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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> |
2056a782 | 36 | #include <linux/blktrace_api.h> |
1da177e4 LT |
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 | ||
769db45b | 68 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
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 | } | |
1da177e4 | 84 | |
1da177e4 LT |
85 | static struct elevator_type *elevator_find(const char *name) |
86 | { | |
87 | struct elevator_type *e = NULL; | |
88 | struct list_head *entry; | |
89 | ||
1da177e4 LT |
90 | list_for_each(entry, &elv_list) { |
91 | struct elevator_type *__e; | |
92 | ||
93 | __e = list_entry(entry, struct elevator_type, list); | |
94 | ||
95 | if (!strcmp(__e->elevator_name, name)) { | |
96 | e = __e; | |
97 | break; | |
98 | } | |
99 | } | |
1da177e4 LT |
100 | |
101 | return e; | |
102 | } | |
103 | ||
104 | static void elevator_put(struct elevator_type *e) | |
105 | { | |
106 | module_put(e->elevator_owner); | |
107 | } | |
108 | ||
109 | static struct elevator_type *elevator_get(const char *name) | |
110 | { | |
2824bc93 | 111 | struct elevator_type *e; |
1da177e4 | 112 | |
2824bc93 TH |
113 | spin_lock_irq(&elv_list_lock); |
114 | ||
115 | e = elevator_find(name); | |
116 | if (e && !try_module_get(e->elevator_owner)) | |
117 | e = NULL; | |
118 | ||
119 | spin_unlock_irq(&elv_list_lock); | |
1da177e4 LT |
120 | |
121 | return e; | |
122 | } | |
123 | ||
3d1ab40f | 124 | static int elevator_attach(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 LT |
125 | { |
126 | int ret = 0; | |
127 | ||
1da177e4 LT |
128 | q->elevator = eq; |
129 | ||
130 | if (eq->ops->elevator_init_fn) | |
131 | ret = eq->ops->elevator_init_fn(q, eq); | |
132 | ||
133 | return ret; | |
134 | } | |
135 | ||
136 | static char chosen_elevator[16]; | |
137 | ||
5f003976 | 138 | static int __init elevator_setup(char *str) |
1da177e4 | 139 | { |
752a3b79 CE |
140 | /* |
141 | * Be backwards-compatible with previous kernels, so users | |
142 | * won't get the wrong elevator. | |
143 | */ | |
5f003976 | 144 | if (!strcmp(str, "as")) |
752a3b79 | 145 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 146 | else |
5f003976 | 147 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 148 | return 1; |
1da177e4 LT |
149 | } |
150 | ||
151 | __setup("elevator=", elevator_setup); | |
152 | ||
3d1ab40f AV |
153 | static struct kobj_type elv_ktype; |
154 | ||
155 | static elevator_t *elevator_alloc(struct elevator_type *e) | |
156 | { | |
157 | elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL); | |
158 | if (eq) { | |
159 | memset(eq, 0, sizeof(*eq)); | |
160 | eq->ops = &e->ops; | |
161 | eq->elevator_type = e; | |
162 | kobject_init(&eq->kobj); | |
163 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); | |
164 | eq->kobj.ktype = &elv_ktype; | |
165 | mutex_init(&eq->sysfs_lock); | |
166 | } else { | |
167 | elevator_put(e); | |
168 | } | |
169 | return eq; | |
170 | } | |
171 | ||
172 | static void elevator_release(struct kobject *kobj) | |
173 | { | |
174 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
175 | elevator_put(e->elevator_type); | |
176 | kfree(e); | |
177 | } | |
178 | ||
1da177e4 LT |
179 | int elevator_init(request_queue_t *q, char *name) |
180 | { | |
181 | struct elevator_type *e = NULL; | |
182 | struct elevator_queue *eq; | |
183 | int ret = 0; | |
184 | ||
cb98fc8b TH |
185 | INIT_LIST_HEAD(&q->queue_head); |
186 | q->last_merge = NULL; | |
187 | q->end_sector = 0; | |
188 | q->boundary_rq = NULL; | |
cb98fc8b | 189 | |
5f003976 | 190 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
191 | return -EINVAL; |
192 | ||
248d5ca5 ND |
193 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
194 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
195 | ||
196 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
197 | printk("Default I/O scheduler not found, using no-op\n"); | |
198 | e = elevator_get("noop"); | |
5f003976 ND |
199 | } |
200 | ||
3d1ab40f AV |
201 | eq = elevator_alloc(e); |
202 | if (!eq) | |
1da177e4 | 203 | return -ENOMEM; |
1da177e4 | 204 | |
3d1ab40f AV |
205 | ret = elevator_attach(q, eq); |
206 | if (ret) | |
207 | kobject_put(&eq->kobj); | |
1da177e4 LT |
208 | |
209 | return ret; | |
210 | } | |
211 | ||
212 | void elevator_exit(elevator_t *e) | |
213 | { | |
3d1ab40f | 214 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
215 | if (e->ops->elevator_exit_fn) |
216 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
217 | e->ops = NULL; |
218 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 219 | |
3d1ab40f | 220 | kobject_put(&e->kobj); |
1da177e4 LT |
221 | } |
222 | ||
8922e16c TH |
223 | /* |
224 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
225 | * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be | |
226 | * appended to the dispatch queue. To be used by specific elevators. | |
227 | */ | |
1b47f531 | 228 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
229 | { |
230 | sector_t boundary; | |
8922e16c TH |
231 | struct list_head *entry; |
232 | ||
06b86245 TH |
233 | if (q->last_merge == rq) |
234 | q->last_merge = NULL; | |
15853af9 | 235 | q->nr_sorted--; |
06b86245 | 236 | |
1b47f531 | 237 | boundary = q->end_sector; |
cb19833d | 238 | |
8922e16c TH |
239 | list_for_each_prev(entry, &q->queue_head) { |
240 | struct request *pos = list_entry_rq(entry); | |
241 | ||
242 | if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) | |
243 | break; | |
244 | if (rq->sector >= boundary) { | |
245 | if (pos->sector < boundary) | |
246 | continue; | |
247 | } else { | |
248 | if (pos->sector >= boundary) | |
249 | break; | |
250 | } | |
251 | if (rq->sector >= pos->sector) | |
252 | break; | |
253 | } | |
254 | ||
255 | list_add(&rq->queuelist, entry); | |
256 | } | |
257 | ||
1da177e4 LT |
258 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
259 | { | |
260 | elevator_t *e = q->elevator; | |
06b86245 TH |
261 | int ret; |
262 | ||
263 | if (q->last_merge) { | |
264 | ret = elv_try_merge(q->last_merge, bio); | |
265 | if (ret != ELEVATOR_NO_MERGE) { | |
266 | *req = q->last_merge; | |
267 | return ret; | |
268 | } | |
269 | } | |
1da177e4 LT |
270 | |
271 | if (e->ops->elevator_merge_fn) | |
272 | return e->ops->elevator_merge_fn(q, req, bio); | |
273 | ||
274 | return ELEVATOR_NO_MERGE; | |
275 | } | |
276 | ||
277 | void elv_merged_request(request_queue_t *q, struct request *rq) | |
278 | { | |
279 | elevator_t *e = q->elevator; | |
280 | ||
281 | if (e->ops->elevator_merged_fn) | |
282 | e->ops->elevator_merged_fn(q, rq); | |
06b86245 TH |
283 | |
284 | q->last_merge = rq; | |
1da177e4 LT |
285 | } |
286 | ||
287 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
288 | struct request *next) | |
289 | { | |
290 | elevator_t *e = q->elevator; | |
291 | ||
1da177e4 LT |
292 | if (e->ops->elevator_merge_req_fn) |
293 | e->ops->elevator_merge_req_fn(q, rq, next); | |
15853af9 | 294 | q->nr_sorted--; |
06b86245 TH |
295 | |
296 | q->last_merge = rq; | |
1da177e4 LT |
297 | } |
298 | ||
8922e16c | 299 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 LT |
300 | { |
301 | elevator_t *e = q->elevator; | |
302 | ||
303 | /* | |
304 | * it already went through dequeue, we need to decrement the | |
305 | * in_flight count again | |
306 | */ | |
8922e16c | 307 | if (blk_account_rq(rq)) { |
1da177e4 | 308 | q->in_flight--; |
8922e16c TH |
309 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
310 | e->ops->elevator_deactivate_req_fn(q, rq); | |
311 | } | |
1da177e4 LT |
312 | |
313 | rq->flags &= ~REQ_STARTED; | |
314 | ||
30e9656c | 315 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
316 | } |
317 | ||
15853af9 TH |
318 | static void elv_drain_elevator(request_queue_t *q) |
319 | { | |
320 | static int printed; | |
321 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
322 | ; | |
323 | if (q->nr_sorted == 0) | |
324 | return; | |
325 | if (printed++ < 10) { | |
326 | printk(KERN_ERR "%s: forced dispatching is broken " | |
327 | "(nr_sorted=%u), please report this\n", | |
328 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
329 | } | |
330 | } | |
331 | ||
30e9656c | 332 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 333 | { |
797e7dbb TH |
334 | struct list_head *pos; |
335 | unsigned ordseq; | |
dac07ec1 | 336 | int unplug_it = 1; |
797e7dbb | 337 | |
2056a782 JA |
338 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
339 | ||
1da177e4 LT |
340 | rq->q = q; |
341 | ||
8922e16c TH |
342 | switch (where) { |
343 | case ELEVATOR_INSERT_FRONT: | |
344 | rq->flags |= REQ_SOFTBARRIER; | |
345 | ||
346 | list_add(&rq->queuelist, &q->queue_head); | |
347 | break; | |
348 | ||
349 | case ELEVATOR_INSERT_BACK: | |
350 | rq->flags |= REQ_SOFTBARRIER; | |
15853af9 | 351 | elv_drain_elevator(q); |
8922e16c TH |
352 | list_add_tail(&rq->queuelist, &q->queue_head); |
353 | /* | |
354 | * We kick the queue here for the following reasons. | |
355 | * - The elevator might have returned NULL previously | |
356 | * to delay requests and returned them now. As the | |
357 | * queue wasn't empty before this request, ll_rw_blk | |
358 | * won't run the queue on return, resulting in hang. | |
359 | * - Usually, back inserted requests won't be merged | |
360 | * with anything. There's no point in delaying queue | |
361 | * processing. | |
362 | */ | |
363 | blk_remove_plug(q); | |
364 | q->request_fn(q); | |
365 | break; | |
366 | ||
367 | case ELEVATOR_INSERT_SORT: | |
368 | BUG_ON(!blk_fs_request(rq)); | |
369 | rq->flags |= REQ_SORTED; | |
15853af9 | 370 | q->nr_sorted++; |
06b86245 TH |
371 | if (q->last_merge == NULL && rq_mergeable(rq)) |
372 | q->last_merge = rq; | |
ca23509f TH |
373 | /* |
374 | * Some ioscheds (cfq) run q->request_fn directly, so | |
375 | * rq cannot be accessed after calling | |
376 | * elevator_add_req_fn. | |
377 | */ | |
378 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
379 | break; |
380 | ||
797e7dbb TH |
381 | case ELEVATOR_INSERT_REQUEUE: |
382 | /* | |
383 | * If ordered flush isn't in progress, we do front | |
384 | * insertion; otherwise, requests should be requeued | |
385 | * in ordseq order. | |
386 | */ | |
387 | rq->flags |= REQ_SOFTBARRIER; | |
388 | ||
389 | if (q->ordseq == 0) { | |
390 | list_add(&rq->queuelist, &q->queue_head); | |
391 | break; | |
392 | } | |
393 | ||
394 | ordseq = blk_ordered_req_seq(rq); | |
395 | ||
396 | list_for_each(pos, &q->queue_head) { | |
397 | struct request *pos_rq = list_entry_rq(pos); | |
398 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
399 | break; | |
400 | } | |
401 | ||
402 | list_add_tail(&rq->queuelist, pos); | |
dac07ec1 JA |
403 | /* |
404 | * most requeues happen because of a busy condition, don't | |
405 | * force unplug of the queue for that case. | |
406 | */ | |
407 | unplug_it = 0; | |
797e7dbb TH |
408 | break; |
409 | ||
8922e16c TH |
410 | default: |
411 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
412 | __FUNCTION__, where); | |
413 | BUG(); | |
414 | } | |
415 | ||
dac07ec1 | 416 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
417 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
418 | - q->in_flight; | |
419 | ||
420 | if (nrq >= q->unplug_thresh) | |
421 | __generic_unplug_device(q); | |
422 | } | |
1da177e4 LT |
423 | } |
424 | ||
30e9656c TH |
425 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
426 | int plug) | |
427 | { | |
428 | if (q->ordcolor) | |
429 | rq->flags |= REQ_ORDERED_COLOR; | |
430 | ||
431 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { | |
432 | /* | |
433 | * toggle ordered color | |
434 | */ | |
435 | if (blk_barrier_rq(rq)) | |
436 | q->ordcolor ^= 1; | |
437 | ||
438 | /* | |
439 | * barriers implicitly indicate back insertion | |
440 | */ | |
441 | if (where == ELEVATOR_INSERT_SORT) | |
442 | where = ELEVATOR_INSERT_BACK; | |
443 | ||
444 | /* | |
445 | * this request is scheduling boundary, update | |
446 | * end_sector | |
447 | */ | |
448 | if (blk_fs_request(rq)) { | |
449 | q->end_sector = rq_end_sector(rq); | |
450 | q->boundary_rq = rq; | |
451 | } | |
452 | } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) | |
453 | where = ELEVATOR_INSERT_BACK; | |
454 | ||
455 | if (plug) | |
456 | blk_plug_device(q); | |
457 | ||
458 | elv_insert(q, rq, where); | |
459 | } | |
460 | ||
1da177e4 LT |
461 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
462 | int plug) | |
463 | { | |
464 | unsigned long flags; | |
465 | ||
466 | spin_lock_irqsave(q->queue_lock, flags); | |
467 | __elv_add_request(q, rq, where, plug); | |
468 | spin_unlock_irqrestore(q->queue_lock, flags); | |
469 | } | |
470 | ||
471 | static inline struct request *__elv_next_request(request_queue_t *q) | |
472 | { | |
8922e16c TH |
473 | struct request *rq; |
474 | ||
797e7dbb TH |
475 | while (1) { |
476 | while (!list_empty(&q->queue_head)) { | |
477 | rq = list_entry_rq(q->queue_head.next); | |
478 | if (blk_do_ordered(q, &rq)) | |
479 | return rq; | |
480 | } | |
1da177e4 | 481 | |
797e7dbb TH |
482 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
483 | return NULL; | |
1da177e4 | 484 | } |
1da177e4 LT |
485 | } |
486 | ||
487 | struct request *elv_next_request(request_queue_t *q) | |
488 | { | |
489 | struct request *rq; | |
490 | int ret; | |
491 | ||
492 | while ((rq = __elv_next_request(q)) != NULL) { | |
8922e16c TH |
493 | if (!(rq->flags & REQ_STARTED)) { |
494 | elevator_t *e = q->elevator; | |
495 | ||
496 | /* | |
497 | * This is the first time the device driver | |
498 | * sees this request (possibly after | |
499 | * requeueing). Notify IO scheduler. | |
500 | */ | |
501 | if (blk_sorted_rq(rq) && | |
502 | e->ops->elevator_activate_req_fn) | |
503 | e->ops->elevator_activate_req_fn(q, rq); | |
1da177e4 | 504 | |
8922e16c TH |
505 | /* |
506 | * just mark as started even if we don't start | |
507 | * it, a request that has been delayed should | |
508 | * not be passed by new incoming requests | |
509 | */ | |
510 | rq->flags |= REQ_STARTED; | |
2056a782 | 511 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 512 | } |
1da177e4 | 513 | |
8922e16c | 514 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 515 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
516 | q->boundary_rq = NULL; |
517 | } | |
1da177e4 LT |
518 | |
519 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) | |
520 | break; | |
521 | ||
522 | ret = q->prep_rq_fn(q, rq); | |
523 | if (ret == BLKPREP_OK) { | |
524 | break; | |
525 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
526 | /* |
527 | * the request may have been (partially) prepped. | |
528 | * we need to keep this request in the front to | |
8922e16c TH |
529 | * avoid resource deadlock. REQ_STARTED will |
530 | * prevent other fs requests from passing this one. | |
2e759cd4 | 531 | */ |
1da177e4 LT |
532 | rq = NULL; |
533 | break; | |
534 | } else if (ret == BLKPREP_KILL) { | |
535 | int nr_bytes = rq->hard_nr_sectors << 9; | |
536 | ||
537 | if (!nr_bytes) | |
538 | nr_bytes = rq->data_len; | |
539 | ||
540 | blkdev_dequeue_request(rq); | |
541 | rq->flags |= REQ_QUIET; | |
542 | end_that_request_chunk(rq, 0, nr_bytes); | |
8ffdc655 | 543 | end_that_request_last(rq, 0); |
1da177e4 LT |
544 | } else { |
545 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
546 | ret); | |
547 | break; | |
548 | } | |
549 | } | |
550 | ||
551 | return rq; | |
552 | } | |
553 | ||
8922e16c | 554 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 555 | { |
8922e16c TH |
556 | BUG_ON(list_empty(&rq->queuelist)); |
557 | ||
558 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
559 | |
560 | /* | |
561 | * the time frame between a request being removed from the lists | |
562 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 563 | * the driver side. |
1da177e4 LT |
564 | */ |
565 | if (blk_account_rq(rq)) | |
566 | q->in_flight++; | |
1da177e4 LT |
567 | } |
568 | ||
569 | int elv_queue_empty(request_queue_t *q) | |
570 | { | |
571 | elevator_t *e = q->elevator; | |
572 | ||
8922e16c TH |
573 | if (!list_empty(&q->queue_head)) |
574 | return 0; | |
575 | ||
1da177e4 LT |
576 | if (e->ops->elevator_queue_empty_fn) |
577 | return e->ops->elevator_queue_empty_fn(q); | |
578 | ||
8922e16c | 579 | return 1; |
1da177e4 LT |
580 | } |
581 | ||
582 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) | |
583 | { | |
1da177e4 LT |
584 | elevator_t *e = q->elevator; |
585 | ||
586 | if (e->ops->elevator_latter_req_fn) | |
587 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
588 | return NULL; |
589 | } | |
590 | ||
591 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
592 | { | |
1da177e4 LT |
593 | elevator_t *e = q->elevator; |
594 | ||
595 | if (e->ops->elevator_former_req_fn) | |
596 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
597 | return NULL; |
598 | } | |
599 | ||
22e2c507 | 600 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
8267e268 | 601 | gfp_t gfp_mask) |
1da177e4 LT |
602 | { |
603 | elevator_t *e = q->elevator; | |
604 | ||
605 | if (e->ops->elevator_set_req_fn) | |
22e2c507 | 606 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
607 | |
608 | rq->elevator_private = NULL; | |
609 | return 0; | |
610 | } | |
611 | ||
612 | void elv_put_request(request_queue_t *q, struct request *rq) | |
613 | { | |
614 | elevator_t *e = q->elevator; | |
615 | ||
616 | if (e->ops->elevator_put_req_fn) | |
617 | e->ops->elevator_put_req_fn(q, rq); | |
618 | } | |
619 | ||
22e2c507 | 620 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
621 | { |
622 | elevator_t *e = q->elevator; | |
623 | ||
624 | if (e->ops->elevator_may_queue_fn) | |
22e2c507 | 625 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
1da177e4 LT |
626 | |
627 | return ELV_MQUEUE_MAY; | |
628 | } | |
629 | ||
630 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
631 | { | |
632 | elevator_t *e = q->elevator; | |
633 | ||
634 | /* | |
635 | * request is released from the driver, io must be done | |
636 | */ | |
8922e16c | 637 | if (blk_account_rq(rq)) { |
1da177e4 | 638 | q->in_flight--; |
1bc691d3 TH |
639 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
640 | e->ops->elevator_completed_req_fn(q, rq); | |
641 | } | |
797e7dbb | 642 | |
1bc691d3 TH |
643 | /* |
644 | * Check if the queue is waiting for fs requests to be | |
645 | * drained for flush sequence. | |
646 | */ | |
647 | if (unlikely(q->ordseq)) { | |
648 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
649 | if (q->in_flight == 0 && | |
797e7dbb TH |
650 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
651 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
652 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
653 | q->request_fn(q); | |
654 | } | |
8922e16c | 655 | } |
1da177e4 LT |
656 | } |
657 | ||
3d1ab40f AV |
658 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
659 | ||
660 | static ssize_t | |
661 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 662 | { |
3d1ab40f AV |
663 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
664 | struct elv_fs_entry *entry = to_elv(attr); | |
665 | ssize_t error; | |
666 | ||
667 | if (!entry->show) | |
668 | return -EIO; | |
669 | ||
670 | mutex_lock(&e->sysfs_lock); | |
671 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
672 | mutex_unlock(&e->sysfs_lock); | |
673 | return error; | |
674 | } | |
1da177e4 | 675 | |
3d1ab40f AV |
676 | static ssize_t |
677 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
678 | const char *page, size_t length) | |
679 | { | |
680 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
681 | struct elv_fs_entry *entry = to_elv(attr); | |
682 | ssize_t error; | |
1da177e4 | 683 | |
3d1ab40f AV |
684 | if (!entry->store) |
685 | return -EIO; | |
1da177e4 | 686 | |
3d1ab40f AV |
687 | mutex_lock(&e->sysfs_lock); |
688 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
689 | mutex_unlock(&e->sysfs_lock); | |
690 | return error; | |
691 | } | |
692 | ||
693 | static struct sysfs_ops elv_sysfs_ops = { | |
694 | .show = elv_attr_show, | |
695 | .store = elv_attr_store, | |
696 | }; | |
697 | ||
698 | static struct kobj_type elv_ktype = { | |
699 | .sysfs_ops = &elv_sysfs_ops, | |
700 | .release = elevator_release, | |
701 | }; | |
702 | ||
703 | int elv_register_queue(struct request_queue *q) | |
704 | { | |
705 | elevator_t *e = q->elevator; | |
706 | int error; | |
707 | ||
708 | e->kobj.parent = &q->kobj; | |
709 | ||
710 | error = kobject_add(&e->kobj); | |
711 | if (!error) { | |
e572ec7e | 712 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 713 | if (attr) { |
e572ec7e AV |
714 | while (attr->attr.name) { |
715 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 716 | break; |
e572ec7e | 717 | attr++; |
3d1ab40f AV |
718 | } |
719 | } | |
720 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
721 | } | |
722 | return error; | |
1da177e4 LT |
723 | } |
724 | ||
725 | void elv_unregister_queue(struct request_queue *q) | |
726 | { | |
727 | if (q) { | |
728 | elevator_t *e = q->elevator; | |
3d1ab40f AV |
729 | kobject_uevent(&e->kobj, KOBJ_REMOVE); |
730 | kobject_del(&e->kobj); | |
1da177e4 LT |
731 | } |
732 | } | |
733 | ||
734 | int elv_register(struct elevator_type *e) | |
735 | { | |
2824bc93 | 736 | spin_lock_irq(&elv_list_lock); |
ce524497 | 737 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 LT |
738 | list_add_tail(&e->list, &elv_list); |
739 | spin_unlock_irq(&elv_list_lock); | |
740 | ||
741 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
742 | if (!strcmp(e->elevator_name, chosen_elevator) || |
743 | (!*chosen_elevator && | |
744 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
745 | printk(" (default)"); | |
1da177e4 LT |
746 | printk("\n"); |
747 | return 0; | |
748 | } | |
749 | EXPORT_SYMBOL_GPL(elv_register); | |
750 | ||
751 | void elv_unregister(struct elevator_type *e) | |
752 | { | |
83521d3e CH |
753 | struct task_struct *g, *p; |
754 | ||
755 | /* | |
756 | * Iterate every thread in the process to remove the io contexts. | |
757 | */ | |
e17a9489 AV |
758 | if (e->ops.trim) { |
759 | read_lock(&tasklist_lock); | |
760 | do_each_thread(g, p) { | |
761 | task_lock(p); | |
762 | e->ops.trim(p->io_context); | |
763 | task_unlock(p); | |
764 | } while_each_thread(g, p); | |
765 | read_unlock(&tasklist_lock); | |
766 | } | |
83521d3e | 767 | |
1da177e4 LT |
768 | spin_lock_irq(&elv_list_lock); |
769 | list_del_init(&e->list); | |
770 | spin_unlock_irq(&elv_list_lock); | |
771 | } | |
772 | EXPORT_SYMBOL_GPL(elv_unregister); | |
773 | ||
774 | /* | |
775 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
776 | * we don't free the old io scheduler, before we have allocated what we | |
777 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 778 | * one, if the new one fails init for some reason. |
1da177e4 | 779 | */ |
3d1ab40f | 780 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
1da177e4 | 781 | { |
cb98fc8b | 782 | elevator_t *old_elevator, *e; |
1da177e4 | 783 | |
cb98fc8b TH |
784 | /* |
785 | * Allocate new elevator | |
786 | */ | |
3d1ab40f | 787 | e = elevator_alloc(new_e); |
1da177e4 | 788 | if (!e) |
3d1ab40f | 789 | return 0; |
1da177e4 LT |
790 | |
791 | /* | |
cb98fc8b | 792 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 793 | */ |
cb98fc8b TH |
794 | spin_lock_irq(q->queue_lock); |
795 | ||
64521d1a | 796 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 797 | |
15853af9 | 798 | elv_drain_elevator(q); |
cb98fc8b TH |
799 | |
800 | while (q->rq.elvpriv) { | |
407df2aa TH |
801 | blk_remove_plug(q); |
802 | q->request_fn(q); | |
cb98fc8b | 803 | spin_unlock_irq(q->queue_lock); |
64521d1a | 804 | msleep(10); |
cb98fc8b | 805 | spin_lock_irq(q->queue_lock); |
15853af9 | 806 | elv_drain_elevator(q); |
cb98fc8b TH |
807 | } |
808 | ||
809 | spin_unlock_irq(q->queue_lock); | |
1da177e4 LT |
810 | |
811 | /* | |
812 | * unregister old elevator data | |
813 | */ | |
814 | elv_unregister_queue(q); | |
815 | old_elevator = q->elevator; | |
816 | ||
1da177e4 LT |
817 | /* |
818 | * attach and start new elevator | |
819 | */ | |
3d1ab40f | 820 | if (elevator_attach(q, e)) |
1da177e4 LT |
821 | goto fail; |
822 | ||
823 | if (elv_register_queue(q)) | |
824 | goto fail_register; | |
825 | ||
826 | /* | |
cb98fc8b | 827 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
828 | */ |
829 | elevator_exit(old_elevator); | |
64521d1a | 830 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 831 | return 1; |
1da177e4 LT |
832 | |
833 | fail_register: | |
834 | /* | |
835 | * switch failed, exit the new io scheduler and reattach the old | |
836 | * one again (along with re-adding the sysfs dir) | |
837 | */ | |
838 | elevator_exit(e); | |
cb98fc8b | 839 | e = NULL; |
1da177e4 LT |
840 | fail: |
841 | q->elevator = old_elevator; | |
842 | elv_register_queue(q); | |
64521d1a | 843 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f AV |
844 | if (e) |
845 | kobject_put(&e->kobj); | |
846 | return 0; | |
1da177e4 LT |
847 | } |
848 | ||
849 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
850 | { | |
851 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 852 | size_t len; |
1da177e4 LT |
853 | struct elevator_type *e; |
854 | ||
be561235 TH |
855 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
856 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
857 | len = strlen(elevator_name); | |
1da177e4 | 858 | |
be561235 TH |
859 | if (len && elevator_name[len - 1] == '\n') |
860 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
861 | |
862 | e = elevator_get(elevator_name); | |
863 | if (!e) { | |
864 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
865 | return -EINVAL; | |
866 | } | |
867 | ||
2ca7d93b ND |
868 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
869 | elevator_put(e); | |
1da177e4 | 870 | return count; |
2ca7d93b | 871 | } |
1da177e4 | 872 | |
3d1ab40f AV |
873 | if (!elevator_switch(q, e)) |
874 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
875 | return count; |
876 | } | |
877 | ||
878 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
879 | { | |
880 | elevator_t *e = q->elevator; | |
881 | struct elevator_type *elv = e->elevator_type; | |
882 | struct list_head *entry; | |
883 | int len = 0; | |
884 | ||
885 | spin_lock_irq(q->queue_lock); | |
886 | list_for_each(entry, &elv_list) { | |
887 | struct elevator_type *__e; | |
888 | ||
889 | __e = list_entry(entry, struct elevator_type, list); | |
890 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
891 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
892 | else | |
893 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
894 | } | |
895 | spin_unlock_irq(q->queue_lock); | |
896 | ||
897 | len += sprintf(len+name, "\n"); | |
898 | return len; | |
899 | } | |
900 | ||
1b47f531 | 901 | EXPORT_SYMBOL(elv_dispatch_sort); |
1da177e4 LT |
902 | EXPORT_SYMBOL(elv_add_request); |
903 | EXPORT_SYMBOL(__elv_add_request); | |
1da177e4 | 904 | EXPORT_SYMBOL(elv_next_request); |
8922e16c | 905 | EXPORT_SYMBOL(elv_dequeue_request); |
1da177e4 | 906 | EXPORT_SYMBOL(elv_queue_empty); |
1da177e4 LT |
907 | EXPORT_SYMBOL(elevator_exit); |
908 | EXPORT_SYMBOL(elevator_init); |