Commit | Line | Data |
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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 | * | |
0fe23479 | 6 | * 30042000 Jens Axboe <axboe@kernel.dk> : |
1da177e4 LT |
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> |
5f3ea37c | 36 | #include <trace/block.h> |
9817064b | 37 | #include <linux/hash.h> |
0835da67 | 38 | #include <linux/uaccess.h> |
1da177e4 | 39 | |
242f9dcb JA |
40 | #include "blk.h" |
41 | ||
1da177e4 LT |
42 | static DEFINE_SPINLOCK(elv_list_lock); |
43 | static LIST_HEAD(elv_list); | |
44 | ||
0bfc2455 IM |
45 | DEFINE_TRACE(block_rq_abort); |
46 | ||
9817064b JA |
47 | /* |
48 | * Merge hash stuff. | |
49 | */ | |
50 | static const int elv_hash_shift = 6; | |
51 | #define ELV_HASH_BLOCK(sec) ((sec) >> 3) | |
4eb166d9 JA |
52 | #define ELV_HASH_FN(sec) \ |
53 | (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) | |
9817064b JA |
54 | #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
55 | #define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) | |
56 | #define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) | |
57 | ||
0bfc2455 IM |
58 | DEFINE_TRACE(block_rq_insert); |
59 | DEFINE_TRACE(block_rq_issue); | |
60 | ||
da775265 JA |
61 | /* |
62 | * Query io scheduler to see if the current process issuing bio may be | |
63 | * merged with rq. | |
64 | */ | |
65 | static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) | |
66 | { | |
165125e1 | 67 | struct request_queue *q = rq->q; |
da775265 JA |
68 | elevator_t *e = q->elevator; |
69 | ||
70 | if (e->ops->elevator_allow_merge_fn) | |
71 | return e->ops->elevator_allow_merge_fn(q, rq, bio); | |
72 | ||
73 | return 1; | |
74 | } | |
75 | ||
1da177e4 LT |
76 | /* |
77 | * can we safely merge with this request? | |
78 | */ | |
72ed0bf6 | 79 | int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 LT |
80 | { |
81 | if (!rq_mergeable(rq)) | |
82 | return 0; | |
83 | ||
e17fc0a1 DW |
84 | /* |
85 | * Don't merge file system requests and discard requests | |
86 | */ | |
87 | if (bio_discard(bio) != bio_discard(rq->bio)) | |
88 | return 0; | |
89 | ||
1da177e4 LT |
90 | /* |
91 | * different data direction or already started, don't merge | |
92 | */ | |
93 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
94 | return 0; | |
95 | ||
96 | /* | |
da775265 | 97 | * must be same device and not a special request |
1da177e4 | 98 | */ |
bb4067e3 | 99 | if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
da775265 JA |
100 | return 0; |
101 | ||
7ba1ba12 MP |
102 | /* |
103 | * only merge integrity protected bio into ditto rq | |
104 | */ | |
105 | if (bio_integrity(bio) != blk_integrity_rq(rq)) | |
106 | return 0; | |
107 | ||
da775265 JA |
108 | if (!elv_iosched_allow_merge(rq, bio)) |
109 | return 0; | |
1da177e4 | 110 | |
da775265 | 111 | return 1; |
1da177e4 LT |
112 | } |
113 | EXPORT_SYMBOL(elv_rq_merge_ok); | |
114 | ||
769db45b | 115 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
1da177e4 LT |
116 | { |
117 | int ret = ELEVATOR_NO_MERGE; | |
118 | ||
119 | /* | |
120 | * we can merge and sequence is ok, check if it's possible | |
121 | */ | |
122 | if (elv_rq_merge_ok(__rq, bio)) { | |
123 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) | |
124 | ret = ELEVATOR_BACK_MERGE; | |
125 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) | |
126 | ret = ELEVATOR_FRONT_MERGE; | |
127 | } | |
128 | ||
129 | return ret; | |
130 | } | |
1da177e4 | 131 | |
1da177e4 LT |
132 | static struct elevator_type *elevator_find(const char *name) |
133 | { | |
a22b169d | 134 | struct elevator_type *e; |
1da177e4 | 135 | |
70cee26e | 136 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
137 | if (!strcmp(e->elevator_name, name)) |
138 | return e; | |
1da177e4 | 139 | } |
1da177e4 | 140 | |
a22b169d | 141 | return NULL; |
1da177e4 LT |
142 | } |
143 | ||
144 | static void elevator_put(struct elevator_type *e) | |
145 | { | |
146 | module_put(e->elevator_owner); | |
147 | } | |
148 | ||
149 | static struct elevator_type *elevator_get(const char *name) | |
150 | { | |
2824bc93 | 151 | struct elevator_type *e; |
1da177e4 | 152 | |
2a12dcd7 | 153 | spin_lock(&elv_list_lock); |
2824bc93 TH |
154 | |
155 | e = elevator_find(name); | |
e1640949 JA |
156 | if (!e) { |
157 | char elv[ELV_NAME_MAX + strlen("-iosched")]; | |
158 | ||
159 | spin_unlock(&elv_list_lock); | |
160 | ||
161 | if (!strcmp(name, "anticipatory")) | |
162 | sprintf(elv, "as-iosched"); | |
163 | else | |
164 | sprintf(elv, "%s-iosched", name); | |
165 | ||
e180f594 | 166 | request_module("%s", elv); |
e1640949 JA |
167 | spin_lock(&elv_list_lock); |
168 | e = elevator_find(name); | |
169 | } | |
170 | ||
2824bc93 TH |
171 | if (e && !try_module_get(e->elevator_owner)) |
172 | e = NULL; | |
173 | ||
2a12dcd7 | 174 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
175 | |
176 | return e; | |
177 | } | |
178 | ||
165125e1 JA |
179 | static void *elevator_init_queue(struct request_queue *q, |
180 | struct elevator_queue *eq) | |
1da177e4 | 181 | { |
bb37b94c | 182 | return eq->ops->elevator_init_fn(q); |
bc1c1169 | 183 | } |
1da177e4 | 184 | |
165125e1 | 185 | static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
bc1c1169 JA |
186 | void *data) |
187 | { | |
1da177e4 | 188 | q->elevator = eq; |
bc1c1169 | 189 | eq->elevator_data = data; |
1da177e4 LT |
190 | } |
191 | ||
192 | static char chosen_elevator[16]; | |
193 | ||
5f003976 | 194 | static int __init elevator_setup(char *str) |
1da177e4 | 195 | { |
752a3b79 CE |
196 | /* |
197 | * Be backwards-compatible with previous kernels, so users | |
198 | * won't get the wrong elevator. | |
199 | */ | |
5f003976 | 200 | if (!strcmp(str, "as")) |
752a3b79 | 201 | strcpy(chosen_elevator, "anticipatory"); |
cff3ba22 | 202 | else |
5f003976 | 203 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 204 | return 1; |
1da177e4 LT |
205 | } |
206 | ||
207 | __setup("elevator=", elevator_setup); | |
208 | ||
3d1ab40f AV |
209 | static struct kobj_type elv_ktype; |
210 | ||
165125e1 JA |
211 | static elevator_t *elevator_alloc(struct request_queue *q, |
212 | struct elevator_type *e) | |
3d1ab40f | 213 | { |
9817064b JA |
214 | elevator_t *eq; |
215 | int i; | |
216 | ||
94f6030c | 217 | eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL | __GFP_ZERO, q->node); |
9817064b JA |
218 | if (unlikely(!eq)) |
219 | goto err; | |
220 | ||
9817064b JA |
221 | eq->ops = &e->ops; |
222 | eq->elevator_type = e; | |
f9cb074b | 223 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b JA |
224 | mutex_init(&eq->sysfs_lock); |
225 | ||
b5deef90 JA |
226 | eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
227 | GFP_KERNEL, q->node); | |
9817064b JA |
228 | if (!eq->hash) |
229 | goto err; | |
230 | ||
231 | for (i = 0; i < ELV_HASH_ENTRIES; i++) | |
232 | INIT_HLIST_HEAD(&eq->hash[i]); | |
233 | ||
3d1ab40f | 234 | return eq; |
9817064b JA |
235 | err: |
236 | kfree(eq); | |
237 | elevator_put(e); | |
238 | return NULL; | |
3d1ab40f AV |
239 | } |
240 | ||
241 | static void elevator_release(struct kobject *kobj) | |
242 | { | |
243 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
9817064b | 244 | |
3d1ab40f | 245 | elevator_put(e->elevator_type); |
9817064b | 246 | kfree(e->hash); |
3d1ab40f AV |
247 | kfree(e); |
248 | } | |
249 | ||
165125e1 | 250 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
251 | { |
252 | struct elevator_type *e = NULL; | |
253 | struct elevator_queue *eq; | |
254 | int ret = 0; | |
bc1c1169 | 255 | void *data; |
1da177e4 | 256 | |
cb98fc8b TH |
257 | INIT_LIST_HEAD(&q->queue_head); |
258 | q->last_merge = NULL; | |
259 | q->end_sector = 0; | |
260 | q->boundary_rq = NULL; | |
cb98fc8b | 261 | |
4eb166d9 JA |
262 | if (name) { |
263 | e = elevator_get(name); | |
264 | if (!e) | |
265 | return -EINVAL; | |
266 | } | |
1da177e4 | 267 | |
4eb166d9 JA |
268 | if (!e && *chosen_elevator) { |
269 | e = elevator_get(chosen_elevator); | |
270 | if (!e) | |
271 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
272 | chosen_elevator); | |
273 | } | |
248d5ca5 | 274 | |
4eb166d9 JA |
275 | if (!e) { |
276 | e = elevator_get(CONFIG_DEFAULT_IOSCHED); | |
277 | if (!e) { | |
278 | printk(KERN_ERR | |
279 | "Default I/O scheduler not found. " \ | |
280 | "Using noop.\n"); | |
281 | e = elevator_get("noop"); | |
282 | } | |
5f003976 ND |
283 | } |
284 | ||
b5deef90 | 285 | eq = elevator_alloc(q, e); |
3d1ab40f | 286 | if (!eq) |
1da177e4 | 287 | return -ENOMEM; |
1da177e4 | 288 | |
bc1c1169 JA |
289 | data = elevator_init_queue(q, eq); |
290 | if (!data) { | |
3d1ab40f | 291 | kobject_put(&eq->kobj); |
bc1c1169 JA |
292 | return -ENOMEM; |
293 | } | |
1da177e4 | 294 | |
bc1c1169 | 295 | elevator_attach(q, eq, data); |
1da177e4 LT |
296 | return ret; |
297 | } | |
2e662b65 JA |
298 | EXPORT_SYMBOL(elevator_init); |
299 | ||
1da177e4 LT |
300 | void elevator_exit(elevator_t *e) |
301 | { | |
3d1ab40f | 302 | mutex_lock(&e->sysfs_lock); |
1da177e4 LT |
303 | if (e->ops->elevator_exit_fn) |
304 | e->ops->elevator_exit_fn(e); | |
3d1ab40f AV |
305 | e->ops = NULL; |
306 | mutex_unlock(&e->sysfs_lock); | |
1da177e4 | 307 | |
3d1ab40f | 308 | kobject_put(&e->kobj); |
1da177e4 | 309 | } |
2e662b65 JA |
310 | EXPORT_SYMBOL(elevator_exit); |
311 | ||
165125e1 | 312 | static void elv_activate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
313 | { |
314 | elevator_t *e = q->elevator; | |
315 | ||
316 | if (e->ops->elevator_activate_req_fn) | |
317 | e->ops->elevator_activate_req_fn(q, rq); | |
318 | } | |
319 | ||
165125e1 | 320 | static void elv_deactivate_rq(struct request_queue *q, struct request *rq) |
cad97516 JA |
321 | { |
322 | elevator_t *e = q->elevator; | |
323 | ||
324 | if (e->ops->elevator_deactivate_req_fn) | |
325 | e->ops->elevator_deactivate_req_fn(q, rq); | |
326 | } | |
327 | ||
9817064b JA |
328 | static inline void __elv_rqhash_del(struct request *rq) |
329 | { | |
330 | hlist_del_init(&rq->hash); | |
331 | } | |
332 | ||
165125e1 | 333 | static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
334 | { |
335 | if (ELV_ON_HASH(rq)) | |
336 | __elv_rqhash_del(rq); | |
337 | } | |
338 | ||
165125e1 | 339 | static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b JA |
340 | { |
341 | elevator_t *e = q->elevator; | |
342 | ||
343 | BUG_ON(ELV_ON_HASH(rq)); | |
344 | hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); | |
345 | } | |
346 | ||
165125e1 | 347 | static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
348 | { |
349 | __elv_rqhash_del(rq); | |
350 | elv_rqhash_add(q, rq); | |
351 | } | |
352 | ||
165125e1 | 353 | static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b JA |
354 | { |
355 | elevator_t *e = q->elevator; | |
356 | struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; | |
357 | struct hlist_node *entry, *next; | |
358 | struct request *rq; | |
359 | ||
360 | hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { | |
361 | BUG_ON(!ELV_ON_HASH(rq)); | |
362 | ||
363 | if (unlikely(!rq_mergeable(rq))) { | |
364 | __elv_rqhash_del(rq); | |
365 | continue; | |
366 | } | |
367 | ||
368 | if (rq_hash_key(rq) == offset) | |
369 | return rq; | |
370 | } | |
371 | ||
372 | return NULL; | |
373 | } | |
374 | ||
2e662b65 JA |
375 | /* |
376 | * RB-tree support functions for inserting/lookup/removal of requests | |
377 | * in a sorted RB tree. | |
378 | */ | |
379 | struct request *elv_rb_add(struct rb_root *root, struct request *rq) | |
380 | { | |
381 | struct rb_node **p = &root->rb_node; | |
382 | struct rb_node *parent = NULL; | |
383 | struct request *__rq; | |
384 | ||
385 | while (*p) { | |
386 | parent = *p; | |
387 | __rq = rb_entry(parent, struct request, rb_node); | |
388 | ||
389 | if (rq->sector < __rq->sector) | |
390 | p = &(*p)->rb_left; | |
391 | else if (rq->sector > __rq->sector) | |
392 | p = &(*p)->rb_right; | |
393 | else | |
394 | return __rq; | |
395 | } | |
396 | ||
397 | rb_link_node(&rq->rb_node, parent, p); | |
398 | rb_insert_color(&rq->rb_node, root); | |
399 | return NULL; | |
400 | } | |
2e662b65 JA |
401 | EXPORT_SYMBOL(elv_rb_add); |
402 | ||
403 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
404 | { | |
405 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
406 | rb_erase(&rq->rb_node, root); | |
407 | RB_CLEAR_NODE(&rq->rb_node); | |
408 | } | |
2e662b65 JA |
409 | EXPORT_SYMBOL(elv_rb_del); |
410 | ||
411 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
412 | { | |
413 | struct rb_node *n = root->rb_node; | |
414 | struct request *rq; | |
415 | ||
416 | while (n) { | |
417 | rq = rb_entry(n, struct request, rb_node); | |
418 | ||
419 | if (sector < rq->sector) | |
420 | n = n->rb_left; | |
421 | else if (sector > rq->sector) | |
422 | n = n->rb_right; | |
423 | else | |
424 | return rq; | |
425 | } | |
426 | ||
427 | return NULL; | |
428 | } | |
2e662b65 JA |
429 | EXPORT_SYMBOL(elv_rb_find); |
430 | ||
8922e16c TH |
431 | /* |
432 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 433 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 434 | * specific elevators. |
8922e16c | 435 | */ |
165125e1 | 436 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
437 | { |
438 | sector_t boundary; | |
8922e16c | 439 | struct list_head *entry; |
4eb166d9 | 440 | int stop_flags; |
8922e16c | 441 | |
06b86245 TH |
442 | if (q->last_merge == rq) |
443 | q->last_merge = NULL; | |
9817064b JA |
444 | |
445 | elv_rqhash_del(q, rq); | |
446 | ||
15853af9 | 447 | q->nr_sorted--; |
06b86245 | 448 | |
1b47f531 | 449 | boundary = q->end_sector; |
4eb166d9 | 450 | stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED; |
8922e16c TH |
451 | list_for_each_prev(entry, &q->queue_head) { |
452 | struct request *pos = list_entry_rq(entry); | |
453 | ||
e17fc0a1 DW |
454 | if (blk_discard_rq(rq) != blk_discard_rq(pos)) |
455 | break; | |
783660b2 JA |
456 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
457 | break; | |
4eb166d9 | 458 | if (pos->cmd_flags & stop_flags) |
8922e16c TH |
459 | break; |
460 | if (rq->sector >= boundary) { | |
461 | if (pos->sector < boundary) | |
462 | continue; | |
463 | } else { | |
464 | if (pos->sector >= boundary) | |
465 | break; | |
466 | } | |
467 | if (rq->sector >= pos->sector) | |
468 | break; | |
469 | } | |
470 | ||
471 | list_add(&rq->queuelist, entry); | |
472 | } | |
2e662b65 JA |
473 | EXPORT_SYMBOL(elv_dispatch_sort); |
474 | ||
9817064b | 475 | /* |
2e662b65 JA |
476 | * Insert rq into dispatch queue of q. Queue lock must be held on |
477 | * entry. rq is added to the back of the dispatch queue. To be used by | |
478 | * specific elevators. | |
9817064b JA |
479 | */ |
480 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
481 | { | |
482 | if (q->last_merge == rq) | |
483 | q->last_merge = NULL; | |
484 | ||
485 | elv_rqhash_del(q, rq); | |
486 | ||
487 | q->nr_sorted--; | |
488 | ||
489 | q->end_sector = rq_end_sector(rq); | |
490 | q->boundary_rq = rq; | |
491 | list_add_tail(&rq->queuelist, &q->queue_head); | |
492 | } | |
2e662b65 JA |
493 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
494 | ||
165125e1 | 495 | int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
1da177e4 LT |
496 | { |
497 | elevator_t *e = q->elevator; | |
9817064b | 498 | struct request *__rq; |
06b86245 TH |
499 | int ret; |
500 | ||
9817064b JA |
501 | /* |
502 | * First try one-hit cache. | |
503 | */ | |
06b86245 TH |
504 | if (q->last_merge) { |
505 | ret = elv_try_merge(q->last_merge, bio); | |
506 | if (ret != ELEVATOR_NO_MERGE) { | |
507 | *req = q->last_merge; | |
508 | return ret; | |
509 | } | |
510 | } | |
1da177e4 | 511 | |
ac9fafa1 AB |
512 | if (blk_queue_nomerges(q)) |
513 | return ELEVATOR_NO_MERGE; | |
514 | ||
9817064b JA |
515 | /* |
516 | * See if our hash lookup can find a potential backmerge. | |
517 | */ | |
518 | __rq = elv_rqhash_find(q, bio->bi_sector); | |
519 | if (__rq && elv_rq_merge_ok(__rq, bio)) { | |
520 | *req = __rq; | |
521 | return ELEVATOR_BACK_MERGE; | |
522 | } | |
523 | ||
1da177e4 LT |
524 | if (e->ops->elevator_merge_fn) |
525 | return e->ops->elevator_merge_fn(q, req, bio); | |
526 | ||
527 | return ELEVATOR_NO_MERGE; | |
528 | } | |
529 | ||
165125e1 | 530 | void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
1da177e4 LT |
531 | { |
532 | elevator_t *e = q->elevator; | |
533 | ||
534 | if (e->ops->elevator_merged_fn) | |
2e662b65 | 535 | e->ops->elevator_merged_fn(q, rq, type); |
06b86245 | 536 | |
2e662b65 JA |
537 | if (type == ELEVATOR_BACK_MERGE) |
538 | elv_rqhash_reposition(q, rq); | |
9817064b | 539 | |
06b86245 | 540 | q->last_merge = rq; |
1da177e4 LT |
541 | } |
542 | ||
165125e1 | 543 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
544 | struct request *next) |
545 | { | |
546 | elevator_t *e = q->elevator; | |
547 | ||
1da177e4 LT |
548 | if (e->ops->elevator_merge_req_fn) |
549 | e->ops->elevator_merge_req_fn(q, rq, next); | |
06b86245 | 550 | |
9817064b JA |
551 | elv_rqhash_reposition(q, rq); |
552 | elv_rqhash_del(q, next); | |
553 | ||
554 | q->nr_sorted--; | |
06b86245 | 555 | q->last_merge = rq; |
1da177e4 LT |
556 | } |
557 | ||
165125e1 | 558 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 559 | { |
1da177e4 LT |
560 | /* |
561 | * it already went through dequeue, we need to decrement the | |
562 | * in_flight count again | |
563 | */ | |
8922e16c | 564 | if (blk_account_rq(rq)) { |
1da177e4 | 565 | q->in_flight--; |
cad97516 JA |
566 | if (blk_sorted_rq(rq)) |
567 | elv_deactivate_rq(q, rq); | |
8922e16c | 568 | } |
1da177e4 | 569 | |
4aff5e23 | 570 | rq->cmd_flags &= ~REQ_STARTED; |
1da177e4 | 571 | |
30e9656c | 572 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
573 | } |
574 | ||
165125e1 | 575 | static void elv_drain_elevator(struct request_queue *q) |
15853af9 TH |
576 | { |
577 | static int printed; | |
578 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) | |
579 | ; | |
580 | if (q->nr_sorted == 0) | |
581 | return; | |
582 | if (printed++ < 10) { | |
583 | printk(KERN_ERR "%s: forced dispatching is broken " | |
584 | "(nr_sorted=%u), please report this\n", | |
585 | q->elevator->elevator_type->elevator_name, q->nr_sorted); | |
586 | } | |
587 | } | |
588 | ||
165125e1 | 589 | void elv_insert(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 590 | { |
797e7dbb TH |
591 | struct list_head *pos; |
592 | unsigned ordseq; | |
dac07ec1 | 593 | int unplug_it = 1; |
797e7dbb | 594 | |
5f3ea37c | 595 | trace_block_rq_insert(q, rq); |
2056a782 | 596 | |
1da177e4 LT |
597 | rq->q = q; |
598 | ||
8922e16c TH |
599 | switch (where) { |
600 | case ELEVATOR_INSERT_FRONT: | |
4aff5e23 | 601 | rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16c TH |
602 | |
603 | list_add(&rq->queuelist, &q->queue_head); | |
604 | break; | |
605 | ||
606 | case ELEVATOR_INSERT_BACK: | |
4aff5e23 | 607 | rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9 | 608 | elv_drain_elevator(q); |
8922e16c TH |
609 | list_add_tail(&rq->queuelist, &q->queue_head); |
610 | /* | |
611 | * We kick the queue here for the following reasons. | |
612 | * - The elevator might have returned NULL previously | |
613 | * to delay requests and returned them now. As the | |
614 | * queue wasn't empty before this request, ll_rw_blk | |
615 | * won't run the queue on return, resulting in hang. | |
616 | * - Usually, back inserted requests won't be merged | |
617 | * with anything. There's no point in delaying queue | |
618 | * processing. | |
619 | */ | |
620 | blk_remove_plug(q); | |
80a4b58e | 621 | blk_start_queueing(q); |
8922e16c TH |
622 | break; |
623 | ||
624 | case ELEVATOR_INSERT_SORT: | |
e17fc0a1 | 625 | BUG_ON(!blk_fs_request(rq) && !blk_discard_rq(rq)); |
4aff5e23 | 626 | rq->cmd_flags |= REQ_SORTED; |
15853af9 | 627 | q->nr_sorted++; |
9817064b JA |
628 | if (rq_mergeable(rq)) { |
629 | elv_rqhash_add(q, rq); | |
630 | if (!q->last_merge) | |
631 | q->last_merge = rq; | |
632 | } | |
633 | ||
ca23509f TH |
634 | /* |
635 | * Some ioscheds (cfq) run q->request_fn directly, so | |
636 | * rq cannot be accessed after calling | |
637 | * elevator_add_req_fn. | |
638 | */ | |
639 | q->elevator->ops->elevator_add_req_fn(q, rq); | |
8922e16c TH |
640 | break; |
641 | ||
797e7dbb TH |
642 | case ELEVATOR_INSERT_REQUEUE: |
643 | /* | |
644 | * If ordered flush isn't in progress, we do front | |
645 | * insertion; otherwise, requests should be requeued | |
646 | * in ordseq order. | |
647 | */ | |
4aff5e23 | 648 | rq->cmd_flags |= REQ_SOFTBARRIER; |
797e7dbb | 649 | |
95543179 LV |
650 | /* |
651 | * Most requeues happen because of a busy condition, | |
652 | * don't force unplug of the queue for that case. | |
653 | */ | |
654 | unplug_it = 0; | |
655 | ||
797e7dbb TH |
656 | if (q->ordseq == 0) { |
657 | list_add(&rq->queuelist, &q->queue_head); | |
658 | break; | |
659 | } | |
660 | ||
661 | ordseq = blk_ordered_req_seq(rq); | |
662 | ||
663 | list_for_each(pos, &q->queue_head) { | |
664 | struct request *pos_rq = list_entry_rq(pos); | |
665 | if (ordseq <= blk_ordered_req_seq(pos_rq)) | |
666 | break; | |
667 | } | |
668 | ||
669 | list_add_tail(&rq->queuelist, pos); | |
670 | break; | |
671 | ||
8922e16c TH |
672 | default: |
673 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 674 | __func__, where); |
8922e16c TH |
675 | BUG(); |
676 | } | |
677 | ||
dac07ec1 | 678 | if (unplug_it && blk_queue_plugged(q)) { |
8922e16c TH |
679 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
680 | - q->in_flight; | |
681 | ||
682 | if (nrq >= q->unplug_thresh) | |
683 | __generic_unplug_device(q); | |
684 | } | |
1da177e4 LT |
685 | } |
686 | ||
165125e1 | 687 | void __elv_add_request(struct request_queue *q, struct request *rq, int where, |
30e9656c TH |
688 | int plug) |
689 | { | |
690 | if (q->ordcolor) | |
4aff5e23 | 691 | rq->cmd_flags |= REQ_ORDERED_COLOR; |
30e9656c | 692 | |
4aff5e23 | 693 | if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
30e9656c TH |
694 | /* |
695 | * toggle ordered color | |
696 | */ | |
697 | if (blk_barrier_rq(rq)) | |
698 | q->ordcolor ^= 1; | |
699 | ||
700 | /* | |
701 | * barriers implicitly indicate back insertion | |
702 | */ | |
703 | if (where == ELEVATOR_INSERT_SORT) | |
704 | where = ELEVATOR_INSERT_BACK; | |
705 | ||
706 | /* | |
707 | * this request is scheduling boundary, update | |
708 | * end_sector | |
709 | */ | |
e17fc0a1 | 710 | if (blk_fs_request(rq) || blk_discard_rq(rq)) { |
30e9656c TH |
711 | q->end_sector = rq_end_sector(rq); |
712 | q->boundary_rq = rq; | |
713 | } | |
4eb166d9 JA |
714 | } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
715 | where == ELEVATOR_INSERT_SORT) | |
30e9656c TH |
716 | where = ELEVATOR_INSERT_BACK; |
717 | ||
718 | if (plug) | |
719 | blk_plug_device(q); | |
720 | ||
721 | elv_insert(q, rq, where); | |
722 | } | |
2e662b65 JA |
723 | EXPORT_SYMBOL(__elv_add_request); |
724 | ||
165125e1 | 725 | void elv_add_request(struct request_queue *q, struct request *rq, int where, |
1da177e4 LT |
726 | int plug) |
727 | { | |
728 | unsigned long flags; | |
729 | ||
730 | spin_lock_irqsave(q->queue_lock, flags); | |
731 | __elv_add_request(q, rq, where, plug); | |
732 | spin_unlock_irqrestore(q->queue_lock, flags); | |
733 | } | |
2e662b65 JA |
734 | EXPORT_SYMBOL(elv_add_request); |
735 | ||
165125e1 | 736 | static inline struct request *__elv_next_request(struct request_queue *q) |
1da177e4 | 737 | { |
8922e16c TH |
738 | struct request *rq; |
739 | ||
797e7dbb TH |
740 | while (1) { |
741 | while (!list_empty(&q->queue_head)) { | |
742 | rq = list_entry_rq(q->queue_head.next); | |
743 | if (blk_do_ordered(q, &rq)) | |
744 | return rq; | |
745 | } | |
1da177e4 | 746 | |
797e7dbb TH |
747 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
748 | return NULL; | |
1da177e4 | 749 | } |
1da177e4 LT |
750 | } |
751 | ||
165125e1 | 752 | struct request *elv_next_request(struct request_queue *q) |
1da177e4 LT |
753 | { |
754 | struct request *rq; | |
755 | int ret; | |
756 | ||
757 | while ((rq = __elv_next_request(q)) != NULL) { | |
bf2de6f5 JA |
758 | /* |
759 | * Kill the empty barrier place holder, the driver must | |
760 | * not ever see it. | |
761 | */ | |
762 | if (blk_empty_barrier(rq)) { | |
99cd3386 | 763 | __blk_end_request(rq, 0, blk_rq_bytes(rq)); |
bf2de6f5 JA |
764 | continue; |
765 | } | |
4aff5e23 | 766 | if (!(rq->cmd_flags & REQ_STARTED)) { |
8922e16c TH |
767 | /* |
768 | * This is the first time the device driver | |
769 | * sees this request (possibly after | |
770 | * requeueing). Notify IO scheduler. | |
771 | */ | |
cad97516 JA |
772 | if (blk_sorted_rq(rq)) |
773 | elv_activate_rq(q, rq); | |
1da177e4 | 774 | |
8922e16c TH |
775 | /* |
776 | * just mark as started even if we don't start | |
777 | * it, a request that has been delayed should | |
778 | * not be passed by new incoming requests | |
779 | */ | |
4aff5e23 | 780 | rq->cmd_flags |= REQ_STARTED; |
5f3ea37c | 781 | trace_block_rq_issue(q, rq); |
8922e16c | 782 | } |
1da177e4 | 783 | |
8922e16c | 784 | if (!q->boundary_rq || q->boundary_rq == rq) { |
1b47f531 | 785 | q->end_sector = rq_end_sector(rq); |
8922e16c TH |
786 | q->boundary_rq = NULL; |
787 | } | |
1da177e4 | 788 | |
fa0ccd83 JB |
789 | if (rq->cmd_flags & REQ_DONTPREP) |
790 | break; | |
791 | ||
792 | if (q->dma_drain_size && rq->data_len) { | |
793 | /* | |
794 | * make sure space for the drain appears we | |
795 | * know we can do this because max_hw_segments | |
796 | * has been adjusted to be one fewer than the | |
797 | * device can handle | |
798 | */ | |
799 | rq->nr_phys_segments++; | |
fa0ccd83 JB |
800 | } |
801 | ||
802 | if (!q->prep_rq_fn) | |
1da177e4 LT |
803 | break; |
804 | ||
805 | ret = q->prep_rq_fn(q, rq); | |
806 | if (ret == BLKPREP_OK) { | |
807 | break; | |
808 | } else if (ret == BLKPREP_DEFER) { | |
2e759cd4 TH |
809 | /* |
810 | * the request may have been (partially) prepped. | |
811 | * we need to keep this request in the front to | |
8922e16c TH |
812 | * avoid resource deadlock. REQ_STARTED will |
813 | * prevent other fs requests from passing this one. | |
2e759cd4 | 814 | */ |
fa0ccd83 JB |
815 | if (q->dma_drain_size && rq->data_len && |
816 | !(rq->cmd_flags & REQ_DONTPREP)) { | |
817 | /* | |
818 | * remove the space for the drain we added | |
819 | * so that we don't add it again | |
820 | */ | |
821 | --rq->nr_phys_segments; | |
fa0ccd83 JB |
822 | } |
823 | ||
1da177e4 LT |
824 | rq = NULL; |
825 | break; | |
826 | } else if (ret == BLKPREP_KILL) { | |
4aff5e23 | 827 | rq->cmd_flags |= REQ_QUIET; |
99cd3386 | 828 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
1da177e4 | 829 | } else { |
24c03d47 | 830 | printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
1da177e4 LT |
831 | break; |
832 | } | |
833 | } | |
834 | ||
835 | return rq; | |
836 | } | |
2e662b65 JA |
837 | EXPORT_SYMBOL(elv_next_request); |
838 | ||
165125e1 | 839 | void elv_dequeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 840 | { |
8922e16c | 841 | BUG_ON(list_empty(&rq->queuelist)); |
9817064b | 842 | BUG_ON(ELV_ON_HASH(rq)); |
8922e16c TH |
843 | |
844 | list_del_init(&rq->queuelist); | |
1da177e4 LT |
845 | |
846 | /* | |
847 | * the time frame between a request being removed from the lists | |
848 | * and to it is freed is accounted as io that is in progress at | |
8922e16c | 849 | * the driver side. |
1da177e4 LT |
850 | */ |
851 | if (blk_account_rq(rq)) | |
852 | q->in_flight++; | |
1da177e4 | 853 | } |
2e662b65 | 854 | |
165125e1 | 855 | int elv_queue_empty(struct request_queue *q) |
1da177e4 LT |
856 | { |
857 | elevator_t *e = q->elevator; | |
858 | ||
8922e16c TH |
859 | if (!list_empty(&q->queue_head)) |
860 | return 0; | |
861 | ||
1da177e4 LT |
862 | if (e->ops->elevator_queue_empty_fn) |
863 | return e->ops->elevator_queue_empty_fn(q); | |
864 | ||
8922e16c | 865 | return 1; |
1da177e4 | 866 | } |
2e662b65 JA |
867 | EXPORT_SYMBOL(elv_queue_empty); |
868 | ||
165125e1 | 869 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 870 | { |
1da177e4 LT |
871 | elevator_t *e = q->elevator; |
872 | ||
873 | if (e->ops->elevator_latter_req_fn) | |
874 | return e->ops->elevator_latter_req_fn(q, rq); | |
1da177e4 LT |
875 | return NULL; |
876 | } | |
877 | ||
165125e1 | 878 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 879 | { |
1da177e4 LT |
880 | elevator_t *e = q->elevator; |
881 | ||
882 | if (e->ops->elevator_former_req_fn) | |
883 | return e->ops->elevator_former_req_fn(q, rq); | |
1da177e4 LT |
884 | return NULL; |
885 | } | |
886 | ||
165125e1 | 887 | int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
1da177e4 LT |
888 | { |
889 | elevator_t *e = q->elevator; | |
890 | ||
891 | if (e->ops->elevator_set_req_fn) | |
cb78b285 | 892 | return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
1da177e4 LT |
893 | |
894 | rq->elevator_private = NULL; | |
895 | return 0; | |
896 | } | |
897 | ||
165125e1 | 898 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
899 | { |
900 | elevator_t *e = q->elevator; | |
901 | ||
902 | if (e->ops->elevator_put_req_fn) | |
bb37b94c | 903 | e->ops->elevator_put_req_fn(rq); |
1da177e4 LT |
904 | } |
905 | ||
165125e1 | 906 | int elv_may_queue(struct request_queue *q, int rw) |
1da177e4 LT |
907 | { |
908 | elevator_t *e = q->elevator; | |
909 | ||
910 | if (e->ops->elevator_may_queue_fn) | |
cb78b285 | 911 | return e->ops->elevator_may_queue_fn(q, rw); |
1da177e4 LT |
912 | |
913 | return ELV_MQUEUE_MAY; | |
914 | } | |
915 | ||
11914a53 MA |
916 | void elv_abort_queue(struct request_queue *q) |
917 | { | |
918 | struct request *rq; | |
919 | ||
920 | while (!list_empty(&q->queue_head)) { | |
921 | rq = list_entry_rq(q->queue_head.next); | |
922 | rq->cmd_flags |= REQ_QUIET; | |
5f3ea37c | 923 | trace_block_rq_abort(q, rq); |
99cd3386 | 924 | __blk_end_request(rq, -EIO, blk_rq_bytes(rq)); |
11914a53 MA |
925 | } |
926 | } | |
927 | EXPORT_SYMBOL(elv_abort_queue); | |
928 | ||
165125e1 | 929 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 LT |
930 | { |
931 | elevator_t *e = q->elevator; | |
932 | ||
933 | /* | |
934 | * request is released from the driver, io must be done | |
935 | */ | |
8922e16c | 936 | if (blk_account_rq(rq)) { |
1da177e4 | 937 | q->in_flight--; |
1bc691d3 TH |
938 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
939 | e->ops->elevator_completed_req_fn(q, rq); | |
940 | } | |
797e7dbb | 941 | |
1bc691d3 TH |
942 | /* |
943 | * Check if the queue is waiting for fs requests to be | |
944 | * drained for flush sequence. | |
945 | */ | |
946 | if (unlikely(q->ordseq)) { | |
947 | struct request *first_rq = list_entry_rq(q->queue_head.next); | |
948 | if (q->in_flight == 0 && | |
797e7dbb TH |
949 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
950 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { | |
951 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); | |
80a4b58e | 952 | blk_start_queueing(q); |
797e7dbb | 953 | } |
8922e16c | 954 | } |
1da177e4 LT |
955 | } |
956 | ||
3d1ab40f AV |
957 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
958 | ||
959 | static ssize_t | |
960 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 961 | { |
3d1ab40f AV |
962 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
963 | struct elv_fs_entry *entry = to_elv(attr); | |
964 | ssize_t error; | |
965 | ||
966 | if (!entry->show) | |
967 | return -EIO; | |
968 | ||
969 | mutex_lock(&e->sysfs_lock); | |
970 | error = e->ops ? entry->show(e, page) : -ENOENT; | |
971 | mutex_unlock(&e->sysfs_lock); | |
972 | return error; | |
973 | } | |
1da177e4 | 974 | |
3d1ab40f AV |
975 | static ssize_t |
976 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
977 | const char *page, size_t length) | |
978 | { | |
979 | elevator_t *e = container_of(kobj, elevator_t, kobj); | |
980 | struct elv_fs_entry *entry = to_elv(attr); | |
981 | ssize_t error; | |
1da177e4 | 982 | |
3d1ab40f AV |
983 | if (!entry->store) |
984 | return -EIO; | |
1da177e4 | 985 | |
3d1ab40f AV |
986 | mutex_lock(&e->sysfs_lock); |
987 | error = e->ops ? entry->store(e, page, length) : -ENOENT; | |
988 | mutex_unlock(&e->sysfs_lock); | |
989 | return error; | |
990 | } | |
991 | ||
992 | static struct sysfs_ops elv_sysfs_ops = { | |
993 | .show = elv_attr_show, | |
994 | .store = elv_attr_store, | |
995 | }; | |
996 | ||
997 | static struct kobj_type elv_ktype = { | |
998 | .sysfs_ops = &elv_sysfs_ops, | |
999 | .release = elevator_release, | |
1000 | }; | |
1001 | ||
1002 | int elv_register_queue(struct request_queue *q) | |
1003 | { | |
1004 | elevator_t *e = q->elevator; | |
1005 | int error; | |
1006 | ||
b2d6db58 | 1007 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 1008 | if (!error) { |
e572ec7e | 1009 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
3d1ab40f | 1010 | if (attr) { |
e572ec7e AV |
1011 | while (attr->attr.name) { |
1012 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 1013 | break; |
e572ec7e | 1014 | attr++; |
3d1ab40f AV |
1015 | } |
1016 | } | |
1017 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
1018 | } | |
1019 | return error; | |
1da177e4 LT |
1020 | } |
1021 | ||
bc1c1169 JA |
1022 | static void __elv_unregister_queue(elevator_t *e) |
1023 | { | |
1024 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
1025 | kobject_del(&e->kobj); | |
1026 | } | |
1027 | ||
1da177e4 LT |
1028 | void elv_unregister_queue(struct request_queue *q) |
1029 | { | |
bc1c1169 JA |
1030 | if (q) |
1031 | __elv_unregister_queue(q->elevator); | |
1da177e4 LT |
1032 | } |
1033 | ||
2fdd82bd | 1034 | void elv_register(struct elevator_type *e) |
1da177e4 | 1035 | { |
1ffb96c5 | 1036 | char *def = ""; |
2a12dcd7 JA |
1037 | |
1038 | spin_lock(&elv_list_lock); | |
ce524497 | 1039 | BUG_ON(elevator_find(e->elevator_name)); |
1da177e4 | 1040 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 1041 | spin_unlock(&elv_list_lock); |
1da177e4 | 1042 | |
5f003976 ND |
1043 | if (!strcmp(e->elevator_name, chosen_elevator) || |
1044 | (!*chosen_elevator && | |
1045 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
1046 | def = " (default)"; |
1047 | ||
4eb166d9 JA |
1048 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
1049 | def); | |
1da177e4 LT |
1050 | } |
1051 | EXPORT_SYMBOL_GPL(elv_register); | |
1052 | ||
1053 | void elv_unregister(struct elevator_type *e) | |
1054 | { | |
83521d3e CH |
1055 | struct task_struct *g, *p; |
1056 | ||
1057 | /* | |
1058 | * Iterate every thread in the process to remove the io contexts. | |
1059 | */ | |
e17a9489 AV |
1060 | if (e->ops.trim) { |
1061 | read_lock(&tasklist_lock); | |
1062 | do_each_thread(g, p) { | |
1063 | task_lock(p); | |
2d8f6131 ON |
1064 | if (p->io_context) |
1065 | e->ops.trim(p->io_context); | |
e17a9489 AV |
1066 | task_unlock(p); |
1067 | } while_each_thread(g, p); | |
1068 | read_unlock(&tasklist_lock); | |
1069 | } | |
83521d3e | 1070 | |
2a12dcd7 | 1071 | spin_lock(&elv_list_lock); |
1da177e4 | 1072 | list_del_init(&e->list); |
2a12dcd7 | 1073 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1074 | } |
1075 | EXPORT_SYMBOL_GPL(elv_unregister); | |
1076 | ||
1077 | /* | |
1078 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
1079 | * we don't free the old io scheduler, before we have allocated what we | |
1080 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 1081 | * one, if the new one fails init for some reason. |
1da177e4 | 1082 | */ |
165125e1 | 1083 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 1084 | { |
cb98fc8b | 1085 | elevator_t *old_elevator, *e; |
bc1c1169 | 1086 | void *data; |
1da177e4 | 1087 | |
cb98fc8b TH |
1088 | /* |
1089 | * Allocate new elevator | |
1090 | */ | |
b5deef90 | 1091 | e = elevator_alloc(q, new_e); |
1da177e4 | 1092 | if (!e) |
3d1ab40f | 1093 | return 0; |
1da177e4 | 1094 | |
bc1c1169 JA |
1095 | data = elevator_init_queue(q, e); |
1096 | if (!data) { | |
1097 | kobject_put(&e->kobj); | |
1098 | return 0; | |
1099 | } | |
1100 | ||
1da177e4 | 1101 | /* |
cb98fc8b | 1102 | * Turn on BYPASS and drain all requests w/ elevator private data |
1da177e4 | 1103 | */ |
cb98fc8b TH |
1104 | spin_lock_irq(q->queue_lock); |
1105 | ||
75ad23bc | 1106 | queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
cb98fc8b | 1107 | |
15853af9 | 1108 | elv_drain_elevator(q); |
cb98fc8b TH |
1109 | |
1110 | while (q->rq.elvpriv) { | |
80a4b58e | 1111 | blk_start_queueing(q); |
cb98fc8b | 1112 | spin_unlock_irq(q->queue_lock); |
64521d1a | 1113 | msleep(10); |
cb98fc8b | 1114 | spin_lock_irq(q->queue_lock); |
15853af9 | 1115 | elv_drain_elevator(q); |
cb98fc8b TH |
1116 | } |
1117 | ||
1da177e4 | 1118 | /* |
bc1c1169 | 1119 | * Remember old elevator. |
1da177e4 | 1120 | */ |
1da177e4 LT |
1121 | old_elevator = q->elevator; |
1122 | ||
1da177e4 LT |
1123 | /* |
1124 | * attach and start new elevator | |
1125 | */ | |
bc1c1169 JA |
1126 | elevator_attach(q, e, data); |
1127 | ||
1128 | spin_unlock_irq(q->queue_lock); | |
1129 | ||
1130 | __elv_unregister_queue(old_elevator); | |
1da177e4 LT |
1131 | |
1132 | if (elv_register_queue(q)) | |
1133 | goto fail_register; | |
1134 | ||
1135 | /* | |
cb98fc8b | 1136 | * finally exit old elevator and turn off BYPASS. |
1da177e4 LT |
1137 | */ |
1138 | elevator_exit(old_elevator); | |
75ad23bc NP |
1139 | spin_lock_irq(q->queue_lock); |
1140 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1141 | spin_unlock_irq(q->queue_lock); | |
1142 | ||
4722dc52 AB |
1143 | blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
1144 | ||
3d1ab40f | 1145 | return 1; |
1da177e4 LT |
1146 | |
1147 | fail_register: | |
1148 | /* | |
1149 | * switch failed, exit the new io scheduler and reattach the old | |
1150 | * one again (along with re-adding the sysfs dir) | |
1151 | */ | |
1152 | elevator_exit(e); | |
1da177e4 LT |
1153 | q->elevator = old_elevator; |
1154 | elv_register_queue(q); | |
75ad23bc NP |
1155 | |
1156 | spin_lock_irq(q->queue_lock); | |
1157 | queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); | |
1158 | spin_unlock_irq(q->queue_lock); | |
1159 | ||
3d1ab40f | 1160 | return 0; |
1da177e4 LT |
1161 | } |
1162 | ||
165125e1 JA |
1163 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1164 | size_t count) | |
1da177e4 LT |
1165 | { |
1166 | char elevator_name[ELV_NAME_MAX]; | |
1167 | struct elevator_type *e; | |
1168 | ||
ee2e992c LZ |
1169 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
1170 | strstrip(elevator_name); | |
1da177e4 LT |
1171 | |
1172 | e = elevator_get(elevator_name); | |
1173 | if (!e) { | |
1174 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1175 | return -EINVAL; | |
1176 | } | |
1177 | ||
2ca7d93b ND |
1178 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
1179 | elevator_put(e); | |
1da177e4 | 1180 | return count; |
2ca7d93b | 1181 | } |
1da177e4 | 1182 | |
3d1ab40f | 1183 | if (!elevator_switch(q, e)) |
4eb166d9 JA |
1184 | printk(KERN_ERR "elevator: switch to %s failed\n", |
1185 | elevator_name); | |
1da177e4 LT |
1186 | return count; |
1187 | } | |
1188 | ||
165125e1 | 1189 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 LT |
1190 | { |
1191 | elevator_t *e = q->elevator; | |
1192 | struct elevator_type *elv = e->elevator_type; | |
70cee26e | 1193 | struct elevator_type *__e; |
1da177e4 LT |
1194 | int len = 0; |
1195 | ||
2a12dcd7 | 1196 | spin_lock(&elv_list_lock); |
70cee26e | 1197 | list_for_each_entry(__e, &elv_list, list) { |
1da177e4 LT |
1198 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
1199 | len += sprintf(name+len, "[%s] ", elv->elevator_name); | |
1200 | else | |
1201 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1202 | } | |
2a12dcd7 | 1203 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
1204 | |
1205 | len += sprintf(len+name, "\n"); | |
1206 | return len; | |
1207 | } | |
1208 | ||
165125e1 JA |
1209 | struct request *elv_rb_former_request(struct request_queue *q, |
1210 | struct request *rq) | |
2e662b65 JA |
1211 | { |
1212 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1213 | ||
1214 | if (rbprev) | |
1215 | return rb_entry_rq(rbprev); | |
1216 | ||
1217 | return NULL; | |
1218 | } | |
2e662b65 JA |
1219 | EXPORT_SYMBOL(elv_rb_former_request); |
1220 | ||
165125e1 JA |
1221 | struct request *elv_rb_latter_request(struct request_queue *q, |
1222 | struct request *rq) | |
2e662b65 JA |
1223 | { |
1224 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1225 | ||
1226 | if (rbnext) | |
1227 | return rb_entry_rq(rbnext); | |
1228 | ||
1229 | return NULL; | |
1230 | } | |
2e662b65 | 1231 | EXPORT_SYMBOL(elv_rb_latter_request); |