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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> | |
2056a782 | 34 | #include <linux/blktrace_api.h> |
9817064b | 35 | #include <linux/hash.h> |
0835da67 | 36 | #include <linux/uaccess.h> |
1da177e4 | 37 | |
55782138 LZ |
38 | #include <trace/events/block.h> |
39 | ||
242f9dcb JA |
40 | #include "blk.h" |
41 | ||
1da177e4 LT |
42 | static DEFINE_SPINLOCK(elv_list_lock); |
43 | static LIST_HEAD(elv_list); | |
44 | ||
9817064b JA |
45 | /* |
46 | * Merge hash stuff. | |
47 | */ | |
48 | static const int elv_hash_shift = 6; | |
49 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
50 | #define ELV_HASH_FN(sec) \ |
51 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b | 52 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
83096ebf | 53 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 54 | |
da775265 JA |
55 | /* |
56 | * Query io scheduler to see if the current process issuing bio may be | |
57 | * merged with rq. | |
58 | */ | |
59 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
60 | { | |
165125e1 | 61 | struct request_queue *q = rq->q; |
b374d18a | 62 | struct elevator_queue *e = q->elevator; |
da775265 | 63 | |
22f746e2 TH |
64 | if (e->type->ops.elevator_allow_merge_fn) |
65 | return e->type->ops.elevator_allow_merge_fn(q, rq, bio); | |
da775265 JA |
66 | |
67 | return 1; | |
68 | } | |
69 | ||
1da177e4 LT |
70 | /* |
71 | * can we safely merge with this request? | |
72 | */ | |
72ed0bf6 | 73 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
74 | { |
75 | if (!rq_mergeable(rq)) | |
76 | return 0; | |
77 | ||
e17fc0a1 DW |
78 | /* |
79 | * Don't merge file system requests and discard requests | |
80 | */ | |
7b6d91da | 81 | if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD)) |
e17fc0a1 DW |
82 | return 0; |
83 | ||
8d57a98c AH |
84 | /* |
85 | * Don't merge discard requests and secure discard requests | |
86 | */ | |
87 | if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE)) | |
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 | ||
73c10101 | 115 | 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)) { | |
83096ebf | 123 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
1da177e4 | 124 | ret = ELEVATOR_BACK_MERGE; |
83096ebf | 125 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
1da177e4 LT |
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 | 156 | if (!e) { |
e1640949 | 157 | spin_unlock(&elv_list_lock); |
490b94be | 158 | request_module("%s-iosched", name); |
e1640949 JA |
159 | spin_lock(&elv_list_lock); |
160 | e = elevator_find(name); | |
161 | } | |
162 | ||
2824bc93 TH |
163 | if (e && !try_module_get(e->elevator_owner)) |
164 | e = NULL; | |
165 | ||
2a12dcd7 | 166 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
167 | |
168 | return e; | |
169 | } | |
170 | ||
f8fc877d TH |
171 | static int elevator_init_queue(struct request_queue *q, |
172 | struct elevator_queue *eq) | |
1da177e4 | 173 | { |
22f746e2 | 174 | eq->elevator_data = eq->type->ops.elevator_init_fn(q); |
f8fc877d TH |
175 | if (eq->elevator_data) |
176 | return 0; | |
177 | return -ENOMEM; | |
1da177e4 LT |
178 | } |
179 | ||
484fc254 | 180 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 181 | |
5f003976 | 182 | static int __init elevator_setup(char *str) |
1da177e4 | 183 | { |
752a3b79 CE |
184 | /* |
185 | * Be backwards-compatible with previous kernels, so users | |
186 | * won't get the wrong elevator. | |
187 | */ | |
492af635 | 188 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 189 | return 1; |
1da177e4 LT |
190 | } |
191 | ||
192 | __setup("elevator=", elevator_setup); | |
193 | ||
3d1ab40f AV |
194 | static struct kobj_type elv_ktype; |
195 | ||
b374d18a | 196 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 197 | struct elevator_type *e) |
3d1ab40f | 198 | { |
b374d18a | 199 | struct elevator_queue *eq; |
9817064b JA |
200 | int i; |
201 | ||
b374d18a | 202 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
203 | if (unlikely(!eq)) |
204 | goto err; | |
205 | ||
22f746e2 | 206 | eq->type = e; |
f9cb074b | 207 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
208 | mutex_init(&eq->sysfs_lock); |
209 | ||
b5deef90 JA |
210 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
211 | GFP_KERNEL, q->node); | |
9817064b JA |
212 | if (!eq->hash) |
213 | goto err; | |
214 | ||
215 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
216 | INIT_HLIST_HEAD(&eq->hash[i]); | |
217 | ||
3d1ab40f | 218 | return eq; |
9817064b JA |
219 | err: |
220 | kfree(eq); | |
221 | elevator_put(e); | |
222 | return NULL; | |
3d1ab40f AV |
223 | } |
224 | ||
225 | static void elevator_release(struct kobject *kobj) | |
226 | { | |
b374d18a | 227 | struct elevator_queue *e; |
9817064b | 228 | |
b374d18a | 229 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 230 | elevator_put(e->type); |
9817064b | 231 | kfree(e->hash); |
3d1ab40f AV |
232 | kfree(e); |
233 | } | |
234 | ||
165125e1 | 235 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
236 | { |
237 | struct elevator_type *e = NULL; | |
238 | struct elevator_queue *eq; | |
f8fc877d | 239 | int err; |
1da177e4 | 240 | |
1abec4fd MS |
241 | if (unlikely(q->elevator)) |
242 | return 0; | |
243 | ||
cb98fc8b TH |
244 | INIT_LIST_HEAD(&q->queue_head); |
245 | q->last_merge = NULL; | |
246 | q->end_sector = 0; | |
247 | q->boundary_rq = NULL; | |
cb98fc8b | 248 | |
4eb166d9 JA |
249 | if (name) { |
250 | e = elevator_get(name); | |
251 | if (!e) | |
252 | return -EINVAL; | |
253 | } | |
1da177e4 | 254 | |
4eb166d9 JA |
255 | if (!e && *chosen_elevator) { |
256 | e = elevator_get(chosen_elevator); | |
257 | if (!e) | |
258 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
259 | chosen_elevator); | |
260 | } | |
248d5ca5 | 261 | |
4eb166d9 JA |
262 | if (!e) { |
263 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
264 | if (!e) { | |
265 | printk(KERN_ERR | |
266 | "Default I/O scheduler not found. " \ | |
267 | "Using noop.\n"); | |
268 | e = elevator_get("noop"); | |
269 | } | |
5f003976 ND |
270 | } |
271 | ||
b5deef90 | 272 | eq = elevator_alloc(q, e); |
3d1ab40f | 273 | if (!eq) |
1da177e4 | 274 | return -ENOMEM; |
1da177e4 | 275 | |
f8fc877d TH |
276 | err = elevator_init_queue(q, eq); |
277 | if (err) { | |
3d1ab40f | 278 | kobject_put(&eq->kobj); |
f8fc877d | 279 | return err; |
bc1c1169 | 280 | } |
1da177e4 | 281 | |
f8fc877d | 282 | q->elevator = eq; |
1abec4fd | 283 | return 0; |
1da177e4 | 284 | } |
2e662b65 JA |
285 | EXPORT_SYMBOL(elevator_init); |
286 | ||
b374d18a | 287 | void elevator_exit(struct elevator_queue *e) |
1da177e4 | 288 | { |
3d1ab40f | 289 | mutex_lock(&e->sysfs_lock); |
22f746e2 TH |
290 | if (e->type->ops.elevator_exit_fn) |
291 | e->type->ops.elevator_exit_fn(e); | |
3d1ab40f | 292 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 293 | |
3d1ab40f | 294 | kobject_put(&e->kobj); |
1da177e4 | 295 | } |
2e662b65 JA |
296 | EXPORT_SYMBOL(elevator_exit); |
297 | ||
9817064b JA |
298 | static inline void __elv_rqhash_del(struct request *rq) |
299 | { | |
300 | hlist_del_init(&rq->hash); | |
301 | } | |
302 | ||
165125e1 | 303 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
304 | { |
305 | if (ELV_ON_HASH(rq)) | |
306 | __elv_rqhash_del(rq); | |
307 | } | |
308 | ||
165125e1 | 309 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 310 | { |
b374d18a | 311 | struct elevator_queue *e = q->elevator; |
9817064b JA |
312 | |
313 | BUG_ON(ELV_ON_HASH(rq)); | |
314 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
315 | } | |
316 | ||
165125e1 | 317 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
318 | { |
319 | __elv_rqhash_del(rq); | |
320 | elv_rqhash_add(q, rq); | |
321 | } | |
322 | ||
165125e1 | 323 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 324 | { |
b374d18a | 325 | struct elevator_queue *e = q->elevator; |
9817064b JA |
326 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
327 | struct hlist_node *entry, *next; | |
328 | struct request *rq; | |
329 | ||
330 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
331 | BUG_ON(!ELV_ON_HASH(rq)); | |
332 | ||
333 | if (unlikely(!rq_mergeable(rq))) { | |
334 | __elv_rqhash_del(rq); | |
335 | continue; | |
336 | } | |
337 | ||
338 | if (rq_hash_key(rq) == offset) | |
339 | return rq; | |
340 | } | |
341 | ||
342 | return NULL; | |
343 | } | |
344 | ||
2e662b65 JA |
345 | /* |
346 | * RB-tree support functions for inserting/lookup/removal of requests | |
347 | * in a sorted RB tree. | |
348 | */ | |
796d5116 | 349 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
350 | { |
351 | struct rb_node **p = &root->rb_node; | |
352 | struct rb_node *parent = NULL; | |
353 | struct request *__rq; | |
354 | ||
355 | while (*p) { | |
356 | parent = *p; | |
357 | __rq = rb_entry(parent, struct request, rb_node); | |
358 | ||
83096ebf | 359 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 360 | p = &(*p)->rb_left; |
796d5116 | 361 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 362 | p = &(*p)->rb_right; |
2e662b65 JA |
363 | } |
364 | ||
365 | rb_link_node(&rq->rb_node, parent, p); | |
366 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 367 | } |
2e662b65 JA |
368 | EXPORT_SYMBOL(elv_rb_add); |
369 | ||
370 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
371 | { | |
372 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
373 | rb_erase(&rq->rb_node, root); | |
374 | RB_CLEAR_NODE(&rq->rb_node); | |
375 | } | |
2e662b65 JA |
376 | EXPORT_SYMBOL(elv_rb_del); |
377 | ||
378 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
379 | { | |
380 | struct rb_node *n = root->rb_node; | |
381 | struct request *rq; | |
382 | ||
383 | while (n) { | |
384 | rq = rb_entry(n, struct request, rb_node); | |
385 | ||
83096ebf | 386 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 387 | n = n->rb_left; |
83096ebf | 388 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
389 | n = n->rb_right; |
390 | else | |
391 | return rq; | |
392 | } | |
393 | ||
394 | return NULL; | |
395 | } | |
2e662b65 JA |
396 | EXPORT_SYMBOL(elv_rb_find); |
397 | ||
8922e16c TH |
398 | /* |
399 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 400 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 401 | * specific elevators. |
8922e16c | 402 | */ |
165125e1 | 403 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
404 | { |
405 | sector_t boundary; | |
8922e16c | 406 | struct list_head *entry; |
4eb166d9 | 407 | int stop_flags; |
8922e16c | 408 | |
06b86245 TH |
409 | if (q->last_merge == rq) |
410 | q->last_merge = NULL; | |
9817064b JA |
411 | |
412 | elv_rqhash_del(q, rq); | |
413 | ||
15853af9 | 414 | q->nr_sorted--; |
06b86245 | 415 | |
1b47f531 | 416 | boundary = q->end_sector; |
02e031cb | 417 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
8922e16c TH |
418 | list_for_each_prev(entry, &q->queue_head) { |
419 | struct request *pos = list_entry_rq(entry); | |
420 | ||
33659ebb CH |
421 | if ((rq->cmd_flags & REQ_DISCARD) != |
422 | (pos->cmd_flags & REQ_DISCARD)) | |
e17fc0a1 | 423 | break; |
783660b2 JA |
424 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
425 | break; | |
4eb166d9 | 426 | if (pos->cmd_flags & stop_flags) |
8922e16c | 427 | break; |
83096ebf TH |
428 | if (blk_rq_pos(rq) >= boundary) { |
429 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
430 | continue; |
431 | } else { | |
83096ebf | 432 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
433 | break; |
434 | } | |
83096ebf | 435 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
436 | break; |
437 | } | |
438 | ||
439 | list_add(&rq->queuelist, entry); | |
440 | } | |
2e662b65 JA |
441 | EXPORT_SYMBOL(elv_dispatch_sort); |
442 | ||
9817064b | 443 | /* |
2e662b65 JA |
444 | * Insert rq into dispatch queue of q. Queue lock must be held on |
445 | * entry. rq is added to the back of the dispatch queue. To be used by | |
446 | * specific elevators. | |
9817064b JA |
447 | */ |
448 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
449 | { | |
450 | if (q->last_merge == rq) | |
451 | q->last_merge = NULL; | |
452 | ||
453 | elv_rqhash_del(q, rq); | |
454 | ||
455 | q->nr_sorted--; | |
456 | ||
457 | q->end_sector = rq_end_sector(rq); | |
458 | q->boundary_rq = rq; | |
459 | list_add_tail(&rq->queuelist, &q->queue_head); | |
460 | } | |
2e662b65 JA |
461 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
462 | ||
165125e1 | 463 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 | 464 | { |
b374d18a | 465 | struct elevator_queue *e = q->elevator; |
9817064b | 466 | struct request *__rq; |
06b86245 TH |
467 | int ret; |
468 | ||
488991e2 AB |
469 | /* |
470 | * Levels of merges: | |
471 | * nomerges: No merges at all attempted | |
472 | * noxmerges: Only simple one-hit cache try | |
473 | * merges: All merge tries attempted | |
474 | */ | |
475 | if (blk_queue_nomerges(q)) | |
476 | return ELEVATOR_NO_MERGE; | |
477 | ||
9817064b JA |
478 | /* |
479 | * First try one-hit cache. | |
480 | */ | |
06b86245 TH |
481 | if (q->last_merge) { |
482 | ret = elv_try_merge(q->last_merge, bio); | |
483 | if (ret != ELEVATOR_NO_MERGE) { | |
484 | *req = q->last_merge; | |
485 | return ret; | |
486 | } | |
487 | } | |
1da177e4 | 488 | |
488991e2 | 489 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
490 | return ELEVATOR_NO_MERGE; |
491 | ||
9817064b JA |
492 | /* |
493 | * See if our hash lookup can find a potential backmerge. | |
494 | */ | |
495 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
496 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
497 | *req = __rq; | |
498 | return ELEVATOR_BACK_MERGE; | |
499 | } | |
500 | ||
22f746e2 TH |
501 | if (e->type->ops.elevator_merge_fn) |
502 | return e->type->ops.elevator_merge_fn(q, req, bio); | |
1da177e4 LT |
503 | |
504 | return ELEVATOR_NO_MERGE; | |
505 | } | |
506 | ||
5e84ea3a JA |
507 | /* |
508 | * Attempt to do an insertion back merge. Only check for the case where | |
509 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
510 | * afterwards. | |
511 | * | |
512 | * Returns true if we merged, false otherwise | |
513 | */ | |
514 | static bool elv_attempt_insert_merge(struct request_queue *q, | |
515 | struct request *rq) | |
516 | { | |
517 | struct request *__rq; | |
518 | ||
519 | if (blk_queue_nomerges(q)) | |
520 | return false; | |
521 | ||
522 | /* | |
523 | * First try one-hit cache. | |
524 | */ | |
525 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
526 | return true; | |
527 | ||
528 | if (blk_queue_noxmerges(q)) | |
529 | return false; | |
530 | ||
531 | /* | |
532 | * See if our hash lookup can find a potential backmerge. | |
533 | */ | |
534 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
535 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) | |
536 | return true; | |
537 | ||
538 | return false; | |
539 | } | |
540 | ||
165125e1 | 541 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 | 542 | { |
b374d18a | 543 | struct elevator_queue *e = q->elevator; |
1da177e4 | 544 | |
22f746e2 TH |
545 | if (e->type->ops.elevator_merged_fn) |
546 | e->type->ops.elevator_merged_fn(q, rq, type); | |
06b86245 | 547 | |
2e662b65 JA |
548 | if (type == ELEVATOR_BACK_MERGE) |
549 | elv_rqhash_reposition(q, rq); | |
9817064b | 550 | |
06b86245 | 551 | q->last_merge = rq; |
1da177e4 LT |
552 | } |
553 | ||
165125e1 | 554 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
555 | struct request *next) |
556 | { | |
b374d18a | 557 | struct elevator_queue *e = q->elevator; |
5e84ea3a | 558 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
1da177e4 | 559 | |
22f746e2 TH |
560 | if (next_sorted && e->type->ops.elevator_merge_req_fn) |
561 | e->type->ops.elevator_merge_req_fn(q, rq, next); | |
06b86245 | 562 | |
9817064b | 563 | elv_rqhash_reposition(q, rq); |
9817064b | 564 | |
5e84ea3a JA |
565 | if (next_sorted) { |
566 | elv_rqhash_del(q, next); | |
567 | q->nr_sorted--; | |
568 | } | |
569 | ||
06b86245 | 570 | q->last_merge = rq; |
1da177e4 LT |
571 | } |
572 | ||
812d4026 DS |
573 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
574 | struct bio *bio) | |
575 | { | |
576 | struct elevator_queue *e = q->elevator; | |
577 | ||
22f746e2 TH |
578 | if (e->type->ops.elevator_bio_merged_fn) |
579 | e->type->ops.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
580 | } |
581 | ||
165125e1 | 582 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 583 | { |
1da177e4 LT |
584 | /* |
585 | * it already went through dequeue, we need to decrement the | |
586 | * in_flight count again | |
587 | */ | |
8922e16c | 588 | if (blk_account_rq(rq)) { |
0a7ae2ff | 589 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 590 | if (rq->cmd_flags & REQ_SORTED) |
cad97516 | 591 | elv_deactivate_rq(q, rq); |
8922e16c | 592 | } |
1da177e4 | 593 | |
4aff5e23 | 594 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 595 | |
b710a480 | 596 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
597 | } |
598 | ||
26308eab | 599 | void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
600 | { |
601 | static int printed; | |
e3c78ca5 TH |
602 | |
603 | lockdep_assert_held(q->queue_lock); | |
604 | ||
22f746e2 | 605 | while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
15853af9 | 606 | ; |
e3c78ca5 | 607 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
608 | printk(KERN_ERR "%s: forced dispatching is broken " |
609 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 610 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
611 | } |
612 | } | |
613 | ||
f600abe2 | 614 | void elv_quiesce_start(struct request_queue *q) |
6c7e8cee | 615 | { |
cd43e26f MP |
616 | if (!q->elevator) |
617 | return; | |
618 | ||
e3c78ca5 | 619 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 620 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 621 | spin_unlock_irq(q->queue_lock); |
6c7e8cee | 622 | |
c9a929dd | 623 | blk_drain_queue(q, false); |
6c7e8cee JA |
624 | } |
625 | ||
f600abe2 | 626 | void elv_quiesce_end(struct request_queue *q) |
6c7e8cee | 627 | { |
e3c78ca5 | 628 | spin_lock_irq(q->queue_lock); |
6c7e8cee | 629 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
e3c78ca5 | 630 | spin_unlock_irq(q->queue_lock); |
6c7e8cee JA |
631 | } |
632 | ||
b710a480 | 633 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 634 | { |
5f3ea37c | 635 | trace_block_rq_insert(q, rq); |
2056a782 | 636 | |
1da177e4 LT |
637 | rq->q = q; |
638 | ||
b710a480 JA |
639 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
640 | /* barriers are scheduling boundary, update end_sector */ | |
641 | if (rq->cmd_type == REQ_TYPE_FS || | |
642 | (rq->cmd_flags & REQ_DISCARD)) { | |
643 | q->end_sector = rq_end_sector(rq); | |
644 | q->boundary_rq = rq; | |
645 | } | |
646 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && | |
3aa72873 JA |
647 | (where == ELEVATOR_INSERT_SORT || |
648 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
649 | where = ELEVATOR_INSERT_BACK; |
650 | ||
8922e16c | 651 | switch (where) { |
28e7d184 | 652 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 653 | case ELEVATOR_INSERT_FRONT: |
4aff5e23 | 654 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
655 | list_add(&rq->queuelist, &q->queue_head); |
656 | break; | |
657 | ||
658 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 659 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 660 | elv_drain_elevator(q); |
8922e16c TH |
661 | list_add_tail(&rq->queuelist, &q->queue_head); |
662 | /* | |
663 | * We kick the queue here for the following reasons. | |
664 | * - The elevator might have returned NULL previously | |
665 | * to delay requests and returned them now. As the | |
666 | * queue wasn't empty before this request, ll_rw_blk | |
667 | * won't run the queue on return, resulting in hang. | |
668 | * - Usually, back inserted requests won't be merged | |
669 | * with anything. There's no point in delaying queue | |
670 | * processing. | |
671 | */ | |
24ecfbe2 | 672 | __blk_run_queue(q); |
8922e16c TH |
673 | break; |
674 | ||
5e84ea3a JA |
675 | case ELEVATOR_INSERT_SORT_MERGE: |
676 | /* | |
677 | * If we succeed in merging this request with one in the | |
678 | * queue already, we are done - rq has now been freed, | |
679 | * so no need to do anything further. | |
680 | */ | |
681 | if (elv_attempt_insert_merge(q, rq)) | |
682 | break; | |
8922e16c | 683 | case ELEVATOR_INSERT_SORT: |
33659ebb CH |
684 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
685 | !(rq->cmd_flags & REQ_DISCARD)); | |
4aff5e23 | 686 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 687 | q->nr_sorted++; |
9817064b JA |
688 | if (rq_mergeable(rq)) { |
689 | elv_rqhash_add(q, rq); | |
690 | if (!q->last_merge) | |
691 | q->last_merge = rq; | |
692 | } | |
693 | ||
ca23509f TH |
694 | /* |
695 | * Some ioscheds (cfq) run q->request_fn directly, so | |
696 | * rq cannot be accessed after calling | |
697 | * elevator_add_req_fn. | |
698 | */ | |
22f746e2 | 699 | q->elevator->type->ops.elevator_add_req_fn(q, rq); |
8922e16c TH |
700 | break; |
701 | ||
ae1b1539 TH |
702 | case ELEVATOR_INSERT_FLUSH: |
703 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
704 | blk_insert_flush(rq); | |
705 | break; | |
8922e16c TH |
706 | default: |
707 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 708 | __func__, where); |
8922e16c TH |
709 | BUG(); |
710 | } | |
1da177e4 | 711 | } |
2e662b65 JA |
712 | EXPORT_SYMBOL(__elv_add_request); |
713 | ||
7eaceacc | 714 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
715 | { |
716 | unsigned long flags; | |
717 | ||
718 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 719 | __elv_add_request(q, rq, where); |
1da177e4 LT |
720 | spin_unlock_irqrestore(q->queue_lock, flags); |
721 | } | |
2e662b65 JA |
722 | EXPORT_SYMBOL(elv_add_request); |
723 | ||
165125e1 | 724 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 725 | { |
b374d18a | 726 | struct elevator_queue *e = q->elevator; |
1da177e4 | 727 | |
22f746e2 TH |
728 | if (e->type->ops.elevator_latter_req_fn) |
729 | return e->type->ops.elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
730 | return NULL; |
731 | } | |
732 | ||
165125e1 | 733 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 734 | { |
b374d18a | 735 | struct elevator_queue *e = q->elevator; |
1da177e4 | 736 | |
22f746e2 TH |
737 | if (e->type->ops.elevator_former_req_fn) |
738 | return e->type->ops.elevator_former_req_fn(q, rq); | |
1da177e4 LT |
739 | return NULL; |
740 | } | |
741 | ||
165125e1 | 742 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 | 743 | { |
b374d18a | 744 | struct elevator_queue *e = q->elevator; |
1da177e4 | 745 | |
22f746e2 TH |
746 | if (e->type->ops.elevator_set_req_fn) |
747 | return e->type->ops.elevator_set_req_fn(q, rq, gfp_mask); | |
1da177e4 LT |
748 | return 0; |
749 | } | |
750 | ||
165125e1 | 751 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 752 | { |
b374d18a | 753 | struct elevator_queue *e = q->elevator; |
1da177e4 | 754 | |
22f746e2 TH |
755 | if (e->type->ops.elevator_put_req_fn) |
756 | e->type->ops.elevator_put_req_fn(rq); | |
1da177e4 LT |
757 | } |
758 | ||
165125e1 | 759 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 | 760 | { |
b374d18a | 761 | struct elevator_queue *e = q->elevator; |
1da177e4 | 762 | |
22f746e2 TH |
763 | if (e->type->ops.elevator_may_queue_fn) |
764 | return e->type->ops.elevator_may_queue_fn(q, rw); | |
1da177e4 LT |
765 | |
766 | return ELV_MQUEUE_MAY; | |
767 | } | |
768 | ||
11914a53 MA |
769 | void elv_abort_queue(struct request_queue *q) |
770 | { | |
771 | struct request *rq; | |
772 | ||
ae1b1539 TH |
773 | blk_abort_flushes(q); |
774 | ||
11914a53 MA |
775 | while (!list_empty(&q->queue_head)) { |
776 | rq = list_entry_rq(q->queue_head.next); | |
777 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 778 | trace_block_rq_abort(q, rq); |
53c663ce KU |
779 | /* |
780 | * Mark this request as started so we don't trigger | |
781 | * any debug logic in the end I/O path. | |
782 | */ | |
783 | blk_start_request(rq); | |
40cbbb78 | 784 | __blk_end_request_all(rq, -EIO); |
11914a53 MA |
785 | } |
786 | } | |
787 | EXPORT_SYMBOL(elv_abort_queue); | |
788 | ||
165125e1 | 789 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 790 | { |
b374d18a | 791 | struct elevator_queue *e = q->elevator; |
1da177e4 LT |
792 | |
793 | /* | |
794 | * request is released from the driver, io must be done | |
795 | */ | |
8922e16c | 796 | if (blk_account_rq(rq)) { |
0a7ae2ff | 797 | q->in_flight[rq_is_sync(rq)]--; |
33659ebb | 798 | if ((rq->cmd_flags & REQ_SORTED) && |
22f746e2 TH |
799 | e->type->ops.elevator_completed_req_fn) |
800 | e->type->ops.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 801 | } |
1da177e4 LT |
802 | } |
803 | ||
3d1ab40f AV |
804 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
805 | ||
806 | static ssize_t | |
807 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 808 | { |
3d1ab40f | 809 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 810 | struct elevator_queue *e; |
3d1ab40f AV |
811 | ssize_t error; |
812 | ||
813 | if (!entry->show) | |
814 | return -EIO; | |
815 | ||
b374d18a | 816 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 817 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 818 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
819 | mutex_unlock(&e->sysfs_lock); |
820 | return error; | |
821 | } | |
1da177e4 | 822 | |
3d1ab40f AV |
823 | static ssize_t |
824 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
825 | const char *page, size_t length) | |
826 | { | |
3d1ab40f | 827 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 828 | struct elevator_queue *e; |
3d1ab40f | 829 | ssize_t error; |
1da177e4 | 830 | |
3d1ab40f AV |
831 | if (!entry->store) |
832 | return -EIO; | |
1da177e4 | 833 | |
b374d18a | 834 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 835 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 836 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
837 | mutex_unlock(&e->sysfs_lock); |
838 | return error; | |
839 | } | |
840 | ||
52cf25d0 | 841 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
842 | .show = elv_attr_show, |
843 | .store = elv_attr_store, | |
844 | }; | |
845 | ||
846 | static struct kobj_type elv_ktype = { | |
847 | .sysfs_ops = &elv_sysfs_ops, | |
848 | .release = elevator_release, | |
849 | }; | |
850 | ||
f8fc877d | 851 | int __elv_register_queue(struct request_queue *q, struct elevator_queue *e) |
3d1ab40f | 852 | { |
3d1ab40f AV |
853 | int error; |
854 | ||
b2d6db58 | 855 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 856 | if (!error) { |
22f746e2 | 857 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 858 | if (attr) { |
e572ec7e AV |
859 | while (attr->attr.name) { |
860 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 861 | break; |
e572ec7e | 862 | attr++; |
3d1ab40f AV |
863 | } |
864 | } | |
865 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 866 | e->registered = 1; |
3d1ab40f AV |
867 | } |
868 | return error; | |
1da177e4 LT |
869 | } |
870 | ||
f8fc877d | 871 | int elv_register_queue(struct request_queue *q) |
bc1c1169 | 872 | { |
f8fc877d | 873 | return __elv_register_queue(q, q->elevator); |
bc1c1169 | 874 | } |
f8fc877d | 875 | EXPORT_SYMBOL(elv_register_queue); |
bc1c1169 | 876 | |
1da177e4 LT |
877 | void elv_unregister_queue(struct request_queue *q) |
878 | { | |
f8fc877d TH |
879 | if (q) { |
880 | struct elevator_queue *e = q->elevator; | |
881 | ||
882 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
883 | kobject_del(&e->kobj); | |
884 | e->registered = 0; | |
885 | } | |
1da177e4 | 886 | } |
01effb0d | 887 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 888 | |
2fdd82bd | 889 | void elv_register(struct elevator_type *e) |
1da177e4 | 890 | { |
1ffb96c5 | 891 | char *def = ""; |
2a12dcd7 JA |
892 | |
893 | spin_lock(&elv_list_lock); | |
ce524497 | 894 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 895 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 896 | spin_unlock(&elv_list_lock); |
1da177e4 | 897 | |
5f003976 ND |
898 | if (!strcmp(e->elevator_name, chosen_elevator) || |
899 | (!*chosen_elevator && | |
900 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
901 | def = " (default)"; |
902 | ||
4eb166d9 JA |
903 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
904 | def); | |
1da177e4 LT |
905 | } |
906 | EXPORT_SYMBOL_GPL(elv_register); | |
907 | ||
908 | void elv_unregister(struct elevator_type *e) | |
909 | { | |
2a12dcd7 | 910 | spin_lock(&elv_list_lock); |
1da177e4 | 911 | list_del_init(&e->list); |
2a12dcd7 | 912 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
913 | } |
914 | EXPORT_SYMBOL_GPL(elv_unregister); | |
915 | ||
916 | /* | |
917 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
918 | * we don't free the old io scheduler, before we have allocated what we | |
919 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 920 | * one, if the new one fails init for some reason. |
1da177e4 | 921 | */ |
165125e1 | 922 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 923 | { |
b374d18a | 924 | struct elevator_queue *old_elevator, *e; |
5dd531a0 | 925 | int err; |
1da177e4 | 926 | |
f8fc877d | 927 | /* allocate new elevator */ |
b5deef90 | 928 | e = elevator_alloc(q, new_e); |
1da177e4 | 929 | if (!e) |
5dd531a0 | 930 | return -ENOMEM; |
1da177e4 | 931 | |
f8fc877d TH |
932 | err = elevator_init_queue(q, e); |
933 | if (err) { | |
bc1c1169 | 934 | kobject_put(&e->kobj); |
f8fc877d | 935 | return err; |
bc1c1169 JA |
936 | } |
937 | ||
f8fc877d | 938 | /* turn on BYPASS and drain all requests w/ elevator private data */ |
f600abe2 | 939 | elv_quiesce_start(q); |
cb98fc8b | 940 | |
f8fc877d TH |
941 | /* unregister old queue, register new one and kill old elevator */ |
942 | if (q->elevator->registered) { | |
943 | elv_unregister_queue(q); | |
944 | err = __elv_register_queue(q, e); | |
430c62fb JA |
945 | if (err) |
946 | goto fail_register; | |
947 | } | |
1da177e4 | 948 | |
f8fc877d TH |
949 | /* done, replace the old one with new one and turn off BYPASS */ |
950 | spin_lock_irq(q->queue_lock); | |
951 | old_elevator = q->elevator; | |
952 | q->elevator = e; | |
953 | spin_unlock_irq(q->queue_lock); | |
954 | ||
1da177e4 | 955 | elevator_exit(old_elevator); |
f600abe2 | 956 | elv_quiesce_end(q); |
75ad23bc | 957 | |
22f746e2 | 958 | blk_add_trace_msg(q, "elv switch: %s", e->type->elevator_name); |
4722dc52 | 959 | |
5dd531a0 | 960 | return 0; |
1da177e4 LT |
961 | |
962 | fail_register: | |
963 | /* | |
964 | * switch failed, exit the new io scheduler and reattach the old | |
965 | * one again (along with re-adding the sysfs dir) | |
966 | */ | |
967 | elevator_exit(e); | |
1da177e4 | 968 | elv_register_queue(q); |
e3c78ca5 | 969 | elv_quiesce_end(q); |
75ad23bc | 970 | |
5dd531a0 | 971 | return err; |
1da177e4 LT |
972 | } |
973 | ||
5dd531a0 JA |
974 | /* |
975 | * Switch this queue to the given IO scheduler. | |
976 | */ | |
977 | int elevator_change(struct request_queue *q, const char *name) | |
1da177e4 LT |
978 | { |
979 | char elevator_name[ELV_NAME_MAX]; | |
980 | struct elevator_type *e; | |
981 | ||
cd43e26f | 982 | if (!q->elevator) |
5dd531a0 | 983 | return -ENXIO; |
cd43e26f | 984 | |
ee2e992c | 985 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
8c279598 | 986 | e = elevator_get(strstrip(elevator_name)); |
1da177e4 LT |
987 | if (!e) { |
988 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
989 | return -EINVAL; | |
990 | } | |
991 | ||
22f746e2 | 992 | if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
2ca7d93b | 993 | elevator_put(e); |
5dd531a0 | 994 | return 0; |
2ca7d93b | 995 | } |
1da177e4 | 996 | |
5dd531a0 JA |
997 | return elevator_switch(q, e); |
998 | } | |
999 | EXPORT_SYMBOL(elevator_change); | |
1000 | ||
1001 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
1002 | size_t count) | |
1003 | { | |
1004 | int ret; | |
1005 | ||
1006 | if (!q->elevator) | |
1007 | return count; | |
1008 | ||
1009 | ret = elevator_change(q, name); | |
1010 | if (!ret) | |
1011 | return count; | |
1012 | ||
1013 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
1014 | return ret; | |
1da177e4 LT |
1015 | } |
1016 | ||
165125e1 | 1017 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1018 | { |
b374d18a | 1019 | struct elevator_queue *e = q->elevator; |
cd43e26f | 1020 | struct elevator_type *elv; |
70cee26e | 1021 | struct elevator_type *__e; |
1da177e4 LT |
1022 | int len = 0; |
1023 | ||
e36f724b | 1024 | if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f MP |
1025 | return sprintf(name, "none\n"); |
1026 | ||
22f746e2 | 1027 | elv = e->type; |
cd43e26f | 1028 | |
2a12dcd7 | 1029 | spin_lock(&elv_list_lock); |
70cee26e | 1030 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1031 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1032 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1033 | else | |
1034 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1035 | } | |
2a12dcd7 | 1036 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1037 | |
1038 | len += sprintf(len+name, "\n"); | |
1039 | return len; | |
1040 | } | |
1041 | ||
165125e1 JA |
1042 | struct request *elv_rb_former_request(struct request_queue *q, |
1043 | struct request *rq) | |
2e662b65 JA |
1044 | { |
1045 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1046 | ||
1047 | if (rbprev) | |
1048 | return rb_entry_rq(rbprev); | |
1049 | ||
1050 | return NULL; | |
1051 | } | |
2e662b65 JA |
1052 | EXPORT_SYMBOL(elv_rb_former_request); |
1053 | ||
165125e1 JA |
1054 | struct request *elv_rb_latter_request(struct request_queue *q, |
1055 | struct request *rq) | |
2e662b65 JA |
1056 | { |
1057 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1058 | ||
1059 | if (rbnext) | |
1060 | return rb_entry_rq(rbnext); | |
1061 | ||
1062 | return NULL; | |
1063 | } | |
2e662b65 | 1064 | EXPORT_SYMBOL(elv_rb_latter_request); |