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> | |
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" |
bca6b067 | 44 | #include "blk-pm.h" |
8330cdb0 | 45 | #include "blk-wbt.h" |
242f9dcb | 46 | |
1da177e4 LT |
47 | static DEFINE_SPINLOCK(elv_list_lock); |
48 | static LIST_HEAD(elv_list); | |
49 | ||
9817064b JA |
50 | /* |
51 | * Merge hash stuff. | |
52 | */ | |
83096ebf | 53 | #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
9817064b | 54 | |
da775265 JA |
55 | /* |
56 | * Query io scheduler to see if the current process issuing bio may be | |
57 | * merged with rq. | |
58 | */ | |
72ef799b | 59 | static int elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio) |
da775265 | 60 | { |
165125e1 | 61 | struct request_queue *q = rq->q; |
b374d18a | 62 | struct elevator_queue *e = q->elevator; |
da775265 | 63 | |
bd166ef1 JA |
64 | if (e->uses_mq && e->type->ops.mq.allow_merge) |
65 | return e->type->ops.mq.allow_merge(q, rq, bio); | |
66 | else if (!e->uses_mq && e->type->ops.sq.elevator_allow_bio_merge_fn) | |
c51ca6cf | 67 | return e->type->ops.sq.elevator_allow_bio_merge_fn(q, rq, bio); |
da775265 JA |
68 | |
69 | return 1; | |
70 | } | |
71 | ||
1da177e4 LT |
72 | /* |
73 | * can we safely merge with this request? | |
74 | */ | |
72ef799b | 75 | bool elv_bio_merge_ok(struct request *rq, struct bio *bio) |
1da177e4 | 76 | { |
050c8ea8 | 77 | if (!blk_rq_merge_ok(rq, bio)) |
72ef799b | 78 | return false; |
7ba1ba12 | 79 | |
72ef799b TE |
80 | if (!elv_iosched_allow_bio_merge(rq, bio)) |
81 | return false; | |
1da177e4 | 82 | |
72ef799b | 83 | return true; |
1da177e4 | 84 | } |
72ef799b | 85 | EXPORT_SYMBOL(elv_bio_merge_ok); |
1da177e4 | 86 | |
8ac0d9a8 JA |
87 | static bool elevator_match(const struct elevator_type *e, const char *name) |
88 | { | |
89 | if (!strcmp(e->elevator_name, name)) | |
90 | return true; | |
91 | if (e->elevator_alias && !strcmp(e->elevator_alias, name)) | |
92 | return true; | |
93 | ||
94 | return false; | |
95 | } | |
96 | ||
2527d997 JA |
97 | /* |
98 | * Return scheduler with name 'name' and with matching 'mq capability | |
99 | */ | |
100 | static struct elevator_type *elevator_find(const char *name, bool mq) | |
1da177e4 | 101 | { |
a22b169d | 102 | struct elevator_type *e; |
1da177e4 | 103 | |
70cee26e | 104 | list_for_each_entry(e, &elv_list, list) { |
8ac0d9a8 | 105 | if (elevator_match(e, name) && (mq == e->uses_mq)) |
a22b169d | 106 | return e; |
1da177e4 | 107 | } |
1da177e4 | 108 | |
a22b169d | 109 | return NULL; |
1da177e4 LT |
110 | } |
111 | ||
112 | static void elevator_put(struct elevator_type *e) | |
113 | { | |
114 | module_put(e->elevator_owner); | |
115 | } | |
116 | ||
2527d997 JA |
117 | static struct elevator_type *elevator_get(struct request_queue *q, |
118 | const char *name, bool try_loading) | |
1da177e4 | 119 | { |
2824bc93 | 120 | struct elevator_type *e; |
1da177e4 | 121 | |
2a12dcd7 | 122 | spin_lock(&elv_list_lock); |
2824bc93 | 123 | |
2527d997 | 124 | e = elevator_find(name, q->mq_ops != NULL); |
21c3c5d2 | 125 | if (!e && try_loading) { |
e1640949 | 126 | spin_unlock(&elv_list_lock); |
490b94be | 127 | request_module("%s-iosched", name); |
e1640949 | 128 | spin_lock(&elv_list_lock); |
2527d997 | 129 | e = elevator_find(name, q->mq_ops != NULL); |
e1640949 JA |
130 | } |
131 | ||
2824bc93 TH |
132 | if (e && !try_module_get(e->elevator_owner)) |
133 | e = NULL; | |
134 | ||
2a12dcd7 | 135 | spin_unlock(&elv_list_lock); |
1da177e4 LT |
136 | return e; |
137 | } | |
138 | ||
484fc254 | 139 | static char chosen_elevator[ELV_NAME_MAX]; |
1da177e4 | 140 | |
5f003976 | 141 | static int __init elevator_setup(char *str) |
1da177e4 | 142 | { |
752a3b79 CE |
143 | /* |
144 | * Be backwards-compatible with previous kernels, so users | |
145 | * won't get the wrong elevator. | |
146 | */ | |
492af635 | 147 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
9b41046c | 148 | return 1; |
1da177e4 LT |
149 | } |
150 | ||
151 | __setup("elevator=", elevator_setup); | |
152 | ||
bb813f4c TH |
153 | /* called during boot to load the elevator chosen by the elevator param */ |
154 | void __init load_default_elevator_module(void) | |
155 | { | |
156 | struct elevator_type *e; | |
157 | ||
158 | if (!chosen_elevator[0]) | |
159 | return; | |
160 | ||
2527d997 JA |
161 | /* |
162 | * Boot parameter is deprecated, we haven't supported that for MQ. | |
163 | * Only look for non-mq schedulers from here. | |
164 | */ | |
bb813f4c | 165 | spin_lock(&elv_list_lock); |
2527d997 | 166 | e = elevator_find(chosen_elevator, false); |
bb813f4c TH |
167 | spin_unlock(&elv_list_lock); |
168 | ||
169 | if (!e) | |
170 | request_module("%s-iosched", chosen_elevator); | |
171 | } | |
172 | ||
3d1ab40f AV |
173 | static struct kobj_type elv_ktype; |
174 | ||
d50235b7 | 175 | struct elevator_queue *elevator_alloc(struct request_queue *q, |
165125e1 | 176 | struct elevator_type *e) |
3d1ab40f | 177 | { |
b374d18a | 178 | struct elevator_queue *eq; |
9817064b | 179 | |
c1b511eb | 180 | eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node); |
9817064b | 181 | if (unlikely(!eq)) |
8406a4d5 | 182 | return NULL; |
9817064b | 183 | |
22f746e2 | 184 | eq->type = e; |
f9cb074b | 185 | kobject_init(&eq->kobj, &elv_ktype); |
9817064b | 186 | mutex_init(&eq->sysfs_lock); |
242d98f0 | 187 | hash_init(eq->hash); |
bd166ef1 | 188 | eq->uses_mq = e->uses_mq; |
9817064b | 189 | |
3d1ab40f AV |
190 | return eq; |
191 | } | |
d50235b7 | 192 | EXPORT_SYMBOL(elevator_alloc); |
3d1ab40f AV |
193 | |
194 | static void elevator_release(struct kobject *kobj) | |
195 | { | |
b374d18a | 196 | struct elevator_queue *e; |
9817064b | 197 | |
b374d18a | 198 | e = container_of(kobj, struct elevator_queue, kobj); |
22f746e2 | 199 | elevator_put(e->type); |
3d1ab40f AV |
200 | kfree(e); |
201 | } | |
202 | ||
131d08e1 CH |
203 | /* |
204 | * Use the default elevator specified by config boot param for non-mq devices, | |
205 | * or by config option. Don't try to load modules as we could be running off | |
206 | * async and request_module() isn't allowed from async. | |
207 | */ | |
ddb72532 | 208 | int elevator_init(struct request_queue *q) |
1da177e4 LT |
209 | { |
210 | struct elevator_type *e = NULL; | |
acddf3b3 | 211 | int err = 0; |
1da177e4 | 212 | |
eb1c160b TS |
213 | /* |
214 | * q->sysfs_lock must be held to provide mutual exclusion between | |
215 | * elevator_switch() and here. | |
216 | */ | |
acddf3b3 | 217 | mutex_lock(&q->sysfs_lock); |
1abec4fd | 218 | if (unlikely(q->elevator)) |
acddf3b3 | 219 | goto out_unlock; |
1abec4fd | 220 | |
131d08e1 | 221 | if (*chosen_elevator) { |
2527d997 | 222 | e = elevator_get(q, chosen_elevator, false); |
4eb166d9 JA |
223 | if (!e) |
224 | printk(KERN_ERR "I/O scheduler %s not found\n", | |
225 | chosen_elevator); | |
226 | } | |
248d5ca5 | 227 | |
131d08e1 CH |
228 | if (!e) |
229 | e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false); | |
4eb166d9 | 230 | if (!e) { |
131d08e1 CH |
231 | printk(KERN_ERR |
232 | "Default I/O scheduler not found. Using noop.\n"); | |
233 | e = elevator_get(q, "noop", false); | |
5f003976 ND |
234 | } |
235 | ||
131d08e1 | 236 | err = e->ops.sq.elevator_init_fn(q, e); |
6917ff0b | 237 | if (err) |
d32f6b57 | 238 | elevator_put(e); |
acddf3b3 CH |
239 | out_unlock: |
240 | mutex_unlock(&q->sysfs_lock); | |
d32f6b57 | 241 | return err; |
1da177e4 | 242 | } |
2e662b65 | 243 | |
54d5329d | 244 | void elevator_exit(struct request_queue *q, struct elevator_queue *e) |
1da177e4 | 245 | { |
3d1ab40f | 246 | mutex_lock(&e->sysfs_lock); |
bd166ef1 | 247 | if (e->uses_mq && e->type->ops.mq.exit_sched) |
54d5329d | 248 | blk_mq_exit_sched(q, e); |
bd166ef1 | 249 | else if (!e->uses_mq && e->type->ops.sq.elevator_exit_fn) |
c51ca6cf | 250 | e->type->ops.sq.elevator_exit_fn(e); |
3d1ab40f | 251 | mutex_unlock(&e->sysfs_lock); |
1da177e4 | 252 | |
3d1ab40f | 253 | kobject_put(&e->kobj); |
1da177e4 | 254 | } |
2e662b65 | 255 | |
9817064b JA |
256 | static inline void __elv_rqhash_del(struct request *rq) |
257 | { | |
242d98f0 | 258 | hash_del(&rq->hash); |
e8064021 | 259 | rq->rq_flags &= ~RQF_HASHED; |
9817064b JA |
260 | } |
261 | ||
70b3ea05 | 262 | void elv_rqhash_del(struct request_queue *q, struct request *rq) |
9817064b JA |
263 | { |
264 | if (ELV_ON_HASH(rq)) | |
265 | __elv_rqhash_del(rq); | |
266 | } | |
bd166ef1 | 267 | EXPORT_SYMBOL_GPL(elv_rqhash_del); |
9817064b | 268 | |
70b3ea05 | 269 | void elv_rqhash_add(struct request_queue *q, struct request *rq) |
9817064b | 270 | { |
b374d18a | 271 | struct elevator_queue *e = q->elevator; |
9817064b JA |
272 | |
273 | BUG_ON(ELV_ON_HASH(rq)); | |
242d98f0 | 274 | hash_add(e->hash, &rq->hash, rq_hash_key(rq)); |
e8064021 | 275 | rq->rq_flags |= RQF_HASHED; |
9817064b | 276 | } |
bd166ef1 | 277 | EXPORT_SYMBOL_GPL(elv_rqhash_add); |
9817064b | 278 | |
70b3ea05 | 279 | void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
9817064b JA |
280 | { |
281 | __elv_rqhash_del(rq); | |
282 | elv_rqhash_add(q, rq); | |
283 | } | |
284 | ||
70b3ea05 | 285 | struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
9817064b | 286 | { |
b374d18a | 287 | struct elevator_queue *e = q->elevator; |
b67bfe0d | 288 | struct hlist_node *next; |
9817064b JA |
289 | struct request *rq; |
290 | ||
ee89f812 | 291 | hash_for_each_possible_safe(e->hash, rq, next, hash, offset) { |
9817064b JA |
292 | BUG_ON(!ELV_ON_HASH(rq)); |
293 | ||
294 | if (unlikely(!rq_mergeable(rq))) { | |
295 | __elv_rqhash_del(rq); | |
296 | continue; | |
297 | } | |
298 | ||
299 | if (rq_hash_key(rq) == offset) | |
300 | return rq; | |
301 | } | |
302 | ||
303 | return NULL; | |
304 | } | |
305 | ||
2e662b65 JA |
306 | /* |
307 | * RB-tree support functions for inserting/lookup/removal of requests | |
308 | * in a sorted RB tree. | |
309 | */ | |
796d5116 | 310 | void elv_rb_add(struct rb_root *root, struct request *rq) |
2e662b65 JA |
311 | { |
312 | struct rb_node **p = &root->rb_node; | |
313 | struct rb_node *parent = NULL; | |
314 | struct request *__rq; | |
315 | ||
316 | while (*p) { | |
317 | parent = *p; | |
318 | __rq = rb_entry(parent, struct request, rb_node); | |
319 | ||
83096ebf | 320 | if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
2e662b65 | 321 | p = &(*p)->rb_left; |
796d5116 | 322 | else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
2e662b65 | 323 | p = &(*p)->rb_right; |
2e662b65 JA |
324 | } |
325 | ||
326 | rb_link_node(&rq->rb_node, parent, p); | |
327 | rb_insert_color(&rq->rb_node, root); | |
2e662b65 | 328 | } |
2e662b65 JA |
329 | EXPORT_SYMBOL(elv_rb_add); |
330 | ||
331 | void elv_rb_del(struct rb_root *root, struct request *rq) | |
332 | { | |
333 | BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); | |
334 | rb_erase(&rq->rb_node, root); | |
335 | RB_CLEAR_NODE(&rq->rb_node); | |
336 | } | |
2e662b65 JA |
337 | EXPORT_SYMBOL(elv_rb_del); |
338 | ||
339 | struct request *elv_rb_find(struct rb_root *root, sector_t sector) | |
340 | { | |
341 | struct rb_node *n = root->rb_node; | |
342 | struct request *rq; | |
343 | ||
344 | while (n) { | |
345 | rq = rb_entry(n, struct request, rb_node); | |
346 | ||
83096ebf | 347 | if (sector < blk_rq_pos(rq)) |
2e662b65 | 348 | n = n->rb_left; |
83096ebf | 349 | else if (sector > blk_rq_pos(rq)) |
2e662b65 JA |
350 | n = n->rb_right; |
351 | else | |
352 | return rq; | |
353 | } | |
354 | ||
355 | return NULL; | |
356 | } | |
2e662b65 JA |
357 | EXPORT_SYMBOL(elv_rb_find); |
358 | ||
8922e16c TH |
359 | /* |
360 | * Insert rq into dispatch queue of q. Queue lock must be held on | |
dbe7f76d | 361 | * entry. rq is sort instead into the dispatch queue. To be used by |
2e662b65 | 362 | * specific elevators. |
8922e16c | 363 | */ |
165125e1 | 364 | void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
8922e16c TH |
365 | { |
366 | sector_t boundary; | |
8922e16c TH |
367 | struct list_head *entry; |
368 | ||
06b86245 TH |
369 | if (q->last_merge == rq) |
370 | q->last_merge = NULL; | |
9817064b JA |
371 | |
372 | elv_rqhash_del(q, rq); | |
373 | ||
15853af9 | 374 | q->nr_sorted--; |
06b86245 | 375 | |
1b47f531 | 376 | boundary = q->end_sector; |
8922e16c TH |
377 | list_for_each_prev(entry, &q->queue_head) { |
378 | struct request *pos = list_entry_rq(entry); | |
379 | ||
7afafc8a | 380 | if (req_op(rq) != req_op(pos)) |
e17fc0a1 | 381 | break; |
783660b2 JA |
382 | if (rq_data_dir(rq) != rq_data_dir(pos)) |
383 | break; | |
e8064021 | 384 | if (pos->rq_flags & (RQF_STARTED | RQF_SOFTBARRIER)) |
8922e16c | 385 | break; |
83096ebf TH |
386 | if (blk_rq_pos(rq) >= boundary) { |
387 | if (blk_rq_pos(pos) < boundary) | |
8922e16c TH |
388 | continue; |
389 | } else { | |
83096ebf | 390 | if (blk_rq_pos(pos) >= boundary) |
8922e16c TH |
391 | break; |
392 | } | |
83096ebf | 393 | if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
8922e16c TH |
394 | break; |
395 | } | |
396 | ||
397 | list_add(&rq->queuelist, entry); | |
398 | } | |
2e662b65 JA |
399 | EXPORT_SYMBOL(elv_dispatch_sort); |
400 | ||
9817064b | 401 | /* |
2e662b65 JA |
402 | * Insert rq into dispatch queue of q. Queue lock must be held on |
403 | * entry. rq is added to the back of the dispatch queue. To be used by | |
404 | * specific elevators. | |
9817064b JA |
405 | */ |
406 | void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) | |
407 | { | |
408 | if (q->last_merge == rq) | |
409 | q->last_merge = NULL; | |
410 | ||
411 | elv_rqhash_del(q, rq); | |
412 | ||
413 | q->nr_sorted--; | |
414 | ||
415 | q->end_sector = rq_end_sector(rq); | |
416 | q->boundary_rq = rq; | |
417 | list_add_tail(&rq->queuelist, &q->queue_head); | |
418 | } | |
2e662b65 JA |
419 | EXPORT_SYMBOL(elv_dispatch_add_tail); |
420 | ||
34fe7c05 CH |
421 | enum elv_merge elv_merge(struct request_queue *q, struct request **req, |
422 | struct bio *bio) | |
1da177e4 | 423 | { |
b374d18a | 424 | struct elevator_queue *e = q->elevator; |
9817064b | 425 | struct request *__rq; |
06b86245 | 426 | |
488991e2 AB |
427 | /* |
428 | * Levels of merges: | |
429 | * nomerges: No merges at all attempted | |
430 | * noxmerges: Only simple one-hit cache try | |
431 | * merges: All merge tries attempted | |
432 | */ | |
7460d389 | 433 | if (blk_queue_nomerges(q) || !bio_mergeable(bio)) |
488991e2 AB |
434 | return ELEVATOR_NO_MERGE; |
435 | ||
9817064b JA |
436 | /* |
437 | * First try one-hit cache. | |
438 | */ | |
72ef799b | 439 | if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) { |
34fe7c05 CH |
440 | enum elv_merge ret = blk_try_merge(q->last_merge, bio); |
441 | ||
06b86245 TH |
442 | if (ret != ELEVATOR_NO_MERGE) { |
443 | *req = q->last_merge; | |
444 | return ret; | |
445 | } | |
446 | } | |
1da177e4 | 447 | |
488991e2 | 448 | if (blk_queue_noxmerges(q)) |
ac9fafa1 AB |
449 | return ELEVATOR_NO_MERGE; |
450 | ||
9817064b JA |
451 | /* |
452 | * See if our hash lookup can find a potential backmerge. | |
453 | */ | |
4f024f37 | 454 | __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); |
72ef799b | 455 | if (__rq && elv_bio_merge_ok(__rq, bio)) { |
9817064b JA |
456 | *req = __rq; |
457 | return ELEVATOR_BACK_MERGE; | |
458 | } | |
459 | ||
bd166ef1 JA |
460 | if (e->uses_mq && e->type->ops.mq.request_merge) |
461 | return e->type->ops.mq.request_merge(q, req, bio); | |
462 | else if (!e->uses_mq && e->type->ops.sq.elevator_merge_fn) | |
c51ca6cf | 463 | return e->type->ops.sq.elevator_merge_fn(q, req, bio); |
1da177e4 LT |
464 | |
465 | return ELEVATOR_NO_MERGE; | |
466 | } | |
467 | ||
5e84ea3a JA |
468 | /* |
469 | * Attempt to do an insertion back merge. Only check for the case where | |
470 | * we can append 'rq' to an existing request, so we can throw 'rq' away | |
471 | * afterwards. | |
472 | * | |
473 | * Returns true if we merged, false otherwise | |
474 | */ | |
bd166ef1 | 475 | bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq) |
5e84ea3a JA |
476 | { |
477 | struct request *__rq; | |
bee0393c | 478 | bool ret; |
5e84ea3a JA |
479 | |
480 | if (blk_queue_nomerges(q)) | |
481 | return false; | |
482 | ||
483 | /* | |
484 | * First try one-hit cache. | |
485 | */ | |
486 | if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) | |
487 | return true; | |
488 | ||
489 | if (blk_queue_noxmerges(q)) | |
490 | return false; | |
491 | ||
bee0393c | 492 | ret = false; |
5e84ea3a JA |
493 | /* |
494 | * See if our hash lookup can find a potential backmerge. | |
495 | */ | |
bee0393c SL |
496 | while (1) { |
497 | __rq = elv_rqhash_find(q, blk_rq_pos(rq)); | |
498 | if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) | |
499 | break; | |
500 | ||
501 | /* The merged request could be merged with others, try again */ | |
502 | ret = true; | |
503 | rq = __rq; | |
504 | } | |
27419322 | 505 | |
bee0393c | 506 | return ret; |
5e84ea3a JA |
507 | } |
508 | ||
34fe7c05 CH |
509 | void elv_merged_request(struct request_queue *q, struct request *rq, |
510 | enum elv_merge type) | |
1da177e4 | 511 | { |
b374d18a | 512 | struct elevator_queue *e = q->elevator; |
1da177e4 | 513 | |
bd166ef1 JA |
514 | if (e->uses_mq && e->type->ops.mq.request_merged) |
515 | e->type->ops.mq.request_merged(q, rq, type); | |
516 | else if (!e->uses_mq && e->type->ops.sq.elevator_merged_fn) | |
c51ca6cf | 517 | e->type->ops.sq.elevator_merged_fn(q, rq, type); |
06b86245 | 518 | |
2e662b65 JA |
519 | if (type == ELEVATOR_BACK_MERGE) |
520 | elv_rqhash_reposition(q, rq); | |
9817064b | 521 | |
06b86245 | 522 | q->last_merge = rq; |
1da177e4 LT |
523 | } |
524 | ||
165125e1 | 525 | void elv_merge_requests(struct request_queue *q, struct request *rq, |
1da177e4 LT |
526 | struct request *next) |
527 | { | |
b374d18a | 528 | struct elevator_queue *e = q->elevator; |
bd166ef1 JA |
529 | bool next_sorted = false; |
530 | ||
531 | if (e->uses_mq && e->type->ops.mq.requests_merged) | |
532 | e->type->ops.mq.requests_merged(q, rq, next); | |
533 | else if (e->type->ops.sq.elevator_merge_req_fn) { | |
a1ae0f74 | 534 | next_sorted = (__force bool)(next->rq_flags & RQF_SORTED); |
bd166ef1 JA |
535 | if (next_sorted) |
536 | e->type->ops.sq.elevator_merge_req_fn(q, rq, next); | |
537 | } | |
06b86245 | 538 | |
9817064b | 539 | elv_rqhash_reposition(q, rq); |
9817064b | 540 | |
5e84ea3a JA |
541 | if (next_sorted) { |
542 | elv_rqhash_del(q, next); | |
543 | q->nr_sorted--; | |
544 | } | |
545 | ||
06b86245 | 546 | q->last_merge = rq; |
1da177e4 LT |
547 | } |
548 | ||
812d4026 DS |
549 | void elv_bio_merged(struct request_queue *q, struct request *rq, |
550 | struct bio *bio) | |
551 | { | |
552 | struct elevator_queue *e = q->elevator; | |
553 | ||
bd166ef1 JA |
554 | if (WARN_ON_ONCE(e->uses_mq)) |
555 | return; | |
556 | ||
c51ca6cf JA |
557 | if (e->type->ops.sq.elevator_bio_merged_fn) |
558 | e->type->ops.sq.elevator_bio_merged_fn(q, rq, bio); | |
812d4026 DS |
559 | } |
560 | ||
165125e1 | 561 | void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4 | 562 | { |
1da177e4 LT |
563 | /* |
564 | * it already went through dequeue, we need to decrement the | |
565 | * in_flight count again | |
566 | */ | |
8922e16c | 567 | if (blk_account_rq(rq)) { |
0a7ae2ff | 568 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 569 | if (rq->rq_flags & RQF_SORTED) |
cad97516 | 570 | elv_deactivate_rq(q, rq); |
8922e16c | 571 | } |
1da177e4 | 572 | |
e8064021 | 573 | rq->rq_flags &= ~RQF_STARTED; |
1da177e4 | 574 | |
c8158819 LM |
575 | blk_pm_requeue_request(rq); |
576 | ||
b710a480 | 577 | __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4 LT |
578 | } |
579 | ||
26308eab | 580 | void elv_drain_elevator(struct request_queue *q) |
15853af9 | 581 | { |
bd166ef1 | 582 | struct elevator_queue *e = q->elevator; |
15853af9 | 583 | static int printed; |
e3c78ca5 | 584 | |
bd166ef1 JA |
585 | if (WARN_ON_ONCE(e->uses_mq)) |
586 | return; | |
587 | ||
e3c78ca5 TH |
588 | lockdep_assert_held(q->queue_lock); |
589 | ||
bd166ef1 | 590 | while (e->type->ops.sq.elevator_dispatch_fn(q, 1)) |
15853af9 | 591 | ; |
854f31cc | 592 | if (q->nr_sorted && !blk_queue_is_zoned(q) && printed++ < 10 ) { |
15853af9 TH |
593 | printk(KERN_ERR "%s: forced dispatching is broken " |
594 | "(nr_sorted=%u), please report this\n", | |
22f746e2 | 595 | q->elevator->type->elevator_name, q->nr_sorted); |
15853af9 TH |
596 | } |
597 | } | |
598 | ||
b710a480 | 599 | void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 | 600 | { |
5f3ea37c | 601 | trace_block_rq_insert(q, rq); |
2056a782 | 602 | |
c8158819 LM |
603 | blk_pm_add_request(q, rq); |
604 | ||
1da177e4 LT |
605 | rq->q = q; |
606 | ||
e8064021 | 607 | if (rq->rq_flags & RQF_SOFTBARRIER) { |
b710a480 | 608 | /* barriers are scheduling boundary, update end_sector */ |
57292b58 | 609 | if (!blk_rq_is_passthrough(rq)) { |
b710a480 JA |
610 | q->end_sector = rq_end_sector(rq); |
611 | q->boundary_rq = rq; | |
612 | } | |
e8064021 | 613 | } else if (!(rq->rq_flags & RQF_ELVPRIV) && |
3aa72873 JA |
614 | (where == ELEVATOR_INSERT_SORT || |
615 | where == ELEVATOR_INSERT_SORT_MERGE)) | |
b710a480 JA |
616 | where = ELEVATOR_INSERT_BACK; |
617 | ||
8922e16c | 618 | switch (where) { |
28e7d184 | 619 | case ELEVATOR_INSERT_REQUEUE: |
8922e16c | 620 | case ELEVATOR_INSERT_FRONT: |
e8064021 | 621 | rq->rq_flags |= RQF_SOFTBARRIER; |
8922e16c TH |
622 | list_add(&rq->queuelist, &q->queue_head); |
623 | break; | |
624 | ||
625 | case ELEVATOR_INSERT_BACK: | |
e8064021 | 626 | rq->rq_flags |= RQF_SOFTBARRIER; |
15853af9 | 627 | elv_drain_elevator(q); |
8922e16c TH |
628 | list_add_tail(&rq->queuelist, &q->queue_head); |
629 | /* | |
630 | * We kick the queue here for the following reasons. | |
631 | * - The elevator might have returned NULL previously | |
632 | * to delay requests and returned them now. As the | |
633 | * queue wasn't empty before this request, ll_rw_blk | |
634 | * won't run the queue on return, resulting in hang. | |
635 | * - Usually, back inserted requests won't be merged | |
636 | * with anything. There's no point in delaying queue | |
637 | * processing. | |
638 | */ | |
24ecfbe2 | 639 | __blk_run_queue(q); |
8922e16c TH |
640 | break; |
641 | ||
5e84ea3a JA |
642 | case ELEVATOR_INSERT_SORT_MERGE: |
643 | /* | |
644 | * If we succeed in merging this request with one in the | |
645 | * queue already, we are done - rq has now been freed, | |
646 | * so no need to do anything further. | |
647 | */ | |
648 | if (elv_attempt_insert_merge(q, rq)) | |
649 | break; | |
e29387eb | 650 | /* fall through */ |
8922e16c | 651 | case ELEVATOR_INSERT_SORT: |
57292b58 | 652 | BUG_ON(blk_rq_is_passthrough(rq)); |
e8064021 | 653 | rq->rq_flags |= RQF_SORTED; |
15853af9 | 654 | q->nr_sorted++; |
9817064b JA |
655 | if (rq_mergeable(rq)) { |
656 | elv_rqhash_add(q, rq); | |
657 | if (!q->last_merge) | |
658 | q->last_merge = rq; | |
659 | } | |
660 | ||
ca23509f TH |
661 | /* |
662 | * Some ioscheds (cfq) run q->request_fn directly, so | |
663 | * rq cannot be accessed after calling | |
664 | * elevator_add_req_fn. | |
665 | */ | |
c51ca6cf | 666 | q->elevator->type->ops.sq.elevator_add_req_fn(q, rq); |
8922e16c TH |
667 | break; |
668 | ||
ae1b1539 | 669 | case ELEVATOR_INSERT_FLUSH: |
e8064021 | 670 | rq->rq_flags |= RQF_SOFTBARRIER; |
ae1b1539 TH |
671 | blk_insert_flush(rq); |
672 | break; | |
8922e16c TH |
673 | default: |
674 | printk(KERN_ERR "%s: bad insertion point %d\n", | |
24c03d47 | 675 | __func__, where); |
8922e16c TH |
676 | BUG(); |
677 | } | |
1da177e4 | 678 | } |
2e662b65 JA |
679 | EXPORT_SYMBOL(__elv_add_request); |
680 | ||
7eaceacc | 681 | void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4 LT |
682 | { |
683 | unsigned long flags; | |
684 | ||
685 | spin_lock_irqsave(q->queue_lock, flags); | |
7eaceacc | 686 | __elv_add_request(q, rq, where); |
1da177e4 LT |
687 | spin_unlock_irqrestore(q->queue_lock, flags); |
688 | } | |
2e662b65 JA |
689 | EXPORT_SYMBOL(elv_add_request); |
690 | ||
165125e1 | 691 | struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4 | 692 | { |
b374d18a | 693 | struct elevator_queue *e = q->elevator; |
1da177e4 | 694 | |
bd166ef1 JA |
695 | if (e->uses_mq && e->type->ops.mq.next_request) |
696 | return e->type->ops.mq.next_request(q, rq); | |
697 | else if (!e->uses_mq && e->type->ops.sq.elevator_latter_req_fn) | |
c51ca6cf | 698 | return e->type->ops.sq.elevator_latter_req_fn(q, rq); |
bd166ef1 | 699 | |
1da177e4 LT |
700 | return NULL; |
701 | } | |
702 | ||
165125e1 | 703 | struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4 | 704 | { |
b374d18a | 705 | struct elevator_queue *e = q->elevator; |
1da177e4 | 706 | |
bd166ef1 JA |
707 | if (e->uses_mq && e->type->ops.mq.former_request) |
708 | return e->type->ops.mq.former_request(q, rq); | |
709 | if (!e->uses_mq && e->type->ops.sq.elevator_former_req_fn) | |
c51ca6cf | 710 | return e->type->ops.sq.elevator_former_req_fn(q, rq); |
1da177e4 LT |
711 | return NULL; |
712 | } | |
713 | ||
852c788f TH |
714 | int elv_set_request(struct request_queue *q, struct request *rq, |
715 | struct bio *bio, gfp_t gfp_mask) | |
1da177e4 | 716 | { |
b374d18a | 717 | struct elevator_queue *e = q->elevator; |
1da177e4 | 718 | |
bd166ef1 JA |
719 | if (WARN_ON_ONCE(e->uses_mq)) |
720 | return 0; | |
721 | ||
c51ca6cf JA |
722 | if (e->type->ops.sq.elevator_set_req_fn) |
723 | return e->type->ops.sq.elevator_set_req_fn(q, rq, bio, gfp_mask); | |
1da177e4 LT |
724 | return 0; |
725 | } | |
726 | ||
165125e1 | 727 | void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4 | 728 | { |
b374d18a | 729 | struct elevator_queue *e = q->elevator; |
1da177e4 | 730 | |
bd166ef1 JA |
731 | if (WARN_ON_ONCE(e->uses_mq)) |
732 | return; | |
733 | ||
c51ca6cf JA |
734 | if (e->type->ops.sq.elevator_put_req_fn) |
735 | e->type->ops.sq.elevator_put_req_fn(rq); | |
1da177e4 LT |
736 | } |
737 | ||
ef295ecf | 738 | int elv_may_queue(struct request_queue *q, unsigned int op) |
1da177e4 | 739 | { |
b374d18a | 740 | struct elevator_queue *e = q->elevator; |
1da177e4 | 741 | |
bd166ef1 JA |
742 | if (WARN_ON_ONCE(e->uses_mq)) |
743 | return 0; | |
744 | ||
c51ca6cf JA |
745 | if (e->type->ops.sq.elevator_may_queue_fn) |
746 | return e->type->ops.sq.elevator_may_queue_fn(q, op); | |
1da177e4 LT |
747 | |
748 | return ELV_MQUEUE_MAY; | |
749 | } | |
750 | ||
165125e1 | 751 | void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4 | 752 | { |
b374d18a | 753 | struct elevator_queue *e = q->elevator; |
1da177e4 | 754 | |
bd166ef1 JA |
755 | if (WARN_ON_ONCE(e->uses_mq)) |
756 | return; | |
757 | ||
1da177e4 LT |
758 | /* |
759 | * request is released from the driver, io must be done | |
760 | */ | |
8922e16c | 761 | if (blk_account_rq(rq)) { |
0a7ae2ff | 762 | q->in_flight[rq_is_sync(rq)]--; |
e8064021 | 763 | if ((rq->rq_flags & RQF_SORTED) && |
c51ca6cf JA |
764 | e->type->ops.sq.elevator_completed_req_fn) |
765 | e->type->ops.sq.elevator_completed_req_fn(q, rq); | |
1bc691d3 | 766 | } |
1da177e4 LT |
767 | } |
768 | ||
3d1ab40f AV |
769 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
770 | ||
771 | static ssize_t | |
772 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
1da177e4 | 773 | { |
3d1ab40f | 774 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 775 | struct elevator_queue *e; |
3d1ab40f AV |
776 | ssize_t error; |
777 | ||
778 | if (!entry->show) | |
779 | return -EIO; | |
780 | ||
b374d18a | 781 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 782 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 783 | error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f AV |
784 | mutex_unlock(&e->sysfs_lock); |
785 | return error; | |
786 | } | |
1da177e4 | 787 | |
3d1ab40f AV |
788 | static ssize_t |
789 | elv_attr_store(struct kobject *kobj, struct attribute *attr, | |
790 | const char *page, size_t length) | |
791 | { | |
3d1ab40f | 792 | struct elv_fs_entry *entry = to_elv(attr); |
b374d18a | 793 | struct elevator_queue *e; |
3d1ab40f | 794 | ssize_t error; |
1da177e4 | 795 | |
3d1ab40f AV |
796 | if (!entry->store) |
797 | return -EIO; | |
1da177e4 | 798 | |
b374d18a | 799 | e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f | 800 | mutex_lock(&e->sysfs_lock); |
22f746e2 | 801 | error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f AV |
802 | mutex_unlock(&e->sysfs_lock); |
803 | return error; | |
804 | } | |
805 | ||
52cf25d0 | 806 | static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f AV |
807 | .show = elv_attr_show, |
808 | .store = elv_attr_store, | |
809 | }; | |
810 | ||
811 | static struct kobj_type elv_ktype = { | |
812 | .sysfs_ops = &elv_sysfs_ops, | |
813 | .release = elevator_release, | |
814 | }; | |
815 | ||
5a5bafdc | 816 | int elv_register_queue(struct request_queue *q) |
3d1ab40f | 817 | { |
5a5bafdc | 818 | struct elevator_queue *e = q->elevator; |
3d1ab40f AV |
819 | int error; |
820 | ||
14a23498 BVA |
821 | lockdep_assert_held(&q->sysfs_lock); |
822 | ||
b2d6db58 | 823 | error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f | 824 | if (!error) { |
22f746e2 | 825 | struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f | 826 | if (attr) { |
e572ec7e AV |
827 | while (attr->attr.name) { |
828 | if (sysfs_create_file(&e->kobj, &attr->attr)) | |
3d1ab40f | 829 | break; |
e572ec7e | 830 | attr++; |
3d1ab40f AV |
831 | } |
832 | } | |
833 | kobject_uevent(&e->kobj, KOBJ_ADD); | |
430c62fb | 834 | e->registered = 1; |
bd166ef1 | 835 | if (!e->uses_mq && e->type->ops.sq.elevator_registered_fn) |
c51ca6cf | 836 | e->type->ops.sq.elevator_registered_fn(q); |
3d1ab40f AV |
837 | } |
838 | return error; | |
1da177e4 | 839 | } |
bc1c1169 | 840 | |
1da177e4 LT |
841 | void elv_unregister_queue(struct request_queue *q) |
842 | { | |
14a23498 BVA |
843 | lockdep_assert_held(&q->sysfs_lock); |
844 | ||
f8fc877d TH |
845 | if (q) { |
846 | struct elevator_queue *e = q->elevator; | |
847 | ||
848 | kobject_uevent(&e->kobj, KOBJ_REMOVE); | |
849 | kobject_del(&e->kobj); | |
850 | e->registered = 0; | |
8330cdb0 JK |
851 | /* Re-enable throttling in case elevator disabled it */ |
852 | wbt_enable_default(q); | |
f8fc877d | 853 | } |
1da177e4 LT |
854 | } |
855 | ||
e567bf71 | 856 | int elv_register(struct elevator_type *e) |
1da177e4 | 857 | { |
1ffb96c5 | 858 | char *def = ""; |
2a12dcd7 | 859 | |
3d3c2379 TH |
860 | /* create icq_cache if requested */ |
861 | if (e->icq_size) { | |
862 | if (WARN_ON(e->icq_size < sizeof(struct io_cq)) || | |
863 | WARN_ON(e->icq_align < __alignof__(struct io_cq))) | |
864 | return -EINVAL; | |
865 | ||
866 | snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), | |
867 | "%s_io_cq", e->elevator_name); | |
868 | e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size, | |
869 | e->icq_align, 0, NULL); | |
870 | if (!e->icq_cache) | |
871 | return -ENOMEM; | |
872 | } | |
873 | ||
874 | /* register, don't allow duplicate names */ | |
2a12dcd7 | 875 | spin_lock(&elv_list_lock); |
2527d997 | 876 | if (elevator_find(e->elevator_name, e->uses_mq)) { |
3d3c2379 | 877 | spin_unlock(&elv_list_lock); |
62d2a194 | 878 | kmem_cache_destroy(e->icq_cache); |
3d3c2379 TH |
879 | return -EBUSY; |
880 | } | |
1da177e4 | 881 | list_add_tail(&e->list, &elv_list); |
2a12dcd7 | 882 | spin_unlock(&elv_list_lock); |
1da177e4 | 883 | |
3d3c2379 | 884 | /* print pretty message */ |
8ac0d9a8 | 885 | if (elevator_match(e, chosen_elevator) || |
5f003976 | 886 | (!*chosen_elevator && |
8ac0d9a8 | 887 | elevator_match(e, CONFIG_DEFAULT_IOSCHED))) |
1ffb96c5 TV |
888 | def = " (default)"; |
889 | ||
4eb166d9 JA |
890 | printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, |
891 | def); | |
3d3c2379 | 892 | return 0; |
1da177e4 LT |
893 | } |
894 | EXPORT_SYMBOL_GPL(elv_register); | |
895 | ||
896 | void elv_unregister(struct elevator_type *e) | |
897 | { | |
3d3c2379 | 898 | /* unregister */ |
2a12dcd7 | 899 | spin_lock(&elv_list_lock); |
1da177e4 | 900 | list_del_init(&e->list); |
2a12dcd7 | 901 | spin_unlock(&elv_list_lock); |
3d3c2379 TH |
902 | |
903 | /* | |
904 | * Destroy icq_cache if it exists. icq's are RCU managed. Make | |
905 | * sure all RCU operations are complete before proceeding. | |
906 | */ | |
907 | if (e->icq_cache) { | |
908 | rcu_barrier(); | |
909 | kmem_cache_destroy(e->icq_cache); | |
910 | e->icq_cache = NULL; | |
911 | } | |
1da177e4 LT |
912 | } |
913 | EXPORT_SYMBOL_GPL(elv_unregister); | |
914 | ||
d48ece20 | 915 | int elevator_switch_mq(struct request_queue *q, |
54d5329d OS |
916 | struct elevator_type *new_e) |
917 | { | |
918 | int ret; | |
919 | ||
14a23498 BVA |
920 | lockdep_assert_held(&q->sysfs_lock); |
921 | ||
54d5329d OS |
922 | if (q->elevator) { |
923 | if (q->elevator->registered) | |
924 | elv_unregister_queue(q); | |
925 | ioc_clear_queue(q); | |
926 | elevator_exit(q, q->elevator); | |
927 | } | |
928 | ||
929 | ret = blk_mq_init_sched(q, new_e); | |
930 | if (ret) | |
931 | goto out; | |
932 | ||
933 | if (new_e) { | |
934 | ret = elv_register_queue(q); | |
935 | if (ret) { | |
936 | elevator_exit(q, q->elevator); | |
937 | goto out; | |
938 | } | |
939 | } | |
940 | ||
941 | if (new_e) | |
942 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); | |
943 | else | |
944 | blk_add_trace_msg(q, "elv switch: none"); | |
945 | ||
946 | out: | |
54d5329d | 947 | return ret; |
54d5329d OS |
948 | } |
949 | ||
131d08e1 CH |
950 | /* |
951 | * For blk-mq devices, we default to using mq-deadline, if available, for single | |
952 | * queue devices. If deadline isn't available OR we have multiple queues, | |
953 | * default to "none". | |
954 | */ | |
955 | int elevator_init_mq(struct request_queue *q) | |
956 | { | |
957 | struct elevator_type *e; | |
958 | int err = 0; | |
959 | ||
960 | if (q->nr_hw_queues != 1) | |
961 | return 0; | |
962 | ||
963 | /* | |
964 | * q->sysfs_lock must be held to provide mutual exclusion between | |
965 | * elevator_switch() and here. | |
966 | */ | |
967 | mutex_lock(&q->sysfs_lock); | |
968 | if (unlikely(q->elevator)) | |
969 | goto out_unlock; | |
970 | ||
971 | e = elevator_get(q, "mq-deadline", false); | |
972 | if (!e) | |
973 | goto out_unlock; | |
974 | ||
975 | err = blk_mq_init_sched(q, e); | |
976 | if (err) | |
977 | elevator_put(e); | |
978 | out_unlock: | |
979 | mutex_unlock(&q->sysfs_lock); | |
980 | return err; | |
981 | } | |
982 | ||
983 | ||
1da177e4 LT |
984 | /* |
985 | * switch to new_e io scheduler. be careful not to introduce deadlocks - | |
986 | * we don't free the old io scheduler, before we have allocated what we | |
987 | * need for the new one. this way we have a chance of going back to the old | |
cb98fc8b | 988 | * one, if the new one fails init for some reason. |
1da177e4 | 989 | */ |
165125e1 | 990 | static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4 | 991 | { |
5a5bafdc | 992 | struct elevator_queue *old = q->elevator; |
bd166ef1 | 993 | bool old_registered = false; |
e8989fae | 994 | int err; |
1da177e4 | 995 | |
14a23498 BVA |
996 | lockdep_assert_held(&q->sysfs_lock); |
997 | ||
d48ece20 JW |
998 | if (q->mq_ops) { |
999 | blk_mq_freeze_queue(q); | |
1000 | blk_mq_quiesce_queue(q); | |
1001 | ||
1002 | err = elevator_switch_mq(q, new_e); | |
1003 | ||
1004 | blk_mq_unquiesce_queue(q); | |
1005 | blk_mq_unfreeze_queue(q); | |
1006 | ||
1007 | return err; | |
1008 | } | |
bd166ef1 | 1009 | |
5a5bafdc TH |
1010 | /* |
1011 | * Turn on BYPASS and drain all requests w/ elevator private data. | |
1012 | * Block layer doesn't call into a quiesced elevator - all requests | |
1013 | * are directly put on the dispatch list without elevator data | |
1014 | * using INSERT_BACK. All requests have SOFTBARRIER set and no | |
1015 | * merge happens either. | |
1016 | */ | |
bd166ef1 JA |
1017 | if (old) { |
1018 | old_registered = old->registered; | |
1019 | ||
54d5329d | 1020 | blk_queue_bypass_start(q); |
1da177e4 | 1021 | |
bd166ef1 JA |
1022 | /* unregister and clear all auxiliary data of the old elevator */ |
1023 | if (old_registered) | |
1024 | elv_unregister_queue(q); | |
1025 | ||
bd166ef1 | 1026 | ioc_clear_queue(q); |
bd166ef1 | 1027 | } |
f8fc877d | 1028 | |
5a5bafdc | 1029 | /* allocate, init and register new elevator */ |
54d5329d | 1030 | err = new_e->ops.sq.elevator_init_fn(q, new_e); |
6917ff0b OS |
1031 | if (err) |
1032 | goto fail_init; | |
5a5bafdc | 1033 | |
54d5329d OS |
1034 | err = elv_register_queue(q); |
1035 | if (err) | |
1036 | goto fail_register; | |
5a5bafdc TH |
1037 | |
1038 | /* done, kill the old one and finish */ | |
bd166ef1 | 1039 | if (old) { |
54d5329d OS |
1040 | elevator_exit(q, old); |
1041 | blk_queue_bypass_end(q); | |
bd166ef1 JA |
1042 | } |
1043 | ||
54d5329d | 1044 | blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52 | 1045 | |
5dd531a0 | 1046 | return 0; |
1da177e4 LT |
1047 | |
1048 | fail_register: | |
54d5329d | 1049 | elevator_exit(q, q->elevator); |
5a5bafdc TH |
1050 | fail_init: |
1051 | /* switch failed, restore and re-register old elevator */ | |
bd166ef1 JA |
1052 | if (old) { |
1053 | q->elevator = old; | |
1054 | elv_register_queue(q); | |
54d5329d | 1055 | blk_queue_bypass_end(q); |
bd166ef1 | 1056 | } |
75ad23bc | 1057 | |
5dd531a0 | 1058 | return err; |
1da177e4 LT |
1059 | } |
1060 | ||
5dd531a0 JA |
1061 | /* |
1062 | * Switch this queue to the given IO scheduler. | |
1063 | */ | |
7c8a3679 | 1064 | static int __elevator_change(struct request_queue *q, const char *name) |
1da177e4 LT |
1065 | { |
1066 | char elevator_name[ELV_NAME_MAX]; | |
1067 | struct elevator_type *e; | |
1068 | ||
e9a823fb DJ |
1069 | /* Make sure queue is not in the middle of being removed */ |
1070 | if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags)) | |
1071 | return -ENOENT; | |
1072 | ||
bd166ef1 JA |
1073 | /* |
1074 | * Special case for mq, turn off scheduling | |
1075 | */ | |
1076 | if (q->mq_ops && !strncmp(name, "none", 4)) | |
1077 | return elevator_switch(q, NULL); | |
cd43e26f | 1078 | |
ee2e992c | 1079 | strlcpy(elevator_name, name, sizeof(elevator_name)); |
2527d997 | 1080 | e = elevator_get(q, strstrip(elevator_name), true); |
340ff321 | 1081 | if (!e) |
1da177e4 | 1082 | return -EINVAL; |
1da177e4 | 1083 | |
8ac0d9a8 | 1084 | if (q->elevator && elevator_match(q->elevator->type, elevator_name)) { |
2ca7d93b | 1085 | elevator_put(e); |
5dd531a0 | 1086 | return 0; |
2ca7d93b | 1087 | } |
1da177e4 | 1088 | |
5dd531a0 JA |
1089 | return elevator_switch(q, e); |
1090 | } | |
7c8a3679 | 1091 | |
3a5088c8 ML |
1092 | static inline bool elv_support_iosched(struct request_queue *q) |
1093 | { | |
1094 | if (q->mq_ops && q->tag_set && (q->tag_set->flags & | |
1095 | BLK_MQ_F_NO_SCHED)) | |
1096 | return false; | |
1097 | return true; | |
1098 | } | |
1099 | ||
5dd531a0 JA |
1100 | ssize_t elv_iosched_store(struct request_queue *q, const char *name, |
1101 | size_t count) | |
1102 | { | |
1103 | int ret; | |
1104 | ||
3a5088c8 | 1105 | if (!(q->mq_ops || q->request_fn) || !elv_support_iosched(q)) |
5dd531a0 JA |
1106 | return count; |
1107 | ||
7c8a3679 | 1108 | ret = __elevator_change(q, name); |
5dd531a0 JA |
1109 | if (!ret) |
1110 | return count; | |
1111 | ||
5dd531a0 | 1112 | return ret; |
1da177e4 LT |
1113 | } |
1114 | ||
165125e1 | 1115 | ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4 | 1116 | { |
b374d18a | 1117 | struct elevator_queue *e = q->elevator; |
bd166ef1 | 1118 | struct elevator_type *elv = NULL; |
70cee26e | 1119 | struct elevator_type *__e; |
8ac0d9a8 | 1120 | bool uses_mq = q->mq_ops != NULL; |
1da177e4 LT |
1121 | int len = 0; |
1122 | ||
5fdee212 | 1123 | if (!queue_is_rq_based(q)) |
cd43e26f MP |
1124 | return sprintf(name, "none\n"); |
1125 | ||
bd166ef1 JA |
1126 | if (!q->elevator) |
1127 | len += sprintf(name+len, "[none] "); | |
1128 | else | |
1129 | elv = e->type; | |
cd43e26f | 1130 | |
2a12dcd7 | 1131 | spin_lock(&elv_list_lock); |
70cee26e | 1132 | list_for_each_entry(__e, &elv_list, list) { |
8ac0d9a8 JA |
1133 | if (elv && elevator_match(elv, __e->elevator_name) && |
1134 | (__e->uses_mq == uses_mq)) { | |
1da177e4 | 1135 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
bd166ef1 JA |
1136 | continue; |
1137 | } | |
3a5088c8 | 1138 | if (__e->uses_mq && q->mq_ops && elv_support_iosched(q)) |
bd166ef1 JA |
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); |