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/delay.h> |
35 | #include <linux/blktrace_api.h> |
36 | #include <linux/hash.h> |
37 | #include <linux/uaccess.h> |
38 | |
39 | #include <trace/events/block.h> |
40 | |
41 | #include "blk.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->ops->elevator_allow_merge_fn) |
66 | return e->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 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
75 | { |
76 | if (!rq_mergeable(rq)) |
77 | return 0; |
78 | |
79 | /* |
80 | * Don't merge file system requests and discard requests |
81 | */ |
82 | if (bio_discard(bio) != bio_discard(rq->bio)) |
83 | return 0; |
84 | |
85 | /* |
86 | * different data direction or already started, don't merge |
87 | */ |
88 | if (bio_data_dir(bio) != rq_data_dir(rq)) |
89 | return 0; |
90 | |
91 | /* |
92 | * must be same device and not a special request |
93 | */ |
94 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
95 | return 0; |
96 | |
97 | /* |
98 | * only merge integrity protected bio into ditto rq |
99 | */ |
100 | if (bio_integrity(bio) != blk_integrity_rq(rq)) |
101 | return 0; |
102 | |
103 | /* |
104 | * Don't merge if failfast settings don't match. |
105 | * |
106 | * FIXME: The negation in front of each condition is necessary |
107 | * because bio and request flags use different bit positions |
108 | * and the accessors return those bits directly. This |
109 | * ugliness will soon go away. |
110 | */ |
111 | if (!bio_failfast_dev(bio) != !blk_failfast_dev(rq) || |
112 | !bio_failfast_transport(bio) != !blk_failfast_transport(rq) || |
113 | !bio_failfast_driver(bio) != !blk_failfast_driver(rq)) |
114 | return 0; |
115 | |
116 | if (!elv_iosched_allow_merge(rq, bio)) |
117 | return 0; |
118 | |
119 | return 1; |
120 | } |
121 | EXPORT_SYMBOL(elv_rq_merge_ok); |
122 | |
123 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
124 | { |
125 | int ret = ELEVATOR_NO_MERGE; |
126 | |
127 | /* |
128 | * we can merge and sequence is ok, check if it's possible |
129 | */ |
130 | if (elv_rq_merge_ok(__rq, bio)) { |
131 | if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
132 | ret = ELEVATOR_BACK_MERGE; |
133 | else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
134 | ret = ELEVATOR_FRONT_MERGE; |
135 | } |
136 | |
137 | return ret; |
138 | } |
139 | |
140 | static struct elevator_type *elevator_find(const char *name) |
141 | { |
142 | struct elevator_type *e; |
143 | |
144 | list_for_each_entry(e, &elv_list, list) { |
145 | if (!strcmp(e->elevator_name, name)) |
146 | return e; |
147 | } |
148 | |
149 | return NULL; |
150 | } |
151 | |
152 | static void elevator_put(struct elevator_type *e) |
153 | { |
154 | module_put(e->elevator_owner); |
155 | } |
156 | |
157 | static struct elevator_type *elevator_get(const char *name) |
158 | { |
159 | struct elevator_type *e; |
160 | |
161 | spin_lock(&elv_list_lock); |
162 | |
163 | e = elevator_find(name); |
164 | if (!e) { |
165 | char elv[ELV_NAME_MAX + strlen("-iosched")]; |
166 | |
167 | spin_unlock(&elv_list_lock); |
168 | |
169 | if (!strcmp(name, "anticipatory")) |
170 | sprintf(elv, "as-iosched"); |
171 | else |
172 | sprintf(elv, "%s-iosched", name); |
173 | |
174 | request_module("%s", elv); |
175 | spin_lock(&elv_list_lock); |
176 | e = elevator_find(name); |
177 | } |
178 | |
179 | if (e && !try_module_get(e->elevator_owner)) |
180 | e = NULL; |
181 | |
182 | spin_unlock(&elv_list_lock); |
183 | |
184 | return e; |
185 | } |
186 | |
187 | static void *elevator_init_queue(struct request_queue *q, |
188 | struct elevator_queue *eq) |
189 | { |
190 | return eq->ops->elevator_init_fn(q); |
191 | } |
192 | |
193 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
194 | void *data) |
195 | { |
196 | q->elevator = eq; |
197 | eq->elevator_data = data; |
198 | } |
199 | |
200 | static char chosen_elevator[16]; |
201 | |
202 | static int __init elevator_setup(char *str) |
203 | { |
204 | /* |
205 | * Be backwards-compatible with previous kernels, so users |
206 | * won't get the wrong elevator. |
207 | */ |
208 | if (!strcmp(str, "as")) |
209 | strcpy(chosen_elevator, "anticipatory"); |
210 | else |
211 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
212 | return 1; |
213 | } |
214 | |
215 | __setup("elevator=", elevator_setup); |
216 | |
217 | static struct kobj_type elv_ktype; |
218 | |
219 | static struct elevator_queue *elevator_alloc(struct request_queue *q, |
220 | struct elevator_type *e) |
221 | { |
222 | struct elevator_queue *eq; |
223 | int i; |
224 | |
225 | eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
226 | if (unlikely(!eq)) |
227 | goto err; |
228 | |
229 | eq->ops = &e->ops; |
230 | eq->elevator_type = e; |
231 | kobject_init(&eq->kobj, &elv_ktype); |
232 | mutex_init(&eq->sysfs_lock); |
233 | |
234 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
235 | GFP_KERNEL, q->node); |
236 | if (!eq->hash) |
237 | goto err; |
238 | |
239 | for (i = 0; i < ELV_HASH_ENTRIES; i++) |
240 | INIT_HLIST_HEAD(&eq->hash[i]); |
241 | |
242 | return eq; |
243 | err: |
244 | kfree(eq); |
245 | elevator_put(e); |
246 | return NULL; |
247 | } |
248 | |
249 | static void elevator_release(struct kobject *kobj) |
250 | { |
251 | struct elevator_queue *e; |
252 | |
253 | e = container_of(kobj, struct elevator_queue, kobj); |
254 | elevator_put(e->elevator_type); |
255 | kfree(e->hash); |
256 | kfree(e); |
257 | } |
258 | |
259 | int elevator_init(struct request_queue *q, char *name) |
260 | { |
261 | struct elevator_type *e = NULL; |
262 | struct elevator_queue *eq; |
263 | int ret = 0; |
264 | void *data; |
265 | |
266 | INIT_LIST_HEAD(&q->queue_head); |
267 | q->last_merge = NULL; |
268 | q->end_sector = 0; |
269 | q->boundary_rq = NULL; |
270 | |
271 | if (name) { |
272 | e = elevator_get(name); |
273 | if (!e) |
274 | return -EINVAL; |
275 | } |
276 | |
277 | if (!e && *chosen_elevator) { |
278 | e = elevator_get(chosen_elevator); |
279 | if (!e) |
280 | printk(KERN_ERR "I/O scheduler %s not found\n", |
281 | chosen_elevator); |
282 | } |
283 | |
284 | if (!e) { |
285 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); |
286 | if (!e) { |
287 | printk(KERN_ERR |
288 | "Default I/O scheduler not found. " \ |
289 | "Using noop.\n"); |
290 | e = elevator_get("noop"); |
291 | } |
292 | } |
293 | |
294 | eq = elevator_alloc(q, e); |
295 | if (!eq) |
296 | return -ENOMEM; |
297 | |
298 | data = elevator_init_queue(q, eq); |
299 | if (!data) { |
300 | kobject_put(&eq->kobj); |
301 | return -ENOMEM; |
302 | } |
303 | |
304 | elevator_attach(q, eq, data); |
305 | return ret; |
306 | } |
307 | EXPORT_SYMBOL(elevator_init); |
308 | |
309 | void elevator_exit(struct elevator_queue *e) |
310 | { |
311 | mutex_lock(&e->sysfs_lock); |
312 | if (e->ops->elevator_exit_fn) |
313 | e->ops->elevator_exit_fn(e); |
314 | e->ops = NULL; |
315 | mutex_unlock(&e->sysfs_lock); |
316 | |
317 | kobject_put(&e->kobj); |
318 | } |
319 | EXPORT_SYMBOL(elevator_exit); |
320 | |
321 | static inline void __elv_rqhash_del(struct request *rq) |
322 | { |
323 | hlist_del_init(&rq->hash); |
324 | } |
325 | |
326 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
327 | { |
328 | if (ELV_ON_HASH(rq)) |
329 | __elv_rqhash_del(rq); |
330 | } |
331 | |
332 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
333 | { |
334 | struct elevator_queue *e = q->elevator; |
335 | |
336 | BUG_ON(ELV_ON_HASH(rq)); |
337 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); |
338 | } |
339 | |
340 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
341 | { |
342 | __elv_rqhash_del(rq); |
343 | elv_rqhash_add(q, rq); |
344 | } |
345 | |
346 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
347 | { |
348 | struct elevator_queue *e = q->elevator; |
349 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
350 | struct hlist_node *entry, *next; |
351 | struct request *rq; |
352 | |
353 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { |
354 | BUG_ON(!ELV_ON_HASH(rq)); |
355 | |
356 | if (unlikely(!rq_mergeable(rq))) { |
357 | __elv_rqhash_del(rq); |
358 | continue; |
359 | } |
360 | |
361 | if (rq_hash_key(rq) == offset) |
362 | return rq; |
363 | } |
364 | |
365 | return NULL; |
366 | } |
367 | |
368 | /* |
369 | * RB-tree support functions for inserting/lookup/removal of requests |
370 | * in a sorted RB tree. |
371 | */ |
372 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) |
373 | { |
374 | struct rb_node **p = &root->rb_node; |
375 | struct rb_node *parent = NULL; |
376 | struct request *__rq; |
377 | |
378 | while (*p) { |
379 | parent = *p; |
380 | __rq = rb_entry(parent, struct request, rb_node); |
381 | |
382 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
383 | p = &(*p)->rb_left; |
384 | else if (blk_rq_pos(rq) > blk_rq_pos(__rq)) |
385 | p = &(*p)->rb_right; |
386 | else |
387 | return __rq; |
388 | } |
389 | |
390 | rb_link_node(&rq->rb_node, parent, p); |
391 | rb_insert_color(&rq->rb_node, root); |
392 | return NULL; |
393 | } |
394 | EXPORT_SYMBOL(elv_rb_add); |
395 | |
396 | void elv_rb_del(struct rb_root *root, struct request *rq) |
397 | { |
398 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); |
399 | rb_erase(&rq->rb_node, root); |
400 | RB_CLEAR_NODE(&rq->rb_node); |
401 | } |
402 | EXPORT_SYMBOL(elv_rb_del); |
403 | |
404 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) |
405 | { |
406 | struct rb_node *n = root->rb_node; |
407 | struct request *rq; |
408 | |
409 | while (n) { |
410 | rq = rb_entry(n, struct request, rb_node); |
411 | |
412 | if (sector < blk_rq_pos(rq)) |
413 | n = n->rb_left; |
414 | else if (sector > blk_rq_pos(rq)) |
415 | n = n->rb_right; |
416 | else |
417 | return rq; |
418 | } |
419 | |
420 | return NULL; |
421 | } |
422 | EXPORT_SYMBOL(elv_rb_find); |
423 | |
424 | /* |
425 | * Insert rq into dispatch queue of q. Queue lock must be held on |
426 | * entry. rq is sort instead into the dispatch queue. To be used by |
427 | * specific elevators. |
428 | */ |
429 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
430 | { |
431 | sector_t boundary; |
432 | struct list_head *entry; |
433 | int stop_flags; |
434 | |
435 | if (q->last_merge == rq) |
436 | q->last_merge = NULL; |
437 | |
438 | elv_rqhash_del(q, rq); |
439 | |
440 | q->nr_sorted--; |
441 | |
442 | boundary = q->end_sector; |
443 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
444 | list_for_each_prev(entry, &q->queue_head) { |
445 | struct request *pos = list_entry_rq(entry); |
446 | |
447 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
448 | break; |
449 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
450 | break; |
451 | if (pos->cmd_flags & stop_flags) |
452 | break; |
453 | if (blk_rq_pos(rq) >= boundary) { |
454 | if (blk_rq_pos(pos) < boundary) |
455 | continue; |
456 | } else { |
457 | if (blk_rq_pos(pos) >= boundary) |
458 | break; |
459 | } |
460 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
461 | break; |
462 | } |
463 | |
464 | list_add(&rq->queuelist, entry); |
465 | } |
466 | EXPORT_SYMBOL(elv_dispatch_sort); |
467 | |
468 | /* |
469 | * Insert rq into dispatch queue of q. Queue lock must be held on |
470 | * entry. rq is added to the back of the dispatch queue. To be used by |
471 | * specific elevators. |
472 | */ |
473 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) |
474 | { |
475 | if (q->last_merge == rq) |
476 | q->last_merge = NULL; |
477 | |
478 | elv_rqhash_del(q, rq); |
479 | |
480 | q->nr_sorted--; |
481 | |
482 | q->end_sector = rq_end_sector(rq); |
483 | q->boundary_rq = rq; |
484 | list_add_tail(&rq->queuelist, &q->queue_head); |
485 | } |
486 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
487 | |
488 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
489 | { |
490 | struct elevator_queue *e = q->elevator; |
491 | struct request *__rq; |
492 | int ret; |
493 | |
494 | /* |
495 | * First try one-hit cache. |
496 | */ |
497 | if (q->last_merge) { |
498 | ret = elv_try_merge(q->last_merge, bio); |
499 | if (ret != ELEVATOR_NO_MERGE) { |
500 | *req = q->last_merge; |
501 | return ret; |
502 | } |
503 | } |
504 | |
505 | if (blk_queue_nomerges(q)) |
506 | return ELEVATOR_NO_MERGE; |
507 | |
508 | /* |
509 | * See if our hash lookup can find a potential backmerge. |
510 | */ |
511 | __rq = elv_rqhash_find(q, bio->bi_sector); |
512 | if (__rq && elv_rq_merge_ok(__rq, bio)) { |
513 | *req = __rq; |
514 | return ELEVATOR_BACK_MERGE; |
515 | } |
516 | |
517 | if (e->ops->elevator_merge_fn) |
518 | return e->ops->elevator_merge_fn(q, req, bio); |
519 | |
520 | return ELEVATOR_NO_MERGE; |
521 | } |
522 | |
523 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
524 | { |
525 | struct elevator_queue *e = q->elevator; |
526 | |
527 | if (e->ops->elevator_merged_fn) |
528 | e->ops->elevator_merged_fn(q, rq, type); |
529 | |
530 | if (type == ELEVATOR_BACK_MERGE) |
531 | elv_rqhash_reposition(q, rq); |
532 | |
533 | q->last_merge = rq; |
534 | } |
535 | |
536 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
537 | struct request *next) |
538 | { |
539 | struct elevator_queue *e = q->elevator; |
540 | |
541 | if (e->ops->elevator_merge_req_fn) |
542 | e->ops->elevator_merge_req_fn(q, rq, next); |
543 | |
544 | elv_rqhash_reposition(q, rq); |
545 | elv_rqhash_del(q, next); |
546 | |
547 | q->nr_sorted--; |
548 | q->last_merge = rq; |
549 | } |
550 | |
551 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
552 | { |
553 | /* |
554 | * it already went through dequeue, we need to decrement the |
555 | * in_flight count again |
556 | */ |
557 | if (blk_account_rq(rq)) { |
558 | q->in_flight[rq_is_sync(rq)]--; |
559 | if (blk_sorted_rq(rq)) |
560 | elv_deactivate_rq(q, rq); |
561 | } |
562 | |
563 | rq->cmd_flags &= ~REQ_STARTED; |
564 | |
565 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
566 | } |
567 | |
568 | void elv_drain_elevator(struct request_queue *q) |
569 | { |
570 | static int printed; |
571 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) |
572 | ; |
573 | if (q->nr_sorted == 0) |
574 | return; |
575 | if (printed++ < 10) { |
576 | printk(KERN_ERR "%s: forced dispatching is broken " |
577 | "(nr_sorted=%u), please report this\n", |
578 | q->elevator->elevator_type->elevator_name, q->nr_sorted); |
579 | } |
580 | } |
581 | |
582 | /* |
583 | * Call with queue lock held, interrupts disabled |
584 | */ |
585 | void elv_quiesce_start(struct request_queue *q) |
586 | { |
587 | if (!q->elevator) |
588 | return; |
589 | |
590 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
591 | |
592 | /* |
593 | * make sure we don't have any requests in flight |
594 | */ |
595 | elv_drain_elevator(q); |
596 | while (q->rq.elvpriv) { |
597 | __blk_run_queue(q); |
598 | spin_unlock_irq(q->queue_lock); |
599 | msleep(10); |
600 | spin_lock_irq(q->queue_lock); |
601 | elv_drain_elevator(q); |
602 | } |
603 | } |
604 | |
605 | void elv_quiesce_end(struct request_queue *q) |
606 | { |
607 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
608 | } |
609 | |
610 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
611 | { |
612 | struct list_head *pos; |
613 | unsigned ordseq; |
614 | int unplug_it = 1; |
615 | |
616 | trace_block_rq_insert(q, rq); |
617 | |
618 | rq->q = q; |
619 | |
620 | switch (where) { |
621 | case ELEVATOR_INSERT_FRONT: |
622 | rq->cmd_flags |= REQ_SOFTBARRIER; |
623 | |
624 | list_add(&rq->queuelist, &q->queue_head); |
625 | break; |
626 | |
627 | case ELEVATOR_INSERT_BACK: |
628 | rq->cmd_flags |= REQ_SOFTBARRIER; |
629 | elv_drain_elevator(q); |
630 | list_add_tail(&rq->queuelist, &q->queue_head); |
631 | /* |
632 | * We kick the queue here for the following reasons. |
633 | * - The elevator might have returned NULL previously |
634 | * to delay requests and returned them now. As the |
635 | * queue wasn't empty before this request, ll_rw_blk |
636 | * won't run the queue on return, resulting in hang. |
637 | * - Usually, back inserted requests won't be merged |
638 | * with anything. There's no point in delaying queue |
639 | * processing. |
640 | */ |
641 | __blk_run_queue(q); |
642 | break; |
643 | |
644 | case ELEVATOR_INSERT_SORT: |
645 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
646 | rq->cmd_flags |= REQ_SORTED; |
647 | q->nr_sorted++; |
648 | if (rq_mergeable(rq)) { |
649 | elv_rqhash_add(q, rq); |
650 | if (!q->last_merge) |
651 | q->last_merge = rq; |
652 | } |
653 | |
654 | /* |
655 | * Some ioscheds (cfq) run q->request_fn directly, so |
656 | * rq cannot be accessed after calling |
657 | * elevator_add_req_fn. |
658 | */ |
659 | q->elevator->ops->elevator_add_req_fn(q, rq); |
660 | break; |
661 | |
662 | case ELEVATOR_INSERT_REQUEUE: |
663 | /* |
664 | * If ordered flush isn't in progress, we do front |
665 | * insertion; otherwise, requests should be requeued |
666 | * in ordseq order. |
667 | */ |
668 | rq->cmd_flags |= REQ_SOFTBARRIER; |
669 | |
670 | /* |
671 | * Most requeues happen because of a busy condition, |
672 | * don't force unplug of the queue for that case. |
673 | */ |
674 | unplug_it = 0; |
675 | |
676 | if (q->ordseq == 0) { |
677 | list_add(&rq->queuelist, &q->queue_head); |
678 | break; |
679 | } |
680 | |
681 | ordseq = blk_ordered_req_seq(rq); |
682 | |
683 | list_for_each(pos, &q->queue_head) { |
684 | struct request *pos_rq = list_entry_rq(pos); |
685 | if (ordseq <= blk_ordered_req_seq(pos_rq)) |
686 | break; |
687 | } |
688 | |
689 | list_add_tail(&rq->queuelist, pos); |
690 | break; |
691 | |
692 | default: |
693 | printk(KERN_ERR "%s: bad insertion point %d\n", |
694 | __func__, where); |
695 | BUG(); |
696 | } |
697 | |
698 | if (unplug_it && blk_queue_plugged(q)) { |
699 | int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC] |
700 | - queue_in_flight(q); |
701 | |
702 | if (nrq >= q->unplug_thresh) |
703 | __generic_unplug_device(q); |
704 | } |
705 | } |
706 | |
707 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
708 | int plug) |
709 | { |
710 | if (q->ordcolor) |
711 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
712 | |
713 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
714 | /* |
715 | * toggle ordered color |
716 | */ |
717 | if (blk_barrier_rq(rq)) |
718 | q->ordcolor ^= 1; |
719 | |
720 | /* |
721 | * barriers implicitly indicate back insertion |
722 | */ |
723 | if (where == ELEVATOR_INSERT_SORT) |
724 | where = ELEVATOR_INSERT_BACK; |
725 | |
726 | /* |
727 | * this request is scheduling boundary, update |
728 | * end_sector |
729 | */ |
730 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
731 | q->end_sector = rq_end_sector(rq); |
732 | q->boundary_rq = rq; |
733 | } |
734 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
735 | where == ELEVATOR_INSERT_SORT) |
736 | where = ELEVATOR_INSERT_BACK; |
737 | |
738 | if (plug) |
739 | blk_plug_device(q); |
740 | |
741 | elv_insert(q, rq, where); |
742 | } |
743 | EXPORT_SYMBOL(__elv_add_request); |
744 | |
745 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
746 | int plug) |
747 | { |
748 | unsigned long flags; |
749 | |
750 | spin_lock_irqsave(q->queue_lock, flags); |
751 | __elv_add_request(q, rq, where, plug); |
752 | spin_unlock_irqrestore(q->queue_lock, flags); |
753 | } |
754 | EXPORT_SYMBOL(elv_add_request); |
755 | |
756 | int elv_queue_empty(struct request_queue *q) |
757 | { |
758 | struct elevator_queue *e = q->elevator; |
759 | |
760 | if (!list_empty(&q->queue_head)) |
761 | return 0; |
762 | |
763 | if (e->ops->elevator_queue_empty_fn) |
764 | return e->ops->elevator_queue_empty_fn(q); |
765 | |
766 | return 1; |
767 | } |
768 | EXPORT_SYMBOL(elv_queue_empty); |
769 | |
770 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
771 | { |
772 | struct elevator_queue *e = q->elevator; |
773 | |
774 | if (e->ops->elevator_latter_req_fn) |
775 | return e->ops->elevator_latter_req_fn(q, rq); |
776 | return NULL; |
777 | } |
778 | |
779 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
780 | { |
781 | struct elevator_queue *e = q->elevator; |
782 | |
783 | if (e->ops->elevator_former_req_fn) |
784 | return e->ops->elevator_former_req_fn(q, rq); |
785 | return NULL; |
786 | } |
787 | |
788 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
789 | { |
790 | struct elevator_queue *e = q->elevator; |
791 | |
792 | if (e->ops->elevator_set_req_fn) |
793 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
794 | |
795 | rq->elevator_private = NULL; |
796 | return 0; |
797 | } |
798 | |
799 | void elv_put_request(struct request_queue *q, struct request *rq) |
800 | { |
801 | struct elevator_queue *e = q->elevator; |
802 | |
803 | if (e->ops->elevator_put_req_fn) |
804 | e->ops->elevator_put_req_fn(rq); |
805 | } |
806 | |
807 | int elv_may_queue(struct request_queue *q, int rw) |
808 | { |
809 | struct elevator_queue *e = q->elevator; |
810 | |
811 | if (e->ops->elevator_may_queue_fn) |
812 | return e->ops->elevator_may_queue_fn(q, rw); |
813 | |
814 | return ELV_MQUEUE_MAY; |
815 | } |
816 | |
817 | void elv_abort_queue(struct request_queue *q) |
818 | { |
819 | struct request *rq; |
820 | |
821 | while (!list_empty(&q->queue_head)) { |
822 | rq = list_entry_rq(q->queue_head.next); |
823 | rq->cmd_flags |= REQ_QUIET; |
824 | trace_block_rq_abort(q, rq); |
825 | /* |
826 | * Mark this request as started so we don't trigger |
827 | * any debug logic in the end I/O path. |
828 | */ |
829 | blk_start_request(rq); |
830 | __blk_end_request_all(rq, -EIO); |
831 | } |
832 | } |
833 | EXPORT_SYMBOL(elv_abort_queue); |
834 | |
835 | void elv_completed_request(struct request_queue *q, struct request *rq) |
836 | { |
837 | struct elevator_queue *e = q->elevator; |
838 | |
839 | /* |
840 | * request is released from the driver, io must be done |
841 | */ |
842 | if (blk_account_rq(rq)) { |
843 | q->in_flight[rq_is_sync(rq)]--; |
844 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
845 | e->ops->elevator_completed_req_fn(q, rq); |
846 | } |
847 | |
848 | /* |
849 | * Check if the queue is waiting for fs requests to be |
850 | * drained for flush sequence. |
851 | */ |
852 | if (unlikely(q->ordseq)) { |
853 | struct request *next = NULL; |
854 | |
855 | if (!list_empty(&q->queue_head)) |
856 | next = list_entry_rq(q->queue_head.next); |
857 | |
858 | if (!queue_in_flight(q) && |
859 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
860 | (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) { |
861 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
862 | __blk_run_queue(q); |
863 | } |
864 | } |
865 | } |
866 | |
867 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
868 | |
869 | static ssize_t |
870 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) |
871 | { |
872 | struct elv_fs_entry *entry = to_elv(attr); |
873 | struct elevator_queue *e; |
874 | ssize_t error; |
875 | |
876 | if (!entry->show) |
877 | return -EIO; |
878 | |
879 | e = container_of(kobj, struct elevator_queue, kobj); |
880 | mutex_lock(&e->sysfs_lock); |
881 | error = e->ops ? entry->show(e, page) : -ENOENT; |
882 | mutex_unlock(&e->sysfs_lock); |
883 | return error; |
884 | } |
885 | |
886 | static ssize_t |
887 | elv_attr_store(struct kobject *kobj, struct attribute *attr, |
888 | const char *page, size_t length) |
889 | { |
890 | struct elv_fs_entry *entry = to_elv(attr); |
891 | struct elevator_queue *e; |
892 | ssize_t error; |
893 | |
894 | if (!entry->store) |
895 | return -EIO; |
896 | |
897 | e = container_of(kobj, struct elevator_queue, kobj); |
898 | mutex_lock(&e->sysfs_lock); |
899 | error = e->ops ? entry->store(e, page, length) : -ENOENT; |
900 | mutex_unlock(&e->sysfs_lock); |
901 | return error; |
902 | } |
903 | |
904 | static struct sysfs_ops elv_sysfs_ops = { |
905 | .show = elv_attr_show, |
906 | .store = elv_attr_store, |
907 | }; |
908 | |
909 | static struct kobj_type elv_ktype = { |
910 | .sysfs_ops = &elv_sysfs_ops, |
911 | .release = elevator_release, |
912 | }; |
913 | |
914 | int elv_register_queue(struct request_queue *q) |
915 | { |
916 | struct elevator_queue *e = q->elevator; |
917 | int error; |
918 | |
919 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
920 | if (!error) { |
921 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
922 | if (attr) { |
923 | while (attr->attr.name) { |
924 | if (sysfs_create_file(&e->kobj, &attr->attr)) |
925 | break; |
926 | attr++; |
927 | } |
928 | } |
929 | kobject_uevent(&e->kobj, KOBJ_ADD); |
930 | } |
931 | return error; |
932 | } |
933 | |
934 | static void __elv_unregister_queue(struct elevator_queue *e) |
935 | { |
936 | kobject_uevent(&e->kobj, KOBJ_REMOVE); |
937 | kobject_del(&e->kobj); |
938 | } |
939 | |
940 | void elv_unregister_queue(struct request_queue *q) |
941 | { |
942 | if (q) |
943 | __elv_unregister_queue(q->elevator); |
944 | } |
945 | |
946 | void elv_register(struct elevator_type *e) |
947 | { |
948 | char *def = ""; |
949 | |
950 | spin_lock(&elv_list_lock); |
951 | BUG_ON(elevator_find(e->elevator_name)); |
952 | list_add_tail(&e->list, &elv_list); |
953 | spin_unlock(&elv_list_lock); |
954 | |
955 | if (!strcmp(e->elevator_name, chosen_elevator) || |
956 | (!*chosen_elevator && |
957 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) |
958 | def = " (default)"; |
959 | |
960 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
961 | def); |
962 | } |
963 | EXPORT_SYMBOL_GPL(elv_register); |
964 | |
965 | void elv_unregister(struct elevator_type *e) |
966 | { |
967 | struct task_struct *g, *p; |
968 | |
969 | /* |
970 | * Iterate every thread in the process to remove the io contexts. |
971 | */ |
972 | if (e->ops.trim) { |
973 | read_lock(&tasklist_lock); |
974 | do_each_thread(g, p) { |
975 | task_lock(p); |
976 | if (p->io_context) |
977 | e->ops.trim(p->io_context); |
978 | task_unlock(p); |
979 | } while_each_thread(g, p); |
980 | read_unlock(&tasklist_lock); |
981 | } |
982 | |
983 | spin_lock(&elv_list_lock); |
984 | list_del_init(&e->list); |
985 | spin_unlock(&elv_list_lock); |
986 | } |
987 | EXPORT_SYMBOL_GPL(elv_unregister); |
988 | |
989 | /* |
990 | * switch to new_e io scheduler. be careful not to introduce deadlocks - |
991 | * we don't free the old io scheduler, before we have allocated what we |
992 | * need for the new one. this way we have a chance of going back to the old |
993 | * one, if the new one fails init for some reason. |
994 | */ |
995 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
996 | { |
997 | struct elevator_queue *old_elevator, *e; |
998 | void *data; |
999 | |
1000 | /* |
1001 | * Allocate new elevator |
1002 | */ |
1003 | e = elevator_alloc(q, new_e); |
1004 | if (!e) |
1005 | return 0; |
1006 | |
1007 | data = elevator_init_queue(q, e); |
1008 | if (!data) { |
1009 | kobject_put(&e->kobj); |
1010 | return 0; |
1011 | } |
1012 | |
1013 | /* |
1014 | * Turn on BYPASS and drain all requests w/ elevator private data |
1015 | */ |
1016 | spin_lock_irq(q->queue_lock); |
1017 | elv_quiesce_start(q); |
1018 | |
1019 | /* |
1020 | * Remember old elevator. |
1021 | */ |
1022 | old_elevator = q->elevator; |
1023 | |
1024 | /* |
1025 | * attach and start new elevator |
1026 | */ |
1027 | elevator_attach(q, e, data); |
1028 | |
1029 | spin_unlock_irq(q->queue_lock); |
1030 | |
1031 | __elv_unregister_queue(old_elevator); |
1032 | |
1033 | if (elv_register_queue(q)) |
1034 | goto fail_register; |
1035 | |
1036 | /* |
1037 | * finally exit old elevator and turn off BYPASS. |
1038 | */ |
1039 | elevator_exit(old_elevator); |
1040 | spin_lock_irq(q->queue_lock); |
1041 | elv_quiesce_end(q); |
1042 | spin_unlock_irq(q->queue_lock); |
1043 | |
1044 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1045 | |
1046 | return 1; |
1047 | |
1048 | fail_register: |
1049 | /* |
1050 | * switch failed, exit the new io scheduler and reattach the old |
1051 | * one again (along with re-adding the sysfs dir) |
1052 | */ |
1053 | elevator_exit(e); |
1054 | q->elevator = old_elevator; |
1055 | elv_register_queue(q); |
1056 | |
1057 | spin_lock_irq(q->queue_lock); |
1058 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
1059 | spin_unlock_irq(q->queue_lock); |
1060 | |
1061 | return 0; |
1062 | } |
1063 | |
1064 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1065 | size_t count) |
1066 | { |
1067 | char elevator_name[ELV_NAME_MAX]; |
1068 | struct elevator_type *e; |
1069 | |
1070 | if (!q->elevator) |
1071 | return count; |
1072 | |
1073 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1074 | strstrip(elevator_name); |
1075 | |
1076 | e = elevator_get(elevator_name); |
1077 | if (!e) { |
1078 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); |
1079 | return -EINVAL; |
1080 | } |
1081 | |
1082 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1083 | elevator_put(e); |
1084 | return count; |
1085 | } |
1086 | |
1087 | if (!elevator_switch(q, e)) |
1088 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1089 | elevator_name); |
1090 | return count; |
1091 | } |
1092 | |
1093 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1094 | { |
1095 | struct elevator_queue *e = q->elevator; |
1096 | struct elevator_type *elv; |
1097 | struct elevator_type *__e; |
1098 | int len = 0; |
1099 | |
1100 | if (!q->elevator) |
1101 | return sprintf(name, "none\n"); |
1102 | |
1103 | elv = e->elevator_type; |
1104 | |
1105 | spin_lock(&elv_list_lock); |
1106 | list_for_each_entry(__e, &elv_list, list) { |
1107 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1108 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
1109 | else |
1110 | len += sprintf(name+len, "%s ", __e->elevator_name); |
1111 | } |
1112 | spin_unlock(&elv_list_lock); |
1113 | |
1114 | len += sprintf(len+name, "\n"); |
1115 | return len; |
1116 | } |
1117 | |
1118 | struct request *elv_rb_former_request(struct request_queue *q, |
1119 | struct request *rq) |
1120 | { |
1121 | struct rb_node *rbprev = rb_prev(&rq->rb_node); |
1122 | |
1123 | if (rbprev) |
1124 | return rb_entry_rq(rbprev); |
1125 | |
1126 | return NULL; |
1127 | } |
1128 | EXPORT_SYMBOL(elv_rb_former_request); |
1129 | |
1130 | struct request *elv_rb_latter_request(struct request_queue *q, |
1131 | struct request *rq) |
1132 | { |
1133 | struct rb_node *rbnext = rb_next(&rq->rb_node); |
1134 | |
1135 | if (rbnext) |
1136 | return rb_entry_rq(rbnext); |
1137 | |
1138 | return NULL; |
1139 | } |
1140 | EXPORT_SYMBOL(elv_rb_latter_request); |
1141 |
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