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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 | ||
1da177e4 LT |
100 | list_for_each(entry, &elv_list) { |
101 | struct elevator_type *__e; | |
102 | ||
103 | __e = list_entry(entry, struct elevator_type, list); | |
104 | ||
105 | if (!strcmp(__e->elevator_name, name)) { | |
106 | e = __e; | |
107 | break; | |
108 | } | |
109 | } | |
1da177e4 LT |
110 | |
111 | return e; | |
112 | } | |
113 | ||
114 | static void elevator_put(struct elevator_type *e) | |
115 | { | |
116 | module_put(e->elevator_owner); | |
117 | } | |
118 | ||
119 | static struct elevator_type *elevator_get(const char *name) | |
120 | { | |
2824bc93 | 121 | struct elevator_type *e; |
1da177e4 | 122 | |
2824bc93 TH |
123 | spin_lock_irq(&elv_list_lock); |
124 | ||
125 | e = elevator_find(name); | |
126 | if (e && !try_module_get(e->elevator_owner)) | |
127 | e = NULL; | |
128 | ||
129 | spin_unlock_irq(&elv_list_lock); | |
1da177e4 LT |
130 | |
131 | return e; | |
132 | } | |
133 | ||
134 | static int elevator_attach(request_queue_t *q, struct elevator_type *e, | |
135 | struct elevator_queue *eq) | |
136 | { | |
137 | int ret = 0; | |
138 | ||
139 | memset(eq, 0, sizeof(*eq)); | |
140 | eq->ops = &e->ops; | |
141 | eq->elevator_type = e; | |
142 | ||
143 | INIT_LIST_HEAD(&q->queue_head); | |
144 | q->last_merge = NULL; | |
145 | q->elevator = eq; | |
146 | ||
147 | if (eq->ops->elevator_init_fn) | |
148 | ret = eq->ops->elevator_init_fn(q, eq); | |
149 | ||
150 | return ret; | |
151 | } | |
152 | ||
153 | static char chosen_elevator[16]; | |
154 | ||
155 | static void elevator_setup_default(void) | |
156 | { | |
2824bc93 TH |
157 | struct elevator_type *e; |
158 | ||
1da177e4 LT |
159 | /* |
160 | * check if default is set and exists | |
161 | */ | |
2824bc93 TH |
162 | if (chosen_elevator[0] && (e = elevator_get(chosen_elevator))) { |
163 | elevator_put(e); | |
1da177e4 | 164 | return; |
2824bc93 | 165 | } |
1da177e4 LT |
166 | |
167 | #if defined(CONFIG_IOSCHED_AS) | |
168 | strcpy(chosen_elevator, "anticipatory"); | |
169 | #elif defined(CONFIG_IOSCHED_DEADLINE) | |
170 | strcpy(chosen_elevator, "deadline"); | |
171 | #elif defined(CONFIG_IOSCHED_CFQ) | |
172 | strcpy(chosen_elevator, "cfq"); | |
173 | #elif defined(CONFIG_IOSCHED_NOOP) | |
174 | strcpy(chosen_elevator, "noop"); | |
175 | #else | |
176 | #error "You must build at least 1 IO scheduler into the kernel" | |
177 | #endif | |
178 | } | |
179 | ||
180 | static int __init elevator_setup(char *str) | |
181 | { | |
182 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); | |
183 | return 0; | |
184 | } | |
185 | ||
186 | __setup("elevator=", elevator_setup); | |
187 | ||
188 | int elevator_init(request_queue_t *q, char *name) | |
189 | { | |
190 | struct elevator_type *e = NULL; | |
191 | struct elevator_queue *eq; | |
192 | int ret = 0; | |
193 | ||
194 | elevator_setup_default(); | |
195 | ||
196 | if (!name) | |
197 | name = chosen_elevator; | |
198 | ||
199 | e = elevator_get(name); | |
200 | if (!e) | |
201 | return -EINVAL; | |
202 | ||
203 | eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL); | |
204 | if (!eq) { | |
205 | elevator_put(e->elevator_type); | |
206 | return -ENOMEM; | |
207 | } | |
208 | ||
209 | ret = elevator_attach(q, e, eq); | |
210 | if (ret) { | |
211 | kfree(eq); | |
212 | elevator_put(e->elevator_type); | |
213 | } | |
214 | ||
215 | return ret; | |
216 | } | |
217 | ||
218 | void elevator_exit(elevator_t *e) | |
219 | { | |
220 | if (e->ops->elevator_exit_fn) | |
221 | e->ops->elevator_exit_fn(e); | |
222 | ||
223 | elevator_put(e->elevator_type); | |
224 | e->elevator_type = NULL; | |
225 | kfree(e); | |
226 | } | |
227 | ||
1da177e4 LT |
228 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
229 | { | |
230 | elevator_t *e = q->elevator; | |
231 | ||
232 | if (e->ops->elevator_merge_fn) | |
233 | return e->ops->elevator_merge_fn(q, req, bio); | |
234 | ||
235 | return ELEVATOR_NO_MERGE; | |
236 | } | |
237 | ||
238 | void elv_merged_request(request_queue_t *q, struct request *rq) | |
239 | { | |
240 | elevator_t *e = q->elevator; | |
241 | ||
242 | if (e->ops->elevator_merged_fn) | |
243 | e->ops->elevator_merged_fn(q, rq); | |
244 | } | |
245 | ||
246 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
247 | struct request *next) | |
248 | { | |
249 | elevator_t *e = q->elevator; | |
250 | ||
251 | if (q->last_merge == next) | |
252 | q->last_merge = NULL; | |
253 | ||
254 | if (e->ops->elevator_merge_req_fn) | |
255 | e->ops->elevator_merge_req_fn(q, rq, next); | |
256 | } | |
257 | ||
258 | /* | |
259 | * For careful internal use by the block layer. Essentially the same as | |
260 | * a requeue in that it tells the io scheduler that this request is not | |
261 | * active in the driver or hardware anymore, but we don't want the request | |
262 | * added back to the scheduler. Function is not exported. | |
263 | */ | |
264 | void elv_deactivate_request(request_queue_t *q, struct request *rq) | |
265 | { | |
266 | elevator_t *e = q->elevator; | |
267 | ||
268 | /* | |
269 | * it already went through dequeue, we need to decrement the | |
270 | * in_flight count again | |
271 | */ | |
272 | if (blk_account_rq(rq)) | |
273 | q->in_flight--; | |
274 | ||
275 | rq->flags &= ~REQ_STARTED; | |
276 | ||
277 | if (e->ops->elevator_deactivate_req_fn) | |
278 | e->ops->elevator_deactivate_req_fn(q, rq); | |
279 | } | |
280 | ||
281 | void elv_requeue_request(request_queue_t *q, struct request *rq) | |
282 | { | |
283 | elv_deactivate_request(q, rq); | |
284 | ||
285 | /* | |
286 | * if this is the flush, requeue the original instead and drop the flush | |
287 | */ | |
288 | if (rq->flags & REQ_BAR_FLUSH) { | |
289 | clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); | |
290 | rq = rq->end_io_data; | |
291 | } | |
292 | ||
2e759cd4 TH |
293 | /* |
294 | * the request is prepped and may have some resources allocated. | |
295 | * allowing unprepped requests to pass this one may cause resource | |
296 | * deadlock. turn on softbarrier. | |
297 | */ | |
298 | rq->flags |= REQ_SOFTBARRIER; | |
299 | ||
1da177e4 LT |
300 | /* |
301 | * if iosched has an explicit requeue hook, then use that. otherwise | |
302 | * just put the request at the front of the queue | |
303 | */ | |
304 | if (q->elevator->ops->elevator_requeue_req_fn) | |
305 | q->elevator->ops->elevator_requeue_req_fn(q, rq); | |
306 | else | |
307 | __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0); | |
308 | } | |
309 | ||
310 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, | |
311 | int plug) | |
312 | { | |
313 | /* | |
314 | * barriers implicitly indicate back insertion | |
315 | */ | |
316 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER) && | |
317 | where == ELEVATOR_INSERT_SORT) | |
318 | where = ELEVATOR_INSERT_BACK; | |
319 | ||
320 | if (plug) | |
321 | blk_plug_device(q); | |
322 | ||
323 | rq->q = q; | |
324 | ||
325 | if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) { | |
326 | q->elevator->ops->elevator_add_req_fn(q, rq, where); | |
327 | ||
328 | if (blk_queue_plugged(q)) { | |
329 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] | |
330 | - q->in_flight; | |
331 | ||
c374f127 | 332 | if (nrq >= q->unplug_thresh) |
1da177e4 LT |
333 | __generic_unplug_device(q); |
334 | } | |
335 | } else | |
336 | /* | |
337 | * if drain is set, store the request "locally". when the drain | |
338 | * is finished, the requests will be handed ordered to the io | |
339 | * scheduler | |
340 | */ | |
341 | list_add_tail(&rq->queuelist, &q->drain_list); | |
342 | } | |
343 | ||
344 | void elv_add_request(request_queue_t *q, struct request *rq, int where, | |
345 | int plug) | |
346 | { | |
347 | unsigned long flags; | |
348 | ||
349 | spin_lock_irqsave(q->queue_lock, flags); | |
350 | __elv_add_request(q, rq, where, plug); | |
351 | spin_unlock_irqrestore(q->queue_lock, flags); | |
352 | } | |
353 | ||
354 | static inline struct request *__elv_next_request(request_queue_t *q) | |
355 | { | |
356 | struct request *rq = q->elevator->ops->elevator_next_req_fn(q); | |
357 | ||
358 | /* | |
359 | * if this is a barrier write and the device has to issue a | |
360 | * flush sequence to support it, check how far we are | |
361 | */ | |
362 | if (rq && blk_fs_request(rq) && blk_barrier_rq(rq)) { | |
363 | BUG_ON(q->ordered == QUEUE_ORDERED_NONE); | |
364 | ||
365 | if (q->ordered == QUEUE_ORDERED_FLUSH && | |
366 | !blk_barrier_preflush(rq)) | |
367 | rq = blk_start_pre_flush(q, rq); | |
368 | } | |
369 | ||
370 | return rq; | |
371 | } | |
372 | ||
373 | struct request *elv_next_request(request_queue_t *q) | |
374 | { | |
375 | struct request *rq; | |
376 | int ret; | |
377 | ||
378 | while ((rq = __elv_next_request(q)) != NULL) { | |
379 | /* | |
380 | * just mark as started even if we don't start it, a request | |
381 | * that has been delayed should not be passed by new incoming | |
382 | * requests | |
383 | */ | |
384 | rq->flags |= REQ_STARTED; | |
385 | ||
386 | if (rq == q->last_merge) | |
387 | q->last_merge = NULL; | |
388 | ||
389 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) | |
390 | break; | |
391 | ||
392 | ret = q->prep_rq_fn(q, rq); | |
393 | if (ret == BLKPREP_OK) { | |
394 | break; | |
395 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
396 | /* |
397 | * the request may have been (partially) prepped. | |
398 | * we need to keep this request in the front to | |
399 | * avoid resource deadlock. turn on softbarrier. | |
400 | */ | |
401 | rq->flags |= REQ_SOFTBARRIER; | |
1da177e4 LT |
402 | rq = NULL; |
403 | break; | |
404 | } else if (ret == BLKPREP_KILL) { | |
405 | int nr_bytes = rq->hard_nr_sectors << 9; | |
406 | ||
407 | if (!nr_bytes) | |
408 | nr_bytes = rq->data_len; | |
409 | ||
410 | blkdev_dequeue_request(rq); | |
411 | rq->flags |= REQ_QUIET; | |
412 | end_that_request_chunk(rq, 0, nr_bytes); | |
413 | end_that_request_last(rq); | |
414 | } else { | |
415 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
416 | ret); | |
417 | break; | |
418 | } | |
419 | } | |
420 | ||
421 | return rq; | |
422 | } | |
423 | ||
424 | void elv_remove_request(request_queue_t *q, struct request *rq) | |
425 | { | |
426 | elevator_t *e = q->elevator; | |
427 | ||
428 | /* | |
429 | * the time frame between a request being removed from the lists | |
430 | * and to it is freed is accounted as io that is in progress at | |
431 | * the driver side. note that we only account requests that the | |
432 | * driver has seen (REQ_STARTED set), to avoid false accounting | |
433 | * for request-request merges | |
434 | */ | |
435 | if (blk_account_rq(rq)) | |
436 | q->in_flight++; | |
437 | ||
438 | /* | |
439 | * the main clearing point for q->last_merge is on retrieval of | |
440 | * request by driver (it calls elv_next_request()), but it _can_ | |
441 | * also happen here if a request is added to the queue but later | |
442 | * deleted without ever being given to driver (merged with another | |
443 | * request). | |
444 | */ | |
445 | if (rq == q->last_merge) | |
446 | q->last_merge = NULL; | |
447 | ||
448 | if (e->ops->elevator_remove_req_fn) | |
449 | e->ops->elevator_remove_req_fn(q, rq); | |
450 | } | |
451 | ||
452 | int elv_queue_empty(request_queue_t *q) | |
453 | { | |
454 | elevator_t *e = q->elevator; | |
455 | ||
456 | if (e->ops->elevator_queue_empty_fn) | |
457 | return e->ops->elevator_queue_empty_fn(q); | |
458 | ||
459 | return list_empty(&q->queue_head); | |
460 | } | |
461 | ||
462 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) | |
463 | { | |
464 | struct list_head *next; | |
465 | ||
466 | elevator_t *e = q->elevator; | |
467 | ||
468 | if (e->ops->elevator_latter_req_fn) | |
469 | return e->ops->elevator_latter_req_fn(q, rq); | |
470 | ||
471 | next = rq->queuelist.next; | |
472 | if (next != &q->queue_head && next != &rq->queuelist) | |
473 | return list_entry_rq(next); | |
474 | ||
475 | return NULL; | |
476 | } | |
477 | ||
478 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
479 | { | |
480 | struct list_head *prev; | |
481 | ||
482 | elevator_t *e = q->elevator; | |
483 | ||
484 | if (e->ops->elevator_former_req_fn) | |
485 | return e->ops->elevator_former_req_fn(q, rq); | |
486 | ||
487 | prev = rq->queuelist.prev; | |
488 | if (prev != &q->queue_head && prev != &rq->queuelist) | |
489 | return list_entry_rq(prev); | |
490 | ||
491 | return NULL; | |
492 | } | |
493 | ||
22e2c507 JA |
494 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
495 | int gfp_mask) | |
1da177e4 LT |
496 | { |
497 | elevator_t *e = q->elevator; | |
498 | ||
499 | if (e->ops->elevator_set_req_fn) | |
22e2c507 | 500 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
501 | |
502 | rq->elevator_private = NULL; | |
503 | return 0; | |
504 | } | |
505 | ||
506 | void elv_put_request(request_queue_t *q, struct request *rq) | |
507 | { | |
508 | elevator_t *e = q->elevator; | |
509 | ||
510 | if (e->ops->elevator_put_req_fn) | |
511 | e->ops->elevator_put_req_fn(q, rq); | |
512 | } | |
513 | ||
22e2c507 | 514 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
515 | { |
516 | elevator_t *e = q->elevator; | |
517 | ||
518 | if (e->ops->elevator_may_queue_fn) | |
22e2c507 | 519 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
1da177e4 LT |
520 | |
521 | return ELV_MQUEUE_MAY; | |
522 | } | |
523 | ||
524 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
525 | { | |
526 | elevator_t *e = q->elevator; | |
527 | ||
528 | /* | |
529 | * request is released from the driver, io must be done | |
530 | */ | |
531 | if (blk_account_rq(rq)) | |
532 | q->in_flight--; | |
533 | ||
534 | if (e->ops->elevator_completed_req_fn) | |
535 | e->ops->elevator_completed_req_fn(q, rq); | |
536 | } | |
537 | ||
538 | int elv_register_queue(struct request_queue *q) | |
539 | { | |
540 | elevator_t *e = q->elevator; | |
541 | ||
542 | e->kobj.parent = kobject_get(&q->kobj); | |
543 | if (!e->kobj.parent) | |
544 | return -EBUSY; | |
545 | ||
546 | snprintf(e->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
547 | e->kobj.ktype = e->elevator_type->elevator_ktype; | |
548 | ||
549 | return kobject_register(&e->kobj); | |
550 | } | |
551 | ||
552 | void elv_unregister_queue(struct request_queue *q) | |
553 | { | |
554 | if (q) { | |
555 | elevator_t *e = q->elevator; | |
556 | kobject_unregister(&e->kobj); | |
557 | kobject_put(&q->kobj); | |
558 | } | |
559 | } | |
560 | ||
561 | int elv_register(struct elevator_type *e) | |
562 | { | |
2824bc93 | 563 | spin_lock_irq(&elv_list_lock); |
1da177e4 LT |
564 | if (elevator_find(e->elevator_name)) |
565 | BUG(); | |
1da177e4 LT |
566 | list_add_tail(&e->list, &elv_list); |
567 | spin_unlock_irq(&elv_list_lock); | |
568 | ||
569 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
570 | if (!strcmp(e->elevator_name, chosen_elevator)) | |
571 | printk(" (default)"); | |
572 | printk("\n"); | |
573 | return 0; | |
574 | } | |
575 | EXPORT_SYMBOL_GPL(elv_register); | |
576 | ||
577 | void elv_unregister(struct elevator_type *e) | |
578 | { | |
579 | spin_lock_irq(&elv_list_lock); | |
580 | list_del_init(&e->list); | |
581 | spin_unlock_irq(&elv_list_lock); | |
582 | } | |
583 | EXPORT_SYMBOL_GPL(elv_unregister); | |
584 | ||
585 | /* | |
586 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
587 | * we don't free the old io scheduler, before we have allocated what we | |
588 | * need for the new one. this way we have a chance of going back to the old | |
589 | * one, if the new one fails init for some reason. we also do an intermediate | |
590 | * switch to noop to ensure safety with stack-allocated requests, since they | |
591 | * don't originate from the block layer allocator. noop is safe here, because | |
592 | * it never needs to touch the elevator itself for completion events. DRAIN | |
593 | * flags will make sure we don't touch it for additions either. | |
594 | */ | |
595 | static void elevator_switch(request_queue_t *q, struct elevator_type *new_e) | |
596 | { | |
597 | elevator_t *e = kmalloc(sizeof(elevator_t), GFP_KERNEL); | |
598 | struct elevator_type *noop_elevator = NULL; | |
599 | elevator_t *old_elevator; | |
600 | ||
601 | if (!e) | |
602 | goto error; | |
603 | ||
604 | /* | |
605 | * first step, drain requests from the block freelist | |
606 | */ | |
607 | blk_wait_queue_drained(q, 0); | |
608 | ||
609 | /* | |
610 | * unregister old elevator data | |
611 | */ | |
612 | elv_unregister_queue(q); | |
613 | old_elevator = q->elevator; | |
614 | ||
615 | /* | |
616 | * next step, switch to noop since it uses no private rq structures | |
617 | * and doesn't allocate any memory for anything. then wait for any | |
618 | * non-fs requests in-flight | |
619 | */ | |
620 | noop_elevator = elevator_get("noop"); | |
621 | spin_lock_irq(q->queue_lock); | |
622 | elevator_attach(q, noop_elevator, e); | |
623 | spin_unlock_irq(q->queue_lock); | |
624 | ||
625 | blk_wait_queue_drained(q, 1); | |
626 | ||
627 | /* | |
628 | * attach and start new elevator | |
629 | */ | |
630 | if (elevator_attach(q, new_e, e)) | |
631 | goto fail; | |
632 | ||
633 | if (elv_register_queue(q)) | |
634 | goto fail_register; | |
635 | ||
636 | /* | |
637 | * finally exit old elevator and start queue again | |
638 | */ | |
639 | elevator_exit(old_elevator); | |
640 | blk_finish_queue_drain(q); | |
641 | elevator_put(noop_elevator); | |
642 | return; | |
643 | ||
644 | fail_register: | |
645 | /* | |
646 | * switch failed, exit the new io scheduler and reattach the old | |
647 | * one again (along with re-adding the sysfs dir) | |
648 | */ | |
649 | elevator_exit(e); | |
650 | fail: | |
651 | q->elevator = old_elevator; | |
652 | elv_register_queue(q); | |
653 | blk_finish_queue_drain(q); | |
654 | error: | |
655 | if (noop_elevator) | |
656 | elevator_put(noop_elevator); | |
657 | elevator_put(new_e); | |
658 | printk(KERN_ERR "elevator: switch to %s failed\n",new_e->elevator_name); | |
659 | } | |
660 | ||
661 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
662 | { | |
663 | char elevator_name[ELV_NAME_MAX]; | |
664 | struct elevator_type *e; | |
665 | ||
666 | memset(elevator_name, 0, sizeof(elevator_name)); | |
667 | strncpy(elevator_name, name, sizeof(elevator_name)); | |
668 | ||
669 | if (elevator_name[strlen(elevator_name) - 1] == '\n') | |
670 | elevator_name[strlen(elevator_name) - 1] = '\0'; | |
671 | ||
672 | e = elevator_get(elevator_name); | |
673 | if (!e) { | |
674 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
675 | return -EINVAL; | |
676 | } | |
677 | ||
678 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) | |
679 | return count; | |
680 | ||
681 | elevator_switch(q, e); | |
682 | return count; | |
683 | } | |
684 | ||
685 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
686 | { | |
687 | elevator_t *e = q->elevator; | |
688 | struct elevator_type *elv = e->elevator_type; | |
689 | struct list_head *entry; | |
690 | int len = 0; | |
691 | ||
692 | spin_lock_irq(q->queue_lock); | |
693 | list_for_each(entry, &elv_list) { | |
694 | struct elevator_type *__e; | |
695 | ||
696 | __e = list_entry(entry, struct elevator_type, list); | |
697 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
698 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
699 | else | |
700 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
701 | } | |
702 | spin_unlock_irq(q->queue_lock); | |
703 | ||
704 | len += sprintf(len+name, "\n"); | |
705 | return len; | |
706 | } | |
707 | ||
1da177e4 LT |
708 | EXPORT_SYMBOL(elv_add_request); |
709 | EXPORT_SYMBOL(__elv_add_request); | |
710 | EXPORT_SYMBOL(elv_requeue_request); | |
711 | EXPORT_SYMBOL(elv_next_request); | |
712 | EXPORT_SYMBOL(elv_remove_request); | |
713 | EXPORT_SYMBOL(elv_queue_empty); | |
714 | EXPORT_SYMBOL(elv_completed_request); | |
715 | EXPORT_SYMBOL(elevator_exit); | |
716 | EXPORT_SYMBOL(elevator_init); |