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