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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
4 * for the blk-mq scheduling framework
5 *
6 * Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
7 */
8#include <linux/kernel.h>
9#include <linux/fs.h>
10#include <linux/blkdev.h>
11#include <linux/blk-mq.h>
12#include <linux/bio.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/init.h>
16#include <linux/compiler.h>
17#include <linux/rbtree.h>
18#include <linux/sbitmap.h>
19
20#include <trace/events/block.h>
21
22#include "elevator.h"
23#include "blk.h"
24#include "blk-mq.h"
25#include "blk-mq-debugfs.h"
26#include "blk-mq-tag.h"
27#include "blk-mq-sched.h"
28
29/*
30 * See Documentation/block/deadline-iosched.rst
31 */
32static const int read_expire = HZ / 2; /* max time before a read is submitted. */
33static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
34/*
35 * Time after which to dispatch lower priority requests even if higher
36 * priority requests are pending.
37 */
38static const int prio_aging_expire = 10 * HZ;
39static const int writes_starved = 2; /* max times reads can starve a write */
40static const int fifo_batch = 16; /* # of sequential requests treated as one
41 by the above parameters. For throughput. */
42
43enum dd_data_dir {
44 DD_READ = READ,
45 DD_WRITE = WRITE,
46};
47
48enum { DD_DIR_COUNT = 2 };
49
50enum dd_prio {
51 DD_RT_PRIO = 0,
52 DD_BE_PRIO = 1,
53 DD_IDLE_PRIO = 2,
54 DD_PRIO_MAX = 2,
55};
56
57enum { DD_PRIO_COUNT = 3 };
58
59/*
60 * I/O statistics per I/O priority. It is fine if these counters overflow.
61 * What matters is that these counters are at least as wide as
62 * log2(max_outstanding_requests).
63 */
64struct io_stats_per_prio {
65 uint32_t inserted;
66 uint32_t merged;
67 uint32_t dispatched;
68 atomic_t completed;
69};
70
71/*
72 * Deadline scheduler data per I/O priority (enum dd_prio). Requests are
73 * present on both sort_list[] and fifo_list[].
74 */
75struct dd_per_prio {
76 struct list_head dispatch;
77 struct rb_root sort_list[DD_DIR_COUNT];
78 struct list_head fifo_list[DD_DIR_COUNT];
79 /* Next request in FIFO order. Read, write or both are NULL. */
80 struct request *next_rq[DD_DIR_COUNT];
81 struct io_stats_per_prio stats;
82};
83
84struct deadline_data {
85 /*
86 * run time data
87 */
88
89 struct dd_per_prio per_prio[DD_PRIO_COUNT];
90
91 /* Data direction of latest dispatched request. */
92 enum dd_data_dir last_dir;
93 unsigned int batching; /* number of sequential requests made */
94 unsigned int starved; /* times reads have starved writes */
95
96 /*
97 * settings that change how the i/o scheduler behaves
98 */
99 int fifo_expire[DD_DIR_COUNT];
100 int fifo_batch;
101 int writes_starved;
102 int front_merges;
103 u32 async_depth;
104 int prio_aging_expire;
105
106 spinlock_t lock;
107 spinlock_t zone_lock;
108};
109
110/* Maps an I/O priority class to a deadline scheduler priority. */
111static const enum dd_prio ioprio_class_to_prio[] = {
112 [IOPRIO_CLASS_NONE] = DD_BE_PRIO,
113 [IOPRIO_CLASS_RT] = DD_RT_PRIO,
114 [IOPRIO_CLASS_BE] = DD_BE_PRIO,
115 [IOPRIO_CLASS_IDLE] = DD_IDLE_PRIO,
116};
117
118static inline struct rb_root *
119deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)
120{
121 return &per_prio->sort_list[rq_data_dir(rq)];
122}
123
124/*
125 * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
126 * request.
127 */
128static u8 dd_rq_ioclass(struct request *rq)
129{
130 return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
131}
132
133/*
134 * get the request before `rq' in sector-sorted order
135 */
136static inline struct request *
137deadline_earlier_request(struct request *rq)
138{
139 struct rb_node *node = rb_prev(&rq->rb_node);
140
141 if (node)
142 return rb_entry_rq(node);
143
144 return NULL;
145}
146
147/*
148 * get the request after `rq' in sector-sorted order
149 */
150static inline struct request *
151deadline_latter_request(struct request *rq)
152{
153 struct rb_node *node = rb_next(&rq->rb_node);
154
155 if (node)
156 return rb_entry_rq(node);
157
158 return NULL;
159}
160
161static void
162deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
163{
164 struct rb_root *root = deadline_rb_root(per_prio, rq);
165
166 elv_rb_add(root, rq);
167}
168
169static inline void
170deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
171{
172 const enum dd_data_dir data_dir = rq_data_dir(rq);
173
174 if (per_prio->next_rq[data_dir] == rq)
175 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
176
177 elv_rb_del(deadline_rb_root(per_prio, rq), rq);
178}
179
180/*
181 * remove rq from rbtree and fifo.
182 */
183static void deadline_remove_request(struct request_queue *q,
184 struct dd_per_prio *per_prio,
185 struct request *rq)
186{
187 list_del_init(&rq->queuelist);
188
189 /*
190 * We might not be on the rbtree, if we are doing an insert merge
191 */
192 if (!RB_EMPTY_NODE(&rq->rb_node))
193 deadline_del_rq_rb(per_prio, rq);
194
195 elv_rqhash_del(q, rq);
196 if (q->last_merge == rq)
197 q->last_merge = NULL;
198}
199
200static void dd_request_merged(struct request_queue *q, struct request *req,
201 enum elv_merge type)
202{
203 struct deadline_data *dd = q->elevator->elevator_data;
204 const u8 ioprio_class = dd_rq_ioclass(req);
205 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
206 struct dd_per_prio *per_prio = &dd->per_prio[prio];
207
208 /*
209 * if the merge was a front merge, we need to reposition request
210 */
211 if (type == ELEVATOR_FRONT_MERGE) {
212 elv_rb_del(deadline_rb_root(per_prio, req), req);
213 deadline_add_rq_rb(per_prio, req);
214 }
215}
216
217/*
218 * Callback function that is invoked after @next has been merged into @req.
219 */
220static void dd_merged_requests(struct request_queue *q, struct request *req,
221 struct request *next)
222{
223 struct deadline_data *dd = q->elevator->elevator_data;
224 const u8 ioprio_class = dd_rq_ioclass(next);
225 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
226
227 lockdep_assert_held(&dd->lock);
228
229 dd->per_prio[prio].stats.merged++;
230
231 /*
232 * if next expires before rq, assign its expire time to rq
233 * and move into next position (next will be deleted) in fifo
234 */
235 if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
236 if (time_before((unsigned long)next->fifo_time,
237 (unsigned long)req->fifo_time)) {
238 list_move(&req->queuelist, &next->queuelist);
239 req->fifo_time = next->fifo_time;
240 }
241 }
242
243 /*
244 * kill knowledge of next, this one is a goner
245 */
246 deadline_remove_request(q, &dd->per_prio[prio], next);
247}
248
249/*
250 * move an entry to dispatch queue
251 */
252static void
253deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
254 struct request *rq)
255{
256 const enum dd_data_dir data_dir = rq_data_dir(rq);
257
258 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
259
260 /*
261 * take it off the sort and fifo list
262 */
263 deadline_remove_request(rq->q, per_prio, rq);
264}
265
266/* Number of requests queued for a given priority level. */
267static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
268{
269 const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
270
271 lockdep_assert_held(&dd->lock);
272
273 return stats->inserted - atomic_read(&stats->completed);
274}
275
276/*
277 * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
278 * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
279 */
280static inline int deadline_check_fifo(struct dd_per_prio *per_prio,
281 enum dd_data_dir data_dir)
282{
283 struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
284
285 /*
286 * rq is expired!
287 */
288 if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
289 return 1;
290
291 return 0;
292}
293
294/*
295 * Check if rq has a sequential request preceding it.
296 */
297static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq)
298{
299 struct request *prev = deadline_earlier_request(rq);
300
301 if (!prev)
302 return false;
303
304 return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq);
305}
306
307/*
308 * Skip all write requests that are sequential from @rq, even if we cross
309 * a zone boundary.
310 */
311static struct request *deadline_skip_seq_writes(struct deadline_data *dd,
312 struct request *rq)
313{
314 sector_t pos = blk_rq_pos(rq);
315 sector_t skipped_sectors = 0;
316
317 while (rq) {
318 if (blk_rq_pos(rq) != pos + skipped_sectors)
319 break;
320 skipped_sectors += blk_rq_sectors(rq);
321 rq = deadline_latter_request(rq);
322 }
323
324 return rq;
325}
326
327/*
328 * For the specified data direction, return the next request to
329 * dispatch using arrival ordered lists.
330 */
331static struct request *
332deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
333 enum dd_data_dir data_dir)
334{
335 struct request *rq;
336 unsigned long flags;
337
338 if (list_empty(&per_prio->fifo_list[data_dir]))
339 return NULL;
340
341 rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
342 if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
343 return rq;
344
345 /*
346 * Look for a write request that can be dispatched, that is one with
347 * an unlocked target zone. For some HDDs, breaking a sequential
348 * write stream can lead to lower throughput, so make sure to preserve
349 * sequential write streams, even if that stream crosses into the next
350 * zones and these zones are unlocked.
351 */
352 spin_lock_irqsave(&dd->zone_lock, flags);
353 list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {
354 if (blk_req_can_dispatch_to_zone(rq) &&
355 (blk_queue_nonrot(rq->q) ||
356 !deadline_is_seq_write(dd, rq)))
357 goto out;
358 }
359 rq = NULL;
360out:
361 spin_unlock_irqrestore(&dd->zone_lock, flags);
362
363 return rq;
364}
365
366/*
367 * For the specified data direction, return the next request to
368 * dispatch using sector position sorted lists.
369 */
370static struct request *
371deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
372 enum dd_data_dir data_dir)
373{
374 struct request *rq;
375 unsigned long flags;
376
377 rq = per_prio->next_rq[data_dir];
378 if (!rq)
379 return NULL;
380
381 if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
382 return rq;
383
384 /*
385 * Look for a write request that can be dispatched, that is one with
386 * an unlocked target zone. For some HDDs, breaking a sequential
387 * write stream can lead to lower throughput, so make sure to preserve
388 * sequential write streams, even if that stream crosses into the next
389 * zones and these zones are unlocked.
390 */
391 spin_lock_irqsave(&dd->zone_lock, flags);
392 while (rq) {
393 if (blk_req_can_dispatch_to_zone(rq))
394 break;
395 if (blk_queue_nonrot(rq->q))
396 rq = deadline_latter_request(rq);
397 else
398 rq = deadline_skip_seq_writes(dd, rq);
399 }
400 spin_unlock_irqrestore(&dd->zone_lock, flags);
401
402 return rq;
403}
404
405/*
406 * Returns true if and only if @rq started after @latest_start where
407 * @latest_start is in jiffies.
408 */
409static bool started_after(struct deadline_data *dd, struct request *rq,
410 unsigned long latest_start)
411{
412 unsigned long start_time = (unsigned long)rq->fifo_time;
413
414 start_time -= dd->fifo_expire[rq_data_dir(rq)];
415
416 return time_after(start_time, latest_start);
417}
418
419/*
420 * deadline_dispatch_requests selects the best request according to
421 * read/write expire, fifo_batch, etc and with a start time <= @latest_start.
422 */
423static struct request *__dd_dispatch_request(struct deadline_data *dd,
424 struct dd_per_prio *per_prio,
425 unsigned long latest_start)
426{
427 struct request *rq, *next_rq;
428 enum dd_data_dir data_dir;
429 enum dd_prio prio;
430 u8 ioprio_class;
431
432 lockdep_assert_held(&dd->lock);
433
434 if (!list_empty(&per_prio->dispatch)) {
435 rq = list_first_entry(&per_prio->dispatch, struct request,
436 queuelist);
437 if (started_after(dd, rq, latest_start))
438 return NULL;
439 list_del_init(&rq->queuelist);
440 goto done;
441 }
442
443 /*
444 * batches are currently reads XOR writes
445 */
446 rq = deadline_next_request(dd, per_prio, dd->last_dir);
447 if (rq && dd->batching < dd->fifo_batch)
448 /* we have a next request are still entitled to batch */
449 goto dispatch_request;
450
451 /*
452 * at this point we are not running a batch. select the appropriate
453 * data direction (read / write)
454 */
455
456 if (!list_empty(&per_prio->fifo_list[DD_READ])) {
457 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));
458
459 if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&
460 (dd->starved++ >= dd->writes_starved))
461 goto dispatch_writes;
462
463 data_dir = DD_READ;
464
465 goto dispatch_find_request;
466 }
467
468 /*
469 * there are either no reads or writes have been starved
470 */
471
472 if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {
473dispatch_writes:
474 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));
475
476 dd->starved = 0;
477
478 data_dir = DD_WRITE;
479
480 goto dispatch_find_request;
481 }
482
483 return NULL;
484
485dispatch_find_request:
486 /*
487 * we are not running a batch, find best request for selected data_dir
488 */
489 next_rq = deadline_next_request(dd, per_prio, data_dir);
490 if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {
491 /*
492 * A deadline has expired, the last request was in the other
493 * direction, or we have run out of higher-sectored requests.
494 * Start again from the request with the earliest expiry time.
495 */
496 rq = deadline_fifo_request(dd, per_prio, data_dir);
497 } else {
498 /*
499 * The last req was the same dir and we have a next request in
500 * sort order. No expired requests so continue on from here.
501 */
502 rq = next_rq;
503 }
504
505 /*
506 * For a zoned block device, if we only have writes queued and none of
507 * them can be dispatched, rq will be NULL.
508 */
509 if (!rq)
510 return NULL;
511
512 dd->last_dir = data_dir;
513 dd->batching = 0;
514
515dispatch_request:
516 if (started_after(dd, rq, latest_start))
517 return NULL;
518
519 /*
520 * rq is the selected appropriate request.
521 */
522 dd->batching++;
523 deadline_move_request(dd, per_prio, rq);
524done:
525 ioprio_class = dd_rq_ioclass(rq);
526 prio = ioprio_class_to_prio[ioprio_class];
527 dd->per_prio[prio].stats.dispatched++;
528 /*
529 * If the request needs its target zone locked, do it.
530 */
531 blk_req_zone_write_lock(rq);
532 rq->rq_flags |= RQF_STARTED;
533 return rq;
534}
535
536/*
537 * Check whether there are any requests with priority other than DD_RT_PRIO
538 * that were inserted more than prio_aging_expire jiffies ago.
539 */
540static struct request *dd_dispatch_prio_aged_requests(struct deadline_data *dd,
541 unsigned long now)
542{
543 struct request *rq;
544 enum dd_prio prio;
545 int prio_cnt;
546
547 lockdep_assert_held(&dd->lock);
548
549 prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, DD_BE_PRIO) +
550 !!dd_queued(dd, DD_IDLE_PRIO);
551 if (prio_cnt < 2)
552 return NULL;
553
554 for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) {
555 rq = __dd_dispatch_request(dd, &dd->per_prio[prio],
556 now - dd->prio_aging_expire);
557 if (rq)
558 return rq;
559 }
560
561 return NULL;
562}
563
564/*
565 * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
566 *
567 * One confusing aspect here is that we get called for a specific
568 * hardware queue, but we may return a request that is for a
569 * different hardware queue. This is because mq-deadline has shared
570 * state for all hardware queues, in terms of sorting, FIFOs, etc.
571 */
572static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
573{
574 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
575 const unsigned long now = jiffies;
576 struct request *rq;
577 enum dd_prio prio;
578
579 spin_lock(&dd->lock);
580 rq = dd_dispatch_prio_aged_requests(dd, now);
581 if (rq)
582 goto unlock;
583
584 /*
585 * Next, dispatch requests in priority order. Ignore lower priority
586 * requests if any higher priority requests are pending.
587 */
588 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
589 rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now);
590 if (rq || dd_queued(dd, prio))
591 break;
592 }
593
594unlock:
595 spin_unlock(&dd->lock);
596
597 return rq;
598}
599
600/*
601 * Called by __blk_mq_alloc_request(). The shallow_depth value set by this
602 * function is used by __blk_mq_get_tag().
603 */
604static void dd_limit_depth(blk_opf_t opf, struct blk_mq_alloc_data *data)
605{
606 struct deadline_data *dd = data->q->elevator->elevator_data;
607
608 /* Do not throttle synchronous reads. */
609 if (op_is_sync(opf) && !op_is_write(opf))
610 return;
611
612 /*
613 * Throttle asynchronous requests and writes such that these requests
614 * do not block the allocation of synchronous requests.
615 */
616 data->shallow_depth = dd->async_depth;
617}
618
619/* Called by blk_mq_update_nr_requests(). */
620static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
621{
622 struct request_queue *q = hctx->queue;
623 struct deadline_data *dd = q->elevator->elevator_data;
624 struct blk_mq_tags *tags = hctx->sched_tags;
625
626 dd->async_depth = max(1UL, 3 * q->nr_requests / 4);
627
628 sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, dd->async_depth);
629}
630
631/* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
632static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
633{
634 dd_depth_updated(hctx);
635 return 0;
636}
637
638static void dd_exit_sched(struct elevator_queue *e)
639{
640 struct deadline_data *dd = e->elevator_data;
641 enum dd_prio prio;
642
643 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
644 struct dd_per_prio *per_prio = &dd->per_prio[prio];
645 const struct io_stats_per_prio *stats = &per_prio->stats;
646 uint32_t queued;
647
648 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
649 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
650
651 spin_lock(&dd->lock);
652 queued = dd_queued(dd, prio);
653 spin_unlock(&dd->lock);
654
655 WARN_ONCE(queued != 0,
656 "statistics for priority %d: i %u m %u d %u c %u\n",
657 prio, stats->inserted, stats->merged,
658 stats->dispatched, atomic_read(&stats->completed));
659 }
660
661 kfree(dd);
662}
663
664/*
665 * initialize elevator private data (deadline_data).
666 */
667static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
668{
669 struct deadline_data *dd;
670 struct elevator_queue *eq;
671 enum dd_prio prio;
672 int ret = -ENOMEM;
673
674 eq = elevator_alloc(q, e);
675 if (!eq)
676 return ret;
677
678 dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
679 if (!dd)
680 goto put_eq;
681
682 eq->elevator_data = dd;
683
684 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
685 struct dd_per_prio *per_prio = &dd->per_prio[prio];
686
687 INIT_LIST_HEAD(&per_prio->dispatch);
688 INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]);
689 INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]);
690 per_prio->sort_list[DD_READ] = RB_ROOT;
691 per_prio->sort_list[DD_WRITE] = RB_ROOT;
692 }
693 dd->fifo_expire[DD_READ] = read_expire;
694 dd->fifo_expire[DD_WRITE] = write_expire;
695 dd->writes_starved = writes_starved;
696 dd->front_merges = 1;
697 dd->last_dir = DD_WRITE;
698 dd->fifo_batch = fifo_batch;
699 dd->prio_aging_expire = prio_aging_expire;
700 spin_lock_init(&dd->lock);
701 spin_lock_init(&dd->zone_lock);
702
703 /* We dispatch from request queue wide instead of hw queue */
704 blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q);
705
706 q->elevator = eq;
707 return 0;
708
709put_eq:
710 kobject_put(&eq->kobj);
711 return ret;
712}
713
714/*
715 * Try to merge @bio into an existing request. If @bio has been merged into
716 * an existing request, store the pointer to that request into *@rq.
717 */
718static int dd_request_merge(struct request_queue *q, struct request **rq,
719 struct bio *bio)
720{
721 struct deadline_data *dd = q->elevator->elevator_data;
722 const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
723 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
724 struct dd_per_prio *per_prio = &dd->per_prio[prio];
725 sector_t sector = bio_end_sector(bio);
726 struct request *__rq;
727
728 if (!dd->front_merges)
729 return ELEVATOR_NO_MERGE;
730
731 __rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector);
732 if (__rq) {
733 BUG_ON(sector != blk_rq_pos(__rq));
734
735 if (elv_bio_merge_ok(__rq, bio)) {
736 *rq = __rq;
737 if (blk_discard_mergable(__rq))
738 return ELEVATOR_DISCARD_MERGE;
739 return ELEVATOR_FRONT_MERGE;
740 }
741 }
742
743 return ELEVATOR_NO_MERGE;
744}
745
746/*
747 * Attempt to merge a bio into an existing request. This function is called
748 * before @bio is associated with a request.
749 */
750static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
751 unsigned int nr_segs)
752{
753 struct deadline_data *dd = q->elevator->elevator_data;
754 struct request *free = NULL;
755 bool ret;
756
757 spin_lock(&dd->lock);
758 ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
759 spin_unlock(&dd->lock);
760
761 if (free)
762 blk_mq_free_request(free);
763
764 return ret;
765}
766
767/*
768 * add rq to rbtree and fifo
769 */
770static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
771 bool at_head)
772{
773 struct request_queue *q = hctx->queue;
774 struct deadline_data *dd = q->elevator->elevator_data;
775 const enum dd_data_dir data_dir = rq_data_dir(rq);
776 u16 ioprio = req_get_ioprio(rq);
777 u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
778 struct dd_per_prio *per_prio;
779 enum dd_prio prio;
780 LIST_HEAD(free);
781
782 lockdep_assert_held(&dd->lock);
783
784 /*
785 * This may be a requeue of a write request that has locked its
786 * target zone. If it is the case, this releases the zone lock.
787 */
788 blk_req_zone_write_unlock(rq);
789
790 prio = ioprio_class_to_prio[ioprio_class];
791 per_prio = &dd->per_prio[prio];
792 if (!rq->elv.priv[0]) {
793 per_prio->stats.inserted++;
794 rq->elv.priv[0] = (void *)(uintptr_t)1;
795 }
796
797 if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
798 blk_mq_free_requests(&free);
799 return;
800 }
801
802 trace_block_rq_insert(rq);
803
804 if (at_head) {
805 list_add(&rq->queuelist, &per_prio->dispatch);
806 rq->fifo_time = jiffies;
807 } else {
808 deadline_add_rq_rb(per_prio, rq);
809
810 if (rq_mergeable(rq)) {
811 elv_rqhash_add(q, rq);
812 if (!q->last_merge)
813 q->last_merge = rq;
814 }
815
816 /*
817 * set expire time and add to fifo list
818 */
819 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
820 list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
821 }
822}
823
824/*
825 * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests().
826 */
827static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
828 struct list_head *list, bool at_head)
829{
830 struct request_queue *q = hctx->queue;
831 struct deadline_data *dd = q->elevator->elevator_data;
832
833 spin_lock(&dd->lock);
834 while (!list_empty(list)) {
835 struct request *rq;
836
837 rq = list_first_entry(list, struct request, queuelist);
838 list_del_init(&rq->queuelist);
839 dd_insert_request(hctx, rq, at_head);
840 }
841 spin_unlock(&dd->lock);
842}
843
844/* Callback from inside blk_mq_rq_ctx_init(). */
845static void dd_prepare_request(struct request *rq)
846{
847 rq->elv.priv[0] = NULL;
848}
849
850static bool dd_has_write_work(struct blk_mq_hw_ctx *hctx)
851{
852 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
853 enum dd_prio p;
854
855 for (p = 0; p <= DD_PRIO_MAX; p++)
856 if (!list_empty_careful(&dd->per_prio[p].fifo_list[DD_WRITE]))
857 return true;
858
859 return false;
860}
861
862/*
863 * Callback from inside blk_mq_free_request().
864 *
865 * For zoned block devices, write unlock the target zone of
866 * completed write requests. Do this while holding the zone lock
867 * spinlock so that the zone is never unlocked while deadline_fifo_request()
868 * or deadline_next_request() are executing. This function is called for
869 * all requests, whether or not these requests complete successfully.
870 *
871 * For a zoned block device, __dd_dispatch_request() may have stopped
872 * dispatching requests if all the queued requests are write requests directed
873 * at zones that are already locked due to on-going write requests. To ensure
874 * write request dispatch progress in this case, mark the queue as needing a
875 * restart to ensure that the queue is run again after completion of the
876 * request and zones being unlocked.
877 */
878static void dd_finish_request(struct request *rq)
879{
880 struct request_queue *q = rq->q;
881 struct deadline_data *dd = q->elevator->elevator_data;
882 const u8 ioprio_class = dd_rq_ioclass(rq);
883 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
884 struct dd_per_prio *per_prio = &dd->per_prio[prio];
885
886 /*
887 * The block layer core may call dd_finish_request() without having
888 * called dd_insert_requests(). Skip requests that bypassed I/O
889 * scheduling. See also blk_mq_request_bypass_insert().
890 */
891 if (!rq->elv.priv[0])
892 return;
893
894 atomic_inc(&per_prio->stats.completed);
895
896 if (blk_queue_is_zoned(q)) {
897 unsigned long flags;
898
899 spin_lock_irqsave(&dd->zone_lock, flags);
900 blk_req_zone_write_unlock(rq);
901 spin_unlock_irqrestore(&dd->zone_lock, flags);
902
903 if (dd_has_write_work(rq->mq_hctx))
904 blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
905 }
906}
907
908static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
909{
910 return !list_empty_careful(&per_prio->dispatch) ||
911 !list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
912 !list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
913}
914
915static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
916{
917 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
918 enum dd_prio prio;
919
920 for (prio = 0; prio <= DD_PRIO_MAX; prio++)
921 if (dd_has_work_for_prio(&dd->per_prio[prio]))
922 return true;
923
924 return false;
925}
926
927/*
928 * sysfs parts below
929 */
930#define SHOW_INT(__FUNC, __VAR) \
931static ssize_t __FUNC(struct elevator_queue *e, char *page) \
932{ \
933 struct deadline_data *dd = e->elevator_data; \
934 \
935 return sysfs_emit(page, "%d\n", __VAR); \
936}
937#define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
938SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
939SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
940SHOW_JIFFIES(deadline_prio_aging_expire_show, dd->prio_aging_expire);
941SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
942SHOW_INT(deadline_front_merges_show, dd->front_merges);
943SHOW_INT(deadline_async_depth_show, dd->async_depth);
944SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
945#undef SHOW_INT
946#undef SHOW_JIFFIES
947
948#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
949static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
950{ \
951 struct deadline_data *dd = e->elevator_data; \
952 int __data, __ret; \
953 \
954 __ret = kstrtoint(page, 0, &__data); \
955 if (__ret < 0) \
956 return __ret; \
957 if (__data < (MIN)) \
958 __data = (MIN); \
959 else if (__data > (MAX)) \
960 __data = (MAX); \
961 *(__PTR) = __CONV(__data); \
962 return count; \
963}
964#define STORE_INT(__FUNC, __PTR, MIN, MAX) \
965 STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
966#define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX) \
967 STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
968STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
969STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
970STORE_JIFFIES(deadline_prio_aging_expire_store, &dd->prio_aging_expire, 0, INT_MAX);
971STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
972STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
973STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX);
974STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
975#undef STORE_FUNCTION
976#undef STORE_INT
977#undef STORE_JIFFIES
978
979#define DD_ATTR(name) \
980 __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
981
982static struct elv_fs_entry deadline_attrs[] = {
983 DD_ATTR(read_expire),
984 DD_ATTR(write_expire),
985 DD_ATTR(writes_starved),
986 DD_ATTR(front_merges),
987 DD_ATTR(async_depth),
988 DD_ATTR(fifo_batch),
989 DD_ATTR(prio_aging_expire),
990 __ATTR_NULL
991};
992
993#ifdef CONFIG_BLK_DEBUG_FS
994#define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name) \
995static void *deadline_##name##_fifo_start(struct seq_file *m, \
996 loff_t *pos) \
997 __acquires(&dd->lock) \
998{ \
999 struct request_queue *q = m->private; \
1000 struct deadline_data *dd = q->elevator->elevator_data; \
1001 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1002 \
1003 spin_lock(&dd->lock); \
1004 return seq_list_start(&per_prio->fifo_list[data_dir], *pos); \
1005} \
1006 \
1007static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \
1008 loff_t *pos) \
1009{ \
1010 struct request_queue *q = m->private; \
1011 struct deadline_data *dd = q->elevator->elevator_data; \
1012 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1013 \
1014 return seq_list_next(v, &per_prio->fifo_list[data_dir], pos); \
1015} \
1016 \
1017static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \
1018 __releases(&dd->lock) \
1019{ \
1020 struct request_queue *q = m->private; \
1021 struct deadline_data *dd = q->elevator->elevator_data; \
1022 \
1023 spin_unlock(&dd->lock); \
1024} \
1025 \
1026static const struct seq_operations deadline_##name##_fifo_seq_ops = { \
1027 .start = deadline_##name##_fifo_start, \
1028 .next = deadline_##name##_fifo_next, \
1029 .stop = deadline_##name##_fifo_stop, \
1030 .show = blk_mq_debugfs_rq_show, \
1031}; \
1032 \
1033static int deadline_##name##_next_rq_show(void *data, \
1034 struct seq_file *m) \
1035{ \
1036 struct request_queue *q = data; \
1037 struct deadline_data *dd = q->elevator->elevator_data; \
1038 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1039 struct request *rq = per_prio->next_rq[data_dir]; \
1040 \
1041 if (rq) \
1042 __blk_mq_debugfs_rq_show(m, rq); \
1043 return 0; \
1044}
1045
1046DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
1047DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
1048DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
1049DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
1050DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
1051DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);
1052#undef DEADLINE_DEBUGFS_DDIR_ATTRS
1053
1054static int deadline_batching_show(void *data, struct seq_file *m)
1055{
1056 struct request_queue *q = data;
1057 struct deadline_data *dd = q->elevator->elevator_data;
1058
1059 seq_printf(m, "%u\n", dd->batching);
1060 return 0;
1061}
1062
1063static int deadline_starved_show(void *data, struct seq_file *m)
1064{
1065 struct request_queue *q = data;
1066 struct deadline_data *dd = q->elevator->elevator_data;
1067
1068 seq_printf(m, "%u\n", dd->starved);
1069 return 0;
1070}
1071
1072static int dd_async_depth_show(void *data, struct seq_file *m)
1073{
1074 struct request_queue *q = data;
1075 struct deadline_data *dd = q->elevator->elevator_data;
1076
1077 seq_printf(m, "%u\n", dd->async_depth);
1078 return 0;
1079}
1080
1081static int dd_queued_show(void *data, struct seq_file *m)
1082{
1083 struct request_queue *q = data;
1084 struct deadline_data *dd = q->elevator->elevator_data;
1085 u32 rt, be, idle;
1086
1087 spin_lock(&dd->lock);
1088 rt = dd_queued(dd, DD_RT_PRIO);
1089 be = dd_queued(dd, DD_BE_PRIO);
1090 idle = dd_queued(dd, DD_IDLE_PRIO);
1091 spin_unlock(&dd->lock);
1092
1093 seq_printf(m, "%u %u %u\n", rt, be, idle);
1094
1095 return 0;
1096}
1097
1098/* Number of requests owned by the block driver for a given priority. */
1099static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
1100{
1101 const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
1102
1103 lockdep_assert_held(&dd->lock);
1104
1105 return stats->dispatched + stats->merged -
1106 atomic_read(&stats->completed);
1107}
1108
1109static int dd_owned_by_driver_show(void *data, struct seq_file *m)
1110{
1111 struct request_queue *q = data;
1112 struct deadline_data *dd = q->elevator->elevator_data;
1113 u32 rt, be, idle;
1114
1115 spin_lock(&dd->lock);
1116 rt = dd_owned_by_driver(dd, DD_RT_PRIO);
1117 be = dd_owned_by_driver(dd, DD_BE_PRIO);
1118 idle = dd_owned_by_driver(dd, DD_IDLE_PRIO);
1119 spin_unlock(&dd->lock);
1120
1121 seq_printf(m, "%u %u %u\n", rt, be, idle);
1122
1123 return 0;
1124}
1125
1126#define DEADLINE_DISPATCH_ATTR(prio) \
1127static void *deadline_dispatch##prio##_start(struct seq_file *m, \
1128 loff_t *pos) \
1129 __acquires(&dd->lock) \
1130{ \
1131 struct request_queue *q = m->private; \
1132 struct deadline_data *dd = q->elevator->elevator_data; \
1133 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1134 \
1135 spin_lock(&dd->lock); \
1136 return seq_list_start(&per_prio->dispatch, *pos); \
1137} \
1138 \
1139static void *deadline_dispatch##prio##_next(struct seq_file *m, \
1140 void *v, loff_t *pos) \
1141{ \
1142 struct request_queue *q = m->private; \
1143 struct deadline_data *dd = q->elevator->elevator_data; \
1144 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1145 \
1146 return seq_list_next(v, &per_prio->dispatch, pos); \
1147} \
1148 \
1149static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \
1150 __releases(&dd->lock) \
1151{ \
1152 struct request_queue *q = m->private; \
1153 struct deadline_data *dd = q->elevator->elevator_data; \
1154 \
1155 spin_unlock(&dd->lock); \
1156} \
1157 \
1158static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
1159 .start = deadline_dispatch##prio##_start, \
1160 .next = deadline_dispatch##prio##_next, \
1161 .stop = deadline_dispatch##prio##_stop, \
1162 .show = blk_mq_debugfs_rq_show, \
1163}
1164
1165DEADLINE_DISPATCH_ATTR(0);
1166DEADLINE_DISPATCH_ATTR(1);
1167DEADLINE_DISPATCH_ATTR(2);
1168#undef DEADLINE_DISPATCH_ATTR
1169
1170#define DEADLINE_QUEUE_DDIR_ATTRS(name) \
1171 {#name "_fifo_list", 0400, \
1172 .seq_ops = &deadline_##name##_fifo_seq_ops}
1173#define DEADLINE_NEXT_RQ_ATTR(name) \
1174 {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
1175static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
1176 DEADLINE_QUEUE_DDIR_ATTRS(read0),
1177 DEADLINE_QUEUE_DDIR_ATTRS(write0),
1178 DEADLINE_QUEUE_DDIR_ATTRS(read1),
1179 DEADLINE_QUEUE_DDIR_ATTRS(write1),
1180 DEADLINE_QUEUE_DDIR_ATTRS(read2),
1181 DEADLINE_QUEUE_DDIR_ATTRS(write2),
1182 DEADLINE_NEXT_RQ_ATTR(read0),
1183 DEADLINE_NEXT_RQ_ATTR(write0),
1184 DEADLINE_NEXT_RQ_ATTR(read1),
1185 DEADLINE_NEXT_RQ_ATTR(write1),
1186 DEADLINE_NEXT_RQ_ATTR(read2),
1187 DEADLINE_NEXT_RQ_ATTR(write2),
1188 {"batching", 0400, deadline_batching_show},
1189 {"starved", 0400, deadline_starved_show},
1190 {"async_depth", 0400, dd_async_depth_show},
1191 {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
1192 {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
1193 {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},
1194 {"owned_by_driver", 0400, dd_owned_by_driver_show},
1195 {"queued", 0400, dd_queued_show},
1196 {},
1197};
1198#undef DEADLINE_QUEUE_DDIR_ATTRS
1199#endif
1200
1201static struct elevator_type mq_deadline = {
1202 .ops = {
1203 .depth_updated = dd_depth_updated,
1204 .limit_depth = dd_limit_depth,
1205 .insert_requests = dd_insert_requests,
1206 .dispatch_request = dd_dispatch_request,
1207 .prepare_request = dd_prepare_request,
1208 .finish_request = dd_finish_request,
1209 .next_request = elv_rb_latter_request,
1210 .former_request = elv_rb_former_request,
1211 .bio_merge = dd_bio_merge,
1212 .request_merge = dd_request_merge,
1213 .requests_merged = dd_merged_requests,
1214 .request_merged = dd_request_merged,
1215 .has_work = dd_has_work,
1216 .init_sched = dd_init_sched,
1217 .exit_sched = dd_exit_sched,
1218 .init_hctx = dd_init_hctx,
1219 },
1220
1221#ifdef CONFIG_BLK_DEBUG_FS
1222 .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
1223#endif
1224 .elevator_attrs = deadline_attrs,
1225 .elevator_name = "mq-deadline",
1226 .elevator_alias = "deadline",
1227 .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
1228 .elevator_owner = THIS_MODULE,
1229};
1230MODULE_ALIAS("mq-deadline-iosched");
1231
1232static int __init deadline_init(void)
1233{
1234 return elv_register(&mq_deadline);
1235}
1236
1237static void __exit deadline_exit(void)
1238{
1239 elv_unregister(&mq_deadline);
1240}
1241
1242module_init(deadline_init);
1243module_exit(deadline_exit);
1244
1245MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");
1246MODULE_LICENSE("GPL");
1247MODULE_DESCRIPTION("MQ deadline IO scheduler");
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
4 * for the blk-mq scheduling framework
5 *
6 * Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
7 */
8#include <linux/kernel.h>
9#include <linux/fs.h>
10#include <linux/blkdev.h>
11#include <linux/blk-mq.h>
12#include <linux/elevator.h>
13#include <linux/bio.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/compiler.h>
18#include <linux/rbtree.h>
19#include <linux/sbitmap.h>
20
21#include <trace/events/block.h>
22
23#include "blk.h"
24#include "blk-mq.h"
25#include "blk-mq-debugfs.h"
26#include "blk-mq-tag.h"
27#include "blk-mq-sched.h"
28
29/*
30 * See Documentation/block/deadline-iosched.rst
31 */
32static const int read_expire = HZ / 2; /* max time before a read is submitted. */
33static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
34static const int writes_starved = 2; /* max times reads can starve a write */
35static const int fifo_batch = 16; /* # of sequential requests treated as one
36 by the above parameters. For throughput. */
37
38enum dd_data_dir {
39 DD_READ = READ,
40 DD_WRITE = WRITE,
41};
42
43enum { DD_DIR_COUNT = 2 };
44
45enum dd_prio {
46 DD_RT_PRIO = 0,
47 DD_BE_PRIO = 1,
48 DD_IDLE_PRIO = 2,
49 DD_PRIO_MAX = 2,
50};
51
52enum { DD_PRIO_COUNT = 3 };
53
54/* I/O statistics per I/O priority. */
55struct io_stats_per_prio {
56 local_t inserted;
57 local_t merged;
58 local_t dispatched;
59 local_t completed;
60};
61
62/* I/O statistics for all I/O priorities (enum dd_prio). */
63struct io_stats {
64 struct io_stats_per_prio stats[DD_PRIO_COUNT];
65};
66
67/*
68 * Deadline scheduler data per I/O priority (enum dd_prio). Requests are
69 * present on both sort_list[] and fifo_list[].
70 */
71struct dd_per_prio {
72 struct list_head dispatch;
73 struct rb_root sort_list[DD_DIR_COUNT];
74 struct list_head fifo_list[DD_DIR_COUNT];
75 /* Next request in FIFO order. Read, write or both are NULL. */
76 struct request *next_rq[DD_DIR_COUNT];
77};
78
79struct deadline_data {
80 /*
81 * run time data
82 */
83
84 struct dd_per_prio per_prio[DD_PRIO_COUNT];
85
86 /* Data direction of latest dispatched request. */
87 enum dd_data_dir last_dir;
88 unsigned int batching; /* number of sequential requests made */
89 unsigned int starved; /* times reads have starved writes */
90
91 struct io_stats __percpu *stats;
92
93 /*
94 * settings that change how the i/o scheduler behaves
95 */
96 int fifo_expire[DD_DIR_COUNT];
97 int fifo_batch;
98 int writes_starved;
99 int front_merges;
100 u32 async_depth;
101
102 spinlock_t lock;
103 spinlock_t zone_lock;
104};
105
106/* Count one event of type 'event_type' and with I/O priority 'prio' */
107#define dd_count(dd, event_type, prio) do { \
108 struct io_stats *io_stats = get_cpu_ptr((dd)->stats); \
109 \
110 BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
111 BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
112 local_inc(&io_stats->stats[(prio)].event_type); \
113 put_cpu_ptr(io_stats); \
114} while (0)
115
116/*
117 * Returns the total number of dd_count(dd, event_type, prio) calls across all
118 * CPUs. No locking or barriers since it is fine if the returned sum is slightly
119 * outdated.
120 */
121#define dd_sum(dd, event_type, prio) ({ \
122 unsigned int cpu; \
123 u32 sum = 0; \
124 \
125 BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
126 BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
127 for_each_present_cpu(cpu) \
128 sum += local_read(&per_cpu_ptr((dd)->stats, cpu)-> \
129 stats[(prio)].event_type); \
130 sum; \
131})
132
133/* Maps an I/O priority class to a deadline scheduler priority. */
134static const enum dd_prio ioprio_class_to_prio[] = {
135 [IOPRIO_CLASS_NONE] = DD_BE_PRIO,
136 [IOPRIO_CLASS_RT] = DD_RT_PRIO,
137 [IOPRIO_CLASS_BE] = DD_BE_PRIO,
138 [IOPRIO_CLASS_IDLE] = DD_IDLE_PRIO,
139};
140
141static inline struct rb_root *
142deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)
143{
144 return &per_prio->sort_list[rq_data_dir(rq)];
145}
146
147/*
148 * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
149 * request.
150 */
151static u8 dd_rq_ioclass(struct request *rq)
152{
153 return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
154}
155
156/*
157 * get the request after `rq' in sector-sorted order
158 */
159static inline struct request *
160deadline_latter_request(struct request *rq)
161{
162 struct rb_node *node = rb_next(&rq->rb_node);
163
164 if (node)
165 return rb_entry_rq(node);
166
167 return NULL;
168}
169
170static void
171deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
172{
173 struct rb_root *root = deadline_rb_root(per_prio, rq);
174
175 elv_rb_add(root, rq);
176}
177
178static inline void
179deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
180{
181 const enum dd_data_dir data_dir = rq_data_dir(rq);
182
183 if (per_prio->next_rq[data_dir] == rq)
184 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
185
186 elv_rb_del(deadline_rb_root(per_prio, rq), rq);
187}
188
189/*
190 * remove rq from rbtree and fifo.
191 */
192static void deadline_remove_request(struct request_queue *q,
193 struct dd_per_prio *per_prio,
194 struct request *rq)
195{
196 list_del_init(&rq->queuelist);
197
198 /*
199 * We might not be on the rbtree, if we are doing an insert merge
200 */
201 if (!RB_EMPTY_NODE(&rq->rb_node))
202 deadline_del_rq_rb(per_prio, rq);
203
204 elv_rqhash_del(q, rq);
205 if (q->last_merge == rq)
206 q->last_merge = NULL;
207}
208
209static void dd_request_merged(struct request_queue *q, struct request *req,
210 enum elv_merge type)
211{
212 struct deadline_data *dd = q->elevator->elevator_data;
213 const u8 ioprio_class = dd_rq_ioclass(req);
214 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
215 struct dd_per_prio *per_prio = &dd->per_prio[prio];
216
217 /*
218 * if the merge was a front merge, we need to reposition request
219 */
220 if (type == ELEVATOR_FRONT_MERGE) {
221 elv_rb_del(deadline_rb_root(per_prio, req), req);
222 deadline_add_rq_rb(per_prio, req);
223 }
224}
225
226/*
227 * Callback function that is invoked after @next has been merged into @req.
228 */
229static void dd_merged_requests(struct request_queue *q, struct request *req,
230 struct request *next)
231{
232 struct deadline_data *dd = q->elevator->elevator_data;
233 const u8 ioprio_class = dd_rq_ioclass(next);
234 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
235
236 dd_count(dd, merged, prio);
237
238 /*
239 * if next expires before rq, assign its expire time to rq
240 * and move into next position (next will be deleted) in fifo
241 */
242 if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
243 if (time_before((unsigned long)next->fifo_time,
244 (unsigned long)req->fifo_time)) {
245 list_move(&req->queuelist, &next->queuelist);
246 req->fifo_time = next->fifo_time;
247 }
248 }
249
250 /*
251 * kill knowledge of next, this one is a goner
252 */
253 deadline_remove_request(q, &dd->per_prio[prio], next);
254}
255
256/*
257 * move an entry to dispatch queue
258 */
259static void
260deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
261 struct request *rq)
262{
263 const enum dd_data_dir data_dir = rq_data_dir(rq);
264
265 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
266
267 /*
268 * take it off the sort and fifo list
269 */
270 deadline_remove_request(rq->q, per_prio, rq);
271}
272
273/*
274 * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
275 * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
276 */
277static inline int deadline_check_fifo(struct dd_per_prio *per_prio,
278 enum dd_data_dir data_dir)
279{
280 struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
281
282 /*
283 * rq is expired!
284 */
285 if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
286 return 1;
287
288 return 0;
289}
290
291/*
292 * For the specified data direction, return the next request to
293 * dispatch using arrival ordered lists.
294 */
295static struct request *
296deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
297 enum dd_data_dir data_dir)
298{
299 struct request *rq;
300 unsigned long flags;
301
302 if (list_empty(&per_prio->fifo_list[data_dir]))
303 return NULL;
304
305 rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
306 if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
307 return rq;
308
309 /*
310 * Look for a write request that can be dispatched, that is one with
311 * an unlocked target zone.
312 */
313 spin_lock_irqsave(&dd->zone_lock, flags);
314 list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {
315 if (blk_req_can_dispatch_to_zone(rq))
316 goto out;
317 }
318 rq = NULL;
319out:
320 spin_unlock_irqrestore(&dd->zone_lock, flags);
321
322 return rq;
323}
324
325/*
326 * For the specified data direction, return the next request to
327 * dispatch using sector position sorted lists.
328 */
329static struct request *
330deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
331 enum dd_data_dir data_dir)
332{
333 struct request *rq;
334 unsigned long flags;
335
336 rq = per_prio->next_rq[data_dir];
337 if (!rq)
338 return NULL;
339
340 if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
341 return rq;
342
343 /*
344 * Look for a write request that can be dispatched, that is one with
345 * an unlocked target zone.
346 */
347 spin_lock_irqsave(&dd->zone_lock, flags);
348 while (rq) {
349 if (blk_req_can_dispatch_to_zone(rq))
350 break;
351 rq = deadline_latter_request(rq);
352 }
353 spin_unlock_irqrestore(&dd->zone_lock, flags);
354
355 return rq;
356}
357
358/*
359 * deadline_dispatch_requests selects the best request according to
360 * read/write expire, fifo_batch, etc
361 */
362static struct request *__dd_dispatch_request(struct deadline_data *dd,
363 struct dd_per_prio *per_prio)
364{
365 struct request *rq, *next_rq;
366 enum dd_data_dir data_dir;
367 enum dd_prio prio;
368 u8 ioprio_class;
369
370 lockdep_assert_held(&dd->lock);
371
372 if (!list_empty(&per_prio->dispatch)) {
373 rq = list_first_entry(&per_prio->dispatch, struct request,
374 queuelist);
375 list_del_init(&rq->queuelist);
376 goto done;
377 }
378
379 /*
380 * batches are currently reads XOR writes
381 */
382 rq = deadline_next_request(dd, per_prio, dd->last_dir);
383 if (rq && dd->batching < dd->fifo_batch)
384 /* we have a next request are still entitled to batch */
385 goto dispatch_request;
386
387 /*
388 * at this point we are not running a batch. select the appropriate
389 * data direction (read / write)
390 */
391
392 if (!list_empty(&per_prio->fifo_list[DD_READ])) {
393 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));
394
395 if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&
396 (dd->starved++ >= dd->writes_starved))
397 goto dispatch_writes;
398
399 data_dir = DD_READ;
400
401 goto dispatch_find_request;
402 }
403
404 /*
405 * there are either no reads or writes have been starved
406 */
407
408 if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {
409dispatch_writes:
410 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));
411
412 dd->starved = 0;
413
414 data_dir = DD_WRITE;
415
416 goto dispatch_find_request;
417 }
418
419 return NULL;
420
421dispatch_find_request:
422 /*
423 * we are not running a batch, find best request for selected data_dir
424 */
425 next_rq = deadline_next_request(dd, per_prio, data_dir);
426 if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {
427 /*
428 * A deadline has expired, the last request was in the other
429 * direction, or we have run out of higher-sectored requests.
430 * Start again from the request with the earliest expiry time.
431 */
432 rq = deadline_fifo_request(dd, per_prio, data_dir);
433 } else {
434 /*
435 * The last req was the same dir and we have a next request in
436 * sort order. No expired requests so continue on from here.
437 */
438 rq = next_rq;
439 }
440
441 /*
442 * For a zoned block device, if we only have writes queued and none of
443 * them can be dispatched, rq will be NULL.
444 */
445 if (!rq)
446 return NULL;
447
448 dd->last_dir = data_dir;
449 dd->batching = 0;
450
451dispatch_request:
452 /*
453 * rq is the selected appropriate request.
454 */
455 dd->batching++;
456 deadline_move_request(dd, per_prio, rq);
457done:
458 ioprio_class = dd_rq_ioclass(rq);
459 prio = ioprio_class_to_prio[ioprio_class];
460 dd_count(dd, dispatched, prio);
461 /*
462 * If the request needs its target zone locked, do it.
463 */
464 blk_req_zone_write_lock(rq);
465 rq->rq_flags |= RQF_STARTED;
466 return rq;
467}
468
469/*
470 * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
471 *
472 * One confusing aspect here is that we get called for a specific
473 * hardware queue, but we may return a request that is for a
474 * different hardware queue. This is because mq-deadline has shared
475 * state for all hardware queues, in terms of sorting, FIFOs, etc.
476 */
477static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
478{
479 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
480 struct request *rq;
481 enum dd_prio prio;
482
483 spin_lock(&dd->lock);
484 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
485 rq = __dd_dispatch_request(dd, &dd->per_prio[prio]);
486 if (rq)
487 break;
488 }
489 spin_unlock(&dd->lock);
490
491 return rq;
492}
493
494/*
495 * Called by __blk_mq_alloc_request(). The shallow_depth value set by this
496 * function is used by __blk_mq_get_tag().
497 */
498static void dd_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
499{
500 struct deadline_data *dd = data->q->elevator->elevator_data;
501
502 /* Do not throttle synchronous reads. */
503 if (op_is_sync(op) && !op_is_write(op))
504 return;
505
506 /*
507 * Throttle asynchronous requests and writes such that these requests
508 * do not block the allocation of synchronous requests.
509 */
510 data->shallow_depth = dd->async_depth;
511}
512
513/* Called by blk_mq_update_nr_requests(). */
514static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
515{
516 struct request_queue *q = hctx->queue;
517 struct deadline_data *dd = q->elevator->elevator_data;
518 struct blk_mq_tags *tags = hctx->sched_tags;
519
520 dd->async_depth = max(1UL, 3 * q->nr_requests / 4);
521
522 sbitmap_queue_min_shallow_depth(tags->bitmap_tags, dd->async_depth);
523}
524
525/* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
526static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
527{
528 dd_depth_updated(hctx);
529 return 0;
530}
531
532static void dd_exit_sched(struct elevator_queue *e)
533{
534 struct deadline_data *dd = e->elevator_data;
535 enum dd_prio prio;
536
537 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
538 struct dd_per_prio *per_prio = &dd->per_prio[prio];
539
540 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
541 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
542 }
543
544 free_percpu(dd->stats);
545
546 kfree(dd);
547}
548
549/*
550 * initialize elevator private data (deadline_data).
551 */
552static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
553{
554 struct deadline_data *dd;
555 struct elevator_queue *eq;
556 enum dd_prio prio;
557 int ret = -ENOMEM;
558
559 eq = elevator_alloc(q, e);
560 if (!eq)
561 return ret;
562
563 dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
564 if (!dd)
565 goto put_eq;
566
567 eq->elevator_data = dd;
568
569 dd->stats = alloc_percpu_gfp(typeof(*dd->stats),
570 GFP_KERNEL | __GFP_ZERO);
571 if (!dd->stats)
572 goto free_dd;
573
574 for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
575 struct dd_per_prio *per_prio = &dd->per_prio[prio];
576
577 INIT_LIST_HEAD(&per_prio->dispatch);
578 INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]);
579 INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]);
580 per_prio->sort_list[DD_READ] = RB_ROOT;
581 per_prio->sort_list[DD_WRITE] = RB_ROOT;
582 }
583 dd->fifo_expire[DD_READ] = read_expire;
584 dd->fifo_expire[DD_WRITE] = write_expire;
585 dd->writes_starved = writes_starved;
586 dd->front_merges = 1;
587 dd->last_dir = DD_WRITE;
588 dd->fifo_batch = fifo_batch;
589 spin_lock_init(&dd->lock);
590 spin_lock_init(&dd->zone_lock);
591
592 q->elevator = eq;
593 return 0;
594
595free_dd:
596 kfree(dd);
597
598put_eq:
599 kobject_put(&eq->kobj);
600 return ret;
601}
602
603/*
604 * Try to merge @bio into an existing request. If @bio has been merged into
605 * an existing request, store the pointer to that request into *@rq.
606 */
607static int dd_request_merge(struct request_queue *q, struct request **rq,
608 struct bio *bio)
609{
610 struct deadline_data *dd = q->elevator->elevator_data;
611 const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
612 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
613 struct dd_per_prio *per_prio = &dd->per_prio[prio];
614 sector_t sector = bio_end_sector(bio);
615 struct request *__rq;
616
617 if (!dd->front_merges)
618 return ELEVATOR_NO_MERGE;
619
620 __rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector);
621 if (__rq) {
622 BUG_ON(sector != blk_rq_pos(__rq));
623
624 if (elv_bio_merge_ok(__rq, bio)) {
625 *rq = __rq;
626 if (blk_discard_mergable(__rq))
627 return ELEVATOR_DISCARD_MERGE;
628 return ELEVATOR_FRONT_MERGE;
629 }
630 }
631
632 return ELEVATOR_NO_MERGE;
633}
634
635/*
636 * Attempt to merge a bio into an existing request. This function is called
637 * before @bio is associated with a request.
638 */
639static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
640 unsigned int nr_segs)
641{
642 struct deadline_data *dd = q->elevator->elevator_data;
643 struct request *free = NULL;
644 bool ret;
645
646 spin_lock(&dd->lock);
647 ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
648 spin_unlock(&dd->lock);
649
650 if (free)
651 blk_mq_free_request(free);
652
653 return ret;
654}
655
656/*
657 * add rq to rbtree and fifo
658 */
659static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
660 bool at_head)
661{
662 struct request_queue *q = hctx->queue;
663 struct deadline_data *dd = q->elevator->elevator_data;
664 const enum dd_data_dir data_dir = rq_data_dir(rq);
665 u16 ioprio = req_get_ioprio(rq);
666 u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
667 struct dd_per_prio *per_prio;
668 enum dd_prio prio;
669 LIST_HEAD(free);
670
671 lockdep_assert_held(&dd->lock);
672
673 /*
674 * This may be a requeue of a write request that has locked its
675 * target zone. If it is the case, this releases the zone lock.
676 */
677 blk_req_zone_write_unlock(rq);
678
679 prio = ioprio_class_to_prio[ioprio_class];
680 dd_count(dd, inserted, prio);
681 rq->elv.priv[0] = (void *)(uintptr_t)1;
682
683 if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
684 blk_mq_free_requests(&free);
685 return;
686 }
687
688 trace_block_rq_insert(rq);
689
690 per_prio = &dd->per_prio[prio];
691 if (at_head) {
692 list_add(&rq->queuelist, &per_prio->dispatch);
693 } else {
694 deadline_add_rq_rb(per_prio, rq);
695
696 if (rq_mergeable(rq)) {
697 elv_rqhash_add(q, rq);
698 if (!q->last_merge)
699 q->last_merge = rq;
700 }
701
702 /*
703 * set expire time and add to fifo list
704 */
705 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
706 list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
707 }
708}
709
710/*
711 * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests().
712 */
713static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
714 struct list_head *list, bool at_head)
715{
716 struct request_queue *q = hctx->queue;
717 struct deadline_data *dd = q->elevator->elevator_data;
718
719 spin_lock(&dd->lock);
720 while (!list_empty(list)) {
721 struct request *rq;
722
723 rq = list_first_entry(list, struct request, queuelist);
724 list_del_init(&rq->queuelist);
725 dd_insert_request(hctx, rq, at_head);
726 }
727 spin_unlock(&dd->lock);
728}
729
730/* Callback from inside blk_mq_rq_ctx_init(). */
731static void dd_prepare_request(struct request *rq)
732{
733 rq->elv.priv[0] = NULL;
734}
735
736/*
737 * Callback from inside blk_mq_free_request().
738 *
739 * For zoned block devices, write unlock the target zone of
740 * completed write requests. Do this while holding the zone lock
741 * spinlock so that the zone is never unlocked while deadline_fifo_request()
742 * or deadline_next_request() are executing. This function is called for
743 * all requests, whether or not these requests complete successfully.
744 *
745 * For a zoned block device, __dd_dispatch_request() may have stopped
746 * dispatching requests if all the queued requests are write requests directed
747 * at zones that are already locked due to on-going write requests. To ensure
748 * write request dispatch progress in this case, mark the queue as needing a
749 * restart to ensure that the queue is run again after completion of the
750 * request and zones being unlocked.
751 */
752static void dd_finish_request(struct request *rq)
753{
754 struct request_queue *q = rq->q;
755 struct deadline_data *dd = q->elevator->elevator_data;
756 const u8 ioprio_class = dd_rq_ioclass(rq);
757 const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
758 struct dd_per_prio *per_prio = &dd->per_prio[prio];
759
760 /*
761 * The block layer core may call dd_finish_request() without having
762 * called dd_insert_requests(). Hence only update statistics for
763 * requests for which dd_insert_requests() has been called. See also
764 * blk_mq_request_bypass_insert().
765 */
766 if (rq->elv.priv[0])
767 dd_count(dd, completed, prio);
768
769 if (blk_queue_is_zoned(q)) {
770 unsigned long flags;
771
772 spin_lock_irqsave(&dd->zone_lock, flags);
773 blk_req_zone_write_unlock(rq);
774 if (!list_empty(&per_prio->fifo_list[DD_WRITE]))
775 blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
776 spin_unlock_irqrestore(&dd->zone_lock, flags);
777 }
778}
779
780static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
781{
782 return !list_empty_careful(&per_prio->dispatch) ||
783 !list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
784 !list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
785}
786
787static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
788{
789 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
790 enum dd_prio prio;
791
792 for (prio = 0; prio <= DD_PRIO_MAX; prio++)
793 if (dd_has_work_for_prio(&dd->per_prio[prio]))
794 return true;
795
796 return false;
797}
798
799/*
800 * sysfs parts below
801 */
802#define SHOW_INT(__FUNC, __VAR) \
803static ssize_t __FUNC(struct elevator_queue *e, char *page) \
804{ \
805 struct deadline_data *dd = e->elevator_data; \
806 \
807 return sysfs_emit(page, "%d\n", __VAR); \
808}
809#define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
810SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
811SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
812SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
813SHOW_INT(deadline_front_merges_show, dd->front_merges);
814SHOW_INT(deadline_async_depth_show, dd->front_merges);
815SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
816#undef SHOW_INT
817#undef SHOW_JIFFIES
818
819#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
820static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
821{ \
822 struct deadline_data *dd = e->elevator_data; \
823 int __data, __ret; \
824 \
825 __ret = kstrtoint(page, 0, &__data); \
826 if (__ret < 0) \
827 return __ret; \
828 if (__data < (MIN)) \
829 __data = (MIN); \
830 else if (__data > (MAX)) \
831 __data = (MAX); \
832 *(__PTR) = __CONV(__data); \
833 return count; \
834}
835#define STORE_INT(__FUNC, __PTR, MIN, MAX) \
836 STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
837#define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX) \
838 STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
839STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
840STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
841STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
842STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
843STORE_INT(deadline_async_depth_store, &dd->front_merges, 1, INT_MAX);
844STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
845#undef STORE_FUNCTION
846#undef STORE_INT
847#undef STORE_JIFFIES
848
849#define DD_ATTR(name) \
850 __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
851
852static struct elv_fs_entry deadline_attrs[] = {
853 DD_ATTR(read_expire),
854 DD_ATTR(write_expire),
855 DD_ATTR(writes_starved),
856 DD_ATTR(front_merges),
857 DD_ATTR(async_depth),
858 DD_ATTR(fifo_batch),
859 __ATTR_NULL
860};
861
862#ifdef CONFIG_BLK_DEBUG_FS
863#define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name) \
864static void *deadline_##name##_fifo_start(struct seq_file *m, \
865 loff_t *pos) \
866 __acquires(&dd->lock) \
867{ \
868 struct request_queue *q = m->private; \
869 struct deadline_data *dd = q->elevator->elevator_data; \
870 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
871 \
872 spin_lock(&dd->lock); \
873 return seq_list_start(&per_prio->fifo_list[data_dir], *pos); \
874} \
875 \
876static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \
877 loff_t *pos) \
878{ \
879 struct request_queue *q = m->private; \
880 struct deadline_data *dd = q->elevator->elevator_data; \
881 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
882 \
883 return seq_list_next(v, &per_prio->fifo_list[data_dir], pos); \
884} \
885 \
886static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \
887 __releases(&dd->lock) \
888{ \
889 struct request_queue *q = m->private; \
890 struct deadline_data *dd = q->elevator->elevator_data; \
891 \
892 spin_unlock(&dd->lock); \
893} \
894 \
895static const struct seq_operations deadline_##name##_fifo_seq_ops = { \
896 .start = deadline_##name##_fifo_start, \
897 .next = deadline_##name##_fifo_next, \
898 .stop = deadline_##name##_fifo_stop, \
899 .show = blk_mq_debugfs_rq_show, \
900}; \
901 \
902static int deadline_##name##_next_rq_show(void *data, \
903 struct seq_file *m) \
904{ \
905 struct request_queue *q = data; \
906 struct deadline_data *dd = q->elevator->elevator_data; \
907 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
908 struct request *rq = per_prio->next_rq[data_dir]; \
909 \
910 if (rq) \
911 __blk_mq_debugfs_rq_show(m, rq); \
912 return 0; \
913}
914
915DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
916DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
917DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
918DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
919DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
920DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);
921#undef DEADLINE_DEBUGFS_DDIR_ATTRS
922
923static int deadline_batching_show(void *data, struct seq_file *m)
924{
925 struct request_queue *q = data;
926 struct deadline_data *dd = q->elevator->elevator_data;
927
928 seq_printf(m, "%u\n", dd->batching);
929 return 0;
930}
931
932static int deadline_starved_show(void *data, struct seq_file *m)
933{
934 struct request_queue *q = data;
935 struct deadline_data *dd = q->elevator->elevator_data;
936
937 seq_printf(m, "%u\n", dd->starved);
938 return 0;
939}
940
941static int dd_async_depth_show(void *data, struct seq_file *m)
942{
943 struct request_queue *q = data;
944 struct deadline_data *dd = q->elevator->elevator_data;
945
946 seq_printf(m, "%u\n", dd->async_depth);
947 return 0;
948}
949
950/* Number of requests queued for a given priority level. */
951static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
952{
953 return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
954}
955
956static int dd_queued_show(void *data, struct seq_file *m)
957{
958 struct request_queue *q = data;
959 struct deadline_data *dd = q->elevator->elevator_data;
960
961 seq_printf(m, "%u %u %u\n", dd_queued(dd, DD_RT_PRIO),
962 dd_queued(dd, DD_BE_PRIO),
963 dd_queued(dd, DD_IDLE_PRIO));
964 return 0;
965}
966
967/* Number of requests owned by the block driver for a given priority. */
968static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
969{
970 return dd_sum(dd, dispatched, prio) + dd_sum(dd, merged, prio)
971 - dd_sum(dd, completed, prio);
972}
973
974static int dd_owned_by_driver_show(void *data, struct seq_file *m)
975{
976 struct request_queue *q = data;
977 struct deadline_data *dd = q->elevator->elevator_data;
978
979 seq_printf(m, "%u %u %u\n", dd_owned_by_driver(dd, DD_RT_PRIO),
980 dd_owned_by_driver(dd, DD_BE_PRIO),
981 dd_owned_by_driver(dd, DD_IDLE_PRIO));
982 return 0;
983}
984
985#define DEADLINE_DISPATCH_ATTR(prio) \
986static void *deadline_dispatch##prio##_start(struct seq_file *m, \
987 loff_t *pos) \
988 __acquires(&dd->lock) \
989{ \
990 struct request_queue *q = m->private; \
991 struct deadline_data *dd = q->elevator->elevator_data; \
992 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
993 \
994 spin_lock(&dd->lock); \
995 return seq_list_start(&per_prio->dispatch, *pos); \
996} \
997 \
998static void *deadline_dispatch##prio##_next(struct seq_file *m, \
999 void *v, loff_t *pos) \
1000{ \
1001 struct request_queue *q = m->private; \
1002 struct deadline_data *dd = q->elevator->elevator_data; \
1003 struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
1004 \
1005 return seq_list_next(v, &per_prio->dispatch, pos); \
1006} \
1007 \
1008static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \
1009 __releases(&dd->lock) \
1010{ \
1011 struct request_queue *q = m->private; \
1012 struct deadline_data *dd = q->elevator->elevator_data; \
1013 \
1014 spin_unlock(&dd->lock); \
1015} \
1016 \
1017static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
1018 .start = deadline_dispatch##prio##_start, \
1019 .next = deadline_dispatch##prio##_next, \
1020 .stop = deadline_dispatch##prio##_stop, \
1021 .show = blk_mq_debugfs_rq_show, \
1022}
1023
1024DEADLINE_DISPATCH_ATTR(0);
1025DEADLINE_DISPATCH_ATTR(1);
1026DEADLINE_DISPATCH_ATTR(2);
1027#undef DEADLINE_DISPATCH_ATTR
1028
1029#define DEADLINE_QUEUE_DDIR_ATTRS(name) \
1030 {#name "_fifo_list", 0400, \
1031 .seq_ops = &deadline_##name##_fifo_seq_ops}
1032#define DEADLINE_NEXT_RQ_ATTR(name) \
1033 {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
1034static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
1035 DEADLINE_QUEUE_DDIR_ATTRS(read0),
1036 DEADLINE_QUEUE_DDIR_ATTRS(write0),
1037 DEADLINE_QUEUE_DDIR_ATTRS(read1),
1038 DEADLINE_QUEUE_DDIR_ATTRS(write1),
1039 DEADLINE_QUEUE_DDIR_ATTRS(read2),
1040 DEADLINE_QUEUE_DDIR_ATTRS(write2),
1041 DEADLINE_NEXT_RQ_ATTR(read0),
1042 DEADLINE_NEXT_RQ_ATTR(write0),
1043 DEADLINE_NEXT_RQ_ATTR(read1),
1044 DEADLINE_NEXT_RQ_ATTR(write1),
1045 DEADLINE_NEXT_RQ_ATTR(read2),
1046 DEADLINE_NEXT_RQ_ATTR(write2),
1047 {"batching", 0400, deadline_batching_show},
1048 {"starved", 0400, deadline_starved_show},
1049 {"async_depth", 0400, dd_async_depth_show},
1050 {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
1051 {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
1052 {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},
1053 {"owned_by_driver", 0400, dd_owned_by_driver_show},
1054 {"queued", 0400, dd_queued_show},
1055 {},
1056};
1057#undef DEADLINE_QUEUE_DDIR_ATTRS
1058#endif
1059
1060static struct elevator_type mq_deadline = {
1061 .ops = {
1062 .depth_updated = dd_depth_updated,
1063 .limit_depth = dd_limit_depth,
1064 .insert_requests = dd_insert_requests,
1065 .dispatch_request = dd_dispatch_request,
1066 .prepare_request = dd_prepare_request,
1067 .finish_request = dd_finish_request,
1068 .next_request = elv_rb_latter_request,
1069 .former_request = elv_rb_former_request,
1070 .bio_merge = dd_bio_merge,
1071 .request_merge = dd_request_merge,
1072 .requests_merged = dd_merged_requests,
1073 .request_merged = dd_request_merged,
1074 .has_work = dd_has_work,
1075 .init_sched = dd_init_sched,
1076 .exit_sched = dd_exit_sched,
1077 .init_hctx = dd_init_hctx,
1078 },
1079
1080#ifdef CONFIG_BLK_DEBUG_FS
1081 .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
1082#endif
1083 .elevator_attrs = deadline_attrs,
1084 .elevator_name = "mq-deadline",
1085 .elevator_alias = "deadline",
1086 .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
1087 .elevator_owner = THIS_MODULE,
1088};
1089MODULE_ALIAS("mq-deadline-iosched");
1090
1091static int __init deadline_init(void)
1092{
1093 return elv_register(&mq_deadline);
1094}
1095
1096static void __exit deadline_exit(void)
1097{
1098 elv_unregister(&mq_deadline);
1099}
1100
1101module_init(deadline_init);
1102module_exit(deadline_exit);
1103
1104MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");
1105MODULE_LICENSE("GPL");
1106MODULE_DESCRIPTION("MQ deadline IO scheduler");