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 | ||
5a5bafdc | 124 | static int elevator_init_queue(struct request_queue *q) |
1da177e4 | 125 | { |
5a5bafdc TH |
126 | q->elevator->elevator_data = q->elevator->type->ops.elevator_init_fn(q); |
127 | if (q->elevator->elevator_data) | |
f8fc877d TH |
128 | return 0; |
129 | return -ENOMEM; | |
1da177e4 LT |
130 | } |
131 | ||
484fc254 | 132 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 133 | |
5f003976 | 134 | static int __init elevator_setup(char *str) |
1da177e4 | 135 | { |
752a3b79 CE |
136 | /* |
137 | * Be backwards-compatible with previous kernels, so users | |
138 | * won't get the wrong elevator. | |
139 | */ | |
492af635 | 140 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 141 | return 1; |
1da177e4 LT |
142 | } |
143 | ||
144 | __setup("elevator=", elevator_setup); | |
145 | ||
3d1ab40f AV |
146 | static struct kobj_type elv_ktype; |
147 | ||
b374d18a | 148 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 149 | struct elevator_type *e) |
3d1ab40f | 150 | { |
b374d18a | 151 | struct elevator_queue *eq; |
9817064b JA |
152 | int i; |
153 | ||
b374d18a | 154 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
155 | if (unlikely(!eq)) |
156 | goto err; | |
157 | ||
22f746e2 | 158 | eq->type = e; |
f9cb074b | 159 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
160 | mutex_init(&eq->sysfs_lock); |
161 | ||
b5deef90 JA |
162 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
163 | GFP_KERNEL, q->node); | |
9817064b JA |
164 | if (!eq->hash) |
165 | goto err; | |
166 | ||
167 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
168 | INIT_HLIST_HEAD(&eq->hash[i]); | |
169 | ||
3d1ab40f | 170 | return eq; |
9817064b JA |
171 | err: |
172 | kfree(eq); | |
173 | elevator_put(e); | |
174 | return NULL; | |
3d1ab40f AV |
175 | } |
176 | ||
177 | static void elevator_release(struct kobject *kobj) | |
178 | { | |
b374d18a | 179 | struct elevator_queue *e; |
9817064b | 180 | |
b374d18a | 181 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 182 | elevator_put(e->type); |
9817064b | 183 | kfree(e->hash); |
3d1ab40f AV |
184 | kfree(e); |
185 | } | |
186 | ||
165125e1 | 187 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
188 | { |
189 | struct elevator_type *e = NULL; | |
f8fc877d | 190 | int err; |
1da177e4 | 191 | |
1abec4fd MS |
192 | if (unlikely(q->elevator)) |
193 | return 0; | |
194 | ||
cb98fc8b TH |
195 | INIT_LIST_HEAD(&q->queue_head); |
196 | q->last_merge = NULL; | |
197 | q->end_sector = 0; | |
198 | q->boundary_rq = NULL; | |
cb98fc8b | 199 | |
4eb166d9 JA |
200 | if (name) { |
201 | e = elevator_get(name); | |
202 | if (!e) | |
203 | return -EINVAL; | |
204 | } | |
1da177e4 | 205 | |
4eb166d9 JA |
206 | if (!e && *chosen_elevator) { |
207 | e = elevator_get(chosen_elevator); | |
208 | if (!e) | |
209 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
210 | chosen_elevator); | |
211 | } | |
248d5ca5 | 212 | |
4eb166d9 JA |
213 | if (!e) { |
214 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
215 | if (!e) { | |
216 | printk(KERN_ERR | |
217 | "Default I/O scheduler not found. " \ | |
218 | "Using noop.\n"); | |
219 | e = elevator_get("noop"); | |
220 | } | |
5f003976 ND |
221 | } |
222 | ||
5a5bafdc TH |
223 | q->elevator = elevator_alloc(q, e); |
224 | if (!q->elevator) | |
1da177e4 | 225 | return -ENOMEM; |
1da177e4 | 226 | |
5a5bafdc | 227 | err = elevator_init_queue(q); |
f8fc877d | 228 | if (err) { |
5a5bafdc | 229 | kobject_put(&q->elevator->kobj); |
f8fc877d | 230 | return err; |
bc1c1169 | 231 | } |
1da177e4 | 232 | |
1abec4fd | 233 | return 0; |
1da177e4 | 234 | } |
2e662b65 JA |
235 | EXPORT_SYMBOL(elevator_init); |
236 | ||
b374d18a | 237 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 238 | { |
3d1ab40f | 239 | mutex_lock(&e->sysfs_lock); |
22f746e2 TH |
240 | if (e->type->ops.elevator_exit_fn) |
241 | e->type->ops.elevator_exit_fn(e); | |
3d1ab40f | 242 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 243 | |
3d1ab40f | 244 | kobject_put(&e->kobj); |
1da177e4 | 245 | } |
2e662b65 JA |
246 | EXPORT_SYMBOL(elevator_exit); |
247 | ||
9817064b JA |
248 | static inline void __elv_rqhash_del(struct request *rq) |
249 | { | |
250 | hlist_del_init(&rq->hash); | |
251 | } | |
252 | ||
165125e1 | 253 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
254 | { |
255 | if (ELV_ON_HASH(rq)) | |
256 | __elv_rqhash_del(rq); | |
257 | } | |
258 | ||
165125e1 | 259 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 260 | { |
b374d18a | 261 | struct elevator_queue *e = q->elevator; |
9817064b JA |
262 | |
263 | BUG_ON(ELV_ON_HASH(rq)); | |
264 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
265 | } | |
266 | ||
165125e1 | 267 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
268 | { |
269 | __elv_rqhash_del(rq); | |
270 | elv_rqhash_add(q, rq); | |
271 | } | |
272 | ||
165125e1 | 273 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 274 | { |
b374d18a | 275 | struct elevator_queue *e = q->elevator; |
9817064b JA |
276 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
277 | struct hlist_node *entry, *next; | |
278 | struct request *rq; | |
279 | ||
280 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
281 | BUG_ON(!ELV_ON_HASH(rq)); | |
282 | ||
283 | if (unlikely(!rq_mergeable(rq))) { | |
284 | __elv_rqhash_del(rq); | |
285 | continue; | |
286 | } | |
287 | ||
288 | if (rq_hash_key(rq) == offset) | |
289 | return rq; | |
290 | } | |
291 | ||
292 | return NULL; | |
293 | } | |
294 | ||
2e662b65 JA |
295 | /* |
296 | * RB-tree support functions for inserting/lookup/removal of requests | |
297 | * in a sorted RB tree. | |
298 | */ | |
796d5116 | 299 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
300 | { |
301 | struct rb_node **p = &root->rb_node; | |
302 | struct rb_node *parent = NULL; | |
303 | struct request *__rq; | |
304 | ||
305 | while (*p) { | |
306 | parent = *p; | |
307 | __rq = rb_entry(parent, struct request, rb_node); | |
308 | ||
83096ebf | 309 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 310 | p = &(*p)->rb_left; |
796d5116 | 311 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 312 | p = &(*p)->rb_right; |
2e662b65 JA |
313 | } |
314 | ||
315 | rb_link_node(&rq->rb_node, parent, p); | |
316 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 317 | } |
2e662b65 JA |
318 | EXPORT_SYMBOL(elv_rb_add); |
319 | ||
320 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
321 | { | |
322 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
323 | rb_erase(&rq->rb_node, root); | |
324 | RB_CLEAR_NODE(&rq->rb_node); | |
325 | } | |
2e662b65 JA |
326 | EXPORT_SYMBOL(elv_rb_del); |
327 | ||
328 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
329 | { | |
330 | struct rb_node *n = root->rb_node; | |
331 | struct request *rq; | |
332 | ||
333 | while (n) { | |
334 | rq = rb_entry(n, struct request, rb_node); | |
335 | ||
83096ebf | 336 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 337 | n = n->rb_left; |
83096ebf | 338 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
339 | n = n->rb_right; |
340 | else | |
341 | return rq; | |
342 | } | |
343 | ||
344 | return NULL; | |
345 | } | |
2e662b65 JA |
346 | EXPORT_SYMBOL(elv_rb_find); |
347 | ||
8922e16c TH |
348 | /* |
349 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 350 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 351 | * specific elevators. |
8922e16c | 352 | */ |
165125e1 | 353 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
354 | { |
355 | sector_t boundary; | |
8922e16c | 356 | struct list_head *entry; |
4eb166d9 | 357 | int stop_flags; |
8922e16c | 358 | |
06b86245 TH |
359 | if (q->last_merge == rq) |
360 | q->last_merge = NULL; | |
9817064b JA |
361 | |
362 | elv_rqhash_del(q, rq); | |
363 | ||
15853af9 | 364 | q->nr_sorted--; |
06b86245 | 365 | |
1b47f531 | 366 | boundary = q->end_sector; |
02e031cb | 367 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
8922e16c TH |
368 | list_for_each_prev(entry, &q->queue_head) { |
369 | struct request *pos = list_entry_rq(entry); | |
370 | ||
33659ebb CH |
371 | if ((rq->cmd_flags & REQ_DISCARD) != |
372 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 373 | break; |
783660b2 JA |
374 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
375 | break; | |
4eb166d9 | 376 | if (pos->cmd_flags & stop_flags) |
8922e16c | 377 | break; |
83096ebf TH |
378 | if (blk_rq_pos(rq) >= boundary) { |
379 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
380 | continue; |
381 | } else { | |
83096ebf | 382 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
383 | break; |
384 | } | |
83096ebf | 385 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
386 | break; |
387 | } | |
388 | ||
389 | list_add(&rq->queuelist, entry); | |
390 | } | |
2e662b65 JA |
391 | EXPORT_SYMBOL(elv_dispatch_sort); |
392 | ||
9817064b | 393 | /* |
2e662b65 JA |
394 | * Insert rq into dispatch queue of q. Queue lock must be held on |
395 | * entry. rq is added to the back of the dispatch queue. To be used by | |
396 | * specific elevators. | |
9817064b JA |
397 | */ |
398 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
399 | { | |
400 | if (q->last_merge == rq) | |
401 | q->last_merge = NULL; | |
402 | ||
403 | elv_rqhash_del(q, rq); | |
404 | ||
405 | q->nr_sorted--; | |
406 | ||
407 | q->end_sector = rq_end_sector(rq); | |
408 | q->boundary_rq = rq; | |
409 | list_add_tail(&rq->queuelist, &q->queue_head); | |
410 | } | |
2e662b65 JA |
411 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
412 | ||
165125e1 | 413 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 414 | { |
b374d18a | 415 | struct elevator_queue *e = q->elevator; |
9817064b | 416 | struct request *__rq; |
06b86245 TH |
417 | int ret; |
418 | ||
488991e2 AB |
419 | /* |
420 | * Levels of merges: | |
421 | * nomerges: No merges at all attempted | |
422 | * noxmerges: Only simple one-hit cache try | |
423 | * merges: All merge tries attempted | |
424 | */ | |
425 | if (blk_queue_nomerges(q)) | |
426 | return ELEVATOR_NO_MERGE; | |
427 | ||
9817064b JA |
428 | /* |
429 | * First try one-hit cache. | |
430 | */ | |
050c8ea8 TH |
431 | if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { |
432 | ret = blk_try_merge(q->last_merge, bio); | |
06b86245 TH |
433 | if (ret != ELEVATOR_NO_MERGE) { |
434 | *req = q->last_merge; | |
435 | return ret; | |
436 | } | |
437 | } | |
1da177e4 | 438 | |
488991e2 | 439 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
440 | return ELEVATOR_NO_MERGE; |
441 | ||
9817064b JA |
442 | /* |
443 | * See if our hash lookup can find a potential backmerge. | |
444 | */ | |
445 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
446 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
447 | *req = __rq; | |
448 | return ELEVATOR_BACK_MERGE; | |
449 | } | |
450 | ||
22f746e2 TH |
451 | if (e->type->ops.elevator_merge_fn) |
452 | return e->type->ops.elevator_merge_fn(q, req, bio); | |
1da177e4 LT |
453 | |
454 | return ELEVATOR_NO_MERGE; | |
455 | } | |
456 | ||
5e84ea3a JA |
457 | /* |
458 | * Attempt to do an insertion back merge. Only check for the case where | |
459 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
460 | * afterwards. | |
461 | * | |
462 | * Returns true if we merged, false otherwise | |
463 | */ | |
464 | static bool elv_attempt_insert_merge(struct request_queue *q, | |
465 | struct request *rq) | |
466 | { | |
467 | struct request *__rq; | |
468 | ||
469 | if (blk_queue_nomerges(q)) | |
470 | return false; | |
471 | ||
472 | /* | |
473 | * First try one-hit cache. | |
474 | */ | |
475 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
476 | return true; | |
477 | ||
478 | if (blk_queue_noxmerges(q)) | |
479 | return false; | |
480 | ||
481 | /* | |
482 | * See if our hash lookup can find a potential backmerge. | |
483 | */ | |
5d381efb JA |
484 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); |
485 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) | |
486 | return true; | |
27419322 | 487 | |
5d381efb | 488 | return false; |
5e84ea3a JA |
489 | } |
490 | ||
165125e1 | 491 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 492 | { |
b374d18a | 493 | struct elevator_queue *e = q->elevator; |
1da177e4 | 494 | |
22f746e2 TH |
495 | if (e->type->ops.elevator_merged_fn) |
496 | e->type->ops.elevator_merged_fn(q, rq, type); | |
06b86245 | 497 | |
2e662b65 JA |
498 | if (type == ELEVATOR_BACK_MERGE) |
499 | elv_rqhash_reposition(q, rq); | |
9817064b | 500 | |
06b86245 | 501 | q->last_merge = rq; |
1da177e4 LT |
502 | } |
503 | ||
165125e1 | 504 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
505 | struct request *next) |
506 | { | |
b374d18a | 507 | struct elevator_queue *e = q->elevator; |
5e84ea3a | 508 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
1da177e4 | 509 | |
22f746e2 TH |
510 | if (next_sorted && e->type->ops.elevator_merge_req_fn) |
511 | e->type->ops.elevator_merge_req_fn(q, rq, next); | |
06b86245 | 512 | |
9817064b | 513 | elv_rqhash_reposition(q, rq); |
9817064b | 514 | |
5e84ea3a JA |
515 | if (next_sorted) { |
516 | elv_rqhash_del(q, next); | |
517 | q->nr_sorted--; | |
518 | } | |
519 | ||
06b86245 | 520 | q->last_merge = rq; |
1da177e4 LT |
521 | } |
522 | ||
812d4026 DS |
523 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
524 | struct bio *bio) | |
525 | { | |
526 | struct elevator_queue *e = q->elevator; | |
527 | ||
22f746e2 TH |
528 | if (e->type->ops.elevator_bio_merged_fn) |
529 | e->type->ops.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
530 | } |
531 | ||
165125e1 | 532 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 533 | { |
1da177e4 LT |
534 | /* |
535 | * it already went through dequeue, we need to decrement the | |
536 | * in_flight count again | |
537 | */ | |
8922e16c | 538 | if (blk_account_rq(rq)) { |
0a7ae2ff | 539 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 540 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 541 | elv_deactivate_rq(q, rq); |
8922e16c | 542 | } |
1da177e4 | 543 | |
4aff5e23 | 544 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 545 | |
b710a480 | 546 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
547 | } |
548 | ||
26308eab | 549 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
550 | { |
551 | static int printed; | |
e3c78ca5 TH |
552 | |
553 | lockdep_assert_held(q->queue_lock); | |
554 | ||
22f746e2 | 555 | while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
15853af9 | 556 | ; |
e3c78ca5 | 557 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
558 | printk(KERN_ERR "%s: forced dispatching is broken " |
559 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 560 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
561 | } |
562 | } | |
563 | ||
f600abe2 | 564 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 565 | { |
cd43e26f MP |
566 | if (!q->elevator) |
567 | return; | |
568 | ||
e3c78ca5 | 569 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 570 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 571 | spin_unlock_irq(q->queue_lock); |
6c7e8cee | 572 | |
c9a929dd | 573 | blk_drain_queue(q, false); |
6c7e8cee JA |
574 | } |
575 | ||
f600abe2 | 576 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee | 577 | { |
e3c78ca5 | 578 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 579 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 580 | spin_unlock_irq(q->queue_lock); |
6c7e8cee JA |
581 | } |
582 | ||
b710a480 | 583 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 584 | { |
5f3ea37c | 585 | trace_block_rq_insert(q, rq); |
2056a782 | 586 | |
1da177e4 LT |
587 | rq->q = q; |
588 | ||
b710a480 JA |
589 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
590 | /* barriers are scheduling boundary, update end_sector */ | |
591 | if (rq->cmd_type == REQ_TYPE_FS || | |
592 | (rq->cmd_flags & REQ_DISCARD)) { | |
593 | q->end_sector = rq_end_sector(rq); | |
594 | q->boundary_rq = rq; | |
595 | } | |
596 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && | |
3aa72873 JA |
597 | (where == ELEVATOR_INSERT_SORT || |
598 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
599 | where = ELEVATOR_INSERT_BACK; |
600 | ||
8922e16c | 601 | switch (where) { |
28e7d184 | 602 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 603 | case ELEVATOR_INSERT_FRONT: |
4aff5e23 | 604 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
605 | list_add(&rq->queuelist, &q->queue_head); |
606 | break; | |
607 | ||
608 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 609 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 610 | elv_drain_elevator(q); |
8922e16c TH |
611 | list_add_tail(&rq->queuelist, &q->queue_head); |
612 | /* | |
613 | * We kick the queue here for the following reasons. | |
614 | * - The elevator might have returned NULL previously | |
615 | * to delay requests and returned them now. As the | |
616 | * queue wasn't empty before this request, ll_rw_blk | |
617 | * won't run the queue on return, resulting in hang. | |
618 | * - Usually, back inserted requests won't be merged | |
619 | * with anything. There's no point in delaying queue | |
620 | * processing. | |
621 | */ | |
24ecfbe2 | 622 | __blk_run_queue(q); |
8922e16c TH |
623 | break; |
624 | ||
5e84ea3a JA |
625 | case ELEVATOR_INSERT_SORT_MERGE: |
626 | /* | |
627 | * If we succeed in merging this request with one in the | |
628 | * queue already, we are done - rq has now been freed, | |
629 | * so no need to do anything further. | |
630 | */ | |
631 | if (elv_attempt_insert_merge(q, rq)) | |
632 | break; | |
8922e16c | 633 | case ELEVATOR_INSERT_SORT: |
33659ebb CH |
634 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
635 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 636 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 637 | q->nr_sorted++; |
9817064b JA |
638 | if (rq_mergeable(rq)) { |
639 | elv_rqhash_add(q, rq); | |
640 | if (!q->last_merge) | |
641 | q->last_merge = rq; | |
642 | } | |
643 | ||
ca23509f TH |
644 | /* |
645 | * Some ioscheds (cfq) run q->request_fn directly, so | |
646 | * rq cannot be accessed after calling | |
647 | * elevator_add_req_fn. | |
648 | */ | |
22f746e2 | 649 | q->elevator->type->ops.elevator_add_req_fn(q, rq); |
8922e16c TH |
650 | break; |
651 | ||
ae1b1539 TH |
652 | case ELEVATOR_INSERT_FLUSH: |
653 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
654 | blk_insert_flush(rq); | |
655 | break; | |
8922e16c TH |
656 | default: |
657 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 658 | __func__, where); |
8922e16c TH |
659 | BUG(); |
660 | } | |
1da177e4 | 661 | } |
2e662b65 JA |
662 | EXPORT_SYMBOL(__elv_add_request); |
663 | ||
7eaceacc | 664 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
665 | { |
666 | unsigned long flags; | |
667 | ||
668 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 669 | __elv_add_request(q, rq, where); |
1da177e4 LT |
670 | spin_unlock_irqrestore(q->queue_lock, flags); |
671 | } | |
2e662b65 JA |
672 | EXPORT_SYMBOL(elv_add_request); |
673 | ||
165125e1 | 674 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 675 | { |
b374d18a | 676 | struct elevator_queue *e = q->elevator; |
1da177e4 | 677 | |
22f746e2 TH |
678 | if (e->type->ops.elevator_latter_req_fn) |
679 | return e->type->ops.elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
680 | return NULL; |
681 | } | |
682 | ||
165125e1 | 683 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 684 | { |
b374d18a | 685 | struct elevator_queue *e = q->elevator; |
1da177e4 | 686 | |
22f746e2 TH |
687 | if (e->type->ops.elevator_former_req_fn) |
688 | return e->type->ops.elevator_former_req_fn(q, rq); | |
1da177e4 LT |
689 | return NULL; |
690 | } | |
691 | ||
165125e1 | 692 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 693 | { |
b374d18a | 694 | struct elevator_queue *e = q->elevator; |
1da177e4 | 695 | |
22f746e2 TH |
696 | if (e->type->ops.elevator_set_req_fn) |
697 | return e->type->ops.elevator_set_req_fn(q, rq, gfp_mask); | |
1da177e4 LT |
698 | return 0; |
699 | } | |
700 | ||
165125e1 | 701 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 702 | { |
b374d18a | 703 | struct elevator_queue *e = q->elevator; |
1da177e4 | 704 | |
22f746e2 TH |
705 | if (e->type->ops.elevator_put_req_fn) |
706 | e->type->ops.elevator_put_req_fn(rq); | |
1da177e4 LT |
707 | } |
708 | ||
165125e1 | 709 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 710 | { |
b374d18a | 711 | struct elevator_queue *e = q->elevator; |
1da177e4 | 712 | |
22f746e2 TH |
713 | if (e->type->ops.elevator_may_queue_fn) |
714 | return e->type->ops.elevator_may_queue_fn(q, rw); | |
1da177e4 LT |
715 | |
716 | return ELV_MQUEUE_MAY; | |
717 | } | |
718 | ||
11914a53 MA |
719 | void elv_abort_queue(struct request_queue *q) |
720 | { | |
721 | struct request *rq; | |
722 | ||
ae1b1539 TH |
723 | blk_abort_flushes(q); |
724 | ||
11914a53 MA |
725 | while (!list_empty(&q->queue_head)) { |
726 | rq = list_entry_rq(q->queue_head.next); | |
727 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 728 | trace_block_rq_abort(q, rq); |
53c663ce KU |
729 | /* |
730 | * Mark this request as started so we don't trigger | |
731 | * any debug logic in the end I/O path. | |
732 | */ | |
733 | blk_start_request(rq); | |
40cbbb78 | 734 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
735 | } |
736 | } | |
737 | EXPORT_SYMBOL(elv_abort_queue); | |
738 | ||
165125e1 | 739 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 740 | { |
b374d18a | 741 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
742 | |
743 | /* | |
744 | * request is released from the driver, io must be done | |
745 | */ | |
8922e16c | 746 | if (blk_account_rq(rq)) { |
0a7ae2ff | 747 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 748 | if ((rq->cmd_flags & REQ_SORTED) && |
22f746e2 TH |
749 | e->type->ops.elevator_completed_req_fn) |
750 | e->type->ops.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 751 | } |
1da177e4 LT |
752 | } |
753 | ||
3d1ab40f AV |
754 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
755 | ||
756 | static ssize_t | |
757 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 758 | { |
3d1ab40f | 759 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 760 | struct elevator_queue *e; |
3d1ab40f AV |
761 | ssize_t error; |
762 | ||
763 | if (!entry->show) | |
764 | return -EIO; | |
765 | ||
b374d18a | 766 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 767 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 768 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
769 | mutex_unlock(&e->sysfs_lock); |
770 | return error; | |
771 | } | |
1da177e4 | 772 | |
3d1ab40f AV |
773 | static ssize_t |
774 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
775 | const char *page, size_t length) | |
776 | { | |
3d1ab40f | 777 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 778 | struct elevator_queue *e; |
3d1ab40f | 779 | ssize_t error; |
1da177e4 | 780 | |
3d1ab40f AV |
781 | if (!entry->store) |
782 | return -EIO; | |
1da177e4 | 783 | |
b374d18a | 784 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 785 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 786 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
787 | mutex_unlock(&e->sysfs_lock); |
788 | return error; | |
789 | } | |
790 | ||
52cf25d0 | 791 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
792 | .show = elv_attr_show, |
793 | .store = elv_attr_store, | |
794 | }; | |
795 | ||
796 | static struct kobj_type elv_ktype = { | |
797 | .sysfs_ops = &elv_sysfs_ops, | |
798 | .release = elevator_release, | |
799 | }; | |
800 | ||
5a5bafdc | 801 | int elv_register_queue(struct request_queue *q) |
3d1ab40f | 802 | { |
5a5bafdc | 803 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
804 | int error; |
805 | ||
b2d6db58 | 806 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 807 | if (!error) { |
22f746e2 | 808 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 809 | if (attr) { |
e572ec7e AV |
810 | while (attr->attr.name) { |
811 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 812 | break; |
e572ec7e | 813 | attr++; |
3d1ab40f AV |
814 | } |
815 | } | |
816 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 817 | e->registered = 1; |
3d1ab40f AV |
818 | } |
819 | return error; | |
1da177e4 | 820 | } |
f8fc877d | 821 | EXPORT_SYMBOL(elv_register_queue); |
bc1c1169 | 822 | |
1da177e4 LT |
823 | void elv_unregister_queue(struct request_queue *q) |
824 | { | |
f8fc877d TH |
825 | if (q) { |
826 | struct elevator_queue *e = q->elevator; | |
827 | ||
828 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
829 | kobject_del(&e->kobj); | |
830 | e->registered = 0; | |
831 | } | |
1da177e4 | 832 | } |
01effb0d | 833 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 834 | |
3d3c2379 | 835 | int elv_register(struct elevator_type *e) |
1da177e4 | 836 | { |
1ffb96c5 | 837 | char *def = ""; |
2a12dcd7 | 838 | |
3d3c2379 TH |
839 | /* create icq_cache if requested */ |
840 | if (e->icq_size) { | |
841 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || | |
842 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) | |
843 | return -EINVAL; | |
844 | ||
845 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), | |
846 | "%s_io_cq", e->elevator_name); | |
847 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, | |
848 | e->icq_align, 0, NULL); | |
849 | if (!e->icq_cache) | |
850 | return -ENOMEM; | |
851 | } | |
852 | ||
853 | /* register, don't allow duplicate names */ | |
2a12dcd7 | 854 | spin_lock(&elv_list_lock); |
3d3c2379 TH |
855 | if (elevator_find(e->elevator_name)) { |
856 | spin_unlock(&elv_list_lock); | |
857 | if (e->icq_cache) | |
858 | kmem_cache_destroy(e->icq_cache); | |
859 | return -EBUSY; | |
860 | } | |
1da177e4 | 861 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 862 | spin_unlock(&elv_list_lock); |
1da177e4 | 863 | |
3d3c2379 | 864 | /* print pretty message */ |
5f003976 ND |
865 | if (!strcmp(e->elevator_name, chosen_elevator) || |
866 | (!*chosen_elevator && | |
867 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
868 | def = " (default)"; |
869 | ||
4eb166d9 JA |
870 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
871 | def); | |
3d3c2379 | 872 | return 0; |
1da177e4 LT |
873 | } |
874 | EXPORT_SYMBOL_GPL(elv_register); | |
875 | ||
876 | void elv_unregister(struct elevator_type *e) | |
877 | { | |
3d3c2379 | 878 | /* unregister */ |
2a12dcd7 | 879 | spin_lock(&elv_list_lock); |
1da177e4 | 880 | list_del_init(&e->list); |
2a12dcd7 | 881 | spin_unlock(&elv_list_lock); |
3d3c2379 TH |
882 | |
883 | /* | |
884 | * Destroy icq_cache if it exists. icq's are RCU managed. Make | |
885 | * sure all RCU operations are complete before proceeding. | |
886 | */ | |
887 | if (e->icq_cache) { | |
888 | rcu_barrier(); | |
889 | kmem_cache_destroy(e->icq_cache); | |
890 | e->icq_cache = NULL; | |
891 | } | |
1da177e4 LT |
892 | } |
893 | EXPORT_SYMBOL_GPL(elv_unregister); | |
894 | ||
895 | /* | |
896 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
897 | * we don't free the old io scheduler, before we have allocated what we | |
898 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 899 | * one, if the new one fails init for some reason. |
1da177e4 | 900 | */ |
165125e1 | 901 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 902 | { |
5a5bafdc TH |
903 | struct elevator_queue *old = q->elevator; |
904 | bool registered = old->registered; | |
5dd531a0 | 905 | int err; |
1da177e4 | 906 | |
5a5bafdc TH |
907 | /* |
908 | * Turn on BYPASS and drain all requests w/ elevator private data. | |
909 | * Block layer doesn't call into a quiesced elevator - all requests | |
910 | * are directly put on the dispatch list without elevator data | |
911 | * using INSERT_BACK. All requests have SOFTBARRIER set and no | |
912 | * merge happens either. | |
913 | */ | |
f600abe2 | 914 | elv_quiesce_start(q); |
cb98fc8b | 915 | |
5a5bafdc TH |
916 | /* unregister and clear all auxiliary data of the old elevator */ |
917 | if (registered) | |
f8fc877d | 918 | elv_unregister_queue(q); |
1da177e4 | 919 | |
f8fc877d | 920 | spin_lock_irq(q->queue_lock); |
7e5a8794 | 921 | ioc_clear_queue(q); |
f8fc877d TH |
922 | spin_unlock_irq(q->queue_lock); |
923 | ||
5a5bafdc TH |
924 | /* allocate, init and register new elevator */ |
925 | err = -ENOMEM; | |
926 | q->elevator = elevator_alloc(q, new_e); | |
927 | if (!q->elevator) | |
928 | goto fail_init; | |
929 | ||
930 | err = elevator_init_queue(q); | |
931 | if (err) { | |
932 | kobject_put(&q->elevator->kobj); | |
933 | goto fail_init; | |
934 | } | |
935 | ||
936 | if (registered) { | |
937 | err = elv_register_queue(q); | |
938 | if (err) | |
939 | goto fail_register; | |
940 | } | |
941 | ||
942 | /* done, kill the old one and finish */ | |
943 | elevator_exit(old); | |
f600abe2 | 944 | elv_quiesce_end(q); |
75ad23bc | 945 | |
5a5bafdc | 946 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52 | 947 | |
5dd531a0 | 948 | return 0; |
1da177e4 LT |
949 | |
950 | fail_register: | |
5a5bafdc TH |
951 | elevator_exit(q->elevator); |
952 | fail_init: | |
953 | /* switch failed, restore and re-register old elevator */ | |
954 | q->elevator = old; | |
1da177e4 | 955 | elv_register_queue(q); |
e3c78ca5 | 956 | elv_quiesce_end(q); |
75ad23bc | 957 | |
5dd531a0 | 958 | return err; |
1da177e4 LT |
959 | } |
960 | ||
5dd531a0 JA |
961 | /* |
962 | * Switch this queue to the given IO scheduler. | |
963 | */ | |
964 | int elevator_change(struct request_queue *q, const char *name) | |
1da177e4 LT |
965 | { |
966 | char elevator_name[ELV_NAME_MAX]; | |
967 | struct elevator_type *e; | |
968 | ||
cd43e26f | 969 | if (!q->elevator) |
5dd531a0 | 970 | return -ENXIO; |
cd43e26f | 971 | |
ee2e992c | 972 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 973 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
974 | if (!e) { |
975 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
976 | return -EINVAL; | |
977 | } | |
978 | ||
22f746e2 | 979 | if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
2ca7d93b | 980 | elevator_put(e); |
5dd531a0 | 981 | return 0; |
2ca7d93b | 982 | } |
1da177e4 | 983 | |
5dd531a0 JA |
984 | return elevator_switch(q, e); |
985 | } | |
986 | EXPORT_SYMBOL(elevator_change); | |
987 | ||
988 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
989 | size_t count) | |
990 | { | |
991 | int ret; | |
992 | ||
993 | if (!q->elevator) | |
994 | return count; | |
995 | ||
996 | ret = elevator_change(q, name); | |
997 | if (!ret) | |
998 | return count; | |
999 | ||
1000 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
1001 | return ret; | |
1da177e4 LT |
1002 | } |
1003 | ||
165125e1 | 1004 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1005 | { |
b374d18a | 1006 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1007 | struct elevator_type *elv; |
70cee26e | 1008 | struct elevator_type *__e; |
1da177e4 LT |
1009 | int len = 0; |
1010 | ||
e36f724b | 1011 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1012 | return sprintf(name, "none\n"); |
1013 | ||
22f746e2 | 1014 | elv = e->type; |
cd43e26f | 1015 | |
2a12dcd7 | 1016 | spin_lock(&elv_list_lock); |
70cee26e | 1017 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1018 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1019 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1020 | else | |
1021 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1022 | } | |
2a12dcd7 | 1023 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1024 | |
1025 | len += sprintf(len+name, "\n"); | |
1026 | return len; | |
1027 | } | |
1028 | ||
165125e1 JA |
1029 | struct request *elv_rb_former_request(struct request_queue *q, |
1030 | struct request *rq) | |
2e662b65 JA |
1031 | { |
1032 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1033 | ||
1034 | if (rbprev) | |
1035 | return rb_entry_rq(rbprev); | |
1036 | ||
1037 | return NULL; | |
1038 | } | |
2e662b65 JA |
1039 | EXPORT_SYMBOL(elv_rb_former_request); |
1040 | ||
165125e1 JA |
1041 | struct request *elv_rb_latter_request(struct request_queue *q, |
1042 | struct request *rq) | |
2e662b65 JA |
1043 | { |
1044 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1045 | ||
1046 | if (rbnext) | |
1047 | return rb_entry_rq(rbnext); | |
1048 | ||
1049 | return NULL; | |
1050 | } | |
2e662b65 | 1051 | EXPORT_SYMBOL(elv_rb_latter_request); |