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) | |
48 | #define ELV_HASH_FN(sec) (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
49 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) | |
50 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
51 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
52 | ||
da775265 JA |
53 | /* |
54 | * Query io scheduler to see if the current process issuing bio may be | |
55 | * merged with rq. | |
56 | */ | |
57 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
58 | { | |
59 | request_queue_t *q = rq->q; | |
60 | elevator_t *e = q->elevator; | |
61 | ||
62 | if (e->ops->elevator_allow_merge_fn) | |
63 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
64 | ||
65 | return 1; | |
66 | } | |
67 | ||
1da177e4 LT |
68 | /* |
69 | * can we safely merge with this request? | |
70 | */ | |
71 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) | |
72 | { | |
73 | if (!rq_mergeable(rq)) | |
74 | return 0; | |
75 | ||
76 | /* | |
77 | * different data direction or already started, don't merge | |
78 | */ | |
79 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
80 | return 0; | |
81 | ||
82 | /* | |
da775265 | 83 | * must be same device and not a special request |
1da177e4 | 84 | */ |
da775265 JA |
85 | if (rq->rq_disk != bio->bi_bdev->bd_disk || !rq->special) |
86 | return 0; | |
87 | ||
88 | if (!elv_iosched_allow_merge(rq, bio)) | |
89 | return 0; | |
1da177e4 | 90 | |
da775265 | 91 | return 1; |
1da177e4 LT |
92 | } |
93 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
94 | ||
769db45b | 95 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
96 | { |
97 | int ret = ELEVATOR_NO_MERGE; | |
98 | ||
99 | /* | |
100 | * we can merge and sequence is ok, check if it's possible | |
101 | */ | |
102 | if (elv_rq_merge_ok(__rq, bio)) { | |
103 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
104 | ret = ELEVATOR_BACK_MERGE; | |
105 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
106 | ret = ELEVATOR_FRONT_MERGE; | |
107 | } | |
108 | ||
109 | return ret; | |
110 | } | |
1da177e4 | 111 | |
1da177e4 LT |
112 | static struct elevator_type *elevator_find(const char *name) |
113 | { | |
a22b169d | 114 | struct elevator_type *e; |
1da177e4 LT |
115 | struct list_head *entry; |
116 | ||
1da177e4 | 117 | list_for_each(entry, &elv_list) { |
1da177e4 | 118 | |
a22b169d | 119 | e = list_entry(entry, struct elevator_type, list); |
1da177e4 | 120 | |
a22b169d VT |
121 | if (!strcmp(e->elevator_name, name)) |
122 | return e; | |
1da177e4 | 123 | } |
1da177e4 | 124 | |
a22b169d | 125 | return NULL; |
1da177e4 LT |
126 | } |
127 | ||
128 | static void elevator_put(struct elevator_type *e) | |
129 | { | |
130 | module_put(e->elevator_owner); | |
131 | } | |
132 | ||
133 | static struct elevator_type *elevator_get(const char *name) | |
134 | { | |
2824bc93 | 135 | struct elevator_type *e; |
1da177e4 | 136 | |
2824bc93 TH |
137 | spin_lock_irq(&elv_list_lock); |
138 | ||
139 | e = elevator_find(name); | |
140 | if (e && !try_module_get(e->elevator_owner)) | |
141 | e = NULL; | |
142 | ||
143 | spin_unlock_irq(&elv_list_lock); | |
1da177e4 LT |
144 | |
145 | return e; | |
146 | } | |
147 | ||
bc1c1169 | 148 | static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 | 149 | { |
bb37b94c | 150 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 151 | } |
1da177e4 | 152 | |
bc1c1169 JA |
153 | static void elevator_attach(request_queue_t *q, struct elevator_queue *eq, |
154 | void *data) | |
155 | { | |
1da177e4 | 156 | q->elevator = eq; |
bc1c1169 | 157 | eq->elevator_data = data; |
1da177e4 LT |
158 | } |
159 | ||
160 | static char chosen_elevator[16]; | |
161 | ||
5f003976 | 162 | static int __init elevator_setup(char *str) |
1da177e4 | 163 | { |
752a3b79 CE |
164 | /* |
165 | * Be backwards-compatible with previous kernels, so users | |
166 | * won't get the wrong elevator. | |
167 | */ | |
5f003976 | 168 | if (!strcmp(str, "as")) |
752a3b79 | 169 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 170 | else |
5f003976 | 171 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 172 | return 1; |
1da177e4 LT |
173 | } |
174 | ||
175 | __setup("elevator=", elevator_setup); | |
176 | ||
3d1ab40f AV |
177 | static struct kobj_type elv_ktype; |
178 | ||
b5deef90 | 179 | static elevator_t *elevator_alloc(request_queue_t *q, struct elevator_type *e) |
3d1ab40f | 180 | { |
9817064b JA |
181 | elevator_t *eq; |
182 | int i; | |
183 | ||
b5deef90 | 184 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL, q->node); |
9817064b JA |
185 | if (unlikely(!eq)) |
186 | goto err; | |
187 | ||
188 | memset(eq, 0, sizeof(*eq)); | |
189 | eq->ops = &e->ops; | |
190 | eq->elevator_type = e; | |
191 | kobject_init(&eq->kobj); | |
192 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
193 | eq->kobj.ktype = &elv_ktype; | |
194 | mutex_init(&eq->sysfs_lock); | |
195 | ||
b5deef90 JA |
196 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
197 | GFP_KERNEL, q->node); | |
9817064b JA |
198 | if (!eq->hash) |
199 | goto err; | |
200 | ||
201 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
202 | INIT_HLIST_HEAD(&eq->hash[i]); | |
203 | ||
3d1ab40f | 204 | return eq; |
9817064b JA |
205 | err: |
206 | kfree(eq); | |
207 | elevator_put(e); | |
208 | return NULL; | |
3d1ab40f AV |
209 | } |
210 | ||
211 | static void elevator_release(struct kobject *kobj) | |
212 | { | |
213 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 214 | |
3d1ab40f | 215 | elevator_put(e->elevator_type); |
9817064b | 216 | kfree(e->hash); |
3d1ab40f AV |
217 | kfree(e); |
218 | } | |
219 | ||
1da177e4 LT |
220 | int elevator_init(request_queue_t *q, char *name) |
221 | { | |
222 | struct elevator_type *e = NULL; | |
223 | struct elevator_queue *eq; | |
224 | int ret = 0; | |
bc1c1169 | 225 | void *data; |
1da177e4 | 226 | |
cb98fc8b TH |
227 | INIT_LIST_HEAD(&q->queue_head); |
228 | q->last_merge = NULL; | |
229 | q->end_sector = 0; | |
230 | q->boundary_rq = NULL; | |
cb98fc8b | 231 | |
5f003976 | 232 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
233 | return -EINVAL; |
234 | ||
248d5ca5 ND |
235 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
236 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
237 | ||
238 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
239 | printk("Default I/O scheduler not found, using no-op\n"); | |
240 | e = elevator_get("noop"); | |
5f003976 ND |
241 | } |
242 | ||
b5deef90 | 243 | eq = elevator_alloc(q, e); |
3d1ab40f | 244 | if (!eq) |
1da177e4 | 245 | return -ENOMEM; |
1da177e4 | 246 | |
bc1c1169 JA |
247 | data = elevator_init_queue(q, eq); |
248 | if (!data) { | |
3d1ab40f | 249 | kobject_put(&eq->kobj); |
bc1c1169 JA |
250 | return -ENOMEM; |
251 | } | |
1da177e4 | 252 | |
bc1c1169 | 253 | elevator_attach(q, eq, data); |
1da177e4 LT |
254 | return ret; |
255 | } | |
256 | ||
2e662b65 JA |
257 | EXPORT_SYMBOL(elevator_init); |
258 | ||
1da177e4 LT |
259 | void elevator_exit(elevator_t *e) |
260 | { | |
3d1ab40f | 261 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
262 | if (e->ops->elevator_exit_fn) |
263 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
264 | e->ops = NULL; |
265 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 266 | |
3d1ab40f | 267 | kobject_put(&e->kobj); |
1da177e4 LT |
268 | } |
269 | ||
2e662b65 JA |
270 | EXPORT_SYMBOL(elevator_exit); |
271 | ||
9817064b JA |
272 | static inline void __elv_rqhash_del(struct request *rq) |
273 | { | |
274 | hlist_del_init(&rq->hash); | |
275 | } | |
276 | ||
277 | static void elv_rqhash_del(request_queue_t *q, struct request *rq) | |
278 | { | |
279 | if (ELV_ON_HASH(rq)) | |
280 | __elv_rqhash_del(rq); | |
281 | } | |
282 | ||
283 | static void elv_rqhash_add(request_queue_t *q, struct request *rq) | |
284 | { | |
285 | elevator_t *e = q->elevator; | |
286 | ||
287 | BUG_ON(ELV_ON_HASH(rq)); | |
288 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
289 | } | |
290 | ||
291 | static void elv_rqhash_reposition(request_queue_t *q, struct request *rq) | |
292 | { | |
293 | __elv_rqhash_del(rq); | |
294 | elv_rqhash_add(q, rq); | |
295 | } | |
296 | ||
297 | static struct request *elv_rqhash_find(request_queue_t *q, sector_t offset) | |
298 | { | |
299 | elevator_t *e = q->elevator; | |
300 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
301 | struct hlist_node *entry, *next; | |
302 | struct request *rq; | |
303 | ||
304 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
305 | BUG_ON(!ELV_ON_HASH(rq)); | |
306 | ||
307 | if (unlikely(!rq_mergeable(rq))) { | |
308 | __elv_rqhash_del(rq); | |
309 | continue; | |
310 | } | |
311 | ||
312 | if (rq_hash_key(rq) == offset) | |
313 | return rq; | |
314 | } | |
315 | ||
316 | return NULL; | |
317 | } | |
318 | ||
2e662b65 JA |
319 | /* |
320 | * RB-tree support functions for inserting/lookup/removal of requests | |
321 | * in a sorted RB tree. | |
322 | */ | |
323 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
324 | { | |
325 | struct rb_node **p = &root->rb_node; | |
326 | struct rb_node *parent = NULL; | |
327 | struct request *__rq; | |
328 | ||
329 | while (*p) { | |
330 | parent = *p; | |
331 | __rq = rb_entry(parent, struct request, rb_node); | |
332 | ||
333 | if (rq->sector < __rq->sector) | |
334 | p = &(*p)->rb_left; | |
335 | else if (rq->sector > __rq->sector) | |
336 | p = &(*p)->rb_right; | |
337 | else | |
338 | return __rq; | |
339 | } | |
340 | ||
341 | rb_link_node(&rq->rb_node, parent, p); | |
342 | rb_insert_color(&rq->rb_node, root); | |
343 | return NULL; | |
344 | } | |
345 | ||
346 | EXPORT_SYMBOL(elv_rb_add); | |
347 | ||
348 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
349 | { | |
350 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
351 | rb_erase(&rq->rb_node, root); | |
352 | RB_CLEAR_NODE(&rq->rb_node); | |
353 | } | |
354 | ||
355 | EXPORT_SYMBOL(elv_rb_del); | |
356 | ||
357 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
358 | { | |
359 | struct rb_node *n = root->rb_node; | |
360 | struct request *rq; | |
361 | ||
362 | while (n) { | |
363 | rq = rb_entry(n, struct request, rb_node); | |
364 | ||
365 | if (sector < rq->sector) | |
366 | n = n->rb_left; | |
367 | else if (sector > rq->sector) | |
368 | n = n->rb_right; | |
369 | else | |
370 | return rq; | |
371 | } | |
372 | ||
373 | return NULL; | |
374 | } | |
375 | ||
376 | EXPORT_SYMBOL(elv_rb_find); | |
377 | ||
8922e16c TH |
378 | /* |
379 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
2e662b65 JA |
380 | * entry. rq is sort insted into the dispatch queue. To be used by |
381 | * specific elevators. | |
8922e16c | 382 | */ |
1b47f531 | 383 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
384 | { |
385 | sector_t boundary; | |
8922e16c TH |
386 | struct list_head *entry; |
387 | ||
06b86245 TH |
388 | if (q->last_merge == rq) |
389 | q->last_merge = NULL; | |
9817064b JA |
390 | |
391 | elv_rqhash_del(q, rq); | |
392 | ||
15853af9 | 393 | q->nr_sorted--; |
06b86245 | 394 | |
1b47f531 | 395 | boundary = q->end_sector; |
cb19833d | 396 | |
8922e16c TH |
397 | list_for_each_prev(entry, &q->queue_head) { |
398 | struct request *pos = list_entry_rq(entry); | |
399 | ||
4aff5e23 | 400 | if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) |
8922e16c TH |
401 | break; |
402 | if (rq->sector >= boundary) { | |
403 | if (pos->sector < boundary) | |
404 | continue; | |
405 | } else { | |
406 | if (pos->sector >= boundary) | |
407 | break; | |
408 | } | |
409 | if (rq->sector >= pos->sector) | |
410 | break; | |
411 | } | |
412 | ||
413 | list_add(&rq->queuelist, entry); | |
414 | } | |
415 | ||
2e662b65 JA |
416 | EXPORT_SYMBOL(elv_dispatch_sort); |
417 | ||
9817064b | 418 | /* |
2e662b65 JA |
419 | * Insert rq into dispatch queue of q. Queue lock must be held on |
420 | * entry. rq is added to the back of the dispatch queue. To be used by | |
421 | * specific elevators. | |
9817064b JA |
422 | */ |
423 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
424 | { | |
425 | if (q->last_merge == rq) | |
426 | q->last_merge = NULL; | |
427 | ||
428 | elv_rqhash_del(q, rq); | |
429 | ||
430 | q->nr_sorted--; | |
431 | ||
432 | q->end_sector = rq_end_sector(rq); | |
433 | q->boundary_rq = rq; | |
434 | list_add_tail(&rq->queuelist, &q->queue_head); | |
435 | } | |
436 | ||
2e662b65 JA |
437 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
438 | ||
1da177e4 LT |
439 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
440 | { | |
441 | elevator_t *e = q->elevator; | |
9817064b | 442 | struct request *__rq; |
06b86245 TH |
443 | int ret; |
444 | ||
9817064b JA |
445 | /* |
446 | * First try one-hit cache. | |
447 | */ | |
06b86245 TH |
448 | if (q->last_merge) { |
449 | ret = elv_try_merge(q->last_merge, bio); | |
450 | if (ret != ELEVATOR_NO_MERGE) { | |
451 | *req = q->last_merge; | |
452 | return ret; | |
453 | } | |
454 | } | |
1da177e4 | 455 | |
9817064b JA |
456 | /* |
457 | * See if our hash lookup can find a potential backmerge. | |
458 | */ | |
459 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
460 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
461 | *req = __rq; | |
462 | return ELEVATOR_BACK_MERGE; | |
463 | } | |
464 | ||
1da177e4 LT |
465 | if (e->ops->elevator_merge_fn) |
466 | return e->ops->elevator_merge_fn(q, req, bio); | |
467 | ||
468 | return ELEVATOR_NO_MERGE; | |
469 | } | |
470 | ||
2e662b65 | 471 | void elv_merged_request(request_queue_t *q, struct request *rq, int type) |
1da177e4 LT |
472 | { |
473 | elevator_t *e = q->elevator; | |
474 | ||
475 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 476 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 477 | |
2e662b65 JA |
478 | if (type == ELEVATOR_BACK_MERGE) |
479 | elv_rqhash_reposition(q, rq); | |
9817064b | 480 | |
06b86245 | 481 | q->last_merge = rq; |
1da177e4 LT |
482 | } |
483 | ||
484 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
485 | struct request *next) | |
486 | { | |
487 | elevator_t *e = q->elevator; | |
488 | ||
1da177e4 LT |
489 | if (e->ops->elevator_merge_req_fn) |
490 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 491 | |
9817064b JA |
492 | elv_rqhash_reposition(q, rq); |
493 | elv_rqhash_del(q, next); | |
494 | ||
495 | q->nr_sorted--; | |
06b86245 | 496 | q->last_merge = rq; |
1da177e4 LT |
497 | } |
498 | ||
8922e16c | 499 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 LT |
500 | { |
501 | elevator_t *e = q->elevator; | |
502 | ||
503 | /* | |
504 | * it already went through dequeue, we need to decrement the | |
505 | * in_flight count again | |
506 | */ | |
8922e16c | 507 | if (blk_account_rq(rq)) { |
1da177e4 | 508 | q->in_flight--; |
8922e16c TH |
509 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
510 | e->ops->elevator_deactivate_req_fn(q, rq); | |
511 | } | |
1da177e4 | 512 | |
4aff5e23 | 513 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 514 | |
30e9656c | 515 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
516 | } |
517 | ||
15853af9 TH |
518 | static void elv_drain_elevator(request_queue_t *q) |
519 | { | |
520 | static int printed; | |
521 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
522 | ; | |
523 | if (q->nr_sorted == 0) | |
524 | return; | |
525 | if (printed++ < 10) { | |
526 | printk(KERN_ERR "%s: forced dispatching is broken " | |
527 | "(nr_sorted=%u), please report this\n", | |
528 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
529 | } | |
530 | } | |
531 | ||
30e9656c | 532 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 533 | { |
797e7dbb TH |
534 | struct list_head *pos; |
535 | unsigned ordseq; | |
dac07ec1 | 536 | int unplug_it = 1; |
797e7dbb | 537 | |
2056a782 JA |
538 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
539 | ||
1da177e4 LT |
540 | rq->q = q; |
541 | ||
8922e16c TH |
542 | switch (where) { |
543 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 544 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
545 | |
546 | list_add(&rq->queuelist, &q->queue_head); | |
547 | break; | |
548 | ||
549 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 550 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 551 | elv_drain_elevator(q); |
8922e16c TH |
552 | list_add_tail(&rq->queuelist, &q->queue_head); |
553 | /* | |
554 | * We kick the queue here for the following reasons. | |
555 | * - The elevator might have returned NULL previously | |
556 | * to delay requests and returned them now. As the | |
557 | * queue wasn't empty before this request, ll_rw_blk | |
558 | * won't run the queue on return, resulting in hang. | |
559 | * - Usually, back inserted requests won't be merged | |
560 | * with anything. There's no point in delaying queue | |
561 | * processing. | |
562 | */ | |
563 | blk_remove_plug(q); | |
564 | q->request_fn(q); | |
565 | break; | |
566 | ||
567 | case ELEVATOR_INSERT_SORT: | |
568 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 569 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 570 | q->nr_sorted++; |
9817064b JA |
571 | if (rq_mergeable(rq)) { |
572 | elv_rqhash_add(q, rq); | |
573 | if (!q->last_merge) | |
574 | q->last_merge = rq; | |
575 | } | |
576 | ||
ca23509f TH |
577 | /* |
578 | * Some ioscheds (cfq) run q->request_fn directly, so | |
579 | * rq cannot be accessed after calling | |
580 | * elevator_add_req_fn. | |
581 | */ | |
582 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
583 | break; |
584 | ||
797e7dbb TH |
585 | case ELEVATOR_INSERT_REQUEUE: |
586 | /* | |
587 | * If ordered flush isn't in progress, we do front | |
588 | * insertion; otherwise, requests should be requeued | |
589 | * in ordseq order. | |
590 | */ | |
4aff5e23 | 591 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb TH |
592 | |
593 | if (q->ordseq == 0) { | |
594 | list_add(&rq->queuelist, &q->queue_head); | |
595 | break; | |
596 | } | |
597 | ||
598 | ordseq = blk_ordered_req_seq(rq); | |
599 | ||
600 | list_for_each(pos, &q->queue_head) { | |
601 | struct request *pos_rq = list_entry_rq(pos); | |
602 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
603 | break; | |
604 | } | |
605 | ||
606 | list_add_tail(&rq->queuelist, pos); | |
dac07ec1 JA |
607 | /* |
608 | * most requeues happen because of a busy condition, don't | |
609 | * force unplug of the queue for that case. | |
610 | */ | |
611 | unplug_it = 0; | |
797e7dbb TH |
612 | break; |
613 | ||
8922e16c TH |
614 | default: |
615 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
616 | __FUNCTION__, where); | |
617 | BUG(); | |
618 | } | |
619 | ||
dac07ec1 | 620 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
621 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
622 | - q->in_flight; | |
623 | ||
624 | if (nrq >= q->unplug_thresh) | |
625 | __generic_unplug_device(q); | |
626 | } | |
1da177e4 LT |
627 | } |
628 | ||
30e9656c TH |
629 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
630 | int plug) | |
631 | { | |
632 | if (q->ordcolor) | |
4aff5e23 | 633 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 634 | |
4aff5e23 | 635 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
636 | /* |
637 | * toggle ordered color | |
638 | */ | |
639 | if (blk_barrier_rq(rq)) | |
640 | q->ordcolor ^= 1; | |
641 | ||
642 | /* | |
643 | * barriers implicitly indicate back insertion | |
644 | */ | |
645 | if (where == ELEVATOR_INSERT_SORT) | |
646 | where = ELEVATOR_INSERT_BACK; | |
647 | ||
648 | /* | |
649 | * this request is scheduling boundary, update | |
650 | * end_sector | |
651 | */ | |
652 | if (blk_fs_request(rq)) { | |
653 | q->end_sector = rq_end_sector(rq); | |
654 | q->boundary_rq = rq; | |
655 | } | |
4aff5e23 | 656 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) |
30e9656c TH |
657 | where = ELEVATOR_INSERT_BACK; |
658 | ||
659 | if (plug) | |
660 | blk_plug_device(q); | |
661 | ||
662 | elv_insert(q, rq, where); | |
663 | } | |
664 | ||
2e662b65 JA |
665 | EXPORT_SYMBOL(__elv_add_request); |
666 | ||
1da177e4 LT |
667 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
668 | int plug) | |
669 | { | |
670 | unsigned long flags; | |
671 | ||
672 | spin_lock_irqsave(q->queue_lock, flags); | |
673 | __elv_add_request(q, rq, where, plug); | |
674 | spin_unlock_irqrestore(q->queue_lock, flags); | |
675 | } | |
676 | ||
2e662b65 JA |
677 | EXPORT_SYMBOL(elv_add_request); |
678 | ||
1da177e4 LT |
679 | static inline struct request *__elv_next_request(request_queue_t *q) |
680 | { | |
8922e16c TH |
681 | struct request *rq; |
682 | ||
797e7dbb TH |
683 | while (1) { |
684 | while (!list_empty(&q->queue_head)) { | |
685 | rq = list_entry_rq(q->queue_head.next); | |
686 | if (blk_do_ordered(q, &rq)) | |
687 | return rq; | |
688 | } | |
1da177e4 | 689 | |
797e7dbb TH |
690 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
691 | return NULL; | |
1da177e4 | 692 | } |
1da177e4 LT |
693 | } |
694 | ||
695 | struct request *elv_next_request(request_queue_t *q) | |
696 | { | |
697 | struct request *rq; | |
698 | int ret; | |
699 | ||
700 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 701 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
702 | elevator_t *e = q->elevator; |
703 | ||
704 | /* | |
705 | * This is the first time the device driver | |
706 | * sees this request (possibly after | |
707 | * requeueing). Notify IO scheduler. | |
708 | */ | |
709 | if (blk_sorted_rq(rq) && | |
710 | e->ops->elevator_activate_req_fn) | |
711 | e->ops->elevator_activate_req_fn(q, rq); | |
1da177e4 | 712 | |
8922e16c TH |
713 | /* |
714 | * just mark as started even if we don't start | |
715 | * it, a request that has been delayed should | |
716 | * not be passed by new incoming requests | |
717 | */ | |
4aff5e23 | 718 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 719 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 720 | } |
1da177e4 | 721 | |
8922e16c | 722 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 723 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
724 | q->boundary_rq = NULL; |
725 | } | |
1da177e4 | 726 | |
4aff5e23 | 727 | if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn) |
1da177e4 LT |
728 | break; |
729 | ||
730 | ret = q->prep_rq_fn(q, rq); | |
731 | if (ret == BLKPREP_OK) { | |
732 | break; | |
733 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
734 | /* |
735 | * the request may have been (partially) prepped. | |
736 | * we need to keep this request in the front to | |
8922e16c TH |
737 | * avoid resource deadlock. REQ_STARTED will |
738 | * prevent other fs requests from passing this one. | |
2e759cd4 | 739 | */ |
1da177e4 LT |
740 | rq = NULL; |
741 | break; | |
742 | } else if (ret == BLKPREP_KILL) { | |
743 | int nr_bytes = rq->hard_nr_sectors << 9; | |
744 | ||
745 | if (!nr_bytes) | |
746 | nr_bytes = rq->data_len; | |
747 | ||
748 | blkdev_dequeue_request(rq); | |
4aff5e23 | 749 | rq->cmd_flags |= REQ_QUIET; |
1da177e4 | 750 | end_that_request_chunk(rq, 0, nr_bytes); |
8ffdc655 | 751 | end_that_request_last(rq, 0); |
1da177e4 LT |
752 | } else { |
753 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
754 | ret); | |
755 | break; | |
756 | } | |
757 | } | |
758 | ||
759 | return rq; | |
760 | } | |
761 | ||
2e662b65 JA |
762 | EXPORT_SYMBOL(elv_next_request); |
763 | ||
8922e16c | 764 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 765 | { |
8922e16c | 766 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 767 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
768 | |
769 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
770 | |
771 | /* | |
772 | * the time frame between a request being removed from the lists | |
773 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 774 | * the driver side. |
1da177e4 LT |
775 | */ |
776 | if (blk_account_rq(rq)) | |
777 | q->in_flight++; | |
1da177e4 LT |
778 | } |
779 | ||
2e662b65 JA |
780 | EXPORT_SYMBOL(elv_dequeue_request); |
781 | ||
1da177e4 LT |
782 | int elv_queue_empty(request_queue_t *q) |
783 | { | |
784 | elevator_t *e = q->elevator; | |
785 | ||
8922e16c TH |
786 | if (!list_empty(&q->queue_head)) |
787 | return 0; | |
788 | ||
1da177e4 LT |
789 | if (e->ops->elevator_queue_empty_fn) |
790 | return e->ops->elevator_queue_empty_fn(q); | |
791 | ||
8922e16c | 792 | return 1; |
1da177e4 LT |
793 | } |
794 | ||
2e662b65 JA |
795 | EXPORT_SYMBOL(elv_queue_empty); |
796 | ||
1da177e4 LT |
797 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) |
798 | { | |
1da177e4 LT |
799 | elevator_t *e = q->elevator; |
800 | ||
801 | if (e->ops->elevator_latter_req_fn) | |
802 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
803 | return NULL; |
804 | } | |
805 | ||
806 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
807 | { | |
1da177e4 LT |
808 | elevator_t *e = q->elevator; |
809 | ||
810 | if (e->ops->elevator_former_req_fn) | |
811 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
812 | return NULL; |
813 | } | |
814 | ||
cb78b285 | 815 | int elv_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
816 | { |
817 | elevator_t *e = q->elevator; | |
818 | ||
819 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 820 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
821 | |
822 | rq->elevator_private = NULL; | |
823 | return 0; | |
824 | } | |
825 | ||
826 | void elv_put_request(request_queue_t *q, struct request *rq) | |
827 | { | |
828 | elevator_t *e = q->elevator; | |
829 | ||
830 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 831 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
832 | } |
833 | ||
cb78b285 | 834 | int elv_may_queue(request_queue_t *q, int rw) |
1da177e4 LT |
835 | { |
836 | elevator_t *e = q->elevator; | |
837 | ||
838 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 839 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
840 | |
841 | return ELV_MQUEUE_MAY; | |
842 | } | |
843 | ||
844 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
845 | { | |
846 | elevator_t *e = q->elevator; | |
847 | ||
848 | /* | |
849 | * request is released from the driver, io must be done | |
850 | */ | |
8922e16c | 851 | if (blk_account_rq(rq)) { |
1da177e4 | 852 | q->in_flight--; |
1bc691d3 TH |
853 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
854 | e->ops->elevator_completed_req_fn(q, rq); | |
855 | } | |
797e7dbb | 856 | |
1bc691d3 TH |
857 | /* |
858 | * Check if the queue is waiting for fs requests to be | |
859 | * drained for flush sequence. | |
860 | */ | |
861 | if (unlikely(q->ordseq)) { | |
862 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
863 | if (q->in_flight == 0 && | |
797e7dbb TH |
864 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
865 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
866 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
867 | q->request_fn(q); | |
868 | } | |
8922e16c | 869 | } |
1da177e4 LT |
870 | } |
871 | ||
3d1ab40f AV |
872 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
873 | ||
874 | static ssize_t | |
875 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 876 | { |
3d1ab40f AV |
877 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
878 | struct elv_fs_entry *entry = to_elv(attr); | |
879 | ssize_t error; | |
880 | ||
881 | if (!entry->show) | |
882 | return -EIO; | |
883 | ||
884 | mutex_lock(&e->sysfs_lock); | |
885 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
886 | mutex_unlock(&e->sysfs_lock); | |
887 | return error; | |
888 | } | |
1da177e4 | 889 | |
3d1ab40f AV |
890 | static ssize_t |
891 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
892 | const char *page, size_t length) | |
893 | { | |
894 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
895 | struct elv_fs_entry *entry = to_elv(attr); | |
896 | ssize_t error; | |
1da177e4 | 897 | |
3d1ab40f AV |
898 | if (!entry->store) |
899 | return -EIO; | |
1da177e4 | 900 | |
3d1ab40f AV |
901 | mutex_lock(&e->sysfs_lock); |
902 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
903 | mutex_unlock(&e->sysfs_lock); | |
904 | return error; | |
905 | } | |
906 | ||
907 | static struct sysfs_ops elv_sysfs_ops = { | |
908 | .show = elv_attr_show, | |
909 | .store = elv_attr_store, | |
910 | }; | |
911 | ||
912 | static struct kobj_type elv_ktype = { | |
913 | .sysfs_ops = &elv_sysfs_ops, | |
914 | .release = elevator_release, | |
915 | }; | |
916 | ||
917 | int elv_register_queue(struct request_queue *q) | |
918 | { | |
919 | elevator_t *e = q->elevator; | |
920 | int error; | |
921 | ||
922 | e->kobj.parent = &q->kobj; | |
923 | ||
924 | error = kobject_add(&e->kobj); | |
925 | if (!error) { | |
e572ec7e | 926 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 927 | if (attr) { |
e572ec7e AV |
928 | while (attr->attr.name) { |
929 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 930 | break; |
e572ec7e | 931 | attr++; |
3d1ab40f AV |
932 | } |
933 | } | |
934 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
935 | } | |
936 | return error; | |
1da177e4 LT |
937 | } |
938 | ||
bc1c1169 JA |
939 | static void __elv_unregister_queue(elevator_t *e) |
940 | { | |
941 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
942 | kobject_del(&e->kobj); | |
943 | } | |
944 | ||
1da177e4 LT |
945 | void elv_unregister_queue(struct request_queue *q) |
946 | { | |
bc1c1169 JA |
947 | if (q) |
948 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
949 | } |
950 | ||
951 | int elv_register(struct elevator_type *e) | |
952 | { | |
2824bc93 | 953 | spin_lock_irq(&elv_list_lock); |
ce524497 | 954 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 LT |
955 | list_add_tail(&e->list, &elv_list); |
956 | spin_unlock_irq(&elv_list_lock); | |
957 | ||
958 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
959 | if (!strcmp(e->elevator_name, chosen_elevator) || |
960 | (!*chosen_elevator && | |
961 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
962 | printk(" (default)"); | |
1da177e4 LT |
963 | printk("\n"); |
964 | return 0; | |
965 | } | |
966 | EXPORT_SYMBOL_GPL(elv_register); | |
967 | ||
968 | void elv_unregister(struct elevator_type *e) | |
969 | { | |
83521d3e CH |
970 | struct task_struct *g, *p; |
971 | ||
972 | /* | |
973 | * Iterate every thread in the process to remove the io contexts. | |
974 | */ | |
e17a9489 AV |
975 | if (e->ops.trim) { |
976 | read_lock(&tasklist_lock); | |
977 | do_each_thread(g, p) { | |
978 | task_lock(p); | |
2d8f6131 ON |
979 | if (p->io_context) |
980 | e->ops.trim(p->io_context); | |
e17a9489 AV |
981 | task_unlock(p); |
982 | } while_each_thread(g, p); | |
983 | read_unlock(&tasklist_lock); | |
984 | } | |
83521d3e | 985 | |
1da177e4 LT |
986 | spin_lock_irq(&elv_list_lock); |
987 | list_del_init(&e->list); | |
988 | spin_unlock_irq(&elv_list_lock); | |
989 | } | |
990 | EXPORT_SYMBOL_GPL(elv_unregister); | |
991 | ||
992 | /* | |
993 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
994 | * we don't free the old io scheduler, before we have allocated what we | |
995 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 996 | * one, if the new one fails init for some reason. |
1da177e4 | 997 | */ |
3d1ab40f | 998 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
1da177e4 | 999 | { |
cb98fc8b | 1000 | elevator_t *old_elevator, *e; |
bc1c1169 | 1001 | void *data; |
1da177e4 | 1002 | |
cb98fc8b TH |
1003 | /* |
1004 | * Allocate new elevator | |
1005 | */ | |
b5deef90 | 1006 | e = elevator_alloc(q, new_e); |
1da177e4 | 1007 | if (!e) |
3d1ab40f | 1008 | return 0; |
1da177e4 | 1009 | |
bc1c1169 JA |
1010 | data = elevator_init_queue(q, e); |
1011 | if (!data) { | |
1012 | kobject_put(&e->kobj); | |
1013 | return 0; | |
1014 | } | |
1015 | ||
1da177e4 | 1016 | /* |
cb98fc8b | 1017 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1018 | */ |
cb98fc8b TH |
1019 | spin_lock_irq(q->queue_lock); |
1020 | ||
64521d1a | 1021 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 1022 | |
15853af9 | 1023 | elv_drain_elevator(q); |
cb98fc8b TH |
1024 | |
1025 | while (q->rq.elvpriv) { | |
407df2aa TH |
1026 | blk_remove_plug(q); |
1027 | q->request_fn(q); | |
cb98fc8b | 1028 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1029 | msleep(10); |
cb98fc8b | 1030 | spin_lock_irq(q->queue_lock); |
15853af9 | 1031 | elv_drain_elevator(q); |
cb98fc8b TH |
1032 | } |
1033 | ||
1da177e4 | 1034 | /* |
bc1c1169 | 1035 | * Remember old elevator. |
1da177e4 | 1036 | */ |
1da177e4 LT |
1037 | old_elevator = q->elevator; |
1038 | ||
1da177e4 LT |
1039 | /* |
1040 | * attach and start new elevator | |
1041 | */ | |
bc1c1169 JA |
1042 | elevator_attach(q, e, data); |
1043 | ||
1044 | spin_unlock_irq(q->queue_lock); | |
1045 | ||
1046 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1047 | |
1048 | if (elv_register_queue(q)) | |
1049 | goto fail_register; | |
1050 | ||
1051 | /* | |
cb98fc8b | 1052 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1053 | */ |
1054 | elevator_exit(old_elevator); | |
64521d1a | 1055 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1056 | return 1; |
1da177e4 LT |
1057 | |
1058 | fail_register: | |
1059 | /* | |
1060 | * switch failed, exit the new io scheduler and reattach the old | |
1061 | * one again (along with re-adding the sysfs dir) | |
1062 | */ | |
1063 | elevator_exit(e); | |
1da177e4 LT |
1064 | q->elevator = old_elevator; |
1065 | elv_register_queue(q); | |
64521d1a | 1066 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1067 | return 0; |
1da177e4 LT |
1068 | } |
1069 | ||
1070 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
1071 | { | |
1072 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1073 | size_t len; |
1da177e4 LT |
1074 | struct elevator_type *e; |
1075 | ||
be561235 TH |
1076 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1077 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1078 | len = strlen(elevator_name); | |
1da177e4 | 1079 | |
be561235 TH |
1080 | if (len && elevator_name[len - 1] == '\n') |
1081 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1082 | |
1083 | e = elevator_get(elevator_name); | |
1084 | if (!e) { | |
1085 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1086 | return -EINVAL; | |
1087 | } | |
1088 | ||
2ca7d93b ND |
1089 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1090 | elevator_put(e); | |
1da177e4 | 1091 | return count; |
2ca7d93b | 1092 | } |
1da177e4 | 1093 | |
3d1ab40f AV |
1094 | if (!elevator_switch(q, e)) |
1095 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
1096 | return count; |
1097 | } | |
1098 | ||
1099 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
1100 | { | |
1101 | elevator_t *e = q->elevator; | |
1102 | struct elevator_type *elv = e->elevator_type; | |
1103 | struct list_head *entry; | |
1104 | int len = 0; | |
1105 | ||
c5841642 | 1106 | spin_lock_irq(&elv_list_lock); |
1da177e4 LT |
1107 | list_for_each(entry, &elv_list) { |
1108 | struct elevator_type *__e; | |
1109 | ||
1110 | __e = list_entry(entry, struct elevator_type, list); | |
1111 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
1112 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1113 | else | |
1114 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1115 | } | |
c5841642 | 1116 | spin_unlock_irq(&elv_list_lock); |
1da177e4 LT |
1117 | |
1118 | len += sprintf(len+name, "\n"); | |
1119 | return len; | |
1120 | } | |
1121 | ||
2e662b65 JA |
1122 | struct request *elv_rb_former_request(request_queue_t *q, struct request *rq) |
1123 | { | |
1124 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1125 | ||
1126 | if (rbprev) | |
1127 | return rb_entry_rq(rbprev); | |
1128 | ||
1129 | return NULL; | |
1130 | } | |
1131 | ||
1132 | EXPORT_SYMBOL(elv_rb_former_request); | |
1133 | ||
1134 | struct request *elv_rb_latter_request(request_queue_t *q, struct request *rq) | |
1135 | { | |
1136 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1137 | ||
1138 | if (rbnext) | |
1139 | return rb_entry_rq(rbnext); | |
1140 | ||
1141 | return NULL; | |
1142 | } | |
1143 | ||
1144 | EXPORT_SYMBOL(elv_rb_latter_request); |