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> |
5f3ea37c | 36 | #include <trace/block.h> |
9817064b | 37 | #include <linux/hash.h> |
0835da67 | 38 | #include <linux/uaccess.h> |
1da177e4 | 39 | |
242f9dcb JA |
40 | #include "blk.h" |
41 | ||
1da177e4 LT |
42 | static DEFINE_SPINLOCK(elv_list_lock); |
43 | static LIST_HEAD(elv_list); | |
44 | ||
9817064b JA |
45 | /* |
46 | * Merge hash stuff. | |
47 | */ | |
48 | static const int elv_hash_shift = 6; | |
49 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
50 | #define ELV_HASH_FN(sec) \ |
51 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
52 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
53 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
54 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
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; |
da775265 JA |
63 | elevator_t *e = q->elevator; |
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 | */ | |
82 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
83 | return 0; | |
84 | ||
1da177e4 LT |
85 | /* |
86 | * different data direction or already started, don't merge | |
87 | */ | |
88 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
89 | return 0; | |
90 | ||
91 | /* | |
da775265 | 92 | * must be same device and not a special request |
1da177e4 | 93 | */ |
bb4067e3 | 94 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
95 | return 0; |
96 | ||
7ba1ba12 MP |
97 | /* |
98 | * only merge integrity protected bio into ditto rq | |
99 | */ | |
100 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
101 | return 0; | |
102 | ||
da775265 JA |
103 | if (!elv_iosched_allow_merge(rq, bio)) |
104 | return 0; | |
1da177e4 | 105 | |
da775265 | 106 | return 1; |
1da177e4 LT |
107 | } |
108 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
109 | ||
769db45b | 110 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
111 | { |
112 | int ret = ELEVATOR_NO_MERGE; | |
113 | ||
114 | /* | |
115 | * we can merge and sequence is ok, check if it's possible | |
116 | */ | |
117 | if (elv_rq_merge_ok(__rq, bio)) { | |
118 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
119 | ret = ELEVATOR_BACK_MERGE; | |
120 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
121 | ret = ELEVATOR_FRONT_MERGE; | |
122 | } | |
123 | ||
124 | return ret; | |
125 | } | |
1da177e4 | 126 | |
1da177e4 LT |
127 | static struct elevator_type *elevator_find(const char *name) |
128 | { | |
a22b169d | 129 | struct elevator_type *e; |
1da177e4 | 130 | |
70cee26e | 131 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
132 | if (!strcmp(e->elevator_name, name)) |
133 | return e; | |
1da177e4 | 134 | } |
1da177e4 | 135 | |
a22b169d | 136 | return NULL; |
1da177e4 LT |
137 | } |
138 | ||
139 | static void elevator_put(struct elevator_type *e) | |
140 | { | |
141 | module_put(e->elevator_owner); | |
142 | } | |
143 | ||
144 | static struct elevator_type *elevator_get(const char *name) | |
145 | { | |
2824bc93 | 146 | struct elevator_type *e; |
1da177e4 | 147 | |
2a12dcd7 | 148 | spin_lock(&elv_list_lock); |
2824bc93 TH |
149 | |
150 | e = elevator_find(name); | |
e1640949 JA |
151 | if (!e) { |
152 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
153 | ||
154 | spin_unlock(&elv_list_lock); | |
155 | ||
156 | if (!strcmp(name, "anticipatory")) | |
157 | sprintf(elv, "as-iosched"); | |
158 | else | |
159 | sprintf(elv, "%s-iosched", name); | |
160 | ||
e180f594 | 161 | request_module("%s", elv); |
e1640949 JA |
162 | spin_lock(&elv_list_lock); |
163 | e = elevator_find(name); | |
164 | } | |
165 | ||
2824bc93 TH |
166 | if (e && !try_module_get(e->elevator_owner)) |
167 | e = NULL; | |
168 | ||
2a12dcd7 | 169 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
170 | |
171 | return e; | |
172 | } | |
173 | ||
165125e1 JA |
174 | static void *elevator_init_queue(struct request_queue *q, |
175 | struct elevator_queue *eq) | |
1da177e4 | 176 | { |
bb37b94c | 177 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 178 | } |
1da177e4 | 179 | |
165125e1 | 180 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
181 | void *data) |
182 | { | |
1da177e4 | 183 | q->elevator = eq; |
bc1c1169 | 184 | eq->elevator_data = data; |
1da177e4 LT |
185 | } |
186 | ||
187 | static char chosen_elevator[16]; | |
188 | ||
5f003976 | 189 | static int __init elevator_setup(char *str) |
1da177e4 | 190 | { |
752a3b79 CE |
191 | /* |
192 | * Be backwards-compatible with previous kernels, so users | |
193 | * won't get the wrong elevator. | |
194 | */ | |
5f003976 | 195 | if (!strcmp(str, "as")) |
752a3b79 | 196 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 197 | else |
5f003976 | 198 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 199 | return 1; |
1da177e4 LT |
200 | } |
201 | ||
202 | __setup("elevator=", elevator_setup); | |
203 | ||
3d1ab40f AV |
204 | static struct kobj_type elv_ktype; |
205 | ||
165125e1 JA |
206 | static elevator_t *elevator_alloc(struct request_queue *q, |
207 | struct elevator_type *e) | |
3d1ab40f | 208 | { |
9817064b JA |
209 | elevator_t *eq; |
210 | int i; | |
211 | ||
94f6030c | 212 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
213 | if (unlikely(!eq)) |
214 | goto err; | |
215 | ||
9817064b JA |
216 | eq->ops = &e->ops; |
217 | eq->elevator_type = e; | |
f9cb074b | 218 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
219 | mutex_init(&eq->sysfs_lock); |
220 | ||
b5deef90 JA |
221 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
222 | GFP_KERNEL, q->node); | |
9817064b JA |
223 | if (!eq->hash) |
224 | goto err; | |
225 | ||
226 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
227 | INIT_HLIST_HEAD(&eq->hash[i]); | |
228 | ||
3d1ab40f | 229 | return eq; |
9817064b JA |
230 | err: |
231 | kfree(eq); | |
232 | elevator_put(e); | |
233 | return NULL; | |
3d1ab40f AV |
234 | } |
235 | ||
236 | static void elevator_release(struct kobject *kobj) | |
237 | { | |
238 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 239 | |
3d1ab40f | 240 | elevator_put(e->elevator_type); |
9817064b | 241 | kfree(e->hash); |
3d1ab40f AV |
242 | kfree(e); |
243 | } | |
244 | ||
165125e1 | 245 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
246 | { |
247 | struct elevator_type *e = NULL; | |
248 | struct elevator_queue *eq; | |
249 | int ret = 0; | |
bc1c1169 | 250 | void *data; |
1da177e4 | 251 | |
cb98fc8b TH |
252 | INIT_LIST_HEAD(&q->queue_head); |
253 | q->last_merge = NULL; | |
254 | q->end_sector = 0; | |
255 | q->boundary_rq = NULL; | |
cb98fc8b | 256 | |
4eb166d9 JA |
257 | if (name) { |
258 | e = elevator_get(name); | |
259 | if (!e) | |
260 | return -EINVAL; | |
261 | } | |
1da177e4 | 262 | |
4eb166d9 JA |
263 | if (!e && *chosen_elevator) { |
264 | e = elevator_get(chosen_elevator); | |
265 | if (!e) | |
266 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
267 | chosen_elevator); | |
268 | } | |
248d5ca5 | 269 | |
4eb166d9 JA |
270 | if (!e) { |
271 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
272 | if (!e) { | |
273 | printk(KERN_ERR | |
274 | "Default I/O scheduler not found. " \ | |
275 | "Using noop.\n"); | |
276 | e = elevator_get("noop"); | |
277 | } | |
5f003976 ND |
278 | } |
279 | ||
b5deef90 | 280 | eq = elevator_alloc(q, e); |
3d1ab40f | 281 | if (!eq) |
1da177e4 | 282 | return -ENOMEM; |
1da177e4 | 283 | |
bc1c1169 JA |
284 | data = elevator_init_queue(q, eq); |
285 | if (!data) { | |
3d1ab40f | 286 | kobject_put(&eq->kobj); |
bc1c1169 JA |
287 | return -ENOMEM; |
288 | } | |
1da177e4 | 289 | |
bc1c1169 | 290 | elevator_attach(q, eq, data); |
1da177e4 LT |
291 | return ret; |
292 | } | |
2e662b65 JA |
293 | EXPORT_SYMBOL(elevator_init); |
294 | ||
1da177e4 LT |
295 | void elevator_exit(elevator_t *e) |
296 | { | |
3d1ab40f | 297 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
298 | if (e->ops->elevator_exit_fn) |
299 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
300 | e->ops = NULL; |
301 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 302 | |
3d1ab40f | 303 | kobject_put(&e->kobj); |
1da177e4 | 304 | } |
2e662b65 JA |
305 | EXPORT_SYMBOL(elevator_exit); |
306 | ||
165125e1 | 307 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
308 | { |
309 | elevator_t *e = q->elevator; | |
310 | ||
311 | if (e->ops->elevator_activate_req_fn) | |
312 | e->ops->elevator_activate_req_fn(q, rq); | |
313 | } | |
314 | ||
165125e1 | 315 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
316 | { |
317 | elevator_t *e = q->elevator; | |
318 | ||
319 | if (e->ops->elevator_deactivate_req_fn) | |
320 | e->ops->elevator_deactivate_req_fn(q, rq); | |
321 | } | |
322 | ||
9817064b JA |
323 | static inline void __elv_rqhash_del(struct request *rq) |
324 | { | |
325 | hlist_del_init(&rq->hash); | |
326 | } | |
327 | ||
165125e1 | 328 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
329 | { |
330 | if (ELV_ON_HASH(rq)) | |
331 | __elv_rqhash_del(rq); | |
332 | } | |
333 | ||
165125e1 | 334 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b JA |
335 | { |
336 | elevator_t *e = q->elevator; | |
337 | ||
338 | BUG_ON(ELV_ON_HASH(rq)); | |
339 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
340 | } | |
341 | ||
165125e1 | 342 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
343 | { |
344 | __elv_rqhash_del(rq); | |
345 | elv_rqhash_add(q, rq); | |
346 | } | |
347 | ||
165125e1 | 348 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b JA |
349 | { |
350 | elevator_t *e = q->elevator; | |
351 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
352 | struct hlist_node *entry, *next; | |
353 | struct request *rq; | |
354 | ||
355 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
356 | BUG_ON(!ELV_ON_HASH(rq)); | |
357 | ||
358 | if (unlikely(!rq_mergeable(rq))) { | |
359 | __elv_rqhash_del(rq); | |
360 | continue; | |
361 | } | |
362 | ||
363 | if (rq_hash_key(rq) == offset) | |
364 | return rq; | |
365 | } | |
366 | ||
367 | return NULL; | |
368 | } | |
369 | ||
2e662b65 JA |
370 | /* |
371 | * RB-tree support functions for inserting/lookup/removal of requests | |
372 | * in a sorted RB tree. | |
373 | */ | |
374 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
375 | { | |
376 | struct rb_node **p = &root->rb_node; | |
377 | struct rb_node *parent = NULL; | |
378 | struct request *__rq; | |
379 | ||
380 | while (*p) { | |
381 | parent = *p; | |
382 | __rq = rb_entry(parent, struct request, rb_node); | |
383 | ||
384 | if (rq->sector < __rq->sector) | |
385 | p = &(*p)->rb_left; | |
386 | else if (rq->sector > __rq->sector) | |
387 | p = &(*p)->rb_right; | |
388 | else | |
389 | return __rq; | |
390 | } | |
391 | ||
392 | rb_link_node(&rq->rb_node, parent, p); | |
393 | rb_insert_color(&rq->rb_node, root); | |
394 | return NULL; | |
395 | } | |
2e662b65 JA |
396 | EXPORT_SYMBOL(elv_rb_add); |
397 | ||
398 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
399 | { | |
400 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
401 | rb_erase(&rq->rb_node, root); | |
402 | RB_CLEAR_NODE(&rq->rb_node); | |
403 | } | |
2e662b65 JA |
404 | EXPORT_SYMBOL(elv_rb_del); |
405 | ||
406 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
407 | { | |
408 | struct rb_node *n = root->rb_node; | |
409 | struct request *rq; | |
410 | ||
411 | while (n) { | |
412 | rq = rb_entry(n, struct request, rb_node); | |
413 | ||
414 | if (sector < rq->sector) | |
415 | n = n->rb_left; | |
416 | else if (sector > rq->sector) | |
417 | n = n->rb_right; | |
418 | else | |
419 | return rq; | |
420 | } | |
421 | ||
422 | return NULL; | |
423 | } | |
2e662b65 JA |
424 | EXPORT_SYMBOL(elv_rb_find); |
425 | ||
8922e16c TH |
426 | /* |
427 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 428 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 429 | * specific elevators. |
8922e16c | 430 | */ |
165125e1 | 431 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
432 | { |
433 | sector_t boundary; | |
8922e16c | 434 | struct list_head *entry; |
4eb166d9 | 435 | int stop_flags; |
8922e16c | 436 | |
06b86245 TH |
437 | if (q->last_merge == rq) |
438 | q->last_merge = NULL; | |
9817064b JA |
439 | |
440 | elv_rqhash_del(q, rq); | |
441 | ||
15853af9 | 442 | q->nr_sorted--; |
06b86245 | 443 | |
1b47f531 | 444 | boundary = q->end_sector; |
4eb166d9 | 445 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
446 | list_for_each_prev(entry, &q->queue_head) { |
447 | struct request *pos = list_entry_rq(entry); | |
448 | ||
e17fc0a1 DW |
449 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
450 | break; | |
783660b2 JA |
451 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
452 | break; | |
4eb166d9 | 453 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
454 | break; |
455 | if (rq->sector >= boundary) { | |
456 | if (pos->sector < boundary) | |
457 | continue; | |
458 | } else { | |
459 | if (pos->sector >= boundary) | |
460 | break; | |
461 | } | |
462 | if (rq->sector >= pos->sector) | |
463 | break; | |
464 | } | |
465 | ||
466 | list_add(&rq->queuelist, entry); | |
467 | } | |
2e662b65 JA |
468 | EXPORT_SYMBOL(elv_dispatch_sort); |
469 | ||
9817064b | 470 | /* |
2e662b65 JA |
471 | * Insert rq into dispatch queue of q. Queue lock must be held on |
472 | * entry. rq is added to the back of the dispatch queue. To be used by | |
473 | * specific elevators. | |
9817064b JA |
474 | */ |
475 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
476 | { | |
477 | if (q->last_merge == rq) | |
478 | q->last_merge = NULL; | |
479 | ||
480 | elv_rqhash_del(q, rq); | |
481 | ||
482 | q->nr_sorted--; | |
483 | ||
484 | q->end_sector = rq_end_sector(rq); | |
485 | q->boundary_rq = rq; | |
486 | list_add_tail(&rq->queuelist, &q->queue_head); | |
487 | } | |
2e662b65 JA |
488 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
489 | ||
165125e1 | 490 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 LT |
491 | { |
492 | elevator_t *e = q->elevator; | |
9817064b | 493 | struct request *__rq; |
06b86245 TH |
494 | int ret; |
495 | ||
9817064b JA |
496 | /* |
497 | * First try one-hit cache. | |
498 | */ | |
06b86245 TH |
499 | if (q->last_merge) { |
500 | ret = elv_try_merge(q->last_merge, bio); | |
501 | if (ret != ELEVATOR_NO_MERGE) { | |
502 | *req = q->last_merge; | |
503 | return ret; | |
504 | } | |
505 | } | |
1da177e4 | 506 | |
ac9fafa1 AB |
507 | if (blk_queue_nomerges(q)) |
508 | return ELEVATOR_NO_MERGE; | |
509 | ||
9817064b JA |
510 | /* |
511 | * See if our hash lookup can find a potential backmerge. | |
512 | */ | |
513 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
514 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
515 | *req = __rq; | |
516 | return ELEVATOR_BACK_MERGE; | |
517 | } | |
518 | ||
1da177e4 LT |
519 | if (e->ops->elevator_merge_fn) |
520 | return e->ops->elevator_merge_fn(q, req, bio); | |
521 | ||
522 | return ELEVATOR_NO_MERGE; | |
523 | } | |
524 | ||
165125e1 | 525 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 LT |
526 | { |
527 | elevator_t *e = q->elevator; | |
528 | ||
529 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 530 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 531 | |
2e662b65 JA |
532 | if (type == ELEVATOR_BACK_MERGE) |
533 | elv_rqhash_reposition(q, rq); | |
9817064b | 534 | |
06b86245 | 535 | q->last_merge = rq; |
1da177e4 LT |
536 | } |
537 | ||
165125e1 | 538 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
539 | struct request *next) |
540 | { | |
541 | elevator_t *e = q->elevator; | |
542 | ||
1da177e4 LT |
543 | if (e->ops->elevator_merge_req_fn) |
544 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 545 | |
9817064b JA |
546 | elv_rqhash_reposition(q, rq); |
547 | elv_rqhash_del(q, next); | |
548 | ||
549 | q->nr_sorted--; | |
06b86245 | 550 | q->last_merge = rq; |
1da177e4 LT |
551 | } |
552 | ||
165125e1 | 553 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 554 | { |
1da177e4 LT |
555 | /* |
556 | * it already went through dequeue, we need to decrement the | |
557 | * in_flight count again | |
558 | */ | |
8922e16c | 559 | if (blk_account_rq(rq)) { |
1da177e4 | 560 | q->in_flight--; |
cad97516 JA |
561 | if (blk_sorted_rq(rq)) |
562 | elv_deactivate_rq(q, rq); | |
8922e16c | 563 | } |
1da177e4 | 564 | |
4aff5e23 | 565 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 566 | |
30e9656c | 567 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
568 | } |
569 | ||
165125e1 | 570 | static void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
571 | { |
572 | static int printed; | |
573 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
574 | ; | |
575 | if (q->nr_sorted == 0) | |
576 | return; | |
577 | if (printed++ < 10) { | |
578 | printk(KERN_ERR "%s: forced dispatching is broken " | |
579 | "(nr_sorted=%u), please report this\n", | |
580 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
581 | } | |
582 | } | |
583 | ||
165125e1 | 584 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 585 | { |
797e7dbb TH |
586 | struct list_head *pos; |
587 | unsigned ordseq; | |
dac07ec1 | 588 | int unplug_it = 1; |
797e7dbb | 589 | |
5f3ea37c | 590 | trace_block_rq_insert(q, rq); |
2056a782 | 591 | |
1da177e4 LT |
592 | rq->q = q; |
593 | ||
8922e16c TH |
594 | switch (where) { |
595 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 596 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
597 | |
598 | list_add(&rq->queuelist, &q->queue_head); | |
599 | break; | |
600 | ||
601 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 602 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 603 | elv_drain_elevator(q); |
8922e16c TH |
604 | list_add_tail(&rq->queuelist, &q->queue_head); |
605 | /* | |
606 | * We kick the queue here for the following reasons. | |
607 | * - The elevator might have returned NULL previously | |
608 | * to delay requests and returned them now. As the | |
609 | * queue wasn't empty before this request, ll_rw_blk | |
610 | * won't run the queue on return, resulting in hang. | |
611 | * - Usually, back inserted requests won't be merged | |
612 | * with anything. There's no point in delaying queue | |
613 | * processing. | |
614 | */ | |
615 | blk_remove_plug(q); | |
80a4b58e | 616 | blk_start_queueing(q); |
8922e16c TH |
617 | break; |
618 | ||
619 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 620 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 621 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 622 | q->nr_sorted++; |
9817064b JA |
623 | if (rq_mergeable(rq)) { |
624 | elv_rqhash_add(q, rq); | |
625 | if (!q->last_merge) | |
626 | q->last_merge = rq; | |
627 | } | |
628 | ||
ca23509f TH |
629 | /* |
630 | * Some ioscheds (cfq) run q->request_fn directly, so | |
631 | * rq cannot be accessed after calling | |
632 | * elevator_add_req_fn. | |
633 | */ | |
634 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
635 | break; |
636 | ||
797e7dbb TH |
637 | case ELEVATOR_INSERT_REQUEUE: |
638 | /* | |
639 | * If ordered flush isn't in progress, we do front | |
640 | * insertion; otherwise, requests should be requeued | |
641 | * in ordseq order. | |
642 | */ | |
4aff5e23 | 643 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 644 | |
95543179 LV |
645 | /* |
646 | * Most requeues happen because of a busy condition, | |
647 | * don't force unplug of the queue for that case. | |
648 | */ | |
649 | unplug_it = 0; | |
650 | ||
797e7dbb TH |
651 | if (q->ordseq == 0) { |
652 | list_add(&rq->queuelist, &q->queue_head); | |
653 | break; | |
654 | } | |
655 | ||
656 | ordseq = blk_ordered_req_seq(rq); | |
657 | ||
658 | list_for_each(pos, &q->queue_head) { | |
659 | struct request *pos_rq = list_entry_rq(pos); | |
660 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
661 | break; | |
662 | } | |
663 | ||
664 | list_add_tail(&rq->queuelist, pos); | |
665 | break; | |
666 | ||
8922e16c TH |
667 | default: |
668 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 669 | __func__, where); |
8922e16c TH |
670 | BUG(); |
671 | } | |
672 | ||
dac07ec1 | 673 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
674 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
675 | - q->in_flight; | |
676 | ||
677 | if (nrq >= q->unplug_thresh) | |
678 | __generic_unplug_device(q); | |
679 | } | |
1da177e4 LT |
680 | } |
681 | ||
165125e1 | 682 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
683 | int plug) |
684 | { | |
685 | if (q->ordcolor) | |
4aff5e23 | 686 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 687 | |
4aff5e23 | 688 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
689 | /* |
690 | * toggle ordered color | |
691 | */ | |
692 | if (blk_barrier_rq(rq)) | |
693 | q->ordcolor ^= 1; | |
694 | ||
695 | /* | |
696 | * barriers implicitly indicate back insertion | |
697 | */ | |
698 | if (where == ELEVATOR_INSERT_SORT) | |
699 | where = ELEVATOR_INSERT_BACK; | |
700 | ||
701 | /* | |
702 | * this request is scheduling boundary, update | |
703 | * end_sector | |
704 | */ | |
e17fc0a1 | 705 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
706 | q->end_sector = rq_end_sector(rq); |
707 | q->boundary_rq = rq; | |
708 | } | |
4eb166d9 JA |
709 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
710 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
711 | where = ELEVATOR_INSERT_BACK; |
712 | ||
713 | if (plug) | |
714 | blk_plug_device(q); | |
715 | ||
716 | elv_insert(q, rq, where); | |
717 | } | |
2e662b65 JA |
718 | EXPORT_SYMBOL(__elv_add_request); |
719 | ||
165125e1 | 720 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
721 | int plug) |
722 | { | |
723 | unsigned long flags; | |
724 | ||
725 | spin_lock_irqsave(q->queue_lock, flags); | |
726 | __elv_add_request(q, rq, where, plug); | |
727 | spin_unlock_irqrestore(q->queue_lock, flags); | |
728 | } | |
2e662b65 JA |
729 | EXPORT_SYMBOL(elv_add_request); |
730 | ||
165125e1 | 731 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 732 | { |
8922e16c TH |
733 | struct request *rq; |
734 | ||
797e7dbb TH |
735 | while (1) { |
736 | while (!list_empty(&q->queue_head)) { | |
737 | rq = list_entry_rq(q->queue_head.next); | |
738 | if (blk_do_ordered(q, &rq)) | |
739 | return rq; | |
740 | } | |
1da177e4 | 741 | |
797e7dbb TH |
742 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
743 | return NULL; | |
1da177e4 | 744 | } |
1da177e4 LT |
745 | } |
746 | ||
165125e1 | 747 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
748 | { |
749 | struct request *rq; | |
750 | int ret; | |
751 | ||
752 | while ((rq = __elv_next_request(q)) != NULL) { | |
bf2de6f5 JA |
753 | /* |
754 | * Kill the empty barrier place holder, the driver must | |
755 | * not ever see it. | |
756 | */ | |
757 | if (blk_empty_barrier(rq)) { | |
99cd3386 | 758 | __blk_end_request(rq, 0, blk_rq_bytes(rq)); |
bf2de6f5 JA |
759 | continue; |
760 | } | |
4aff5e23 | 761 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
762 | /* |
763 | * This is the first time the device driver | |
764 | * sees this request (possibly after | |
765 | * requeueing). Notify IO scheduler. | |
766 | */ | |
cad97516 JA |
767 | if (blk_sorted_rq(rq)) |
768 | elv_activate_rq(q, rq); | |
1da177e4 | 769 | |
8922e16c TH |
770 | /* |
771 | * just mark as started even if we don't start | |
772 | * it, a request that has been delayed should | |
773 | * not be passed by new incoming requests | |
774 | */ | |
4aff5e23 | 775 | rq->cmd_flags |= REQ_STARTED; |
5f3ea37c | 776 | trace_block_rq_issue(q, rq); |
8922e16c | 777 | } |
1da177e4 | 778 | |
8922e16c | 779 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 780 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
781 | q->boundary_rq = NULL; |
782 | } | |
1da177e4 | 783 | |
fa0ccd83 JB |
784 | if (rq->cmd_flags & REQ_DONTPREP) |
785 | break; | |
786 | ||
787 | if (q->dma_drain_size && rq->data_len) { | |
788 | /* | |
789 | * make sure space for the drain appears we | |
790 | * know we can do this because max_hw_segments | |
791 | * has been adjusted to be one fewer than the | |
792 | * device can handle | |
793 | */ | |
794 | rq->nr_phys_segments++; | |
fa0ccd83 JB |
795 | } |
796 | ||
797 | if (!q->prep_rq_fn) | |
1da177e4 LT |
798 | break; |
799 | ||
800 | ret = q->prep_rq_fn(q, rq); | |
801 | if (ret == BLKPREP_OK) { | |
802 | break; | |
803 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
804 | /* |
805 | * the request may have been (partially) prepped. | |
806 | * we need to keep this request in the front to | |
8922e16c TH |
807 | * avoid resource deadlock. REQ_STARTED will |
808 | * prevent other fs requests from passing this one. | |
2e759cd4 | 809 | */ |
fa0ccd83 JB |
810 | if (q->dma_drain_size && rq->data_len && |
811 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
812 | /* | |
813 | * remove the space for the drain we added | |
814 | * so that we don't add it again | |
815 | */ | |
816 | --rq->nr_phys_segments; | |
fa0ccd83 JB |
817 | } |
818 | ||
1da177e4 LT |
819 | rq = NULL; |
820 | break; | |
821 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 822 | rq->cmd_flags |= REQ_QUIET; |
99cd3386 | 823 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
1da177e4 | 824 | } else { |
24c03d47 | 825 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1da177e4 LT |
826 | break; |
827 | } | |
828 | } | |
829 | ||
830 | return rq; | |
831 | } | |
2e662b65 JA |
832 | EXPORT_SYMBOL(elv_next_request); |
833 | ||
165125e1 | 834 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 835 | { |
8922e16c | 836 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 837 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
838 | |
839 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
840 | |
841 | /* | |
842 | * the time frame between a request being removed from the lists | |
843 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 844 | * the driver side. |
1da177e4 LT |
845 | */ |
846 | if (blk_account_rq(rq)) | |
847 | q->in_flight++; | |
2920ebbd TH |
848 | |
849 | /* | |
850 | * We are now handing the request to the hardware, add the | |
851 | * timeout handler. | |
852 | */ | |
853 | blk_add_timer(rq); | |
1da177e4 | 854 | } |
2e662b65 JA |
855 | EXPORT_SYMBOL(elv_dequeue_request); |
856 | ||
165125e1 | 857 | int elv_queue_empty(struct request_queue *q) |
1da177e4 LT |
858 | { |
859 | elevator_t *e = q->elevator; | |
860 | ||
8922e16c TH |
861 | if (!list_empty(&q->queue_head)) |
862 | return 0; | |
863 | ||
1da177e4 LT |
864 | if (e->ops->elevator_queue_empty_fn) |
865 | return e->ops->elevator_queue_empty_fn(q); | |
866 | ||
8922e16c | 867 | return 1; |
1da177e4 | 868 | } |
2e662b65 JA |
869 | EXPORT_SYMBOL(elv_queue_empty); |
870 | ||
165125e1 | 871 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 872 | { |
1da177e4 LT |
873 | elevator_t *e = q->elevator; |
874 | ||
875 | if (e->ops->elevator_latter_req_fn) | |
876 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
877 | return NULL; |
878 | } | |
879 | ||
165125e1 | 880 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 881 | { |
1da177e4 LT |
882 | elevator_t *e = q->elevator; |
883 | ||
884 | if (e->ops->elevator_former_req_fn) | |
885 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
886 | return NULL; |
887 | } | |
888 | ||
165125e1 | 889 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
890 | { |
891 | elevator_t *e = q->elevator; | |
892 | ||
893 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 894 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
895 | |
896 | rq->elevator_private = NULL; | |
897 | return 0; | |
898 | } | |
899 | ||
165125e1 | 900 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
901 | { |
902 | elevator_t *e = q->elevator; | |
903 | ||
904 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 905 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
906 | } |
907 | ||
165125e1 | 908 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 LT |
909 | { |
910 | elevator_t *e = q->elevator; | |
911 | ||
912 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 913 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
914 | |
915 | return ELV_MQUEUE_MAY; | |
916 | } | |
917 | ||
11914a53 MA |
918 | void elv_abort_queue(struct request_queue *q) |
919 | { | |
920 | struct request *rq; | |
921 | ||
922 | while (!list_empty(&q->queue_head)) { | |
923 | rq = list_entry_rq(q->queue_head.next); | |
924 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 925 | trace_block_rq_abort(q, rq); |
99cd3386 | 926 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
11914a53 MA |
927 | } |
928 | } | |
929 | EXPORT_SYMBOL(elv_abort_queue); | |
930 | ||
165125e1 | 931 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
932 | { |
933 | elevator_t *e = q->elevator; | |
934 | ||
935 | /* | |
936 | * request is released from the driver, io must be done | |
937 | */ | |
8922e16c | 938 | if (blk_account_rq(rq)) { |
1da177e4 | 939 | q->in_flight--; |
1bc691d3 TH |
940 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
941 | e->ops->elevator_completed_req_fn(q, rq); | |
942 | } | |
797e7dbb | 943 | |
1bc691d3 TH |
944 | /* |
945 | * Check if the queue is waiting for fs requests to be | |
946 | * drained for flush sequence. | |
947 | */ | |
948 | if (unlikely(q->ordseq)) { | |
949 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
950 | if (q->in_flight == 0 && | |
797e7dbb TH |
951 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
952 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
953 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
80a4b58e | 954 | blk_start_queueing(q); |
797e7dbb | 955 | } |
8922e16c | 956 | } |
1da177e4 LT |
957 | } |
958 | ||
3d1ab40f AV |
959 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
960 | ||
961 | static ssize_t | |
962 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 963 | { |
3d1ab40f AV |
964 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
965 | struct elv_fs_entry *entry = to_elv(attr); | |
966 | ssize_t error; | |
967 | ||
968 | if (!entry->show) | |
969 | return -EIO; | |
970 | ||
971 | mutex_lock(&e->sysfs_lock); | |
972 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
973 | mutex_unlock(&e->sysfs_lock); | |
974 | return error; | |
975 | } | |
1da177e4 | 976 | |
3d1ab40f AV |
977 | static ssize_t |
978 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
979 | const char *page, size_t length) | |
980 | { | |
981 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
982 | struct elv_fs_entry *entry = to_elv(attr); | |
983 | ssize_t error; | |
1da177e4 | 984 | |
3d1ab40f AV |
985 | if (!entry->store) |
986 | return -EIO; | |
1da177e4 | 987 | |
3d1ab40f AV |
988 | mutex_lock(&e->sysfs_lock); |
989 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
990 | mutex_unlock(&e->sysfs_lock); | |
991 | return error; | |
992 | } | |
993 | ||
994 | static struct sysfs_ops elv_sysfs_ops = { | |
995 | .show = elv_attr_show, | |
996 | .store = elv_attr_store, | |
997 | }; | |
998 | ||
999 | static struct kobj_type elv_ktype = { | |
1000 | .sysfs_ops = &elv_sysfs_ops, | |
1001 | .release = elevator_release, | |
1002 | }; | |
1003 | ||
1004 | int elv_register_queue(struct request_queue *q) | |
1005 | { | |
1006 | elevator_t *e = q->elevator; | |
1007 | int error; | |
1008 | ||
b2d6db58 | 1009 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 1010 | if (!error) { |
e572ec7e | 1011 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 1012 | if (attr) { |
e572ec7e AV |
1013 | while (attr->attr.name) { |
1014 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 1015 | break; |
e572ec7e | 1016 | attr++; |
3d1ab40f AV |
1017 | } |
1018 | } | |
1019 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
1020 | } | |
1021 | return error; | |
1da177e4 LT |
1022 | } |
1023 | ||
bc1c1169 JA |
1024 | static void __elv_unregister_queue(elevator_t *e) |
1025 | { | |
1026 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
1027 | kobject_del(&e->kobj); | |
1028 | } | |
1029 | ||
1da177e4 LT |
1030 | void elv_unregister_queue(struct request_queue *q) |
1031 | { | |
bc1c1169 JA |
1032 | if (q) |
1033 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
1034 | } |
1035 | ||
2fdd82bd | 1036 | void elv_register(struct elevator_type *e) |
1da177e4 | 1037 | { |
1ffb96c5 | 1038 | char *def = ""; |
2a12dcd7 JA |
1039 | |
1040 | spin_lock(&elv_list_lock); | |
ce524497 | 1041 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 1042 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 1043 | spin_unlock(&elv_list_lock); |
1da177e4 | 1044 | |
5f003976 ND |
1045 | if (!strcmp(e->elevator_name, chosen_elevator) || |
1046 | (!*chosen_elevator && | |
1047 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
1048 | def = " (default)"; |
1049 | ||
4eb166d9 JA |
1050 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1051 | def); | |
1da177e4 LT |
1052 | } |
1053 | EXPORT_SYMBOL_GPL(elv_register); | |
1054 | ||
1055 | void elv_unregister(struct elevator_type *e) | |
1056 | { | |
83521d3e CH |
1057 | struct task_struct *g, *p; |
1058 | ||
1059 | /* | |
1060 | * Iterate every thread in the process to remove the io contexts. | |
1061 | */ | |
e17a9489 AV |
1062 | if (e->ops.trim) { |
1063 | read_lock(&tasklist_lock); | |
1064 | do_each_thread(g, p) { | |
1065 | task_lock(p); | |
2d8f6131 ON |
1066 | if (p->io_context) |
1067 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1068 | task_unlock(p); |
1069 | } while_each_thread(g, p); | |
1070 | read_unlock(&tasklist_lock); | |
1071 | } | |
83521d3e | 1072 | |
2a12dcd7 | 1073 | spin_lock(&elv_list_lock); |
1da177e4 | 1074 | list_del_init(&e->list); |
2a12dcd7 | 1075 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1076 | } |
1077 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1078 | ||
1079 | /* | |
1080 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1081 | * we don't free the old io scheduler, before we have allocated what we | |
1082 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1083 | * one, if the new one fails init for some reason. |
1da177e4 | 1084 | */ |
165125e1 | 1085 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1086 | { |
cb98fc8b | 1087 | elevator_t *old_elevator, *e; |
bc1c1169 | 1088 | void *data; |
1da177e4 | 1089 | |
cb98fc8b TH |
1090 | /* |
1091 | * Allocate new elevator | |
1092 | */ | |
b5deef90 | 1093 | e = elevator_alloc(q, new_e); |
1da177e4 | 1094 | if (!e) |
3d1ab40f | 1095 | return 0; |
1da177e4 | 1096 | |
bc1c1169 JA |
1097 | data = elevator_init_queue(q, e); |
1098 | if (!data) { | |
1099 | kobject_put(&e->kobj); | |
1100 | return 0; | |
1101 | } | |
1102 | ||
1da177e4 | 1103 | /* |
cb98fc8b | 1104 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1105 | */ |
cb98fc8b TH |
1106 | spin_lock_irq(q->queue_lock); |
1107 | ||
75ad23bc | 1108 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
cb98fc8b | 1109 | |
15853af9 | 1110 | elv_drain_elevator(q); |
cb98fc8b TH |
1111 | |
1112 | while (q->rq.elvpriv) { | |
80a4b58e | 1113 | blk_start_queueing(q); |
cb98fc8b | 1114 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1115 | msleep(10); |
cb98fc8b | 1116 | spin_lock_irq(q->queue_lock); |
15853af9 | 1117 | elv_drain_elevator(q); |
cb98fc8b TH |
1118 | } |
1119 | ||
1da177e4 | 1120 | /* |
bc1c1169 | 1121 | * Remember old elevator. |
1da177e4 | 1122 | */ |
1da177e4 LT |
1123 | old_elevator = q->elevator; |
1124 | ||
1da177e4 LT |
1125 | /* |
1126 | * attach and start new elevator | |
1127 | */ | |
bc1c1169 JA |
1128 | elevator_attach(q, e, data); |
1129 | ||
1130 | spin_unlock_irq(q->queue_lock); | |
1131 | ||
1132 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1133 | |
1134 | if (elv_register_queue(q)) | |
1135 | goto fail_register; | |
1136 | ||
1137 | /* | |
cb98fc8b | 1138 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1139 | */ |
1140 | elevator_exit(old_elevator); | |
75ad23bc NP |
1141 | spin_lock_irq(q->queue_lock); |
1142 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1143 | spin_unlock_irq(q->queue_lock); | |
1144 | ||
4722dc52 AB |
1145 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1146 | ||
3d1ab40f | 1147 | return 1; |
1da177e4 LT |
1148 | |
1149 | fail_register: | |
1150 | /* | |
1151 | * switch failed, exit the new io scheduler and reattach the old | |
1152 | * one again (along with re-adding the sysfs dir) | |
1153 | */ | |
1154 | elevator_exit(e); | |
1da177e4 LT |
1155 | q->elevator = old_elevator; |
1156 | elv_register_queue(q); | |
75ad23bc NP |
1157 | |
1158 | spin_lock_irq(q->queue_lock); | |
1159 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1160 | spin_unlock_irq(q->queue_lock); | |
1161 | ||
3d1ab40f | 1162 | return 0; |
1da177e4 LT |
1163 | } |
1164 | ||
165125e1 JA |
1165 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1166 | size_t count) | |
1da177e4 LT |
1167 | { |
1168 | char elevator_name[ELV_NAME_MAX]; | |
1169 | struct elevator_type *e; | |
1170 | ||
ee2e992c LZ |
1171 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1172 | strstrip(elevator_name); | |
1da177e4 LT |
1173 | |
1174 | e = elevator_get(elevator_name); | |
1175 | if (!e) { | |
1176 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1177 | return -EINVAL; | |
1178 | } | |
1179 | ||
2ca7d93b ND |
1180 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1181 | elevator_put(e); | |
1da177e4 | 1182 | return count; |
2ca7d93b | 1183 | } |
1da177e4 | 1184 | |
3d1ab40f | 1185 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1186 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1187 | elevator_name); | |
1da177e4 LT |
1188 | return count; |
1189 | } | |
1190 | ||
165125e1 | 1191 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 LT |
1192 | { |
1193 | elevator_t *e = q->elevator; | |
1194 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1195 | struct elevator_type *__e; |
1da177e4 LT |
1196 | int len = 0; |
1197 | ||
2a12dcd7 | 1198 | spin_lock(&elv_list_lock); |
70cee26e | 1199 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1200 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1201 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1202 | else | |
1203 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1204 | } | |
2a12dcd7 | 1205 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1206 | |
1207 | len += sprintf(len+name, "\n"); | |
1208 | return len; | |
1209 | } | |
1210 | ||
165125e1 JA |
1211 | struct request *elv_rb_former_request(struct request_queue *q, |
1212 | struct request *rq) | |
2e662b65 JA |
1213 | { |
1214 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1215 | ||
1216 | if (rbprev) | |
1217 | return rb_entry_rq(rbprev); | |
1218 | ||
1219 | return NULL; | |
1220 | } | |
2e662b65 JA |
1221 | EXPORT_SYMBOL(elv_rb_former_request); |
1222 | ||
165125e1 JA |
1223 | struct request *elv_rb_latter_request(struct request_queue *q, |
1224 | struct request *rq) | |
2e662b65 JA |
1225 | { |
1226 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1227 | ||
1228 | if (rbnext) | |
1229 | return rb_entry_rq(rbnext); | |
1230 | ||
1231 | return NULL; | |
1232 | } | |
2e662b65 | 1233 | EXPORT_SYMBOL(elv_rb_latter_request); |