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> |
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 | ||
bc1c1169 | 124 | static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 | 125 | { |
bc1c1169 JA |
126 | return eq->ops->elevator_init_fn(q, eq); |
127 | } | |
1da177e4 | 128 | |
bc1c1169 JA |
129 | static void elevator_attach(request_queue_t *q, struct elevator_queue *eq, |
130 | void *data) | |
131 | { | |
1da177e4 | 132 | q->elevator = eq; |
bc1c1169 | 133 | eq->elevator_data = data; |
1da177e4 LT |
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; | |
bc1c1169 | 184 | void *data; |
1da177e4 | 185 | |
cb98fc8b TH |
186 | INIT_LIST_HEAD(&q->queue_head); |
187 | q->last_merge = NULL; | |
188 | q->end_sector = 0; | |
189 | q->boundary_rq = NULL; | |
cb98fc8b | 190 | |
5f003976 | 191 | if (name && !(e = elevator_get(name))) |
1da177e4 LT |
192 | return -EINVAL; |
193 | ||
248d5ca5 ND |
194 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
195 | printk("I/O scheduler %s not found\n", chosen_elevator); | |
196 | ||
197 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { | |
198 | printk("Default I/O scheduler not found, using no-op\n"); | |
199 | e = elevator_get("noop"); | |
5f003976 ND |
200 | } |
201 | ||
3d1ab40f AV |
202 | eq = elevator_alloc(e); |
203 | if (!eq) | |
1da177e4 | 204 | return -ENOMEM; |
1da177e4 | 205 | |
bc1c1169 JA |
206 | data = elevator_init_queue(q, eq); |
207 | if (!data) { | |
3d1ab40f | 208 | kobject_put(&eq->kobj); |
bc1c1169 JA |
209 | return -ENOMEM; |
210 | } | |
1da177e4 | 211 | |
bc1c1169 | 212 | elevator_attach(q, eq, data); |
1da177e4 LT |
213 | return ret; |
214 | } | |
215 | ||
216 | void elevator_exit(elevator_t *e) | |
217 | { | |
3d1ab40f | 218 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
219 | if (e->ops->elevator_exit_fn) |
220 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
221 | e->ops = NULL; |
222 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 223 | |
3d1ab40f | 224 | kobject_put(&e->kobj); |
1da177e4 LT |
225 | } |
226 | ||
8922e16c TH |
227 | /* |
228 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
229 | * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be | |
230 | * appended to the dispatch queue. To be used by specific elevators. | |
231 | */ | |
1b47f531 | 232 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
233 | { |
234 | sector_t boundary; | |
8922e16c TH |
235 | struct list_head *entry; |
236 | ||
06b86245 TH |
237 | if (q->last_merge == rq) |
238 | q->last_merge = NULL; | |
15853af9 | 239 | q->nr_sorted--; |
06b86245 | 240 | |
1b47f531 | 241 | boundary = q->end_sector; |
cb19833d | 242 | |
8922e16c TH |
243 | list_for_each_prev(entry, &q->queue_head) { |
244 | struct request *pos = list_entry_rq(entry); | |
245 | ||
246 | if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) | |
247 | break; | |
248 | if (rq->sector >= boundary) { | |
249 | if (pos->sector < boundary) | |
250 | continue; | |
251 | } else { | |
252 | if (pos->sector >= boundary) | |
253 | break; | |
254 | } | |
255 | if (rq->sector >= pos->sector) | |
256 | break; | |
257 | } | |
258 | ||
259 | list_add(&rq->queuelist, entry); | |
260 | } | |
261 | ||
1da177e4 LT |
262 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
263 | { | |
264 | elevator_t *e = q->elevator; | |
06b86245 TH |
265 | int ret; |
266 | ||
267 | if (q->last_merge) { | |
268 | ret = elv_try_merge(q->last_merge, bio); | |
269 | if (ret != ELEVATOR_NO_MERGE) { | |
270 | *req = q->last_merge; | |
271 | return ret; | |
272 | } | |
273 | } | |
1da177e4 LT |
274 | |
275 | if (e->ops->elevator_merge_fn) | |
276 | return e->ops->elevator_merge_fn(q, req, bio); | |
277 | ||
278 | return ELEVATOR_NO_MERGE; | |
279 | } | |
280 | ||
281 | void elv_merged_request(request_queue_t *q, struct request *rq) | |
282 | { | |
283 | elevator_t *e = q->elevator; | |
284 | ||
285 | if (e->ops->elevator_merged_fn) | |
286 | e->ops->elevator_merged_fn(q, rq); | |
06b86245 TH |
287 | |
288 | q->last_merge = rq; | |
1da177e4 LT |
289 | } |
290 | ||
291 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
292 | struct request *next) | |
293 | { | |
294 | elevator_t *e = q->elevator; | |
295 | ||
1da177e4 LT |
296 | if (e->ops->elevator_merge_req_fn) |
297 | e->ops->elevator_merge_req_fn(q, rq, next); | |
15853af9 | 298 | q->nr_sorted--; |
06b86245 TH |
299 | |
300 | q->last_merge = rq; | |
1da177e4 LT |
301 | } |
302 | ||
8922e16c | 303 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 LT |
304 | { |
305 | elevator_t *e = q->elevator; | |
306 | ||
307 | /* | |
308 | * it already went through dequeue, we need to decrement the | |
309 | * in_flight count again | |
310 | */ | |
8922e16c | 311 | if (blk_account_rq(rq)) { |
1da177e4 | 312 | q->in_flight--; |
8922e16c TH |
313 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
314 | e->ops->elevator_deactivate_req_fn(q, rq); | |
315 | } | |
1da177e4 LT |
316 | |
317 | rq->flags &= ~REQ_STARTED; | |
318 | ||
30e9656c | 319 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
320 | } |
321 | ||
15853af9 TH |
322 | static void elv_drain_elevator(request_queue_t *q) |
323 | { | |
324 | static int printed; | |
325 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
326 | ; | |
327 | if (q->nr_sorted == 0) | |
328 | return; | |
329 | if (printed++ < 10) { | |
330 | printk(KERN_ERR "%s: forced dispatching is broken " | |
331 | "(nr_sorted=%u), please report this\n", | |
332 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
333 | } | |
334 | } | |
335 | ||
30e9656c | 336 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 337 | { |
797e7dbb TH |
338 | struct list_head *pos; |
339 | unsigned ordseq; | |
dac07ec1 | 340 | int unplug_it = 1; |
797e7dbb | 341 | |
2056a782 JA |
342 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
343 | ||
1da177e4 LT |
344 | rq->q = q; |
345 | ||
8922e16c TH |
346 | switch (where) { |
347 | case ELEVATOR_INSERT_FRONT: | |
348 | rq->flags |= REQ_SOFTBARRIER; | |
349 | ||
350 | list_add(&rq->queuelist, &q->queue_head); | |
351 | break; | |
352 | ||
353 | case ELEVATOR_INSERT_BACK: | |
354 | rq->flags |= REQ_SOFTBARRIER; | |
15853af9 | 355 | elv_drain_elevator(q); |
8922e16c TH |
356 | list_add_tail(&rq->queuelist, &q->queue_head); |
357 | /* | |
358 | * We kick the queue here for the following reasons. | |
359 | * - The elevator might have returned NULL previously | |
360 | * to delay requests and returned them now. As the | |
361 | * queue wasn't empty before this request, ll_rw_blk | |
362 | * won't run the queue on return, resulting in hang. | |
363 | * - Usually, back inserted requests won't be merged | |
364 | * with anything. There's no point in delaying queue | |
365 | * processing. | |
366 | */ | |
367 | blk_remove_plug(q); | |
368 | q->request_fn(q); | |
369 | break; | |
370 | ||
371 | case ELEVATOR_INSERT_SORT: | |
372 | BUG_ON(!blk_fs_request(rq)); | |
373 | rq->flags |= REQ_SORTED; | |
15853af9 | 374 | q->nr_sorted++; |
06b86245 TH |
375 | if (q->last_merge == NULL && rq_mergeable(rq)) |
376 | q->last_merge = rq; | |
ca23509f TH |
377 | /* |
378 | * Some ioscheds (cfq) run q->request_fn directly, so | |
379 | * rq cannot be accessed after calling | |
380 | * elevator_add_req_fn. | |
381 | */ | |
382 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
383 | break; |
384 | ||
797e7dbb TH |
385 | case ELEVATOR_INSERT_REQUEUE: |
386 | /* | |
387 | * If ordered flush isn't in progress, we do front | |
388 | * insertion; otherwise, requests should be requeued | |
389 | * in ordseq order. | |
390 | */ | |
391 | rq->flags |= REQ_SOFTBARRIER; | |
392 | ||
393 | if (q->ordseq == 0) { | |
394 | list_add(&rq->queuelist, &q->queue_head); | |
395 | break; | |
396 | } | |
397 | ||
398 | ordseq = blk_ordered_req_seq(rq); | |
399 | ||
400 | list_for_each(pos, &q->queue_head) { | |
401 | struct request *pos_rq = list_entry_rq(pos); | |
402 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
403 | break; | |
404 | } | |
405 | ||
406 | list_add_tail(&rq->queuelist, pos); | |
dac07ec1 JA |
407 | /* |
408 | * most requeues happen because of a busy condition, don't | |
409 | * force unplug of the queue for that case. | |
410 | */ | |
411 | unplug_it = 0; | |
797e7dbb TH |
412 | break; |
413 | ||
8922e16c TH |
414 | default: |
415 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
416 | __FUNCTION__, where); | |
417 | BUG(); | |
418 | } | |
419 | ||
dac07ec1 | 420 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
421 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
422 | - q->in_flight; | |
423 | ||
424 | if (nrq >= q->unplug_thresh) | |
425 | __generic_unplug_device(q); | |
426 | } | |
1da177e4 LT |
427 | } |
428 | ||
30e9656c TH |
429 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
430 | int plug) | |
431 | { | |
432 | if (q->ordcolor) | |
433 | rq->flags |= REQ_ORDERED_COLOR; | |
434 | ||
435 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { | |
436 | /* | |
437 | * toggle ordered color | |
438 | */ | |
439 | if (blk_barrier_rq(rq)) | |
440 | q->ordcolor ^= 1; | |
441 | ||
442 | /* | |
443 | * barriers implicitly indicate back insertion | |
444 | */ | |
445 | if (where == ELEVATOR_INSERT_SORT) | |
446 | where = ELEVATOR_INSERT_BACK; | |
447 | ||
448 | /* | |
449 | * this request is scheduling boundary, update | |
450 | * end_sector | |
451 | */ | |
452 | if (blk_fs_request(rq)) { | |
453 | q->end_sector = rq_end_sector(rq); | |
454 | q->boundary_rq = rq; | |
455 | } | |
456 | } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) | |
457 | where = ELEVATOR_INSERT_BACK; | |
458 | ||
459 | if (plug) | |
460 | blk_plug_device(q); | |
461 | ||
462 | elv_insert(q, rq, where); | |
463 | } | |
464 | ||
1da177e4 LT |
465 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
466 | int plug) | |
467 | { | |
468 | unsigned long flags; | |
469 | ||
470 | spin_lock_irqsave(q->queue_lock, flags); | |
471 | __elv_add_request(q, rq, where, plug); | |
472 | spin_unlock_irqrestore(q->queue_lock, flags); | |
473 | } | |
474 | ||
475 | static inline struct request *__elv_next_request(request_queue_t *q) | |
476 | { | |
8922e16c TH |
477 | struct request *rq; |
478 | ||
797e7dbb TH |
479 | while (1) { |
480 | while (!list_empty(&q->queue_head)) { | |
481 | rq = list_entry_rq(q->queue_head.next); | |
482 | if (blk_do_ordered(q, &rq)) | |
483 | return rq; | |
484 | } | |
1da177e4 | 485 | |
797e7dbb TH |
486 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
487 | return NULL; | |
1da177e4 | 488 | } |
1da177e4 LT |
489 | } |
490 | ||
491 | struct request *elv_next_request(request_queue_t *q) | |
492 | { | |
493 | struct request *rq; | |
494 | int ret; | |
495 | ||
496 | while ((rq = __elv_next_request(q)) != NULL) { | |
8922e16c TH |
497 | if (!(rq->flags & REQ_STARTED)) { |
498 | elevator_t *e = q->elevator; | |
499 | ||
500 | /* | |
501 | * This is the first time the device driver | |
502 | * sees this request (possibly after | |
503 | * requeueing). Notify IO scheduler. | |
504 | */ | |
505 | if (blk_sorted_rq(rq) && | |
506 | e->ops->elevator_activate_req_fn) | |
507 | e->ops->elevator_activate_req_fn(q, rq); | |
1da177e4 | 508 | |
8922e16c TH |
509 | /* |
510 | * just mark as started even if we don't start | |
511 | * it, a request that has been delayed should | |
512 | * not be passed by new incoming requests | |
513 | */ | |
514 | rq->flags |= REQ_STARTED; | |
2056a782 | 515 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 516 | } |
1da177e4 | 517 | |
8922e16c | 518 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 519 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
520 | q->boundary_rq = NULL; |
521 | } | |
1da177e4 LT |
522 | |
523 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) | |
524 | break; | |
525 | ||
526 | ret = q->prep_rq_fn(q, rq); | |
527 | if (ret == BLKPREP_OK) { | |
528 | break; | |
529 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
530 | /* |
531 | * the request may have been (partially) prepped. | |
532 | * we need to keep this request in the front to | |
8922e16c TH |
533 | * avoid resource deadlock. REQ_STARTED will |
534 | * prevent other fs requests from passing this one. | |
2e759cd4 | 535 | */ |
1da177e4 LT |
536 | rq = NULL; |
537 | break; | |
538 | } else if (ret == BLKPREP_KILL) { | |
539 | int nr_bytes = rq->hard_nr_sectors << 9; | |
540 | ||
541 | if (!nr_bytes) | |
542 | nr_bytes = rq->data_len; | |
543 | ||
544 | blkdev_dequeue_request(rq); | |
545 | rq->flags |= REQ_QUIET; | |
546 | end_that_request_chunk(rq, 0, nr_bytes); | |
8ffdc655 | 547 | end_that_request_last(rq, 0); |
1da177e4 LT |
548 | } else { |
549 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
550 | ret); | |
551 | break; | |
552 | } | |
553 | } | |
554 | ||
555 | return rq; | |
556 | } | |
557 | ||
8922e16c | 558 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 559 | { |
8922e16c TH |
560 | BUG_ON(list_empty(&rq->queuelist)); |
561 | ||
562 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
563 | |
564 | /* | |
565 | * the time frame between a request being removed from the lists | |
566 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 567 | * the driver side. |
1da177e4 LT |
568 | */ |
569 | if (blk_account_rq(rq)) | |
570 | q->in_flight++; | |
1da177e4 LT |
571 | } |
572 | ||
573 | int elv_queue_empty(request_queue_t *q) | |
574 | { | |
575 | elevator_t *e = q->elevator; | |
576 | ||
8922e16c TH |
577 | if (!list_empty(&q->queue_head)) |
578 | return 0; | |
579 | ||
1da177e4 LT |
580 | if (e->ops->elevator_queue_empty_fn) |
581 | return e->ops->elevator_queue_empty_fn(q); | |
582 | ||
8922e16c | 583 | return 1; |
1da177e4 LT |
584 | } |
585 | ||
586 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) | |
587 | { | |
1da177e4 LT |
588 | elevator_t *e = q->elevator; |
589 | ||
590 | if (e->ops->elevator_latter_req_fn) | |
591 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
592 | return NULL; |
593 | } | |
594 | ||
595 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
596 | { | |
1da177e4 LT |
597 | elevator_t *e = q->elevator; |
598 | ||
599 | if (e->ops->elevator_former_req_fn) | |
600 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
601 | return NULL; |
602 | } | |
603 | ||
22e2c507 | 604 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
8267e268 | 605 | gfp_t gfp_mask) |
1da177e4 LT |
606 | { |
607 | elevator_t *e = q->elevator; | |
608 | ||
609 | if (e->ops->elevator_set_req_fn) | |
22e2c507 | 610 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
611 | |
612 | rq->elevator_private = NULL; | |
613 | return 0; | |
614 | } | |
615 | ||
616 | void elv_put_request(request_queue_t *q, struct request *rq) | |
617 | { | |
618 | elevator_t *e = q->elevator; | |
619 | ||
620 | if (e->ops->elevator_put_req_fn) | |
621 | e->ops->elevator_put_req_fn(q, rq); | |
622 | } | |
623 | ||
22e2c507 | 624 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
625 | { |
626 | elevator_t *e = q->elevator; | |
627 | ||
628 | if (e->ops->elevator_may_queue_fn) | |
22e2c507 | 629 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
1da177e4 LT |
630 | |
631 | return ELV_MQUEUE_MAY; | |
632 | } | |
633 | ||
634 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
635 | { | |
636 | elevator_t *e = q->elevator; | |
637 | ||
638 | /* | |
639 | * request is released from the driver, io must be done | |
640 | */ | |
8922e16c | 641 | if (blk_account_rq(rq)) { |
1da177e4 | 642 | q->in_flight--; |
1bc691d3 TH |
643 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
644 | e->ops->elevator_completed_req_fn(q, rq); | |
645 | } | |
797e7dbb | 646 | |
1bc691d3 TH |
647 | /* |
648 | * Check if the queue is waiting for fs requests to be | |
649 | * drained for flush sequence. | |
650 | */ | |
651 | if (unlikely(q->ordseq)) { | |
652 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
653 | if (q->in_flight == 0 && | |
797e7dbb TH |
654 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
655 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
656 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
657 | q->request_fn(q); | |
658 | } | |
8922e16c | 659 | } |
1da177e4 LT |
660 | } |
661 | ||
3d1ab40f AV |
662 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
663 | ||
664 | static ssize_t | |
665 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 666 | { |
3d1ab40f AV |
667 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
668 | struct elv_fs_entry *entry = to_elv(attr); | |
669 | ssize_t error; | |
670 | ||
671 | if (!entry->show) | |
672 | return -EIO; | |
673 | ||
674 | mutex_lock(&e->sysfs_lock); | |
675 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
676 | mutex_unlock(&e->sysfs_lock); | |
677 | return error; | |
678 | } | |
1da177e4 | 679 | |
3d1ab40f AV |
680 | static ssize_t |
681 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
682 | const char *page, size_t length) | |
683 | { | |
684 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
685 | struct elv_fs_entry *entry = to_elv(attr); | |
686 | ssize_t error; | |
1da177e4 | 687 | |
3d1ab40f AV |
688 | if (!entry->store) |
689 | return -EIO; | |
1da177e4 | 690 | |
3d1ab40f AV |
691 | mutex_lock(&e->sysfs_lock); |
692 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
693 | mutex_unlock(&e->sysfs_lock); | |
694 | return error; | |
695 | } | |
696 | ||
697 | static struct sysfs_ops elv_sysfs_ops = { | |
698 | .show = elv_attr_show, | |
699 | .store = elv_attr_store, | |
700 | }; | |
701 | ||
702 | static struct kobj_type elv_ktype = { | |
703 | .sysfs_ops = &elv_sysfs_ops, | |
704 | .release = elevator_release, | |
705 | }; | |
706 | ||
707 | int elv_register_queue(struct request_queue *q) | |
708 | { | |
709 | elevator_t *e = q->elevator; | |
710 | int error; | |
711 | ||
712 | e->kobj.parent = &q->kobj; | |
713 | ||
714 | error = kobject_add(&e->kobj); | |
715 | if (!error) { | |
e572ec7e | 716 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 717 | if (attr) { |
e572ec7e AV |
718 | while (attr->attr.name) { |
719 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 720 | break; |
e572ec7e | 721 | attr++; |
3d1ab40f AV |
722 | } |
723 | } | |
724 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
725 | } | |
726 | return error; | |
1da177e4 LT |
727 | } |
728 | ||
bc1c1169 JA |
729 | static void __elv_unregister_queue(elevator_t *e) |
730 | { | |
731 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
732 | kobject_del(&e->kobj); | |
733 | } | |
734 | ||
1da177e4 LT |
735 | void elv_unregister_queue(struct request_queue *q) |
736 | { | |
bc1c1169 JA |
737 | if (q) |
738 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
739 | } |
740 | ||
741 | int elv_register(struct elevator_type *e) | |
742 | { | |
2824bc93 | 743 | spin_lock_irq(&elv_list_lock); |
ce524497 | 744 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 LT |
745 | list_add_tail(&e->list, &elv_list); |
746 | spin_unlock_irq(&elv_list_lock); | |
747 | ||
748 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
749 | if (!strcmp(e->elevator_name, chosen_elevator) || |
750 | (!*chosen_elevator && | |
751 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
752 | printk(" (default)"); | |
1da177e4 LT |
753 | printk("\n"); |
754 | return 0; | |
755 | } | |
756 | EXPORT_SYMBOL_GPL(elv_register); | |
757 | ||
758 | void elv_unregister(struct elevator_type *e) | |
759 | { | |
83521d3e CH |
760 | struct task_struct *g, *p; |
761 | ||
762 | /* | |
763 | * Iterate every thread in the process to remove the io contexts. | |
764 | */ | |
e17a9489 AV |
765 | if (e->ops.trim) { |
766 | read_lock(&tasklist_lock); | |
767 | do_each_thread(g, p) { | |
768 | task_lock(p); | |
769 | e->ops.trim(p->io_context); | |
770 | task_unlock(p); | |
771 | } while_each_thread(g, p); | |
772 | read_unlock(&tasklist_lock); | |
773 | } | |
83521d3e | 774 | |
1da177e4 LT |
775 | spin_lock_irq(&elv_list_lock); |
776 | list_del_init(&e->list); | |
777 | spin_unlock_irq(&elv_list_lock); | |
778 | } | |
779 | EXPORT_SYMBOL_GPL(elv_unregister); | |
780 | ||
781 | /* | |
782 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
783 | * we don't free the old io scheduler, before we have allocated what we | |
784 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 785 | * one, if the new one fails init for some reason. |
1da177e4 | 786 | */ |
3d1ab40f | 787 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
1da177e4 | 788 | { |
cb98fc8b | 789 | elevator_t *old_elevator, *e; |
bc1c1169 | 790 | void *data; |
1da177e4 | 791 | |
cb98fc8b TH |
792 | /* |
793 | * Allocate new elevator | |
794 | */ | |
3d1ab40f | 795 | e = elevator_alloc(new_e); |
1da177e4 | 796 | if (!e) |
3d1ab40f | 797 | return 0; |
1da177e4 | 798 | |
bc1c1169 JA |
799 | data = elevator_init_queue(q, e); |
800 | if (!data) { | |
801 | kobject_put(&e->kobj); | |
802 | return 0; | |
803 | } | |
804 | ||
1da177e4 | 805 | /* |
cb98fc8b | 806 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 807 | */ |
cb98fc8b TH |
808 | spin_lock_irq(q->queue_lock); |
809 | ||
64521d1a | 810 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
cb98fc8b | 811 | |
15853af9 | 812 | elv_drain_elevator(q); |
cb98fc8b TH |
813 | |
814 | while (q->rq.elvpriv) { | |
407df2aa TH |
815 | blk_remove_plug(q); |
816 | q->request_fn(q); | |
cb98fc8b | 817 | spin_unlock_irq(q->queue_lock); |
64521d1a | 818 | msleep(10); |
cb98fc8b | 819 | spin_lock_irq(q->queue_lock); |
15853af9 | 820 | elv_drain_elevator(q); |
cb98fc8b TH |
821 | } |
822 | ||
1da177e4 | 823 | /* |
bc1c1169 | 824 | * Remember old elevator. |
1da177e4 | 825 | */ |
1da177e4 LT |
826 | old_elevator = q->elevator; |
827 | ||
1da177e4 LT |
828 | /* |
829 | * attach and start new elevator | |
830 | */ | |
bc1c1169 JA |
831 | elevator_attach(q, e, data); |
832 | ||
833 | spin_unlock_irq(q->queue_lock); | |
834 | ||
835 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
836 | |
837 | if (elv_register_queue(q)) | |
838 | goto fail_register; | |
839 | ||
840 | /* | |
cb98fc8b | 841 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
842 | */ |
843 | elevator_exit(old_elevator); | |
64521d1a | 844 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 845 | return 1; |
1da177e4 LT |
846 | |
847 | fail_register: | |
848 | /* | |
849 | * switch failed, exit the new io scheduler and reattach the old | |
850 | * one again (along with re-adding the sysfs dir) | |
851 | */ | |
852 | elevator_exit(e); | |
cb98fc8b | 853 | e = NULL; |
1da177e4 LT |
854 | q->elevator = old_elevator; |
855 | elv_register_queue(q); | |
64521d1a | 856 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f AV |
857 | if (e) |
858 | kobject_put(&e->kobj); | |
859 | return 0; | |
1da177e4 LT |
860 | } |
861 | ||
862 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
863 | { | |
864 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 865 | size_t len; |
1da177e4 LT |
866 | struct elevator_type *e; |
867 | ||
be561235 TH |
868 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
869 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
870 | len = strlen(elevator_name); | |
1da177e4 | 871 | |
be561235 TH |
872 | if (len && elevator_name[len - 1] == '\n') |
873 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
874 | |
875 | e = elevator_get(elevator_name); | |
876 | if (!e) { | |
877 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
878 | return -EINVAL; | |
879 | } | |
880 | ||
2ca7d93b ND |
881 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
882 | elevator_put(e); | |
1da177e4 | 883 | return count; |
2ca7d93b | 884 | } |
1da177e4 | 885 | |
3d1ab40f AV |
886 | if (!elevator_switch(q, e)) |
887 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
888 | return count; |
889 | } | |
890 | ||
891 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
892 | { | |
893 | elevator_t *e = q->elevator; | |
894 | struct elevator_type *elv = e->elevator_type; | |
895 | struct list_head *entry; | |
896 | int len = 0; | |
897 | ||
898 | spin_lock_irq(q->queue_lock); | |
899 | list_for_each(entry, &elv_list) { | |
900 | struct elevator_type *__e; | |
901 | ||
902 | __e = list_entry(entry, struct elevator_type, list); | |
903 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
904 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
905 | else | |
906 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
907 | } | |
908 | spin_unlock_irq(q->queue_lock); | |
909 | ||
910 | len += sprintf(len+name, "\n"); | |
911 | return len; | |
912 | } | |
913 | ||
1b47f531 | 914 | EXPORT_SYMBOL(elv_dispatch_sort); |
1da177e4 LT |
915 | EXPORT_SYMBOL(elv_add_request); |
916 | EXPORT_SYMBOL(__elv_add_request); | |
1da177e4 | 917 | EXPORT_SYMBOL(elv_next_request); |
8922e16c | 918 | EXPORT_SYMBOL(elv_dequeue_request); |
1da177e4 | 919 | EXPORT_SYMBOL(elv_queue_empty); |
1da177e4 LT |
920 | EXPORT_SYMBOL(elevator_exit); |
921 | EXPORT_SYMBOL(elevator_init); |