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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
7 | * |
8 | * Split the elevator a bit so that it is possible to choose a different | |
9 | * one or even write a new "plug in". There are three pieces: | |
10 | * - elevator_fn, inserts a new request in the queue list | |
11 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
12 | * an existing request | |
13 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
14 | * | |
15 | * 20082000 Dave Jones <davej@suse.de> : | |
16 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
17 | * when run without -bN | |
18 | * | |
19 | * Jens: | |
20 | * - Rework again to work with bio instead of buffer_heads | |
21 | * - loose bi_dev comparisons, partition handling is right now | |
22 | * - completely modularize elevator setup and teardown | |
23 | * | |
24 | */ | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/elevator.h> | |
29 | #include <linux/bio.h> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
cb98fc8b | 34 | #include <linux/delay.h> |
2056a782 | 35 | #include <linux/blktrace_api.h> |
9817064b | 36 | #include <linux/hash.h> |
1da177e4 LT |
37 | |
38 | #include <asm/uaccess.h> | |
39 | ||
40 | static DEFINE_SPINLOCK(elv_list_lock); | |
41 | static LIST_HEAD(elv_list); | |
42 | ||
9817064b JA |
43 | /* |
44 | * Merge hash stuff. | |
45 | */ | |
46 | static const int elv_hash_shift = 6; | |
47 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
48 | #define ELV_HASH_FN(sec) \ |
49 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
50 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
51 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
52 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
53 | ||
da775265 JA |
54 | /* |
55 | * Query io scheduler to see if the current process issuing bio may be | |
56 | * merged with rq. | |
57 | */ | |
58 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
59 | { | |
165125e1 | 60 | struct request_queue *q = rq->q; |
da775265 JA |
61 | elevator_t *e = q->elevator; |
62 | ||
63 | if (e->ops->elevator_allow_merge_fn) | |
64 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
65 | ||
66 | return 1; | |
67 | } | |
68 | ||
1da177e4 LT |
69 | /* |
70 | * can we safely merge with this request? | |
71 | */ | |
72 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) | |
73 | { | |
74 | if (!rq_mergeable(rq)) | |
75 | return 0; | |
76 | ||
77 | /* | |
78 | * different data direction or already started, don't merge | |
79 | */ | |
80 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
81 | return 0; | |
82 | ||
83 | /* | |
da775265 | 84 | * must be same device and not a special request |
1da177e4 | 85 | */ |
bb4067e3 | 86 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
87 | return 0; |
88 | ||
89 | if (!elv_iosched_allow_merge(rq, bio)) | |
90 | return 0; | |
1da177e4 | 91 | |
da775265 | 92 | return 1; |
1da177e4 LT |
93 | } |
94 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
95 | ||
769db45b | 96 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
97 | { |
98 | int ret = ELEVATOR_NO_MERGE; | |
99 | ||
100 | /* | |
101 | * we can merge and sequence is ok, check if it's possible | |
102 | */ | |
103 | if (elv_rq_merge_ok(__rq, bio)) { | |
104 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
105 | ret = ELEVATOR_BACK_MERGE; | |
106 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
107 | ret = ELEVATOR_FRONT_MERGE; | |
108 | } | |
109 | ||
110 | return ret; | |
111 | } | |
1da177e4 | 112 | |
1da177e4 LT |
113 | static struct elevator_type *elevator_find(const char *name) |
114 | { | |
a22b169d | 115 | struct elevator_type *e; |
1da177e4 | 116 | |
70cee26e | 117 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
118 | if (!strcmp(e->elevator_name, name)) |
119 | return e; | |
1da177e4 | 120 | } |
1da177e4 | 121 | |
a22b169d | 122 | return NULL; |
1da177e4 LT |
123 | } |
124 | ||
125 | static void elevator_put(struct elevator_type *e) | |
126 | { | |
127 | module_put(e->elevator_owner); | |
128 | } | |
129 | ||
130 | static struct elevator_type *elevator_get(const char *name) | |
131 | { | |
2824bc93 | 132 | struct elevator_type *e; |
1da177e4 | 133 | |
2a12dcd7 | 134 | spin_lock(&elv_list_lock); |
2824bc93 TH |
135 | |
136 | e = elevator_find(name); | |
137 | if (e && !try_module_get(e->elevator_owner)) | |
138 | e = NULL; | |
139 | ||
2a12dcd7 | 140 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
141 | |
142 | return e; | |
143 | } | |
144 | ||
165125e1 JA |
145 | static void *elevator_init_queue(struct request_queue *q, |
146 | struct elevator_queue *eq) | |
1da177e4 | 147 | { |
bb37b94c | 148 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 149 | } |
1da177e4 | 150 | |
165125e1 | 151 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
152 | void *data) |
153 | { | |
1da177e4 | 154 | q->elevator = eq; |
bc1c1169 | 155 | eq->elevator_data = data; |
1da177e4 LT |
156 | } |
157 | ||
158 | static char chosen_elevator[16]; | |
159 | ||
5f003976 | 160 | static int __init elevator_setup(char *str) |
1da177e4 | 161 | { |
752a3b79 CE |
162 | /* |
163 | * Be backwards-compatible with previous kernels, so users | |
164 | * won't get the wrong elevator. | |
165 | */ | |
5f003976 | 166 | if (!strcmp(str, "as")) |
752a3b79 | 167 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 168 | else |
5f003976 | 169 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 170 | return 1; |
1da177e4 LT |
171 | } |
172 | ||
173 | __setup("elevator=", elevator_setup); | |
174 | ||
3d1ab40f AV |
175 | static struct kobj_type elv_ktype; |
176 | ||
165125e1 JA |
177 | static elevator_t *elevator_alloc(struct request_queue *q, |
178 | struct elevator_type *e) | |
3d1ab40f | 179 | { |
9817064b JA |
180 | elevator_t *eq; |
181 | int i; | |
182 | ||
94f6030c | 183 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
184 | if (unlikely(!eq)) |
185 | goto err; | |
186 | ||
9817064b JA |
187 | eq->ops = &e->ops; |
188 | eq->elevator_type = e; | |
f9cb074b | 189 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
190 | mutex_init(&eq->sysfs_lock); |
191 | ||
b5deef90 JA |
192 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
193 | GFP_KERNEL, q->node); | |
9817064b JA |
194 | if (!eq->hash) |
195 | goto err; | |
196 | ||
197 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
198 | INIT_HLIST_HEAD(&eq->hash[i]); | |
199 | ||
3d1ab40f | 200 | return eq; |
9817064b JA |
201 | err: |
202 | kfree(eq); | |
203 | elevator_put(e); | |
204 | return NULL; | |
3d1ab40f AV |
205 | } |
206 | ||
207 | static void elevator_release(struct kobject *kobj) | |
208 | { | |
209 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 210 | |
3d1ab40f | 211 | elevator_put(e->elevator_type); |
9817064b | 212 | kfree(e->hash); |
3d1ab40f AV |
213 | kfree(e); |
214 | } | |
215 | ||
165125e1 | 216 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
217 | { |
218 | struct elevator_type *e = NULL; | |
219 | struct elevator_queue *eq; | |
220 | int ret = 0; | |
bc1c1169 | 221 | void *data; |
1da177e4 | 222 | |
cb98fc8b TH |
223 | INIT_LIST_HEAD(&q->queue_head); |
224 | q->last_merge = NULL; | |
225 | q->end_sector = 0; | |
226 | q->boundary_rq = NULL; | |
cb98fc8b | 227 | |
4eb166d9 JA |
228 | if (name) { |
229 | e = elevator_get(name); | |
230 | if (!e) | |
231 | return -EINVAL; | |
232 | } | |
1da177e4 | 233 | |
4eb166d9 JA |
234 | if (!e && *chosen_elevator) { |
235 | e = elevator_get(chosen_elevator); | |
236 | if (!e) | |
237 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
238 | chosen_elevator); | |
239 | } | |
248d5ca5 | 240 | |
4eb166d9 JA |
241 | if (!e) { |
242 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
243 | if (!e) { | |
244 | printk(KERN_ERR | |
245 | "Default I/O scheduler not found. " \ | |
246 | "Using noop.\n"); | |
247 | e = elevator_get("noop"); | |
248 | } | |
5f003976 ND |
249 | } |
250 | ||
b5deef90 | 251 | eq = elevator_alloc(q, e); |
3d1ab40f | 252 | if (!eq) |
1da177e4 | 253 | return -ENOMEM; |
1da177e4 | 254 | |
bc1c1169 JA |
255 | data = elevator_init_queue(q, eq); |
256 | if (!data) { | |
3d1ab40f | 257 | kobject_put(&eq->kobj); |
bc1c1169 JA |
258 | return -ENOMEM; |
259 | } | |
1da177e4 | 260 | |
bc1c1169 | 261 | elevator_attach(q, eq, data); |
1da177e4 LT |
262 | return ret; |
263 | } | |
2e662b65 JA |
264 | EXPORT_SYMBOL(elevator_init); |
265 | ||
1da177e4 LT |
266 | void elevator_exit(elevator_t *e) |
267 | { | |
3d1ab40f | 268 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
269 | if (e->ops->elevator_exit_fn) |
270 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
271 | e->ops = NULL; |
272 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 273 | |
3d1ab40f | 274 | kobject_put(&e->kobj); |
1da177e4 | 275 | } |
2e662b65 JA |
276 | EXPORT_SYMBOL(elevator_exit); |
277 | ||
165125e1 | 278 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
279 | { |
280 | elevator_t *e = q->elevator; | |
281 | ||
282 | if (e->ops->elevator_activate_req_fn) | |
283 | e->ops->elevator_activate_req_fn(q, rq); | |
284 | } | |
285 | ||
165125e1 | 286 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
287 | { |
288 | elevator_t *e = q->elevator; | |
289 | ||
290 | if (e->ops->elevator_deactivate_req_fn) | |
291 | e->ops->elevator_deactivate_req_fn(q, rq); | |
292 | } | |
293 | ||
9817064b JA |
294 | static inline void __elv_rqhash_del(struct request *rq) |
295 | { | |
296 | hlist_del_init(&rq->hash); | |
297 | } | |
298 | ||
165125e1 | 299 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
300 | { |
301 | if (ELV_ON_HASH(rq)) | |
302 | __elv_rqhash_del(rq); | |
303 | } | |
304 | ||
165125e1 | 305 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b JA |
306 | { |
307 | elevator_t *e = q->elevator; | |
308 | ||
309 | BUG_ON(ELV_ON_HASH(rq)); | |
310 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
311 | } | |
312 | ||
165125e1 | 313 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
314 | { |
315 | __elv_rqhash_del(rq); | |
316 | elv_rqhash_add(q, rq); | |
317 | } | |
318 | ||
165125e1 | 319 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b JA |
320 | { |
321 | elevator_t *e = q->elevator; | |
322 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
323 | struct hlist_node *entry, *next; | |
324 | struct request *rq; | |
325 | ||
326 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
327 | BUG_ON(!ELV_ON_HASH(rq)); | |
328 | ||
329 | if (unlikely(!rq_mergeable(rq))) { | |
330 | __elv_rqhash_del(rq); | |
331 | continue; | |
332 | } | |
333 | ||
334 | if (rq_hash_key(rq) == offset) | |
335 | return rq; | |
336 | } | |
337 | ||
338 | return NULL; | |
339 | } | |
340 | ||
2e662b65 JA |
341 | /* |
342 | * RB-tree support functions for inserting/lookup/removal of requests | |
343 | * in a sorted RB tree. | |
344 | */ | |
345 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
346 | { | |
347 | struct rb_node **p = &root->rb_node; | |
348 | struct rb_node *parent = NULL; | |
349 | struct request *__rq; | |
350 | ||
351 | while (*p) { | |
352 | parent = *p; | |
353 | __rq = rb_entry(parent, struct request, rb_node); | |
354 | ||
355 | if (rq->sector < __rq->sector) | |
356 | p = &(*p)->rb_left; | |
357 | else if (rq->sector > __rq->sector) | |
358 | p = &(*p)->rb_right; | |
359 | else | |
360 | return __rq; | |
361 | } | |
362 | ||
363 | rb_link_node(&rq->rb_node, parent, p); | |
364 | rb_insert_color(&rq->rb_node, root); | |
365 | return NULL; | |
366 | } | |
2e662b65 JA |
367 | EXPORT_SYMBOL(elv_rb_add); |
368 | ||
369 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
370 | { | |
371 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
372 | rb_erase(&rq->rb_node, root); | |
373 | RB_CLEAR_NODE(&rq->rb_node); | |
374 | } | |
2e662b65 JA |
375 | EXPORT_SYMBOL(elv_rb_del); |
376 | ||
377 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
378 | { | |
379 | struct rb_node *n = root->rb_node; | |
380 | struct request *rq; | |
381 | ||
382 | while (n) { | |
383 | rq = rb_entry(n, struct request, rb_node); | |
384 | ||
385 | if (sector < rq->sector) | |
386 | n = n->rb_left; | |
387 | else if (sector > rq->sector) | |
388 | n = n->rb_right; | |
389 | else | |
390 | return rq; | |
391 | } | |
392 | ||
393 | return NULL; | |
394 | } | |
2e662b65 JA |
395 | EXPORT_SYMBOL(elv_rb_find); |
396 | ||
8922e16c TH |
397 | /* |
398 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 399 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 400 | * specific elevators. |
8922e16c | 401 | */ |
165125e1 | 402 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
403 | { |
404 | sector_t boundary; | |
8922e16c | 405 | struct list_head *entry; |
4eb166d9 | 406 | int stop_flags; |
8922e16c | 407 | |
06b86245 TH |
408 | if (q->last_merge == rq) |
409 | q->last_merge = NULL; | |
9817064b JA |
410 | |
411 | elv_rqhash_del(q, rq); | |
412 | ||
15853af9 | 413 | q->nr_sorted--; |
06b86245 | 414 | |
1b47f531 | 415 | boundary = q->end_sector; |
4eb166d9 | 416 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
417 | list_for_each_prev(entry, &q->queue_head) { |
418 | struct request *pos = list_entry_rq(entry); | |
419 | ||
783660b2 JA |
420 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
421 | break; | |
4eb166d9 | 422 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
423 | break; |
424 | if (rq->sector >= boundary) { | |
425 | if (pos->sector < boundary) | |
426 | continue; | |
427 | } else { | |
428 | if (pos->sector >= boundary) | |
429 | break; | |
430 | } | |
431 | if (rq->sector >= pos->sector) | |
432 | break; | |
433 | } | |
434 | ||
435 | list_add(&rq->queuelist, entry); | |
436 | } | |
2e662b65 JA |
437 | EXPORT_SYMBOL(elv_dispatch_sort); |
438 | ||
9817064b | 439 | /* |
2e662b65 JA |
440 | * Insert rq into dispatch queue of q. Queue lock must be held on |
441 | * entry. rq is added to the back of the dispatch queue. To be used by | |
442 | * specific elevators. | |
9817064b JA |
443 | */ |
444 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
445 | { | |
446 | if (q->last_merge == rq) | |
447 | q->last_merge = NULL; | |
448 | ||
449 | elv_rqhash_del(q, rq); | |
450 | ||
451 | q->nr_sorted--; | |
452 | ||
453 | q->end_sector = rq_end_sector(rq); | |
454 | q->boundary_rq = rq; | |
455 | list_add_tail(&rq->queuelist, &q->queue_head); | |
456 | } | |
2e662b65 JA |
457 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
458 | ||
165125e1 | 459 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 LT |
460 | { |
461 | elevator_t *e = q->elevator; | |
9817064b | 462 | struct request *__rq; |
06b86245 TH |
463 | int ret; |
464 | ||
9817064b JA |
465 | /* |
466 | * First try one-hit cache. | |
467 | */ | |
06b86245 TH |
468 | if (q->last_merge) { |
469 | ret = elv_try_merge(q->last_merge, bio); | |
470 | if (ret != ELEVATOR_NO_MERGE) { | |
471 | *req = q->last_merge; | |
472 | return ret; | |
473 | } | |
474 | } | |
1da177e4 | 475 | |
9817064b JA |
476 | /* |
477 | * See if our hash lookup can find a potential backmerge. | |
478 | */ | |
479 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
480 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
481 | *req = __rq; | |
482 | return ELEVATOR_BACK_MERGE; | |
483 | } | |
484 | ||
1da177e4 LT |
485 | if (e->ops->elevator_merge_fn) |
486 | return e->ops->elevator_merge_fn(q, req, bio); | |
487 | ||
488 | return ELEVATOR_NO_MERGE; | |
489 | } | |
490 | ||
165125e1 | 491 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 LT |
492 | { |
493 | elevator_t *e = q->elevator; | |
494 | ||
495 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 496 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 497 | |
2e662b65 JA |
498 | if (type == ELEVATOR_BACK_MERGE) |
499 | elv_rqhash_reposition(q, rq); | |
9817064b | 500 | |
06b86245 | 501 | q->last_merge = rq; |
1da177e4 LT |
502 | } |
503 | ||
165125e1 | 504 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
505 | struct request *next) |
506 | { | |
507 | elevator_t *e = q->elevator; | |
508 | ||
1da177e4 LT |
509 | if (e->ops->elevator_merge_req_fn) |
510 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 511 | |
9817064b JA |
512 | elv_rqhash_reposition(q, rq); |
513 | elv_rqhash_del(q, next); | |
514 | ||
515 | q->nr_sorted--; | |
06b86245 | 516 | q->last_merge = rq; |
1da177e4 LT |
517 | } |
518 | ||
165125e1 | 519 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 520 | { |
1da177e4 LT |
521 | /* |
522 | * it already went through dequeue, we need to decrement the | |
523 | * in_flight count again | |
524 | */ | |
8922e16c | 525 | if (blk_account_rq(rq)) { |
1da177e4 | 526 | q->in_flight--; |
cad97516 JA |
527 | if (blk_sorted_rq(rq)) |
528 | elv_deactivate_rq(q, rq); | |
8922e16c | 529 | } |
1da177e4 | 530 | |
4aff5e23 | 531 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 532 | |
30e9656c | 533 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
534 | } |
535 | ||
165125e1 | 536 | static void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
537 | { |
538 | static int printed; | |
539 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
540 | ; | |
541 | if (q->nr_sorted == 0) | |
542 | return; | |
543 | if (printed++ < 10) { | |
544 | printk(KERN_ERR "%s: forced dispatching is broken " | |
545 | "(nr_sorted=%u), please report this\n", | |
546 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
547 | } | |
548 | } | |
549 | ||
165125e1 | 550 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 551 | { |
797e7dbb TH |
552 | struct list_head *pos; |
553 | unsigned ordseq; | |
dac07ec1 | 554 | int unplug_it = 1; |
797e7dbb | 555 | |
2056a782 JA |
556 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
557 | ||
1da177e4 LT |
558 | rq->q = q; |
559 | ||
8922e16c TH |
560 | switch (where) { |
561 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 562 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
563 | |
564 | list_add(&rq->queuelist, &q->queue_head); | |
565 | break; | |
566 | ||
567 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 568 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 569 | elv_drain_elevator(q); |
8922e16c TH |
570 | list_add_tail(&rq->queuelist, &q->queue_head); |
571 | /* | |
572 | * We kick the queue here for the following reasons. | |
573 | * - The elevator might have returned NULL previously | |
574 | * to delay requests and returned them now. As the | |
575 | * queue wasn't empty before this request, ll_rw_blk | |
576 | * won't run the queue on return, resulting in hang. | |
577 | * - Usually, back inserted requests won't be merged | |
578 | * with anything. There's no point in delaying queue | |
579 | * processing. | |
580 | */ | |
581 | blk_remove_plug(q); | |
582 | q->request_fn(q); | |
583 | break; | |
584 | ||
585 | case ELEVATOR_INSERT_SORT: | |
586 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 587 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 588 | q->nr_sorted++; |
9817064b JA |
589 | if (rq_mergeable(rq)) { |
590 | elv_rqhash_add(q, rq); | |
591 | if (!q->last_merge) | |
592 | q->last_merge = rq; | |
593 | } | |
594 | ||
ca23509f TH |
595 | /* |
596 | * Some ioscheds (cfq) run q->request_fn directly, so | |
597 | * rq cannot be accessed after calling | |
598 | * elevator_add_req_fn. | |
599 | */ | |
600 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
601 | break; |
602 | ||
797e7dbb TH |
603 | case ELEVATOR_INSERT_REQUEUE: |
604 | /* | |
605 | * If ordered flush isn't in progress, we do front | |
606 | * insertion; otherwise, requests should be requeued | |
607 | * in ordseq order. | |
608 | */ | |
4aff5e23 | 609 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 610 | |
95543179 LV |
611 | /* |
612 | * Most requeues happen because of a busy condition, | |
613 | * don't force unplug of the queue for that case. | |
614 | */ | |
615 | unplug_it = 0; | |
616 | ||
797e7dbb TH |
617 | if (q->ordseq == 0) { |
618 | list_add(&rq->queuelist, &q->queue_head); | |
619 | break; | |
620 | } | |
621 | ||
622 | ordseq = blk_ordered_req_seq(rq); | |
623 | ||
624 | list_for_each(pos, &q->queue_head) { | |
625 | struct request *pos_rq = list_entry_rq(pos); | |
626 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
627 | break; | |
628 | } | |
629 | ||
630 | list_add_tail(&rq->queuelist, pos); | |
631 | break; | |
632 | ||
8922e16c TH |
633 | default: |
634 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
635 | __FUNCTION__, where); | |
636 | BUG(); | |
637 | } | |
638 | ||
dac07ec1 | 639 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
640 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
641 | - q->in_flight; | |
642 | ||
643 | if (nrq >= q->unplug_thresh) | |
644 | __generic_unplug_device(q); | |
645 | } | |
1da177e4 LT |
646 | } |
647 | ||
165125e1 | 648 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
649 | int plug) |
650 | { | |
651 | if (q->ordcolor) | |
4aff5e23 | 652 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 653 | |
4aff5e23 | 654 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
655 | /* |
656 | * toggle ordered color | |
657 | */ | |
658 | if (blk_barrier_rq(rq)) | |
659 | q->ordcolor ^= 1; | |
660 | ||
661 | /* | |
662 | * barriers implicitly indicate back insertion | |
663 | */ | |
664 | if (where == ELEVATOR_INSERT_SORT) | |
665 | where = ELEVATOR_INSERT_BACK; | |
666 | ||
667 | /* | |
668 | * this request is scheduling boundary, update | |
669 | * end_sector | |
670 | */ | |
671 | if (blk_fs_request(rq)) { | |
672 | q->end_sector = rq_end_sector(rq); | |
673 | q->boundary_rq = rq; | |
674 | } | |
4eb166d9 JA |
675 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
676 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
677 | where = ELEVATOR_INSERT_BACK; |
678 | ||
679 | if (plug) | |
680 | blk_plug_device(q); | |
681 | ||
682 | elv_insert(q, rq, where); | |
683 | } | |
2e662b65 JA |
684 | EXPORT_SYMBOL(__elv_add_request); |
685 | ||
165125e1 | 686 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
687 | int plug) |
688 | { | |
689 | unsigned long flags; | |
690 | ||
691 | spin_lock_irqsave(q->queue_lock, flags); | |
692 | __elv_add_request(q, rq, where, plug); | |
693 | spin_unlock_irqrestore(q->queue_lock, flags); | |
694 | } | |
2e662b65 JA |
695 | EXPORT_SYMBOL(elv_add_request); |
696 | ||
165125e1 | 697 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 698 | { |
8922e16c TH |
699 | struct request *rq; |
700 | ||
797e7dbb TH |
701 | while (1) { |
702 | while (!list_empty(&q->queue_head)) { | |
703 | rq = list_entry_rq(q->queue_head.next); | |
704 | if (blk_do_ordered(q, &rq)) | |
705 | return rq; | |
706 | } | |
1da177e4 | 707 | |
797e7dbb TH |
708 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
709 | return NULL; | |
1da177e4 | 710 | } |
1da177e4 LT |
711 | } |
712 | ||
165125e1 | 713 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
714 | { |
715 | struct request *rq; | |
716 | int ret; | |
717 | ||
718 | while ((rq = __elv_next_request(q)) != NULL) { | |
bf2de6f5 JA |
719 | /* |
720 | * Kill the empty barrier place holder, the driver must | |
721 | * not ever see it. | |
722 | */ | |
723 | if (blk_empty_barrier(rq)) { | |
724 | end_queued_request(rq, 1); | |
725 | continue; | |
726 | } | |
4aff5e23 | 727 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
728 | /* |
729 | * This is the first time the device driver | |
730 | * sees this request (possibly after | |
731 | * requeueing). Notify IO scheduler. | |
732 | */ | |
cad97516 JA |
733 | if (blk_sorted_rq(rq)) |
734 | elv_activate_rq(q, rq); | |
1da177e4 | 735 | |
8922e16c TH |
736 | /* |
737 | * just mark as started even if we don't start | |
738 | * it, a request that has been delayed should | |
739 | * not be passed by new incoming requests | |
740 | */ | |
4aff5e23 | 741 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 742 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 743 | } |
1da177e4 | 744 | |
8922e16c | 745 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 746 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
747 | q->boundary_rq = NULL; |
748 | } | |
1da177e4 | 749 | |
fa0ccd83 JB |
750 | if (rq->cmd_flags & REQ_DONTPREP) |
751 | break; | |
752 | ||
753 | if (q->dma_drain_size && rq->data_len) { | |
754 | /* | |
755 | * make sure space for the drain appears we | |
756 | * know we can do this because max_hw_segments | |
757 | * has been adjusted to be one fewer than the | |
758 | * device can handle | |
759 | */ | |
760 | rq->nr_phys_segments++; | |
761 | rq->nr_hw_segments++; | |
762 | } | |
763 | ||
764 | if (!q->prep_rq_fn) | |
1da177e4 LT |
765 | break; |
766 | ||
767 | ret = q->prep_rq_fn(q, rq); | |
768 | if (ret == BLKPREP_OK) { | |
769 | break; | |
770 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
771 | /* |
772 | * the request may have been (partially) prepped. | |
773 | * we need to keep this request in the front to | |
8922e16c TH |
774 | * avoid resource deadlock. REQ_STARTED will |
775 | * prevent other fs requests from passing this one. | |
2e759cd4 | 776 | */ |
fa0ccd83 JB |
777 | if (q->dma_drain_size && rq->data_len && |
778 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
779 | /* | |
780 | * remove the space for the drain we added | |
781 | * so that we don't add it again | |
782 | */ | |
783 | --rq->nr_phys_segments; | |
784 | --rq->nr_hw_segments; | |
785 | } | |
786 | ||
1da177e4 LT |
787 | rq = NULL; |
788 | break; | |
789 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 790 | rq->cmd_flags |= REQ_QUIET; |
a0cd1285 | 791 | end_queued_request(rq, 0); |
1da177e4 LT |
792 | } else { |
793 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
794 | ret); | |
795 | break; | |
796 | } | |
797 | } | |
798 | ||
799 | return rq; | |
800 | } | |
2e662b65 JA |
801 | EXPORT_SYMBOL(elv_next_request); |
802 | ||
165125e1 | 803 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 804 | { |
8922e16c | 805 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 806 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
807 | |
808 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
809 | |
810 | /* | |
811 | * the time frame between a request being removed from the lists | |
812 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 813 | * the driver side. |
1da177e4 LT |
814 | */ |
815 | if (blk_account_rq(rq)) | |
816 | q->in_flight++; | |
1da177e4 | 817 | } |
2e662b65 JA |
818 | EXPORT_SYMBOL(elv_dequeue_request); |
819 | ||
165125e1 | 820 | int elv_queue_empty(struct request_queue *q) |
1da177e4 LT |
821 | { |
822 | elevator_t *e = q->elevator; | |
823 | ||
8922e16c TH |
824 | if (!list_empty(&q->queue_head)) |
825 | return 0; | |
826 | ||
1da177e4 LT |
827 | if (e->ops->elevator_queue_empty_fn) |
828 | return e->ops->elevator_queue_empty_fn(q); | |
829 | ||
8922e16c | 830 | return 1; |
1da177e4 | 831 | } |
2e662b65 JA |
832 | EXPORT_SYMBOL(elv_queue_empty); |
833 | ||
165125e1 | 834 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 835 | { |
1da177e4 LT |
836 | elevator_t *e = q->elevator; |
837 | ||
838 | if (e->ops->elevator_latter_req_fn) | |
839 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
840 | return NULL; |
841 | } | |
842 | ||
165125e1 | 843 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 844 | { |
1da177e4 LT |
845 | elevator_t *e = q->elevator; |
846 | ||
847 | if (e->ops->elevator_former_req_fn) | |
848 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
849 | return NULL; |
850 | } | |
851 | ||
165125e1 | 852 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
853 | { |
854 | elevator_t *e = q->elevator; | |
855 | ||
856 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 857 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
858 | |
859 | rq->elevator_private = NULL; | |
860 | return 0; | |
861 | } | |
862 | ||
165125e1 | 863 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
864 | { |
865 | elevator_t *e = q->elevator; | |
866 | ||
867 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 868 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
869 | } |
870 | ||
165125e1 | 871 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 LT |
872 | { |
873 | elevator_t *e = q->elevator; | |
874 | ||
875 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 876 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
877 | |
878 | return ELV_MQUEUE_MAY; | |
879 | } | |
880 | ||
165125e1 | 881 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
882 | { |
883 | elevator_t *e = q->elevator; | |
884 | ||
885 | /* | |
886 | * request is released from the driver, io must be done | |
887 | */ | |
8922e16c | 888 | if (blk_account_rq(rq)) { |
1da177e4 | 889 | q->in_flight--; |
1bc691d3 TH |
890 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
891 | e->ops->elevator_completed_req_fn(q, rq); | |
892 | } | |
797e7dbb | 893 | |
1bc691d3 TH |
894 | /* |
895 | * Check if the queue is waiting for fs requests to be | |
896 | * drained for flush sequence. | |
897 | */ | |
898 | if (unlikely(q->ordseq)) { | |
899 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
900 | if (q->in_flight == 0 && | |
797e7dbb TH |
901 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
902 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
903 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
904 | q->request_fn(q); | |
905 | } | |
8922e16c | 906 | } |
1da177e4 LT |
907 | } |
908 | ||
3d1ab40f AV |
909 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
910 | ||
911 | static ssize_t | |
912 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 913 | { |
3d1ab40f AV |
914 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
915 | struct elv_fs_entry *entry = to_elv(attr); | |
916 | ssize_t error; | |
917 | ||
918 | if (!entry->show) | |
919 | return -EIO; | |
920 | ||
921 | mutex_lock(&e->sysfs_lock); | |
922 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
923 | mutex_unlock(&e->sysfs_lock); | |
924 | return error; | |
925 | } | |
1da177e4 | 926 | |
3d1ab40f AV |
927 | static ssize_t |
928 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
929 | const char *page, size_t length) | |
930 | { | |
931 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
932 | struct elv_fs_entry *entry = to_elv(attr); | |
933 | ssize_t error; | |
1da177e4 | 934 | |
3d1ab40f AV |
935 | if (!entry->store) |
936 | return -EIO; | |
1da177e4 | 937 | |
3d1ab40f AV |
938 | mutex_lock(&e->sysfs_lock); |
939 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
940 | mutex_unlock(&e->sysfs_lock); | |
941 | return error; | |
942 | } | |
943 | ||
944 | static struct sysfs_ops elv_sysfs_ops = { | |
945 | .show = elv_attr_show, | |
946 | .store = elv_attr_store, | |
947 | }; | |
948 | ||
949 | static struct kobj_type elv_ktype = { | |
950 | .sysfs_ops = &elv_sysfs_ops, | |
951 | .release = elevator_release, | |
952 | }; | |
953 | ||
954 | int elv_register_queue(struct request_queue *q) | |
955 | { | |
956 | elevator_t *e = q->elevator; | |
957 | int error; | |
958 | ||
b2d6db58 | 959 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 960 | if (!error) { |
e572ec7e | 961 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 962 | if (attr) { |
e572ec7e AV |
963 | while (attr->attr.name) { |
964 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 965 | break; |
e572ec7e | 966 | attr++; |
3d1ab40f AV |
967 | } |
968 | } | |
969 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
970 | } | |
971 | return error; | |
1da177e4 LT |
972 | } |
973 | ||
bc1c1169 JA |
974 | static void __elv_unregister_queue(elevator_t *e) |
975 | { | |
976 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
977 | kobject_del(&e->kobj); | |
978 | } | |
979 | ||
1da177e4 LT |
980 | void elv_unregister_queue(struct request_queue *q) |
981 | { | |
bc1c1169 JA |
982 | if (q) |
983 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
984 | } |
985 | ||
2fdd82bd | 986 | void elv_register(struct elevator_type *e) |
1da177e4 | 987 | { |
1ffb96c5 | 988 | char *def = ""; |
2a12dcd7 JA |
989 | |
990 | spin_lock(&elv_list_lock); | |
ce524497 | 991 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 992 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 993 | spin_unlock(&elv_list_lock); |
1da177e4 | 994 | |
5f003976 ND |
995 | if (!strcmp(e->elevator_name, chosen_elevator) || |
996 | (!*chosen_elevator && | |
997 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
998 | def = " (default)"; |
999 | ||
4eb166d9 JA |
1000 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1001 | def); | |
1da177e4 LT |
1002 | } |
1003 | EXPORT_SYMBOL_GPL(elv_register); | |
1004 | ||
1005 | void elv_unregister(struct elevator_type *e) | |
1006 | { | |
83521d3e CH |
1007 | struct task_struct *g, *p; |
1008 | ||
1009 | /* | |
1010 | * Iterate every thread in the process to remove the io contexts. | |
1011 | */ | |
e17a9489 AV |
1012 | if (e->ops.trim) { |
1013 | read_lock(&tasklist_lock); | |
1014 | do_each_thread(g, p) { | |
1015 | task_lock(p); | |
2d8f6131 ON |
1016 | if (p->io_context) |
1017 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1018 | task_unlock(p); |
1019 | } while_each_thread(g, p); | |
1020 | read_unlock(&tasklist_lock); | |
1021 | } | |
83521d3e | 1022 | |
2a12dcd7 | 1023 | spin_lock(&elv_list_lock); |
1da177e4 | 1024 | list_del_init(&e->list); |
2a12dcd7 | 1025 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1026 | } |
1027 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1028 | ||
1029 | /* | |
1030 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1031 | * we don't free the old io scheduler, before we have allocated what we | |
1032 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1033 | * one, if the new one fails init for some reason. |
1da177e4 | 1034 | */ |
165125e1 | 1035 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1036 | { |
cb98fc8b | 1037 | elevator_t *old_elevator, *e; |
bc1c1169 | 1038 | void *data; |
1da177e4 | 1039 | |
cb98fc8b TH |
1040 | /* |
1041 | * Allocate new elevator | |
1042 | */ | |
b5deef90 | 1043 | e = elevator_alloc(q, new_e); |
1da177e4 | 1044 | if (!e) |
3d1ab40f | 1045 | return 0; |
1da177e4 | 1046 | |
bc1c1169 JA |
1047 | data = elevator_init_queue(q, e); |
1048 | if (!data) { | |
1049 | kobject_put(&e->kobj); | |
1050 | return 0; | |
1051 | } | |
1052 | ||
1da177e4 | 1053 | /* |
cb98fc8b | 1054 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1055 | */ |
cb98fc8b TH |
1056 | spin_lock_irq(q->queue_lock); |
1057 | ||
64521d1a | 1058 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 1059 | |
15853af9 | 1060 | elv_drain_elevator(q); |
cb98fc8b TH |
1061 | |
1062 | while (q->rq.elvpriv) { | |
407df2aa TH |
1063 | blk_remove_plug(q); |
1064 | q->request_fn(q); | |
cb98fc8b | 1065 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1066 | msleep(10); |
cb98fc8b | 1067 | spin_lock_irq(q->queue_lock); |
15853af9 | 1068 | elv_drain_elevator(q); |
cb98fc8b TH |
1069 | } |
1070 | ||
1da177e4 | 1071 | /* |
bc1c1169 | 1072 | * Remember old elevator. |
1da177e4 | 1073 | */ |
1da177e4 LT |
1074 | old_elevator = q->elevator; |
1075 | ||
1da177e4 LT |
1076 | /* |
1077 | * attach and start new elevator | |
1078 | */ | |
bc1c1169 JA |
1079 | elevator_attach(q, e, data); |
1080 | ||
1081 | spin_unlock_irq(q->queue_lock); | |
1082 | ||
1083 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1084 | |
1085 | if (elv_register_queue(q)) | |
1086 | goto fail_register; | |
1087 | ||
1088 | /* | |
cb98fc8b | 1089 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1090 | */ |
1091 | elevator_exit(old_elevator); | |
64521d1a | 1092 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1093 | return 1; |
1da177e4 LT |
1094 | |
1095 | fail_register: | |
1096 | /* | |
1097 | * switch failed, exit the new io scheduler and reattach the old | |
1098 | * one again (along with re-adding the sysfs dir) | |
1099 | */ | |
1100 | elevator_exit(e); | |
1da177e4 LT |
1101 | q->elevator = old_elevator; |
1102 | elv_register_queue(q); | |
64521d1a | 1103 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1104 | return 0; |
1da177e4 LT |
1105 | } |
1106 | ||
165125e1 JA |
1107 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1108 | size_t count) | |
1da177e4 LT |
1109 | { |
1110 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1111 | size_t len; |
1da177e4 LT |
1112 | struct elevator_type *e; |
1113 | ||
be561235 TH |
1114 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1115 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1116 | len = strlen(elevator_name); | |
1da177e4 | 1117 | |
be561235 TH |
1118 | if (len && elevator_name[len - 1] == '\n') |
1119 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1120 | |
1121 | e = elevator_get(elevator_name); | |
1122 | if (!e) { | |
1123 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1124 | return -EINVAL; | |
1125 | } | |
1126 | ||
2ca7d93b ND |
1127 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1128 | elevator_put(e); | |
1da177e4 | 1129 | return count; |
2ca7d93b | 1130 | } |
1da177e4 | 1131 | |
3d1ab40f | 1132 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1133 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1134 | elevator_name); | |
1da177e4 LT |
1135 | return count; |
1136 | } | |
1137 | ||
165125e1 | 1138 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 LT |
1139 | { |
1140 | elevator_t *e = q->elevator; | |
1141 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1142 | struct elevator_type *__e; |
1da177e4 LT |
1143 | int len = 0; |
1144 | ||
2a12dcd7 | 1145 | spin_lock(&elv_list_lock); |
70cee26e | 1146 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1147 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1148 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1149 | else | |
1150 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1151 | } | |
2a12dcd7 | 1152 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1153 | |
1154 | len += sprintf(len+name, "\n"); | |
1155 | return len; | |
1156 | } | |
1157 | ||
165125e1 JA |
1158 | struct request *elv_rb_former_request(struct request_queue *q, |
1159 | struct request *rq) | |
2e662b65 JA |
1160 | { |
1161 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1162 | ||
1163 | if (rbprev) | |
1164 | return rb_entry_rq(rbprev); | |
1165 | ||
1166 | return NULL; | |
1167 | } | |
2e662b65 JA |
1168 | EXPORT_SYMBOL(elv_rb_former_request); |
1169 | ||
165125e1 JA |
1170 | struct request *elv_rb_latter_request(struct request_queue *q, |
1171 | struct request *rq) | |
2e662b65 JA |
1172 | { |
1173 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1174 | ||
1175 | if (rbnext) | |
1176 | return rb_entry_rq(rbnext); | |
1177 | ||
1178 | return NULL; | |
1179 | } | |
2e662b65 | 1180 | EXPORT_SYMBOL(elv_rb_latter_request); |