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bd166ef1 JA |
1 | /* |
2 | * blk-mq scheduling framework | |
3 | * | |
4 | * Copyright (C) 2016 Jens Axboe | |
5 | */ | |
6 | #include <linux/kernel.h> | |
7 | #include <linux/module.h> | |
8 | #include <linux/blk-mq.h> | |
9 | ||
10 | #include <trace/events/block.h> | |
11 | ||
12 | #include "blk.h" | |
13 | #include "blk-mq.h" | |
14 | #include "blk-mq-sched.h" | |
15 | #include "blk-mq-tag.h" | |
16 | #include "blk-wbt.h" | |
17 | ||
18 | void blk_mq_sched_free_hctx_data(struct request_queue *q, | |
19 | void (*exit)(struct blk_mq_hw_ctx *)) | |
20 | { | |
21 | struct blk_mq_hw_ctx *hctx; | |
22 | int i; | |
23 | ||
24 | queue_for_each_hw_ctx(q, hctx, i) { | |
25 | if (exit && hctx->sched_data) | |
26 | exit(hctx); | |
27 | kfree(hctx->sched_data); | |
28 | hctx->sched_data = NULL; | |
29 | } | |
30 | } | |
31 | EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data); | |
32 | ||
33 | int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size, | |
34 | int (*init)(struct blk_mq_hw_ctx *), | |
35 | void (*exit)(struct blk_mq_hw_ctx *)) | |
36 | { | |
37 | struct blk_mq_hw_ctx *hctx; | |
38 | int ret; | |
39 | int i; | |
40 | ||
41 | queue_for_each_hw_ctx(q, hctx, i) { | |
42 | hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node); | |
43 | if (!hctx->sched_data) { | |
44 | ret = -ENOMEM; | |
45 | goto error; | |
46 | } | |
47 | ||
48 | if (init) { | |
49 | ret = init(hctx); | |
50 | if (ret) { | |
51 | /* | |
52 | * We don't want to give exit() a partially | |
53 | * initialized sched_data. init() must clean up | |
54 | * if it fails. | |
55 | */ | |
56 | kfree(hctx->sched_data); | |
57 | hctx->sched_data = NULL; | |
58 | goto error; | |
59 | } | |
60 | } | |
61 | } | |
62 | ||
63 | return 0; | |
64 | error: | |
65 | blk_mq_sched_free_hctx_data(q, exit); | |
66 | return ret; | |
67 | } | |
68 | EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data); | |
69 | ||
70 | static void __blk_mq_sched_assign_ioc(struct request_queue *q, | |
f1ba8261 PV |
71 | struct request *rq, |
72 | struct bio *bio, | |
73 | struct io_context *ioc) | |
bd166ef1 JA |
74 | { |
75 | struct io_cq *icq; | |
76 | ||
77 | spin_lock_irq(q->queue_lock); | |
78 | icq = ioc_lookup_icq(ioc, q); | |
79 | spin_unlock_irq(q->queue_lock); | |
80 | ||
81 | if (!icq) { | |
82 | icq = ioc_create_icq(ioc, q, GFP_ATOMIC); | |
83 | if (!icq) | |
84 | return; | |
85 | } | |
86 | ||
87 | rq->elv.icq = icq; | |
f1ba8261 | 88 | if (!blk_mq_sched_get_rq_priv(q, rq, bio)) { |
bd166ef1 JA |
89 | rq->rq_flags |= RQF_ELVPRIV; |
90 | get_io_context(icq->ioc); | |
91 | return; | |
92 | } | |
93 | ||
94 | rq->elv.icq = NULL; | |
95 | } | |
96 | ||
97 | static void blk_mq_sched_assign_ioc(struct request_queue *q, | |
98 | struct request *rq, struct bio *bio) | |
99 | { | |
100 | struct io_context *ioc; | |
101 | ||
102 | ioc = rq_ioc(bio); | |
103 | if (ioc) | |
f1ba8261 | 104 | __blk_mq_sched_assign_ioc(q, rq, bio, ioc); |
bd166ef1 JA |
105 | } |
106 | ||
107 | struct request *blk_mq_sched_get_request(struct request_queue *q, | |
108 | struct bio *bio, | |
109 | unsigned int op, | |
110 | struct blk_mq_alloc_data *data) | |
111 | { | |
112 | struct elevator_queue *e = q->elevator; | |
bd166ef1 | 113 | struct request *rq; |
bd166ef1 JA |
114 | |
115 | blk_queue_enter_live(q); | |
6d2809d5 OS |
116 | data->q = q; |
117 | if (likely(!data->ctx)) | |
118 | data->ctx = blk_mq_get_ctx(q); | |
119 | if (likely(!data->hctx)) | |
120 | data->hctx = blk_mq_map_queue(q, data->ctx->cpu); | |
bd166ef1 JA |
121 | |
122 | if (e) { | |
123 | data->flags |= BLK_MQ_REQ_INTERNAL; | |
124 | ||
125 | /* | |
126 | * Flush requests are special and go directly to the | |
127 | * dispatch list. | |
128 | */ | |
f73f44eb | 129 | if (!op_is_flush(op) && e->type->ops.mq.get_request) { |
bd166ef1 JA |
130 | rq = e->type->ops.mq.get_request(q, op, data); |
131 | if (rq) | |
132 | rq->rq_flags |= RQF_QUEUED; | |
133 | } else | |
134 | rq = __blk_mq_alloc_request(data, op); | |
135 | } else { | |
136 | rq = __blk_mq_alloc_request(data, op); | |
bd166ef1 JA |
137 | } |
138 | ||
139 | if (rq) { | |
f73f44eb | 140 | if (!op_is_flush(op)) { |
bd166ef1 JA |
141 | rq->elv.icq = NULL; |
142 | if (e && e->type->icq_cache) | |
143 | blk_mq_sched_assign_ioc(q, rq, bio); | |
144 | } | |
145 | data->hctx->queued++; | |
146 | return rq; | |
147 | } | |
148 | ||
149 | blk_queue_exit(q); | |
150 | return NULL; | |
151 | } | |
152 | ||
153 | void blk_mq_sched_put_request(struct request *rq) | |
154 | { | |
155 | struct request_queue *q = rq->q; | |
156 | struct elevator_queue *e = q->elevator; | |
157 | ||
158 | if (rq->rq_flags & RQF_ELVPRIV) { | |
159 | blk_mq_sched_put_rq_priv(rq->q, rq); | |
160 | if (rq->elv.icq) { | |
161 | put_io_context(rq->elv.icq->ioc); | |
162 | rq->elv.icq = NULL; | |
163 | } | |
164 | } | |
165 | ||
166 | if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request) | |
167 | e->type->ops.mq.put_request(rq); | |
168 | else | |
169 | blk_mq_finish_request(rq); | |
170 | } | |
171 | ||
172 | void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) | |
173 | { | |
174 | struct elevator_queue *e = hctx->queue->elevator; | |
64765a75 JA |
175 | const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request; |
176 | bool did_work = false; | |
bd166ef1 JA |
177 | LIST_HEAD(rq_list); |
178 | ||
179 | if (unlikely(blk_mq_hctx_stopped(hctx))) | |
180 | return; | |
181 | ||
182 | hctx->run++; | |
183 | ||
184 | /* | |
185 | * If we have previous entries on our dispatch list, grab them first for | |
186 | * more fair dispatch. | |
187 | */ | |
188 | if (!list_empty_careful(&hctx->dispatch)) { | |
189 | spin_lock(&hctx->lock); | |
190 | if (!list_empty(&hctx->dispatch)) | |
191 | list_splice_init(&hctx->dispatch, &rq_list); | |
192 | spin_unlock(&hctx->lock); | |
193 | } | |
194 | ||
195 | /* | |
196 | * Only ask the scheduler for requests, if we didn't have residual | |
197 | * requests from the dispatch list. This is to avoid the case where | |
198 | * we only ever dispatch a fraction of the requests available because | |
199 | * of low device queue depth. Once we pull requests out of the IO | |
200 | * scheduler, we can no longer merge or sort them. So it's best to | |
201 | * leave them there for as long as we can. Mark the hw queue as | |
202 | * needing a restart in that case. | |
203 | */ | |
c13660a0 | 204 | if (!list_empty(&rq_list)) { |
d38d3515 | 205 | blk_mq_sched_mark_restart_hctx(hctx); |
64765a75 JA |
206 | did_work = blk_mq_dispatch_rq_list(hctx, &rq_list); |
207 | } else if (!has_sched_dispatch) { | |
c13660a0 JA |
208 | blk_mq_flush_busy_ctxs(hctx, &rq_list); |
209 | blk_mq_dispatch_rq_list(hctx, &rq_list); | |
64765a75 JA |
210 | } |
211 | ||
212 | /* | |
213 | * We want to dispatch from the scheduler if we had no work left | |
214 | * on the dispatch list, OR if we did have work but weren't able | |
215 | * to make progress. | |
216 | */ | |
217 | if (!did_work && has_sched_dispatch) { | |
c13660a0 JA |
218 | do { |
219 | struct request *rq; | |
220 | ||
221 | rq = e->type->ops.mq.dispatch_request(hctx); | |
222 | if (!rq) | |
223 | break; | |
224 | list_add(&rq->queuelist, &rq_list); | |
225 | } while (blk_mq_dispatch_rq_list(hctx, &rq_list)); | |
226 | } | |
bd166ef1 JA |
227 | } |
228 | ||
229 | void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx, | |
230 | struct list_head *rq_list, | |
231 | struct request *(*get_rq)(struct blk_mq_hw_ctx *)) | |
232 | { | |
233 | do { | |
234 | struct request *rq; | |
235 | ||
236 | rq = get_rq(hctx); | |
237 | if (!rq) | |
238 | break; | |
239 | ||
240 | list_add_tail(&rq->queuelist, rq_list); | |
241 | } while (1); | |
242 | } | |
243 | EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch); | |
244 | ||
e4d750c9 JA |
245 | bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, |
246 | struct request **merged_request) | |
bd166ef1 JA |
247 | { |
248 | struct request *rq; | |
bd166ef1 | 249 | |
34fe7c05 CH |
250 | switch (elv_merge(q, &rq, bio)) { |
251 | case ELEVATOR_BACK_MERGE: | |
bd166ef1 JA |
252 | if (!blk_mq_sched_allow_merge(q, rq, bio)) |
253 | return false; | |
34fe7c05 CH |
254 | if (!bio_attempt_back_merge(q, rq, bio)) |
255 | return false; | |
256 | *merged_request = attempt_back_merge(q, rq); | |
257 | if (!*merged_request) | |
258 | elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); | |
259 | return true; | |
260 | case ELEVATOR_FRONT_MERGE: | |
bd166ef1 JA |
261 | if (!blk_mq_sched_allow_merge(q, rq, bio)) |
262 | return false; | |
34fe7c05 CH |
263 | if (!bio_attempt_front_merge(q, rq, bio)) |
264 | return false; | |
265 | *merged_request = attempt_front_merge(q, rq); | |
266 | if (!*merged_request) | |
267 | elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); | |
268 | return true; | |
269 | default: | |
270 | return false; | |
bd166ef1 | 271 | } |
bd166ef1 JA |
272 | } |
273 | EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); | |
274 | ||
275 | bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio) | |
276 | { | |
277 | struct elevator_queue *e = q->elevator; | |
278 | ||
279 | if (e->type->ops.mq.bio_merge) { | |
280 | struct blk_mq_ctx *ctx = blk_mq_get_ctx(q); | |
281 | struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu); | |
282 | ||
283 | blk_mq_put_ctx(ctx); | |
284 | return e->type->ops.mq.bio_merge(hctx, bio); | |
285 | } | |
286 | ||
287 | return false; | |
288 | } | |
289 | ||
290 | bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq) | |
291 | { | |
292 | return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq); | |
293 | } | |
294 | EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge); | |
295 | ||
296 | void blk_mq_sched_request_inserted(struct request *rq) | |
297 | { | |
298 | trace_block_rq_insert(rq->q, rq); | |
299 | } | |
300 | EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted); | |
301 | ||
0cacba6c OS |
302 | static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, |
303 | struct request *rq) | |
bd166ef1 JA |
304 | { |
305 | if (rq->tag == -1) { | |
306 | rq->rq_flags |= RQF_SORTED; | |
307 | return false; | |
308 | } | |
309 | ||
310 | /* | |
311 | * If we already have a real request tag, send directly to | |
312 | * the dispatch list. | |
313 | */ | |
314 | spin_lock(&hctx->lock); | |
315 | list_add(&rq->queuelist, &hctx->dispatch); | |
316 | spin_unlock(&hctx->lock); | |
317 | return true; | |
318 | } | |
bd166ef1 | 319 | |
50e1dab8 JA |
320 | static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx) |
321 | { | |
322 | if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) { | |
323 | clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state); | |
324 | if (blk_mq_hctx_has_pending(hctx)) | |
325 | blk_mq_run_hw_queue(hctx, true); | |
326 | } | |
327 | } | |
328 | ||
329 | void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx) | |
330 | { | |
d38d3515 | 331 | struct request_queue *q = hctx->queue; |
50e1dab8 JA |
332 | unsigned int i; |
333 | ||
d38d3515 OS |
334 | if (test_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) { |
335 | if (test_and_clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) { | |
336 | queue_for_each_hw_ctx(q, hctx, i) | |
337 | blk_mq_sched_restart_hctx(hctx); | |
338 | } | |
339 | } else { | |
50e1dab8 | 340 | blk_mq_sched_restart_hctx(hctx); |
50e1dab8 JA |
341 | } |
342 | } | |
343 | ||
bd6737f1 JA |
344 | /* |
345 | * Add flush/fua to the queue. If we fail getting a driver tag, then | |
346 | * punt to the requeue list. Requeue will re-invoke us from a context | |
347 | * that's safe to block from. | |
348 | */ | |
349 | static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx, | |
350 | struct request *rq, bool can_block) | |
351 | { | |
352 | if (blk_mq_get_driver_tag(rq, &hctx, can_block)) { | |
353 | blk_insert_flush(rq); | |
354 | blk_mq_run_hw_queue(hctx, true); | |
355 | } else | |
c7a571b4 | 356 | blk_mq_add_to_requeue_list(rq, false, true); |
bd6737f1 JA |
357 | } |
358 | ||
359 | void blk_mq_sched_insert_request(struct request *rq, bool at_head, | |
360 | bool run_queue, bool async, bool can_block) | |
361 | { | |
362 | struct request_queue *q = rq->q; | |
363 | struct elevator_queue *e = q->elevator; | |
364 | struct blk_mq_ctx *ctx = rq->mq_ctx; | |
365 | struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu); | |
366 | ||
f3a8ab7d | 367 | if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) { |
bd6737f1 JA |
368 | blk_mq_sched_insert_flush(hctx, rq, can_block); |
369 | return; | |
370 | } | |
371 | ||
0cacba6c OS |
372 | if (e && blk_mq_sched_bypass_insert(hctx, rq)) |
373 | goto run; | |
374 | ||
bd6737f1 JA |
375 | if (e && e->type->ops.mq.insert_requests) { |
376 | LIST_HEAD(list); | |
377 | ||
378 | list_add(&rq->queuelist, &list); | |
379 | e->type->ops.mq.insert_requests(hctx, &list, at_head); | |
380 | } else { | |
381 | spin_lock(&ctx->lock); | |
382 | __blk_mq_insert_request(hctx, rq, at_head); | |
383 | spin_unlock(&ctx->lock); | |
384 | } | |
385 | ||
0cacba6c | 386 | run: |
bd6737f1 JA |
387 | if (run_queue) |
388 | blk_mq_run_hw_queue(hctx, async); | |
389 | } | |
390 | ||
391 | void blk_mq_sched_insert_requests(struct request_queue *q, | |
392 | struct blk_mq_ctx *ctx, | |
393 | struct list_head *list, bool run_queue_async) | |
394 | { | |
395 | struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu); | |
396 | struct elevator_queue *e = hctx->queue->elevator; | |
397 | ||
0cacba6c OS |
398 | if (e) { |
399 | struct request *rq, *next; | |
400 | ||
401 | /* | |
402 | * We bypass requests that already have a driver tag assigned, | |
403 | * which should only be flushes. Flushes are only ever inserted | |
404 | * as single requests, so we shouldn't ever hit the | |
405 | * WARN_ON_ONCE() below (but let's handle it just in case). | |
406 | */ | |
407 | list_for_each_entry_safe(rq, next, list, queuelist) { | |
408 | if (WARN_ON_ONCE(rq->tag != -1)) { | |
409 | list_del_init(&rq->queuelist); | |
410 | blk_mq_sched_bypass_insert(hctx, rq); | |
411 | } | |
412 | } | |
413 | } | |
414 | ||
bd6737f1 JA |
415 | if (e && e->type->ops.mq.insert_requests) |
416 | e->type->ops.mq.insert_requests(hctx, list, false); | |
417 | else | |
418 | blk_mq_insert_requests(hctx, ctx, list); | |
419 | ||
420 | blk_mq_run_hw_queue(hctx, run_queue_async); | |
421 | } | |
422 | ||
bd166ef1 JA |
423 | static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set, |
424 | struct blk_mq_hw_ctx *hctx, | |
425 | unsigned int hctx_idx) | |
426 | { | |
427 | if (hctx->sched_tags) { | |
428 | blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx); | |
429 | blk_mq_free_rq_map(hctx->sched_tags); | |
430 | hctx->sched_tags = NULL; | |
431 | } | |
432 | } | |
433 | ||
434 | int blk_mq_sched_setup(struct request_queue *q) | |
435 | { | |
436 | struct blk_mq_tag_set *set = q->tag_set; | |
437 | struct blk_mq_hw_ctx *hctx; | |
438 | int ret, i; | |
439 | ||
440 | /* | |
441 | * Default to 256, since we don't split into sync/async like the | |
442 | * old code did. Additionally, this is a per-hw queue depth. | |
443 | */ | |
444 | q->nr_requests = 2 * BLKDEV_MAX_RQ; | |
445 | ||
446 | /* | |
447 | * We're switching to using an IO scheduler, so setup the hctx | |
448 | * scheduler tags and switch the request map from the regular | |
449 | * tags to scheduler tags. First allocate what we need, so we | |
450 | * can safely fail and fallback, if needed. | |
451 | */ | |
452 | ret = 0; | |
453 | queue_for_each_hw_ctx(q, hctx, i) { | |
415b806d SG |
454 | hctx->sched_tags = blk_mq_alloc_rq_map(set, i, |
455 | q->nr_requests, set->reserved_tags); | |
bd166ef1 JA |
456 | if (!hctx->sched_tags) { |
457 | ret = -ENOMEM; | |
458 | break; | |
459 | } | |
460 | ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests); | |
461 | if (ret) | |
462 | break; | |
463 | } | |
464 | ||
465 | /* | |
466 | * If we failed, free what we did allocate | |
467 | */ | |
468 | if (ret) { | |
469 | queue_for_each_hw_ctx(q, hctx, i) { | |
470 | if (!hctx->sched_tags) | |
471 | continue; | |
472 | blk_mq_sched_free_tags(set, hctx, i); | |
473 | } | |
474 | ||
475 | return ret; | |
476 | } | |
477 | ||
478 | return 0; | |
479 | } | |
480 | ||
481 | void blk_mq_sched_teardown(struct request_queue *q) | |
482 | { | |
483 | struct blk_mq_tag_set *set = q->tag_set; | |
484 | struct blk_mq_hw_ctx *hctx; | |
485 | int i; | |
486 | ||
487 | queue_for_each_hw_ctx(q, hctx, i) | |
488 | blk_mq_sched_free_tags(set, hctx, i); | |
489 | } | |
d3484991 JA |
490 | |
491 | int blk_mq_sched_init(struct request_queue *q) | |
492 | { | |
493 | int ret; | |
494 | ||
d3484991 JA |
495 | mutex_lock(&q->sysfs_lock); |
496 | ret = elevator_init(q, NULL); | |
497 | mutex_unlock(&q->sysfs_lock); | |
498 | ||
499 | return ret; | |
500 | } |