Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Block device elevator/IO-scheduler. |
3 | * | |
4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * | |
6 | * 30042000 Jens Axboe <axboe@suse.de> : | |
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/config.h> | |
31 | #include <linux/module.h> | |
32 | #include <linux/slab.h> | |
33 | #include <linux/init.h> | |
34 | #include <linux/compiler.h> | |
cb98fc8b | 35 | #include <linux/delay.h> |
1da177e4 LT |
36 | |
37 | #include <asm/uaccess.h> | |
38 | ||
39 | static DEFINE_SPINLOCK(elv_list_lock); | |
40 | static LIST_HEAD(elv_list); | |
41 | ||
42 | /* | |
43 | * can we safely merge with this request? | |
44 | */ | |
45 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) | |
46 | { | |
47 | if (!rq_mergeable(rq)) | |
48 | return 0; | |
49 | ||
50 | /* | |
51 | * different data direction or already started, don't merge | |
52 | */ | |
53 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
54 | return 0; | |
55 | ||
56 | /* | |
57 | * same device and no special stuff set, merge is ok | |
58 | */ | |
59 | if (rq->rq_disk == bio->bi_bdev->bd_disk && | |
60 | !rq->waiting && !rq->special) | |
61 | return 1; | |
62 | ||
63 | return 0; | |
64 | } | |
65 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
66 | ||
769db45b | 67 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
68 | { |
69 | int ret = ELEVATOR_NO_MERGE; | |
70 | ||
71 | /* | |
72 | * we can merge and sequence is ok, check if it's possible | |
73 | */ | |
74 | if (elv_rq_merge_ok(__rq, bio)) { | |
75 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
76 | ret = ELEVATOR_BACK_MERGE; | |
77 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
78 | ret = ELEVATOR_FRONT_MERGE; | |
79 | } | |
80 | ||
81 | return ret; | |
82 | } | |
1da177e4 | 83 | |
1da177e4 LT |
84 | static struct elevator_type *elevator_find(const char *name) |
85 | { | |
86 | struct elevator_type *e = NULL; | |
87 | struct list_head *entry; | |
88 | ||
1da177e4 LT |
89 | list_for_each(entry, &elv_list) { |
90 | struct elevator_type *__e; | |
91 | ||
92 | __e = list_entry(entry, struct elevator_type, list); | |
93 | ||
94 | if (!strcmp(__e->elevator_name, name)) { | |
95 | e = __e; | |
96 | break; | |
97 | } | |
98 | } | |
1da177e4 LT |
99 | |
100 | return e; | |
101 | } | |
102 | ||
103 | static void elevator_put(struct elevator_type *e) | |
104 | { | |
105 | module_put(e->elevator_owner); | |
106 | } | |
107 | ||
108 | static struct elevator_type *elevator_get(const char *name) | |
109 | { | |
2824bc93 | 110 | struct elevator_type *e; |
1da177e4 | 111 | |
2824bc93 TH |
112 | spin_lock_irq(&elv_list_lock); |
113 | ||
114 | e = elevator_find(name); | |
115 | if (e && !try_module_get(e->elevator_owner)) | |
116 | e = NULL; | |
117 | ||
118 | spin_unlock_irq(&elv_list_lock); | |
1da177e4 LT |
119 | |
120 | return e; | |
121 | } | |
122 | ||
3d1ab40f | 123 | static int elevator_attach(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 LT |
124 | { |
125 | int ret = 0; | |
126 | ||
1da177e4 LT |
127 | q->elevator = eq; |
128 | ||
129 | if (eq->ops->elevator_init_fn) | |
130 | ret = eq->ops->elevator_init_fn(q, eq); | |
131 | ||
132 | return ret; | |
133 | } | |
134 | ||
135 | static char chosen_elevator[16]; | |
136 | ||
5f003976 | 137 | static int __init elevator_setup(char *str) |
1da177e4 | 138 | { |
752a3b79 CE |
139 | /* |
140 | * Be backwards-compatible with previous kernels, so users | |
141 | * won't get the wrong elevator. | |
142 | */ | |
5f003976 | 143 | if (!strcmp(str, "as")) |
752a3b79 | 144 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 145 | else |
5f003976 | 146 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
1da177e4 LT |
147 | return 0; |
148 | } | |
149 | ||
150 | __setup("elevator=", elevator_setup); | |
151 | ||
3d1ab40f AV |
152 | static struct kobj_type elv_ktype; |
153 | ||
154 | static elevator_t *elevator_alloc(struct elevator_type *e) | |
155 | { | |
156 | elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL); | |
157 | if (eq) { | |
158 | memset(eq, 0, sizeof(*eq)); | |
159 | eq->ops = &e->ops; | |
160 | eq->elevator_type = e; | |
161 | kobject_init(&eq->kobj); | |
162 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
163 | eq->kobj.ktype = &elv_ktype; | |
164 | mutex_init(&eq->sysfs_lock); | |
165 | } else { | |
166 | elevator_put(e); | |
167 | } | |
168 | return eq; | |
169 | } | |
170 | ||
171 | static void elevator_release(struct kobject *kobj) | |
172 | { | |
173 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
174 | elevator_put(e->elevator_type); | |
175 | kfree(e); | |
176 | } | |
177 | ||
1da177e4 LT |
178 | int elevator_init(request_queue_t *q, char *name) |
179 | { | |
180 | struct elevator_type *e = NULL; | |
181 | struct elevator_queue *eq; | |
182 | int ret = 0; | |
183 | ||
cb98fc8b TH |
184 | INIT_LIST_HEAD(&q->queue_head); |
185 | q->last_merge = NULL; | |
186 | q->end_sector = 0; | |
187 | q->boundary_rq = NULL; | |
cb98fc8b | 188 | |
5f003976 | 189 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
190 | return -EINVAL; |
191 | ||
248d5ca5 ND |
192 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
193 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
194 | ||
195 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
196 | printk("Default I/O scheduler not found, using no-op\n"); | |
197 | e = elevator_get("noop"); | |
5f003976 ND |
198 | } |
199 | ||
3d1ab40f AV |
200 | eq = elevator_alloc(e); |
201 | if (!eq) | |
1da177e4 | 202 | return -ENOMEM; |
1da177e4 | 203 | |
3d1ab40f AV |
204 | ret = elevator_attach(q, eq); |
205 | if (ret) | |
206 | kobject_put(&eq->kobj); | |
1da177e4 LT |
207 | |
208 | return ret; | |
209 | } | |
210 | ||
211 | void elevator_exit(elevator_t *e) | |
212 | { | |
3d1ab40f | 213 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
214 | if (e->ops->elevator_exit_fn) |
215 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
216 | e->ops = NULL; |
217 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 218 | |
3d1ab40f | 219 | kobject_put(&e->kobj); |
1da177e4 LT |
220 | } |
221 | ||
8922e16c TH |
222 | /* |
223 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
224 | * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be | |
225 | * appended to the dispatch queue. To be used by specific elevators. | |
226 | */ | |
1b47f531 | 227 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
228 | { |
229 | sector_t boundary; | |
8922e16c TH |
230 | struct list_head *entry; |
231 | ||
06b86245 TH |
232 | if (q->last_merge == rq) |
233 | q->last_merge = NULL; | |
15853af9 | 234 | q->nr_sorted--; |
06b86245 | 235 | |
1b47f531 | 236 | boundary = q->end_sector; |
cb19833d | 237 | |
8922e16c TH |
238 | list_for_each_prev(entry, &q->queue_head) { |
239 | struct request *pos = list_entry_rq(entry); | |
240 | ||
241 | if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) | |
242 | break; | |
243 | if (rq->sector >= boundary) { | |
244 | if (pos->sector < boundary) | |
245 | continue; | |
246 | } else { | |
247 | if (pos->sector >= boundary) | |
248 | break; | |
249 | } | |
250 | if (rq->sector >= pos->sector) | |
251 | break; | |
252 | } | |
253 | ||
254 | list_add(&rq->queuelist, entry); | |
255 | } | |
256 | ||
1da177e4 LT |
257 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
258 | { | |
259 | elevator_t *e = q->elevator; | |
06b86245 TH |
260 | int ret; |
261 | ||
262 | if (q->last_merge) { | |
263 | ret = elv_try_merge(q->last_merge, bio); | |
264 | if (ret != ELEVATOR_NO_MERGE) { | |
265 | *req = q->last_merge; | |
266 | return ret; | |
267 | } | |
268 | } | |
1da177e4 LT |
269 | |
270 | if (e->ops->elevator_merge_fn) | |
271 | return e->ops->elevator_merge_fn(q, req, bio); | |
272 | ||
273 | return ELEVATOR_NO_MERGE; | |
274 | } | |
275 | ||
276 | void elv_merged_request(request_queue_t *q, struct request *rq) | |
277 | { | |
278 | elevator_t *e = q->elevator; | |
279 | ||
280 | if (e->ops->elevator_merged_fn) | |
281 | e->ops->elevator_merged_fn(q, rq); | |
06b86245 TH |
282 | |
283 | q->last_merge = rq; | |
1da177e4 LT |
284 | } |
285 | ||
286 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
287 | struct request *next) | |
288 | { | |
289 | elevator_t *e = q->elevator; | |
290 | ||
1da177e4 LT |
291 | if (e->ops->elevator_merge_req_fn) |
292 | e->ops->elevator_merge_req_fn(q, rq, next); | |
15853af9 | 293 | q->nr_sorted--; |
06b86245 TH |
294 | |
295 | q->last_merge = rq; | |
1da177e4 LT |
296 | } |
297 | ||
8922e16c | 298 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 LT |
299 | { |
300 | elevator_t *e = q->elevator; | |
301 | ||
302 | /* | |
303 | * it already went through dequeue, we need to decrement the | |
304 | * in_flight count again | |
305 | */ | |
8922e16c | 306 | if (blk_account_rq(rq)) { |
1da177e4 | 307 | q->in_flight--; |
8922e16c TH |
308 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
309 | e->ops->elevator_deactivate_req_fn(q, rq); | |
310 | } | |
1da177e4 LT |
311 | |
312 | rq->flags &= ~REQ_STARTED; | |
313 | ||
30e9656c | 314 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
315 | } |
316 | ||
15853af9 TH |
317 | static void elv_drain_elevator(request_queue_t *q) |
318 | { | |
319 | static int printed; | |
320 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
321 | ; | |
322 | if (q->nr_sorted == 0) | |
323 | return; | |
324 | if (printed++ < 10) { | |
325 | printk(KERN_ERR "%s: forced dispatching is broken " | |
326 | "(nr_sorted=%u), please report this\n", | |
327 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
328 | } | |
329 | } | |
330 | ||
30e9656c | 331 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 332 | { |
797e7dbb TH |
333 | struct list_head *pos; |
334 | unsigned ordseq; | |
335 | ||
1da177e4 LT |
336 | rq->q = q; |
337 | ||
8922e16c TH |
338 | switch (where) { |
339 | case ELEVATOR_INSERT_FRONT: | |
340 | rq->flags |= REQ_SOFTBARRIER; | |
341 | ||
342 | list_add(&rq->queuelist, &q->queue_head); | |
343 | break; | |
344 | ||
345 | case ELEVATOR_INSERT_BACK: | |
346 | rq->flags |= REQ_SOFTBARRIER; | |
15853af9 | 347 | elv_drain_elevator(q); |
8922e16c TH |
348 | list_add_tail(&rq->queuelist, &q->queue_head); |
349 | /* | |
350 | * We kick the queue here for the following reasons. | |
351 | * - The elevator might have returned NULL previously | |
352 | * to delay requests and returned them now. As the | |
353 | * queue wasn't empty before this request, ll_rw_blk | |
354 | * won't run the queue on return, resulting in hang. | |
355 | * - Usually, back inserted requests won't be merged | |
356 | * with anything. There's no point in delaying queue | |
357 | * processing. | |
358 | */ | |
359 | blk_remove_plug(q); | |
360 | q->request_fn(q); | |
361 | break; | |
362 | ||
363 | case ELEVATOR_INSERT_SORT: | |
364 | BUG_ON(!blk_fs_request(rq)); | |
365 | rq->flags |= REQ_SORTED; | |
15853af9 | 366 | q->nr_sorted++; |
06b86245 TH |
367 | if (q->last_merge == NULL && rq_mergeable(rq)) |
368 | q->last_merge = rq; | |
ca23509f TH |
369 | /* |
370 | * Some ioscheds (cfq) run q->request_fn directly, so | |
371 | * rq cannot be accessed after calling | |
372 | * elevator_add_req_fn. | |
373 | */ | |
374 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
375 | break; |
376 | ||
797e7dbb TH |
377 | case ELEVATOR_INSERT_REQUEUE: |
378 | /* | |
379 | * If ordered flush isn't in progress, we do front | |
380 | * insertion; otherwise, requests should be requeued | |
381 | * in ordseq order. | |
382 | */ | |
383 | rq->flags |= REQ_SOFTBARRIER; | |
384 | ||
385 | if (q->ordseq == 0) { | |
386 | list_add(&rq->queuelist, &q->queue_head); | |
387 | break; | |
388 | } | |
389 | ||
390 | ordseq = blk_ordered_req_seq(rq); | |
391 | ||
392 | list_for_each(pos, &q->queue_head) { | |
393 | struct request *pos_rq = list_entry_rq(pos); | |
394 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
395 | break; | |
396 | } | |
397 | ||
398 | list_add_tail(&rq->queuelist, pos); | |
399 | break; | |
400 | ||
8922e16c TH |
401 | default: |
402 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
403 | __FUNCTION__, where); | |
404 | BUG(); | |
405 | } | |
406 | ||
407 | if (blk_queue_plugged(q)) { | |
408 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] | |
409 | - q->in_flight; | |
410 | ||
411 | if (nrq >= q->unplug_thresh) | |
412 | __generic_unplug_device(q); | |
413 | } | |
1da177e4 LT |
414 | } |
415 | ||
30e9656c TH |
416 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
417 | int plug) | |
418 | { | |
419 | if (q->ordcolor) | |
420 | rq->flags |= REQ_ORDERED_COLOR; | |
421 | ||
422 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { | |
423 | /* | |
424 | * toggle ordered color | |
425 | */ | |
426 | if (blk_barrier_rq(rq)) | |
427 | q->ordcolor ^= 1; | |
428 | ||
429 | /* | |
430 | * barriers implicitly indicate back insertion | |
431 | */ | |
432 | if (where == ELEVATOR_INSERT_SORT) | |
433 | where = ELEVATOR_INSERT_BACK; | |
434 | ||
435 | /* | |
436 | * this request is scheduling boundary, update | |
437 | * end_sector | |
438 | */ | |
439 | if (blk_fs_request(rq)) { | |
440 | q->end_sector = rq_end_sector(rq); | |
441 | q->boundary_rq = rq; | |
442 | } | |
443 | } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) | |
444 | where = ELEVATOR_INSERT_BACK; | |
445 | ||
446 | if (plug) | |
447 | blk_plug_device(q); | |
448 | ||
449 | elv_insert(q, rq, where); | |
450 | } | |
451 | ||
1da177e4 LT |
452 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
453 | int plug) | |
454 | { | |
455 | unsigned long flags; | |
456 | ||
457 | spin_lock_irqsave(q->queue_lock, flags); | |
458 | __elv_add_request(q, rq, where, plug); | |
459 | spin_unlock_irqrestore(q->queue_lock, flags); | |
460 | } | |
461 | ||
462 | static inline struct request *__elv_next_request(request_queue_t *q) | |
463 | { | |
8922e16c TH |
464 | struct request *rq; |
465 | ||
797e7dbb TH |
466 | while (1) { |
467 | while (!list_empty(&q->queue_head)) { | |
468 | rq = list_entry_rq(q->queue_head.next); | |
469 | if (blk_do_ordered(q, &rq)) | |
470 | return rq; | |
471 | } | |
1da177e4 | 472 | |
797e7dbb TH |
473 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
474 | return NULL; | |
1da177e4 | 475 | } |
1da177e4 LT |
476 | } |
477 | ||
478 | struct request *elv_next_request(request_queue_t *q) | |
479 | { | |
480 | struct request *rq; | |
481 | int ret; | |
482 | ||
483 | while ((rq = __elv_next_request(q)) != NULL) { | |
8922e16c TH |
484 | if (!(rq->flags & REQ_STARTED)) { |
485 | elevator_t *e = q->elevator; | |
486 | ||
487 | /* | |
488 | * This is the first time the device driver | |
489 | * sees this request (possibly after | |
490 | * requeueing). Notify IO scheduler. | |
491 | */ | |
492 | if (blk_sorted_rq(rq) && | |
493 | e->ops->elevator_activate_req_fn) | |
494 | e->ops->elevator_activate_req_fn(q, rq); | |
1da177e4 | 495 | |
8922e16c TH |
496 | /* |
497 | * just mark as started even if we don't start | |
498 | * it, a request that has been delayed should | |
499 | * not be passed by new incoming requests | |
500 | */ | |
501 | rq->flags |= REQ_STARTED; | |
502 | } | |
1da177e4 | 503 | |
8922e16c | 504 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 505 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
506 | q->boundary_rq = NULL; |
507 | } | |
1da177e4 LT |
508 | |
509 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) | |
510 | break; | |
511 | ||
512 | ret = q->prep_rq_fn(q, rq); | |
513 | if (ret == BLKPREP_OK) { | |
514 | break; | |
515 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
516 | /* |
517 | * the request may have been (partially) prepped. | |
518 | * we need to keep this request in the front to | |
8922e16c TH |
519 | * avoid resource deadlock. REQ_STARTED will |
520 | * prevent other fs requests from passing this one. | |
2e759cd4 | 521 | */ |
1da177e4 LT |
522 | rq = NULL; |
523 | break; | |
524 | } else if (ret == BLKPREP_KILL) { | |
525 | int nr_bytes = rq->hard_nr_sectors << 9; | |
526 | ||
527 | if (!nr_bytes) | |
528 | nr_bytes = rq->data_len; | |
529 | ||
530 | blkdev_dequeue_request(rq); | |
531 | rq->flags |= REQ_QUIET; | |
532 | end_that_request_chunk(rq, 0, nr_bytes); | |
8ffdc655 | 533 | end_that_request_last(rq, 0); |
1da177e4 LT |
534 | } else { |
535 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
536 | ret); | |
537 | break; | |
538 | } | |
539 | } | |
540 | ||
541 | return rq; | |
542 | } | |
543 | ||
8922e16c | 544 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 545 | { |
8922e16c TH |
546 | BUG_ON(list_empty(&rq->queuelist)); |
547 | ||
548 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
549 | |
550 | /* | |
551 | * the time frame between a request being removed from the lists | |
552 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 553 | * the driver side. |
1da177e4 LT |
554 | */ |
555 | if (blk_account_rq(rq)) | |
556 | q->in_flight++; | |
1da177e4 LT |
557 | } |
558 | ||
559 | int elv_queue_empty(request_queue_t *q) | |
560 | { | |
561 | elevator_t *e = q->elevator; | |
562 | ||
8922e16c TH |
563 | if (!list_empty(&q->queue_head)) |
564 | return 0; | |
565 | ||
1da177e4 LT |
566 | if (e->ops->elevator_queue_empty_fn) |
567 | return e->ops->elevator_queue_empty_fn(q); | |
568 | ||
8922e16c | 569 | return 1; |
1da177e4 LT |
570 | } |
571 | ||
572 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) | |
573 | { | |
1da177e4 LT |
574 | elevator_t *e = q->elevator; |
575 | ||
576 | if (e->ops->elevator_latter_req_fn) | |
577 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
578 | return NULL; |
579 | } | |
580 | ||
581 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
582 | { | |
1da177e4 LT |
583 | elevator_t *e = q->elevator; |
584 | ||
585 | if (e->ops->elevator_former_req_fn) | |
586 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
587 | return NULL; |
588 | } | |
589 | ||
22e2c507 | 590 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
8267e268 | 591 | gfp_t gfp_mask) |
1da177e4 LT |
592 | { |
593 | elevator_t *e = q->elevator; | |
594 | ||
595 | if (e->ops->elevator_set_req_fn) | |
22e2c507 | 596 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
597 | |
598 | rq->elevator_private = NULL; | |
599 | return 0; | |
600 | } | |
601 | ||
602 | void elv_put_request(request_queue_t *q, struct request *rq) | |
603 | { | |
604 | elevator_t *e = q->elevator; | |
605 | ||
606 | if (e->ops->elevator_put_req_fn) | |
607 | e->ops->elevator_put_req_fn(q, rq); | |
608 | } | |
609 | ||
22e2c507 | 610 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
611 | { |
612 | elevator_t *e = q->elevator; | |
613 | ||
614 | if (e->ops->elevator_may_queue_fn) | |
22e2c507 | 615 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
1da177e4 LT |
616 | |
617 | return ELV_MQUEUE_MAY; | |
618 | } | |
619 | ||
620 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
621 | { | |
622 | elevator_t *e = q->elevator; | |
623 | ||
624 | /* | |
625 | * request is released from the driver, io must be done | |
626 | */ | |
8922e16c | 627 | if (blk_account_rq(rq)) { |
1da177e4 | 628 | q->in_flight--; |
1bc691d3 TH |
629 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
630 | e->ops->elevator_completed_req_fn(q, rq); | |
631 | } | |
797e7dbb | 632 | |
1bc691d3 TH |
633 | /* |
634 | * Check if the queue is waiting for fs requests to be | |
635 | * drained for flush sequence. | |
636 | */ | |
637 | if (unlikely(q->ordseq)) { | |
638 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
639 | if (q->in_flight == 0 && | |
797e7dbb TH |
640 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
641 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
642 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
643 | q->request_fn(q); | |
644 | } | |
8922e16c | 645 | } |
1da177e4 LT |
646 | } |
647 | ||
3d1ab40f AV |
648 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
649 | ||
650 | static ssize_t | |
651 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 652 | { |
3d1ab40f AV |
653 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
654 | struct elv_fs_entry *entry = to_elv(attr); | |
655 | ssize_t error; | |
656 | ||
657 | if (!entry->show) | |
658 | return -EIO; | |
659 | ||
660 | mutex_lock(&e->sysfs_lock); | |
661 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
662 | mutex_unlock(&e->sysfs_lock); | |
663 | return error; | |
664 | } | |
1da177e4 | 665 | |
3d1ab40f AV |
666 | static ssize_t |
667 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
668 | const char *page, size_t length) | |
669 | { | |
670 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
671 | struct elv_fs_entry *entry = to_elv(attr); | |
672 | ssize_t error; | |
1da177e4 | 673 | |
3d1ab40f AV |
674 | if (!entry->store) |
675 | return -EIO; | |
1da177e4 | 676 | |
3d1ab40f AV |
677 | mutex_lock(&e->sysfs_lock); |
678 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
679 | mutex_unlock(&e->sysfs_lock); | |
680 | return error; | |
681 | } | |
682 | ||
683 | static struct sysfs_ops elv_sysfs_ops = { | |
684 | .show = elv_attr_show, | |
685 | .store = elv_attr_store, | |
686 | }; | |
687 | ||
688 | static struct kobj_type elv_ktype = { | |
689 | .sysfs_ops = &elv_sysfs_ops, | |
690 | .release = elevator_release, | |
691 | }; | |
692 | ||
693 | int elv_register_queue(struct request_queue *q) | |
694 | { | |
695 | elevator_t *e = q->elevator; | |
696 | int error; | |
697 | ||
698 | e->kobj.parent = &q->kobj; | |
699 | ||
700 | error = kobject_add(&e->kobj); | |
701 | if (!error) { | |
e572ec7e | 702 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 703 | if (attr) { |
e572ec7e AV |
704 | while (attr->attr.name) { |
705 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 706 | break; |
e572ec7e | 707 | attr++; |
3d1ab40f AV |
708 | } |
709 | } | |
710 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
711 | } | |
712 | return error; | |
1da177e4 LT |
713 | } |
714 | ||
715 | void elv_unregister_queue(struct request_queue *q) | |
716 | { | |
717 | if (q) { | |
718 | elevator_t *e = q->elevator; | |
3d1ab40f AV |
719 | kobject_uevent(&e->kobj, KOBJ_REMOVE); |
720 | kobject_del(&e->kobj); | |
1da177e4 LT |
721 | } |
722 | } | |
723 | ||
724 | int elv_register(struct elevator_type *e) | |
725 | { | |
2824bc93 | 726 | spin_lock_irq(&elv_list_lock); |
1da177e4 LT |
727 | if (elevator_find(e->elevator_name)) |
728 | BUG(); | |
1da177e4 LT |
729 | list_add_tail(&e->list, &elv_list); |
730 | spin_unlock_irq(&elv_list_lock); | |
731 | ||
732 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
733 | if (!strcmp(e->elevator_name, chosen_elevator) || |
734 | (!*chosen_elevator && | |
735 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
736 | printk(" (default)"); | |
1da177e4 LT |
737 | printk("\n"); |
738 | return 0; | |
739 | } | |
740 | EXPORT_SYMBOL_GPL(elv_register); | |
741 | ||
742 | void elv_unregister(struct elevator_type *e) | |
743 | { | |
83521d3e CH |
744 | struct task_struct *g, *p; |
745 | ||
746 | /* | |
747 | * Iterate every thread in the process to remove the io contexts. | |
748 | */ | |
e17a9489 AV |
749 | if (e->ops.trim) { |
750 | read_lock(&tasklist_lock); | |
751 | do_each_thread(g, p) { | |
752 | task_lock(p); | |
753 | e->ops.trim(p->io_context); | |
754 | task_unlock(p); | |
755 | } while_each_thread(g, p); | |
756 | read_unlock(&tasklist_lock); | |
757 | } | |
83521d3e | 758 | |
1da177e4 LT |
759 | spin_lock_irq(&elv_list_lock); |
760 | list_del_init(&e->list); | |
761 | spin_unlock_irq(&elv_list_lock); | |
762 | } | |
763 | EXPORT_SYMBOL_GPL(elv_unregister); | |
764 | ||
765 | /* | |
766 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
767 | * we don't free the old io scheduler, before we have allocated what we | |
768 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 769 | * one, if the new one fails init for some reason. |
1da177e4 | 770 | */ |
3d1ab40f | 771 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
1da177e4 | 772 | { |
cb98fc8b | 773 | elevator_t *old_elevator, *e; |
1da177e4 | 774 | |
cb98fc8b TH |
775 | /* |
776 | * Allocate new elevator | |
777 | */ | |
3d1ab40f | 778 | e = elevator_alloc(new_e); |
1da177e4 | 779 | if (!e) |
3d1ab40f | 780 | return 0; |
1da177e4 LT |
781 | |
782 | /* | |
cb98fc8b | 783 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 784 | */ |
cb98fc8b TH |
785 | spin_lock_irq(q->queue_lock); |
786 | ||
64521d1a | 787 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 788 | |
15853af9 | 789 | elv_drain_elevator(q); |
cb98fc8b TH |
790 | |
791 | while (q->rq.elvpriv) { | |
407df2aa TH |
792 | blk_remove_plug(q); |
793 | q->request_fn(q); | |
cb98fc8b | 794 | spin_unlock_irq(q->queue_lock); |
64521d1a | 795 | msleep(10); |
cb98fc8b | 796 | spin_lock_irq(q->queue_lock); |
15853af9 | 797 | elv_drain_elevator(q); |
cb98fc8b TH |
798 | } |
799 | ||
800 | spin_unlock_irq(q->queue_lock); | |
1da177e4 LT |
801 | |
802 | /* | |
803 | * unregister old elevator data | |
804 | */ | |
805 | elv_unregister_queue(q); | |
806 | old_elevator = q->elevator; | |
807 | ||
1da177e4 LT |
808 | /* |
809 | * attach and start new elevator | |
810 | */ | |
3d1ab40f | 811 | if (elevator_attach(q, e)) |
1da177e4 LT |
812 | goto fail; |
813 | ||
814 | if (elv_register_queue(q)) | |
815 | goto fail_register; | |
816 | ||
817 | /* | |
cb98fc8b | 818 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
819 | */ |
820 | elevator_exit(old_elevator); | |
64521d1a | 821 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 822 | return 1; |
1da177e4 LT |
823 | |
824 | fail_register: | |
825 | /* | |
826 | * switch failed, exit the new io scheduler and reattach the old | |
827 | * one again (along with re-adding the sysfs dir) | |
828 | */ | |
829 | elevator_exit(e); | |
cb98fc8b | 830 | e = NULL; |
1da177e4 LT |
831 | fail: |
832 | q->elevator = old_elevator; | |
833 | elv_register_queue(q); | |
64521d1a | 834 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f AV |
835 | if (e) |
836 | kobject_put(&e->kobj); | |
837 | return 0; | |
1da177e4 LT |
838 | } |
839 | ||
840 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
841 | { | |
842 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 843 | size_t len; |
1da177e4 LT |
844 | struct elevator_type *e; |
845 | ||
be561235 TH |
846 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
847 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
848 | len = strlen(elevator_name); | |
1da177e4 | 849 | |
be561235 TH |
850 | if (len && elevator_name[len - 1] == '\n') |
851 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
852 | |
853 | e = elevator_get(elevator_name); | |
854 | if (!e) { | |
855 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
856 | return -EINVAL; | |
857 | } | |
858 | ||
2ca7d93b ND |
859 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
860 | elevator_put(e); | |
1da177e4 | 861 | return count; |
2ca7d93b | 862 | } |
1da177e4 | 863 | |
3d1ab40f AV |
864 | if (!elevator_switch(q, e)) |
865 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
866 | return count; |
867 | } | |
868 | ||
869 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
870 | { | |
871 | elevator_t *e = q->elevator; | |
872 | struct elevator_type *elv = e->elevator_type; | |
873 | struct list_head *entry; | |
874 | int len = 0; | |
875 | ||
876 | spin_lock_irq(q->queue_lock); | |
877 | list_for_each(entry, &elv_list) { | |
878 | struct elevator_type *__e; | |
879 | ||
880 | __e = list_entry(entry, struct elevator_type, list); | |
881 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
882 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
883 | else | |
884 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
885 | } | |
886 | spin_unlock_irq(q->queue_lock); | |
887 | ||
888 | len += sprintf(len+name, "\n"); | |
889 | return len; | |
890 | } | |
891 | ||
1b47f531 | 892 | EXPORT_SYMBOL(elv_dispatch_sort); |
1da177e4 LT |
893 | EXPORT_SYMBOL(elv_add_request); |
894 | EXPORT_SYMBOL(__elv_add_request); | |
895 | EXPORT_SYMBOL(elv_requeue_request); | |
896 | EXPORT_SYMBOL(elv_next_request); | |
8922e16c | 897 | EXPORT_SYMBOL(elv_dequeue_request); |
1da177e4 LT |
898 | EXPORT_SYMBOL(elv_queue_empty); |
899 | EXPORT_SYMBOL(elv_completed_request); | |
900 | EXPORT_SYMBOL(elevator_exit); | |
901 | EXPORT_SYMBOL(elevator_init); |