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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
29 | #include <linux/bio.h> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
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 | */ | |
82 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
83 | return 0; | |
84 | ||
1da177e4 LT |
85 | /* |
86 | * different data direction or already started, don't merge | |
87 | */ | |
88 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
89 | return 0; | |
90 | ||
91 | /* | |
da775265 | 92 | * must be same device and not a special request |
1da177e4 | 93 | */ |
bb4067e3 | 94 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
95 | return 0; |
96 | ||
7ba1ba12 MP |
97 | /* |
98 | * only merge integrity protected bio into ditto rq | |
99 | */ | |
100 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
101 | return 0; | |
102 | ||
da775265 JA |
103 | if (!elv_iosched_allow_merge(rq, bio)) |
104 | return 0; | |
1da177e4 | 105 | |
da775265 | 106 | return 1; |
1da177e4 LT |
107 | } |
108 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
109 | ||
769db45b | 110 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
111 | { |
112 | int ret = ELEVATOR_NO_MERGE; | |
113 | ||
114 | /* | |
115 | * we can merge and sequence is ok, check if it's possible | |
116 | */ | |
117 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 118 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 119 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 120 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
121 | ret = ELEVATOR_FRONT_MERGE; |
122 | } | |
123 | ||
124 | return ret; | |
125 | } | |
1da177e4 | 126 | |
1da177e4 LT |
127 | static struct elevator_type *elevator_find(const char *name) |
128 | { | |
a22b169d | 129 | struct elevator_type *e; |
1da177e4 | 130 | |
70cee26e | 131 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
132 | if (!strcmp(e->elevator_name, name)) |
133 | return e; | |
1da177e4 | 134 | } |
1da177e4 | 135 | |
a22b169d | 136 | return NULL; |
1da177e4 LT |
137 | } |
138 | ||
139 | static void elevator_put(struct elevator_type *e) | |
140 | { | |
141 | module_put(e->elevator_owner); | |
142 | } | |
143 | ||
144 | static struct elevator_type *elevator_get(const char *name) | |
145 | { | |
2824bc93 | 146 | struct elevator_type *e; |
1da177e4 | 147 | |
2a12dcd7 | 148 | spin_lock(&elv_list_lock); |
2824bc93 TH |
149 | |
150 | e = elevator_find(name); | |
e1640949 JA |
151 | if (!e) { |
152 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
153 | ||
154 | spin_unlock(&elv_list_lock); | |
155 | ||
156 | if (!strcmp(name, "anticipatory")) | |
157 | sprintf(elv, "as-iosched"); | |
158 | else | |
159 | sprintf(elv, "%s-iosched", name); | |
160 | ||
e180f594 | 161 | request_module("%s", elv); |
e1640949 JA |
162 | spin_lock(&elv_list_lock); |
163 | e = elevator_find(name); | |
164 | } | |
165 | ||
2824bc93 TH |
166 | if (e && !try_module_get(e->elevator_owner)) |
167 | e = NULL; | |
168 | ||
2a12dcd7 | 169 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
170 | |
171 | return e; | |
172 | } | |
173 | ||
165125e1 JA |
174 | static void *elevator_init_queue(struct request_queue *q, |
175 | struct elevator_queue *eq) | |
1da177e4 | 176 | { |
bb37b94c | 177 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 178 | } |
1da177e4 | 179 | |
165125e1 | 180 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
181 | void *data) |
182 | { | |
1da177e4 | 183 | q->elevator = eq; |
bc1c1169 | 184 | eq->elevator_data = data; |
1da177e4 LT |
185 | } |
186 | ||
187 | static char chosen_elevator[16]; | |
188 | ||
5f003976 | 189 | static int __init elevator_setup(char *str) |
1da177e4 | 190 | { |
752a3b79 CE |
191 | /* |
192 | * Be backwards-compatible with previous kernels, so users | |
193 | * won't get the wrong elevator. | |
194 | */ | |
5f003976 | 195 | if (!strcmp(str, "as")) |
752a3b79 | 196 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 197 | else |
5f003976 | 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; | |
250 | int ret = 0; | |
bc1c1169 | 251 | void *data; |
1da177e4 | 252 | |
cb98fc8b TH |
253 | INIT_LIST_HEAD(&q->queue_head); |
254 | q->last_merge = NULL; | |
255 | q->end_sector = 0; | |
256 | q->boundary_rq = NULL; | |
cb98fc8b | 257 | |
4eb166d9 JA |
258 | if (name) { |
259 | e = elevator_get(name); | |
260 | if (!e) | |
261 | return -EINVAL; | |
262 | } | |
1da177e4 | 263 | |
4eb166d9 JA |
264 | if (!e && *chosen_elevator) { |
265 | e = elevator_get(chosen_elevator); | |
266 | if (!e) | |
267 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
268 | chosen_elevator); | |
269 | } | |
248d5ca5 | 270 | |
4eb166d9 JA |
271 | if (!e) { |
272 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
273 | if (!e) { | |
274 | printk(KERN_ERR | |
275 | "Default I/O scheduler not found. " \ | |
276 | "Using noop.\n"); | |
277 | e = elevator_get("noop"); | |
278 | } | |
5f003976 ND |
279 | } |
280 | ||
b5deef90 | 281 | eq = elevator_alloc(q, e); |
3d1ab40f | 282 | if (!eq) |
1da177e4 | 283 | return -ENOMEM; |
1da177e4 | 284 | |
bc1c1169 JA |
285 | data = elevator_init_queue(q, eq); |
286 | if (!data) { | |
3d1ab40f | 287 | kobject_put(&eq->kobj); |
bc1c1169 JA |
288 | return -ENOMEM; |
289 | } | |
1da177e4 | 290 | |
bc1c1169 | 291 | elevator_attach(q, eq, data); |
1da177e4 LT |
292 | return ret; |
293 | } | |
2e662b65 JA |
294 | EXPORT_SYMBOL(elevator_init); |
295 | ||
b374d18a | 296 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 297 | { |
3d1ab40f | 298 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
299 | if (e->ops->elevator_exit_fn) |
300 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
301 | e->ops = NULL; |
302 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 303 | |
3d1ab40f | 304 | kobject_put(&e->kobj); |
1da177e4 | 305 | } |
2e662b65 JA |
306 | EXPORT_SYMBOL(elevator_exit); |
307 | ||
9817064b JA |
308 | static inline void __elv_rqhash_del(struct request *rq) |
309 | { | |
310 | hlist_del_init(&rq->hash); | |
311 | } | |
312 | ||
165125e1 | 313 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
314 | { |
315 | if (ELV_ON_HASH(rq)) | |
316 | __elv_rqhash_del(rq); | |
317 | } | |
318 | ||
165125e1 | 319 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 320 | { |
b374d18a | 321 | struct elevator_queue *e = q->elevator; |
9817064b JA |
322 | |
323 | BUG_ON(ELV_ON_HASH(rq)); | |
324 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
325 | } | |
326 | ||
165125e1 | 327 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
328 | { |
329 | __elv_rqhash_del(rq); | |
330 | elv_rqhash_add(q, rq); | |
331 | } | |
332 | ||
165125e1 | 333 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 334 | { |
b374d18a | 335 | struct elevator_queue *e = q->elevator; |
9817064b JA |
336 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
337 | struct hlist_node *entry, *next; | |
338 | struct request *rq; | |
339 | ||
340 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
341 | BUG_ON(!ELV_ON_HASH(rq)); | |
342 | ||
343 | if (unlikely(!rq_mergeable(rq))) { | |
344 | __elv_rqhash_del(rq); | |
345 | continue; | |
346 | } | |
347 | ||
348 | if (rq_hash_key(rq) == offset) | |
349 | return rq; | |
350 | } | |
351 | ||
352 | return NULL; | |
353 | } | |
354 | ||
2e662b65 JA |
355 | /* |
356 | * RB-tree support functions for inserting/lookup/removal of requests | |
357 | * in a sorted RB tree. | |
358 | */ | |
359 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
360 | { | |
361 | struct rb_node **p = &root->rb_node; | |
362 | struct rb_node *parent = NULL; | |
363 | struct request *__rq; | |
364 | ||
365 | while (*p) { | |
366 | parent = *p; | |
367 | __rq = rb_entry(parent, struct request, rb_node); | |
368 | ||
83096ebf | 369 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 370 | p = &(*p)->rb_left; |
83096ebf | 371 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
372 | p = &(*p)->rb_right; |
373 | else | |
374 | return __rq; | |
375 | } | |
376 | ||
377 | rb_link_node(&rq->rb_node, parent, p); | |
378 | rb_insert_color(&rq->rb_node, root); | |
379 | return NULL; | |
380 | } | |
2e662b65 JA |
381 | EXPORT_SYMBOL(elv_rb_add); |
382 | ||
383 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
384 | { | |
385 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
386 | rb_erase(&rq->rb_node, root); | |
387 | RB_CLEAR_NODE(&rq->rb_node); | |
388 | } | |
2e662b65 JA |
389 | EXPORT_SYMBOL(elv_rb_del); |
390 | ||
391 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
392 | { | |
393 | struct rb_node *n = root->rb_node; | |
394 | struct request *rq; | |
395 | ||
396 | while (n) { | |
397 | rq = rb_entry(n, struct request, rb_node); | |
398 | ||
83096ebf | 399 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 400 | n = n->rb_left; |
83096ebf | 401 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
402 | n = n->rb_right; |
403 | else | |
404 | return rq; | |
405 | } | |
406 | ||
407 | return NULL; | |
408 | } | |
2e662b65 JA |
409 | EXPORT_SYMBOL(elv_rb_find); |
410 | ||
8922e16c TH |
411 | /* |
412 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 413 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 414 | * specific elevators. |
8922e16c | 415 | */ |
165125e1 | 416 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
417 | { |
418 | sector_t boundary; | |
8922e16c | 419 | struct list_head *entry; |
4eb166d9 | 420 | int stop_flags; |
8922e16c | 421 | |
06b86245 TH |
422 | if (q->last_merge == rq) |
423 | q->last_merge = NULL; | |
9817064b JA |
424 | |
425 | elv_rqhash_del(q, rq); | |
426 | ||
15853af9 | 427 | q->nr_sorted--; |
06b86245 | 428 | |
1b47f531 | 429 | boundary = q->end_sector; |
4eb166d9 | 430 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
431 | list_for_each_prev(entry, &q->queue_head) { |
432 | struct request *pos = list_entry_rq(entry); | |
433 | ||
e17fc0a1 DW |
434 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
435 | break; | |
783660b2 JA |
436 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
437 | break; | |
4eb166d9 | 438 | if (pos->cmd_flags & stop_flags) |
8922e16c | 439 | break; |
83096ebf TH |
440 | if (blk_rq_pos(rq) >= boundary) { |
441 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
442 | continue; |
443 | } else { | |
83096ebf | 444 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
445 | break; |
446 | } | |
83096ebf | 447 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
448 | break; |
449 | } | |
450 | ||
451 | list_add(&rq->queuelist, entry); | |
452 | } | |
2e662b65 JA |
453 | EXPORT_SYMBOL(elv_dispatch_sort); |
454 | ||
9817064b | 455 | /* |
2e662b65 JA |
456 | * Insert rq into dispatch queue of q. Queue lock must be held on |
457 | * entry. rq is added to the back of the dispatch queue. To be used by | |
458 | * specific elevators. | |
9817064b JA |
459 | */ |
460 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
461 | { | |
462 | if (q->last_merge == rq) | |
463 | q->last_merge = NULL; | |
464 | ||
465 | elv_rqhash_del(q, rq); | |
466 | ||
467 | q->nr_sorted--; | |
468 | ||
469 | q->end_sector = rq_end_sector(rq); | |
470 | q->boundary_rq = rq; | |
471 | list_add_tail(&rq->queuelist, &q->queue_head); | |
472 | } | |
2e662b65 JA |
473 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
474 | ||
165125e1 | 475 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 476 | { |
b374d18a | 477 | struct elevator_queue *e = q->elevator; |
9817064b | 478 | struct request *__rq; |
06b86245 TH |
479 | int ret; |
480 | ||
9817064b JA |
481 | /* |
482 | * First try one-hit cache. | |
483 | */ | |
06b86245 TH |
484 | if (q->last_merge) { |
485 | ret = elv_try_merge(q->last_merge, bio); | |
486 | if (ret != ELEVATOR_NO_MERGE) { | |
487 | *req = q->last_merge; | |
488 | return ret; | |
489 | } | |
490 | } | |
1da177e4 | 491 | |
ac9fafa1 AB |
492 | if (blk_queue_nomerges(q)) |
493 | return ELEVATOR_NO_MERGE; | |
494 | ||
9817064b JA |
495 | /* |
496 | * See if our hash lookup can find a potential backmerge. | |
497 | */ | |
498 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
499 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
500 | *req = __rq; | |
501 | return ELEVATOR_BACK_MERGE; | |
502 | } | |
503 | ||
1da177e4 LT |
504 | if (e->ops->elevator_merge_fn) |
505 | return e->ops->elevator_merge_fn(q, req, bio); | |
506 | ||
507 | return ELEVATOR_NO_MERGE; | |
508 | } | |
509 | ||
165125e1 | 510 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 511 | { |
b374d18a | 512 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
513 | |
514 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 515 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 516 | |
2e662b65 JA |
517 | if (type == ELEVATOR_BACK_MERGE) |
518 | elv_rqhash_reposition(q, rq); | |
9817064b | 519 | |
06b86245 | 520 | q->last_merge = rq; |
1da177e4 LT |
521 | } |
522 | ||
165125e1 | 523 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
524 | struct request *next) |
525 | { | |
b374d18a | 526 | struct elevator_queue *e = q->elevator; |
1da177e4 | 527 | |
1da177e4 LT |
528 | if (e->ops->elevator_merge_req_fn) |
529 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 530 | |
9817064b JA |
531 | elv_rqhash_reposition(q, rq); |
532 | elv_rqhash_del(q, next); | |
533 | ||
534 | q->nr_sorted--; | |
06b86245 | 535 | q->last_merge = rq; |
1da177e4 LT |
536 | } |
537 | ||
165125e1 | 538 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 539 | { |
1da177e4 LT |
540 | /* |
541 | * it already went through dequeue, we need to decrement the | |
542 | * in_flight count again | |
543 | */ | |
8922e16c | 544 | if (blk_account_rq(rq)) { |
0a7ae2ff | 545 | q->in_flight[rq_is_sync(rq)]--; |
cad97516 JA |
546 | if (blk_sorted_rq(rq)) |
547 | elv_deactivate_rq(q, rq); | |
8922e16c | 548 | } |
1da177e4 | 549 | |
4aff5e23 | 550 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 551 | |
30e9656c | 552 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
553 | } |
554 | ||
26308eab | 555 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
556 | { |
557 | static int printed; | |
558 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
559 | ; | |
560 | if (q->nr_sorted == 0) | |
561 | return; | |
562 | if (printed++ < 10) { | |
563 | printk(KERN_ERR "%s: forced dispatching is broken " | |
564 | "(nr_sorted=%u), please report this\n", | |
565 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
566 | } | |
567 | } | |
568 | ||
6c7e8cee JA |
569 | /* |
570 | * Call with queue lock held, interrupts disabled | |
571 | */ | |
f600abe2 | 572 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 573 | { |
cd43e26f MP |
574 | if (!q->elevator) |
575 | return; | |
576 | ||
6c7e8cee JA |
577 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
578 | ||
579 | /* | |
580 | * make sure we don't have any requests in flight | |
581 | */ | |
582 | elv_drain_elevator(q); | |
583 | while (q->rq.elvpriv) { | |
a7f55792 | 584 | __blk_run_queue(q); |
6c7e8cee JA |
585 | spin_unlock_irq(q->queue_lock); |
586 | msleep(10); | |
587 | spin_lock_irq(q->queue_lock); | |
588 | elv_drain_elevator(q); | |
589 | } | |
590 | } | |
591 | ||
f600abe2 | 592 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
593 | { |
594 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
595 | } | |
596 | ||
165125e1 | 597 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 598 | { |
797e7dbb TH |
599 | struct list_head *pos; |
600 | unsigned ordseq; | |
dac07ec1 | 601 | int unplug_it = 1; |
797e7dbb | 602 | |
5f3ea37c | 603 | trace_block_rq_insert(q, rq); |
2056a782 | 604 | |
1da177e4 LT |
605 | rq->q = q; |
606 | ||
8922e16c TH |
607 | switch (where) { |
608 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 609 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
610 | |
611 | list_add(&rq->queuelist, &q->queue_head); | |
612 | break; | |
613 | ||
614 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 615 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 616 | elv_drain_elevator(q); |
8922e16c TH |
617 | list_add_tail(&rq->queuelist, &q->queue_head); |
618 | /* | |
619 | * We kick the queue here for the following reasons. | |
620 | * - The elevator might have returned NULL previously | |
621 | * to delay requests and returned them now. As the | |
622 | * queue wasn't empty before this request, ll_rw_blk | |
623 | * won't run the queue on return, resulting in hang. | |
624 | * - Usually, back inserted requests won't be merged | |
625 | * with anything. There's no point in delaying queue | |
626 | * processing. | |
627 | */ | |
a7f55792 | 628 | __blk_run_queue(q); |
8922e16c TH |
629 | break; |
630 | ||
631 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 632 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 633 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 634 | q->nr_sorted++; |
9817064b JA |
635 | if (rq_mergeable(rq)) { |
636 | elv_rqhash_add(q, rq); | |
637 | if (!q->last_merge) | |
638 | q->last_merge = rq; | |
639 | } | |
640 | ||
ca23509f TH |
641 | /* |
642 | * Some ioscheds (cfq) run q->request_fn directly, so | |
643 | * rq cannot be accessed after calling | |
644 | * elevator_add_req_fn. | |
645 | */ | |
646 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
647 | break; |
648 | ||
797e7dbb TH |
649 | case ELEVATOR_INSERT_REQUEUE: |
650 | /* | |
651 | * If ordered flush isn't in progress, we do front | |
652 | * insertion; otherwise, requests should be requeued | |
653 | * in ordseq order. | |
654 | */ | |
4aff5e23 | 655 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 656 | |
95543179 LV |
657 | /* |
658 | * Most requeues happen because of a busy condition, | |
659 | * don't force unplug of the queue for that case. | |
660 | */ | |
661 | unplug_it = 0; | |
662 | ||
797e7dbb TH |
663 | if (q->ordseq == 0) { |
664 | list_add(&rq->queuelist, &q->queue_head); | |
665 | break; | |
666 | } | |
667 | ||
668 | ordseq = blk_ordered_req_seq(rq); | |
669 | ||
670 | list_for_each(pos, &q->queue_head) { | |
671 | struct request *pos_rq = list_entry_rq(pos); | |
672 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
673 | break; | |
674 | } | |
675 | ||
676 | list_add_tail(&rq->queuelist, pos); | |
677 | break; | |
678 | ||
8922e16c TH |
679 | default: |
680 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 681 | __func__, where); |
8922e16c TH |
682 | BUG(); |
683 | } | |
684 | ||
dac07ec1 | 685 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 686 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
0a7ae2ff | 687 | - queue_in_flight(q); |
8922e16c TH |
688 | |
689 | if (nrq >= q->unplug_thresh) | |
690 | __generic_unplug_device(q); | |
691 | } | |
1da177e4 LT |
692 | } |
693 | ||
165125e1 | 694 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
695 | int plug) |
696 | { | |
697 | if (q->ordcolor) | |
4aff5e23 | 698 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 699 | |
4aff5e23 | 700 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
701 | /* |
702 | * toggle ordered color | |
703 | */ | |
704 | if (blk_barrier_rq(rq)) | |
705 | q->ordcolor ^= 1; | |
706 | ||
707 | /* | |
708 | * barriers implicitly indicate back insertion | |
709 | */ | |
710 | if (where == ELEVATOR_INSERT_SORT) | |
711 | where = ELEVATOR_INSERT_BACK; | |
712 | ||
713 | /* | |
714 | * this request is scheduling boundary, update | |
715 | * end_sector | |
716 | */ | |
e17fc0a1 | 717 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
718 | q->end_sector = rq_end_sector(rq); |
719 | q->boundary_rq = rq; | |
720 | } | |
4eb166d9 JA |
721 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
722 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
723 | where = ELEVATOR_INSERT_BACK; |
724 | ||
725 | if (plug) | |
726 | blk_plug_device(q); | |
727 | ||
728 | elv_insert(q, rq, where); | |
729 | } | |
2e662b65 JA |
730 | EXPORT_SYMBOL(__elv_add_request); |
731 | ||
165125e1 | 732 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
733 | int plug) |
734 | { | |
735 | unsigned long flags; | |
736 | ||
737 | spin_lock_irqsave(q->queue_lock, flags); | |
738 | __elv_add_request(q, rq, where, plug); | |
739 | spin_unlock_irqrestore(q->queue_lock, flags); | |
740 | } | |
2e662b65 JA |
741 | EXPORT_SYMBOL(elv_add_request); |
742 | ||
165125e1 | 743 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 744 | { |
b374d18a | 745 | struct elevator_queue *e = q->elevator; |
1da177e4 | 746 | |
8922e16c TH |
747 | if (!list_empty(&q->queue_head)) |
748 | return 0; | |
749 | ||
1da177e4 LT |
750 | if (e->ops->elevator_queue_empty_fn) |
751 | return e->ops->elevator_queue_empty_fn(q); | |
752 | ||
8922e16c | 753 | return 1; |
1da177e4 | 754 | } |
2e662b65 JA |
755 | EXPORT_SYMBOL(elv_queue_empty); |
756 | ||
165125e1 | 757 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 758 | { |
b374d18a | 759 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
760 | |
761 | if (e->ops->elevator_latter_req_fn) | |
762 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
763 | return NULL; |
764 | } | |
765 | ||
165125e1 | 766 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 767 | { |
b374d18a | 768 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
769 | |
770 | if (e->ops->elevator_former_req_fn) | |
771 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
772 | return NULL; |
773 | } | |
774 | ||
165125e1 | 775 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 776 | { |
b374d18a | 777 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
778 | |
779 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 780 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
781 | |
782 | rq->elevator_private = NULL; | |
783 | return 0; | |
784 | } | |
785 | ||
165125e1 | 786 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 787 | { |
b374d18a | 788 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
789 | |
790 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 791 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
792 | } |
793 | ||
165125e1 | 794 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 795 | { |
b374d18a | 796 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
797 | |
798 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 799 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
800 | |
801 | return ELV_MQUEUE_MAY; | |
802 | } | |
803 | ||
11914a53 MA |
804 | void elv_abort_queue(struct request_queue *q) |
805 | { | |
806 | struct request *rq; | |
807 | ||
808 | while (!list_empty(&q->queue_head)) { | |
809 | rq = list_entry_rq(q->queue_head.next); | |
810 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 811 | trace_block_rq_abort(q, rq); |
53c663ce KU |
812 | /* |
813 | * Mark this request as started so we don't trigger | |
814 | * any debug logic in the end I/O path. | |
815 | */ | |
816 | blk_start_request(rq); | |
40cbbb78 | 817 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
818 | } |
819 | } | |
820 | EXPORT_SYMBOL(elv_abort_queue); | |
821 | ||
165125e1 | 822 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 823 | { |
b374d18a | 824 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
825 | |
826 | /* | |
827 | * request is released from the driver, io must be done | |
828 | */ | |
8922e16c | 829 | if (blk_account_rq(rq)) { |
0a7ae2ff | 830 | q->in_flight[rq_is_sync(rq)]--; |
1bc691d3 TH |
831 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
832 | e->ops->elevator_completed_req_fn(q, rq); | |
833 | } | |
797e7dbb | 834 | |
1bc691d3 TH |
835 | /* |
836 | * Check if the queue is waiting for fs requests to be | |
837 | * drained for flush sequence. | |
838 | */ | |
839 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
840 | struct request *next = NULL; |
841 | ||
842 | if (!list_empty(&q->queue_head)) | |
843 | next = list_entry_rq(q->queue_head.next); | |
844 | ||
0a7ae2ff | 845 | if (!queue_in_flight(q) && |
797e7dbb | 846 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 847 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 848 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
a7f55792 | 849 | __blk_run_queue(q); |
797e7dbb | 850 | } |
8922e16c | 851 | } |
1da177e4 LT |
852 | } |
853 | ||
3d1ab40f AV |
854 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
855 | ||
856 | static ssize_t | |
857 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 858 | { |
3d1ab40f | 859 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 860 | struct elevator_queue *e; |
3d1ab40f AV |
861 | ssize_t error; |
862 | ||
863 | if (!entry->show) | |
864 | return -EIO; | |
865 | ||
b374d18a | 866 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
867 | mutex_lock(&e->sysfs_lock); |
868 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
869 | mutex_unlock(&e->sysfs_lock); | |
870 | return error; | |
871 | } | |
1da177e4 | 872 | |
3d1ab40f AV |
873 | static ssize_t |
874 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
875 | const char *page, size_t length) | |
876 | { | |
3d1ab40f | 877 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 878 | struct elevator_queue *e; |
3d1ab40f | 879 | ssize_t error; |
1da177e4 | 880 | |
3d1ab40f AV |
881 | if (!entry->store) |
882 | return -EIO; | |
1da177e4 | 883 | |
b374d18a | 884 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
885 | mutex_lock(&e->sysfs_lock); |
886 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
887 | mutex_unlock(&e->sysfs_lock); | |
888 | return error; | |
889 | } | |
890 | ||
891 | static struct sysfs_ops elv_sysfs_ops = { | |
892 | .show = elv_attr_show, | |
893 | .store = elv_attr_store, | |
894 | }; | |
895 | ||
896 | static struct kobj_type elv_ktype = { | |
897 | .sysfs_ops = &elv_sysfs_ops, | |
898 | .release = elevator_release, | |
899 | }; | |
900 | ||
901 | int elv_register_queue(struct request_queue *q) | |
902 | { | |
b374d18a | 903 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
904 | int error; |
905 | ||
b2d6db58 | 906 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 907 | if (!error) { |
e572ec7e | 908 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 909 | if (attr) { |
e572ec7e AV |
910 | while (attr->attr.name) { |
911 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 912 | break; |
e572ec7e | 913 | attr++; |
3d1ab40f AV |
914 | } |
915 | } | |
916 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
917 | } | |
918 | return error; | |
1da177e4 LT |
919 | } |
920 | ||
b374d18a | 921 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
922 | { |
923 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
924 | kobject_del(&e->kobj); | |
925 | } | |
926 | ||
1da177e4 LT |
927 | void elv_unregister_queue(struct request_queue *q) |
928 | { | |
bc1c1169 JA |
929 | if (q) |
930 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
931 | } |
932 | ||
2fdd82bd | 933 | void elv_register(struct elevator_type *e) |
1da177e4 | 934 | { |
1ffb96c5 | 935 | char *def = ""; |
2a12dcd7 JA |
936 | |
937 | spin_lock(&elv_list_lock); | |
ce524497 | 938 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 939 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 940 | spin_unlock(&elv_list_lock); |
1da177e4 | 941 | |
5f003976 ND |
942 | if (!strcmp(e->elevator_name, chosen_elevator) || |
943 | (!*chosen_elevator && | |
944 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
945 | def = " (default)"; |
946 | ||
4eb166d9 JA |
947 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
948 | def); | |
1da177e4 LT |
949 | } |
950 | EXPORT_SYMBOL_GPL(elv_register); | |
951 | ||
952 | void elv_unregister(struct elevator_type *e) | |
953 | { | |
83521d3e CH |
954 | struct task_struct *g, *p; |
955 | ||
956 | /* | |
957 | * Iterate every thread in the process to remove the io contexts. | |
958 | */ | |
e17a9489 AV |
959 | if (e->ops.trim) { |
960 | read_lock(&tasklist_lock); | |
961 | do_each_thread(g, p) { | |
962 | task_lock(p); | |
2d8f6131 ON |
963 | if (p->io_context) |
964 | e->ops.trim(p->io_context); | |
e17a9489 AV |
965 | task_unlock(p); |
966 | } while_each_thread(g, p); | |
967 | read_unlock(&tasklist_lock); | |
968 | } | |
83521d3e | 969 | |
2a12dcd7 | 970 | spin_lock(&elv_list_lock); |
1da177e4 | 971 | list_del_init(&e->list); |
2a12dcd7 | 972 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
973 | } |
974 | EXPORT_SYMBOL_GPL(elv_unregister); | |
975 | ||
976 | /* | |
977 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
978 | * we don't free the old io scheduler, before we have allocated what we | |
979 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 980 | * one, if the new one fails init for some reason. |
1da177e4 | 981 | */ |
165125e1 | 982 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 983 | { |
b374d18a | 984 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 985 | void *data; |
1da177e4 | 986 | |
cb98fc8b TH |
987 | /* |
988 | * Allocate new elevator | |
989 | */ | |
b5deef90 | 990 | e = elevator_alloc(q, new_e); |
1da177e4 | 991 | if (!e) |
3d1ab40f | 992 | return 0; |
1da177e4 | 993 | |
bc1c1169 JA |
994 | data = elevator_init_queue(q, e); |
995 | if (!data) { | |
996 | kobject_put(&e->kobj); | |
997 | return 0; | |
998 | } | |
999 | ||
1da177e4 | 1000 | /* |
cb98fc8b | 1001 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1002 | */ |
cb98fc8b | 1003 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1004 | elv_quiesce_start(q); |
cb98fc8b | 1005 | |
1da177e4 | 1006 | /* |
bc1c1169 | 1007 | * Remember old elevator. |
1da177e4 | 1008 | */ |
1da177e4 LT |
1009 | old_elevator = q->elevator; |
1010 | ||
1da177e4 LT |
1011 | /* |
1012 | * attach and start new elevator | |
1013 | */ | |
bc1c1169 JA |
1014 | elevator_attach(q, e, data); |
1015 | ||
1016 | spin_unlock_irq(q->queue_lock); | |
1017 | ||
1018 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1019 | |
1020 | if (elv_register_queue(q)) | |
1021 | goto fail_register; | |
1022 | ||
1023 | /* | |
cb98fc8b | 1024 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1025 | */ |
1026 | elevator_exit(old_elevator); | |
75ad23bc | 1027 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1028 | elv_quiesce_end(q); |
75ad23bc NP |
1029 | spin_unlock_irq(q->queue_lock); |
1030 | ||
4722dc52 AB |
1031 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1032 | ||
3d1ab40f | 1033 | return 1; |
1da177e4 LT |
1034 | |
1035 | fail_register: | |
1036 | /* | |
1037 | * switch failed, exit the new io scheduler and reattach the old | |
1038 | * one again (along with re-adding the sysfs dir) | |
1039 | */ | |
1040 | elevator_exit(e); | |
1da177e4 LT |
1041 | q->elevator = old_elevator; |
1042 | elv_register_queue(q); | |
75ad23bc NP |
1043 | |
1044 | spin_lock_irq(q->queue_lock); | |
1045 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1046 | spin_unlock_irq(q->queue_lock); | |
1047 | ||
3d1ab40f | 1048 | return 0; |
1da177e4 LT |
1049 | } |
1050 | ||
165125e1 JA |
1051 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1052 | size_t count) | |
1da177e4 LT |
1053 | { |
1054 | char elevator_name[ELV_NAME_MAX]; | |
1055 | struct elevator_type *e; | |
1056 | ||
cd43e26f MP |
1057 | if (!q->elevator) |
1058 | return count; | |
1059 | ||
ee2e992c LZ |
1060 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1061 | strstrip(elevator_name); | |
1da177e4 LT |
1062 | |
1063 | e = elevator_get(elevator_name); | |
1064 | if (!e) { | |
1065 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1066 | return -EINVAL; | |
1067 | } | |
1068 | ||
2ca7d93b ND |
1069 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1070 | elevator_put(e); | |
1da177e4 | 1071 | return count; |
2ca7d93b | 1072 | } |
1da177e4 | 1073 | |
3d1ab40f | 1074 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1075 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1076 | elevator_name); | |
1da177e4 LT |
1077 | return count; |
1078 | } | |
1079 | ||
165125e1 | 1080 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1081 | { |
b374d18a | 1082 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1083 | struct elevator_type *elv; |
70cee26e | 1084 | struct elevator_type *__e; |
1da177e4 LT |
1085 | int len = 0; |
1086 | ||
cd43e26f MP |
1087 | if (!q->elevator) |
1088 | return sprintf(name, "none\n"); | |
1089 | ||
1090 | elv = e->elevator_type; | |
1091 | ||
2a12dcd7 | 1092 | spin_lock(&elv_list_lock); |
70cee26e | 1093 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1094 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1095 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1096 | else | |
1097 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1098 | } | |
2a12dcd7 | 1099 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1100 | |
1101 | len += sprintf(len+name, "\n"); | |
1102 | return len; | |
1103 | } | |
1104 | ||
165125e1 JA |
1105 | struct request *elv_rb_former_request(struct request_queue *q, |
1106 | struct request *rq) | |
2e662b65 JA |
1107 | { |
1108 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1109 | ||
1110 | if (rbprev) | |
1111 | return rb_entry_rq(rbprev); | |
1112 | ||
1113 | return NULL; | |
1114 | } | |
2e662b65 JA |
1115 | EXPORT_SYMBOL(elv_rb_former_request); |
1116 | ||
165125e1 JA |
1117 | struct request *elv_rb_latter_request(struct request_queue *q, |
1118 | struct request *rq) | |
2e662b65 JA |
1119 | { |
1120 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1121 | ||
1122 | if (rbnext) | |
1123 | return rb_entry_rq(rbnext); | |
1124 | ||
1125 | return NULL; | |
1126 | } | |
2e662b65 | 1127 | EXPORT_SYMBOL(elv_rb_latter_request); |