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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
29 | #include <linux/bio.h> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
cb98fc8b | 34 | #include <linux/delay.h> |
2056a782 | 35 | #include <linux/blktrace_api.h> |
9817064b | 36 | #include <linux/hash.h> |
1da177e4 LT |
37 | |
38 | #include <asm/uaccess.h> | |
39 | ||
40 | static DEFINE_SPINLOCK(elv_list_lock); | |
41 | static LIST_HEAD(elv_list); | |
42 | ||
9817064b JA |
43 | /* |
44 | * Merge hash stuff. | |
45 | */ | |
46 | static const int elv_hash_shift = 6; | |
47 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
48 | #define ELV_HASH_FN(sec) (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
49 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) | |
50 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
51 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
52 | ||
da775265 JA |
53 | /* |
54 | * Query io scheduler to see if the current process issuing bio may be | |
55 | * merged with rq. | |
56 | */ | |
57 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
58 | { | |
59 | request_queue_t *q = rq->q; | |
60 | elevator_t *e = q->elevator; | |
61 | ||
62 | if (e->ops->elevator_allow_merge_fn) | |
63 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
64 | ||
65 | return 1; | |
66 | } | |
67 | ||
1da177e4 LT |
68 | /* |
69 | * can we safely merge with this request? | |
70 | */ | |
71 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) | |
72 | { | |
73 | if (!rq_mergeable(rq)) | |
74 | return 0; | |
75 | ||
76 | /* | |
77 | * different data direction or already started, don't merge | |
78 | */ | |
79 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
80 | return 0; | |
81 | ||
82 | /* | |
da775265 | 83 | * must be same device and not a special request |
1da177e4 | 84 | */ |
bb4067e3 | 85 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
86 | return 0; |
87 | ||
88 | if (!elv_iosched_allow_merge(rq, bio)) | |
89 | return 0; | |
1da177e4 | 90 | |
da775265 | 91 | return 1; |
1da177e4 LT |
92 | } |
93 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
94 | ||
769db45b | 95 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
96 | { |
97 | int ret = ELEVATOR_NO_MERGE; | |
98 | ||
99 | /* | |
100 | * we can merge and sequence is ok, check if it's possible | |
101 | */ | |
102 | if (elv_rq_merge_ok(__rq, bio)) { | |
103 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
104 | ret = ELEVATOR_BACK_MERGE; | |
105 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
106 | ret = ELEVATOR_FRONT_MERGE; | |
107 | } | |
108 | ||
109 | return ret; | |
110 | } | |
1da177e4 | 111 | |
1da177e4 LT |
112 | static struct elevator_type *elevator_find(const char *name) |
113 | { | |
a22b169d | 114 | struct elevator_type *e; |
1da177e4 | 115 | |
70cee26e | 116 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
117 | if (!strcmp(e->elevator_name, name)) |
118 | return e; | |
1da177e4 | 119 | } |
1da177e4 | 120 | |
a22b169d | 121 | return NULL; |
1da177e4 LT |
122 | } |
123 | ||
124 | static void elevator_put(struct elevator_type *e) | |
125 | { | |
126 | module_put(e->elevator_owner); | |
127 | } | |
128 | ||
129 | static struct elevator_type *elevator_get(const char *name) | |
130 | { | |
2824bc93 | 131 | struct elevator_type *e; |
1da177e4 | 132 | |
2a12dcd7 | 133 | spin_lock(&elv_list_lock); |
2824bc93 TH |
134 | |
135 | e = elevator_find(name); | |
136 | if (e && !try_module_get(e->elevator_owner)) | |
137 | e = NULL; | |
138 | ||
2a12dcd7 | 139 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
140 | |
141 | return e; | |
142 | } | |
143 | ||
bc1c1169 | 144 | static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 | 145 | { |
bb37b94c | 146 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 147 | } |
1da177e4 | 148 | |
bc1c1169 JA |
149 | static void elevator_attach(request_queue_t *q, struct elevator_queue *eq, |
150 | void *data) | |
151 | { | |
1da177e4 | 152 | q->elevator = eq; |
bc1c1169 | 153 | eq->elevator_data = data; |
1da177e4 LT |
154 | } |
155 | ||
156 | static char chosen_elevator[16]; | |
157 | ||
5f003976 | 158 | static int __init elevator_setup(char *str) |
1da177e4 | 159 | { |
752a3b79 CE |
160 | /* |
161 | * Be backwards-compatible with previous kernels, so users | |
162 | * won't get the wrong elevator. | |
163 | */ | |
5f003976 | 164 | if (!strcmp(str, "as")) |
752a3b79 | 165 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 166 | else |
5f003976 | 167 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 168 | return 1; |
1da177e4 LT |
169 | } |
170 | ||
171 | __setup("elevator=", elevator_setup); | |
172 | ||
3d1ab40f AV |
173 | static struct kobj_type elv_ktype; |
174 | ||
b5deef90 | 175 | static elevator_t *elevator_alloc(request_queue_t *q, struct elevator_type *e) |
3d1ab40f | 176 | { |
9817064b JA |
177 | elevator_t *eq; |
178 | int i; | |
179 | ||
b5deef90 | 180 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL, q->node); |
9817064b JA |
181 | if (unlikely(!eq)) |
182 | goto err; | |
183 | ||
184 | memset(eq, 0, sizeof(*eq)); | |
185 | eq->ops = &e->ops; | |
186 | eq->elevator_type = e; | |
187 | kobject_init(&eq->kobj); | |
188 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
189 | eq->kobj.ktype = &elv_ktype; | |
190 | mutex_init(&eq->sysfs_lock); | |
191 | ||
b5deef90 JA |
192 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
193 | GFP_KERNEL, q->node); | |
9817064b JA |
194 | if (!eq->hash) |
195 | goto err; | |
196 | ||
197 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
198 | INIT_HLIST_HEAD(&eq->hash[i]); | |
199 | ||
3d1ab40f | 200 | return eq; |
9817064b JA |
201 | err: |
202 | kfree(eq); | |
203 | elevator_put(e); | |
204 | return NULL; | |
3d1ab40f AV |
205 | } |
206 | ||
207 | static void elevator_release(struct kobject *kobj) | |
208 | { | |
209 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 210 | |
3d1ab40f | 211 | elevator_put(e->elevator_type); |
9817064b | 212 | kfree(e->hash); |
3d1ab40f AV |
213 | kfree(e); |
214 | } | |
215 | ||
1da177e4 LT |
216 | int elevator_init(request_queue_t *q, char *name) |
217 | { | |
218 | struct elevator_type *e = NULL; | |
219 | struct elevator_queue *eq; | |
220 | int ret = 0; | |
bc1c1169 | 221 | void *data; |
1da177e4 | 222 | |
cb98fc8b TH |
223 | INIT_LIST_HEAD(&q->queue_head); |
224 | q->last_merge = NULL; | |
225 | q->end_sector = 0; | |
226 | q->boundary_rq = NULL; | |
cb98fc8b | 227 | |
5f003976 | 228 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
229 | return -EINVAL; |
230 | ||
248d5ca5 ND |
231 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
232 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
233 | ||
234 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
235 | printk("Default I/O scheduler not found, using no-op\n"); | |
236 | e = elevator_get("noop"); | |
5f003976 ND |
237 | } |
238 | ||
b5deef90 | 239 | eq = elevator_alloc(q, e); |
3d1ab40f | 240 | if (!eq) |
1da177e4 | 241 | return -ENOMEM; |
1da177e4 | 242 | |
bc1c1169 JA |
243 | data = elevator_init_queue(q, eq); |
244 | if (!data) { | |
3d1ab40f | 245 | kobject_put(&eq->kobj); |
bc1c1169 JA |
246 | return -ENOMEM; |
247 | } | |
1da177e4 | 248 | |
bc1c1169 | 249 | elevator_attach(q, eq, data); |
1da177e4 LT |
250 | return ret; |
251 | } | |
252 | ||
2e662b65 JA |
253 | EXPORT_SYMBOL(elevator_init); |
254 | ||
1da177e4 LT |
255 | void elevator_exit(elevator_t *e) |
256 | { | |
3d1ab40f | 257 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
258 | if (e->ops->elevator_exit_fn) |
259 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
260 | e->ops = NULL; |
261 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 262 | |
3d1ab40f | 263 | kobject_put(&e->kobj); |
1da177e4 LT |
264 | } |
265 | ||
2e662b65 JA |
266 | EXPORT_SYMBOL(elevator_exit); |
267 | ||
cad97516 JA |
268 | static void elv_activate_rq(request_queue_t *q, struct request *rq) |
269 | { | |
270 | elevator_t *e = q->elevator; | |
271 | ||
272 | if (e->ops->elevator_activate_req_fn) | |
273 | e->ops->elevator_activate_req_fn(q, rq); | |
274 | } | |
275 | ||
276 | static void elv_deactivate_rq(request_queue_t *q, struct request *rq) | |
277 | { | |
278 | elevator_t *e = q->elevator; | |
279 | ||
280 | if (e->ops->elevator_deactivate_req_fn) | |
281 | e->ops->elevator_deactivate_req_fn(q, rq); | |
282 | } | |
283 | ||
9817064b JA |
284 | static inline void __elv_rqhash_del(struct request *rq) |
285 | { | |
286 | hlist_del_init(&rq->hash); | |
287 | } | |
288 | ||
289 | static void elv_rqhash_del(request_queue_t *q, struct request *rq) | |
290 | { | |
291 | if (ELV_ON_HASH(rq)) | |
292 | __elv_rqhash_del(rq); | |
293 | } | |
294 | ||
295 | static void elv_rqhash_add(request_queue_t *q, struct request *rq) | |
296 | { | |
297 | elevator_t *e = q->elevator; | |
298 | ||
299 | BUG_ON(ELV_ON_HASH(rq)); | |
300 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
301 | } | |
302 | ||
303 | static void elv_rqhash_reposition(request_queue_t *q, struct request *rq) | |
304 | { | |
305 | __elv_rqhash_del(rq); | |
306 | elv_rqhash_add(q, rq); | |
307 | } | |
308 | ||
309 | static struct request *elv_rqhash_find(request_queue_t *q, sector_t offset) | |
310 | { | |
311 | elevator_t *e = q->elevator; | |
312 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
313 | struct hlist_node *entry, *next; | |
314 | struct request *rq; | |
315 | ||
316 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
317 | BUG_ON(!ELV_ON_HASH(rq)); | |
318 | ||
319 | if (unlikely(!rq_mergeable(rq))) { | |
320 | __elv_rqhash_del(rq); | |
321 | continue; | |
322 | } | |
323 | ||
324 | if (rq_hash_key(rq) == offset) | |
325 | return rq; | |
326 | } | |
327 | ||
328 | return NULL; | |
329 | } | |
330 | ||
2e662b65 JA |
331 | /* |
332 | * RB-tree support functions for inserting/lookup/removal of requests | |
333 | * in a sorted RB tree. | |
334 | */ | |
335 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
336 | { | |
337 | struct rb_node **p = &root->rb_node; | |
338 | struct rb_node *parent = NULL; | |
339 | struct request *__rq; | |
340 | ||
341 | while (*p) { | |
342 | parent = *p; | |
343 | __rq = rb_entry(parent, struct request, rb_node); | |
344 | ||
345 | if (rq->sector < __rq->sector) | |
346 | p = &(*p)->rb_left; | |
347 | else if (rq->sector > __rq->sector) | |
348 | p = &(*p)->rb_right; | |
349 | else | |
350 | return __rq; | |
351 | } | |
352 | ||
353 | rb_link_node(&rq->rb_node, parent, p); | |
354 | rb_insert_color(&rq->rb_node, root); | |
355 | return NULL; | |
356 | } | |
357 | ||
358 | EXPORT_SYMBOL(elv_rb_add); | |
359 | ||
360 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
361 | { | |
362 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
363 | rb_erase(&rq->rb_node, root); | |
364 | RB_CLEAR_NODE(&rq->rb_node); | |
365 | } | |
366 | ||
367 | EXPORT_SYMBOL(elv_rb_del); | |
368 | ||
369 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
370 | { | |
371 | struct rb_node *n = root->rb_node; | |
372 | struct request *rq; | |
373 | ||
374 | while (n) { | |
375 | rq = rb_entry(n, struct request, rb_node); | |
376 | ||
377 | if (sector < rq->sector) | |
378 | n = n->rb_left; | |
379 | else if (sector > rq->sector) | |
380 | n = n->rb_right; | |
381 | else | |
382 | return rq; | |
383 | } | |
384 | ||
385 | return NULL; | |
386 | } | |
387 | ||
388 | EXPORT_SYMBOL(elv_rb_find); | |
389 | ||
8922e16c TH |
390 | /* |
391 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
2e662b65 JA |
392 | * entry. rq is sort insted into the dispatch queue. To be used by |
393 | * specific elevators. | |
8922e16c | 394 | */ |
1b47f531 | 395 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
396 | { |
397 | sector_t boundary; | |
8922e16c TH |
398 | struct list_head *entry; |
399 | ||
06b86245 TH |
400 | if (q->last_merge == rq) |
401 | q->last_merge = NULL; | |
9817064b JA |
402 | |
403 | elv_rqhash_del(q, rq); | |
404 | ||
15853af9 | 405 | q->nr_sorted--; |
06b86245 | 406 | |
1b47f531 | 407 | boundary = q->end_sector; |
cb19833d | 408 | |
8922e16c TH |
409 | list_for_each_prev(entry, &q->queue_head) { |
410 | struct request *pos = list_entry_rq(entry); | |
411 | ||
783660b2 JA |
412 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
413 | break; | |
4aff5e23 | 414 | if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) |
8922e16c TH |
415 | break; |
416 | if (rq->sector >= boundary) { | |
417 | if (pos->sector < boundary) | |
418 | continue; | |
419 | } else { | |
420 | if (pos->sector >= boundary) | |
421 | break; | |
422 | } | |
423 | if (rq->sector >= pos->sector) | |
424 | break; | |
425 | } | |
426 | ||
427 | list_add(&rq->queuelist, entry); | |
428 | } | |
429 | ||
2e662b65 JA |
430 | EXPORT_SYMBOL(elv_dispatch_sort); |
431 | ||
9817064b | 432 | /* |
2e662b65 JA |
433 | * Insert rq into dispatch queue of q. Queue lock must be held on |
434 | * entry. rq is added to the back of the dispatch queue. To be used by | |
435 | * specific elevators. | |
9817064b JA |
436 | */ |
437 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
438 | { | |
439 | if (q->last_merge == rq) | |
440 | q->last_merge = NULL; | |
441 | ||
442 | elv_rqhash_del(q, rq); | |
443 | ||
444 | q->nr_sorted--; | |
445 | ||
446 | q->end_sector = rq_end_sector(rq); | |
447 | q->boundary_rq = rq; | |
448 | list_add_tail(&rq->queuelist, &q->queue_head); | |
449 | } | |
450 | ||
2e662b65 JA |
451 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
452 | ||
1da177e4 LT |
453 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
454 | { | |
455 | elevator_t *e = q->elevator; | |
9817064b | 456 | struct request *__rq; |
06b86245 TH |
457 | int ret; |
458 | ||
9817064b JA |
459 | /* |
460 | * First try one-hit cache. | |
461 | */ | |
06b86245 TH |
462 | if (q->last_merge) { |
463 | ret = elv_try_merge(q->last_merge, bio); | |
464 | if (ret != ELEVATOR_NO_MERGE) { | |
465 | *req = q->last_merge; | |
466 | return ret; | |
467 | } | |
468 | } | |
1da177e4 | 469 | |
9817064b JA |
470 | /* |
471 | * See if our hash lookup can find a potential backmerge. | |
472 | */ | |
473 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
474 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
475 | *req = __rq; | |
476 | return ELEVATOR_BACK_MERGE; | |
477 | } | |
478 | ||
1da177e4 LT |
479 | if (e->ops->elevator_merge_fn) |
480 | return e->ops->elevator_merge_fn(q, req, bio); | |
481 | ||
482 | return ELEVATOR_NO_MERGE; | |
483 | } | |
484 | ||
2e662b65 | 485 | void elv_merged_request(request_queue_t *q, struct request *rq, int type) |
1da177e4 LT |
486 | { |
487 | elevator_t *e = q->elevator; | |
488 | ||
489 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 490 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 491 | |
2e662b65 JA |
492 | if (type == ELEVATOR_BACK_MERGE) |
493 | elv_rqhash_reposition(q, rq); | |
9817064b | 494 | |
06b86245 | 495 | q->last_merge = rq; |
1da177e4 LT |
496 | } |
497 | ||
498 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
499 | struct request *next) | |
500 | { | |
501 | elevator_t *e = q->elevator; | |
502 | ||
1da177e4 LT |
503 | if (e->ops->elevator_merge_req_fn) |
504 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 505 | |
9817064b JA |
506 | elv_rqhash_reposition(q, rq); |
507 | elv_rqhash_del(q, next); | |
508 | ||
509 | q->nr_sorted--; | |
06b86245 | 510 | q->last_merge = rq; |
1da177e4 LT |
511 | } |
512 | ||
8922e16c | 513 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 514 | { |
1da177e4 LT |
515 | /* |
516 | * it already went through dequeue, we need to decrement the | |
517 | * in_flight count again | |
518 | */ | |
8922e16c | 519 | if (blk_account_rq(rq)) { |
1da177e4 | 520 | q->in_flight--; |
cad97516 JA |
521 | if (blk_sorted_rq(rq)) |
522 | elv_deactivate_rq(q, rq); | |
8922e16c | 523 | } |
1da177e4 | 524 | |
4aff5e23 | 525 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 526 | |
30e9656c | 527 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
528 | } |
529 | ||
15853af9 TH |
530 | static void elv_drain_elevator(request_queue_t *q) |
531 | { | |
532 | static int printed; | |
533 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
534 | ; | |
535 | if (q->nr_sorted == 0) | |
536 | return; | |
537 | if (printed++ < 10) { | |
538 | printk(KERN_ERR "%s: forced dispatching is broken " | |
539 | "(nr_sorted=%u), please report this\n", | |
540 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
541 | } | |
542 | } | |
543 | ||
30e9656c | 544 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 545 | { |
797e7dbb TH |
546 | struct list_head *pos; |
547 | unsigned ordseq; | |
dac07ec1 | 548 | int unplug_it = 1; |
797e7dbb | 549 | |
2056a782 JA |
550 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
551 | ||
1da177e4 LT |
552 | rq->q = q; |
553 | ||
8922e16c TH |
554 | switch (where) { |
555 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 556 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
557 | |
558 | list_add(&rq->queuelist, &q->queue_head); | |
559 | break; | |
560 | ||
561 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 562 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 563 | elv_drain_elevator(q); |
8922e16c TH |
564 | list_add_tail(&rq->queuelist, &q->queue_head); |
565 | /* | |
566 | * We kick the queue here for the following reasons. | |
567 | * - The elevator might have returned NULL previously | |
568 | * to delay requests and returned them now. As the | |
569 | * queue wasn't empty before this request, ll_rw_blk | |
570 | * won't run the queue on return, resulting in hang. | |
571 | * - Usually, back inserted requests won't be merged | |
572 | * with anything. There's no point in delaying queue | |
573 | * processing. | |
574 | */ | |
575 | blk_remove_plug(q); | |
576 | q->request_fn(q); | |
577 | break; | |
578 | ||
579 | case ELEVATOR_INSERT_SORT: | |
580 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 581 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 582 | q->nr_sorted++; |
9817064b JA |
583 | if (rq_mergeable(rq)) { |
584 | elv_rqhash_add(q, rq); | |
585 | if (!q->last_merge) | |
586 | q->last_merge = rq; | |
587 | } | |
588 | ||
ca23509f TH |
589 | /* |
590 | * Some ioscheds (cfq) run q->request_fn directly, so | |
591 | * rq cannot be accessed after calling | |
592 | * elevator_add_req_fn. | |
593 | */ | |
594 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
595 | break; |
596 | ||
797e7dbb TH |
597 | case ELEVATOR_INSERT_REQUEUE: |
598 | /* | |
599 | * If ordered flush isn't in progress, we do front | |
600 | * insertion; otherwise, requests should be requeued | |
601 | * in ordseq order. | |
602 | */ | |
4aff5e23 | 603 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 604 | |
95543179 LV |
605 | /* |
606 | * Most requeues happen because of a busy condition, | |
607 | * don't force unplug of the queue for that case. | |
608 | */ | |
609 | unplug_it = 0; | |
610 | ||
797e7dbb TH |
611 | if (q->ordseq == 0) { |
612 | list_add(&rq->queuelist, &q->queue_head); | |
613 | break; | |
614 | } | |
615 | ||
616 | ordseq = blk_ordered_req_seq(rq); | |
617 | ||
618 | list_for_each(pos, &q->queue_head) { | |
619 | struct request *pos_rq = list_entry_rq(pos); | |
620 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
621 | break; | |
622 | } | |
623 | ||
624 | list_add_tail(&rq->queuelist, pos); | |
625 | break; | |
626 | ||
8922e16c TH |
627 | default: |
628 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
629 | __FUNCTION__, where); | |
630 | BUG(); | |
631 | } | |
632 | ||
dac07ec1 | 633 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
634 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
635 | - q->in_flight; | |
636 | ||
637 | if (nrq >= q->unplug_thresh) | |
638 | __generic_unplug_device(q); | |
639 | } | |
1da177e4 LT |
640 | } |
641 | ||
30e9656c TH |
642 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
643 | int plug) | |
644 | { | |
645 | if (q->ordcolor) | |
4aff5e23 | 646 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 647 | |
4aff5e23 | 648 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
649 | /* |
650 | * toggle ordered color | |
651 | */ | |
652 | if (blk_barrier_rq(rq)) | |
653 | q->ordcolor ^= 1; | |
654 | ||
655 | /* | |
656 | * barriers implicitly indicate back insertion | |
657 | */ | |
658 | if (where == ELEVATOR_INSERT_SORT) | |
659 | where = ELEVATOR_INSERT_BACK; | |
660 | ||
661 | /* | |
662 | * this request is scheduling boundary, update | |
663 | * end_sector | |
664 | */ | |
665 | if (blk_fs_request(rq)) { | |
666 | q->end_sector = rq_end_sector(rq); | |
667 | q->boundary_rq = rq; | |
668 | } | |
4aff5e23 | 669 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) |
30e9656c TH |
670 | where = ELEVATOR_INSERT_BACK; |
671 | ||
672 | if (plug) | |
673 | blk_plug_device(q); | |
674 | ||
675 | elv_insert(q, rq, where); | |
676 | } | |
677 | ||
2e662b65 JA |
678 | EXPORT_SYMBOL(__elv_add_request); |
679 | ||
1da177e4 LT |
680 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
681 | int plug) | |
682 | { | |
683 | unsigned long flags; | |
684 | ||
685 | spin_lock_irqsave(q->queue_lock, flags); | |
686 | __elv_add_request(q, rq, where, plug); | |
687 | spin_unlock_irqrestore(q->queue_lock, flags); | |
688 | } | |
689 | ||
2e662b65 JA |
690 | EXPORT_SYMBOL(elv_add_request); |
691 | ||
1da177e4 LT |
692 | static inline struct request *__elv_next_request(request_queue_t *q) |
693 | { | |
8922e16c TH |
694 | struct request *rq; |
695 | ||
797e7dbb TH |
696 | while (1) { |
697 | while (!list_empty(&q->queue_head)) { | |
698 | rq = list_entry_rq(q->queue_head.next); | |
699 | if (blk_do_ordered(q, &rq)) | |
700 | return rq; | |
701 | } | |
1da177e4 | 702 | |
797e7dbb TH |
703 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
704 | return NULL; | |
1da177e4 | 705 | } |
1da177e4 LT |
706 | } |
707 | ||
708 | struct request *elv_next_request(request_queue_t *q) | |
709 | { | |
710 | struct request *rq; | |
711 | int ret; | |
712 | ||
713 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 714 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
715 | /* |
716 | * This is the first time the device driver | |
717 | * sees this request (possibly after | |
718 | * requeueing). Notify IO scheduler. | |
719 | */ | |
cad97516 JA |
720 | if (blk_sorted_rq(rq)) |
721 | elv_activate_rq(q, rq); | |
1da177e4 | 722 | |
8922e16c TH |
723 | /* |
724 | * just mark as started even if we don't start | |
725 | * it, a request that has been delayed should | |
726 | * not be passed by new incoming requests | |
727 | */ | |
4aff5e23 | 728 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 729 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 730 | } |
1da177e4 | 731 | |
8922e16c | 732 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 733 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
734 | q->boundary_rq = NULL; |
735 | } | |
1da177e4 | 736 | |
4aff5e23 | 737 | if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn) |
1da177e4 LT |
738 | break; |
739 | ||
740 | ret = q->prep_rq_fn(q, rq); | |
741 | if (ret == BLKPREP_OK) { | |
742 | break; | |
743 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
744 | /* |
745 | * the request may have been (partially) prepped. | |
746 | * we need to keep this request in the front to | |
8922e16c TH |
747 | * avoid resource deadlock. REQ_STARTED will |
748 | * prevent other fs requests from passing this one. | |
2e759cd4 | 749 | */ |
1da177e4 LT |
750 | rq = NULL; |
751 | break; | |
752 | } else if (ret == BLKPREP_KILL) { | |
753 | int nr_bytes = rq->hard_nr_sectors << 9; | |
754 | ||
755 | if (!nr_bytes) | |
756 | nr_bytes = rq->data_len; | |
757 | ||
758 | blkdev_dequeue_request(rq); | |
4aff5e23 | 759 | rq->cmd_flags |= REQ_QUIET; |
1da177e4 | 760 | end_that_request_chunk(rq, 0, nr_bytes); |
8ffdc655 | 761 | end_that_request_last(rq, 0); |
1da177e4 LT |
762 | } else { |
763 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
764 | ret); | |
765 | break; | |
766 | } | |
767 | } | |
768 | ||
769 | return rq; | |
770 | } | |
771 | ||
2e662b65 JA |
772 | EXPORT_SYMBOL(elv_next_request); |
773 | ||
8922e16c | 774 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 775 | { |
8922e16c | 776 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 777 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
778 | |
779 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
780 | |
781 | /* | |
782 | * the time frame between a request being removed from the lists | |
783 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 784 | * the driver side. |
1da177e4 LT |
785 | */ |
786 | if (blk_account_rq(rq)) | |
787 | q->in_flight++; | |
1da177e4 LT |
788 | } |
789 | ||
2e662b65 JA |
790 | EXPORT_SYMBOL(elv_dequeue_request); |
791 | ||
1da177e4 LT |
792 | int elv_queue_empty(request_queue_t *q) |
793 | { | |
794 | elevator_t *e = q->elevator; | |
795 | ||
8922e16c TH |
796 | if (!list_empty(&q->queue_head)) |
797 | return 0; | |
798 | ||
1da177e4 LT |
799 | if (e->ops->elevator_queue_empty_fn) |
800 | return e->ops->elevator_queue_empty_fn(q); | |
801 | ||
8922e16c | 802 | return 1; |
1da177e4 LT |
803 | } |
804 | ||
2e662b65 JA |
805 | EXPORT_SYMBOL(elv_queue_empty); |
806 | ||
1da177e4 LT |
807 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) |
808 | { | |
1da177e4 LT |
809 | elevator_t *e = q->elevator; |
810 | ||
811 | if (e->ops->elevator_latter_req_fn) | |
812 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
813 | return NULL; |
814 | } | |
815 | ||
816 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
817 | { | |
1da177e4 LT |
818 | elevator_t *e = q->elevator; |
819 | ||
820 | if (e->ops->elevator_former_req_fn) | |
821 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
822 | return NULL; |
823 | } | |
824 | ||
cb78b285 | 825 | int elv_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
826 | { |
827 | elevator_t *e = q->elevator; | |
828 | ||
829 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 830 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
831 | |
832 | rq->elevator_private = NULL; | |
833 | return 0; | |
834 | } | |
835 | ||
836 | void elv_put_request(request_queue_t *q, struct request *rq) | |
837 | { | |
838 | elevator_t *e = q->elevator; | |
839 | ||
840 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 841 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
842 | } |
843 | ||
cb78b285 | 844 | int elv_may_queue(request_queue_t *q, int rw) |
1da177e4 LT |
845 | { |
846 | elevator_t *e = q->elevator; | |
847 | ||
848 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 849 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
850 | |
851 | return ELV_MQUEUE_MAY; | |
852 | } | |
853 | ||
854 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
855 | { | |
856 | elevator_t *e = q->elevator; | |
857 | ||
858 | /* | |
859 | * request is released from the driver, io must be done | |
860 | */ | |
8922e16c | 861 | if (blk_account_rq(rq)) { |
1da177e4 | 862 | q->in_flight--; |
1bc691d3 TH |
863 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
864 | e->ops->elevator_completed_req_fn(q, rq); | |
865 | } | |
797e7dbb | 866 | |
1bc691d3 TH |
867 | /* |
868 | * Check if the queue is waiting for fs requests to be | |
869 | * drained for flush sequence. | |
870 | */ | |
871 | if (unlikely(q->ordseq)) { | |
872 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
873 | if (q->in_flight == 0 && | |
797e7dbb TH |
874 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
875 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
876 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
877 | q->request_fn(q); | |
878 | } | |
8922e16c | 879 | } |
1da177e4 LT |
880 | } |
881 | ||
3d1ab40f AV |
882 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
883 | ||
884 | static ssize_t | |
885 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 886 | { |
3d1ab40f AV |
887 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
888 | struct elv_fs_entry *entry = to_elv(attr); | |
889 | ssize_t error; | |
890 | ||
891 | if (!entry->show) | |
892 | return -EIO; | |
893 | ||
894 | mutex_lock(&e->sysfs_lock); | |
895 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
896 | mutex_unlock(&e->sysfs_lock); | |
897 | return error; | |
898 | } | |
1da177e4 | 899 | |
3d1ab40f AV |
900 | static ssize_t |
901 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
902 | const char *page, size_t length) | |
903 | { | |
904 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
905 | struct elv_fs_entry *entry = to_elv(attr); | |
906 | ssize_t error; | |
1da177e4 | 907 | |
3d1ab40f AV |
908 | if (!entry->store) |
909 | return -EIO; | |
1da177e4 | 910 | |
3d1ab40f AV |
911 | mutex_lock(&e->sysfs_lock); |
912 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
913 | mutex_unlock(&e->sysfs_lock); | |
914 | return error; | |
915 | } | |
916 | ||
917 | static struct sysfs_ops elv_sysfs_ops = { | |
918 | .show = elv_attr_show, | |
919 | .store = elv_attr_store, | |
920 | }; | |
921 | ||
922 | static struct kobj_type elv_ktype = { | |
923 | .sysfs_ops = &elv_sysfs_ops, | |
924 | .release = elevator_release, | |
925 | }; | |
926 | ||
927 | int elv_register_queue(struct request_queue *q) | |
928 | { | |
929 | elevator_t *e = q->elevator; | |
930 | int error; | |
931 | ||
932 | e->kobj.parent = &q->kobj; | |
933 | ||
934 | error = kobject_add(&e->kobj); | |
935 | if (!error) { | |
e572ec7e | 936 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 937 | if (attr) { |
e572ec7e AV |
938 | while (attr->attr.name) { |
939 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 940 | break; |
e572ec7e | 941 | attr++; |
3d1ab40f AV |
942 | } |
943 | } | |
944 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
945 | } | |
946 | return error; | |
1da177e4 LT |
947 | } |
948 | ||
bc1c1169 JA |
949 | static void __elv_unregister_queue(elevator_t *e) |
950 | { | |
951 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
952 | kobject_del(&e->kobj); | |
953 | } | |
954 | ||
1da177e4 LT |
955 | void elv_unregister_queue(struct request_queue *q) |
956 | { | |
bc1c1169 JA |
957 | if (q) |
958 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
959 | } |
960 | ||
961 | int elv_register(struct elevator_type *e) | |
962 | { | |
1ffb96c5 | 963 | char *def = ""; |
2a12dcd7 JA |
964 | |
965 | spin_lock(&elv_list_lock); | |
ce524497 | 966 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 967 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 968 | spin_unlock(&elv_list_lock); |
1da177e4 | 969 | |
5f003976 ND |
970 | if (!strcmp(e->elevator_name, chosen_elevator) || |
971 | (!*chosen_elevator && | |
972 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
973 | def = " (default)"; |
974 | ||
975 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, def); | |
1da177e4 LT |
976 | return 0; |
977 | } | |
978 | EXPORT_SYMBOL_GPL(elv_register); | |
979 | ||
980 | void elv_unregister(struct elevator_type *e) | |
981 | { | |
83521d3e CH |
982 | struct task_struct *g, *p; |
983 | ||
984 | /* | |
985 | * Iterate every thread in the process to remove the io contexts. | |
986 | */ | |
e17a9489 AV |
987 | if (e->ops.trim) { |
988 | read_lock(&tasklist_lock); | |
989 | do_each_thread(g, p) { | |
990 | task_lock(p); | |
2d8f6131 ON |
991 | if (p->io_context) |
992 | e->ops.trim(p->io_context); | |
e17a9489 AV |
993 | task_unlock(p); |
994 | } while_each_thread(g, p); | |
995 | read_unlock(&tasklist_lock); | |
996 | } | |
83521d3e | 997 | |
2a12dcd7 | 998 | spin_lock(&elv_list_lock); |
1da177e4 | 999 | list_del_init(&e->list); |
2a12dcd7 | 1000 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1001 | } |
1002 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1003 | ||
1004 | /* | |
1005 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1006 | * we don't free the old io scheduler, before we have allocated what we | |
1007 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1008 | * one, if the new one fails init for some reason. |
1da177e4 | 1009 | */ |
3d1ab40f | 1010 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
1da177e4 | 1011 | { |
cb98fc8b | 1012 | elevator_t *old_elevator, *e; |
bc1c1169 | 1013 | void *data; |
1da177e4 | 1014 | |
cb98fc8b TH |
1015 | /* |
1016 | * Allocate new elevator | |
1017 | */ | |
b5deef90 | 1018 | e = elevator_alloc(q, new_e); |
1da177e4 | 1019 | if (!e) |
3d1ab40f | 1020 | return 0; |
1da177e4 | 1021 | |
bc1c1169 JA |
1022 | data = elevator_init_queue(q, e); |
1023 | if (!data) { | |
1024 | kobject_put(&e->kobj); | |
1025 | return 0; | |
1026 | } | |
1027 | ||
1da177e4 | 1028 | /* |
cb98fc8b | 1029 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1030 | */ |
cb98fc8b TH |
1031 | spin_lock_irq(q->queue_lock); |
1032 | ||
64521d1a | 1033 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 1034 | |
15853af9 | 1035 | elv_drain_elevator(q); |
cb98fc8b TH |
1036 | |
1037 | while (q->rq.elvpriv) { | |
407df2aa TH |
1038 | blk_remove_plug(q); |
1039 | q->request_fn(q); | |
cb98fc8b | 1040 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1041 | msleep(10); |
cb98fc8b | 1042 | spin_lock_irq(q->queue_lock); |
15853af9 | 1043 | elv_drain_elevator(q); |
cb98fc8b TH |
1044 | } |
1045 | ||
1da177e4 | 1046 | /* |
bc1c1169 | 1047 | * Remember old elevator. |
1da177e4 | 1048 | */ |
1da177e4 LT |
1049 | old_elevator = q->elevator; |
1050 | ||
1da177e4 LT |
1051 | /* |
1052 | * attach and start new elevator | |
1053 | */ | |
bc1c1169 JA |
1054 | elevator_attach(q, e, data); |
1055 | ||
1056 | spin_unlock_irq(q->queue_lock); | |
1057 | ||
1058 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1059 | |
1060 | if (elv_register_queue(q)) | |
1061 | goto fail_register; | |
1062 | ||
1063 | /* | |
cb98fc8b | 1064 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1065 | */ |
1066 | elevator_exit(old_elevator); | |
64521d1a | 1067 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1068 | return 1; |
1da177e4 LT |
1069 | |
1070 | fail_register: | |
1071 | /* | |
1072 | * switch failed, exit the new io scheduler and reattach the old | |
1073 | * one again (along with re-adding the sysfs dir) | |
1074 | */ | |
1075 | elevator_exit(e); | |
1da177e4 LT |
1076 | q->elevator = old_elevator; |
1077 | elv_register_queue(q); | |
64521d1a | 1078 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1079 | return 0; |
1da177e4 LT |
1080 | } |
1081 | ||
1082 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
1083 | { | |
1084 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1085 | size_t len; |
1da177e4 LT |
1086 | struct elevator_type *e; |
1087 | ||
be561235 TH |
1088 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1089 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1090 | len = strlen(elevator_name); | |
1da177e4 | 1091 | |
be561235 TH |
1092 | if (len && elevator_name[len - 1] == '\n') |
1093 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1094 | |
1095 | e = elevator_get(elevator_name); | |
1096 | if (!e) { | |
1097 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1098 | return -EINVAL; | |
1099 | } | |
1100 | ||
2ca7d93b ND |
1101 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1102 | elevator_put(e); | |
1da177e4 | 1103 | return count; |
2ca7d93b | 1104 | } |
1da177e4 | 1105 | |
3d1ab40f AV |
1106 | if (!elevator_switch(q, e)) |
1107 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
1108 | return count; |
1109 | } | |
1110 | ||
1111 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
1112 | { | |
1113 | elevator_t *e = q->elevator; | |
1114 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1115 | struct elevator_type *__e; |
1da177e4 LT |
1116 | int len = 0; |
1117 | ||
2a12dcd7 | 1118 | spin_lock(&elv_list_lock); |
70cee26e | 1119 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1120 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1121 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1122 | else | |
1123 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1124 | } | |
2a12dcd7 | 1125 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1126 | |
1127 | len += sprintf(len+name, "\n"); | |
1128 | return len; | |
1129 | } | |
1130 | ||
2e662b65 JA |
1131 | struct request *elv_rb_former_request(request_queue_t *q, struct request *rq) |
1132 | { | |
1133 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1134 | ||
1135 | if (rbprev) | |
1136 | return rb_entry_rq(rbprev); | |
1137 | ||
1138 | return NULL; | |
1139 | } | |
1140 | ||
1141 | EXPORT_SYMBOL(elv_rb_former_request); | |
1142 | ||
1143 | struct request *elv_rb_latter_request(request_queue_t *q, struct request *rq) | |
1144 | { | |
1145 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1146 | ||
1147 | if (rbnext) | |
1148 | return rb_entry_rq(rbnext); | |
1149 | ||
1150 | return NULL; | |
1151 | } | |
1152 | ||
1153 | EXPORT_SYMBOL(elv_rb_latter_request); |