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> | |
1da177e4 LT |
30 | #include <linux/module.h> |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/compiler.h> | |
cb98fc8b | 34 | #include <linux/delay.h> |
2056a782 | 35 | #include <linux/blktrace_api.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 | ||
bc1c1169 | 123 | static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq) |
1da177e4 | 124 | { |
bc1c1169 JA |
125 | return eq->ops->elevator_init_fn(q, eq); |
126 | } | |
1da177e4 | 127 | |
bc1c1169 JA |
128 | static void elevator_attach(request_queue_t *q, struct elevator_queue *eq, |
129 | void *data) | |
130 | { | |
1da177e4 | 131 | q->elevator = eq; |
bc1c1169 | 132 | eq->elevator_data = data; |
1da177e4 LT |
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); |
9b41046c | 147 | return 1; |
1da177e4 LT |
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; | |
bc1c1169 | 183 | void *data; |
1da177e4 | 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 | |
bc1c1169 JA |
205 | data = elevator_init_queue(q, eq); |
206 | if (!data) { | |
3d1ab40f | 207 | kobject_put(&eq->kobj); |
bc1c1169 JA |
208 | return -ENOMEM; |
209 | } | |
1da177e4 | 210 | |
bc1c1169 | 211 | elevator_attach(q, eq, data); |
1da177e4 LT |
212 | return ret; |
213 | } | |
214 | ||
215 | void elevator_exit(elevator_t *e) | |
216 | { | |
3d1ab40f | 217 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
218 | if (e->ops->elevator_exit_fn) |
219 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
220 | e->ops = NULL; |
221 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 222 | |
3d1ab40f | 223 | kobject_put(&e->kobj); |
1da177e4 LT |
224 | } |
225 | ||
8922e16c TH |
226 | /* |
227 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
228 | * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be | |
229 | * appended to the dispatch queue. To be used by specific elevators. | |
230 | */ | |
1b47f531 | 231 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
8922e16c TH |
232 | { |
233 | sector_t boundary; | |
8922e16c TH |
234 | struct list_head *entry; |
235 | ||
06b86245 TH |
236 | if (q->last_merge == rq) |
237 | q->last_merge = NULL; | |
15853af9 | 238 | q->nr_sorted--; |
06b86245 | 239 | |
1b47f531 | 240 | boundary = q->end_sector; |
cb19833d | 241 | |
8922e16c TH |
242 | list_for_each_prev(entry, &q->queue_head) { |
243 | struct request *pos = list_entry_rq(entry); | |
244 | ||
245 | if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) | |
246 | break; | |
247 | if (rq->sector >= boundary) { | |
248 | if (pos->sector < boundary) | |
249 | continue; | |
250 | } else { | |
251 | if (pos->sector >= boundary) | |
252 | break; | |
253 | } | |
254 | if (rq->sector >= pos->sector) | |
255 | break; | |
256 | } | |
257 | ||
258 | list_add(&rq->queuelist, entry); | |
259 | } | |
260 | ||
1da177e4 LT |
261 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
262 | { | |
263 | elevator_t *e = q->elevator; | |
06b86245 TH |
264 | int ret; |
265 | ||
266 | if (q->last_merge) { | |
267 | ret = elv_try_merge(q->last_merge, bio); | |
268 | if (ret != ELEVATOR_NO_MERGE) { | |
269 | *req = q->last_merge; | |
270 | return ret; | |
271 | } | |
272 | } | |
1da177e4 LT |
273 | |
274 | if (e->ops->elevator_merge_fn) | |
275 | return e->ops->elevator_merge_fn(q, req, bio); | |
276 | ||
277 | return ELEVATOR_NO_MERGE; | |
278 | } | |
279 | ||
280 | void elv_merged_request(request_queue_t *q, struct request *rq) | |
281 | { | |
282 | elevator_t *e = q->elevator; | |
283 | ||
284 | if (e->ops->elevator_merged_fn) | |
285 | e->ops->elevator_merged_fn(q, rq); | |
06b86245 TH |
286 | |
287 | q->last_merge = rq; | |
1da177e4 LT |
288 | } |
289 | ||
290 | void elv_merge_requests(request_queue_t *q, struct request *rq, | |
291 | struct request *next) | |
292 | { | |
293 | elevator_t *e = q->elevator; | |
294 | ||
1da177e4 LT |
295 | if (e->ops->elevator_merge_req_fn) |
296 | e->ops->elevator_merge_req_fn(q, rq, next); | |
15853af9 | 297 | q->nr_sorted--; |
06b86245 TH |
298 | |
299 | q->last_merge = rq; | |
1da177e4 LT |
300 | } |
301 | ||
8922e16c | 302 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
1da177e4 LT |
303 | { |
304 | elevator_t *e = q->elevator; | |
305 | ||
306 | /* | |
307 | * it already went through dequeue, we need to decrement the | |
308 | * in_flight count again | |
309 | */ | |
8922e16c | 310 | if (blk_account_rq(rq)) { |
1da177e4 | 311 | q->in_flight--; |
8922e16c TH |
312 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
313 | e->ops->elevator_deactivate_req_fn(q, rq); | |
314 | } | |
1da177e4 LT |
315 | |
316 | rq->flags &= ~REQ_STARTED; | |
317 | ||
30e9656c | 318 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
319 | } |
320 | ||
15853af9 TH |
321 | static void elv_drain_elevator(request_queue_t *q) |
322 | { | |
323 | static int printed; | |
324 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
325 | ; | |
326 | if (q->nr_sorted == 0) | |
327 | return; | |
328 | if (printed++ < 10) { | |
329 | printk(KERN_ERR "%s: forced dispatching is broken " | |
330 | "(nr_sorted=%u), please report this\n", | |
331 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
332 | } | |
333 | } | |
334 | ||
30e9656c | 335 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
1da177e4 | 336 | { |
797e7dbb TH |
337 | struct list_head *pos; |
338 | unsigned ordseq; | |
dac07ec1 | 339 | int unplug_it = 1; |
797e7dbb | 340 | |
2056a782 JA |
341 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
342 | ||
1da177e4 LT |
343 | rq->q = q; |
344 | ||
8922e16c TH |
345 | switch (where) { |
346 | case ELEVATOR_INSERT_FRONT: | |
347 | rq->flags |= REQ_SOFTBARRIER; | |
348 | ||
349 | list_add(&rq->queuelist, &q->queue_head); | |
350 | break; | |
351 | ||
352 | case ELEVATOR_INSERT_BACK: | |
353 | rq->flags |= REQ_SOFTBARRIER; | |
15853af9 | 354 | elv_drain_elevator(q); |
8922e16c TH |
355 | list_add_tail(&rq->queuelist, &q->queue_head); |
356 | /* | |
357 | * We kick the queue here for the following reasons. | |
358 | * - The elevator might have returned NULL previously | |
359 | * to delay requests and returned them now. As the | |
360 | * queue wasn't empty before this request, ll_rw_blk | |
361 | * won't run the queue on return, resulting in hang. | |
362 | * - Usually, back inserted requests won't be merged | |
363 | * with anything. There's no point in delaying queue | |
364 | * processing. | |
365 | */ | |
366 | blk_remove_plug(q); | |
367 | q->request_fn(q); | |
368 | break; | |
369 | ||
370 | case ELEVATOR_INSERT_SORT: | |
371 | BUG_ON(!blk_fs_request(rq)); | |
372 | rq->flags |= REQ_SORTED; | |
15853af9 | 373 | q->nr_sorted++; |
06b86245 TH |
374 | if (q->last_merge == NULL && rq_mergeable(rq)) |
375 | q->last_merge = rq; | |
ca23509f TH |
376 | /* |
377 | * Some ioscheds (cfq) run q->request_fn directly, so | |
378 | * rq cannot be accessed after calling | |
379 | * elevator_add_req_fn. | |
380 | */ | |
381 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
382 | break; |
383 | ||
797e7dbb TH |
384 | case ELEVATOR_INSERT_REQUEUE: |
385 | /* | |
386 | * If ordered flush isn't in progress, we do front | |
387 | * insertion; otherwise, requests should be requeued | |
388 | * in ordseq order. | |
389 | */ | |
390 | rq->flags |= REQ_SOFTBARRIER; | |
391 | ||
392 | if (q->ordseq == 0) { | |
393 | list_add(&rq->queuelist, &q->queue_head); | |
394 | break; | |
395 | } | |
396 | ||
397 | ordseq = blk_ordered_req_seq(rq); | |
398 | ||
399 | list_for_each(pos, &q->queue_head) { | |
400 | struct request *pos_rq = list_entry_rq(pos); | |
401 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
402 | break; | |
403 | } | |
404 | ||
405 | list_add_tail(&rq->queuelist, pos); | |
dac07ec1 JA |
406 | /* |
407 | * most requeues happen because of a busy condition, don't | |
408 | * force unplug of the queue for that case. | |
409 | */ | |
410 | unplug_it = 0; | |
797e7dbb TH |
411 | break; |
412 | ||
8922e16c TH |
413 | default: |
414 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
415 | __FUNCTION__, where); | |
416 | BUG(); | |
417 | } | |
418 | ||
dac07ec1 | 419 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
420 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
421 | - q->in_flight; | |
422 | ||
423 | if (nrq >= q->unplug_thresh) | |
424 | __generic_unplug_device(q); | |
425 | } | |
1da177e4 LT |
426 | } |
427 | ||
30e9656c TH |
428 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
429 | int plug) | |
430 | { | |
431 | if (q->ordcolor) | |
432 | rq->flags |= REQ_ORDERED_COLOR; | |
433 | ||
434 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { | |
435 | /* | |
436 | * toggle ordered color | |
437 | */ | |
438 | if (blk_barrier_rq(rq)) | |
439 | q->ordcolor ^= 1; | |
440 | ||
441 | /* | |
442 | * barriers implicitly indicate back insertion | |
443 | */ | |
444 | if (where == ELEVATOR_INSERT_SORT) | |
445 | where = ELEVATOR_INSERT_BACK; | |
446 | ||
447 | /* | |
448 | * this request is scheduling boundary, update | |
449 | * end_sector | |
450 | */ | |
451 | if (blk_fs_request(rq)) { | |
452 | q->end_sector = rq_end_sector(rq); | |
453 | q->boundary_rq = rq; | |
454 | } | |
455 | } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) | |
456 | where = ELEVATOR_INSERT_BACK; | |
457 | ||
458 | if (plug) | |
459 | blk_plug_device(q); | |
460 | ||
461 | elv_insert(q, rq, where); | |
462 | } | |
463 | ||
1da177e4 LT |
464 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
465 | int plug) | |
466 | { | |
467 | unsigned long flags; | |
468 | ||
469 | spin_lock_irqsave(q->queue_lock, flags); | |
470 | __elv_add_request(q, rq, where, plug); | |
471 | spin_unlock_irqrestore(q->queue_lock, flags); | |
472 | } | |
473 | ||
474 | static inline struct request *__elv_next_request(request_queue_t *q) | |
475 | { | |
8922e16c TH |
476 | struct request *rq; |
477 | ||
797e7dbb TH |
478 | while (1) { |
479 | while (!list_empty(&q->queue_head)) { | |
480 | rq = list_entry_rq(q->queue_head.next); | |
481 | if (blk_do_ordered(q, &rq)) | |
482 | return rq; | |
483 | } | |
1da177e4 | 484 | |
797e7dbb TH |
485 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
486 | return NULL; | |
1da177e4 | 487 | } |
1da177e4 LT |
488 | } |
489 | ||
490 | struct request *elv_next_request(request_queue_t *q) | |
491 | { | |
492 | struct request *rq; | |
493 | int ret; | |
494 | ||
495 | while ((rq = __elv_next_request(q)) != NULL) { | |
8922e16c TH |
496 | if (!(rq->flags & REQ_STARTED)) { |
497 | elevator_t *e = q->elevator; | |
498 | ||
499 | /* | |
500 | * This is the first time the device driver | |
501 | * sees this request (possibly after | |
502 | * requeueing). Notify IO scheduler. | |
503 | */ | |
504 | if (blk_sorted_rq(rq) && | |
505 | e->ops->elevator_activate_req_fn) | |
506 | e->ops->elevator_activate_req_fn(q, rq); | |
1da177e4 | 507 | |
8922e16c TH |
508 | /* |
509 | * just mark as started even if we don't start | |
510 | * it, a request that has been delayed should | |
511 | * not be passed by new incoming requests | |
512 | */ | |
513 | rq->flags |= REQ_STARTED; | |
2056a782 | 514 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
8922e16c | 515 | } |
1da177e4 | 516 | |
8922e16c | 517 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 518 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
519 | q->boundary_rq = NULL; |
520 | } | |
1da177e4 LT |
521 | |
522 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) | |
523 | break; | |
524 | ||
525 | ret = q->prep_rq_fn(q, rq); | |
526 | if (ret == BLKPREP_OK) { | |
527 | break; | |
528 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
529 | /* |
530 | * the request may have been (partially) prepped. | |
531 | * we need to keep this request in the front to | |
8922e16c TH |
532 | * avoid resource deadlock. REQ_STARTED will |
533 | * prevent other fs requests from passing this one. | |
2e759cd4 | 534 | */ |
1da177e4 LT |
535 | rq = NULL; |
536 | break; | |
537 | } else if (ret == BLKPREP_KILL) { | |
538 | int nr_bytes = rq->hard_nr_sectors << 9; | |
539 | ||
540 | if (!nr_bytes) | |
541 | nr_bytes = rq->data_len; | |
542 | ||
543 | blkdev_dequeue_request(rq); | |
544 | rq->flags |= REQ_QUIET; | |
545 | end_that_request_chunk(rq, 0, nr_bytes); | |
8ffdc655 | 546 | end_that_request_last(rq, 0); |
1da177e4 LT |
547 | } else { |
548 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, | |
549 | ret); | |
550 | break; | |
551 | } | |
552 | } | |
553 | ||
554 | return rq; | |
555 | } | |
556 | ||
8922e16c | 557 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
1da177e4 | 558 | { |
8922e16c TH |
559 | BUG_ON(list_empty(&rq->queuelist)); |
560 | ||
561 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
562 | |
563 | /* | |
564 | * the time frame between a request being removed from the lists | |
565 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 566 | * the driver side. |
1da177e4 LT |
567 | */ |
568 | if (blk_account_rq(rq)) | |
569 | q->in_flight++; | |
1da177e4 LT |
570 | } |
571 | ||
572 | int elv_queue_empty(request_queue_t *q) | |
573 | { | |
574 | elevator_t *e = q->elevator; | |
575 | ||
8922e16c TH |
576 | if (!list_empty(&q->queue_head)) |
577 | return 0; | |
578 | ||
1da177e4 LT |
579 | if (e->ops->elevator_queue_empty_fn) |
580 | return e->ops->elevator_queue_empty_fn(q); | |
581 | ||
8922e16c | 582 | return 1; |
1da177e4 LT |
583 | } |
584 | ||
585 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) | |
586 | { | |
1da177e4 LT |
587 | elevator_t *e = q->elevator; |
588 | ||
589 | if (e->ops->elevator_latter_req_fn) | |
590 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
591 | return NULL; |
592 | } | |
593 | ||
594 | struct request *elv_former_request(request_queue_t *q, struct request *rq) | |
595 | { | |
1da177e4 LT |
596 | elevator_t *e = q->elevator; |
597 | ||
598 | if (e->ops->elevator_former_req_fn) | |
599 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
600 | return NULL; |
601 | } | |
602 | ||
22e2c507 | 603 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
8267e268 | 604 | gfp_t gfp_mask) |
1da177e4 LT |
605 | { |
606 | elevator_t *e = q->elevator; | |
607 | ||
608 | if (e->ops->elevator_set_req_fn) | |
22e2c507 | 609 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4 LT |
610 | |
611 | rq->elevator_private = NULL; | |
612 | return 0; | |
613 | } | |
614 | ||
615 | void elv_put_request(request_queue_t *q, struct request *rq) | |
616 | { | |
617 | elevator_t *e = q->elevator; | |
618 | ||
619 | if (e->ops->elevator_put_req_fn) | |
620 | e->ops->elevator_put_req_fn(q, rq); | |
621 | } | |
622 | ||
22e2c507 | 623 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
1da177e4 LT |
624 | { |
625 | elevator_t *e = q->elevator; | |
626 | ||
627 | if (e->ops->elevator_may_queue_fn) | |
22e2c507 | 628 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
1da177e4 LT |
629 | |
630 | return ELV_MQUEUE_MAY; | |
631 | } | |
632 | ||
633 | void elv_completed_request(request_queue_t *q, struct request *rq) | |
634 | { | |
635 | elevator_t *e = q->elevator; | |
636 | ||
637 | /* | |
638 | * request is released from the driver, io must be done | |
639 | */ | |
8922e16c | 640 | if (blk_account_rq(rq)) { |
1da177e4 | 641 | q->in_flight--; |
1bc691d3 TH |
642 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
643 | e->ops->elevator_completed_req_fn(q, rq); | |
644 | } | |
797e7dbb | 645 | |
1bc691d3 TH |
646 | /* |
647 | * Check if the queue is waiting for fs requests to be | |
648 | * drained for flush sequence. | |
649 | */ | |
650 | if (unlikely(q->ordseq)) { | |
651 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
652 | if (q->in_flight == 0 && | |
797e7dbb TH |
653 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
654 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
655 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
656 | q->request_fn(q); | |
657 | } | |
8922e16c | 658 | } |
1da177e4 LT |
659 | } |
660 | ||
3d1ab40f AV |
661 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
662 | ||
663 | static ssize_t | |
664 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 665 | { |
3d1ab40f AV |
666 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
667 | struct elv_fs_entry *entry = to_elv(attr); | |
668 | ssize_t error; | |
669 | ||
670 | if (!entry->show) | |
671 | return -EIO; | |
672 | ||
673 | mutex_lock(&e->sysfs_lock); | |
674 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
675 | mutex_unlock(&e->sysfs_lock); | |
676 | return error; | |
677 | } | |
1da177e4 | 678 | |
3d1ab40f AV |
679 | static ssize_t |
680 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
681 | const char *page, size_t length) | |
682 | { | |
683 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
684 | struct elv_fs_entry *entry = to_elv(attr); | |
685 | ssize_t error; | |
1da177e4 | 686 | |
3d1ab40f AV |
687 | if (!entry->store) |
688 | return -EIO; | |
1da177e4 | 689 | |
3d1ab40f AV |
690 | mutex_lock(&e->sysfs_lock); |
691 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
692 | mutex_unlock(&e->sysfs_lock); | |
693 | return error; | |
694 | } | |
695 | ||
696 | static struct sysfs_ops elv_sysfs_ops = { | |
697 | .show = elv_attr_show, | |
698 | .store = elv_attr_store, | |
699 | }; | |
700 | ||
701 | static struct kobj_type elv_ktype = { | |
702 | .sysfs_ops = &elv_sysfs_ops, | |
703 | .release = elevator_release, | |
704 | }; | |
705 | ||
706 | int elv_register_queue(struct request_queue *q) | |
707 | { | |
708 | elevator_t *e = q->elevator; | |
709 | int error; | |
710 | ||
711 | e->kobj.parent = &q->kobj; | |
712 | ||
713 | error = kobject_add(&e->kobj); | |
714 | if (!error) { | |
e572ec7e | 715 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 716 | if (attr) { |
e572ec7e AV |
717 | while (attr->attr.name) { |
718 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 719 | break; |
e572ec7e | 720 | attr++; |
3d1ab40f AV |
721 | } |
722 | } | |
723 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
724 | } | |
725 | return error; | |
1da177e4 LT |
726 | } |
727 | ||
bc1c1169 JA |
728 | static void __elv_unregister_queue(elevator_t *e) |
729 | { | |
730 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
731 | kobject_del(&e->kobj); | |
732 | } | |
733 | ||
1da177e4 LT |
734 | void elv_unregister_queue(struct request_queue *q) |
735 | { | |
bc1c1169 JA |
736 | if (q) |
737 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
738 | } |
739 | ||
740 | int elv_register(struct elevator_type *e) | |
741 | { | |
2824bc93 | 742 | spin_lock_irq(&elv_list_lock); |
ce524497 | 743 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 LT |
744 | list_add_tail(&e->list, &elv_list); |
745 | spin_unlock_irq(&elv_list_lock); | |
746 | ||
747 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); | |
5f003976 ND |
748 | if (!strcmp(e->elevator_name, chosen_elevator) || |
749 | (!*chosen_elevator && | |
750 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
751 | printk(" (default)"); | |
1da177e4 LT |
752 | printk("\n"); |
753 | return 0; | |
754 | } | |
755 | EXPORT_SYMBOL_GPL(elv_register); | |
756 | ||
757 | void elv_unregister(struct elevator_type *e) | |
758 | { | |
83521d3e CH |
759 | struct task_struct *g, *p; |
760 | ||
761 | /* | |
762 | * Iterate every thread in the process to remove the io contexts. | |
763 | */ | |
e17a9489 AV |
764 | if (e->ops.trim) { |
765 | read_lock(&tasklist_lock); | |
766 | do_each_thread(g, p) { | |
767 | task_lock(p); | |
2d8f6131 ON |
768 | if (p->io_context) |
769 | e->ops.trim(p->io_context); | |
e17a9489 AV |
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); | |
1da177e4 LT |
853 | q->elevator = old_elevator; |
854 | elv_register_queue(q); | |
64521d1a | 855 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
3d1ab40f | 856 | return 0; |
1da177e4 LT |
857 | } |
858 | ||
859 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) | |
860 | { | |
861 | char elevator_name[ELV_NAME_MAX]; | |
be561235 | 862 | size_t len; |
1da177e4 LT |
863 | struct elevator_type *e; |
864 | ||
be561235 TH |
865 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
866 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); | |
867 | len = strlen(elevator_name); | |
1da177e4 | 868 | |
be561235 TH |
869 | if (len && elevator_name[len - 1] == '\n') |
870 | elevator_name[len - 1] = '\0'; | |
1da177e4 LT |
871 | |
872 | e = elevator_get(elevator_name); | |
873 | if (!e) { | |
874 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
875 | return -EINVAL; | |
876 | } | |
877 | ||
2ca7d93b ND |
878 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
879 | elevator_put(e); | |
1da177e4 | 880 | return count; |
2ca7d93b | 881 | } |
1da177e4 | 882 | |
3d1ab40f AV |
883 | if (!elevator_switch(q, e)) |
884 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); | |
1da177e4 LT |
885 | return count; |
886 | } | |
887 | ||
888 | ssize_t elv_iosched_show(request_queue_t *q, char *name) | |
889 | { | |
890 | elevator_t *e = q->elevator; | |
891 | struct elevator_type *elv = e->elevator_type; | |
892 | struct list_head *entry; | |
893 | int len = 0; | |
894 | ||
895 | spin_lock_irq(q->queue_lock); | |
896 | list_for_each(entry, &elv_list) { | |
897 | struct elevator_type *__e; | |
898 | ||
899 | __e = list_entry(entry, struct elevator_type, list); | |
900 | if (!strcmp(elv->elevator_name, __e->elevator_name)) | |
901 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
902 | else | |
903 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
904 | } | |
905 | spin_unlock_irq(q->queue_lock); | |
906 | ||
907 | len += sprintf(len+name, "\n"); | |
908 | return len; | |
909 | } | |
910 | ||
1b47f531 | 911 | EXPORT_SYMBOL(elv_dispatch_sort); |
1da177e4 LT |
912 | EXPORT_SYMBOL(elv_add_request); |
913 | EXPORT_SYMBOL(__elv_add_request); | |
1da177e4 | 914 | EXPORT_SYMBOL(elv_next_request); |
8922e16c | 915 | EXPORT_SYMBOL(elv_dequeue_request); |
1da177e4 | 916 | EXPORT_SYMBOL(elv_queue_empty); |
1da177e4 LT |
917 | EXPORT_SYMBOL(elevator_exit); |
918 | EXPORT_SYMBOL(elevator_init); |