c56f211c84400662f3e18c137b51c3f5406e20fd
[linux-2.6-microblaze.git] / block / mq-deadline.c
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  */
29 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
30 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
31 static const int writes_starved = 2;    /* max times reads can starve a write */
32 static const int fifo_batch = 16;       /* # of sequential requests treated as one
33                                      by the above parameters. For throughput. */
34
35 struct 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
66 static inline struct rb_root *
67 deadline_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  */
75 static inline struct request *
76 deadline_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
86 static void
87 deadline_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
94 static inline void
95 deadline_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  */
108 static 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
125 static 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
139 static 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  */
163 static void
164 deadline_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  */
182 static 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  */
199 static struct request *
200 deadline_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;
225 out:
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  */
235 static struct request *
236 deadline_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  */
270 static 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) {
318 dispatch_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
330 dispatch_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
359 dispatch_request:
360         /*
361          * rq is the selected appropriate request.
362          */
363         dd->batching++;
364         deadline_move_request(dd, rq);
365 done:
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  */
380 static 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
392 static 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  */
405 static 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
438 static 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
461 static 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  */
481 static 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
521 static 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  * For zoned block devices, write unlock the target zone of
540  * completed write requests. Do this while holding the zone lock
541  * spinlock so that the zone is never unlocked while deadline_fifo_request()
542  * while deadline_next_request() are executing.
543  */
544 static void dd_completed_request(struct request *rq)
545 {
546         struct request_queue *q = rq->q;
547
548         if (blk_queue_is_zoned(q)) {
549                 struct deadline_data *dd = q->elevator->elevator_data;
550                 unsigned long flags;
551
552                 spin_lock_irqsave(&dd->zone_lock, flags);
553                 blk_req_zone_write_unlock(rq);
554                 spin_unlock_irqrestore(&dd->zone_lock, flags);
555         }
556 }
557
558 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
559 {
560         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
561
562         return !list_empty_careful(&dd->dispatch) ||
563                 !list_empty_careful(&dd->fifo_list[0]) ||
564                 !list_empty_careful(&dd->fifo_list[1]);
565 }
566
567 /*
568  * sysfs parts below
569  */
570 static ssize_t
571 deadline_var_show(int var, char *page)
572 {
573         return sprintf(page, "%d\n", var);
574 }
575
576 static void
577 deadline_var_store(int *var, const char *page)
578 {
579         char *p = (char *) page;
580
581         *var = simple_strtol(p, &p, 10);
582 }
583
584 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
585 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
586 {                                                                       \
587         struct deadline_data *dd = e->elevator_data;                    \
588         int __data = __VAR;                                             \
589         if (__CONV)                                                     \
590                 __data = jiffies_to_msecs(__data);                      \
591         return deadline_var_show(__data, (page));                       \
592 }
593 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
594 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
595 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
596 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
597 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
598 #undef SHOW_FUNCTION
599
600 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
601 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
602 {                                                                       \
603         struct deadline_data *dd = e->elevator_data;                    \
604         int __data;                                                     \
605         deadline_var_store(&__data, (page));                            \
606         if (__data < (MIN))                                             \
607                 __data = (MIN);                                         \
608         else if (__data > (MAX))                                        \
609                 __data = (MAX);                                         \
610         if (__CONV)                                                     \
611                 *(__PTR) = msecs_to_jiffies(__data);                    \
612         else                                                            \
613                 *(__PTR) = __data;                                      \
614         return count;                                                   \
615 }
616 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
617 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
618 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
619 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
620 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
621 #undef STORE_FUNCTION
622
623 #define DD_ATTR(name) \
624         __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
625                                       deadline_##name##_store)
626
627 static struct elv_fs_entry deadline_attrs[] = {
628         DD_ATTR(read_expire),
629         DD_ATTR(write_expire),
630         DD_ATTR(writes_starved),
631         DD_ATTR(front_merges),
632         DD_ATTR(fifo_batch),
633         __ATTR_NULL
634 };
635
636 #ifdef CONFIG_BLK_DEBUG_FS
637 #define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)                         \
638 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
639                                           loff_t *pos)                  \
640         __acquires(&dd->lock)                                           \
641 {                                                                       \
642         struct request_queue *q = m->private;                           \
643         struct deadline_data *dd = q->elevator->elevator_data;          \
644                                                                         \
645         spin_lock(&dd->lock);                                           \
646         return seq_list_start(&dd->fifo_list[ddir], *pos);              \
647 }                                                                       \
648                                                                         \
649 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
650                                          loff_t *pos)                   \
651 {                                                                       \
652         struct request_queue *q = m->private;                           \
653         struct deadline_data *dd = q->elevator->elevator_data;          \
654                                                                         \
655         return seq_list_next(v, &dd->fifo_list[ddir], pos);             \
656 }                                                                       \
657                                                                         \
658 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
659         __releases(&dd->lock)                                           \
660 {                                                                       \
661         struct request_queue *q = m->private;                           \
662         struct deadline_data *dd = q->elevator->elevator_data;          \
663                                                                         \
664         spin_unlock(&dd->lock);                                         \
665 }                                                                       \
666                                                                         \
667 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
668         .start  = deadline_##name##_fifo_start,                         \
669         .next   = deadline_##name##_fifo_next,                          \
670         .stop   = deadline_##name##_fifo_stop,                          \
671         .show   = blk_mq_debugfs_rq_show,                               \
672 };                                                                      \
673                                                                         \
674 static int deadline_##name##_next_rq_show(void *data,                   \
675                                           struct seq_file *m)           \
676 {                                                                       \
677         struct request_queue *q = data;                                 \
678         struct deadline_data *dd = q->elevator->elevator_data;          \
679         struct request *rq = dd->next_rq[ddir];                         \
680                                                                         \
681         if (rq)                                                         \
682                 __blk_mq_debugfs_rq_show(m, rq);                        \
683         return 0;                                                       \
684 }
685 DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
686 DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
687 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
688
689 static int deadline_batching_show(void *data, struct seq_file *m)
690 {
691         struct request_queue *q = data;
692         struct deadline_data *dd = q->elevator->elevator_data;
693
694         seq_printf(m, "%u\n", dd->batching);
695         return 0;
696 }
697
698 static int deadline_starved_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->starved);
704         return 0;
705 }
706
707 static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
708         __acquires(&dd->lock)
709 {
710         struct request_queue *q = m->private;
711         struct deadline_data *dd = q->elevator->elevator_data;
712
713         spin_lock(&dd->lock);
714         return seq_list_start(&dd->dispatch, *pos);
715 }
716
717 static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
718 {
719         struct request_queue *q = m->private;
720         struct deadline_data *dd = q->elevator->elevator_data;
721
722         return seq_list_next(v, &dd->dispatch, pos);
723 }
724
725 static void deadline_dispatch_stop(struct seq_file *m, void *v)
726         __releases(&dd->lock)
727 {
728         struct request_queue *q = m->private;
729         struct deadline_data *dd = q->elevator->elevator_data;
730
731         spin_unlock(&dd->lock);
732 }
733
734 static const struct seq_operations deadline_dispatch_seq_ops = {
735         .start  = deadline_dispatch_start,
736         .next   = deadline_dispatch_next,
737         .stop   = deadline_dispatch_stop,
738         .show   = blk_mq_debugfs_rq_show,
739 };
740
741 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                         \
742         {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
743         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
744 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
745         DEADLINE_QUEUE_DDIR_ATTRS(read),
746         DEADLINE_QUEUE_DDIR_ATTRS(write),
747         {"batching", 0400, deadline_batching_show},
748         {"starved", 0400, deadline_starved_show},
749         {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
750         {},
751 };
752 #undef DEADLINE_QUEUE_DDIR_ATTRS
753 #endif
754
755 static struct elevator_type mq_deadline = {
756         .ops.mq = {
757                 .insert_requests        = dd_insert_requests,
758                 .dispatch_request       = dd_dispatch_request,
759                 .completed_request      = dd_completed_request,
760                 .next_request           = elv_rb_latter_request,
761                 .former_request         = elv_rb_former_request,
762                 .bio_merge              = dd_bio_merge,
763                 .request_merge          = dd_request_merge,
764                 .requests_merged        = dd_merged_requests,
765                 .request_merged         = dd_request_merged,
766                 .has_work               = dd_has_work,
767                 .init_sched             = dd_init_queue,
768                 .exit_sched             = dd_exit_queue,
769         },
770
771         .uses_mq        = true,
772 #ifdef CONFIG_BLK_DEBUG_FS
773         .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
774 #endif
775         .elevator_attrs = deadline_attrs,
776         .elevator_name = "mq-deadline",
777         .elevator_alias = "deadline",
778         .elevator_owner = THIS_MODULE,
779 };
780 MODULE_ALIAS("mq-deadline-iosched");
781
782 static int __init deadline_init(void)
783 {
784         return elv_register(&mq_deadline);
785 }
786
787 static void __exit deadline_exit(void)
788 {
789         elv_unregister(&mq_deadline);
790 }
791
792 module_init(deadline_init);
793 module_exit(deadline_exit);
794
795 MODULE_AUTHOR("Jens Axboe");
796 MODULE_LICENSE("GPL");
797 MODULE_DESCRIPTION("MQ deadline IO scheduler");