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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> |
0835da67 | 37 | #include <linux/uaccess.h> |
1da177e4 LT |
38 | |
39 | static DEFINE_SPINLOCK(elv_list_lock); | |
40 | static LIST_HEAD(elv_list); | |
41 | ||
9817064b JA |
42 | /* |
43 | * Merge hash stuff. | |
44 | */ | |
45 | static const int elv_hash_shift = 6; | |
46 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
47 | #define ELV_HASH_FN(sec) \ |
48 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
49 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
50 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
51 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
52 | ||
da775265 JA |
53 | /* |
54 | * Query io scheduler to see if the current process issuing bio may be | |
55 | * merged with rq. | |
56 | */ | |
57 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
58 | { | |
165125e1 | 59 | struct request_queue *q = rq->q; |
da775265 JA |
60 | elevator_t *e = q->elevator; |
61 | ||
62 | if (e->ops->elevator_allow_merge_fn) | |
63 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
64 | ||
65 | return 1; | |
66 | } | |
67 | ||
1da177e4 LT |
68 | /* |
69 | * can we safely merge with this request? | |
70 | */ | |
72ed0bf6 | 71 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
72 | { |
73 | if (!rq_mergeable(rq)) | |
74 | return 0; | |
75 | ||
e17fc0a1 DW |
76 | /* |
77 | * Don't merge file system requests and discard requests | |
78 | */ | |
79 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
80 | return 0; | |
81 | ||
1da177e4 LT |
82 | /* |
83 | * different data direction or already started, don't merge | |
84 | */ | |
85 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
86 | return 0; | |
87 | ||
88 | /* | |
da775265 | 89 | * must be same device and not a special request |
1da177e4 | 90 | */ |
bb4067e3 | 91 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
92 | return 0; |
93 | ||
7ba1ba12 MP |
94 | /* |
95 | * only merge integrity protected bio into ditto rq | |
96 | */ | |
97 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
98 | return 0; | |
99 | ||
da775265 JA |
100 | if (!elv_iosched_allow_merge(rq, bio)) |
101 | return 0; | |
1da177e4 | 102 | |
da775265 | 103 | return 1; |
1da177e4 LT |
104 | } |
105 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
106 | ||
769db45b | 107 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
108 | { |
109 | int ret = ELEVATOR_NO_MERGE; | |
110 | ||
111 | /* | |
112 | * we can merge and sequence is ok, check if it's possible | |
113 | */ | |
114 | if (elv_rq_merge_ok(__rq, bio)) { | |
115 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
116 | ret = ELEVATOR_BACK_MERGE; | |
117 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
118 | ret = ELEVATOR_FRONT_MERGE; | |
119 | } | |
120 | ||
121 | return ret; | |
122 | } | |
1da177e4 | 123 | |
1da177e4 LT |
124 | static struct elevator_type *elevator_find(const char *name) |
125 | { | |
a22b169d | 126 | struct elevator_type *e; |
1da177e4 | 127 | |
70cee26e | 128 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
129 | if (!strcmp(e->elevator_name, name)) |
130 | return e; | |
1da177e4 | 131 | } |
1da177e4 | 132 | |
a22b169d | 133 | return NULL; |
1da177e4 LT |
134 | } |
135 | ||
136 | static void elevator_put(struct elevator_type *e) | |
137 | { | |
138 | module_put(e->elevator_owner); | |
139 | } | |
140 | ||
141 | static struct elevator_type *elevator_get(const char *name) | |
142 | { | |
2824bc93 | 143 | struct elevator_type *e; |
1da177e4 | 144 | |
2a12dcd7 | 145 | spin_lock(&elv_list_lock); |
2824bc93 TH |
146 | |
147 | e = elevator_find(name); | |
e1640949 JA |
148 | if (!e) { |
149 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
150 | ||
151 | spin_unlock(&elv_list_lock); | |
152 | ||
153 | if (!strcmp(name, "anticipatory")) | |
154 | sprintf(elv, "as-iosched"); | |
155 | else | |
156 | sprintf(elv, "%s-iosched", name); | |
157 | ||
e180f594 | 158 | request_module("%s", elv); |
e1640949 JA |
159 | spin_lock(&elv_list_lock); |
160 | e = elevator_find(name); | |
161 | } | |
162 | ||
2824bc93 TH |
163 | if (e && !try_module_get(e->elevator_owner)) |
164 | e = NULL; | |
165 | ||
2a12dcd7 | 166 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
167 | |
168 | return e; | |
169 | } | |
170 | ||
165125e1 JA |
171 | static void *elevator_init_queue(struct request_queue *q, |
172 | struct elevator_queue *eq) | |
1da177e4 | 173 | { |
bb37b94c | 174 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 175 | } |
1da177e4 | 176 | |
165125e1 | 177 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
178 | void *data) |
179 | { | |
1da177e4 | 180 | q->elevator = eq; |
bc1c1169 | 181 | eq->elevator_data = data; |
1da177e4 LT |
182 | } |
183 | ||
184 | static char chosen_elevator[16]; | |
185 | ||
5f003976 | 186 | static int __init elevator_setup(char *str) |
1da177e4 | 187 | { |
752a3b79 CE |
188 | /* |
189 | * Be backwards-compatible with previous kernels, so users | |
190 | * won't get the wrong elevator. | |
191 | */ | |
5f003976 | 192 | if (!strcmp(str, "as")) |
752a3b79 | 193 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 194 | else |
5f003976 | 195 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 196 | return 1; |
1da177e4 LT |
197 | } |
198 | ||
199 | __setup("elevator=", elevator_setup); | |
200 | ||
3d1ab40f AV |
201 | static struct kobj_type elv_ktype; |
202 | ||
165125e1 JA |
203 | static elevator_t *elevator_alloc(struct request_queue *q, |
204 | struct elevator_type *e) | |
3d1ab40f | 205 | { |
9817064b JA |
206 | elevator_t *eq; |
207 | int i; | |
208 | ||
94f6030c | 209 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
210 | if (unlikely(!eq)) |
211 | goto err; | |
212 | ||
9817064b JA |
213 | eq->ops = &e->ops; |
214 | eq->elevator_type = e; | |
f9cb074b | 215 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
216 | mutex_init(&eq->sysfs_lock); |
217 | ||
b5deef90 JA |
218 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
219 | GFP_KERNEL, q->node); | |
9817064b JA |
220 | if (!eq->hash) |
221 | goto err; | |
222 | ||
223 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
224 | INIT_HLIST_HEAD(&eq->hash[i]); | |
225 | ||
3d1ab40f | 226 | return eq; |
9817064b JA |
227 | err: |
228 | kfree(eq); | |
229 | elevator_put(e); | |
230 | return NULL; | |
3d1ab40f AV |
231 | } |
232 | ||
233 | static void elevator_release(struct kobject *kobj) | |
234 | { | |
235 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 236 | |
3d1ab40f | 237 | elevator_put(e->elevator_type); |
9817064b | 238 | kfree(e->hash); |
3d1ab40f AV |
239 | kfree(e); |
240 | } | |
241 | ||
165125e1 | 242 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
243 | { |
244 | struct elevator_type *e = NULL; | |
245 | struct elevator_queue *eq; | |
246 | int ret = 0; | |
bc1c1169 | 247 | void *data; |
1da177e4 | 248 | |
cb98fc8b TH |
249 | INIT_LIST_HEAD(&q->queue_head); |
250 | q->last_merge = NULL; | |
251 | q->end_sector = 0; | |
252 | q->boundary_rq = NULL; | |
cb98fc8b | 253 | |
4eb166d9 JA |
254 | if (name) { |
255 | e = elevator_get(name); | |
256 | if (!e) | |
257 | return -EINVAL; | |
258 | } | |
1da177e4 | 259 | |
4eb166d9 JA |
260 | if (!e && *chosen_elevator) { |
261 | e = elevator_get(chosen_elevator); | |
262 | if (!e) | |
263 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
264 | chosen_elevator); | |
265 | } | |
248d5ca5 | 266 | |
4eb166d9 JA |
267 | if (!e) { |
268 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
269 | if (!e) { | |
270 | printk(KERN_ERR | |
271 | "Default I/O scheduler not found. " \ | |
272 | "Using noop.\n"); | |
273 | e = elevator_get("noop"); | |
274 | } | |
5f003976 ND |
275 | } |
276 | ||
b5deef90 | 277 | eq = elevator_alloc(q, e); |
3d1ab40f | 278 | if (!eq) |
1da177e4 | 279 | return -ENOMEM; |
1da177e4 | 280 | |
bc1c1169 JA |
281 | data = elevator_init_queue(q, eq); |
282 | if (!data) { | |
3d1ab40f | 283 | kobject_put(&eq->kobj); |
bc1c1169 JA |
284 | return -ENOMEM; |
285 | } | |
1da177e4 | 286 | |
bc1c1169 | 287 | elevator_attach(q, eq, data); |
1da177e4 LT |
288 | return ret; |
289 | } | |
2e662b65 JA |
290 | EXPORT_SYMBOL(elevator_init); |
291 | ||
1da177e4 LT |
292 | void elevator_exit(elevator_t *e) |
293 | { | |
3d1ab40f | 294 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
295 | if (e->ops->elevator_exit_fn) |
296 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
297 | e->ops = NULL; |
298 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 299 | |
3d1ab40f | 300 | kobject_put(&e->kobj); |
1da177e4 | 301 | } |
2e662b65 JA |
302 | EXPORT_SYMBOL(elevator_exit); |
303 | ||
165125e1 | 304 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
305 | { |
306 | elevator_t *e = q->elevator; | |
307 | ||
308 | if (e->ops->elevator_activate_req_fn) | |
309 | e->ops->elevator_activate_req_fn(q, rq); | |
310 | } | |
311 | ||
165125e1 | 312 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
313 | { |
314 | elevator_t *e = q->elevator; | |
315 | ||
316 | if (e->ops->elevator_deactivate_req_fn) | |
317 | e->ops->elevator_deactivate_req_fn(q, rq); | |
318 | } | |
319 | ||
9817064b JA |
320 | static inline void __elv_rqhash_del(struct request *rq) |
321 | { | |
322 | hlist_del_init(&rq->hash); | |
323 | } | |
324 | ||
165125e1 | 325 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
326 | { |
327 | if (ELV_ON_HASH(rq)) | |
328 | __elv_rqhash_del(rq); | |
329 | } | |
330 | ||
165125e1 | 331 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b JA |
332 | { |
333 | elevator_t *e = q->elevator; | |
334 | ||
335 | BUG_ON(ELV_ON_HASH(rq)); | |
336 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
337 | } | |
338 | ||
165125e1 | 339 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
340 | { |
341 | __elv_rqhash_del(rq); | |
342 | elv_rqhash_add(q, rq); | |
343 | } | |
344 | ||
165125e1 | 345 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b JA |
346 | { |
347 | elevator_t *e = q->elevator; | |
348 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
349 | struct hlist_node *entry, *next; | |
350 | struct request *rq; | |
351 | ||
352 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
353 | BUG_ON(!ELV_ON_HASH(rq)); | |
354 | ||
355 | if (unlikely(!rq_mergeable(rq))) { | |
356 | __elv_rqhash_del(rq); | |
357 | continue; | |
358 | } | |
359 | ||
360 | if (rq_hash_key(rq) == offset) | |
361 | return rq; | |
362 | } | |
363 | ||
364 | return NULL; | |
365 | } | |
366 | ||
2e662b65 JA |
367 | /* |
368 | * RB-tree support functions for inserting/lookup/removal of requests | |
369 | * in a sorted RB tree. | |
370 | */ | |
371 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
372 | { | |
373 | struct rb_node **p = &root->rb_node; | |
374 | struct rb_node *parent = NULL; | |
375 | struct request *__rq; | |
376 | ||
377 | while (*p) { | |
378 | parent = *p; | |
379 | __rq = rb_entry(parent, struct request, rb_node); | |
380 | ||
381 | if (rq->sector < __rq->sector) | |
382 | p = &(*p)->rb_left; | |
383 | else if (rq->sector > __rq->sector) | |
384 | p = &(*p)->rb_right; | |
385 | else | |
386 | return __rq; | |
387 | } | |
388 | ||
389 | rb_link_node(&rq->rb_node, parent, p); | |
390 | rb_insert_color(&rq->rb_node, root); | |
391 | return NULL; | |
392 | } | |
2e662b65 JA |
393 | EXPORT_SYMBOL(elv_rb_add); |
394 | ||
395 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
396 | { | |
397 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
398 | rb_erase(&rq->rb_node, root); | |
399 | RB_CLEAR_NODE(&rq->rb_node); | |
400 | } | |
2e662b65 JA |
401 | EXPORT_SYMBOL(elv_rb_del); |
402 | ||
403 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
404 | { | |
405 | struct rb_node *n = root->rb_node; | |
406 | struct request *rq; | |
407 | ||
408 | while (n) { | |
409 | rq = rb_entry(n, struct request, rb_node); | |
410 | ||
411 | if (sector < rq->sector) | |
412 | n = n->rb_left; | |
413 | else if (sector > rq->sector) | |
414 | n = n->rb_right; | |
415 | else | |
416 | return rq; | |
417 | } | |
418 | ||
419 | return NULL; | |
420 | } | |
2e662b65 JA |
421 | EXPORT_SYMBOL(elv_rb_find); |
422 | ||
8922e16c TH |
423 | /* |
424 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 425 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 426 | * specific elevators. |
8922e16c | 427 | */ |
165125e1 | 428 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
429 | { |
430 | sector_t boundary; | |
8922e16c | 431 | struct list_head *entry; |
4eb166d9 | 432 | int stop_flags; |
8922e16c | 433 | |
06b86245 TH |
434 | if (q->last_merge == rq) |
435 | q->last_merge = NULL; | |
9817064b JA |
436 | |
437 | elv_rqhash_del(q, rq); | |
438 | ||
15853af9 | 439 | q->nr_sorted--; |
06b86245 | 440 | |
1b47f531 | 441 | boundary = q->end_sector; |
4eb166d9 | 442 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
443 | list_for_each_prev(entry, &q->queue_head) { |
444 | struct request *pos = list_entry_rq(entry); | |
445 | ||
e17fc0a1 DW |
446 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
447 | break; | |
783660b2 JA |
448 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
449 | break; | |
4eb166d9 | 450 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
451 | break; |
452 | if (rq->sector >= boundary) { | |
453 | if (pos->sector < boundary) | |
454 | continue; | |
455 | } else { | |
456 | if (pos->sector >= boundary) | |
457 | break; | |
458 | } | |
459 | if (rq->sector >= pos->sector) | |
460 | break; | |
461 | } | |
462 | ||
463 | list_add(&rq->queuelist, entry); | |
464 | } | |
2e662b65 JA |
465 | EXPORT_SYMBOL(elv_dispatch_sort); |
466 | ||
9817064b | 467 | /* |
2e662b65 JA |
468 | * Insert rq into dispatch queue of q. Queue lock must be held on |
469 | * entry. rq is added to the back of the dispatch queue. To be used by | |
470 | * specific elevators. | |
9817064b JA |
471 | */ |
472 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
473 | { | |
474 | if (q->last_merge == rq) | |
475 | q->last_merge = NULL; | |
476 | ||
477 | elv_rqhash_del(q, rq); | |
478 | ||
479 | q->nr_sorted--; | |
480 | ||
481 | q->end_sector = rq_end_sector(rq); | |
482 | q->boundary_rq = rq; | |
483 | list_add_tail(&rq->queuelist, &q->queue_head); | |
484 | } | |
2e662b65 JA |
485 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
486 | ||
165125e1 | 487 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 LT |
488 | { |
489 | elevator_t *e = q->elevator; | |
9817064b | 490 | struct request *__rq; |
06b86245 TH |
491 | int ret; |
492 | ||
9817064b JA |
493 | /* |
494 | * First try one-hit cache. | |
495 | */ | |
06b86245 TH |
496 | if (q->last_merge) { |
497 | ret = elv_try_merge(q->last_merge, bio); | |
498 | if (ret != ELEVATOR_NO_MERGE) { | |
499 | *req = q->last_merge; | |
500 | return ret; | |
501 | } | |
502 | } | |
1da177e4 | 503 | |
ac9fafa1 AB |
504 | if (blk_queue_nomerges(q)) |
505 | return ELEVATOR_NO_MERGE; | |
506 | ||
9817064b JA |
507 | /* |
508 | * See if our hash lookup can find a potential backmerge. | |
509 | */ | |
510 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
511 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
512 | *req = __rq; | |
513 | return ELEVATOR_BACK_MERGE; | |
514 | } | |
515 | ||
1da177e4 LT |
516 | if (e->ops->elevator_merge_fn) |
517 | return e->ops->elevator_merge_fn(q, req, bio); | |
518 | ||
519 | return ELEVATOR_NO_MERGE; | |
520 | } | |
521 | ||
165125e1 | 522 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 LT |
523 | { |
524 | elevator_t *e = q->elevator; | |
525 | ||
526 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 527 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 528 | |
2e662b65 JA |
529 | if (type == ELEVATOR_BACK_MERGE) |
530 | elv_rqhash_reposition(q, rq); | |
9817064b | 531 | |
06b86245 | 532 | q->last_merge = rq; |
1da177e4 LT |
533 | } |
534 | ||
165125e1 | 535 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
536 | struct request *next) |
537 | { | |
538 | elevator_t *e = q->elevator; | |
539 | ||
1da177e4 LT |
540 | if (e->ops->elevator_merge_req_fn) |
541 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 542 | |
9817064b JA |
543 | elv_rqhash_reposition(q, rq); |
544 | elv_rqhash_del(q, next); | |
545 | ||
546 | q->nr_sorted--; | |
06b86245 | 547 | q->last_merge = rq; |
1da177e4 LT |
548 | } |
549 | ||
165125e1 | 550 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 551 | { |
1da177e4 LT |
552 | /* |
553 | * it already went through dequeue, we need to decrement the | |
554 | * in_flight count again | |
555 | */ | |
8922e16c | 556 | if (blk_account_rq(rq)) { |
1da177e4 | 557 | q->in_flight--; |
cad97516 JA |
558 | if (blk_sorted_rq(rq)) |
559 | elv_deactivate_rq(q, rq); | |
8922e16c | 560 | } |
1da177e4 | 561 | |
4aff5e23 | 562 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 563 | |
30e9656c | 564 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
565 | } |
566 | ||
165125e1 | 567 | static void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
568 | { |
569 | static int printed; | |
570 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
571 | ; | |
572 | if (q->nr_sorted == 0) | |
573 | return; | |
574 | if (printed++ < 10) { | |
575 | printk(KERN_ERR "%s: forced dispatching is broken " | |
576 | "(nr_sorted=%u), please report this\n", | |
577 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
578 | } | |
579 | } | |
580 | ||
165125e1 | 581 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 582 | { |
797e7dbb TH |
583 | struct list_head *pos; |
584 | unsigned ordseq; | |
dac07ec1 | 585 | int unplug_it = 1; |
797e7dbb | 586 | |
2056a782 JA |
587 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
588 | ||
1da177e4 LT |
589 | rq->q = q; |
590 | ||
8922e16c TH |
591 | switch (where) { |
592 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 593 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
594 | |
595 | list_add(&rq->queuelist, &q->queue_head); | |
596 | break; | |
597 | ||
598 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 599 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 600 | elv_drain_elevator(q); |
8922e16c TH |
601 | list_add_tail(&rq->queuelist, &q->queue_head); |
602 | /* | |
603 | * We kick the queue here for the following reasons. | |
604 | * - The elevator might have returned NULL previously | |
605 | * to delay requests and returned them now. As the | |
606 | * queue wasn't empty before this request, ll_rw_blk | |
607 | * won't run the queue on return, resulting in hang. | |
608 | * - Usually, back inserted requests won't be merged | |
609 | * with anything. There's no point in delaying queue | |
610 | * processing. | |
611 | */ | |
612 | blk_remove_plug(q); | |
613 | q->request_fn(q); | |
614 | break; | |
615 | ||
616 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 617 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 618 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 619 | q->nr_sorted++; |
9817064b JA |
620 | if (rq_mergeable(rq)) { |
621 | elv_rqhash_add(q, rq); | |
622 | if (!q->last_merge) | |
623 | q->last_merge = rq; | |
624 | } | |
625 | ||
ca23509f TH |
626 | /* |
627 | * Some ioscheds (cfq) run q->request_fn directly, so | |
628 | * rq cannot be accessed after calling | |
629 | * elevator_add_req_fn. | |
630 | */ | |
631 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
632 | break; |
633 | ||
797e7dbb TH |
634 | case ELEVATOR_INSERT_REQUEUE: |
635 | /* | |
636 | * If ordered flush isn't in progress, we do front | |
637 | * insertion; otherwise, requests should be requeued | |
638 | * in ordseq order. | |
639 | */ | |
4aff5e23 | 640 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 641 | |
95543179 LV |
642 | /* |
643 | * Most requeues happen because of a busy condition, | |
644 | * don't force unplug of the queue for that case. | |
645 | */ | |
646 | unplug_it = 0; | |
647 | ||
797e7dbb TH |
648 | if (q->ordseq == 0) { |
649 | list_add(&rq->queuelist, &q->queue_head); | |
650 | break; | |
651 | } | |
652 | ||
653 | ordseq = blk_ordered_req_seq(rq); | |
654 | ||
655 | list_for_each(pos, &q->queue_head) { | |
656 | struct request *pos_rq = list_entry_rq(pos); | |
657 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
658 | break; | |
659 | } | |
660 | ||
661 | list_add_tail(&rq->queuelist, pos); | |
662 | break; | |
663 | ||
8922e16c TH |
664 | default: |
665 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 666 | __func__, where); |
8922e16c TH |
667 | BUG(); |
668 | } | |
669 | ||
dac07ec1 | 670 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
671 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
672 | - q->in_flight; | |
673 | ||
674 | if (nrq >= q->unplug_thresh) | |
675 | __generic_unplug_device(q); | |
676 | } | |
1da177e4 LT |
677 | } |
678 | ||
165125e1 | 679 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
680 | int plug) |
681 | { | |
682 | if (q->ordcolor) | |
4aff5e23 | 683 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 684 | |
4aff5e23 | 685 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
686 | /* |
687 | * toggle ordered color | |
688 | */ | |
689 | if (blk_barrier_rq(rq)) | |
690 | q->ordcolor ^= 1; | |
691 | ||
692 | /* | |
693 | * barriers implicitly indicate back insertion | |
694 | */ | |
695 | if (where == ELEVATOR_INSERT_SORT) | |
696 | where = ELEVATOR_INSERT_BACK; | |
697 | ||
698 | /* | |
699 | * this request is scheduling boundary, update | |
700 | * end_sector | |
701 | */ | |
e17fc0a1 | 702 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
703 | q->end_sector = rq_end_sector(rq); |
704 | q->boundary_rq = rq; | |
705 | } | |
4eb166d9 JA |
706 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
707 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
708 | where = ELEVATOR_INSERT_BACK; |
709 | ||
710 | if (plug) | |
711 | blk_plug_device(q); | |
712 | ||
713 | elv_insert(q, rq, where); | |
714 | } | |
2e662b65 JA |
715 | EXPORT_SYMBOL(__elv_add_request); |
716 | ||
165125e1 | 717 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
718 | int plug) |
719 | { | |
720 | unsigned long flags; | |
721 | ||
722 | spin_lock_irqsave(q->queue_lock, flags); | |
723 | __elv_add_request(q, rq, where, plug); | |
724 | spin_unlock_irqrestore(q->queue_lock, flags); | |
725 | } | |
2e662b65 JA |
726 | EXPORT_SYMBOL(elv_add_request); |
727 | ||
165125e1 | 728 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 729 | { |
8922e16c TH |
730 | struct request *rq; |
731 | ||
797e7dbb TH |
732 | while (1) { |
733 | while (!list_empty(&q->queue_head)) { | |
734 | rq = list_entry_rq(q->queue_head.next); | |
735 | if (blk_do_ordered(q, &rq)) | |
736 | return rq; | |
737 | } | |
1da177e4 | 738 | |
797e7dbb TH |
739 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
740 | return NULL; | |
1da177e4 | 741 | } |
1da177e4 LT |
742 | } |
743 | ||
165125e1 | 744 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
745 | { |
746 | struct request *rq; | |
747 | int ret; | |
748 | ||
749 | while ((rq = __elv_next_request(q)) != NULL) { | |
bf2de6f5 JA |
750 | /* |
751 | * Kill the empty barrier place holder, the driver must | |
752 | * not ever see it. | |
753 | */ | |
754 | if (blk_empty_barrier(rq)) { | |
755 | end_queued_request(rq, 1); | |
756 | continue; | |
757 | } | |
4aff5e23 | 758 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
759 | /* |
760 | * This is the first time the device driver | |
761 | * sees this request (possibly after | |
762 | * requeueing). Notify IO scheduler. | |
763 | */ | |
cad97516 JA |
764 | if (blk_sorted_rq(rq)) |
765 | elv_activate_rq(q, rq); | |
1da177e4 | 766 | |
8922e16c TH |
767 | /* |
768 | * just mark as started even if we don't start | |
769 | * it, a request that has been delayed should | |
770 | * not be passed by new incoming requests | |
771 | */ | |
4aff5e23 | 772 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 773 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 774 | } |
1da177e4 | 775 | |
8922e16c | 776 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 777 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
778 | q->boundary_rq = NULL; |
779 | } | |
1da177e4 | 780 | |
fa0ccd83 JB |
781 | if (rq->cmd_flags & REQ_DONTPREP) |
782 | break; | |
783 | ||
784 | if (q->dma_drain_size && rq->data_len) { | |
785 | /* | |
786 | * make sure space for the drain appears we | |
787 | * know we can do this because max_hw_segments | |
788 | * has been adjusted to be one fewer than the | |
789 | * device can handle | |
790 | */ | |
791 | rq->nr_phys_segments++; | |
fa0ccd83 JB |
792 | } |
793 | ||
794 | if (!q->prep_rq_fn) | |
1da177e4 LT |
795 | break; |
796 | ||
797 | ret = q->prep_rq_fn(q, rq); | |
798 | if (ret == BLKPREP_OK) { | |
799 | break; | |
800 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
801 | /* |
802 | * the request may have been (partially) prepped. | |
803 | * we need to keep this request in the front to | |
8922e16c TH |
804 | * avoid resource deadlock. REQ_STARTED will |
805 | * prevent other fs requests from passing this one. | |
2e759cd4 | 806 | */ |
fa0ccd83 JB |
807 | if (q->dma_drain_size && rq->data_len && |
808 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
809 | /* | |
810 | * remove the space for the drain we added | |
811 | * so that we don't add it again | |
812 | */ | |
813 | --rq->nr_phys_segments; | |
fa0ccd83 JB |
814 | } |
815 | ||
1da177e4 LT |
816 | rq = NULL; |
817 | break; | |
818 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 819 | rq->cmd_flags |= REQ_QUIET; |
a0cd1285 | 820 | end_queued_request(rq, 0); |
1da177e4 | 821 | } else { |
24c03d47 | 822 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1da177e4 LT |
823 | break; |
824 | } | |
825 | } | |
826 | ||
827 | return rq; | |
828 | } | |
2e662b65 JA |
829 | EXPORT_SYMBOL(elv_next_request); |
830 | ||
165125e1 | 831 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 832 | { |
8922e16c | 833 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 834 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
835 | |
836 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
837 | |
838 | /* | |
839 | * the time frame between a request being removed from the lists | |
840 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 841 | * the driver side. |
1da177e4 LT |
842 | */ |
843 | if (blk_account_rq(rq)) | |
844 | q->in_flight++; | |
1da177e4 | 845 | } |
2e662b65 JA |
846 | EXPORT_SYMBOL(elv_dequeue_request); |
847 | ||
165125e1 | 848 | int elv_queue_empty(struct request_queue *q) |
1da177e4 LT |
849 | { |
850 | elevator_t *e = q->elevator; | |
851 | ||
8922e16c TH |
852 | if (!list_empty(&q->queue_head)) |
853 | return 0; | |
854 | ||
1da177e4 LT |
855 | if (e->ops->elevator_queue_empty_fn) |
856 | return e->ops->elevator_queue_empty_fn(q); | |
857 | ||
8922e16c | 858 | return 1; |
1da177e4 | 859 | } |
2e662b65 JA |
860 | EXPORT_SYMBOL(elv_queue_empty); |
861 | ||
165125e1 | 862 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 863 | { |
1da177e4 LT |
864 | elevator_t *e = q->elevator; |
865 | ||
866 | if (e->ops->elevator_latter_req_fn) | |
867 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
868 | return NULL; |
869 | } | |
870 | ||
165125e1 | 871 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 872 | { |
1da177e4 LT |
873 | elevator_t *e = q->elevator; |
874 | ||
875 | if (e->ops->elevator_former_req_fn) | |
876 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
877 | return NULL; |
878 | } | |
879 | ||
165125e1 | 880 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
881 | { |
882 | elevator_t *e = q->elevator; | |
883 | ||
884 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 885 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
886 | |
887 | rq->elevator_private = NULL; | |
888 | return 0; | |
889 | } | |
890 | ||
165125e1 | 891 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
892 | { |
893 | elevator_t *e = q->elevator; | |
894 | ||
895 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 896 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
897 | } |
898 | ||
165125e1 | 899 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 LT |
900 | { |
901 | elevator_t *e = q->elevator; | |
902 | ||
903 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 904 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
905 | |
906 | return ELV_MQUEUE_MAY; | |
907 | } | |
908 | ||
165125e1 | 909 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
910 | { |
911 | elevator_t *e = q->elevator; | |
912 | ||
913 | /* | |
914 | * request is released from the driver, io must be done | |
915 | */ | |
8922e16c | 916 | if (blk_account_rq(rq)) { |
1da177e4 | 917 | q->in_flight--; |
1bc691d3 TH |
918 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
919 | e->ops->elevator_completed_req_fn(q, rq); | |
920 | } | |
797e7dbb | 921 | |
1bc691d3 TH |
922 | /* |
923 | * Check if the queue is waiting for fs requests to be | |
924 | * drained for flush sequence. | |
925 | */ | |
926 | if (unlikely(q->ordseq)) { | |
927 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
928 | if (q->in_flight == 0 && | |
797e7dbb TH |
929 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
930 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
931 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
932 | q->request_fn(q); | |
933 | } | |
8922e16c | 934 | } |
1da177e4 LT |
935 | } |
936 | ||
3d1ab40f AV |
937 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
938 | ||
939 | static ssize_t | |
940 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 941 | { |
3d1ab40f AV |
942 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
943 | struct elv_fs_entry *entry = to_elv(attr); | |
944 | ssize_t error; | |
945 | ||
946 | if (!entry->show) | |
947 | return -EIO; | |
948 | ||
949 | mutex_lock(&e->sysfs_lock); | |
950 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
951 | mutex_unlock(&e->sysfs_lock); | |
952 | return error; | |
953 | } | |
1da177e4 | 954 | |
3d1ab40f AV |
955 | static ssize_t |
956 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
957 | const char *page, size_t length) | |
958 | { | |
959 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
960 | struct elv_fs_entry *entry = to_elv(attr); | |
961 | ssize_t error; | |
1da177e4 | 962 | |
3d1ab40f AV |
963 | if (!entry->store) |
964 | return -EIO; | |
1da177e4 | 965 | |
3d1ab40f AV |
966 | mutex_lock(&e->sysfs_lock); |
967 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
968 | mutex_unlock(&e->sysfs_lock); | |
969 | return error; | |
970 | } | |
971 | ||
972 | static struct sysfs_ops elv_sysfs_ops = { | |
973 | .show = elv_attr_show, | |
974 | .store = elv_attr_store, | |
975 | }; | |
976 | ||
977 | static struct kobj_type elv_ktype = { | |
978 | .sysfs_ops = &elv_sysfs_ops, | |
979 | .release = elevator_release, | |
980 | }; | |
981 | ||
982 | int elv_register_queue(struct request_queue *q) | |
983 | { | |
984 | elevator_t *e = q->elevator; | |
985 | int error; | |
986 | ||
b2d6db58 | 987 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 988 | if (!error) { |
e572ec7e | 989 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 990 | if (attr) { |
e572ec7e AV |
991 | while (attr->attr.name) { |
992 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 993 | break; |
e572ec7e | 994 | attr++; |
3d1ab40f AV |
995 | } |
996 | } | |
997 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
998 | } | |
999 | return error; | |
1da177e4 LT |
1000 | } |
1001 | ||
bc1c1169 JA |
1002 | static void __elv_unregister_queue(elevator_t *e) |
1003 | { | |
1004 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
1005 | kobject_del(&e->kobj); | |
1006 | } | |
1007 | ||
1da177e4 LT |
1008 | void elv_unregister_queue(struct request_queue *q) |
1009 | { | |
bc1c1169 JA |
1010 | if (q) |
1011 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
1012 | } |
1013 | ||
2fdd82bd | 1014 | void elv_register(struct elevator_type *e) |
1da177e4 | 1015 | { |
1ffb96c5 | 1016 | char *def = ""; |
2a12dcd7 JA |
1017 | |
1018 | spin_lock(&elv_list_lock); | |
ce524497 | 1019 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 1020 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 1021 | spin_unlock(&elv_list_lock); |
1da177e4 | 1022 | |
5f003976 ND |
1023 | if (!strcmp(e->elevator_name, chosen_elevator) || |
1024 | (!*chosen_elevator && | |
1025 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
1026 | def = " (default)"; |
1027 | ||
4eb166d9 JA |
1028 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1029 | def); | |
1da177e4 LT |
1030 | } |
1031 | EXPORT_SYMBOL_GPL(elv_register); | |
1032 | ||
1033 | void elv_unregister(struct elevator_type *e) | |
1034 | { | |
83521d3e CH |
1035 | struct task_struct *g, *p; |
1036 | ||
1037 | /* | |
1038 | * Iterate every thread in the process to remove the io contexts. | |
1039 | */ | |
e17a9489 AV |
1040 | if (e->ops.trim) { |
1041 | read_lock(&tasklist_lock); | |
1042 | do_each_thread(g, p) { | |
1043 | task_lock(p); | |
2d8f6131 ON |
1044 | if (p->io_context) |
1045 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1046 | task_unlock(p); |
1047 | } while_each_thread(g, p); | |
1048 | read_unlock(&tasklist_lock); | |
1049 | } | |
83521d3e | 1050 | |
2a12dcd7 | 1051 | spin_lock(&elv_list_lock); |
1da177e4 | 1052 | list_del_init(&e->list); |
2a12dcd7 | 1053 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1054 | } |
1055 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1056 | ||
1057 | /* | |
1058 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1059 | * we don't free the old io scheduler, before we have allocated what we | |
1060 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1061 | * one, if the new one fails init for some reason. |
1da177e4 | 1062 | */ |
165125e1 | 1063 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1064 | { |
cb98fc8b | 1065 | elevator_t *old_elevator, *e; |
bc1c1169 | 1066 | void *data; |
1da177e4 | 1067 | |
cb98fc8b TH |
1068 | /* |
1069 | * Allocate new elevator | |
1070 | */ | |
b5deef90 | 1071 | e = elevator_alloc(q, new_e); |
1da177e4 | 1072 | if (!e) |
3d1ab40f | 1073 | return 0; |
1da177e4 | 1074 | |
bc1c1169 JA |
1075 | data = elevator_init_queue(q, e); |
1076 | if (!data) { | |
1077 | kobject_put(&e->kobj); | |
1078 | return 0; | |
1079 | } | |
1080 | ||
1da177e4 | 1081 | /* |
cb98fc8b | 1082 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1083 | */ |
cb98fc8b TH |
1084 | spin_lock_irq(q->queue_lock); |
1085 | ||
75ad23bc | 1086 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
cb98fc8b | 1087 | |
15853af9 | 1088 | elv_drain_elevator(q); |
cb98fc8b TH |
1089 | |
1090 | while (q->rq.elvpriv) { | |
407df2aa TH |
1091 | blk_remove_plug(q); |
1092 | q->request_fn(q); | |
cb98fc8b | 1093 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1094 | msleep(10); |
cb98fc8b | 1095 | spin_lock_irq(q->queue_lock); |
15853af9 | 1096 | elv_drain_elevator(q); |
cb98fc8b TH |
1097 | } |
1098 | ||
1da177e4 | 1099 | /* |
bc1c1169 | 1100 | * Remember old elevator. |
1da177e4 | 1101 | */ |
1da177e4 LT |
1102 | old_elevator = q->elevator; |
1103 | ||
1da177e4 LT |
1104 | /* |
1105 | * attach and start new elevator | |
1106 | */ | |
bc1c1169 JA |
1107 | elevator_attach(q, e, data); |
1108 | ||
1109 | spin_unlock_irq(q->queue_lock); | |
1110 | ||
1111 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1112 | |
1113 | if (elv_register_queue(q)) | |
1114 | goto fail_register; | |
1115 | ||
1116 | /* | |
cb98fc8b | 1117 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1118 | */ |
1119 | elevator_exit(old_elevator); | |
75ad23bc NP |
1120 | spin_lock_irq(q->queue_lock); |
1121 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1122 | spin_unlock_irq(q->queue_lock); | |
1123 | ||
4722dc52 AB |
1124 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1125 | ||
3d1ab40f | 1126 | return 1; |
1da177e4 LT |
1127 | |
1128 | fail_register: | |
1129 | /* | |
1130 | * switch failed, exit the new io scheduler and reattach the old | |
1131 | * one again (along with re-adding the sysfs dir) | |
1132 | */ | |
1133 | elevator_exit(e); | |
1da177e4 LT |
1134 | q->elevator = old_elevator; |
1135 | elv_register_queue(q); | |
75ad23bc NP |
1136 | |
1137 | spin_lock_irq(q->queue_lock); | |
1138 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1139 | spin_unlock_irq(q->queue_lock); | |
1140 | ||
3d1ab40f | 1141 | return 0; |
1da177e4 LT |
1142 | } |
1143 | ||
165125e1 JA |
1144 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1145 | size_t count) | |
1da177e4 LT |
1146 | { |
1147 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1148 | size_t len; |
1da177e4 LT |
1149 | struct elevator_type *e; |
1150 | ||
be561235 TH |
1151 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1152 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1153 | len = strlen(elevator_name); | |
1da177e4 | 1154 | |
be561235 TH |
1155 | if (len && elevator_name[len - 1] == '\n') |
1156 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1157 | |
1158 | e = elevator_get(elevator_name); | |
1159 | if (!e) { | |
1160 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1161 | return -EINVAL; | |
1162 | } | |
1163 | ||
2ca7d93b ND |
1164 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1165 | elevator_put(e); | |
1da177e4 | 1166 | return count; |
2ca7d93b | 1167 | } |
1da177e4 | 1168 | |
3d1ab40f | 1169 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1170 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1171 | elevator_name); | |
1da177e4 LT |
1172 | return count; |
1173 | } | |
1174 | ||
165125e1 | 1175 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 LT |
1176 | { |
1177 | elevator_t *e = q->elevator; | |
1178 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1179 | struct elevator_type *__e; |
1da177e4 LT |
1180 | int len = 0; |
1181 | ||
2a12dcd7 | 1182 | spin_lock(&elv_list_lock); |
70cee26e | 1183 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1184 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1185 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1186 | else | |
1187 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1188 | } | |
2a12dcd7 | 1189 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1190 | |
1191 | len += sprintf(len+name, "\n"); | |
1192 | return len; | |
1193 | } | |
1194 | ||
165125e1 JA |
1195 | struct request *elv_rb_former_request(struct request_queue *q, |
1196 | struct request *rq) | |
2e662b65 JA |
1197 | { |
1198 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1199 | ||
1200 | if (rbprev) | |
1201 | return rb_entry_rq(rbprev); | |
1202 | ||
1203 | return NULL; | |
1204 | } | |
2e662b65 JA |
1205 | EXPORT_SYMBOL(elv_rb_former_request); |
1206 | ||
165125e1 JA |
1207 | struct request *elv_rb_latter_request(struct request_queue *q, |
1208 | struct request *rq) | |
2e662b65 JA |
1209 | { |
1210 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1211 | ||
1212 | if (rbnext) | |
1213 | return rb_entry_rq(rbnext); | |
1214 | ||
1215 | return NULL; | |
1216 | } | |
2e662b65 | 1217 | EXPORT_SYMBOL(elv_rb_latter_request); |