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> |
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 LT |
115 | struct list_head *entry; |
116 | ||
1da177e4 | 117 | list_for_each(entry, &elv_list) { |
1da177e4 | 118 | |
a22b169d | 119 | e = list_entry(entry, struct elevator_type, list); |
1da177e4 | 120 | |
a22b169d VT |
121 | if (!strcmp(e->elevator_name, name)) |
122 | return e; | |
1da177e4 | 123 | } |
1da177e4 | 124 | |
a22b169d | 125 | return NULL; |
1da177e4 LT |
126 | } |
127 | ||
128 | static void elevator_put(struct elevator_type *e) | |
129 | { | |
130 | module_put(e->elevator_owner); | |
131 | } | |
132 | ||
133 | static struct elevator_type *elevator_get(const char *name) | |
134 | { | |
2824bc93 | 135 | struct elevator_type *e; |
1da177e4 | 136 | |
2824bc93 TH |
137 | spin_lock_irq(&elv_list_lock); |
138 | ||
139 | e = elevator_find(name); | |
140 | if (e && !try_module_get(e->elevator_owner)) | |
141 | e = NULL; | |
142 | ||
143 | spin_unlock_irq(&elv_list_lock); | |
1da177e4 LT |
144 | |
145 | return e; | |
146 | } | |
147 | ||
bc1c1169 | 148 | static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 | 149 | { |
bb37b94c | 150 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 151 | } |
1da177e4 | 152 | |
bc1c1169 JA |
153 | static void elevator_attach(request_queue_t *q, struct elevator_queue *eq, |
154 | void *data) | |
155 | { | |
1da177e4 | 156 | q->elevator = eq; |
bc1c1169 | 157 | eq->elevator_data = data; |
1da177e4 LT |
158 | } |
159 | ||
160 | static char chosen_elevator[16]; | |
161 | ||
5f003976 | 162 | static int __init elevator_setup(char *str) |
1da177e4 | 163 | { |
752a3b79 CE |
164 | /* |
165 | * Be backwards-compatible with previous kernels, so users | |
166 | * won't get the wrong elevator. | |
167 | */ | |
5f003976 | 168 | if (!strcmp(str, "as")) |
752a3b79 | 169 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 170 | else |
5f003976 | 171 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 172 | return 1; |
1da177e4 LT |
173 | } |
174 | ||
175 | __setup("elevator=", elevator_setup); | |
176 | ||
3d1ab40f AV |
177 | static struct kobj_type elv_ktype; |
178 | ||
b5deef90 | 179 | static elevator_t *elevator_alloc(request_queue_t *q, struct elevator_type *e) |
3d1ab40f | 180 | { |
9817064b JA |
181 | elevator_t *eq; |
182 | int i; | |
183 | ||
b5deef90 | 184 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL, q->node); |
9817064b JA |
185 | if (unlikely(!eq)) |
186 | goto err; | |
187 | ||
188 | memset(eq, 0, sizeof(*eq)); | |
189 | eq->ops = &e->ops; | |
190 | eq->elevator_type = e; | |
191 | kobject_init(&eq->kobj); | |
192 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
193 | eq->kobj.ktype = &elv_ktype; | |
194 | mutex_init(&eq->sysfs_lock); | |
195 | ||
b5deef90 JA |
196 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
197 | GFP_KERNEL, q->node); | |
9817064b JA |
198 | if (!eq->hash) |
199 | goto err; | |
200 | ||
201 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
202 | INIT_HLIST_HEAD(&eq->hash[i]); | |
203 | ||
3d1ab40f | 204 | return eq; |
9817064b JA |
205 | err: |
206 | kfree(eq); | |
207 | elevator_put(e); | |
208 | return NULL; | |
3d1ab40f AV |
209 | } |
210 | ||
211 | static void elevator_release(struct kobject *kobj) | |
212 | { | |
213 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 214 | |
3d1ab40f | 215 | elevator_put(e->elevator_type); |
9817064b | 216 | kfree(e->hash); |
3d1ab40f AV |
217 | kfree(e); |
218 | } | |
219 | ||
1da177e4 LT |
220 | int elevator_init(request_queue_t *q, char *name) |
221 | { | |
222 | struct elevator_type *e = NULL; | |
223 | struct elevator_queue *eq; | |
224 | int ret = 0; | |
bc1c1169 | 225 | void *data; |
1da177e4 | 226 | |
cb98fc8b TH |
227 | INIT_LIST_HEAD(&q->queue_head); |
228 | q->last_merge = NULL; | |
229 | q->end_sector = 0; | |
230 | q->boundary_rq = NULL; | |
cb98fc8b | 231 | |
5f003976 | 232 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
233 | return -EINVAL; |
234 | ||
248d5ca5 ND |
235 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
236 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
237 | ||
238 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
239 | printk("Default I/O scheduler not found, using no-op\n"); | |
240 | e = elevator_get("noop"); | |
5f003976 ND |
241 | } |
242 | ||
b5deef90 | 243 | eq = elevator_alloc(q, e); |
3d1ab40f | 244 | if (!eq) |
1da177e4 | 245 | return -ENOMEM; |
1da177e4 | 246 | |
bc1c1169 JA |
247 | data = elevator_init_queue(q, eq); |
248 | if (!data) { | |
3d1ab40f | 249 | kobject_put(&eq->kobj); |
bc1c1169 JA |
250 | return -ENOMEM; |
251 | } | |
1da177e4 | 252 | |
bc1c1169 | 253 | elevator_attach(q, eq, data); |
1da177e4 LT |
254 | return ret; |
255 | } | |
256 | ||
2e662b65 JA |
257 | EXPORT_SYMBOL(elevator_init); |
258 | ||
1da177e4 LT |
259 | void elevator_exit(elevator_t *e) |
260 | { | |
3d1ab40f | 261 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
262 | if (e->ops->elevator_exit_fn) |
263 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
264 | e->ops = NULL; |
265 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 266 | |
3d1ab40f | 267 | kobject_put(&e->kobj); |
1da177e4 LT |
268 | } |
269 | ||
2e662b65 JA |
270 | EXPORT_SYMBOL(elevator_exit); |
271 | ||
cad97516 JA |
272 | static void elv_activate_rq(request_queue_t *q, struct request *rq) |
273 | { | |
274 | elevator_t *e = q->elevator; | |
275 | ||
276 | if (e->ops->elevator_activate_req_fn) | |
277 | e->ops->elevator_activate_req_fn(q, rq); | |
278 | } | |
279 | ||
280 | static void elv_deactivate_rq(request_queue_t *q, struct request *rq) | |
281 | { | |
282 | elevator_t *e = q->elevator; | |
283 | ||
284 | if (e->ops->elevator_deactivate_req_fn) | |
285 | e->ops->elevator_deactivate_req_fn(q, rq); | |
286 | } | |
287 | ||
9817064b JA |
288 | static inline void __elv_rqhash_del(struct request *rq) |
289 | { | |
290 | hlist_del_init(&rq->hash); | |
291 | } | |
292 | ||
293 | static void elv_rqhash_del(request_queue_t *q, struct request *rq) | |
294 | { | |
295 | if (ELV_ON_HASH(rq)) | |
296 | __elv_rqhash_del(rq); | |
297 | } | |
298 | ||
299 | static void elv_rqhash_add(request_queue_t *q, struct request *rq) | |
300 | { | |
301 | elevator_t *e = q->elevator; | |
302 | ||
303 | BUG_ON(ELV_ON_HASH(rq)); | |
304 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
305 | } | |
306 | ||
307 | static void elv_rqhash_reposition(request_queue_t *q, struct request *rq) | |
308 | { | |
309 | __elv_rqhash_del(rq); | |
310 | elv_rqhash_add(q, rq); | |
311 | } | |
312 | ||
313 | static struct request *elv_rqhash_find(request_queue_t *q, sector_t offset) | |
314 | { | |
315 | elevator_t *e = q->elevator; | |
316 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
317 | struct hlist_node *entry, *next; | |
318 | struct request *rq; | |
319 | ||
320 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
321 | BUG_ON(!ELV_ON_HASH(rq)); | |
322 | ||
323 | if (unlikely(!rq_mergeable(rq))) { | |
324 | __elv_rqhash_del(rq); | |
325 | continue; | |
326 | } | |
327 | ||
328 | if (rq_hash_key(rq) == offset) | |
329 | return rq; | |
330 | } | |
331 | ||
332 | return NULL; | |
333 | } | |
334 | ||
2e662b65 JA |
335 | /* |
336 | * RB-tree support functions for inserting/lookup/removal of requests | |
337 | * in a sorted RB tree. | |
338 | */ | |
339 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
340 | { | |
341 | struct rb_node **p = &root->rb_node; | |
342 | struct rb_node *parent = NULL; | |
343 | struct request *__rq; | |
344 | ||
345 | while (*p) { | |
346 | parent = *p; | |
347 | __rq = rb_entry(parent, struct request, rb_node); | |
348 | ||
349 | if (rq->sector < __rq->sector) | |
350 | p = &(*p)->rb_left; | |
351 | else if (rq->sector > __rq->sector) | |
352 | p = &(*p)->rb_right; | |
353 | else | |
354 | return __rq; | |
355 | } | |
356 | ||
357 | rb_link_node(&rq->rb_node, parent, p); | |
358 | rb_insert_color(&rq->rb_node, root); | |
359 | return NULL; | |
360 | } | |
361 | ||
362 | EXPORT_SYMBOL(elv_rb_add); | |
363 | ||
364 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
365 | { | |
366 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
367 | rb_erase(&rq->rb_node, root); | |
368 | RB_CLEAR_NODE(&rq->rb_node); | |
369 | } | |
370 | ||
371 | EXPORT_SYMBOL(elv_rb_del); | |
372 | ||
373 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
374 | { | |
375 | struct rb_node *n = root->rb_node; | |
376 | struct request *rq; | |
377 | ||
378 | while (n) { | |
379 | rq = rb_entry(n, struct request, rb_node); | |
380 | ||
381 | if (sector < rq->sector) | |
382 | n = n->rb_left; | |
383 | else if (sector > rq->sector) | |
384 | n = n->rb_right; | |
385 | else | |
386 | return rq; | |
387 | } | |
388 | ||
389 | return NULL; | |
390 | } | |
391 | ||
392 | EXPORT_SYMBOL(elv_rb_find); | |
393 | ||
8922e16c TH |
394 | /* |
395 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
2e662b65 JA |
396 | * entry. rq is sort insted into the dispatch queue. To be used by |
397 | * specific elevators. | |
8922e16c | 398 | */ |
1b47f531 | 399 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
400 | { |
401 | sector_t boundary; | |
8922e16c TH |
402 | struct list_head *entry; |
403 | ||
06b86245 TH |
404 | if (q->last_merge == rq) |
405 | q->last_merge = NULL; | |
9817064b JA |
406 | |
407 | elv_rqhash_del(q, rq); | |
408 | ||
15853af9 | 409 | q->nr_sorted--; |
06b86245 | 410 | |
1b47f531 | 411 | boundary = q->end_sector; |
cb19833d | 412 | |
8922e16c TH |
413 | list_for_each_prev(entry, &q->queue_head) { |
414 | struct request *pos = list_entry_rq(entry); | |
415 | ||
4aff5e23 | 416 | if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) |
8922e16c TH |
417 | break; |
418 | if (rq->sector >= boundary) { | |
419 | if (pos->sector < boundary) | |
420 | continue; | |
421 | } else { | |
422 | if (pos->sector >= boundary) | |
423 | break; | |
424 | } | |
425 | if (rq->sector >= pos->sector) | |
426 | break; | |
427 | } | |
428 | ||
429 | list_add(&rq->queuelist, entry); | |
430 | } | |
431 | ||
2e662b65 JA |
432 | EXPORT_SYMBOL(elv_dispatch_sort); |
433 | ||
9817064b | 434 | /* |
2e662b65 JA |
435 | * Insert rq into dispatch queue of q. Queue lock must be held on |
436 | * entry. rq is added to the back of the dispatch queue. To be used by | |
437 | * specific elevators. | |
9817064b JA |
438 | */ |
439 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
440 | { | |
441 | if (q->last_merge == rq) | |
442 | q->last_merge = NULL; | |
443 | ||
444 | elv_rqhash_del(q, rq); | |
445 | ||
446 | q->nr_sorted--; | |
447 | ||
448 | q->end_sector = rq_end_sector(rq); | |
449 | q->boundary_rq = rq; | |
450 | list_add_tail(&rq->queuelist, &q->queue_head); | |
451 | } | |
452 | ||
2e662b65 JA |
453 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
454 | ||
1da177e4 LT |
455 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
456 | { | |
457 | elevator_t *e = q->elevator; | |
9817064b | 458 | struct request *__rq; |
06b86245 TH |
459 | int ret; |
460 | ||
9817064b JA |
461 | /* |
462 | * First try one-hit cache. | |
463 | */ | |
06b86245 TH |
464 | if (q->last_merge) { |
465 | ret = elv_try_merge(q->last_merge, bio); | |
466 | if (ret != ELEVATOR_NO_MERGE) { | |
467 | *req = q->last_merge; | |
468 | return ret; | |
469 | } | |
470 | } | |
1da177e4 | 471 | |
9817064b JA |
472 | /* |
473 | * See if our hash lookup can find a potential backmerge. | |
474 | */ | |
475 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
476 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
477 | *req = __rq; | |
478 | return ELEVATOR_BACK_MERGE; | |
479 | } | |
480 | ||
1da177e4 LT |
481 | if (e->ops->elevator_merge_fn) |
482 | return e->ops->elevator_merge_fn(q, req, bio); | |
483 | ||
484 | return ELEVATOR_NO_MERGE; | |
485 | } | |
486 | ||
2e662b65 | 487 | void elv_merged_request(request_queue_t *q, struct request *rq, int type) |
1da177e4 LT |
488 | { |
489 | elevator_t *e = q->elevator; | |
490 | ||
491 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 492 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 493 | |
2e662b65 JA |
494 | if (type == ELEVATOR_BACK_MERGE) |
495 | elv_rqhash_reposition(q, rq); | |
9817064b | 496 | |
06b86245 | 497 | q->last_merge = rq; |
1da177e4 LT |
498 | } |
499 | ||
500 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
501 | struct request *next) | |
502 | { | |
503 | elevator_t *e = q->elevator; | |
504 | ||
1da177e4 LT |
505 | if (e->ops->elevator_merge_req_fn) |
506 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 507 | |
9817064b JA |
508 | elv_rqhash_reposition(q, rq); |
509 | elv_rqhash_del(q, next); | |
510 | ||
511 | q->nr_sorted--; | |
06b86245 | 512 | q->last_merge = rq; |
1da177e4 LT |
513 | } |
514 | ||
8922e16c | 515 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 516 | { |
1da177e4 LT |
517 | /* |
518 | * it already went through dequeue, we need to decrement the | |
519 | * in_flight count again | |
520 | */ | |
8922e16c | 521 | if (blk_account_rq(rq)) { |
1da177e4 | 522 | q->in_flight--; |
cad97516 JA |
523 | if (blk_sorted_rq(rq)) |
524 | elv_deactivate_rq(q, rq); | |
8922e16c | 525 | } |
1da177e4 | 526 | |
4aff5e23 | 527 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 528 | |
30e9656c | 529 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
530 | } |
531 | ||
15853af9 TH |
532 | static void elv_drain_elevator(request_queue_t *q) |
533 | { | |
534 | static int printed; | |
535 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
536 | ; | |
537 | if (q->nr_sorted == 0) | |
538 | return; | |
539 | if (printed++ < 10) { | |
540 | printk(KERN_ERR "%s: forced dispatching is broken " | |
541 | "(nr_sorted=%u), please report this\n", | |
542 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
543 | } | |
544 | } | |
545 | ||
30e9656c | 546 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 547 | { |
797e7dbb TH |
548 | struct list_head *pos; |
549 | unsigned ordseq; | |
dac07ec1 | 550 | int unplug_it = 1; |
797e7dbb | 551 | |
2056a782 JA |
552 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
553 | ||
1da177e4 LT |
554 | rq->q = q; |
555 | ||
8922e16c TH |
556 | switch (where) { |
557 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 558 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
559 | |
560 | list_add(&rq->queuelist, &q->queue_head); | |
561 | break; | |
562 | ||
563 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 564 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 565 | elv_drain_elevator(q); |
8922e16c TH |
566 | list_add_tail(&rq->queuelist, &q->queue_head); |
567 | /* | |
568 | * We kick the queue here for the following reasons. | |
569 | * - The elevator might have returned NULL previously | |
570 | * to delay requests and returned them now. As the | |
571 | * queue wasn't empty before this request, ll_rw_blk | |
572 | * won't run the queue on return, resulting in hang. | |
573 | * - Usually, back inserted requests won't be merged | |
574 | * with anything. There's no point in delaying queue | |
575 | * processing. | |
576 | */ | |
577 | blk_remove_plug(q); | |
578 | q->request_fn(q); | |
579 | break; | |
580 | ||
581 | case ELEVATOR_INSERT_SORT: | |
582 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 583 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 584 | q->nr_sorted++; |
9817064b JA |
585 | if (rq_mergeable(rq)) { |
586 | elv_rqhash_add(q, rq); | |
587 | if (!q->last_merge) | |
588 | q->last_merge = rq; | |
589 | } | |
590 | ||
ca23509f TH |
591 | /* |
592 | * Some ioscheds (cfq) run q->request_fn directly, so | |
593 | * rq cannot be accessed after calling | |
594 | * elevator_add_req_fn. | |
595 | */ | |
596 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
597 | break; |
598 | ||
797e7dbb TH |
599 | case ELEVATOR_INSERT_REQUEUE: |
600 | /* | |
601 | * If ordered flush isn't in progress, we do front | |
602 | * insertion; otherwise, requests should be requeued | |
603 | * in ordseq order. | |
604 | */ | |
4aff5e23 | 605 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 606 | |
95543179 LV |
607 | /* |
608 | * Most requeues happen because of a busy condition, | |
609 | * don't force unplug of the queue for that case. | |
610 | */ | |
611 | unplug_it = 0; | |
612 | ||
797e7dbb TH |
613 | if (q->ordseq == 0) { |
614 | list_add(&rq->queuelist, &q->queue_head); | |
615 | break; | |
616 | } | |
617 | ||
618 | ordseq = blk_ordered_req_seq(rq); | |
619 | ||
620 | list_for_each(pos, &q->queue_head) { | |
621 | struct request *pos_rq = list_entry_rq(pos); | |
622 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
623 | break; | |
624 | } | |
625 | ||
626 | list_add_tail(&rq->queuelist, pos); | |
627 | break; | |
628 | ||
8922e16c TH |
629 | default: |
630 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
631 | __FUNCTION__, where); | |
632 | BUG(); | |
633 | } | |
634 | ||
dac07ec1 | 635 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
636 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
637 | - q->in_flight; | |
638 | ||
639 | if (nrq >= q->unplug_thresh) | |
640 | __generic_unplug_device(q); | |
641 | } | |
1da177e4 LT |
642 | } |
643 | ||
30e9656c TH |
644 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
645 | int plug) | |
646 | { | |
647 | if (q->ordcolor) | |
4aff5e23 | 648 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 649 | |
4aff5e23 | 650 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
651 | /* |
652 | * toggle ordered color | |
653 | */ | |
654 | if (blk_barrier_rq(rq)) | |
655 | q->ordcolor ^= 1; | |
656 | ||
657 | /* | |
658 | * barriers implicitly indicate back insertion | |
659 | */ | |
660 | if (where == ELEVATOR_INSERT_SORT) | |
661 | where = ELEVATOR_INSERT_BACK; | |
662 | ||
663 | /* | |
664 | * this request is scheduling boundary, update | |
665 | * end_sector | |
666 | */ | |
667 | if (blk_fs_request(rq)) { | |
668 | q->end_sector = rq_end_sector(rq); | |
669 | q->boundary_rq = rq; | |
670 | } | |
4aff5e23 | 671 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) |
30e9656c TH |
672 | where = ELEVATOR_INSERT_BACK; |
673 | ||
674 | if (plug) | |
675 | blk_plug_device(q); | |
676 | ||
677 | elv_insert(q, rq, where); | |
678 | } | |
679 | ||
2e662b65 JA |
680 | EXPORT_SYMBOL(__elv_add_request); |
681 | ||
1da177e4 LT |
682 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
683 | int plug) | |
684 | { | |
685 | unsigned long flags; | |
686 | ||
687 | spin_lock_irqsave(q->queue_lock, flags); | |
688 | __elv_add_request(q, rq, where, plug); | |
689 | spin_unlock_irqrestore(q->queue_lock, flags); | |
690 | } | |
691 | ||
2e662b65 JA |
692 | EXPORT_SYMBOL(elv_add_request); |
693 | ||
1da177e4 LT |
694 | static inline struct request *__elv_next_request(request_queue_t *q) |
695 | { | |
8922e16c TH |
696 | struct request *rq; |
697 | ||
797e7dbb TH |
698 | while (1) { |
699 | while (!list_empty(&q->queue_head)) { | |
700 | rq = list_entry_rq(q->queue_head.next); | |
701 | if (blk_do_ordered(q, &rq)) | |
702 | return rq; | |
703 | } | |
1da177e4 | 704 | |
797e7dbb TH |
705 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
706 | return NULL; | |
1da177e4 | 707 | } |
1da177e4 LT |
708 | } |
709 | ||
710 | struct request *elv_next_request(request_queue_t *q) | |
711 | { | |
712 | struct request *rq; | |
713 | int ret; | |
714 | ||
715 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 716 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
717 | /* |
718 | * This is the first time the device driver | |
719 | * sees this request (possibly after | |
720 | * requeueing). Notify IO scheduler. | |
721 | */ | |
cad97516 JA |
722 | if (blk_sorted_rq(rq)) |
723 | elv_activate_rq(q, rq); | |
1da177e4 | 724 | |
8922e16c TH |
725 | /* |
726 | * just mark as started even if we don't start | |
727 | * it, a request that has been delayed should | |
728 | * not be passed by new incoming requests | |
729 | */ | |
4aff5e23 | 730 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 731 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 732 | } |
1da177e4 | 733 | |
8922e16c | 734 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 735 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
736 | q->boundary_rq = NULL; |
737 | } | |
1da177e4 | 738 | |
4aff5e23 | 739 | if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn) |
1da177e4 LT |
740 | break; |
741 | ||
742 | ret = q->prep_rq_fn(q, rq); | |
743 | if (ret == BLKPREP_OK) { | |
744 | break; | |
745 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
746 | /* |
747 | * the request may have been (partially) prepped. | |
748 | * we need to keep this request in the front to | |
8922e16c TH |
749 | * avoid resource deadlock. REQ_STARTED will |
750 | * prevent other fs requests from passing this one. | |
2e759cd4 | 751 | */ |
1da177e4 LT |
752 | rq = NULL; |
753 | break; | |
754 | } else if (ret == BLKPREP_KILL) { | |
755 | int nr_bytes = rq->hard_nr_sectors << 9; | |
756 | ||
757 | if (!nr_bytes) | |
758 | nr_bytes = rq->data_len; | |
759 | ||
760 | blkdev_dequeue_request(rq); | |
4aff5e23 | 761 | rq->cmd_flags |= REQ_QUIET; |
1da177e4 | 762 | end_that_request_chunk(rq, 0, nr_bytes); |
8ffdc655 | 763 | end_that_request_last(rq, 0); |
1da177e4 LT |
764 | } else { |
765 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
766 | ret); | |
767 | break; | |
768 | } | |
769 | } | |
770 | ||
771 | return rq; | |
772 | } | |
773 | ||
2e662b65 JA |
774 | EXPORT_SYMBOL(elv_next_request); |
775 | ||
8922e16c | 776 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 777 | { |
8922e16c | 778 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 779 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
780 | |
781 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
782 | |
783 | /* | |
784 | * the time frame between a request being removed from the lists | |
785 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 786 | * the driver side. |
1da177e4 LT |
787 | */ |
788 | if (blk_account_rq(rq)) | |
789 | q->in_flight++; | |
1da177e4 LT |
790 | } |
791 | ||
2e662b65 JA |
792 | EXPORT_SYMBOL(elv_dequeue_request); |
793 | ||
1da177e4 LT |
794 | int elv_queue_empty(request_queue_t *q) |
795 | { | |
796 | elevator_t *e = q->elevator; | |
797 | ||
8922e16c TH |
798 | if (!list_empty(&q->queue_head)) |
799 | return 0; | |
800 | ||
1da177e4 LT |
801 | if (e->ops->elevator_queue_empty_fn) |
802 | return e->ops->elevator_queue_empty_fn(q); | |
803 | ||
8922e16c | 804 | return 1; |
1da177e4 LT |
805 | } |
806 | ||
2e662b65 JA |
807 | EXPORT_SYMBOL(elv_queue_empty); |
808 | ||
1da177e4 LT |
809 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) |
810 | { | |
1da177e4 LT |
811 | elevator_t *e = q->elevator; |
812 | ||
813 | if (e->ops->elevator_latter_req_fn) | |
814 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
815 | return NULL; |
816 | } | |
817 | ||
818 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
819 | { | |
1da177e4 LT |
820 | elevator_t *e = q->elevator; |
821 | ||
822 | if (e->ops->elevator_former_req_fn) | |
823 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
824 | return NULL; |
825 | } | |
826 | ||
cb78b285 | 827 | int elv_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
828 | { |
829 | elevator_t *e = q->elevator; | |
830 | ||
831 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 832 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
833 | |
834 | rq->elevator_private = NULL; | |
835 | return 0; | |
836 | } | |
837 | ||
838 | void elv_put_request(request_queue_t *q, struct request *rq) | |
839 | { | |
840 | elevator_t *e = q->elevator; | |
841 | ||
842 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 843 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
844 | } |
845 | ||
cb78b285 | 846 | int elv_may_queue(request_queue_t *q, int rw) |
1da177e4 LT |
847 | { |
848 | elevator_t *e = q->elevator; | |
849 | ||
850 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 851 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
852 | |
853 | return ELV_MQUEUE_MAY; | |
854 | } | |
855 | ||
856 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
857 | { | |
858 | elevator_t *e = q->elevator; | |
859 | ||
860 | /* | |
861 | * request is released from the driver, io must be done | |
862 | */ | |
8922e16c | 863 | if (blk_account_rq(rq)) { |
1da177e4 | 864 | q->in_flight--; |
1bc691d3 TH |
865 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
866 | e->ops->elevator_completed_req_fn(q, rq); | |
867 | } | |
797e7dbb | 868 | |
1bc691d3 TH |
869 | /* |
870 | * Check if the queue is waiting for fs requests to be | |
871 | * drained for flush sequence. | |
872 | */ | |
873 | if (unlikely(q->ordseq)) { | |
874 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
875 | if (q->in_flight == 0 && | |
797e7dbb TH |
876 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
877 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
878 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
879 | q->request_fn(q); | |
880 | } | |
8922e16c | 881 | } |
1da177e4 LT |
882 | } |
883 | ||
3d1ab40f AV |
884 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
885 | ||
886 | static ssize_t | |
887 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 888 | { |
3d1ab40f AV |
889 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
890 | struct elv_fs_entry *entry = to_elv(attr); | |
891 | ssize_t error; | |
892 | ||
893 | if (!entry->show) | |
894 | return -EIO; | |
895 | ||
896 | mutex_lock(&e->sysfs_lock); | |
897 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
898 | mutex_unlock(&e->sysfs_lock); | |
899 | return error; | |
900 | } | |
1da177e4 | 901 | |
3d1ab40f AV |
902 | static ssize_t |
903 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
904 | const char *page, size_t length) | |
905 | { | |
906 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
907 | struct elv_fs_entry *entry = to_elv(attr); | |
908 | ssize_t error; | |
1da177e4 | 909 | |
3d1ab40f AV |
910 | if (!entry->store) |
911 | return -EIO; | |
1da177e4 | 912 | |
3d1ab40f AV |
913 | mutex_lock(&e->sysfs_lock); |
914 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
915 | mutex_unlock(&e->sysfs_lock); | |
916 | return error; | |
917 | } | |
918 | ||
919 | static struct sysfs_ops elv_sysfs_ops = { | |
920 | .show = elv_attr_show, | |
921 | .store = elv_attr_store, | |
922 | }; | |
923 | ||
924 | static struct kobj_type elv_ktype = { | |
925 | .sysfs_ops = &elv_sysfs_ops, | |
926 | .release = elevator_release, | |
927 | }; | |
928 | ||
929 | int elv_register_queue(struct request_queue *q) | |
930 | { | |
931 | elevator_t *e = q->elevator; | |
932 | int error; | |
933 | ||
934 | e->kobj.parent = &q->kobj; | |
935 | ||
936 | error = kobject_add(&e->kobj); | |
937 | if (!error) { | |
e572ec7e | 938 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 939 | if (attr) { |
e572ec7e AV |
940 | while (attr->attr.name) { |
941 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 942 | break; |
e572ec7e | 943 | attr++; |
3d1ab40f AV |
944 | } |
945 | } | |
946 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
947 | } | |
948 | return error; | |
1da177e4 LT |
949 | } |
950 | ||
bc1c1169 JA |
951 | static void __elv_unregister_queue(elevator_t *e) |
952 | { | |
953 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
954 | kobject_del(&e->kobj); | |
955 | } | |
956 | ||
1da177e4 LT |
957 | void elv_unregister_queue(struct request_queue *q) |
958 | { | |
bc1c1169 JA |
959 | if (q) |
960 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
961 | } |
962 | ||
963 | int elv_register(struct elevator_type *e) | |
964 | { | |
2824bc93 | 965 | spin_lock_irq(&elv_list_lock); |
ce524497 | 966 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 LT |
967 | list_add_tail(&e->list, &elv_list); |
968 | spin_unlock_irq(&elv_list_lock); | |
969 | ||
970 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
971 | if (!strcmp(e->elevator_name, chosen_elevator) || |
972 | (!*chosen_elevator && | |
973 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
974 | printk(" (default)"); | |
1da177e4 LT |
975 | printk("\n"); |
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 | |
1da177e4 LT |
998 | spin_lock_irq(&elv_list_lock); |
999 | list_del_init(&e->list); | |
1000 | spin_unlock_irq(&elv_list_lock); | |
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; | |
1115 | struct list_head *entry; | |
1116 | int len = 0; | |
1117 | ||
c5841642 | 1118 | spin_lock_irq(&elv_list_lock); |
1da177e4 LT |
1119 | list_for_each(entry, &elv_list) { |
1120 | struct elevator_type *__e; | |
1121 | ||
1122 | __e = list_entry(entry, struct elevator_type, list); | |
1123 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
1124 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1125 | else | |
1126 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1127 | } | |
c5841642 | 1128 | spin_unlock_irq(&elv_list_lock); |
1da177e4 LT |
1129 | |
1130 | len += sprintf(len+name, "\n"); | |
1131 | return len; | |
1132 | } | |
1133 | ||
2e662b65 JA |
1134 | struct request *elv_rb_former_request(request_queue_t *q, struct request *rq) |
1135 | { | |
1136 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1137 | ||
1138 | if (rbprev) | |
1139 | return rb_entry_rq(rbprev); | |
1140 | ||
1141 | return NULL; | |
1142 | } | |
1143 | ||
1144 | EXPORT_SYMBOL(elv_rb_former_request); | |
1145 | ||
1146 | struct request *elv_rb_latter_request(request_queue_t *q, struct request *rq) | |
1147 | { | |
1148 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1149 | ||
1150 | if (rbnext) | |
1151 | return rb_entry_rq(rbnext); | |
1152 | ||
1153 | return NULL; | |
1154 | } | |
1155 | ||
1156 | EXPORT_SYMBOL(elv_rb_latter_request); |