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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, | |
71 | struct request *rq, struct io_context *ioc) | |
72 | { | |
73 | struct io_cq *icq; | |
74 | ||
75 | spin_lock_irq(q->queue_lock); | |
76 | icq = ioc_lookup_icq(ioc, q); | |
77 | spin_unlock_irq(q->queue_lock); | |
78 | ||
79 | if (!icq) { | |
80 | icq = ioc_create_icq(ioc, q, GFP_ATOMIC); | |
81 | if (!icq) | |
82 | return; | |
83 | } | |
84 | ||
85 | rq->elv.icq = icq; | |
86 | if (!blk_mq_sched_get_rq_priv(q, rq)) { | |
87 | rq->rq_flags |= RQF_ELVPRIV; | |
88 | get_io_context(icq->ioc); | |
89 | return; | |
90 | } | |
91 | ||
92 | rq->elv.icq = NULL; | |
93 | } | |
94 | ||
95 | static void blk_mq_sched_assign_ioc(struct request_queue *q, | |
96 | struct request *rq, struct bio *bio) | |
97 | { | |
98 | struct io_context *ioc; | |
99 | ||
100 | ioc = rq_ioc(bio); | |
101 | if (ioc) | |
102 | __blk_mq_sched_assign_ioc(q, rq, ioc); | |
103 | } | |
104 | ||
105 | struct request *blk_mq_sched_get_request(struct request_queue *q, | |
106 | struct bio *bio, | |
107 | unsigned int op, | |
108 | struct blk_mq_alloc_data *data) | |
109 | { | |
110 | struct elevator_queue *e = q->elevator; | |
111 | struct blk_mq_hw_ctx *hctx; | |
112 | struct blk_mq_ctx *ctx; | |
113 | struct request *rq; | |
114 | const bool is_flush = op & (REQ_PREFLUSH | REQ_FUA); | |
115 | ||
116 | blk_queue_enter_live(q); | |
117 | ctx = blk_mq_get_ctx(q); | |
118 | hctx = blk_mq_map_queue(q, ctx->cpu); | |
119 | ||
5a797e00 | 120 | blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx); |
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 | */ | |
129 | if (!is_flush && e->type->ops.mq.get_request) { | |
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); | |
b48fda09 JA |
137 | if (rq) |
138 | data->hctx->tags->rqs[rq->tag] = rq; | |
bd166ef1 JA |
139 | } |
140 | ||
141 | if (rq) { | |
142 | if (!is_flush) { | |
143 | rq->elv.icq = NULL; | |
144 | if (e && e->type->icq_cache) | |
145 | blk_mq_sched_assign_ioc(q, rq, bio); | |
146 | } | |
147 | data->hctx->queued++; | |
148 | return rq; | |
149 | } | |
150 | ||
151 | blk_queue_exit(q); | |
152 | return NULL; | |
153 | } | |
154 | ||
155 | void blk_mq_sched_put_request(struct request *rq) | |
156 | { | |
157 | struct request_queue *q = rq->q; | |
158 | struct elevator_queue *e = q->elevator; | |
159 | ||
160 | if (rq->rq_flags & RQF_ELVPRIV) { | |
161 | blk_mq_sched_put_rq_priv(rq->q, rq); | |
162 | if (rq->elv.icq) { | |
163 | put_io_context(rq->elv.icq->ioc); | |
164 | rq->elv.icq = NULL; | |
165 | } | |
166 | } | |
167 | ||
168 | if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request) | |
169 | e->type->ops.mq.put_request(rq); | |
170 | else | |
171 | blk_mq_finish_request(rq); | |
172 | } | |
173 | ||
174 | void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx) | |
175 | { | |
176 | struct elevator_queue *e = hctx->queue->elevator; | |
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)) { |
bd166ef1 | 205 | blk_mq_sched_mark_restart(hctx); |
c13660a0 JA |
206 | blk_mq_dispatch_rq_list(hctx, &rq_list); |
207 | } else if (!e || !e->type->ops.mq.dispatch_request) { | |
208 | blk_mq_flush_busy_ctxs(hctx, &rq_list); | |
209 | blk_mq_dispatch_rq_list(hctx, &rq_list); | |
210 | } else { | |
211 | do { | |
212 | struct request *rq; | |
213 | ||
214 | rq = e->type->ops.mq.dispatch_request(hctx); | |
215 | if (!rq) | |
216 | break; | |
217 | list_add(&rq->queuelist, &rq_list); | |
218 | } while (blk_mq_dispatch_rq_list(hctx, &rq_list)); | |
219 | } | |
bd166ef1 JA |
220 | } |
221 | ||
222 | void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx, | |
223 | struct list_head *rq_list, | |
224 | struct request *(*get_rq)(struct blk_mq_hw_ctx *)) | |
225 | { | |
226 | do { | |
227 | struct request *rq; | |
228 | ||
229 | rq = get_rq(hctx); | |
230 | if (!rq) | |
231 | break; | |
232 | ||
233 | list_add_tail(&rq->queuelist, rq_list); | |
234 | } while (1); | |
235 | } | |
236 | EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch); | |
237 | ||
238 | bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio) | |
239 | { | |
240 | struct request *rq; | |
241 | int ret; | |
242 | ||
243 | ret = elv_merge(q, &rq, bio); | |
244 | if (ret == ELEVATOR_BACK_MERGE) { | |
245 | if (!blk_mq_sched_allow_merge(q, rq, bio)) | |
246 | return false; | |
247 | if (bio_attempt_back_merge(q, rq, bio)) { | |
248 | if (!attempt_back_merge(q, rq)) | |
249 | elv_merged_request(q, rq, ret); | |
250 | return true; | |
251 | } | |
252 | } else if (ret == ELEVATOR_FRONT_MERGE) { | |
253 | if (!blk_mq_sched_allow_merge(q, rq, bio)) | |
254 | return false; | |
255 | if (bio_attempt_front_merge(q, rq, bio)) { | |
256 | if (!attempt_front_merge(q, rq)) | |
257 | elv_merged_request(q, rq, ret); | |
258 | return true; | |
259 | } | |
260 | } | |
261 | ||
262 | return false; | |
263 | } | |
264 | EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); | |
265 | ||
266 | bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio) | |
267 | { | |
268 | struct elevator_queue *e = q->elevator; | |
269 | ||
270 | if (e->type->ops.mq.bio_merge) { | |
271 | struct blk_mq_ctx *ctx = blk_mq_get_ctx(q); | |
272 | struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu); | |
273 | ||
274 | blk_mq_put_ctx(ctx); | |
275 | return e->type->ops.mq.bio_merge(hctx, bio); | |
276 | } | |
277 | ||
278 | return false; | |
279 | } | |
280 | ||
281 | bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq) | |
282 | { | |
283 | return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq); | |
284 | } | |
285 | EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge); | |
286 | ||
287 | void blk_mq_sched_request_inserted(struct request *rq) | |
288 | { | |
289 | trace_block_rq_insert(rq->q, rq); | |
290 | } | |
291 | EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted); | |
292 | ||
293 | bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, struct request *rq) | |
294 | { | |
295 | if (rq->tag == -1) { | |
296 | rq->rq_flags |= RQF_SORTED; | |
297 | return false; | |
298 | } | |
299 | ||
300 | /* | |
301 | * If we already have a real request tag, send directly to | |
302 | * the dispatch list. | |
303 | */ | |
304 | spin_lock(&hctx->lock); | |
305 | list_add(&rq->queuelist, &hctx->dispatch); | |
306 | spin_unlock(&hctx->lock); | |
307 | return true; | |
308 | } | |
309 | EXPORT_SYMBOL_GPL(blk_mq_sched_bypass_insert); | |
310 | ||
50e1dab8 JA |
311 | static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx) |
312 | { | |
313 | if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) { | |
314 | clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state); | |
315 | if (blk_mq_hctx_has_pending(hctx)) | |
316 | blk_mq_run_hw_queue(hctx, true); | |
317 | } | |
318 | } | |
319 | ||
320 | void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx) | |
321 | { | |
322 | unsigned int i; | |
323 | ||
324 | if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) | |
325 | blk_mq_sched_restart_hctx(hctx); | |
326 | else { | |
327 | struct request_queue *q = hctx->queue; | |
328 | ||
329 | if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) | |
330 | return; | |
331 | ||
332 | clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags); | |
333 | ||
334 | queue_for_each_hw_ctx(q, hctx, i) | |
335 | blk_mq_sched_restart_hctx(hctx); | |
336 | } | |
337 | } | |
338 | ||
bd166ef1 JA |
339 | static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set, |
340 | struct blk_mq_hw_ctx *hctx, | |
341 | unsigned int hctx_idx) | |
342 | { | |
343 | if (hctx->sched_tags) { | |
344 | blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx); | |
345 | blk_mq_free_rq_map(hctx->sched_tags); | |
346 | hctx->sched_tags = NULL; | |
347 | } | |
348 | } | |
349 | ||
350 | int blk_mq_sched_setup(struct request_queue *q) | |
351 | { | |
352 | struct blk_mq_tag_set *set = q->tag_set; | |
353 | struct blk_mq_hw_ctx *hctx; | |
354 | int ret, i; | |
355 | ||
356 | /* | |
357 | * Default to 256, since we don't split into sync/async like the | |
358 | * old code did. Additionally, this is a per-hw queue depth. | |
359 | */ | |
360 | q->nr_requests = 2 * BLKDEV_MAX_RQ; | |
361 | ||
362 | /* | |
363 | * We're switching to using an IO scheduler, so setup the hctx | |
364 | * scheduler tags and switch the request map from the regular | |
365 | * tags to scheduler tags. First allocate what we need, so we | |
366 | * can safely fail and fallback, if needed. | |
367 | */ | |
368 | ret = 0; | |
369 | queue_for_each_hw_ctx(q, hctx, i) { | |
370 | hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0); | |
371 | if (!hctx->sched_tags) { | |
372 | ret = -ENOMEM; | |
373 | break; | |
374 | } | |
375 | ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests); | |
376 | if (ret) | |
377 | break; | |
378 | } | |
379 | ||
380 | /* | |
381 | * If we failed, free what we did allocate | |
382 | */ | |
383 | if (ret) { | |
384 | queue_for_each_hw_ctx(q, hctx, i) { | |
385 | if (!hctx->sched_tags) | |
386 | continue; | |
387 | blk_mq_sched_free_tags(set, hctx, i); | |
388 | } | |
389 | ||
390 | return ret; | |
391 | } | |
392 | ||
393 | return 0; | |
394 | } | |
395 | ||
396 | void blk_mq_sched_teardown(struct request_queue *q) | |
397 | { | |
398 | struct blk_mq_tag_set *set = q->tag_set; | |
399 | struct blk_mq_hw_ctx *hctx; | |
400 | int i; | |
401 | ||
402 | queue_for_each_hw_ctx(q, hctx, i) | |
403 | blk_mq_sched_free_tags(set, hctx, i); | |
404 | } | |
d3484991 JA |
405 | |
406 | int blk_mq_sched_init(struct request_queue *q) | |
407 | { | |
408 | int ret; | |
409 | ||
410 | #if defined(CONFIG_DEFAULT_SQ_NONE) | |
411 | if (q->nr_hw_queues == 1) | |
412 | return 0; | |
413 | #endif | |
414 | #if defined(CONFIG_DEFAULT_MQ_NONE) | |
415 | if (q->nr_hw_queues > 1) | |
416 | return 0; | |
417 | #endif | |
418 | ||
419 | mutex_lock(&q->sysfs_lock); | |
420 | ret = elevator_init(q, NULL); | |
421 | mutex_unlock(&q->sysfs_lock); | |
422 | ||
423 | return ret; | |
424 | } |