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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
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> |
eea8f41c | 38 | #include <linux/blk-cgroup.h> |
1da177e4 | 39 | |
55782138 LZ |
40 | #include <trace/events/block.h> |
41 | ||
242f9dcb | 42 | #include "blk.h" |
bd166ef1 | 43 | #include "blk-mq-sched.h" |
8330cdb0 | 44 | #include "blk-wbt.h" |
242f9dcb | 45 | |
1da177e4 LT |
46 | static DEFINE_SPINLOCK(elv_list_lock); |
47 | static LIST_HEAD(elv_list); | |
48 | ||
9817064b JA |
49 | /* |
50 | * Merge hash stuff. | |
51 | */ | |
83096ebf | 52 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 53 | |
da775265 JA |
54 | /* |
55 | * Query io scheduler to see if the current process issuing bio may be | |
56 | * merged with rq. | |
57 | */ | |
72ef799b | 58 | static int elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio) |
da775265 | 59 | { |
165125e1 | 60 | struct request_queue *q = rq->q; |
b374d18a | 61 | struct elevator_queue *e = q->elevator; |
da775265 | 62 | |
bd166ef1 JA |
63 | if (e->uses_mq && e->type->ops.mq.allow_merge) |
64 | return e->type->ops.mq.allow_merge(q, rq, bio); | |
65 | else if (!e->uses_mq && e->type->ops.sq.elevator_allow_bio_merge_fn) | |
c51ca6cf | 66 | return e->type->ops.sq.elevator_allow_bio_merge_fn(q, rq, bio); |
da775265 JA |
67 | |
68 | return 1; | |
69 | } | |
70 | ||
1da177e4 LT |
71 | /* |
72 | * can we safely merge with this request? | |
73 | */ | |
72ef799b | 74 | bool 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 | 84 | EXPORT_SYMBOL(elv_bio_merge_ok); |
1da177e4 | 85 | |
8ac0d9a8 JA |
86 | static bool elevator_match(const struct elevator_type *e, const char *name) |
87 | { | |
88 | if (!strcmp(e->elevator_name, name)) | |
89 | return true; | |
90 | if (e->elevator_alias && !strcmp(e->elevator_alias, name)) | |
91 | return true; | |
92 | ||
93 | return false; | |
94 | } | |
95 | ||
2527d997 JA |
96 | /* |
97 | * Return scheduler with name 'name' and with matching 'mq capability | |
98 | */ | |
99 | static struct elevator_type *elevator_find(const char *name, bool mq) | |
1da177e4 | 100 | { |
a22b169d | 101 | struct elevator_type *e; |
1da177e4 | 102 | |
70cee26e | 103 | list_for_each_entry(e, &elv_list, list) { |
8ac0d9a8 | 104 | if (elevator_match(e, name) && (mq == e->uses_mq)) |
a22b169d | 105 | return e; |
1da177e4 | 106 | } |
1da177e4 | 107 | |
a22b169d | 108 | return NULL; |
1da177e4 LT |
109 | } |
110 | ||
111 | static void elevator_put(struct elevator_type *e) | |
112 | { | |
113 | module_put(e->elevator_owner); | |
114 | } | |
115 | ||
2527d997 JA |
116 | static struct elevator_type *elevator_get(struct request_queue *q, |
117 | const char *name, bool try_loading) | |
1da177e4 | 118 | { |
2824bc93 | 119 | struct elevator_type *e; |
1da177e4 | 120 | |
2a12dcd7 | 121 | spin_lock(&elv_list_lock); |
2824bc93 | 122 | |
2527d997 | 123 | e = elevator_find(name, q->mq_ops != NULL); |
21c3c5d2 | 124 | if (!e && try_loading) { |
e1640949 | 125 | spin_unlock(&elv_list_lock); |
490b94be | 126 | request_module("%s-iosched", name); |
e1640949 | 127 | spin_lock(&elv_list_lock); |
2527d997 | 128 | e = elevator_find(name, q->mq_ops != NULL); |
e1640949 JA |
129 | } |
130 | ||
2824bc93 TH |
131 | if (e && !try_module_get(e->elevator_owner)) |
132 | e = NULL; | |
133 | ||
2a12dcd7 | 134 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
135 | return e; |
136 | } | |
137 | ||
484fc254 | 138 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 139 | |
5f003976 | 140 | static int __init elevator_setup(char *str) |
1da177e4 | 141 | { |
752a3b79 CE |
142 | /* |
143 | * Be backwards-compatible with previous kernels, so users | |
144 | * won't get the wrong elevator. | |
145 | */ | |
492af635 | 146 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 147 | return 1; |
1da177e4 LT |
148 | } |
149 | ||
150 | __setup("elevator=", elevator_setup); | |
151 | ||
bb813f4c TH |
152 | /* called during boot to load the elevator chosen by the elevator param */ |
153 | void __init load_default_elevator_module(void) | |
154 | { | |
155 | struct elevator_type *e; | |
156 | ||
157 | if (!chosen_elevator[0]) | |
158 | return; | |
159 | ||
2527d997 JA |
160 | /* |
161 | * Boot parameter is deprecated, we haven't supported that for MQ. | |
162 | * Only look for non-mq schedulers from here. | |
163 | */ | |
bb813f4c | 164 | spin_lock(&elv_list_lock); |
2527d997 | 165 | e = elevator_find(chosen_elevator, false); |
bb813f4c TH |
166 | spin_unlock(&elv_list_lock); |
167 | ||
168 | if (!e) | |
169 | request_module("%s-iosched", chosen_elevator); | |
170 | } | |
171 | ||
3d1ab40f AV |
172 | static struct kobj_type elv_ktype; |
173 | ||
d50235b7 | 174 | struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 175 | struct elevator_type *e) |
3d1ab40f | 176 | { |
b374d18a | 177 | struct elevator_queue *eq; |
9817064b | 178 | |
c1b511eb | 179 | eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node); |
9817064b | 180 | if (unlikely(!eq)) |
8406a4d5 | 181 | return NULL; |
9817064b | 182 | |
22f746e2 | 183 | eq->type = e; |
f9cb074b | 184 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b | 185 | mutex_init(&eq->sysfs_lock); |
242d98f0 | 186 | hash_init(eq->hash); |
bd166ef1 | 187 | eq->uses_mq = e->uses_mq; |
9817064b | 188 | |
3d1ab40f AV |
189 | return eq; |
190 | } | |
d50235b7 | 191 | EXPORT_SYMBOL(elevator_alloc); |
3d1ab40f AV |
192 | |
193 | static void elevator_release(struct kobject *kobj) | |
194 | { | |
b374d18a | 195 | struct elevator_queue *e; |
9817064b | 196 | |
b374d18a | 197 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 198 | elevator_put(e->type); |
3d1ab40f AV |
199 | kfree(e); |
200 | } | |
201 | ||
165125e1 | 202 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
203 | { |
204 | struct elevator_type *e = NULL; | |
f8fc877d | 205 | int err; |
1da177e4 | 206 | |
eb1c160b TS |
207 | /* |
208 | * q->sysfs_lock must be held to provide mutual exclusion between | |
209 | * elevator_switch() and here. | |
210 | */ | |
211 | lockdep_assert_held(&q->sysfs_lock); | |
212 | ||
1abec4fd MS |
213 | if (unlikely(q->elevator)) |
214 | return 0; | |
215 | ||
cb98fc8b TH |
216 | INIT_LIST_HEAD(&q->queue_head); |
217 | q->last_merge = NULL; | |
218 | q->end_sector = 0; | |
219 | q->boundary_rq = NULL; | |
cb98fc8b | 220 | |
4eb166d9 | 221 | if (name) { |
2527d997 | 222 | e = elevator_get(q, name, true); |
4eb166d9 JA |
223 | if (!e) |
224 | return -EINVAL; | |
225 | } | |
1da177e4 | 226 | |
21c3c5d2 | 227 | /* |
d1a987f3 JA |
228 | * Use the default elevator specified by config boot param for |
229 | * non-mq devices, or by config option. Don't try to load modules | |
230 | * as we could be running off async and request_module() isn't | |
231 | * allowed from async. | |
21c3c5d2 | 232 | */ |
d1a987f3 | 233 | if (!e && !q->mq_ops && *chosen_elevator) { |
2527d997 | 234 | e = elevator_get(q, chosen_elevator, false); |
4eb166d9 JA |
235 | if (!e) |
236 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
237 | chosen_elevator); | |
238 | } | |
248d5ca5 | 239 | |
4eb166d9 | 240 | if (!e) { |
b86dd815 JA |
241 | /* |
242 | * For blk-mq devices, we default to using mq-deadline, | |
243 | * if available, for single queue devices. If deadline | |
244 | * isn't available OR we have multiple queues, default | |
245 | * to "none". | |
246 | */ | |
247 | if (q->mq_ops) { | |
248 | if (q->nr_hw_queues == 1) | |
2527d997 | 249 | e = elevator_get(q, "mq-deadline", false); |
b86dd815 JA |
250 | if (!e) |
251 | return 0; | |
252 | } else | |
2527d997 | 253 | e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false); |
d3484991 | 254 | |
4eb166d9 JA |
255 | if (!e) { |
256 | printk(KERN_ERR | |
257 | "Default I/O scheduler not found. " \ | |
b86dd815 | 258 | "Using noop.\n"); |
2527d997 | 259 | e = elevator_get(q, "noop", false); |
4eb166d9 | 260 | } |
5f003976 ND |
261 | } |
262 | ||
6917ff0b OS |
263 | if (e->uses_mq) |
264 | err = blk_mq_init_sched(q, e); | |
265 | else | |
bd166ef1 | 266 | err = e->ops.sq.elevator_init_fn(q, e); |
6917ff0b | 267 | if (err) |
d32f6b57 SM |
268 | elevator_put(e); |
269 | return err; | |
1da177e4 | 270 | } |
2e662b65 JA |
271 | EXPORT_SYMBOL(elevator_init); |
272 | ||
54d5329d | 273 | void elevator_exit(struct request_queue *q, struct elevator_queue *e) |
1da177e4 | 274 | { |
3d1ab40f | 275 | mutex_lock(&e->sysfs_lock); |
bd166ef1 | 276 | if (e->uses_mq && e->type->ops.mq.exit_sched) |
54d5329d | 277 | blk_mq_exit_sched(q, e); |
bd166ef1 | 278 | else if (!e->uses_mq && e->type->ops.sq.elevator_exit_fn) |
c51ca6cf | 279 | e->type->ops.sq.elevator_exit_fn(e); |
3d1ab40f | 280 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 281 | |
3d1ab40f | 282 | kobject_put(&e->kobj); |
1da177e4 | 283 | } |
2e662b65 JA |
284 | EXPORT_SYMBOL(elevator_exit); |
285 | ||
9817064b JA |
286 | static inline void __elv_rqhash_del(struct request *rq) |
287 | { | |
242d98f0 | 288 | hash_del(&rq->hash); |
e8064021 | 289 | rq->rq_flags &= ~RQF_HASHED; |
9817064b JA |
290 | } |
291 | ||
70b3ea05 | 292 | void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
293 | { |
294 | if (ELV_ON_HASH(rq)) | |
295 | __elv_rqhash_del(rq); | |
296 | } | |
bd166ef1 | 297 | EXPORT_SYMBOL_GPL(elv_rqhash_del); |
9817064b | 298 | |
70b3ea05 | 299 | void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 300 | { |
b374d18a | 301 | struct elevator_queue *e = q->elevator; |
9817064b JA |
302 | |
303 | BUG_ON(ELV_ON_HASH(rq)); | |
242d98f0 | 304 | hash_add(e->hash, &rq->hash, rq_hash_key(rq)); |
e8064021 | 305 | rq->rq_flags |= RQF_HASHED; |
9817064b | 306 | } |
bd166ef1 | 307 | EXPORT_SYMBOL_GPL(elv_rqhash_add); |
9817064b | 308 | |
70b3ea05 | 309 | void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
310 | { |
311 | __elv_rqhash_del(rq); | |
312 | elv_rqhash_add(q, rq); | |
313 | } | |
314 | ||
70b3ea05 | 315 | struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 316 | { |
b374d18a | 317 | struct elevator_queue *e = q->elevator; |
b67bfe0d | 318 | struct hlist_node *next; |
9817064b JA |
319 | struct request *rq; |
320 | ||
ee89f812 | 321 | hash_for_each_possible_safe(e->hash, rq, next, hash, offset) { |
9817064b JA |
322 | BUG_ON(!ELV_ON_HASH(rq)); |
323 | ||
324 | if (unlikely(!rq_mergeable(rq))) { | |
325 | __elv_rqhash_del(rq); | |
326 | continue; | |
327 | } | |
328 | ||
329 | if (rq_hash_key(rq) == offset) | |
330 | return rq; | |
331 | } | |
332 | ||
333 | return NULL; | |
334 | } | |
335 | ||
2e662b65 JA |
336 | /* |
337 | * RB-tree support functions for inserting/lookup/removal of requests | |
338 | * in a sorted RB tree. | |
339 | */ | |
796d5116 | 340 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
341 | { |
342 | struct rb_node **p = &root->rb_node; | |
343 | struct rb_node *parent = NULL; | |
344 | struct request *__rq; | |
345 | ||
346 | while (*p) { | |
347 | parent = *p; | |
348 | __rq = rb_entry(parent, struct request, rb_node); | |
349 | ||
83096ebf | 350 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 351 | p = &(*p)->rb_left; |
796d5116 | 352 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 353 | p = &(*p)->rb_right; |
2e662b65 JA |
354 | } |
355 | ||
356 | rb_link_node(&rq->rb_node, parent, p); | |
357 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 358 | } |
2e662b65 JA |
359 | EXPORT_SYMBOL(elv_rb_add); |
360 | ||
361 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
362 | { | |
363 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
364 | rb_erase(&rq->rb_node, root); | |
365 | RB_CLEAR_NODE(&rq->rb_node); | |
366 | } | |
2e662b65 JA |
367 | EXPORT_SYMBOL(elv_rb_del); |
368 | ||
369 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
370 | { | |
371 | struct rb_node *n = root->rb_node; | |
372 | struct request *rq; | |
373 | ||
374 | while (n) { | |
375 | rq = rb_entry(n, struct request, rb_node); | |
376 | ||
83096ebf | 377 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 378 | n = n->rb_left; |
83096ebf | 379 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
380 | n = n->rb_right; |
381 | else | |
382 | return rq; | |
383 | } | |
384 | ||
385 | return NULL; | |
386 | } | |
2e662b65 JA |
387 | EXPORT_SYMBOL(elv_rb_find); |
388 | ||
8922e16c TH |
389 | /* |
390 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 391 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 392 | * specific elevators. |
8922e16c | 393 | */ |
165125e1 | 394 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
395 | { |
396 | sector_t boundary; | |
8922e16c TH |
397 | struct list_head *entry; |
398 | ||
06b86245 TH |
399 | if (q->last_merge == rq) |
400 | q->last_merge = NULL; | |
9817064b JA |
401 | |
402 | elv_rqhash_del(q, rq); | |
403 | ||
15853af9 | 404 | q->nr_sorted--; |
06b86245 | 405 | |
1b47f531 | 406 | boundary = q->end_sector; |
8922e16c TH |
407 | list_for_each_prev(entry, &q->queue_head) { |
408 | struct request *pos = list_entry_rq(entry); | |
409 | ||
7afafc8a | 410 | if (req_op(rq) != req_op(pos)) |
e17fc0a1 | 411 | break; |
783660b2 JA |
412 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
413 | break; | |
e8064021 | 414 | if (pos->rq_flags & (RQF_STARTED | RQF_SOFTBARRIER)) |
8922e16c | 415 | break; |
83096ebf TH |
416 | if (blk_rq_pos(rq) >= boundary) { |
417 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
418 | continue; |
419 | } else { | |
83096ebf | 420 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
421 | break; |
422 | } | |
83096ebf | 423 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
424 | break; |
425 | } | |
426 | ||
427 | list_add(&rq->queuelist, entry); | |
428 | } | |
2e662b65 JA |
429 | EXPORT_SYMBOL(elv_dispatch_sort); |
430 | ||
9817064b | 431 | /* |
2e662b65 JA |
432 | * Insert rq into dispatch queue of q. Queue lock must be held on |
433 | * entry. rq is added to the back of the dispatch queue. To be used by | |
434 | * specific elevators. | |
9817064b JA |
435 | */ |
436 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
437 | { | |
438 | if (q->last_merge == rq) | |
439 | q->last_merge = NULL; | |
440 | ||
441 | elv_rqhash_del(q, rq); | |
442 | ||
443 | q->nr_sorted--; | |
444 | ||
445 | q->end_sector = rq_end_sector(rq); | |
446 | q->boundary_rq = rq; | |
447 | list_add_tail(&rq->queuelist, &q->queue_head); | |
448 | } | |
2e662b65 JA |
449 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
450 | ||
34fe7c05 CH |
451 | enum elv_merge elv_merge(struct request_queue *q, struct request **req, |
452 | struct bio *bio) | |
1da177e4 | 453 | { |
b374d18a | 454 | struct elevator_queue *e = q->elevator; |
9817064b | 455 | struct request *__rq; |
06b86245 | 456 | |
488991e2 AB |
457 | /* |
458 | * Levels of merges: | |
459 | * nomerges: No merges at all attempted | |
460 | * noxmerges: Only simple one-hit cache try | |
461 | * merges: All merge tries attempted | |
462 | */ | |
7460d389 | 463 | if (blk_queue_nomerges(q) || !bio_mergeable(bio)) |
488991e2 AB |
464 | return ELEVATOR_NO_MERGE; |
465 | ||
9817064b JA |
466 | /* |
467 | * First try one-hit cache. | |
468 | */ | |
72ef799b | 469 | if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) { |
34fe7c05 CH |
470 | enum elv_merge ret = blk_try_merge(q->last_merge, bio); |
471 | ||
06b86245 TH |
472 | if (ret != ELEVATOR_NO_MERGE) { |
473 | *req = q->last_merge; | |
474 | return ret; | |
475 | } | |
476 | } | |
1da177e4 | 477 | |
488991e2 | 478 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
479 | return ELEVATOR_NO_MERGE; |
480 | ||
9817064b JA |
481 | /* |
482 | * See if our hash lookup can find a potential backmerge. | |
483 | */ | |
4f024f37 | 484 | __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); |
72ef799b | 485 | if (__rq && elv_bio_merge_ok(__rq, bio)) { |
9817064b JA |
486 | *req = __rq; |
487 | return ELEVATOR_BACK_MERGE; | |
488 | } | |
489 | ||
bd166ef1 JA |
490 | if (e->uses_mq && e->type->ops.mq.request_merge) |
491 | return e->type->ops.mq.request_merge(q, req, bio); | |
492 | else if (!e->uses_mq && e->type->ops.sq.elevator_merge_fn) | |
c51ca6cf | 493 | return e->type->ops.sq.elevator_merge_fn(q, req, bio); |
1da177e4 LT |
494 | |
495 | return ELEVATOR_NO_MERGE; | |
496 | } | |
497 | ||
5e84ea3a JA |
498 | /* |
499 | * Attempt to do an insertion back merge. Only check for the case where | |
500 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
501 | * afterwards. | |
502 | * | |
503 | * Returns true if we merged, false otherwise | |
504 | */ | |
bd166ef1 | 505 | bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq) |
5e84ea3a JA |
506 | { |
507 | struct request *__rq; | |
bee0393c | 508 | bool ret; |
5e84ea3a JA |
509 | |
510 | if (blk_queue_nomerges(q)) | |
511 | return false; | |
512 | ||
513 | /* | |
514 | * First try one-hit cache. | |
515 | */ | |
516 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
517 | return true; | |
518 | ||
519 | if (blk_queue_noxmerges(q)) | |
520 | return false; | |
521 | ||
bee0393c | 522 | ret = false; |
5e84ea3a JA |
523 | /* |
524 | * See if our hash lookup can find a potential backmerge. | |
525 | */ | |
bee0393c SL |
526 | while (1) { |
527 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
528 | if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) | |
529 | break; | |
530 | ||
531 | /* The merged request could be merged with others, try again */ | |
532 | ret = true; | |
533 | rq = __rq; | |
534 | } | |
27419322 | 535 | |
bee0393c | 536 | return ret; |
5e84ea3a JA |
537 | } |
538 | ||
34fe7c05 CH |
539 | void elv_merged_request(struct request_queue *q, struct request *rq, |
540 | enum elv_merge type) | |
1da177e4 | 541 | { |
b374d18a | 542 | struct elevator_queue *e = q->elevator; |
1da177e4 | 543 | |
bd166ef1 JA |
544 | if (e->uses_mq && e->type->ops.mq.request_merged) |
545 | e->type->ops.mq.request_merged(q, rq, type); | |
546 | else if (!e->uses_mq && e->type->ops.sq.elevator_merged_fn) | |
c51ca6cf | 547 | e->type->ops.sq.elevator_merged_fn(q, rq, type); |
06b86245 | 548 | |
2e662b65 JA |
549 | if (type == ELEVATOR_BACK_MERGE) |
550 | elv_rqhash_reposition(q, rq); | |
9817064b | 551 | |
06b86245 | 552 | q->last_merge = rq; |
1da177e4 LT |
553 | } |
554 | ||
165125e1 | 555 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
556 | struct request *next) |
557 | { | |
b374d18a | 558 | struct elevator_queue *e = q->elevator; |
bd166ef1 JA |
559 | bool next_sorted = false; |
560 | ||
561 | if (e->uses_mq && e->type->ops.mq.requests_merged) | |
562 | e->type->ops.mq.requests_merged(q, rq, next); | |
563 | else if (e->type->ops.sq.elevator_merge_req_fn) { | |
a1ae0f74 | 564 | next_sorted = (__force bool)(next->rq_flags & RQF_SORTED); |
bd166ef1 JA |
565 | if (next_sorted) |
566 | e->type->ops.sq.elevator_merge_req_fn(q, rq, next); | |
567 | } | |
06b86245 | 568 | |
9817064b | 569 | elv_rqhash_reposition(q, rq); |
9817064b | 570 | |
5e84ea3a JA |
571 | if (next_sorted) { |
572 | elv_rqhash_del(q, next); | |
573 | q->nr_sorted--; | |
574 | } | |
575 | ||
06b86245 | 576 | q->last_merge = rq; |
1da177e4 LT |
577 | } |
578 | ||
812d4026 DS |
579 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
580 | struct bio *bio) | |
581 | { | |
582 | struct elevator_queue *e = q->elevator; | |
583 | ||
bd166ef1 JA |
584 | if (WARN_ON_ONCE(e->uses_mq)) |
585 | return; | |
586 | ||
c51ca6cf JA |
587 | if (e->type->ops.sq.elevator_bio_merged_fn) |
588 | e->type->ops.sq.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
589 | } |
590 | ||
47fafbc7 | 591 | #ifdef CONFIG_PM |
c8158819 LM |
592 | static void blk_pm_requeue_request(struct request *rq) |
593 | { | |
e8064021 | 594 | if (rq->q->dev && !(rq->rq_flags & RQF_PM)) |
c8158819 LM |
595 | rq->q->nr_pending--; |
596 | } | |
597 | ||
598 | static void blk_pm_add_request(struct request_queue *q, struct request *rq) | |
599 | { | |
e8064021 | 600 | if (q->dev && !(rq->rq_flags & RQF_PM) && q->nr_pending++ == 0 && |
c8158819 LM |
601 | (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING)) |
602 | pm_request_resume(q->dev); | |
603 | } | |
604 | #else | |
605 | static inline void blk_pm_requeue_request(struct request *rq) {} | |
606 | static inline void blk_pm_add_request(struct request_queue *q, | |
607 | struct request *rq) | |
608 | { | |
609 | } | |
610 | #endif | |
611 | ||
165125e1 | 612 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 613 | { |
1da177e4 LT |
614 | /* |
615 | * it already went through dequeue, we need to decrement the | |
616 | * in_flight count again | |
617 | */ | |
8922e16c | 618 | if (blk_account_rq(rq)) { |
0a7ae2ff | 619 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 620 | if (rq->rq_flags & RQF_SORTED) |
cad97516 | 621 | elv_deactivate_rq(q, rq); |
8922e16c | 622 | } |
1da177e4 | 623 | |
e8064021 | 624 | rq->rq_flags &= ~RQF_STARTED; |
1da177e4 | 625 | |
c8158819 LM |
626 | blk_pm_requeue_request(rq); |
627 | ||
b710a480 | 628 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
629 | } |
630 | ||
26308eab | 631 | void elv_drain_elevator(struct request_queue *q) |
15853af9 | 632 | { |
bd166ef1 | 633 | struct elevator_queue *e = q->elevator; |
15853af9 | 634 | static int printed; |
e3c78ca5 | 635 | |
bd166ef1 JA |
636 | if (WARN_ON_ONCE(e->uses_mq)) |
637 | return; | |
638 | ||
e3c78ca5 TH |
639 | lockdep_assert_held(q->queue_lock); |
640 | ||
bd166ef1 | 641 | while (e->type->ops.sq.elevator_dispatch_fn(q, 1)) |
15853af9 | 642 | ; |
e3c78ca5 | 643 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
644 | printk(KERN_ERR "%s: forced dispatching is broken " |
645 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 646 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
647 | } |
648 | } | |
649 | ||
b710a480 | 650 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 651 | { |
5f3ea37c | 652 | trace_block_rq_insert(q, rq); |
2056a782 | 653 | |
c8158819 LM |
654 | blk_pm_add_request(q, rq); |
655 | ||
1da177e4 LT |
656 | rq->q = q; |
657 | ||
e8064021 | 658 | if (rq->rq_flags & RQF_SOFTBARRIER) { |
b710a480 | 659 | /* barriers are scheduling boundary, update end_sector */ |
57292b58 | 660 | if (!blk_rq_is_passthrough(rq)) { |
b710a480 JA |
661 | q->end_sector = rq_end_sector(rq); |
662 | q->boundary_rq = rq; | |
663 | } | |
e8064021 | 664 | } else if (!(rq->rq_flags & RQF_ELVPRIV) && |
3aa72873 JA |
665 | (where == ELEVATOR_INSERT_SORT || |
666 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
667 | where = ELEVATOR_INSERT_BACK; |
668 | ||
8922e16c | 669 | switch (where) { |
28e7d184 | 670 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 671 | case ELEVATOR_INSERT_FRONT: |
e8064021 | 672 | rq->rq_flags |= RQF_SOFTBARRIER; |
8922e16c TH |
673 | list_add(&rq->queuelist, &q->queue_head); |
674 | break; | |
675 | ||
676 | case ELEVATOR_INSERT_BACK: | |
e8064021 | 677 | rq->rq_flags |= RQF_SOFTBARRIER; |
15853af9 | 678 | elv_drain_elevator(q); |
8922e16c TH |
679 | list_add_tail(&rq->queuelist, &q->queue_head); |
680 | /* | |
681 | * We kick the queue here for the following reasons. | |
682 | * - The elevator might have returned NULL previously | |
683 | * to delay requests and returned them now. As the | |
684 | * queue wasn't empty before this request, ll_rw_blk | |
685 | * won't run the queue on return, resulting in hang. | |
686 | * - Usually, back inserted requests won't be merged | |
687 | * with anything. There's no point in delaying queue | |
688 | * processing. | |
689 | */ | |
24ecfbe2 | 690 | __blk_run_queue(q); |
8922e16c TH |
691 | break; |
692 | ||
5e84ea3a JA |
693 | case ELEVATOR_INSERT_SORT_MERGE: |
694 | /* | |
695 | * If we succeed in merging this request with one in the | |
696 | * queue already, we are done - rq has now been freed, | |
697 | * so no need to do anything further. | |
698 | */ | |
699 | if (elv_attempt_insert_merge(q, rq)) | |
700 | break; | |
e29387eb | 701 | /* fall through */ |
8922e16c | 702 | case ELEVATOR_INSERT_SORT: |
57292b58 | 703 | BUG_ON(blk_rq_is_passthrough(rq)); |
e8064021 | 704 | rq->rq_flags |= RQF_SORTED; |
15853af9 | 705 | q->nr_sorted++; |
9817064b JA |
706 | if (rq_mergeable(rq)) { |
707 | elv_rqhash_add(q, rq); | |
708 | if (!q->last_merge) | |
709 | q->last_merge = rq; | |
710 | } | |
711 | ||
ca23509f TH |
712 | /* |
713 | * Some ioscheds (cfq) run q->request_fn directly, so | |
714 | * rq cannot be accessed after calling | |
715 | * elevator_add_req_fn. | |
716 | */ | |
c51ca6cf | 717 | q->elevator->type->ops.sq.elevator_add_req_fn(q, rq); |
8922e16c TH |
718 | break; |
719 | ||
ae1b1539 | 720 | case ELEVATOR_INSERT_FLUSH: |
e8064021 | 721 | rq->rq_flags |= RQF_SOFTBARRIER; |
ae1b1539 TH |
722 | blk_insert_flush(rq); |
723 | break; | |
8922e16c TH |
724 | default: |
725 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 726 | __func__, where); |
8922e16c TH |
727 | BUG(); |
728 | } | |
1da177e4 | 729 | } |
2e662b65 JA |
730 | EXPORT_SYMBOL(__elv_add_request); |
731 | ||
7eaceacc | 732 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
733 | { |
734 | unsigned long flags; | |
735 | ||
736 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 737 | __elv_add_request(q, rq, where); |
1da177e4 LT |
738 | spin_unlock_irqrestore(q->queue_lock, flags); |
739 | } | |
2e662b65 JA |
740 | EXPORT_SYMBOL(elv_add_request); |
741 | ||
165125e1 | 742 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 743 | { |
b374d18a | 744 | struct elevator_queue *e = q->elevator; |
1da177e4 | 745 | |
bd166ef1 JA |
746 | if (e->uses_mq && e->type->ops.mq.next_request) |
747 | return e->type->ops.mq.next_request(q, rq); | |
748 | else if (!e->uses_mq && e->type->ops.sq.elevator_latter_req_fn) | |
c51ca6cf | 749 | return e->type->ops.sq.elevator_latter_req_fn(q, rq); |
bd166ef1 | 750 | |
1da177e4 LT |
751 | return NULL; |
752 | } | |
753 | ||
165125e1 | 754 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 755 | { |
b374d18a | 756 | struct elevator_queue *e = q->elevator; |
1da177e4 | 757 | |
bd166ef1 JA |
758 | if (e->uses_mq && e->type->ops.mq.former_request) |
759 | return e->type->ops.mq.former_request(q, rq); | |
760 | if (!e->uses_mq && e->type->ops.sq.elevator_former_req_fn) | |
c51ca6cf | 761 | return e->type->ops.sq.elevator_former_req_fn(q, rq); |
1da177e4 LT |
762 | return NULL; |
763 | } | |
764 | ||
852c788f TH |
765 | int elv_set_request(struct request_queue *q, struct request *rq, |
766 | struct bio *bio, gfp_t gfp_mask) | |
1da177e4 | 767 | { |
b374d18a | 768 | struct elevator_queue *e = q->elevator; |
1da177e4 | 769 | |
bd166ef1 JA |
770 | if (WARN_ON_ONCE(e->uses_mq)) |
771 | return 0; | |
772 | ||
c51ca6cf JA |
773 | if (e->type->ops.sq.elevator_set_req_fn) |
774 | return e->type->ops.sq.elevator_set_req_fn(q, rq, bio, gfp_mask); | |
1da177e4 LT |
775 | return 0; |
776 | } | |
777 | ||
165125e1 | 778 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 779 | { |
b374d18a | 780 | struct elevator_queue *e = q->elevator; |
1da177e4 | 781 | |
bd166ef1 JA |
782 | if (WARN_ON_ONCE(e->uses_mq)) |
783 | return; | |
784 | ||
c51ca6cf JA |
785 | if (e->type->ops.sq.elevator_put_req_fn) |
786 | e->type->ops.sq.elevator_put_req_fn(rq); | |
1da177e4 LT |
787 | } |
788 | ||
ef295ecf | 789 | int elv_may_queue(struct request_queue *q, unsigned int op) |
1da177e4 | 790 | { |
b374d18a | 791 | struct elevator_queue *e = q->elevator; |
1da177e4 | 792 | |
bd166ef1 JA |
793 | if (WARN_ON_ONCE(e->uses_mq)) |
794 | return 0; | |
795 | ||
c51ca6cf JA |
796 | if (e->type->ops.sq.elevator_may_queue_fn) |
797 | return e->type->ops.sq.elevator_may_queue_fn(q, op); | |
1da177e4 LT |
798 | |
799 | return ELV_MQUEUE_MAY; | |
800 | } | |
801 | ||
165125e1 | 802 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 803 | { |
b374d18a | 804 | struct elevator_queue *e = q->elevator; |
1da177e4 | 805 | |
bd166ef1 JA |
806 | if (WARN_ON_ONCE(e->uses_mq)) |
807 | return; | |
808 | ||
1da177e4 LT |
809 | /* |
810 | * request is released from the driver, io must be done | |
811 | */ | |
8922e16c | 812 | if (blk_account_rq(rq)) { |
0a7ae2ff | 813 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 814 | if ((rq->rq_flags & RQF_SORTED) && |
c51ca6cf JA |
815 | e->type->ops.sq.elevator_completed_req_fn) |
816 | e->type->ops.sq.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 817 | } |
1da177e4 LT |
818 | } |
819 | ||
3d1ab40f AV |
820 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
821 | ||
822 | static ssize_t | |
823 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 824 | { |
3d1ab40f | 825 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 826 | struct elevator_queue *e; |
3d1ab40f AV |
827 | ssize_t error; |
828 | ||
829 | if (!entry->show) | |
830 | return -EIO; | |
831 | ||
b374d18a | 832 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 833 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 834 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
835 | mutex_unlock(&e->sysfs_lock); |
836 | return error; | |
837 | } | |
1da177e4 | 838 | |
3d1ab40f AV |
839 | static ssize_t |
840 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
841 | const char *page, size_t length) | |
842 | { | |
3d1ab40f | 843 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 844 | struct elevator_queue *e; |
3d1ab40f | 845 | ssize_t error; |
1da177e4 | 846 | |
3d1ab40f AV |
847 | if (!entry->store) |
848 | return -EIO; | |
1da177e4 | 849 | |
b374d18a | 850 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 851 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 852 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
853 | mutex_unlock(&e->sysfs_lock); |
854 | return error; | |
855 | } | |
856 | ||
52cf25d0 | 857 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
858 | .show = elv_attr_show, |
859 | .store = elv_attr_store, | |
860 | }; | |
861 | ||
862 | static struct kobj_type elv_ktype = { | |
863 | .sysfs_ops = &elv_sysfs_ops, | |
864 | .release = elevator_release, | |
865 | }; | |
866 | ||
5a5bafdc | 867 | int elv_register_queue(struct request_queue *q) |
3d1ab40f | 868 | { |
5a5bafdc | 869 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
870 | int error; |
871 | ||
14a23498 BVA |
872 | lockdep_assert_held(&q->sysfs_lock); |
873 | ||
b2d6db58 | 874 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 875 | if (!error) { |
22f746e2 | 876 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 877 | if (attr) { |
e572ec7e AV |
878 | while (attr->attr.name) { |
879 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 880 | break; |
e572ec7e | 881 | attr++; |
3d1ab40f AV |
882 | } |
883 | } | |
884 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 885 | e->registered = 1; |
bd166ef1 | 886 | if (!e->uses_mq && e->type->ops.sq.elevator_registered_fn) |
c51ca6cf | 887 | e->type->ops.sq.elevator_registered_fn(q); |
3d1ab40f AV |
888 | } |
889 | return error; | |
1da177e4 | 890 | } |
bc1c1169 | 891 | |
1da177e4 LT |
892 | void elv_unregister_queue(struct request_queue *q) |
893 | { | |
14a23498 BVA |
894 | lockdep_assert_held(&q->sysfs_lock); |
895 | ||
f8fc877d TH |
896 | if (q) { |
897 | struct elevator_queue *e = q->elevator; | |
898 | ||
899 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
900 | kobject_del(&e->kobj); | |
901 | e->registered = 0; | |
8330cdb0 JK |
902 | /* Re-enable throttling in case elevator disabled it */ |
903 | wbt_enable_default(q); | |
f8fc877d | 904 | } |
1da177e4 LT |
905 | } |
906 | ||
e567bf71 | 907 | int elv_register(struct elevator_type *e) |
1da177e4 | 908 | { |
1ffb96c5 | 909 | char *def = ""; |
2a12dcd7 | 910 | |
3d3c2379 TH |
911 | /* create icq_cache if requested */ |
912 | if (e->icq_size) { | |
913 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || | |
914 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) | |
915 | return -EINVAL; | |
916 | ||
917 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), | |
918 | "%s_io_cq", e->elevator_name); | |
919 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, | |
920 | e->icq_align, 0, NULL); | |
921 | if (!e->icq_cache) | |
922 | return -ENOMEM; | |
923 | } | |
924 | ||
925 | /* register, don't allow duplicate names */ | |
2a12dcd7 | 926 | spin_lock(&elv_list_lock); |
2527d997 | 927 | if (elevator_find(e->elevator_name, e->uses_mq)) { |
3d3c2379 TH |
928 | spin_unlock(&elv_list_lock); |
929 | if (e->icq_cache) | |
930 | kmem_cache_destroy(e->icq_cache); | |
931 | return -EBUSY; | |
932 | } | |
1da177e4 | 933 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 934 | spin_unlock(&elv_list_lock); |
1da177e4 | 935 | |
3d3c2379 | 936 | /* print pretty message */ |
8ac0d9a8 | 937 | if (elevator_match(e, chosen_elevator) || |
5f003976 | 938 | (!*chosen_elevator && |
8ac0d9a8 | 939 | elevator_match(e, CONFIG_DEFAULT_IOSCHED))) |
1ffb96c5 TV |
940 | def = " (default)"; |
941 | ||
4eb166d9 JA |
942 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
943 | def); | |
3d3c2379 | 944 | return 0; |
1da177e4 LT |
945 | } |
946 | EXPORT_SYMBOL_GPL(elv_register); | |
947 | ||
948 | void elv_unregister(struct elevator_type *e) | |
949 | { | |
3d3c2379 | 950 | /* unregister */ |
2a12dcd7 | 951 | spin_lock(&elv_list_lock); |
1da177e4 | 952 | list_del_init(&e->list); |
2a12dcd7 | 953 | spin_unlock(&elv_list_lock); |
3d3c2379 TH |
954 | |
955 | /* | |
956 | * Destroy icq_cache if it exists. icq's are RCU managed. Make | |
957 | * sure all RCU operations are complete before proceeding. | |
958 | */ | |
959 | if (e->icq_cache) { | |
960 | rcu_barrier(); | |
961 | kmem_cache_destroy(e->icq_cache); | |
962 | e->icq_cache = NULL; | |
963 | } | |
1da177e4 LT |
964 | } |
965 | EXPORT_SYMBOL_GPL(elv_unregister); | |
966 | ||
54d5329d OS |
967 | static int elevator_switch_mq(struct request_queue *q, |
968 | struct elevator_type *new_e) | |
969 | { | |
970 | int ret; | |
971 | ||
14a23498 BVA |
972 | lockdep_assert_held(&q->sysfs_lock); |
973 | ||
54d5329d | 974 | blk_mq_freeze_queue(q); |
24f5a90f | 975 | blk_mq_quiesce_queue(q); |
54d5329d OS |
976 | |
977 | if (q->elevator) { | |
978 | if (q->elevator->registered) | |
979 | elv_unregister_queue(q); | |
980 | ioc_clear_queue(q); | |
981 | elevator_exit(q, q->elevator); | |
982 | } | |
983 | ||
984 | ret = blk_mq_init_sched(q, new_e); | |
985 | if (ret) | |
986 | goto out; | |
987 | ||
988 | if (new_e) { | |
989 | ret = elv_register_queue(q); | |
990 | if (ret) { | |
991 | elevator_exit(q, q->elevator); | |
992 | goto out; | |
993 | } | |
994 | } | |
995 | ||
996 | if (new_e) | |
997 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); | |
998 | else | |
999 | blk_add_trace_msg(q, "elv switch: none"); | |
1000 | ||
1001 | out: | |
24f5a90f | 1002 | blk_mq_unquiesce_queue(q); |
54d5329d | 1003 | blk_mq_unfreeze_queue(q); |
54d5329d | 1004 | return ret; |
54d5329d OS |
1005 | } |
1006 | ||
1da177e4 LT |
1007 | /* |
1008 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1009 | * we don't free the old io scheduler, before we have allocated what we | |
1010 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1011 | * one, if the new one fails init for some reason. |
1da177e4 | 1012 | */ |
165125e1 | 1013 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1014 | { |
5a5bafdc | 1015 | struct elevator_queue *old = q->elevator; |
bd166ef1 | 1016 | bool old_registered = false; |
e8989fae | 1017 | int err; |
1da177e4 | 1018 | |
14a23498 BVA |
1019 | lockdep_assert_held(&q->sysfs_lock); |
1020 | ||
54d5329d OS |
1021 | if (q->mq_ops) |
1022 | return elevator_switch_mq(q, new_e); | |
bd166ef1 | 1023 | |
5a5bafdc TH |
1024 | /* |
1025 | * Turn on BYPASS and drain all requests w/ elevator private data. | |
1026 | * Block layer doesn't call into a quiesced elevator - all requests | |
1027 | * are directly put on the dispatch list without elevator data | |
1028 | * using INSERT_BACK. All requests have SOFTBARRIER set and no | |
1029 | * merge happens either. | |
1030 | */ | |
bd166ef1 JA |
1031 | if (old) { |
1032 | old_registered = old->registered; | |
1033 | ||
54d5329d | 1034 | blk_queue_bypass_start(q); |
1da177e4 | 1035 | |
bd166ef1 JA |
1036 | /* unregister and clear all auxiliary data of the old elevator */ |
1037 | if (old_registered) | |
1038 | elv_unregister_queue(q); | |
1039 | ||
bd166ef1 | 1040 | ioc_clear_queue(q); |
bd166ef1 | 1041 | } |
f8fc877d | 1042 | |
5a5bafdc | 1043 | /* allocate, init and register new elevator */ |
54d5329d | 1044 | err = new_e->ops.sq.elevator_init_fn(q, new_e); |
6917ff0b OS |
1045 | if (err) |
1046 | goto fail_init; | |
5a5bafdc | 1047 | |
54d5329d OS |
1048 | err = elv_register_queue(q); |
1049 | if (err) | |
1050 | goto fail_register; | |
5a5bafdc TH |
1051 | |
1052 | /* done, kill the old one and finish */ | |
bd166ef1 | 1053 | if (old) { |
54d5329d OS |
1054 | elevator_exit(q, old); |
1055 | blk_queue_bypass_end(q); | |
bd166ef1 JA |
1056 | } |
1057 | ||
54d5329d | 1058 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52 | 1059 | |
5dd531a0 | 1060 | return 0; |
1da177e4 LT |
1061 | |
1062 | fail_register: | |
54d5329d | 1063 | elevator_exit(q, q->elevator); |
5a5bafdc TH |
1064 | fail_init: |
1065 | /* switch failed, restore and re-register old elevator */ | |
bd166ef1 JA |
1066 | if (old) { |
1067 | q->elevator = old; | |
1068 | elv_register_queue(q); | |
54d5329d | 1069 | blk_queue_bypass_end(q); |
bd166ef1 | 1070 | } |
75ad23bc | 1071 | |
5dd531a0 | 1072 | return err; |
1da177e4 LT |
1073 | } |
1074 | ||
5dd531a0 JA |
1075 | /* |
1076 | * Switch this queue to the given IO scheduler. | |
1077 | */ | |
7c8a3679 | 1078 | static int __elevator_change(struct request_queue *q, const char *name) |
1da177e4 LT |
1079 | { |
1080 | char elevator_name[ELV_NAME_MAX]; | |
1081 | struct elevator_type *e; | |
1082 | ||
e9a823fb DJ |
1083 | /* Make sure queue is not in the middle of being removed */ |
1084 | if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags)) | |
1085 | return -ENOENT; | |
1086 | ||
bd166ef1 JA |
1087 | /* |
1088 | * Special case for mq, turn off scheduling | |
1089 | */ | |
1090 | if (q->mq_ops && !strncmp(name, "none", 4)) | |
1091 | return elevator_switch(q, NULL); | |
cd43e26f | 1092 | |
ee2e992c | 1093 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
2527d997 | 1094 | e = elevator_get(q, strstrip(elevator_name), true); |
340ff321 | 1095 | if (!e) |
1da177e4 | 1096 | return -EINVAL; |
1da177e4 | 1097 | |
8ac0d9a8 | 1098 | if (q->elevator && elevator_match(q->elevator->type, elevator_name)) { |
2ca7d93b | 1099 | elevator_put(e); |
5dd531a0 | 1100 | return 0; |
2ca7d93b | 1101 | } |
1da177e4 | 1102 | |
5dd531a0 JA |
1103 | return elevator_switch(q, e); |
1104 | } | |
7c8a3679 | 1105 | |
3a5088c8 ML |
1106 | static inline bool elv_support_iosched(struct request_queue *q) |
1107 | { | |
1108 | if (q->mq_ops && q->tag_set && (q->tag_set->flags & | |
1109 | BLK_MQ_F_NO_SCHED)) | |
1110 | return false; | |
1111 | return true; | |
1112 | } | |
1113 | ||
5dd531a0 JA |
1114 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1115 | size_t count) | |
1116 | { | |
1117 | int ret; | |
1118 | ||
3a5088c8 | 1119 | if (!(q->mq_ops || q->request_fn) || !elv_support_iosched(q)) |
5dd531a0 JA |
1120 | return count; |
1121 | ||
7c8a3679 | 1122 | ret = __elevator_change(q, name); |
5dd531a0 JA |
1123 | if (!ret) |
1124 | return count; | |
1125 | ||
5dd531a0 | 1126 | return ret; |
1da177e4 LT |
1127 | } |
1128 | ||
165125e1 | 1129 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1130 | { |
b374d18a | 1131 | struct elevator_queue *e = q->elevator; |
bd166ef1 | 1132 | struct elevator_type *elv = NULL; |
70cee26e | 1133 | struct elevator_type *__e; |
8ac0d9a8 | 1134 | bool uses_mq = q->mq_ops != NULL; |
1da177e4 LT |
1135 | int len = 0; |
1136 | ||
5fdee212 | 1137 | if (!queue_is_rq_based(q)) |
cd43e26f MP |
1138 | return sprintf(name, "none\n"); |
1139 | ||
bd166ef1 JA |
1140 | if (!q->elevator) |
1141 | len += sprintf(name+len, "[none] "); | |
1142 | else | |
1143 | elv = e->type; | |
cd43e26f | 1144 | |
2a12dcd7 | 1145 | spin_lock(&elv_list_lock); |
70cee26e | 1146 | list_for_each_entry(__e, &elv_list, list) { |
8ac0d9a8 JA |
1147 | if (elv && elevator_match(elv, __e->elevator_name) && |
1148 | (__e->uses_mq == uses_mq)) { | |
1da177e4 | 1149 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
bd166ef1 JA |
1150 | continue; |
1151 | } | |
3a5088c8 | 1152 | if (__e->uses_mq && q->mq_ops && elv_support_iosched(q)) |
bd166ef1 JA |
1153 | len += sprintf(name+len, "%s ", __e->elevator_name); |
1154 | else if (!__e->uses_mq && !q->mq_ops) | |
1da177e4 LT |
1155 | len += sprintf(name+len, "%s ", __e->elevator_name); |
1156 | } | |
2a12dcd7 | 1157 | spin_unlock(&elv_list_lock); |
1da177e4 | 1158 | |
bd166ef1 JA |
1159 | if (q->mq_ops && q->elevator) |
1160 | len += sprintf(name+len, "none"); | |
1161 | ||
1da177e4 LT |
1162 | len += sprintf(len+name, "\n"); |
1163 | return len; | |
1164 | } | |
1165 | ||
165125e1 JA |
1166 | struct request *elv_rb_former_request(struct request_queue *q, |
1167 | struct request *rq) | |
2e662b65 JA |
1168 | { |
1169 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1170 | ||
1171 | if (rbprev) | |
1172 | return rb_entry_rq(rbprev); | |
1173 | ||
1174 | return NULL; | |
1175 | } | |
2e662b65 JA |
1176 | EXPORT_SYMBOL(elv_rb_former_request); |
1177 | ||
165125e1 JA |
1178 | struct request *elv_rb_latter_request(struct request_queue *q, |
1179 | struct request *rq) | |
2e662b65 JA |
1180 | { |
1181 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1182 | ||
1183 | if (rbnext) | |
1184 | return rb_entry_rq(rbnext); | |
1185 | ||
1186 | return NULL; | |
1187 | } | |
2e662b65 | 1188 | EXPORT_SYMBOL(elv_rb_latter_request); |