Root/
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 | #include <linux/pm_runtime.h> |
38 | |
39 | #include <trace/events/block.h> |
40 | |
41 | #include "blk.h" |
42 | #include "blk-cgroup.h" |
43 | |
44 | static DEFINE_SPINLOCK(elv_list_lock); |
45 | static LIST_HEAD(elv_list); |
46 | |
47 | /* |
48 | * Merge hash stuff. |
49 | */ |
50 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
51 | |
52 | /* |
53 | * Query io scheduler to see if the current process issuing bio may be |
54 | * merged with rq. |
55 | */ |
56 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) |
57 | { |
58 | struct request_queue *q = rq->q; |
59 | struct elevator_queue *e = q->elevator; |
60 | |
61 | if (e->type->ops.elevator_allow_merge_fn) |
62 | return e->type->ops.elevator_allow_merge_fn(q, rq, bio); |
63 | |
64 | return 1; |
65 | } |
66 | |
67 | /* |
68 | * can we safely merge with this request? |
69 | */ |
70 | bool elv_rq_merge_ok(struct request *rq, struct bio *bio) |
71 | { |
72 | if (!blk_rq_merge_ok(rq, bio)) |
73 | return 0; |
74 | |
75 | if (!elv_iosched_allow_merge(rq, bio)) |
76 | return 0; |
77 | |
78 | return 1; |
79 | } |
80 | EXPORT_SYMBOL(elv_rq_merge_ok); |
81 | |
82 | static struct elevator_type *elevator_find(const char *name) |
83 | { |
84 | struct elevator_type *e; |
85 | |
86 | list_for_each_entry(e, &elv_list, list) { |
87 | if (!strcmp(e->elevator_name, name)) |
88 | return e; |
89 | } |
90 | |
91 | return NULL; |
92 | } |
93 | |
94 | static void elevator_put(struct elevator_type *e) |
95 | { |
96 | module_put(e->elevator_owner); |
97 | } |
98 | |
99 | static struct elevator_type *elevator_get(const char *name, bool try_loading) |
100 | { |
101 | struct elevator_type *e; |
102 | |
103 | spin_lock(&elv_list_lock); |
104 | |
105 | e = elevator_find(name); |
106 | if (!e && try_loading) { |
107 | spin_unlock(&elv_list_lock); |
108 | request_module("%s-iosched", name); |
109 | spin_lock(&elv_list_lock); |
110 | e = elevator_find(name); |
111 | } |
112 | |
113 | if (e && !try_module_get(e->elevator_owner)) |
114 | e = NULL; |
115 | |
116 | spin_unlock(&elv_list_lock); |
117 | |
118 | return e; |
119 | } |
120 | |
121 | static char chosen_elevator[ELV_NAME_MAX]; |
122 | |
123 | static int __init elevator_setup(char *str) |
124 | { |
125 | /* |
126 | * Be backwards-compatible with previous kernels, so users |
127 | * won't get the wrong elevator. |
128 | */ |
129 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
130 | return 1; |
131 | } |
132 | |
133 | __setup("elevator=", elevator_setup); |
134 | |
135 | /* called during boot to load the elevator chosen by the elevator param */ |
136 | void __init load_default_elevator_module(void) |
137 | { |
138 | struct elevator_type *e; |
139 | |
140 | if (!chosen_elevator[0]) |
141 | return; |
142 | |
143 | spin_lock(&elv_list_lock); |
144 | e = elevator_find(chosen_elevator); |
145 | spin_unlock(&elv_list_lock); |
146 | |
147 | if (!e) |
148 | request_module("%s-iosched", chosen_elevator); |
149 | } |
150 | |
151 | static struct kobj_type elv_ktype; |
152 | |
153 | struct elevator_queue *elevator_alloc(struct request_queue *q, |
154 | struct elevator_type *e) |
155 | { |
156 | struct elevator_queue *eq; |
157 | |
158 | eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node); |
159 | if (unlikely(!eq)) |
160 | goto err; |
161 | |
162 | eq->type = e; |
163 | kobject_init(&eq->kobj, &elv_ktype); |
164 | mutex_init(&eq->sysfs_lock); |
165 | hash_init(eq->hash); |
166 | |
167 | return eq; |
168 | err: |
169 | kfree(eq); |
170 | elevator_put(e); |
171 | return NULL; |
172 | } |
173 | EXPORT_SYMBOL(elevator_alloc); |
174 | |
175 | static void elevator_release(struct kobject *kobj) |
176 | { |
177 | struct elevator_queue *e; |
178 | |
179 | e = container_of(kobj, struct elevator_queue, kobj); |
180 | elevator_put(e->type); |
181 | kfree(e); |
182 | } |
183 | |
184 | int elevator_init(struct request_queue *q, char *name) |
185 | { |
186 | struct elevator_type *e = NULL; |
187 | int err; |
188 | |
189 | /* |
190 | * q->sysfs_lock must be held to provide mutual exclusion between |
191 | * elevator_switch() and here. |
192 | */ |
193 | lockdep_assert_held(&q->sysfs_lock); |
194 | |
195 | if (unlikely(q->elevator)) |
196 | return 0; |
197 | |
198 | INIT_LIST_HEAD(&q->queue_head); |
199 | q->last_merge = NULL; |
200 | q->end_sector = 0; |
201 | q->boundary_rq = NULL; |
202 | |
203 | if (name) { |
204 | e = elevator_get(name, true); |
205 | if (!e) |
206 | return -EINVAL; |
207 | } |
208 | |
209 | /* |
210 | * Use the default elevator specified by config boot param or |
211 | * config option. Don't try to load modules as we could be running |
212 | * off async and request_module() isn't allowed from async. |
213 | */ |
214 | if (!e && *chosen_elevator) { |
215 | e = elevator_get(chosen_elevator, false); |
216 | if (!e) |
217 | printk(KERN_ERR "I/O scheduler %s not found\n", |
218 | chosen_elevator); |
219 | } |
220 | |
221 | if (!e) { |
222 | e = elevator_get(CONFIG_DEFAULT_IOSCHED, false); |
223 | if (!e) { |
224 | printk(KERN_ERR |
225 | "Default I/O scheduler not found. " \ |
226 | "Using noop.\n"); |
227 | e = elevator_get("noop", false); |
228 | } |
229 | } |
230 | |
231 | err = e->ops.elevator_init_fn(q, e); |
232 | return 0; |
233 | } |
234 | EXPORT_SYMBOL(elevator_init); |
235 | |
236 | void elevator_exit(struct elevator_queue *e) |
237 | { |
238 | mutex_lock(&e->sysfs_lock); |
239 | if (e->type->ops.elevator_exit_fn) |
240 | e->type->ops.elevator_exit_fn(e); |
241 | mutex_unlock(&e->sysfs_lock); |
242 | |
243 | kobject_put(&e->kobj); |
244 | } |
245 | EXPORT_SYMBOL(elevator_exit); |
246 | |
247 | static inline void __elv_rqhash_del(struct request *rq) |
248 | { |
249 | hash_del(&rq->hash); |
250 | rq->cmd_flags &= ~REQ_HASHED; |
251 | } |
252 | |
253 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
254 | { |
255 | if (ELV_ON_HASH(rq)) |
256 | __elv_rqhash_del(rq); |
257 | } |
258 | |
259 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
260 | { |
261 | struct elevator_queue *e = q->elevator; |
262 | |
263 | BUG_ON(ELV_ON_HASH(rq)); |
264 | hash_add(e->hash, &rq->hash, rq_hash_key(rq)); |
265 | rq->cmd_flags |= REQ_HASHED; |
266 | } |
267 | |
268 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
269 | { |
270 | __elv_rqhash_del(rq); |
271 | elv_rqhash_add(q, rq); |
272 | } |
273 | |
274 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
275 | { |
276 | struct elevator_queue *e = q->elevator; |
277 | struct hlist_node *next; |
278 | struct request *rq; |
279 | |
280 | hash_for_each_possible_safe(e->hash, rq, next, hash, offset) { |
281 | BUG_ON(!ELV_ON_HASH(rq)); |
282 | |
283 | if (unlikely(!rq_mergeable(rq))) { |
284 | __elv_rqhash_del(rq); |
285 | continue; |
286 | } |
287 | |
288 | if (rq_hash_key(rq) == offset) |
289 | return rq; |
290 | } |
291 | |
292 | return NULL; |
293 | } |
294 | |
295 | /* |
296 | * RB-tree support functions for inserting/lookup/removal of requests |
297 | * in a sorted RB tree. |
298 | */ |
299 | void elv_rb_add(struct rb_root *root, struct request *rq) |
300 | { |
301 | struct rb_node **p = &root->rb_node; |
302 | struct rb_node *parent = NULL; |
303 | struct request *__rq; |
304 | |
305 | while (*p) { |
306 | parent = *p; |
307 | __rq = rb_entry(parent, struct request, rb_node); |
308 | |
309 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
310 | p = &(*p)->rb_left; |
311 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
312 | p = &(*p)->rb_right; |
313 | } |
314 | |
315 | rb_link_node(&rq->rb_node, parent, p); |
316 | rb_insert_color(&rq->rb_node, root); |
317 | } |
318 | EXPORT_SYMBOL(elv_rb_add); |
319 | |
320 | void elv_rb_del(struct rb_root *root, struct request *rq) |
321 | { |
322 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); |
323 | rb_erase(&rq->rb_node, root); |
324 | RB_CLEAR_NODE(&rq->rb_node); |
325 | } |
326 | EXPORT_SYMBOL(elv_rb_del); |
327 | |
328 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) |
329 | { |
330 | struct rb_node *n = root->rb_node; |
331 | struct request *rq; |
332 | |
333 | while (n) { |
334 | rq = rb_entry(n, struct request, rb_node); |
335 | |
336 | if (sector < blk_rq_pos(rq)) |
337 | n = n->rb_left; |
338 | else if (sector > blk_rq_pos(rq)) |
339 | n = n->rb_right; |
340 | else |
341 | return rq; |
342 | } |
343 | |
344 | return NULL; |
345 | } |
346 | EXPORT_SYMBOL(elv_rb_find); |
347 | |
348 | /* |
349 | * Insert rq into dispatch queue of q. Queue lock must be held on |
350 | * entry. rq is sort instead into the dispatch queue. To be used by |
351 | * specific elevators. |
352 | */ |
353 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
354 | { |
355 | sector_t boundary; |
356 | struct list_head *entry; |
357 | int stop_flags; |
358 | |
359 | if (q->last_merge == rq) |
360 | q->last_merge = NULL; |
361 | |
362 | elv_rqhash_del(q, rq); |
363 | |
364 | q->nr_sorted--; |
365 | |
366 | boundary = q->end_sector; |
367 | stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
368 | list_for_each_prev(entry, &q->queue_head) { |
369 | struct request *pos = list_entry_rq(entry); |
370 | |
371 | if ((rq->cmd_flags & REQ_DISCARD) != |
372 | (pos->cmd_flags & REQ_DISCARD)) |
373 | break; |
374 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
375 | break; |
376 | if (pos->cmd_flags & stop_flags) |
377 | break; |
378 | if (blk_rq_pos(rq) >= boundary) { |
379 | if (blk_rq_pos(pos) < boundary) |
380 | continue; |
381 | } else { |
382 | if (blk_rq_pos(pos) >= boundary) |
383 | break; |
384 | } |
385 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
386 | break; |
387 | } |
388 | |
389 | list_add(&rq->queuelist, entry); |
390 | } |
391 | EXPORT_SYMBOL(elv_dispatch_sort); |
392 | |
393 | /* |
394 | * Insert rq into dispatch queue of q. Queue lock must be held on |
395 | * entry. rq is added to the back of the dispatch queue. To be used by |
396 | * specific elevators. |
397 | */ |
398 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) |
399 | { |
400 | if (q->last_merge == rq) |
401 | q->last_merge = NULL; |
402 | |
403 | elv_rqhash_del(q, rq); |
404 | |
405 | q->nr_sorted--; |
406 | |
407 | q->end_sector = rq_end_sector(rq); |
408 | q->boundary_rq = rq; |
409 | list_add_tail(&rq->queuelist, &q->queue_head); |
410 | } |
411 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
412 | |
413 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
414 | { |
415 | struct elevator_queue *e = q->elevator; |
416 | struct request *__rq; |
417 | int ret; |
418 | |
419 | /* |
420 | * Levels of merges: |
421 | * nomerges: No merges at all attempted |
422 | * noxmerges: Only simple one-hit cache try |
423 | * merges: All merge tries attempted |
424 | */ |
425 | if (blk_queue_nomerges(q)) |
426 | return ELEVATOR_NO_MERGE; |
427 | |
428 | /* |
429 | * First try one-hit cache. |
430 | */ |
431 | if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { |
432 | ret = blk_try_merge(q->last_merge, bio); |
433 | if (ret != ELEVATOR_NO_MERGE) { |
434 | *req = q->last_merge; |
435 | return ret; |
436 | } |
437 | } |
438 | |
439 | if (blk_queue_noxmerges(q)) |
440 | return ELEVATOR_NO_MERGE; |
441 | |
442 | /* |
443 | * See if our hash lookup can find a potential backmerge. |
444 | */ |
445 | __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); |
446 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
447 | *req = __rq; |
448 | return ELEVATOR_BACK_MERGE; |
449 | } |
450 | |
451 | if (e->type->ops.elevator_merge_fn) |
452 | return e->type->ops.elevator_merge_fn(q, req, bio); |
453 | |
454 | return ELEVATOR_NO_MERGE; |
455 | } |
456 | |
457 | /* |
458 | * Attempt to do an insertion back merge. Only check for the case where |
459 | * we can append 'rq' to an existing request, so we can throw 'rq' away |
460 | * afterwards. |
461 | * |
462 | * Returns true if we merged, false otherwise |
463 | */ |
464 | static bool elv_attempt_insert_merge(struct request_queue *q, |
465 | struct request *rq) |
466 | { |
467 | struct request *__rq; |
468 | bool ret; |
469 | |
470 | if (blk_queue_nomerges(q)) |
471 | return false; |
472 | |
473 | /* |
474 | * First try one-hit cache. |
475 | */ |
476 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) |
477 | return true; |
478 | |
479 | if (blk_queue_noxmerges(q)) |
480 | return false; |
481 | |
482 | ret = false; |
483 | /* |
484 | * See if our hash lookup can find a potential backmerge. |
485 | */ |
486 | while (1) { |
487 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); |
488 | if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) |
489 | break; |
490 | |
491 | /* The merged request could be merged with others, try again */ |
492 | ret = true; |
493 | rq = __rq; |
494 | } |
495 | |
496 | return ret; |
497 | } |
498 | |
499 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
500 | { |
501 | struct elevator_queue *e = q->elevator; |
502 | |
503 | if (e->type->ops.elevator_merged_fn) |
504 | e->type->ops.elevator_merged_fn(q, rq, type); |
505 | |
506 | if (type == ELEVATOR_BACK_MERGE) |
507 | elv_rqhash_reposition(q, rq); |
508 | |
509 | q->last_merge = rq; |
510 | } |
511 | |
512 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
513 | struct request *next) |
514 | { |
515 | struct elevator_queue *e = q->elevator; |
516 | const int next_sorted = next->cmd_flags & REQ_SORTED; |
517 | |
518 | if (next_sorted && e->type->ops.elevator_merge_req_fn) |
519 | e->type->ops.elevator_merge_req_fn(q, rq, next); |
520 | |
521 | elv_rqhash_reposition(q, rq); |
522 | |
523 | if (next_sorted) { |
524 | elv_rqhash_del(q, next); |
525 | q->nr_sorted--; |
526 | } |
527 | |
528 | q->last_merge = rq; |
529 | } |
530 | |
531 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
532 | struct bio *bio) |
533 | { |
534 | struct elevator_queue *e = q->elevator; |
535 | |
536 | if (e->type->ops.elevator_bio_merged_fn) |
537 | e->type->ops.elevator_bio_merged_fn(q, rq, bio); |
538 | } |
539 | |
540 | #ifdef CONFIG_PM_RUNTIME |
541 | static void blk_pm_requeue_request(struct request *rq) |
542 | { |
543 | if (rq->q->dev && !(rq->cmd_flags & REQ_PM)) |
544 | rq->q->nr_pending--; |
545 | } |
546 | |
547 | static void blk_pm_add_request(struct request_queue *q, struct request *rq) |
548 | { |
549 | if (q->dev && !(rq->cmd_flags & REQ_PM) && q->nr_pending++ == 0 && |
550 | (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING)) |
551 | pm_request_resume(q->dev); |
552 | } |
553 | #else |
554 | static inline void blk_pm_requeue_request(struct request *rq) {} |
555 | static inline void blk_pm_add_request(struct request_queue *q, |
556 | struct request *rq) |
557 | { |
558 | } |
559 | #endif |
560 | |
561 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
562 | { |
563 | /* |
564 | * it already went through dequeue, we need to decrement the |
565 | * in_flight count again |
566 | */ |
567 | if (blk_account_rq(rq)) { |
568 | q->in_flight[rq_is_sync(rq)]--; |
569 | if (rq->cmd_flags & REQ_SORTED) |
570 | elv_deactivate_rq(q, rq); |
571 | } |
572 | |
573 | rq->cmd_flags &= ~REQ_STARTED; |
574 | |
575 | blk_pm_requeue_request(rq); |
576 | |
577 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
578 | } |
579 | |
580 | void elv_drain_elevator(struct request_queue *q) |
581 | { |
582 | static int printed; |
583 | |
584 | lockdep_assert_held(q->queue_lock); |
585 | |
586 | while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
587 | ; |
588 | if (q->nr_sorted && printed++ < 10) { |
589 | printk(KERN_ERR "%s: forced dispatching is broken " |
590 | "(nr_sorted=%u), please report this\n", |
591 | q->elevator->type->elevator_name, q->nr_sorted); |
592 | } |
593 | } |
594 | |
595 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
596 | { |
597 | trace_block_rq_insert(q, rq); |
598 | |
599 | blk_pm_add_request(q, rq); |
600 | |
601 | rq->q = q; |
602 | |
603 | if (rq->cmd_flags & REQ_SOFTBARRIER) { |
604 | /* barriers are scheduling boundary, update end_sector */ |
605 | if (rq->cmd_type == REQ_TYPE_FS) { |
606 | q->end_sector = rq_end_sector(rq); |
607 | q->boundary_rq = rq; |
608 | } |
609 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
610 | (where == ELEVATOR_INSERT_SORT || |
611 | where == ELEVATOR_INSERT_SORT_MERGE)) |
612 | where = ELEVATOR_INSERT_BACK; |
613 | |
614 | switch (where) { |
615 | case ELEVATOR_INSERT_REQUEUE: |
616 | case ELEVATOR_INSERT_FRONT: |
617 | rq->cmd_flags |= REQ_SOFTBARRIER; |
618 | list_add(&rq->queuelist, &q->queue_head); |
619 | break; |
620 | |
621 | case ELEVATOR_INSERT_BACK: |
622 | rq->cmd_flags |= REQ_SOFTBARRIER; |
623 | elv_drain_elevator(q); |
624 | list_add_tail(&rq->queuelist, &q->queue_head); |
625 | /* |
626 | * We kick the queue here for the following reasons. |
627 | * - The elevator might have returned NULL previously |
628 | * to delay requests and returned them now. As the |
629 | * queue wasn't empty before this request, ll_rw_blk |
630 | * won't run the queue on return, resulting in hang. |
631 | * - Usually, back inserted requests won't be merged |
632 | * with anything. There's no point in delaying queue |
633 | * processing. |
634 | */ |
635 | __blk_run_queue(q); |
636 | break; |
637 | |
638 | case ELEVATOR_INSERT_SORT_MERGE: |
639 | /* |
640 | * If we succeed in merging this request with one in the |
641 | * queue already, we are done - rq has now been freed, |
642 | * so no need to do anything further. |
643 | */ |
644 | if (elv_attempt_insert_merge(q, rq)) |
645 | break; |
646 | case ELEVATOR_INSERT_SORT: |
647 | BUG_ON(rq->cmd_type != REQ_TYPE_FS); |
648 | rq->cmd_flags |= REQ_SORTED; |
649 | q->nr_sorted++; |
650 | if (rq_mergeable(rq)) { |
651 | elv_rqhash_add(q, rq); |
652 | if (!q->last_merge) |
653 | q->last_merge = rq; |
654 | } |
655 | |
656 | /* |
657 | * Some ioscheds (cfq) run q->request_fn directly, so |
658 | * rq cannot be accessed after calling |
659 | * elevator_add_req_fn. |
660 | */ |
661 | q->elevator->type->ops.elevator_add_req_fn(q, rq); |
662 | break; |
663 | |
664 | case ELEVATOR_INSERT_FLUSH: |
665 | rq->cmd_flags |= REQ_SOFTBARRIER; |
666 | blk_insert_flush(rq); |
667 | break; |
668 | default: |
669 | printk(KERN_ERR "%s: bad insertion point %d\n", |
670 | __func__, where); |
671 | BUG(); |
672 | } |
673 | } |
674 | EXPORT_SYMBOL(__elv_add_request); |
675 | |
676 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
677 | { |
678 | unsigned long flags; |
679 | |
680 | spin_lock_irqsave(q->queue_lock, flags); |
681 | __elv_add_request(q, rq, where); |
682 | spin_unlock_irqrestore(q->queue_lock, flags); |
683 | } |
684 | EXPORT_SYMBOL(elv_add_request); |
685 | |
686 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
687 | { |
688 | struct elevator_queue *e = q->elevator; |
689 | |
690 | if (e->type->ops.elevator_latter_req_fn) |
691 | return e->type->ops.elevator_latter_req_fn(q, rq); |
692 | return NULL; |
693 | } |
694 | |
695 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
696 | { |
697 | struct elevator_queue *e = q->elevator; |
698 | |
699 | if (e->type->ops.elevator_former_req_fn) |
700 | return e->type->ops.elevator_former_req_fn(q, rq); |
701 | return NULL; |
702 | } |
703 | |
704 | int elv_set_request(struct request_queue *q, struct request *rq, |
705 | struct bio *bio, gfp_t gfp_mask) |
706 | { |
707 | struct elevator_queue *e = q->elevator; |
708 | |
709 | if (e->type->ops.elevator_set_req_fn) |
710 | return e->type->ops.elevator_set_req_fn(q, rq, bio, gfp_mask); |
711 | return 0; |
712 | } |
713 | |
714 | void elv_put_request(struct request_queue *q, struct request *rq) |
715 | { |
716 | struct elevator_queue *e = q->elevator; |
717 | |
718 | if (e->type->ops.elevator_put_req_fn) |
719 | e->type->ops.elevator_put_req_fn(rq); |
720 | } |
721 | |
722 | int elv_may_queue(struct request_queue *q, int rw) |
723 | { |
724 | struct elevator_queue *e = q->elevator; |
725 | |
726 | if (e->type->ops.elevator_may_queue_fn) |
727 | return e->type->ops.elevator_may_queue_fn(q, rw); |
728 | |
729 | return ELV_MQUEUE_MAY; |
730 | } |
731 | |
732 | void elv_abort_queue(struct request_queue *q) |
733 | { |
734 | struct request *rq; |
735 | |
736 | blk_abort_flushes(q); |
737 | |
738 | while (!list_empty(&q->queue_head)) { |
739 | rq = list_entry_rq(q->queue_head.next); |
740 | rq->cmd_flags |= REQ_QUIET; |
741 | trace_block_rq_abort(q, rq); |
742 | /* |
743 | * Mark this request as started so we don't trigger |
744 | * any debug logic in the end I/O path. |
745 | */ |
746 | blk_start_request(rq); |
747 | __blk_end_request_all(rq, -EIO); |
748 | } |
749 | } |
750 | EXPORT_SYMBOL(elv_abort_queue); |
751 | |
752 | void elv_completed_request(struct request_queue *q, struct request *rq) |
753 | { |
754 | struct elevator_queue *e = q->elevator; |
755 | |
756 | /* |
757 | * request is released from the driver, io must be done |
758 | */ |
759 | if (blk_account_rq(rq)) { |
760 | q->in_flight[rq_is_sync(rq)]--; |
761 | if ((rq->cmd_flags & REQ_SORTED) && |
762 | e->type->ops.elevator_completed_req_fn) |
763 | e->type->ops.elevator_completed_req_fn(q, rq); |
764 | } |
765 | } |
766 | |
767 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
768 | |
769 | static ssize_t |
770 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) |
771 | { |
772 | struct elv_fs_entry *entry = to_elv(attr); |
773 | struct elevator_queue *e; |
774 | ssize_t error; |
775 | |
776 | if (!entry->show) |
777 | return -EIO; |
778 | |
779 | e = container_of(kobj, struct elevator_queue, kobj); |
780 | mutex_lock(&e->sysfs_lock); |
781 | error = e->type ? entry->show(e, page) : -ENOENT; |
782 | mutex_unlock(&e->sysfs_lock); |
783 | return error; |
784 | } |
785 | |
786 | static ssize_t |
787 | elv_attr_store(struct kobject *kobj, struct attribute *attr, |
788 | const char *page, size_t length) |
789 | { |
790 | struct elv_fs_entry *entry = to_elv(attr); |
791 | struct elevator_queue *e; |
792 | ssize_t error; |
793 | |
794 | if (!entry->store) |
795 | return -EIO; |
796 | |
797 | e = container_of(kobj, struct elevator_queue, kobj); |
798 | mutex_lock(&e->sysfs_lock); |
799 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
800 | mutex_unlock(&e->sysfs_lock); |
801 | return error; |
802 | } |
803 | |
804 | static const struct sysfs_ops elv_sysfs_ops = { |
805 | .show = elv_attr_show, |
806 | .store = elv_attr_store, |
807 | }; |
808 | |
809 | static struct kobj_type elv_ktype = { |
810 | .sysfs_ops = &elv_sysfs_ops, |
811 | .release = elevator_release, |
812 | }; |
813 | |
814 | int elv_register_queue(struct request_queue *q) |
815 | { |
816 | struct elevator_queue *e = q->elevator; |
817 | int error; |
818 | |
819 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
820 | if (!error) { |
821 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
822 | if (attr) { |
823 | while (attr->attr.name) { |
824 | if (sysfs_create_file(&e->kobj, &attr->attr)) |
825 | break; |
826 | attr++; |
827 | } |
828 | } |
829 | kobject_uevent(&e->kobj, KOBJ_ADD); |
830 | e->registered = 1; |
831 | } |
832 | return error; |
833 | } |
834 | EXPORT_SYMBOL(elv_register_queue); |
835 | |
836 | void elv_unregister_queue(struct request_queue *q) |
837 | { |
838 | if (q) { |
839 | struct elevator_queue *e = q->elevator; |
840 | |
841 | kobject_uevent(&e->kobj, KOBJ_REMOVE); |
842 | kobject_del(&e->kobj); |
843 | e->registered = 0; |
844 | } |
845 | } |
846 | EXPORT_SYMBOL(elv_unregister_queue); |
847 | |
848 | int elv_register(struct elevator_type *e) |
849 | { |
850 | char *def = ""; |
851 | |
852 | /* create icq_cache if requested */ |
853 | if (e->icq_size) { |
854 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || |
855 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) |
856 | return -EINVAL; |
857 | |
858 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), |
859 | "%s_io_cq", e->elevator_name); |
860 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, |
861 | e->icq_align, 0, NULL); |
862 | if (!e->icq_cache) |
863 | return -ENOMEM; |
864 | } |
865 | |
866 | /* register, don't allow duplicate names */ |
867 | spin_lock(&elv_list_lock); |
868 | if (elevator_find(e->elevator_name)) { |
869 | spin_unlock(&elv_list_lock); |
870 | if (e->icq_cache) |
871 | kmem_cache_destroy(e->icq_cache); |
872 | return -EBUSY; |
873 | } |
874 | list_add_tail(&e->list, &elv_list); |
875 | spin_unlock(&elv_list_lock); |
876 | |
877 | /* print pretty message */ |
878 | if (!strcmp(e->elevator_name, chosen_elevator) || |
879 | (!*chosen_elevator && |
880 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) |
881 | def = " (default)"; |
882 | |
883 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
884 | def); |
885 | return 0; |
886 | } |
887 | EXPORT_SYMBOL_GPL(elv_register); |
888 | |
889 | void elv_unregister(struct elevator_type *e) |
890 | { |
891 | /* unregister */ |
892 | spin_lock(&elv_list_lock); |
893 | list_del_init(&e->list); |
894 | spin_unlock(&elv_list_lock); |
895 | |
896 | /* |
897 | * Destroy icq_cache if it exists. icq's are RCU managed. Make |
898 | * sure all RCU operations are complete before proceeding. |
899 | */ |
900 | if (e->icq_cache) { |
901 | rcu_barrier(); |
902 | kmem_cache_destroy(e->icq_cache); |
903 | e->icq_cache = NULL; |
904 | } |
905 | } |
906 | EXPORT_SYMBOL_GPL(elv_unregister); |
907 | |
908 | /* |
909 | * switch to new_e io scheduler. be careful not to introduce deadlocks - |
910 | * we don't free the old io scheduler, before we have allocated what we |
911 | * need for the new one. this way we have a chance of going back to the old |
912 | * one, if the new one fails init for some reason. |
913 | */ |
914 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
915 | { |
916 | struct elevator_queue *old = q->elevator; |
917 | bool registered = old->registered; |
918 | int err; |
919 | |
920 | /* |
921 | * Turn on BYPASS and drain all requests w/ elevator private data. |
922 | * Block layer doesn't call into a quiesced elevator - all requests |
923 | * are directly put on the dispatch list without elevator data |
924 | * using INSERT_BACK. All requests have SOFTBARRIER set and no |
925 | * merge happens either. |
926 | */ |
927 | blk_queue_bypass_start(q); |
928 | |
929 | /* unregister and clear all auxiliary data of the old elevator */ |
930 | if (registered) |
931 | elv_unregister_queue(q); |
932 | |
933 | spin_lock_irq(q->queue_lock); |
934 | ioc_clear_queue(q); |
935 | spin_unlock_irq(q->queue_lock); |
936 | |
937 | /* allocate, init and register new elevator */ |
938 | err = new_e->ops.elevator_init_fn(q, new_e); |
939 | if (err) |
940 | goto fail_init; |
941 | |
942 | if (registered) { |
943 | err = elv_register_queue(q); |
944 | if (err) |
945 | goto fail_register; |
946 | } |
947 | |
948 | /* done, kill the old one and finish */ |
949 | elevator_exit(old); |
950 | blk_queue_bypass_end(q); |
951 | |
952 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
953 | |
954 | return 0; |
955 | |
956 | fail_register: |
957 | elevator_exit(q->elevator); |
958 | fail_init: |
959 | /* switch failed, restore and re-register old elevator */ |
960 | q->elevator = old; |
961 | elv_register_queue(q); |
962 | blk_queue_bypass_end(q); |
963 | |
964 | return err; |
965 | } |
966 | |
967 | /* |
968 | * Switch this queue to the given IO scheduler. |
969 | */ |
970 | static int __elevator_change(struct request_queue *q, const char *name) |
971 | { |
972 | char elevator_name[ELV_NAME_MAX]; |
973 | struct elevator_type *e; |
974 | |
975 | if (!q->elevator) |
976 | return -ENXIO; |
977 | |
978 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
979 | e = elevator_get(strstrip(elevator_name), true); |
980 | if (!e) { |
981 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); |
982 | return -EINVAL; |
983 | } |
984 | |
985 | if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
986 | elevator_put(e); |
987 | return 0; |
988 | } |
989 | |
990 | return elevator_switch(q, e); |
991 | } |
992 | |
993 | int elevator_change(struct request_queue *q, const char *name) |
994 | { |
995 | int ret; |
996 | |
997 | /* Protect q->elevator from elevator_init() */ |
998 | mutex_lock(&q->sysfs_lock); |
999 | ret = __elevator_change(q, name); |
1000 | mutex_unlock(&q->sysfs_lock); |
1001 | |
1002 | return ret; |
1003 | } |
1004 | EXPORT_SYMBOL(elevator_change); |
1005 | |
1006 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1007 | size_t count) |
1008 | { |
1009 | int ret; |
1010 | |
1011 | if (!q->elevator) |
1012 | return count; |
1013 | |
1014 | ret = __elevator_change(q, name); |
1015 | if (!ret) |
1016 | return count; |
1017 | |
1018 | printk(KERN_ERR "elevator: switch to %s failed\n", name); |
1019 | return ret; |
1020 | } |
1021 | |
1022 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1023 | { |
1024 | struct elevator_queue *e = q->elevator; |
1025 | struct elevator_type *elv; |
1026 | struct elevator_type *__e; |
1027 | int len = 0; |
1028 | |
1029 | if (!q->elevator || !blk_queue_stackable(q)) |
1030 | return sprintf(name, "none\n"); |
1031 | |
1032 | elv = e->type; |
1033 | |
1034 | spin_lock(&elv_list_lock); |
1035 | list_for_each_entry(__e, &elv_list, list) { |
1036 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1037 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
1038 | else |
1039 | len += sprintf(name+len, "%s ", __e->elevator_name); |
1040 | } |
1041 | spin_unlock(&elv_list_lock); |
1042 | |
1043 | len += sprintf(len+name, "\n"); |
1044 | return len; |
1045 | } |
1046 | |
1047 | struct request *elv_rb_former_request(struct request_queue *q, |
1048 | struct request *rq) |
1049 | { |
1050 | struct rb_node *rbprev = rb_prev(&rq->rb_node); |
1051 | |
1052 | if (rbprev) |
1053 | return rb_entry_rq(rbprev); |
1054 | |
1055 | return NULL; |
1056 | } |
1057 | EXPORT_SYMBOL(elv_rb_former_request); |
1058 | |
1059 | struct request *elv_rb_latter_request(struct request_queue *q, |
1060 | struct request *rq) |
1061 | { |
1062 | struct rb_node *rbnext = rb_next(&rq->rb_node); |
1063 | |
1064 | if (rbnext) |
1065 | return rb_entry_rq(rbnext); |
1066 | |
1067 | return NULL; |
1068 | } |
1069 | EXPORT_SYMBOL(elv_rb_latter_request); |
1070 |
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