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