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1da177e4 LT |
1 | /* |
2 | * linux/drivers/block/elevator.c | |
3 | * | |
4 | * Block device elevator/IO-scheduler. | |
5 | * | |
6 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
7 | * | |
8 | * 30042000 Jens Axboe <axboe@suse.de> : | |
9 | * | |
10 | * Split the elevator a bit so that it is possible to choose a different | |
11 | * one or even write a new "plug in". There are three pieces: | |
12 | * - elevator_fn, inserts a new request in the queue list | |
13 | * - elevator_merge_fn, decides whether a new buffer can be merged with | |
14 | * an existing request | |
15 | * - elevator_dequeue_fn, called when a request is taken off the active list | |
16 | * | |
17 | * 20082000 Dave Jones <davej@suse.de> : | |
18 | * Removed tests for max-bomb-segments, which was breaking elvtune | |
19 | * when run without -bN | |
20 | * | |
21 | * Jens: | |
22 | * - Rework again to work with bio instead of buffer_heads | |
23 | * - loose bi_dev comparisons, partition handling is right now | |
24 | * - completely modularize elevator setup and teardown | |
25 | * | |
26 | */ | |
27 | #include <linux/kernel.h> | |
28 | #include <linux/fs.h> | |
29 | #include <linux/blkdev.h> | |
30 | #include <linux/elevator.h> | |
31 | #include <linux/bio.h> | |
32 | #include <linux/config.h> | |
33 | #include <linux/module.h> | |
34 | #include <linux/slab.h> | |
35 | #include <linux/init.h> | |
36 | #include <linux/compiler.h> | |
37 | ||
38 | #include <asm/uaccess.h> | |
39 | ||
40 | static DEFINE_SPINLOCK(elv_list_lock); | |
41 | static LIST_HEAD(elv_list); | |
42 | ||
43 | /* | |
44 | * can we safely merge with this request? | |
45 | */ | |
46 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) | |
47 | { | |
48 | if (!rq_mergeable(rq)) | |
49 | return 0; | |
50 | ||
51 | /* | |
52 | * different data direction or already started, don't merge | |
53 | */ | |
54 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
55 | return 0; | |
56 | ||
57 | /* | |
58 | * same device and no special stuff set, merge is ok | |
59 | */ | |
60 | if (rq->rq_disk == bio->bi_bdev->bd_disk && | |
61 | !rq->waiting && !rq->special) | |
62 | return 1; | |
63 | ||
64 | return 0; | |
65 | } | |
66 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
67 | ||
68 | inline int elv_try_merge(struct request *__rq, struct bio *bio) | |
69 | { | |
70 | int ret = ELEVATOR_NO_MERGE; | |
71 | ||
72 | /* | |
73 | * we can merge and sequence is ok, check if it's possible | |
74 | */ | |
75 | if (elv_rq_merge_ok(__rq, bio)) { | |
76 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
77 | ret = ELEVATOR_BACK_MERGE; | |
78 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
79 | ret = ELEVATOR_FRONT_MERGE; | |
80 | } | |
81 | ||
82 | return ret; | |
83 | } | |
84 | EXPORT_SYMBOL(elv_try_merge); | |
85 | ||
86 | inline int elv_try_last_merge(request_queue_t *q, struct bio *bio) | |
87 | { | |
88 | if (q->last_merge) | |
89 | return elv_try_merge(q->last_merge, bio); | |
90 | ||
91 | return ELEVATOR_NO_MERGE; | |
92 | } | |
93 | EXPORT_SYMBOL(elv_try_last_merge); | |
94 | ||
95 | static struct elevator_type *elevator_find(const char *name) | |
96 | { | |
97 | struct elevator_type *e = NULL; | |
98 | struct list_head *entry; | |
99 | ||
100 | spin_lock_irq(&elv_list_lock); | |
101 | list_for_each(entry, &elv_list) { | |
102 | struct elevator_type *__e; | |
103 | ||
104 | __e = list_entry(entry, struct elevator_type, list); | |
105 | ||
106 | if (!strcmp(__e->elevator_name, name)) { | |
107 | e = __e; | |
108 | break; | |
109 | } | |
110 | } | |
111 | spin_unlock_irq(&elv_list_lock); | |
112 | ||
113 | return e; | |
114 | } | |
115 | ||
116 | static void elevator_put(struct elevator_type *e) | |
117 | { | |
118 | module_put(e->elevator_owner); | |
119 | } | |
120 | ||
121 | static struct elevator_type *elevator_get(const char *name) | |
122 | { | |
123 | struct elevator_type *e = elevator_find(name); | |
124 | ||
125 | if (!e) | |
126 | return NULL; | |
127 | if (!try_module_get(e->elevator_owner)) | |
128 | return NULL; | |
129 | ||
130 | return e; | |
131 | } | |
132 | ||
133 | static int elevator_attach(request_queue_t *q, struct elevator_type *e, | |
134 | struct elevator_queue *eq) | |
135 | { | |
136 | int ret = 0; | |
137 | ||
138 | memset(eq, 0, sizeof(*eq)); | |
139 | eq->ops = &e->ops; | |
140 | eq->elevator_type = e; | |
141 | ||
142 | INIT_LIST_HEAD(&q->queue_head); | |
143 | q->last_merge = NULL; | |
144 | q->elevator = eq; | |
145 | ||
146 | if (eq->ops->elevator_init_fn) | |
147 | ret = eq->ops->elevator_init_fn(q, eq); | |
148 | ||
149 | return ret; | |
150 | } | |
151 | ||
152 | static char chosen_elevator[16]; | |
153 | ||
154 | static void elevator_setup_default(void) | |
155 | { | |
156 | /* | |
157 | * check if default is set and exists | |
158 | */ | |
159 | if (chosen_elevator[0] && elevator_find(chosen_elevator)) | |
160 | return; | |
161 | ||
162 | #if defined(CONFIG_IOSCHED_AS) | |
163 | strcpy(chosen_elevator, "anticipatory"); | |
164 | #elif defined(CONFIG_IOSCHED_DEADLINE) | |
165 | strcpy(chosen_elevator, "deadline"); | |
166 | #elif defined(CONFIG_IOSCHED_CFQ) | |
167 | strcpy(chosen_elevator, "cfq"); | |
168 | #elif defined(CONFIG_IOSCHED_NOOP) | |
169 | strcpy(chosen_elevator, "noop"); | |
170 | #else | |
171 | #error "You must build at least 1 IO scheduler into the kernel" | |
172 | #endif | |
173 | } | |
174 | ||
175 | static int __init elevator_setup(char *str) | |
176 | { | |
177 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); | |
178 | return 0; | |
179 | } | |
180 | ||
181 | __setup("elevator=", elevator_setup); | |
182 | ||
183 | int elevator_init(request_queue_t *q, char *name) | |
184 | { | |
185 | struct elevator_type *e = NULL; | |
186 | struct elevator_queue *eq; | |
187 | int ret = 0; | |
188 | ||
189 | elevator_setup_default(); | |
190 | ||
191 | if (!name) | |
192 | name = chosen_elevator; | |
193 | ||
194 | e = elevator_get(name); | |
195 | if (!e) | |
196 | return -EINVAL; | |
197 | ||
198 | eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL); | |
199 | if (!eq) { | |
200 | elevator_put(e->elevator_type); | |
201 | return -ENOMEM; | |
202 | } | |
203 | ||
204 | ret = elevator_attach(q, e, eq); | |
205 | if (ret) { | |
206 | kfree(eq); | |
207 | elevator_put(e->elevator_type); | |
208 | } | |
209 | ||
210 | return ret; | |
211 | } | |
212 | ||
213 | void elevator_exit(elevator_t *e) | |
214 | { | |
215 | if (e->ops->elevator_exit_fn) | |
216 | e->ops->elevator_exit_fn(e); | |
217 | ||
218 | elevator_put(e->elevator_type); | |
219 | e->elevator_type = NULL; | |
220 | kfree(e); | |
221 | } | |
222 | ||
1da177e4 LT |
223 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
224 | { | |
225 | elevator_t *e = q->elevator; | |
226 | ||
227 | if (e->ops->elevator_merge_fn) | |
228 | return e->ops->elevator_merge_fn(q, req, bio); | |
229 | ||
230 | return ELEVATOR_NO_MERGE; | |
231 | } | |
232 | ||
233 | void elv_merged_request(request_queue_t *q, struct request *rq) | |
234 | { | |
235 | elevator_t *e = q->elevator; | |
236 | ||
237 | if (e->ops->elevator_merged_fn) | |
238 | e->ops->elevator_merged_fn(q, rq); | |
239 | } | |
240 | ||
241 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
242 | struct request *next) | |
243 | { | |
244 | elevator_t *e = q->elevator; | |
245 | ||
246 | if (q->last_merge == next) | |
247 | q->last_merge = NULL; | |
248 | ||
249 | if (e->ops->elevator_merge_req_fn) | |
250 | e->ops->elevator_merge_req_fn(q, rq, next); | |
251 | } | |
252 | ||
253 | /* | |
254 | * For careful internal use by the block layer. Essentially the same as | |
255 | * a requeue in that it tells the io scheduler that this request is not | |
256 | * active in the driver or hardware anymore, but we don't want the request | |
257 | * added back to the scheduler. Function is not exported. | |
258 | */ | |
259 | void elv_deactivate_request(request_queue_t *q, struct request *rq) | |
260 | { | |
261 | elevator_t *e = q->elevator; | |
262 | ||
263 | /* | |
264 | * it already went through dequeue, we need to decrement the | |
265 | * in_flight count again | |
266 | */ | |
267 | if (blk_account_rq(rq)) | |
268 | q->in_flight--; | |
269 | ||
270 | rq->flags &= ~REQ_STARTED; | |
271 | ||
272 | if (e->ops->elevator_deactivate_req_fn) | |
273 | e->ops->elevator_deactivate_req_fn(q, rq); | |
274 | } | |
275 | ||
276 | void elv_requeue_request(request_queue_t *q, struct request *rq) | |
277 | { | |
278 | elv_deactivate_request(q, rq); | |
279 | ||
280 | /* | |
281 | * if this is the flush, requeue the original instead and drop the flush | |
282 | */ | |
283 | if (rq->flags & REQ_BAR_FLUSH) { | |
284 | clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); | |
285 | rq = rq->end_io_data; | |
286 | } | |
287 | ||
2e759cd4 TH |
288 | /* |
289 | * the request is prepped and may have some resources allocated. | |
290 | * allowing unprepped requests to pass this one may cause resource | |
291 | * deadlock. turn on softbarrier. | |
292 | */ | |
293 | rq->flags |= REQ_SOFTBARRIER; | |
294 | ||
1da177e4 LT |
295 | /* |
296 | * if iosched has an explicit requeue hook, then use that. otherwise | |
297 | * just put the request at the front of the queue | |
298 | */ | |
299 | if (q->elevator->ops->elevator_requeue_req_fn) | |
300 | q->elevator->ops->elevator_requeue_req_fn(q, rq); | |
301 | else | |
302 | __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0); | |
303 | } | |
304 | ||
305 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, | |
306 | int plug) | |
307 | { | |
308 | /* | |
309 | * barriers implicitly indicate back insertion | |
310 | */ | |
311 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER) && | |
312 | where == ELEVATOR_INSERT_SORT) | |
313 | where = ELEVATOR_INSERT_BACK; | |
314 | ||
315 | if (plug) | |
316 | blk_plug_device(q); | |
317 | ||
318 | rq->q = q; | |
319 | ||
320 | if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) { | |
321 | q->elevator->ops->elevator_add_req_fn(q, rq, where); | |
322 | ||
323 | if (blk_queue_plugged(q)) { | |
324 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] | |
325 | - q->in_flight; | |
326 | ||
c374f127 | 327 | if (nrq >= q->unplug_thresh) |
1da177e4 LT |
328 | __generic_unplug_device(q); |
329 | } | |
330 | } else | |
331 | /* | |
332 | * if drain is set, store the request "locally". when the drain | |
333 | * is finished, the requests will be handed ordered to the io | |
334 | * scheduler | |
335 | */ | |
336 | list_add_tail(&rq->queuelist, &q->drain_list); | |
337 | } | |
338 | ||
339 | void elv_add_request(request_queue_t *q, struct request *rq, int where, | |
340 | int plug) | |
341 | { | |
342 | unsigned long flags; | |
343 | ||
344 | spin_lock_irqsave(q->queue_lock, flags); | |
345 | __elv_add_request(q, rq, where, plug); | |
346 | spin_unlock_irqrestore(q->queue_lock, flags); | |
347 | } | |
348 | ||
349 | static inline struct request *__elv_next_request(request_queue_t *q) | |
350 | { | |
351 | struct request *rq = q->elevator->ops->elevator_next_req_fn(q); | |
352 | ||
353 | /* | |
354 | * if this is a barrier write and the device has to issue a | |
355 | * flush sequence to support it, check how far we are | |
356 | */ | |
357 | if (rq && blk_fs_request(rq) && blk_barrier_rq(rq)) { | |
358 | BUG_ON(q->ordered == QUEUE_ORDERED_NONE); | |
359 | ||
360 | if (q->ordered == QUEUE_ORDERED_FLUSH && | |
361 | !blk_barrier_preflush(rq)) | |
362 | rq = blk_start_pre_flush(q, rq); | |
363 | } | |
364 | ||
365 | return rq; | |
366 | } | |
367 | ||
368 | struct request *elv_next_request(request_queue_t *q) | |
369 | { | |
370 | struct request *rq; | |
371 | int ret; | |
372 | ||
373 | while ((rq = __elv_next_request(q)) != NULL) { | |
374 | /* | |
375 | * just mark as started even if we don't start it, a request | |
376 | * that has been delayed should not be passed by new incoming | |
377 | * requests | |
378 | */ | |
379 | rq->flags |= REQ_STARTED; | |
380 | ||
381 | if (rq == q->last_merge) | |
382 | q->last_merge = NULL; | |
383 | ||
384 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) | |
385 | break; | |
386 | ||
387 | ret = q->prep_rq_fn(q, rq); | |
388 | if (ret == BLKPREP_OK) { | |
389 | break; | |
390 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
391 | /* |
392 | * the request may have been (partially) prepped. | |
393 | * we need to keep this request in the front to | |
394 | * avoid resource deadlock. turn on softbarrier. | |
395 | */ | |
396 | rq->flags |= REQ_SOFTBARRIER; | |
1da177e4 LT |
397 | rq = NULL; |
398 | break; | |
399 | } else if (ret == BLKPREP_KILL) { | |
400 | int nr_bytes = rq->hard_nr_sectors << 9; | |
401 | ||
402 | if (!nr_bytes) | |
403 | nr_bytes = rq->data_len; | |
404 | ||
405 | blkdev_dequeue_request(rq); | |
406 | rq->flags |= REQ_QUIET; | |
407 | end_that_request_chunk(rq, 0, nr_bytes); | |
408 | end_that_request_last(rq); | |
409 | } else { | |
410 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
411 | ret); | |
412 | break; | |
413 | } | |
414 | } | |
415 | ||
416 | return rq; | |
417 | } | |
418 | ||
419 | void elv_remove_request(request_queue_t *q, struct request *rq) | |
420 | { | |
421 | elevator_t *e = q->elevator; | |
422 | ||
423 | /* | |
424 | * the time frame between a request being removed from the lists | |
425 | * and to it is freed is accounted as io that is in progress at | |
426 | * the driver side. note that we only account requests that the | |
427 | * driver has seen (REQ_STARTED set), to avoid false accounting | |
428 | * for request-request merges | |
429 | */ | |
430 | if (blk_account_rq(rq)) | |
431 | q->in_flight++; | |
432 | ||
433 | /* | |
434 | * the main clearing point for q->last_merge is on retrieval of | |
435 | * request by driver (it calls elv_next_request()), but it _can_ | |
436 | * also happen here if a request is added to the queue but later | |
437 | * deleted without ever being given to driver (merged with another | |
438 | * request). | |
439 | */ | |
440 | if (rq == q->last_merge) | |
441 | q->last_merge = NULL; | |
442 | ||
443 | if (e->ops->elevator_remove_req_fn) | |
444 | e->ops->elevator_remove_req_fn(q, rq); | |
445 | } | |
446 | ||
447 | int elv_queue_empty(request_queue_t *q) | |
448 | { | |
449 | elevator_t *e = q->elevator; | |
450 | ||
451 | if (e->ops->elevator_queue_empty_fn) | |
452 | return e->ops->elevator_queue_empty_fn(q); | |
453 | ||
454 | return list_empty(&q->queue_head); | |
455 | } | |
456 | ||
457 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) | |
458 | { | |
459 | struct list_head *next; | |
460 | ||
461 | elevator_t *e = q->elevator; | |
462 | ||
463 | if (e->ops->elevator_latter_req_fn) | |
464 | return e->ops->elevator_latter_req_fn(q, rq); | |
465 | ||
466 | next = rq->queuelist.next; | |
467 | if (next != &q->queue_head && next != &rq->queuelist) | |
468 | return list_entry_rq(next); | |
469 | ||
470 | return NULL; | |
471 | } | |
472 | ||
473 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
474 | { | |
475 | struct list_head *prev; | |
476 | ||
477 | elevator_t *e = q->elevator; | |
478 | ||
479 | if (e->ops->elevator_former_req_fn) | |
480 | return e->ops->elevator_former_req_fn(q, rq); | |
481 | ||
482 | prev = rq->queuelist.prev; | |
483 | if (prev != &q->queue_head && prev != &rq->queuelist) | |
484 | return list_entry_rq(prev); | |
485 | ||
486 | return NULL; | |
487 | } | |
488 | ||
22e2c507 JA |
489 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
490 | int gfp_mask) | |
1da177e4 LT |
491 | { |
492 | elevator_t *e = q->elevator; | |
493 | ||
494 | if (e->ops->elevator_set_req_fn) | |
22e2c507 | 495 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
496 | |
497 | rq->elevator_private = NULL; | |
498 | return 0; | |
499 | } | |
500 | ||
501 | void elv_put_request(request_queue_t *q, struct request *rq) | |
502 | { | |
503 | elevator_t *e = q->elevator; | |
504 | ||
505 | if (e->ops->elevator_put_req_fn) | |
506 | e->ops->elevator_put_req_fn(q, rq); | |
507 | } | |
508 | ||
22e2c507 | 509 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
510 | { |
511 | elevator_t *e = q->elevator; | |
512 | ||
513 | if (e->ops->elevator_may_queue_fn) | |
22e2c507 | 514 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
1da177e4 LT |
515 | |
516 | return ELV_MQUEUE_MAY; | |
517 | } | |
518 | ||
519 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
520 | { | |
521 | elevator_t *e = q->elevator; | |
522 | ||
523 | /* | |
524 | * request is released from the driver, io must be done | |
525 | */ | |
526 | if (blk_account_rq(rq)) | |
527 | q->in_flight--; | |
528 | ||
529 | if (e->ops->elevator_completed_req_fn) | |
530 | e->ops->elevator_completed_req_fn(q, rq); | |
531 | } | |
532 | ||
533 | int elv_register_queue(struct request_queue *q) | |
534 | { | |
535 | elevator_t *e = q->elevator; | |
536 | ||
537 | e->kobj.parent = kobject_get(&q->kobj); | |
538 | if (!e->kobj.parent) | |
539 | return -EBUSY; | |
540 | ||
541 | snprintf(e->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
542 | e->kobj.ktype = e->elevator_type->elevator_ktype; | |
543 | ||
544 | return kobject_register(&e->kobj); | |
545 | } | |
546 | ||
547 | void elv_unregister_queue(struct request_queue *q) | |
548 | { | |
549 | if (q) { | |
550 | elevator_t *e = q->elevator; | |
551 | kobject_unregister(&e->kobj); | |
552 | kobject_put(&q->kobj); | |
553 | } | |
554 | } | |
555 | ||
556 | int elv_register(struct elevator_type *e) | |
557 | { | |
558 | if (elevator_find(e->elevator_name)) | |
559 | BUG(); | |
560 | ||
561 | spin_lock_irq(&elv_list_lock); | |
562 | list_add_tail(&e->list, &elv_list); | |
563 | spin_unlock_irq(&elv_list_lock); | |
564 | ||
565 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
566 | if (!strcmp(e->elevator_name, chosen_elevator)) | |
567 | printk(" (default)"); | |
568 | printk("\n"); | |
569 | return 0; | |
570 | } | |
571 | EXPORT_SYMBOL_GPL(elv_register); | |
572 | ||
573 | void elv_unregister(struct elevator_type *e) | |
574 | { | |
575 | spin_lock_irq(&elv_list_lock); | |
576 | list_del_init(&e->list); | |
577 | spin_unlock_irq(&elv_list_lock); | |
578 | } | |
579 | EXPORT_SYMBOL_GPL(elv_unregister); | |
580 | ||
581 | /* | |
582 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
583 | * we don't free the old io scheduler, before we have allocated what we | |
584 | * need for the new one. this way we have a chance of going back to the old | |
585 | * one, if the new one fails init for some reason. we also do an intermediate | |
586 | * switch to noop to ensure safety with stack-allocated requests, since they | |
587 | * don't originate from the block layer allocator. noop is safe here, because | |
588 | * it never needs to touch the elevator itself for completion events. DRAIN | |
589 | * flags will make sure we don't touch it for additions either. | |
590 | */ | |
591 | static void elevator_switch(request_queue_t *q, struct elevator_type *new_e) | |
592 | { | |
593 | elevator_t *e = kmalloc(sizeof(elevator_t), GFP_KERNEL); | |
594 | struct elevator_type *noop_elevator = NULL; | |
595 | elevator_t *old_elevator; | |
596 | ||
597 | if (!e) | |
598 | goto error; | |
599 | ||
600 | /* | |
601 | * first step, drain requests from the block freelist | |
602 | */ | |
603 | blk_wait_queue_drained(q, 0); | |
604 | ||
605 | /* | |
606 | * unregister old elevator data | |
607 | */ | |
608 | elv_unregister_queue(q); | |
609 | old_elevator = q->elevator; | |
610 | ||
611 | /* | |
612 | * next step, switch to noop since it uses no private rq structures | |
613 | * and doesn't allocate any memory for anything. then wait for any | |
614 | * non-fs requests in-flight | |
615 | */ | |
616 | noop_elevator = elevator_get("noop"); | |
617 | spin_lock_irq(q->queue_lock); | |
618 | elevator_attach(q, noop_elevator, e); | |
619 | spin_unlock_irq(q->queue_lock); | |
620 | ||
621 | blk_wait_queue_drained(q, 1); | |
622 | ||
623 | /* | |
624 | * attach and start new elevator | |
625 | */ | |
626 | if (elevator_attach(q, new_e, e)) | |
627 | goto fail; | |
628 | ||
629 | if (elv_register_queue(q)) | |
630 | goto fail_register; | |
631 | ||
632 | /* | |
633 | * finally exit old elevator and start queue again | |
634 | */ | |
635 | elevator_exit(old_elevator); | |
636 | blk_finish_queue_drain(q); | |
637 | elevator_put(noop_elevator); | |
638 | return; | |
639 | ||
640 | fail_register: | |
641 | /* | |
642 | * switch failed, exit the new io scheduler and reattach the old | |
643 | * one again (along with re-adding the sysfs dir) | |
644 | */ | |
645 | elevator_exit(e); | |
646 | fail: | |
647 | q->elevator = old_elevator; | |
648 | elv_register_queue(q); | |
649 | blk_finish_queue_drain(q); | |
650 | error: | |
651 | if (noop_elevator) | |
652 | elevator_put(noop_elevator); | |
653 | elevator_put(new_e); | |
654 | printk(KERN_ERR "elevator: switch to %s failed\n",new_e->elevator_name); | |
655 | } | |
656 | ||
657 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
658 | { | |
659 | char elevator_name[ELV_NAME_MAX]; | |
660 | struct elevator_type *e; | |
661 | ||
662 | memset(elevator_name, 0, sizeof(elevator_name)); | |
663 | strncpy(elevator_name, name, sizeof(elevator_name)); | |
664 | ||
665 | if (elevator_name[strlen(elevator_name) - 1] == '\n') | |
666 | elevator_name[strlen(elevator_name) - 1] = '\0'; | |
667 | ||
668 | e = elevator_get(elevator_name); | |
669 | if (!e) { | |
670 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
671 | return -EINVAL; | |
672 | } | |
673 | ||
674 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) | |
675 | return count; | |
676 | ||
677 | elevator_switch(q, e); | |
678 | return count; | |
679 | } | |
680 | ||
681 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
682 | { | |
683 | elevator_t *e = q->elevator; | |
684 | struct elevator_type *elv = e->elevator_type; | |
685 | struct list_head *entry; | |
686 | int len = 0; | |
687 | ||
688 | spin_lock_irq(q->queue_lock); | |
689 | list_for_each(entry, &elv_list) { | |
690 | struct elevator_type *__e; | |
691 | ||
692 | __e = list_entry(entry, struct elevator_type, list); | |
693 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
694 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
695 | else | |
696 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
697 | } | |
698 | spin_unlock_irq(q->queue_lock); | |
699 | ||
700 | len += sprintf(len+name, "\n"); | |
701 | return len; | |
702 | } | |
703 | ||
1da177e4 LT |
704 | EXPORT_SYMBOL(elv_add_request); |
705 | EXPORT_SYMBOL(__elv_add_request); | |
706 | EXPORT_SYMBOL(elv_requeue_request); | |
707 | EXPORT_SYMBOL(elv_next_request); | |
708 | EXPORT_SYMBOL(elv_remove_request); | |
709 | EXPORT_SYMBOL(elv_queue_empty); | |
710 | EXPORT_SYMBOL(elv_completed_request); | |
711 | EXPORT_SYMBOL(elevator_exit); | |
712 | EXPORT_SYMBOL(elevator_init); |