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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 JA |
42 | #include "blk.h" |
43 | ||
1da177e4 LT |
44 | static DEFINE_SPINLOCK(elv_list_lock); |
45 | static LIST_HEAD(elv_list); | |
46 | ||
9817064b JA |
47 | /* |
48 | * Merge hash stuff. | |
49 | */ | |
83096ebf | 50 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 51 | |
da775265 JA |
52 | /* |
53 | * Query io scheduler to see if the current process issuing bio may be | |
54 | * merged with rq. | |
55 | */ | |
72ef799b | 56 | static int elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio) |
da775265 | 57 | { |
165125e1 | 58 | struct request_queue *q = rq->q; |
b374d18a | 59 | struct elevator_queue *e = q->elevator; |
da775265 | 60 | |
72ef799b TE |
61 | if (e->type->ops.elevator_allow_bio_merge_fn) |
62 | return e->type->ops.elevator_allow_bio_merge_fn(q, rq, bio); | |
da775265 JA |
63 | |
64 | return 1; | |
65 | } | |
66 | ||
1da177e4 LT |
67 | /* |
68 | * can we safely merge with this request? | |
69 | */ | |
72ef799b | 70 | bool elv_bio_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 | 71 | { |
050c8ea8 | 72 | if (!blk_rq_merge_ok(rq, bio)) |
72ef799b | 73 | return false; |
7ba1ba12 | 74 | |
72ef799b TE |
75 | if (!elv_iosched_allow_bio_merge(rq, bio)) |
76 | return false; | |
1da177e4 | 77 | |
72ef799b | 78 | return true; |
1da177e4 | 79 | } |
72ef799b | 80 | EXPORT_SYMBOL(elv_bio_merge_ok); |
1da177e4 | 81 | |
1da177e4 LT |
82 | static struct elevator_type *elevator_find(const char *name) |
83 | { | |
a22b169d | 84 | struct elevator_type *e; |
1da177e4 | 85 | |
70cee26e | 86 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
87 | if (!strcmp(e->elevator_name, name)) |
88 | return e; | |
1da177e4 | 89 | } |
1da177e4 | 90 | |
a22b169d | 91 | return NULL; |
1da177e4 LT |
92 | } |
93 | ||
94 | static void elevator_put(struct elevator_type *e) | |
95 | { | |
96 | module_put(e->elevator_owner); | |
97 | } | |
98 | ||
21c3c5d2 | 99 | static struct elevator_type *elevator_get(const char *name, bool try_loading) |
1da177e4 | 100 | { |
2824bc93 | 101 | struct elevator_type *e; |
1da177e4 | 102 | |
2a12dcd7 | 103 | spin_lock(&elv_list_lock); |
2824bc93 TH |
104 | |
105 | e = elevator_find(name); | |
21c3c5d2 | 106 | if (!e && try_loading) { |
e1640949 | 107 | spin_unlock(&elv_list_lock); |
490b94be | 108 | request_module("%s-iosched", name); |
e1640949 JA |
109 | spin_lock(&elv_list_lock); |
110 | e = elevator_find(name); | |
111 | } | |
112 | ||
2824bc93 TH |
113 | if (e && !try_module_get(e->elevator_owner)) |
114 | e = NULL; | |
115 | ||
2a12dcd7 | 116 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
117 | |
118 | return e; | |
119 | } | |
120 | ||
484fc254 | 121 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 122 | |
5f003976 | 123 | static int __init elevator_setup(char *str) |
1da177e4 | 124 | { |
752a3b79 CE |
125 | /* |
126 | * Be backwards-compatible with previous kernels, so users | |
127 | * won't get the wrong elevator. | |
128 | */ | |
492af635 | 129 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 130 | return 1; |
1da177e4 LT |
131 | } |
132 | ||
133 | __setup("elevator=", elevator_setup); | |
134 | ||
bb813f4c TH |
135 | /* called during boot to load the elevator chosen by the elevator param */ |
136 | void __init load_default_elevator_module(void) | |
137 | { | |
138 | struct elevator_type *e; | |
139 | ||
140 | if (!chosen_elevator[0]) | |
141 | return; | |
142 | ||
143 | spin_lock(&elv_list_lock); | |
144 | e = elevator_find(chosen_elevator); | |
145 | spin_unlock(&elv_list_lock); | |
146 | ||
147 | if (!e) | |
148 | request_module("%s-iosched", chosen_elevator); | |
149 | } | |
150 | ||
3d1ab40f AV |
151 | static struct kobj_type elv_ktype; |
152 | ||
d50235b7 | 153 | struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 154 | struct elevator_type *e) |
3d1ab40f | 155 | { |
b374d18a | 156 | struct elevator_queue *eq; |
9817064b | 157 | |
c1b511eb | 158 | eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node); |
9817064b | 159 | if (unlikely(!eq)) |
8406a4d5 | 160 | return NULL; |
9817064b | 161 | |
22f746e2 | 162 | eq->type = e; |
f9cb074b | 163 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b | 164 | mutex_init(&eq->sysfs_lock); |
242d98f0 | 165 | hash_init(eq->hash); |
9817064b | 166 | |
3d1ab40f AV |
167 | return eq; |
168 | } | |
d50235b7 | 169 | EXPORT_SYMBOL(elevator_alloc); |
3d1ab40f AV |
170 | |
171 | static void elevator_release(struct kobject *kobj) | |
172 | { | |
b374d18a | 173 | struct elevator_queue *e; |
9817064b | 174 | |
b374d18a | 175 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 176 | elevator_put(e->type); |
3d1ab40f AV |
177 | kfree(e); |
178 | } | |
179 | ||
165125e1 | 180 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
181 | { |
182 | struct elevator_type *e = NULL; | |
f8fc877d | 183 | int err; |
1da177e4 | 184 | |
eb1c160b TS |
185 | /* |
186 | * q->sysfs_lock must be held to provide mutual exclusion between | |
187 | * elevator_switch() and here. | |
188 | */ | |
189 | lockdep_assert_held(&q->sysfs_lock); | |
190 | ||
1abec4fd MS |
191 | if (unlikely(q->elevator)) |
192 | return 0; | |
193 | ||
cb98fc8b TH |
194 | INIT_LIST_HEAD(&q->queue_head); |
195 | q->last_merge = NULL; | |
196 | q->end_sector = 0; | |
197 | q->boundary_rq = NULL; | |
cb98fc8b | 198 | |
4eb166d9 | 199 | if (name) { |
21c3c5d2 | 200 | e = elevator_get(name, true); |
4eb166d9 JA |
201 | if (!e) |
202 | return -EINVAL; | |
203 | } | |
1da177e4 | 204 | |
21c3c5d2 TH |
205 | /* |
206 | * Use the default elevator specified by config boot param or | |
207 | * config option. Don't try to load modules as we could be running | |
208 | * off async and request_module() isn't allowed from async. | |
209 | */ | |
4eb166d9 | 210 | if (!e && *chosen_elevator) { |
21c3c5d2 | 211 | e = elevator_get(chosen_elevator, false); |
4eb166d9 JA |
212 | if (!e) |
213 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
214 | chosen_elevator); | |
215 | } | |
248d5ca5 | 216 | |
4eb166d9 | 217 | if (!e) { |
21c3c5d2 | 218 | e = elevator_get(CONFIG_DEFAULT_IOSCHED, false); |
4eb166d9 JA |
219 | if (!e) { |
220 | printk(KERN_ERR | |
221 | "Default I/O scheduler not found. " \ | |
222 | "Using noop.\n"); | |
21c3c5d2 | 223 | e = elevator_get("noop", false); |
4eb166d9 | 224 | } |
5f003976 ND |
225 | } |
226 | ||
d50235b7 | 227 | err = e->ops.elevator_init_fn(q, e); |
d32f6b57 SM |
228 | if (err) |
229 | elevator_put(e); | |
230 | return err; | |
1da177e4 | 231 | } |
2e662b65 JA |
232 | EXPORT_SYMBOL(elevator_init); |
233 | ||
b374d18a | 234 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 235 | { |
3d1ab40f | 236 | mutex_lock(&e->sysfs_lock); |
22f746e2 TH |
237 | if (e->type->ops.elevator_exit_fn) |
238 | e->type->ops.elevator_exit_fn(e); | |
3d1ab40f | 239 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 240 | |
3d1ab40f | 241 | kobject_put(&e->kobj); |
1da177e4 | 242 | } |
2e662b65 JA |
243 | EXPORT_SYMBOL(elevator_exit); |
244 | ||
9817064b JA |
245 | static inline void __elv_rqhash_del(struct request *rq) |
246 | { | |
242d98f0 | 247 | hash_del(&rq->hash); |
e8064021 | 248 | rq->rq_flags &= ~RQF_HASHED; |
9817064b JA |
249 | } |
250 | ||
70b3ea05 | 251 | void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
252 | { |
253 | if (ELV_ON_HASH(rq)) | |
254 | __elv_rqhash_del(rq); | |
255 | } | |
256 | ||
70b3ea05 | 257 | void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 258 | { |
b374d18a | 259 | struct elevator_queue *e = q->elevator; |
9817064b JA |
260 | |
261 | BUG_ON(ELV_ON_HASH(rq)); | |
242d98f0 | 262 | hash_add(e->hash, &rq->hash, rq_hash_key(rq)); |
e8064021 | 263 | rq->rq_flags |= RQF_HASHED; |
9817064b JA |
264 | } |
265 | ||
70b3ea05 | 266 | void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
267 | { |
268 | __elv_rqhash_del(rq); | |
269 | elv_rqhash_add(q, rq); | |
270 | } | |
271 | ||
70b3ea05 | 272 | struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 273 | { |
b374d18a | 274 | struct elevator_queue *e = q->elevator; |
b67bfe0d | 275 | struct hlist_node *next; |
9817064b JA |
276 | struct request *rq; |
277 | ||
ee89f812 | 278 | hash_for_each_possible_safe(e->hash, rq, next, hash, offset) { |
9817064b JA |
279 | BUG_ON(!ELV_ON_HASH(rq)); |
280 | ||
281 | if (unlikely(!rq_mergeable(rq))) { | |
282 | __elv_rqhash_del(rq); | |
283 | continue; | |
284 | } | |
285 | ||
286 | if (rq_hash_key(rq) == offset) | |
287 | return rq; | |
288 | } | |
289 | ||
290 | return NULL; | |
291 | } | |
292 | ||
2e662b65 JA |
293 | /* |
294 | * RB-tree support functions for inserting/lookup/removal of requests | |
295 | * in a sorted RB tree. | |
296 | */ | |
796d5116 | 297 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
298 | { |
299 | struct rb_node **p = &root->rb_node; | |
300 | struct rb_node *parent = NULL; | |
301 | struct request *__rq; | |
302 | ||
303 | while (*p) { | |
304 | parent = *p; | |
305 | __rq = rb_entry(parent, struct request, rb_node); | |
306 | ||
83096ebf | 307 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 308 | p = &(*p)->rb_left; |
796d5116 | 309 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 310 | p = &(*p)->rb_right; |
2e662b65 JA |
311 | } |
312 | ||
313 | rb_link_node(&rq->rb_node, parent, p); | |
314 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 315 | } |
2e662b65 JA |
316 | EXPORT_SYMBOL(elv_rb_add); |
317 | ||
318 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
319 | { | |
320 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
321 | rb_erase(&rq->rb_node, root); | |
322 | RB_CLEAR_NODE(&rq->rb_node); | |
323 | } | |
2e662b65 JA |
324 | EXPORT_SYMBOL(elv_rb_del); |
325 | ||
326 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
327 | { | |
328 | struct rb_node *n = root->rb_node; | |
329 | struct request *rq; | |
330 | ||
331 | while (n) { | |
332 | rq = rb_entry(n, struct request, rb_node); | |
333 | ||
83096ebf | 334 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 335 | n = n->rb_left; |
83096ebf | 336 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
337 | n = n->rb_right; |
338 | else | |
339 | return rq; | |
340 | } | |
341 | ||
342 | return NULL; | |
343 | } | |
2e662b65 JA |
344 | EXPORT_SYMBOL(elv_rb_find); |
345 | ||
8922e16c TH |
346 | /* |
347 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 348 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 349 | * specific elevators. |
8922e16c | 350 | */ |
165125e1 | 351 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
352 | { |
353 | sector_t boundary; | |
8922e16c TH |
354 | struct list_head *entry; |
355 | ||
06b86245 TH |
356 | if (q->last_merge == rq) |
357 | q->last_merge = NULL; | |
9817064b JA |
358 | |
359 | elv_rqhash_del(q, rq); | |
360 | ||
15853af9 | 361 | q->nr_sorted--; |
06b86245 | 362 | |
1b47f531 | 363 | boundary = q->end_sector; |
8922e16c TH |
364 | list_for_each_prev(entry, &q->queue_head) { |
365 | struct request *pos = list_entry_rq(entry); | |
366 | ||
7afafc8a | 367 | if (req_op(rq) != req_op(pos)) |
e17fc0a1 | 368 | break; |
783660b2 JA |
369 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
370 | break; | |
e8064021 | 371 | if (pos->rq_flags & (RQF_STARTED | RQF_SOFTBARRIER)) |
8922e16c | 372 | break; |
83096ebf TH |
373 | if (blk_rq_pos(rq) >= boundary) { |
374 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
375 | continue; |
376 | } else { | |
83096ebf | 377 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
378 | break; |
379 | } | |
83096ebf | 380 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
381 | break; |
382 | } | |
383 | ||
384 | list_add(&rq->queuelist, entry); | |
385 | } | |
2e662b65 JA |
386 | EXPORT_SYMBOL(elv_dispatch_sort); |
387 | ||
9817064b | 388 | /* |
2e662b65 JA |
389 | * Insert rq into dispatch queue of q. Queue lock must be held on |
390 | * entry. rq is added to the back of the dispatch queue. To be used by | |
391 | * specific elevators. | |
9817064b JA |
392 | */ |
393 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
394 | { | |
395 | if (q->last_merge == rq) | |
396 | q->last_merge = NULL; | |
397 | ||
398 | elv_rqhash_del(q, rq); | |
399 | ||
400 | q->nr_sorted--; | |
401 | ||
402 | q->end_sector = rq_end_sector(rq); | |
403 | q->boundary_rq = rq; | |
404 | list_add_tail(&rq->queuelist, &q->queue_head); | |
405 | } | |
2e662b65 JA |
406 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
407 | ||
165125e1 | 408 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 409 | { |
b374d18a | 410 | struct elevator_queue *e = q->elevator; |
9817064b | 411 | struct request *__rq; |
06b86245 TH |
412 | int ret; |
413 | ||
488991e2 AB |
414 | /* |
415 | * Levels of merges: | |
416 | * nomerges: No merges at all attempted | |
417 | * noxmerges: Only simple one-hit cache try | |
418 | * merges: All merge tries attempted | |
419 | */ | |
7460d389 | 420 | if (blk_queue_nomerges(q) || !bio_mergeable(bio)) |
488991e2 AB |
421 | return ELEVATOR_NO_MERGE; |
422 | ||
9817064b JA |
423 | /* |
424 | * First try one-hit cache. | |
425 | */ | |
72ef799b | 426 | if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) { |
050c8ea8 | 427 | ret = blk_try_merge(q->last_merge, bio); |
06b86245 TH |
428 | if (ret != ELEVATOR_NO_MERGE) { |
429 | *req = q->last_merge; | |
430 | return ret; | |
431 | } | |
432 | } | |
1da177e4 | 433 | |
488991e2 | 434 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
435 | return ELEVATOR_NO_MERGE; |
436 | ||
9817064b JA |
437 | /* |
438 | * See if our hash lookup can find a potential backmerge. | |
439 | */ | |
4f024f37 | 440 | __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); |
72ef799b | 441 | if (__rq && elv_bio_merge_ok(__rq, bio)) { |
9817064b JA |
442 | *req = __rq; |
443 | return ELEVATOR_BACK_MERGE; | |
444 | } | |
445 | ||
22f746e2 TH |
446 | if (e->type->ops.elevator_merge_fn) |
447 | return e->type->ops.elevator_merge_fn(q, req, bio); | |
1da177e4 LT |
448 | |
449 | return ELEVATOR_NO_MERGE; | |
450 | } | |
451 | ||
5e84ea3a JA |
452 | /* |
453 | * Attempt to do an insertion back merge. Only check for the case where | |
454 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
455 | * afterwards. | |
456 | * | |
457 | * Returns true if we merged, false otherwise | |
458 | */ | |
459 | static bool elv_attempt_insert_merge(struct request_queue *q, | |
460 | struct request *rq) | |
461 | { | |
462 | struct request *__rq; | |
bee0393c | 463 | bool ret; |
5e84ea3a JA |
464 | |
465 | if (blk_queue_nomerges(q)) | |
466 | return false; | |
467 | ||
468 | /* | |
469 | * First try one-hit cache. | |
470 | */ | |
471 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
472 | return true; | |
473 | ||
474 | if (blk_queue_noxmerges(q)) | |
475 | return false; | |
476 | ||
bee0393c | 477 | ret = false; |
5e84ea3a JA |
478 | /* |
479 | * See if our hash lookup can find a potential backmerge. | |
480 | */ | |
bee0393c SL |
481 | while (1) { |
482 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
483 | if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) | |
484 | break; | |
485 | ||
486 | /* The merged request could be merged with others, try again */ | |
487 | ret = true; | |
488 | rq = __rq; | |
489 | } | |
27419322 | 490 | |
bee0393c | 491 | return ret; |
5e84ea3a JA |
492 | } |
493 | ||
165125e1 | 494 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 495 | { |
b374d18a | 496 | struct elevator_queue *e = q->elevator; |
1da177e4 | 497 | |
22f746e2 TH |
498 | if (e->type->ops.elevator_merged_fn) |
499 | e->type->ops.elevator_merged_fn(q, rq, type); | |
06b86245 | 500 | |
2e662b65 JA |
501 | if (type == ELEVATOR_BACK_MERGE) |
502 | elv_rqhash_reposition(q, rq); | |
9817064b | 503 | |
06b86245 | 504 | q->last_merge = rq; |
1da177e4 LT |
505 | } |
506 | ||
165125e1 | 507 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
508 | struct request *next) |
509 | { | |
b374d18a | 510 | struct elevator_queue *e = q->elevator; |
e8064021 | 511 | const int next_sorted = next->rq_flags & RQF_SORTED; |
1da177e4 | 512 | |
22f746e2 TH |
513 | if (next_sorted && e->type->ops.elevator_merge_req_fn) |
514 | e->type->ops.elevator_merge_req_fn(q, rq, next); | |
06b86245 | 515 | |
9817064b | 516 | elv_rqhash_reposition(q, rq); |
9817064b | 517 | |
5e84ea3a JA |
518 | if (next_sorted) { |
519 | elv_rqhash_del(q, next); | |
520 | q->nr_sorted--; | |
521 | } | |
522 | ||
06b86245 | 523 | q->last_merge = rq; |
1da177e4 LT |
524 | } |
525 | ||
812d4026 DS |
526 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
527 | struct bio *bio) | |
528 | { | |
529 | struct elevator_queue *e = q->elevator; | |
530 | ||
22f746e2 TH |
531 | if (e->type->ops.elevator_bio_merged_fn) |
532 | e->type->ops.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
533 | } |
534 | ||
47fafbc7 | 535 | #ifdef CONFIG_PM |
c8158819 LM |
536 | static void blk_pm_requeue_request(struct request *rq) |
537 | { | |
e8064021 | 538 | if (rq->q->dev && !(rq->rq_flags & RQF_PM)) |
c8158819 LM |
539 | rq->q->nr_pending--; |
540 | } | |
541 | ||
542 | static void blk_pm_add_request(struct request_queue *q, struct request *rq) | |
543 | { | |
e8064021 | 544 | if (q->dev && !(rq->rq_flags & RQF_PM) && q->nr_pending++ == 0 && |
c8158819 LM |
545 | (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING)) |
546 | pm_request_resume(q->dev); | |
547 | } | |
548 | #else | |
549 | static inline void blk_pm_requeue_request(struct request *rq) {} | |
550 | static inline void blk_pm_add_request(struct request_queue *q, | |
551 | struct request *rq) | |
552 | { | |
553 | } | |
554 | #endif | |
555 | ||
165125e1 | 556 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 557 | { |
1da177e4 LT |
558 | /* |
559 | * it already went through dequeue, we need to decrement the | |
560 | * in_flight count again | |
561 | */ | |
8922e16c | 562 | if (blk_account_rq(rq)) { |
0a7ae2ff | 563 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 564 | if (rq->rq_flags & RQF_SORTED) |
cad97516 | 565 | elv_deactivate_rq(q, rq); |
8922e16c | 566 | } |
1da177e4 | 567 | |
e8064021 | 568 | rq->rq_flags &= ~RQF_STARTED; |
1da177e4 | 569 | |
c8158819 LM |
570 | blk_pm_requeue_request(rq); |
571 | ||
b710a480 | 572 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
573 | } |
574 | ||
26308eab | 575 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
576 | { |
577 | static int printed; | |
e3c78ca5 TH |
578 | |
579 | lockdep_assert_held(q->queue_lock); | |
580 | ||
22f746e2 | 581 | while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
15853af9 | 582 | ; |
e3c78ca5 | 583 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
584 | printk(KERN_ERR "%s: forced dispatching is broken " |
585 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 586 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
587 | } |
588 | } | |
589 | ||
b710a480 | 590 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 591 | { |
5f3ea37c | 592 | trace_block_rq_insert(q, rq); |
2056a782 | 593 | |
c8158819 LM |
594 | blk_pm_add_request(q, rq); |
595 | ||
1da177e4 LT |
596 | rq->q = q; |
597 | ||
e8064021 | 598 | if (rq->rq_flags & RQF_SOFTBARRIER) { |
b710a480 | 599 | /* barriers are scheduling boundary, update end_sector */ |
e2a60da7 | 600 | if (rq->cmd_type == REQ_TYPE_FS) { |
b710a480 JA |
601 | q->end_sector = rq_end_sector(rq); |
602 | q->boundary_rq = rq; | |
603 | } | |
e8064021 | 604 | } else if (!(rq->rq_flags & RQF_ELVPRIV) && |
3aa72873 JA |
605 | (where == ELEVATOR_INSERT_SORT || |
606 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
607 | where = ELEVATOR_INSERT_BACK; |
608 | ||
8922e16c | 609 | switch (where) { |
28e7d184 | 610 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 611 | case ELEVATOR_INSERT_FRONT: |
e8064021 | 612 | rq->rq_flags |= RQF_SOFTBARRIER; |
8922e16c TH |
613 | list_add(&rq->queuelist, &q->queue_head); |
614 | break; | |
615 | ||
616 | case ELEVATOR_INSERT_BACK: | |
e8064021 | 617 | rq->rq_flags |= RQF_SOFTBARRIER; |
15853af9 | 618 | elv_drain_elevator(q); |
8922e16c TH |
619 | list_add_tail(&rq->queuelist, &q->queue_head); |
620 | /* | |
621 | * We kick the queue here for the following reasons. | |
622 | * - The elevator might have returned NULL previously | |
623 | * to delay requests and returned them now. As the | |
624 | * queue wasn't empty before this request, ll_rw_blk | |
625 | * won't run the queue on return, resulting in hang. | |
626 | * - Usually, back inserted requests won't be merged | |
627 | * with anything. There's no point in delaying queue | |
628 | * processing. | |
629 | */ | |
24ecfbe2 | 630 | __blk_run_queue(q); |
8922e16c TH |
631 | break; |
632 | ||
5e84ea3a JA |
633 | case ELEVATOR_INSERT_SORT_MERGE: |
634 | /* | |
635 | * If we succeed in merging this request with one in the | |
636 | * queue already, we are done - rq has now been freed, | |
637 | * so no need to do anything further. | |
638 | */ | |
639 | if (elv_attempt_insert_merge(q, rq)) | |
640 | break; | |
8922e16c | 641 | case ELEVATOR_INSERT_SORT: |
e2a60da7 | 642 | BUG_ON(rq->cmd_type != REQ_TYPE_FS); |
e8064021 | 643 | rq->rq_flags |= RQF_SORTED; |
15853af9 | 644 | q->nr_sorted++; |
9817064b JA |
645 | if (rq_mergeable(rq)) { |
646 | elv_rqhash_add(q, rq); | |
647 | if (!q->last_merge) | |
648 | q->last_merge = rq; | |
649 | } | |
650 | ||
ca23509f TH |
651 | /* |
652 | * Some ioscheds (cfq) run q->request_fn directly, so | |
653 | * rq cannot be accessed after calling | |
654 | * elevator_add_req_fn. | |
655 | */ | |
22f746e2 | 656 | q->elevator->type->ops.elevator_add_req_fn(q, rq); |
8922e16c TH |
657 | break; |
658 | ||
ae1b1539 | 659 | case ELEVATOR_INSERT_FLUSH: |
e8064021 | 660 | rq->rq_flags |= RQF_SOFTBARRIER; |
ae1b1539 TH |
661 | blk_insert_flush(rq); |
662 | break; | |
8922e16c TH |
663 | default: |
664 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 665 | __func__, where); |
8922e16c TH |
666 | BUG(); |
667 | } | |
1da177e4 | 668 | } |
2e662b65 JA |
669 | EXPORT_SYMBOL(__elv_add_request); |
670 | ||
7eaceacc | 671 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
672 | { |
673 | unsigned long flags; | |
674 | ||
675 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 676 | __elv_add_request(q, rq, where); |
1da177e4 LT |
677 | spin_unlock_irqrestore(q->queue_lock, flags); |
678 | } | |
2e662b65 JA |
679 | EXPORT_SYMBOL(elv_add_request); |
680 | ||
165125e1 | 681 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 682 | { |
b374d18a | 683 | struct elevator_queue *e = q->elevator; |
1da177e4 | 684 | |
22f746e2 TH |
685 | if (e->type->ops.elevator_latter_req_fn) |
686 | return e->type->ops.elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
687 | return NULL; |
688 | } | |
689 | ||
165125e1 | 690 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 691 | { |
b374d18a | 692 | struct elevator_queue *e = q->elevator; |
1da177e4 | 693 | |
22f746e2 TH |
694 | if (e->type->ops.elevator_former_req_fn) |
695 | return e->type->ops.elevator_former_req_fn(q, rq); | |
1da177e4 LT |
696 | return NULL; |
697 | } | |
698 | ||
852c788f TH |
699 | int elv_set_request(struct request_queue *q, struct request *rq, |
700 | struct bio *bio, gfp_t gfp_mask) | |
1da177e4 | 701 | { |
b374d18a | 702 | struct elevator_queue *e = q->elevator; |
1da177e4 | 703 | |
22f746e2 | 704 | if (e->type->ops.elevator_set_req_fn) |
852c788f | 705 | return e->type->ops.elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
706 | return 0; |
707 | } | |
708 | ||
165125e1 | 709 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 710 | { |
b374d18a | 711 | struct elevator_queue *e = q->elevator; |
1da177e4 | 712 | |
22f746e2 TH |
713 | if (e->type->ops.elevator_put_req_fn) |
714 | e->type->ops.elevator_put_req_fn(rq); | |
1da177e4 LT |
715 | } |
716 | ||
ef295ecf | 717 | int elv_may_queue(struct request_queue *q, unsigned int op) |
1da177e4 | 718 | { |
b374d18a | 719 | struct elevator_queue *e = q->elevator; |
1da177e4 | 720 | |
22f746e2 | 721 | if (e->type->ops.elevator_may_queue_fn) |
ef295ecf | 722 | return e->type->ops.elevator_may_queue_fn(q, op); |
1da177e4 LT |
723 | |
724 | return ELV_MQUEUE_MAY; | |
725 | } | |
726 | ||
165125e1 | 727 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 728 | { |
b374d18a | 729 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
730 | |
731 | /* | |
732 | * request is released from the driver, io must be done | |
733 | */ | |
8922e16c | 734 | if (blk_account_rq(rq)) { |
0a7ae2ff | 735 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 736 | if ((rq->rq_flags & RQF_SORTED) && |
22f746e2 TH |
737 | e->type->ops.elevator_completed_req_fn) |
738 | e->type->ops.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 739 | } |
1da177e4 LT |
740 | } |
741 | ||
3d1ab40f AV |
742 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
743 | ||
744 | static ssize_t | |
745 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 746 | { |
3d1ab40f | 747 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 748 | struct elevator_queue *e; |
3d1ab40f AV |
749 | ssize_t error; |
750 | ||
751 | if (!entry->show) | |
752 | return -EIO; | |
753 | ||
b374d18a | 754 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 755 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 756 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
757 | mutex_unlock(&e->sysfs_lock); |
758 | return error; | |
759 | } | |
1da177e4 | 760 | |
3d1ab40f AV |
761 | static ssize_t |
762 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
763 | const char *page, size_t length) | |
764 | { | |
3d1ab40f | 765 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 766 | struct elevator_queue *e; |
3d1ab40f | 767 | ssize_t error; |
1da177e4 | 768 | |
3d1ab40f AV |
769 | if (!entry->store) |
770 | return -EIO; | |
1da177e4 | 771 | |
b374d18a | 772 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 773 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 774 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
775 | mutex_unlock(&e->sysfs_lock); |
776 | return error; | |
777 | } | |
778 | ||
52cf25d0 | 779 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
780 | .show = elv_attr_show, |
781 | .store = elv_attr_store, | |
782 | }; | |
783 | ||
784 | static struct kobj_type elv_ktype = { | |
785 | .sysfs_ops = &elv_sysfs_ops, | |
786 | .release = elevator_release, | |
787 | }; | |
788 | ||
5a5bafdc | 789 | int elv_register_queue(struct request_queue *q) |
3d1ab40f | 790 | { |
5a5bafdc | 791 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
792 | int error; |
793 | ||
b2d6db58 | 794 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 795 | if (!error) { |
22f746e2 | 796 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 797 | if (attr) { |
e572ec7e AV |
798 | while (attr->attr.name) { |
799 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 800 | break; |
e572ec7e | 801 | attr++; |
3d1ab40f AV |
802 | } |
803 | } | |
804 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 805 | e->registered = 1; |
0bb97947 JA |
806 | if (e->type->ops.elevator_registered_fn) |
807 | e->type->ops.elevator_registered_fn(q); | |
3d1ab40f AV |
808 | } |
809 | return error; | |
1da177e4 | 810 | } |
f8fc877d | 811 | EXPORT_SYMBOL(elv_register_queue); |
bc1c1169 | 812 | |
1da177e4 LT |
813 | void elv_unregister_queue(struct request_queue *q) |
814 | { | |
f8fc877d TH |
815 | if (q) { |
816 | struct elevator_queue *e = q->elevator; | |
817 | ||
818 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
819 | kobject_del(&e->kobj); | |
820 | e->registered = 0; | |
821 | } | |
1da177e4 | 822 | } |
01effb0d | 823 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 824 | |
e567bf71 | 825 | int elv_register(struct elevator_type *e) |
1da177e4 | 826 | { |
1ffb96c5 | 827 | char *def = ""; |
2a12dcd7 | 828 | |
3d3c2379 TH |
829 | /* create icq_cache if requested */ |
830 | if (e->icq_size) { | |
831 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || | |
832 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) | |
833 | return -EINVAL; | |
834 | ||
835 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), | |
836 | "%s_io_cq", e->elevator_name); | |
837 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, | |
838 | e->icq_align, 0, NULL); | |
839 | if (!e->icq_cache) | |
840 | return -ENOMEM; | |
841 | } | |
842 | ||
843 | /* register, don't allow duplicate names */ | |
2a12dcd7 | 844 | spin_lock(&elv_list_lock); |
3d3c2379 TH |
845 | if (elevator_find(e->elevator_name)) { |
846 | spin_unlock(&elv_list_lock); | |
847 | if (e->icq_cache) | |
848 | kmem_cache_destroy(e->icq_cache); | |
849 | return -EBUSY; | |
850 | } | |
1da177e4 | 851 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 852 | spin_unlock(&elv_list_lock); |
1da177e4 | 853 | |
3d3c2379 | 854 | /* print pretty message */ |
5f003976 ND |
855 | if (!strcmp(e->elevator_name, chosen_elevator) || |
856 | (!*chosen_elevator && | |
857 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
858 | def = " (default)"; |
859 | ||
4eb166d9 JA |
860 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
861 | def); | |
3d3c2379 | 862 | return 0; |
1da177e4 LT |
863 | } |
864 | EXPORT_SYMBOL_GPL(elv_register); | |
865 | ||
866 | void elv_unregister(struct elevator_type *e) | |
867 | { | |
3d3c2379 | 868 | /* unregister */ |
2a12dcd7 | 869 | spin_lock(&elv_list_lock); |
1da177e4 | 870 | list_del_init(&e->list); |
2a12dcd7 | 871 | spin_unlock(&elv_list_lock); |
3d3c2379 TH |
872 | |
873 | /* | |
874 | * Destroy icq_cache if it exists. icq's are RCU managed. Make | |
875 | * sure all RCU operations are complete before proceeding. | |
876 | */ | |
877 | if (e->icq_cache) { | |
878 | rcu_barrier(); | |
879 | kmem_cache_destroy(e->icq_cache); | |
880 | e->icq_cache = NULL; | |
881 | } | |
1da177e4 LT |
882 | } |
883 | EXPORT_SYMBOL_GPL(elv_unregister); | |
884 | ||
885 | /* | |
886 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
887 | * we don't free the old io scheduler, before we have allocated what we | |
888 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 889 | * one, if the new one fails init for some reason. |
1da177e4 | 890 | */ |
165125e1 | 891 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 892 | { |
5a5bafdc TH |
893 | struct elevator_queue *old = q->elevator; |
894 | bool registered = old->registered; | |
e8989fae | 895 | int err; |
1da177e4 | 896 | |
5a5bafdc TH |
897 | /* |
898 | * Turn on BYPASS and drain all requests w/ elevator private data. | |
899 | * Block layer doesn't call into a quiesced elevator - all requests | |
900 | * are directly put on the dispatch list without elevator data | |
901 | * using INSERT_BACK. All requests have SOFTBARRIER set and no | |
902 | * merge happens either. | |
903 | */ | |
d732580b | 904 | blk_queue_bypass_start(q); |
cb98fc8b | 905 | |
5a5bafdc TH |
906 | /* unregister and clear all auxiliary data of the old elevator */ |
907 | if (registered) | |
f8fc877d | 908 | elv_unregister_queue(q); |
1da177e4 | 909 | |
f8fc877d | 910 | spin_lock_irq(q->queue_lock); |
7e5a8794 | 911 | ioc_clear_queue(q); |
f8fc877d TH |
912 | spin_unlock_irq(q->queue_lock); |
913 | ||
5a5bafdc | 914 | /* allocate, init and register new elevator */ |
d50235b7 JM |
915 | err = new_e->ops.elevator_init_fn(q, new_e); |
916 | if (err) | |
5a5bafdc TH |
917 | goto fail_init; |
918 | ||
5a5bafdc TH |
919 | if (registered) { |
920 | err = elv_register_queue(q); | |
921 | if (err) | |
922 | goto fail_register; | |
923 | } | |
924 | ||
925 | /* done, kill the old one and finish */ | |
926 | elevator_exit(old); | |
d732580b | 927 | blk_queue_bypass_end(q); |
75ad23bc | 928 | |
5a5bafdc | 929 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52 | 930 | |
5dd531a0 | 931 | return 0; |
1da177e4 LT |
932 | |
933 | fail_register: | |
5a5bafdc TH |
934 | elevator_exit(q->elevator); |
935 | fail_init: | |
936 | /* switch failed, restore and re-register old elevator */ | |
937 | q->elevator = old; | |
1da177e4 | 938 | elv_register_queue(q); |
d732580b | 939 | blk_queue_bypass_end(q); |
75ad23bc | 940 | |
5dd531a0 | 941 | return err; |
1da177e4 LT |
942 | } |
943 | ||
5dd531a0 JA |
944 | /* |
945 | * Switch this queue to the given IO scheduler. | |
946 | */ | |
7c8a3679 | 947 | static int __elevator_change(struct request_queue *q, const char *name) |
1da177e4 LT |
948 | { |
949 | char elevator_name[ELV_NAME_MAX]; | |
950 | struct elevator_type *e; | |
951 | ||
cd43e26f | 952 | if (!q->elevator) |
5dd531a0 | 953 | return -ENXIO; |
cd43e26f | 954 | |
ee2e992c | 955 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
21c3c5d2 | 956 | e = elevator_get(strstrip(elevator_name), true); |
1da177e4 LT |
957 | if (!e) { |
958 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
959 | return -EINVAL; | |
960 | } | |
961 | ||
22f746e2 | 962 | if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
2ca7d93b | 963 | elevator_put(e); |
5dd531a0 | 964 | return 0; |
2ca7d93b | 965 | } |
1da177e4 | 966 | |
5dd531a0 JA |
967 | return elevator_switch(q, e); |
968 | } | |
7c8a3679 TS |
969 | |
970 | int elevator_change(struct request_queue *q, const char *name) | |
971 | { | |
972 | int ret; | |
973 | ||
974 | /* Protect q->elevator from elevator_init() */ | |
975 | mutex_lock(&q->sysfs_lock); | |
976 | ret = __elevator_change(q, name); | |
977 | mutex_unlock(&q->sysfs_lock); | |
978 | ||
979 | return ret; | |
980 | } | |
5dd531a0 JA |
981 | EXPORT_SYMBOL(elevator_change); |
982 | ||
983 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
984 | size_t count) | |
985 | { | |
986 | int ret; | |
987 | ||
988 | if (!q->elevator) | |
989 | return count; | |
990 | ||
7c8a3679 | 991 | ret = __elevator_change(q, name); |
5dd531a0 JA |
992 | if (!ret) |
993 | return count; | |
994 | ||
995 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
996 | return ret; | |
1da177e4 LT |
997 | } |
998 | ||
165125e1 | 999 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1000 | { |
b374d18a | 1001 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1002 | struct elevator_type *elv; |
70cee26e | 1003 | struct elevator_type *__e; |
1da177e4 LT |
1004 | int len = 0; |
1005 | ||
e36f724b | 1006 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1007 | return sprintf(name, "none\n"); |
1008 | ||
22f746e2 | 1009 | elv = e->type; |
cd43e26f | 1010 | |
2a12dcd7 | 1011 | spin_lock(&elv_list_lock); |
70cee26e | 1012 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1013 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1014 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1015 | else | |
1016 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1017 | } | |
2a12dcd7 | 1018 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1019 | |
1020 | len += sprintf(len+name, "\n"); | |
1021 | return len; | |
1022 | } | |
1023 | ||
165125e1 JA |
1024 | struct request *elv_rb_former_request(struct request_queue *q, |
1025 | struct request *rq) | |
2e662b65 JA |
1026 | { |
1027 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1028 | ||
1029 | if (rbprev) | |
1030 | return rb_entry_rq(rbprev); | |
1031 | ||
1032 | return NULL; | |
1033 | } | |
2e662b65 JA |
1034 | EXPORT_SYMBOL(elv_rb_former_request); |
1035 | ||
165125e1 JA |
1036 | struct request *elv_rb_latter_request(struct request_queue *q, |
1037 | struct request *rq) | |
2e662b65 JA |
1038 | { |
1039 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1040 | ||
1041 | if (rbnext) | |
1042 | return rb_entry_rq(rbnext); | |
1043 | ||
1044 | return NULL; | |
1045 | } | |
2e662b65 | 1046 | EXPORT_SYMBOL(elv_rb_latter_request); |