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 | */ | |
1f98a13f JA |
82 | if (bio_rw_flagged(bio, BIO_RW_DISCARD) != |
83 | bio_rw_flagged(rq->bio, BIO_RW_DISCARD)) | |
e17fc0a1 DW |
84 | return 0; |
85 | ||
1da177e4 LT |
86 | /* |
87 | * different data direction or already started, don't merge | |
88 | */ | |
89 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
90 | return 0; | |
91 | ||
92 | /* | |
da775265 | 93 | * must be same device and not a special request |
1da177e4 | 94 | */ |
bb4067e3 | 95 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
96 | return 0; |
97 | ||
7ba1ba12 MP |
98 | /* |
99 | * only merge integrity protected bio into ditto rq | |
100 | */ | |
101 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
102 | return 0; | |
103 | ||
da775265 JA |
104 | if (!elv_iosched_allow_merge(rq, bio)) |
105 | return 0; | |
1da177e4 | 106 | |
da775265 | 107 | return 1; |
1da177e4 LT |
108 | } |
109 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
110 | ||
769db45b | 111 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
112 | { |
113 | int ret = ELEVATOR_NO_MERGE; | |
114 | ||
115 | /* | |
116 | * we can merge and sequence is ok, check if it's possible | |
117 | */ | |
118 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 119 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 120 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 121 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
122 | ret = ELEVATOR_FRONT_MERGE; |
123 | } | |
124 | ||
125 | return ret; | |
126 | } | |
1da177e4 | 127 | |
1da177e4 LT |
128 | static struct elevator_type *elevator_find(const char *name) |
129 | { | |
a22b169d | 130 | struct elevator_type *e; |
1da177e4 | 131 | |
70cee26e | 132 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
133 | if (!strcmp(e->elevator_name, name)) |
134 | return e; | |
1da177e4 | 135 | } |
1da177e4 | 136 | |
a22b169d | 137 | return NULL; |
1da177e4 LT |
138 | } |
139 | ||
140 | static void elevator_put(struct elevator_type *e) | |
141 | { | |
142 | module_put(e->elevator_owner); | |
143 | } | |
144 | ||
145 | static struct elevator_type *elevator_get(const char *name) | |
146 | { | |
2824bc93 | 147 | struct elevator_type *e; |
1da177e4 | 148 | |
2a12dcd7 | 149 | spin_lock(&elv_list_lock); |
2824bc93 TH |
150 | |
151 | e = elevator_find(name); | |
e1640949 JA |
152 | if (!e) { |
153 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
154 | ||
155 | spin_unlock(&elv_list_lock); | |
156 | ||
492af635 | 157 | sprintf(elv, "%s-iosched", name); |
e1640949 | 158 | |
e180f594 | 159 | request_module("%s", elv); |
e1640949 JA |
160 | spin_lock(&elv_list_lock); |
161 | e = elevator_find(name); | |
162 | } | |
163 | ||
2824bc93 TH |
164 | if (e && !try_module_get(e->elevator_owner)) |
165 | e = NULL; | |
166 | ||
2a12dcd7 | 167 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
168 | |
169 | return e; | |
170 | } | |
171 | ||
165125e1 JA |
172 | static void *elevator_init_queue(struct request_queue *q, |
173 | struct elevator_queue *eq) | |
1da177e4 | 174 | { |
bb37b94c | 175 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 176 | } |
1da177e4 | 177 | |
165125e1 | 178 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
179 | void *data) |
180 | { | |
1da177e4 | 181 | q->elevator = eq; |
bc1c1169 | 182 | eq->elevator_data = data; |
1da177e4 LT |
183 | } |
184 | ||
185 | static char chosen_elevator[16]; | |
186 | ||
5f003976 | 187 | static int __init elevator_setup(char *str) |
1da177e4 | 188 | { |
752a3b79 CE |
189 | /* |
190 | * Be backwards-compatible with previous kernels, so users | |
191 | * won't get the wrong elevator. | |
192 | */ | |
492af635 | 193 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 194 | return 1; |
1da177e4 LT |
195 | } |
196 | ||
197 | __setup("elevator=", elevator_setup); | |
198 | ||
3d1ab40f AV |
199 | static struct kobj_type elv_ktype; |
200 | ||
b374d18a | 201 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 202 | struct elevator_type *e) |
3d1ab40f | 203 | { |
b374d18a | 204 | struct elevator_queue *eq; |
9817064b JA |
205 | int i; |
206 | ||
b374d18a | 207 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
208 | if (unlikely(!eq)) |
209 | goto err; | |
210 | ||
9817064b JA |
211 | eq->ops = &e->ops; |
212 | eq->elevator_type = e; | |
f9cb074b | 213 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
214 | mutex_init(&eq->sysfs_lock); |
215 | ||
b5deef90 JA |
216 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
217 | GFP_KERNEL, q->node); | |
9817064b JA |
218 | if (!eq->hash) |
219 | goto err; | |
220 | ||
221 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
222 | INIT_HLIST_HEAD(&eq->hash[i]); | |
223 | ||
3d1ab40f | 224 | return eq; |
9817064b JA |
225 | err: |
226 | kfree(eq); | |
227 | elevator_put(e); | |
228 | return NULL; | |
3d1ab40f AV |
229 | } |
230 | ||
231 | static void elevator_release(struct kobject *kobj) | |
232 | { | |
b374d18a | 233 | struct elevator_queue *e; |
9817064b | 234 | |
b374d18a | 235 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 236 | elevator_put(e->elevator_type); |
9817064b | 237 | kfree(e->hash); |
3d1ab40f AV |
238 | kfree(e); |
239 | } | |
240 | ||
165125e1 | 241 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
242 | { |
243 | struct elevator_type *e = NULL; | |
244 | struct elevator_queue *eq; | |
245 | int ret = 0; | |
bc1c1169 | 246 | void *data; |
1da177e4 | 247 | |
cb98fc8b TH |
248 | INIT_LIST_HEAD(&q->queue_head); |
249 | q->last_merge = NULL; | |
250 | q->end_sector = 0; | |
251 | q->boundary_rq = NULL; | |
cb98fc8b | 252 | |
4eb166d9 JA |
253 | if (name) { |
254 | e = elevator_get(name); | |
255 | if (!e) | |
256 | return -EINVAL; | |
257 | } | |
1da177e4 | 258 | |
4eb166d9 JA |
259 | if (!e && *chosen_elevator) { |
260 | e = elevator_get(chosen_elevator); | |
261 | if (!e) | |
262 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
263 | chosen_elevator); | |
264 | } | |
248d5ca5 | 265 | |
4eb166d9 JA |
266 | if (!e) { |
267 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
268 | if (!e) { | |
269 | printk(KERN_ERR | |
270 | "Default I/O scheduler not found. " \ | |
271 | "Using noop.\n"); | |
272 | e = elevator_get("noop"); | |
273 | } | |
5f003976 ND |
274 | } |
275 | ||
b5deef90 | 276 | eq = elevator_alloc(q, e); |
3d1ab40f | 277 | if (!eq) |
1da177e4 | 278 | return -ENOMEM; |
1da177e4 | 279 | |
bc1c1169 JA |
280 | data = elevator_init_queue(q, eq); |
281 | if (!data) { | |
3d1ab40f | 282 | kobject_put(&eq->kobj); |
bc1c1169 JA |
283 | return -ENOMEM; |
284 | } | |
1da177e4 | 285 | |
bc1c1169 | 286 | elevator_attach(q, eq, data); |
1da177e4 LT |
287 | return ret; |
288 | } | |
2e662b65 JA |
289 | EXPORT_SYMBOL(elevator_init); |
290 | ||
b374d18a | 291 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 292 | { |
3d1ab40f | 293 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
294 | if (e->ops->elevator_exit_fn) |
295 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
296 | e->ops = NULL; |
297 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 298 | |
3d1ab40f | 299 | kobject_put(&e->kobj); |
1da177e4 | 300 | } |
2e662b65 JA |
301 | EXPORT_SYMBOL(elevator_exit); |
302 | ||
9817064b JA |
303 | static inline void __elv_rqhash_del(struct request *rq) |
304 | { | |
305 | hlist_del_init(&rq->hash); | |
306 | } | |
307 | ||
165125e1 | 308 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
309 | { |
310 | if (ELV_ON_HASH(rq)) | |
311 | __elv_rqhash_del(rq); | |
312 | } | |
313 | ||
165125e1 | 314 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 315 | { |
b374d18a | 316 | struct elevator_queue *e = q->elevator; |
9817064b JA |
317 | |
318 | BUG_ON(ELV_ON_HASH(rq)); | |
319 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
320 | } | |
321 | ||
165125e1 | 322 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
323 | { |
324 | __elv_rqhash_del(rq); | |
325 | elv_rqhash_add(q, rq); | |
326 | } | |
327 | ||
165125e1 | 328 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 329 | { |
b374d18a | 330 | struct elevator_queue *e = q->elevator; |
9817064b JA |
331 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
332 | struct hlist_node *entry, *next; | |
333 | struct request *rq; | |
334 | ||
335 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
336 | BUG_ON(!ELV_ON_HASH(rq)); | |
337 | ||
338 | if (unlikely(!rq_mergeable(rq))) { | |
339 | __elv_rqhash_del(rq); | |
340 | continue; | |
341 | } | |
342 | ||
343 | if (rq_hash_key(rq) == offset) | |
344 | return rq; | |
345 | } | |
346 | ||
347 | return NULL; | |
348 | } | |
349 | ||
2e662b65 JA |
350 | /* |
351 | * RB-tree support functions for inserting/lookup/removal of requests | |
352 | * in a sorted RB tree. | |
353 | */ | |
354 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
355 | { | |
356 | struct rb_node **p = &root->rb_node; | |
357 | struct rb_node *parent = NULL; | |
358 | struct request *__rq; | |
359 | ||
360 | while (*p) { | |
361 | parent = *p; | |
362 | __rq = rb_entry(parent, struct request, rb_node); | |
363 | ||
83096ebf | 364 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 365 | p = &(*p)->rb_left; |
83096ebf | 366 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
367 | p = &(*p)->rb_right; |
368 | else | |
369 | return __rq; | |
370 | } | |
371 | ||
372 | rb_link_node(&rq->rb_node, parent, p); | |
373 | rb_insert_color(&rq->rb_node, root); | |
374 | return NULL; | |
375 | } | |
2e662b65 JA |
376 | EXPORT_SYMBOL(elv_rb_add); |
377 | ||
378 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
379 | { | |
380 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
381 | rb_erase(&rq->rb_node, root); | |
382 | RB_CLEAR_NODE(&rq->rb_node); | |
383 | } | |
2e662b65 JA |
384 | EXPORT_SYMBOL(elv_rb_del); |
385 | ||
386 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
387 | { | |
388 | struct rb_node *n = root->rb_node; | |
389 | struct request *rq; | |
390 | ||
391 | while (n) { | |
392 | rq = rb_entry(n, struct request, rb_node); | |
393 | ||
83096ebf | 394 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 395 | n = n->rb_left; |
83096ebf | 396 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
397 | n = n->rb_right; |
398 | else | |
399 | return rq; | |
400 | } | |
401 | ||
402 | return NULL; | |
403 | } | |
2e662b65 JA |
404 | EXPORT_SYMBOL(elv_rb_find); |
405 | ||
8922e16c TH |
406 | /* |
407 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 408 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 409 | * specific elevators. |
8922e16c | 410 | */ |
165125e1 | 411 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
412 | { |
413 | sector_t boundary; | |
8922e16c | 414 | struct list_head *entry; |
4eb166d9 | 415 | int stop_flags; |
8922e16c | 416 | |
06b86245 TH |
417 | if (q->last_merge == rq) |
418 | q->last_merge = NULL; | |
9817064b JA |
419 | |
420 | elv_rqhash_del(q, rq); | |
421 | ||
15853af9 | 422 | q->nr_sorted--; |
06b86245 | 423 | |
1b47f531 | 424 | boundary = q->end_sector; |
4eb166d9 | 425 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
426 | list_for_each_prev(entry, &q->queue_head) { |
427 | struct request *pos = list_entry_rq(entry); | |
428 | ||
e17fc0a1 DW |
429 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
430 | break; | |
783660b2 JA |
431 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
432 | break; | |
4eb166d9 | 433 | if (pos->cmd_flags & stop_flags) |
8922e16c | 434 | break; |
83096ebf TH |
435 | if (blk_rq_pos(rq) >= boundary) { |
436 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
437 | continue; |
438 | } else { | |
83096ebf | 439 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
440 | break; |
441 | } | |
83096ebf | 442 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
443 | break; |
444 | } | |
445 | ||
446 | list_add(&rq->queuelist, entry); | |
447 | } | |
2e662b65 JA |
448 | EXPORT_SYMBOL(elv_dispatch_sort); |
449 | ||
9817064b | 450 | /* |
2e662b65 JA |
451 | * Insert rq into dispatch queue of q. Queue lock must be held on |
452 | * entry. rq is added to the back of the dispatch queue. To be used by | |
453 | * specific elevators. | |
9817064b JA |
454 | */ |
455 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
456 | { | |
457 | if (q->last_merge == rq) | |
458 | q->last_merge = NULL; | |
459 | ||
460 | elv_rqhash_del(q, rq); | |
461 | ||
462 | q->nr_sorted--; | |
463 | ||
464 | q->end_sector = rq_end_sector(rq); | |
465 | q->boundary_rq = rq; | |
466 | list_add_tail(&rq->queuelist, &q->queue_head); | |
467 | } | |
2e662b65 JA |
468 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
469 | ||
165125e1 | 470 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 471 | { |
b374d18a | 472 | struct elevator_queue *e = q->elevator; |
9817064b | 473 | struct request *__rq; |
06b86245 TH |
474 | int ret; |
475 | ||
9817064b JA |
476 | /* |
477 | * First try one-hit cache. | |
478 | */ | |
06b86245 TH |
479 | if (q->last_merge) { |
480 | ret = elv_try_merge(q->last_merge, bio); | |
481 | if (ret != ELEVATOR_NO_MERGE) { | |
482 | *req = q->last_merge; | |
483 | return ret; | |
484 | } | |
485 | } | |
1da177e4 | 486 | |
ac9fafa1 AB |
487 | if (blk_queue_nomerges(q)) |
488 | return ELEVATOR_NO_MERGE; | |
489 | ||
9817064b JA |
490 | /* |
491 | * See if our hash lookup can find a potential backmerge. | |
492 | */ | |
493 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
494 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
495 | *req = __rq; | |
496 | return ELEVATOR_BACK_MERGE; | |
497 | } | |
498 | ||
1da177e4 LT |
499 | if (e->ops->elevator_merge_fn) |
500 | return e->ops->elevator_merge_fn(q, req, bio); | |
501 | ||
502 | return ELEVATOR_NO_MERGE; | |
503 | } | |
504 | ||
165125e1 | 505 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 506 | { |
b374d18a | 507 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
508 | |
509 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 510 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 511 | |
2e662b65 JA |
512 | if (type == ELEVATOR_BACK_MERGE) |
513 | elv_rqhash_reposition(q, rq); | |
9817064b | 514 | |
06b86245 | 515 | q->last_merge = rq; |
1da177e4 LT |
516 | } |
517 | ||
165125e1 | 518 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
519 | struct request *next) |
520 | { | |
b374d18a | 521 | struct elevator_queue *e = q->elevator; |
1da177e4 | 522 | |
1da177e4 LT |
523 | if (e->ops->elevator_merge_req_fn) |
524 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 525 | |
9817064b JA |
526 | elv_rqhash_reposition(q, rq); |
527 | elv_rqhash_del(q, next); | |
528 | ||
529 | q->nr_sorted--; | |
06b86245 | 530 | q->last_merge = rq; |
1da177e4 LT |
531 | } |
532 | ||
165125e1 | 533 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 534 | { |
1da177e4 LT |
535 | /* |
536 | * it already went through dequeue, we need to decrement the | |
537 | * in_flight count again | |
538 | */ | |
8922e16c | 539 | if (blk_account_rq(rq)) { |
0a7ae2ff | 540 | q->in_flight[rq_is_sync(rq)]--; |
cad97516 JA |
541 | if (blk_sorted_rq(rq)) |
542 | elv_deactivate_rq(q, rq); | |
8922e16c | 543 | } |
1da177e4 | 544 | |
4aff5e23 | 545 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 546 | |
30e9656c | 547 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
548 | } |
549 | ||
26308eab | 550 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
551 | { |
552 | static int printed; | |
553 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
554 | ; | |
555 | if (q->nr_sorted == 0) | |
556 | return; | |
557 | if (printed++ < 10) { | |
558 | printk(KERN_ERR "%s: forced dispatching is broken " | |
559 | "(nr_sorted=%u), please report this\n", | |
560 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
561 | } | |
562 | } | |
563 | ||
6c7e8cee JA |
564 | /* |
565 | * Call with queue lock held, interrupts disabled | |
566 | */ | |
f600abe2 | 567 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 568 | { |
cd43e26f MP |
569 | if (!q->elevator) |
570 | return; | |
571 | ||
6c7e8cee JA |
572 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
573 | ||
574 | /* | |
575 | * make sure we don't have any requests in flight | |
576 | */ | |
577 | elv_drain_elevator(q); | |
578 | while (q->rq.elvpriv) { | |
a7f55792 | 579 | __blk_run_queue(q); |
6c7e8cee JA |
580 | spin_unlock_irq(q->queue_lock); |
581 | msleep(10); | |
582 | spin_lock_irq(q->queue_lock); | |
583 | elv_drain_elevator(q); | |
584 | } | |
585 | } | |
586 | ||
f600abe2 | 587 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
588 | { |
589 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
590 | } | |
591 | ||
165125e1 | 592 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 593 | { |
797e7dbb TH |
594 | struct list_head *pos; |
595 | unsigned ordseq; | |
dac07ec1 | 596 | int unplug_it = 1; |
797e7dbb | 597 | |
5f3ea37c | 598 | trace_block_rq_insert(q, rq); |
2056a782 | 599 | |
1da177e4 LT |
600 | rq->q = q; |
601 | ||
8922e16c TH |
602 | switch (where) { |
603 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 604 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
605 | |
606 | list_add(&rq->queuelist, &q->queue_head); | |
607 | break; | |
608 | ||
609 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 610 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 611 | elv_drain_elevator(q); |
8922e16c TH |
612 | list_add_tail(&rq->queuelist, &q->queue_head); |
613 | /* | |
614 | * We kick the queue here for the following reasons. | |
615 | * - The elevator might have returned NULL previously | |
616 | * to delay requests and returned them now. As the | |
617 | * queue wasn't empty before this request, ll_rw_blk | |
618 | * won't run the queue on return, resulting in hang. | |
619 | * - Usually, back inserted requests won't be merged | |
620 | * with anything. There's no point in delaying queue | |
621 | * processing. | |
622 | */ | |
a7f55792 | 623 | __blk_run_queue(q); |
8922e16c TH |
624 | break; |
625 | ||
626 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 627 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 628 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 629 | q->nr_sorted++; |
9817064b JA |
630 | if (rq_mergeable(rq)) { |
631 | elv_rqhash_add(q, rq); | |
632 | if (!q->last_merge) | |
633 | q->last_merge = rq; | |
634 | } | |
635 | ||
ca23509f TH |
636 | /* |
637 | * Some ioscheds (cfq) run q->request_fn directly, so | |
638 | * rq cannot be accessed after calling | |
639 | * elevator_add_req_fn. | |
640 | */ | |
641 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
642 | break; |
643 | ||
797e7dbb TH |
644 | case ELEVATOR_INSERT_REQUEUE: |
645 | /* | |
646 | * If ordered flush isn't in progress, we do front | |
647 | * insertion; otherwise, requests should be requeued | |
648 | * in ordseq order. | |
649 | */ | |
4aff5e23 | 650 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 651 | |
95543179 LV |
652 | /* |
653 | * Most requeues happen because of a busy condition, | |
654 | * don't force unplug of the queue for that case. | |
655 | */ | |
656 | unplug_it = 0; | |
657 | ||
797e7dbb TH |
658 | if (q->ordseq == 0) { |
659 | list_add(&rq->queuelist, &q->queue_head); | |
660 | break; | |
661 | } | |
662 | ||
663 | ordseq = blk_ordered_req_seq(rq); | |
664 | ||
665 | list_for_each(pos, &q->queue_head) { | |
666 | struct request *pos_rq = list_entry_rq(pos); | |
667 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
668 | break; | |
669 | } | |
670 | ||
671 | list_add_tail(&rq->queuelist, pos); | |
672 | break; | |
673 | ||
8922e16c TH |
674 | default: |
675 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 676 | __func__, where); |
8922e16c TH |
677 | BUG(); |
678 | } | |
679 | ||
dac07ec1 | 680 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 681 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
0a7ae2ff | 682 | - queue_in_flight(q); |
8922e16c TH |
683 | |
684 | if (nrq >= q->unplug_thresh) | |
685 | __generic_unplug_device(q); | |
686 | } | |
1da177e4 LT |
687 | } |
688 | ||
165125e1 | 689 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
690 | int plug) |
691 | { | |
692 | if (q->ordcolor) | |
4aff5e23 | 693 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 694 | |
4aff5e23 | 695 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
696 | /* |
697 | * toggle ordered color | |
698 | */ | |
699 | if (blk_barrier_rq(rq)) | |
700 | q->ordcolor ^= 1; | |
701 | ||
702 | /* | |
703 | * barriers implicitly indicate back insertion | |
704 | */ | |
705 | if (where == ELEVATOR_INSERT_SORT) | |
706 | where = ELEVATOR_INSERT_BACK; | |
707 | ||
708 | /* | |
709 | * this request is scheduling boundary, update | |
710 | * end_sector | |
711 | */ | |
e17fc0a1 | 712 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
713 | q->end_sector = rq_end_sector(rq); |
714 | q->boundary_rq = rq; | |
715 | } | |
4eb166d9 JA |
716 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
717 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
718 | where = ELEVATOR_INSERT_BACK; |
719 | ||
720 | if (plug) | |
721 | blk_plug_device(q); | |
722 | ||
723 | elv_insert(q, rq, where); | |
724 | } | |
2e662b65 JA |
725 | EXPORT_SYMBOL(__elv_add_request); |
726 | ||
165125e1 | 727 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
728 | int plug) |
729 | { | |
730 | unsigned long flags; | |
731 | ||
732 | spin_lock_irqsave(q->queue_lock, flags); | |
733 | __elv_add_request(q, rq, where, plug); | |
734 | spin_unlock_irqrestore(q->queue_lock, flags); | |
735 | } | |
2e662b65 JA |
736 | EXPORT_SYMBOL(elv_add_request); |
737 | ||
165125e1 | 738 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 739 | { |
b374d18a | 740 | struct elevator_queue *e = q->elevator; |
1da177e4 | 741 | |
8922e16c TH |
742 | if (!list_empty(&q->queue_head)) |
743 | return 0; | |
744 | ||
1da177e4 LT |
745 | if (e->ops->elevator_queue_empty_fn) |
746 | return e->ops->elevator_queue_empty_fn(q); | |
747 | ||
8922e16c | 748 | return 1; |
1da177e4 | 749 | } |
2e662b65 JA |
750 | EXPORT_SYMBOL(elv_queue_empty); |
751 | ||
165125e1 | 752 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 753 | { |
b374d18a | 754 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
755 | |
756 | if (e->ops->elevator_latter_req_fn) | |
757 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
758 | return NULL; |
759 | } | |
760 | ||
165125e1 | 761 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 762 | { |
b374d18a | 763 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
764 | |
765 | if (e->ops->elevator_former_req_fn) | |
766 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
767 | return NULL; |
768 | } | |
769 | ||
165125e1 | 770 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 771 | { |
b374d18a | 772 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
773 | |
774 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 775 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
776 | |
777 | rq->elevator_private = NULL; | |
778 | return 0; | |
779 | } | |
780 | ||
165125e1 | 781 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 782 | { |
b374d18a | 783 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
784 | |
785 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 786 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
787 | } |
788 | ||
165125e1 | 789 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 790 | { |
b374d18a | 791 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
792 | |
793 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 794 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
795 | |
796 | return ELV_MQUEUE_MAY; | |
797 | } | |
798 | ||
11914a53 MA |
799 | void elv_abort_queue(struct request_queue *q) |
800 | { | |
801 | struct request *rq; | |
802 | ||
803 | while (!list_empty(&q->queue_head)) { | |
804 | rq = list_entry_rq(q->queue_head.next); | |
805 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 806 | trace_block_rq_abort(q, rq); |
53c663ce KU |
807 | /* |
808 | * Mark this request as started so we don't trigger | |
809 | * any debug logic in the end I/O path. | |
810 | */ | |
811 | blk_start_request(rq); | |
40cbbb78 | 812 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
813 | } |
814 | } | |
815 | EXPORT_SYMBOL(elv_abort_queue); | |
816 | ||
165125e1 | 817 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 818 | { |
b374d18a | 819 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
820 | |
821 | /* | |
822 | * request is released from the driver, io must be done | |
823 | */ | |
8922e16c | 824 | if (blk_account_rq(rq)) { |
0a7ae2ff | 825 | q->in_flight[rq_is_sync(rq)]--; |
1bc691d3 TH |
826 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
827 | e->ops->elevator_completed_req_fn(q, rq); | |
828 | } | |
797e7dbb | 829 | |
1bc691d3 TH |
830 | /* |
831 | * Check if the queue is waiting for fs requests to be | |
832 | * drained for flush sequence. | |
833 | */ | |
834 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
835 | struct request *next = NULL; |
836 | ||
837 | if (!list_empty(&q->queue_head)) | |
838 | next = list_entry_rq(q->queue_head.next); | |
839 | ||
0a7ae2ff | 840 | if (!queue_in_flight(q) && |
797e7dbb | 841 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 842 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 843 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
a7f55792 | 844 | __blk_run_queue(q); |
797e7dbb | 845 | } |
8922e16c | 846 | } |
1da177e4 LT |
847 | } |
848 | ||
3d1ab40f AV |
849 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
850 | ||
851 | static ssize_t | |
852 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 853 | { |
3d1ab40f | 854 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 855 | struct elevator_queue *e; |
3d1ab40f AV |
856 | ssize_t error; |
857 | ||
858 | if (!entry->show) | |
859 | return -EIO; | |
860 | ||
b374d18a | 861 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
862 | mutex_lock(&e->sysfs_lock); |
863 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
864 | mutex_unlock(&e->sysfs_lock); | |
865 | return error; | |
866 | } | |
1da177e4 | 867 | |
3d1ab40f AV |
868 | static ssize_t |
869 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
870 | const char *page, size_t length) | |
871 | { | |
3d1ab40f | 872 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 873 | struct elevator_queue *e; |
3d1ab40f | 874 | ssize_t error; |
1da177e4 | 875 | |
3d1ab40f AV |
876 | if (!entry->store) |
877 | return -EIO; | |
1da177e4 | 878 | |
b374d18a | 879 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
880 | mutex_lock(&e->sysfs_lock); |
881 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
882 | mutex_unlock(&e->sysfs_lock); | |
883 | return error; | |
884 | } | |
885 | ||
886 | static struct sysfs_ops elv_sysfs_ops = { | |
887 | .show = elv_attr_show, | |
888 | .store = elv_attr_store, | |
889 | }; | |
890 | ||
891 | static struct kobj_type elv_ktype = { | |
892 | .sysfs_ops = &elv_sysfs_ops, | |
893 | .release = elevator_release, | |
894 | }; | |
895 | ||
896 | int elv_register_queue(struct request_queue *q) | |
897 | { | |
b374d18a | 898 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
899 | int error; |
900 | ||
b2d6db58 | 901 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 902 | if (!error) { |
e572ec7e | 903 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 904 | if (attr) { |
e572ec7e AV |
905 | while (attr->attr.name) { |
906 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 907 | break; |
e572ec7e | 908 | attr++; |
3d1ab40f AV |
909 | } |
910 | } | |
911 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
912 | } | |
913 | return error; | |
1da177e4 LT |
914 | } |
915 | ||
b374d18a | 916 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
917 | { |
918 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
919 | kobject_del(&e->kobj); | |
920 | } | |
921 | ||
1da177e4 LT |
922 | void elv_unregister_queue(struct request_queue *q) |
923 | { | |
bc1c1169 JA |
924 | if (q) |
925 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
926 | } |
927 | ||
2fdd82bd | 928 | void elv_register(struct elevator_type *e) |
1da177e4 | 929 | { |
1ffb96c5 | 930 | char *def = ""; |
2a12dcd7 JA |
931 | |
932 | spin_lock(&elv_list_lock); | |
ce524497 | 933 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 934 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 935 | spin_unlock(&elv_list_lock); |
1da177e4 | 936 | |
5f003976 ND |
937 | if (!strcmp(e->elevator_name, chosen_elevator) || |
938 | (!*chosen_elevator && | |
939 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
940 | def = " (default)"; |
941 | ||
4eb166d9 JA |
942 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
943 | def); | |
1da177e4 LT |
944 | } |
945 | EXPORT_SYMBOL_GPL(elv_register); | |
946 | ||
947 | void elv_unregister(struct elevator_type *e) | |
948 | { | |
83521d3e CH |
949 | struct task_struct *g, *p; |
950 | ||
951 | /* | |
952 | * Iterate every thread in the process to remove the io contexts. | |
953 | */ | |
e17a9489 AV |
954 | if (e->ops.trim) { |
955 | read_lock(&tasklist_lock); | |
956 | do_each_thread(g, p) { | |
957 | task_lock(p); | |
2d8f6131 ON |
958 | if (p->io_context) |
959 | e->ops.trim(p->io_context); | |
e17a9489 AV |
960 | task_unlock(p); |
961 | } while_each_thread(g, p); | |
962 | read_unlock(&tasklist_lock); | |
963 | } | |
83521d3e | 964 | |
2a12dcd7 | 965 | spin_lock(&elv_list_lock); |
1da177e4 | 966 | list_del_init(&e->list); |
2a12dcd7 | 967 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
968 | } |
969 | EXPORT_SYMBOL_GPL(elv_unregister); | |
970 | ||
971 | /* | |
972 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
973 | * we don't free the old io scheduler, before we have allocated what we | |
974 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 975 | * one, if the new one fails init for some reason. |
1da177e4 | 976 | */ |
165125e1 | 977 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 978 | { |
b374d18a | 979 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 980 | void *data; |
1da177e4 | 981 | |
cb98fc8b TH |
982 | /* |
983 | * Allocate new elevator | |
984 | */ | |
b5deef90 | 985 | e = elevator_alloc(q, new_e); |
1da177e4 | 986 | if (!e) |
3d1ab40f | 987 | return 0; |
1da177e4 | 988 | |
bc1c1169 JA |
989 | data = elevator_init_queue(q, e); |
990 | if (!data) { | |
991 | kobject_put(&e->kobj); | |
992 | return 0; | |
993 | } | |
994 | ||
1da177e4 | 995 | /* |
cb98fc8b | 996 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 997 | */ |
cb98fc8b | 998 | spin_lock_irq(q->queue_lock); |
f600abe2 | 999 | elv_quiesce_start(q); |
cb98fc8b | 1000 | |
1da177e4 | 1001 | /* |
bc1c1169 | 1002 | * Remember old elevator. |
1da177e4 | 1003 | */ |
1da177e4 LT |
1004 | old_elevator = q->elevator; |
1005 | ||
1da177e4 LT |
1006 | /* |
1007 | * attach and start new elevator | |
1008 | */ | |
bc1c1169 JA |
1009 | elevator_attach(q, e, data); |
1010 | ||
1011 | spin_unlock_irq(q->queue_lock); | |
1012 | ||
1013 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1014 | |
1015 | if (elv_register_queue(q)) | |
1016 | goto fail_register; | |
1017 | ||
1018 | /* | |
cb98fc8b | 1019 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1020 | */ |
1021 | elevator_exit(old_elevator); | |
75ad23bc | 1022 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1023 | elv_quiesce_end(q); |
75ad23bc NP |
1024 | spin_unlock_irq(q->queue_lock); |
1025 | ||
4722dc52 AB |
1026 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1027 | ||
3d1ab40f | 1028 | return 1; |
1da177e4 LT |
1029 | |
1030 | fail_register: | |
1031 | /* | |
1032 | * switch failed, exit the new io scheduler and reattach the old | |
1033 | * one again (along with re-adding the sysfs dir) | |
1034 | */ | |
1035 | elevator_exit(e); | |
1da177e4 LT |
1036 | q->elevator = old_elevator; |
1037 | elv_register_queue(q); | |
75ad23bc NP |
1038 | |
1039 | spin_lock_irq(q->queue_lock); | |
1040 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1041 | spin_unlock_irq(q->queue_lock); | |
1042 | ||
3d1ab40f | 1043 | return 0; |
1da177e4 LT |
1044 | } |
1045 | ||
165125e1 JA |
1046 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1047 | size_t count) | |
1da177e4 LT |
1048 | { |
1049 | char elevator_name[ELV_NAME_MAX]; | |
1050 | struct elevator_type *e; | |
1051 | ||
cd43e26f MP |
1052 | if (!q->elevator) |
1053 | return count; | |
1054 | ||
ee2e992c | 1055 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 1056 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
1057 | if (!e) { |
1058 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1059 | return -EINVAL; | |
1060 | } | |
1061 | ||
2ca7d93b ND |
1062 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1063 | elevator_put(e); | |
1da177e4 | 1064 | return count; |
2ca7d93b | 1065 | } |
1da177e4 | 1066 | |
3d1ab40f | 1067 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1068 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1069 | elevator_name); | |
1da177e4 LT |
1070 | return count; |
1071 | } | |
1072 | ||
165125e1 | 1073 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1074 | { |
b374d18a | 1075 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1076 | struct elevator_type *elv; |
70cee26e | 1077 | struct elevator_type *__e; |
1da177e4 LT |
1078 | int len = 0; |
1079 | ||
cd43e26f MP |
1080 | if (!q->elevator) |
1081 | return sprintf(name, "none\n"); | |
1082 | ||
1083 | elv = e->elevator_type; | |
1084 | ||
2a12dcd7 | 1085 | spin_lock(&elv_list_lock); |
70cee26e | 1086 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1087 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1088 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1089 | else | |
1090 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1091 | } | |
2a12dcd7 | 1092 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1093 | |
1094 | len += sprintf(len+name, "\n"); | |
1095 | return len; | |
1096 | } | |
1097 | ||
165125e1 JA |
1098 | struct request *elv_rb_former_request(struct request_queue *q, |
1099 | struct request *rq) | |
2e662b65 JA |
1100 | { |
1101 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1102 | ||
1103 | if (rbprev) | |
1104 | return rb_entry_rq(rbprev); | |
1105 | ||
1106 | return NULL; | |
1107 | } | |
2e662b65 JA |
1108 | EXPORT_SYMBOL(elv_rb_former_request); |
1109 | ||
165125e1 JA |
1110 | struct request *elv_rb_latter_request(struct request_queue *q, |
1111 | struct request *rq) | |
2e662b65 JA |
1112 | { |
1113 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1114 | ||
1115 | if (rbnext) | |
1116 | return rb_entry_rq(rbnext); | |
1117 | ||
1118 | return NULL; | |
1119 | } | |
2e662b65 | 1120 | EXPORT_SYMBOL(elv_rb_latter_request); |