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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> | |
2056a782 | 34 | #include <linux/blktrace_api.h> |
9817064b | 35 | #include <linux/hash.h> |
0835da67 | 36 | #include <linux/uaccess.h> |
c8158819 | 37 | #include <linux/pm_runtime.h> |
eea8f41c | 38 | #include <linux/blk-cgroup.h> |
1da177e4 | 39 | |
55782138 LZ |
40 | #include <trace/events/block.h> |
41 | ||
242f9dcb | 42 | #include "blk.h" |
bd166ef1 | 43 | #include "blk-mq-sched.h" |
242f9dcb | 44 | |
1da177e4 LT |
45 | static DEFINE_SPINLOCK(elv_list_lock); |
46 | static LIST_HEAD(elv_list); | |
47 | ||
9817064b JA |
48 | /* |
49 | * Merge hash stuff. | |
50 | */ | |
83096ebf | 51 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 52 | |
da775265 JA |
53 | /* |
54 | * Query io scheduler to see if the current process issuing bio may be | |
55 | * merged with rq. | |
56 | */ | |
72ef799b | 57 | static int elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio) |
da775265 | 58 | { |
165125e1 | 59 | struct request_queue *q = rq->q; |
b374d18a | 60 | struct elevator_queue *e = q->elevator; |
da775265 | 61 | |
bd166ef1 JA |
62 | if (e->uses_mq && e->type->ops.mq.allow_merge) |
63 | return e->type->ops.mq.allow_merge(q, rq, bio); | |
64 | else if (!e->uses_mq && e->type->ops.sq.elevator_allow_bio_merge_fn) | |
c51ca6cf | 65 | return e->type->ops.sq.elevator_allow_bio_merge_fn(q, rq, bio); |
da775265 JA |
66 | |
67 | return 1; | |
68 | } | |
69 | ||
1da177e4 LT |
70 | /* |
71 | * can we safely merge with this request? | |
72 | */ | |
72ef799b | 73 | bool elv_bio_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 | 74 | { |
050c8ea8 | 75 | if (!blk_rq_merge_ok(rq, bio)) |
72ef799b | 76 | return false; |
7ba1ba12 | 77 | |
72ef799b TE |
78 | if (!elv_iosched_allow_bio_merge(rq, bio)) |
79 | return false; | |
1da177e4 | 80 | |
72ef799b | 81 | return true; |
1da177e4 | 82 | } |
72ef799b | 83 | EXPORT_SYMBOL(elv_bio_merge_ok); |
1da177e4 | 84 | |
1da177e4 LT |
85 | static struct elevator_type *elevator_find(const char *name) |
86 | { | |
a22b169d | 87 | struct elevator_type *e; |
1da177e4 | 88 | |
70cee26e | 89 | list_for_each_entry(e, &elv_list, list) { |
a22b169d VT |
90 | if (!strcmp(e->elevator_name, name)) |
91 | return e; | |
1da177e4 | 92 | } |
1da177e4 | 93 | |
a22b169d | 94 | return NULL; |
1da177e4 LT |
95 | } |
96 | ||
97 | static void elevator_put(struct elevator_type *e) | |
98 | { | |
99 | module_put(e->elevator_owner); | |
100 | } | |
101 | ||
21c3c5d2 | 102 | static struct elevator_type *elevator_get(const char *name, bool try_loading) |
1da177e4 | 103 | { |
2824bc93 | 104 | struct elevator_type *e; |
1da177e4 | 105 | |
2a12dcd7 | 106 | spin_lock(&elv_list_lock); |
2824bc93 TH |
107 | |
108 | e = elevator_find(name); | |
21c3c5d2 | 109 | if (!e && try_loading) { |
e1640949 | 110 | spin_unlock(&elv_list_lock); |
490b94be | 111 | request_module("%s-iosched", name); |
e1640949 JA |
112 | spin_lock(&elv_list_lock); |
113 | e = elevator_find(name); | |
114 | } | |
115 | ||
2824bc93 TH |
116 | if (e && !try_module_get(e->elevator_owner)) |
117 | e = NULL; | |
118 | ||
2a12dcd7 | 119 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
120 | |
121 | return e; | |
122 | } | |
123 | ||
484fc254 | 124 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 125 | |
5f003976 | 126 | static int __init elevator_setup(char *str) |
1da177e4 | 127 | { |
752a3b79 CE |
128 | /* |
129 | * Be backwards-compatible with previous kernels, so users | |
130 | * won't get the wrong elevator. | |
131 | */ | |
492af635 | 132 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 133 | return 1; |
1da177e4 LT |
134 | } |
135 | ||
136 | __setup("elevator=", elevator_setup); | |
137 | ||
bb813f4c TH |
138 | /* called during boot to load the elevator chosen by the elevator param */ |
139 | void __init load_default_elevator_module(void) | |
140 | { | |
141 | struct elevator_type *e; | |
142 | ||
143 | if (!chosen_elevator[0]) | |
144 | return; | |
145 | ||
146 | spin_lock(&elv_list_lock); | |
147 | e = elevator_find(chosen_elevator); | |
148 | spin_unlock(&elv_list_lock); | |
149 | ||
150 | if (!e) | |
151 | request_module("%s-iosched", chosen_elevator); | |
152 | } | |
153 | ||
3d1ab40f AV |
154 | static struct kobj_type elv_ktype; |
155 | ||
d50235b7 | 156 | struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 157 | struct elevator_type *e) |
3d1ab40f | 158 | { |
b374d18a | 159 | struct elevator_queue *eq; |
9817064b | 160 | |
c1b511eb | 161 | eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node); |
9817064b | 162 | if (unlikely(!eq)) |
8406a4d5 | 163 | return NULL; |
9817064b | 164 | |
22f746e2 | 165 | eq->type = e; |
f9cb074b | 166 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b | 167 | mutex_init(&eq->sysfs_lock); |
242d98f0 | 168 | hash_init(eq->hash); |
bd166ef1 | 169 | eq->uses_mq = e->uses_mq; |
9817064b | 170 | |
3d1ab40f AV |
171 | return eq; |
172 | } | |
d50235b7 | 173 | EXPORT_SYMBOL(elevator_alloc); |
3d1ab40f AV |
174 | |
175 | static void elevator_release(struct kobject *kobj) | |
176 | { | |
b374d18a | 177 | struct elevator_queue *e; |
9817064b | 178 | |
b374d18a | 179 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 180 | elevator_put(e->type); |
3d1ab40f AV |
181 | kfree(e); |
182 | } | |
183 | ||
165125e1 | 184 | int elevator_init(struct request_queue *q, char *name) |
1da177e4 LT |
185 | { |
186 | struct elevator_type *e = NULL; | |
f8fc877d | 187 | int err; |
1da177e4 | 188 | |
eb1c160b TS |
189 | /* |
190 | * q->sysfs_lock must be held to provide mutual exclusion between | |
191 | * elevator_switch() and here. | |
192 | */ | |
193 | lockdep_assert_held(&q->sysfs_lock); | |
194 | ||
1abec4fd MS |
195 | if (unlikely(q->elevator)) |
196 | return 0; | |
197 | ||
cb98fc8b TH |
198 | INIT_LIST_HEAD(&q->queue_head); |
199 | q->last_merge = NULL; | |
200 | q->end_sector = 0; | |
201 | q->boundary_rq = NULL; | |
cb98fc8b | 202 | |
4eb166d9 | 203 | if (name) { |
21c3c5d2 | 204 | e = elevator_get(name, true); |
4eb166d9 JA |
205 | if (!e) |
206 | return -EINVAL; | |
207 | } | |
1da177e4 | 208 | |
21c3c5d2 | 209 | /* |
d1a987f3 JA |
210 | * Use the default elevator specified by config boot param for |
211 | * non-mq devices, or by config option. Don't try to load modules | |
212 | * as we could be running off async and request_module() isn't | |
213 | * allowed from async. | |
21c3c5d2 | 214 | */ |
d1a987f3 | 215 | if (!e && !q->mq_ops && *chosen_elevator) { |
21c3c5d2 | 216 | e = elevator_get(chosen_elevator, false); |
4eb166d9 JA |
217 | if (!e) |
218 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
219 | chosen_elevator); | |
220 | } | |
248d5ca5 | 221 | |
4eb166d9 | 222 | if (!e) { |
b86dd815 JA |
223 | /* |
224 | * For blk-mq devices, we default to using mq-deadline, | |
225 | * if available, for single queue devices. If deadline | |
226 | * isn't available OR we have multiple queues, default | |
227 | * to "none". | |
228 | */ | |
229 | if (q->mq_ops) { | |
230 | if (q->nr_hw_queues == 1) | |
231 | e = elevator_get("mq-deadline", false); | |
232 | if (!e) | |
233 | return 0; | |
234 | } else | |
d3484991 JA |
235 | e = elevator_get(CONFIG_DEFAULT_IOSCHED, false); |
236 | ||
4eb166d9 JA |
237 | if (!e) { |
238 | printk(KERN_ERR | |
239 | "Default I/O scheduler not found. " \ | |
b86dd815 | 240 | "Using noop.\n"); |
21c3c5d2 | 241 | e = elevator_get("noop", false); |
4eb166d9 | 242 | } |
5f003976 ND |
243 | } |
244 | ||
6917ff0b OS |
245 | if (e->uses_mq) |
246 | err = blk_mq_init_sched(q, e); | |
247 | else | |
bd166ef1 | 248 | err = e->ops.sq.elevator_init_fn(q, e); |
6917ff0b | 249 | if (err) |
d32f6b57 SM |
250 | elevator_put(e); |
251 | return err; | |
1da177e4 | 252 | } |
2e662b65 JA |
253 | EXPORT_SYMBOL(elevator_init); |
254 | ||
54d5329d | 255 | void elevator_exit(struct request_queue *q, struct elevator_queue *e) |
1da177e4 | 256 | { |
3d1ab40f | 257 | mutex_lock(&e->sysfs_lock); |
bd166ef1 | 258 | if (e->uses_mq && e->type->ops.mq.exit_sched) |
54d5329d | 259 | blk_mq_exit_sched(q, e); |
bd166ef1 | 260 | else if (!e->uses_mq && e->type->ops.sq.elevator_exit_fn) |
c51ca6cf | 261 | e->type->ops.sq.elevator_exit_fn(e); |
3d1ab40f | 262 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 263 | |
3d1ab40f | 264 | kobject_put(&e->kobj); |
1da177e4 | 265 | } |
2e662b65 JA |
266 | EXPORT_SYMBOL(elevator_exit); |
267 | ||
9817064b JA |
268 | static inline void __elv_rqhash_del(struct request *rq) |
269 | { | |
242d98f0 | 270 | hash_del(&rq->hash); |
e8064021 | 271 | rq->rq_flags &= ~RQF_HASHED; |
9817064b JA |
272 | } |
273 | ||
70b3ea05 | 274 | void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
275 | { |
276 | if (ELV_ON_HASH(rq)) | |
277 | __elv_rqhash_del(rq); | |
278 | } | |
bd166ef1 | 279 | EXPORT_SYMBOL_GPL(elv_rqhash_del); |
9817064b | 280 | |
70b3ea05 | 281 | void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 282 | { |
b374d18a | 283 | struct elevator_queue *e = q->elevator; |
9817064b JA |
284 | |
285 | BUG_ON(ELV_ON_HASH(rq)); | |
242d98f0 | 286 | hash_add(e->hash, &rq->hash, rq_hash_key(rq)); |
e8064021 | 287 | rq->rq_flags |= RQF_HASHED; |
9817064b | 288 | } |
bd166ef1 | 289 | EXPORT_SYMBOL_GPL(elv_rqhash_add); |
9817064b | 290 | |
70b3ea05 | 291 | void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
292 | { |
293 | __elv_rqhash_del(rq); | |
294 | elv_rqhash_add(q, rq); | |
295 | } | |
296 | ||
70b3ea05 | 297 | struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 298 | { |
b374d18a | 299 | struct elevator_queue *e = q->elevator; |
b67bfe0d | 300 | struct hlist_node *next; |
9817064b JA |
301 | struct request *rq; |
302 | ||
ee89f812 | 303 | hash_for_each_possible_safe(e->hash, rq, next, hash, offset) { |
9817064b JA |
304 | BUG_ON(!ELV_ON_HASH(rq)); |
305 | ||
306 | if (unlikely(!rq_mergeable(rq))) { | |
307 | __elv_rqhash_del(rq); | |
308 | continue; | |
309 | } | |
310 | ||
311 | if (rq_hash_key(rq) == offset) | |
312 | return rq; | |
313 | } | |
314 | ||
315 | return NULL; | |
316 | } | |
317 | ||
2e662b65 JA |
318 | /* |
319 | * RB-tree support functions for inserting/lookup/removal of requests | |
320 | * in a sorted RB tree. | |
321 | */ | |
796d5116 | 322 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
323 | { |
324 | struct rb_node **p = &root->rb_node; | |
325 | struct rb_node *parent = NULL; | |
326 | struct request *__rq; | |
327 | ||
328 | while (*p) { | |
329 | parent = *p; | |
330 | __rq = rb_entry(parent, struct request, rb_node); | |
331 | ||
83096ebf | 332 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 333 | p = &(*p)->rb_left; |
796d5116 | 334 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 335 | p = &(*p)->rb_right; |
2e662b65 JA |
336 | } |
337 | ||
338 | rb_link_node(&rq->rb_node, parent, p); | |
339 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 340 | } |
2e662b65 JA |
341 | EXPORT_SYMBOL(elv_rb_add); |
342 | ||
343 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
344 | { | |
345 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
346 | rb_erase(&rq->rb_node, root); | |
347 | RB_CLEAR_NODE(&rq->rb_node); | |
348 | } | |
2e662b65 JA |
349 | EXPORT_SYMBOL(elv_rb_del); |
350 | ||
351 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
352 | { | |
353 | struct rb_node *n = root->rb_node; | |
354 | struct request *rq; | |
355 | ||
356 | while (n) { | |
357 | rq = rb_entry(n, struct request, rb_node); | |
358 | ||
83096ebf | 359 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 360 | n = n->rb_left; |
83096ebf | 361 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
362 | n = n->rb_right; |
363 | else | |
364 | return rq; | |
365 | } | |
366 | ||
367 | return NULL; | |
368 | } | |
2e662b65 JA |
369 | EXPORT_SYMBOL(elv_rb_find); |
370 | ||
8922e16c TH |
371 | /* |
372 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 373 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 374 | * specific elevators. |
8922e16c | 375 | */ |
165125e1 | 376 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
377 | { |
378 | sector_t boundary; | |
8922e16c TH |
379 | struct list_head *entry; |
380 | ||
06b86245 TH |
381 | if (q->last_merge == rq) |
382 | q->last_merge = NULL; | |
9817064b JA |
383 | |
384 | elv_rqhash_del(q, rq); | |
385 | ||
15853af9 | 386 | q->nr_sorted--; |
06b86245 | 387 | |
1b47f531 | 388 | boundary = q->end_sector; |
8922e16c TH |
389 | list_for_each_prev(entry, &q->queue_head) { |
390 | struct request *pos = list_entry_rq(entry); | |
391 | ||
7afafc8a | 392 | if (req_op(rq) != req_op(pos)) |
e17fc0a1 | 393 | break; |
783660b2 JA |
394 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
395 | break; | |
e8064021 | 396 | if (pos->rq_flags & (RQF_STARTED | RQF_SOFTBARRIER)) |
8922e16c | 397 | break; |
83096ebf TH |
398 | if (blk_rq_pos(rq) >= boundary) { |
399 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
400 | continue; |
401 | } else { | |
83096ebf | 402 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
403 | break; |
404 | } | |
83096ebf | 405 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
406 | break; |
407 | } | |
408 | ||
409 | list_add(&rq->queuelist, entry); | |
410 | } | |
2e662b65 JA |
411 | EXPORT_SYMBOL(elv_dispatch_sort); |
412 | ||
9817064b | 413 | /* |
2e662b65 JA |
414 | * Insert rq into dispatch queue of q. Queue lock must be held on |
415 | * entry. rq is added to the back of the dispatch queue. To be used by | |
416 | * specific elevators. | |
9817064b JA |
417 | */ |
418 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
419 | { | |
420 | if (q->last_merge == rq) | |
421 | q->last_merge = NULL; | |
422 | ||
423 | elv_rqhash_del(q, rq); | |
424 | ||
425 | q->nr_sorted--; | |
426 | ||
427 | q->end_sector = rq_end_sector(rq); | |
428 | q->boundary_rq = rq; | |
429 | list_add_tail(&rq->queuelist, &q->queue_head); | |
430 | } | |
2e662b65 JA |
431 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
432 | ||
34fe7c05 CH |
433 | enum elv_merge elv_merge(struct request_queue *q, struct request **req, |
434 | struct bio *bio) | |
1da177e4 | 435 | { |
b374d18a | 436 | struct elevator_queue *e = q->elevator; |
9817064b | 437 | struct request *__rq; |
06b86245 | 438 | |
488991e2 AB |
439 | /* |
440 | * Levels of merges: | |
441 | * nomerges: No merges at all attempted | |
442 | * noxmerges: Only simple one-hit cache try | |
443 | * merges: All merge tries attempted | |
444 | */ | |
7460d389 | 445 | if (blk_queue_nomerges(q) || !bio_mergeable(bio)) |
488991e2 AB |
446 | return ELEVATOR_NO_MERGE; |
447 | ||
9817064b JA |
448 | /* |
449 | * First try one-hit cache. | |
450 | */ | |
72ef799b | 451 | if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) { |
34fe7c05 CH |
452 | enum elv_merge ret = blk_try_merge(q->last_merge, bio); |
453 | ||
06b86245 TH |
454 | if (ret != ELEVATOR_NO_MERGE) { |
455 | *req = q->last_merge; | |
456 | return ret; | |
457 | } | |
458 | } | |
1da177e4 | 459 | |
488991e2 | 460 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
461 | return ELEVATOR_NO_MERGE; |
462 | ||
9817064b JA |
463 | /* |
464 | * See if our hash lookup can find a potential backmerge. | |
465 | */ | |
4f024f37 | 466 | __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); |
72ef799b | 467 | if (__rq && elv_bio_merge_ok(__rq, bio)) { |
9817064b JA |
468 | *req = __rq; |
469 | return ELEVATOR_BACK_MERGE; | |
470 | } | |
471 | ||
bd166ef1 JA |
472 | if (e->uses_mq && e->type->ops.mq.request_merge) |
473 | return e->type->ops.mq.request_merge(q, req, bio); | |
474 | else if (!e->uses_mq && e->type->ops.sq.elevator_merge_fn) | |
c51ca6cf | 475 | return e->type->ops.sq.elevator_merge_fn(q, req, bio); |
1da177e4 LT |
476 | |
477 | return ELEVATOR_NO_MERGE; | |
478 | } | |
479 | ||
5e84ea3a JA |
480 | /* |
481 | * Attempt to do an insertion back merge. Only check for the case where | |
482 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
483 | * afterwards. | |
484 | * | |
485 | * Returns true if we merged, false otherwise | |
486 | */ | |
bd166ef1 | 487 | bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq) |
5e84ea3a JA |
488 | { |
489 | struct request *__rq; | |
bee0393c | 490 | bool ret; |
5e84ea3a JA |
491 | |
492 | if (blk_queue_nomerges(q)) | |
493 | return false; | |
494 | ||
495 | /* | |
496 | * First try one-hit cache. | |
497 | */ | |
498 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
499 | return true; | |
500 | ||
501 | if (blk_queue_noxmerges(q)) | |
502 | return false; | |
503 | ||
bee0393c | 504 | ret = false; |
5e84ea3a JA |
505 | /* |
506 | * See if our hash lookup can find a potential backmerge. | |
507 | */ | |
bee0393c SL |
508 | while (1) { |
509 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
510 | if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) | |
511 | break; | |
512 | ||
513 | /* The merged request could be merged with others, try again */ | |
514 | ret = true; | |
515 | rq = __rq; | |
516 | } | |
27419322 | 517 | |
bee0393c | 518 | return ret; |
5e84ea3a JA |
519 | } |
520 | ||
34fe7c05 CH |
521 | void elv_merged_request(struct request_queue *q, struct request *rq, |
522 | enum elv_merge type) | |
1da177e4 | 523 | { |
b374d18a | 524 | struct elevator_queue *e = q->elevator; |
1da177e4 | 525 | |
bd166ef1 JA |
526 | if (e->uses_mq && e->type->ops.mq.request_merged) |
527 | e->type->ops.mq.request_merged(q, rq, type); | |
528 | else if (!e->uses_mq && e->type->ops.sq.elevator_merged_fn) | |
c51ca6cf | 529 | e->type->ops.sq.elevator_merged_fn(q, rq, type); |
06b86245 | 530 | |
2e662b65 JA |
531 | if (type == ELEVATOR_BACK_MERGE) |
532 | elv_rqhash_reposition(q, rq); | |
9817064b | 533 | |
06b86245 | 534 | q->last_merge = rq; |
1da177e4 LT |
535 | } |
536 | ||
165125e1 | 537 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
538 | struct request *next) |
539 | { | |
b374d18a | 540 | struct elevator_queue *e = q->elevator; |
bd166ef1 JA |
541 | bool next_sorted = false; |
542 | ||
543 | if (e->uses_mq && e->type->ops.mq.requests_merged) | |
544 | e->type->ops.mq.requests_merged(q, rq, next); | |
545 | else if (e->type->ops.sq.elevator_merge_req_fn) { | |
a1ae0f74 | 546 | next_sorted = (__force bool)(next->rq_flags & RQF_SORTED); |
bd166ef1 JA |
547 | if (next_sorted) |
548 | e->type->ops.sq.elevator_merge_req_fn(q, rq, next); | |
549 | } | |
06b86245 | 550 | |
9817064b | 551 | elv_rqhash_reposition(q, rq); |
9817064b | 552 | |
5e84ea3a JA |
553 | if (next_sorted) { |
554 | elv_rqhash_del(q, next); | |
555 | q->nr_sorted--; | |
556 | } | |
557 | ||
06b86245 | 558 | q->last_merge = rq; |
1da177e4 LT |
559 | } |
560 | ||
812d4026 DS |
561 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
562 | struct bio *bio) | |
563 | { | |
564 | struct elevator_queue *e = q->elevator; | |
565 | ||
bd166ef1 JA |
566 | if (WARN_ON_ONCE(e->uses_mq)) |
567 | return; | |
568 | ||
c51ca6cf JA |
569 | if (e->type->ops.sq.elevator_bio_merged_fn) |
570 | e->type->ops.sq.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
571 | } |
572 | ||
47fafbc7 | 573 | #ifdef CONFIG_PM |
c8158819 LM |
574 | static void blk_pm_requeue_request(struct request *rq) |
575 | { | |
e8064021 | 576 | if (rq->q->dev && !(rq->rq_flags & RQF_PM)) |
c8158819 LM |
577 | rq->q->nr_pending--; |
578 | } | |
579 | ||
580 | static void blk_pm_add_request(struct request_queue *q, struct request *rq) | |
581 | { | |
e8064021 | 582 | if (q->dev && !(rq->rq_flags & RQF_PM) && q->nr_pending++ == 0 && |
c8158819 LM |
583 | (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING)) |
584 | pm_request_resume(q->dev); | |
585 | } | |
586 | #else | |
587 | static inline void blk_pm_requeue_request(struct request *rq) {} | |
588 | static inline void blk_pm_add_request(struct request_queue *q, | |
589 | struct request *rq) | |
590 | { | |
591 | } | |
592 | #endif | |
593 | ||
165125e1 | 594 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 595 | { |
1da177e4 LT |
596 | /* |
597 | * it already went through dequeue, we need to decrement the | |
598 | * in_flight count again | |
599 | */ | |
8922e16c | 600 | if (blk_account_rq(rq)) { |
0a7ae2ff | 601 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 602 | if (rq->rq_flags & RQF_SORTED) |
cad97516 | 603 | elv_deactivate_rq(q, rq); |
8922e16c | 604 | } |
1da177e4 | 605 | |
e8064021 | 606 | rq->rq_flags &= ~RQF_STARTED; |
1da177e4 | 607 | |
c8158819 LM |
608 | blk_pm_requeue_request(rq); |
609 | ||
b710a480 | 610 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
611 | } |
612 | ||
26308eab | 613 | void elv_drain_elevator(struct request_queue *q) |
15853af9 | 614 | { |
bd166ef1 | 615 | struct elevator_queue *e = q->elevator; |
15853af9 | 616 | static int printed; |
e3c78ca5 | 617 | |
bd166ef1 JA |
618 | if (WARN_ON_ONCE(e->uses_mq)) |
619 | return; | |
620 | ||
e3c78ca5 TH |
621 | lockdep_assert_held(q->queue_lock); |
622 | ||
bd166ef1 | 623 | while (e->type->ops.sq.elevator_dispatch_fn(q, 1)) |
15853af9 | 624 | ; |
e3c78ca5 | 625 | if (q->nr_sorted && printed++ < 10) { |
15853af9 TH |
626 | printk(KERN_ERR "%s: forced dispatching is broken " |
627 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 628 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
629 | } |
630 | } | |
631 | ||
b710a480 | 632 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 633 | { |
5f3ea37c | 634 | trace_block_rq_insert(q, rq); |
2056a782 | 635 | |
c8158819 LM |
636 | blk_pm_add_request(q, rq); |
637 | ||
1da177e4 LT |
638 | rq->q = q; |
639 | ||
e8064021 | 640 | if (rq->rq_flags & RQF_SOFTBARRIER) { |
b710a480 | 641 | /* barriers are scheduling boundary, update end_sector */ |
57292b58 | 642 | if (!blk_rq_is_passthrough(rq)) { |
b710a480 JA |
643 | q->end_sector = rq_end_sector(rq); |
644 | q->boundary_rq = rq; | |
645 | } | |
e8064021 | 646 | } else if (!(rq->rq_flags & RQF_ELVPRIV) && |
3aa72873 JA |
647 | (where == ELEVATOR_INSERT_SORT || |
648 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
649 | where = ELEVATOR_INSERT_BACK; |
650 | ||
8922e16c | 651 | switch (where) { |
28e7d184 | 652 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 653 | case ELEVATOR_INSERT_FRONT: |
e8064021 | 654 | rq->rq_flags |= RQF_SOFTBARRIER; |
8922e16c TH |
655 | list_add(&rq->queuelist, &q->queue_head); |
656 | break; | |
657 | ||
658 | case ELEVATOR_INSERT_BACK: | |
e8064021 | 659 | rq->rq_flags |= RQF_SOFTBARRIER; |
15853af9 | 660 | elv_drain_elevator(q); |
8922e16c TH |
661 | list_add_tail(&rq->queuelist, &q->queue_head); |
662 | /* | |
663 | * We kick the queue here for the following reasons. | |
664 | * - The elevator might have returned NULL previously | |
665 | * to delay requests and returned them now. As the | |
666 | * queue wasn't empty before this request, ll_rw_blk | |
667 | * won't run the queue on return, resulting in hang. | |
668 | * - Usually, back inserted requests won't be merged | |
669 | * with anything. There's no point in delaying queue | |
670 | * processing. | |
671 | */ | |
24ecfbe2 | 672 | __blk_run_queue(q); |
8922e16c TH |
673 | break; |
674 | ||
5e84ea3a JA |
675 | case ELEVATOR_INSERT_SORT_MERGE: |
676 | /* | |
677 | * If we succeed in merging this request with one in the | |
678 | * queue already, we are done - rq has now been freed, | |
679 | * so no need to do anything further. | |
680 | */ | |
681 | if (elv_attempt_insert_merge(q, rq)) | |
682 | break; | |
8922e16c | 683 | case ELEVATOR_INSERT_SORT: |
57292b58 | 684 | BUG_ON(blk_rq_is_passthrough(rq)); |
e8064021 | 685 | rq->rq_flags |= RQF_SORTED; |
15853af9 | 686 | q->nr_sorted++; |
9817064b JA |
687 | if (rq_mergeable(rq)) { |
688 | elv_rqhash_add(q, rq); | |
689 | if (!q->last_merge) | |
690 | q->last_merge = rq; | |
691 | } | |
692 | ||
ca23509f TH |
693 | /* |
694 | * Some ioscheds (cfq) run q->request_fn directly, so | |
695 | * rq cannot be accessed after calling | |
696 | * elevator_add_req_fn. | |
697 | */ | |
c51ca6cf | 698 | q->elevator->type->ops.sq.elevator_add_req_fn(q, rq); |
8922e16c TH |
699 | break; |
700 | ||
ae1b1539 | 701 | case ELEVATOR_INSERT_FLUSH: |
e8064021 | 702 | rq->rq_flags |= RQF_SOFTBARRIER; |
ae1b1539 TH |
703 | blk_insert_flush(rq); |
704 | break; | |
8922e16c TH |
705 | default: |
706 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 707 | __func__, where); |
8922e16c TH |
708 | BUG(); |
709 | } | |
1da177e4 | 710 | } |
2e662b65 JA |
711 | EXPORT_SYMBOL(__elv_add_request); |
712 | ||
7eaceacc | 713 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
714 | { |
715 | unsigned long flags; | |
716 | ||
717 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 718 | __elv_add_request(q, rq, where); |
1da177e4 LT |
719 | spin_unlock_irqrestore(q->queue_lock, flags); |
720 | } | |
2e662b65 JA |
721 | EXPORT_SYMBOL(elv_add_request); |
722 | ||
165125e1 | 723 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 724 | { |
b374d18a | 725 | struct elevator_queue *e = q->elevator; |
1da177e4 | 726 | |
bd166ef1 JA |
727 | if (e->uses_mq && e->type->ops.mq.next_request) |
728 | return e->type->ops.mq.next_request(q, rq); | |
729 | else if (!e->uses_mq && e->type->ops.sq.elevator_latter_req_fn) | |
c51ca6cf | 730 | return e->type->ops.sq.elevator_latter_req_fn(q, rq); |
bd166ef1 | 731 | |
1da177e4 LT |
732 | return NULL; |
733 | } | |
734 | ||
165125e1 | 735 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 736 | { |
b374d18a | 737 | struct elevator_queue *e = q->elevator; |
1da177e4 | 738 | |
bd166ef1 JA |
739 | if (e->uses_mq && e->type->ops.mq.former_request) |
740 | return e->type->ops.mq.former_request(q, rq); | |
741 | if (!e->uses_mq && e->type->ops.sq.elevator_former_req_fn) | |
c51ca6cf | 742 | return e->type->ops.sq.elevator_former_req_fn(q, rq); |
1da177e4 LT |
743 | return NULL; |
744 | } | |
745 | ||
852c788f TH |
746 | int elv_set_request(struct request_queue *q, struct request *rq, |
747 | struct bio *bio, gfp_t gfp_mask) | |
1da177e4 | 748 | { |
b374d18a | 749 | struct elevator_queue *e = q->elevator; |
1da177e4 | 750 | |
bd166ef1 JA |
751 | if (WARN_ON_ONCE(e->uses_mq)) |
752 | return 0; | |
753 | ||
c51ca6cf JA |
754 | if (e->type->ops.sq.elevator_set_req_fn) |
755 | return e->type->ops.sq.elevator_set_req_fn(q, rq, bio, gfp_mask); | |
1da177e4 LT |
756 | return 0; |
757 | } | |
758 | ||
165125e1 | 759 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 760 | { |
b374d18a | 761 | struct elevator_queue *e = q->elevator; |
1da177e4 | 762 | |
bd166ef1 JA |
763 | if (WARN_ON_ONCE(e->uses_mq)) |
764 | return; | |
765 | ||
c51ca6cf JA |
766 | if (e->type->ops.sq.elevator_put_req_fn) |
767 | e->type->ops.sq.elevator_put_req_fn(rq); | |
1da177e4 LT |
768 | } |
769 | ||
ef295ecf | 770 | int elv_may_queue(struct request_queue *q, unsigned int op) |
1da177e4 | 771 | { |
b374d18a | 772 | struct elevator_queue *e = q->elevator; |
1da177e4 | 773 | |
bd166ef1 JA |
774 | if (WARN_ON_ONCE(e->uses_mq)) |
775 | return 0; | |
776 | ||
c51ca6cf JA |
777 | if (e->type->ops.sq.elevator_may_queue_fn) |
778 | return e->type->ops.sq.elevator_may_queue_fn(q, op); | |
1da177e4 LT |
779 | |
780 | return ELV_MQUEUE_MAY; | |
781 | } | |
782 | ||
165125e1 | 783 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 784 | { |
b374d18a | 785 | struct elevator_queue *e = q->elevator; |
1da177e4 | 786 | |
bd166ef1 JA |
787 | if (WARN_ON_ONCE(e->uses_mq)) |
788 | return; | |
789 | ||
1da177e4 LT |
790 | /* |
791 | * request is released from the driver, io must be done | |
792 | */ | |
8922e16c | 793 | if (blk_account_rq(rq)) { |
0a7ae2ff | 794 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 795 | if ((rq->rq_flags & RQF_SORTED) && |
c51ca6cf JA |
796 | e->type->ops.sq.elevator_completed_req_fn) |
797 | e->type->ops.sq.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 798 | } |
1da177e4 LT |
799 | } |
800 | ||
3d1ab40f AV |
801 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
802 | ||
803 | static ssize_t | |
804 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 805 | { |
3d1ab40f | 806 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 807 | struct elevator_queue *e; |
3d1ab40f AV |
808 | ssize_t error; |
809 | ||
810 | if (!entry->show) | |
811 | return -EIO; | |
812 | ||
b374d18a | 813 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 814 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 815 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
816 | mutex_unlock(&e->sysfs_lock); |
817 | return error; | |
818 | } | |
1da177e4 | 819 | |
3d1ab40f AV |
820 | static ssize_t |
821 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
822 | const char *page, size_t length) | |
823 | { | |
3d1ab40f | 824 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 825 | struct elevator_queue *e; |
3d1ab40f | 826 | ssize_t error; |
1da177e4 | 827 | |
3d1ab40f AV |
828 | if (!entry->store) |
829 | return -EIO; | |
1da177e4 | 830 | |
b374d18a | 831 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 832 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 833 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
834 | mutex_unlock(&e->sysfs_lock); |
835 | return error; | |
836 | } | |
837 | ||
52cf25d0 | 838 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
839 | .show = elv_attr_show, |
840 | .store = elv_attr_store, | |
841 | }; | |
842 | ||
843 | static struct kobj_type elv_ktype = { | |
844 | .sysfs_ops = &elv_sysfs_ops, | |
845 | .release = elevator_release, | |
846 | }; | |
847 | ||
5a5bafdc | 848 | int elv_register_queue(struct request_queue *q) |
3d1ab40f | 849 | { |
5a5bafdc | 850 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
851 | int error; |
852 | ||
b2d6db58 | 853 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 854 | if (!error) { |
22f746e2 | 855 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 856 | if (attr) { |
e572ec7e AV |
857 | while (attr->attr.name) { |
858 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 859 | break; |
e572ec7e | 860 | attr++; |
3d1ab40f AV |
861 | } |
862 | } | |
863 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 864 | e->registered = 1; |
bd166ef1 | 865 | if (!e->uses_mq && e->type->ops.sq.elevator_registered_fn) |
c51ca6cf | 866 | e->type->ops.sq.elevator_registered_fn(q); |
3d1ab40f AV |
867 | } |
868 | return error; | |
1da177e4 | 869 | } |
f8fc877d | 870 | EXPORT_SYMBOL(elv_register_queue); |
bc1c1169 | 871 | |
1da177e4 LT |
872 | void elv_unregister_queue(struct request_queue *q) |
873 | { | |
f8fc877d TH |
874 | if (q) { |
875 | struct elevator_queue *e = q->elevator; | |
876 | ||
877 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
878 | kobject_del(&e->kobj); | |
879 | e->registered = 0; | |
880 | } | |
1da177e4 | 881 | } |
01effb0d | 882 | EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4 | 883 | |
e567bf71 | 884 | int elv_register(struct elevator_type *e) |
1da177e4 | 885 | { |
1ffb96c5 | 886 | char *def = ""; |
2a12dcd7 | 887 | |
3d3c2379 TH |
888 | /* create icq_cache if requested */ |
889 | if (e->icq_size) { | |
890 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || | |
891 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) | |
892 | return -EINVAL; | |
893 | ||
894 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), | |
895 | "%s_io_cq", e->elevator_name); | |
896 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, | |
897 | e->icq_align, 0, NULL); | |
898 | if (!e->icq_cache) | |
899 | return -ENOMEM; | |
900 | } | |
901 | ||
902 | /* register, don't allow duplicate names */ | |
2a12dcd7 | 903 | spin_lock(&elv_list_lock); |
3d3c2379 TH |
904 | if (elevator_find(e->elevator_name)) { |
905 | spin_unlock(&elv_list_lock); | |
906 | if (e->icq_cache) | |
907 | kmem_cache_destroy(e->icq_cache); | |
908 | return -EBUSY; | |
909 | } | |
1da177e4 | 910 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 911 | spin_unlock(&elv_list_lock); |
1da177e4 | 912 | |
3d3c2379 | 913 | /* print pretty message */ |
5f003976 ND |
914 | if (!strcmp(e->elevator_name, chosen_elevator) || |
915 | (!*chosen_elevator && | |
916 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) | |
1ffb96c5 TV |
917 | def = " (default)"; |
918 | ||
4eb166d9 JA |
919 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
920 | def); | |
3d3c2379 | 921 | return 0; |
1da177e4 LT |
922 | } |
923 | EXPORT_SYMBOL_GPL(elv_register); | |
924 | ||
925 | void elv_unregister(struct elevator_type *e) | |
926 | { | |
3d3c2379 | 927 | /* unregister */ |
2a12dcd7 | 928 | spin_lock(&elv_list_lock); |
1da177e4 | 929 | list_del_init(&e->list); |
2a12dcd7 | 930 | spin_unlock(&elv_list_lock); |
3d3c2379 TH |
931 | |
932 | /* | |
933 | * Destroy icq_cache if it exists. icq's are RCU managed. Make | |
934 | * sure all RCU operations are complete before proceeding. | |
935 | */ | |
936 | if (e->icq_cache) { | |
937 | rcu_barrier(); | |
938 | kmem_cache_destroy(e->icq_cache); | |
939 | e->icq_cache = NULL; | |
940 | } | |
1da177e4 LT |
941 | } |
942 | EXPORT_SYMBOL_GPL(elv_unregister); | |
943 | ||
54d5329d OS |
944 | static int elevator_switch_mq(struct request_queue *q, |
945 | struct elevator_type *new_e) | |
946 | { | |
947 | int ret; | |
948 | ||
949 | blk_mq_freeze_queue(q); | |
950 | blk_mq_quiesce_queue(q); | |
951 | ||
952 | if (q->elevator) { | |
953 | if (q->elevator->registered) | |
954 | elv_unregister_queue(q); | |
955 | ioc_clear_queue(q); | |
956 | elevator_exit(q, q->elevator); | |
957 | } | |
958 | ||
959 | ret = blk_mq_init_sched(q, new_e); | |
960 | if (ret) | |
961 | goto out; | |
962 | ||
963 | if (new_e) { | |
964 | ret = elv_register_queue(q); | |
965 | if (ret) { | |
966 | elevator_exit(q, q->elevator); | |
967 | goto out; | |
968 | } | |
969 | } | |
970 | ||
971 | if (new_e) | |
972 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); | |
973 | else | |
974 | blk_add_trace_msg(q, "elv switch: none"); | |
975 | ||
976 | out: | |
977 | blk_mq_unfreeze_queue(q); | |
978 | blk_mq_start_stopped_hw_queues(q, true); | |
979 | return ret; | |
980 | ||
981 | } | |
982 | ||
1da177e4 LT |
983 | /* |
984 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
985 | * we don't free the old io scheduler, before we have allocated what we | |
986 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 987 | * one, if the new one fails init for some reason. |
1da177e4 | 988 | */ |
165125e1 | 989 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 990 | { |
5a5bafdc | 991 | struct elevator_queue *old = q->elevator; |
bd166ef1 | 992 | bool old_registered = false; |
e8989fae | 993 | int err; |
1da177e4 | 994 | |
54d5329d OS |
995 | if (q->mq_ops) |
996 | return elevator_switch_mq(q, new_e); | |
bd166ef1 | 997 | |
5a5bafdc TH |
998 | /* |
999 | * Turn on BYPASS and drain all requests w/ elevator private data. | |
1000 | * Block layer doesn't call into a quiesced elevator - all requests | |
1001 | * are directly put on the dispatch list without elevator data | |
1002 | * using INSERT_BACK. All requests have SOFTBARRIER set and no | |
1003 | * merge happens either. | |
1004 | */ | |
bd166ef1 JA |
1005 | if (old) { |
1006 | old_registered = old->registered; | |
1007 | ||
54d5329d | 1008 | blk_queue_bypass_start(q); |
1da177e4 | 1009 | |
bd166ef1 JA |
1010 | /* unregister and clear all auxiliary data of the old elevator */ |
1011 | if (old_registered) | |
1012 | elv_unregister_queue(q); | |
1013 | ||
bd166ef1 | 1014 | ioc_clear_queue(q); |
bd166ef1 | 1015 | } |
f8fc877d | 1016 | |
5a5bafdc | 1017 | /* allocate, init and register new elevator */ |
54d5329d | 1018 | err = new_e->ops.sq.elevator_init_fn(q, new_e); |
6917ff0b OS |
1019 | if (err) |
1020 | goto fail_init; | |
5a5bafdc | 1021 | |
54d5329d OS |
1022 | err = elv_register_queue(q); |
1023 | if (err) | |
1024 | goto fail_register; | |
5a5bafdc TH |
1025 | |
1026 | /* done, kill the old one and finish */ | |
bd166ef1 | 1027 | if (old) { |
54d5329d OS |
1028 | elevator_exit(q, old); |
1029 | blk_queue_bypass_end(q); | |
bd166ef1 JA |
1030 | } |
1031 | ||
54d5329d | 1032 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52 | 1033 | |
5dd531a0 | 1034 | return 0; |
1da177e4 LT |
1035 | |
1036 | fail_register: | |
54d5329d | 1037 | elevator_exit(q, q->elevator); |
5a5bafdc TH |
1038 | fail_init: |
1039 | /* switch failed, restore and re-register old elevator */ | |
bd166ef1 JA |
1040 | if (old) { |
1041 | q->elevator = old; | |
1042 | elv_register_queue(q); | |
54d5329d | 1043 | blk_queue_bypass_end(q); |
bd166ef1 | 1044 | } |
75ad23bc | 1045 | |
5dd531a0 | 1046 | return err; |
1da177e4 LT |
1047 | } |
1048 | ||
5dd531a0 JA |
1049 | /* |
1050 | * Switch this queue to the given IO scheduler. | |
1051 | */ | |
7c8a3679 | 1052 | static int __elevator_change(struct request_queue *q, const char *name) |
1da177e4 LT |
1053 | { |
1054 | char elevator_name[ELV_NAME_MAX]; | |
1055 | struct elevator_type *e; | |
1056 | ||
bd166ef1 JA |
1057 | /* |
1058 | * Special case for mq, turn off scheduling | |
1059 | */ | |
1060 | if (q->mq_ops && !strncmp(name, "none", 4)) | |
1061 | return elevator_switch(q, NULL); | |
cd43e26f | 1062 | |
ee2e992c | 1063 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
21c3c5d2 | 1064 | e = elevator_get(strstrip(elevator_name), true); |
1da177e4 LT |
1065 | if (!e) { |
1066 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); | |
1067 | return -EINVAL; | |
1068 | } | |
1069 | ||
bd166ef1 JA |
1070 | if (q->elevator && |
1071 | !strcmp(elevator_name, q->elevator->type->elevator_name)) { | |
2ca7d93b | 1072 | elevator_put(e); |
5dd531a0 | 1073 | return 0; |
2ca7d93b | 1074 | } |
1da177e4 | 1075 | |
bd166ef1 JA |
1076 | if (!e->uses_mq && q->mq_ops) { |
1077 | elevator_put(e); | |
1078 | return -EINVAL; | |
1079 | } | |
1080 | if (e->uses_mq && !q->mq_ops) { | |
1081 | elevator_put(e); | |
1082 | return -EINVAL; | |
1083 | } | |
1084 | ||
5dd531a0 JA |
1085 | return elevator_switch(q, e); |
1086 | } | |
7c8a3679 TS |
1087 | |
1088 | int elevator_change(struct request_queue *q, const char *name) | |
1089 | { | |
1090 | int ret; | |
1091 | ||
1092 | /* Protect q->elevator from elevator_init() */ | |
1093 | mutex_lock(&q->sysfs_lock); | |
1094 | ret = __elevator_change(q, name); | |
1095 | mutex_unlock(&q->sysfs_lock); | |
1096 | ||
1097 | return ret; | |
1098 | } | |
5dd531a0 JA |
1099 | EXPORT_SYMBOL(elevator_change); |
1100 | ||
1101 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, | |
1102 | size_t count) | |
1103 | { | |
1104 | int ret; | |
1105 | ||
bd166ef1 | 1106 | if (!(q->mq_ops || q->request_fn)) |
5dd531a0 JA |
1107 | return count; |
1108 | ||
7c8a3679 | 1109 | ret = __elevator_change(q, name); |
5dd531a0 JA |
1110 | if (!ret) |
1111 | return count; | |
1112 | ||
1113 | printk(KERN_ERR "elevator: switch to %s failed\n", name); | |
1114 | return ret; | |
1da177e4 LT |
1115 | } |
1116 | ||
165125e1 | 1117 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1118 | { |
b374d18a | 1119 | struct elevator_queue *e = q->elevator; |
bd166ef1 | 1120 | struct elevator_type *elv = NULL; |
70cee26e | 1121 | struct elevator_type *__e; |
1da177e4 LT |
1122 | int len = 0; |
1123 | ||
bd166ef1 | 1124 | if (!blk_queue_stackable(q)) |
cd43e26f MP |
1125 | return sprintf(name, "none\n"); |
1126 | ||
bd166ef1 JA |
1127 | if (!q->elevator) |
1128 | len += sprintf(name+len, "[none] "); | |
1129 | else | |
1130 | elv = e->type; | |
cd43e26f | 1131 | |
2a12dcd7 | 1132 | spin_lock(&elv_list_lock); |
70cee26e | 1133 | list_for_each_entry(__e, &elv_list, list) { |
bd166ef1 | 1134 | if (elv && !strcmp(elv->elevator_name, __e->elevator_name)) { |
1da177e4 | 1135 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
bd166ef1 JA |
1136 | continue; |
1137 | } | |
1138 | if (__e->uses_mq && q->mq_ops) | |
1139 | len += sprintf(name+len, "%s ", __e->elevator_name); | |
1140 | else if (!__e->uses_mq && !q->mq_ops) | |
1da177e4 LT |
1141 | len += sprintf(name+len, "%s ", __e->elevator_name); |
1142 | } | |
2a12dcd7 | 1143 | spin_unlock(&elv_list_lock); |
1da177e4 | 1144 | |
bd166ef1 JA |
1145 | if (q->mq_ops && q->elevator) |
1146 | len += sprintf(name+len, "none"); | |
1147 | ||
1da177e4 LT |
1148 | len += sprintf(len+name, "\n"); |
1149 | return len; | |
1150 | } | |
1151 | ||
165125e1 JA |
1152 | struct request *elv_rb_former_request(struct request_queue *q, |
1153 | struct request *rq) | |
2e662b65 JA |
1154 | { |
1155 | struct rb_node *rbprev = rb_prev(&rq->rb_node); | |
1156 | ||
1157 | if (rbprev) | |
1158 | return rb_entry_rq(rbprev); | |
1159 | ||
1160 | return NULL; | |
1161 | } | |
2e662b65 JA |
1162 | EXPORT_SYMBOL(elv_rb_former_request); |
1163 | ||
165125e1 JA |
1164 | struct request *elv_rb_latter_request(struct request_queue *q, |
1165 | struct request *rq) | |
2e662b65 JA |
1166 | { |
1167 | struct rb_node *rbnext = rb_next(&rq->rb_node); | |
1168 | ||
1169 | if (rbnext) | |
1170 | return rb_entry_rq(rbnext); | |
1171 | ||
1172 | return NULL; | |
1173 | } | |
2e662b65 | 1174 | EXPORT_SYMBOL(elv_rb_latter_request); |