]> git.ipfire.org Git - thirdparty/kernel/stable.git/blame - block/elevator.c
drm/amdgpu: differentiate external rev id for gfx 11.5.0
[thirdparty/kernel/stable.git] / block / elevator.c
CommitLineData
3dcf60bc 1// SPDX-License-Identifier: GPL-2.0
1da177e4 2/*
1da177e4
LT
3 * Block device elevator/IO-scheduler.
4 *
5 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
6 *
0fe23479 7 * 30042000 Jens Axboe <axboe@kernel.dk> :
1da177e4
LT
8 *
9 * Split the elevator a bit so that it is possible to choose a different
10 * one or even write a new "plug in". There are three pieces:
11 * - elevator_fn, inserts a new request in the queue list
12 * - elevator_merge_fn, decides whether a new buffer can be merged with
13 * an existing request
14 * - elevator_dequeue_fn, called when a request is taken off the active list
15 *
16 * 20082000 Dave Jones <davej@suse.de> :
17 * Removed tests for max-bomb-segments, which was breaking elvtune
18 * when run without -bN
19 *
20 * Jens:
21 * - Rework again to work with bio instead of buffer_heads
22 * - loose bi_dev comparisons, partition handling is right now
23 * - completely modularize elevator setup and teardown
24 *
25 */
26#include <linux/kernel.h>
27#include <linux/fs.h>
28#include <linux/blkdev.h>
1da177e4 29#include <linux/bio.h>
1da177e4
LT
30#include <linux/module.h>
31#include <linux/slab.h>
32#include <linux/init.h>
33#include <linux/compiler.h>
2056a782 34#include <linux/blktrace_api.h>
9817064b 35#include <linux/hash.h>
0835da67 36#include <linux/uaccess.h>
c8158819 37#include <linux/pm_runtime.h>
1da177e4 38
55782138
LZ
39#include <trace/events/block.h>
40
2e9bc346 41#include "elevator.h"
242f9dcb 42#include "blk.h"
bd166ef1 43#include "blk-mq-sched.h"
bca6b067 44#include "blk-pm.h"
8330cdb0 45#include "blk-wbt.h"
672fdcf0 46#include "blk-cgroup.h"
242f9dcb 47
1da177e4
LT
48static DEFINE_SPINLOCK(elv_list_lock);
49static LIST_HEAD(elv_list);
50
9817064b
JA
51/*
52 * Merge hash stuff.
53 */
83096ebf 54#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
9817064b 55
da775265
JA
56/*
57 * Query io scheduler to see if the current process issuing bio may be
58 * merged with rq.
59 */
8d283ee6 60static bool elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio)
da775265 61{
165125e1 62 struct request_queue *q = rq->q;
b374d18a 63 struct elevator_queue *e = q->elevator;
da775265 64
f9cd4bfe
JA
65 if (e->type->ops.allow_merge)
66 return e->type->ops.allow_merge(q, rq, bio);
da775265 67
8d283ee6 68 return true;
da775265
JA
69}
70
1da177e4
LT
71/*
72 * can we safely merge with this request?
73 */
72ef799b 74bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
1da177e4 75{
050c8ea8 76 if (!blk_rq_merge_ok(rq, bio))
72ef799b 77 return false;
7ba1ba12 78
72ef799b
TE
79 if (!elv_iosched_allow_bio_merge(rq, bio))
80 return false;
1da177e4 81
72ef799b 82 return true;
1da177e4 83}
72ef799b 84EXPORT_SYMBOL(elv_bio_merge_ok);
1da177e4 85
ffb86425
CH
86static inline bool elv_support_features(struct request_queue *q,
87 const struct elevator_type *e)
8ac0d9a8 88{
ffb86425
CH
89 return (q->required_elevator_features & e->elevator_features) ==
90 q->required_elevator_features;
68c43f13
DLM
91}
92
93/**
f69b5e8f 94 * elevator_match - Check whether @e's name or alias matches @name
68c43f13
DLM
95 * @e: Scheduler to test
96 * @name: Elevator name to test
68c43f13 97 *
f69b5e8f 98 * Return true if the elevator @e's name or alias matches @name.
68c43f13 99 */
ffb86425 100static bool elevator_match(const struct elevator_type *e, const char *name)
68c43f13 101{
ffb86425
CH
102 return !strcmp(e->elevator_name, name) ||
103 (e->elevator_alias && !strcmp(e->elevator_alias, name));
8ac0d9a8
JA
104}
105
ffb86425 106static struct elevator_type *__elevator_find(const char *name)
1da177e4 107{
a22b169d 108 struct elevator_type *e;
1da177e4 109
ffb86425
CH
110 list_for_each_entry(e, &elv_list, list)
111 if (elevator_match(e, name))
a22b169d 112 return e;
a22b169d 113 return NULL;
1da177e4
LT
114}
115
81eaca44
CH
116static struct elevator_type *elevator_find_get(struct request_queue *q,
117 const char *name)
1da177e4 118{
2824bc93 119 struct elevator_type *e;
1da177e4 120
2a12dcd7 121 spin_lock(&elv_list_lock);
ffb86425
CH
122 e = __elevator_find(name);
123 if (e && (!elv_support_features(q, e) || !elevator_tryget(e)))
2824bc93 124 e = NULL;
2a12dcd7 125 spin_unlock(&elv_list_lock);
1da177e4
LT
126 return e;
127}
128
5f622417 129static const struct kobj_type elv_ktype;
3d1ab40f 130
d50235b7 131struct elevator_queue *elevator_alloc(struct request_queue *q,
165125e1 132 struct elevator_type *e)
3d1ab40f 133{
b374d18a 134 struct elevator_queue *eq;
9817064b 135
c1b511eb 136 eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node);
9817064b 137 if (unlikely(!eq))
8406a4d5 138 return NULL;
9817064b 139
8ed40ee3 140 __elevator_get(e);
22f746e2 141 eq->type = e;
f9cb074b 142 kobject_init(&eq->kobj, &elv_ktype);
9817064b 143 mutex_init(&eq->sysfs_lock);
242d98f0 144 hash_init(eq->hash);
9817064b 145
3d1ab40f
AV
146 return eq;
147}
d50235b7 148EXPORT_SYMBOL(elevator_alloc);
3d1ab40f
AV
149
150static void elevator_release(struct kobject *kobj)
151{
b374d18a 152 struct elevator_queue *e;
9817064b 153
b374d18a 154 e = container_of(kobj, struct elevator_queue, kobj);
22f746e2 155 elevator_put(e->type);
3d1ab40f
AV
156 kfree(e);
157}
158
0c6cb3a2 159void elevator_exit(struct request_queue *q)
1da177e4 160{
0c6cb3a2
CH
161 struct elevator_queue *e = q->elevator;
162
28883074
CH
163 ioc_clear_queue(q);
164 blk_mq_sched_free_rqs(q);
165
3d1ab40f 166 mutex_lock(&e->sysfs_lock);
dd1c372d 167 blk_mq_exit_sched(q, e);
3d1ab40f 168 mutex_unlock(&e->sysfs_lock);
1da177e4 169
3d1ab40f 170 kobject_put(&e->kobj);
1da177e4 171}
2e662b65 172
9817064b
JA
173static inline void __elv_rqhash_del(struct request *rq)
174{
242d98f0 175 hash_del(&rq->hash);
e8064021 176 rq->rq_flags &= ~RQF_HASHED;
9817064b
JA
177}
178
70b3ea05 179void elv_rqhash_del(struct request_queue *q, struct request *rq)
9817064b
JA
180{
181 if (ELV_ON_HASH(rq))
182 __elv_rqhash_del(rq);
183}
bd166ef1 184EXPORT_SYMBOL_GPL(elv_rqhash_del);
9817064b 185
70b3ea05 186void elv_rqhash_add(struct request_queue *q, struct request *rq)
9817064b 187{
b374d18a 188 struct elevator_queue *e = q->elevator;
9817064b
JA
189
190 BUG_ON(ELV_ON_HASH(rq));
242d98f0 191 hash_add(e->hash, &rq->hash, rq_hash_key(rq));
e8064021 192 rq->rq_flags |= RQF_HASHED;
9817064b 193}
bd166ef1 194EXPORT_SYMBOL_GPL(elv_rqhash_add);
9817064b 195
70b3ea05 196void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
9817064b
JA
197{
198 __elv_rqhash_del(rq);
199 elv_rqhash_add(q, rq);
200}
201
70b3ea05 202struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
9817064b 203{
b374d18a 204 struct elevator_queue *e = q->elevator;
b67bfe0d 205 struct hlist_node *next;
9817064b
JA
206 struct request *rq;
207
ee89f812 208 hash_for_each_possible_safe(e->hash, rq, next, hash, offset) {
9817064b
JA
209 BUG_ON(!ELV_ON_HASH(rq));
210
211 if (unlikely(!rq_mergeable(rq))) {
212 __elv_rqhash_del(rq);
213 continue;
214 }
215
216 if (rq_hash_key(rq) == offset)
217 return rq;
218 }
219
220 return NULL;
221}
222
2e662b65
JA
223/*
224 * RB-tree support functions for inserting/lookup/removal of requests
225 * in a sorted RB tree.
226 */
796d5116 227void elv_rb_add(struct rb_root *root, struct request *rq)
2e662b65
JA
228{
229 struct rb_node **p = &root->rb_node;
230 struct rb_node *parent = NULL;
231 struct request *__rq;
232
233 while (*p) {
234 parent = *p;
235 __rq = rb_entry(parent, struct request, rb_node);
236
83096ebf 237 if (blk_rq_pos(rq) < blk_rq_pos(__rq))
2e662b65 238 p = &(*p)->rb_left;
796d5116 239 else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
2e662b65 240 p = &(*p)->rb_right;
2e662b65
JA
241 }
242
243 rb_link_node(&rq->rb_node, parent, p);
244 rb_insert_color(&rq->rb_node, root);
2e662b65 245}
2e662b65
JA
246EXPORT_SYMBOL(elv_rb_add);
247
248void elv_rb_del(struct rb_root *root, struct request *rq)
249{
250 BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
251 rb_erase(&rq->rb_node, root);
252 RB_CLEAR_NODE(&rq->rb_node);
253}
2e662b65
JA
254EXPORT_SYMBOL(elv_rb_del);
255
256struct request *elv_rb_find(struct rb_root *root, sector_t sector)
257{
258 struct rb_node *n = root->rb_node;
259 struct request *rq;
260
261 while (n) {
262 rq = rb_entry(n, struct request, rb_node);
263
83096ebf 264 if (sector < blk_rq_pos(rq))
2e662b65 265 n = n->rb_left;
83096ebf 266 else if (sector > blk_rq_pos(rq))
2e662b65
JA
267 n = n->rb_right;
268 else
269 return rq;
270 }
271
272 return NULL;
273}
2e662b65
JA
274EXPORT_SYMBOL(elv_rb_find);
275
34fe7c05
CH
276enum elv_merge elv_merge(struct request_queue *q, struct request **req,
277 struct bio *bio)
1da177e4 278{
b374d18a 279 struct elevator_queue *e = q->elevator;
9817064b 280 struct request *__rq;
06b86245 281
488991e2
AB
282 /*
283 * Levels of merges:
284 * nomerges: No merges at all attempted
285 * noxmerges: Only simple one-hit cache try
286 * merges: All merge tries attempted
287 */
7460d389 288 if (blk_queue_nomerges(q) || !bio_mergeable(bio))
488991e2
AB
289 return ELEVATOR_NO_MERGE;
290
9817064b
JA
291 /*
292 * First try one-hit cache.
293 */
72ef799b 294 if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) {
34fe7c05
CH
295 enum elv_merge ret = blk_try_merge(q->last_merge, bio);
296
06b86245
TH
297 if (ret != ELEVATOR_NO_MERGE) {
298 *req = q->last_merge;
299 return ret;
300 }
301 }
1da177e4 302
488991e2 303 if (blk_queue_noxmerges(q))
ac9fafa1
AB
304 return ELEVATOR_NO_MERGE;
305
9817064b
JA
306 /*
307 * See if our hash lookup can find a potential backmerge.
308 */
4f024f37 309 __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector);
72ef799b 310 if (__rq && elv_bio_merge_ok(__rq, bio)) {
9817064b 311 *req = __rq;
866663b7
ML
312
313 if (blk_discard_mergable(__rq))
314 return ELEVATOR_DISCARD_MERGE;
9817064b
JA
315 return ELEVATOR_BACK_MERGE;
316 }
317
f9cd4bfe
JA
318 if (e->type->ops.request_merge)
319 return e->type->ops.request_merge(q, req, bio);
1da177e4
LT
320
321 return ELEVATOR_NO_MERGE;
322}
323
5e84ea3a
JA
324/*
325 * Attempt to do an insertion back merge. Only check for the case where
326 * we can append 'rq' to an existing request, so we can throw 'rq' away
327 * afterwards.
328 *
fd2ef39c
JK
329 * Returns true if we merged, false otherwise. 'free' will contain all
330 * requests that need to be freed.
5e84ea3a 331 */
fd2ef39c
JK
332bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq,
333 struct list_head *free)
5e84ea3a
JA
334{
335 struct request *__rq;
bee0393c 336 bool ret;
5e84ea3a
JA
337
338 if (blk_queue_nomerges(q))
339 return false;
340
341 /*
342 * First try one-hit cache.
343 */
fd2ef39c
JK
344 if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) {
345 list_add(&rq->queuelist, free);
5e84ea3a 346 return true;
fd2ef39c 347 }
5e84ea3a
JA
348
349 if (blk_queue_noxmerges(q))
350 return false;
351
bee0393c 352 ret = false;
5e84ea3a
JA
353 /*
354 * See if our hash lookup can find a potential backmerge.
355 */
bee0393c
SL
356 while (1) {
357 __rq = elv_rqhash_find(q, blk_rq_pos(rq));
358 if (!__rq || !blk_attempt_req_merge(q, __rq, rq))
359 break;
360
fd2ef39c 361 list_add(&rq->queuelist, free);
bee0393c
SL
362 /* The merged request could be merged with others, try again */
363 ret = true;
364 rq = __rq;
365 }
27419322 366
bee0393c 367 return ret;
5e84ea3a
JA
368}
369
34fe7c05
CH
370void elv_merged_request(struct request_queue *q, struct request *rq,
371 enum elv_merge type)
1da177e4 372{
b374d18a 373 struct elevator_queue *e = q->elevator;
1da177e4 374
f9cd4bfe
JA
375 if (e->type->ops.request_merged)
376 e->type->ops.request_merged(q, rq, type);
06b86245 377
2e662b65
JA
378 if (type == ELEVATOR_BACK_MERGE)
379 elv_rqhash_reposition(q, rq);
9817064b 380
06b86245 381 q->last_merge = rq;
1da177e4
LT
382}
383
165125e1 384void elv_merge_requests(struct request_queue *q, struct request *rq,
1da177e4
LT
385 struct request *next)
386{
b374d18a 387 struct elevator_queue *e = q->elevator;
bd166ef1 388
f9cd4bfe
JA
389 if (e->type->ops.requests_merged)
390 e->type->ops.requests_merged(q, rq, next);
06b86245 391
9817064b 392 elv_rqhash_reposition(q, rq);
06b86245 393 q->last_merge = rq;
1da177e4
LT
394}
395
165125e1 396struct request *elv_latter_request(struct request_queue *q, struct request *rq)
1da177e4 397{
b374d18a 398 struct elevator_queue *e = q->elevator;
1da177e4 399
f9cd4bfe
JA
400 if (e->type->ops.next_request)
401 return e->type->ops.next_request(q, rq);
bd166ef1 402
1da177e4
LT
403 return NULL;
404}
405
165125e1 406struct request *elv_former_request(struct request_queue *q, struct request *rq)
1da177e4 407{
b374d18a 408 struct elevator_queue *e = q->elevator;
1da177e4 409
f9cd4bfe
JA
410 if (e->type->ops.former_request)
411 return e->type->ops.former_request(q, rq);
bd166ef1 412
a1ce35fa 413 return NULL;
1da177e4
LT
414}
415
3d1ab40f
AV
416#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
417
418static ssize_t
419elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
1da177e4 420{
3d1ab40f 421 struct elv_fs_entry *entry = to_elv(attr);
b374d18a 422 struct elevator_queue *e;
3d1ab40f
AV
423 ssize_t error;
424
425 if (!entry->show)
426 return -EIO;
427
b374d18a 428 e = container_of(kobj, struct elevator_queue, kobj);
3d1ab40f 429 mutex_lock(&e->sysfs_lock);
22f746e2 430 error = e->type ? entry->show(e, page) : -ENOENT;
3d1ab40f
AV
431 mutex_unlock(&e->sysfs_lock);
432 return error;
433}
1da177e4 434
3d1ab40f
AV
435static ssize_t
436elv_attr_store(struct kobject *kobj, struct attribute *attr,
437 const char *page, size_t length)
438{
3d1ab40f 439 struct elv_fs_entry *entry = to_elv(attr);
b374d18a 440 struct elevator_queue *e;
3d1ab40f 441 ssize_t error;
1da177e4 442
3d1ab40f
AV
443 if (!entry->store)
444 return -EIO;
1da177e4 445
b374d18a 446 e = container_of(kobj, struct elevator_queue, kobj);
3d1ab40f 447 mutex_lock(&e->sysfs_lock);
22f746e2 448 error = e->type ? entry->store(e, page, length) : -ENOENT;
3d1ab40f
AV
449 mutex_unlock(&e->sysfs_lock);
450 return error;
451}
452
52cf25d0 453static const struct sysfs_ops elv_sysfs_ops = {
3d1ab40f
AV
454 .show = elv_attr_show,
455 .store = elv_attr_store,
456};
457
5f622417 458static const struct kobj_type elv_ktype = {
3d1ab40f
AV
459 .sysfs_ops = &elv_sysfs_ops,
460 .release = elevator_release,
461};
462
cecf5d87 463int elv_register_queue(struct request_queue *q, bool uevent)
3d1ab40f 464{
5a5bafdc 465 struct elevator_queue *e = q->elevator;
3d1ab40f
AV
466 int error;
467
f0c6ae09
YY
468 lockdep_assert_held(&q->sysfs_lock);
469
2bd85221 470 error = kobject_add(&e->kobj, &q->disk->queue_kobj, "iosched");
3d1ab40f 471 if (!error) {
22f746e2 472 struct elv_fs_entry *attr = e->type->elevator_attrs;
3d1ab40f 473 if (attr) {
e572ec7e
AV
474 while (attr->attr.name) {
475 if (sysfs_create_file(&e->kobj, &attr->attr))
3d1ab40f 476 break;
e572ec7e 477 attr++;
3d1ab40f
AV
478 }
479 }
cecf5d87
ML
480 if (uevent)
481 kobject_uevent(&e->kobj, KOBJ_ADD);
482
181d0663 483 set_bit(ELEVATOR_FLAG_REGISTERED, &e->flags);
3d1ab40f
AV
484 }
485 return error;
1da177e4 486}
bc1c1169 487
1da177e4
LT
488void elv_unregister_queue(struct request_queue *q)
489{
f5ec592d
EB
490 struct elevator_queue *e = q->elevator;
491
f0c6ae09
YY
492 lockdep_assert_held(&q->sysfs_lock);
493
181d0663 494 if (e && test_and_clear_bit(ELEVATOR_FLAG_REGISTERED, &e->flags)) {
f8fc877d
TH
495 kobject_uevent(&e->kobj, KOBJ_REMOVE);
496 kobject_del(&e->kobj);
f8fc877d 497 }
1da177e4
LT
498}
499
e567bf71 500int elv_register(struct elevator_type *e)
1da177e4 501{
e5c0ca13
CZ
502 /* finish request is mandatory */
503 if (WARN_ON_ONCE(!e->ops.finish_request))
504 return -EINVAL;
e42cfb1d
DLM
505 /* insert_requests and dispatch_request are mandatory */
506 if (WARN_ON_ONCE(!e->ops.insert_requests || !e->ops.dispatch_request))
507 return -EINVAL;
508
3d3c2379
TH
509 /* create icq_cache if requested */
510 if (e->icq_size) {
511 if (WARN_ON(e->icq_size < sizeof(struct io_cq)) ||
512 WARN_ON(e->icq_align < __alignof__(struct io_cq)))
513 return -EINVAL;
514
515 snprintf(e->icq_cache_name, sizeof(e->icq_cache_name),
516 "%s_io_cq", e->elevator_name);
517 e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size,
518 e->icq_align, 0, NULL);
519 if (!e->icq_cache)
520 return -ENOMEM;
521 }
522
523 /* register, don't allow duplicate names */
2a12dcd7 524 spin_lock(&elv_list_lock);
ffb86425 525 if (__elevator_find(e->elevator_name)) {
3d3c2379 526 spin_unlock(&elv_list_lock);
62d2a194 527 kmem_cache_destroy(e->icq_cache);
3d3c2379
TH
528 return -EBUSY;
529 }
1da177e4 530 list_add_tail(&e->list, &elv_list);
2a12dcd7 531 spin_unlock(&elv_list_lock);
1da177e4 532
d0b0a81a
HT
533 printk(KERN_INFO "io scheduler %s registered\n", e->elevator_name);
534
3d3c2379 535 return 0;
1da177e4
LT
536}
537EXPORT_SYMBOL_GPL(elv_register);
538
539void elv_unregister(struct elevator_type *e)
540{
3d3c2379 541 /* unregister */
2a12dcd7 542 spin_lock(&elv_list_lock);
1da177e4 543 list_del_init(&e->list);
2a12dcd7 544 spin_unlock(&elv_list_lock);
3d3c2379
TH
545
546 /*
547 * Destroy icq_cache if it exists. icq's are RCU managed. Make
548 * sure all RCU operations are complete before proceeding.
549 */
550 if (e->icq_cache) {
551 rcu_barrier();
552 kmem_cache_destroy(e->icq_cache);
553 e->icq_cache = NULL;
554 }
1da177e4
LT
555}
556EXPORT_SYMBOL_GPL(elv_unregister);
557
61db437d
DLM
558static inline bool elv_support_iosched(struct request_queue *q)
559{
6251b754 560 if (!queue_is_mq(q) ||
7a7c5e71 561 (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED)))
61db437d
DLM
562 return false;
563 return true;
564}
565
131d08e1 566/*
a0958ba7
DLM
567 * For single queue devices, default to using mq-deadline. If we have multiple
568 * queues or mq-deadline is not available, default to "none".
569 */
570static struct elevator_type *elevator_get_default(struct request_queue *q)
571{
90b71980
BVA
572 if (q->tag_set && q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT)
573 return NULL;
574
580dca81 575 if (q->nr_hw_queues != 1 &&
079a2e3e 576 !blk_mq_is_shared_tags(q->tag_set->flags))
a0958ba7
DLM
577 return NULL;
578
81eaca44 579 return elevator_find_get(q, "mq-deadline");
a0958ba7
DLM
580}
581
582/*
583 * Get the first elevator providing the features required by the request queue.
584 * Default to "none" if no matching elevator is found.
585 */
586static struct elevator_type *elevator_get_by_features(struct request_queue *q)
587{
a2614255 588 struct elevator_type *e, *found = NULL;
a0958ba7
DLM
589
590 spin_lock(&elv_list_lock);
591
592 list_for_each_entry(e, &elv_list, list) {
ffb86425 593 if (elv_support_features(q, e)) {
a2614255 594 found = e;
a0958ba7 595 break;
a2614255 596 }
a0958ba7
DLM
597 }
598
dd6f7f17 599 if (found && !elevator_tryget(found))
a2614255 600 found = NULL;
a0958ba7
DLM
601
602 spin_unlock(&elv_list_lock);
a2614255 603 return found;
a0958ba7
DLM
604}
605
606/*
607 * For a device queue that has no required features, use the default elevator
608 * settings. Otherwise, use the first elevator available matching the required
609 * features. If no suitable elevator is find or if the chosen elevator
610 * initialization fails, fall back to the "none" elevator (no elevator).
131d08e1 611 */
954b4a5c 612void elevator_init_mq(struct request_queue *q)
131d08e1
CH
613{
614 struct elevator_type *e;
954b4a5c 615 int err;
131d08e1 616
61db437d 617 if (!elv_support_iosched(q))
954b4a5c 618 return;
61db437d 619
75e6c00f 620 WARN_ON_ONCE(blk_queue_registered(q));
c48dac13 621
131d08e1 622 if (unlikely(q->elevator))
954b4a5c 623 return;
131d08e1 624
a0958ba7
DLM
625 if (!q->required_elevator_features)
626 e = elevator_get_default(q);
627 else
628 e = elevator_get_by_features(q);
131d08e1 629 if (!e)
954b4a5c 630 return;
131d08e1 631
245a489e
ML
632 /*
633 * We are called before adding disk, when there isn't any FS I/O,
634 * so freezing queue plus canceling dispatch work is enough to
635 * drain any dispatch activities originated from passthrough
636 * requests, then no need to quiesce queue which may add long boot
637 * latency, especially when lots of disks are involved.
638 */
737eb78e 639 blk_mq_freeze_queue(q);
245a489e 640 blk_mq_cancel_work_sync(q);
737eb78e 641
131d08e1 642 err = blk_mq_init_sched(q, e);
737eb78e 643
737eb78e
DLM
644 blk_mq_unfreeze_queue(q);
645
954b4a5c
DLM
646 if (err) {
647 pr_warn("\"%s\" elevator initialization failed, "
648 "falling back to \"none\"\n", e->elevator_name);
954b4a5c 649 }
8ed40ee3
JC
650
651 elevator_put(e);
131d08e1 652}
131d08e1 653
1da177e4 654/*
ac1171bd
JC
655 * Switch to new_e io scheduler.
656 *
657 * If switching fails, we are most likely running out of memory and not able
658 * to restore the old io scheduler, so leaving the io scheduler being none.
1da177e4 659 */
8237c01f 660int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
1da177e4 661{
64b36075 662 int ret;
1da177e4 663
14a23498
BVA
664 lockdep_assert_held(&q->sysfs_lock);
665
a1ce35fa
JA
666 blk_mq_freeze_queue(q);
667 blk_mq_quiesce_queue(q);
4722dc52 668
64b36075
CH
669 if (q->elevator) {
670 elv_unregister_queue(q);
671 elevator_exit(q);
672 }
673
674 ret = blk_mq_init_sched(q, new_e);
675 if (ret)
676 goto out_unfreeze;
677
678 ret = elv_register_queue(q, true);
679 if (ret) {
680 elevator_exit(q);
681 goto out_unfreeze;
682 }
683 blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
1da177e4 684
64b36075 685out_unfreeze:
a1ce35fa
JA
686 blk_mq_unquiesce_queue(q);
687 blk_mq_unfreeze_queue(q);
e0cca8bc
JC
688
689 if (ret) {
690 pr_warn("elv: switch to \"%s\" failed, falling back to \"none\"\n",
691 new_e->elevator_name);
692 }
693
64b36075
CH
694 return ret;
695}
696
697void elevator_disable(struct request_queue *q)
698{
699 lockdep_assert_held(&q->sysfs_lock);
75ad23bc 700
64b36075
CH
701 blk_mq_freeze_queue(q);
702 blk_mq_quiesce_queue(q);
703
704 elv_unregister_queue(q);
705 elevator_exit(q);
706 blk_queue_flag_clear(QUEUE_FLAG_SQ_SCHED, q);
707 q->elevator = NULL;
708 q->nr_requests = q->tag_set->queue_depth;
709 blk_add_trace_msg(q, "elv switch: none");
710
711 blk_mq_unquiesce_queue(q);
712 blk_mq_unfreeze_queue(q);
1da177e4
LT
713}
714
5dd531a0
JA
715/*
716 * Switch this queue to the given IO scheduler.
717 */
58367c8a 718static int elevator_change(struct request_queue *q, const char *elevator_name)
1da177e4 719{
1da177e4 720 struct elevator_type *e;
8ed40ee3 721 int ret;
1da177e4 722
e9a823fb 723 /* Make sure queue is not in the middle of being removed */
58c898ba 724 if (!blk_queue_registered(q))
e9a823fb
DJ
725 return -ENOENT;
726
58367c8a 727 if (!strncmp(elevator_name, "none", 4)) {
64b36075
CH
728 if (q->elevator)
729 elevator_disable(q);
730 return 0;
fbd72127 731 }
cd43e26f 732
ffb86425 733 if (q->elevator && elevator_match(q->elevator->type, elevator_name))
b54c2ad9
JC
734 return 0;
735
81eaca44
CH
736 e = elevator_find_get(q, elevator_name);
737 if (!e) {
738 request_module("%s-iosched", elevator_name);
739 e = elevator_find_get(q, elevator_name);
740 if (!e)
741 return -EINVAL;
742 }
8ed40ee3
JC
743 ret = elevator_switch(q, e);
744 elevator_put(e);
745 return ret;
5dd531a0 746}
7c8a3679 747
58367c8a 748ssize_t elv_iosched_store(struct request_queue *q, const char *buf,
5dd531a0
JA
749 size_t count)
750{
58367c8a 751 char elevator_name[ELV_NAME_MAX];
5dd531a0
JA
752 int ret;
753
6251b754 754 if (!elv_support_iosched(q))
5dd531a0
JA
755 return count;
756
20d09975 757 strscpy(elevator_name, buf, sizeof(elevator_name));
58367c8a 758 ret = elevator_change(q, strstrip(elevator_name));
5dd531a0
JA
759 if (!ret)
760 return count;
5dd531a0 761 return ret;
1da177e4
LT
762}
763
165125e1 764ssize_t elv_iosched_show(struct request_queue *q, char *name)
1da177e4 765{
16095af2
CH
766 struct elevator_queue *eq = q->elevator;
767 struct elevator_type *cur = NULL, *e;
1da177e4
LT
768 int len = 0;
769
aae2a643 770 if (!elv_support_iosched(q))
cd43e26f
MP
771 return sprintf(name, "none\n");
772
7919d679 773 if (!q->elevator) {
bd166ef1 774 len += sprintf(name+len, "[none] ");
7919d679
JC
775 } else {
776 len += sprintf(name+len, "none ");
16095af2 777 cur = eq->type;
7919d679 778 }
cd43e26f 779
2a12dcd7 780 spin_lock(&elv_list_lock);
16095af2 781 list_for_each_entry(e, &elv_list, list) {
5998249e 782 if (e == cur)
7a3b3660 783 len += sprintf(name+len, "[%s] ", e->elevator_name);
5998249e 784 else if (elv_support_features(q, e))
16095af2 785 len += sprintf(name+len, "%s ", e->elevator_name);
1da177e4 786 }
2a12dcd7 787 spin_unlock(&elv_list_lock);
1da177e4 788
c6451ede 789 len += sprintf(name+len, "\n");
1da177e4
LT
790 return len;
791}
792
165125e1
JA
793struct request *elv_rb_former_request(struct request_queue *q,
794 struct request *rq)
2e662b65
JA
795{
796 struct rb_node *rbprev = rb_prev(&rq->rb_node);
797
798 if (rbprev)
799 return rb_entry_rq(rbprev);
800
801 return NULL;
802}
2e662b65
JA
803EXPORT_SYMBOL(elv_rb_former_request);
804
165125e1
JA
805struct request *elv_rb_latter_request(struct request_queue *q,
806 struct request *rq)
2e662b65
JA
807{
808 struct rb_node *rbnext = rb_next(&rq->rb_node);
809
810 if (rbnext)
811 return rb_entry_rq(rbnext);
812
813 return NULL;
814}
2e662b65 815EXPORT_SYMBOL(elv_rb_latter_request);
f8db3835
JK
816
817static int __init elevator_setup(char *str)
818{
819 pr_warn("Kernel parameter elevator= does not have any effect anymore.\n"
820 "Please use sysfs to set IO scheduler for individual devices.\n");
821 return 1;
822}
823
824__setup("elevator=", elevator_setup);