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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) | |
4eb166d9 JA |
48 | #define ELV_HASH_FN(sec) \ |
49 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
50 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
51 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
52 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
53 | ||
da775265 JA |
54 | /* |
55 | * Query io scheduler to see if the current process issuing bio may be | |
56 | * merged with rq. | |
57 | */ | |
58 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
59 | { | |
165125e1 | 60 | struct request_queue *q = rq->q; |
da775265 JA |
61 | elevator_t *e = q->elevator; |
62 | ||
63 | if (e->ops->elevator_allow_merge_fn) | |
64 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
65 | ||
66 | return 1; | |
67 | } | |
68 | ||
1da177e4 LT |
69 | /* |
70 | * can we safely merge with this request? | |
71 | */ | |
72ed0bf6 | 72 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
73 | { |
74 | if (!rq_mergeable(rq)) | |
75 | return 0; | |
76 | ||
77 | /* | |
78 | * different data direction or already started, don't merge | |
79 | */ | |
80 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
81 | return 0; | |
82 | ||
83 | /* | |
da775265 | 84 | * must be same device and not a special request |
1da177e4 | 85 | */ |
bb4067e3 | 86 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
87 | return 0; |
88 | ||
7ba1ba12 MP |
89 | /* |
90 | * only merge integrity protected bio into ditto rq | |
91 | */ | |
92 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
93 | return 0; | |
94 | ||
da775265 JA |
95 | if (!elv_iosched_allow_merge(rq, bio)) |
96 | return 0; | |
1da177e4 | 97 | |
da775265 | 98 | return 1; |
1da177e4 LT |
99 | } |
100 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
101 | ||
769db45b | 102 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
103 | { |
104 | int ret = ELEVATOR_NO_MERGE; | |
105 | ||
106 | /* | |
107 | * we can merge and sequence is ok, check if it's possible | |
108 | */ | |
109 | if (elv_rq_merge_ok(__rq, bio)) { | |
110 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
111 | ret = ELEVATOR_BACK_MERGE; | |
112 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
113 | ret = ELEVATOR_FRONT_MERGE; | |
114 | } | |
115 | ||
116 | return ret; | |
117 | } | |
1da177e4 | 118 | |
1da177e4 LT |
119 | static struct elevator_type *elevator_find(const char *name) |
120 | { | |
a22b169d | 121 | struct elevator_type *e; |
1da177e4 | 122 | |
70cee26e | 123 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
124 | if (!strcmp(e->elevator_name, name)) |
125 | return e; | |
1da177e4 | 126 | } |
1da177e4 | 127 | |
a22b169d | 128 | return NULL; |
1da177e4 LT |
129 | } |
130 | ||
131 | static void elevator_put(struct elevator_type *e) | |
132 | { | |
133 | module_put(e->elevator_owner); | |
134 | } | |
135 | ||
136 | static struct elevator_type *elevator_get(const char *name) | |
137 | { | |
2824bc93 | 138 | struct elevator_type *e; |
1da177e4 | 139 | |
2a12dcd7 | 140 | spin_lock(&elv_list_lock); |
2824bc93 TH |
141 | |
142 | e = elevator_find(name); | |
e1640949 JA |
143 | if (!e) { |
144 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
145 | ||
146 | spin_unlock(&elv_list_lock); | |
147 | ||
148 | if (!strcmp(name, "anticipatory")) | |
149 | sprintf(elv, "as-iosched"); | |
150 | else | |
151 | sprintf(elv, "%s-iosched", name); | |
152 | ||
e180f594 | 153 | request_module("%s", elv); |
e1640949 JA |
154 | spin_lock(&elv_list_lock); |
155 | e = elevator_find(name); | |
156 | } | |
157 | ||
2824bc93 TH |
158 | if (e && !try_module_get(e->elevator_owner)) |
159 | e = NULL; | |
160 | ||
2a12dcd7 | 161 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
162 | |
163 | return e; | |
164 | } | |
165 | ||
165125e1 JA |
166 | static void *elevator_init_queue(struct request_queue *q, |
167 | struct elevator_queue *eq) | |
1da177e4 | 168 | { |
bb37b94c | 169 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 170 | } |
1da177e4 | 171 | |
165125e1 | 172 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
173 | void *data) |
174 | { | |
1da177e4 | 175 | q->elevator = eq; |
bc1c1169 | 176 | eq->elevator_data = data; |
1da177e4 LT |
177 | } |
178 | ||
179 | static char chosen_elevator[16]; | |
180 | ||
5f003976 | 181 | static int __init elevator_setup(char *str) |
1da177e4 | 182 | { |
752a3b79 CE |
183 | /* |
184 | * Be backwards-compatible with previous kernels, so users | |
185 | * won't get the wrong elevator. | |
186 | */ | |
5f003976 | 187 | if (!strcmp(str, "as")) |
752a3b79 | 188 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 189 | else |
5f003976 | 190 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 191 | return 1; |
1da177e4 LT |
192 | } |
193 | ||
194 | __setup("elevator=", elevator_setup); | |
195 | ||
3d1ab40f AV |
196 | static struct kobj_type elv_ktype; |
197 | ||
165125e1 JA |
198 | static elevator_t *elevator_alloc(struct request_queue *q, |
199 | struct elevator_type *e) | |
3d1ab40f | 200 | { |
9817064b JA |
201 | elevator_t *eq; |
202 | int i; | |
203 | ||
94f6030c | 204 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
205 | if (unlikely(!eq)) |
206 | goto err; | |
207 | ||
9817064b JA |
208 | eq->ops = &e->ops; |
209 | eq->elevator_type = e; | |
f9cb074b | 210 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
211 | mutex_init(&eq->sysfs_lock); |
212 | ||
b5deef90 JA |
213 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
214 | GFP_KERNEL, q->node); | |
9817064b JA |
215 | if (!eq->hash) |
216 | goto err; | |
217 | ||
218 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
219 | INIT_HLIST_HEAD(&eq->hash[i]); | |
220 | ||
3d1ab40f | 221 | return eq; |
9817064b JA |
222 | err: |
223 | kfree(eq); | |
224 | elevator_put(e); | |
225 | return NULL; | |
3d1ab40f AV |
226 | } |
227 | ||
228 | static void elevator_release(struct kobject *kobj) | |
229 | { | |
230 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 231 | |
3d1ab40f | 232 | elevator_put(e->elevator_type); |
9817064b | 233 | kfree(e->hash); |
3d1ab40f AV |
234 | kfree(e); |
235 | } | |
236 | ||
165125e1 | 237 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
238 | { |
239 | struct elevator_type *e = NULL; | |
240 | struct elevator_queue *eq; | |
241 | int ret = 0; | |
bc1c1169 | 242 | void *data; |
1da177e4 | 243 | |
cb98fc8b TH |
244 | INIT_LIST_HEAD(&q->queue_head); |
245 | q->last_merge = NULL; | |
246 | q->end_sector = 0; | |
247 | q->boundary_rq = NULL; | |
cb98fc8b | 248 | |
4eb166d9 JA |
249 | if (name) { |
250 | e = elevator_get(name); | |
251 | if (!e) | |
252 | return -EINVAL; | |
253 | } | |
1da177e4 | 254 | |
4eb166d9 JA |
255 | if (!e && *chosen_elevator) { |
256 | e = elevator_get(chosen_elevator); | |
257 | if (!e) | |
258 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
259 | chosen_elevator); | |
260 | } | |
248d5ca5 | 261 | |
4eb166d9 JA |
262 | if (!e) { |
263 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
264 | if (!e) { | |
265 | printk(KERN_ERR | |
266 | "Default I/O scheduler not found. " \ | |
267 | "Using noop.\n"); | |
268 | e = elevator_get("noop"); | |
269 | } | |
5f003976 ND |
270 | } |
271 | ||
b5deef90 | 272 | eq = elevator_alloc(q, e); |
3d1ab40f | 273 | if (!eq) |
1da177e4 | 274 | return -ENOMEM; |
1da177e4 | 275 | |
bc1c1169 JA |
276 | data = elevator_init_queue(q, eq); |
277 | if (!data) { | |
3d1ab40f | 278 | kobject_put(&eq->kobj); |
bc1c1169 JA |
279 | return -ENOMEM; |
280 | } | |
1da177e4 | 281 | |
bc1c1169 | 282 | elevator_attach(q, eq, data); |
1da177e4 LT |
283 | return ret; |
284 | } | |
2e662b65 JA |
285 | EXPORT_SYMBOL(elevator_init); |
286 | ||
1da177e4 LT |
287 | void elevator_exit(elevator_t *e) |
288 | { | |
3d1ab40f | 289 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
290 | if (e->ops->elevator_exit_fn) |
291 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
292 | e->ops = NULL; |
293 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 294 | |
3d1ab40f | 295 | kobject_put(&e->kobj); |
1da177e4 | 296 | } |
2e662b65 JA |
297 | EXPORT_SYMBOL(elevator_exit); |
298 | ||
165125e1 | 299 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
300 | { |
301 | elevator_t *e = q->elevator; | |
302 | ||
303 | if (e->ops->elevator_activate_req_fn) | |
304 | e->ops->elevator_activate_req_fn(q, rq); | |
305 | } | |
306 | ||
165125e1 | 307 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
308 | { |
309 | elevator_t *e = q->elevator; | |
310 | ||
311 | if (e->ops->elevator_deactivate_req_fn) | |
312 | e->ops->elevator_deactivate_req_fn(q, rq); | |
313 | } | |
314 | ||
9817064b JA |
315 | static inline void __elv_rqhash_del(struct request *rq) |
316 | { | |
317 | hlist_del_init(&rq->hash); | |
318 | } | |
319 | ||
165125e1 | 320 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
321 | { |
322 | if (ELV_ON_HASH(rq)) | |
323 | __elv_rqhash_del(rq); | |
324 | } | |
325 | ||
165125e1 | 326 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b JA |
327 | { |
328 | elevator_t *e = q->elevator; | |
329 | ||
330 | BUG_ON(ELV_ON_HASH(rq)); | |
331 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
332 | } | |
333 | ||
165125e1 | 334 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
335 | { |
336 | __elv_rqhash_del(rq); | |
337 | elv_rqhash_add(q, rq); | |
338 | } | |
339 | ||
165125e1 | 340 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b JA |
341 | { |
342 | elevator_t *e = q->elevator; | |
343 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
344 | struct hlist_node *entry, *next; | |
345 | struct request *rq; | |
346 | ||
347 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
348 | BUG_ON(!ELV_ON_HASH(rq)); | |
349 | ||
350 | if (unlikely(!rq_mergeable(rq))) { | |
351 | __elv_rqhash_del(rq); | |
352 | continue; | |
353 | } | |
354 | ||
355 | if (rq_hash_key(rq) == offset) | |
356 | return rq; | |
357 | } | |
358 | ||
359 | return NULL; | |
360 | } | |
361 | ||
2e662b65 JA |
362 | /* |
363 | * RB-tree support functions for inserting/lookup/removal of requests | |
364 | * in a sorted RB tree. | |
365 | */ | |
366 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
367 | { | |
368 | struct rb_node **p = &root->rb_node; | |
369 | struct rb_node *parent = NULL; | |
370 | struct request *__rq; | |
371 | ||
372 | while (*p) { | |
373 | parent = *p; | |
374 | __rq = rb_entry(parent, struct request, rb_node); | |
375 | ||
376 | if (rq->sector < __rq->sector) | |
377 | p = &(*p)->rb_left; | |
378 | else if (rq->sector > __rq->sector) | |
379 | p = &(*p)->rb_right; | |
380 | else | |
381 | return __rq; | |
382 | } | |
383 | ||
384 | rb_link_node(&rq->rb_node, parent, p); | |
385 | rb_insert_color(&rq->rb_node, root); | |
386 | return NULL; | |
387 | } | |
2e662b65 JA |
388 | EXPORT_SYMBOL(elv_rb_add); |
389 | ||
390 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
391 | { | |
392 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
393 | rb_erase(&rq->rb_node, root); | |
394 | RB_CLEAR_NODE(&rq->rb_node); | |
395 | } | |
2e662b65 JA |
396 | EXPORT_SYMBOL(elv_rb_del); |
397 | ||
398 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
399 | { | |
400 | struct rb_node *n = root->rb_node; | |
401 | struct request *rq; | |
402 | ||
403 | while (n) { | |
404 | rq = rb_entry(n, struct request, rb_node); | |
405 | ||
406 | if (sector < rq->sector) | |
407 | n = n->rb_left; | |
408 | else if (sector > rq->sector) | |
409 | n = n->rb_right; | |
410 | else | |
411 | return rq; | |
412 | } | |
413 | ||
414 | return NULL; | |
415 | } | |
2e662b65 JA |
416 | EXPORT_SYMBOL(elv_rb_find); |
417 | ||
8922e16c TH |
418 | /* |
419 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 420 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 421 | * specific elevators. |
8922e16c | 422 | */ |
165125e1 | 423 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
424 | { |
425 | sector_t boundary; | |
8922e16c | 426 | struct list_head *entry; |
4eb166d9 | 427 | int stop_flags; |
8922e16c | 428 | |
06b86245 TH |
429 | if (q->last_merge == rq) |
430 | q->last_merge = NULL; | |
9817064b JA |
431 | |
432 | elv_rqhash_del(q, rq); | |
433 | ||
15853af9 | 434 | q->nr_sorted--; |
06b86245 | 435 | |
1b47f531 | 436 | boundary = q->end_sector; |
4eb166d9 | 437 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
438 | list_for_each_prev(entry, &q->queue_head) { |
439 | struct request *pos = list_entry_rq(entry); | |
440 | ||
783660b2 JA |
441 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
442 | break; | |
4eb166d9 | 443 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
444 | break; |
445 | if (rq->sector >= boundary) { | |
446 | if (pos->sector < boundary) | |
447 | continue; | |
448 | } else { | |
449 | if (pos->sector >= boundary) | |
450 | break; | |
451 | } | |
452 | if (rq->sector >= pos->sector) | |
453 | break; | |
454 | } | |
455 | ||
456 | list_add(&rq->queuelist, entry); | |
457 | } | |
2e662b65 JA |
458 | EXPORT_SYMBOL(elv_dispatch_sort); |
459 | ||
9817064b | 460 | /* |
2e662b65 JA |
461 | * Insert rq into dispatch queue of q. Queue lock must be held on |
462 | * entry. rq is added to the back of the dispatch queue. To be used by | |
463 | * specific elevators. | |
9817064b JA |
464 | */ |
465 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
466 | { | |
467 | if (q->last_merge == rq) | |
468 | q->last_merge = NULL; | |
469 | ||
470 | elv_rqhash_del(q, rq); | |
471 | ||
472 | q->nr_sorted--; | |
473 | ||
474 | q->end_sector = rq_end_sector(rq); | |
475 | q->boundary_rq = rq; | |
476 | list_add_tail(&rq->queuelist, &q->queue_head); | |
477 | } | |
2e662b65 JA |
478 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
479 | ||
165125e1 | 480 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 LT |
481 | { |
482 | elevator_t *e = q->elevator; | |
9817064b | 483 | struct request *__rq; |
06b86245 TH |
484 | int ret; |
485 | ||
9817064b JA |
486 | /* |
487 | * First try one-hit cache. | |
488 | */ | |
06b86245 TH |
489 | if (q->last_merge) { |
490 | ret = elv_try_merge(q->last_merge, bio); | |
491 | if (ret != ELEVATOR_NO_MERGE) { | |
492 | *req = q->last_merge; | |
493 | return ret; | |
494 | } | |
495 | } | |
1da177e4 | 496 | |
ac9fafa1 AB |
497 | if (blk_queue_nomerges(q)) |
498 | return ELEVATOR_NO_MERGE; | |
499 | ||
9817064b JA |
500 | /* |
501 | * See if our hash lookup can find a potential backmerge. | |
502 | */ | |
503 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
504 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
505 | *req = __rq; | |
506 | return ELEVATOR_BACK_MERGE; | |
507 | } | |
508 | ||
1da177e4 LT |
509 | if (e->ops->elevator_merge_fn) |
510 | return e->ops->elevator_merge_fn(q, req, bio); | |
511 | ||
512 | return ELEVATOR_NO_MERGE; | |
513 | } | |
514 | ||
165125e1 | 515 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 LT |
516 | { |
517 | elevator_t *e = q->elevator; | |
518 | ||
519 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 520 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 521 | |
2e662b65 JA |
522 | if (type == ELEVATOR_BACK_MERGE) |
523 | elv_rqhash_reposition(q, rq); | |
9817064b | 524 | |
06b86245 | 525 | q->last_merge = rq; |
1da177e4 LT |
526 | } |
527 | ||
165125e1 | 528 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
529 | struct request *next) |
530 | { | |
531 | elevator_t *e = q->elevator; | |
532 | ||
1da177e4 LT |
533 | if (e->ops->elevator_merge_req_fn) |
534 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 535 | |
9817064b JA |
536 | elv_rqhash_reposition(q, rq); |
537 | elv_rqhash_del(q, next); | |
538 | ||
539 | q->nr_sorted--; | |
06b86245 | 540 | q->last_merge = rq; |
1da177e4 LT |
541 | } |
542 | ||
165125e1 | 543 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 544 | { |
1da177e4 LT |
545 | /* |
546 | * it already went through dequeue, we need to decrement the | |
547 | * in_flight count again | |
548 | */ | |
8922e16c | 549 | if (blk_account_rq(rq)) { |
1da177e4 | 550 | q->in_flight--; |
cad97516 JA |
551 | if (blk_sorted_rq(rq)) |
552 | elv_deactivate_rq(q, rq); | |
8922e16c | 553 | } |
1da177e4 | 554 | |
4aff5e23 | 555 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 556 | |
30e9656c | 557 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
558 | } |
559 | ||
165125e1 | 560 | static void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
561 | { |
562 | static int printed; | |
563 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
564 | ; | |
565 | if (q->nr_sorted == 0) | |
566 | return; | |
567 | if (printed++ < 10) { | |
568 | printk(KERN_ERR "%s: forced dispatching is broken " | |
569 | "(nr_sorted=%u), please report this\n", | |
570 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
571 | } | |
572 | } | |
573 | ||
165125e1 | 574 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 575 | { |
797e7dbb TH |
576 | struct list_head *pos; |
577 | unsigned ordseq; | |
dac07ec1 | 578 | int unplug_it = 1; |
797e7dbb | 579 | |
2056a782 JA |
580 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
581 | ||
1da177e4 LT |
582 | rq->q = q; |
583 | ||
8922e16c TH |
584 | switch (where) { |
585 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 586 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
587 | |
588 | list_add(&rq->queuelist, &q->queue_head); | |
589 | break; | |
590 | ||
591 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 592 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 593 | elv_drain_elevator(q); |
8922e16c TH |
594 | list_add_tail(&rq->queuelist, &q->queue_head); |
595 | /* | |
596 | * We kick the queue here for the following reasons. | |
597 | * - The elevator might have returned NULL previously | |
598 | * to delay requests and returned them now. As the | |
599 | * queue wasn't empty before this request, ll_rw_blk | |
600 | * won't run the queue on return, resulting in hang. | |
601 | * - Usually, back inserted requests won't be merged | |
602 | * with anything. There's no point in delaying queue | |
603 | * processing. | |
604 | */ | |
605 | blk_remove_plug(q); | |
606 | q->request_fn(q); | |
607 | break; | |
608 | ||
609 | case ELEVATOR_INSERT_SORT: | |
610 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 611 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 612 | q->nr_sorted++; |
9817064b JA |
613 | if (rq_mergeable(rq)) { |
614 | elv_rqhash_add(q, rq); | |
615 | if (!q->last_merge) | |
616 | q->last_merge = rq; | |
617 | } | |
618 | ||
ca23509f TH |
619 | /* |
620 | * Some ioscheds (cfq) run q->request_fn directly, so | |
621 | * rq cannot be accessed after calling | |
622 | * elevator_add_req_fn. | |
623 | */ | |
624 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
625 | break; |
626 | ||
797e7dbb TH |
627 | case ELEVATOR_INSERT_REQUEUE: |
628 | /* | |
629 | * If ordered flush isn't in progress, we do front | |
630 | * insertion; otherwise, requests should be requeued | |
631 | * in ordseq order. | |
632 | */ | |
4aff5e23 | 633 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 634 | |
95543179 LV |
635 | /* |
636 | * Most requeues happen because of a busy condition, | |
637 | * don't force unplug of the queue for that case. | |
638 | */ | |
639 | unplug_it = 0; | |
640 | ||
797e7dbb TH |
641 | if (q->ordseq == 0) { |
642 | list_add(&rq->queuelist, &q->queue_head); | |
643 | break; | |
644 | } | |
645 | ||
646 | ordseq = blk_ordered_req_seq(rq); | |
647 | ||
648 | list_for_each(pos, &q->queue_head) { | |
649 | struct request *pos_rq = list_entry_rq(pos); | |
650 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
651 | break; | |
652 | } | |
653 | ||
654 | list_add_tail(&rq->queuelist, pos); | |
655 | break; | |
656 | ||
8922e16c TH |
657 | default: |
658 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 659 | __func__, where); |
8922e16c TH |
660 | BUG(); |
661 | } | |
662 | ||
dac07ec1 | 663 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
664 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
665 | - q->in_flight; | |
666 | ||
667 | if (nrq >= q->unplug_thresh) | |
668 | __generic_unplug_device(q); | |
669 | } | |
1da177e4 LT |
670 | } |
671 | ||
165125e1 | 672 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
673 | int plug) |
674 | { | |
675 | if (q->ordcolor) | |
4aff5e23 | 676 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 677 | |
4aff5e23 | 678 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
679 | /* |
680 | * toggle ordered color | |
681 | */ | |
682 | if (blk_barrier_rq(rq)) | |
683 | q->ordcolor ^= 1; | |
684 | ||
685 | /* | |
686 | * barriers implicitly indicate back insertion | |
687 | */ | |
688 | if (where == ELEVATOR_INSERT_SORT) | |
689 | where = ELEVATOR_INSERT_BACK; | |
690 | ||
691 | /* | |
692 | * this request is scheduling boundary, update | |
693 | * end_sector | |
694 | */ | |
695 | if (blk_fs_request(rq)) { | |
696 | q->end_sector = rq_end_sector(rq); | |
697 | q->boundary_rq = rq; | |
698 | } | |
4eb166d9 JA |
699 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
700 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
701 | where = ELEVATOR_INSERT_BACK; |
702 | ||
703 | if (plug) | |
704 | blk_plug_device(q); | |
705 | ||
706 | elv_insert(q, rq, where); | |
707 | } | |
2e662b65 JA |
708 | EXPORT_SYMBOL(__elv_add_request); |
709 | ||
165125e1 | 710 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
711 | int plug) |
712 | { | |
713 | unsigned long flags; | |
714 | ||
715 | spin_lock_irqsave(q->queue_lock, flags); | |
716 | __elv_add_request(q, rq, where, plug); | |
717 | spin_unlock_irqrestore(q->queue_lock, flags); | |
718 | } | |
2e662b65 JA |
719 | EXPORT_SYMBOL(elv_add_request); |
720 | ||
165125e1 | 721 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 722 | { |
8922e16c TH |
723 | struct request *rq; |
724 | ||
797e7dbb TH |
725 | while (1) { |
726 | while (!list_empty(&q->queue_head)) { | |
727 | rq = list_entry_rq(q->queue_head.next); | |
728 | if (blk_do_ordered(q, &rq)) | |
729 | return rq; | |
730 | } | |
1da177e4 | 731 | |
797e7dbb TH |
732 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
733 | return NULL; | |
1da177e4 | 734 | } |
1da177e4 LT |
735 | } |
736 | ||
165125e1 | 737 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
738 | { |
739 | struct request *rq; | |
740 | int ret; | |
741 | ||
742 | while ((rq = __elv_next_request(q)) != NULL) { | |
bf2de6f5 JA |
743 | /* |
744 | * Kill the empty barrier place holder, the driver must | |
745 | * not ever see it. | |
746 | */ | |
747 | if (blk_empty_barrier(rq)) { | |
748 | end_queued_request(rq, 1); | |
749 | continue; | |
750 | } | |
4aff5e23 | 751 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
752 | /* |
753 | * This is the first time the device driver | |
754 | * sees this request (possibly after | |
755 | * requeueing). Notify IO scheduler. | |
756 | */ | |
cad97516 JA |
757 | if (blk_sorted_rq(rq)) |
758 | elv_activate_rq(q, rq); | |
1da177e4 | 759 | |
8922e16c TH |
760 | /* |
761 | * just mark as started even if we don't start | |
762 | * it, a request that has been delayed should | |
763 | * not be passed by new incoming requests | |
764 | */ | |
4aff5e23 | 765 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 766 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 767 | } |
1da177e4 | 768 | |
8922e16c | 769 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 770 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
771 | q->boundary_rq = NULL; |
772 | } | |
1da177e4 | 773 | |
fa0ccd83 JB |
774 | if (rq->cmd_flags & REQ_DONTPREP) |
775 | break; | |
776 | ||
777 | if (q->dma_drain_size && rq->data_len) { | |
778 | /* | |
779 | * make sure space for the drain appears we | |
780 | * know we can do this because max_hw_segments | |
781 | * has been adjusted to be one fewer than the | |
782 | * device can handle | |
783 | */ | |
784 | rq->nr_phys_segments++; | |
785 | rq->nr_hw_segments++; | |
786 | } | |
787 | ||
788 | if (!q->prep_rq_fn) | |
1da177e4 LT |
789 | break; |
790 | ||
791 | ret = q->prep_rq_fn(q, rq); | |
792 | if (ret == BLKPREP_OK) { | |
793 | break; | |
794 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
795 | /* |
796 | * the request may have been (partially) prepped. | |
797 | * we need to keep this request in the front to | |
8922e16c TH |
798 | * avoid resource deadlock. REQ_STARTED will |
799 | * prevent other fs requests from passing this one. | |
2e759cd4 | 800 | */ |
fa0ccd83 JB |
801 | if (q->dma_drain_size && rq->data_len && |
802 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
803 | /* | |
804 | * remove the space for the drain we added | |
805 | * so that we don't add it again | |
806 | */ | |
807 | --rq->nr_phys_segments; | |
808 | --rq->nr_hw_segments; | |
809 | } | |
810 | ||
1da177e4 LT |
811 | rq = NULL; |
812 | break; | |
813 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 814 | rq->cmd_flags |= REQ_QUIET; |
a0cd1285 | 815 | end_queued_request(rq, 0); |
1da177e4 | 816 | } else { |
24c03d47 | 817 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1da177e4 LT |
818 | break; |
819 | } | |
820 | } | |
821 | ||
822 | return rq; | |
823 | } | |
2e662b65 JA |
824 | EXPORT_SYMBOL(elv_next_request); |
825 | ||
165125e1 | 826 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 827 | { |
8922e16c | 828 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 829 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
830 | |
831 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
832 | |
833 | /* | |
834 | * the time frame between a request being removed from the lists | |
835 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 836 | * the driver side. |
1da177e4 LT |
837 | */ |
838 | if (blk_account_rq(rq)) | |
839 | q->in_flight++; | |
1da177e4 | 840 | } |
2e662b65 JA |
841 | EXPORT_SYMBOL(elv_dequeue_request); |
842 | ||
165125e1 | 843 | int elv_queue_empty(struct request_queue *q) |
1da177e4 LT |
844 | { |
845 | elevator_t *e = q->elevator; | |
846 | ||
8922e16c TH |
847 | if (!list_empty(&q->queue_head)) |
848 | return 0; | |
849 | ||
1da177e4 LT |
850 | if (e->ops->elevator_queue_empty_fn) |
851 | return e->ops->elevator_queue_empty_fn(q); | |
852 | ||
8922e16c | 853 | return 1; |
1da177e4 | 854 | } |
2e662b65 JA |
855 | EXPORT_SYMBOL(elv_queue_empty); |
856 | ||
165125e1 | 857 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 858 | { |
1da177e4 LT |
859 | elevator_t *e = q->elevator; |
860 | ||
861 | if (e->ops->elevator_latter_req_fn) | |
862 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
863 | return NULL; |
864 | } | |
865 | ||
165125e1 | 866 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 867 | { |
1da177e4 LT |
868 | elevator_t *e = q->elevator; |
869 | ||
870 | if (e->ops->elevator_former_req_fn) | |
871 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
872 | return NULL; |
873 | } | |
874 | ||
165125e1 | 875 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
876 | { |
877 | elevator_t *e = q->elevator; | |
878 | ||
879 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 880 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
881 | |
882 | rq->elevator_private = NULL; | |
883 | return 0; | |
884 | } | |
885 | ||
165125e1 | 886 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
887 | { |
888 | elevator_t *e = q->elevator; | |
889 | ||
890 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 891 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
892 | } |
893 | ||
165125e1 | 894 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 LT |
895 | { |
896 | elevator_t *e = q->elevator; | |
897 | ||
898 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 899 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
900 | |
901 | return ELV_MQUEUE_MAY; | |
902 | } | |
903 | ||
165125e1 | 904 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
905 | { |
906 | elevator_t *e = q->elevator; | |
907 | ||
908 | /* | |
909 | * request is released from the driver, io must be done | |
910 | */ | |
8922e16c | 911 | if (blk_account_rq(rq)) { |
1da177e4 | 912 | q->in_flight--; |
1bc691d3 TH |
913 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
914 | e->ops->elevator_completed_req_fn(q, rq); | |
915 | } | |
797e7dbb | 916 | |
1bc691d3 TH |
917 | /* |
918 | * Check if the queue is waiting for fs requests to be | |
919 | * drained for flush sequence. | |
920 | */ | |
921 | if (unlikely(q->ordseq)) { | |
922 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
923 | if (q->in_flight == 0 && | |
797e7dbb TH |
924 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
925 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
926 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
927 | q->request_fn(q); | |
928 | } | |
8922e16c | 929 | } |
1da177e4 LT |
930 | } |
931 | ||
3d1ab40f AV |
932 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
933 | ||
934 | static ssize_t | |
935 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 936 | { |
3d1ab40f AV |
937 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
938 | struct elv_fs_entry *entry = to_elv(attr); | |
939 | ssize_t error; | |
940 | ||
941 | if (!entry->show) | |
942 | return -EIO; | |
943 | ||
944 | mutex_lock(&e->sysfs_lock); | |
945 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
946 | mutex_unlock(&e->sysfs_lock); | |
947 | return error; | |
948 | } | |
1da177e4 | 949 | |
3d1ab40f AV |
950 | static ssize_t |
951 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
952 | const char *page, size_t length) | |
953 | { | |
954 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
955 | struct elv_fs_entry *entry = to_elv(attr); | |
956 | ssize_t error; | |
1da177e4 | 957 | |
3d1ab40f AV |
958 | if (!entry->store) |
959 | return -EIO; | |
1da177e4 | 960 | |
3d1ab40f AV |
961 | mutex_lock(&e->sysfs_lock); |
962 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
963 | mutex_unlock(&e->sysfs_lock); | |
964 | return error; | |
965 | } | |
966 | ||
967 | static struct sysfs_ops elv_sysfs_ops = { | |
968 | .show = elv_attr_show, | |
969 | .store = elv_attr_store, | |
970 | }; | |
971 | ||
972 | static struct kobj_type elv_ktype = { | |
973 | .sysfs_ops = &elv_sysfs_ops, | |
974 | .release = elevator_release, | |
975 | }; | |
976 | ||
977 | int elv_register_queue(struct request_queue *q) | |
978 | { | |
979 | elevator_t *e = q->elevator; | |
980 | int error; | |
981 | ||
b2d6db58 | 982 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 983 | if (!error) { |
e572ec7e | 984 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 985 | if (attr) { |
e572ec7e AV |
986 | while (attr->attr.name) { |
987 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 988 | break; |
e572ec7e | 989 | attr++; |
3d1ab40f AV |
990 | } |
991 | } | |
992 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
993 | } | |
994 | return error; | |
1da177e4 LT |
995 | } |
996 | ||
bc1c1169 JA |
997 | static void __elv_unregister_queue(elevator_t *e) |
998 | { | |
999 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
1000 | kobject_del(&e->kobj); | |
1001 | } | |
1002 | ||
1da177e4 LT |
1003 | void elv_unregister_queue(struct request_queue *q) |
1004 | { | |
bc1c1169 JA |
1005 | if (q) |
1006 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
1007 | } |
1008 | ||
2fdd82bd | 1009 | void elv_register(struct elevator_type *e) |
1da177e4 | 1010 | { |
1ffb96c5 | 1011 | char *def = ""; |
2a12dcd7 JA |
1012 | |
1013 | spin_lock(&elv_list_lock); | |
ce524497 | 1014 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 1015 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 1016 | spin_unlock(&elv_list_lock); |
1da177e4 | 1017 | |
5f003976 ND |
1018 | if (!strcmp(e->elevator_name, chosen_elevator) || |
1019 | (!*chosen_elevator && | |
1020 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
1021 | def = " (default)"; |
1022 | ||
4eb166d9 JA |
1023 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1024 | def); | |
1da177e4 LT |
1025 | } |
1026 | EXPORT_SYMBOL_GPL(elv_register); | |
1027 | ||
1028 | void elv_unregister(struct elevator_type *e) | |
1029 | { | |
83521d3e CH |
1030 | struct task_struct *g, *p; |
1031 | ||
1032 | /* | |
1033 | * Iterate every thread in the process to remove the io contexts. | |
1034 | */ | |
e17a9489 AV |
1035 | if (e->ops.trim) { |
1036 | read_lock(&tasklist_lock); | |
1037 | do_each_thread(g, p) { | |
1038 | task_lock(p); | |
2d8f6131 ON |
1039 | if (p->io_context) |
1040 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1041 | task_unlock(p); |
1042 | } while_each_thread(g, p); | |
1043 | read_unlock(&tasklist_lock); | |
1044 | } | |
83521d3e | 1045 | |
2a12dcd7 | 1046 | spin_lock(&elv_list_lock); |
1da177e4 | 1047 | list_del_init(&e->list); |
2a12dcd7 | 1048 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1049 | } |
1050 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1051 | ||
1052 | /* | |
1053 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1054 | * we don't free the old io scheduler, before we have allocated what we | |
1055 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1056 | * one, if the new one fails init for some reason. |
1da177e4 | 1057 | */ |
165125e1 | 1058 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1059 | { |
cb98fc8b | 1060 | elevator_t *old_elevator, *e; |
bc1c1169 | 1061 | void *data; |
1da177e4 | 1062 | |
cb98fc8b TH |
1063 | /* |
1064 | * Allocate new elevator | |
1065 | */ | |
b5deef90 | 1066 | e = elevator_alloc(q, new_e); |
1da177e4 | 1067 | if (!e) |
3d1ab40f | 1068 | return 0; |
1da177e4 | 1069 | |
bc1c1169 JA |
1070 | data = elevator_init_queue(q, e); |
1071 | if (!data) { | |
1072 | kobject_put(&e->kobj); | |
1073 | return 0; | |
1074 | } | |
1075 | ||
1da177e4 | 1076 | /* |
cb98fc8b | 1077 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1078 | */ |
cb98fc8b TH |
1079 | spin_lock_irq(q->queue_lock); |
1080 | ||
75ad23bc | 1081 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
cb98fc8b | 1082 | |
15853af9 | 1083 | elv_drain_elevator(q); |
cb98fc8b TH |
1084 | |
1085 | while (q->rq.elvpriv) { | |
407df2aa TH |
1086 | blk_remove_plug(q); |
1087 | q->request_fn(q); | |
cb98fc8b | 1088 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1089 | msleep(10); |
cb98fc8b | 1090 | spin_lock_irq(q->queue_lock); |
15853af9 | 1091 | elv_drain_elevator(q); |
cb98fc8b TH |
1092 | } |
1093 | ||
1da177e4 | 1094 | /* |
bc1c1169 | 1095 | * Remember old elevator. |
1da177e4 | 1096 | */ |
1da177e4 LT |
1097 | old_elevator = q->elevator; |
1098 | ||
1da177e4 LT |
1099 | /* |
1100 | * attach and start new elevator | |
1101 | */ | |
bc1c1169 JA |
1102 | elevator_attach(q, e, data); |
1103 | ||
1104 | spin_unlock_irq(q->queue_lock); | |
1105 | ||
1106 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1107 | |
1108 | if (elv_register_queue(q)) | |
1109 | goto fail_register; | |
1110 | ||
1111 | /* | |
cb98fc8b | 1112 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1113 | */ |
1114 | elevator_exit(old_elevator); | |
75ad23bc NP |
1115 | spin_lock_irq(q->queue_lock); |
1116 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1117 | spin_unlock_irq(q->queue_lock); | |
1118 | ||
4722dc52 AB |
1119 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1120 | ||
3d1ab40f | 1121 | return 1; |
1da177e4 LT |
1122 | |
1123 | fail_register: | |
1124 | /* | |
1125 | * switch failed, exit the new io scheduler and reattach the old | |
1126 | * one again (along with re-adding the sysfs dir) | |
1127 | */ | |
1128 | elevator_exit(e); | |
1da177e4 LT |
1129 | q->elevator = old_elevator; |
1130 | elv_register_queue(q); | |
75ad23bc NP |
1131 | |
1132 | spin_lock_irq(q->queue_lock); | |
1133 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1134 | spin_unlock_irq(q->queue_lock); | |
1135 | ||
3d1ab40f | 1136 | return 0; |
1da177e4 LT |
1137 | } |
1138 | ||
165125e1 JA |
1139 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1140 | size_t count) | |
1da177e4 LT |
1141 | { |
1142 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1143 | size_t len; |
1da177e4 LT |
1144 | struct elevator_type *e; |
1145 | ||
be561235 TH |
1146 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1147 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1148 | len = strlen(elevator_name); | |
1da177e4 | 1149 | |
be561235 TH |
1150 | if (len && elevator_name[len - 1] == '\n') |
1151 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1152 | |
1153 | e = elevator_get(elevator_name); | |
1154 | if (!e) { | |
1155 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1156 | return -EINVAL; | |
1157 | } | |
1158 | ||
2ca7d93b ND |
1159 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1160 | elevator_put(e); | |
1da177e4 | 1161 | return count; |
2ca7d93b | 1162 | } |
1da177e4 | 1163 | |
3d1ab40f | 1164 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1165 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1166 | elevator_name); | |
1da177e4 LT |
1167 | return count; |
1168 | } | |
1169 | ||
165125e1 | 1170 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 LT |
1171 | { |
1172 | elevator_t *e = q->elevator; | |
1173 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1174 | struct elevator_type *__e; |
1da177e4 LT |
1175 | int len = 0; |
1176 | ||
2a12dcd7 | 1177 | spin_lock(&elv_list_lock); |
70cee26e | 1178 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1179 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1180 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1181 | else | |
1182 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1183 | } | |
2a12dcd7 | 1184 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1185 | |
1186 | len += sprintf(len+name, "\n"); | |
1187 | return len; | |
1188 | } | |
1189 | ||
165125e1 JA |
1190 | struct request *elv_rb_former_request(struct request_queue *q, |
1191 | struct request *rq) | |
2e662b65 JA |
1192 | { |
1193 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1194 | ||
1195 | if (rbprev) | |
1196 | return rb_entry_rq(rbprev); | |
1197 | ||
1198 | return NULL; | |
1199 | } | |
2e662b65 JA |
1200 | EXPORT_SYMBOL(elv_rb_former_request); |
1201 | ||
165125e1 JA |
1202 | struct request *elv_rb_latter_request(struct request_queue *q, |
1203 | struct request *rq) | |
2e662b65 JA |
1204 | { |
1205 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1206 | ||
1207 | if (rbnext) | |
1208 | return rb_entry_rq(rbnext); | |
1209 | ||
1210 | return NULL; | |
1211 | } | |
2e662b65 | 1212 | EXPORT_SYMBOL(elv_rb_latter_request); |