Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
6 | * 30042000 Jens Axboe <axboe@suse.de> : | |
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 | ||
1da177e4 LT |
53 | /* |
54 | * can we safely merge with this request? | |
55 | */ | |
56 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) | |
57 | { | |
58 | if (!rq_mergeable(rq)) | |
59 | return 0; | |
60 | ||
61 | /* | |
62 | * different data direction or already started, don't merge | |
63 | */ | |
64 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
65 | return 0; | |
66 | ||
67 | /* | |
68 | * same device and no special stuff set, merge is ok | |
69 | */ | |
c00895ab | 70 | if (rq->rq_disk == bio->bi_bdev->bd_disk && !rq->special) |
1da177e4 LT |
71 | return 1; |
72 | ||
73 | return 0; | |
74 | } | |
75 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
76 | ||
769db45b | 77 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
78 | { |
79 | int ret = ELEVATOR_NO_MERGE; | |
80 | ||
81 | /* | |
82 | * we can merge and sequence is ok, check if it's possible | |
83 | */ | |
84 | if (elv_rq_merge_ok(__rq, bio)) { | |
85 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
86 | ret = ELEVATOR_BACK_MERGE; | |
87 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
88 | ret = ELEVATOR_FRONT_MERGE; | |
89 | } | |
90 | ||
91 | return ret; | |
92 | } | |
1da177e4 | 93 | |
1da177e4 LT |
94 | static struct elevator_type *elevator_find(const char *name) |
95 | { | |
96 | struct elevator_type *e = NULL; | |
97 | struct list_head *entry; | |
98 | ||
1da177e4 LT |
99 | list_for_each(entry, &elv_list) { |
100 | struct elevator_type *__e; | |
101 | ||
102 | __e = list_entry(entry, struct elevator_type, list); | |
103 | ||
104 | if (!strcmp(__e->elevator_name, name)) { | |
105 | e = __e; | |
106 | break; | |
107 | } | |
108 | } | |
1da177e4 LT |
109 | |
110 | return e; | |
111 | } | |
112 | ||
113 | static void elevator_put(struct elevator_type *e) | |
114 | { | |
115 | module_put(e->elevator_owner); | |
116 | } | |
117 | ||
118 | static struct elevator_type *elevator_get(const char *name) | |
119 | { | |
2824bc93 | 120 | struct elevator_type *e; |
1da177e4 | 121 | |
2824bc93 TH |
122 | spin_lock_irq(&elv_list_lock); |
123 | ||
124 | e = elevator_find(name); | |
125 | if (e && !try_module_get(e->elevator_owner)) | |
126 | e = NULL; | |
127 | ||
128 | spin_unlock_irq(&elv_list_lock); | |
1da177e4 LT |
129 | |
130 | return e; | |
131 | } | |
132 | ||
bc1c1169 | 133 | static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 | 134 | { |
bc1c1169 JA |
135 | return eq->ops->elevator_init_fn(q, eq); |
136 | } | |
1da177e4 | 137 | |
bc1c1169 JA |
138 | static void elevator_attach(request_queue_t *q, struct elevator_queue *eq, |
139 | void *data) | |
140 | { | |
1da177e4 | 141 | q->elevator = eq; |
bc1c1169 | 142 | eq->elevator_data = data; |
1da177e4 LT |
143 | } |
144 | ||
145 | static char chosen_elevator[16]; | |
146 | ||
5f003976 | 147 | static int __init elevator_setup(char *str) |
1da177e4 | 148 | { |
752a3b79 CE |
149 | /* |
150 | * Be backwards-compatible with previous kernels, so users | |
151 | * won't get the wrong elevator. | |
152 | */ | |
5f003976 | 153 | if (!strcmp(str, "as")) |
752a3b79 | 154 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 155 | else |
5f003976 | 156 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 157 | return 1; |
1da177e4 LT |
158 | } |
159 | ||
160 | __setup("elevator=", elevator_setup); | |
161 | ||
3d1ab40f AV |
162 | static struct kobj_type elv_ktype; |
163 | ||
b5deef90 | 164 | static elevator_t *elevator_alloc(request_queue_t *q, struct elevator_type *e) |
3d1ab40f | 165 | { |
9817064b JA |
166 | elevator_t *eq; |
167 | int i; | |
168 | ||
b5deef90 | 169 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL, q->node); |
9817064b JA |
170 | if (unlikely(!eq)) |
171 | goto err; | |
172 | ||
173 | memset(eq, 0, sizeof(*eq)); | |
174 | eq->ops = &e->ops; | |
175 | eq->elevator_type = e; | |
176 | kobject_init(&eq->kobj); | |
177 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
178 | eq->kobj.ktype = &elv_ktype; | |
179 | mutex_init(&eq->sysfs_lock); | |
180 | ||
b5deef90 JA |
181 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
182 | GFP_KERNEL, q->node); | |
9817064b JA |
183 | if (!eq->hash) |
184 | goto err; | |
185 | ||
186 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
187 | INIT_HLIST_HEAD(&eq->hash[i]); | |
188 | ||
3d1ab40f | 189 | return eq; |
9817064b JA |
190 | err: |
191 | kfree(eq); | |
192 | elevator_put(e); | |
193 | return NULL; | |
3d1ab40f AV |
194 | } |
195 | ||
196 | static void elevator_release(struct kobject *kobj) | |
197 | { | |
198 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 199 | |
3d1ab40f | 200 | elevator_put(e->elevator_type); |
9817064b | 201 | kfree(e->hash); |
3d1ab40f AV |
202 | kfree(e); |
203 | } | |
204 | ||
1da177e4 LT |
205 | int elevator_init(request_queue_t *q, char *name) |
206 | { | |
207 | struct elevator_type *e = NULL; | |
208 | struct elevator_queue *eq; | |
209 | int ret = 0; | |
bc1c1169 | 210 | void *data; |
1da177e4 | 211 | |
cb98fc8b TH |
212 | INIT_LIST_HEAD(&q->queue_head); |
213 | q->last_merge = NULL; | |
214 | q->end_sector = 0; | |
215 | q->boundary_rq = NULL; | |
cb98fc8b | 216 | |
5f003976 | 217 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
218 | return -EINVAL; |
219 | ||
248d5ca5 ND |
220 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
221 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
222 | ||
223 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
224 | printk("Default I/O scheduler not found, using no-op\n"); | |
225 | e = elevator_get("noop"); | |
5f003976 ND |
226 | } |
227 | ||
b5deef90 | 228 | eq = elevator_alloc(q, e); |
3d1ab40f | 229 | if (!eq) |
1da177e4 | 230 | return -ENOMEM; |
1da177e4 | 231 | |
bc1c1169 JA |
232 | data = elevator_init_queue(q, eq); |
233 | if (!data) { | |
3d1ab40f | 234 | kobject_put(&eq->kobj); |
bc1c1169 JA |
235 | return -ENOMEM; |
236 | } | |
1da177e4 | 237 | |
bc1c1169 | 238 | elevator_attach(q, eq, data); |
1da177e4 LT |
239 | return ret; |
240 | } | |
241 | ||
2e662b65 JA |
242 | EXPORT_SYMBOL(elevator_init); |
243 | ||
1da177e4 LT |
244 | void elevator_exit(elevator_t *e) |
245 | { | |
3d1ab40f | 246 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
247 | if (e->ops->elevator_exit_fn) |
248 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
249 | e->ops = NULL; |
250 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 251 | |
3d1ab40f | 252 | kobject_put(&e->kobj); |
1da177e4 LT |
253 | } |
254 | ||
2e662b65 JA |
255 | EXPORT_SYMBOL(elevator_exit); |
256 | ||
9817064b JA |
257 | static inline void __elv_rqhash_del(struct request *rq) |
258 | { | |
259 | hlist_del_init(&rq->hash); | |
260 | } | |
261 | ||
262 | static void elv_rqhash_del(request_queue_t *q, struct request *rq) | |
263 | { | |
264 | if (ELV_ON_HASH(rq)) | |
265 | __elv_rqhash_del(rq); | |
266 | } | |
267 | ||
268 | static void elv_rqhash_add(request_queue_t *q, struct request *rq) | |
269 | { | |
270 | elevator_t *e = q->elevator; | |
271 | ||
272 | BUG_ON(ELV_ON_HASH(rq)); | |
273 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
274 | } | |
275 | ||
276 | static void elv_rqhash_reposition(request_queue_t *q, struct request *rq) | |
277 | { | |
278 | __elv_rqhash_del(rq); | |
279 | elv_rqhash_add(q, rq); | |
280 | } | |
281 | ||
282 | static struct request *elv_rqhash_find(request_queue_t *q, sector_t offset) | |
283 | { | |
284 | elevator_t *e = q->elevator; | |
285 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
286 | struct hlist_node *entry, *next; | |
287 | struct request *rq; | |
288 | ||
289 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
290 | BUG_ON(!ELV_ON_HASH(rq)); | |
291 | ||
292 | if (unlikely(!rq_mergeable(rq))) { | |
293 | __elv_rqhash_del(rq); | |
294 | continue; | |
295 | } | |
296 | ||
297 | if (rq_hash_key(rq) == offset) | |
298 | return rq; | |
299 | } | |
300 | ||
301 | return NULL; | |
302 | } | |
303 | ||
2e662b65 JA |
304 | /* |
305 | * RB-tree support functions for inserting/lookup/removal of requests | |
306 | * in a sorted RB tree. | |
307 | */ | |
308 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
309 | { | |
310 | struct rb_node **p = &root->rb_node; | |
311 | struct rb_node *parent = NULL; | |
312 | struct request *__rq; | |
313 | ||
314 | while (*p) { | |
315 | parent = *p; | |
316 | __rq = rb_entry(parent, struct request, rb_node); | |
317 | ||
318 | if (rq->sector < __rq->sector) | |
319 | p = &(*p)->rb_left; | |
320 | else if (rq->sector > __rq->sector) | |
321 | p = &(*p)->rb_right; | |
322 | else | |
323 | return __rq; | |
324 | } | |
325 | ||
326 | rb_link_node(&rq->rb_node, parent, p); | |
327 | rb_insert_color(&rq->rb_node, root); | |
328 | return NULL; | |
329 | } | |
330 | ||
331 | EXPORT_SYMBOL(elv_rb_add); | |
332 | ||
333 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
334 | { | |
335 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
336 | rb_erase(&rq->rb_node, root); | |
337 | RB_CLEAR_NODE(&rq->rb_node); | |
338 | } | |
339 | ||
340 | EXPORT_SYMBOL(elv_rb_del); | |
341 | ||
342 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
343 | { | |
344 | struct rb_node *n = root->rb_node; | |
345 | struct request *rq; | |
346 | ||
347 | while (n) { | |
348 | rq = rb_entry(n, struct request, rb_node); | |
349 | ||
350 | if (sector < rq->sector) | |
351 | n = n->rb_left; | |
352 | else if (sector > rq->sector) | |
353 | n = n->rb_right; | |
354 | else | |
355 | return rq; | |
356 | } | |
357 | ||
358 | return NULL; | |
359 | } | |
360 | ||
361 | EXPORT_SYMBOL(elv_rb_find); | |
362 | ||
8922e16c TH |
363 | /* |
364 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
2e662b65 JA |
365 | * entry. rq is sort insted into the dispatch queue. To be used by |
366 | * specific elevators. | |
8922e16c | 367 | */ |
1b47f531 | 368 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
369 | { |
370 | sector_t boundary; | |
8922e16c TH |
371 | struct list_head *entry; |
372 | ||
06b86245 TH |
373 | if (q->last_merge == rq) |
374 | q->last_merge = NULL; | |
9817064b JA |
375 | |
376 | elv_rqhash_del(q, rq); | |
377 | ||
15853af9 | 378 | q->nr_sorted--; |
06b86245 | 379 | |
1b47f531 | 380 | boundary = q->end_sector; |
cb19833d | 381 | |
8922e16c TH |
382 | list_for_each_prev(entry, &q->queue_head) { |
383 | struct request *pos = list_entry_rq(entry); | |
384 | ||
4aff5e23 | 385 | if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) |
8922e16c TH |
386 | break; |
387 | if (rq->sector >= boundary) { | |
388 | if (pos->sector < boundary) | |
389 | continue; | |
390 | } else { | |
391 | if (pos->sector >= boundary) | |
392 | break; | |
393 | } | |
394 | if (rq->sector >= pos->sector) | |
395 | break; | |
396 | } | |
397 | ||
398 | list_add(&rq->queuelist, entry); | |
399 | } | |
400 | ||
2e662b65 JA |
401 | EXPORT_SYMBOL(elv_dispatch_sort); |
402 | ||
9817064b | 403 | /* |
2e662b65 JA |
404 | * Insert rq into dispatch queue of q. Queue lock must be held on |
405 | * entry. rq is added to the back of the dispatch queue. To be used by | |
406 | * specific elevators. | |
9817064b JA |
407 | */ |
408 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
409 | { | |
410 | if (q->last_merge == rq) | |
411 | q->last_merge = NULL; | |
412 | ||
413 | elv_rqhash_del(q, rq); | |
414 | ||
415 | q->nr_sorted--; | |
416 | ||
417 | q->end_sector = rq_end_sector(rq); | |
418 | q->boundary_rq = rq; | |
419 | list_add_tail(&rq->queuelist, &q->queue_head); | |
420 | } | |
421 | ||
2e662b65 JA |
422 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
423 | ||
1da177e4 LT |
424 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
425 | { | |
426 | elevator_t *e = q->elevator; | |
9817064b | 427 | struct request *__rq; |
06b86245 TH |
428 | int ret; |
429 | ||
9817064b JA |
430 | /* |
431 | * First try one-hit cache. | |
432 | */ | |
06b86245 TH |
433 | if (q->last_merge) { |
434 | ret = elv_try_merge(q->last_merge, bio); | |
435 | if (ret != ELEVATOR_NO_MERGE) { | |
436 | *req = q->last_merge; | |
437 | return ret; | |
438 | } | |
439 | } | |
1da177e4 | 440 | |
9817064b JA |
441 | /* |
442 | * See if our hash lookup can find a potential backmerge. | |
443 | */ | |
444 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
445 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
446 | *req = __rq; | |
447 | return ELEVATOR_BACK_MERGE; | |
448 | } | |
449 | ||
1da177e4 LT |
450 | if (e->ops->elevator_merge_fn) |
451 | return e->ops->elevator_merge_fn(q, req, bio); | |
452 | ||
453 | return ELEVATOR_NO_MERGE; | |
454 | } | |
455 | ||
2e662b65 | 456 | void elv_merged_request(request_queue_t *q, struct request *rq, int type) |
1da177e4 LT |
457 | { |
458 | elevator_t *e = q->elevator; | |
459 | ||
460 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 461 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 462 | |
2e662b65 JA |
463 | if (type == ELEVATOR_BACK_MERGE) |
464 | elv_rqhash_reposition(q, rq); | |
9817064b | 465 | |
06b86245 | 466 | q->last_merge = rq; |
1da177e4 LT |
467 | } |
468 | ||
469 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
470 | struct request *next) | |
471 | { | |
472 | elevator_t *e = q->elevator; | |
473 | ||
1da177e4 LT |
474 | if (e->ops->elevator_merge_req_fn) |
475 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 476 | |
9817064b JA |
477 | elv_rqhash_reposition(q, rq); |
478 | elv_rqhash_del(q, next); | |
479 | ||
480 | q->nr_sorted--; | |
06b86245 | 481 | q->last_merge = rq; |
1da177e4 LT |
482 | } |
483 | ||
8922e16c | 484 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 LT |
485 | { |
486 | elevator_t *e = q->elevator; | |
487 | ||
488 | /* | |
489 | * it already went through dequeue, we need to decrement the | |
490 | * in_flight count again | |
491 | */ | |
8922e16c | 492 | if (blk_account_rq(rq)) { |
1da177e4 | 493 | q->in_flight--; |
8922e16c TH |
494 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
495 | e->ops->elevator_deactivate_req_fn(q, rq); | |
496 | } | |
1da177e4 | 497 | |
4aff5e23 | 498 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 499 | |
30e9656c | 500 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
501 | } |
502 | ||
15853af9 TH |
503 | static void elv_drain_elevator(request_queue_t *q) |
504 | { | |
505 | static int printed; | |
506 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
507 | ; | |
508 | if (q->nr_sorted == 0) | |
509 | return; | |
510 | if (printed++ < 10) { | |
511 | printk(KERN_ERR "%s: forced dispatching is broken " | |
512 | "(nr_sorted=%u), please report this\n", | |
513 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
514 | } | |
515 | } | |
516 | ||
30e9656c | 517 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 518 | { |
797e7dbb TH |
519 | struct list_head *pos; |
520 | unsigned ordseq; | |
dac07ec1 | 521 | int unplug_it = 1; |
797e7dbb | 522 | |
2056a782 JA |
523 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
524 | ||
1da177e4 LT |
525 | rq->q = q; |
526 | ||
8922e16c TH |
527 | switch (where) { |
528 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 529 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
530 | |
531 | list_add(&rq->queuelist, &q->queue_head); | |
532 | break; | |
533 | ||
534 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 535 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 536 | elv_drain_elevator(q); |
8922e16c TH |
537 | list_add_tail(&rq->queuelist, &q->queue_head); |
538 | /* | |
539 | * We kick the queue here for the following reasons. | |
540 | * - The elevator might have returned NULL previously | |
541 | * to delay requests and returned them now. As the | |
542 | * queue wasn't empty before this request, ll_rw_blk | |
543 | * won't run the queue on return, resulting in hang. | |
544 | * - Usually, back inserted requests won't be merged | |
545 | * with anything. There's no point in delaying queue | |
546 | * processing. | |
547 | */ | |
548 | blk_remove_plug(q); | |
549 | q->request_fn(q); | |
550 | break; | |
551 | ||
552 | case ELEVATOR_INSERT_SORT: | |
553 | BUG_ON(!blk_fs_request(rq)); | |
4aff5e23 | 554 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 555 | q->nr_sorted++; |
9817064b JA |
556 | if (rq_mergeable(rq)) { |
557 | elv_rqhash_add(q, rq); | |
558 | if (!q->last_merge) | |
559 | q->last_merge = rq; | |
560 | } | |
561 | ||
ca23509f TH |
562 | /* |
563 | * Some ioscheds (cfq) run q->request_fn directly, so | |
564 | * rq cannot be accessed after calling | |
565 | * elevator_add_req_fn. | |
566 | */ | |
567 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
568 | break; |
569 | ||
797e7dbb TH |
570 | case ELEVATOR_INSERT_REQUEUE: |
571 | /* | |
572 | * If ordered flush isn't in progress, we do front | |
573 | * insertion; otherwise, requests should be requeued | |
574 | * in ordseq order. | |
575 | */ | |
4aff5e23 | 576 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb TH |
577 | |
578 | if (q->ordseq == 0) { | |
579 | list_add(&rq->queuelist, &q->queue_head); | |
580 | break; | |
581 | } | |
582 | ||
583 | ordseq = blk_ordered_req_seq(rq); | |
584 | ||
585 | list_for_each(pos, &q->queue_head) { | |
586 | struct request *pos_rq = list_entry_rq(pos); | |
587 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
588 | break; | |
589 | } | |
590 | ||
591 | list_add_tail(&rq->queuelist, pos); | |
dac07ec1 JA |
592 | /* |
593 | * most requeues happen because of a busy condition, don't | |
594 | * force unplug of the queue for that case. | |
595 | */ | |
596 | unplug_it = 0; | |
797e7dbb TH |
597 | break; |
598 | ||
8922e16c TH |
599 | default: |
600 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
601 | __FUNCTION__, where); | |
602 | BUG(); | |
603 | } | |
604 | ||
dac07ec1 | 605 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
606 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
607 | - q->in_flight; | |
608 | ||
609 | if (nrq >= q->unplug_thresh) | |
610 | __generic_unplug_device(q); | |
611 | } | |
1da177e4 LT |
612 | } |
613 | ||
30e9656c TH |
614 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
615 | int plug) | |
616 | { | |
617 | if (q->ordcolor) | |
4aff5e23 | 618 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 619 | |
4aff5e23 | 620 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
621 | /* |
622 | * toggle ordered color | |
623 | */ | |
624 | if (blk_barrier_rq(rq)) | |
625 | q->ordcolor ^= 1; | |
626 | ||
627 | /* | |
628 | * barriers implicitly indicate back insertion | |
629 | */ | |
630 | if (where == ELEVATOR_INSERT_SORT) | |
631 | where = ELEVATOR_INSERT_BACK; | |
632 | ||
633 | /* | |
634 | * this request is scheduling boundary, update | |
635 | * end_sector | |
636 | */ | |
637 | if (blk_fs_request(rq)) { | |
638 | q->end_sector = rq_end_sector(rq); | |
639 | q->boundary_rq = rq; | |
640 | } | |
4aff5e23 | 641 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) |
30e9656c TH |
642 | where = ELEVATOR_INSERT_BACK; |
643 | ||
644 | if (plug) | |
645 | blk_plug_device(q); | |
646 | ||
647 | elv_insert(q, rq, where); | |
648 | } | |
649 | ||
2e662b65 JA |
650 | EXPORT_SYMBOL(__elv_add_request); |
651 | ||
1da177e4 LT |
652 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
653 | int plug) | |
654 | { | |
655 | unsigned long flags; | |
656 | ||
657 | spin_lock_irqsave(q->queue_lock, flags); | |
658 | __elv_add_request(q, rq, where, plug); | |
659 | spin_unlock_irqrestore(q->queue_lock, flags); | |
660 | } | |
661 | ||
2e662b65 JA |
662 | EXPORT_SYMBOL(elv_add_request); |
663 | ||
1da177e4 LT |
664 | static inline struct request *__elv_next_request(request_queue_t *q) |
665 | { | |
8922e16c TH |
666 | struct request *rq; |
667 | ||
797e7dbb TH |
668 | while (1) { |
669 | while (!list_empty(&q->queue_head)) { | |
670 | rq = list_entry_rq(q->queue_head.next); | |
671 | if (blk_do_ordered(q, &rq)) | |
672 | return rq; | |
673 | } | |
1da177e4 | 674 | |
797e7dbb TH |
675 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
676 | return NULL; | |
1da177e4 | 677 | } |
1da177e4 LT |
678 | } |
679 | ||
680 | struct request *elv_next_request(request_queue_t *q) | |
681 | { | |
682 | struct request *rq; | |
683 | int ret; | |
684 | ||
685 | while ((rq = __elv_next_request(q)) != NULL) { | |
4aff5e23 | 686 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
687 | elevator_t *e = q->elevator; |
688 | ||
689 | /* | |
690 | * This is the first time the device driver | |
691 | * sees this request (possibly after | |
692 | * requeueing). Notify IO scheduler. | |
693 | */ | |
694 | if (blk_sorted_rq(rq) && | |
695 | e->ops->elevator_activate_req_fn) | |
696 | e->ops->elevator_activate_req_fn(q, rq); | |
1da177e4 | 697 | |
8922e16c TH |
698 | /* |
699 | * just mark as started even if we don't start | |
700 | * it, a request that has been delayed should | |
701 | * not be passed by new incoming requests | |
702 | */ | |
4aff5e23 | 703 | rq->cmd_flags |= REQ_STARTED; |
2056a782 | 704 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 705 | } |
1da177e4 | 706 | |
8922e16c | 707 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 708 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
709 | q->boundary_rq = NULL; |
710 | } | |
1da177e4 | 711 | |
4aff5e23 | 712 | if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn) |
1da177e4 LT |
713 | break; |
714 | ||
715 | ret = q->prep_rq_fn(q, rq); | |
716 | if (ret == BLKPREP_OK) { | |
717 | break; | |
718 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
719 | /* |
720 | * the request may have been (partially) prepped. | |
721 | * we need to keep this request in the front to | |
8922e16c TH |
722 | * avoid resource deadlock. REQ_STARTED will |
723 | * prevent other fs requests from passing this one. | |
2e759cd4 | 724 | */ |
1da177e4 LT |
725 | rq = NULL; |
726 | break; | |
727 | } else if (ret == BLKPREP_KILL) { | |
728 | int nr_bytes = rq->hard_nr_sectors << 9; | |
729 | ||
730 | if (!nr_bytes) | |
731 | nr_bytes = rq->data_len; | |
732 | ||
733 | blkdev_dequeue_request(rq); | |
4aff5e23 | 734 | rq->cmd_flags |= REQ_QUIET; |
1da177e4 | 735 | end_that_request_chunk(rq, 0, nr_bytes); |
8ffdc655 | 736 | end_that_request_last(rq, 0); |
1da177e4 LT |
737 | } else { |
738 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
739 | ret); | |
740 | break; | |
741 | } | |
742 | } | |
743 | ||
744 | return rq; | |
745 | } | |
746 | ||
2e662b65 JA |
747 | EXPORT_SYMBOL(elv_next_request); |
748 | ||
8922e16c | 749 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 750 | { |
8922e16c | 751 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 752 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
753 | |
754 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
755 | |
756 | /* | |
757 | * the time frame between a request being removed from the lists | |
758 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 759 | * the driver side. |
1da177e4 LT |
760 | */ |
761 | if (blk_account_rq(rq)) | |
762 | q->in_flight++; | |
1da177e4 LT |
763 | } |
764 | ||
2e662b65 JA |
765 | EXPORT_SYMBOL(elv_dequeue_request); |
766 | ||
1da177e4 LT |
767 | int elv_queue_empty(request_queue_t *q) |
768 | { | |
769 | elevator_t *e = q->elevator; | |
770 | ||
8922e16c TH |
771 | if (!list_empty(&q->queue_head)) |
772 | return 0; | |
773 | ||
1da177e4 LT |
774 | if (e->ops->elevator_queue_empty_fn) |
775 | return e->ops->elevator_queue_empty_fn(q); | |
776 | ||
8922e16c | 777 | return 1; |
1da177e4 LT |
778 | } |
779 | ||
2e662b65 JA |
780 | EXPORT_SYMBOL(elv_queue_empty); |
781 | ||
1da177e4 LT |
782 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) |
783 | { | |
1da177e4 LT |
784 | elevator_t *e = q->elevator; |
785 | ||
786 | if (e->ops->elevator_latter_req_fn) | |
787 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
788 | return NULL; |
789 | } | |
790 | ||
791 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
792 | { | |
1da177e4 LT |
793 | elevator_t *e = q->elevator; |
794 | ||
795 | if (e->ops->elevator_former_req_fn) | |
796 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
797 | return NULL; |
798 | } | |
799 | ||
cb78b285 | 800 | int elv_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
801 | { |
802 | elevator_t *e = q->elevator; | |
803 | ||
804 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 805 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
806 | |
807 | rq->elevator_private = NULL; | |
808 | return 0; | |
809 | } | |
810 | ||
811 | void elv_put_request(request_queue_t *q, struct request *rq) | |
812 | { | |
813 | elevator_t *e = q->elevator; | |
814 | ||
815 | if (e->ops->elevator_put_req_fn) | |
816 | e->ops->elevator_put_req_fn(q, rq); | |
817 | } | |
818 | ||
cb78b285 | 819 | int elv_may_queue(request_queue_t *q, int rw) |
1da177e4 LT |
820 | { |
821 | elevator_t *e = q->elevator; | |
822 | ||
823 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 824 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
825 | |
826 | return ELV_MQUEUE_MAY; | |
827 | } | |
828 | ||
829 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
830 | { | |
831 | elevator_t *e = q->elevator; | |
832 | ||
833 | /* | |
834 | * request is released from the driver, io must be done | |
835 | */ | |
8922e16c | 836 | if (blk_account_rq(rq)) { |
1da177e4 | 837 | q->in_flight--; |
1bc691d3 TH |
838 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
839 | e->ops->elevator_completed_req_fn(q, rq); | |
840 | } | |
797e7dbb | 841 | |
1bc691d3 TH |
842 | /* |
843 | * Check if the queue is waiting for fs requests to be | |
844 | * drained for flush sequence. | |
845 | */ | |
846 | if (unlikely(q->ordseq)) { | |
847 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
848 | if (q->in_flight == 0 && | |
797e7dbb TH |
849 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
850 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
851 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
852 | q->request_fn(q); | |
853 | } | |
8922e16c | 854 | } |
1da177e4 LT |
855 | } |
856 | ||
3d1ab40f AV |
857 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
858 | ||
859 | static ssize_t | |
860 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 861 | { |
3d1ab40f AV |
862 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
863 | struct elv_fs_entry *entry = to_elv(attr); | |
864 | ssize_t error; | |
865 | ||
866 | if (!entry->show) | |
867 | return -EIO; | |
868 | ||
869 | mutex_lock(&e->sysfs_lock); | |
870 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
871 | mutex_unlock(&e->sysfs_lock); | |
872 | return error; | |
873 | } | |
1da177e4 | 874 | |
3d1ab40f AV |
875 | static ssize_t |
876 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
877 | const char *page, size_t length) | |
878 | { | |
879 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
880 | struct elv_fs_entry *entry = to_elv(attr); | |
881 | ssize_t error; | |
1da177e4 | 882 | |
3d1ab40f AV |
883 | if (!entry->store) |
884 | return -EIO; | |
1da177e4 | 885 | |
3d1ab40f AV |
886 | mutex_lock(&e->sysfs_lock); |
887 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
888 | mutex_unlock(&e->sysfs_lock); | |
889 | return error; | |
890 | } | |
891 | ||
892 | static struct sysfs_ops elv_sysfs_ops = { | |
893 | .show = elv_attr_show, | |
894 | .store = elv_attr_store, | |
895 | }; | |
896 | ||
897 | static struct kobj_type elv_ktype = { | |
898 | .sysfs_ops = &elv_sysfs_ops, | |
899 | .release = elevator_release, | |
900 | }; | |
901 | ||
902 | int elv_register_queue(struct request_queue *q) | |
903 | { | |
904 | elevator_t *e = q->elevator; | |
905 | int error; | |
906 | ||
907 | e->kobj.parent = &q->kobj; | |
908 | ||
909 | error = kobject_add(&e->kobj); | |
910 | if (!error) { | |
e572ec7e | 911 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 912 | if (attr) { |
e572ec7e AV |
913 | while (attr->attr.name) { |
914 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 915 | break; |
e572ec7e | 916 | attr++; |
3d1ab40f AV |
917 | } |
918 | } | |
919 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
920 | } | |
921 | return error; | |
1da177e4 LT |
922 | } |
923 | ||
bc1c1169 JA |
924 | static void __elv_unregister_queue(elevator_t *e) |
925 | { | |
926 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
927 | kobject_del(&e->kobj); | |
928 | } | |
929 | ||
1da177e4 LT |
930 | void elv_unregister_queue(struct request_queue *q) |
931 | { | |
bc1c1169 JA |
932 | if (q) |
933 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
934 | } |
935 | ||
936 | int elv_register(struct elevator_type *e) | |
937 | { | |
2824bc93 | 938 | spin_lock_irq(&elv_list_lock); |
ce524497 | 939 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 LT |
940 | list_add_tail(&e->list, &elv_list); |
941 | spin_unlock_irq(&elv_list_lock); | |
942 | ||
943 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
944 | if (!strcmp(e->elevator_name, chosen_elevator) || |
945 | (!*chosen_elevator && | |
946 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
947 | printk(" (default)"); | |
1da177e4 LT |
948 | printk("\n"); |
949 | return 0; | |
950 | } | |
951 | EXPORT_SYMBOL_GPL(elv_register); | |
952 | ||
953 | void elv_unregister(struct elevator_type *e) | |
954 | { | |
83521d3e CH |
955 | struct task_struct *g, *p; |
956 | ||
957 | /* | |
958 | * Iterate every thread in the process to remove the io contexts. | |
959 | */ | |
e17a9489 AV |
960 | if (e->ops.trim) { |
961 | read_lock(&tasklist_lock); | |
962 | do_each_thread(g, p) { | |
963 | task_lock(p); | |
2d8f6131 ON |
964 | if (p->io_context) |
965 | e->ops.trim(p->io_context); | |
e17a9489 AV |
966 | task_unlock(p); |
967 | } while_each_thread(g, p); | |
968 | read_unlock(&tasklist_lock); | |
969 | } | |
83521d3e | 970 | |
1da177e4 LT |
971 | spin_lock_irq(&elv_list_lock); |
972 | list_del_init(&e->list); | |
973 | spin_unlock_irq(&elv_list_lock); | |
974 | } | |
975 | EXPORT_SYMBOL_GPL(elv_unregister); | |
976 | ||
977 | /* | |
978 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
979 | * we don't free the old io scheduler, before we have allocated what we | |
980 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 981 | * one, if the new one fails init for some reason. |
1da177e4 | 982 | */ |
3d1ab40f | 983 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
1da177e4 | 984 | { |
cb98fc8b | 985 | elevator_t *old_elevator, *e; |
bc1c1169 | 986 | void *data; |
1da177e4 | 987 | |
cb98fc8b TH |
988 | /* |
989 | * Allocate new elevator | |
990 | */ | |
b5deef90 | 991 | e = elevator_alloc(q, new_e); |
1da177e4 | 992 | if (!e) |
3d1ab40f | 993 | return 0; |
1da177e4 | 994 | |
bc1c1169 JA |
995 | data = elevator_init_queue(q, e); |
996 | if (!data) { | |
997 | kobject_put(&e->kobj); | |
998 | return 0; | |
999 | } | |
1000 | ||
1da177e4 | 1001 | /* |
cb98fc8b | 1002 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1003 | */ |
cb98fc8b TH |
1004 | spin_lock_irq(q->queue_lock); |
1005 | ||
64521d1a | 1006 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 1007 | |
15853af9 | 1008 | elv_drain_elevator(q); |
cb98fc8b TH |
1009 | |
1010 | while (q->rq.elvpriv) { | |
407df2aa TH |
1011 | blk_remove_plug(q); |
1012 | q->request_fn(q); | |
cb98fc8b | 1013 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1014 | msleep(10); |
cb98fc8b | 1015 | spin_lock_irq(q->queue_lock); |
15853af9 | 1016 | elv_drain_elevator(q); |
cb98fc8b TH |
1017 | } |
1018 | ||
1da177e4 | 1019 | /* |
bc1c1169 | 1020 | * Remember old elevator. |
1da177e4 | 1021 | */ |
1da177e4 LT |
1022 | old_elevator = q->elevator; |
1023 | ||
1da177e4 LT |
1024 | /* |
1025 | * attach and start new elevator | |
1026 | */ | |
bc1c1169 JA |
1027 | elevator_attach(q, e, data); |
1028 | ||
1029 | spin_unlock_irq(q->queue_lock); | |
1030 | ||
1031 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1032 | |
1033 | if (elv_register_queue(q)) | |
1034 | goto fail_register; | |
1035 | ||
1036 | /* | |
cb98fc8b | 1037 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1038 | */ |
1039 | elevator_exit(old_elevator); | |
64521d1a | 1040 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1041 | return 1; |
1da177e4 LT |
1042 | |
1043 | fail_register: | |
1044 | /* | |
1045 | * switch failed, exit the new io scheduler and reattach the old | |
1046 | * one again (along with re-adding the sysfs dir) | |
1047 | */ | |
1048 | elevator_exit(e); | |
1da177e4 LT |
1049 | q->elevator = old_elevator; |
1050 | elv_register_queue(q); | |
64521d1a | 1051 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 1052 | return 0; |
1da177e4 LT |
1053 | } |
1054 | ||
1055 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
1056 | { | |
1057 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 1058 | size_t len; |
1da177e4 LT |
1059 | struct elevator_type *e; |
1060 | ||
be561235 TH |
1061 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
1062 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
1063 | len = strlen(elevator_name); | |
1da177e4 | 1064 | |
be561235 TH |
1065 | if (len && elevator_name[len - 1] == '\n') |
1066 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
1067 | |
1068 | e = elevator_get(elevator_name); | |
1069 | if (!e) { | |
1070 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1071 | return -EINVAL; | |
1072 | } | |
1073 | ||
2ca7d93b ND |
1074 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1075 | elevator_put(e); | |
1da177e4 | 1076 | return count; |
2ca7d93b | 1077 | } |
1da177e4 | 1078 | |
3d1ab40f AV |
1079 | if (!elevator_switch(q, e)) |
1080 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
1081 | return count; |
1082 | } | |
1083 | ||
1084 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
1085 | { | |
1086 | elevator_t *e = q->elevator; | |
1087 | struct elevator_type *elv = e->elevator_type; | |
1088 | struct list_head *entry; | |
1089 | int len = 0; | |
1090 | ||
1091 | spin_lock_irq(q->queue_lock); | |
1092 | list_for_each(entry, &elv_list) { | |
1093 | struct elevator_type *__e; | |
1094 | ||
1095 | __e = list_entry(entry, struct elevator_type, list); | |
1096 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
1097 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1098 | else | |
1099 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1100 | } | |
1101 | spin_unlock_irq(q->queue_lock); | |
1102 | ||
1103 | len += sprintf(len+name, "\n"); | |
1104 | return len; | |
1105 | } | |
1106 | ||
2e662b65 JA |
1107 | struct request *elv_rb_former_request(request_queue_t *q, struct request *rq) |
1108 | { | |
1109 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1110 | ||
1111 | if (rbprev) | |
1112 | return rb_entry_rq(rbprev); | |
1113 | ||
1114 | return NULL; | |
1115 | } | |
1116 | ||
1117 | EXPORT_SYMBOL(elv_rb_former_request); | |
1118 | ||
1119 | struct request *elv_rb_latter_request(request_queue_t *q, struct request *rq) | |
1120 | { | |
1121 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1122 | ||
1123 | if (rbnext) | |
1124 | return rb_entry_rq(rbnext); | |
1125 | ||
1126 | return NULL; | |
1127 | } | |
1128 | ||
1129 | EXPORT_SYMBOL(elv_rb_latter_request); |