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