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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 | { | |
165125e1 | 59 | struct request_queue *q = rq->q; |
da775265 JA |
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 | ||
165125e1 JA |
144 | static void *elevator_init_queue(struct request_queue *q, |
145 | struct elevator_queue *eq) | |
1da177e4 | 146 | { |
bb37b94c | 147 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 148 | } |
1da177e4 | 149 | |
165125e1 | 150 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
151 | void *data) |
152 | { | |
1da177e4 | 153 | q->elevator = eq; |
bc1c1169 | 154 | eq->elevator_data = data; |
1da177e4 LT |
155 | } |
156 | ||
157 | static char chosen_elevator[16]; | |
158 | ||
5f003976 | 159 | static int __init elevator_setup(char *str) |
1da177e4 | 160 | { |
752a3b79 CE |
161 | /* |
162 | * Be backwards-compatible with previous kernels, so users | |
163 | * won't get the wrong elevator. | |
164 | */ | |
5f003976 | 165 | if (!strcmp(str, "as")) |
752a3b79 | 166 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 167 | else |
5f003976 | 168 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 169 | return 1; |
1da177e4 LT |
170 | } |
171 | ||
172 | __setup("elevator=", elevator_setup); | |
173 | ||
3d1ab40f AV |
174 | static struct kobj_type elv_ktype; |
175 | ||
165125e1 JA |
176 | static elevator_t *elevator_alloc(struct request_queue *q, |
177 | struct elevator_type *e) | |
3d1ab40f | 178 | { |
9817064b JA |
179 | elevator_t *eq; |
180 | int i; | |
181 | ||
94f6030c | 182 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
183 | if (unlikely(!eq)) |
184 | goto err; | |
185 | ||
9817064b JA |
186 | eq->ops = &e->ops; |
187 | eq->elevator_type = e; | |
188 | kobject_init(&eq->kobj); | |
19c38de8 | 189 | kobject_set_name(&eq->kobj, "%s", "iosched"); |
9817064b JA |
190 | eq->kobj.ktype = &elv_ktype; |
191 | mutex_init(&eq->sysfs_lock); | |
192 | ||
b5deef90 JA |
193 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
194 | GFP_KERNEL, q->node); | |
9817064b JA |
195 | if (!eq->hash) |
196 | goto err; | |
197 | ||
198 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
199 | INIT_HLIST_HEAD(&eq->hash[i]); | |
200 | ||
3d1ab40f | 201 | return eq; |
9817064b JA |
202 | err: |
203 | kfree(eq); | |
204 | elevator_put(e); | |
205 | return NULL; | |
3d1ab40f AV |
206 | } |
207 | ||
208 | static void elevator_release(struct kobject *kobj) | |
209 | { | |
210 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 211 | |
3d1ab40f | 212 | elevator_put(e->elevator_type); |
9817064b | 213 | kfree(e->hash); |
3d1ab40f AV |
214 | kfree(e); |
215 | } | |
216 | ||
165125e1 | 217 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
218 | { |
219 | struct elevator_type *e = NULL; | |
220 | struct elevator_queue *eq; | |
221 | int ret = 0; | |
bc1c1169 | 222 | void *data; |
1da177e4 | 223 | |
cb98fc8b TH |
224 | INIT_LIST_HEAD(&q->queue_head); |
225 | q->last_merge = NULL; | |
226 | q->end_sector = 0; | |
227 | q->boundary_rq = NULL; | |
cb98fc8b | 228 | |
5f003976 | 229 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
230 | return -EINVAL; |
231 | ||
248d5ca5 ND |
232 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
233 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
234 | ||
235 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
236 | printk("Default I/O scheduler not found, using no-op\n"); | |
237 | e = elevator_get("noop"); | |
5f003976 ND |
238 | } |
239 | ||
b5deef90 | 240 | eq = elevator_alloc(q, e); |
3d1ab40f | 241 | if (!eq) |
1da177e4 | 242 | return -ENOMEM; |
1da177e4 | 243 | |
bc1c1169 JA |
244 | data = elevator_init_queue(q, eq); |
245 | if (!data) { | |
3d1ab40f | 246 | kobject_put(&eq->kobj); |
bc1c1169 JA |
247 | return -ENOMEM; |
248 | } | |
1da177e4 | 249 | |
bc1c1169 | 250 | elevator_attach(q, eq, data); |
1da177e4 LT |
251 | return ret; |
252 | } | |
253 | ||
2e662b65 JA |
254 | EXPORT_SYMBOL(elevator_init); |
255 | ||
1da177e4 LT |
256 | void elevator_exit(elevator_t *e) |
257 | { | |
3d1ab40f | 258 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
259 | if (e->ops->elevator_exit_fn) |
260 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
261 | e->ops = NULL; |
262 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 263 | |
3d1ab40f | 264 | kobject_put(&e->kobj); |
1da177e4 LT |
265 | } |
266 | ||
2e662b65 JA |
267 | EXPORT_SYMBOL(elevator_exit); |
268 | ||
165125e1 | 269 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
270 | { |
271 | elevator_t *e = q->elevator; | |
272 | ||
273 | if (e->ops->elevator_activate_req_fn) | |
274 | e->ops->elevator_activate_req_fn(q, rq); | |
275 | } | |
276 | ||
165125e1 | 277 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
278 | { |
279 | elevator_t *e = q->elevator; | |
280 | ||
281 | if (e->ops->elevator_deactivate_req_fn) | |
282 | e->ops->elevator_deactivate_req_fn(q, rq); | |
283 | } | |
284 | ||
9817064b JA |
285 | static inline void __elv_rqhash_del(struct request *rq) |
286 | { | |
287 | hlist_del_init(&rq->hash); | |
288 | } | |
289 | ||
165125e1 | 290 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
291 | { |
292 | if (ELV_ON_HASH(rq)) | |
293 | __elv_rqhash_del(rq); | |
294 | } | |
295 | ||
165125e1 | 296 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b JA |
297 | { |
298 | elevator_t *e = q->elevator; | |
299 | ||
300 | BUG_ON(ELV_ON_HASH(rq)); | |
301 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
302 | } | |
303 | ||
165125e1 | 304 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
305 | { |
306 | __elv_rqhash_del(rq); | |
307 | elv_rqhash_add(q, rq); | |
308 | } | |
309 | ||
165125e1 | 310 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b JA |
311 | { |
312 | elevator_t *e = q->elevator; | |
313 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
314 | struct hlist_node *entry, *next; | |
315 | struct request *rq; | |
316 | ||
317 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
318 | BUG_ON(!ELV_ON_HASH(rq)); | |
319 | ||
320 | if (unlikely(!rq_mergeable(rq))) { | |
321 | __elv_rqhash_del(rq); | |
322 | continue; | |
323 | } | |
324 | ||
325 | if (rq_hash_key(rq) == offset) | |
326 | return rq; | |
327 | } | |
328 | ||
329 | return NULL; | |
330 | } | |
331 | ||
2e662b65 JA |
332 | /* |
333 | * RB-tree support functions for inserting/lookup/removal of requests | |
334 | * in a sorted RB tree. | |
335 | */ | |
336 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
337 | { | |
338 | struct rb_node **p = &root->rb_node; | |
339 | struct rb_node *parent = NULL; | |
340 | struct request *__rq; | |
341 | ||
342 | while (*p) { | |
343 | parent = *p; | |
344 | __rq = rb_entry(parent, struct request, rb_node); | |
345 | ||
346 | if (rq->sector < __rq->sector) | |
347 | p = &(*p)->rb_left; | |
348 | else if (rq->sector > __rq->sector) | |
349 | p = &(*p)->rb_right; | |
350 | else | |
351 | return __rq; | |
352 | } | |
353 | ||
354 | rb_link_node(&rq->rb_node, parent, p); | |
355 | rb_insert_color(&rq->rb_node, root); | |
356 | return NULL; | |
357 | } | |
358 | ||
359 | EXPORT_SYMBOL(elv_rb_add); | |
360 | ||
361 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
362 | { | |
363 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
364 | rb_erase(&rq->rb_node, root); | |
365 | RB_CLEAR_NODE(&rq->rb_node); | |
366 | } | |
367 | ||
368 | EXPORT_SYMBOL(elv_rb_del); | |
369 | ||
370 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
371 | { | |
372 | struct rb_node *n = root->rb_node; | |
373 | struct request *rq; | |
374 | ||
375 | while (n) { | |
376 | rq = rb_entry(n, struct request, rb_node); | |
377 | ||
378 | if (sector < rq->sector) | |
379 | n = n->rb_left; | |
380 | else if (sector > rq->sector) | |
381 | n = n->rb_right; | |
382 | else | |
383 | return rq; | |
384 | } | |
385 | ||
386 | return NULL; | |
387 | } | |
388 | ||
389 | EXPORT_SYMBOL(elv_rb_find); | |
390 | ||
8922e16c TH |
391 | /* |
392 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
2e662b65 JA |
393 | * entry. rq is sort insted into the dispatch queue. To be used by |
394 | * specific elevators. | |
8922e16c | 395 | */ |
165125e1 | 396 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
397 | { |
398 | sector_t boundary; | |
8922e16c TH |
399 | struct list_head *entry; |
400 | ||
06b86245 TH |
401 | if (q->last_merge == rq) |
402 | q->last_merge = NULL; | |
9817064b JA |
403 | |
404 | elv_rqhash_del(q, rq); | |
405 | ||
15853af9 | 406 | q->nr_sorted--; |
06b86245 | 407 | |
1b47f531 | 408 | boundary = q->end_sector; |
cb19833d | 409 | |
8922e16c TH |
410 | list_for_each_prev(entry, &q->queue_head) { |
411 | struct request *pos = list_entry_rq(entry); | |
412 | ||
783660b2 JA |
413 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
414 | break; | |
4aff5e23 | 415 | if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) |
8922e16c TH |
416 | break; |
417 | if (rq->sector >= boundary) { | |
418 | if (pos->sector < boundary) | |
419 | continue; | |
420 | } else { | |
421 | if (pos->sector >= boundary) | |
422 | break; | |
423 | } | |
424 | if (rq->sector >= pos->sector) | |
425 | break; | |
426 | } | |
427 | ||
428 | list_add(&rq->queuelist, entry); | |
429 | } | |
430 | ||
2e662b65 JA |
431 | EXPORT_SYMBOL(elv_dispatch_sort); |
432 | ||
9817064b | 433 | /* |
2e662b65 JA |
434 | * Insert rq into dispatch queue of q. Queue lock must be held on |
435 | * entry. rq is added to the back of the dispatch queue. To be used by | |
436 | * specific elevators. | |
9817064b JA |
437 | */ |
438 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
439 | { | |
440 | if (q->last_merge == rq) | |
441 | q->last_merge = NULL; | |
442 | ||
443 | elv_rqhash_del(q, rq); | |
444 | ||
445 | q->nr_sorted--; | |
446 | ||
447 | q->end_sector = rq_end_sector(rq); | |
448 | q->boundary_rq = rq; | |
449 | list_add_tail(&rq->queuelist, &q->queue_head); | |
450 | } | |
451 | ||
2e662b65 JA |
452 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
453 | ||
165125e1 | 454 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 LT |
455 | { |
456 | elevator_t *e = q->elevator; | |
9817064b | 457 | struct request *__rq; |
06b86245 TH |
458 | int ret; |
459 | ||
9817064b JA |
460 | /* |
461 | * First try one-hit cache. | |
462 | */ | |
06b86245 TH |
463 | if (q->last_merge) { |
464 | ret = elv_try_merge(q->last_merge, bio); | |
465 | if (ret != ELEVATOR_NO_MERGE) { | |
466 | *req = q->last_merge; | |
467 | return ret; | |
468 | } | |
469 | } | |
1da177e4 | 470 | |
9817064b JA |
471 | /* |
472 | * See if our hash lookup can find a potential backmerge. | |
473 | */ | |
474 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
475 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
476 | *req = __rq; | |
477 | return ELEVATOR_BACK_MERGE; | |
478 | } | |
479 | ||
1da177e4 LT |
480 | if (e->ops->elevator_merge_fn) |
481 | return e->ops->elevator_merge_fn(q, req, bio); | |
482 | ||
483 | return ELEVATOR_NO_MERGE; | |
484 | } | |
485 | ||
165125e1 | 486 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 LT |
487 | { |
488 | elevator_t *e = q->elevator; | |
489 | ||
490 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 491 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 492 | |
2e662b65 JA |
493 | if (type == ELEVATOR_BACK_MERGE) |
494 | elv_rqhash_reposition(q, rq); | |
9817064b | 495 | |
06b86245 | 496 | q->last_merge = rq; |
1da177e4 LT |
497 | } |
498 | ||
165125e1 | 499 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
500 | struct request *next) |
501 | { | |
502 | elevator_t *e = q->elevator; | |
503 | ||
1da177e4 LT |
504 | if (e->ops->elevator_merge_req_fn) |
505 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 506 | |
9817064b JA |
507 | elv_rqhash_reposition(q, rq); |
508 | elv_rqhash_del(q, next); | |
509 | ||
510 | q->nr_sorted--; | |
06b86245 | 511 | q->last_merge = rq; |
1da177e4 LT |
512 | } |
513 | ||
165125e1 | 514 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 515 | { |
1da177e4 LT |
516 | /* |
517 | * it already went through dequeue, we need to decrement the | |
518 | * in_flight count again | |
519 | */ | |
8922e16c | 520 | if (blk_account_rq(rq)) { |
1da177e4 | 521 | q->in_flight--; |
cad97516 JA |
522 | if (blk_sorted_rq(rq)) |
523 | elv_deactivate_rq(q, rq); | |
8922e16c | 524 | } |
1da177e4 | 525 | |
4aff5e23 | 526 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 527 | |
30e9656c | 528 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
529 | } |
530 | ||
165125e1 | 531 | static void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
532 | { |
533 | static int printed; | |
534 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
535 | ; | |
536 | if (q->nr_sorted == 0) | |
537 | return; | |
538 | if (printed++ < 10) { | |
539 | printk(KERN_ERR "%s: forced dispatching is broken " | |
540 | "(nr_sorted=%u), please report this\n", | |
541 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
542 | } | |
543 | } | |
544 | ||
165125e1 | 545 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 546 | { |
797e7dbb TH |
547 | struct list_head *pos; |
548 | unsigned ordseq; | |
dac07ec1 | 549 | int unplug_it = 1; |
797e7dbb | 550 | |
2056a782 JA |
551 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
552 | ||
1da177e4 LT |
553 | rq->q = q; |
554 | ||
8922e16c TH |
555 | switch (where) { |
556 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 557 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
558 | |
559 | list_add(&rq->queuelist, &q->queue_head); | |
560 | break; | |
561 | ||
562 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 563 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 564 | elv_drain_elevator(q); |
8922e16c TH |
565 | list_add_tail(&rq->queuelist, &q->queue_head); |
566 | /* | |
567 | * We kick the queue here for the following reasons. | |
568 | * - The elevator might have returned NULL previously | |
569 | * to delay requests and returned them now. As the | |
570 | * queue wasn't empty before this request, ll_rw_blk | |
571 | * won't run the queue on return, resulting in hang. | |
572 | * - Usually, back inserted requests won't be merged | |
573 | * with anything. There's no point in delaying queue | |
574 | * processing. | |
575 | */ | |
576 | blk_remove_plug(q); | |
577 | q->request_fn(q); | |
578 | break; | |
579 | ||
580 | case ELEVATOR_INSERT_SORT: | |
581 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 582 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 583 | q->nr_sorted++; |
9817064b JA |
584 | if (rq_mergeable(rq)) { |
585 | elv_rqhash_add(q, rq); | |
586 | if (!q->last_merge) | |
587 | q->last_merge = rq; | |
588 | } | |
589 | ||
ca23509f TH |
590 | /* |
591 | * Some ioscheds (cfq) run q->request_fn directly, so | |
592 | * rq cannot be accessed after calling | |
593 | * elevator_add_req_fn. | |
594 | */ | |
595 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
596 | break; |
597 | ||
797e7dbb TH |
598 | case ELEVATOR_INSERT_REQUEUE: |
599 | /* | |
600 | * If ordered flush isn't in progress, we do front | |
601 | * insertion; otherwise, requests should be requeued | |
602 | * in ordseq order. | |
603 | */ | |
4aff5e23 | 604 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 605 | |
95543179 LV |
606 | /* |
607 | * Most requeues happen because of a busy condition, | |
608 | * don't force unplug of the queue for that case. | |
609 | */ | |
610 | unplug_it = 0; | |
611 | ||
797e7dbb TH |
612 | if (q->ordseq == 0) { |
613 | list_add(&rq->queuelist, &q->queue_head); | |
614 | break; | |
615 | } | |
616 | ||
617 | ordseq = blk_ordered_req_seq(rq); | |
618 | ||
619 | list_for_each(pos, &q->queue_head) { | |
620 | struct request *pos_rq = list_entry_rq(pos); | |
621 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
622 | break; | |
623 | } | |
624 | ||
625 | list_add_tail(&rq->queuelist, pos); | |
626 | break; | |
627 | ||
8922e16c TH |
628 | default: |
629 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
630 | __FUNCTION__, where); | |
631 | BUG(); | |
632 | } | |
633 | ||
dac07ec1 | 634 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
635 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
636 | - q->in_flight; | |
637 | ||
638 | if (nrq >= q->unplug_thresh) | |
639 | __generic_unplug_device(q); | |
640 | } | |
1da177e4 LT |
641 | } |
642 | ||
165125e1 | 643 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
644 | int plug) |
645 | { | |
646 | if (q->ordcolor) | |
4aff5e23 | 647 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 648 | |
4aff5e23 | 649 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
650 | /* |
651 | * toggle ordered color | |
652 | */ | |
653 | if (blk_barrier_rq(rq)) | |
654 | q->ordcolor ^= 1; | |
655 | ||
656 | /* | |
657 | * barriers implicitly indicate back insertion | |
658 | */ | |
659 | if (where == ELEVATOR_INSERT_SORT) | |
660 | where = ELEVATOR_INSERT_BACK; | |
661 | ||
662 | /* | |
663 | * this request is scheduling boundary, update | |
664 | * end_sector | |
665 | */ | |
666 | if (blk_fs_request(rq)) { | |
667 | q->end_sector = rq_end_sector(rq); | |
668 | q->boundary_rq = rq; | |
669 | } | |
4aff5e23 | 670 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) |
30e9656c TH |
671 | where = ELEVATOR_INSERT_BACK; |
672 | ||
673 | if (plug) | |
674 | blk_plug_device(q); | |
675 | ||
676 | elv_insert(q, rq, where); | |
677 | } | |
678 | ||
2e662b65 JA |
679 | EXPORT_SYMBOL(__elv_add_request); |
680 | ||
165125e1 | 681 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
682 | int plug) |
683 | { | |
684 | unsigned long flags; | |
685 | ||
686 | spin_lock_irqsave(q->queue_lock, flags); | |
687 | __elv_add_request(q, rq, where, plug); | |
688 | spin_unlock_irqrestore(q->queue_lock, flags); | |
689 | } | |
690 | ||
2e662b65 JA |
691 | EXPORT_SYMBOL(elv_add_request); |
692 | ||
165125e1 | 693 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 694 | { |
8922e16c TH |
695 | struct request *rq; |
696 | ||
797e7dbb TH |
697 | while (1) { |
698 | while (!list_empty(&q->queue_head)) { | |
699 | rq = list_entry_rq(q->queue_head.next); | |
700 | if (blk_do_ordered(q, &rq)) | |
701 | return rq; | |
702 | } | |
1da177e4 | 703 | |
797e7dbb TH |
704 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
705 | return NULL; | |
1da177e4 | 706 | } |
1da177e4 LT |
707 | } |
708 | ||
165125e1 | 709 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
710 | { |
711 | struct request *rq; | |
712 | int ret; | |
713 | ||
714 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 715 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
716 | /* |
717 | * This is the first time the device driver | |
718 | * sees this request (possibly after | |
719 | * requeueing). Notify IO scheduler. | |
720 | */ | |
cad97516 JA |
721 | if (blk_sorted_rq(rq)) |
722 | elv_activate_rq(q, rq); | |
1da177e4 | 723 | |
8922e16c TH |
724 | /* |
725 | * just mark as started even if we don't start | |
726 | * it, a request that has been delayed should | |
727 | * not be passed by new incoming requests | |
728 | */ | |
4aff5e23 | 729 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 730 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 731 | } |
1da177e4 | 732 | |
8922e16c | 733 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 734 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
735 | q->boundary_rq = NULL; |
736 | } | |
1da177e4 | 737 | |
4aff5e23 | 738 | if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn) |
1da177e4 LT |
739 | break; |
740 | ||
741 | ret = q->prep_rq_fn(q, rq); | |
742 | if (ret == BLKPREP_OK) { | |
743 | break; | |
744 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
745 | /* |
746 | * the request may have been (partially) prepped. | |
747 | * we need to keep this request in the front to | |
8922e16c TH |
748 | * avoid resource deadlock. REQ_STARTED will |
749 | * prevent other fs requests from passing this one. | |
2e759cd4 | 750 | */ |
1da177e4 LT |
751 | rq = NULL; |
752 | break; | |
753 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 754 | rq->cmd_flags |= REQ_QUIET; |
a0cd1285 | 755 | end_queued_request(rq, 0); |
1da177e4 LT |
756 | } else { |
757 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
758 | ret); | |
759 | break; | |
760 | } | |
761 | } | |
762 | ||
763 | return rq; | |
764 | } | |
765 | ||
2e662b65 JA |
766 | EXPORT_SYMBOL(elv_next_request); |
767 | ||
165125e1 | 768 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 769 | { |
8922e16c | 770 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 771 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
772 | |
773 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
774 | |
775 | /* | |
776 | * the time frame between a request being removed from the lists | |
777 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 778 | * the driver side. |
1da177e4 LT |
779 | */ |
780 | if (blk_account_rq(rq)) | |
781 | q->in_flight++; | |
1da177e4 LT |
782 | } |
783 | ||
2e662b65 JA |
784 | EXPORT_SYMBOL(elv_dequeue_request); |
785 | ||
165125e1 | 786 | int elv_queue_empty(struct request_queue *q) |
1da177e4 LT |
787 | { |
788 | elevator_t *e = q->elevator; | |
789 | ||
8922e16c TH |
790 | if (!list_empty(&q->queue_head)) |
791 | return 0; | |
792 | ||
1da177e4 LT |
793 | if (e->ops->elevator_queue_empty_fn) |
794 | return e->ops->elevator_queue_empty_fn(q); | |
795 | ||
8922e16c | 796 | return 1; |
1da177e4 LT |
797 | } |
798 | ||
2e662b65 JA |
799 | EXPORT_SYMBOL(elv_queue_empty); |
800 | ||
165125e1 | 801 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 802 | { |
1da177e4 LT |
803 | elevator_t *e = q->elevator; |
804 | ||
805 | if (e->ops->elevator_latter_req_fn) | |
806 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
807 | return NULL; |
808 | } | |
809 | ||
165125e1 | 810 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 811 | { |
1da177e4 LT |
812 | elevator_t *e = q->elevator; |
813 | ||
814 | if (e->ops->elevator_former_req_fn) | |
815 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
816 | return NULL; |
817 | } | |
818 | ||
165125e1 | 819 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
820 | { |
821 | elevator_t *e = q->elevator; | |
822 | ||
823 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 824 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
825 | |
826 | rq->elevator_private = NULL; | |
827 | return 0; | |
828 | } | |
829 | ||
165125e1 | 830 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
831 | { |
832 | elevator_t *e = q->elevator; | |
833 | ||
834 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 835 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
836 | } |
837 | ||
165125e1 | 838 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 LT |
839 | { |
840 | elevator_t *e = q->elevator; | |
841 | ||
842 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 843 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
844 | |
845 | return ELV_MQUEUE_MAY; | |
846 | } | |
847 | ||
165125e1 | 848 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
849 | { |
850 | elevator_t *e = q->elevator; | |
851 | ||
852 | /* | |
853 | * request is released from the driver, io must be done | |
854 | */ | |
8922e16c | 855 | if (blk_account_rq(rq)) { |
1da177e4 | 856 | q->in_flight--; |
1bc691d3 TH |
857 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
858 | e->ops->elevator_completed_req_fn(q, rq); | |
859 | } | |
797e7dbb | 860 | |
1bc691d3 TH |
861 | /* |
862 | * Check if the queue is waiting for fs requests to be | |
863 | * drained for flush sequence. | |
864 | */ | |
865 | if (unlikely(q->ordseq)) { | |
866 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
867 | if (q->in_flight == 0 && | |
797e7dbb TH |
868 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
869 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
870 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
871 | q->request_fn(q); | |
872 | } | |
8922e16c | 873 | } |
1da177e4 LT |
874 | } |
875 | ||
3d1ab40f AV |
876 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
877 | ||
878 | static ssize_t | |
879 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 880 | { |
3d1ab40f AV |
881 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
882 | struct elv_fs_entry *entry = to_elv(attr); | |
883 | ssize_t error; | |
884 | ||
885 | if (!entry->show) | |
886 | return -EIO; | |
887 | ||
888 | mutex_lock(&e->sysfs_lock); | |
889 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
890 | mutex_unlock(&e->sysfs_lock); | |
891 | return error; | |
892 | } | |
1da177e4 | 893 | |
3d1ab40f AV |
894 | static ssize_t |
895 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
896 | const char *page, size_t length) | |
897 | { | |
898 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
899 | struct elv_fs_entry *entry = to_elv(attr); | |
900 | ssize_t error; | |
1da177e4 | 901 | |
3d1ab40f AV |
902 | if (!entry->store) |
903 | return -EIO; | |
1da177e4 | 904 | |
3d1ab40f AV |
905 | mutex_lock(&e->sysfs_lock); |
906 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
907 | mutex_unlock(&e->sysfs_lock); | |
908 | return error; | |
909 | } | |
910 | ||
911 | static struct sysfs_ops elv_sysfs_ops = { | |
912 | .show = elv_attr_show, | |
913 | .store = elv_attr_store, | |
914 | }; | |
915 | ||
916 | static struct kobj_type elv_ktype = { | |
917 | .sysfs_ops = &elv_sysfs_ops, | |
918 | .release = elevator_release, | |
919 | }; | |
920 | ||
921 | int elv_register_queue(struct request_queue *q) | |
922 | { | |
923 | elevator_t *e = q->elevator; | |
924 | int error; | |
925 | ||
926 | e->kobj.parent = &q->kobj; | |
927 | ||
928 | error = kobject_add(&e->kobj); | |
929 | if (!error) { | |
e572ec7e | 930 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 931 | if (attr) { |
e572ec7e AV |
932 | while (attr->attr.name) { |
933 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 934 | break; |
e572ec7e | 935 | attr++; |
3d1ab40f AV |
936 | } |
937 | } | |
938 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
939 | } | |
940 | return error; | |
1da177e4 LT |
941 | } |
942 | ||
bc1c1169 JA |
943 | static void __elv_unregister_queue(elevator_t *e) |
944 | { | |
945 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
946 | kobject_del(&e->kobj); | |
947 | } | |
948 | ||
1da177e4 LT |
949 | void elv_unregister_queue(struct request_queue *q) |
950 | { | |
bc1c1169 JA |
951 | if (q) |
952 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
953 | } |
954 | ||
955 | int elv_register(struct elevator_type *e) | |
956 | { | |
1ffb96c5 | 957 | char *def = ""; |
2a12dcd7 JA |
958 | |
959 | spin_lock(&elv_list_lock); | |
ce524497 | 960 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 961 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 962 | spin_unlock(&elv_list_lock); |
1da177e4 | 963 | |
5f003976 ND |
964 | if (!strcmp(e->elevator_name, chosen_elevator) || |
965 | (!*chosen_elevator && | |
966 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
967 | def = " (default)"; |
968 | ||
969 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, def); | |
1da177e4 LT |
970 | return 0; |
971 | } | |
972 | EXPORT_SYMBOL_GPL(elv_register); | |
973 | ||
974 | void elv_unregister(struct elevator_type *e) | |
975 | { | |
83521d3e CH |
976 | struct task_struct *g, *p; |
977 | ||
978 | /* | |
979 | * Iterate every thread in the process to remove the io contexts. | |
980 | */ | |
e17a9489 AV |
981 | if (e->ops.trim) { |
982 | read_lock(&tasklist_lock); | |
983 | do_each_thread(g, p) { | |
984 | task_lock(p); | |
2d8f6131 ON |
985 | if (p->io_context) |
986 | e->ops.trim(p->io_context); | |
e17a9489 AV |
987 | task_unlock(p); |
988 | } while_each_thread(g, p); | |
989 | read_unlock(&tasklist_lock); | |
990 | } | |
83521d3e | 991 | |
2a12dcd7 | 992 | spin_lock(&elv_list_lock); |
1da177e4 | 993 | list_del_init(&e->list); |
2a12dcd7 | 994 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
995 | } |
996 | EXPORT_SYMBOL_GPL(elv_unregister); | |
997 | ||
998 | /* | |
999 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1000 | * we don't free the old io scheduler, before we have allocated what we | |
1001 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1002 | * one, if the new one fails init for some reason. |
1da177e4 | 1003 | */ |
165125e1 | 1004 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1005 | { |
cb98fc8b | 1006 | elevator_t *old_elevator, *e; |
bc1c1169 | 1007 | void *data; |
1da177e4 | 1008 | |
cb98fc8b TH |
1009 | /* |
1010 | * Allocate new elevator | |
1011 | */ | |
b5deef90 | 1012 | e = elevator_alloc(q, new_e); |
1da177e4 | 1013 | if (!e) |
3d1ab40f | 1014 | return 0; |
1da177e4 | 1015 | |
bc1c1169 JA |
1016 | data = elevator_init_queue(q, e); |
1017 | if (!data) { | |
1018 | kobject_put(&e->kobj); | |
1019 | return 0; | |
1020 | } | |
1021 | ||
1da177e4 | 1022 | /* |
cb98fc8b | 1023 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1024 | */ |
cb98fc8b TH |
1025 | spin_lock_irq(q->queue_lock); |
1026 | ||
64521d1a | 1027 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 1028 | |
15853af9 | 1029 | elv_drain_elevator(q); |
cb98fc8b TH |
1030 | |
1031 | while (q->rq.elvpriv) { | |
407df2aa TH |
1032 | blk_remove_plug(q); |
1033 | q->request_fn(q); | |
cb98fc8b | 1034 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1035 | msleep(10); |
cb98fc8b | 1036 | spin_lock_irq(q->queue_lock); |
15853af9 | 1037 | elv_drain_elevator(q); |
cb98fc8b TH |
1038 | } |
1039 | ||
1da177e4 | 1040 | /* |
bc1c1169 | 1041 | * Remember old elevator. |
1da177e4 | 1042 | */ |
1da177e4 LT |
1043 | old_elevator = q->elevator; |
1044 | ||
1da177e4 LT |
1045 | /* |
1046 | * attach and start new elevator | |
1047 | */ | |
bc1c1169 JA |
1048 | elevator_attach(q, e, data); |
1049 | ||
1050 | spin_unlock_irq(q->queue_lock); | |
1051 | ||
1052 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1053 | |
1054 | if (elv_register_queue(q)) | |
1055 | goto fail_register; | |
1056 | ||
1057 | /* | |
cb98fc8b | 1058 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1059 | */ |
1060 | elevator_exit(old_elevator); | |
64521d1a | 1061 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1062 | return 1; |
1da177e4 LT |
1063 | |
1064 | fail_register: | |
1065 | /* | |
1066 | * switch failed, exit the new io scheduler and reattach the old | |
1067 | * one again (along with re-adding the sysfs dir) | |
1068 | */ | |
1069 | elevator_exit(e); | |
1da177e4 LT |
1070 | q->elevator = old_elevator; |
1071 | elv_register_queue(q); | |
64521d1a | 1072 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1073 | return 0; |
1da177e4 LT |
1074 | } |
1075 | ||
165125e1 JA |
1076 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1077 | size_t count) | |
1da177e4 LT |
1078 | { |
1079 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1080 | size_t len; |
1da177e4 LT |
1081 | struct elevator_type *e; |
1082 | ||
be561235 TH |
1083 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1084 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1085 | len = strlen(elevator_name); | |
1da177e4 | 1086 | |
be561235 TH |
1087 | if (len && elevator_name[len - 1] == '\n') |
1088 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1089 | |
1090 | e = elevator_get(elevator_name); | |
1091 | if (!e) { | |
1092 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1093 | return -EINVAL; | |
1094 | } | |
1095 | ||
2ca7d93b ND |
1096 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1097 | elevator_put(e); | |
1da177e4 | 1098 | return count; |
2ca7d93b | 1099 | } |
1da177e4 | 1100 | |
3d1ab40f AV |
1101 | if (!elevator_switch(q, e)) |
1102 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
1103 | return count; |
1104 | } | |
1105 | ||
165125e1 | 1106 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 LT |
1107 | { |
1108 | elevator_t *e = q->elevator; | |
1109 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1110 | struct elevator_type *__e; |
1da177e4 LT |
1111 | int len = 0; |
1112 | ||
2a12dcd7 | 1113 | spin_lock(&elv_list_lock); |
70cee26e | 1114 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1115 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1116 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1117 | else | |
1118 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1119 | } | |
2a12dcd7 | 1120 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1121 | |
1122 | len += sprintf(len+name, "\n"); | |
1123 | return len; | |
1124 | } | |
1125 | ||
165125e1 JA |
1126 | struct request *elv_rb_former_request(struct request_queue *q, |
1127 | struct request *rq) | |
2e662b65 JA |
1128 | { |
1129 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1130 | ||
1131 | if (rbprev) | |
1132 | return rb_entry_rq(rbprev); | |
1133 | ||
1134 | return NULL; | |
1135 | } | |
1136 | ||
1137 | EXPORT_SYMBOL(elv_rb_former_request); | |
1138 | ||
165125e1 JA |
1139 | struct request *elv_rb_latter_request(struct request_queue *q, |
1140 | struct request *rq) | |
2e662b65 JA |
1141 | { |
1142 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1143 | ||
1144 | if (rbnext) | |
1145 | return rb_entry_rq(rbnext); | |
1146 | ||
1147 | return NULL; | |
1148 | } | |
1149 | ||
1150 | EXPORT_SYMBOL(elv_rb_latter_request); |