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 | ||
ab0fd1de | 103 | /* |
0a09f431 TH |
104 | * Don't merge if failfast settings don't match. |
105 | * | |
106 | * FIXME: The negation in front of each condition is necessary | |
107 | * because bio and request flags use different bit positions | |
108 | * and the accessors return those bits directly. This | |
109 | * ugliness will soon go away. | |
ab0fd1de | 110 | */ |
0a09f431 TH |
111 | if (!bio_failfast_dev(bio) != !blk_failfast_dev(rq) || |
112 | !bio_failfast_transport(bio) != !blk_failfast_transport(rq) || | |
113 | !bio_failfast_driver(bio) != !blk_failfast_driver(rq)) | |
ab0fd1de TH |
114 | return 0; |
115 | ||
da775265 JA |
116 | if (!elv_iosched_allow_merge(rq, bio)) |
117 | return 0; | |
1da177e4 | 118 | |
da775265 | 119 | return 1; |
1da177e4 LT |
120 | } |
121 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
122 | ||
769db45b | 123 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
124 | { |
125 | int ret = ELEVATOR_NO_MERGE; | |
126 | ||
127 | /* | |
128 | * we can merge and sequence is ok, check if it's possible | |
129 | */ | |
130 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 131 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 132 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 133 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
134 | ret = ELEVATOR_FRONT_MERGE; |
135 | } | |
136 | ||
137 | return ret; | |
138 | } | |
1da177e4 | 139 | |
1da177e4 LT |
140 | static struct elevator_type *elevator_find(const char *name) |
141 | { | |
a22b169d | 142 | struct elevator_type *e; |
1da177e4 | 143 | |
70cee26e | 144 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
145 | if (!strcmp(e->elevator_name, name)) |
146 | return e; | |
1da177e4 | 147 | } |
1da177e4 | 148 | |
a22b169d | 149 | return NULL; |
1da177e4 LT |
150 | } |
151 | ||
152 | static void elevator_put(struct elevator_type *e) | |
153 | { | |
154 | module_put(e->elevator_owner); | |
155 | } | |
156 | ||
157 | static struct elevator_type *elevator_get(const char *name) | |
158 | { | |
2824bc93 | 159 | struct elevator_type *e; |
1da177e4 | 160 | |
2a12dcd7 | 161 | spin_lock(&elv_list_lock); |
2824bc93 TH |
162 | |
163 | e = elevator_find(name); | |
e1640949 JA |
164 | if (!e) { |
165 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
166 | ||
167 | spin_unlock(&elv_list_lock); | |
168 | ||
169 | if (!strcmp(name, "anticipatory")) | |
170 | sprintf(elv, "as-iosched"); | |
171 | else | |
172 | sprintf(elv, "%s-iosched", name); | |
173 | ||
e180f594 | 174 | request_module("%s", elv); |
e1640949 JA |
175 | spin_lock(&elv_list_lock); |
176 | e = elevator_find(name); | |
177 | } | |
178 | ||
2824bc93 TH |
179 | if (e && !try_module_get(e->elevator_owner)) |
180 | e = NULL; | |
181 | ||
2a12dcd7 | 182 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
183 | |
184 | return e; | |
185 | } | |
186 | ||
165125e1 JA |
187 | static void *elevator_init_queue(struct request_queue *q, |
188 | struct elevator_queue *eq) | |
1da177e4 | 189 | { |
bb37b94c | 190 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 191 | } |
1da177e4 | 192 | |
165125e1 | 193 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
194 | void *data) |
195 | { | |
1da177e4 | 196 | q->elevator = eq; |
bc1c1169 | 197 | eq->elevator_data = data; |
1da177e4 LT |
198 | } |
199 | ||
200 | static char chosen_elevator[16]; | |
201 | ||
5f003976 | 202 | static int __init elevator_setup(char *str) |
1da177e4 | 203 | { |
752a3b79 CE |
204 | /* |
205 | * Be backwards-compatible with previous kernels, so users | |
206 | * won't get the wrong elevator. | |
207 | */ | |
5f003976 | 208 | if (!strcmp(str, "as")) |
752a3b79 | 209 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 210 | else |
5f003976 | 211 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 212 | return 1; |
1da177e4 LT |
213 | } |
214 | ||
215 | __setup("elevator=", elevator_setup); | |
216 | ||
3d1ab40f AV |
217 | static struct kobj_type elv_ktype; |
218 | ||
b374d18a | 219 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 220 | struct elevator_type *e) |
3d1ab40f | 221 | { |
b374d18a | 222 | struct elevator_queue *eq; |
9817064b JA |
223 | int i; |
224 | ||
b374d18a | 225 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
226 | if (unlikely(!eq)) |
227 | goto err; | |
228 | ||
9817064b JA |
229 | eq->ops = &e->ops; |
230 | eq->elevator_type = e; | |
f9cb074b | 231 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
232 | mutex_init(&eq->sysfs_lock); |
233 | ||
b5deef90 JA |
234 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
235 | GFP_KERNEL, q->node); | |
9817064b JA |
236 | if (!eq->hash) |
237 | goto err; | |
238 | ||
239 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
240 | INIT_HLIST_HEAD(&eq->hash[i]); | |
241 | ||
3d1ab40f | 242 | return eq; |
9817064b JA |
243 | err: |
244 | kfree(eq); | |
245 | elevator_put(e); | |
246 | return NULL; | |
3d1ab40f AV |
247 | } |
248 | ||
249 | static void elevator_release(struct kobject *kobj) | |
250 | { | |
b374d18a | 251 | struct elevator_queue *e; |
9817064b | 252 | |
b374d18a | 253 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 254 | elevator_put(e->elevator_type); |
9817064b | 255 | kfree(e->hash); |
3d1ab40f AV |
256 | kfree(e); |
257 | } | |
258 | ||
165125e1 | 259 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
260 | { |
261 | struct elevator_type *e = NULL; | |
262 | struct elevator_queue *eq; | |
263 | int ret = 0; | |
bc1c1169 | 264 | void *data; |
1da177e4 | 265 | |
cb98fc8b TH |
266 | INIT_LIST_HEAD(&q->queue_head); |
267 | q->last_merge = NULL; | |
268 | q->end_sector = 0; | |
269 | q->boundary_rq = NULL; | |
cb98fc8b | 270 | |
4eb166d9 JA |
271 | if (name) { |
272 | e = elevator_get(name); | |
273 | if (!e) | |
274 | return -EINVAL; | |
275 | } | |
1da177e4 | 276 | |
4eb166d9 JA |
277 | if (!e && *chosen_elevator) { |
278 | e = elevator_get(chosen_elevator); | |
279 | if (!e) | |
280 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
281 | chosen_elevator); | |
282 | } | |
248d5ca5 | 283 | |
4eb166d9 JA |
284 | if (!e) { |
285 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
286 | if (!e) { | |
287 | printk(KERN_ERR | |
288 | "Default I/O scheduler not found. " \ | |
289 | "Using noop.\n"); | |
290 | e = elevator_get("noop"); | |
291 | } | |
5f003976 ND |
292 | } |
293 | ||
b5deef90 | 294 | eq = elevator_alloc(q, e); |
3d1ab40f | 295 | if (!eq) |
1da177e4 | 296 | return -ENOMEM; |
1da177e4 | 297 | |
bc1c1169 JA |
298 | data = elevator_init_queue(q, eq); |
299 | if (!data) { | |
3d1ab40f | 300 | kobject_put(&eq->kobj); |
bc1c1169 JA |
301 | return -ENOMEM; |
302 | } | |
1da177e4 | 303 | |
bc1c1169 | 304 | elevator_attach(q, eq, data); |
1da177e4 LT |
305 | return ret; |
306 | } | |
2e662b65 JA |
307 | EXPORT_SYMBOL(elevator_init); |
308 | ||
b374d18a | 309 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 310 | { |
3d1ab40f | 311 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
312 | if (e->ops->elevator_exit_fn) |
313 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
314 | e->ops = NULL; |
315 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 316 | |
3d1ab40f | 317 | kobject_put(&e->kobj); |
1da177e4 | 318 | } |
2e662b65 JA |
319 | EXPORT_SYMBOL(elevator_exit); |
320 | ||
9817064b JA |
321 | static inline void __elv_rqhash_del(struct request *rq) |
322 | { | |
323 | hlist_del_init(&rq->hash); | |
324 | } | |
325 | ||
165125e1 | 326 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
327 | { |
328 | if (ELV_ON_HASH(rq)) | |
329 | __elv_rqhash_del(rq); | |
330 | } | |
331 | ||
165125e1 | 332 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 333 | { |
b374d18a | 334 | struct elevator_queue *e = q->elevator; |
9817064b JA |
335 | |
336 | BUG_ON(ELV_ON_HASH(rq)); | |
337 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
338 | } | |
339 | ||
165125e1 | 340 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
341 | { |
342 | __elv_rqhash_del(rq); | |
343 | elv_rqhash_add(q, rq); | |
344 | } | |
345 | ||
165125e1 | 346 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 347 | { |
b374d18a | 348 | struct elevator_queue *e = q->elevator; |
9817064b JA |
349 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
350 | struct hlist_node *entry, *next; | |
351 | struct request *rq; | |
352 | ||
353 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
354 | BUG_ON(!ELV_ON_HASH(rq)); | |
355 | ||
356 | if (unlikely(!rq_mergeable(rq))) { | |
357 | __elv_rqhash_del(rq); | |
358 | continue; | |
359 | } | |
360 | ||
361 | if (rq_hash_key(rq) == offset) | |
362 | return rq; | |
363 | } | |
364 | ||
365 | return NULL; | |
366 | } | |
367 | ||
2e662b65 JA |
368 | /* |
369 | * RB-tree support functions for inserting/lookup/removal of requests | |
370 | * in a sorted RB tree. | |
371 | */ | |
372 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
373 | { | |
374 | struct rb_node **p = &root->rb_node; | |
375 | struct rb_node *parent = NULL; | |
376 | struct request *__rq; | |
377 | ||
378 | while (*p) { | |
379 | parent = *p; | |
380 | __rq = rb_entry(parent, struct request, rb_node); | |
381 | ||
83096ebf | 382 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 383 | p = &(*p)->rb_left; |
83096ebf | 384 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
385 | p = &(*p)->rb_right; |
386 | else | |
387 | return __rq; | |
388 | } | |
389 | ||
390 | rb_link_node(&rq->rb_node, parent, p); | |
391 | rb_insert_color(&rq->rb_node, root); | |
392 | return NULL; | |
393 | } | |
2e662b65 JA |
394 | EXPORT_SYMBOL(elv_rb_add); |
395 | ||
396 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
397 | { | |
398 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
399 | rb_erase(&rq->rb_node, root); | |
400 | RB_CLEAR_NODE(&rq->rb_node); | |
401 | } | |
2e662b65 JA |
402 | EXPORT_SYMBOL(elv_rb_del); |
403 | ||
404 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
405 | { | |
406 | struct rb_node *n = root->rb_node; | |
407 | struct request *rq; | |
408 | ||
409 | while (n) { | |
410 | rq = rb_entry(n, struct request, rb_node); | |
411 | ||
83096ebf | 412 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 413 | n = n->rb_left; |
83096ebf | 414 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
415 | n = n->rb_right; |
416 | else | |
417 | return rq; | |
418 | } | |
419 | ||
420 | return NULL; | |
421 | } | |
2e662b65 JA |
422 | EXPORT_SYMBOL(elv_rb_find); |
423 | ||
8922e16c TH |
424 | /* |
425 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 426 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 427 | * specific elevators. |
8922e16c | 428 | */ |
165125e1 | 429 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
430 | { |
431 | sector_t boundary; | |
8922e16c | 432 | struct list_head *entry; |
4eb166d9 | 433 | int stop_flags; |
8922e16c | 434 | |
06b86245 TH |
435 | if (q->last_merge == rq) |
436 | q->last_merge = NULL; | |
9817064b JA |
437 | |
438 | elv_rqhash_del(q, rq); | |
439 | ||
15853af9 | 440 | q->nr_sorted--; |
06b86245 | 441 | |
1b47f531 | 442 | boundary = q->end_sector; |
4eb166d9 | 443 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
444 | list_for_each_prev(entry, &q->queue_head) { |
445 | struct request *pos = list_entry_rq(entry); | |
446 | ||
e17fc0a1 DW |
447 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
448 | break; | |
783660b2 JA |
449 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
450 | break; | |
4eb166d9 | 451 | if (pos->cmd_flags & stop_flags) |
8922e16c | 452 | break; |
83096ebf TH |
453 | if (blk_rq_pos(rq) >= boundary) { |
454 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
455 | continue; |
456 | } else { | |
83096ebf | 457 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
458 | break; |
459 | } | |
83096ebf | 460 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
461 | break; |
462 | } | |
463 | ||
464 | list_add(&rq->queuelist, entry); | |
465 | } | |
2e662b65 JA |
466 | EXPORT_SYMBOL(elv_dispatch_sort); |
467 | ||
9817064b | 468 | /* |
2e662b65 JA |
469 | * Insert rq into dispatch queue of q. Queue lock must be held on |
470 | * entry. rq is added to the back of the dispatch queue. To be used by | |
471 | * specific elevators. | |
9817064b JA |
472 | */ |
473 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
474 | { | |
475 | if (q->last_merge == rq) | |
476 | q->last_merge = NULL; | |
477 | ||
478 | elv_rqhash_del(q, rq); | |
479 | ||
480 | q->nr_sorted--; | |
481 | ||
482 | q->end_sector = rq_end_sector(rq); | |
483 | q->boundary_rq = rq; | |
484 | list_add_tail(&rq->queuelist, &q->queue_head); | |
485 | } | |
2e662b65 JA |
486 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
487 | ||
165125e1 | 488 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 489 | { |
b374d18a | 490 | struct elevator_queue *e = q->elevator; |
9817064b | 491 | struct request *__rq; |
06b86245 TH |
492 | int ret; |
493 | ||
9817064b JA |
494 | /* |
495 | * First try one-hit cache. | |
496 | */ | |
06b86245 TH |
497 | if (q->last_merge) { |
498 | ret = elv_try_merge(q->last_merge, bio); | |
499 | if (ret != ELEVATOR_NO_MERGE) { | |
500 | *req = q->last_merge; | |
501 | return ret; | |
502 | } | |
503 | } | |
1da177e4 | 504 | |
ac9fafa1 AB |
505 | if (blk_queue_nomerges(q)) |
506 | return ELEVATOR_NO_MERGE; | |
507 | ||
9817064b JA |
508 | /* |
509 | * See if our hash lookup can find a potential backmerge. | |
510 | */ | |
511 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
512 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
513 | *req = __rq; | |
514 | return ELEVATOR_BACK_MERGE; | |
515 | } | |
516 | ||
1da177e4 LT |
517 | if (e->ops->elevator_merge_fn) |
518 | return e->ops->elevator_merge_fn(q, req, bio); | |
519 | ||
520 | return ELEVATOR_NO_MERGE; | |
521 | } | |
522 | ||
165125e1 | 523 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 524 | { |
b374d18a | 525 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
526 | |
527 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 528 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 529 | |
2e662b65 JA |
530 | if (type == ELEVATOR_BACK_MERGE) |
531 | elv_rqhash_reposition(q, rq); | |
9817064b | 532 | |
06b86245 | 533 | q->last_merge = rq; |
1da177e4 LT |
534 | } |
535 | ||
165125e1 | 536 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
537 | struct request *next) |
538 | { | |
b374d18a | 539 | struct elevator_queue *e = q->elevator; |
1da177e4 | 540 | |
1da177e4 LT |
541 | if (e->ops->elevator_merge_req_fn) |
542 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 543 | |
9817064b JA |
544 | elv_rqhash_reposition(q, rq); |
545 | elv_rqhash_del(q, next); | |
546 | ||
547 | q->nr_sorted--; | |
06b86245 | 548 | q->last_merge = rq; |
1da177e4 LT |
549 | } |
550 | ||
165125e1 | 551 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 552 | { |
1da177e4 LT |
553 | /* |
554 | * it already went through dequeue, we need to decrement the | |
555 | * in_flight count again | |
556 | */ | |
8922e16c | 557 | if (blk_account_rq(rq)) { |
0a7ae2ff | 558 | q->in_flight[rq_is_sync(rq)]--; |
cad97516 JA |
559 | if (blk_sorted_rq(rq)) |
560 | elv_deactivate_rq(q, rq); | |
8922e16c | 561 | } |
1da177e4 | 562 | |
4aff5e23 | 563 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 564 | |
30e9656c | 565 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
566 | } |
567 | ||
26308eab | 568 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
569 | { |
570 | static int printed; | |
571 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
572 | ; | |
573 | if (q->nr_sorted == 0) | |
574 | return; | |
575 | if (printed++ < 10) { | |
576 | printk(KERN_ERR "%s: forced dispatching is broken " | |
577 | "(nr_sorted=%u), please report this\n", | |
578 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
579 | } | |
580 | } | |
581 | ||
6c7e8cee JA |
582 | /* |
583 | * Call with queue lock held, interrupts disabled | |
584 | */ | |
f600abe2 | 585 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 586 | { |
cd43e26f MP |
587 | if (!q->elevator) |
588 | return; | |
589 | ||
6c7e8cee JA |
590 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
591 | ||
592 | /* | |
593 | * make sure we don't have any requests in flight | |
594 | */ | |
595 | elv_drain_elevator(q); | |
596 | while (q->rq.elvpriv) { | |
a7f55792 | 597 | __blk_run_queue(q); |
6c7e8cee JA |
598 | spin_unlock_irq(q->queue_lock); |
599 | msleep(10); | |
600 | spin_lock_irq(q->queue_lock); | |
601 | elv_drain_elevator(q); | |
602 | } | |
603 | } | |
604 | ||
f600abe2 | 605 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
606 | { |
607 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
608 | } | |
609 | ||
165125e1 | 610 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 611 | { |
797e7dbb TH |
612 | struct list_head *pos; |
613 | unsigned ordseq; | |
dac07ec1 | 614 | int unplug_it = 1; |
797e7dbb | 615 | |
5f3ea37c | 616 | trace_block_rq_insert(q, rq); |
2056a782 | 617 | |
1da177e4 LT |
618 | rq->q = q; |
619 | ||
8922e16c TH |
620 | switch (where) { |
621 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 622 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
623 | |
624 | list_add(&rq->queuelist, &q->queue_head); | |
625 | break; | |
626 | ||
627 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 628 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 629 | elv_drain_elevator(q); |
8922e16c TH |
630 | list_add_tail(&rq->queuelist, &q->queue_head); |
631 | /* | |
632 | * We kick the queue here for the following reasons. | |
633 | * - The elevator might have returned NULL previously | |
634 | * to delay requests and returned them now. As the | |
635 | * queue wasn't empty before this request, ll_rw_blk | |
636 | * won't run the queue on return, resulting in hang. | |
637 | * - Usually, back inserted requests won't be merged | |
638 | * with anything. There's no point in delaying queue | |
639 | * processing. | |
640 | */ | |
a7f55792 | 641 | __blk_run_queue(q); |
8922e16c TH |
642 | break; |
643 | ||
644 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 645 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 646 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 647 | q->nr_sorted++; |
9817064b JA |
648 | if (rq_mergeable(rq)) { |
649 | elv_rqhash_add(q, rq); | |
650 | if (!q->last_merge) | |
651 | q->last_merge = rq; | |
652 | } | |
653 | ||
ca23509f TH |
654 | /* |
655 | * Some ioscheds (cfq) run q->request_fn directly, so | |
656 | * rq cannot be accessed after calling | |
657 | * elevator_add_req_fn. | |
658 | */ | |
659 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
660 | break; |
661 | ||
797e7dbb TH |
662 | case ELEVATOR_INSERT_REQUEUE: |
663 | /* | |
664 | * If ordered flush isn't in progress, we do front | |
665 | * insertion; otherwise, requests should be requeued | |
666 | * in ordseq order. | |
667 | */ | |
4aff5e23 | 668 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 669 | |
95543179 LV |
670 | /* |
671 | * Most requeues happen because of a busy condition, | |
672 | * don't force unplug of the queue for that case. | |
673 | */ | |
674 | unplug_it = 0; | |
675 | ||
797e7dbb TH |
676 | if (q->ordseq == 0) { |
677 | list_add(&rq->queuelist, &q->queue_head); | |
678 | break; | |
679 | } | |
680 | ||
681 | ordseq = blk_ordered_req_seq(rq); | |
682 | ||
683 | list_for_each(pos, &q->queue_head) { | |
684 | struct request *pos_rq = list_entry_rq(pos); | |
685 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
686 | break; | |
687 | } | |
688 | ||
689 | list_add_tail(&rq->queuelist, pos); | |
690 | break; | |
691 | ||
8922e16c TH |
692 | default: |
693 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 694 | __func__, where); |
8922e16c TH |
695 | BUG(); |
696 | } | |
697 | ||
dac07ec1 | 698 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 699 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
0a7ae2ff | 700 | - queue_in_flight(q); |
8922e16c TH |
701 | |
702 | if (nrq >= q->unplug_thresh) | |
703 | __generic_unplug_device(q); | |
704 | } | |
1da177e4 LT |
705 | } |
706 | ||
165125e1 | 707 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
708 | int plug) |
709 | { | |
710 | if (q->ordcolor) | |
4aff5e23 | 711 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 712 | |
4aff5e23 | 713 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
714 | /* |
715 | * toggle ordered color | |
716 | */ | |
717 | if (blk_barrier_rq(rq)) | |
718 | q->ordcolor ^= 1; | |
719 | ||
720 | /* | |
721 | * barriers implicitly indicate back insertion | |
722 | */ | |
723 | if (where == ELEVATOR_INSERT_SORT) | |
724 | where = ELEVATOR_INSERT_BACK; | |
725 | ||
726 | /* | |
727 | * this request is scheduling boundary, update | |
728 | * end_sector | |
729 | */ | |
e17fc0a1 | 730 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
731 | q->end_sector = rq_end_sector(rq); |
732 | q->boundary_rq = rq; | |
733 | } | |
4eb166d9 JA |
734 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
735 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
736 | where = ELEVATOR_INSERT_BACK; |
737 | ||
738 | if (plug) | |
739 | blk_plug_device(q); | |
740 | ||
741 | elv_insert(q, rq, where); | |
742 | } | |
2e662b65 JA |
743 | EXPORT_SYMBOL(__elv_add_request); |
744 | ||
165125e1 | 745 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
746 | int plug) |
747 | { | |
748 | unsigned long flags; | |
749 | ||
750 | spin_lock_irqsave(q->queue_lock, flags); | |
751 | __elv_add_request(q, rq, where, plug); | |
752 | spin_unlock_irqrestore(q->queue_lock, flags); | |
753 | } | |
2e662b65 JA |
754 | EXPORT_SYMBOL(elv_add_request); |
755 | ||
165125e1 | 756 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 757 | { |
b374d18a | 758 | struct elevator_queue *e = q->elevator; |
1da177e4 | 759 | |
8922e16c TH |
760 | if (!list_empty(&q->queue_head)) |
761 | return 0; | |
762 | ||
1da177e4 LT |
763 | if (e->ops->elevator_queue_empty_fn) |
764 | return e->ops->elevator_queue_empty_fn(q); | |
765 | ||
8922e16c | 766 | return 1; |
1da177e4 | 767 | } |
2e662b65 JA |
768 | EXPORT_SYMBOL(elv_queue_empty); |
769 | ||
165125e1 | 770 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 771 | { |
b374d18a | 772 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
773 | |
774 | if (e->ops->elevator_latter_req_fn) | |
775 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
776 | return NULL; |
777 | } | |
778 | ||
165125e1 | 779 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 780 | { |
b374d18a | 781 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
782 | |
783 | if (e->ops->elevator_former_req_fn) | |
784 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
785 | return NULL; |
786 | } | |
787 | ||
165125e1 | 788 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 789 | { |
b374d18a | 790 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
791 | |
792 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 793 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
794 | |
795 | rq->elevator_private = NULL; | |
796 | return 0; | |
797 | } | |
798 | ||
165125e1 | 799 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 800 | { |
b374d18a | 801 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
802 | |
803 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 804 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
805 | } |
806 | ||
165125e1 | 807 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 808 | { |
b374d18a | 809 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
810 | |
811 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 812 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
813 | |
814 | return ELV_MQUEUE_MAY; | |
815 | } | |
816 | ||
11914a53 MA |
817 | void elv_abort_queue(struct request_queue *q) |
818 | { | |
819 | struct request *rq; | |
820 | ||
821 | while (!list_empty(&q->queue_head)) { | |
822 | rq = list_entry_rq(q->queue_head.next); | |
823 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 824 | trace_block_rq_abort(q, rq); |
53c663ce KU |
825 | /* |
826 | * Mark this request as started so we don't trigger | |
827 | * any debug logic in the end I/O path. | |
828 | */ | |
829 | blk_start_request(rq); | |
40cbbb78 | 830 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
831 | } |
832 | } | |
833 | EXPORT_SYMBOL(elv_abort_queue); | |
834 | ||
165125e1 | 835 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 836 | { |
b374d18a | 837 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
838 | |
839 | /* | |
840 | * request is released from the driver, io must be done | |
841 | */ | |
8922e16c | 842 | if (blk_account_rq(rq)) { |
0a7ae2ff | 843 | q->in_flight[rq_is_sync(rq)]--; |
1bc691d3 TH |
844 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
845 | e->ops->elevator_completed_req_fn(q, rq); | |
846 | } | |
797e7dbb | 847 | |
1bc691d3 TH |
848 | /* |
849 | * Check if the queue is waiting for fs requests to be | |
850 | * drained for flush sequence. | |
851 | */ | |
852 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
853 | struct request *next = NULL; |
854 | ||
855 | if (!list_empty(&q->queue_head)) | |
856 | next = list_entry_rq(q->queue_head.next); | |
857 | ||
0a7ae2ff | 858 | if (!queue_in_flight(q) && |
797e7dbb | 859 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 860 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 861 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
a7f55792 | 862 | __blk_run_queue(q); |
797e7dbb | 863 | } |
8922e16c | 864 | } |
1da177e4 LT |
865 | } |
866 | ||
3d1ab40f AV |
867 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
868 | ||
869 | static ssize_t | |
870 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 871 | { |
3d1ab40f | 872 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 873 | struct elevator_queue *e; |
3d1ab40f AV |
874 | ssize_t error; |
875 | ||
876 | if (!entry->show) | |
877 | return -EIO; | |
878 | ||
b374d18a | 879 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
880 | mutex_lock(&e->sysfs_lock); |
881 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
882 | mutex_unlock(&e->sysfs_lock); | |
883 | return error; | |
884 | } | |
1da177e4 | 885 | |
3d1ab40f AV |
886 | static ssize_t |
887 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
888 | const char *page, size_t length) | |
889 | { | |
3d1ab40f | 890 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 891 | struct elevator_queue *e; |
3d1ab40f | 892 | ssize_t error; |
1da177e4 | 893 | |
3d1ab40f AV |
894 | if (!entry->store) |
895 | return -EIO; | |
1da177e4 | 896 | |
b374d18a | 897 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
898 | mutex_lock(&e->sysfs_lock); |
899 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
900 | mutex_unlock(&e->sysfs_lock); | |
901 | return error; | |
902 | } | |
903 | ||
904 | static struct sysfs_ops elv_sysfs_ops = { | |
905 | .show = elv_attr_show, | |
906 | .store = elv_attr_store, | |
907 | }; | |
908 | ||
909 | static struct kobj_type elv_ktype = { | |
910 | .sysfs_ops = &elv_sysfs_ops, | |
911 | .release = elevator_release, | |
912 | }; | |
913 | ||
914 | int elv_register_queue(struct request_queue *q) | |
915 | { | |
b374d18a | 916 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
917 | int error; |
918 | ||
b2d6db58 | 919 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 920 | if (!error) { |
e572ec7e | 921 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 922 | if (attr) { |
e572ec7e AV |
923 | while (attr->attr.name) { |
924 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 925 | break; |
e572ec7e | 926 | attr++; |
3d1ab40f AV |
927 | } |
928 | } | |
929 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
930 | } | |
931 | return error; | |
1da177e4 LT |
932 | } |
933 | ||
b374d18a | 934 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
935 | { |
936 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
937 | kobject_del(&e->kobj); | |
938 | } | |
939 | ||
1da177e4 LT |
940 | void elv_unregister_queue(struct request_queue *q) |
941 | { | |
bc1c1169 JA |
942 | if (q) |
943 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
944 | } |
945 | ||
2fdd82bd | 946 | void elv_register(struct elevator_type *e) |
1da177e4 | 947 | { |
1ffb96c5 | 948 | char *def = ""; |
2a12dcd7 JA |
949 | |
950 | spin_lock(&elv_list_lock); | |
ce524497 | 951 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 952 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 953 | spin_unlock(&elv_list_lock); |
1da177e4 | 954 | |
5f003976 ND |
955 | if (!strcmp(e->elevator_name, chosen_elevator) || |
956 | (!*chosen_elevator && | |
957 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
958 | def = " (default)"; |
959 | ||
4eb166d9 JA |
960 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
961 | def); | |
1da177e4 LT |
962 | } |
963 | EXPORT_SYMBOL_GPL(elv_register); | |
964 | ||
965 | void elv_unregister(struct elevator_type *e) | |
966 | { | |
83521d3e CH |
967 | struct task_struct *g, *p; |
968 | ||
969 | /* | |
970 | * Iterate every thread in the process to remove the io contexts. | |
971 | */ | |
e17a9489 AV |
972 | if (e->ops.trim) { |
973 | read_lock(&tasklist_lock); | |
974 | do_each_thread(g, p) { | |
975 | task_lock(p); | |
2d8f6131 ON |
976 | if (p->io_context) |
977 | e->ops.trim(p->io_context); | |
e17a9489 AV |
978 | task_unlock(p); |
979 | } while_each_thread(g, p); | |
980 | read_unlock(&tasklist_lock); | |
981 | } | |
83521d3e | 982 | |
2a12dcd7 | 983 | spin_lock(&elv_list_lock); |
1da177e4 | 984 | list_del_init(&e->list); |
2a12dcd7 | 985 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
986 | } |
987 | EXPORT_SYMBOL_GPL(elv_unregister); | |
988 | ||
989 | /* | |
990 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
991 | * we don't free the old io scheduler, before we have allocated what we | |
992 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 993 | * one, if the new one fails init for some reason. |
1da177e4 | 994 | */ |
165125e1 | 995 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 996 | { |
b374d18a | 997 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 998 | void *data; |
1da177e4 | 999 | |
cb98fc8b TH |
1000 | /* |
1001 | * Allocate new elevator | |
1002 | */ | |
b5deef90 | 1003 | e = elevator_alloc(q, new_e); |
1da177e4 | 1004 | if (!e) |
3d1ab40f | 1005 | return 0; |
1da177e4 | 1006 | |
bc1c1169 JA |
1007 | data = elevator_init_queue(q, e); |
1008 | if (!data) { | |
1009 | kobject_put(&e->kobj); | |
1010 | return 0; | |
1011 | } | |
1012 | ||
1da177e4 | 1013 | /* |
cb98fc8b | 1014 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1015 | */ |
cb98fc8b | 1016 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1017 | elv_quiesce_start(q); |
cb98fc8b | 1018 | |
1da177e4 | 1019 | /* |
bc1c1169 | 1020 | * Remember old elevator. |
1da177e4 | 1021 | */ |
1da177e4 LT |
1022 | old_elevator = q->elevator; |
1023 | ||
1da177e4 LT |
1024 | /* |
1025 | * attach and start new elevator | |
1026 | */ | |
bc1c1169 JA |
1027 | elevator_attach(q, e, data); |
1028 | ||
1029 | spin_unlock_irq(q->queue_lock); | |
1030 | ||
1031 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1032 | |
1033 | if (elv_register_queue(q)) | |
1034 | goto fail_register; | |
1035 | ||
1036 | /* | |
cb98fc8b | 1037 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1038 | */ |
1039 | elevator_exit(old_elevator); | |
75ad23bc | 1040 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1041 | elv_quiesce_end(q); |
75ad23bc NP |
1042 | spin_unlock_irq(q->queue_lock); |
1043 | ||
4722dc52 AB |
1044 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1045 | ||
3d1ab40f | 1046 | return 1; |
1da177e4 LT |
1047 | |
1048 | fail_register: | |
1049 | /* | |
1050 | * switch failed, exit the new io scheduler and reattach the old | |
1051 | * one again (along with re-adding the sysfs dir) | |
1052 | */ | |
1053 | elevator_exit(e); | |
1da177e4 LT |
1054 | q->elevator = old_elevator; |
1055 | elv_register_queue(q); | |
75ad23bc NP |
1056 | |
1057 | spin_lock_irq(q->queue_lock); | |
1058 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1059 | spin_unlock_irq(q->queue_lock); | |
1060 | ||
3d1ab40f | 1061 | return 0; |
1da177e4 LT |
1062 | } |
1063 | ||
165125e1 JA |
1064 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1065 | size_t count) | |
1da177e4 LT |
1066 | { |
1067 | char elevator_name[ELV_NAME_MAX]; | |
1068 | struct elevator_type *e; | |
1069 | ||
cd43e26f MP |
1070 | if (!q->elevator) |
1071 | return count; | |
1072 | ||
ee2e992c LZ |
1073 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1074 | strstrip(elevator_name); | |
1da177e4 LT |
1075 | |
1076 | e = elevator_get(elevator_name); | |
1077 | if (!e) { | |
1078 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1079 | return -EINVAL; | |
1080 | } | |
1081 | ||
2ca7d93b ND |
1082 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1083 | elevator_put(e); | |
1da177e4 | 1084 | return count; |
2ca7d93b | 1085 | } |
1da177e4 | 1086 | |
3d1ab40f | 1087 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1088 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1089 | elevator_name); | |
1da177e4 LT |
1090 | return count; |
1091 | } | |
1092 | ||
165125e1 | 1093 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1094 | { |
b374d18a | 1095 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1096 | struct elevator_type *elv; |
70cee26e | 1097 | struct elevator_type *__e; |
1da177e4 LT |
1098 | int len = 0; |
1099 | ||
cd43e26f MP |
1100 | if (!q->elevator) |
1101 | return sprintf(name, "none\n"); | |
1102 | ||
1103 | elv = e->elevator_type; | |
1104 | ||
2a12dcd7 | 1105 | spin_lock(&elv_list_lock); |
70cee26e | 1106 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1107 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1108 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1109 | else | |
1110 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1111 | } | |
2a12dcd7 | 1112 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1113 | |
1114 | len += sprintf(len+name, "\n"); | |
1115 | return len; | |
1116 | } | |
1117 | ||
165125e1 JA |
1118 | struct request *elv_rb_former_request(struct request_queue *q, |
1119 | struct request *rq) | |
2e662b65 JA |
1120 | { |
1121 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1122 | ||
1123 | if (rbprev) | |
1124 | return rb_entry_rq(rbprev); | |
1125 | ||
1126 | return NULL; | |
1127 | } | |
2e662b65 JA |
1128 | EXPORT_SYMBOL(elv_rb_former_request); |
1129 | ||
165125e1 JA |
1130 | struct request *elv_rb_latter_request(struct request_queue *q, |
1131 | struct request *rq) | |
2e662b65 JA |
1132 | { |
1133 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1134 | ||
1135 | if (rbnext) | |
1136 | return rb_entry_rq(rbnext); | |
1137 | ||
1138 | return NULL; | |
1139 | } | |
2e662b65 | 1140 | EXPORT_SYMBOL(elv_rb_latter_request); |