Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
29 | #include <linux/bio.h> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
cb98fc8b | 34 | #include <linux/delay.h> |
2056a782 | 35 | #include <linux/blktrace_api.h> |
9817064b | 36 | #include <linux/hash.h> |
0835da67 | 37 | #include <linux/uaccess.h> |
1da177e4 | 38 | |
55782138 LZ |
39 | #include <trace/events/block.h> |
40 | ||
242f9dcb JA |
41 | #include "blk.h" |
42 | ||
1da177e4 LT |
43 | static DEFINE_SPINLOCK(elv_list_lock); |
44 | static LIST_HEAD(elv_list); | |
45 | ||
9817064b JA |
46 | /* |
47 | * Merge hash stuff. | |
48 | */ | |
49 | static const int elv_hash_shift = 6; | |
50 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
51 | #define ELV_HASH_FN(sec) \ |
52 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b | 53 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
83096ebf | 54 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 55 | |
da775265 JA |
56 | /* |
57 | * Query io scheduler to see if the current process issuing bio may be | |
58 | * merged with rq. | |
59 | */ | |
60 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
61 | { | |
165125e1 | 62 | struct request_queue *q = rq->q; |
b374d18a | 63 | struct elevator_queue *e = q->elevator; |
da775265 JA |
64 | |
65 | if (e->ops->elevator_allow_merge_fn) | |
66 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
67 | ||
68 | return 1; | |
69 | } | |
70 | ||
1da177e4 LT |
71 | /* |
72 | * can we safely merge with this request? | |
73 | */ | |
72ed0bf6 | 74 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
75 | { |
76 | if (!rq_mergeable(rq)) | |
77 | return 0; | |
78 | ||
e17fc0a1 DW |
79 | /* |
80 | * Don't merge file system requests and discard requests | |
81 | */ | |
1f98a13f JA |
82 | if (bio_rw_flagged(bio, BIO_RW_DISCARD) != |
83 | bio_rw_flagged(rq->bio, BIO_RW_DISCARD)) | |
e17fc0a1 DW |
84 | return 0; |
85 | ||
1da177e4 LT |
86 | /* |
87 | * different data direction or already started, don't merge | |
88 | */ | |
89 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
90 | return 0; | |
91 | ||
92 | /* | |
da775265 | 93 | * must be same device and not a special request |
1da177e4 | 94 | */ |
bb4067e3 | 95 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
96 | return 0; |
97 | ||
7ba1ba12 MP |
98 | /* |
99 | * only merge integrity protected bio into ditto rq | |
100 | */ | |
101 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
102 | return 0; | |
103 | ||
da775265 JA |
104 | if (!elv_iosched_allow_merge(rq, bio)) |
105 | return 0; | |
1da177e4 | 106 | |
da775265 | 107 | return 1; |
1da177e4 LT |
108 | } |
109 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
110 | ||
769db45b | 111 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
112 | { |
113 | int ret = ELEVATOR_NO_MERGE; | |
114 | ||
115 | /* | |
116 | * we can merge and sequence is ok, check if it's possible | |
117 | */ | |
118 | if (elv_rq_merge_ok(__rq, bio)) { | |
83096ebf | 119 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 120 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 121 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
122 | ret = ELEVATOR_FRONT_MERGE; |
123 | } | |
124 | ||
125 | return ret; | |
126 | } | |
1da177e4 | 127 | |
1da177e4 LT |
128 | static struct elevator_type *elevator_find(const char *name) |
129 | { | |
a22b169d | 130 | struct elevator_type *e; |
1da177e4 | 131 | |
70cee26e | 132 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
133 | if (!strcmp(e->elevator_name, name)) |
134 | return e; | |
1da177e4 | 135 | } |
1da177e4 | 136 | |
a22b169d | 137 | return NULL; |
1da177e4 LT |
138 | } |
139 | ||
140 | static void elevator_put(struct elevator_type *e) | |
141 | { | |
142 | module_put(e->elevator_owner); | |
143 | } | |
144 | ||
145 | static struct elevator_type *elevator_get(const char *name) | |
146 | { | |
2824bc93 | 147 | struct elevator_type *e; |
1da177e4 | 148 | |
2a12dcd7 | 149 | spin_lock(&elv_list_lock); |
2824bc93 TH |
150 | |
151 | e = elevator_find(name); | |
e1640949 JA |
152 | if (!e) { |
153 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
154 | ||
155 | spin_unlock(&elv_list_lock); | |
156 | ||
157 | if (!strcmp(name, "anticipatory")) | |
158 | sprintf(elv, "as-iosched"); | |
159 | else | |
160 | sprintf(elv, "%s-iosched", name); | |
161 | ||
e180f594 | 162 | request_module("%s", elv); |
e1640949 JA |
163 | spin_lock(&elv_list_lock); |
164 | e = elevator_find(name); | |
165 | } | |
166 | ||
2824bc93 TH |
167 | if (e && !try_module_get(e->elevator_owner)) |
168 | e = NULL; | |
169 | ||
2a12dcd7 | 170 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
171 | |
172 | return e; | |
173 | } | |
174 | ||
165125e1 JA |
175 | static void *elevator_init_queue(struct request_queue *q, |
176 | struct elevator_queue *eq) | |
1da177e4 | 177 | { |
bb37b94c | 178 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 179 | } |
1da177e4 | 180 | |
165125e1 | 181 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
182 | void *data) |
183 | { | |
1da177e4 | 184 | q->elevator = eq; |
bc1c1169 | 185 | eq->elevator_data = data; |
1da177e4 LT |
186 | } |
187 | ||
188 | static char chosen_elevator[16]; | |
189 | ||
5f003976 | 190 | static int __init elevator_setup(char *str) |
1da177e4 | 191 | { |
752a3b79 CE |
192 | /* |
193 | * Be backwards-compatible with previous kernels, so users | |
194 | * won't get the wrong elevator. | |
195 | */ | |
5f003976 | 196 | if (!strcmp(str, "as")) |
752a3b79 | 197 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 198 | else |
5f003976 | 199 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 200 | return 1; |
1da177e4 LT |
201 | } |
202 | ||
203 | __setup("elevator=", elevator_setup); | |
204 | ||
3d1ab40f AV |
205 | static struct kobj_type elv_ktype; |
206 | ||
b374d18a | 207 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 208 | struct elevator_type *e) |
3d1ab40f | 209 | { |
b374d18a | 210 | struct elevator_queue *eq; |
9817064b JA |
211 | int i; |
212 | ||
b374d18a | 213 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
214 | if (unlikely(!eq)) |
215 | goto err; | |
216 | ||
9817064b JA |
217 | eq->ops = &e->ops; |
218 | eq->elevator_type = e; | |
f9cb074b | 219 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
220 | mutex_init(&eq->sysfs_lock); |
221 | ||
b5deef90 JA |
222 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
223 | GFP_KERNEL, q->node); | |
9817064b JA |
224 | if (!eq->hash) |
225 | goto err; | |
226 | ||
227 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
228 | INIT_HLIST_HEAD(&eq->hash[i]); | |
229 | ||
3d1ab40f | 230 | return eq; |
9817064b JA |
231 | err: |
232 | kfree(eq); | |
233 | elevator_put(e); | |
234 | return NULL; | |
3d1ab40f AV |
235 | } |
236 | ||
237 | static void elevator_release(struct kobject *kobj) | |
238 | { | |
b374d18a | 239 | struct elevator_queue *e; |
9817064b | 240 | |
b374d18a | 241 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 242 | elevator_put(e->elevator_type); |
9817064b | 243 | kfree(e->hash); |
3d1ab40f AV |
244 | kfree(e); |
245 | } | |
246 | ||
165125e1 | 247 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
248 | { |
249 | struct elevator_type *e = NULL; | |
250 | struct elevator_queue *eq; | |
251 | int ret = 0; | |
bc1c1169 | 252 | void *data; |
1da177e4 | 253 | |
cb98fc8b TH |
254 | INIT_LIST_HEAD(&q->queue_head); |
255 | q->last_merge = NULL; | |
256 | q->end_sector = 0; | |
257 | q->boundary_rq = NULL; | |
cb98fc8b | 258 | |
4eb166d9 JA |
259 | if (name) { |
260 | e = elevator_get(name); | |
261 | if (!e) | |
262 | return -EINVAL; | |
263 | } | |
1da177e4 | 264 | |
4eb166d9 JA |
265 | if (!e && *chosen_elevator) { |
266 | e = elevator_get(chosen_elevator); | |
267 | if (!e) | |
268 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
269 | chosen_elevator); | |
270 | } | |
248d5ca5 | 271 | |
4eb166d9 JA |
272 | if (!e) { |
273 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
274 | if (!e) { | |
275 | printk(KERN_ERR | |
276 | "Default I/O scheduler not found. " \ | |
277 | "Using noop.\n"); | |
278 | e = elevator_get("noop"); | |
279 | } | |
5f003976 ND |
280 | } |
281 | ||
b5deef90 | 282 | eq = elevator_alloc(q, e); |
3d1ab40f | 283 | if (!eq) |
1da177e4 | 284 | return -ENOMEM; |
1da177e4 | 285 | |
bc1c1169 JA |
286 | data = elevator_init_queue(q, eq); |
287 | if (!data) { | |
3d1ab40f | 288 | kobject_put(&eq->kobj); |
bc1c1169 JA |
289 | return -ENOMEM; |
290 | } | |
1da177e4 | 291 | |
bc1c1169 | 292 | elevator_attach(q, eq, data); |
1da177e4 LT |
293 | return ret; |
294 | } | |
2e662b65 JA |
295 | EXPORT_SYMBOL(elevator_init); |
296 | ||
b374d18a | 297 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 298 | { |
3d1ab40f | 299 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
300 | if (e->ops->elevator_exit_fn) |
301 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
302 | e->ops = NULL; |
303 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 304 | |
3d1ab40f | 305 | kobject_put(&e->kobj); |
1da177e4 | 306 | } |
2e662b65 JA |
307 | EXPORT_SYMBOL(elevator_exit); |
308 | ||
9817064b JA |
309 | static inline void __elv_rqhash_del(struct request *rq) |
310 | { | |
311 | hlist_del_init(&rq->hash); | |
312 | } | |
313 | ||
165125e1 | 314 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
315 | { |
316 | if (ELV_ON_HASH(rq)) | |
317 | __elv_rqhash_del(rq); | |
318 | } | |
319 | ||
165125e1 | 320 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 321 | { |
b374d18a | 322 | struct elevator_queue *e = q->elevator; |
9817064b JA |
323 | |
324 | BUG_ON(ELV_ON_HASH(rq)); | |
325 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
326 | } | |
327 | ||
165125e1 | 328 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
329 | { |
330 | __elv_rqhash_del(rq); | |
331 | elv_rqhash_add(q, rq); | |
332 | } | |
333 | ||
165125e1 | 334 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 335 | { |
b374d18a | 336 | struct elevator_queue *e = q->elevator; |
9817064b JA |
337 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
338 | struct hlist_node *entry, *next; | |
339 | struct request *rq; | |
340 | ||
341 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
342 | BUG_ON(!ELV_ON_HASH(rq)); | |
343 | ||
344 | if (unlikely(!rq_mergeable(rq))) { | |
345 | __elv_rqhash_del(rq); | |
346 | continue; | |
347 | } | |
348 | ||
349 | if (rq_hash_key(rq) == offset) | |
350 | return rq; | |
351 | } | |
352 | ||
353 | return NULL; | |
354 | } | |
355 | ||
2e662b65 JA |
356 | /* |
357 | * RB-tree support functions for inserting/lookup/removal of requests | |
358 | * in a sorted RB tree. | |
359 | */ | |
360 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
361 | { | |
362 | struct rb_node **p = &root->rb_node; | |
363 | struct rb_node *parent = NULL; | |
364 | struct request *__rq; | |
365 | ||
366 | while (*p) { | |
367 | parent = *p; | |
368 | __rq = rb_entry(parent, struct request, rb_node); | |
369 | ||
83096ebf | 370 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 371 | p = &(*p)->rb_left; |
83096ebf | 372 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
2e662b65 JA |
373 | p = &(*p)->rb_right; |
374 | else | |
375 | return __rq; | |
376 | } | |
377 | ||
378 | rb_link_node(&rq->rb_node, parent, p); | |
379 | rb_insert_color(&rq->rb_node, root); | |
380 | return NULL; | |
381 | } | |
2e662b65 JA |
382 | EXPORT_SYMBOL(elv_rb_add); |
383 | ||
384 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
385 | { | |
386 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
387 | rb_erase(&rq->rb_node, root); | |
388 | RB_CLEAR_NODE(&rq->rb_node); | |
389 | } | |
2e662b65 JA |
390 | EXPORT_SYMBOL(elv_rb_del); |
391 | ||
392 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
393 | { | |
394 | struct rb_node *n = root->rb_node; | |
395 | struct request *rq; | |
396 | ||
397 | while (n) { | |
398 | rq = rb_entry(n, struct request, rb_node); | |
399 | ||
83096ebf | 400 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 401 | n = n->rb_left; |
83096ebf | 402 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
403 | n = n->rb_right; |
404 | else | |
405 | return rq; | |
406 | } | |
407 | ||
408 | return NULL; | |
409 | } | |
2e662b65 JA |
410 | EXPORT_SYMBOL(elv_rb_find); |
411 | ||
8922e16c TH |
412 | /* |
413 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 414 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 415 | * specific elevators. |
8922e16c | 416 | */ |
165125e1 | 417 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
418 | { |
419 | sector_t boundary; | |
8922e16c | 420 | struct list_head *entry; |
4eb166d9 | 421 | int stop_flags; |
8922e16c | 422 | |
06b86245 TH |
423 | if (q->last_merge == rq) |
424 | q->last_merge = NULL; | |
9817064b JA |
425 | |
426 | elv_rqhash_del(q, rq); | |
427 | ||
15853af9 | 428 | q->nr_sorted--; |
06b86245 | 429 | |
1b47f531 | 430 | boundary = q->end_sector; |
4eb166d9 | 431 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
432 | list_for_each_prev(entry, &q->queue_head) { |
433 | struct request *pos = list_entry_rq(entry); | |
434 | ||
e17fc0a1 DW |
435 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
436 | break; | |
783660b2 JA |
437 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
438 | break; | |
4eb166d9 | 439 | if (pos->cmd_flags & stop_flags) |
8922e16c | 440 | break; |
83096ebf TH |
441 | if (blk_rq_pos(rq) >= boundary) { |
442 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
443 | continue; |
444 | } else { | |
83096ebf | 445 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
446 | break; |
447 | } | |
83096ebf | 448 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
449 | break; |
450 | } | |
451 | ||
452 | list_add(&rq->queuelist, entry); | |
453 | } | |
2e662b65 JA |
454 | EXPORT_SYMBOL(elv_dispatch_sort); |
455 | ||
9817064b | 456 | /* |
2e662b65 JA |
457 | * Insert rq into dispatch queue of q. Queue lock must be held on |
458 | * entry. rq is added to the back of the dispatch queue. To be used by | |
459 | * specific elevators. | |
9817064b JA |
460 | */ |
461 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
462 | { | |
463 | if (q->last_merge == rq) | |
464 | q->last_merge = NULL; | |
465 | ||
466 | elv_rqhash_del(q, rq); | |
467 | ||
468 | q->nr_sorted--; | |
469 | ||
470 | q->end_sector = rq_end_sector(rq); | |
471 | q->boundary_rq = rq; | |
472 | list_add_tail(&rq->queuelist, &q->queue_head); | |
473 | } | |
2e662b65 JA |
474 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
475 | ||
165125e1 | 476 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 477 | { |
b374d18a | 478 | struct elevator_queue *e = q->elevator; |
9817064b | 479 | struct request *__rq; |
06b86245 TH |
480 | int ret; |
481 | ||
9817064b JA |
482 | /* |
483 | * First try one-hit cache. | |
484 | */ | |
06b86245 TH |
485 | if (q->last_merge) { |
486 | ret = elv_try_merge(q->last_merge, bio); | |
487 | if (ret != ELEVATOR_NO_MERGE) { | |
488 | *req = q->last_merge; | |
489 | return ret; | |
490 | } | |
491 | } | |
1da177e4 | 492 | |
ac9fafa1 AB |
493 | if (blk_queue_nomerges(q)) |
494 | return ELEVATOR_NO_MERGE; | |
495 | ||
9817064b JA |
496 | /* |
497 | * See if our hash lookup can find a potential backmerge. | |
498 | */ | |
499 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
500 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
501 | *req = __rq; | |
502 | return ELEVATOR_BACK_MERGE; | |
503 | } | |
504 | ||
1da177e4 LT |
505 | if (e->ops->elevator_merge_fn) |
506 | return e->ops->elevator_merge_fn(q, req, bio); | |
507 | ||
508 | return ELEVATOR_NO_MERGE; | |
509 | } | |
510 | ||
165125e1 | 511 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 512 | { |
b374d18a | 513 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
514 | |
515 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 516 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 517 | |
2e662b65 JA |
518 | if (type == ELEVATOR_BACK_MERGE) |
519 | elv_rqhash_reposition(q, rq); | |
9817064b | 520 | |
06b86245 | 521 | q->last_merge = rq; |
1da177e4 LT |
522 | } |
523 | ||
165125e1 | 524 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
525 | struct request *next) |
526 | { | |
b374d18a | 527 | struct elevator_queue *e = q->elevator; |
1da177e4 | 528 | |
1da177e4 LT |
529 | if (e->ops->elevator_merge_req_fn) |
530 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 531 | |
9817064b JA |
532 | elv_rqhash_reposition(q, rq); |
533 | elv_rqhash_del(q, next); | |
534 | ||
535 | q->nr_sorted--; | |
06b86245 | 536 | q->last_merge = rq; |
1da177e4 LT |
537 | } |
538 | ||
165125e1 | 539 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 540 | { |
1da177e4 LT |
541 | /* |
542 | * it already went through dequeue, we need to decrement the | |
543 | * in_flight count again | |
544 | */ | |
8922e16c | 545 | if (blk_account_rq(rq)) { |
0a7ae2ff | 546 | q->in_flight[rq_is_sync(rq)]--; |
cad97516 JA |
547 | if (blk_sorted_rq(rq)) |
548 | elv_deactivate_rq(q, rq); | |
8922e16c | 549 | } |
1da177e4 | 550 | |
4aff5e23 | 551 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 552 | |
30e9656c | 553 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
554 | } |
555 | ||
26308eab | 556 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
557 | { |
558 | static int printed; | |
559 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
560 | ; | |
561 | if (q->nr_sorted == 0) | |
562 | return; | |
563 | if (printed++ < 10) { | |
564 | printk(KERN_ERR "%s: forced dispatching is broken " | |
565 | "(nr_sorted=%u), please report this\n", | |
566 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
567 | } | |
568 | } | |
569 | ||
6c7e8cee JA |
570 | /* |
571 | * Call with queue lock held, interrupts disabled | |
572 | */ | |
f600abe2 | 573 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 574 | { |
cd43e26f MP |
575 | if (!q->elevator) |
576 | return; | |
577 | ||
6c7e8cee JA |
578 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
579 | ||
580 | /* | |
581 | * make sure we don't have any requests in flight | |
582 | */ | |
583 | elv_drain_elevator(q); | |
584 | while (q->rq.elvpriv) { | |
a7f55792 | 585 | __blk_run_queue(q); |
6c7e8cee JA |
586 | spin_unlock_irq(q->queue_lock); |
587 | msleep(10); | |
588 | spin_lock_irq(q->queue_lock); | |
589 | elv_drain_elevator(q); | |
590 | } | |
591 | } | |
592 | ||
f600abe2 | 593 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
594 | { |
595 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
596 | } | |
597 | ||
165125e1 | 598 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 599 | { |
797e7dbb TH |
600 | struct list_head *pos; |
601 | unsigned ordseq; | |
dac07ec1 | 602 | int unplug_it = 1; |
797e7dbb | 603 | |
5f3ea37c | 604 | trace_block_rq_insert(q, rq); |
2056a782 | 605 | |
1da177e4 LT |
606 | rq->q = q; |
607 | ||
8922e16c TH |
608 | switch (where) { |
609 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 610 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
611 | |
612 | list_add(&rq->queuelist, &q->queue_head); | |
613 | break; | |
614 | ||
615 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 616 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 617 | elv_drain_elevator(q); |
8922e16c TH |
618 | list_add_tail(&rq->queuelist, &q->queue_head); |
619 | /* | |
620 | * We kick the queue here for the following reasons. | |
621 | * - The elevator might have returned NULL previously | |
622 | * to delay requests and returned them now. As the | |
623 | * queue wasn't empty before this request, ll_rw_blk | |
624 | * won't run the queue on return, resulting in hang. | |
625 | * - Usually, back inserted requests won't be merged | |
626 | * with anything. There's no point in delaying queue | |
627 | * processing. | |
628 | */ | |
a7f55792 | 629 | __blk_run_queue(q); |
8922e16c TH |
630 | break; |
631 | ||
632 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 633 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 634 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 635 | q->nr_sorted++; |
9817064b JA |
636 | if (rq_mergeable(rq)) { |
637 | elv_rqhash_add(q, rq); | |
638 | if (!q->last_merge) | |
639 | q->last_merge = rq; | |
640 | } | |
641 | ||
ca23509f TH |
642 | /* |
643 | * Some ioscheds (cfq) run q->request_fn directly, so | |
644 | * rq cannot be accessed after calling | |
645 | * elevator_add_req_fn. | |
646 | */ | |
647 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
648 | break; |
649 | ||
797e7dbb TH |
650 | case ELEVATOR_INSERT_REQUEUE: |
651 | /* | |
652 | * If ordered flush isn't in progress, we do front | |
653 | * insertion; otherwise, requests should be requeued | |
654 | * in ordseq order. | |
655 | */ | |
4aff5e23 | 656 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 657 | |
95543179 LV |
658 | /* |
659 | * Most requeues happen because of a busy condition, | |
660 | * don't force unplug of the queue for that case. | |
661 | */ | |
662 | unplug_it = 0; | |
663 | ||
797e7dbb TH |
664 | if (q->ordseq == 0) { |
665 | list_add(&rq->queuelist, &q->queue_head); | |
666 | break; | |
667 | } | |
668 | ||
669 | ordseq = blk_ordered_req_seq(rq); | |
670 | ||
671 | list_for_each(pos, &q->queue_head) { | |
672 | struct request *pos_rq = list_entry_rq(pos); | |
673 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
674 | break; | |
675 | } | |
676 | ||
677 | list_add_tail(&rq->queuelist, pos); | |
678 | break; | |
679 | ||
8922e16c TH |
680 | default: |
681 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 682 | __func__, where); |
8922e16c TH |
683 | BUG(); |
684 | } | |
685 | ||
dac07ec1 | 686 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 687 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
0a7ae2ff | 688 | - queue_in_flight(q); |
8922e16c TH |
689 | |
690 | if (nrq >= q->unplug_thresh) | |
691 | __generic_unplug_device(q); | |
692 | } | |
1da177e4 LT |
693 | } |
694 | ||
165125e1 | 695 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
696 | int plug) |
697 | { | |
698 | if (q->ordcolor) | |
4aff5e23 | 699 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 700 | |
4aff5e23 | 701 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
702 | /* |
703 | * toggle ordered color | |
704 | */ | |
705 | if (blk_barrier_rq(rq)) | |
706 | q->ordcolor ^= 1; | |
707 | ||
708 | /* | |
709 | * barriers implicitly indicate back insertion | |
710 | */ | |
711 | if (where == ELEVATOR_INSERT_SORT) | |
712 | where = ELEVATOR_INSERT_BACK; | |
713 | ||
714 | /* | |
715 | * this request is scheduling boundary, update | |
716 | * end_sector | |
717 | */ | |
e17fc0a1 | 718 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
719 | q->end_sector = rq_end_sector(rq); |
720 | q->boundary_rq = rq; | |
721 | } | |
4eb166d9 JA |
722 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
723 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
724 | where = ELEVATOR_INSERT_BACK; |
725 | ||
726 | if (plug) | |
727 | blk_plug_device(q); | |
728 | ||
729 | elv_insert(q, rq, where); | |
730 | } | |
2e662b65 JA |
731 | EXPORT_SYMBOL(__elv_add_request); |
732 | ||
165125e1 | 733 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
734 | int plug) |
735 | { | |
736 | unsigned long flags; | |
737 | ||
738 | spin_lock_irqsave(q->queue_lock, flags); | |
739 | __elv_add_request(q, rq, where, plug); | |
740 | spin_unlock_irqrestore(q->queue_lock, flags); | |
741 | } | |
2e662b65 JA |
742 | EXPORT_SYMBOL(elv_add_request); |
743 | ||
165125e1 | 744 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 745 | { |
b374d18a | 746 | struct elevator_queue *e = q->elevator; |
1da177e4 | 747 | |
8922e16c TH |
748 | if (!list_empty(&q->queue_head)) |
749 | return 0; | |
750 | ||
1da177e4 LT |
751 | if (e->ops->elevator_queue_empty_fn) |
752 | return e->ops->elevator_queue_empty_fn(q); | |
753 | ||
8922e16c | 754 | return 1; |
1da177e4 | 755 | } |
2e662b65 JA |
756 | EXPORT_SYMBOL(elv_queue_empty); |
757 | ||
165125e1 | 758 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 759 | { |
b374d18a | 760 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
761 | |
762 | if (e->ops->elevator_latter_req_fn) | |
763 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
764 | return NULL; |
765 | } | |
766 | ||
165125e1 | 767 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 768 | { |
b374d18a | 769 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
770 | |
771 | if (e->ops->elevator_former_req_fn) | |
772 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
773 | return NULL; |
774 | } | |
775 | ||
165125e1 | 776 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 777 | { |
b374d18a | 778 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
779 | |
780 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 781 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
782 | |
783 | rq->elevator_private = NULL; | |
784 | return 0; | |
785 | } | |
786 | ||
165125e1 | 787 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 788 | { |
b374d18a | 789 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
790 | |
791 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 792 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
793 | } |
794 | ||
165125e1 | 795 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 796 | { |
b374d18a | 797 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
798 | |
799 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 800 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
801 | |
802 | return ELV_MQUEUE_MAY; | |
803 | } | |
804 | ||
11914a53 MA |
805 | void elv_abort_queue(struct request_queue *q) |
806 | { | |
807 | struct request *rq; | |
808 | ||
809 | while (!list_empty(&q->queue_head)) { | |
810 | rq = list_entry_rq(q->queue_head.next); | |
811 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 812 | trace_block_rq_abort(q, rq); |
53c663ce KU |
813 | /* |
814 | * Mark this request as started so we don't trigger | |
815 | * any debug logic in the end I/O path. | |
816 | */ | |
817 | blk_start_request(rq); | |
40cbbb78 | 818 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
819 | } |
820 | } | |
821 | EXPORT_SYMBOL(elv_abort_queue); | |
822 | ||
165125e1 | 823 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 824 | { |
b374d18a | 825 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
826 | |
827 | /* | |
828 | * request is released from the driver, io must be done | |
829 | */ | |
8922e16c | 830 | if (blk_account_rq(rq)) { |
0a7ae2ff | 831 | q->in_flight[rq_is_sync(rq)]--; |
1bc691d3 TH |
832 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
833 | e->ops->elevator_completed_req_fn(q, rq); | |
834 | } | |
797e7dbb | 835 | |
1bc691d3 TH |
836 | /* |
837 | * Check if the queue is waiting for fs requests to be | |
838 | * drained for flush sequence. | |
839 | */ | |
840 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
841 | struct request *next = NULL; |
842 | ||
843 | if (!list_empty(&q->queue_head)) | |
844 | next = list_entry_rq(q->queue_head.next); | |
845 | ||
0a7ae2ff | 846 | if (!queue_in_flight(q) && |
797e7dbb | 847 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 848 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 849 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
a7f55792 | 850 | __blk_run_queue(q); |
797e7dbb | 851 | } |
8922e16c | 852 | } |
1da177e4 LT |
853 | } |
854 | ||
3d1ab40f AV |
855 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
856 | ||
857 | static ssize_t | |
858 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 859 | { |
3d1ab40f | 860 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 861 | struct elevator_queue *e; |
3d1ab40f AV |
862 | ssize_t error; |
863 | ||
864 | if (!entry->show) | |
865 | return -EIO; | |
866 | ||
b374d18a | 867 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
868 | mutex_lock(&e->sysfs_lock); |
869 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
870 | mutex_unlock(&e->sysfs_lock); | |
871 | return error; | |
872 | } | |
1da177e4 | 873 | |
3d1ab40f AV |
874 | static ssize_t |
875 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
876 | const char *page, size_t length) | |
877 | { | |
3d1ab40f | 878 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 879 | struct elevator_queue *e; |
3d1ab40f | 880 | ssize_t error; |
1da177e4 | 881 | |
3d1ab40f AV |
882 | if (!entry->store) |
883 | return -EIO; | |
1da177e4 | 884 | |
b374d18a | 885 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
886 | mutex_lock(&e->sysfs_lock); |
887 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
888 | mutex_unlock(&e->sysfs_lock); | |
889 | return error; | |
890 | } | |
891 | ||
892 | static struct sysfs_ops elv_sysfs_ops = { | |
893 | .show = elv_attr_show, | |
894 | .store = elv_attr_store, | |
895 | }; | |
896 | ||
897 | static struct kobj_type elv_ktype = { | |
898 | .sysfs_ops = &elv_sysfs_ops, | |
899 | .release = elevator_release, | |
900 | }; | |
901 | ||
902 | int elv_register_queue(struct request_queue *q) | |
903 | { | |
b374d18a | 904 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
905 | int error; |
906 | ||
b2d6db58 | 907 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 908 | if (!error) { |
e572ec7e | 909 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 910 | if (attr) { |
e572ec7e AV |
911 | while (attr->attr.name) { |
912 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 913 | break; |
e572ec7e | 914 | attr++; |
3d1ab40f AV |
915 | } |
916 | } | |
917 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
918 | } | |
919 | return error; | |
1da177e4 LT |
920 | } |
921 | ||
b374d18a | 922 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
923 | { |
924 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
925 | kobject_del(&e->kobj); | |
926 | } | |
927 | ||
1da177e4 LT |
928 | void elv_unregister_queue(struct request_queue *q) |
929 | { | |
bc1c1169 JA |
930 | if (q) |
931 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
932 | } |
933 | ||
2fdd82bd | 934 | void elv_register(struct elevator_type *e) |
1da177e4 | 935 | { |
1ffb96c5 | 936 | char *def = ""; |
2a12dcd7 JA |
937 | |
938 | spin_lock(&elv_list_lock); | |
ce524497 | 939 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 940 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 941 | spin_unlock(&elv_list_lock); |
1da177e4 | 942 | |
5f003976 ND |
943 | if (!strcmp(e->elevator_name, chosen_elevator) || |
944 | (!*chosen_elevator && | |
945 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
946 | def = " (default)"; |
947 | ||
4eb166d9 JA |
948 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
949 | def); | |
1da177e4 LT |
950 | } |
951 | EXPORT_SYMBOL_GPL(elv_register); | |
952 | ||
953 | void elv_unregister(struct elevator_type *e) | |
954 | { | |
83521d3e CH |
955 | struct task_struct *g, *p; |
956 | ||
957 | /* | |
958 | * Iterate every thread in the process to remove the io contexts. | |
959 | */ | |
e17a9489 AV |
960 | if (e->ops.trim) { |
961 | read_lock(&tasklist_lock); | |
962 | do_each_thread(g, p) { | |
963 | task_lock(p); | |
2d8f6131 ON |
964 | if (p->io_context) |
965 | e->ops.trim(p->io_context); | |
e17a9489 AV |
966 | task_unlock(p); |
967 | } while_each_thread(g, p); | |
968 | read_unlock(&tasklist_lock); | |
969 | } | |
83521d3e | 970 | |
2a12dcd7 | 971 | spin_lock(&elv_list_lock); |
1da177e4 | 972 | list_del_init(&e->list); |
2a12dcd7 | 973 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
974 | } |
975 | EXPORT_SYMBOL_GPL(elv_unregister); | |
976 | ||
977 | /* | |
978 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
979 | * we don't free the old io scheduler, before we have allocated what we | |
980 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 981 | * one, if the new one fails init for some reason. |
1da177e4 | 982 | */ |
165125e1 | 983 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 984 | { |
b374d18a | 985 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 986 | void *data; |
1da177e4 | 987 | |
cb98fc8b TH |
988 | /* |
989 | * Allocate new elevator | |
990 | */ | |
b5deef90 | 991 | e = elevator_alloc(q, new_e); |
1da177e4 | 992 | if (!e) |
3d1ab40f | 993 | return 0; |
1da177e4 | 994 | |
bc1c1169 JA |
995 | data = elevator_init_queue(q, e); |
996 | if (!data) { | |
997 | kobject_put(&e->kobj); | |
998 | return 0; | |
999 | } | |
1000 | ||
1da177e4 | 1001 | /* |
cb98fc8b | 1002 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1003 | */ |
cb98fc8b | 1004 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1005 | elv_quiesce_start(q); |
cb98fc8b | 1006 | |
1da177e4 | 1007 | /* |
bc1c1169 | 1008 | * Remember old elevator. |
1da177e4 | 1009 | */ |
1da177e4 LT |
1010 | old_elevator = q->elevator; |
1011 | ||
1da177e4 LT |
1012 | /* |
1013 | * attach and start new elevator | |
1014 | */ | |
bc1c1169 JA |
1015 | elevator_attach(q, e, data); |
1016 | ||
1017 | spin_unlock_irq(q->queue_lock); | |
1018 | ||
1019 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1020 | |
1021 | if (elv_register_queue(q)) | |
1022 | goto fail_register; | |
1023 | ||
1024 | /* | |
cb98fc8b | 1025 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1026 | */ |
1027 | elevator_exit(old_elevator); | |
75ad23bc | 1028 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1029 | elv_quiesce_end(q); |
75ad23bc NP |
1030 | spin_unlock_irq(q->queue_lock); |
1031 | ||
4722dc52 AB |
1032 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1033 | ||
3d1ab40f | 1034 | return 1; |
1da177e4 LT |
1035 | |
1036 | fail_register: | |
1037 | /* | |
1038 | * switch failed, exit the new io scheduler and reattach the old | |
1039 | * one again (along with re-adding the sysfs dir) | |
1040 | */ | |
1041 | elevator_exit(e); | |
1da177e4 LT |
1042 | q->elevator = old_elevator; |
1043 | elv_register_queue(q); | |
75ad23bc NP |
1044 | |
1045 | spin_lock_irq(q->queue_lock); | |
1046 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1047 | spin_unlock_irq(q->queue_lock); | |
1048 | ||
3d1ab40f | 1049 | return 0; |
1da177e4 LT |
1050 | } |
1051 | ||
165125e1 JA |
1052 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1053 | size_t count) | |
1da177e4 LT |
1054 | { |
1055 | char elevator_name[ELV_NAME_MAX]; | |
1056 | struct elevator_type *e; | |
1057 | ||
cd43e26f MP |
1058 | if (!q->elevator) |
1059 | return count; | |
1060 | ||
ee2e992c LZ |
1061 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1062 | strstrip(elevator_name); | |
1da177e4 LT |
1063 | |
1064 | e = elevator_get(elevator_name); | |
1065 | if (!e) { | |
1066 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1067 | return -EINVAL; | |
1068 | } | |
1069 | ||
2ca7d93b ND |
1070 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1071 | elevator_put(e); | |
1da177e4 | 1072 | return count; |
2ca7d93b | 1073 | } |
1da177e4 | 1074 | |
3d1ab40f | 1075 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1076 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1077 | elevator_name); | |
1da177e4 LT |
1078 | return count; |
1079 | } | |
1080 | ||
165125e1 | 1081 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1082 | { |
b374d18a | 1083 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1084 | struct elevator_type *elv; |
70cee26e | 1085 | struct elevator_type *__e; |
1da177e4 LT |
1086 | int len = 0; |
1087 | ||
cd43e26f MP |
1088 | if (!q->elevator) |
1089 | return sprintf(name, "none\n"); | |
1090 | ||
1091 | elv = e->elevator_type; | |
1092 | ||
2a12dcd7 | 1093 | spin_lock(&elv_list_lock); |
70cee26e | 1094 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1095 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1096 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1097 | else | |
1098 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1099 | } | |
2a12dcd7 | 1100 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1101 | |
1102 | len += sprintf(len+name, "\n"); | |
1103 | return len; | |
1104 | } | |
1105 | ||
165125e1 JA |
1106 | struct request *elv_rb_former_request(struct request_queue *q, |
1107 | struct request *rq) | |
2e662b65 JA |
1108 | { |
1109 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1110 | ||
1111 | if (rbprev) | |
1112 | return rb_entry_rq(rbprev); | |
1113 | ||
1114 | return NULL; | |
1115 | } | |
2e662b65 JA |
1116 | EXPORT_SYMBOL(elv_rb_former_request); |
1117 | ||
165125e1 JA |
1118 | struct request *elv_rb_latter_request(struct request_queue *q, |
1119 | struct request *rq) | |
2e662b65 JA |
1120 | { |
1121 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1122 | ||
1123 | if (rbnext) | |
1124 | return rb_entry_rq(rbnext); | |
1125 | ||
1126 | return NULL; | |
1127 | } | |
2e662b65 | 1128 | EXPORT_SYMBOL(elv_rb_latter_request); |