GNU Linux-libre 5.10.219-gnu1
[releases.git] / block / mq-deadline.c
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 "blk.h"
22 #include "blk-mq.h"
23 #include "blk-mq-debugfs.h"
24 #include "blk-mq-tag.h"
25 #include "blk-mq-sched.h"
26
27 /*
28  * See Documentation/block/deadline-iosched.rst
29  */
30 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
31 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
32 static const int writes_starved = 2;    /* max times reads can starve a write */
33 static const int fifo_batch = 16;       /* # of sequential requests treated as one
34                                      by the above parameters. For throughput. */
35
36 struct deadline_data {
37         /*
38          * run time data
39          */
40
41         /*
42          * requests (deadline_rq s) are present on both sort_list and fifo_list
43          */
44         struct rb_root sort_list[2];
45         struct list_head fifo_list[2];
46
47         /*
48          * next in sort order. read, write or both are NULL
49          */
50         struct request *next_rq[2];
51         unsigned int batching;          /* number of sequential requests made */
52         unsigned int starved;           /* times reads have starved writes */
53
54         /*
55          * settings that change how the i/o scheduler behaves
56          */
57         int fifo_expire[2];
58         int fifo_batch;
59         int writes_starved;
60         int front_merges;
61
62         spinlock_t lock;
63         spinlock_t zone_lock;
64         struct list_head dispatch;
65 };
66
67 static inline struct rb_root *
68 deadline_rb_root(struct deadline_data *dd, struct request *rq)
69 {
70         return &dd->sort_list[rq_data_dir(rq)];
71 }
72
73 /*
74  * get the request after `rq' in sector-sorted order
75  */
76 static inline struct request *
77 deadline_latter_request(struct request *rq)
78 {
79         struct rb_node *node = rb_next(&rq->rb_node);
80
81         if (node)
82                 return rb_entry_rq(node);
83
84         return NULL;
85 }
86
87 static void
88 deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
89 {
90         struct rb_root *root = deadline_rb_root(dd, rq);
91
92         elv_rb_add(root, rq);
93 }
94
95 static inline void
96 deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
97 {
98         const int data_dir = rq_data_dir(rq);
99
100         if (dd->next_rq[data_dir] == rq)
101                 dd->next_rq[data_dir] = deadline_latter_request(rq);
102
103         elv_rb_del(deadline_rb_root(dd, rq), rq);
104 }
105
106 /*
107  * remove rq from rbtree and fifo.
108  */
109 static void deadline_remove_request(struct request_queue *q, struct request *rq)
110 {
111         struct deadline_data *dd = q->elevator->elevator_data;
112
113         list_del_init(&rq->queuelist);
114
115         /*
116          * We might not be on the rbtree, if we are doing an insert merge
117          */
118         if (!RB_EMPTY_NODE(&rq->rb_node))
119                 deadline_del_rq_rb(dd, rq);
120
121         elv_rqhash_del(q, rq);
122         if (q->last_merge == rq)
123                 q->last_merge = NULL;
124 }
125
126 static void dd_request_merged(struct request_queue *q, struct request *req,
127                               enum elv_merge type)
128 {
129         struct deadline_data *dd = q->elevator->elevator_data;
130
131         /*
132          * if the merge was a front merge, we need to reposition request
133          */
134         if (type == ELEVATOR_FRONT_MERGE) {
135                 elv_rb_del(deadline_rb_root(dd, req), req);
136                 deadline_add_rq_rb(dd, req);
137         }
138 }
139
140 static void dd_merged_requests(struct request_queue *q, struct request *req,
141                                struct request *next)
142 {
143         /*
144          * if next expires before rq, assign its expire time to rq
145          * and move into next position (next will be deleted) in fifo
146          */
147         if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
148                 if (time_before((unsigned long)next->fifo_time,
149                                 (unsigned long)req->fifo_time)) {
150                         list_move(&req->queuelist, &next->queuelist);
151                         req->fifo_time = next->fifo_time;
152                 }
153         }
154
155         /*
156          * kill knowledge of next, this one is a goner
157          */
158         deadline_remove_request(q, next);
159 }
160
161 /*
162  * move an entry to dispatch queue
163  */
164 static void
165 deadline_move_request(struct deadline_data *dd, struct request *rq)
166 {
167         const int data_dir = rq_data_dir(rq);
168
169         dd->next_rq[READ] = NULL;
170         dd->next_rq[WRITE] = NULL;
171         dd->next_rq[data_dir] = deadline_latter_request(rq);
172
173         /*
174          * take it off the sort and fifo list
175          */
176         deadline_remove_request(rq->q, rq);
177 }
178
179 /*
180  * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
181  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
182  */
183 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
184 {
185         struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
186
187         /*
188          * rq is expired!
189          */
190         if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
191                 return 1;
192
193         return 0;
194 }
195
196 /*
197  * For the specified data direction, return the next request to
198  * dispatch using arrival ordered lists.
199  */
200 static struct request *
201 deadline_fifo_request(struct deadline_data *dd, int data_dir)
202 {
203         struct request *rq;
204         unsigned long flags;
205
206         if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
207                 return NULL;
208
209         if (list_empty(&dd->fifo_list[data_dir]))
210                 return NULL;
211
212         rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
213         if (data_dir == READ || !blk_queue_is_zoned(rq->q))
214                 return rq;
215
216         /*
217          * Look for a write request that can be dispatched, that is one with
218          * an unlocked target zone.
219          */
220         spin_lock_irqsave(&dd->zone_lock, flags);
221         list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
222                 if (blk_req_can_dispatch_to_zone(rq))
223                         goto out;
224         }
225         rq = NULL;
226 out:
227         spin_unlock_irqrestore(&dd->zone_lock, flags);
228
229         return rq;
230 }
231
232 /*
233  * For the specified data direction, return the next request to
234  * dispatch using sector position sorted lists.
235  */
236 static struct request *
237 deadline_next_request(struct deadline_data *dd, int data_dir)
238 {
239         struct request *rq;
240         unsigned long flags;
241
242         if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
243                 return NULL;
244
245         rq = dd->next_rq[data_dir];
246         if (!rq)
247                 return NULL;
248
249         if (data_dir == READ || !blk_queue_is_zoned(rq->q))
250                 return rq;
251
252         /*
253          * Look for a write request that can be dispatched, that is one with
254          * an unlocked target zone.
255          */
256         spin_lock_irqsave(&dd->zone_lock, flags);
257         while (rq) {
258                 if (blk_req_can_dispatch_to_zone(rq))
259                         break;
260                 rq = deadline_latter_request(rq);
261         }
262         spin_unlock_irqrestore(&dd->zone_lock, flags);
263
264         return rq;
265 }
266
267 /*
268  * deadline_dispatch_requests selects the best request according to
269  * read/write expire, fifo_batch, etc
270  */
271 static struct request *__dd_dispatch_request(struct deadline_data *dd)
272 {
273         struct request *rq, *next_rq;
274         bool reads, writes;
275         int data_dir;
276
277         if (!list_empty(&dd->dispatch)) {
278                 rq = list_first_entry(&dd->dispatch, struct request, queuelist);
279                 list_del_init(&rq->queuelist);
280                 goto done;
281         }
282
283         reads = !list_empty(&dd->fifo_list[READ]);
284         writes = !list_empty(&dd->fifo_list[WRITE]);
285
286         /*
287          * batches are currently reads XOR writes
288          */
289         rq = deadline_next_request(dd, WRITE);
290         if (!rq)
291                 rq = deadline_next_request(dd, READ);
292
293         if (rq && dd->batching < dd->fifo_batch)
294                 /* we have a next request are still entitled to batch */
295                 goto dispatch_request;
296
297         /*
298          * at this point we are not running a batch. select the appropriate
299          * data direction (read / write)
300          */
301
302         if (reads) {
303                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
304
305                 if (deadline_fifo_request(dd, WRITE) &&
306                     (dd->starved++ >= dd->writes_starved))
307                         goto dispatch_writes;
308
309                 data_dir = READ;
310
311                 goto dispatch_find_request;
312         }
313
314         /*
315          * there are either no reads or writes have been starved
316          */
317
318         if (writes) {
319 dispatch_writes:
320                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
321
322                 dd->starved = 0;
323
324                 data_dir = WRITE;
325
326                 goto dispatch_find_request;
327         }
328
329         return NULL;
330
331 dispatch_find_request:
332         /*
333          * we are not running a batch, find best request for selected data_dir
334          */
335         next_rq = deadline_next_request(dd, data_dir);
336         if (deadline_check_fifo(dd, data_dir) || !next_rq) {
337                 /*
338                  * A deadline has expired, the last request was in the other
339                  * direction, or we have run out of higher-sectored requests.
340                  * Start again from the request with the earliest expiry time.
341                  */
342                 rq = deadline_fifo_request(dd, data_dir);
343         } else {
344                 /*
345                  * The last req was the same dir and we have a next request in
346                  * sort order. No expired requests so continue on from here.
347                  */
348                 rq = next_rq;
349         }
350
351         /*
352          * For a zoned block device, if we only have writes queued and none of
353          * them can be dispatched, rq will be NULL.
354          */
355         if (!rq)
356                 return NULL;
357
358         dd->batching = 0;
359
360 dispatch_request:
361         /*
362          * rq is the selected appropriate request.
363          */
364         dd->batching++;
365         deadline_move_request(dd, rq);
366 done:
367         /*
368          * If the request needs its target zone locked, do it.
369          */
370         blk_req_zone_write_lock(rq);
371         rq->rq_flags |= RQF_STARTED;
372         return rq;
373 }
374
375 /*
376  * One confusing aspect here is that we get called for a specific
377  * hardware queue, but we may return a request that is for a
378  * different hardware queue. This is because mq-deadline has shared
379  * state for all hardware queues, in terms of sorting, FIFOs, etc.
380  */
381 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
382 {
383         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
384         struct request *rq;
385
386         spin_lock(&dd->lock);
387         rq = __dd_dispatch_request(dd);
388         spin_unlock(&dd->lock);
389         if (rq)
390                 atomic_dec(&rq->mq_hctx->elevator_queued);
391
392         return rq;
393 }
394
395 static void dd_exit_queue(struct elevator_queue *e)
396 {
397         struct deadline_data *dd = e->elevator_data;
398
399         BUG_ON(!list_empty(&dd->fifo_list[READ]));
400         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
401
402         kfree(dd);
403 }
404
405 /*
406  * initialize elevator private data (deadline_data).
407  */
408 static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
409 {
410         struct deadline_data *dd;
411         struct elevator_queue *eq;
412
413         eq = elevator_alloc(q, e);
414         if (!eq)
415                 return -ENOMEM;
416
417         dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
418         if (!dd) {
419                 kobject_put(&eq->kobj);
420                 return -ENOMEM;
421         }
422         eq->elevator_data = dd;
423
424         INIT_LIST_HEAD(&dd->fifo_list[READ]);
425         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
426         dd->sort_list[READ] = RB_ROOT;
427         dd->sort_list[WRITE] = RB_ROOT;
428         dd->fifo_expire[READ] = read_expire;
429         dd->fifo_expire[WRITE] = write_expire;
430         dd->writes_starved = writes_starved;
431         dd->front_merges = 1;
432         dd->fifo_batch = fifo_batch;
433         spin_lock_init(&dd->lock);
434         spin_lock_init(&dd->zone_lock);
435         INIT_LIST_HEAD(&dd->dispatch);
436
437         q->elevator = eq;
438         return 0;
439 }
440
441 static int dd_request_merge(struct request_queue *q, struct request **rq,
442                             struct bio *bio)
443 {
444         struct deadline_data *dd = q->elevator->elevator_data;
445         sector_t sector = bio_end_sector(bio);
446         struct request *__rq;
447
448         if (!dd->front_merges)
449                 return ELEVATOR_NO_MERGE;
450
451         __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
452         if (__rq) {
453                 BUG_ON(sector != blk_rq_pos(__rq));
454
455                 if (elv_bio_merge_ok(__rq, bio)) {
456                         *rq = __rq;
457                         if (blk_discard_mergable(__rq))
458                                 return ELEVATOR_DISCARD_MERGE;
459                         return ELEVATOR_FRONT_MERGE;
460                 }
461         }
462
463         return ELEVATOR_NO_MERGE;
464 }
465
466 static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
467                 unsigned int nr_segs)
468 {
469         struct deadline_data *dd = q->elevator->elevator_data;
470         struct request *free = NULL;
471         bool ret;
472
473         spin_lock(&dd->lock);
474         ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
475         spin_unlock(&dd->lock);
476
477         if (free)
478                 blk_mq_free_request(free);
479
480         return ret;
481 }
482
483 /*
484  * add rq to rbtree and fifo
485  */
486 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
487                               bool at_head)
488 {
489         struct request_queue *q = hctx->queue;
490         struct deadline_data *dd = q->elevator->elevator_data;
491         const int data_dir = rq_data_dir(rq);
492
493         /*
494          * This may be a requeue of a write request that has locked its
495          * target zone. If it is the case, this releases the zone lock.
496          */
497         blk_req_zone_write_unlock(rq);
498
499         if (blk_mq_sched_try_insert_merge(q, rq))
500                 return;
501
502         blk_mq_sched_request_inserted(rq);
503
504         if (at_head || blk_rq_is_passthrough(rq)) {
505                 if (at_head)
506                         list_add(&rq->queuelist, &dd->dispatch);
507                 else
508                         list_add_tail(&rq->queuelist, &dd->dispatch);
509         } else {
510                 deadline_add_rq_rb(dd, rq);
511
512                 if (rq_mergeable(rq)) {
513                         elv_rqhash_add(q, rq);
514                         if (!q->last_merge)
515                                 q->last_merge = rq;
516                 }
517
518                 /*
519                  * set expire time and add to fifo list
520                  */
521                 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
522                 list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
523         }
524 }
525
526 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
527                                struct list_head *list, bool at_head)
528 {
529         struct request_queue *q = hctx->queue;
530         struct deadline_data *dd = q->elevator->elevator_data;
531
532         spin_lock(&dd->lock);
533         while (!list_empty(list)) {
534                 struct request *rq;
535
536                 rq = list_first_entry(list, struct request, queuelist);
537                 list_del_init(&rq->queuelist);
538                 dd_insert_request(hctx, rq, at_head);
539                 atomic_inc(&hctx->elevator_queued);
540         }
541         spin_unlock(&dd->lock);
542 }
543
544 /*
545  * Nothing to do here. This is defined only to ensure that .finish_request
546  * method is called upon request completion.
547  */
548 static void dd_prepare_request(struct request *rq)
549 {
550 }
551
552 /*
553  * For zoned block devices, write unlock the target zone of
554  * completed write requests. Do this while holding the zone lock
555  * spinlock so that the zone is never unlocked while deadline_fifo_request()
556  * or deadline_next_request() are executing. This function is called for
557  * all requests, whether or not these requests complete successfully.
558  *
559  * For a zoned block device, __dd_dispatch_request() may have stopped
560  * dispatching requests if all the queued requests are write requests directed
561  * at zones that are already locked due to on-going write requests. To ensure
562  * write request dispatch progress in this case, mark the queue as needing a
563  * restart to ensure that the queue is run again after completion of the
564  * request and zones being unlocked.
565  */
566 static void dd_finish_request(struct request *rq)
567 {
568         struct request_queue *q = rq->q;
569
570         if (blk_queue_is_zoned(q)) {
571                 struct deadline_data *dd = q->elevator->elevator_data;
572                 unsigned long flags;
573
574                 spin_lock_irqsave(&dd->zone_lock, flags);
575                 blk_req_zone_write_unlock(rq);
576                 if (!list_empty(&dd->fifo_list[WRITE]))
577                         blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
578                 spin_unlock_irqrestore(&dd->zone_lock, flags);
579         }
580 }
581
582 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
583 {
584         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
585
586         if (!atomic_read(&hctx->elevator_queued))
587                 return false;
588
589         return !list_empty_careful(&dd->dispatch) ||
590                 !list_empty_careful(&dd->fifo_list[0]) ||
591                 !list_empty_careful(&dd->fifo_list[1]);
592 }
593
594 /*
595  * sysfs parts below
596  */
597 static ssize_t
598 deadline_var_show(int var, char *page)
599 {
600         return sprintf(page, "%d\n", var);
601 }
602
603 static void
604 deadline_var_store(int *var, const char *page)
605 {
606         char *p = (char *) page;
607
608         *var = simple_strtol(p, &p, 10);
609 }
610
611 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
612 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
613 {                                                                       \
614         struct deadline_data *dd = e->elevator_data;                    \
615         int __data = __VAR;                                             \
616         if (__CONV)                                                     \
617                 __data = jiffies_to_msecs(__data);                      \
618         return deadline_var_show(__data, (page));                       \
619 }
620 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
621 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
622 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
623 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
624 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
625 #undef SHOW_FUNCTION
626
627 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
628 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
629 {                                                                       \
630         struct deadline_data *dd = e->elevator_data;                    \
631         int __data;                                                     \
632         deadline_var_store(&__data, (page));                            \
633         if (__data < (MIN))                                             \
634                 __data = (MIN);                                         \
635         else if (__data > (MAX))                                        \
636                 __data = (MAX);                                         \
637         if (__CONV)                                                     \
638                 *(__PTR) = msecs_to_jiffies(__data);                    \
639         else                                                            \
640                 *(__PTR) = __data;                                      \
641         return count;                                                   \
642 }
643 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
644 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
645 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
646 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
647 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
648 #undef STORE_FUNCTION
649
650 #define DD_ATTR(name) \
651         __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
652
653 static struct elv_fs_entry deadline_attrs[] = {
654         DD_ATTR(read_expire),
655         DD_ATTR(write_expire),
656         DD_ATTR(writes_starved),
657         DD_ATTR(front_merges),
658         DD_ATTR(fifo_batch),
659         __ATTR_NULL
660 };
661
662 #ifdef CONFIG_BLK_DEBUG_FS
663 #define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)                         \
664 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
665                                           loff_t *pos)                  \
666         __acquires(&dd->lock)                                           \
667 {                                                                       \
668         struct request_queue *q = m->private;                           \
669         struct deadline_data *dd = q->elevator->elevator_data;          \
670                                                                         \
671         spin_lock(&dd->lock);                                           \
672         return seq_list_start(&dd->fifo_list[ddir], *pos);              \
673 }                                                                       \
674                                                                         \
675 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
676                                          loff_t *pos)                   \
677 {                                                                       \
678         struct request_queue *q = m->private;                           \
679         struct deadline_data *dd = q->elevator->elevator_data;          \
680                                                                         \
681         return seq_list_next(v, &dd->fifo_list[ddir], pos);             \
682 }                                                                       \
683                                                                         \
684 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
685         __releases(&dd->lock)                                           \
686 {                                                                       \
687         struct request_queue *q = m->private;                           \
688         struct deadline_data *dd = q->elevator->elevator_data;          \
689                                                                         \
690         spin_unlock(&dd->lock);                                         \
691 }                                                                       \
692                                                                         \
693 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
694         .start  = deadline_##name##_fifo_start,                         \
695         .next   = deadline_##name##_fifo_next,                          \
696         .stop   = deadline_##name##_fifo_stop,                          \
697         .show   = blk_mq_debugfs_rq_show,                               \
698 };                                                                      \
699                                                                         \
700 static int deadline_##name##_next_rq_show(void *data,                   \
701                                           struct seq_file *m)           \
702 {                                                                       \
703         struct request_queue *q = data;                                 \
704         struct deadline_data *dd = q->elevator->elevator_data;          \
705         struct request *rq = dd->next_rq[ddir];                         \
706                                                                         \
707         if (rq)                                                         \
708                 __blk_mq_debugfs_rq_show(m, rq);                        \
709         return 0;                                                       \
710 }
711 DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
712 DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
713 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
714
715 static int deadline_batching_show(void *data, struct seq_file *m)
716 {
717         struct request_queue *q = data;
718         struct deadline_data *dd = q->elevator->elevator_data;
719
720         seq_printf(m, "%u\n", dd->batching);
721         return 0;
722 }
723
724 static int deadline_starved_show(void *data, struct seq_file *m)
725 {
726         struct request_queue *q = data;
727         struct deadline_data *dd = q->elevator->elevator_data;
728
729         seq_printf(m, "%u\n", dd->starved);
730         return 0;
731 }
732
733 static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
734         __acquires(&dd->lock)
735 {
736         struct request_queue *q = m->private;
737         struct deadline_data *dd = q->elevator->elevator_data;
738
739         spin_lock(&dd->lock);
740         return seq_list_start(&dd->dispatch, *pos);
741 }
742
743 static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
744 {
745         struct request_queue *q = m->private;
746         struct deadline_data *dd = q->elevator->elevator_data;
747
748         return seq_list_next(v, &dd->dispatch, pos);
749 }
750
751 static void deadline_dispatch_stop(struct seq_file *m, void *v)
752         __releases(&dd->lock)
753 {
754         struct request_queue *q = m->private;
755         struct deadline_data *dd = q->elevator->elevator_data;
756
757         spin_unlock(&dd->lock);
758 }
759
760 static const struct seq_operations deadline_dispatch_seq_ops = {
761         .start  = deadline_dispatch_start,
762         .next   = deadline_dispatch_next,
763         .stop   = deadline_dispatch_stop,
764         .show   = blk_mq_debugfs_rq_show,
765 };
766
767 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                         \
768         {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
769         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
770 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
771         DEADLINE_QUEUE_DDIR_ATTRS(read),
772         DEADLINE_QUEUE_DDIR_ATTRS(write),
773         {"batching", 0400, deadline_batching_show},
774         {"starved", 0400, deadline_starved_show},
775         {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
776         {},
777 };
778 #undef DEADLINE_QUEUE_DDIR_ATTRS
779 #endif
780
781 static struct elevator_type mq_deadline = {
782         .ops = {
783                 .insert_requests        = dd_insert_requests,
784                 .dispatch_request       = dd_dispatch_request,
785                 .prepare_request        = dd_prepare_request,
786                 .finish_request         = dd_finish_request,
787                 .next_request           = elv_rb_latter_request,
788                 .former_request         = elv_rb_former_request,
789                 .bio_merge              = dd_bio_merge,
790                 .request_merge          = dd_request_merge,
791                 .requests_merged        = dd_merged_requests,
792                 .request_merged         = dd_request_merged,
793                 .has_work               = dd_has_work,
794                 .init_sched             = dd_init_queue,
795                 .exit_sched             = dd_exit_queue,
796         },
797
798 #ifdef CONFIG_BLK_DEBUG_FS
799         .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
800 #endif
801         .elevator_attrs = deadline_attrs,
802         .elevator_name = "mq-deadline",
803         .elevator_alias = "deadline",
804         .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
805         .elevator_owner = THIS_MODULE,
806 };
807 MODULE_ALIAS("mq-deadline-iosched");
808
809 static int __init deadline_init(void)
810 {
811         return elv_register(&mq_deadline);
812 }
813
814 static void __exit deadline_exit(void)
815 {
816         elv_unregister(&mq_deadline);
817 }
818
819 module_init(deadline_init);
820 module_exit(deadline_exit);
821
822 MODULE_AUTHOR("Jens Axboe");
823 MODULE_LICENSE("GPL");
824 MODULE_DESCRIPTION("MQ deadline IO scheduler");