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> |
5f3ea37c | 36 | #include <trace/block.h> |
9817064b | 37 | #include <linux/hash.h> |
0835da67 | 38 | #include <linux/uaccess.h> |
1da177e4 | 39 | |
242f9dcb JA |
40 | #include "blk.h" |
41 | ||
1da177e4 LT |
42 | static DEFINE_SPINLOCK(elv_list_lock); |
43 | static LIST_HEAD(elv_list); | |
44 | ||
0bfc2455 IM |
45 | DEFINE_TRACE(block_rq_abort); |
46 | ||
9817064b JA |
47 | /* |
48 | * Merge hash stuff. | |
49 | */ | |
50 | static const int elv_hash_shift = 6; | |
51 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
52 | #define ELV_HASH_FN(sec) \ |
53 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b | 54 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
83096ebf | 55 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 56 | |
0bfc2455 IM |
57 | DEFINE_TRACE(block_rq_insert); |
58 | DEFINE_TRACE(block_rq_issue); | |
59 | ||
da775265 JA |
60 | /* |
61 | * Query io scheduler to see if the current process issuing bio may be | |
62 | * merged with rq. | |
63 | */ | |
64 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
65 | { | |
165125e1 | 66 | struct request_queue *q = rq->q; |
b374d18a | 67 | struct elevator_queue *e = q->elevator; |
da775265 JA |
68 | |
69 | if (e->ops->elevator_allow_merge_fn) | |
70 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
71 | ||
72 | return 1; | |
73 | } | |
74 | ||
1da177e4 LT |
75 | /* |
76 | * can we safely merge with this request? | |
77 | */ | |
72ed0bf6 | 78 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
79 | { |
80 | if (!rq_mergeable(rq)) | |
81 | return 0; | |
82 | ||
e17fc0a1 DW |
83 | /* |
84 | * Don't merge file system requests and discard requests | |
85 | */ | |
86 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
87 | return 0; | |
88 | ||
1da177e4 LT |
89 | /* |
90 | * different data direction or already started, don't merge | |
91 | */ | |
92 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
93 | return 0; | |
94 | ||
95 | /* | |
da775265 | 96 | * must be same device and not a special request |
1da177e4 | 97 | */ |
bb4067e3 | 98 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
99 | return 0; |
100 | ||
7ba1ba12 MP |
101 | /* |
102 | * only merge integrity protected bio into ditto rq | |
103 | */ | |
104 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
105 | return 0; | |
106 | ||
da775265 JA |
107 | if (!elv_iosched_allow_merge(rq, bio)) |
108 | return 0; | |
1da177e4 | 109 | |
da775265 | 110 | return 1; |
1da177e4 LT |
111 | } |
112 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
113 | ||
769db45b | 114 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
115 | { |
116 | int ret = ELEVATOR_NO_MERGE; | |
117 | ||
118 | /* | |
119 | * we can merge and sequence is ok, check if it's possible | |
120 | */ | |
121 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 122 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 123 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 124 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
125 | ret = ELEVATOR_FRONT_MERGE; |
126 | } | |
127 | ||
128 | return ret; | |
129 | } | |
1da177e4 | 130 | |
1da177e4 LT |
131 | static struct elevator_type *elevator_find(const char *name) |
132 | { | |
a22b169d | 133 | struct elevator_type *e; |
1da177e4 | 134 | |
70cee26e | 135 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
136 | if (!strcmp(e->elevator_name, name)) |
137 | return e; | |
1da177e4 | 138 | } |
1da177e4 | 139 | |
a22b169d | 140 | return NULL; |
1da177e4 LT |
141 | } |
142 | ||
143 | static void elevator_put(struct elevator_type *e) | |
144 | { | |
145 | module_put(e->elevator_owner); | |
146 | } | |
147 | ||
148 | static struct elevator_type *elevator_get(const char *name) | |
149 | { | |
2824bc93 | 150 | struct elevator_type *e; |
1da177e4 | 151 | |
2a12dcd7 | 152 | spin_lock(&elv_list_lock); |
2824bc93 TH |
153 | |
154 | e = elevator_find(name); | |
e1640949 JA |
155 | if (!e) { |
156 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
157 | ||
158 | spin_unlock(&elv_list_lock); | |
159 | ||
160 | if (!strcmp(name, "anticipatory")) | |
161 | sprintf(elv, "as-iosched"); | |
162 | else | |
163 | sprintf(elv, "%s-iosched", name); | |
164 | ||
e180f594 | 165 | request_module("%s", elv); |
e1640949 JA |
166 | spin_lock(&elv_list_lock); |
167 | e = elevator_find(name); | |
168 | } | |
169 | ||
2824bc93 TH |
170 | if (e && !try_module_get(e->elevator_owner)) |
171 | e = NULL; | |
172 | ||
2a12dcd7 | 173 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
174 | |
175 | return e; | |
176 | } | |
177 | ||
165125e1 JA |
178 | static void *elevator_init_queue(struct request_queue *q, |
179 | struct elevator_queue *eq) | |
1da177e4 | 180 | { |
bb37b94c | 181 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 182 | } |
1da177e4 | 183 | |
165125e1 | 184 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
185 | void *data) |
186 | { | |
1da177e4 | 187 | q->elevator = eq; |
bc1c1169 | 188 | eq->elevator_data = data; |
1da177e4 LT |
189 | } |
190 | ||
191 | static char chosen_elevator[16]; | |
192 | ||
5f003976 | 193 | static int __init elevator_setup(char *str) |
1da177e4 | 194 | { |
752a3b79 CE |
195 | /* |
196 | * Be backwards-compatible with previous kernels, so users | |
197 | * won't get the wrong elevator. | |
198 | */ | |
5f003976 | 199 | if (!strcmp(str, "as")) |
752a3b79 | 200 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 201 | else |
5f003976 | 202 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 203 | return 1; |
1da177e4 LT |
204 | } |
205 | ||
206 | __setup("elevator=", elevator_setup); | |
207 | ||
3d1ab40f AV |
208 | static struct kobj_type elv_ktype; |
209 | ||
b374d18a | 210 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 211 | struct elevator_type *e) |
3d1ab40f | 212 | { |
b374d18a | 213 | struct elevator_queue *eq; |
9817064b JA |
214 | int i; |
215 | ||
b374d18a | 216 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
217 | if (unlikely(!eq)) |
218 | goto err; | |
219 | ||
9817064b JA |
220 | eq->ops = &e->ops; |
221 | eq->elevator_type = e; | |
f9cb074b | 222 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
223 | mutex_init(&eq->sysfs_lock); |
224 | ||
b5deef90 JA |
225 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
226 | GFP_KERNEL, q->node); | |
9817064b JA |
227 | if (!eq->hash) |
228 | goto err; | |
229 | ||
230 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
231 | INIT_HLIST_HEAD(&eq->hash[i]); | |
232 | ||
3d1ab40f | 233 | return eq; |
9817064b JA |
234 | err: |
235 | kfree(eq); | |
236 | elevator_put(e); | |
237 | return NULL; | |
3d1ab40f AV |
238 | } |
239 | ||
240 | static void elevator_release(struct kobject *kobj) | |
241 | { | |
b374d18a | 242 | struct elevator_queue *e; |
9817064b | 243 | |
b374d18a | 244 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 245 | elevator_put(e->elevator_type); |
9817064b | 246 | kfree(e->hash); |
3d1ab40f AV |
247 | kfree(e); |
248 | } | |
249 | ||
165125e1 | 250 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
251 | { |
252 | struct elevator_type *e = NULL; | |
253 | struct elevator_queue *eq; | |
254 | int ret = 0; | |
bc1c1169 | 255 | void *data; |
1da177e4 | 256 | |
cb98fc8b TH |
257 | INIT_LIST_HEAD(&q->queue_head); |
258 | q->last_merge = NULL; | |
259 | q->end_sector = 0; | |
260 | q->boundary_rq = NULL; | |
cb98fc8b | 261 | |
4eb166d9 JA |
262 | if (name) { |
263 | e = elevator_get(name); | |
264 | if (!e) | |
265 | return -EINVAL; | |
266 | } | |
1da177e4 | 267 | |
4eb166d9 JA |
268 | if (!e && *chosen_elevator) { |
269 | e = elevator_get(chosen_elevator); | |
270 | if (!e) | |
271 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
272 | chosen_elevator); | |
273 | } | |
248d5ca5 | 274 | |
4eb166d9 JA |
275 | if (!e) { |
276 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
277 | if (!e) { | |
278 | printk(KERN_ERR | |
279 | "Default I/O scheduler not found. " \ | |
280 | "Using noop.\n"); | |
281 | e = elevator_get("noop"); | |
282 | } | |
5f003976 ND |
283 | } |
284 | ||
b5deef90 | 285 | eq = elevator_alloc(q, e); |
3d1ab40f | 286 | if (!eq) |
1da177e4 | 287 | return -ENOMEM; |
1da177e4 | 288 | |
bc1c1169 JA |
289 | data = elevator_init_queue(q, eq); |
290 | if (!data) { | |
3d1ab40f | 291 | kobject_put(&eq->kobj); |
bc1c1169 JA |
292 | return -ENOMEM; |
293 | } | |
1da177e4 | 294 | |
bc1c1169 | 295 | elevator_attach(q, eq, data); |
1da177e4 LT |
296 | return ret; |
297 | } | |
2e662b65 JA |
298 | EXPORT_SYMBOL(elevator_init); |
299 | ||
b374d18a | 300 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 301 | { |
3d1ab40f | 302 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
303 | if (e->ops->elevator_exit_fn) |
304 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
305 | e->ops = NULL; |
306 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 307 | |
3d1ab40f | 308 | kobject_put(&e->kobj); |
1da177e4 | 309 | } |
2e662b65 JA |
310 | EXPORT_SYMBOL(elevator_exit); |
311 | ||
9817064b JA |
312 | static inline void __elv_rqhash_del(struct request *rq) |
313 | { | |
314 | hlist_del_init(&rq->hash); | |
315 | } | |
316 | ||
165125e1 | 317 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
318 | { |
319 | if (ELV_ON_HASH(rq)) | |
320 | __elv_rqhash_del(rq); | |
321 | } | |
322 | ||
165125e1 | 323 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 324 | { |
b374d18a | 325 | struct elevator_queue *e = q->elevator; |
9817064b JA |
326 | |
327 | BUG_ON(ELV_ON_HASH(rq)); | |
328 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
329 | } | |
330 | ||
165125e1 | 331 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
332 | { |
333 | __elv_rqhash_del(rq); | |
334 | elv_rqhash_add(q, rq); | |
335 | } | |
336 | ||
165125e1 | 337 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 338 | { |
b374d18a | 339 | struct elevator_queue *e = q->elevator; |
9817064b JA |
340 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
341 | struct hlist_node *entry, *next; | |
342 | struct request *rq; | |
343 | ||
344 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
345 | BUG_ON(!ELV_ON_HASH(rq)); | |
346 | ||
347 | if (unlikely(!rq_mergeable(rq))) { | |
348 | __elv_rqhash_del(rq); | |
349 | continue; | |
350 | } | |
351 | ||
352 | if (rq_hash_key(rq) == offset) | |
353 | return rq; | |
354 | } | |
355 | ||
356 | return NULL; | |
357 | } | |
358 | ||
2e662b65 JA |
359 | /* |
360 | * RB-tree support functions for inserting/lookup/removal of requests | |
361 | * in a sorted RB tree. | |
362 | */ | |
363 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
364 | { | |
365 | struct rb_node **p = &root->rb_node; | |
366 | struct rb_node *parent = NULL; | |
367 | struct request *__rq; | |
368 | ||
369 | while (*p) { | |
370 | parent = *p; | |
371 | __rq = rb_entry(parent, struct request, rb_node); | |
372 | ||
83096ebf | 373 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 374 | p = &(*p)->rb_left; |
83096ebf | 375 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
376 | p = &(*p)->rb_right; |
377 | else | |
378 | return __rq; | |
379 | } | |
380 | ||
381 | rb_link_node(&rq->rb_node, parent, p); | |
382 | rb_insert_color(&rq->rb_node, root); | |
383 | return NULL; | |
384 | } | |
2e662b65 JA |
385 | EXPORT_SYMBOL(elv_rb_add); |
386 | ||
387 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
388 | { | |
389 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
390 | rb_erase(&rq->rb_node, root); | |
391 | RB_CLEAR_NODE(&rq->rb_node); | |
392 | } | |
2e662b65 JA |
393 | EXPORT_SYMBOL(elv_rb_del); |
394 | ||
395 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
396 | { | |
397 | struct rb_node *n = root->rb_node; | |
398 | struct request *rq; | |
399 | ||
400 | while (n) { | |
401 | rq = rb_entry(n, struct request, rb_node); | |
402 | ||
83096ebf | 403 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 404 | n = n->rb_left; |
83096ebf | 405 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
406 | n = n->rb_right; |
407 | else | |
408 | return rq; | |
409 | } | |
410 | ||
411 | return NULL; | |
412 | } | |
2e662b65 JA |
413 | EXPORT_SYMBOL(elv_rb_find); |
414 | ||
8922e16c TH |
415 | /* |
416 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 417 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 418 | * specific elevators. |
8922e16c | 419 | */ |
165125e1 | 420 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
421 | { |
422 | sector_t boundary; | |
8922e16c | 423 | struct list_head *entry; |
4eb166d9 | 424 | int stop_flags; |
8922e16c | 425 | |
06b86245 TH |
426 | if (q->last_merge == rq) |
427 | q->last_merge = NULL; | |
9817064b JA |
428 | |
429 | elv_rqhash_del(q, rq); | |
430 | ||
15853af9 | 431 | q->nr_sorted--; |
06b86245 | 432 | |
1b47f531 | 433 | boundary = q->end_sector; |
4eb166d9 | 434 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
435 | list_for_each_prev(entry, &q->queue_head) { |
436 | struct request *pos = list_entry_rq(entry); | |
437 | ||
e17fc0a1 DW |
438 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
439 | break; | |
783660b2 JA |
440 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
441 | break; | |
4eb166d9 | 442 | if (pos->cmd_flags & stop_flags) |
8922e16c | 443 | break; |
83096ebf TH |
444 | if (blk_rq_pos(rq) >= boundary) { |
445 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
446 | continue; |
447 | } else { | |
83096ebf | 448 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
449 | break; |
450 | } | |
83096ebf | 451 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
452 | break; |
453 | } | |
454 | ||
455 | list_add(&rq->queuelist, entry); | |
456 | } | |
2e662b65 JA |
457 | EXPORT_SYMBOL(elv_dispatch_sort); |
458 | ||
9817064b | 459 | /* |
2e662b65 JA |
460 | * Insert rq into dispatch queue of q. Queue lock must be held on |
461 | * entry. rq is added to the back of the dispatch queue. To be used by | |
462 | * specific elevators. | |
9817064b JA |
463 | */ |
464 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
465 | { | |
466 | if (q->last_merge == rq) | |
467 | q->last_merge = NULL; | |
468 | ||
469 | elv_rqhash_del(q, rq); | |
470 | ||
471 | q->nr_sorted--; | |
472 | ||
473 | q->end_sector = rq_end_sector(rq); | |
474 | q->boundary_rq = rq; | |
475 | list_add_tail(&rq->queuelist, &q->queue_head); | |
476 | } | |
2e662b65 JA |
477 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
478 | ||
165125e1 | 479 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 480 | { |
b374d18a | 481 | struct elevator_queue *e = q->elevator; |
9817064b | 482 | struct request *__rq; |
06b86245 TH |
483 | int ret; |
484 | ||
9817064b JA |
485 | /* |
486 | * First try one-hit cache. | |
487 | */ | |
06b86245 TH |
488 | if (q->last_merge) { |
489 | ret = elv_try_merge(q->last_merge, bio); | |
490 | if (ret != ELEVATOR_NO_MERGE) { | |
491 | *req = q->last_merge; | |
492 | return ret; | |
493 | } | |
494 | } | |
1da177e4 | 495 | |
ac9fafa1 AB |
496 | if (blk_queue_nomerges(q)) |
497 | return ELEVATOR_NO_MERGE; | |
498 | ||
9817064b JA |
499 | /* |
500 | * See if our hash lookup can find a potential backmerge. | |
501 | */ | |
502 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
503 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
504 | *req = __rq; | |
505 | return ELEVATOR_BACK_MERGE; | |
506 | } | |
507 | ||
1da177e4 LT |
508 | if (e->ops->elevator_merge_fn) |
509 | return e->ops->elevator_merge_fn(q, req, bio); | |
510 | ||
511 | return ELEVATOR_NO_MERGE; | |
512 | } | |
513 | ||
165125e1 | 514 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 515 | { |
b374d18a | 516 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
517 | |
518 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 519 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 520 | |
2e662b65 JA |
521 | if (type == ELEVATOR_BACK_MERGE) |
522 | elv_rqhash_reposition(q, rq); | |
9817064b | 523 | |
06b86245 | 524 | q->last_merge = rq; |
1da177e4 LT |
525 | } |
526 | ||
165125e1 | 527 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
528 | struct request *next) |
529 | { | |
b374d18a | 530 | struct elevator_queue *e = q->elevator; |
1da177e4 | 531 | |
1da177e4 LT |
532 | if (e->ops->elevator_merge_req_fn) |
533 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 534 | |
9817064b JA |
535 | elv_rqhash_reposition(q, rq); |
536 | elv_rqhash_del(q, next); | |
537 | ||
538 | q->nr_sorted--; | |
06b86245 | 539 | q->last_merge = rq; |
1da177e4 LT |
540 | } |
541 | ||
165125e1 | 542 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 543 | { |
1da177e4 LT |
544 | /* |
545 | * it already went through dequeue, we need to decrement the | |
546 | * in_flight count again | |
547 | */ | |
8922e16c | 548 | if (blk_account_rq(rq)) { |
0a7ae2ff | 549 | q->in_flight[rq_is_sync(rq)]--; |
cad97516 JA |
550 | if (blk_sorted_rq(rq)) |
551 | elv_deactivate_rq(q, rq); | |
8922e16c | 552 | } |
1da177e4 | 553 | |
4aff5e23 | 554 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 555 | |
30e9656c | 556 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
557 | } |
558 | ||
26308eab | 559 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
560 | { |
561 | static int printed; | |
562 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
563 | ; | |
564 | if (q->nr_sorted == 0) | |
565 | return; | |
566 | if (printed++ < 10) { | |
567 | printk(KERN_ERR "%s: forced dispatching is broken " | |
568 | "(nr_sorted=%u), please report this\n", | |
569 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
570 | } | |
571 | } | |
572 | ||
6c7e8cee JA |
573 | /* |
574 | * Call with queue lock held, interrupts disabled | |
575 | */ | |
f600abe2 | 576 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 577 | { |
cd43e26f MP |
578 | if (!q->elevator) |
579 | return; | |
580 | ||
6c7e8cee JA |
581 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
582 | ||
583 | /* | |
584 | * make sure we don't have any requests in flight | |
585 | */ | |
586 | elv_drain_elevator(q); | |
587 | while (q->rq.elvpriv) { | |
a7f55792 | 588 | __blk_run_queue(q); |
6c7e8cee JA |
589 | spin_unlock_irq(q->queue_lock); |
590 | msleep(10); | |
591 | spin_lock_irq(q->queue_lock); | |
592 | elv_drain_elevator(q); | |
593 | } | |
594 | } | |
595 | ||
f600abe2 | 596 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
597 | { |
598 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
599 | } | |
600 | ||
165125e1 | 601 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 602 | { |
797e7dbb TH |
603 | struct list_head *pos; |
604 | unsigned ordseq; | |
dac07ec1 | 605 | int unplug_it = 1; |
797e7dbb | 606 | |
5f3ea37c | 607 | trace_block_rq_insert(q, rq); |
2056a782 | 608 | |
1da177e4 LT |
609 | rq->q = q; |
610 | ||
8922e16c TH |
611 | switch (where) { |
612 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 613 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
614 | |
615 | list_add(&rq->queuelist, &q->queue_head); | |
616 | break; | |
617 | ||
618 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 619 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 620 | elv_drain_elevator(q); |
8922e16c TH |
621 | list_add_tail(&rq->queuelist, &q->queue_head); |
622 | /* | |
623 | * We kick the queue here for the following reasons. | |
624 | * - The elevator might have returned NULL previously | |
625 | * to delay requests and returned them now. As the | |
626 | * queue wasn't empty before this request, ll_rw_blk | |
627 | * won't run the queue on return, resulting in hang. | |
628 | * - Usually, back inserted requests won't be merged | |
629 | * with anything. There's no point in delaying queue | |
630 | * processing. | |
631 | */ | |
a7f55792 | 632 | __blk_run_queue(q); |
8922e16c TH |
633 | break; |
634 | ||
635 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 636 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 637 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 638 | q->nr_sorted++; |
9817064b JA |
639 | if (rq_mergeable(rq)) { |
640 | elv_rqhash_add(q, rq); | |
641 | if (!q->last_merge) | |
642 | q->last_merge = rq; | |
643 | } | |
644 | ||
ca23509f TH |
645 | /* |
646 | * Some ioscheds (cfq) run q->request_fn directly, so | |
647 | * rq cannot be accessed after calling | |
648 | * elevator_add_req_fn. | |
649 | */ | |
650 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
651 | break; |
652 | ||
797e7dbb TH |
653 | case ELEVATOR_INSERT_REQUEUE: |
654 | /* | |
655 | * If ordered flush isn't in progress, we do front | |
656 | * insertion; otherwise, requests should be requeued | |
657 | * in ordseq order. | |
658 | */ | |
4aff5e23 | 659 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 660 | |
95543179 LV |
661 | /* |
662 | * Most requeues happen because of a busy condition, | |
663 | * don't force unplug of the queue for that case. | |
664 | */ | |
665 | unplug_it = 0; | |
666 | ||
797e7dbb TH |
667 | if (q->ordseq == 0) { |
668 | list_add(&rq->queuelist, &q->queue_head); | |
669 | break; | |
670 | } | |
671 | ||
672 | ordseq = blk_ordered_req_seq(rq); | |
673 | ||
674 | list_for_each(pos, &q->queue_head) { | |
675 | struct request *pos_rq = list_entry_rq(pos); | |
676 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
677 | break; | |
678 | } | |
679 | ||
680 | list_add_tail(&rq->queuelist, pos); | |
681 | break; | |
682 | ||
8922e16c TH |
683 | default: |
684 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 685 | __func__, where); |
8922e16c TH |
686 | BUG(); |
687 | } | |
688 | ||
dac07ec1 | 689 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 690 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
0a7ae2ff | 691 | - queue_in_flight(q); |
8922e16c TH |
692 | |
693 | if (nrq >= q->unplug_thresh) | |
694 | __generic_unplug_device(q); | |
695 | } | |
1da177e4 LT |
696 | } |
697 | ||
165125e1 | 698 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
699 | int plug) |
700 | { | |
701 | if (q->ordcolor) | |
4aff5e23 | 702 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 703 | |
4aff5e23 | 704 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
705 | /* |
706 | * toggle ordered color | |
707 | */ | |
708 | if (blk_barrier_rq(rq)) | |
709 | q->ordcolor ^= 1; | |
710 | ||
711 | /* | |
712 | * barriers implicitly indicate back insertion | |
713 | */ | |
714 | if (where == ELEVATOR_INSERT_SORT) | |
715 | where = ELEVATOR_INSERT_BACK; | |
716 | ||
717 | /* | |
718 | * this request is scheduling boundary, update | |
719 | * end_sector | |
720 | */ | |
e17fc0a1 | 721 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
722 | q->end_sector = rq_end_sector(rq); |
723 | q->boundary_rq = rq; | |
724 | } | |
4eb166d9 JA |
725 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
726 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
727 | where = ELEVATOR_INSERT_BACK; |
728 | ||
729 | if (plug) | |
730 | blk_plug_device(q); | |
731 | ||
732 | elv_insert(q, rq, where); | |
733 | } | |
2e662b65 JA |
734 | EXPORT_SYMBOL(__elv_add_request); |
735 | ||
165125e1 | 736 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
737 | int plug) |
738 | { | |
739 | unsigned long flags; | |
740 | ||
741 | spin_lock_irqsave(q->queue_lock, flags); | |
742 | __elv_add_request(q, rq, where, plug); | |
743 | spin_unlock_irqrestore(q->queue_lock, flags); | |
744 | } | |
2e662b65 JA |
745 | EXPORT_SYMBOL(elv_add_request); |
746 | ||
165125e1 | 747 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 748 | { |
b374d18a | 749 | struct elevator_queue *e = q->elevator; |
1da177e4 | 750 | |
8922e16c TH |
751 | if (!list_empty(&q->queue_head)) |
752 | return 0; | |
753 | ||
1da177e4 LT |
754 | if (e->ops->elevator_queue_empty_fn) |
755 | return e->ops->elevator_queue_empty_fn(q); | |
756 | ||
8922e16c | 757 | return 1; |
1da177e4 | 758 | } |
2e662b65 JA |
759 | EXPORT_SYMBOL(elv_queue_empty); |
760 | ||
165125e1 | 761 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 762 | { |
b374d18a | 763 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
764 | |
765 | if (e->ops->elevator_latter_req_fn) | |
766 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
767 | return NULL; |
768 | } | |
769 | ||
165125e1 | 770 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 771 | { |
b374d18a | 772 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
773 | |
774 | if (e->ops->elevator_former_req_fn) | |
775 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
776 | return NULL; |
777 | } | |
778 | ||
165125e1 | 779 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 780 | { |
b374d18a | 781 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
782 | |
783 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 784 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
785 | |
786 | rq->elevator_private = NULL; | |
787 | return 0; | |
788 | } | |
789 | ||
165125e1 | 790 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 791 | { |
b374d18a | 792 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
793 | |
794 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 795 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
796 | } |
797 | ||
165125e1 | 798 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 799 | { |
b374d18a | 800 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
801 | |
802 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 803 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
804 | |
805 | return ELV_MQUEUE_MAY; | |
806 | } | |
807 | ||
11914a53 MA |
808 | void elv_abort_queue(struct request_queue *q) |
809 | { | |
810 | struct request *rq; | |
811 | ||
812 | while (!list_empty(&q->queue_head)) { | |
813 | rq = list_entry_rq(q->queue_head.next); | |
814 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 815 | trace_block_rq_abort(q, rq); |
40cbbb78 | 816 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
817 | } |
818 | } | |
819 | EXPORT_SYMBOL(elv_abort_queue); | |
820 | ||
165125e1 | 821 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 822 | { |
b374d18a | 823 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
824 | |
825 | /* | |
826 | * request is released from the driver, io must be done | |
827 | */ | |
8922e16c | 828 | if (blk_account_rq(rq)) { |
0a7ae2ff | 829 | q->in_flight[rq_is_sync(rq)]--; |
1bc691d3 TH |
830 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
831 | e->ops->elevator_completed_req_fn(q, rq); | |
832 | } | |
797e7dbb | 833 | |
1bc691d3 TH |
834 | /* |
835 | * Check if the queue is waiting for fs requests to be | |
836 | * drained for flush sequence. | |
837 | */ | |
838 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
839 | struct request *next = NULL; |
840 | ||
841 | if (!list_empty(&q->queue_head)) | |
842 | next = list_entry_rq(q->queue_head.next); | |
843 | ||
0a7ae2ff | 844 | if (!queue_in_flight(q) && |
797e7dbb | 845 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 846 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 847 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
a7f55792 | 848 | __blk_run_queue(q); |
797e7dbb | 849 | } |
8922e16c | 850 | } |
1da177e4 LT |
851 | } |
852 | ||
3d1ab40f AV |
853 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
854 | ||
855 | static ssize_t | |
856 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 857 | { |
3d1ab40f | 858 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 859 | struct elevator_queue *e; |
3d1ab40f AV |
860 | ssize_t error; |
861 | ||
862 | if (!entry->show) | |
863 | return -EIO; | |
864 | ||
b374d18a | 865 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
866 | mutex_lock(&e->sysfs_lock); |
867 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
868 | mutex_unlock(&e->sysfs_lock); | |
869 | return error; | |
870 | } | |
1da177e4 | 871 | |
3d1ab40f AV |
872 | static ssize_t |
873 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
874 | const char *page, size_t length) | |
875 | { | |
3d1ab40f | 876 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 877 | struct elevator_queue *e; |
3d1ab40f | 878 | ssize_t error; |
1da177e4 | 879 | |
3d1ab40f AV |
880 | if (!entry->store) |
881 | return -EIO; | |
1da177e4 | 882 | |
b374d18a | 883 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
884 | mutex_lock(&e->sysfs_lock); |
885 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
886 | mutex_unlock(&e->sysfs_lock); | |
887 | return error; | |
888 | } | |
889 | ||
890 | static struct sysfs_ops elv_sysfs_ops = { | |
891 | .show = elv_attr_show, | |
892 | .store = elv_attr_store, | |
893 | }; | |
894 | ||
895 | static struct kobj_type elv_ktype = { | |
896 | .sysfs_ops = &elv_sysfs_ops, | |
897 | .release = elevator_release, | |
898 | }; | |
899 | ||
900 | int elv_register_queue(struct request_queue *q) | |
901 | { | |
b374d18a | 902 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
903 | int error; |
904 | ||
b2d6db58 | 905 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 906 | if (!error) { |
e572ec7e | 907 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 908 | if (attr) { |
e572ec7e AV |
909 | while (attr->attr.name) { |
910 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 911 | break; |
e572ec7e | 912 | attr++; |
3d1ab40f AV |
913 | } |
914 | } | |
915 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
916 | } | |
917 | return error; | |
1da177e4 LT |
918 | } |
919 | ||
b374d18a | 920 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
921 | { |
922 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
923 | kobject_del(&e->kobj); | |
924 | } | |
925 | ||
1da177e4 LT |
926 | void elv_unregister_queue(struct request_queue *q) |
927 | { | |
bc1c1169 JA |
928 | if (q) |
929 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
930 | } |
931 | ||
2fdd82bd | 932 | void elv_register(struct elevator_type *e) |
1da177e4 | 933 | { |
1ffb96c5 | 934 | char *def = ""; |
2a12dcd7 JA |
935 | |
936 | spin_lock(&elv_list_lock); | |
ce524497 | 937 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 938 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 939 | spin_unlock(&elv_list_lock); |
1da177e4 | 940 | |
5f003976 ND |
941 | if (!strcmp(e->elevator_name, chosen_elevator) || |
942 | (!*chosen_elevator && | |
943 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
944 | def = " (default)"; |
945 | ||
4eb166d9 JA |
946 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
947 | def); | |
1da177e4 LT |
948 | } |
949 | EXPORT_SYMBOL_GPL(elv_register); | |
950 | ||
951 | void elv_unregister(struct elevator_type *e) | |
952 | { | |
83521d3e CH |
953 | struct task_struct *g, *p; |
954 | ||
955 | /* | |
956 | * Iterate every thread in the process to remove the io contexts. | |
957 | */ | |
e17a9489 AV |
958 | if (e->ops.trim) { |
959 | read_lock(&tasklist_lock); | |
960 | do_each_thread(g, p) { | |
961 | task_lock(p); | |
2d8f6131 ON |
962 | if (p->io_context) |
963 | e->ops.trim(p->io_context); | |
e17a9489 AV |
964 | task_unlock(p); |
965 | } while_each_thread(g, p); | |
966 | read_unlock(&tasklist_lock); | |
967 | } | |
83521d3e | 968 | |
2a12dcd7 | 969 | spin_lock(&elv_list_lock); |
1da177e4 | 970 | list_del_init(&e->list); |
2a12dcd7 | 971 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
972 | } |
973 | EXPORT_SYMBOL_GPL(elv_unregister); | |
974 | ||
975 | /* | |
976 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
977 | * we don't free the old io scheduler, before we have allocated what we | |
978 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 979 | * one, if the new one fails init for some reason. |
1da177e4 | 980 | */ |
165125e1 | 981 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 982 | { |
b374d18a | 983 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 984 | void *data; |
1da177e4 | 985 | |
cb98fc8b TH |
986 | /* |
987 | * Allocate new elevator | |
988 | */ | |
b5deef90 | 989 | e = elevator_alloc(q, new_e); |
1da177e4 | 990 | if (!e) |
3d1ab40f | 991 | return 0; |
1da177e4 | 992 | |
bc1c1169 JA |
993 | data = elevator_init_queue(q, e); |
994 | if (!data) { | |
995 | kobject_put(&e->kobj); | |
996 | return 0; | |
997 | } | |
998 | ||
1da177e4 | 999 | /* |
cb98fc8b | 1000 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1001 | */ |
cb98fc8b | 1002 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1003 | elv_quiesce_start(q); |
cb98fc8b | 1004 | |
1da177e4 | 1005 | /* |
bc1c1169 | 1006 | * Remember old elevator. |
1da177e4 | 1007 | */ |
1da177e4 LT |
1008 | old_elevator = q->elevator; |
1009 | ||
1da177e4 LT |
1010 | /* |
1011 | * attach and start new elevator | |
1012 | */ | |
bc1c1169 JA |
1013 | elevator_attach(q, e, data); |
1014 | ||
1015 | spin_unlock_irq(q->queue_lock); | |
1016 | ||
1017 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1018 | |
1019 | if (elv_register_queue(q)) | |
1020 | goto fail_register; | |
1021 | ||
1022 | /* | |
cb98fc8b | 1023 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1024 | */ |
1025 | elevator_exit(old_elevator); | |
75ad23bc | 1026 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1027 | elv_quiesce_end(q); |
75ad23bc NP |
1028 | spin_unlock_irq(q->queue_lock); |
1029 | ||
4722dc52 AB |
1030 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1031 | ||
3d1ab40f | 1032 | return 1; |
1da177e4 LT |
1033 | |
1034 | fail_register: | |
1035 | /* | |
1036 | * switch failed, exit the new io scheduler and reattach the old | |
1037 | * one again (along with re-adding the sysfs dir) | |
1038 | */ | |
1039 | elevator_exit(e); | |
1da177e4 LT |
1040 | q->elevator = old_elevator; |
1041 | elv_register_queue(q); | |
75ad23bc NP |
1042 | |
1043 | spin_lock_irq(q->queue_lock); | |
1044 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1045 | spin_unlock_irq(q->queue_lock); | |
1046 | ||
3d1ab40f | 1047 | return 0; |
1da177e4 LT |
1048 | } |
1049 | ||
165125e1 JA |
1050 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1051 | size_t count) | |
1da177e4 LT |
1052 | { |
1053 | char elevator_name[ELV_NAME_MAX]; | |
1054 | struct elevator_type *e; | |
1055 | ||
cd43e26f MP |
1056 | if (!q->elevator) |
1057 | return count; | |
1058 | ||
ee2e992c LZ |
1059 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1060 | strstrip(elevator_name); | |
1da177e4 LT |
1061 | |
1062 | e = elevator_get(elevator_name); | |
1063 | if (!e) { | |
1064 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1065 | return -EINVAL; | |
1066 | } | |
1067 | ||
2ca7d93b ND |
1068 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1069 | elevator_put(e); | |
1da177e4 | 1070 | return count; |
2ca7d93b | 1071 | } |
1da177e4 | 1072 | |
3d1ab40f | 1073 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1074 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1075 | elevator_name); | |
1da177e4 LT |
1076 | return count; |
1077 | } | |
1078 | ||
165125e1 | 1079 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1080 | { |
b374d18a | 1081 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1082 | struct elevator_type *elv; |
70cee26e | 1083 | struct elevator_type *__e; |
1da177e4 LT |
1084 | int len = 0; |
1085 | ||
cd43e26f MP |
1086 | if (!q->elevator) |
1087 | return sprintf(name, "none\n"); | |
1088 | ||
1089 | elv = e->elevator_type; | |
1090 | ||
2a12dcd7 | 1091 | spin_lock(&elv_list_lock); |
70cee26e | 1092 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1093 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1094 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1095 | else | |
1096 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1097 | } | |
2a12dcd7 | 1098 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1099 | |
1100 | len += sprintf(len+name, "\n"); | |
1101 | return len; | |
1102 | } | |
1103 | ||
165125e1 JA |
1104 | struct request *elv_rb_former_request(struct request_queue *q, |
1105 | struct request *rq) | |
2e662b65 JA |
1106 | { |
1107 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1108 | ||
1109 | if (rbprev) | |
1110 | return rb_entry_rq(rbprev); | |
1111 | ||
1112 | return NULL; | |
1113 | } | |
2e662b65 JA |
1114 | EXPORT_SYMBOL(elv_rb_former_request); |
1115 | ||
165125e1 JA |
1116 | struct request *elv_rb_latter_request(struct request_queue *q, |
1117 | struct request *rq) | |
2e662b65 JA |
1118 | { |
1119 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1120 | ||
1121 | if (rbnext) | |
1122 | return rb_entry_rq(rbnext); | |
1123 | ||
1124 | return NULL; | |
1125 | } | |
2e662b65 | 1126 | EXPORT_SYMBOL(elv_rb_latter_request); |