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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> | |
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 | 157 | if (!e) { |
e1640949 | 158 | spin_unlock(&elv_list_lock); |
490b94be | 159 | request_module("%s-iosched", name); |
e1640949 JA |
160 | spin_lock(&elv_list_lock); |
161 | e = elevator_find(name); | |
162 | } | |
163 | ||
2824bc93 TH |
164 | if (e && !try_module_get(e->elevator_owner)) |
165 | e = NULL; | |
166 | ||
2a12dcd7 | 167 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
168 | |
169 | return e; | |
170 | } | |
171 | ||
165125e1 JA |
172 | static void *elevator_init_queue(struct request_queue *q, |
173 | struct elevator_queue *eq) | |
1da177e4 | 174 | { |
bb37b94c | 175 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 176 | } |
1da177e4 | 177 | |
165125e1 | 178 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
179 | void *data) |
180 | { | |
1da177e4 | 181 | q->elevator = eq; |
bc1c1169 | 182 | eq->elevator_data = data; |
1da177e4 LT |
183 | } |
184 | ||
185 | static char chosen_elevator[16]; | |
186 | ||
5f003976 | 187 | static int __init elevator_setup(char *str) |
1da177e4 | 188 | { |
752a3b79 CE |
189 | /* |
190 | * Be backwards-compatible with previous kernels, so users | |
191 | * won't get the wrong elevator. | |
192 | */ | |
492af635 | 193 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 194 | return 1; |
1da177e4 LT |
195 | } |
196 | ||
197 | __setup("elevator=", elevator_setup); | |
198 | ||
3d1ab40f AV |
199 | static struct kobj_type elv_ktype; |
200 | ||
b374d18a | 201 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 202 | struct elevator_type *e) |
3d1ab40f | 203 | { |
b374d18a | 204 | struct elevator_queue *eq; |
9817064b JA |
205 | int i; |
206 | ||
b374d18a | 207 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
208 | if (unlikely(!eq)) |
209 | goto err; | |
210 | ||
9817064b JA |
211 | eq->ops = &e->ops; |
212 | eq->elevator_type = e; | |
f9cb074b | 213 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
214 | mutex_init(&eq->sysfs_lock); |
215 | ||
b5deef90 JA |
216 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
217 | GFP_KERNEL, q->node); | |
9817064b JA |
218 | if (!eq->hash) |
219 | goto err; | |
220 | ||
221 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
222 | INIT_HLIST_HEAD(&eq->hash[i]); | |
223 | ||
3d1ab40f | 224 | return eq; |
9817064b JA |
225 | err: |
226 | kfree(eq); | |
227 | elevator_put(e); | |
228 | return NULL; | |
3d1ab40f AV |
229 | } |
230 | ||
231 | static void elevator_release(struct kobject *kobj) | |
232 | { | |
b374d18a | 233 | struct elevator_queue *e; |
9817064b | 234 | |
b374d18a | 235 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 236 | elevator_put(e->elevator_type); |
9817064b | 237 | kfree(e->hash); |
3d1ab40f AV |
238 | kfree(e); |
239 | } | |
240 | ||
165125e1 | 241 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
242 | { |
243 | struct elevator_type *e = NULL; | |
244 | struct elevator_queue *eq; | |
bc1c1169 | 245 | void *data; |
1da177e4 | 246 | |
1abec4fd MS |
247 | if (unlikely(q->elevator)) |
248 | return 0; | |
249 | ||
cb98fc8b TH |
250 | INIT_LIST_HEAD(&q->queue_head); |
251 | q->last_merge = NULL; | |
252 | q->end_sector = 0; | |
253 | q->boundary_rq = NULL; | |
cb98fc8b | 254 | |
4eb166d9 JA |
255 | if (name) { |
256 | e = elevator_get(name); | |
257 | if (!e) | |
258 | return -EINVAL; | |
259 | } | |
1da177e4 | 260 | |
4eb166d9 JA |
261 | if (!e && *chosen_elevator) { |
262 | e = elevator_get(chosen_elevator); | |
263 | if (!e) | |
264 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
265 | chosen_elevator); | |
266 | } | |
248d5ca5 | 267 | |
4eb166d9 JA |
268 | if (!e) { |
269 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
270 | if (!e) { | |
271 | printk(KERN_ERR | |
272 | "Default I/O scheduler not found. " \ | |
273 | "Using noop.\n"); | |
274 | e = elevator_get("noop"); | |
275 | } | |
5f003976 ND |
276 | } |
277 | ||
b5deef90 | 278 | eq = elevator_alloc(q, e); |
3d1ab40f | 279 | if (!eq) |
1da177e4 | 280 | return -ENOMEM; |
1da177e4 | 281 | |
bc1c1169 JA |
282 | data = elevator_init_queue(q, eq); |
283 | if (!data) { | |
3d1ab40f | 284 | kobject_put(&eq->kobj); |
bc1c1169 JA |
285 | return -ENOMEM; |
286 | } | |
1da177e4 | 287 | |
bc1c1169 | 288 | elevator_attach(q, eq, data); |
1abec4fd | 289 | return 0; |
1da177e4 | 290 | } |
2e662b65 JA |
291 | EXPORT_SYMBOL(elevator_init); |
292 | ||
b374d18a | 293 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 294 | { |
3d1ab40f | 295 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
296 | if (e->ops->elevator_exit_fn) |
297 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
298 | e->ops = NULL; |
299 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 300 | |
3d1ab40f | 301 | kobject_put(&e->kobj); |
1da177e4 | 302 | } |
2e662b65 JA |
303 | EXPORT_SYMBOL(elevator_exit); |
304 | ||
9817064b JA |
305 | static inline void __elv_rqhash_del(struct request *rq) |
306 | { | |
307 | hlist_del_init(&rq->hash); | |
308 | } | |
309 | ||
165125e1 | 310 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
311 | { |
312 | if (ELV_ON_HASH(rq)) | |
313 | __elv_rqhash_del(rq); | |
314 | } | |
315 | ||
165125e1 | 316 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 317 | { |
b374d18a | 318 | struct elevator_queue *e = q->elevator; |
9817064b JA |
319 | |
320 | BUG_ON(ELV_ON_HASH(rq)); | |
321 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
322 | } | |
323 | ||
165125e1 | 324 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
325 | { |
326 | __elv_rqhash_del(rq); | |
327 | elv_rqhash_add(q, rq); | |
328 | } | |
329 | ||
165125e1 | 330 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 331 | { |
b374d18a | 332 | struct elevator_queue *e = q->elevator; |
9817064b JA |
333 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
334 | struct hlist_node *entry, *next; | |
335 | struct request *rq; | |
336 | ||
337 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
338 | BUG_ON(!ELV_ON_HASH(rq)); | |
339 | ||
340 | if (unlikely(!rq_mergeable(rq))) { | |
341 | __elv_rqhash_del(rq); | |
342 | continue; | |
343 | } | |
344 | ||
345 | if (rq_hash_key(rq) == offset) | |
346 | return rq; | |
347 | } | |
348 | ||
349 | return NULL; | |
350 | } | |
351 | ||
2e662b65 JA |
352 | /* |
353 | * RB-tree support functions for inserting/lookup/removal of requests | |
354 | * in a sorted RB tree. | |
355 | */ | |
796d5116 | 356 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
357 | { |
358 | struct rb_node **p = &root->rb_node; | |
359 | struct rb_node *parent = NULL; | |
360 | struct request *__rq; | |
361 | ||
362 | while (*p) { | |
363 | parent = *p; | |
364 | __rq = rb_entry(parent, struct request, rb_node); | |
365 | ||
83096ebf | 366 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 367 | p = &(*p)->rb_left; |
796d5116 | 368 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 369 | p = &(*p)->rb_right; |
2e662b65 JA |
370 | } |
371 | ||
372 | rb_link_node(&rq->rb_node, parent, p); | |
373 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 374 | } |
2e662b65 JA |
375 | EXPORT_SYMBOL(elv_rb_add); |
376 | ||
377 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
378 | { | |
379 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
380 | rb_erase(&rq->rb_node, root); | |
381 | RB_CLEAR_NODE(&rq->rb_node); | |
382 | } | |
2e662b65 JA |
383 | EXPORT_SYMBOL(elv_rb_del); |
384 | ||
385 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
386 | { | |
387 | struct rb_node *n = root->rb_node; | |
388 | struct request *rq; | |
389 | ||
390 | while (n) { | |
391 | rq = rb_entry(n, struct request, rb_node); | |
392 | ||
83096ebf | 393 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 394 | n = n->rb_left; |
83096ebf | 395 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
396 | n = n->rb_right; |
397 | else | |
398 | return rq; | |
399 | } | |
400 | ||
401 | return NULL; | |
402 | } | |
2e662b65 JA |
403 | EXPORT_SYMBOL(elv_rb_find); |
404 | ||
8922e16c TH |
405 | /* |
406 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 407 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 408 | * specific elevators. |
8922e16c | 409 | */ |
165125e1 | 410 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
411 | { |
412 | sector_t boundary; | |
8922e16c | 413 | struct list_head *entry; |
4eb166d9 | 414 | int stop_flags; |
8922e16c | 415 | |
06b86245 TH |
416 | if (q->last_merge == rq) |
417 | q->last_merge = NULL; | |
9817064b JA |
418 | |
419 | elv_rqhash_del(q, rq); | |
420 | ||
15853af9 | 421 | q->nr_sorted--; |
06b86245 | 422 | |
1b47f531 | 423 | boundary = q->end_sector; |
02e031cb | 424 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
8922e16c TH |
425 | list_for_each_prev(entry, &q->queue_head) { |
426 | struct request *pos = list_entry_rq(entry); | |
427 | ||
33659ebb CH |
428 | if ((rq->cmd_flags & REQ_DISCARD) != |
429 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 430 | break; |
783660b2 JA |
431 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
432 | break; | |
4eb166d9 | 433 | if (pos->cmd_flags & stop_flags) |
8922e16c | 434 | break; |
83096ebf TH |
435 | if (blk_rq_pos(rq) >= boundary) { |
436 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
437 | continue; |
438 | } else { | |
83096ebf | 439 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
440 | break; |
441 | } | |
83096ebf | 442 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
443 | break; |
444 | } | |
445 | ||
446 | list_add(&rq->queuelist, entry); | |
447 | } | |
2e662b65 JA |
448 | EXPORT_SYMBOL(elv_dispatch_sort); |
449 | ||
9817064b | 450 | /* |
2e662b65 JA |
451 | * Insert rq into dispatch queue of q. Queue lock must be held on |
452 | * entry. rq is added to the back of the dispatch queue. To be used by | |
453 | * specific elevators. | |
9817064b JA |
454 | */ |
455 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
456 | { | |
457 | if (q->last_merge == rq) | |
458 | q->last_merge = NULL; | |
459 | ||
460 | elv_rqhash_del(q, rq); | |
461 | ||
462 | q->nr_sorted--; | |
463 | ||
464 | q->end_sector = rq_end_sector(rq); | |
465 | q->boundary_rq = rq; | |
466 | list_add_tail(&rq->queuelist, &q->queue_head); | |
467 | } | |
2e662b65 JA |
468 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
469 | ||
165125e1 | 470 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 471 | { |
b374d18a | 472 | struct elevator_queue *e = q->elevator; |
9817064b | 473 | struct request *__rq; |
06b86245 TH |
474 | int ret; |
475 | ||
488991e2 AB |
476 | /* |
477 | * Levels of merges: | |
478 | * nomerges: No merges at all attempted | |
479 | * noxmerges: Only simple one-hit cache try | |
480 | * merges: All merge tries attempted | |
481 | */ | |
482 | if (blk_queue_nomerges(q)) | |
483 | return ELEVATOR_NO_MERGE; | |
484 | ||
9817064b JA |
485 | /* |
486 | * First try one-hit cache. | |
487 | */ | |
06b86245 TH |
488 | if (q->last_merge) { |
489 | ret = elv_try_merge(q->last_merge, bio); | |
490 | if (ret != ELEVATOR_NO_MERGE) { | |
491 | *req = q->last_merge; | |
492 | return ret; | |
493 | } | |
494 | } | |
1da177e4 | 495 | |
488991e2 | 496 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
497 | return ELEVATOR_NO_MERGE; |
498 | ||
9817064b JA |
499 | /* |
500 | * See if our hash lookup can find a potential backmerge. | |
501 | */ | |
502 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
503 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
504 | *req = __rq; | |
505 | return ELEVATOR_BACK_MERGE; | |
506 | } | |
507 | ||
1da177e4 LT |
508 | if (e->ops->elevator_merge_fn) |
509 | return e->ops->elevator_merge_fn(q, req, bio); | |
510 | ||
511 | return ELEVATOR_NO_MERGE; | |
512 | } | |
513 | ||
5e84ea3a JA |
514 | /* |
515 | * Attempt to do an insertion back merge. Only check for the case where | |
516 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
517 | * afterwards. | |
518 | * | |
519 | * Returns true if we merged, false otherwise | |
520 | */ | |
521 | static bool elv_attempt_insert_merge(struct request_queue *q, | |
522 | struct request *rq) | |
523 | { | |
524 | struct request *__rq; | |
525 | ||
526 | if (blk_queue_nomerges(q)) | |
527 | return false; | |
528 | ||
529 | /* | |
530 | * First try one-hit cache. | |
531 | */ | |
532 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
533 | return true; | |
534 | ||
535 | if (blk_queue_noxmerges(q)) | |
536 | return false; | |
537 | ||
538 | /* | |
539 | * See if our hash lookup can find a potential backmerge. | |
540 | */ | |
541 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
542 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) | |
543 | return true; | |
544 | ||
545 | return false; | |
546 | } | |
547 | ||
165125e1 | 548 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 549 | { |
b374d18a | 550 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
551 | |
552 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 553 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 554 | |
2e662b65 JA |
555 | if (type == ELEVATOR_BACK_MERGE) |
556 | elv_rqhash_reposition(q, rq); | |
9817064b | 557 | |
06b86245 | 558 | q->last_merge = rq; |
1da177e4 LT |
559 | } |
560 | ||
165125e1 | 561 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
562 | struct request *next) |
563 | { | |
b374d18a | 564 | struct elevator_queue *e = q->elevator; |
5e84ea3a | 565 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
1da177e4 | 566 | |
5e84ea3a | 567 | if (next_sorted && e->ops->elevator_merge_req_fn) |
1da177e4 | 568 | e->ops->elevator_merge_req_fn(q, rq, next); |
06b86245 | 569 | |
9817064b | 570 | elv_rqhash_reposition(q, rq); |
9817064b | 571 | |
5e84ea3a JA |
572 | if (next_sorted) { |
573 | elv_rqhash_del(q, next); | |
574 | q->nr_sorted--; | |
575 | } | |
576 | ||
06b86245 | 577 | q->last_merge = rq; |
1da177e4 LT |
578 | } |
579 | ||
812d4026 DS |
580 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
581 | struct bio *bio) | |
582 | { | |
583 | struct elevator_queue *e = q->elevator; | |
584 | ||
585 | if (e->ops->elevator_bio_merged_fn) | |
586 | e->ops->elevator_bio_merged_fn(q, rq, bio); | |
587 | } | |
588 | ||
165125e1 | 589 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 590 | { |
1da177e4 LT |
591 | /* |
592 | * it already went through dequeue, we need to decrement the | |
593 | * in_flight count again | |
594 | */ | |
8922e16c | 595 | if (blk_account_rq(rq)) { |
0a7ae2ff | 596 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 597 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 598 | elv_deactivate_rq(q, rq); |
8922e16c | 599 | } |
1da177e4 | 600 | |
4aff5e23 | 601 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 602 | |
b710a480 | 603 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
604 | } |
605 | ||
26308eab | 606 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
607 | { |
608 | static int printed; | |
609 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
610 | ; | |
611 | if (q->nr_sorted == 0) | |
612 | return; | |
613 | if (printed++ < 10) { | |
614 | printk(KERN_ERR "%s: forced dispatching is broken " | |
615 | "(nr_sorted=%u), please report this\n", | |
616 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
617 | } | |
618 | } | |
619 | ||
6c7e8cee JA |
620 | /* |
621 | * Call with queue lock held, interrupts disabled | |
622 | */ | |
f600abe2 | 623 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 624 | { |
cd43e26f MP |
625 | if (!q->elevator) |
626 | return; | |
627 | ||
6c7e8cee JA |
628 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
629 | ||
630 | /* | |
631 | * make sure we don't have any requests in flight | |
632 | */ | |
633 | elv_drain_elevator(q); | |
634 | while (q->rq.elvpriv) { | |
24ecfbe2 | 635 | __blk_run_queue(q); |
6c7e8cee JA |
636 | spin_unlock_irq(q->queue_lock); |
637 | msleep(10); | |
638 | spin_lock_irq(q->queue_lock); | |
639 | elv_drain_elevator(q); | |
640 | } | |
641 | } | |
642 | ||
f600abe2 | 643 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
644 | { |
645 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
646 | } | |
647 | ||
b710a480 | 648 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 649 | { |
5f3ea37c | 650 | trace_block_rq_insert(q, rq); |
2056a782 | 651 | |
1da177e4 LT |
652 | rq->q = q; |
653 | ||
b710a480 JA |
654 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
655 | /* barriers are scheduling boundary, update end_sector */ | |
656 | if (rq->cmd_type == REQ_TYPE_FS || | |
657 | (rq->cmd_flags & REQ_DISCARD)) { | |
658 | q->end_sector = rq_end_sector(rq); | |
659 | q->boundary_rq = rq; | |
660 | } | |
661 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && | |
3aa72873 JA |
662 | (where == ELEVATOR_INSERT_SORT || |
663 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
664 | where = ELEVATOR_INSERT_BACK; |
665 | ||
8922e16c | 666 | switch (where) { |
28e7d184 | 667 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 668 | case ELEVATOR_INSERT_FRONT: |
4aff5e23 | 669 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
670 | list_add(&rq->queuelist, &q->queue_head); |
671 | break; | |
672 | ||
673 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 674 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 675 | elv_drain_elevator(q); |
8922e16c TH |
676 | list_add_tail(&rq->queuelist, &q->queue_head); |
677 | /* | |
678 | * We kick the queue here for the following reasons. | |
679 | * - The elevator might have returned NULL previously | |
680 | * to delay requests and returned them now. As the | |
681 | * queue wasn't empty before this request, ll_rw_blk | |
682 | * won't run the queue on return, resulting in hang. | |
683 | * - Usually, back inserted requests won't be merged | |
684 | * with anything. There's no point in delaying queue | |
685 | * processing. | |
686 | */ | |
24ecfbe2 | 687 | __blk_run_queue(q); |
8922e16c TH |
688 | break; |
689 | ||
5e84ea3a JA |
690 | case ELEVATOR_INSERT_SORT_MERGE: |
691 | /* | |
692 | * If we succeed in merging this request with one in the | |
693 | * queue already, we are done - rq has now been freed, | |
694 | * so no need to do anything further. | |
695 | */ | |
696 | if (elv_attempt_insert_merge(q, rq)) | |
697 | break; | |
8922e16c | 698 | case ELEVATOR_INSERT_SORT: |
33659ebb CH |
699 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
700 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 701 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 702 | q->nr_sorted++; |
9817064b JA |
703 | if (rq_mergeable(rq)) { |
704 | elv_rqhash_add(q, rq); | |
705 | if (!q->last_merge) | |
706 | q->last_merge = rq; | |
707 | } | |
708 | ||
ca23509f TH |
709 | /* |
710 | * Some ioscheds (cfq) run q->request_fn directly, so | |
711 | * rq cannot be accessed after calling | |
712 | * elevator_add_req_fn. | |
713 | */ | |
714 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
715 | break; |
716 | ||
ae1b1539 TH |
717 | case ELEVATOR_INSERT_FLUSH: |
718 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
719 | blk_insert_flush(rq); | |
720 | break; | |
8922e16c TH |
721 | default: |
722 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 723 | __func__, where); |
8922e16c TH |
724 | BUG(); |
725 | } | |
1da177e4 | 726 | } |
2e662b65 JA |
727 | EXPORT_SYMBOL(__elv_add_request); |
728 | ||
7eaceacc | 729 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
730 | { |
731 | unsigned long flags; | |
732 | ||
733 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 734 | __elv_add_request(q, rq, where); |
1da177e4 LT |
735 | spin_unlock_irqrestore(q->queue_lock, flags); |
736 | } | |
2e662b65 JA |
737 | EXPORT_SYMBOL(elv_add_request); |
738 | ||
165125e1 | 739 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 740 | { |
b374d18a | 741 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
742 | |
743 | if (e->ops->elevator_latter_req_fn) | |
744 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
745 | return NULL; |
746 | } | |
747 | ||
165125e1 | 748 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 749 | { |
b374d18a | 750 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
751 | |
752 | if (e->ops->elevator_former_req_fn) | |
753 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
754 | return NULL; |
755 | } | |
756 | ||
165125e1 | 757 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 758 | { |
b374d18a | 759 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
760 | |
761 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 762 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 | 763 | |
c186794d | 764 | rq->elevator_private[0] = NULL; |
1da177e4 LT |
765 | return 0; |
766 | } | |
767 | ||
165125e1 | 768 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 769 | { |
b374d18a | 770 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
771 | |
772 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 773 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
774 | } |
775 | ||
165125e1 | 776 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 777 | { |
b374d18a | 778 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
779 | |
780 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 781 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
782 | |
783 | return ELV_MQUEUE_MAY; | |
784 | } | |
785 | ||
11914a53 MA |
786 | void elv_abort_queue(struct request_queue *q) |
787 | { | |
788 | struct request *rq; | |
789 | ||
ae1b1539 TH |
790 | blk_abort_flushes(q); |
791 | ||
11914a53 MA |
792 | while (!list_empty(&q->queue_head)) { |
793 | rq = list_entry_rq(q->queue_head.next); | |
794 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 795 | trace_block_rq_abort(q, rq); |
53c663ce KU |
796 | /* |
797 | * Mark this request as started so we don't trigger | |
798 | * any debug logic in the end I/O path. | |
799 | */ | |
800 | blk_start_request(rq); | |
40cbbb78 | 801 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
802 | } |
803 | } | |
804 | EXPORT_SYMBOL(elv_abort_queue); | |
805 | ||
165125e1 | 806 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 807 | { |
b374d18a | 808 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
809 | |
810 | /* | |
811 | * request is released from the driver, io must be done | |
812 | */ | |
8922e16c | 813 | if (blk_account_rq(rq)) { |
0a7ae2ff | 814 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb CH |
815 | if ((rq->cmd_flags & REQ_SORTED) && |
816 | e->ops->elevator_completed_req_fn) | |
1bc691d3 TH |
817 | e->ops->elevator_completed_req_fn(q, rq); |
818 | } | |
1da177e4 LT |
819 | } |
820 | ||
3d1ab40f AV |
821 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
822 | ||
823 | static ssize_t | |
824 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 825 | { |
3d1ab40f | 826 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 827 | struct elevator_queue *e; |
3d1ab40f AV |
828 | ssize_t error; |
829 | ||
830 | if (!entry->show) | |
831 | return -EIO; | |
832 | ||
b374d18a | 833 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
834 | mutex_lock(&e->sysfs_lock); |
835 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
836 | mutex_unlock(&e->sysfs_lock); | |
837 | return error; | |
838 | } | |
1da177e4 | 839 | |
3d1ab40f AV |
840 | static ssize_t |
841 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
842 | const char *page, size_t length) | |
843 | { | |
3d1ab40f | 844 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 845 | struct elevator_queue *e; |
3d1ab40f | 846 | ssize_t error; |
1da177e4 | 847 | |
3d1ab40f AV |
848 | if (!entry->store) |
849 | return -EIO; | |
1da177e4 | 850 | |
b374d18a | 851 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
852 | mutex_lock(&e->sysfs_lock); |
853 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
854 | mutex_unlock(&e->sysfs_lock); | |
855 | return error; | |
856 | } | |
857 | ||
52cf25d0 | 858 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
859 | .show = elv_attr_show, |
860 | .store = elv_attr_store, | |
861 | }; | |
862 | ||
863 | static struct kobj_type elv_ktype = { | |
864 | .sysfs_ops = &elv_sysfs_ops, | |
865 | .release = elevator_release, | |
866 | }; | |
867 | ||
868 | int elv_register_queue(struct request_queue *q) | |
869 | { | |
b374d18a | 870 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
871 | int error; |
872 | ||
b2d6db58 | 873 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 874 | if (!error) { |
e572ec7e | 875 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 876 | if (attr) { |
e572ec7e AV |
877 | while (attr->attr.name) { |
878 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 879 | break; |
e572ec7e | 880 | attr++; |
3d1ab40f AV |
881 | } |
882 | } | |
883 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 884 | e->registered = 1; |
3d1ab40f AV |
885 | } |
886 | return error; | |
1da177e4 | 887 | } |
01effb0d | 888 | EXPORT_SYMBOL(elv_register_queue); |
1da177e4 | 889 | |
b374d18a | 890 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
891 | { |
892 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
893 | kobject_del(&e->kobj); | |
430c62fb | 894 | e->registered = 0; |
bc1c1169 JA |
895 | } |
896 | ||
1da177e4 LT |
897 | void elv_unregister_queue(struct request_queue *q) |
898 | { | |
bc1c1169 JA |
899 | if (q) |
900 | __elv_unregister_queue(q->elevator); | |
1da177e4 | 901 | } |
01effb0d | 902 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 903 | |
2fdd82bd | 904 | void elv_register(struct elevator_type *e) |
1da177e4 | 905 | { |
1ffb96c5 | 906 | char *def = ""; |
2a12dcd7 JA |
907 | |
908 | spin_lock(&elv_list_lock); | |
ce524497 | 909 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 910 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 911 | spin_unlock(&elv_list_lock); |
1da177e4 | 912 | |
5f003976 ND |
913 | if (!strcmp(e->elevator_name, chosen_elevator) || |
914 | (!*chosen_elevator && | |
915 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
916 | def = " (default)"; |
917 | ||
4eb166d9 JA |
918 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
919 | def); | |
1da177e4 LT |
920 | } |
921 | EXPORT_SYMBOL_GPL(elv_register); | |
922 | ||
923 | void elv_unregister(struct elevator_type *e) | |
924 | { | |
83521d3e CH |
925 | struct task_struct *g, *p; |
926 | ||
927 | /* | |
928 | * Iterate every thread in the process to remove the io contexts. | |
929 | */ | |
e17a9489 AV |
930 | if (e->ops.trim) { |
931 | read_lock(&tasklist_lock); | |
932 | do_each_thread(g, p) { | |
933 | task_lock(p); | |
2d8f6131 ON |
934 | if (p->io_context) |
935 | e->ops.trim(p->io_context); | |
e17a9489 AV |
936 | task_unlock(p); |
937 | } while_each_thread(g, p); | |
938 | read_unlock(&tasklist_lock); | |
939 | } | |
83521d3e | 940 | |
2a12dcd7 | 941 | spin_lock(&elv_list_lock); |
1da177e4 | 942 | list_del_init(&e->list); |
2a12dcd7 | 943 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
944 | } |
945 | EXPORT_SYMBOL_GPL(elv_unregister); | |
946 | ||
947 | /* | |
948 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
949 | * we don't free the old io scheduler, before we have allocated what we | |
950 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 951 | * one, if the new one fails init for some reason. |
1da177e4 | 952 | */ |
165125e1 | 953 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 954 | { |
b374d18a | 955 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 956 | void *data; |
5dd531a0 | 957 | int err; |
1da177e4 | 958 | |
cb98fc8b TH |
959 | /* |
960 | * Allocate new elevator | |
961 | */ | |
b5deef90 | 962 | e = elevator_alloc(q, new_e); |
1da177e4 | 963 | if (!e) |
5dd531a0 | 964 | return -ENOMEM; |
1da177e4 | 965 | |
bc1c1169 JA |
966 | data = elevator_init_queue(q, e); |
967 | if (!data) { | |
968 | kobject_put(&e->kobj); | |
5dd531a0 | 969 | return -ENOMEM; |
bc1c1169 JA |
970 | } |
971 | ||
1da177e4 | 972 | /* |
cb98fc8b | 973 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 974 | */ |
cb98fc8b | 975 | spin_lock_irq(q->queue_lock); |
f600abe2 | 976 | elv_quiesce_start(q); |
cb98fc8b | 977 | |
1da177e4 | 978 | /* |
bc1c1169 | 979 | * Remember old elevator. |
1da177e4 | 980 | */ |
1da177e4 LT |
981 | old_elevator = q->elevator; |
982 | ||
1da177e4 LT |
983 | /* |
984 | * attach and start new elevator | |
985 | */ | |
bc1c1169 JA |
986 | elevator_attach(q, e, data); |
987 | ||
988 | spin_unlock_irq(q->queue_lock); | |
989 | ||
430c62fb JA |
990 | if (old_elevator->registered) { |
991 | __elv_unregister_queue(old_elevator); | |
1da177e4 | 992 | |
430c62fb JA |
993 | err = elv_register_queue(q); |
994 | if (err) | |
995 | goto fail_register; | |
996 | } | |
1da177e4 LT |
997 | |
998 | /* | |
cb98fc8b | 999 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1000 | */ |
1001 | elevator_exit(old_elevator); | |
75ad23bc | 1002 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1003 | elv_quiesce_end(q); |
75ad23bc NP |
1004 | spin_unlock_irq(q->queue_lock); |
1005 | ||
4722dc52 AB |
1006 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1007 | ||
5dd531a0 | 1008 | return 0; |
1da177e4 LT |
1009 | |
1010 | fail_register: | |
1011 | /* | |
1012 | * switch failed, exit the new io scheduler and reattach the old | |
1013 | * one again (along with re-adding the sysfs dir) | |
1014 | */ | |
1015 | elevator_exit(e); | |
1da177e4 LT |
1016 | q->elevator = old_elevator; |
1017 | elv_register_queue(q); | |
75ad23bc NP |
1018 | |
1019 | spin_lock_irq(q->queue_lock); | |
1020 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1021 | spin_unlock_irq(q->queue_lock); | |
1022 | ||
5dd531a0 | 1023 | return err; |
1da177e4 LT |
1024 | } |
1025 | ||
5dd531a0 JA |
1026 | /* |
1027 | * Switch this queue to the given IO scheduler. | |
1028 | */ | |
1029 | int elevator_change(struct request_queue *q, const char *name) | |
1da177e4 LT |
1030 | { |
1031 | char elevator_name[ELV_NAME_MAX]; | |
1032 | struct elevator_type *e; | |
1033 | ||
cd43e26f | 1034 | if (!q->elevator) |
5dd531a0 | 1035 | return -ENXIO; |
cd43e26f | 1036 | |
ee2e992c | 1037 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 1038 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
1039 | if (!e) { |
1040 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1041 | return -EINVAL; | |
1042 | } | |
1043 | ||
2ca7d93b ND |
1044 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1045 | elevator_put(e); | |
5dd531a0 | 1046 | return 0; |
2ca7d93b | 1047 | } |
1da177e4 | 1048 | |
5dd531a0 JA |
1049 | return elevator_switch(q, e); |
1050 | } | |
1051 | EXPORT_SYMBOL(elevator_change); | |
1052 | ||
1053 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
1054 | size_t count) | |
1055 | { | |
1056 | int ret; | |
1057 | ||
1058 | if (!q->elevator) | |
1059 | return count; | |
1060 | ||
1061 | ret = elevator_change(q, name); | |
1062 | if (!ret) | |
1063 | return count; | |
1064 | ||
1065 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
1066 | return ret; | |
1da177e4 LT |
1067 | } |
1068 | ||
165125e1 | 1069 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1070 | { |
b374d18a | 1071 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1072 | struct elevator_type *elv; |
70cee26e | 1073 | struct elevator_type *__e; |
1da177e4 LT |
1074 | int len = 0; |
1075 | ||
e36f724b | 1076 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1077 | return sprintf(name, "none\n"); |
1078 | ||
1079 | elv = e->elevator_type; | |
1080 | ||
2a12dcd7 | 1081 | spin_lock(&elv_list_lock); |
70cee26e | 1082 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1083 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1084 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1085 | else | |
1086 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1087 | } | |
2a12dcd7 | 1088 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1089 | |
1090 | len += sprintf(len+name, "\n"); | |
1091 | return len; | |
1092 | } | |
1093 | ||
165125e1 JA |
1094 | struct request *elv_rb_former_request(struct request_queue *q, |
1095 | struct request *rq) | |
2e662b65 JA |
1096 | { |
1097 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1098 | ||
1099 | if (rbprev) | |
1100 | return rb_entry_rq(rbprev); | |
1101 | ||
1102 | return NULL; | |
1103 | } | |
2e662b65 JA |
1104 | EXPORT_SYMBOL(elv_rb_former_request); |
1105 | ||
165125e1 JA |
1106 | struct request *elv_rb_latter_request(struct request_queue *q, |
1107 | struct request *rq) | |
2e662b65 JA |
1108 | { |
1109 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1110 | ||
1111 | if (rbnext) | |
1112 | return rb_entry_rq(rbnext); | |
1113 | ||
1114 | return NULL; | |
1115 | } | |
2e662b65 | 1116 | EXPORT_SYMBOL(elv_rb_latter_request); |