Commit | Line | Data |
---|---|---|
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> | |
cb98fc8b | 34 | #include <linux/delay.h> |
2056a782 | 35 | #include <linux/blktrace_api.h> |
9817064b | 36 | #include <linux/hash.h> |
0835da67 | 37 | #include <linux/uaccess.h> |
1da177e4 | 38 | |
55782138 LZ |
39 | #include <trace/events/block.h> |
40 | ||
242f9dcb JA |
41 | #include "blk.h" |
42 | ||
1da177e4 LT |
43 | static DEFINE_SPINLOCK(elv_list_lock); |
44 | static LIST_HEAD(elv_list); | |
45 | ||
9817064b JA |
46 | /* |
47 | * Merge hash stuff. | |
48 | */ | |
49 | static const int elv_hash_shift = 6; | |
50 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
51 | #define ELV_HASH_FN(sec) \ |
52 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b | 53 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
83096ebf | 54 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 55 | |
da775265 JA |
56 | /* |
57 | * Query io scheduler to see if the current process issuing bio may be | |
58 | * merged with rq. | |
59 | */ | |
60 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
61 | { | |
165125e1 | 62 | struct request_queue *q = rq->q; |
b374d18a | 63 | struct elevator_queue *e = q->elevator; |
da775265 JA |
64 | |
65 | if (e->ops->elevator_allow_merge_fn) | |
66 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
67 | ||
68 | return 1; | |
69 | } | |
70 | ||
1da177e4 LT |
71 | /* |
72 | * can we safely merge with this request? | |
73 | */ | |
72ed0bf6 | 74 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
75 | { |
76 | if (!rq_mergeable(rq)) | |
77 | return 0; | |
78 | ||
e17fc0a1 DW |
79 | /* |
80 | * Don't merge file system requests and discard requests | |
81 | */ | |
7b6d91da | 82 | if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD)) |
e17fc0a1 DW |
83 | return 0; |
84 | ||
8d57a98c AH |
85 | /* |
86 | * Don't merge discard requests and secure discard requests | |
87 | */ | |
88 | if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE)) | |
89 | return 0; | |
90 | ||
1da177e4 LT |
91 | /* |
92 | * different data direction or already started, don't merge | |
93 | */ | |
94 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
95 | return 0; | |
96 | ||
97 | /* | |
da775265 | 98 | * must be same device and not a special request |
1da177e4 | 99 | */ |
bb4067e3 | 100 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
101 | return 0; |
102 | ||
7ba1ba12 MP |
103 | /* |
104 | * only merge integrity protected bio into ditto rq | |
105 | */ | |
106 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
107 | return 0; | |
108 | ||
da775265 JA |
109 | if (!elv_iosched_allow_merge(rq, bio)) |
110 | return 0; | |
1da177e4 | 111 | |
da775265 | 112 | return 1; |
1da177e4 LT |
113 | } |
114 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
115 | ||
73c10101 | 116 | int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
117 | { |
118 | int ret = ELEVATOR_NO_MERGE; | |
119 | ||
120 | /* | |
121 | * we can merge and sequence is ok, check if it's possible | |
122 | */ | |
123 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 124 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 125 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 126 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
127 | ret = ELEVATOR_FRONT_MERGE; |
128 | } | |
129 | ||
130 | return ret; | |
131 | } | |
1da177e4 | 132 | |
1da177e4 LT |
133 | static struct elevator_type *elevator_find(const char *name) |
134 | { | |
a22b169d | 135 | struct elevator_type *e; |
1da177e4 | 136 | |
70cee26e | 137 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
138 | if (!strcmp(e->elevator_name, name)) |
139 | return e; | |
1da177e4 | 140 | } |
1da177e4 | 141 | |
a22b169d | 142 | return NULL; |
1da177e4 LT |
143 | } |
144 | ||
145 | static void elevator_put(struct elevator_type *e) | |
146 | { | |
147 | module_put(e->elevator_owner); | |
148 | } | |
149 | ||
150 | static struct elevator_type *elevator_get(const char *name) | |
151 | { | |
2824bc93 | 152 | struct elevator_type *e; |
1da177e4 | 153 | |
2a12dcd7 | 154 | spin_lock(&elv_list_lock); |
2824bc93 TH |
155 | |
156 | e = elevator_find(name); | |
e1640949 JA |
157 | if (!e) { |
158 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
159 | ||
160 | spin_unlock(&elv_list_lock); | |
161 | ||
a506aedc | 162 | snprintf(elv, sizeof(elv), "%s-iosched", name); |
e1640949 | 163 | |
e180f594 | 164 | request_module("%s", elv); |
e1640949 JA |
165 | spin_lock(&elv_list_lock); |
166 | e = elevator_find(name); | |
167 | } | |
168 | ||
2824bc93 TH |
169 | if (e && !try_module_get(e->elevator_owner)) |
170 | e = NULL; | |
171 | ||
2a12dcd7 | 172 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
173 | |
174 | return e; | |
175 | } | |
176 | ||
165125e1 JA |
177 | static void *elevator_init_queue(struct request_queue *q, |
178 | struct elevator_queue *eq) | |
1da177e4 | 179 | { |
bb37b94c | 180 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 181 | } |
1da177e4 | 182 | |
165125e1 | 183 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
184 | void *data) |
185 | { | |
1da177e4 | 186 | q->elevator = eq; |
bc1c1169 | 187 | eq->elevator_data = data; |
1da177e4 LT |
188 | } |
189 | ||
190 | static char chosen_elevator[16]; | |
191 | ||
5f003976 | 192 | static int __init elevator_setup(char *str) |
1da177e4 | 193 | { |
752a3b79 CE |
194 | /* |
195 | * Be backwards-compatible with previous kernels, so users | |
196 | * won't get the wrong elevator. | |
197 | */ | |
492af635 | 198 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 199 | return 1; |
1da177e4 LT |
200 | } |
201 | ||
202 | __setup("elevator=", elevator_setup); | |
203 | ||
3d1ab40f AV |
204 | static struct kobj_type elv_ktype; |
205 | ||
b374d18a | 206 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 207 | struct elevator_type *e) |
3d1ab40f | 208 | { |
b374d18a | 209 | struct elevator_queue *eq; |
9817064b JA |
210 | int i; |
211 | ||
b374d18a | 212 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
213 | if (unlikely(!eq)) |
214 | goto err; | |
215 | ||
9817064b JA |
216 | eq->ops = &e->ops; |
217 | eq->elevator_type = e; | |
f9cb074b | 218 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
219 | mutex_init(&eq->sysfs_lock); |
220 | ||
b5deef90 JA |
221 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
222 | GFP_KERNEL, q->node); | |
9817064b JA |
223 | if (!eq->hash) |
224 | goto err; | |
225 | ||
226 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
227 | INIT_HLIST_HEAD(&eq->hash[i]); | |
228 | ||
3d1ab40f | 229 | return eq; |
9817064b JA |
230 | err: |
231 | kfree(eq); | |
232 | elevator_put(e); | |
233 | return NULL; | |
3d1ab40f AV |
234 | } |
235 | ||
236 | static void elevator_release(struct kobject *kobj) | |
237 | { | |
b374d18a | 238 | struct elevator_queue *e; |
9817064b | 239 | |
b374d18a | 240 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 241 | elevator_put(e->elevator_type); |
9817064b | 242 | kfree(e->hash); |
3d1ab40f AV |
243 | kfree(e); |
244 | } | |
245 | ||
165125e1 | 246 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
247 | { |
248 | struct elevator_type *e = NULL; | |
249 | struct elevator_queue *eq; | |
bc1c1169 | 250 | void *data; |
1da177e4 | 251 | |
1abec4fd MS |
252 | if (unlikely(q->elevator)) |
253 | return 0; | |
254 | ||
cb98fc8b TH |
255 | INIT_LIST_HEAD(&q->queue_head); |
256 | q->last_merge = NULL; | |
257 | q->end_sector = 0; | |
258 | q->boundary_rq = NULL; | |
cb98fc8b | 259 | |
4eb166d9 JA |
260 | if (name) { |
261 | e = elevator_get(name); | |
262 | if (!e) | |
263 | return -EINVAL; | |
264 | } | |
1da177e4 | 265 | |
4eb166d9 JA |
266 | if (!e && *chosen_elevator) { |
267 | e = elevator_get(chosen_elevator); | |
268 | if (!e) | |
269 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
270 | chosen_elevator); | |
271 | } | |
248d5ca5 | 272 | |
4eb166d9 JA |
273 | if (!e) { |
274 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
275 | if (!e) { | |
276 | printk(KERN_ERR | |
277 | "Default I/O scheduler not found. " \ | |
278 | "Using noop.\n"); | |
279 | e = elevator_get("noop"); | |
280 | } | |
5f003976 ND |
281 | } |
282 | ||
b5deef90 | 283 | eq = elevator_alloc(q, e); |
3d1ab40f | 284 | if (!eq) |
1da177e4 | 285 | return -ENOMEM; |
1da177e4 | 286 | |
bc1c1169 JA |
287 | data = elevator_init_queue(q, eq); |
288 | if (!data) { | |
3d1ab40f | 289 | kobject_put(&eq->kobj); |
bc1c1169 JA |
290 | return -ENOMEM; |
291 | } | |
1da177e4 | 292 | |
bc1c1169 | 293 | elevator_attach(q, eq, data); |
1abec4fd | 294 | return 0; |
1da177e4 | 295 | } |
2e662b65 JA |
296 | EXPORT_SYMBOL(elevator_init); |
297 | ||
b374d18a | 298 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 299 | { |
3d1ab40f | 300 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
301 | if (e->ops->elevator_exit_fn) |
302 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
303 | e->ops = NULL; |
304 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 305 | |
3d1ab40f | 306 | kobject_put(&e->kobj); |
1da177e4 | 307 | } |
2e662b65 JA |
308 | EXPORT_SYMBOL(elevator_exit); |
309 | ||
9817064b JA |
310 | static inline void __elv_rqhash_del(struct request *rq) |
311 | { | |
312 | hlist_del_init(&rq->hash); | |
313 | } | |
314 | ||
165125e1 | 315 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
316 | { |
317 | if (ELV_ON_HASH(rq)) | |
318 | __elv_rqhash_del(rq); | |
319 | } | |
320 | ||
165125e1 | 321 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 322 | { |
b374d18a | 323 | struct elevator_queue *e = q->elevator; |
9817064b JA |
324 | |
325 | BUG_ON(ELV_ON_HASH(rq)); | |
326 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
327 | } | |
328 | ||
165125e1 | 329 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
330 | { |
331 | __elv_rqhash_del(rq); | |
332 | elv_rqhash_add(q, rq); | |
333 | } | |
334 | ||
165125e1 | 335 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 336 | { |
b374d18a | 337 | struct elevator_queue *e = q->elevator; |
9817064b JA |
338 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
339 | struct hlist_node *entry, *next; | |
340 | struct request *rq; | |
341 | ||
342 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
343 | BUG_ON(!ELV_ON_HASH(rq)); | |
344 | ||
345 | if (unlikely(!rq_mergeable(rq))) { | |
346 | __elv_rqhash_del(rq); | |
347 | continue; | |
348 | } | |
349 | ||
350 | if (rq_hash_key(rq) == offset) | |
351 | return rq; | |
352 | } | |
353 | ||
354 | return NULL; | |
355 | } | |
356 | ||
2e662b65 JA |
357 | /* |
358 | * RB-tree support functions for inserting/lookup/removal of requests | |
359 | * in a sorted RB tree. | |
360 | */ | |
361 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
362 | { | |
363 | struct rb_node **p = &root->rb_node; | |
364 | struct rb_node *parent = NULL; | |
365 | struct request *__rq; | |
366 | ||
367 | while (*p) { | |
368 | parent = *p; | |
369 | __rq = rb_entry(parent, struct request, rb_node); | |
370 | ||
83096ebf | 371 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 372 | p = &(*p)->rb_left; |
83096ebf | 373 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
374 | p = &(*p)->rb_right; |
375 | else | |
376 | return __rq; | |
377 | } | |
378 | ||
379 | rb_link_node(&rq->rb_node, parent, p); | |
380 | rb_insert_color(&rq->rb_node, root); | |
381 | return NULL; | |
382 | } | |
2e662b65 JA |
383 | EXPORT_SYMBOL(elv_rb_add); |
384 | ||
385 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
386 | { | |
387 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
388 | rb_erase(&rq->rb_node, root); | |
389 | RB_CLEAR_NODE(&rq->rb_node); | |
390 | } | |
2e662b65 JA |
391 | EXPORT_SYMBOL(elv_rb_del); |
392 | ||
393 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
394 | { | |
395 | struct rb_node *n = root->rb_node; | |
396 | struct request *rq; | |
397 | ||
398 | while (n) { | |
399 | rq = rb_entry(n, struct request, rb_node); | |
400 | ||
83096ebf | 401 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 402 | n = n->rb_left; |
83096ebf | 403 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
404 | n = n->rb_right; |
405 | else | |
406 | return rq; | |
407 | } | |
408 | ||
409 | return NULL; | |
410 | } | |
2e662b65 JA |
411 | EXPORT_SYMBOL(elv_rb_find); |
412 | ||
8922e16c TH |
413 | /* |
414 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 415 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 416 | * specific elevators. |
8922e16c | 417 | */ |
165125e1 | 418 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
419 | { |
420 | sector_t boundary; | |
8922e16c | 421 | struct list_head *entry; |
4eb166d9 | 422 | int stop_flags; |
8922e16c | 423 | |
73c10101 JA |
424 | BUG_ON(rq->cmd_flags & REQ_ON_PLUG); |
425 | ||
06b86245 TH |
426 | if (q->last_merge == rq) |
427 | q->last_merge = NULL; | |
9817064b JA |
428 | |
429 | elv_rqhash_del(q, rq); | |
430 | ||
15853af9 | 431 | q->nr_sorted--; |
06b86245 | 432 | |
1b47f531 | 433 | boundary = q->end_sector; |
02e031cb | 434 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
8922e16c TH |
435 | list_for_each_prev(entry, &q->queue_head) { |
436 | struct request *pos = list_entry_rq(entry); | |
437 | ||
33659ebb CH |
438 | if ((rq->cmd_flags & REQ_DISCARD) != |
439 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 440 | break; |
783660b2 JA |
441 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
442 | break; | |
4eb166d9 | 443 | if (pos->cmd_flags & stop_flags) |
8922e16c | 444 | break; |
83096ebf TH |
445 | if (blk_rq_pos(rq) >= boundary) { |
446 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
447 | continue; |
448 | } else { | |
83096ebf | 449 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
450 | break; |
451 | } | |
83096ebf | 452 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
453 | break; |
454 | } | |
455 | ||
456 | list_add(&rq->queuelist, entry); | |
457 | } | |
2e662b65 JA |
458 | EXPORT_SYMBOL(elv_dispatch_sort); |
459 | ||
9817064b | 460 | /* |
2e662b65 JA |
461 | * Insert rq into dispatch queue of q. Queue lock must be held on |
462 | * entry. rq is added to the back of the dispatch queue. To be used by | |
463 | * specific elevators. | |
9817064b JA |
464 | */ |
465 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
466 | { | |
467 | if (q->last_merge == rq) | |
468 | q->last_merge = NULL; | |
469 | ||
470 | elv_rqhash_del(q, rq); | |
471 | ||
472 | q->nr_sorted--; | |
473 | ||
474 | q->end_sector = rq_end_sector(rq); | |
475 | q->boundary_rq = rq; | |
476 | list_add_tail(&rq->queuelist, &q->queue_head); | |
477 | } | |
2e662b65 JA |
478 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
479 | ||
165125e1 | 480 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 481 | { |
b374d18a | 482 | struct elevator_queue *e = q->elevator; |
9817064b | 483 | struct request *__rq; |
06b86245 TH |
484 | int ret; |
485 | ||
488991e2 AB |
486 | /* |
487 | * Levels of merges: | |
488 | * nomerges: No merges at all attempted | |
489 | * noxmerges: Only simple one-hit cache try | |
490 | * merges: All merge tries attempted | |
491 | */ | |
492 | if (blk_queue_nomerges(q)) | |
493 | return ELEVATOR_NO_MERGE; | |
494 | ||
9817064b JA |
495 | /* |
496 | * First try one-hit cache. | |
497 | */ | |
06b86245 TH |
498 | if (q->last_merge) { |
499 | ret = elv_try_merge(q->last_merge, bio); | |
500 | if (ret != ELEVATOR_NO_MERGE) { | |
501 | *req = q->last_merge; | |
502 | return ret; | |
503 | } | |
504 | } | |
1da177e4 | 505 | |
488991e2 | 506 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
507 | return ELEVATOR_NO_MERGE; |
508 | ||
9817064b JA |
509 | /* |
510 | * See if our hash lookup can find a potential backmerge. | |
511 | */ | |
512 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
513 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
514 | *req = __rq; | |
515 | return ELEVATOR_BACK_MERGE; | |
516 | } | |
517 | ||
1da177e4 LT |
518 | if (e->ops->elevator_merge_fn) |
519 | return e->ops->elevator_merge_fn(q, req, bio); | |
520 | ||
521 | return ELEVATOR_NO_MERGE; | |
522 | } | |
523 | ||
165125e1 | 524 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 525 | { |
b374d18a | 526 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
527 | |
528 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 529 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 530 | |
2e662b65 JA |
531 | if (type == ELEVATOR_BACK_MERGE) |
532 | elv_rqhash_reposition(q, rq); | |
9817064b | 533 | |
06b86245 | 534 | q->last_merge = rq; |
1da177e4 LT |
535 | } |
536 | ||
165125e1 | 537 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
538 | struct request *next) |
539 | { | |
b374d18a | 540 | struct elevator_queue *e = q->elevator; |
1da177e4 | 541 | |
1da177e4 LT |
542 | if (e->ops->elevator_merge_req_fn) |
543 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 544 | |
9817064b JA |
545 | elv_rqhash_reposition(q, rq); |
546 | elv_rqhash_del(q, next); | |
547 | ||
548 | q->nr_sorted--; | |
06b86245 | 549 | q->last_merge = rq; |
1da177e4 LT |
550 | } |
551 | ||
812d4026 DS |
552 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
553 | struct bio *bio) | |
554 | { | |
555 | struct elevator_queue *e = q->elevator; | |
556 | ||
557 | if (e->ops->elevator_bio_merged_fn) | |
558 | e->ops->elevator_bio_merged_fn(q, rq, bio); | |
559 | } | |
560 | ||
165125e1 | 561 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 562 | { |
1da177e4 LT |
563 | /* |
564 | * it already went through dequeue, we need to decrement the | |
565 | * in_flight count again | |
566 | */ | |
8922e16c | 567 | if (blk_account_rq(rq)) { |
0a7ae2ff | 568 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 569 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 570 | elv_deactivate_rq(q, rq); |
8922e16c | 571 | } |
1da177e4 | 572 | |
4aff5e23 | 573 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 574 | |
30e9656c | 575 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
576 | } |
577 | ||
26308eab | 578 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
579 | { |
580 | static int printed; | |
581 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
582 | ; | |
583 | if (q->nr_sorted == 0) | |
584 | return; | |
585 | if (printed++ < 10) { | |
586 | printk(KERN_ERR "%s: forced dispatching is broken " | |
587 | "(nr_sorted=%u), please report this\n", | |
588 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
589 | } | |
590 | } | |
591 | ||
6c7e8cee JA |
592 | /* |
593 | * Call with queue lock held, interrupts disabled | |
594 | */ | |
f600abe2 | 595 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 596 | { |
cd43e26f MP |
597 | if (!q->elevator) |
598 | return; | |
599 | ||
6c7e8cee JA |
600 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
601 | ||
602 | /* | |
603 | * make sure we don't have any requests in flight | |
604 | */ | |
605 | elv_drain_elevator(q); | |
606 | while (q->rq.elvpriv) { | |
1654e741 | 607 | __blk_run_queue(q, false); |
6c7e8cee JA |
608 | spin_unlock_irq(q->queue_lock); |
609 | msleep(10); | |
610 | spin_lock_irq(q->queue_lock); | |
611 | elv_drain_elevator(q); | |
612 | } | |
613 | } | |
614 | ||
f600abe2 | 615 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
616 | { |
617 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
618 | } | |
619 | ||
165125e1 | 620 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 621 | { |
5f3ea37c | 622 | trace_block_rq_insert(q, rq); |
2056a782 | 623 | |
1da177e4 LT |
624 | rq->q = q; |
625 | ||
8922e16c | 626 | switch (where) { |
28e7d184 | 627 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 628 | case ELEVATOR_INSERT_FRONT: |
4aff5e23 | 629 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
630 | list_add(&rq->queuelist, &q->queue_head); |
631 | break; | |
632 | ||
633 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 634 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 635 | elv_drain_elevator(q); |
8922e16c TH |
636 | list_add_tail(&rq->queuelist, &q->queue_head); |
637 | /* | |
638 | * We kick the queue here for the following reasons. | |
639 | * - The elevator might have returned NULL previously | |
640 | * to delay requests and returned them now. As the | |
641 | * queue wasn't empty before this request, ll_rw_blk | |
642 | * won't run the queue on return, resulting in hang. | |
643 | * - Usually, back inserted requests won't be merged | |
644 | * with anything. There's no point in delaying queue | |
645 | * processing. | |
646 | */ | |
1654e741 | 647 | __blk_run_queue(q, false); |
8922e16c TH |
648 | break; |
649 | ||
650 | case ELEVATOR_INSERT_SORT: | |
33659ebb CH |
651 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
652 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 653 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 654 | q->nr_sorted++; |
9817064b JA |
655 | if (rq_mergeable(rq)) { |
656 | elv_rqhash_add(q, rq); | |
657 | if (!q->last_merge) | |
658 | q->last_merge = rq; | |
659 | } | |
660 | ||
ca23509f TH |
661 | /* |
662 | * Some ioscheds (cfq) run q->request_fn directly, so | |
663 | * rq cannot be accessed after calling | |
664 | * elevator_add_req_fn. | |
665 | */ | |
666 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
667 | break; |
668 | ||
ae1b1539 TH |
669 | case ELEVATOR_INSERT_FLUSH: |
670 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
671 | blk_insert_flush(rq); | |
672 | break; | |
8922e16c TH |
673 | default: |
674 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 675 | __func__, where); |
8922e16c TH |
676 | BUG(); |
677 | } | |
1da177e4 LT |
678 | } |
679 | ||
7eaceacc | 680 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
30e9656c | 681 | { |
73c10101 JA |
682 | BUG_ON(rq->cmd_flags & REQ_ON_PLUG); |
683 | ||
02e031cb | 684 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
28e7d184 | 685 | /* barriers are scheduling boundary, update end_sector */ |
33659ebb CH |
686 | if (rq->cmd_type == REQ_TYPE_FS || |
687 | (rq->cmd_flags & REQ_DISCARD)) { | |
30e9656c TH |
688 | q->end_sector = rq_end_sector(rq); |
689 | q->boundary_rq = rq; | |
690 | } | |
4eb166d9 JA |
691 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
692 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
693 | where = ELEVATOR_INSERT_BACK; |
694 | ||
30e9656c TH |
695 | elv_insert(q, rq, where); |
696 | } | |
2e662b65 JA |
697 | EXPORT_SYMBOL(__elv_add_request); |
698 | ||
7eaceacc | 699 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
700 | { |
701 | unsigned long flags; | |
702 | ||
703 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 704 | __elv_add_request(q, rq, where); |
1da177e4 LT |
705 | spin_unlock_irqrestore(q->queue_lock, flags); |
706 | } | |
2e662b65 JA |
707 | EXPORT_SYMBOL(elv_add_request); |
708 | ||
165125e1 | 709 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 710 | { |
b374d18a | 711 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
712 | |
713 | if (e->ops->elevator_latter_req_fn) | |
714 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
715 | return NULL; |
716 | } | |
717 | ||
165125e1 | 718 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 719 | { |
b374d18a | 720 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
721 | |
722 | if (e->ops->elevator_former_req_fn) | |
723 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
724 | return NULL; |
725 | } | |
726 | ||
165125e1 | 727 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 728 | { |
b374d18a | 729 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
730 | |
731 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 732 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 | 733 | |
c186794d | 734 | rq->elevator_private[0] = NULL; |
1da177e4 LT |
735 | return 0; |
736 | } | |
737 | ||
165125e1 | 738 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 739 | { |
b374d18a | 740 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
741 | |
742 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 743 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
744 | } |
745 | ||
165125e1 | 746 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 747 | { |
b374d18a | 748 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
749 | |
750 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 751 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
752 | |
753 | return ELV_MQUEUE_MAY; | |
754 | } | |
755 | ||
11914a53 MA |
756 | void elv_abort_queue(struct request_queue *q) |
757 | { | |
758 | struct request *rq; | |
759 | ||
ae1b1539 TH |
760 | blk_abort_flushes(q); |
761 | ||
11914a53 MA |
762 | while (!list_empty(&q->queue_head)) { |
763 | rq = list_entry_rq(q->queue_head.next); | |
764 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 765 | trace_block_rq_abort(q, rq); |
53c663ce KU |
766 | /* |
767 | * Mark this request as started so we don't trigger | |
768 | * any debug logic in the end I/O path. | |
769 | */ | |
770 | blk_start_request(rq); | |
40cbbb78 | 771 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
772 | } |
773 | } | |
774 | EXPORT_SYMBOL(elv_abort_queue); | |
775 | ||
165125e1 | 776 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 777 | { |
b374d18a | 778 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
779 | |
780 | /* | |
781 | * request is released from the driver, io must be done | |
782 | */ | |
8922e16c | 783 | if (blk_account_rq(rq)) { |
0a7ae2ff | 784 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb CH |
785 | if ((rq->cmd_flags & REQ_SORTED) && |
786 | e->ops->elevator_completed_req_fn) | |
1bc691d3 TH |
787 | e->ops->elevator_completed_req_fn(q, rq); |
788 | } | |
1da177e4 LT |
789 | } |
790 | ||
3d1ab40f AV |
791 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
792 | ||
793 | static ssize_t | |
794 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 795 | { |
3d1ab40f | 796 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 797 | struct elevator_queue *e; |
3d1ab40f AV |
798 | ssize_t error; |
799 | ||
800 | if (!entry->show) | |
801 | return -EIO; | |
802 | ||
b374d18a | 803 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
804 | mutex_lock(&e->sysfs_lock); |
805 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
806 | mutex_unlock(&e->sysfs_lock); | |
807 | return error; | |
808 | } | |
1da177e4 | 809 | |
3d1ab40f AV |
810 | static ssize_t |
811 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
812 | const char *page, size_t length) | |
813 | { | |
3d1ab40f | 814 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 815 | struct elevator_queue *e; |
3d1ab40f | 816 | ssize_t error; |
1da177e4 | 817 | |
3d1ab40f AV |
818 | if (!entry->store) |
819 | return -EIO; | |
1da177e4 | 820 | |
b374d18a | 821 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
822 | mutex_lock(&e->sysfs_lock); |
823 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
824 | mutex_unlock(&e->sysfs_lock); | |
825 | return error; | |
826 | } | |
827 | ||
52cf25d0 | 828 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
829 | .show = elv_attr_show, |
830 | .store = elv_attr_store, | |
831 | }; | |
832 | ||
833 | static struct kobj_type elv_ktype = { | |
834 | .sysfs_ops = &elv_sysfs_ops, | |
835 | .release = elevator_release, | |
836 | }; | |
837 | ||
838 | int elv_register_queue(struct request_queue *q) | |
839 | { | |
b374d18a | 840 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
841 | int error; |
842 | ||
b2d6db58 | 843 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 844 | if (!error) { |
e572ec7e | 845 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 846 | if (attr) { |
e572ec7e AV |
847 | while (attr->attr.name) { |
848 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 849 | break; |
e572ec7e | 850 | attr++; |
3d1ab40f AV |
851 | } |
852 | } | |
853 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 854 | e->registered = 1; |
3d1ab40f AV |
855 | } |
856 | return error; | |
1da177e4 | 857 | } |
01effb0d | 858 | EXPORT_SYMBOL(elv_register_queue); |
1da177e4 | 859 | |
b374d18a | 860 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
861 | { |
862 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
863 | kobject_del(&e->kobj); | |
430c62fb | 864 | e->registered = 0; |
bc1c1169 JA |
865 | } |
866 | ||
1da177e4 LT |
867 | void elv_unregister_queue(struct request_queue *q) |
868 | { | |
bc1c1169 JA |
869 | if (q) |
870 | __elv_unregister_queue(q->elevator); | |
1da177e4 | 871 | } |
01effb0d | 872 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 873 | |
2fdd82bd | 874 | void elv_register(struct elevator_type *e) |
1da177e4 | 875 | { |
1ffb96c5 | 876 | char *def = ""; |
2a12dcd7 JA |
877 | |
878 | spin_lock(&elv_list_lock); | |
ce524497 | 879 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 880 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 881 | spin_unlock(&elv_list_lock); |
1da177e4 | 882 | |
5f003976 ND |
883 | if (!strcmp(e->elevator_name, chosen_elevator) || |
884 | (!*chosen_elevator && | |
885 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
886 | def = " (default)"; |
887 | ||
4eb166d9 JA |
888 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
889 | def); | |
1da177e4 LT |
890 | } |
891 | EXPORT_SYMBOL_GPL(elv_register); | |
892 | ||
893 | void elv_unregister(struct elevator_type *e) | |
894 | { | |
83521d3e CH |
895 | struct task_struct *g, *p; |
896 | ||
897 | /* | |
898 | * Iterate every thread in the process to remove the io contexts. | |
899 | */ | |
e17a9489 AV |
900 | if (e->ops.trim) { |
901 | read_lock(&tasklist_lock); | |
902 | do_each_thread(g, p) { | |
903 | task_lock(p); | |
2d8f6131 ON |
904 | if (p->io_context) |
905 | e->ops.trim(p->io_context); | |
e17a9489 AV |
906 | task_unlock(p); |
907 | } while_each_thread(g, p); | |
908 | read_unlock(&tasklist_lock); | |
909 | } | |
83521d3e | 910 | |
2a12dcd7 | 911 | spin_lock(&elv_list_lock); |
1da177e4 | 912 | list_del_init(&e->list); |
2a12dcd7 | 913 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
914 | } |
915 | EXPORT_SYMBOL_GPL(elv_unregister); | |
916 | ||
917 | /* | |
918 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
919 | * we don't free the old io scheduler, before we have allocated what we | |
920 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 921 | * one, if the new one fails init for some reason. |
1da177e4 | 922 | */ |
165125e1 | 923 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 924 | { |
b374d18a | 925 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 926 | void *data; |
5dd531a0 | 927 | int err; |
1da177e4 | 928 | |
cb98fc8b TH |
929 | /* |
930 | * Allocate new elevator | |
931 | */ | |
b5deef90 | 932 | e = elevator_alloc(q, new_e); |
1da177e4 | 933 | if (!e) |
5dd531a0 | 934 | return -ENOMEM; |
1da177e4 | 935 | |
bc1c1169 JA |
936 | data = elevator_init_queue(q, e); |
937 | if (!data) { | |
938 | kobject_put(&e->kobj); | |
5dd531a0 | 939 | return -ENOMEM; |
bc1c1169 JA |
940 | } |
941 | ||
1da177e4 | 942 | /* |
cb98fc8b | 943 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 944 | */ |
cb98fc8b | 945 | spin_lock_irq(q->queue_lock); |
f600abe2 | 946 | elv_quiesce_start(q); |
cb98fc8b | 947 | |
1da177e4 | 948 | /* |
bc1c1169 | 949 | * Remember old elevator. |
1da177e4 | 950 | */ |
1da177e4 LT |
951 | old_elevator = q->elevator; |
952 | ||
1da177e4 LT |
953 | /* |
954 | * attach and start new elevator | |
955 | */ | |
bc1c1169 JA |
956 | elevator_attach(q, e, data); |
957 | ||
958 | spin_unlock_irq(q->queue_lock); | |
959 | ||
430c62fb JA |
960 | if (old_elevator->registered) { |
961 | __elv_unregister_queue(old_elevator); | |
1da177e4 | 962 | |
430c62fb JA |
963 | err = elv_register_queue(q); |
964 | if (err) | |
965 | goto fail_register; | |
966 | } | |
1da177e4 LT |
967 | |
968 | /* | |
cb98fc8b | 969 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
970 | */ |
971 | elevator_exit(old_elevator); | |
75ad23bc | 972 | spin_lock_irq(q->queue_lock); |
f600abe2 | 973 | elv_quiesce_end(q); |
75ad23bc NP |
974 | spin_unlock_irq(q->queue_lock); |
975 | ||
4722dc52 AB |
976 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
977 | ||
5dd531a0 | 978 | return 0; |
1da177e4 LT |
979 | |
980 | fail_register: | |
981 | /* | |
982 | * switch failed, exit the new io scheduler and reattach the old | |
983 | * one again (along with re-adding the sysfs dir) | |
984 | */ | |
985 | elevator_exit(e); | |
1da177e4 LT |
986 | q->elevator = old_elevator; |
987 | elv_register_queue(q); | |
75ad23bc NP |
988 | |
989 | spin_lock_irq(q->queue_lock); | |
990 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
991 | spin_unlock_irq(q->queue_lock); | |
992 | ||
5dd531a0 | 993 | return err; |
1da177e4 LT |
994 | } |
995 | ||
5dd531a0 JA |
996 | /* |
997 | * Switch this queue to the given IO scheduler. | |
998 | */ | |
999 | int elevator_change(struct request_queue *q, const char *name) | |
1da177e4 LT |
1000 | { |
1001 | char elevator_name[ELV_NAME_MAX]; | |
1002 | struct elevator_type *e; | |
1003 | ||
cd43e26f | 1004 | if (!q->elevator) |
5dd531a0 | 1005 | return -ENXIO; |
cd43e26f | 1006 | |
ee2e992c | 1007 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 1008 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
1009 | if (!e) { |
1010 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1011 | return -EINVAL; | |
1012 | } | |
1013 | ||
2ca7d93b ND |
1014 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1015 | elevator_put(e); | |
5dd531a0 | 1016 | return 0; |
2ca7d93b | 1017 | } |
1da177e4 | 1018 | |
5dd531a0 JA |
1019 | return elevator_switch(q, e); |
1020 | } | |
1021 | EXPORT_SYMBOL(elevator_change); | |
1022 | ||
1023 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
1024 | size_t count) | |
1025 | { | |
1026 | int ret; | |
1027 | ||
1028 | if (!q->elevator) | |
1029 | return count; | |
1030 | ||
1031 | ret = elevator_change(q, name); | |
1032 | if (!ret) | |
1033 | return count; | |
1034 | ||
1035 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
1036 | return ret; | |
1da177e4 LT |
1037 | } |
1038 | ||
165125e1 | 1039 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1040 | { |
b374d18a | 1041 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1042 | struct elevator_type *elv; |
70cee26e | 1043 | struct elevator_type *__e; |
1da177e4 LT |
1044 | int len = 0; |
1045 | ||
e36f724b | 1046 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1047 | return sprintf(name, "none\n"); |
1048 | ||
1049 | elv = e->elevator_type; | |
1050 | ||
2a12dcd7 | 1051 | spin_lock(&elv_list_lock); |
70cee26e | 1052 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1053 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1054 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1055 | else | |
1056 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1057 | } | |
2a12dcd7 | 1058 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1059 | |
1060 | len += sprintf(len+name, "\n"); | |
1061 | return len; | |
1062 | } | |
1063 | ||
165125e1 JA |
1064 | struct request *elv_rb_former_request(struct request_queue *q, |
1065 | struct request *rq) | |
2e662b65 JA |
1066 | { |
1067 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1068 | ||
1069 | if (rbprev) | |
1070 | return rb_entry_rq(rbprev); | |
1071 | ||
1072 | return NULL; | |
1073 | } | |
2e662b65 JA |
1074 | EXPORT_SYMBOL(elv_rb_former_request); |
1075 | ||
165125e1 JA |
1076 | struct request *elv_rb_latter_request(struct request_queue *q, |
1077 | struct request *rq) | |
2e662b65 JA |
1078 | { |
1079 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1080 | ||
1081 | if (rbnext) | |
1082 | return rb_entry_rq(rbnext); | |
1083 | ||
1084 | return NULL; | |
1085 | } | |
2e662b65 | 1086 | EXPORT_SYMBOL(elv_rb_latter_request); |