]>
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 | ||
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 | ||
a506aedc | 156 | snprintf(elv, sizeof(elv), "%s-iosched", name); |
e1640949 | 157 | |
e180f594 | 158 | request_module("%s", elv); |
e1640949 JA |
159 | spin_lock(&elv_list_lock); |
160 | e = elevator_find(name); | |
161 | } | |
162 | ||
2824bc93 TH |
163 | if (e && !try_module_get(e->elevator_owner)) |
164 | e = NULL; | |
165 | ||
2a12dcd7 | 166 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
167 | |
168 | return e; | |
169 | } | |
170 | ||
165125e1 JA |
171 | static void *elevator_init_queue(struct request_queue *q, |
172 | struct elevator_queue *eq) | |
1da177e4 | 173 | { |
bb37b94c | 174 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 175 | } |
1da177e4 | 176 | |
165125e1 | 177 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
178 | void *data) |
179 | { | |
1da177e4 | 180 | q->elevator = eq; |
bc1c1169 | 181 | eq->elevator_data = data; |
1da177e4 LT |
182 | } |
183 | ||
184 | static char chosen_elevator[16]; | |
185 | ||
5f003976 | 186 | static int __init elevator_setup(char *str) |
1da177e4 | 187 | { |
752a3b79 CE |
188 | /* |
189 | * Be backwards-compatible with previous kernels, so users | |
190 | * won't get the wrong elevator. | |
191 | */ | |
492af635 | 192 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 193 | return 1; |
1da177e4 LT |
194 | } |
195 | ||
196 | __setup("elevator=", elevator_setup); | |
197 | ||
3d1ab40f AV |
198 | static struct kobj_type elv_ktype; |
199 | ||
b374d18a | 200 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 201 | struct elevator_type *e) |
3d1ab40f | 202 | { |
b374d18a | 203 | struct elevator_queue *eq; |
9817064b JA |
204 | int i; |
205 | ||
b374d18a | 206 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
207 | if (unlikely(!eq)) |
208 | goto err; | |
209 | ||
9817064b JA |
210 | eq->ops = &e->ops; |
211 | eq->elevator_type = e; | |
f9cb074b | 212 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
213 | mutex_init(&eq->sysfs_lock); |
214 | ||
b5deef90 JA |
215 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
216 | GFP_KERNEL, q->node); | |
9817064b JA |
217 | if (!eq->hash) |
218 | goto err; | |
219 | ||
220 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
221 | INIT_HLIST_HEAD(&eq->hash[i]); | |
222 | ||
3d1ab40f | 223 | return eq; |
9817064b JA |
224 | err: |
225 | kfree(eq); | |
226 | elevator_put(e); | |
227 | return NULL; | |
3d1ab40f AV |
228 | } |
229 | ||
230 | static void elevator_release(struct kobject *kobj) | |
231 | { | |
b374d18a | 232 | struct elevator_queue *e; |
9817064b | 233 | |
b374d18a | 234 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 235 | elevator_put(e->elevator_type); |
9817064b | 236 | kfree(e->hash); |
3d1ab40f AV |
237 | kfree(e); |
238 | } | |
239 | ||
165125e1 | 240 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
241 | { |
242 | struct elevator_type *e = NULL; | |
243 | struct elevator_queue *eq; | |
bc1c1169 | 244 | void *data; |
1da177e4 | 245 | |
1abec4fd MS |
246 | if (unlikely(q->elevator)) |
247 | return 0; | |
248 | ||
cb98fc8b TH |
249 | INIT_LIST_HEAD(&q->queue_head); |
250 | q->last_merge = NULL; | |
251 | q->end_sector = 0; | |
252 | q->boundary_rq = NULL; | |
cb98fc8b | 253 | |
4eb166d9 JA |
254 | if (name) { |
255 | e = elevator_get(name); | |
256 | if (!e) | |
257 | return -EINVAL; | |
258 | } | |
1da177e4 | 259 | |
4eb166d9 JA |
260 | if (!e && *chosen_elevator) { |
261 | e = elevator_get(chosen_elevator); | |
262 | if (!e) | |
263 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
264 | chosen_elevator); | |
265 | } | |
248d5ca5 | 266 | |
4eb166d9 JA |
267 | if (!e) { |
268 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
269 | if (!e) { | |
270 | printk(KERN_ERR | |
271 | "Default I/O scheduler not found. " \ | |
272 | "Using noop.\n"); | |
273 | e = elevator_get("noop"); | |
274 | } | |
5f003976 ND |
275 | } |
276 | ||
b5deef90 | 277 | eq = elevator_alloc(q, e); |
3d1ab40f | 278 | if (!eq) |
1da177e4 | 279 | return -ENOMEM; |
1da177e4 | 280 | |
bc1c1169 JA |
281 | data = elevator_init_queue(q, eq); |
282 | if (!data) { | |
3d1ab40f | 283 | kobject_put(&eq->kobj); |
bc1c1169 JA |
284 | return -ENOMEM; |
285 | } | |
1da177e4 | 286 | |
bc1c1169 | 287 | elevator_attach(q, eq, data); |
1abec4fd | 288 | return 0; |
1da177e4 | 289 | } |
2e662b65 JA |
290 | EXPORT_SYMBOL(elevator_init); |
291 | ||
b374d18a | 292 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 293 | { |
3d1ab40f | 294 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
295 | if (e->ops->elevator_exit_fn) |
296 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
297 | e->ops = NULL; |
298 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 299 | |
3d1ab40f | 300 | kobject_put(&e->kobj); |
1da177e4 | 301 | } |
2e662b65 JA |
302 | EXPORT_SYMBOL(elevator_exit); |
303 | ||
9817064b JA |
304 | static inline void __elv_rqhash_del(struct request *rq) |
305 | { | |
306 | hlist_del_init(&rq->hash); | |
307 | } | |
308 | ||
165125e1 | 309 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
310 | { |
311 | if (ELV_ON_HASH(rq)) | |
312 | __elv_rqhash_del(rq); | |
313 | } | |
314 | ||
165125e1 | 315 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 316 | { |
b374d18a | 317 | struct elevator_queue *e = q->elevator; |
9817064b JA |
318 | |
319 | BUG_ON(ELV_ON_HASH(rq)); | |
320 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
321 | } | |
322 | ||
165125e1 | 323 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
324 | { |
325 | __elv_rqhash_del(rq); | |
326 | elv_rqhash_add(q, rq); | |
327 | } | |
328 | ||
165125e1 | 329 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 330 | { |
b374d18a | 331 | struct elevator_queue *e = q->elevator; |
9817064b JA |
332 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
333 | struct hlist_node *entry, *next; | |
334 | struct request *rq; | |
335 | ||
336 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
337 | BUG_ON(!ELV_ON_HASH(rq)); | |
338 | ||
339 | if (unlikely(!rq_mergeable(rq))) { | |
340 | __elv_rqhash_del(rq); | |
341 | continue; | |
342 | } | |
343 | ||
344 | if (rq_hash_key(rq) == offset) | |
345 | return rq; | |
346 | } | |
347 | ||
348 | return NULL; | |
349 | } | |
350 | ||
2e662b65 JA |
351 | /* |
352 | * RB-tree support functions for inserting/lookup/removal of requests | |
353 | * in a sorted RB tree. | |
354 | */ | |
355 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
356 | { | |
357 | struct rb_node **p = &root->rb_node; | |
358 | struct rb_node *parent = NULL; | |
359 | struct request *__rq; | |
360 | ||
361 | while (*p) { | |
362 | parent = *p; | |
363 | __rq = rb_entry(parent, struct request, rb_node); | |
364 | ||
83096ebf | 365 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 366 | p = &(*p)->rb_left; |
83096ebf | 367 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
368 | p = &(*p)->rb_right; |
369 | else | |
370 | return __rq; | |
371 | } | |
372 | ||
373 | rb_link_node(&rq->rb_node, parent, p); | |
374 | rb_insert_color(&rq->rb_node, root); | |
375 | return NULL; | |
376 | } | |
2e662b65 JA |
377 | EXPORT_SYMBOL(elv_rb_add); |
378 | ||
379 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
380 | { | |
381 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
382 | rb_erase(&rq->rb_node, root); | |
383 | RB_CLEAR_NODE(&rq->rb_node); | |
384 | } | |
2e662b65 JA |
385 | EXPORT_SYMBOL(elv_rb_del); |
386 | ||
387 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
388 | { | |
389 | struct rb_node *n = root->rb_node; | |
390 | struct request *rq; | |
391 | ||
392 | while (n) { | |
393 | rq = rb_entry(n, struct request, rb_node); | |
394 | ||
83096ebf | 395 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 396 | n = n->rb_left; |
83096ebf | 397 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
398 | n = n->rb_right; |
399 | else | |
400 | return rq; | |
401 | } | |
402 | ||
403 | return NULL; | |
404 | } | |
2e662b65 JA |
405 | EXPORT_SYMBOL(elv_rb_find); |
406 | ||
8922e16c TH |
407 | /* |
408 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 409 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 410 | * specific elevators. |
8922e16c | 411 | */ |
165125e1 | 412 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
413 | { |
414 | sector_t boundary; | |
8922e16c | 415 | struct list_head *entry; |
4eb166d9 | 416 | int stop_flags; |
8922e16c | 417 | |
06b86245 TH |
418 | if (q->last_merge == rq) |
419 | q->last_merge = NULL; | |
9817064b JA |
420 | |
421 | elv_rqhash_del(q, rq); | |
422 | ||
15853af9 | 423 | q->nr_sorted--; |
06b86245 | 424 | |
1b47f531 | 425 | boundary = q->end_sector; |
4eb166d9 | 426 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
427 | list_for_each_prev(entry, &q->queue_head) { |
428 | struct request *pos = list_entry_rq(entry); | |
429 | ||
33659ebb CH |
430 | if ((rq->cmd_flags & REQ_DISCARD) != |
431 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 432 | break; |
783660b2 JA |
433 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
434 | break; | |
4eb166d9 | 435 | if (pos->cmd_flags & stop_flags) |
8922e16c | 436 | break; |
83096ebf TH |
437 | if (blk_rq_pos(rq) >= boundary) { |
438 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
439 | continue; |
440 | } else { | |
83096ebf | 441 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
442 | break; |
443 | } | |
83096ebf | 444 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
445 | break; |
446 | } | |
447 | ||
448 | list_add(&rq->queuelist, entry); | |
449 | } | |
2e662b65 JA |
450 | EXPORT_SYMBOL(elv_dispatch_sort); |
451 | ||
9817064b | 452 | /* |
2e662b65 JA |
453 | * Insert rq into dispatch queue of q. Queue lock must be held on |
454 | * entry. rq is added to the back of the dispatch queue. To be used by | |
455 | * specific elevators. | |
9817064b JA |
456 | */ |
457 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
458 | { | |
459 | if (q->last_merge == rq) | |
460 | q->last_merge = NULL; | |
461 | ||
462 | elv_rqhash_del(q, rq); | |
463 | ||
464 | q->nr_sorted--; | |
465 | ||
466 | q->end_sector = rq_end_sector(rq); | |
467 | q->boundary_rq = rq; | |
468 | list_add_tail(&rq->queuelist, &q->queue_head); | |
469 | } | |
2e662b65 JA |
470 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
471 | ||
165125e1 | 472 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 473 | { |
b374d18a | 474 | struct elevator_queue *e = q->elevator; |
9817064b | 475 | struct request *__rq; |
06b86245 TH |
476 | int ret; |
477 | ||
488991e2 AB |
478 | /* |
479 | * Levels of merges: | |
480 | * nomerges: No merges at all attempted | |
481 | * noxmerges: Only simple one-hit cache try | |
482 | * merges: All merge tries attempted | |
483 | */ | |
484 | if (blk_queue_nomerges(q)) | |
485 | return ELEVATOR_NO_MERGE; | |
486 | ||
9817064b JA |
487 | /* |
488 | * First try one-hit cache. | |
489 | */ | |
06b86245 TH |
490 | if (q->last_merge) { |
491 | ret = elv_try_merge(q->last_merge, bio); | |
492 | if (ret != ELEVATOR_NO_MERGE) { | |
493 | *req = q->last_merge; | |
494 | return ret; | |
495 | } | |
496 | } | |
1da177e4 | 497 | |
488991e2 | 498 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
499 | return ELEVATOR_NO_MERGE; |
500 | ||
9817064b JA |
501 | /* |
502 | * See if our hash lookup can find a potential backmerge. | |
503 | */ | |
504 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
505 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
506 | *req = __rq; | |
507 | return ELEVATOR_BACK_MERGE; | |
508 | } | |
509 | ||
1da177e4 LT |
510 | if (e->ops->elevator_merge_fn) |
511 | return e->ops->elevator_merge_fn(q, req, bio); | |
512 | ||
513 | return ELEVATOR_NO_MERGE; | |
514 | } | |
515 | ||
165125e1 | 516 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 517 | { |
b374d18a | 518 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
519 | |
520 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 521 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 522 | |
2e662b65 JA |
523 | if (type == ELEVATOR_BACK_MERGE) |
524 | elv_rqhash_reposition(q, rq); | |
9817064b | 525 | |
06b86245 | 526 | q->last_merge = rq; |
1da177e4 LT |
527 | } |
528 | ||
165125e1 | 529 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
530 | struct request *next) |
531 | { | |
b374d18a | 532 | struct elevator_queue *e = q->elevator; |
1da177e4 | 533 | |
1da177e4 LT |
534 | if (e->ops->elevator_merge_req_fn) |
535 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 536 | |
9817064b JA |
537 | elv_rqhash_reposition(q, rq); |
538 | elv_rqhash_del(q, next); | |
539 | ||
540 | q->nr_sorted--; | |
06b86245 | 541 | q->last_merge = rq; |
1da177e4 LT |
542 | } |
543 | ||
812d4026 DS |
544 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
545 | struct bio *bio) | |
546 | { | |
547 | struct elevator_queue *e = q->elevator; | |
548 | ||
549 | if (e->ops->elevator_bio_merged_fn) | |
550 | e->ops->elevator_bio_merged_fn(q, rq, bio); | |
551 | } | |
552 | ||
165125e1 | 553 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 554 | { |
1da177e4 LT |
555 | /* |
556 | * it already went through dequeue, we need to decrement the | |
557 | * in_flight count again | |
558 | */ | |
8922e16c | 559 | if (blk_account_rq(rq)) { |
0a7ae2ff | 560 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 561 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 562 | elv_deactivate_rq(q, rq); |
8922e16c | 563 | } |
1da177e4 | 564 | |
4aff5e23 | 565 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 566 | |
30e9656c | 567 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
568 | } |
569 | ||
26308eab | 570 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
571 | { |
572 | static int printed; | |
573 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
574 | ; | |
575 | if (q->nr_sorted == 0) | |
576 | return; | |
577 | if (printed++ < 10) { | |
578 | printk(KERN_ERR "%s: forced dispatching is broken " | |
579 | "(nr_sorted=%u), please report this\n", | |
580 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
581 | } | |
582 | } | |
583 | ||
6c7e8cee JA |
584 | /* |
585 | * Call with queue lock held, interrupts disabled | |
586 | */ | |
f600abe2 | 587 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 588 | { |
cd43e26f MP |
589 | if (!q->elevator) |
590 | return; | |
591 | ||
6c7e8cee JA |
592 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
593 | ||
594 | /* | |
595 | * make sure we don't have any requests in flight | |
596 | */ | |
597 | elv_drain_elevator(q); | |
598 | while (q->rq.elvpriv) { | |
a7f55792 | 599 | __blk_run_queue(q); |
6c7e8cee JA |
600 | spin_unlock_irq(q->queue_lock); |
601 | msleep(10); | |
602 | spin_lock_irq(q->queue_lock); | |
603 | elv_drain_elevator(q); | |
604 | } | |
605 | } | |
606 | ||
f600abe2 | 607 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
608 | { |
609 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
610 | } | |
611 | ||
165125e1 | 612 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 613 | { |
797e7dbb TH |
614 | struct list_head *pos; |
615 | unsigned ordseq; | |
dac07ec1 | 616 | int unplug_it = 1; |
797e7dbb | 617 | |
5f3ea37c | 618 | trace_block_rq_insert(q, rq); |
2056a782 | 619 | |
1da177e4 LT |
620 | rq->q = q; |
621 | ||
8922e16c TH |
622 | switch (where) { |
623 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 624 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
625 | |
626 | list_add(&rq->queuelist, &q->queue_head); | |
627 | break; | |
628 | ||
629 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 630 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 631 | elv_drain_elevator(q); |
8922e16c TH |
632 | list_add_tail(&rq->queuelist, &q->queue_head); |
633 | /* | |
634 | * We kick the queue here for the following reasons. | |
635 | * - The elevator might have returned NULL previously | |
636 | * to delay requests and returned them now. As the | |
637 | * queue wasn't empty before this request, ll_rw_blk | |
638 | * won't run the queue on return, resulting in hang. | |
639 | * - Usually, back inserted requests won't be merged | |
640 | * with anything. There's no point in delaying queue | |
641 | * processing. | |
642 | */ | |
a7f55792 | 643 | __blk_run_queue(q); |
8922e16c TH |
644 | break; |
645 | ||
646 | case ELEVATOR_INSERT_SORT: | |
33659ebb CH |
647 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
648 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 649 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 650 | q->nr_sorted++; |
9817064b JA |
651 | if (rq_mergeable(rq)) { |
652 | elv_rqhash_add(q, rq); | |
653 | if (!q->last_merge) | |
654 | q->last_merge = rq; | |
655 | } | |
656 | ||
ca23509f TH |
657 | /* |
658 | * Some ioscheds (cfq) run q->request_fn directly, so | |
659 | * rq cannot be accessed after calling | |
660 | * elevator_add_req_fn. | |
661 | */ | |
662 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
663 | break; |
664 | ||
797e7dbb TH |
665 | case ELEVATOR_INSERT_REQUEUE: |
666 | /* | |
667 | * If ordered flush isn't in progress, we do front | |
668 | * insertion; otherwise, requests should be requeued | |
669 | * in ordseq order. | |
670 | */ | |
4aff5e23 | 671 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 672 | |
95543179 LV |
673 | /* |
674 | * Most requeues happen because of a busy condition, | |
675 | * don't force unplug of the queue for that case. | |
676 | */ | |
677 | unplug_it = 0; | |
678 | ||
797e7dbb TH |
679 | if (q->ordseq == 0) { |
680 | list_add(&rq->queuelist, &q->queue_head); | |
681 | break; | |
682 | } | |
683 | ||
684 | ordseq = blk_ordered_req_seq(rq); | |
685 | ||
686 | list_for_each(pos, &q->queue_head) { | |
687 | struct request *pos_rq = list_entry_rq(pos); | |
688 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
689 | break; | |
690 | } | |
691 | ||
692 | list_add_tail(&rq->queuelist, pos); | |
693 | break; | |
694 | ||
8922e16c TH |
695 | default: |
696 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 697 | __func__, where); |
8922e16c TH |
698 | BUG(); |
699 | } | |
700 | ||
dac07ec1 | 701 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 702 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
0a7ae2ff | 703 | - queue_in_flight(q); |
8922e16c TH |
704 | |
705 | if (nrq >= q->unplug_thresh) | |
706 | __generic_unplug_device(q); | |
707 | } | |
1da177e4 LT |
708 | } |
709 | ||
165125e1 | 710 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
711 | int plug) |
712 | { | |
713 | if (q->ordcolor) | |
4aff5e23 | 714 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 715 | |
4aff5e23 | 716 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
717 | /* |
718 | * toggle ordered color | |
719 | */ | |
33659ebb | 720 | if (rq->cmd_flags & REQ_HARDBARRIER) |
30e9656c TH |
721 | q->ordcolor ^= 1; |
722 | ||
723 | /* | |
724 | * barriers implicitly indicate back insertion | |
725 | */ | |
726 | if (where == ELEVATOR_INSERT_SORT) | |
727 | where = ELEVATOR_INSERT_BACK; | |
728 | ||
729 | /* | |
730 | * this request is scheduling boundary, update | |
731 | * end_sector | |
732 | */ | |
33659ebb CH |
733 | if (rq->cmd_type == REQ_TYPE_FS || |
734 | (rq->cmd_flags & REQ_DISCARD)) { | |
30e9656c TH |
735 | q->end_sector = rq_end_sector(rq); |
736 | q->boundary_rq = rq; | |
737 | } | |
4eb166d9 JA |
738 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
739 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
740 | where = ELEVATOR_INSERT_BACK; |
741 | ||
742 | if (plug) | |
743 | blk_plug_device(q); | |
744 | ||
745 | elv_insert(q, rq, where); | |
746 | } | |
2e662b65 JA |
747 | EXPORT_SYMBOL(__elv_add_request); |
748 | ||
165125e1 | 749 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
750 | int plug) |
751 | { | |
752 | unsigned long flags; | |
753 | ||
754 | spin_lock_irqsave(q->queue_lock, flags); | |
755 | __elv_add_request(q, rq, where, plug); | |
756 | spin_unlock_irqrestore(q->queue_lock, flags); | |
757 | } | |
2e662b65 JA |
758 | EXPORT_SYMBOL(elv_add_request); |
759 | ||
165125e1 | 760 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 761 | { |
b374d18a | 762 | struct elevator_queue *e = q->elevator; |
1da177e4 | 763 | |
8922e16c TH |
764 | if (!list_empty(&q->queue_head)) |
765 | return 0; | |
766 | ||
1da177e4 LT |
767 | if (e->ops->elevator_queue_empty_fn) |
768 | return e->ops->elevator_queue_empty_fn(q); | |
769 | ||
8922e16c | 770 | return 1; |
1da177e4 | 771 | } |
2e662b65 JA |
772 | EXPORT_SYMBOL(elv_queue_empty); |
773 | ||
165125e1 | 774 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 775 | { |
b374d18a | 776 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
777 | |
778 | if (e->ops->elevator_latter_req_fn) | |
779 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
780 | return NULL; |
781 | } | |
782 | ||
165125e1 | 783 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 784 | { |
b374d18a | 785 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
786 | |
787 | if (e->ops->elevator_former_req_fn) | |
788 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
789 | return NULL; |
790 | } | |
791 | ||
165125e1 | 792 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 793 | { |
b374d18a | 794 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
795 | |
796 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 797 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
798 | |
799 | rq->elevator_private = NULL; | |
800 | return 0; | |
801 | } | |
802 | ||
165125e1 | 803 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 804 | { |
b374d18a | 805 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
806 | |
807 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 808 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
809 | } |
810 | ||
165125e1 | 811 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 812 | { |
b374d18a | 813 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
814 | |
815 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 816 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
817 | |
818 | return ELV_MQUEUE_MAY; | |
819 | } | |
820 | ||
11914a53 MA |
821 | void elv_abort_queue(struct request_queue *q) |
822 | { | |
823 | struct request *rq; | |
824 | ||
825 | while (!list_empty(&q->queue_head)) { | |
826 | rq = list_entry_rq(q->queue_head.next); | |
827 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 828 | trace_block_rq_abort(q, rq); |
53c663ce KU |
829 | /* |
830 | * Mark this request as started so we don't trigger | |
831 | * any debug logic in the end I/O path. | |
832 | */ | |
833 | blk_start_request(rq); | |
40cbbb78 | 834 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
835 | } |
836 | } | |
837 | EXPORT_SYMBOL(elv_abort_queue); | |
838 | ||
165125e1 | 839 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 840 | { |
b374d18a | 841 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
842 | |
843 | /* | |
844 | * request is released from the driver, io must be done | |
845 | */ | |
8922e16c | 846 | if (blk_account_rq(rq)) { |
0a7ae2ff | 847 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb CH |
848 | if ((rq->cmd_flags & REQ_SORTED) && |
849 | e->ops->elevator_completed_req_fn) | |
1bc691d3 TH |
850 | e->ops->elevator_completed_req_fn(q, rq); |
851 | } | |
797e7dbb | 852 | |
1bc691d3 TH |
853 | /* |
854 | * Check if the queue is waiting for fs requests to be | |
855 | * drained for flush sequence. | |
856 | */ | |
857 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
858 | struct request *next = NULL; |
859 | ||
860 | if (!list_empty(&q->queue_head)) | |
861 | next = list_entry_rq(q->queue_head.next); | |
862 | ||
0a7ae2ff | 863 | if (!queue_in_flight(q) && |
797e7dbb | 864 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 865 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 866 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
a7f55792 | 867 | __blk_run_queue(q); |
797e7dbb | 868 | } |
8922e16c | 869 | } |
1da177e4 LT |
870 | } |
871 | ||
3d1ab40f AV |
872 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
873 | ||
874 | static ssize_t | |
875 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 876 | { |
3d1ab40f | 877 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 878 | struct elevator_queue *e; |
3d1ab40f AV |
879 | ssize_t error; |
880 | ||
881 | if (!entry->show) | |
882 | return -EIO; | |
883 | ||
b374d18a | 884 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
885 | mutex_lock(&e->sysfs_lock); |
886 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
887 | mutex_unlock(&e->sysfs_lock); | |
888 | return error; | |
889 | } | |
1da177e4 | 890 | |
3d1ab40f AV |
891 | static ssize_t |
892 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
893 | const char *page, size_t length) | |
894 | { | |
3d1ab40f | 895 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 896 | struct elevator_queue *e; |
3d1ab40f | 897 | ssize_t error; |
1da177e4 | 898 | |
3d1ab40f AV |
899 | if (!entry->store) |
900 | return -EIO; | |
1da177e4 | 901 | |
b374d18a | 902 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
903 | mutex_lock(&e->sysfs_lock); |
904 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
905 | mutex_unlock(&e->sysfs_lock); | |
906 | return error; | |
907 | } | |
908 | ||
52cf25d0 | 909 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
910 | .show = elv_attr_show, |
911 | .store = elv_attr_store, | |
912 | }; | |
913 | ||
914 | static struct kobj_type elv_ktype = { | |
915 | .sysfs_ops = &elv_sysfs_ops, | |
916 | .release = elevator_release, | |
917 | }; | |
918 | ||
919 | int elv_register_queue(struct request_queue *q) | |
920 | { | |
b374d18a | 921 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
922 | int error; |
923 | ||
b2d6db58 | 924 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 925 | if (!error) { |
e572ec7e | 926 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 927 | if (attr) { |
e572ec7e AV |
928 | while (attr->attr.name) { |
929 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 930 | break; |
e572ec7e | 931 | attr++; |
3d1ab40f AV |
932 | } |
933 | } | |
934 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
935 | } | |
936 | return error; | |
1da177e4 | 937 | } |
01effb0d | 938 | EXPORT_SYMBOL(elv_register_queue); |
1da177e4 | 939 | |
b374d18a | 940 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
941 | { |
942 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
943 | kobject_del(&e->kobj); | |
944 | } | |
945 | ||
1da177e4 LT |
946 | void elv_unregister_queue(struct request_queue *q) |
947 | { | |
bc1c1169 JA |
948 | if (q) |
949 | __elv_unregister_queue(q->elevator); | |
1da177e4 | 950 | } |
01effb0d | 951 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 952 | |
2fdd82bd | 953 | void elv_register(struct elevator_type *e) |
1da177e4 | 954 | { |
1ffb96c5 | 955 | char *def = ""; |
2a12dcd7 JA |
956 | |
957 | spin_lock(&elv_list_lock); | |
ce524497 | 958 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 959 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 960 | spin_unlock(&elv_list_lock); |
1da177e4 | 961 | |
5f003976 ND |
962 | if (!strcmp(e->elevator_name, chosen_elevator) || |
963 | (!*chosen_elevator && | |
964 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
965 | def = " (default)"; |
966 | ||
4eb166d9 JA |
967 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
968 | def); | |
1da177e4 LT |
969 | } |
970 | EXPORT_SYMBOL_GPL(elv_register); | |
971 | ||
972 | void elv_unregister(struct elevator_type *e) | |
973 | { | |
83521d3e CH |
974 | struct task_struct *g, *p; |
975 | ||
976 | /* | |
977 | * Iterate every thread in the process to remove the io contexts. | |
978 | */ | |
e17a9489 AV |
979 | if (e->ops.trim) { |
980 | read_lock(&tasklist_lock); | |
981 | do_each_thread(g, p) { | |
982 | task_lock(p); | |
2d8f6131 ON |
983 | if (p->io_context) |
984 | e->ops.trim(p->io_context); | |
e17a9489 AV |
985 | task_unlock(p); |
986 | } while_each_thread(g, p); | |
987 | read_unlock(&tasklist_lock); | |
988 | } | |
83521d3e | 989 | |
2a12dcd7 | 990 | spin_lock(&elv_list_lock); |
1da177e4 | 991 | list_del_init(&e->list); |
2a12dcd7 | 992 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
993 | } |
994 | EXPORT_SYMBOL_GPL(elv_unregister); | |
995 | ||
996 | /* | |
997 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
998 | * we don't free the old io scheduler, before we have allocated what we | |
999 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1000 | * one, if the new one fails init for some reason. |
1da177e4 | 1001 | */ |
165125e1 | 1002 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1003 | { |
b374d18a | 1004 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 1005 | void *data; |
1da177e4 | 1006 | |
cb98fc8b TH |
1007 | /* |
1008 | * Allocate new elevator | |
1009 | */ | |
b5deef90 | 1010 | e = elevator_alloc(q, new_e); |
1da177e4 | 1011 | if (!e) |
3d1ab40f | 1012 | return 0; |
1da177e4 | 1013 | |
bc1c1169 JA |
1014 | data = elevator_init_queue(q, e); |
1015 | if (!data) { | |
1016 | kobject_put(&e->kobj); | |
1017 | return 0; | |
1018 | } | |
1019 | ||
1da177e4 | 1020 | /* |
cb98fc8b | 1021 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1022 | */ |
cb98fc8b | 1023 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1024 | elv_quiesce_start(q); |
cb98fc8b | 1025 | |
1da177e4 | 1026 | /* |
bc1c1169 | 1027 | * Remember old elevator. |
1da177e4 | 1028 | */ |
1da177e4 LT |
1029 | old_elevator = q->elevator; |
1030 | ||
1da177e4 LT |
1031 | /* |
1032 | * attach and start new elevator | |
1033 | */ | |
bc1c1169 JA |
1034 | elevator_attach(q, e, data); |
1035 | ||
1036 | spin_unlock_irq(q->queue_lock); | |
1037 | ||
1038 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1039 | |
1040 | if (elv_register_queue(q)) | |
1041 | goto fail_register; | |
1042 | ||
1043 | /* | |
cb98fc8b | 1044 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1045 | */ |
1046 | elevator_exit(old_elevator); | |
75ad23bc | 1047 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1048 | elv_quiesce_end(q); |
75ad23bc NP |
1049 | spin_unlock_irq(q->queue_lock); |
1050 | ||
4722dc52 AB |
1051 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1052 | ||
3d1ab40f | 1053 | return 1; |
1da177e4 LT |
1054 | |
1055 | fail_register: | |
1056 | /* | |
1057 | * switch failed, exit the new io scheduler and reattach the old | |
1058 | * one again (along with re-adding the sysfs dir) | |
1059 | */ | |
1060 | elevator_exit(e); | |
1da177e4 LT |
1061 | q->elevator = old_elevator; |
1062 | elv_register_queue(q); | |
75ad23bc NP |
1063 | |
1064 | spin_lock_irq(q->queue_lock); | |
1065 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1066 | spin_unlock_irq(q->queue_lock); | |
1067 | ||
3d1ab40f | 1068 | return 0; |
1da177e4 LT |
1069 | } |
1070 | ||
165125e1 JA |
1071 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1072 | size_t count) | |
1da177e4 LT |
1073 | { |
1074 | char elevator_name[ELV_NAME_MAX]; | |
1075 | struct elevator_type *e; | |
1076 | ||
cd43e26f MP |
1077 | if (!q->elevator) |
1078 | return count; | |
1079 | ||
ee2e992c | 1080 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 1081 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
1082 | if (!e) { |
1083 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1084 | return -EINVAL; | |
1085 | } | |
1086 | ||
2ca7d93b ND |
1087 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1088 | elevator_put(e); | |
1da177e4 | 1089 | return count; |
2ca7d93b | 1090 | } |
1da177e4 | 1091 | |
3d1ab40f | 1092 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1093 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1094 | elevator_name); | |
1da177e4 LT |
1095 | return count; |
1096 | } | |
1097 | ||
165125e1 | 1098 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1099 | { |
b374d18a | 1100 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1101 | struct elevator_type *elv; |
70cee26e | 1102 | struct elevator_type *__e; |
1da177e4 LT |
1103 | int len = 0; |
1104 | ||
e36f724b | 1105 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1106 | return sprintf(name, "none\n"); |
1107 | ||
1108 | elv = e->elevator_type; | |
1109 | ||
2a12dcd7 | 1110 | spin_lock(&elv_list_lock); |
70cee26e | 1111 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1112 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1113 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1114 | else | |
1115 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1116 | } | |
2a12dcd7 | 1117 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1118 | |
1119 | len += sprintf(len+name, "\n"); | |
1120 | return len; | |
1121 | } | |
1122 | ||
165125e1 JA |
1123 | struct request *elv_rb_former_request(struct request_queue *q, |
1124 | struct request *rq) | |
2e662b65 JA |
1125 | { |
1126 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1127 | ||
1128 | if (rbprev) | |
1129 | return rb_entry_rq(rbprev); | |
1130 | ||
1131 | return NULL; | |
1132 | } | |
2e662b65 JA |
1133 | EXPORT_SYMBOL(elv_rb_former_request); |
1134 | ||
165125e1 JA |
1135 | struct request *elv_rb_latter_request(struct request_queue *q, |
1136 | struct request *rq) | |
2e662b65 JA |
1137 | { |
1138 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1139 | ||
1140 | if (rbnext) | |
1141 | return rb_entry_rq(rbnext); | |
1142 | ||
1143 | return NULL; | |
1144 | } | |
2e662b65 | 1145 | EXPORT_SYMBOL(elv_rb_latter_request); |