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1/*
2 * MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
3 * for the blk-mq scheduling framework
4 *
5 * Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
6 */
7#include <linux/kernel.h>
8#include <linux/fs.h>
9#include <linux/blkdev.h>
10#include <linux/blk-mq.h>
11#include <linux/elevator.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 "blk.h"
21#include "blk-mq.h"
22#include "blk-mq-debugfs.h"
23#include "blk-mq-tag.h"
24#include "blk-mq-sched.h"
25
26/*
27 * See Documentation/block/deadline-iosched.txt
28 */
29static const int read_expire = HZ / 2; /* max time before a read is submitted. */
30static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
31static const int writes_starved = 2; /* max times reads can starve a write */
32static const int fifo_batch = 16; /* # of sequential requests treated as one
33 by the above parameters. For throughput. */
34
35struct deadline_data {
36 /*
37 * run time data
38 */
39
40 /*
41 * requests (deadline_rq s) are present on both sort_list and fifo_list
42 */
43 struct rb_root sort_list[2];
44 struct list_head fifo_list[2];
45
46 /*
47 * next in sort order. read, write or both are NULL
48 */
49 struct request *next_rq[2];
50 unsigned int batching; /* number of sequential requests made */
51 unsigned int starved; /* times reads have starved writes */
52
53 /*
54 * settings that change how the i/o scheduler behaves
55 */
56 int fifo_expire[2];
57 int fifo_batch;
58 int writes_starved;
59 int front_merges;
60
61 spinlock_t lock;
62 spinlock_t zone_lock;
63 struct list_head dispatch;
64};
65
66static inline struct rb_root *
67deadline_rb_root(struct deadline_data *dd, struct request *rq)
68{
69 return &dd->sort_list[rq_data_dir(rq)];
70}
71
72/*
73 * get the request after `rq' in sector-sorted order
74 */
75static inline struct request *
76deadline_latter_request(struct request *rq)
77{
78 struct rb_node *node = rb_next(&rq->rb_node);
79
80 if (node)
81 return rb_entry_rq(node);
82
83 return NULL;
84}
85
86static void
87deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
88{
89 struct rb_root *root = deadline_rb_root(dd, rq);
90
91 elv_rb_add(root, rq);
92}
93
94static inline void
95deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
96{
97 const int data_dir = rq_data_dir(rq);
98
99 if (dd->next_rq[data_dir] == rq)
100 dd->next_rq[data_dir] = deadline_latter_request(rq);
101
102 elv_rb_del(deadline_rb_root(dd, rq), rq);
103}
104
105/*
106 * remove rq from rbtree and fifo.
107 */
108static void deadline_remove_request(struct request_queue *q, struct request *rq)
109{
110 struct deadline_data *dd = q->elevator->elevator_data;
111
112 list_del_init(&rq->queuelist);
113
114 /*
115 * We might not be on the rbtree, if we are doing an insert merge
116 */
117 if (!RB_EMPTY_NODE(&rq->rb_node))
118 deadline_del_rq_rb(dd, rq);
119
120 elv_rqhash_del(q, rq);
121 if (q->last_merge == rq)
122 q->last_merge = NULL;
123}
124
125static void dd_request_merged(struct request_queue *q, struct request *req,
126 enum elv_merge type)
127{
128 struct deadline_data *dd = q->elevator->elevator_data;
129
130 /*
131 * if the merge was a front merge, we need to reposition request
132 */
133 if (type == ELEVATOR_FRONT_MERGE) {
134 elv_rb_del(deadline_rb_root(dd, req), req);
135 deadline_add_rq_rb(dd, req);
136 }
137}
138
139static void dd_merged_requests(struct request_queue *q, struct request *req,
140 struct request *next)
141{
142 /*
143 * if next expires before rq, assign its expire time to rq
144 * and move into next position (next will be deleted) in fifo
145 */
146 if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
147 if (time_before((unsigned long)next->fifo_time,
148 (unsigned long)req->fifo_time)) {
149 list_move(&req->queuelist, &next->queuelist);
150 req->fifo_time = next->fifo_time;
151 }
152 }
153
154 /*
155 * kill knowledge of next, this one is a goner
156 */
157 deadline_remove_request(q, next);
158}
159
160/*
161 * move an entry to dispatch queue
162 */
163static void
164deadline_move_request(struct deadline_data *dd, struct request *rq)
165{
166 const int data_dir = rq_data_dir(rq);
167
168 dd->next_rq[READ] = NULL;
169 dd->next_rq[WRITE] = NULL;
170 dd->next_rq[data_dir] = deadline_latter_request(rq);
171
172 /*
173 * take it off the sort and fifo list
174 */
175 deadline_remove_request(rq->q, rq);
176}
177
178/*
179 * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
180 * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
181 */
182static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
183{
184 struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
185
186 /*
187 * rq is expired!
188 */
189 if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
190 return 1;
191
192 return 0;
193}
194
195/*
196 * For the specified data direction, return the next request to
197 * dispatch using arrival ordered lists.
198 */
199static struct request *
200deadline_fifo_request(struct deadline_data *dd, int data_dir)
201{
202 struct request *rq;
203 unsigned long flags;
204
205 if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
206 return NULL;
207
208 if (list_empty(&dd->fifo_list[data_dir]))
209 return NULL;
210
211 rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
212 if (data_dir == READ || !blk_queue_is_zoned(rq->q))
213 return rq;
214
215 /*
216 * Look for a write request that can be dispatched, that is one with
217 * an unlocked target zone.
218 */
219 spin_lock_irqsave(&dd->zone_lock, flags);
220 list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
221 if (blk_req_can_dispatch_to_zone(rq))
222 goto out;
223 }
224 rq = NULL;
225out:
226 spin_unlock_irqrestore(&dd->zone_lock, flags);
227
228 return rq;
229}
230
231/*
232 * For the specified data direction, return the next request to
233 * dispatch using sector position sorted lists.
234 */
235static struct request *
236deadline_next_request(struct deadline_data *dd, int data_dir)
237{
238 struct request *rq;
239 unsigned long flags;
240
241 if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
242 return NULL;
243
244 rq = dd->next_rq[data_dir];
245 if (!rq)
246 return NULL;
247
248 if (data_dir == READ || !blk_queue_is_zoned(rq->q))
249 return rq;
250
251 /*
252 * Look for a write request that can be dispatched, that is one with
253 * an unlocked target zone.
254 */
255 spin_lock_irqsave(&dd->zone_lock, flags);
256 while (rq) {
257 if (blk_req_can_dispatch_to_zone(rq))
258 break;
259 rq = deadline_latter_request(rq);
260 }
261 spin_unlock_irqrestore(&dd->zone_lock, flags);
262
263 return rq;
264}
265
266/*
267 * deadline_dispatch_requests selects the best request according to
268 * read/write expire, fifo_batch, etc
269 */
270static struct request *__dd_dispatch_request(struct deadline_data *dd)
271{
272 struct request *rq, *next_rq;
273 bool reads, writes;
274 int data_dir;
275
276 if (!list_empty(&dd->dispatch)) {
277 rq = list_first_entry(&dd->dispatch, struct request, queuelist);
278 list_del_init(&rq->queuelist);
279 goto done;
280 }
281
282 reads = !list_empty(&dd->fifo_list[READ]);
283 writes = !list_empty(&dd->fifo_list[WRITE]);
284
285 /*
286 * batches are currently reads XOR writes
287 */
288 rq = deadline_next_request(dd, WRITE);
289 if (!rq)
290 rq = deadline_next_request(dd, READ);
291
292 if (rq && dd->batching < dd->fifo_batch)
293 /* we have a next request are still entitled to batch */
294 goto dispatch_request;
295
296 /*
297 * at this point we are not running a batch. select the appropriate
298 * data direction (read / write)
299 */
300
301 if (reads) {
302 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
303
304 if (deadline_fifo_request(dd, WRITE) &&
305 (dd->starved++ >= dd->writes_starved))
306 goto dispatch_writes;
307
308 data_dir = READ;
309
310 goto dispatch_find_request;
311 }
312
313 /*
314 * there are either no reads or writes have been starved
315 */
316
317 if (writes) {
318dispatch_writes:
319 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
320
321 dd->starved = 0;
322
323 data_dir = WRITE;
324
325 goto dispatch_find_request;
326 }
327
328 return NULL;
329
330dispatch_find_request:
331 /*
332 * we are not running a batch, find best request for selected data_dir
333 */
334 next_rq = deadline_next_request(dd, data_dir);
335 if (deadline_check_fifo(dd, data_dir) || !next_rq) {
336 /*
337 * A deadline has expired, the last request was in the other
338 * direction, or we have run out of higher-sectored requests.
339 * Start again from the request with the earliest expiry time.
340 */
341 rq = deadline_fifo_request(dd, data_dir);
342 } else {
343 /*
344 * The last req was the same dir and we have a next request in
345 * sort order. No expired requests so continue on from here.
346 */
347 rq = next_rq;
348 }
349
350 /*
351 * For a zoned block device, if we only have writes queued and none of
352 * them can be dispatched, rq will be NULL.
353 */
354 if (!rq)
355 return NULL;
356
357 dd->batching = 0;
358
359dispatch_request:
360 /*
361 * rq is the selected appropriate request.
362 */
363 dd->batching++;
364 deadline_move_request(dd, rq);
365done:
366 /*
367 * If the request needs its target zone locked, do it.
368 */
369 blk_req_zone_write_lock(rq);
370 rq->rq_flags |= RQF_STARTED;
371 return rq;
372}
373
374/*
375 * One confusing aspect here is that we get called for a specific
376 * hardware queue, but we return a request that may not be for a
377 * different hardware queue. This is because mq-deadline has shared
378 * state for all hardware queues, in terms of sorting, FIFOs, etc.
379 */
380static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
381{
382 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
383 struct request *rq;
384
385 spin_lock(&dd->lock);
386 rq = __dd_dispatch_request(dd);
387 spin_unlock(&dd->lock);
388
389 return rq;
390}
391
392static void dd_exit_queue(struct elevator_queue *e)
393{
394 struct deadline_data *dd = e->elevator_data;
395
396 BUG_ON(!list_empty(&dd->fifo_list[READ]));
397 BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
398
399 kfree(dd);
400}
401
402/*
403 * initialize elevator private data (deadline_data).
404 */
405static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
406{
407 struct deadline_data *dd;
408 struct elevator_queue *eq;
409
410 eq = elevator_alloc(q, e);
411 if (!eq)
412 return -ENOMEM;
413
414 dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
415 if (!dd) {
416 kobject_put(&eq->kobj);
417 return -ENOMEM;
418 }
419 eq->elevator_data = dd;
420
421 INIT_LIST_HEAD(&dd->fifo_list[READ]);
422 INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
423 dd->sort_list[READ] = RB_ROOT;
424 dd->sort_list[WRITE] = RB_ROOT;
425 dd->fifo_expire[READ] = read_expire;
426 dd->fifo_expire[WRITE] = write_expire;
427 dd->writes_starved = writes_starved;
428 dd->front_merges = 1;
429 dd->fifo_batch = fifo_batch;
430 spin_lock_init(&dd->lock);
431 spin_lock_init(&dd->zone_lock);
432 INIT_LIST_HEAD(&dd->dispatch);
433
434 q->elevator = eq;
435 return 0;
436}
437
438static int dd_request_merge(struct request_queue *q, struct request **rq,
439 struct bio *bio)
440{
441 struct deadline_data *dd = q->elevator->elevator_data;
442 sector_t sector = bio_end_sector(bio);
443 struct request *__rq;
444
445 if (!dd->front_merges)
446 return ELEVATOR_NO_MERGE;
447
448 __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
449 if (__rq) {
450 BUG_ON(sector != blk_rq_pos(__rq));
451
452 if (elv_bio_merge_ok(__rq, bio)) {
453 *rq = __rq;
454 return ELEVATOR_FRONT_MERGE;
455 }
456 }
457
458 return ELEVATOR_NO_MERGE;
459}
460
461static bool dd_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
462{
463 struct request_queue *q = hctx->queue;
464 struct deadline_data *dd = q->elevator->elevator_data;
465 struct request *free = NULL;
466 bool ret;
467
468 spin_lock(&dd->lock);
469 ret = blk_mq_sched_try_merge(q, bio, &free);
470 spin_unlock(&dd->lock);
471
472 if (free)
473 blk_mq_free_request(free);
474
475 return ret;
476}
477
478/*
479 * add rq to rbtree and fifo
480 */
481static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
482 bool at_head)
483{
484 struct request_queue *q = hctx->queue;
485 struct deadline_data *dd = q->elevator->elevator_data;
486 const int data_dir = rq_data_dir(rq);
487
488 /*
489 * This may be a requeue of a write request that has locked its
490 * target zone. If it is the case, this releases the zone lock.
491 */
492 blk_req_zone_write_unlock(rq);
493
494 if (blk_mq_sched_try_insert_merge(q, rq))
495 return;
496
497 blk_mq_sched_request_inserted(rq);
498
499 if (at_head || blk_rq_is_passthrough(rq)) {
500 if (at_head)
501 list_add(&rq->queuelist, &dd->dispatch);
502 else
503 list_add_tail(&rq->queuelist, &dd->dispatch);
504 } else {
505 deadline_add_rq_rb(dd, rq);
506
507 if (rq_mergeable(rq)) {
508 elv_rqhash_add(q, rq);
509 if (!q->last_merge)
510 q->last_merge = rq;
511 }
512
513 /*
514 * set expire time and add to fifo list
515 */
516 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
517 list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
518 }
519}
520
521static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
522 struct list_head *list, bool at_head)
523{
524 struct request_queue *q = hctx->queue;
525 struct deadline_data *dd = q->elevator->elevator_data;
526
527 spin_lock(&dd->lock);
528 while (!list_empty(list)) {
529 struct request *rq;
530
531 rq = list_first_entry(list, struct request, queuelist);
532 list_del_init(&rq->queuelist);
533 dd_insert_request(hctx, rq, at_head);
534 }
535 spin_unlock(&dd->lock);
536}
537
538/*
539 * Nothing to do here. This is defined only to ensure that .finish_request
540 * method is called upon request completion.
541 */
542static void dd_prepare_request(struct request *rq, struct bio *bio)
543{
544}
545
546/*
547 * For zoned block devices, write unlock the target zone of
548 * completed write requests. Do this while holding the zone lock
549 * spinlock so that the zone is never unlocked while deadline_fifo_request()
550 * or deadline_next_request() are executing. This function is called for
551 * all requests, whether or not these requests complete successfully.
552 */
553static void dd_finish_request(struct request *rq)
554{
555 struct request_queue *q = rq->q;
556
557 if (blk_queue_is_zoned(q)) {
558 struct deadline_data *dd = q->elevator->elevator_data;
559 unsigned long flags;
560
561 spin_lock_irqsave(&dd->zone_lock, flags);
562 blk_req_zone_write_unlock(rq);
563 spin_unlock_irqrestore(&dd->zone_lock, flags);
564 }
565}
566
567static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
568{
569 struct deadline_data *dd = hctx->queue->elevator->elevator_data;
570
571 return !list_empty_careful(&dd->dispatch) ||
572 !list_empty_careful(&dd->fifo_list[0]) ||
573 !list_empty_careful(&dd->fifo_list[1]);
574}
575
576/*
577 * sysfs parts below
578 */
579static ssize_t
580deadline_var_show(int var, char *page)
581{
582 return sprintf(page, "%d\n", var);
583}
584
585static void
586deadline_var_store(int *var, const char *page)
587{
588 char *p = (char *) page;
589
590 *var = simple_strtol(p, &p, 10);
591}
592
593#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
594static ssize_t __FUNC(struct elevator_queue *e, char *page) \
595{ \
596 struct deadline_data *dd = e->elevator_data; \
597 int __data = __VAR; \
598 if (__CONV) \
599 __data = jiffies_to_msecs(__data); \
600 return deadline_var_show(__data, (page)); \
601}
602SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
603SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
604SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
605SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
606SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
607#undef SHOW_FUNCTION
608
609#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
610static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
611{ \
612 struct deadline_data *dd = e->elevator_data; \
613 int __data; \
614 deadline_var_store(&__data, (page)); \
615 if (__data < (MIN)) \
616 __data = (MIN); \
617 else if (__data > (MAX)) \
618 __data = (MAX); \
619 if (__CONV) \
620 *(__PTR) = msecs_to_jiffies(__data); \
621 else \
622 *(__PTR) = __data; \
623 return count; \
624}
625STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
626STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
627STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
628STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
629STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
630#undef STORE_FUNCTION
631
632#define DD_ATTR(name) \
633 __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
634 deadline_##name##_store)
635
636static struct elv_fs_entry deadline_attrs[] = {
637 DD_ATTR(read_expire),
638 DD_ATTR(write_expire),
639 DD_ATTR(writes_starved),
640 DD_ATTR(front_merges),
641 DD_ATTR(fifo_batch),
642 __ATTR_NULL
643};
644
645#ifdef CONFIG_BLK_DEBUG_FS
646#define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name) \
647static void *deadline_##name##_fifo_start(struct seq_file *m, \
648 loff_t *pos) \
649 __acquires(&dd->lock) \
650{ \
651 struct request_queue *q = m->private; \
652 struct deadline_data *dd = q->elevator->elevator_data; \
653 \
654 spin_lock(&dd->lock); \
655 return seq_list_start(&dd->fifo_list[ddir], *pos); \
656} \
657 \
658static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \
659 loff_t *pos) \
660{ \
661 struct request_queue *q = m->private; \
662 struct deadline_data *dd = q->elevator->elevator_data; \
663 \
664 return seq_list_next(v, &dd->fifo_list[ddir], pos); \
665} \
666 \
667static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \
668 __releases(&dd->lock) \
669{ \
670 struct request_queue *q = m->private; \
671 struct deadline_data *dd = q->elevator->elevator_data; \
672 \
673 spin_unlock(&dd->lock); \
674} \
675 \
676static const struct seq_operations deadline_##name##_fifo_seq_ops = { \
677 .start = deadline_##name##_fifo_start, \
678 .next = deadline_##name##_fifo_next, \
679 .stop = deadline_##name##_fifo_stop, \
680 .show = blk_mq_debugfs_rq_show, \
681}; \
682 \
683static int deadline_##name##_next_rq_show(void *data, \
684 struct seq_file *m) \
685{ \
686 struct request_queue *q = data; \
687 struct deadline_data *dd = q->elevator->elevator_data; \
688 struct request *rq = dd->next_rq[ddir]; \
689 \
690 if (rq) \
691 __blk_mq_debugfs_rq_show(m, rq); \
692 return 0; \
693}
694DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
695DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
696#undef DEADLINE_DEBUGFS_DDIR_ATTRS
697
698static int deadline_batching_show(void *data, struct seq_file *m)
699{
700 struct request_queue *q = data;
701 struct deadline_data *dd = q->elevator->elevator_data;
702
703 seq_printf(m, "%u\n", dd->batching);
704 return 0;
705}
706
707static int deadline_starved_show(void *data, struct seq_file *m)
708{
709 struct request_queue *q = data;
710 struct deadline_data *dd = q->elevator->elevator_data;
711
712 seq_printf(m, "%u\n", dd->starved);
713 return 0;
714}
715
716static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
717 __acquires(&dd->lock)
718{
719 struct request_queue *q = m->private;
720 struct deadline_data *dd = q->elevator->elevator_data;
721
722 spin_lock(&dd->lock);
723 return seq_list_start(&dd->dispatch, *pos);
724}
725
726static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
727{
728 struct request_queue *q = m->private;
729 struct deadline_data *dd = q->elevator->elevator_data;
730
731 return seq_list_next(v, &dd->dispatch, pos);
732}
733
734static void deadline_dispatch_stop(struct seq_file *m, void *v)
735 __releases(&dd->lock)
736{
737 struct request_queue *q = m->private;
738 struct deadline_data *dd = q->elevator->elevator_data;
739
740 spin_unlock(&dd->lock);
741}
742
743static const struct seq_operations deadline_dispatch_seq_ops = {
744 .start = deadline_dispatch_start,
745 .next = deadline_dispatch_next,
746 .stop = deadline_dispatch_stop,
747 .show = blk_mq_debugfs_rq_show,
748};
749
750#define DEADLINE_QUEUE_DDIR_ATTRS(name) \
751 {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
752 {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
753static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
754 DEADLINE_QUEUE_DDIR_ATTRS(read),
755 DEADLINE_QUEUE_DDIR_ATTRS(write),
756 {"batching", 0400, deadline_batching_show},
757 {"starved", 0400, deadline_starved_show},
758 {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
759 {},
760};
761#undef DEADLINE_QUEUE_DDIR_ATTRS
762#endif
763
764static struct elevator_type mq_deadline = {
765 .ops.mq = {
766 .insert_requests = dd_insert_requests,
767 .dispatch_request = dd_dispatch_request,
768 .prepare_request = dd_prepare_request,
769 .finish_request = dd_finish_request,
770 .next_request = elv_rb_latter_request,
771 .former_request = elv_rb_former_request,
772 .bio_merge = dd_bio_merge,
773 .request_merge = dd_request_merge,
774 .requests_merged = dd_merged_requests,
775 .request_merged = dd_request_merged,
776 .has_work = dd_has_work,
777 .init_sched = dd_init_queue,
778 .exit_sched = dd_exit_queue,
779 },
780
781 .uses_mq = true,
782#ifdef CONFIG_BLK_DEBUG_FS
783 .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
784#endif
785 .elevator_attrs = deadline_attrs,
786 .elevator_name = "mq-deadline",
787 .elevator_alias = "deadline",
788 .elevator_owner = THIS_MODULE,
789};
790MODULE_ALIAS("mq-deadline-iosched");
791
792static int __init deadline_init(void)
793{
794 return elv_register(&mq_deadline);
795}
796
797static void __exit deadline_exit(void)
798{
799 elv_unregister(&mq_deadline);
800}
801
802module_init(deadline_init);
803module_exit(deadline_exit);
804
805MODULE_AUTHOR("Jens Axboe");
806MODULE_LICENSE("GPL");
807MODULE_DESCRIPTION("MQ deadline IO scheduler");