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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> |
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 | ||
0bfc2455 IM |
45 | DEFINE_TRACE(block_rq_abort); |
46 | ||
9817064b JA |
47 | /* |
48 | * Merge hash stuff. | |
49 | */ | |
50 | static const int elv_hash_shift = 6; | |
51 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
52 | #define ELV_HASH_FN(sec) \ |
53 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
54 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
55 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
56 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
57 | ||
0bfc2455 IM |
58 | DEFINE_TRACE(block_rq_insert); |
59 | DEFINE_TRACE(block_rq_issue); | |
60 | ||
da775265 JA |
61 | /* |
62 | * Query io scheduler to see if the current process issuing bio may be | |
63 | * merged with rq. | |
64 | */ | |
65 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
66 | { | |
165125e1 | 67 | struct request_queue *q = rq->q; |
b374d18a | 68 | struct elevator_queue *e = q->elevator; |
da775265 JA |
69 | |
70 | if (e->ops->elevator_allow_merge_fn) | |
71 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
72 | ||
73 | return 1; | |
74 | } | |
75 | ||
1da177e4 LT |
76 | /* |
77 | * can we safely merge with this request? | |
78 | */ | |
72ed0bf6 | 79 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
80 | { |
81 | if (!rq_mergeable(rq)) | |
82 | return 0; | |
83 | ||
e17fc0a1 DW |
84 | /* |
85 | * Don't merge file system requests and discard requests | |
86 | */ | |
87 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
88 | return 0; | |
89 | ||
1da177e4 LT |
90 | /* |
91 | * different data direction or already started, don't merge | |
92 | */ | |
93 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
94 | return 0; | |
95 | ||
96 | /* | |
da775265 | 97 | * must be same device and not a special request |
1da177e4 | 98 | */ |
bb4067e3 | 99 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
100 | return 0; |
101 | ||
7ba1ba12 MP |
102 | /* |
103 | * only merge integrity protected bio into ditto rq | |
104 | */ | |
105 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
106 | return 0; | |
107 | ||
da775265 JA |
108 | if (!elv_iosched_allow_merge(rq, bio)) |
109 | return 0; | |
1da177e4 | 110 | |
da775265 | 111 | return 1; |
1da177e4 LT |
112 | } |
113 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
114 | ||
769db45b | 115 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
116 | { |
117 | int ret = ELEVATOR_NO_MERGE; | |
118 | ||
119 | /* | |
120 | * we can merge and sequence is ok, check if it's possible | |
121 | */ | |
122 | if (elv_rq_merge_ok(__rq, bio)) { | |
123 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
124 | ret = ELEVATOR_BACK_MERGE; | |
125 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
126 | ret = ELEVATOR_FRONT_MERGE; | |
127 | } | |
128 | ||
129 | return ret; | |
130 | } | |
1da177e4 | 131 | |
1da177e4 LT |
132 | static struct elevator_type *elevator_find(const char *name) |
133 | { | |
a22b169d | 134 | struct elevator_type *e; |
1da177e4 | 135 | |
70cee26e | 136 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
137 | if (!strcmp(e->elevator_name, name)) |
138 | return e; | |
1da177e4 | 139 | } |
1da177e4 | 140 | |
a22b169d | 141 | return NULL; |
1da177e4 LT |
142 | } |
143 | ||
144 | static void elevator_put(struct elevator_type *e) | |
145 | { | |
146 | module_put(e->elevator_owner); | |
147 | } | |
148 | ||
149 | static struct elevator_type *elevator_get(const char *name) | |
150 | { | |
2824bc93 | 151 | struct elevator_type *e; |
1da177e4 | 152 | |
2a12dcd7 | 153 | spin_lock(&elv_list_lock); |
2824bc93 TH |
154 | |
155 | e = elevator_find(name); | |
e1640949 JA |
156 | if (!e) { |
157 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
158 | ||
159 | spin_unlock(&elv_list_lock); | |
160 | ||
161 | if (!strcmp(name, "anticipatory")) | |
162 | sprintf(elv, "as-iosched"); | |
163 | else | |
164 | sprintf(elv, "%s-iosched", name); | |
165 | ||
e180f594 | 166 | request_module("%s", elv); |
e1640949 JA |
167 | spin_lock(&elv_list_lock); |
168 | e = elevator_find(name); | |
169 | } | |
170 | ||
2824bc93 TH |
171 | if (e && !try_module_get(e->elevator_owner)) |
172 | e = NULL; | |
173 | ||
2a12dcd7 | 174 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
175 | |
176 | return e; | |
177 | } | |
178 | ||
165125e1 JA |
179 | static void *elevator_init_queue(struct request_queue *q, |
180 | struct elevator_queue *eq) | |
1da177e4 | 181 | { |
bb37b94c | 182 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 183 | } |
1da177e4 | 184 | |
165125e1 | 185 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
186 | void *data) |
187 | { | |
1da177e4 | 188 | q->elevator = eq; |
bc1c1169 | 189 | eq->elevator_data = data; |
1da177e4 LT |
190 | } |
191 | ||
192 | static char chosen_elevator[16]; | |
193 | ||
5f003976 | 194 | static int __init elevator_setup(char *str) |
1da177e4 | 195 | { |
752a3b79 CE |
196 | /* |
197 | * Be backwards-compatible with previous kernels, so users | |
198 | * won't get the wrong elevator. | |
199 | */ | |
5f003976 | 200 | if (!strcmp(str, "as")) |
752a3b79 | 201 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 202 | else |
5f003976 | 203 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 204 | return 1; |
1da177e4 LT |
205 | } |
206 | ||
207 | __setup("elevator=", elevator_setup); | |
208 | ||
3d1ab40f AV |
209 | static struct kobj_type elv_ktype; |
210 | ||
b374d18a | 211 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 212 | struct elevator_type *e) |
3d1ab40f | 213 | { |
b374d18a | 214 | struct elevator_queue *eq; |
9817064b JA |
215 | int i; |
216 | ||
b374d18a | 217 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
218 | if (unlikely(!eq)) |
219 | goto err; | |
220 | ||
9817064b JA |
221 | eq->ops = &e->ops; |
222 | eq->elevator_type = e; | |
f9cb074b | 223 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
224 | mutex_init(&eq->sysfs_lock); |
225 | ||
b5deef90 JA |
226 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
227 | GFP_KERNEL, q->node); | |
9817064b JA |
228 | if (!eq->hash) |
229 | goto err; | |
230 | ||
231 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
232 | INIT_HLIST_HEAD(&eq->hash[i]); | |
233 | ||
3d1ab40f | 234 | return eq; |
9817064b JA |
235 | err: |
236 | kfree(eq); | |
237 | elevator_put(e); | |
238 | return NULL; | |
3d1ab40f AV |
239 | } |
240 | ||
241 | static void elevator_release(struct kobject *kobj) | |
242 | { | |
b374d18a | 243 | struct elevator_queue *e; |
9817064b | 244 | |
b374d18a | 245 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 246 | elevator_put(e->elevator_type); |
9817064b | 247 | kfree(e->hash); |
3d1ab40f AV |
248 | kfree(e); |
249 | } | |
250 | ||
165125e1 | 251 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
252 | { |
253 | struct elevator_type *e = NULL; | |
254 | struct elevator_queue *eq; | |
255 | int ret = 0; | |
bc1c1169 | 256 | void *data; |
1da177e4 | 257 | |
cb98fc8b TH |
258 | INIT_LIST_HEAD(&q->queue_head); |
259 | q->last_merge = NULL; | |
260 | q->end_sector = 0; | |
261 | q->boundary_rq = NULL; | |
cb98fc8b | 262 | |
4eb166d9 JA |
263 | if (name) { |
264 | e = elevator_get(name); | |
265 | if (!e) | |
266 | return -EINVAL; | |
267 | } | |
1da177e4 | 268 | |
4eb166d9 JA |
269 | if (!e && *chosen_elevator) { |
270 | e = elevator_get(chosen_elevator); | |
271 | if (!e) | |
272 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
273 | chosen_elevator); | |
274 | } | |
248d5ca5 | 275 | |
4eb166d9 JA |
276 | if (!e) { |
277 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
278 | if (!e) { | |
279 | printk(KERN_ERR | |
280 | "Default I/O scheduler not found. " \ | |
281 | "Using noop.\n"); | |
282 | e = elevator_get("noop"); | |
283 | } | |
5f003976 ND |
284 | } |
285 | ||
b5deef90 | 286 | eq = elevator_alloc(q, e); |
3d1ab40f | 287 | if (!eq) |
1da177e4 | 288 | return -ENOMEM; |
1da177e4 | 289 | |
bc1c1169 JA |
290 | data = elevator_init_queue(q, eq); |
291 | if (!data) { | |
3d1ab40f | 292 | kobject_put(&eq->kobj); |
bc1c1169 JA |
293 | return -ENOMEM; |
294 | } | |
1da177e4 | 295 | |
bc1c1169 | 296 | elevator_attach(q, eq, data); |
1da177e4 LT |
297 | return ret; |
298 | } | |
2e662b65 JA |
299 | EXPORT_SYMBOL(elevator_init); |
300 | ||
b374d18a | 301 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 302 | { |
3d1ab40f | 303 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
304 | if (e->ops->elevator_exit_fn) |
305 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
306 | e->ops = NULL; |
307 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 308 | |
3d1ab40f | 309 | kobject_put(&e->kobj); |
1da177e4 | 310 | } |
2e662b65 JA |
311 | EXPORT_SYMBOL(elevator_exit); |
312 | ||
165125e1 | 313 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 | 314 | { |
b374d18a | 315 | struct elevator_queue *e = q->elevator; |
cad97516 JA |
316 | |
317 | if (e->ops->elevator_activate_req_fn) | |
318 | e->ops->elevator_activate_req_fn(q, rq); | |
319 | } | |
320 | ||
165125e1 | 321 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 | 322 | { |
b374d18a | 323 | struct elevator_queue *e = q->elevator; |
cad97516 JA |
324 | |
325 | if (e->ops->elevator_deactivate_req_fn) | |
326 | e->ops->elevator_deactivate_req_fn(q, rq); | |
327 | } | |
328 | ||
9817064b JA |
329 | static inline void __elv_rqhash_del(struct request *rq) |
330 | { | |
331 | hlist_del_init(&rq->hash); | |
332 | } | |
333 | ||
165125e1 | 334 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
335 | { |
336 | if (ELV_ON_HASH(rq)) | |
337 | __elv_rqhash_del(rq); | |
338 | } | |
339 | ||
165125e1 | 340 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 341 | { |
b374d18a | 342 | struct elevator_queue *e = q->elevator; |
9817064b JA |
343 | |
344 | BUG_ON(ELV_ON_HASH(rq)); | |
345 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
346 | } | |
347 | ||
165125e1 | 348 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
349 | { |
350 | __elv_rqhash_del(rq); | |
351 | elv_rqhash_add(q, rq); | |
352 | } | |
353 | ||
165125e1 | 354 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 355 | { |
b374d18a | 356 | struct elevator_queue *e = q->elevator; |
9817064b JA |
357 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
358 | struct hlist_node *entry, *next; | |
359 | struct request *rq; | |
360 | ||
361 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
362 | BUG_ON(!ELV_ON_HASH(rq)); | |
363 | ||
364 | if (unlikely(!rq_mergeable(rq))) { | |
365 | __elv_rqhash_del(rq); | |
366 | continue; | |
367 | } | |
368 | ||
369 | if (rq_hash_key(rq) == offset) | |
370 | return rq; | |
371 | } | |
372 | ||
373 | return NULL; | |
374 | } | |
375 | ||
2e662b65 JA |
376 | /* |
377 | * RB-tree support functions for inserting/lookup/removal of requests | |
378 | * in a sorted RB tree. | |
379 | */ | |
380 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
381 | { | |
382 | struct rb_node **p = &root->rb_node; | |
383 | struct rb_node *parent = NULL; | |
384 | struct request *__rq; | |
385 | ||
386 | while (*p) { | |
387 | parent = *p; | |
388 | __rq = rb_entry(parent, struct request, rb_node); | |
389 | ||
390 | if (rq->sector < __rq->sector) | |
391 | p = &(*p)->rb_left; | |
392 | else if (rq->sector > __rq->sector) | |
393 | p = &(*p)->rb_right; | |
394 | else | |
395 | return __rq; | |
396 | } | |
397 | ||
398 | rb_link_node(&rq->rb_node, parent, p); | |
399 | rb_insert_color(&rq->rb_node, root); | |
400 | return NULL; | |
401 | } | |
2e662b65 JA |
402 | EXPORT_SYMBOL(elv_rb_add); |
403 | ||
404 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
405 | { | |
406 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
407 | rb_erase(&rq->rb_node, root); | |
408 | RB_CLEAR_NODE(&rq->rb_node); | |
409 | } | |
2e662b65 JA |
410 | EXPORT_SYMBOL(elv_rb_del); |
411 | ||
412 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
413 | { | |
414 | struct rb_node *n = root->rb_node; | |
415 | struct request *rq; | |
416 | ||
417 | while (n) { | |
418 | rq = rb_entry(n, struct request, rb_node); | |
419 | ||
420 | if (sector < rq->sector) | |
421 | n = n->rb_left; | |
422 | else if (sector > rq->sector) | |
423 | n = n->rb_right; | |
424 | else | |
425 | return rq; | |
426 | } | |
427 | ||
428 | return NULL; | |
429 | } | |
2e662b65 JA |
430 | EXPORT_SYMBOL(elv_rb_find); |
431 | ||
8922e16c TH |
432 | /* |
433 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 434 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 435 | * specific elevators. |
8922e16c | 436 | */ |
165125e1 | 437 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
438 | { |
439 | sector_t boundary; | |
8922e16c | 440 | struct list_head *entry; |
4eb166d9 | 441 | int stop_flags; |
8922e16c | 442 | |
06b86245 TH |
443 | if (q->last_merge == rq) |
444 | q->last_merge = NULL; | |
9817064b JA |
445 | |
446 | elv_rqhash_del(q, rq); | |
447 | ||
15853af9 | 448 | q->nr_sorted--; |
06b86245 | 449 | |
1b47f531 | 450 | boundary = q->end_sector; |
4eb166d9 | 451 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
452 | list_for_each_prev(entry, &q->queue_head) { |
453 | struct request *pos = list_entry_rq(entry); | |
454 | ||
e17fc0a1 DW |
455 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
456 | break; | |
783660b2 JA |
457 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
458 | break; | |
4eb166d9 | 459 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
460 | break; |
461 | if (rq->sector >= boundary) { | |
462 | if (pos->sector < boundary) | |
463 | continue; | |
464 | } else { | |
465 | if (pos->sector >= boundary) | |
466 | break; | |
467 | } | |
468 | if (rq->sector >= pos->sector) | |
469 | break; | |
470 | } | |
471 | ||
472 | list_add(&rq->queuelist, entry); | |
473 | } | |
2e662b65 JA |
474 | EXPORT_SYMBOL(elv_dispatch_sort); |
475 | ||
9817064b | 476 | /* |
2e662b65 JA |
477 | * Insert rq into dispatch queue of q. Queue lock must be held on |
478 | * entry. rq is added to the back of the dispatch queue. To be used by | |
479 | * specific elevators. | |
9817064b JA |
480 | */ |
481 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
482 | { | |
483 | if (q->last_merge == rq) | |
484 | q->last_merge = NULL; | |
485 | ||
486 | elv_rqhash_del(q, rq); | |
487 | ||
488 | q->nr_sorted--; | |
489 | ||
490 | q->end_sector = rq_end_sector(rq); | |
491 | q->boundary_rq = rq; | |
492 | list_add_tail(&rq->queuelist, &q->queue_head); | |
493 | } | |
2e662b65 JA |
494 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
495 | ||
165125e1 | 496 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 497 | { |
b374d18a | 498 | struct elevator_queue *e = q->elevator; |
9817064b | 499 | struct request *__rq; |
06b86245 TH |
500 | int ret; |
501 | ||
9817064b JA |
502 | /* |
503 | * First try one-hit cache. | |
504 | */ | |
06b86245 TH |
505 | if (q->last_merge) { |
506 | ret = elv_try_merge(q->last_merge, bio); | |
507 | if (ret != ELEVATOR_NO_MERGE) { | |
508 | *req = q->last_merge; | |
509 | return ret; | |
510 | } | |
511 | } | |
1da177e4 | 512 | |
ac9fafa1 AB |
513 | if (blk_queue_nomerges(q)) |
514 | return ELEVATOR_NO_MERGE; | |
515 | ||
9817064b JA |
516 | /* |
517 | * See if our hash lookup can find a potential backmerge. | |
518 | */ | |
519 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
520 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
521 | *req = __rq; | |
522 | return ELEVATOR_BACK_MERGE; | |
523 | } | |
524 | ||
1da177e4 LT |
525 | if (e->ops->elevator_merge_fn) |
526 | return e->ops->elevator_merge_fn(q, req, bio); | |
527 | ||
528 | return ELEVATOR_NO_MERGE; | |
529 | } | |
530 | ||
165125e1 | 531 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 532 | { |
b374d18a | 533 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
534 | |
535 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 536 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 537 | |
2e662b65 JA |
538 | if (type == ELEVATOR_BACK_MERGE) |
539 | elv_rqhash_reposition(q, rq); | |
9817064b | 540 | |
06b86245 | 541 | q->last_merge = rq; |
1da177e4 LT |
542 | } |
543 | ||
165125e1 | 544 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
545 | struct request *next) |
546 | { | |
b374d18a | 547 | struct elevator_queue *e = q->elevator; |
1da177e4 | 548 | |
1da177e4 LT |
549 | if (e->ops->elevator_merge_req_fn) |
550 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 551 | |
9817064b JA |
552 | elv_rqhash_reposition(q, rq); |
553 | elv_rqhash_del(q, next); | |
554 | ||
555 | q->nr_sorted--; | |
06b86245 | 556 | q->last_merge = rq; |
1da177e4 LT |
557 | } |
558 | ||
165125e1 | 559 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 560 | { |
1da177e4 LT |
561 | /* |
562 | * it already went through dequeue, we need to decrement the | |
563 | * in_flight count again | |
564 | */ | |
8922e16c | 565 | if (blk_account_rq(rq)) { |
1da177e4 | 566 | q->in_flight--; |
cad97516 JA |
567 | if (blk_sorted_rq(rq)) |
568 | elv_deactivate_rq(q, rq); | |
8922e16c | 569 | } |
1da177e4 | 570 | |
4aff5e23 | 571 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 572 | |
30e9656c | 573 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
574 | } |
575 | ||
26308eab | 576 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
577 | { |
578 | static int printed; | |
579 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
580 | ; | |
581 | if (q->nr_sorted == 0) | |
582 | return; | |
583 | if (printed++ < 10) { | |
584 | printk(KERN_ERR "%s: forced dispatching is broken " | |
585 | "(nr_sorted=%u), please report this\n", | |
586 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
587 | } | |
588 | } | |
589 | ||
6c7e8cee JA |
590 | /* |
591 | * Call with queue lock held, interrupts disabled | |
592 | */ | |
593 | void elv_quisce_start(struct request_queue *q) | |
594 | { | |
595 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); | |
596 | ||
597 | /* | |
598 | * make sure we don't have any requests in flight | |
599 | */ | |
600 | elv_drain_elevator(q); | |
601 | while (q->rq.elvpriv) { | |
602 | blk_start_queueing(q); | |
603 | spin_unlock_irq(q->queue_lock); | |
604 | msleep(10); | |
605 | spin_lock_irq(q->queue_lock); | |
606 | elv_drain_elevator(q); | |
607 | } | |
608 | } | |
609 | ||
610 | void elv_quisce_end(struct request_queue *q) | |
611 | { | |
612 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
613 | } | |
614 | ||
165125e1 | 615 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 616 | { |
797e7dbb TH |
617 | struct list_head *pos; |
618 | unsigned ordseq; | |
dac07ec1 | 619 | int unplug_it = 1; |
797e7dbb | 620 | |
5f3ea37c | 621 | trace_block_rq_insert(q, rq); |
2056a782 | 622 | |
1da177e4 LT |
623 | rq->q = q; |
624 | ||
8922e16c TH |
625 | switch (where) { |
626 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 627 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
628 | |
629 | list_add(&rq->queuelist, &q->queue_head); | |
630 | break; | |
631 | ||
632 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 633 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 634 | elv_drain_elevator(q); |
8922e16c TH |
635 | list_add_tail(&rq->queuelist, &q->queue_head); |
636 | /* | |
637 | * We kick the queue here for the following reasons. | |
638 | * - The elevator might have returned NULL previously | |
639 | * to delay requests and returned them now. As the | |
640 | * queue wasn't empty before this request, ll_rw_blk | |
641 | * won't run the queue on return, resulting in hang. | |
642 | * - Usually, back inserted requests won't be merged | |
643 | * with anything. There's no point in delaying queue | |
644 | * processing. | |
645 | */ | |
646 | blk_remove_plug(q); | |
80a4b58e | 647 | blk_start_queueing(q); |
8922e16c TH |
648 | break; |
649 | ||
650 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 651 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 652 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 653 | q->nr_sorted++; |
9817064b JA |
654 | if (rq_mergeable(rq)) { |
655 | elv_rqhash_add(q, rq); | |
656 | if (!q->last_merge) | |
657 | q->last_merge = rq; | |
658 | } | |
659 | ||
ca23509f TH |
660 | /* |
661 | * Some ioscheds (cfq) run q->request_fn directly, so | |
662 | * rq cannot be accessed after calling | |
663 | * elevator_add_req_fn. | |
664 | */ | |
665 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
666 | break; |
667 | ||
797e7dbb TH |
668 | case ELEVATOR_INSERT_REQUEUE: |
669 | /* | |
670 | * If ordered flush isn't in progress, we do front | |
671 | * insertion; otherwise, requests should be requeued | |
672 | * in ordseq order. | |
673 | */ | |
4aff5e23 | 674 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 675 | |
95543179 LV |
676 | /* |
677 | * Most requeues happen because of a busy condition, | |
678 | * don't force unplug of the queue for that case. | |
679 | */ | |
680 | unplug_it = 0; | |
681 | ||
797e7dbb TH |
682 | if (q->ordseq == 0) { |
683 | list_add(&rq->queuelist, &q->queue_head); | |
684 | break; | |
685 | } | |
686 | ||
687 | ordseq = blk_ordered_req_seq(rq); | |
688 | ||
689 | list_for_each(pos, &q->queue_head) { | |
690 | struct request *pos_rq = list_entry_rq(pos); | |
691 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
692 | break; | |
693 | } | |
694 | ||
695 | list_add_tail(&rq->queuelist, pos); | |
696 | break; | |
697 | ||
8922e16c TH |
698 | default: |
699 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 700 | __func__, where); |
8922e16c TH |
701 | BUG(); |
702 | } | |
703 | ||
dac07ec1 | 704 | if (unplug_it && blk_queue_plugged(q)) { |
1faa16d2 | 705 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
8922e16c TH |
706 | - q->in_flight; |
707 | ||
708 | if (nrq >= q->unplug_thresh) | |
709 | __generic_unplug_device(q); | |
710 | } | |
1da177e4 LT |
711 | } |
712 | ||
165125e1 | 713 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
714 | int plug) |
715 | { | |
716 | if (q->ordcolor) | |
4aff5e23 | 717 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 718 | |
4aff5e23 | 719 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
720 | /* |
721 | * toggle ordered color | |
722 | */ | |
723 | if (blk_barrier_rq(rq)) | |
724 | q->ordcolor ^= 1; | |
725 | ||
726 | /* | |
727 | * barriers implicitly indicate back insertion | |
728 | */ | |
729 | if (where == ELEVATOR_INSERT_SORT) | |
730 | where = ELEVATOR_INSERT_BACK; | |
731 | ||
732 | /* | |
733 | * this request is scheduling boundary, update | |
734 | * end_sector | |
735 | */ | |
e17fc0a1 | 736 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
737 | q->end_sector = rq_end_sector(rq); |
738 | q->boundary_rq = rq; | |
739 | } | |
4eb166d9 JA |
740 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
741 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
742 | where = ELEVATOR_INSERT_BACK; |
743 | ||
744 | if (plug) | |
745 | blk_plug_device(q); | |
746 | ||
747 | elv_insert(q, rq, where); | |
748 | } | |
2e662b65 JA |
749 | EXPORT_SYMBOL(__elv_add_request); |
750 | ||
165125e1 | 751 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
752 | int plug) |
753 | { | |
754 | unsigned long flags; | |
755 | ||
756 | spin_lock_irqsave(q->queue_lock, flags); | |
757 | __elv_add_request(q, rq, where, plug); | |
758 | spin_unlock_irqrestore(q->queue_lock, flags); | |
759 | } | |
2e662b65 JA |
760 | EXPORT_SYMBOL(elv_add_request); |
761 | ||
165125e1 | 762 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 763 | { |
8922e16c TH |
764 | struct request *rq; |
765 | ||
797e7dbb TH |
766 | while (1) { |
767 | while (!list_empty(&q->queue_head)) { | |
768 | rq = list_entry_rq(q->queue_head.next); | |
769 | if (blk_do_ordered(q, &rq)) | |
770 | return rq; | |
771 | } | |
1da177e4 | 772 | |
797e7dbb TH |
773 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
774 | return NULL; | |
1da177e4 | 775 | } |
1da177e4 LT |
776 | } |
777 | ||
165125e1 | 778 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
779 | { |
780 | struct request *rq; | |
781 | int ret; | |
782 | ||
783 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 784 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
785 | /* |
786 | * This is the first time the device driver | |
787 | * sees this request (possibly after | |
788 | * requeueing). Notify IO scheduler. | |
789 | */ | |
cad97516 JA |
790 | if (blk_sorted_rq(rq)) |
791 | elv_activate_rq(q, rq); | |
1da177e4 | 792 | |
8922e16c TH |
793 | /* |
794 | * just mark as started even if we don't start | |
795 | * it, a request that has been delayed should | |
796 | * not be passed by new incoming requests | |
797 | */ | |
4aff5e23 | 798 | rq->cmd_flags |= REQ_STARTED; |
5f3ea37c | 799 | trace_block_rq_issue(q, rq); |
8922e16c | 800 | } |
1da177e4 | 801 | |
8922e16c | 802 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 803 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
804 | q->boundary_rq = NULL; |
805 | } | |
1da177e4 | 806 | |
fa0ccd83 JB |
807 | if (rq->cmd_flags & REQ_DONTPREP) |
808 | break; | |
809 | ||
810 | if (q->dma_drain_size && rq->data_len) { | |
811 | /* | |
812 | * make sure space for the drain appears we | |
813 | * know we can do this because max_hw_segments | |
814 | * has been adjusted to be one fewer than the | |
815 | * device can handle | |
816 | */ | |
817 | rq->nr_phys_segments++; | |
fa0ccd83 JB |
818 | } |
819 | ||
820 | if (!q->prep_rq_fn) | |
1da177e4 LT |
821 | break; |
822 | ||
823 | ret = q->prep_rq_fn(q, rq); | |
824 | if (ret == BLKPREP_OK) { | |
825 | break; | |
826 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
827 | /* |
828 | * the request may have been (partially) prepped. | |
829 | * we need to keep this request in the front to | |
8922e16c TH |
830 | * avoid resource deadlock. REQ_STARTED will |
831 | * prevent other fs requests from passing this one. | |
2e759cd4 | 832 | */ |
fa0ccd83 JB |
833 | if (q->dma_drain_size && rq->data_len && |
834 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
835 | /* | |
836 | * remove the space for the drain we added | |
837 | * so that we don't add it again | |
838 | */ | |
839 | --rq->nr_phys_segments; | |
fa0ccd83 JB |
840 | } |
841 | ||
1da177e4 LT |
842 | rq = NULL; |
843 | break; | |
844 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 845 | rq->cmd_flags |= REQ_QUIET; |
99cd3386 | 846 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
1da177e4 | 847 | } else { |
24c03d47 | 848 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1da177e4 LT |
849 | break; |
850 | } | |
851 | } | |
852 | ||
853 | return rq; | |
854 | } | |
2e662b65 JA |
855 | EXPORT_SYMBOL(elv_next_request); |
856 | ||
165125e1 | 857 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 858 | { |
8922e16c | 859 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 860 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
861 | |
862 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
863 | |
864 | /* | |
865 | * the time frame between a request being removed from the lists | |
866 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 867 | * the driver side. |
1da177e4 LT |
868 | */ |
869 | if (blk_account_rq(rq)) | |
870 | q->in_flight++; | |
1da177e4 | 871 | } |
2e662b65 | 872 | |
165125e1 | 873 | int elv_queue_empty(struct request_queue *q) |
1da177e4 | 874 | { |
b374d18a | 875 | struct elevator_queue *e = q->elevator; |
1da177e4 | 876 | |
8922e16c TH |
877 | if (!list_empty(&q->queue_head)) |
878 | return 0; | |
879 | ||
1da177e4 LT |
880 | if (e->ops->elevator_queue_empty_fn) |
881 | return e->ops->elevator_queue_empty_fn(q); | |
882 | ||
8922e16c | 883 | return 1; |
1da177e4 | 884 | } |
2e662b65 JA |
885 | EXPORT_SYMBOL(elv_queue_empty); |
886 | ||
165125e1 | 887 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 888 | { |
b374d18a | 889 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
890 | |
891 | if (e->ops->elevator_latter_req_fn) | |
892 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
893 | return NULL; |
894 | } | |
895 | ||
165125e1 | 896 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 897 | { |
b374d18a | 898 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
899 | |
900 | if (e->ops->elevator_former_req_fn) | |
901 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
902 | return NULL; |
903 | } | |
904 | ||
165125e1 | 905 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 906 | { |
b374d18a | 907 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
908 | |
909 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 910 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
911 | |
912 | rq->elevator_private = NULL; | |
913 | return 0; | |
914 | } | |
915 | ||
165125e1 | 916 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 917 | { |
b374d18a | 918 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
919 | |
920 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 921 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
922 | } |
923 | ||
165125e1 | 924 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 925 | { |
b374d18a | 926 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
927 | |
928 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 929 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
930 | |
931 | return ELV_MQUEUE_MAY; | |
932 | } | |
933 | ||
11914a53 MA |
934 | void elv_abort_queue(struct request_queue *q) |
935 | { | |
936 | struct request *rq; | |
937 | ||
938 | while (!list_empty(&q->queue_head)) { | |
939 | rq = list_entry_rq(q->queue_head.next); | |
940 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 941 | trace_block_rq_abort(q, rq); |
99cd3386 | 942 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
11914a53 MA |
943 | } |
944 | } | |
945 | EXPORT_SYMBOL(elv_abort_queue); | |
946 | ||
165125e1 | 947 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 948 | { |
b374d18a | 949 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
950 | |
951 | /* | |
952 | * request is released from the driver, io must be done | |
953 | */ | |
8922e16c | 954 | if (blk_account_rq(rq)) { |
1da177e4 | 955 | q->in_flight--; |
1bc691d3 TH |
956 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
957 | e->ops->elevator_completed_req_fn(q, rq); | |
958 | } | |
797e7dbb | 959 | |
1bc691d3 TH |
960 | /* |
961 | * Check if the queue is waiting for fs requests to be | |
962 | * drained for flush sequence. | |
963 | */ | |
964 | if (unlikely(q->ordseq)) { | |
8f11b3e9 TH |
965 | struct request *next = NULL; |
966 | ||
967 | if (!list_empty(&q->queue_head)) | |
968 | next = list_entry_rq(q->queue_head.next); | |
969 | ||
970 | if (!q->in_flight && | |
797e7dbb | 971 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
8f11b3e9 | 972 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
797e7dbb | 973 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
80a4b58e | 974 | blk_start_queueing(q); |
797e7dbb | 975 | } |
8922e16c | 976 | } |
1da177e4 LT |
977 | } |
978 | ||
3d1ab40f AV |
979 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
980 | ||
981 | static ssize_t | |
982 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 983 | { |
3d1ab40f | 984 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 985 | struct elevator_queue *e; |
3d1ab40f AV |
986 | ssize_t error; |
987 | ||
988 | if (!entry->show) | |
989 | return -EIO; | |
990 | ||
b374d18a | 991 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
992 | mutex_lock(&e->sysfs_lock); |
993 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
994 | mutex_unlock(&e->sysfs_lock); | |
995 | return error; | |
996 | } | |
1da177e4 | 997 | |
3d1ab40f AV |
998 | static ssize_t |
999 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
1000 | const char *page, size_t length) | |
1001 | { | |
3d1ab40f | 1002 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 1003 | struct elevator_queue *e; |
3d1ab40f | 1004 | ssize_t error; |
1da177e4 | 1005 | |
3d1ab40f AV |
1006 | if (!entry->store) |
1007 | return -EIO; | |
1da177e4 | 1008 | |
b374d18a | 1009 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f AV |
1010 | mutex_lock(&e->sysfs_lock); |
1011 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
1012 | mutex_unlock(&e->sysfs_lock); | |
1013 | return error; | |
1014 | } | |
1015 | ||
1016 | static struct sysfs_ops elv_sysfs_ops = { | |
1017 | .show = elv_attr_show, | |
1018 | .store = elv_attr_store, | |
1019 | }; | |
1020 | ||
1021 | static struct kobj_type elv_ktype = { | |
1022 | .sysfs_ops = &elv_sysfs_ops, | |
1023 | .release = elevator_release, | |
1024 | }; | |
1025 | ||
1026 | int elv_register_queue(struct request_queue *q) | |
1027 | { | |
b374d18a | 1028 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
1029 | int error; |
1030 | ||
b2d6db58 | 1031 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 1032 | if (!error) { |
e572ec7e | 1033 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 1034 | if (attr) { |
e572ec7e AV |
1035 | while (attr->attr.name) { |
1036 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 1037 | break; |
e572ec7e | 1038 | attr++; |
3d1ab40f AV |
1039 | } |
1040 | } | |
1041 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
1042 | } | |
1043 | return error; | |
1da177e4 LT |
1044 | } |
1045 | ||
b374d18a | 1046 | static void __elv_unregister_queue(struct elevator_queue *e) |
bc1c1169 JA |
1047 | { |
1048 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
1049 | kobject_del(&e->kobj); | |
1050 | } | |
1051 | ||
1da177e4 LT |
1052 | void elv_unregister_queue(struct request_queue *q) |
1053 | { | |
bc1c1169 JA |
1054 | if (q) |
1055 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
1056 | } |
1057 | ||
2fdd82bd | 1058 | void elv_register(struct elevator_type *e) |
1da177e4 | 1059 | { |
1ffb96c5 | 1060 | char *def = ""; |
2a12dcd7 JA |
1061 | |
1062 | spin_lock(&elv_list_lock); | |
ce524497 | 1063 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 1064 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 1065 | spin_unlock(&elv_list_lock); |
1da177e4 | 1066 | |
5f003976 ND |
1067 | if (!strcmp(e->elevator_name, chosen_elevator) || |
1068 | (!*chosen_elevator && | |
1069 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
1070 | def = " (default)"; |
1071 | ||
4eb166d9 JA |
1072 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1073 | def); | |
1da177e4 LT |
1074 | } |
1075 | EXPORT_SYMBOL_GPL(elv_register); | |
1076 | ||
1077 | void elv_unregister(struct elevator_type *e) | |
1078 | { | |
83521d3e CH |
1079 | struct task_struct *g, *p; |
1080 | ||
1081 | /* | |
1082 | * Iterate every thread in the process to remove the io contexts. | |
1083 | */ | |
e17a9489 AV |
1084 | if (e->ops.trim) { |
1085 | read_lock(&tasklist_lock); | |
1086 | do_each_thread(g, p) { | |
1087 | task_lock(p); | |
2d8f6131 ON |
1088 | if (p->io_context) |
1089 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1090 | task_unlock(p); |
1091 | } while_each_thread(g, p); | |
1092 | read_unlock(&tasklist_lock); | |
1093 | } | |
83521d3e | 1094 | |
2a12dcd7 | 1095 | spin_lock(&elv_list_lock); |
1da177e4 | 1096 | list_del_init(&e->list); |
2a12dcd7 | 1097 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1098 | } |
1099 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1100 | ||
1101 | /* | |
1102 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1103 | * we don't free the old io scheduler, before we have allocated what we | |
1104 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1105 | * one, if the new one fails init for some reason. |
1da177e4 | 1106 | */ |
165125e1 | 1107 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1108 | { |
b374d18a | 1109 | struct elevator_queue *old_elevator, *e; |
bc1c1169 | 1110 | void *data; |
1da177e4 | 1111 | |
cb98fc8b TH |
1112 | /* |
1113 | * Allocate new elevator | |
1114 | */ | |
b5deef90 | 1115 | e = elevator_alloc(q, new_e); |
1da177e4 | 1116 | if (!e) |
3d1ab40f | 1117 | return 0; |
1da177e4 | 1118 | |
bc1c1169 JA |
1119 | data = elevator_init_queue(q, e); |
1120 | if (!data) { | |
1121 | kobject_put(&e->kobj); | |
1122 | return 0; | |
1123 | } | |
1124 | ||
1da177e4 | 1125 | /* |
cb98fc8b | 1126 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1127 | */ |
cb98fc8b | 1128 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 1129 | elv_quisce_start(q); |
cb98fc8b | 1130 | |
1da177e4 | 1131 | /* |
bc1c1169 | 1132 | * Remember old elevator. |
1da177e4 | 1133 | */ |
1da177e4 LT |
1134 | old_elevator = q->elevator; |
1135 | ||
1da177e4 LT |
1136 | /* |
1137 | * attach and start new elevator | |
1138 | */ | |
bc1c1169 JA |
1139 | elevator_attach(q, e, data); |
1140 | ||
1141 | spin_unlock_irq(q->queue_lock); | |
1142 | ||
1143 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1144 | |
1145 | if (elv_register_queue(q)) | |
1146 | goto fail_register; | |
1147 | ||
1148 | /* | |
cb98fc8b | 1149 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1150 | */ |
1151 | elevator_exit(old_elevator); | |
75ad23bc | 1152 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 1153 | elv_quisce_end(q); |
75ad23bc NP |
1154 | spin_unlock_irq(q->queue_lock); |
1155 | ||
4722dc52 AB |
1156 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1157 | ||
3d1ab40f | 1158 | return 1; |
1da177e4 LT |
1159 | |
1160 | fail_register: | |
1161 | /* | |
1162 | * switch failed, exit the new io scheduler and reattach the old | |
1163 | * one again (along with re-adding the sysfs dir) | |
1164 | */ | |
1165 | elevator_exit(e); | |
1da177e4 LT |
1166 | q->elevator = old_elevator; |
1167 | elv_register_queue(q); | |
75ad23bc NP |
1168 | |
1169 | spin_lock_irq(q->queue_lock); | |
1170 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1171 | spin_unlock_irq(q->queue_lock); | |
1172 | ||
3d1ab40f | 1173 | return 0; |
1da177e4 LT |
1174 | } |
1175 | ||
165125e1 JA |
1176 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1177 | size_t count) | |
1da177e4 LT |
1178 | { |
1179 | char elevator_name[ELV_NAME_MAX]; | |
1180 | struct elevator_type *e; | |
1181 | ||
ee2e992c LZ |
1182 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1183 | strstrip(elevator_name); | |
1da177e4 LT |
1184 | |
1185 | e = elevator_get(elevator_name); | |
1186 | if (!e) { | |
1187 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1188 | return -EINVAL; | |
1189 | } | |
1190 | ||
2ca7d93b ND |
1191 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1192 | elevator_put(e); | |
1da177e4 | 1193 | return count; |
2ca7d93b | 1194 | } |
1da177e4 | 1195 | |
3d1ab40f | 1196 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1197 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1198 | elevator_name); | |
1da177e4 LT |
1199 | return count; |
1200 | } | |
1201 | ||
165125e1 | 1202 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1203 | { |
b374d18a | 1204 | struct elevator_queue *e = q->elevator; |
1da177e4 | 1205 | struct elevator_type *elv = e->elevator_type; |
70cee26e | 1206 | struct elevator_type *__e; |
1da177e4 LT |
1207 | int len = 0; |
1208 | ||
2a12dcd7 | 1209 | spin_lock(&elv_list_lock); |
70cee26e | 1210 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1211 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1212 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1213 | else | |
1214 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1215 | } | |
2a12dcd7 | 1216 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1217 | |
1218 | len += sprintf(len+name, "\n"); | |
1219 | return len; | |
1220 | } | |
1221 | ||
165125e1 JA |
1222 | struct request *elv_rb_former_request(struct request_queue *q, |
1223 | struct request *rq) | |
2e662b65 JA |
1224 | { |
1225 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1226 | ||
1227 | if (rbprev) | |
1228 | return rb_entry_rq(rbprev); | |
1229 | ||
1230 | return NULL; | |
1231 | } | |
2e662b65 JA |
1232 | EXPORT_SYMBOL(elv_rb_former_request); |
1233 | ||
165125e1 JA |
1234 | struct request *elv_rb_latter_request(struct request_queue *q, |
1235 | struct request *rq) | |
2e662b65 JA |
1236 | { |
1237 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1238 | ||
1239 | if (rbnext) | |
1240 | return rb_entry_rq(rbnext); | |
1241 | ||
1242 | return NULL; | |
1243 | } | |
2e662b65 | 1244 | EXPORT_SYMBOL(elv_rb_latter_request); |