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Commit | Line | Data |
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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> |
1da177e4 | 37 | |
55782138 LZ |
38 | #include <trace/events/block.h> |
39 | ||
242f9dcb JA |
40 | #include "blk.h" |
41 | ||
1da177e4 LT |
42 | static DEFINE_SPINLOCK(elv_list_lock); |
43 | static LIST_HEAD(elv_list); | |
44 | ||
9817064b JA |
45 | /* |
46 | * Merge hash stuff. | |
47 | */ | |
48 | static const int elv_hash_shift = 6; | |
49 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
50 | #define ELV_HASH_FN(sec) \ |
51 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b | 52 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
83096ebf | 53 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 54 | |
da775265 JA |
55 | /* |
56 | * Query io scheduler to see if the current process issuing bio may be | |
57 | * merged with rq. | |
58 | */ | |
59 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
60 | { | |
165125e1 | 61 | struct request_queue *q = rq->q; |
b374d18a | 62 | struct elevator_queue *e = q->elevator; |
da775265 | 63 | |
22f746e2 TH |
64 | if (e->type->ops.elevator_allow_merge_fn) |
65 | return e->type->ops.elevator_allow_merge_fn(q, rq, bio); | |
da775265 JA |
66 | |
67 | return 1; | |
68 | } | |
69 | ||
1da177e4 LT |
70 | /* |
71 | * can we safely merge with this request? | |
72 | */ | |
050c8ea8 | 73 | bool elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 | 74 | { |
050c8ea8 | 75 | if (!blk_rq_merge_ok(rq, bio)) |
7ba1ba12 MP |
76 | return 0; |
77 | ||
da775265 JA |
78 | if (!elv_iosched_allow_merge(rq, bio)) |
79 | return 0; | |
1da177e4 | 80 | |
da775265 | 81 | return 1; |
1da177e4 LT |
82 | } |
83 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
84 | ||
1da177e4 LT |
85 | static struct elevator_type *elevator_find(const char *name) |
86 | { | |
a22b169d | 87 | struct elevator_type *e; |
1da177e4 | 88 | |
70cee26e | 89 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
90 | if (!strcmp(e->elevator_name, name)) |
91 | return e; | |
1da177e4 | 92 | } |
1da177e4 | 93 | |
a22b169d | 94 | return NULL; |
1da177e4 LT |
95 | } |
96 | ||
97 | static void elevator_put(struct elevator_type *e) | |
98 | { | |
99 | module_put(e->elevator_owner); | |
100 | } | |
101 | ||
102 | static struct elevator_type *elevator_get(const char *name) | |
103 | { | |
2824bc93 | 104 | struct elevator_type *e; |
1da177e4 | 105 | |
2a12dcd7 | 106 | spin_lock(&elv_list_lock); |
2824bc93 TH |
107 | |
108 | e = elevator_find(name); | |
e1640949 | 109 | if (!e) { |
e1640949 | 110 | spin_unlock(&elv_list_lock); |
490b94be | 111 | request_module("%s-iosched", name); |
e1640949 JA |
112 | spin_lock(&elv_list_lock); |
113 | e = elevator_find(name); | |
114 | } | |
115 | ||
2824bc93 TH |
116 | if (e && !try_module_get(e->elevator_owner)) |
117 | e = NULL; | |
118 | ||
2a12dcd7 | 119 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
120 | |
121 | return e; | |
122 | } | |
123 | ||
484fc254 | 124 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 125 | |
5f003976 | 126 | static int __init elevator_setup(char *str) |
1da177e4 | 127 | { |
752a3b79 CE |
128 | /* |
129 | * Be backwards-compatible with previous kernels, so users | |
130 | * won't get the wrong elevator. | |
131 | */ | |
492af635 | 132 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 133 | return 1; |
1da177e4 LT |
134 | } |
135 | ||
136 | __setup("elevator=", elevator_setup); | |
137 | ||
3d1ab40f AV |
138 | static struct kobj_type elv_ktype; |
139 | ||
b374d18a | 140 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 141 | struct elevator_type *e) |
3d1ab40f | 142 | { |
b374d18a | 143 | struct elevator_queue *eq; |
9817064b JA |
144 | int i; |
145 | ||
b374d18a | 146 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
147 | if (unlikely(!eq)) |
148 | goto err; | |
149 | ||
22f746e2 | 150 | eq->type = e; |
f9cb074b | 151 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
152 | mutex_init(&eq->sysfs_lock); |
153 | ||
b5deef90 JA |
154 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
155 | GFP_KERNEL, q->node); | |
9817064b JA |
156 | if (!eq->hash) |
157 | goto err; | |
158 | ||
159 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
160 | INIT_HLIST_HEAD(&eq->hash[i]); | |
161 | ||
3d1ab40f | 162 | return eq; |
9817064b JA |
163 | err: |
164 | kfree(eq); | |
165 | elevator_put(e); | |
166 | return NULL; | |
3d1ab40f AV |
167 | } |
168 | ||
169 | static void elevator_release(struct kobject *kobj) | |
170 | { | |
b374d18a | 171 | struct elevator_queue *e; |
9817064b | 172 | |
b374d18a | 173 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 174 | elevator_put(e->type); |
9817064b | 175 | kfree(e->hash); |
3d1ab40f AV |
176 | kfree(e); |
177 | } | |
178 | ||
165125e1 | 179 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
180 | { |
181 | struct elevator_type *e = NULL; | |
f8fc877d | 182 | int err; |
1da177e4 | 183 | |
1abec4fd MS |
184 | if (unlikely(q->elevator)) |
185 | return 0; | |
186 | ||
cb98fc8b TH |
187 | INIT_LIST_HEAD(&q->queue_head); |
188 | q->last_merge = NULL; | |
189 | q->end_sector = 0; | |
190 | q->boundary_rq = NULL; | |
cb98fc8b | 191 | |
4eb166d9 JA |
192 | if (name) { |
193 | e = elevator_get(name); | |
194 | if (!e) | |
195 | return -EINVAL; | |
196 | } | |
1da177e4 | 197 | |
4eb166d9 JA |
198 | if (!e && *chosen_elevator) { |
199 | e = elevator_get(chosen_elevator); | |
200 | if (!e) | |
201 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
202 | chosen_elevator); | |
203 | } | |
248d5ca5 | 204 | |
4eb166d9 JA |
205 | if (!e) { |
206 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
207 | if (!e) { | |
208 | printk(KERN_ERR | |
209 | "Default I/O scheduler not found. " \ | |
210 | "Using noop.\n"); | |
211 | e = elevator_get("noop"); | |
212 | } | |
5f003976 ND |
213 | } |
214 | ||
5a5bafdc TH |
215 | q->elevator = elevator_alloc(q, e); |
216 | if (!q->elevator) | |
1da177e4 | 217 | return -ENOMEM; |
1da177e4 | 218 | |
b2fab5ac | 219 | err = e->ops.elevator_init_fn(q); |
f8fc877d | 220 | if (err) { |
5a5bafdc | 221 | kobject_put(&q->elevator->kobj); |
f8fc877d | 222 | return err; |
bc1c1169 | 223 | } |
1da177e4 | 224 | |
1abec4fd | 225 | return 0; |
1da177e4 | 226 | } |
2e662b65 JA |
227 | EXPORT_SYMBOL(elevator_init); |
228 | ||
b374d18a | 229 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 230 | { |
3d1ab40f | 231 | mutex_lock(&e->sysfs_lock); |
22f746e2 TH |
232 | if (e->type->ops.elevator_exit_fn) |
233 | e->type->ops.elevator_exit_fn(e); | |
3d1ab40f | 234 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 235 | |
3d1ab40f | 236 | kobject_put(&e->kobj); |
1da177e4 | 237 | } |
2e662b65 JA |
238 | EXPORT_SYMBOL(elevator_exit); |
239 | ||
9817064b JA |
240 | static inline void __elv_rqhash_del(struct request *rq) |
241 | { | |
242 | hlist_del_init(&rq->hash); | |
243 | } | |
244 | ||
165125e1 | 245 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
246 | { |
247 | if (ELV_ON_HASH(rq)) | |
248 | __elv_rqhash_del(rq); | |
249 | } | |
250 | ||
165125e1 | 251 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 252 | { |
b374d18a | 253 | struct elevator_queue *e = q->elevator; |
9817064b JA |
254 | |
255 | BUG_ON(ELV_ON_HASH(rq)); | |
256 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
257 | } | |
258 | ||
165125e1 | 259 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
260 | { |
261 | __elv_rqhash_del(rq); | |
262 | elv_rqhash_add(q, rq); | |
263 | } | |
264 | ||
165125e1 | 265 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 266 | { |
b374d18a | 267 | struct elevator_queue *e = q->elevator; |
9817064b JA |
268 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
269 | struct hlist_node *entry, *next; | |
270 | struct request *rq; | |
271 | ||
272 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
273 | BUG_ON(!ELV_ON_HASH(rq)); | |
274 | ||
275 | if (unlikely(!rq_mergeable(rq))) { | |
276 | __elv_rqhash_del(rq); | |
277 | continue; | |
278 | } | |
279 | ||
280 | if (rq_hash_key(rq) == offset) | |
281 | return rq; | |
282 | } | |
283 | ||
284 | return NULL; | |
285 | } | |
286 | ||
2e662b65 JA |
287 | /* |
288 | * RB-tree support functions for inserting/lookup/removal of requests | |
289 | * in a sorted RB tree. | |
290 | */ | |
796d5116 | 291 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
292 | { |
293 | struct rb_node **p = &root->rb_node; | |
294 | struct rb_node *parent = NULL; | |
295 | struct request *__rq; | |
296 | ||
297 | while (*p) { | |
298 | parent = *p; | |
299 | __rq = rb_entry(parent, struct request, rb_node); | |
300 | ||
83096ebf | 301 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 302 | p = &(*p)->rb_left; |
796d5116 | 303 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 304 | p = &(*p)->rb_right; |
2e662b65 JA |
305 | } |
306 | ||
307 | rb_link_node(&rq->rb_node, parent, p); | |
308 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 309 | } |
2e662b65 JA |
310 | EXPORT_SYMBOL(elv_rb_add); |
311 | ||
312 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
313 | { | |
314 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
315 | rb_erase(&rq->rb_node, root); | |
316 | RB_CLEAR_NODE(&rq->rb_node); | |
317 | } | |
2e662b65 JA |
318 | EXPORT_SYMBOL(elv_rb_del); |
319 | ||
320 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
321 | { | |
322 | struct rb_node *n = root->rb_node; | |
323 | struct request *rq; | |
324 | ||
325 | while (n) { | |
326 | rq = rb_entry(n, struct request, rb_node); | |
327 | ||
83096ebf | 328 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 329 | n = n->rb_left; |
83096ebf | 330 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
331 | n = n->rb_right; |
332 | else | |
333 | return rq; | |
334 | } | |
335 | ||
336 | return NULL; | |
337 | } | |
2e662b65 JA |
338 | EXPORT_SYMBOL(elv_rb_find); |
339 | ||
8922e16c TH |
340 | /* |
341 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 342 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 343 | * specific elevators. |
8922e16c | 344 | */ |
165125e1 | 345 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
346 | { |
347 | sector_t boundary; | |
8922e16c | 348 | struct list_head *entry; |
4eb166d9 | 349 | int stop_flags; |
8922e16c | 350 | |
06b86245 TH |
351 | if (q->last_merge == rq) |
352 | q->last_merge = NULL; | |
9817064b JA |
353 | |
354 | elv_rqhash_del(q, rq); | |
355 | ||
15853af9 | 356 | q->nr_sorted--; |
06b86245 | 357 | |
1b47f531 | 358 | boundary = q->end_sector; |
02e031cb | 359 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
8922e16c TH |
360 | list_for_each_prev(entry, &q->queue_head) { |
361 | struct request *pos = list_entry_rq(entry); | |
362 | ||
33659ebb CH |
363 | if ((rq->cmd_flags & REQ_DISCARD) != |
364 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 365 | break; |
783660b2 JA |
366 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
367 | break; | |
4eb166d9 | 368 | if (pos->cmd_flags & stop_flags) |
8922e16c | 369 | break; |
83096ebf TH |
370 | if (blk_rq_pos(rq) >= boundary) { |
371 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
372 | continue; |
373 | } else { | |
83096ebf | 374 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
375 | break; |
376 | } | |
83096ebf | 377 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
378 | break; |
379 | } | |
380 | ||
381 | list_add(&rq->queuelist, entry); | |
382 | } | |
2e662b65 JA |
383 | EXPORT_SYMBOL(elv_dispatch_sort); |
384 | ||
9817064b | 385 | /* |
2e662b65 JA |
386 | * Insert rq into dispatch queue of q. Queue lock must be held on |
387 | * entry. rq is added to the back of the dispatch queue. To be used by | |
388 | * specific elevators. | |
9817064b JA |
389 | */ |
390 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
391 | { | |
392 | if (q->last_merge == rq) | |
393 | q->last_merge = NULL; | |
394 | ||
395 | elv_rqhash_del(q, rq); | |
396 | ||
397 | q->nr_sorted--; | |
398 | ||
399 | q->end_sector = rq_end_sector(rq); | |
400 | q->boundary_rq = rq; | |
401 | list_add_tail(&rq->queuelist, &q->queue_head); | |
402 | } | |
2e662b65 JA |
403 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
404 | ||
165125e1 | 405 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 406 | { |
b374d18a | 407 | struct elevator_queue *e = q->elevator; |
9817064b | 408 | struct request *__rq; |
06b86245 TH |
409 | int ret; |
410 | ||
488991e2 AB |
411 | /* |
412 | * Levels of merges: | |
413 | * nomerges: No merges at all attempted | |
414 | * noxmerges: Only simple one-hit cache try | |
415 | * merges: All merge tries attempted | |
416 | */ | |
417 | if (blk_queue_nomerges(q)) | |
418 | return ELEVATOR_NO_MERGE; | |
419 | ||
9817064b JA |
420 | /* |
421 | * First try one-hit cache. | |
422 | */ | |
050c8ea8 TH |
423 | if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { |
424 | ret = blk_try_merge(q->last_merge, bio); | |
06b86245 TH |
425 | if (ret != ELEVATOR_NO_MERGE) { |
426 | *req = q->last_merge; | |
427 | return ret; | |
428 | } | |
429 | } | |
1da177e4 | 430 | |
488991e2 | 431 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
432 | return ELEVATOR_NO_MERGE; |
433 | ||
9817064b JA |
434 | /* |
435 | * See if our hash lookup can find a potential backmerge. | |
436 | */ | |
437 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
438 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
439 | *req = __rq; | |
440 | return ELEVATOR_BACK_MERGE; | |
441 | } | |
442 | ||
22f746e2 TH |
443 | if (e->type->ops.elevator_merge_fn) |
444 | return e->type->ops.elevator_merge_fn(q, req, bio); | |
1da177e4 LT |
445 | |
446 | return ELEVATOR_NO_MERGE; | |
447 | } | |
448 | ||
5e84ea3a JA |
449 | /* |
450 | * Attempt to do an insertion back merge. Only check for the case where | |
451 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
452 | * afterwards. | |
453 | * | |
454 | * Returns true if we merged, false otherwise | |
455 | */ | |
456 | static bool elv_attempt_insert_merge(struct request_queue *q, | |
457 | struct request *rq) | |
458 | { | |
459 | struct request *__rq; | |
460 | ||
461 | if (blk_queue_nomerges(q)) | |
462 | return false; | |
463 | ||
464 | /* | |
465 | * First try one-hit cache. | |
466 | */ | |
467 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
468 | return true; | |
469 | ||
470 | if (blk_queue_noxmerges(q)) | |
471 | return false; | |
472 | ||
473 | /* | |
474 | * See if our hash lookup can find a potential backmerge. | |
475 | */ | |
5d381efb JA |
476 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); |
477 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) | |
478 | return true; | |
27419322 | 479 | |
5d381efb | 480 | return false; |
5e84ea3a JA |
481 | } |
482 | ||
165125e1 | 483 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 484 | { |
b374d18a | 485 | struct elevator_queue *e = q->elevator; |
1da177e4 | 486 | |
22f746e2 TH |
487 | if (e->type->ops.elevator_merged_fn) |
488 | e->type->ops.elevator_merged_fn(q, rq, type); | |
06b86245 | 489 | |
2e662b65 JA |
490 | if (type == ELEVATOR_BACK_MERGE) |
491 | elv_rqhash_reposition(q, rq); | |
9817064b | 492 | |
06b86245 | 493 | q->last_merge = rq; |
1da177e4 LT |
494 | } |
495 | ||
165125e1 | 496 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
497 | struct request *next) |
498 | { | |
b374d18a | 499 | struct elevator_queue *e = q->elevator; |
5e84ea3a | 500 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
1da177e4 | 501 | |
22f746e2 TH |
502 | if (next_sorted && e->type->ops.elevator_merge_req_fn) |
503 | e->type->ops.elevator_merge_req_fn(q, rq, next); | |
06b86245 | 504 | |
9817064b | 505 | elv_rqhash_reposition(q, rq); |
9817064b | 506 | |
5e84ea3a JA |
507 | if (next_sorted) { |
508 | elv_rqhash_del(q, next); | |
509 | q->nr_sorted--; | |
510 | } | |
511 | ||
06b86245 | 512 | q->last_merge = rq; |
1da177e4 LT |
513 | } |
514 | ||
812d4026 DS |
515 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
516 | struct bio *bio) | |
517 | { | |
518 | struct elevator_queue *e = q->elevator; | |
519 | ||
22f746e2 TH |
520 | if (e->type->ops.elevator_bio_merged_fn) |
521 | e->type->ops.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
522 | } |
523 | ||
165125e1 | 524 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 525 | { |
1da177e4 LT |
526 | /* |
527 | * it already went through dequeue, we need to decrement the | |
528 | * in_flight count again | |
529 | */ | |
8922e16c | 530 | if (blk_account_rq(rq)) { |
0a7ae2ff | 531 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 532 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 533 | elv_deactivate_rq(q, rq); |
8922e16c | 534 | } |
1da177e4 | 535 | |
4aff5e23 | 536 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 537 | |
b710a480 | 538 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
539 | } |
540 | ||
26308eab | 541 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
542 | { |
543 | static int printed; | |
e3c78ca5 TH |
544 | |
545 | lockdep_assert_held(q->queue_lock); | |
546 | ||
22f746e2 | 547 | while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
15853af9 | 548 | ; |
e3c78ca5 | 549 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
550 | printk(KERN_ERR "%s: forced dispatching is broken " |
551 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 552 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
553 | } |
554 | } | |
555 | ||
f600abe2 | 556 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 557 | { |
cd43e26f MP |
558 | if (!q->elevator) |
559 | return; | |
560 | ||
e3c78ca5 | 561 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 562 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 563 | spin_unlock_irq(q->queue_lock); |
6c7e8cee | 564 | |
c9a929dd | 565 | blk_drain_queue(q, false); |
6c7e8cee JA |
566 | } |
567 | ||
f600abe2 | 568 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee | 569 | { |
e3c78ca5 | 570 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 571 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 572 | spin_unlock_irq(q->queue_lock); |
6c7e8cee JA |
573 | } |
574 | ||
b710a480 | 575 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 576 | { |
5f3ea37c | 577 | trace_block_rq_insert(q, rq); |
2056a782 | 578 | |
1da177e4 LT |
579 | rq->q = q; |
580 | ||
b710a480 JA |
581 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
582 | /* barriers are scheduling boundary, update end_sector */ | |
583 | if (rq->cmd_type == REQ_TYPE_FS || | |
584 | (rq->cmd_flags & REQ_DISCARD)) { | |
585 | q->end_sector = rq_end_sector(rq); | |
586 | q->boundary_rq = rq; | |
587 | } | |
588 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && | |
3aa72873 JA |
589 | (where == ELEVATOR_INSERT_SORT || |
590 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
591 | where = ELEVATOR_INSERT_BACK; |
592 | ||
8922e16c | 593 | switch (where) { |
28e7d184 | 594 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 595 | case ELEVATOR_INSERT_FRONT: |
4aff5e23 | 596 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
597 | list_add(&rq->queuelist, &q->queue_head); |
598 | break; | |
599 | ||
600 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 601 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 602 | elv_drain_elevator(q); |
8922e16c TH |
603 | list_add_tail(&rq->queuelist, &q->queue_head); |
604 | /* | |
605 | * We kick the queue here for the following reasons. | |
606 | * - The elevator might have returned NULL previously | |
607 | * to delay requests and returned them now. As the | |
608 | * queue wasn't empty before this request, ll_rw_blk | |
609 | * won't run the queue on return, resulting in hang. | |
610 | * - Usually, back inserted requests won't be merged | |
611 | * with anything. There's no point in delaying queue | |
612 | * processing. | |
613 | */ | |
24ecfbe2 | 614 | __blk_run_queue(q); |
8922e16c TH |
615 | break; |
616 | ||
5e84ea3a JA |
617 | case ELEVATOR_INSERT_SORT_MERGE: |
618 | /* | |
619 | * If we succeed in merging this request with one in the | |
620 | * queue already, we are done - rq has now been freed, | |
621 | * so no need to do anything further. | |
622 | */ | |
623 | if (elv_attempt_insert_merge(q, rq)) | |
624 | break; | |
8922e16c | 625 | case ELEVATOR_INSERT_SORT: |
33659ebb CH |
626 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
627 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 628 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 629 | q->nr_sorted++; |
9817064b JA |
630 | if (rq_mergeable(rq)) { |
631 | elv_rqhash_add(q, rq); | |
632 | if (!q->last_merge) | |
633 | q->last_merge = rq; | |
634 | } | |
635 | ||
ca23509f TH |
636 | /* |
637 | * Some ioscheds (cfq) run q->request_fn directly, so | |
638 | * rq cannot be accessed after calling | |
639 | * elevator_add_req_fn. | |
640 | */ | |
22f746e2 | 641 | q->elevator->type->ops.elevator_add_req_fn(q, rq); |
8922e16c TH |
642 | break; |
643 | ||
ae1b1539 TH |
644 | case ELEVATOR_INSERT_FLUSH: |
645 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
646 | blk_insert_flush(rq); | |
647 | break; | |
8922e16c TH |
648 | default: |
649 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 650 | __func__, where); |
8922e16c TH |
651 | BUG(); |
652 | } | |
1da177e4 | 653 | } |
2e662b65 JA |
654 | EXPORT_SYMBOL(__elv_add_request); |
655 | ||
7eaceacc | 656 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
657 | { |
658 | unsigned long flags; | |
659 | ||
660 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 661 | __elv_add_request(q, rq, where); |
1da177e4 LT |
662 | spin_unlock_irqrestore(q->queue_lock, flags); |
663 | } | |
2e662b65 JA |
664 | EXPORT_SYMBOL(elv_add_request); |
665 | ||
165125e1 | 666 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 667 | { |
b374d18a | 668 | struct elevator_queue *e = q->elevator; |
1da177e4 | 669 | |
22f746e2 TH |
670 | if (e->type->ops.elevator_latter_req_fn) |
671 | return e->type->ops.elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
672 | return NULL; |
673 | } | |
674 | ||
165125e1 | 675 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 676 | { |
b374d18a | 677 | struct elevator_queue *e = q->elevator; |
1da177e4 | 678 | |
22f746e2 TH |
679 | if (e->type->ops.elevator_former_req_fn) |
680 | return e->type->ops.elevator_former_req_fn(q, rq); | |
1da177e4 LT |
681 | return NULL; |
682 | } | |
683 | ||
165125e1 | 684 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 685 | { |
b374d18a | 686 | struct elevator_queue *e = q->elevator; |
1da177e4 | 687 | |
22f746e2 TH |
688 | if (e->type->ops.elevator_set_req_fn) |
689 | return e->type->ops.elevator_set_req_fn(q, rq, gfp_mask); | |
1da177e4 LT |
690 | return 0; |
691 | } | |
692 | ||
165125e1 | 693 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 694 | { |
b374d18a | 695 | struct elevator_queue *e = q->elevator; |
1da177e4 | 696 | |
22f746e2 TH |
697 | if (e->type->ops.elevator_put_req_fn) |
698 | e->type->ops.elevator_put_req_fn(rq); | |
1da177e4 LT |
699 | } |
700 | ||
165125e1 | 701 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 702 | { |
b374d18a | 703 | struct elevator_queue *e = q->elevator; |
1da177e4 | 704 | |
22f746e2 TH |
705 | if (e->type->ops.elevator_may_queue_fn) |
706 | return e->type->ops.elevator_may_queue_fn(q, rw); | |
1da177e4 LT |
707 | |
708 | return ELV_MQUEUE_MAY; | |
709 | } | |
710 | ||
11914a53 MA |
711 | void elv_abort_queue(struct request_queue *q) |
712 | { | |
713 | struct request *rq; | |
714 | ||
ae1b1539 TH |
715 | blk_abort_flushes(q); |
716 | ||
11914a53 MA |
717 | while (!list_empty(&q->queue_head)) { |
718 | rq = list_entry_rq(q->queue_head.next); | |
719 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 720 | trace_block_rq_abort(q, rq); |
53c663ce KU |
721 | /* |
722 | * Mark this request as started so we don't trigger | |
723 | * any debug logic in the end I/O path. | |
724 | */ | |
725 | blk_start_request(rq); | |
40cbbb78 | 726 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
727 | } |
728 | } | |
729 | EXPORT_SYMBOL(elv_abort_queue); | |
730 | ||
165125e1 | 731 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 732 | { |
b374d18a | 733 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
734 | |
735 | /* | |
736 | * request is released from the driver, io must be done | |
737 | */ | |
8922e16c | 738 | if (blk_account_rq(rq)) { |
0a7ae2ff | 739 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 740 | if ((rq->cmd_flags & REQ_SORTED) && |
22f746e2 TH |
741 | e->type->ops.elevator_completed_req_fn) |
742 | e->type->ops.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 743 | } |
1da177e4 LT |
744 | } |
745 | ||
3d1ab40f AV |
746 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
747 | ||
748 | static ssize_t | |
749 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 750 | { |
3d1ab40f | 751 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 752 | struct elevator_queue *e; |
3d1ab40f AV |
753 | ssize_t error; |
754 | ||
755 | if (!entry->show) | |
756 | return -EIO; | |
757 | ||
b374d18a | 758 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 759 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 760 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
761 | mutex_unlock(&e->sysfs_lock); |
762 | return error; | |
763 | } | |
1da177e4 | 764 | |
3d1ab40f AV |
765 | static ssize_t |
766 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
767 | const char *page, size_t length) | |
768 | { | |
3d1ab40f | 769 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 770 | struct elevator_queue *e; |
3d1ab40f | 771 | ssize_t error; |
1da177e4 | 772 | |
3d1ab40f AV |
773 | if (!entry->store) |
774 | return -EIO; | |
1da177e4 | 775 | |
b374d18a | 776 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 777 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 778 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
779 | mutex_unlock(&e->sysfs_lock); |
780 | return error; | |
781 | } | |
782 | ||
52cf25d0 | 783 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
784 | .show = elv_attr_show, |
785 | .store = elv_attr_store, | |
786 | }; | |
787 | ||
788 | static struct kobj_type elv_ktype = { | |
789 | .sysfs_ops = &elv_sysfs_ops, | |
790 | .release = elevator_release, | |
791 | }; | |
792 | ||
5a5bafdc | 793 | int elv_register_queue(struct request_queue *q) |
3d1ab40f | 794 | { |
5a5bafdc | 795 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
796 | int error; |
797 | ||
b2d6db58 | 798 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 799 | if (!error) { |
22f746e2 | 800 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 801 | if (attr) { |
e572ec7e AV |
802 | while (attr->attr.name) { |
803 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 804 | break; |
e572ec7e | 805 | attr++; |
3d1ab40f AV |
806 | } |
807 | } | |
808 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 809 | e->registered = 1; |
3d1ab40f AV |
810 | } |
811 | return error; | |
1da177e4 | 812 | } |
f8fc877d | 813 | EXPORT_SYMBOL(elv_register_queue); |
bc1c1169 | 814 | |
1da177e4 LT |
815 | void elv_unregister_queue(struct request_queue *q) |
816 | { | |
f8fc877d TH |
817 | if (q) { |
818 | struct elevator_queue *e = q->elevator; | |
819 | ||
820 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
821 | kobject_del(&e->kobj); | |
822 | e->registered = 0; | |
823 | } | |
1da177e4 | 824 | } |
01effb0d | 825 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 826 | |
3d3c2379 | 827 | int elv_register(struct elevator_type *e) |
1da177e4 | 828 | { |
1ffb96c5 | 829 | char *def = ""; |
2a12dcd7 | 830 | |
3d3c2379 TH |
831 | /* create icq_cache if requested */ |
832 | if (e->icq_size) { | |
833 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || | |
834 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) | |
835 | return -EINVAL; | |
836 | ||
837 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), | |
838 | "%s_io_cq", e->elevator_name); | |
839 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, | |
840 | e->icq_align, 0, NULL); | |
841 | if (!e->icq_cache) | |
842 | return -ENOMEM; | |
843 | } | |
844 | ||
845 | /* register, don't allow duplicate names */ | |
2a12dcd7 | 846 | spin_lock(&elv_list_lock); |
3d3c2379 TH |
847 | if (elevator_find(e->elevator_name)) { |
848 | spin_unlock(&elv_list_lock); | |
849 | if (e->icq_cache) | |
850 | kmem_cache_destroy(e->icq_cache); | |
851 | return -EBUSY; | |
852 | } | |
1da177e4 | 853 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 854 | spin_unlock(&elv_list_lock); |
1da177e4 | 855 | |
3d3c2379 | 856 | /* print pretty message */ |
5f003976 ND |
857 | if (!strcmp(e->elevator_name, chosen_elevator) || |
858 | (!*chosen_elevator && | |
859 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
860 | def = " (default)"; |
861 | ||
4eb166d9 JA |
862 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
863 | def); | |
3d3c2379 | 864 | return 0; |
1da177e4 LT |
865 | } |
866 | EXPORT_SYMBOL_GPL(elv_register); | |
867 | ||
868 | void elv_unregister(struct elevator_type *e) | |
869 | { | |
3d3c2379 | 870 | /* unregister */ |
2a12dcd7 | 871 | spin_lock(&elv_list_lock); |
1da177e4 | 872 | list_del_init(&e->list); |
2a12dcd7 | 873 | spin_unlock(&elv_list_lock); |
3d3c2379 TH |
874 | |
875 | /* | |
876 | * Destroy icq_cache if it exists. icq's are RCU managed. Make | |
877 | * sure all RCU operations are complete before proceeding. | |
878 | */ | |
879 | if (e->icq_cache) { | |
880 | rcu_barrier(); | |
881 | kmem_cache_destroy(e->icq_cache); | |
882 | e->icq_cache = NULL; | |
883 | } | |
1da177e4 LT |
884 | } |
885 | EXPORT_SYMBOL_GPL(elv_unregister); | |
886 | ||
887 | /* | |
888 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
889 | * we don't free the old io scheduler, before we have allocated what we | |
890 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 891 | * one, if the new one fails init for some reason. |
1da177e4 | 892 | */ |
165125e1 | 893 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 894 | { |
5a5bafdc TH |
895 | struct elevator_queue *old = q->elevator; |
896 | bool registered = old->registered; | |
5dd531a0 | 897 | int err; |
1da177e4 | 898 | |
5a5bafdc TH |
899 | /* |
900 | * Turn on BYPASS and drain all requests w/ elevator private data. | |
901 | * Block layer doesn't call into a quiesced elevator - all requests | |
902 | * are directly put on the dispatch list without elevator data | |
903 | * using INSERT_BACK. All requests have SOFTBARRIER set and no | |
904 | * merge happens either. | |
905 | */ | |
f600abe2 | 906 | elv_quiesce_start(q); |
cb98fc8b | 907 | |
5a5bafdc TH |
908 | /* unregister and clear all auxiliary data of the old elevator */ |
909 | if (registered) | |
f8fc877d | 910 | elv_unregister_queue(q); |
1da177e4 | 911 | |
f8fc877d | 912 | spin_lock_irq(q->queue_lock); |
7e5a8794 | 913 | ioc_clear_queue(q); |
f8fc877d TH |
914 | spin_unlock_irq(q->queue_lock); |
915 | ||
5a5bafdc TH |
916 | /* allocate, init and register new elevator */ |
917 | err = -ENOMEM; | |
918 | q->elevator = elevator_alloc(q, new_e); | |
919 | if (!q->elevator) | |
920 | goto fail_init; | |
921 | ||
b2fab5ac | 922 | err = new_e->ops.elevator_init_fn(q); |
5a5bafdc TH |
923 | if (err) { |
924 | kobject_put(&q->elevator->kobj); | |
925 | goto fail_init; | |
926 | } | |
927 | ||
928 | if (registered) { | |
929 | err = elv_register_queue(q); | |
930 | if (err) | |
931 | goto fail_register; | |
932 | } | |
933 | ||
934 | /* done, kill the old one and finish */ | |
935 | elevator_exit(old); | |
f600abe2 | 936 | elv_quiesce_end(q); |
75ad23bc | 937 | |
5a5bafdc | 938 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52 | 939 | |
5dd531a0 | 940 | return 0; |
1da177e4 LT |
941 | |
942 | fail_register: | |
5a5bafdc TH |
943 | elevator_exit(q->elevator); |
944 | fail_init: | |
945 | /* switch failed, restore and re-register old elevator */ | |
946 | q->elevator = old; | |
1da177e4 | 947 | elv_register_queue(q); |
e3c78ca5 | 948 | elv_quiesce_end(q); |
75ad23bc | 949 | |
5dd531a0 | 950 | return err; |
1da177e4 LT |
951 | } |
952 | ||
5dd531a0 JA |
953 | /* |
954 | * Switch this queue to the given IO scheduler. | |
955 | */ | |
956 | int elevator_change(struct request_queue *q, const char *name) | |
1da177e4 LT |
957 | { |
958 | char elevator_name[ELV_NAME_MAX]; | |
959 | struct elevator_type *e; | |
960 | ||
cd43e26f | 961 | if (!q->elevator) |
5dd531a0 | 962 | return -ENXIO; |
cd43e26f | 963 | |
ee2e992c | 964 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 965 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
966 | if (!e) { |
967 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
968 | return -EINVAL; | |
969 | } | |
970 | ||
22f746e2 | 971 | if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
2ca7d93b | 972 | elevator_put(e); |
5dd531a0 | 973 | return 0; |
2ca7d93b | 974 | } |
1da177e4 | 975 | |
5dd531a0 JA |
976 | return elevator_switch(q, e); |
977 | } | |
978 | EXPORT_SYMBOL(elevator_change); | |
979 | ||
980 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
981 | size_t count) | |
982 | { | |
983 | int ret; | |
984 | ||
985 | if (!q->elevator) | |
986 | return count; | |
987 | ||
988 | ret = elevator_change(q, name); | |
989 | if (!ret) | |
990 | return count; | |
991 | ||
992 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
993 | return ret; | |
1da177e4 LT |
994 | } |
995 | ||
165125e1 | 996 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 997 | { |
b374d18a | 998 | struct elevator_queue *e = q->elevator; |
cd43e26f | 999 | struct elevator_type *elv; |
70cee26e | 1000 | struct elevator_type *__e; |
1da177e4 LT |
1001 | int len = 0; |
1002 | ||
e36f724b | 1003 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1004 | return sprintf(name, "none\n"); |
1005 | ||
22f746e2 | 1006 | elv = e->type; |
cd43e26f | 1007 | |
2a12dcd7 | 1008 | spin_lock(&elv_list_lock); |
70cee26e | 1009 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1010 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1011 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1012 | else | |
1013 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1014 | } | |
2a12dcd7 | 1015 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1016 | |
1017 | len += sprintf(len+name, "\n"); | |
1018 | return len; | |
1019 | } | |
1020 | ||
165125e1 JA |
1021 | struct request *elv_rb_former_request(struct request_queue *q, |
1022 | struct request *rq) | |
2e662b65 JA |
1023 | { |
1024 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1025 | ||
1026 | if (rbprev) | |
1027 | return rb_entry_rq(rbprev); | |
1028 | ||
1029 | return NULL; | |
1030 | } | |
2e662b65 JA |
1031 | EXPORT_SYMBOL(elv_rb_former_request); |
1032 | ||
165125e1 JA |
1033 | struct request *elv_rb_latter_request(struct request_queue *q, |
1034 | struct request *rq) | |
2e662b65 JA |
1035 | { |
1036 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1037 | ||
1038 | if (rbnext) | |
1039 | return rb_entry_rq(rbnext); | |
1040 | ||
1041 | return NULL; | |
1042 | } | |
2e662b65 | 1043 | EXPORT_SYMBOL(elv_rb_latter_request); |