, node);
2251 if (!hctx->ctxs)
2252 goto unregister_cpu_notifier;
2253
2254 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
2255 node))
2256 goto free_ctxs;
2257
2258 hctx->nr_ctx = 0;
2259
2260 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2261 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2262
2263 if (set->ops->init_hctx &&
2264 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2265 goto free_bitmap;
2266
2267 if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
2268 goto exit_hctx;
2269
2270 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
2271 if (!hctx->fq)
2272 goto sched_exit_hctx;
2273
2274 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx, node))
2275 goto free_fq;
2276
2277 if (hctx->flags & BLK_MQ_F_BLOCKING)
2278 init_srcu_struct(hctx->srcu);
2279
2280 blk_mq_debugfs_register_hctx(q, hctx);
2281
2282 return 0;
2283
2284 free_fq:
2285 kfree(hctx->fq);
2286 sched_exit_hctx:
2287 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2288 exit_hctx:
2289 if (set->ops->exit_hctx)
2290 set->ops->exit_hctx(hctx, hctx_idx);
2291 free_bitmap:
2292 sbitmap_free(&hctx->ctx_map);
2293 free_ctxs:
2294 kfree(hctx->ctxs);
2295 unregister_cpu_notifier:
2296 blk_mq_remove_cpuhp(hctx);
2297 return -1;
2298}
2299
2300static void blk_mq_init_cpu_queues(struct request_queue *q,
2301 unsigned int nr_hw_queues)
2302{
2303 unsigned int i;
2304
2305 for_each_possible_cpu(i) {
2306 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2307 struct blk_mq_hw_ctx *hctx;
2308
2309 __ctx->cpu = i;
2310 spin_lock_init(&__ctx->lock);
2311 INIT_LIST_HEAD(&__ctx->rq_list);
2312 __ctx->queue = q;
2313
2314 /*
2315 * Set local node, IFF we have more than one hw queue. If
2316 * not, we remain on the home node of the device
2317 */
2318 hctx = blk_mq_map_queue(q, i);
2319 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2320 hctx->numa_node = local_memory_node(cpu_to_node(i));
2321 }
2322}
2323
2324static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2325{
2326 int ret = 0;
2327
2328 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2329 set->queue_depth, set->reserved_tags);
2330 if (!set->tags[hctx_idx])
2331 return false;
2332
2333 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2334 set->queue_depth);
2335 if (!ret)
2336 return true;
2337
2338 blk_mq_free_rq_map(set->tags[hctx_idx]);
2339 set->tags[hctx_idx] = NULL;
2340 return false;
2341}
2342
2343static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2344 unsigned int hctx_idx)
2345{
2346 if (set->tags[hctx_idx]) {
2347 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2348 blk_mq_free_rq_map(set->tags[hctx_idx]);
2349 set->tags[hctx_idx] = NULL;
2350 }
2351}
2352
2353static void blk_mq_map_swqueue(struct request_queue *q)
2354{
2355 unsigned int i, hctx_idx;
2356 struct blk_mq_hw_ctx *hctx;
2357 struct blk_mq_ctx *ctx;
2358 struct blk_mq_tag_set *set = q->tag_set;
2359
2360 /*
2361 * Avoid others reading imcomplete hctx->cpumask through sysfs
2362 */
2363 mutex_lock(&q->sysfs_lock);
2364
2365 queue_for_each_hw_ctx(q, hctx, i) {
2366 cpumask_clear(hctx->cpumask);
2367 hctx->nr_ctx = 0;
2368 }
2369
2370 /*
2371 * Map software to hardware queues.
2372 *
2373 * If the cpu isn't present, the cpu is mapped to first hctx.
2374 */
2375 for_each_possible_cpu(i) {
2376 hctx_idx = q->mq_map[i];
2377 /* unmapped hw queue can be remapped after CPU topo changed */
2378 if (!set->tags[hctx_idx] &&
2379 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2380 /*
2381 * If tags initialization fail for some hctx,
2382 * that hctx won't be brought online. In this
2383 * case, remap the current ctx to hctx[0] which
2384 * is guaranteed to always have tags allocated
2385 */
2386 q->mq_map[i] = 0;
2387 }
2388
2389 ctx = per_cpu_ptr(q->queue_ctx, i);
2390 hctx = blk_mq_map_queue(q, i);
2391
2392 cpumask_set_cpu(i, hctx->cpumask);
2393 ctx->index_hw = hctx->nr_ctx;
2394 hctx->ctxs[hctx->nr_ctx++] = ctx;
2395 }
2396
2397 mutex_unlock(&q->sysfs_lock);
2398
2399 queue_for_each_hw_ctx(q, hctx, i) {
2400 /*
2401 * If no software queues are mapped to this hardware queue,
2402 * disable it and free the request entries.
2403 */
2404 if (!hctx->nr_ctx) {
2405 /* Never unmap queue 0. We need it as a
2406 * fallback in case of a new remap fails
2407 * allocation
2408 */
2409 if (i && set->tags[i])
2410 blk_mq_free_map_and_requests(set, i);
2411
2412 hctx->tags = NULL;
2413 continue;
2414 }
2415
2416 hctx->tags = set->tags[i];
2417 WARN_ON(!hctx->tags);
2418
2419 /*
2420 * Set the map size to the number of mapped software queues.
2421 * This is more accurate and more efficient than looping
2422 * over all possibly mapped software queues.
2423 */
2424 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2425
2426 /*
2427 * Initialize batch roundrobin counts
2428 */
2429 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2430 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2431 }
2432}
2433
2434/*
2435 * Caller needs to ensure that we're either frozen/quiesced, or that
2436 * the queue isn't live yet.
2437 */
2438static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2439{
2440 struct blk_mq_hw_ctx *hctx;
2441 int i;
2442
2443 queue_for_each_hw_ctx(q, hctx, i) {
2444 if (shared) {
2445 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2446 atomic_inc(&q->shared_hctx_restart);
2447 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2448 } else {
2449 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2450 atomic_dec(&q->shared_hctx_restart);
2451 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2452 }
2453 }
2454}
2455
2456static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2457 bool shared)
2458{
2459 struct request_queue *q;
2460
2461 lockdep_assert_held(&set->tag_list_lock);
2462
2463 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2464 blk_mq_freeze_queue(q);
2465 queue_set_hctx_shared(q, shared);
2466 blk_mq_unfreeze_queue(q);
2467 }
2468}
2469
2470static void blk_mq_del_queue_tag_set(struct request_queue *q)
2471{
2472 struct blk_mq_tag_set *set = q->tag_set;
2473
2474 mutex_lock(&set->tag_list_lock);
2475 list_del_rcu(&q->tag_set_list);
2476 INIT_LIST_HEAD(&q->tag_set_list);
2477 if (list_is_singular(&set->tag_list)) {
2478 /* just transitioned to unshared */
2479 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2480 /* update existing queue */
2481 blk_mq_update_tag_set_depth(set, false);
2482 }
2483 mutex_unlock(&set->tag_list_lock);
2484
2485 synchronize_rcu();
2486}
2487
2488static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2489 struct request_queue *q)
2490{
2491 q->tag_set = set;
2492
2493 mutex_lock(&set->tag_list_lock);
2494
2495 /*
2496 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2497 */
2498 if (!list_empty(&set->tag_list) &&
2499 !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2500 set->flags |= BLK_MQ_F_TAG_SHARED;
2501 /* update existing queue */
2502 blk_mq_update_tag_set_depth(set, true);
2503 }
2504 if (set->flags & BLK_MQ_F_TAG_SHARED)
2505 queue_set_hctx_shared(q, true);
2506 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2507
2508 mutex_unlock(&set->tag_list_lock);
2509}
2510
2511/*
2512 * It is the actual release handler for mq, but we do it from
2513 * request queue's release handler for avoiding use-after-free
2514 * and headache because q->mq_kobj shouldn't have been introduced,
2515 * but we can't group ctx/kctx kobj without it.
2516 */
2517void blk_mq_release(struct request_queue *q)
2518{
2519 struct blk_mq_hw_ctx *hctx;
2520 unsigned int i;
2521
2522 /* hctx kobj stays in hctx */
2523 queue_for_each_hw_ctx(q, hctx, i) {
2524 if (!hctx)
2525 continue;
2526 kobject_put(&hctx->kobj);
2527 }
2528
2529 q->mq_map = NULL;
2530
2531 kfree(q->queue_hw_ctx);
2532
2533 /*
2534 * release .mq_kobj and sw queue's kobject now because
2535 * both share lifetime with request queue.
2536 */
2537 blk_mq_sysfs_deinit(q);
2538
2539 free_percpu(q->queue_ctx);
2540}
2541
2542struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2543{
2544 struct request_queue *uninit_q, *q;
2545
2546 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node, NULL);
2547 if (!uninit_q)
2548 return ERR_PTR(-ENOMEM);
2549
2550 q = blk_mq_init_allocated_queue(set, uninit_q);
2551 if (IS_ERR(q))
2552 blk_cleanup_queue(uninit_q);
2553
2554 return q;
2555}
2556EXPORT_SYMBOL(blk_mq_init_queue);
2557
2558static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2559{
2560 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2561
2562 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2563 __alignof__(struct blk_mq_hw_ctx)) !=
2564 sizeof(struct blk_mq_hw_ctx));
2565
2566 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2567 hw_ctx_size += sizeof(struct srcu_struct);
2568
2569 return hw_ctx_size;
2570}
2571
2572static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2573 struct request_queue *q)
2574{
2575 int i, j;
2576 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2577
2578 blk_mq_sysfs_unregister(q);
2579
2580 /* protect against switching io scheduler */
2581 mutex_lock(&q->sysfs_lock);
2582 for (i = 0; i < set->nr_hw_queues; i++) {
2583 int node;
2584
2585 if (hctxs[i])
2586 continue;
2587
2588 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2589 hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
2590 GFP_KERNEL, node);
2591 if (!hctxs[i])
2592 break;
2593
2594 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2595 node)) {
2596 kfree(hctxs[i]);
2597 hctxs[i] = NULL;
2598 break;
2599 }
2600
2601 atomic_set(&hctxs[i]->nr_active, 0);
2602 hctxs[i]->numa_node = node;
2603 hctxs[i]->queue_num = i;
2604
2605 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2606 free_cpumask_var(hctxs[i]->cpumask);
2607 kfree(hctxs[i]);
2608 hctxs[i] = NULL;
2609 break;
2610 }
2611 blk_mq_hctx_kobj_init(hctxs[i]);
2612 }
2613 for (j = i; j < q->nr_hw_queues; j++) {
2614 struct blk_mq_hw_ctx *hctx = hctxs[j];
2615
2616 if (hctx) {
2617 if (hctx->tags)
2618 blk_mq_free_map_and_requests(set, j);
2619 blk_mq_exit_hctx(q, set, hctx, j);
2620 kobject_put(&hctx->kobj);
2621 hctxs[j] = NULL;
2622
2623 }
2624 }
2625 q->nr_hw_queues = i;
2626 mutex_unlock(&q->sysfs_lock);
2627 blk_mq_sysfs_register(q);
2628}
2629
2630struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2631 struct request_queue *q)
2632{
2633 /* mark the queue as mq asap */
2634 q->mq_ops = set->ops;
2635
2636 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2637 blk_mq_poll_stats_bkt,
2638 BLK_MQ_POLL_STATS_BKTS, q);
2639 if (!q->poll_cb)
2640 goto err_exit;
2641
2642 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2643 if (!q->queue_ctx)
2644 goto err_exit;
2645
2646 /* init q->mq_kobj and sw queues' kobjects */
2647 blk_mq_sysfs_init(q);
2648
2649 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2650 GFP_KERNEL, set->numa_node);
2651 if (!q->queue_hw_ctx)
2652 goto err_percpu;
2653
2654 q->mq_map = set->mq_map;
2655
2656 blk_mq_realloc_hw_ctxs(set, q);
2657 if (!q->nr_hw_queues)
2658 goto err_hctxs;
2659
2660 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2661 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2662
2663 q->nr_queues = nr_cpu_ids;
2664
2665 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2666
2667 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2668 queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);
2669
2670 q->sg_reserved_size = INT_MAX;
2671
2672 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2673 INIT_LIST_HEAD(&q->requeue_list);
2674 spin_lock_init(&q->requeue_lock);
2675
2676 blk_queue_make_request(q, blk_mq_make_request);
2677 if (q->mq_ops->poll)
2678 q->poll_fn = blk_mq_poll;
2679
2680 /*
2681 * Do this after blk_queue_make_request() overrides it...
2682 */
2683 q->nr_requests = set->queue_depth;
2684
2685 /*
2686 * Default to classic polling
2687 */
2688 q->poll_nsec = -1;
2689
2690 if (set->ops->complete)
2691 blk_queue_softirq_done(q, set->ops->complete);
2692
2693 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2694 blk_mq_add_queue_tag_set(set, q);
2695 blk_mq_map_swqueue(q);
2696
2697 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2698 int ret;
2699
2700 ret = blk_mq_sched_init(q);
2701 if (ret)
2702 return ERR_PTR(ret);
2703 }
2704
2705 return q;
2706
2707err_hctxs:
2708 kfree(q->queue_hw_ctx);
2709err_percpu:
2710 free_percpu(q->queue_ctx);
2711err_exit:
2712 q->mq_ops = NULL;
2713 return ERR_PTR(-ENOMEM);
2714}
2715EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2716
2717void blk_mq_free_queue(struct request_queue *q)
2718{
2719 struct blk_mq_tag_set *set = q->tag_set;
2720
2721 blk_mq_del_queue_tag_set(q);
2722 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2723}
2724
2725/* Basically redo blk_mq_init_queue with queue frozen */
2726static void blk_mq_queue_reinit(struct request_queue *q)
2727{
2728 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2729
2730 blk_mq_debugfs_unregister_hctxs(q);
2731 blk_mq_sysfs_unregister(q);
2732
2733 /*
2734 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2735 * we should change hctx numa_node according to the new topology (this
2736 * involves freeing and re-allocating memory, worth doing?)
2737 */
2738 blk_mq_map_swqueue(q);
2739
2740 blk_mq_sysfs_register(q);
2741 blk_mq_debugfs_register_hctxs(q);
2742}
2743
2744static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2745{
2746 int i;
2747
2748 for (i = 0; i < set->nr_hw_queues; i++)
2749 if (!__blk_mq_alloc_rq_map(set, i))
2750 goto out_unwind;
2751
2752 return 0;
2753
2754out_unwind:
2755 while (--i >= 0)
2756 blk_mq_free_rq_map(set->tags[i]);
2757
2758 return -ENOMEM;
2759}
2760
2761/*
2762 * Allocate the request maps associated with this tag_set. Note that this
2763 * may reduce the depth asked for, if memory is tight. set->queue_depth
2764 * will be updated to reflect the allocated depth.
2765 */
2766static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2767{
2768 unsigned int depth;
2769 int err;
2770
2771 depth = set->queue_depth;
2772 do {
2773 err = __blk_mq_alloc_rq_maps(set);
2774 if (!err)
2775 break;
2776
2777 set->queue_depth >>= 1;
2778 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2779 err = -ENOMEM;
2780 break;
2781 }
2782 } while (set->queue_depth);
2783
2784 if (!set->queue_depth || err) {
2785 pr_err("blk-mq: failed to allocate request map\n");
2786 return -ENOMEM;
2787 }
2788
2789 if (depth != set->queue_depth)
2790 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2791 depth, set->queue_depth);
2792
2793 return 0;
2794}
2795
2796static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2797{
2798 if (set->ops->map_queues) {
2799 int cpu;
2800 /*
2801 * transport .map_queues is usually done in the following
2802 * way:
2803 *
2804 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2805 * mask = get_cpu_mask(queue)
2806 * for_each_cpu(cpu, mask)
2807 * set->mq_map[cpu] = queue;
2808 * }
2809 *
2810 * When we need to remap, the table has to be cleared for
2811 * killing stale mapping since one CPU may not be mapped
2812 * to any hw queue.
2813 */
2814 for_each_possible_cpu(cpu)
2815 set->mq_map[cpu] = 0;
2816
2817 return set->ops->map_queues(set);
2818 } else
2819 return blk_mq_map_queues(set);
2820}
2821
2822/*
2823 * Alloc a tag set to be associated with one or more request queues.
2824 * May fail with EINVAL for various error conditions. May adjust the
2825 * requested depth down, if if it too large. In that case, the set
2826 * value will be stored in set->queue_depth.
2827 */
2828int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2829{
2830 int ret;
2831
2832 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2833
2834 if (!set->nr_hw_queues)
2835 return -EINVAL;
2836 if (!set->queue_depth)
2837 return -EINVAL;
2838 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2839 return -EINVAL;
2840
2841 if (!set->ops->queue_rq)
2842 return -EINVAL;
2843
2844 if (!set->ops->get_budget ^ !set->ops->put_budget)
2845 return -EINVAL;
2846
2847 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2848 pr_info("blk-mq: reduced tag depth to %u\n",
2849 BLK_MQ_MAX_DEPTH);
2850 set->queue_depth = BLK_MQ_MAX_DEPTH;
2851 }
2852
2853 /*
2854 * If a crashdump is active, then we are potentially in a very
2855 * memory constrained environment. Limit us to 1 queue and
2856 * 64 tags to prevent using too much memory.
2857 */
2858 if (is_kdump_kernel()) {
2859 set->nr_hw_queues = 1;
2860 set->queue_depth = min(64U, set->queue_depth);
2861 }
2862 /*
2863 * There is no use for more h/w queues than cpus.
2864 */
2865 if (set->nr_hw_queues > nr_cpu_ids)
2866 set->nr_hw_queues = nr_cpu_ids;
2867
2868 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2869 GFP_KERNEL, set->numa_node);
2870 if (!set->tags)
2871 return -ENOMEM;
2872
2873 ret = -ENOMEM;
2874 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2875 GFP_KERNEL, set->numa_node);
2876 if (!set->mq_map)
2877 goto out_free_tags;
2878
2879 ret = blk_mq_update_queue_map(set);
2880 if (ret)
2881 goto out_free_mq_map;
2882
2883 ret = blk_mq_alloc_rq_maps(set);
2884 if (ret)
2885 goto out_free_mq_map;
2886
2887 mutex_init(&set->tag_list_lock);
2888 INIT_LIST_HEAD(&set->tag_list);
2889
2890 return 0;
2891
2892out_free_mq_map:
2893 kfree(set->mq_map);
2894 set->mq_map = NULL;
2895out_free_tags:
2896 kfree(set->tags);
2897 set->tags = NULL;
2898 return ret;
2899}
2900EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2901
2902void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2903{
2904 int i;
2905
2906 for (i = 0; i < nr_cpu_ids; i++)
2907 blk_mq_free_map_and_requests(set, i);
2908
2909 kfree(set->mq_map);
2910 set->mq_map = NULL;
2911
2912 kfree(set->tags);
2913 set->tags = NULL;
2914}
2915EXPORT_SYMBOL(blk_mq_free_tag_set);
2916
2917int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2918{
2919 struct blk_mq_tag_set *set = q->tag_set;
2920 struct blk_mq_hw_ctx *hctx;
2921 int i, ret;
2922
2923 if (!set)
2924 return -EINVAL;
2925
2926 blk_mq_freeze_queue(q);
2927 blk_mq_quiesce_queue(q);
2928
2929 ret = 0;
2930 queue_for_each_hw_ctx(q, hctx, i) {
2931 if (!hctx->tags)
2932 continue;
2933 /*
2934 * If we're using an MQ scheduler, just update the scheduler
2935 * queue depth. This is similar to what the old code would do.
2936 */
2937 if (!hctx->sched_tags) {
2938 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
2939 false);
2940 } else {
2941 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2942 nr, true);
2943 }
2944 if (ret)
2945 break;
2946 }
2947
2948 if (!ret)
2949 q->nr_requests = nr;
2950
2951 blk_mq_unquiesce_queue(q);
2952 blk_mq_unfreeze_queue(q);
2953
2954 return ret;
2955}
2956
2957static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
2958 int nr_hw_queues)
2959{
2960 struct request_queue *q;
2961
2962 lockdep_assert_held(&set->tag_list_lock);
2963
2964 if (nr_hw_queues > nr_cpu_ids)
2965 nr_hw_queues = nr_cpu_ids;
2966 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2967 return;
2968
2969 list_for_each_entry(q, &set->tag_list, tag_set_list)
2970 blk_mq_freeze_queue(q);
2971
2972 set->nr_hw_queues = nr_hw_queues;
2973 blk_mq_update_queue_map(set);
2974 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2975 blk_mq_realloc_hw_ctxs(set, q);
2976 blk_mq_queue_reinit(q);
2977 }
2978
2979 list_for_each_entry(q, &set->tag_list, tag_set_list)
2980 blk_mq_unfreeze_queue(q);
2981}
2982
2983void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2984{
2985 mutex_lock(&set->tag_list_lock);
2986 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
2987 mutex_unlock(&set->tag_list_lock);
2988}
2989EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2990
2991/* Enable polling stats and return whether they were already enabled. */
2992static bool blk_poll_stats_enable(struct request_queue *q)
2993{
2994 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2995 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
2996 return true;
2997 blk_stat_add_callback(q, q->poll_cb);
2998 return false;
2999}
3000
3001static void blk_mq_poll_stats_start(struct request_queue *q)
3002{
3003 /*
3004 * We don't arm the callback if polling stats are not enabled or the
3005 * callback is already active.
3006 */
3007 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3008 blk_stat_is_active(q->poll_cb))
3009 return;
3010
3011 blk_stat_activate_msecs(q->poll_cb, 100);
3012}
3013
3014static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3015{
3016 struct request_queue *q = cb->data;
3017 int bucket;
3018
3019 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3020 if (cb->stat[bucket].nr_samples)
3021 q->poll_stat[bucket] = cb->stat[bucket];
3022 }
3023}
3024
3025static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3026 struct blk_mq_hw_ctx *hctx,
3027 struct request *rq)
3028{
3029 unsigned long ret = 0;
3030 int bucket;
3031
3032 /*
3033 * If stats collection isn't on, don't sleep but turn it on for
3034 * future users
3035 */
3036 if (!blk_poll_stats_enable(q))
3037 return 0;
3038
3039 /*
3040 * As an optimistic guess, use half of the mean service time
3041 * for this type of request. We can (and should) make this smarter.
3042 * For instance, if the completion latencies are tight, we can
3043 * get closer than just half the mean. This is especially
3044 * important on devices where the completion latencies are longer
3045 * than ~10 usec. We do use the stats for the relevant IO size
3046 * if available which does lead to better estimates.
3047 */
3048 bucket = blk_mq_poll_stats_bkt(rq);
3049 if (bucket < 0)
3050 return ret;
3051
3052 if (q->poll_stat[bucket].nr_samples)
3053 ret = (q->poll_stat[bucket].mean + 1) / 2;
3054
3055 return ret;
3056}
3057
3058static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3059 struct blk_mq_hw_ctx *hctx,
3060 struct request *rq)
3061{
3062 struct hrtimer_sleeper hs;
3063 enum hrtimer_mode mode;
3064 unsigned int nsecs;
3065 ktime_t kt;
3066
3067 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3068 return false;
3069
3070 /*
3071 * poll_nsec can be:
3072 *
3073 * -1: don't ever hybrid sleep
3074 * 0: use half of prev avg
3075 * >0: use this specific value
3076 */
3077 if (q->poll_nsec == -1)
3078 return false;
3079 else if (q->poll_nsec > 0)
3080 nsecs = q->poll_nsec;
3081 else
3082 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
3083
3084 if (!nsecs)
3085 return false;
3086
3087 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3088
3089 /*
3090 * This will be replaced with the stats tracking code, using
3091 * 'avg_completion_time / 2' as the pre-sleep target.
3092 */
3093 kt = nsecs;
3094
3095 mode = HRTIMER_MODE_REL;
3096 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
3097 hrtimer_set_expires(&hs.timer, kt);
3098
3099 hrtimer_init_sleeper(&hs, current);
3100 do {
3101 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3102 break;
3103 set_current_state(TASK_UNINTERRUPTIBLE);
3104 hrtimer_start_expires(&hs.timer, mode);
3105 if (hs.task)
3106 io_schedule();
3107 hrtimer_cancel(&hs.timer);
3108 mode = HRTIMER_MODE_ABS;
3109 } while (hs.task && !signal_pending(current));
3110
3111 __set_current_state(TASK_RUNNING);
3112 destroy_hrtimer_on_stack(&hs.timer);
3113 return true;
3114}
3115
3116static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
3117{
3118 struct request_queue *q = hctx->queue;
3119 long state;
3120
3121 /*
3122 * If we sleep, have the caller restart the poll loop to reset
3123 * the state. Like for the other success return cases, the
3124 * caller is responsible for checking if the IO completed. If
3125 * the IO isn't complete, we'll get called again and will go
3126 * straight to the busy poll loop.
3127 */
3128 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
3129 return true;
3130
3131 hctx->poll_considered++;
3132
3133 state = current->state;
3134 while (!need_resched()) {
3135 int ret;
3136
3137 hctx->poll_invoked++;
3138
3139 ret = q->mq_ops->poll(hctx, rq->tag);
3140 if (ret > 0) {
3141 hctx->poll_success++;
3142 set_current_state(TASK_RUNNING);
3143 return true;
3144 }
3145
3146 if (signal_pending_state(state, current))
3147 set_current_state(TASK_RUNNING);
3148
3149 if (current->state == TASK_RUNNING)
3150 return true;
3151 if (ret < 0)
3152 break;
3153 cpu_relax();
3154 }
3155
3156 __set_current_state(TASK_RUNNING);
3157 return false;
3158}
3159
3160static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
3161{
3162 struct blk_mq_hw_ctx *hctx;
3163 struct request *rq;
3164
3165 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3166 return false;
3167
3168 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3169 if (!blk_qc_t_is_internal(cookie))
3170 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3171 else {
3172 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3173 /*
3174 * With scheduling, if the request has completed, we'll
3175 * get a NULL return here, as we clear the sched tag when
3176 * that happens. The request still remains valid, like always,
3177 * so we should be safe with just the NULL check.
3178 */
3179 if (!rq)
3180 return false;
3181 }
3182
3183 return __blk_mq_poll(hctx, rq);
3184}
3185
3186static int __init blk_mq_init(void)
3187{
3188 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3189 blk_mq_hctx_notify_dead);
3190 return 0;
3191}
3192subsys_initcall(blk_mq_init);