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