Root/
Source at commit 2604e7f9a98c27be50a0c3ff7503b6a5ea8f6cfe created 12 years 7 months ago. By Maarten ter Huurne, cpufreq_stats: Support runtime changes to frequency table | |
---|---|
1 | /* |
2 | * Block device elevator/IO-scheduler. |
3 | * |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE |
5 | * |
6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
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> |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> |
32 | #include <linux/init.h> |
33 | #include <linux/compiler.h> |
34 | #include <linux/blktrace_api.h> |
35 | #include <linux/hash.h> |
36 | #include <linux/uaccess.h> |
37 | |
38 | #include <trace/events/block.h> |
39 | |
40 | #include "blk.h" |
41 | #include "blk-cgroup.h" |
42 | |
43 | static DEFINE_SPINLOCK(elv_list_lock); |
44 | static LIST_HEAD(elv_list); |
45 | |
46 | /* |
47 | * Merge hash stuff. |
48 | */ |
49 | static const int elv_hash_shift = 6; |
50 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) |
51 | #define ELV_HASH_FN(sec) \ |
52 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) |
53 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
54 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
55 | |
56 | /* |
57 | * Query io scheduler to see if the current process issuing bio may be |
58 | * merged with rq. |
59 | */ |
60 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) |
61 | { |
62 | struct request_queue *q = rq->q; |
63 | struct elevator_queue *e = q->elevator; |
64 | |
65 | if (e->type->ops.elevator_allow_merge_fn) |
66 | return e->type->ops.elevator_allow_merge_fn(q, rq, bio); |
67 | |
68 | return 1; |
69 | } |
70 | |
71 | /* |
72 | * can we safely merge with this request? |
73 | */ |
74 | bool elv_rq_merge_ok(struct request *rq, struct bio *bio) |
75 | { |
76 | if (!blk_rq_merge_ok(rq, bio)) |
77 | return 0; |
78 | |
79 | if (!elv_iosched_allow_merge(rq, bio)) |
80 | return 0; |
81 | |
82 | return 1; |
83 | } |
84 | EXPORT_SYMBOL(elv_rq_merge_ok); |
85 | |
86 | static struct elevator_type *elevator_find(const char *name) |
87 | { |
88 | struct elevator_type *e; |
89 | |
90 | list_for_each_entry(e, &elv_list, list) { |
91 | if (!strcmp(e->elevator_name, name)) |
92 | return e; |
93 | } |
94 | |
95 | return NULL; |
96 | } |
97 | |
98 | static void elevator_put(struct elevator_type *e) |
99 | { |
100 | module_put(e->elevator_owner); |
101 | } |
102 | |
103 | static struct elevator_type *elevator_get(const char *name) |
104 | { |
105 | struct elevator_type *e; |
106 | |
107 | spin_lock(&elv_list_lock); |
108 | |
109 | e = elevator_find(name); |
110 | if (!e) { |
111 | spin_unlock(&elv_list_lock); |
112 | request_module("%s-iosched", name); |
113 | spin_lock(&elv_list_lock); |
114 | e = elevator_find(name); |
115 | } |
116 | |
117 | if (e && !try_module_get(e->elevator_owner)) |
118 | e = NULL; |
119 | |
120 | spin_unlock(&elv_list_lock); |
121 | |
122 | return e; |
123 | } |
124 | |
125 | static char chosen_elevator[ELV_NAME_MAX]; |
126 | |
127 | static int __init elevator_setup(char *str) |
128 | { |
129 | /* |
130 | * Be backwards-compatible with previous kernels, so users |
131 | * won't get the wrong elevator. |
132 | */ |
133 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
134 | return 1; |
135 | } |
136 | |
137 | __setup("elevator=", elevator_setup); |
138 | |
139 | static struct kobj_type elv_ktype; |
140 | |
141 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
142 | struct elevator_type *e) |
143 | { |
144 | struct elevator_queue *eq; |
145 | int i; |
146 | |
147 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
148 | if (unlikely(!eq)) |
149 | goto err; |
150 | |
151 | eq->type = e; |
152 | kobject_init(&eq->kobj, &elv_ktype); |
153 | mutex_init(&eq->sysfs_lock); |
154 | |
155 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
156 | GFP_KERNEL, q->node); |
157 | if (!eq->hash) |
158 | goto err; |
159 | |
160 | for (i = 0; i < ELV_HASH_ENTRIES; i++) |
161 | INIT_HLIST_HEAD(&eq->hash[i]); |
162 | |
163 | return eq; |
164 | err: |
165 | kfree(eq); |
166 | elevator_put(e); |
167 | return NULL; |
168 | } |
169 | |
170 | static void elevator_release(struct kobject *kobj) |
171 | { |
172 | struct elevator_queue *e; |
173 | |
174 | e = container_of(kobj, struct elevator_queue, kobj); |
175 | elevator_put(e->type); |
176 | kfree(e->hash); |
177 | kfree(e); |
178 | } |
179 | |
180 | int elevator_init(struct request_queue *q, char *name) |
181 | { |
182 | struct elevator_type *e = NULL; |
183 | int err; |
184 | |
185 | if (unlikely(q->elevator)) |
186 | return 0; |
187 | |
188 | INIT_LIST_HEAD(&q->queue_head); |
189 | q->last_merge = NULL; |
190 | q->end_sector = 0; |
191 | q->boundary_rq = NULL; |
192 | |
193 | if (name) { |
194 | e = elevator_get(name); |
195 | if (!e) |
196 | return -EINVAL; |
197 | } |
198 | |
199 | if (!e && *chosen_elevator) { |
200 | e = elevator_get(chosen_elevator); |
201 | if (!e) |
202 | printk(KERN_ERR "I/O scheduler %s not found\n", |
203 | chosen_elevator); |
204 | } |
205 | |
206 | if (!e) { |
207 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); |
208 | if (!e) { |
209 | printk(KERN_ERR |
210 | "Default I/O scheduler not found. " \ |
211 | "Using noop.\n"); |
212 | e = elevator_get("noop"); |
213 | } |
214 | } |
215 | |
216 | q->elevator = elevator_alloc(q, e); |
217 | if (!q->elevator) |
218 | return -ENOMEM; |
219 | |
220 | err = e->ops.elevator_init_fn(q); |
221 | if (err) { |
222 | kobject_put(&q->elevator->kobj); |
223 | return err; |
224 | } |
225 | |
226 | return 0; |
227 | } |
228 | EXPORT_SYMBOL(elevator_init); |
229 | |
230 | void elevator_exit(struct elevator_queue *e) |
231 | { |
232 | mutex_lock(&e->sysfs_lock); |
233 | if (e->type->ops.elevator_exit_fn) |
234 | e->type->ops.elevator_exit_fn(e); |
235 | mutex_unlock(&e->sysfs_lock); |
236 | |
237 | kobject_put(&e->kobj); |
238 | } |
239 | EXPORT_SYMBOL(elevator_exit); |
240 | |
241 | static inline void __elv_rqhash_del(struct request *rq) |
242 | { |
243 | hlist_del_init(&rq->hash); |
244 | } |
245 | |
246 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
247 | { |
248 | if (ELV_ON_HASH(rq)) |
249 | __elv_rqhash_del(rq); |
250 | } |
251 | |
252 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
253 | { |
254 | struct elevator_queue *e = q->elevator; |
255 | |
256 | BUG_ON(ELV_ON_HASH(rq)); |
257 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); |
258 | } |
259 | |
260 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
261 | { |
262 | __elv_rqhash_del(rq); |
263 | elv_rqhash_add(q, rq); |
264 | } |
265 | |
266 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
267 | { |
268 | struct elevator_queue *e = q->elevator; |
269 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
270 | struct hlist_node *entry, *next; |
271 | struct request *rq; |
272 | |
273 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { |
274 | BUG_ON(!ELV_ON_HASH(rq)); |
275 | |
276 | if (unlikely(!rq_mergeable(rq))) { |
277 | __elv_rqhash_del(rq); |
278 | continue; |
279 | } |
280 | |
281 | if (rq_hash_key(rq) == offset) |
282 | return rq; |
283 | } |
284 | |
285 | return NULL; |
286 | } |
287 | |
288 | /* |
289 | * RB-tree support functions for inserting/lookup/removal of requests |
290 | * in a sorted RB tree. |
291 | */ |
292 | void elv_rb_add(struct rb_root *root, struct request *rq) |
293 | { |
294 | struct rb_node **p = &root->rb_node; |
295 | struct rb_node *parent = NULL; |
296 | struct request *__rq; |
297 | |
298 | while (*p) { |
299 | parent = *p; |
300 | __rq = rb_entry(parent, struct request, rb_node); |
301 | |
302 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
303 | p = &(*p)->rb_left; |
304 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
305 | p = &(*p)->rb_right; |
306 | } |
307 | |
308 | rb_link_node(&rq->rb_node, parent, p); |
309 | rb_insert_color(&rq->rb_node, root); |
310 | } |
311 | EXPORT_SYMBOL(elv_rb_add); |
312 | |
313 | void elv_rb_del(struct rb_root *root, struct request *rq) |
314 | { |
315 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); |
316 | rb_erase(&rq->rb_node, root); |
317 | RB_CLEAR_NODE(&rq->rb_node); |
318 | } |
319 | EXPORT_SYMBOL(elv_rb_del); |
320 | |
321 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) |
322 | { |
323 | struct rb_node *n = root->rb_node; |
324 | struct request *rq; |
325 | |
326 | while (n) { |
327 | rq = rb_entry(n, struct request, rb_node); |
328 | |
329 | if (sector < blk_rq_pos(rq)) |
330 | n = n->rb_left; |
331 | else if (sector > blk_rq_pos(rq)) |
332 | n = n->rb_right; |
333 | else |
334 | return rq; |
335 | } |
336 | |
337 | return NULL; |
338 | } |
339 | EXPORT_SYMBOL(elv_rb_find); |
340 | |
341 | /* |
342 | * Insert rq into dispatch queue of q. Queue lock must be held on |
343 | * entry. rq is sort instead into the dispatch queue. To be used by |
344 | * specific elevators. |
345 | */ |
346 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
347 | { |
348 | sector_t boundary; |
349 | struct list_head *entry; |
350 | int stop_flags; |
351 | |
352 | if (q->last_merge == rq) |
353 | q->last_merge = NULL; |
354 | |
355 | elv_rqhash_del(q, rq); |
356 | |
357 | q->nr_sorted--; |
358 | |
359 | boundary = q->end_sector; |
360 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
361 | list_for_each_prev(entry, &q->queue_head) { |
362 | struct request *pos = list_entry_rq(entry); |
363 | |
364 | if ((rq->cmd_flags & REQ_DISCARD) != |
365 | (pos->cmd_flags & REQ_DISCARD)) |
366 | break; |
367 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
368 | break; |
369 | if (pos->cmd_flags & stop_flags) |
370 | break; |
371 | if (blk_rq_pos(rq) >= boundary) { |
372 | if (blk_rq_pos(pos) < boundary) |
373 | continue; |
374 | } else { |
375 | if (blk_rq_pos(pos) >= boundary) |
376 | break; |
377 | } |
378 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
379 | break; |
380 | } |
381 | |
382 | list_add(&rq->queuelist, entry); |
383 | } |
384 | EXPORT_SYMBOL(elv_dispatch_sort); |
385 | |
386 | /* |
387 | * Insert rq into dispatch queue of q. Queue lock must be held on |
388 | * entry. rq is added to the back of the dispatch queue. To be used by |
389 | * specific elevators. |
390 | */ |
391 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) |
392 | { |
393 | if (q->last_merge == rq) |
394 | q->last_merge = NULL; |
395 | |
396 | elv_rqhash_del(q, rq); |
397 | |
398 | q->nr_sorted--; |
399 | |
400 | q->end_sector = rq_end_sector(rq); |
401 | q->boundary_rq = rq; |
402 | list_add_tail(&rq->queuelist, &q->queue_head); |
403 | } |
404 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
405 | |
406 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
407 | { |
408 | struct elevator_queue *e = q->elevator; |
409 | struct request *__rq; |
410 | int ret; |
411 | |
412 | /* |
413 | * Levels of merges: |
414 | * nomerges: No merges at all attempted |
415 | * noxmerges: Only simple one-hit cache try |
416 | * merges: All merge tries attempted |
417 | */ |
418 | if (blk_queue_nomerges(q)) |
419 | return ELEVATOR_NO_MERGE; |
420 | |
421 | /* |
422 | * First try one-hit cache. |
423 | */ |
424 | if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { |
425 | ret = blk_try_merge(q->last_merge, bio); |
426 | if (ret != ELEVATOR_NO_MERGE) { |
427 | *req = q->last_merge; |
428 | return ret; |
429 | } |
430 | } |
431 | |
432 | if (blk_queue_noxmerges(q)) |
433 | return ELEVATOR_NO_MERGE; |
434 | |
435 | /* |
436 | * See if our hash lookup can find a potential backmerge. |
437 | */ |
438 | __rq = elv_rqhash_find(q, bio->bi_sector); |
439 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
440 | *req = __rq; |
441 | return ELEVATOR_BACK_MERGE; |
442 | } |
443 | |
444 | if (e->type->ops.elevator_merge_fn) |
445 | return e->type->ops.elevator_merge_fn(q, req, bio); |
446 | |
447 | return ELEVATOR_NO_MERGE; |
448 | } |
449 | |
450 | /* |
451 | * Attempt to do an insertion back merge. Only check for the case where |
452 | * we can append 'rq' to an existing request, so we can throw 'rq' away |
453 | * afterwards. |
454 | * |
455 | * Returns true if we merged, false otherwise |
456 | */ |
457 | static bool elv_attempt_insert_merge(struct request_queue *q, |
458 | struct request *rq) |
459 | { |
460 | struct request *__rq; |
461 | |
462 | if (blk_queue_nomerges(q)) |
463 | return false; |
464 | |
465 | /* |
466 | * First try one-hit cache. |
467 | */ |
468 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) |
469 | return true; |
470 | |
471 | if (blk_queue_noxmerges(q)) |
472 | return false; |
473 | |
474 | /* |
475 | * See if our hash lookup can find a potential backmerge. |
476 | */ |
477 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); |
478 | if (__rq && blk_attempt_req_merge(q, __rq, rq)) |
479 | return true; |
480 | |
481 | return false; |
482 | } |
483 | |
484 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
485 | { |
486 | struct elevator_queue *e = q->elevator; |
487 | |
488 | if (e->type->ops.elevator_merged_fn) |
489 | e->type->ops.elevator_merged_fn(q, rq, type); |
490 | |
491 | if (type == ELEVATOR_BACK_MERGE) |
492 | elv_rqhash_reposition(q, rq); |
493 | |
494 | q->last_merge = rq; |
495 | } |
496 | |
497 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
498 | struct request *next) |
499 | { |
500 | struct elevator_queue *e = q->elevator; |
501 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
502 | |
503 | if (next_sorted && e->type->ops.elevator_merge_req_fn) |
504 | e->type->ops.elevator_merge_req_fn(q, rq, next); |
505 | |
506 | elv_rqhash_reposition(q, rq); |
507 | |
508 | if (next_sorted) { |
509 | elv_rqhash_del(q, next); |
510 | q->nr_sorted--; |
511 | } |
512 | |
513 | q->last_merge = rq; |
514 | } |
515 | |
516 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
517 | struct bio *bio) |
518 | { |
519 | struct elevator_queue *e = q->elevator; |
520 | |
521 | if (e->type->ops.elevator_bio_merged_fn) |
522 | e->type->ops.elevator_bio_merged_fn(q, rq, bio); |
523 | } |
524 | |
525 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
526 | { |
527 | /* |
528 | * it already went through dequeue, we need to decrement the |
529 | * in_flight count again |
530 | */ |
531 | if (blk_account_rq(rq)) { |
532 | q->in_flight[rq_is_sync(rq)]--; |
533 | if (rq->cmd_flags & REQ_SORTED) |
534 | elv_deactivate_rq(q, rq); |
535 | } |
536 | |
537 | rq->cmd_flags &= ~REQ_STARTED; |
538 | |
539 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
540 | } |
541 | |
542 | void elv_drain_elevator(struct request_queue *q) |
543 | { |
544 | static int printed; |
545 | |
546 | lockdep_assert_held(q->queue_lock); |
547 | |
548 | while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
549 | ; |
550 | if (q->nr_sorted && printed++ < 10) { |
551 | printk(KERN_ERR "%s: forced dispatching is broken " |
552 | "(nr_sorted=%u), please report this\n", |
553 | q->elevator->type->elevator_name, q->nr_sorted); |
554 | } |
555 | } |
556 | |
557 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
558 | { |
559 | trace_block_rq_insert(q, rq); |
560 | |
561 | rq->q = q; |
562 | |
563 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
564 | /* barriers are scheduling boundary, update end_sector */ |
565 | if (rq->cmd_type == REQ_TYPE_FS || |
566 | (rq->cmd_flags & REQ_DISCARD)) { |
567 | q->end_sector = rq_end_sector(rq); |
568 | q->boundary_rq = rq; |
569 | } |
570 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
571 | (where == ELEVATOR_INSERT_SORT || |
572 | where == ELEVATOR_INSERT_SORT_MERGE)) |
573 | where = ELEVATOR_INSERT_BACK; |
574 | |
575 | switch (where) { |
576 | case ELEVATOR_INSERT_REQUEUE: |
577 | case ELEVATOR_INSERT_FRONT: |
578 | rq->cmd_flags |= REQ_SOFTBARRIER; |
579 | list_add(&rq->queuelist, &q->queue_head); |
580 | break; |
581 | |
582 | case ELEVATOR_INSERT_BACK: |
583 | rq->cmd_flags |= REQ_SOFTBARRIER; |
584 | elv_drain_elevator(q); |
585 | list_add_tail(&rq->queuelist, &q->queue_head); |
586 | /* |
587 | * We kick the queue here for the following reasons. |
588 | * - The elevator might have returned NULL previously |
589 | * to delay requests and returned them now. As the |
590 | * queue wasn't empty before this request, ll_rw_blk |
591 | * won't run the queue on return, resulting in hang. |
592 | * - Usually, back inserted requests won't be merged |
593 | * with anything. There's no point in delaying queue |
594 | * processing. |
595 | */ |
596 | __blk_run_queue(q); |
597 | break; |
598 | |
599 | case ELEVATOR_INSERT_SORT_MERGE: |
600 | /* |
601 | * If we succeed in merging this request with one in the |
602 | * queue already, we are done - rq has now been freed, |
603 | * so no need to do anything further. |
604 | */ |
605 | if (elv_attempt_insert_merge(q, rq)) |
606 | break; |
607 | case ELEVATOR_INSERT_SORT: |
608 | BUG_ON(rq->cmd_type != REQ_TYPE_FS && |
609 | !(rq->cmd_flags & REQ_DISCARD)); |
610 | rq->cmd_flags |= REQ_SORTED; |
611 | q->nr_sorted++; |
612 | if (rq_mergeable(rq)) { |
613 | elv_rqhash_add(q, rq); |
614 | if (!q->last_merge) |
615 | q->last_merge = rq; |
616 | } |
617 | |
618 | /* |
619 | * Some ioscheds (cfq) run q->request_fn directly, so |
620 | * rq cannot be accessed after calling |
621 | * elevator_add_req_fn. |
622 | */ |
623 | q->elevator->type->ops.elevator_add_req_fn(q, rq); |
624 | break; |
625 | |
626 | case ELEVATOR_INSERT_FLUSH: |
627 | rq->cmd_flags |= REQ_SOFTBARRIER; |
628 | blk_insert_flush(rq); |
629 | break; |
630 | default: |
631 | printk(KERN_ERR "%s: bad insertion point %d\n", |
632 | __func__, where); |
633 | BUG(); |
634 | } |
635 | } |
636 | EXPORT_SYMBOL(__elv_add_request); |
637 | |
638 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
639 | { |
640 | unsigned long flags; |
641 | |
642 | spin_lock_irqsave(q->queue_lock, flags); |
643 | __elv_add_request(q, rq, where); |
644 | spin_unlock_irqrestore(q->queue_lock, flags); |
645 | } |
646 | EXPORT_SYMBOL(elv_add_request); |
647 | |
648 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
649 | { |
650 | struct elevator_queue *e = q->elevator; |
651 | |
652 | if (e->type->ops.elevator_latter_req_fn) |
653 | return e->type->ops.elevator_latter_req_fn(q, rq); |
654 | return NULL; |
655 | } |
656 | |
657 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
658 | { |
659 | struct elevator_queue *e = q->elevator; |
660 | |
661 | if (e->type->ops.elevator_former_req_fn) |
662 | return e->type->ops.elevator_former_req_fn(q, rq); |
663 | return NULL; |
664 | } |
665 | |
666 | int elv_set_request(struct request_queue *q, struct request *rq, |
667 | struct bio *bio, gfp_t gfp_mask) |
668 | { |
669 | struct elevator_queue *e = q->elevator; |
670 | |
671 | if (e->type->ops.elevator_set_req_fn) |
672 | return e->type->ops.elevator_set_req_fn(q, rq, bio, gfp_mask); |
673 | return 0; |
674 | } |
675 | |
676 | void elv_put_request(struct request_queue *q, struct request *rq) |
677 | { |
678 | struct elevator_queue *e = q->elevator; |
679 | |
680 | if (e->type->ops.elevator_put_req_fn) |
681 | e->type->ops.elevator_put_req_fn(rq); |
682 | } |
683 | |
684 | int elv_may_queue(struct request_queue *q, int rw) |
685 | { |
686 | struct elevator_queue *e = q->elevator; |
687 | |
688 | if (e->type->ops.elevator_may_queue_fn) |
689 | return e->type->ops.elevator_may_queue_fn(q, rw); |
690 | |
691 | return ELV_MQUEUE_MAY; |
692 | } |
693 | |
694 | void elv_abort_queue(struct request_queue *q) |
695 | { |
696 | struct request *rq; |
697 | |
698 | blk_abort_flushes(q); |
699 | |
700 | while (!list_empty(&q->queue_head)) { |
701 | rq = list_entry_rq(q->queue_head.next); |
702 | rq->cmd_flags |= REQ_QUIET; |
703 | trace_block_rq_abort(q, rq); |
704 | /* |
705 | * Mark this request as started so we don't trigger |
706 | * any debug logic in the end I/O path. |
707 | */ |
708 | blk_start_request(rq); |
709 | __blk_end_request_all(rq, -EIO); |
710 | } |
711 | } |
712 | EXPORT_SYMBOL(elv_abort_queue); |
713 | |
714 | void elv_completed_request(struct request_queue *q, struct request *rq) |
715 | { |
716 | struct elevator_queue *e = q->elevator; |
717 | |
718 | /* |
719 | * request is released from the driver, io must be done |
720 | */ |
721 | if (blk_account_rq(rq)) { |
722 | q->in_flight[rq_is_sync(rq)]--; |
723 | if ((rq->cmd_flags & REQ_SORTED) && |
724 | e->type->ops.elevator_completed_req_fn) |
725 | e->type->ops.elevator_completed_req_fn(q, rq); |
726 | } |
727 | } |
728 | |
729 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
730 | |
731 | static ssize_t |
732 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) |
733 | { |
734 | struct elv_fs_entry *entry = to_elv(attr); |
735 | struct elevator_queue *e; |
736 | ssize_t error; |
737 | |
738 | if (!entry->show) |
739 | return -EIO; |
740 | |
741 | e = container_of(kobj, struct elevator_queue, kobj); |
742 | mutex_lock(&e->sysfs_lock); |
743 | error = e->type ? entry->show(e, page) : -ENOENT; |
744 | mutex_unlock(&e->sysfs_lock); |
745 | return error; |
746 | } |
747 | |
748 | static ssize_t |
749 | elv_attr_store(struct kobject *kobj, struct attribute *attr, |
750 | const char *page, size_t length) |
751 | { |
752 | struct elv_fs_entry *entry = to_elv(attr); |
753 | struct elevator_queue *e; |
754 | ssize_t error; |
755 | |
756 | if (!entry->store) |
757 | return -EIO; |
758 | |
759 | e = container_of(kobj, struct elevator_queue, kobj); |
760 | mutex_lock(&e->sysfs_lock); |
761 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
762 | mutex_unlock(&e->sysfs_lock); |
763 | return error; |
764 | } |
765 | |
766 | static const struct sysfs_ops elv_sysfs_ops = { |
767 | .show = elv_attr_show, |
768 | .store = elv_attr_store, |
769 | }; |
770 | |
771 | static struct kobj_type elv_ktype = { |
772 | .sysfs_ops = &elv_sysfs_ops, |
773 | .release = elevator_release, |
774 | }; |
775 | |
776 | int elv_register_queue(struct request_queue *q) |
777 | { |
778 | struct elevator_queue *e = q->elevator; |
779 | int error; |
780 | |
781 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
782 | if (!error) { |
783 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
784 | if (attr) { |
785 | while (attr->attr.name) { |
786 | if (sysfs_create_file(&e->kobj, &attr->attr)) |
787 | break; |
788 | attr++; |
789 | } |
790 | } |
791 | kobject_uevent(&e->kobj, KOBJ_ADD); |
792 | e->registered = 1; |
793 | } |
794 | return error; |
795 | } |
796 | EXPORT_SYMBOL(elv_register_queue); |
797 | |
798 | void elv_unregister_queue(struct request_queue *q) |
799 | { |
800 | if (q) { |
801 | struct elevator_queue *e = q->elevator; |
802 | |
803 | kobject_uevent(&e->kobj, KOBJ_REMOVE); |
804 | kobject_del(&e->kobj); |
805 | e->registered = 0; |
806 | } |
807 | } |
808 | EXPORT_SYMBOL(elv_unregister_queue); |
809 | |
810 | int elv_register(struct elevator_type *e) |
811 | { |
812 | char *def = ""; |
813 | |
814 | /* create icq_cache if requested */ |
815 | if (e->icq_size) { |
816 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || |
817 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) |
818 | return -EINVAL; |
819 | |
820 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), |
821 | "%s_io_cq", e->elevator_name); |
822 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, |
823 | e->icq_align, 0, NULL); |
824 | if (!e->icq_cache) |
825 | return -ENOMEM; |
826 | } |
827 | |
828 | /* register, don't allow duplicate names */ |
829 | spin_lock(&elv_list_lock); |
830 | if (elevator_find(e->elevator_name)) { |
831 | spin_unlock(&elv_list_lock); |
832 | if (e->icq_cache) |
833 | kmem_cache_destroy(e->icq_cache); |
834 | return -EBUSY; |
835 | } |
836 | list_add_tail(&e->list, &elv_list); |
837 | spin_unlock(&elv_list_lock); |
838 | |
839 | /* print pretty message */ |
840 | if (!strcmp(e->elevator_name, chosen_elevator) || |
841 | (!*chosen_elevator && |
842 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) |
843 | def = " (default)"; |
844 | |
845 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
846 | def); |
847 | return 0; |
848 | } |
849 | EXPORT_SYMBOL_GPL(elv_register); |
850 | |
851 | void elv_unregister(struct elevator_type *e) |
852 | { |
853 | /* unregister */ |
854 | spin_lock(&elv_list_lock); |
855 | list_del_init(&e->list); |
856 | spin_unlock(&elv_list_lock); |
857 | |
858 | /* |
859 | * Destroy icq_cache if it exists. icq's are RCU managed. Make |
860 | * sure all RCU operations are complete before proceeding. |
861 | */ |
862 | if (e->icq_cache) { |
863 | rcu_barrier(); |
864 | kmem_cache_destroy(e->icq_cache); |
865 | e->icq_cache = NULL; |
866 | } |
867 | } |
868 | EXPORT_SYMBOL_GPL(elv_unregister); |
869 | |
870 | /* |
871 | * switch to new_e io scheduler. be careful not to introduce deadlocks - |
872 | * we don't free the old io scheduler, before we have allocated what we |
873 | * need for the new one. this way we have a chance of going back to the old |
874 | * one, if the new one fails init for some reason. |
875 | */ |
876 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
877 | { |
878 | struct elevator_queue *old = q->elevator; |
879 | bool registered = old->registered; |
880 | int err; |
881 | |
882 | /* |
883 | * Turn on BYPASS and drain all requests w/ elevator private data. |
884 | * Block layer doesn't call into a quiesced elevator - all requests |
885 | * are directly put on the dispatch list without elevator data |
886 | * using INSERT_BACK. All requests have SOFTBARRIER set and no |
887 | * merge happens either. |
888 | */ |
889 | blk_queue_bypass_start(q); |
890 | |
891 | /* unregister and clear all auxiliary data of the old elevator */ |
892 | if (registered) |
893 | elv_unregister_queue(q); |
894 | |
895 | spin_lock_irq(q->queue_lock); |
896 | ioc_clear_queue(q); |
897 | spin_unlock_irq(q->queue_lock); |
898 | |
899 | /* allocate, init and register new elevator */ |
900 | err = -ENOMEM; |
901 | q->elevator = elevator_alloc(q, new_e); |
902 | if (!q->elevator) |
903 | goto fail_init; |
904 | |
905 | err = new_e->ops.elevator_init_fn(q); |
906 | if (err) { |
907 | kobject_put(&q->elevator->kobj); |
908 | goto fail_init; |
909 | } |
910 | |
911 | if (registered) { |
912 | err = elv_register_queue(q); |
913 | if (err) |
914 | goto fail_register; |
915 | } |
916 | |
917 | /* done, kill the old one and finish */ |
918 | elevator_exit(old); |
919 | blk_queue_bypass_end(q); |
920 | |
921 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
922 | |
923 | return 0; |
924 | |
925 | fail_register: |
926 | elevator_exit(q->elevator); |
927 | fail_init: |
928 | /* switch failed, restore and re-register old elevator */ |
929 | q->elevator = old; |
930 | elv_register_queue(q); |
931 | blk_queue_bypass_end(q); |
932 | |
933 | return err; |
934 | } |
935 | |
936 | /* |
937 | * Switch this queue to the given IO scheduler. |
938 | */ |
939 | int elevator_change(struct request_queue *q, const char *name) |
940 | { |
941 | char elevator_name[ELV_NAME_MAX]; |
942 | struct elevator_type *e; |
943 | |
944 | if (!q->elevator) |
945 | return -ENXIO; |
946 | |
947 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
948 | e = elevator_get(strstrip(elevator_name)); |
949 | if (!e) { |
950 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); |
951 | return -EINVAL; |
952 | } |
953 | |
954 | if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
955 | elevator_put(e); |
956 | return 0; |
957 | } |
958 | |
959 | return elevator_switch(q, e); |
960 | } |
961 | EXPORT_SYMBOL(elevator_change); |
962 | |
963 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
964 | size_t count) |
965 | { |
966 | int ret; |
967 | |
968 | if (!q->elevator) |
969 | return count; |
970 | |
971 | ret = elevator_change(q, name); |
972 | if (!ret) |
973 | return count; |
974 | |
975 | printk(KERN_ERR "elevator: switch to %s failed\n", name); |
976 | return ret; |
977 | } |
978 | |
979 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
980 | { |
981 | struct elevator_queue *e = q->elevator; |
982 | struct elevator_type *elv; |
983 | struct elevator_type *__e; |
984 | int len = 0; |
985 | |
986 | if (!q->elevator || !blk_queue_stackable(q)) |
987 | return sprintf(name, "none\n"); |
988 | |
989 | elv = e->type; |
990 | |
991 | spin_lock(&elv_list_lock); |
992 | list_for_each_entry(__e, &elv_list, list) { |
993 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
994 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
995 | else |
996 | len += sprintf(name+len, "%s ", __e->elevator_name); |
997 | } |
998 | spin_unlock(&elv_list_lock); |
999 | |
1000 | len += sprintf(len+name, "\n"); |
1001 | return len; |
1002 | } |
1003 | |
1004 | struct request *elv_rb_former_request(struct request_queue *q, |
1005 | struct request *rq) |
1006 | { |
1007 | struct rb_node *rbprev = rb_prev(&rq->rb_node); |
1008 | |
1009 | if (rbprev) |
1010 | return rb_entry_rq(rbprev); |
1011 | |
1012 | return NULL; |
1013 | } |
1014 | EXPORT_SYMBOL(elv_rb_former_request); |
1015 | |
1016 | struct request *elv_rb_latter_request(struct request_queue *q, |
1017 | struct request *rq) |
1018 | { |
1019 | struct rb_node *rbnext = rb_next(&rq->rb_node); |
1020 | |
1021 | if (rbnext) |
1022 | return rb_entry_rq(rbnext); |
1023 | |
1024 | return NULL; |
1025 | } |
1026 | EXPORT_SYMBOL(elv_rb_latter_request); |
1027 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9