Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
29 | #include <linux/bio.h> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
cb98fc8b | 34 | #include <linux/delay.h> |
2056a782 | 35 | #include <linux/blktrace_api.h> |
9817064b | 36 | #include <linux/hash.h> |
0835da67 | 37 | #include <linux/uaccess.h> |
1da177e4 | 38 | |
55782138 LZ |
39 | #include <trace/events/block.h> |
40 | ||
242f9dcb JA |
41 | #include "blk.h" |
42 | ||
1da177e4 LT |
43 | static DEFINE_SPINLOCK(elv_list_lock); |
44 | static LIST_HEAD(elv_list); | |
45 | ||
9817064b JA |
46 | /* |
47 | * Merge hash stuff. | |
48 | */ | |
49 | static const int elv_hash_shift = 6; | |
50 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
51 | #define ELV_HASH_FN(sec) \ |
52 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
53 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
54 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
55 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
56 | ||
da775265 JA |
57 | /* |
58 | * Query io scheduler to see if the current process issuing bio may be | |
59 | * merged with rq. | |
60 | */ | |
61 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
62 | { | |
165125e1 | 63 | struct request_queue *q = rq->q; |
b374d18a | 64 | struct elevator_queue *e = q->elevator; |
da775265 JA |
65 | |
66 | if (e->ops->elevator_allow_merge_fn) | |
67 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
68 | ||
69 | return 1; | |
70 | } | |
71 | ||
1da177e4 LT |
72 | /* |
73 | * can we safely merge with this request? | |
74 | */ | |
72ed0bf6 | 75 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
76 | { |
77 | if (!rq_mergeable(rq)) | |
78 | return 0; | |
79 | ||
e17fc0a1 DW |
80 | /* |
81 | * Don't merge file system requests and discard requests | |
82 | */ | |
83 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
84 | return 0; | |
85 | ||
1da177e4 LT |
86 | /* |
87 | * different data direction or already started, don't merge | |
88 | */ | |
89 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
90 | return 0; | |
91 | ||
92 | /* | |
da775265 | 93 | * must be same device and not a special request |
1da177e4 | 94 | */ |
bb4067e3 | 95 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
96 | return 0; |
97 | ||
7ba1ba12 MP |
98 | /* |
99 | * only merge integrity protected bio into ditto rq | |
100 | */ | |
101 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
102 | return 0; | |
103 | ||
da775265 JA |
104 | if (!elv_iosched_allow_merge(rq, bio)) |
105 | return 0; | |
1da177e4 | 106 | |
da775265 | 107 | return 1; |
1da177e4 LT |
108 | } |
109 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
110 | ||
769db45b | 111 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
112 | { |
113 | int ret = ELEVATOR_NO_MERGE; | |
114 | ||
115 | /* | |
116 | * we can merge and sequence is ok, check if it's possible | |
117 | */ | |
118 | if (elv_rq_merge_ok(__rq, bio)) { | |
119 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
120 | ret = ELEVATOR_BACK_MERGE; | |
121 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
122 | ret = ELEVATOR_FRONT_MERGE; | |
123 | } | |
124 | ||
125 | return ret; | |
126 | } | |
1da177e4 | 127 | |
1da177e4 LT |
128 | static struct elevator_type *elevator_find(const char *name) |
129 | { | |
a22b169d | 130 | struct elevator_type *e; |
1da177e4 | 131 | |
70cee26e | 132 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
133 | if (!strcmp(e->elevator_name, name)) |
134 | return e; | |
1da177e4 | 135 | } |
1da177e4 | 136 | |
a22b169d | 137 | return NULL; |
1da177e4 LT |
138 | } |
139 | ||
140 | static void elevator_put(struct elevator_type *e) | |
141 | { | |
142 | module_put(e->elevator_owner); | |
143 | } | |
144 | ||
145 | static struct elevator_type *elevator_get(const char *name) | |
146 | { | |
2824bc93 | 147 | struct elevator_type *e; |
1da177e4 | 148 | |
2a12dcd7 | 149 | spin_lock(&elv_list_lock); |
2824bc93 TH |
150 | |
151 | e = elevator_find(name); | |
e1640949 JA |
152 | if (!e) { |
153 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
154 | ||
155 | spin_unlock(&elv_list_lock); | |
156 | ||
157 | if (!strcmp(name, "anticipatory")) | |
158 | sprintf(elv, "as-iosched"); | |
159 | else | |
160 | sprintf(elv, "%s-iosched", name); | |
161 | ||
e180f594 | 162 | request_module("%s", elv); |
e1640949 JA |
163 | spin_lock(&elv_list_lock); |
164 | e = elevator_find(name); | |
165 | } | |
166 | ||
2824bc93 TH |
167 | if (e && !try_module_get(e->elevator_owner)) |
168 | e = NULL; | |
169 | ||
2a12dcd7 | 170 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
171 | |
172 | return e; | |
173 | } | |
174 | ||
165125e1 JA |
175 | static void *elevator_init_queue(struct request_queue *q, |
176 | struct elevator_queue *eq) | |
1da177e4 | 177 | { |
bb37b94c | 178 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 179 | } |
1da177e4 | 180 | |
165125e1 | 181 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
182 | void *data) |
183 | { | |
1da177e4 | 184 | q->elevator = eq; |
bc1c1169 | 185 | eq->elevator_data = data; |
1da177e4 LT |
186 | } |
187 | ||
188 | static char chosen_elevator[16]; | |
189 | ||
5f003976 | 190 | static int __init elevator_setup(char *str) |
1da177e4 | 191 | { |
752a3b79 CE |
192 | /* |
193 | * Be backwards-compatible with previous kernels, so users | |
194 | * won't get the wrong elevator. | |
195 | */ | |
5f003976 | 196 | if (!strcmp(str, "as")) |
752a3b79 | 197 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 198 | else |
5f003976 | 199 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 200 | return 1; |
1da177e4 LT |
201 | } |
202 | ||
203 | __setup("elevator=", elevator_setup); | |
204 | ||
3d1ab40f AV |
205 | static struct kobj_type elv_ktype; |
206 | ||
b374d18a | 207 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 208 | struct elevator_type *e) |
3d1ab40f | 209 | { |
b374d18a | 210 | struct elevator_queue *eq; |
9817064b JA |
211 | int i; |
212 | ||
b374d18a | 213 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
214 | if (unlikely(!eq)) |
215 | goto err; | |
216 | ||
9817064b JA |
217 | eq->ops = &e->ops; |
218 | eq->elevator_type = e; | |
f9cb074b | 219 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
220 | mutex_init(&eq->sysfs_lock); |
221 | ||
b5deef90 JA |
222 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
223 | GFP_KERNEL, q->node); | |
9817064b JA |
224 | if (!eq->hash) |
225 | goto err; | |
226 | ||
227 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
228 | INIT_HLIST_HEAD(&eq->hash[i]); | |
229 | ||
3d1ab40f | 230 | return eq; |
9817064b JA |
231 | err: |
232 | kfree(eq); | |
233 | elevator_put(e); | |
234 | return NULL; | |
3d1ab40f AV |
235 | } |
236 | ||
237 | static void elevator_release(struct kobject *kobj) | |
238 | { | |
b374d18a | 239 | struct elevator_queue *e; |
9817064b | 240 | |
b374d18a | 241 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 242 | elevator_put(e->elevator_type); |
9817064b | 243 | kfree(e->hash); |
3d1ab40f AV |
244 | kfree(e); |
245 | } | |
246 | ||
165125e1 | 247 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
248 | { |
249 | struct elevator_type *e = NULL; | |
250 | struct elevator_queue *eq; | |
251 | int ret = 0; | |
bc1c1169 | 252 | void *data; |
1da177e4 | 253 | |
cb98fc8b TH |
254 | INIT_LIST_HEAD(&q->queue_head); |
255 | q->last_merge = NULL; | |
256 | q->end_sector = 0; | |
257 | q->boundary_rq = NULL; | |
cb98fc8b | 258 | |
4eb166d9 JA |
259 | if (name) { |
260 | e = elevator_get(name); | |
261 | if (!e) | |
262 | return -EINVAL; | |
263 | } | |
1da177e4 | 264 | |
4eb166d9 JA |
265 | if (!e && *chosen_elevator) { |
266 | e = elevator_get(chosen_elevator); | |
267 | if (!e) | |
268 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
269 | chosen_elevator); | |
270 | } | |
248d5ca5 | 271 | |
4eb166d9 JA |
272 | if (!e) { |
273 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
274 | if (!e) { | |
275 | printk(KERN_ERR | |
276 | "Default I/O scheduler not found. " \ | |
277 | "Using noop.\n"); | |
278 | e = elevator_get("noop"); | |
279 | } | |
5f003976 ND |
280 | } |
281 | ||
b5deef90 | 282 | eq = elevator_alloc(q, e); |
3d1ab40f | 283 | if (!eq) |
1da177e4 | 284 | return -ENOMEM; |
1da177e4 | 285 | |
bc1c1169 JA |
286 | data = elevator_init_queue(q, eq); |
287 | if (!data) { | |
3d1ab40f | 288 | kobject_put(&eq->kobj); |
bc1c1169 JA |
289 | return -ENOMEM; |
290 | } | |
1da177e4 | 291 | |
bc1c1169 | 292 | elevator_attach(q, eq, data); |
1da177e4 LT |
293 | return ret; |
294 | } | |
2e662b65 JA |
295 | EXPORT_SYMBOL(elevator_init); |
296 | ||
b374d18a | 297 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 298 | { |
3d1ab40f | 299 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
300 | if (e->ops->elevator_exit_fn) |
301 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
302 | e->ops = NULL; |
303 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 304 | |
3d1ab40f | 305 | kobject_put(&e->kobj); |
1da177e4 | 306 | } |
2e662b65 JA |
307 | EXPORT_SYMBOL(elevator_exit); |
308 | ||
165125e1 | 309 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 | 310 | { |
b374d18a | 311 | struct elevator_queue *e = q->elevator; |
cad97516 JA |
312 | |
313 | if (e->ops->elevator_activate_req_fn) | |
314 | e->ops->elevator_activate_req_fn(q, rq); | |
315 | } | |
316 | ||
165125e1 | 317 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 | 318 | { |
b374d18a | 319 | struct elevator_queue *e = q->elevator; |
cad97516 JA |
320 | |
321 | if (e->ops->elevator_deactivate_req_fn) | |
322 | e->ops->elevator_deactivate_req_fn(q, rq); | |
323 | } | |
324 | ||
9817064b JA |
325 | static inline void __elv_rqhash_del(struct request *rq) |
326 | { | |
327 | hlist_del_init(&rq->hash); | |
328 | } | |
329 | ||
165125e1 | 330 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
331 | { |
332 | if (ELV_ON_HASH(rq)) | |
333 | __elv_rqhash_del(rq); | |
334 | } | |
335 | ||
165125e1 | 336 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 337 | { |
b374d18a | 338 | struct elevator_queue *e = q->elevator; |
9817064b JA |
339 | |
340 | BUG_ON(ELV_ON_HASH(rq)); | |
341 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
342 | } | |
343 | ||
165125e1 | 344 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
345 | { |
346 | __elv_rqhash_del(rq); | |
347 | elv_rqhash_add(q, rq); | |
348 | } | |
349 | ||
165125e1 | 350 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 351 | { |
b374d18a | 352 | struct elevator_queue *e = q->elevator; |
9817064b JA |
353 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
354 | struct hlist_node *entry, *next; | |
355 | struct request *rq; | |
356 | ||
357 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
358 | BUG_ON(!ELV_ON_HASH(rq)); | |
359 | ||
360 | if (unlikely(!rq_mergeable(rq))) { | |
361 | __elv_rqhash_del(rq); | |
362 | continue; | |
363 | } | |
364 | ||
365 | if (rq_hash_key(rq) == offset) | |
366 | return rq; | |
367 | } | |
368 | ||
369 | return NULL; | |
370 | } | |
371 | ||
2e662b65 JA |
372 | /* |
373 | * RB-tree support functions for inserting/lookup/removal of requests | |
374 | * in a sorted RB tree. | |
375 | */ | |
376 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
377 | { | |
378 | struct rb_node **p = &root->rb_node; | |
379 | struct rb_node *parent = NULL; | |
380 | struct request *__rq; | |
381 | ||
382 | while (*p) { | |
383 | parent = *p; | |
384 | __rq = rb_entry(parent, struct request, rb_node); | |
385 | ||
386 | if (rq->sector < __rq->sector) | |
387 | p = &(*p)->rb_left; | |
388 | else if (rq->sector > __rq->sector) | |
389 | p = &(*p)->rb_right; | |
390 | else | |
391 | return __rq; | |
392 | } | |
393 | ||
394 | rb_link_node(&rq->rb_node, parent, p); | |
395 | rb_insert_color(&rq->rb_node, root); | |
396 | return NULL; | |
397 | } | |
2e662b65 JA |
398 | EXPORT_SYMBOL(elv_rb_add); |
399 | ||
400 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
401 | { | |
402 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
403 | rb_erase(&rq->rb_node, root); | |
404 | RB_CLEAR_NODE(&rq->rb_node); | |
405 | } | |
2e662b65 JA |
406 | EXPORT_SYMBOL(elv_rb_del); |
407 | ||
408 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
409 | { | |
410 | struct rb_node *n = root->rb_node; | |
411 | struct request *rq; | |
412 | ||
413 | while (n) { | |
414 | rq = rb_entry(n, struct request, rb_node); | |
415 | ||
416 | if (sector < rq->sector) | |
417 | n = n->rb_left; | |
418 | else if (sector > rq->sector) | |
419 | n = n->rb_right; | |
420 | else | |
421 | return rq; | |
422 | } | |
423 | ||
424 | return NULL; | |
425 | } | |
2e662b65 JA |
426 | EXPORT_SYMBOL(elv_rb_find); |
427 | ||
8922e16c TH |
428 | /* |
429 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 430 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 431 | * specific elevators. |
8922e16c | 432 | */ |
165125e1 | 433 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
434 | { |
435 | sector_t boundary; | |
8922e16c | 436 | struct list_head *entry; |
4eb166d9 | 437 | int stop_flags; |
8922e16c | 438 | |
06b86245 TH |
439 | if (q->last_merge == rq) |
440 | q->last_merge = NULL; | |
9817064b JA |
441 | |
442 | elv_rqhash_del(q, rq); | |
443 | ||
15853af9 | 444 | q->nr_sorted--; |
06b86245 | 445 | |
1b47f531 | 446 | boundary = q->end_sector; |
4eb166d9 | 447 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
448 | list_for_each_prev(entry, &q->queue_head) { |
449 | struct request *pos = list_entry_rq(entry); | |
450 | ||
e17fc0a1 DW |
451 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
452 | break; | |
783660b2 JA |
453 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
454 | break; | |
4eb166d9 | 455 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
456 | break; |
457 | if (rq->sector >= boundary) { | |
458 | if (pos->sector < boundary) | |
459 | continue; | |
460 | } else { | |
461 | if (pos->sector >= boundary) | |
462 | break; | |
463 | } | |
464 | if (rq->sector >= pos->sector) | |
465 | break; | |
466 | } | |
467 | ||
468 | list_add(&rq->queuelist, entry); | |
469 | } | |
2e662b65 JA |
470 | EXPORT_SYMBOL(elv_dispatch_sort); |
471 | ||
9817064b | 472 | /* |
2e662b65 JA |
473 | * Insert rq into dispatch queue of q. Queue lock must be held on |
474 | * entry. rq is added to the back of the dispatch queue. To be used by | |
475 | * specific elevators. | |
9817064b JA |
476 | */ |
477 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
478 | { | |
479 | if (q->last_merge == rq) | |
480 | q->last_merge = NULL; | |
481 | ||
482 | elv_rqhash_del(q, rq); | |
483 | ||
484 | q->nr_sorted--; | |
485 | ||
486 | q->end_sector = rq_end_sector(rq); | |
487 | q->boundary_rq = rq; | |
488 | list_add_tail(&rq->queuelist, &q->queue_head); | |
489 | } | |
2e662b65 JA |
490 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
491 | ||
165125e1 | 492 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 493 | { |
b374d18a | 494 | struct elevator_queue *e = q->elevator; |
9817064b | 495 | struct request *__rq; |
06b86245 TH |
496 | int ret; |
497 | ||
9817064b JA |
498 | /* |
499 | * First try one-hit cache. | |
500 | */ | |
06b86245 TH |
501 | if (q->last_merge) { |
502 | ret = elv_try_merge(q->last_merge, bio); | |
503 | if (ret != ELEVATOR_NO_MERGE) { | |
504 | *req = q->last_merge; | |
505 | return ret; | |
506 | } | |
507 | } | |
1da177e4 | 508 | |
ac9fafa1 AB |
509 | if (blk_queue_nomerges(q)) |
510 | return ELEVATOR_NO_MERGE; | |
511 | ||
9817064b JA |
512 | /* |
513 | * See if our hash lookup can find a potential backmerge. | |
514 | */ | |
515 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
516 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
517 | *req = __rq; | |
518 | return ELEVATOR_BACK_MERGE; | |
519 | } | |
520 | ||
1da177e4 LT |
521 | if (e->ops->elevator_merge_fn) |
522 | return e->ops->elevator_merge_fn(q, req, bio); | |
523 | ||
524 | return ELEVATOR_NO_MERGE; | |
525 | } | |
526 | ||
165125e1 | 527 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 528 | { |
b374d18a | 529 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
530 | |
531 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 532 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 533 | |
2e662b65 JA |
534 | if (type == ELEVATOR_BACK_MERGE) |
535 | elv_rqhash_reposition(q, rq); | |
9817064b | 536 | |
06b86245 | 537 | q->last_merge = rq; |
1da177e4 LT |
538 | } |
539 | ||
165125e1 | 540 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
541 | struct request *next) |
542 | { | |
b374d18a | 543 | struct elevator_queue *e = q->elevator; |
1da177e4 | 544 | |
1da177e4 LT |
545 | if (e->ops->elevator_merge_req_fn) |
546 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 547 | |
9817064b JA |
548 | elv_rqhash_reposition(q, rq); |
549 | elv_rqhash_del(q, next); | |
550 | ||
551 | q->nr_sorted--; | |
06b86245 | 552 | q->last_merge = rq; |
1da177e4 LT |
553 | } |
554 | ||
165125e1 | 555 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 556 | { |
1da177e4 LT |
557 | /* |
558 | * it already went through dequeue, we need to decrement the | |
559 | * in_flight count again | |
560 | */ | |
8922e16c | 561 | if (blk_account_rq(rq)) { |
1da177e4 | 562 | q->in_flight--; |
cad97516 JA |
563 | if (blk_sorted_rq(rq)) |
564 | elv_deactivate_rq(q, rq); | |
8922e16c | 565 | } |
1da177e4 | 566 | |
4aff5e23 | 567 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 568 | |
30e9656c | 569 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
570 | } |
571 | ||
26308eab | 572 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
573 | { |
574 | static int printed; | |
575 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
576 | ; | |
577 | if (q->nr_sorted == 0) | |
578 | return; | |
579 | if (printed++ < 10) { | |
580 | printk(KERN_ERR "%s: forced dispatching is broken " | |
581 | "(nr_sorted=%u), please report this\n", | |
582 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
583 | } | |
584 | } | |
585 | ||
6c7e8cee JA |
586 | /* |
587 | * Call with queue lock held, interrupts disabled | |
588 | */ | |
f600abe2 | 589 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee JA |
590 | { |
591 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); | |
592 | ||
593 | /* | |
594 | * make sure we don't have any requests in flight | |
595 | */ | |
596 | elv_drain_elevator(q); | |
597 | while (q->rq.elvpriv) { | |
598 | blk_start_queueing(q); | |
599 | spin_unlock_irq(q->queue_lock); | |
600 | msleep(10); | |
601 | spin_lock_irq(q->queue_lock); | |
602 | elv_drain_elevator(q); | |
603 | } | |
604 | } | |
605 | ||
f600abe2 | 606 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee JA |
607 | { |
608 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
609 | } | |
610 | ||
165125e1 | 611 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 612 | { |
797e7dbb TH |
613 | struct list_head *pos; |
614 | unsigned ordseq; | |
dac07ec1 | 615 | int unplug_it = 1; |
797e7dbb | 616 | |
5f3ea37c | 617 | trace_block_rq_insert(q, rq); |
2056a782 | 618 | |
1da177e4 LT |
619 | rq->q = q; |
620 | ||
8922e16c TH |
621 | switch (where) { |
622 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 623 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
624 | |
625 | list_add(&rq->queuelist, &q->queue_head); | |
626 | break; | |
627 | ||
628 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 629 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 630 | elv_drain_elevator(q); |
8922e16c TH |
631 | list_add_tail(&rq->queuelist, &q->queue_head); |
632 | /* | |
633 | * We kick the queue here for the following reasons. | |
634 | * - The elevator might have returned NULL previously | |
635 | * to delay requests and returned them now. As the | |
636 | * queue wasn't empty before this request, ll_rw_blk | |
637 | * won't run the queue on return, resulting in hang. | |
638 | * - Usually, back inserted requests won't be merged | |
639 | * with anything. There's no point in delaying queue | |
640 | * processing. | |
641 | */ | |
642 | blk_remove_plug(q); | |
80a4b58e | 643 | blk_start_queueing(q); |
8922e16c TH |
644 | break; |
645 | ||
646 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 647 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 648 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 649 | q->nr_sorted++; |
9817064b JA |
650 | if (rq_mergeable(rq)) { |
651 | elv_rqhash_add(q, rq); | |
652 | if (!q->last_merge) | |
653 | q->last_merge = rq; | |
654 | } | |
655 | ||
ca23509f TH |
656 | /* |
657 | * Some ioscheds (cfq) run q->request_fn directly, so | |
658 | * rq cannot be accessed after calling | |
659 | * elevator_add_req_fn. | |
660 | */ | |
661 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
662 | break; |
663 | ||
797e7dbb TH |
664 | case ELEVATOR_INSERT_REQUEUE: |
665 | /* | |
666 | * If ordered flush isn't in progress, we do front | |
667 | * insertion; otherwise, requests should be requeued | |
668 | * in ordseq order. | |
669 | */ | |
4aff5e23 | 670 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 671 | |
95543179 LV |
672 | /* |
673 | * Most requeues happen because of a busy condition, | |
674 | * don't force unplug of the queue for that case. | |
675 | */ | |
676 | unplug_it = 0; | |
677 | ||
797e7dbb TH |
678 | if (q->ordseq == 0) { |
679 | list_add(&rq->queuelist, &q->queue_head); | |
680 | break; | |
681 | } | |
682 | ||
683 | ordseq = blk_ordered_req_seq(rq); | |
684 | ||
685 | list_for_each(pos, &q->queue_head) { | |
686 | struct request *pos_rq = list_entry_rq(pos); | |
687 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
688 | break; | |
689 | } | |
690 | ||
691 | list_add_tail(&rq->queuelist, pos); | |
692 | break; | |
693 | ||
8922e16c TH |
694 | default: |
695 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 696 | __func__, where); |
8922e16c TH |
697 | BUG(); |
698 | } | |
699 | ||
dac07ec1 | 700 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 701 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
8922e16c TH |
702 | - q->in_flight; |
703 | ||
704 | if (nrq >= q->unplug_thresh) | |
705 | __generic_unplug_device(q); | |
706 | } | |
1da177e4 LT |
707 | } |
708 | ||
165125e1 | 709 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
710 | int plug) |
711 | { | |
712 | if (q->ordcolor) | |
4aff5e23 | 713 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 714 | |
4aff5e23 | 715 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
716 | /* |
717 | * toggle ordered color | |
718 | */ | |
719 | if (blk_barrier_rq(rq)) | |
720 | q->ordcolor ^= 1; | |
721 | ||
722 | /* | |
723 | * barriers implicitly indicate back insertion | |
724 | */ | |
725 | if (where == ELEVATOR_INSERT_SORT) | |
726 | where = ELEVATOR_INSERT_BACK; | |
727 | ||
728 | /* | |
729 | * this request is scheduling boundary, update | |
730 | * end_sector | |
731 | */ | |
e17fc0a1 | 732 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
733 | q->end_sector = rq_end_sector(rq); |
734 | q->boundary_rq = rq; | |
735 | } | |
4eb166d9 JA |
736 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
737 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
738 | where = ELEVATOR_INSERT_BACK; |
739 | ||
740 | if (plug) | |
741 | blk_plug_device(q); | |
742 | ||
743 | elv_insert(q, rq, where); | |
744 | } | |
2e662b65 JA |
745 | EXPORT_SYMBOL(__elv_add_request); |
746 | ||
165125e1 | 747 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
748 | int plug) |
749 | { | |
750 | unsigned long flags; | |
751 | ||
752 | spin_lock_irqsave(q->queue_lock, flags); | |
753 | __elv_add_request(q, rq, where, plug); | |
754 | spin_unlock_irqrestore(q->queue_lock, flags); | |
755 | } | |
2e662b65 JA |
756 | EXPORT_SYMBOL(elv_add_request); |
757 | ||
165125e1 | 758 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 759 | { |
8922e16c TH |
760 | struct request *rq; |
761 | ||
797e7dbb TH |
762 | while (1) { |
763 | while (!list_empty(&q->queue_head)) { | |
764 | rq = list_entry_rq(q->queue_head.next); | |
765 | if (blk_do_ordered(q, &rq)) | |
766 | return rq; | |
767 | } | |
1da177e4 | 768 | |
797e7dbb TH |
769 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
770 | return NULL; | |
1da177e4 | 771 | } |
1da177e4 LT |
772 | } |
773 | ||
165125e1 | 774 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
775 | { |
776 | struct request *rq; | |
777 | int ret; | |
778 | ||
779 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 780 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
781 | /* |
782 | * This is the first time the device driver | |
783 | * sees this request (possibly after | |
784 | * requeueing). Notify IO scheduler. | |
785 | */ | |
cad97516 JA |
786 | if (blk_sorted_rq(rq)) |
787 | elv_activate_rq(q, rq); | |
1da177e4 | 788 | |
8922e16c TH |
789 | /* |
790 | * just mark as started even if we don't start | |
791 | * it, a request that has been delayed should | |
792 | * not be passed by new incoming requests | |
793 | */ | |
4aff5e23 | 794 | rq->cmd_flags |= REQ_STARTED; |
5f3ea37c | 795 | trace_block_rq_issue(q, rq); |
8922e16c | 796 | } |
1da177e4 | 797 | |
8922e16c | 798 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 799 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
800 | q->boundary_rq = NULL; |
801 | } | |
1da177e4 | 802 | |
fa0ccd83 JB |
803 | if (rq->cmd_flags & REQ_DONTPREP) |
804 | break; | |
805 | ||
806 | if (q->dma_drain_size && rq->data_len) { | |
807 | /* | |
808 | * make sure space for the drain appears we | |
809 | * know we can do this because max_hw_segments | |
810 | * has been adjusted to be one fewer than the | |
811 | * device can handle | |
812 | */ | |
813 | rq->nr_phys_segments++; | |
fa0ccd83 JB |
814 | } |
815 | ||
816 | if (!q->prep_rq_fn) | |
1da177e4 LT |
817 | break; |
818 | ||
819 | ret = q->prep_rq_fn(q, rq); | |
820 | if (ret == BLKPREP_OK) { | |
821 | break; | |
822 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
823 | /* |
824 | * the request may have been (partially) prepped. | |
825 | * we need to keep this request in the front to | |
8922e16c TH |
826 | * avoid resource deadlock. REQ_STARTED will |
827 | * prevent other fs requests from passing this one. | |
2e759cd4 | 828 | */ |
fa0ccd83 JB |
829 | if (q->dma_drain_size && rq->data_len && |
830 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
831 | /* | |
832 | * remove the space for the drain we added | |
833 | * so that we don't add it again | |
834 | */ | |
835 | --rq->nr_phys_segments; | |
fa0ccd83 JB |
836 | } |
837 | ||
1da177e4 LT |
838 | rq = NULL; |
839 | break; | |
840 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 841 | rq->cmd_flags |= REQ_QUIET; |
99cd3386 | 842 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
1da177e4 | 843 | } else { |
24c03d47 | 844 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1da177e4 LT |
845 | break; |
846 | } | |
847 | } | |
848 | ||
849 | return rq; | |
850 | } | |
2e662b65 JA |
851 | EXPORT_SYMBOL(elv_next_request); |
852 | ||
165125e1 | 853 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 854 | { |
8922e16c | 855 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 856 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
857 | |
858 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
859 | |
860 | /* | |
861 | * the time frame between a request being removed from the lists | |
862 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 863 | * the driver side. |
1da177e4 LT |
864 | */ |
865 | if (blk_account_rq(rq)) | |
866 | q->in_flight++; | |
1da177e4 | 867 | } |
2e662b65 | 868 | |
165125e1 | 869 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 870 | { |
b374d18a | 871 | struct elevator_queue *e = q->elevator; |
1da177e4 | 872 | |
8922e16c TH |
873 | if (!list_empty(&q->queue_head)) |
874 | return 0; | |
875 | ||
1da177e4 LT |
876 | if (e->ops->elevator_queue_empty_fn) |
877 | return e->ops->elevator_queue_empty_fn(q); | |
878 | ||
8922e16c | 879 | return 1; |
1da177e4 | 880 | } |
2e662b65 JA |
881 | EXPORT_SYMBOL(elv_queue_empty); |
882 | ||
165125e1 | 883 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 884 | { |
b374d18a | 885 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
886 | |
887 | if (e->ops->elevator_latter_req_fn) | |
888 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
889 | return NULL; |
890 | } | |
891 | ||
165125e1 | 892 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 893 | { |
b374d18a | 894 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
895 | |
896 | if (e->ops->elevator_former_req_fn) | |
897 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
898 | return NULL; |
899 | } | |
900 | ||
165125e1 | 901 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 902 | { |
b374d18a | 903 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
904 | |
905 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 906 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
907 | |
908 | rq->elevator_private = NULL; | |
909 | return 0; | |
910 | } | |
911 | ||
165125e1 | 912 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 913 | { |
b374d18a | 914 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
915 | |
916 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 917 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
918 | } |
919 | ||
165125e1 | 920 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 921 | { |
b374d18a | 922 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
923 | |
924 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 925 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
926 | |
927 | return ELV_MQUEUE_MAY; | |
928 | } | |
929 | ||
11914a53 MA |
930 | void elv_abort_queue(struct request_queue *q) |
931 | { | |
932 | struct request *rq; | |
933 | ||
934 | while (!list_empty(&q->queue_head)) { | |
935 | rq = list_entry_rq(q->queue_head.next); | |
936 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 937 | trace_block_rq_abort(q, rq); |
99cd3386 | 938 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
11914a53 MA |
939 | } |
940 | } | |
941 | EXPORT_SYMBOL(elv_abort_queue); | |
942 | ||
165125e1 | 943 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 944 | { |
b374d18a | 945 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
946 | |
947 | /* | |
948 | * request is released from the driver, io must be done | |
949 | */ | |
8922e16c | 950 | if (blk_account_rq(rq)) { |
1da177e4 | 951 | q->in_flight--; |
1bc691d3 TH |
952 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
953 | e->ops->elevator_completed_req_fn(q, rq); | |
954 | } | |
797e7dbb | 955 | |
1bc691d3 TH |
956 | /* |
957 | * Check if the queue is waiting for fs requests to be | |
958 | * drained for flush sequence. | |
959 | */ | |
960 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
961 | struct request *next = NULL; |
962 | ||
963 | if (!list_empty(&q->queue_head)) | |
964 | next = list_entry_rq(q->queue_head.next); | |
965 | ||
966 | if (!q->in_flight && | |
797e7dbb | 967 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 968 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 969 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
80a4b58e | 970 | blk_start_queueing(q); |
797e7dbb | 971 | } |
8922e16c | 972 | } |
1da177e4 LT |
973 | } |
974 | ||
3d1ab40f AV |
975 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
976 | ||
977 | static ssize_t | |
978 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 979 | { |
3d1ab40f | 980 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 981 | struct elevator_queue *e; |
3d1ab40f AV |
982 | ssize_t error; |
983 | ||
984 | if (!entry->show) | |
985 | return -EIO; | |
986 | ||
b374d18a | 987 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
988 | mutex_lock(&e->sysfs_lock); |
989 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
990 | mutex_unlock(&e->sysfs_lock); | |
991 | return error; | |
992 | } | |
1da177e4 | 993 | |
3d1ab40f AV |
994 | static ssize_t |
995 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
996 | const char *page, size_t length) | |
997 | { | |
3d1ab40f | 998 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 999 | struct elevator_queue *e; |
3d1ab40f | 1000 | ssize_t error; |
1da177e4 | 1001 | |
3d1ab40f AV |
1002 | if (!entry->store) |
1003 | return -EIO; | |
1da177e4 | 1004 | |
b374d18a | 1005 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
1006 | mutex_lock(&e->sysfs_lock); |
1007 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
1008 | mutex_unlock(&e->sysfs_lock); | |
1009 | return error; | |
1010 | } | |
1011 | ||
1012 | static struct sysfs_ops elv_sysfs_ops = { | |
1013 | .show = elv_attr_show, | |
1014 | .store = elv_attr_store, | |
1015 | }; | |
1016 | ||
1017 | static struct kobj_type elv_ktype = { | |
1018 | .sysfs_ops = &elv_sysfs_ops, | |
1019 | .release = elevator_release, | |
1020 | }; | |
1021 | ||
1022 | int elv_register_queue(struct request_queue *q) | |
1023 | { | |
b374d18a | 1024 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
1025 | int error; |
1026 | ||
b2d6db58 | 1027 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 1028 | if (!error) { |
e572ec7e | 1029 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 1030 | if (attr) { |
e572ec7e AV |
1031 | while (attr->attr.name) { |
1032 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 1033 | break; |
e572ec7e | 1034 | attr++; |
3d1ab40f AV |
1035 | } |
1036 | } | |
1037 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
1038 | } | |
1039 | return error; | |
1da177e4 LT |
1040 | } |
1041 | ||
b374d18a | 1042 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
1043 | { |
1044 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
1045 | kobject_del(&e->kobj); | |
1046 | } | |
1047 | ||
1da177e4 LT |
1048 | void elv_unregister_queue(struct request_queue *q) |
1049 | { | |
bc1c1169 JA |
1050 | if (q) |
1051 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
1052 | } |
1053 | ||
2fdd82bd | 1054 | void elv_register(struct elevator_type *e) |
1da177e4 | 1055 | { |
1ffb96c5 | 1056 | char *def = ""; |
2a12dcd7 JA |
1057 | |
1058 | spin_lock(&elv_list_lock); | |
ce524497 | 1059 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 1060 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 1061 | spin_unlock(&elv_list_lock); |
1da177e4 | 1062 | |
5f003976 ND |
1063 | if (!strcmp(e->elevator_name, chosen_elevator) || |
1064 | (!*chosen_elevator && | |
1065 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
1066 | def = " (default)"; |
1067 | ||
4eb166d9 JA |
1068 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1069 | def); | |
1da177e4 LT |
1070 | } |
1071 | EXPORT_SYMBOL_GPL(elv_register); | |
1072 | ||
1073 | void elv_unregister(struct elevator_type *e) | |
1074 | { | |
83521d3e CH |
1075 | struct task_struct *g, *p; |
1076 | ||
1077 | /* | |
1078 | * Iterate every thread in the process to remove the io contexts. | |
1079 | */ | |
e17a9489 AV |
1080 | if (e->ops.trim) { |
1081 | read_lock(&tasklist_lock); | |
1082 | do_each_thread(g, p) { | |
1083 | task_lock(p); | |
2d8f6131 ON |
1084 | if (p->io_context) |
1085 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1086 | task_unlock(p); |
1087 | } while_each_thread(g, p); | |
1088 | read_unlock(&tasklist_lock); | |
1089 | } | |
83521d3e | 1090 | |
2a12dcd7 | 1091 | spin_lock(&elv_list_lock); |
1da177e4 | 1092 | list_del_init(&e->list); |
2a12dcd7 | 1093 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1094 | } |
1095 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1096 | ||
1097 | /* | |
1098 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1099 | * we don't free the old io scheduler, before we have allocated what we | |
1100 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1101 | * one, if the new one fails init for some reason. |
1da177e4 | 1102 | */ |
165125e1 | 1103 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1104 | { |
b374d18a | 1105 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 1106 | void *data; |
1da177e4 | 1107 | |
cb98fc8b TH |
1108 | /* |
1109 | * Allocate new elevator | |
1110 | */ | |
b5deef90 | 1111 | e = elevator_alloc(q, new_e); |
1da177e4 | 1112 | if (!e) |
3d1ab40f | 1113 | return 0; |
1da177e4 | 1114 | |
bc1c1169 JA |
1115 | data = elevator_init_queue(q, e); |
1116 | if (!data) { | |
1117 | kobject_put(&e->kobj); | |
1118 | return 0; | |
1119 | } | |
1120 | ||
1da177e4 | 1121 | /* |
cb98fc8b | 1122 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1123 | */ |
cb98fc8b | 1124 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1125 | elv_quiesce_start(q); |
cb98fc8b | 1126 | |
1da177e4 | 1127 | /* |
bc1c1169 | 1128 | * Remember old elevator. |
1da177e4 | 1129 | */ |
1da177e4 LT |
1130 | old_elevator = q->elevator; |
1131 | ||
1da177e4 LT |
1132 | /* |
1133 | * attach and start new elevator | |
1134 | */ | |
bc1c1169 JA |
1135 | elevator_attach(q, e, data); |
1136 | ||
1137 | spin_unlock_irq(q->queue_lock); | |
1138 | ||
1139 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1140 | |
1141 | if (elv_register_queue(q)) | |
1142 | goto fail_register; | |
1143 | ||
1144 | /* | |
cb98fc8b | 1145 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1146 | */ |
1147 | elevator_exit(old_elevator); | |
75ad23bc | 1148 | spin_lock_irq(q->queue_lock); |
f600abe2 | 1149 | elv_quiesce_end(q); |
75ad23bc NP |
1150 | spin_unlock_irq(q->queue_lock); |
1151 | ||
4722dc52 AB |
1152 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1153 | ||
3d1ab40f | 1154 | return 1; |
1da177e4 LT |
1155 | |
1156 | fail_register: | |
1157 | /* | |
1158 | * switch failed, exit the new io scheduler and reattach the old | |
1159 | * one again (along with re-adding the sysfs dir) | |
1160 | */ | |
1161 | elevator_exit(e); | |
1da177e4 LT |
1162 | q->elevator = old_elevator; |
1163 | elv_register_queue(q); | |
75ad23bc NP |
1164 | |
1165 | spin_lock_irq(q->queue_lock); | |
1166 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1167 | spin_unlock_irq(q->queue_lock); | |
1168 | ||
3d1ab40f | 1169 | return 0; |
1da177e4 LT |
1170 | } |
1171 | ||
165125e1 JA |
1172 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1173 | size_t count) | |
1da177e4 LT |
1174 | { |
1175 | char elevator_name[ELV_NAME_MAX]; | |
1176 | struct elevator_type *e; | |
1177 | ||
ee2e992c LZ |
1178 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1179 | strstrip(elevator_name); | |
1da177e4 LT |
1180 | |
1181 | e = elevator_get(elevator_name); | |
1182 | if (!e) { | |
1183 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1184 | return -EINVAL; | |
1185 | } | |
1186 | ||
2ca7d93b ND |
1187 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1188 | elevator_put(e); | |
1da177e4 | 1189 | return count; |
2ca7d93b | 1190 | } |
1da177e4 | 1191 | |
3d1ab40f | 1192 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1193 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1194 | elevator_name); | |
1da177e4 LT |
1195 | return count; |
1196 | } | |
1197 | ||
165125e1 | 1198 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1199 | { |
b374d18a | 1200 | struct elevator_queue *e = q->elevator; |
1da177e4 | 1201 | struct elevator_type *elv = e->elevator_type; |
70cee26e | 1202 | struct elevator_type *__e; |
1da177e4 LT |
1203 | int len = 0; |
1204 | ||
2a12dcd7 | 1205 | spin_lock(&elv_list_lock); |
70cee26e | 1206 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1207 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1208 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1209 | else | |
1210 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1211 | } | |
2a12dcd7 | 1212 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1213 | |
1214 | len += sprintf(len+name, "\n"); | |
1215 | return len; | |
1216 | } | |
1217 | ||
165125e1 JA |
1218 | struct request *elv_rb_former_request(struct request_queue *q, |
1219 | struct request *rq) | |
2e662b65 JA |
1220 | { |
1221 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1222 | ||
1223 | if (rbprev) | |
1224 | return rb_entry_rq(rbprev); | |
1225 | ||
1226 | return NULL; | |
1227 | } | |
2e662b65 JA |
1228 | EXPORT_SYMBOL(elv_rb_former_request); |
1229 | ||
165125e1 JA |
1230 | struct request *elv_rb_latter_request(struct request_queue *q, |
1231 | struct request *rq) | |
2e662b65 JA |
1232 | { |
1233 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1234 | ||
1235 | if (rbnext) | |
1236 | return rb_entry_rq(rbnext); | |
1237 | ||
1238 | return NULL; | |
1239 | } | |
2e662b65 | 1240 | EXPORT_SYMBOL(elv_rb_latter_request); |