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Commit | Line | Data |
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75bb4625 | 1 | /* |
88459642 OS |
2 | * Tag allocation using scalable bitmaps. Uses active queue tracking to support |
3 | * fairer distribution of tags between multiple submitters when a shared tag map | |
4 | * is used. | |
75bb4625 JA |
5 | * |
6 | * Copyright (C) 2013-2014 Jens Axboe | |
7 | */ | |
320ae51f JA |
8 | #include <linux/kernel.h> |
9 | #include <linux/module.h> | |
320ae51f JA |
10 | |
11 | #include <linux/blk-mq.h> | |
12 | #include "blk.h" | |
13 | #include "blk-mq.h" | |
14 | #include "blk-mq-tag.h" | |
15 | ||
320ae51f JA |
16 | bool blk_mq_has_free_tags(struct blk_mq_tags *tags) |
17 | { | |
4bb659b1 JA |
18 | if (!tags) |
19 | return true; | |
20 | ||
88459642 | 21 | return sbitmap_any_bit_clear(&tags->bitmap_tags.sb); |
0d2602ca JA |
22 | } |
23 | ||
24 | /* | |
25 | * If a previously inactive queue goes active, bump the active user count. | |
662e29d9 JW |
26 | * We need to do this before try to allocate driver tag, then even if fail |
27 | * to get tag when first time, the other shared-tag users could reserve | |
28 | * budget for it. | |
0d2602ca JA |
29 | */ |
30 | bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) | |
31 | { | |
32 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && | |
33 | !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
34 | atomic_inc(&hctx->tags->active_queues); | |
35 | ||
36 | return true; | |
37 | } | |
38 | ||
39 | /* | |
aed3ea94 | 40 | * Wakeup all potentially sleeping on tags |
0d2602ca | 41 | */ |
aed3ea94 | 42 | void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve) |
0d2602ca | 43 | { |
88459642 OS |
44 | sbitmap_queue_wake_all(&tags->bitmap_tags); |
45 | if (include_reserve) | |
46 | sbitmap_queue_wake_all(&tags->breserved_tags); | |
0d2602ca JA |
47 | } |
48 | ||
e3a2b3f9 JA |
49 | /* |
50 | * If a previously busy queue goes inactive, potential waiters could now | |
51 | * be allowed to queue. Wake them up and check. | |
52 | */ | |
53 | void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) | |
54 | { | |
55 | struct blk_mq_tags *tags = hctx->tags; | |
56 | ||
57 | if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
58 | return; | |
59 | ||
60 | atomic_dec(&tags->active_queues); | |
61 | ||
aed3ea94 | 62 | blk_mq_tag_wakeup_all(tags, false); |
e3a2b3f9 JA |
63 | } |
64 | ||
0d2602ca JA |
65 | /* |
66 | * For shared tag users, we track the number of currently active users | |
67 | * and attempt to provide a fair share of the tag depth for each of them. | |
68 | */ | |
69 | static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, | |
88459642 | 70 | struct sbitmap_queue *bt) |
0d2602ca JA |
71 | { |
72 | unsigned int depth, users; | |
73 | ||
74 | if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED)) | |
75 | return true; | |
76 | if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) | |
77 | return true; | |
78 | ||
79 | /* | |
80 | * Don't try dividing an ant | |
81 | */ | |
88459642 | 82 | if (bt->sb.depth == 1) |
0d2602ca JA |
83 | return true; |
84 | ||
85 | users = atomic_read(&hctx->tags->active_queues); | |
86 | if (!users) | |
87 | return true; | |
88 | ||
89 | /* | |
90 | * Allow at least some tags | |
91 | */ | |
88459642 | 92 | depth = max((bt->sb.depth + users - 1) / users, 4U); |
0d2602ca JA |
93 | return atomic_read(&hctx->nr_active) < depth; |
94 | } | |
95 | ||
200e86b3 JA |
96 | static int __blk_mq_get_tag(struct blk_mq_alloc_data *data, |
97 | struct sbitmap_queue *bt) | |
4bb659b1 | 98 | { |
200e86b3 JA |
99 | if (!(data->flags & BLK_MQ_REQ_INTERNAL) && |
100 | !hctx_may_queue(data->hctx, bt)) | |
0d2602ca | 101 | return -1; |
229a9287 OS |
102 | if (data->shallow_depth) |
103 | return __sbitmap_queue_get_shallow(bt, data->shallow_depth); | |
104 | else | |
105 | return __sbitmap_queue_get(bt); | |
4bb659b1 JA |
106 | } |
107 | ||
4941115b | 108 | unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) |
320ae51f | 109 | { |
4941115b JA |
110 | struct blk_mq_tags *tags = blk_mq_tags_from_data(data); |
111 | struct sbitmap_queue *bt; | |
88459642 | 112 | struct sbq_wait_state *ws; |
4bb659b1 | 113 | DEFINE_WAIT(wait); |
4941115b | 114 | unsigned int tag_offset; |
bd6737f1 | 115 | bool drop_ctx; |
320ae51f JA |
116 | int tag; |
117 | ||
4941115b JA |
118 | if (data->flags & BLK_MQ_REQ_RESERVED) { |
119 | if (unlikely(!tags->nr_reserved_tags)) { | |
120 | WARN_ON_ONCE(1); | |
121 | return BLK_MQ_TAG_FAIL; | |
122 | } | |
123 | bt = &tags->breserved_tags; | |
124 | tag_offset = 0; | |
125 | } else { | |
126 | bt = &tags->bitmap_tags; | |
127 | tag_offset = tags->nr_reserved_tags; | |
128 | } | |
129 | ||
200e86b3 | 130 | tag = __blk_mq_get_tag(data, bt); |
4bb659b1 | 131 | if (tag != -1) |
4941115b | 132 | goto found_tag; |
4bb659b1 | 133 | |
6f3b0e8b | 134 | if (data->flags & BLK_MQ_REQ_NOWAIT) |
4941115b | 135 | return BLK_MQ_TAG_FAIL; |
4bb659b1 | 136 | |
4941115b | 137 | ws = bt_wait_ptr(bt, data->hctx); |
bd6737f1 | 138 | drop_ctx = data->ctx == NULL; |
4bb659b1 | 139 | do { |
88459642 | 140 | prepare_to_wait(&ws->wait, &wait, TASK_UNINTERRUPTIBLE); |
4bb659b1 | 141 | |
200e86b3 | 142 | tag = __blk_mq_get_tag(data, bt); |
4bb659b1 JA |
143 | if (tag != -1) |
144 | break; | |
145 | ||
b3223207 BVA |
146 | /* |
147 | * We're out of tags on this hardware queue, kick any | |
148 | * pending IO submits before going to sleep waiting for | |
8cecb07d | 149 | * some to complete. |
b3223207 | 150 | */ |
8cecb07d | 151 | blk_mq_run_hw_queue(data->hctx, false); |
b3223207 | 152 | |
080ff351 JA |
153 | /* |
154 | * Retry tag allocation after running the hardware queue, | |
155 | * as running the queue may also have found completions. | |
156 | */ | |
200e86b3 | 157 | tag = __blk_mq_get_tag(data, bt); |
080ff351 JA |
158 | if (tag != -1) |
159 | break; | |
160 | ||
bd6737f1 JA |
161 | if (data->ctx) |
162 | blk_mq_put_ctx(data->ctx); | |
cb96a42c | 163 | |
4bb659b1 | 164 | io_schedule(); |
cb96a42c ML |
165 | |
166 | data->ctx = blk_mq_get_ctx(data->q); | |
7d7e0f90 | 167 | data->hctx = blk_mq_map_queue(data->q, data->ctx->cpu); |
4941115b JA |
168 | tags = blk_mq_tags_from_data(data); |
169 | if (data->flags & BLK_MQ_REQ_RESERVED) | |
170 | bt = &tags->breserved_tags; | |
171 | else | |
172 | bt = &tags->bitmap_tags; | |
173 | ||
88459642 | 174 | finish_wait(&ws->wait, &wait); |
4941115b | 175 | ws = bt_wait_ptr(bt, data->hctx); |
4bb659b1 JA |
176 | } while (1); |
177 | ||
bd6737f1 JA |
178 | if (drop_ctx && data->ctx) |
179 | blk_mq_put_ctx(data->ctx); | |
180 | ||
88459642 | 181 | finish_wait(&ws->wait, &wait); |
320ae51f | 182 | |
4941115b JA |
183 | found_tag: |
184 | return tag + tag_offset; | |
320ae51f JA |
185 | } |
186 | ||
4941115b JA |
187 | void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags, |
188 | struct blk_mq_ctx *ctx, unsigned int tag) | |
320ae51f | 189 | { |
415b806d | 190 | if (!blk_mq_tag_is_reserved(tags, tag)) { |
4bb659b1 JA |
191 | const int real_tag = tag - tags->nr_reserved_tags; |
192 | ||
70114c39 | 193 | BUG_ON(real_tag >= tags->nr_tags); |
f4a644db | 194 | sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu); |
70114c39 JA |
195 | } else { |
196 | BUG_ON(tag >= tags->nr_reserved_tags); | |
f4a644db | 197 | sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu); |
70114c39 | 198 | } |
320ae51f JA |
199 | } |
200 | ||
88459642 OS |
201 | struct bt_iter_data { |
202 | struct blk_mq_hw_ctx *hctx; | |
203 | busy_iter_fn *fn; | |
204 | void *data; | |
205 | bool reserved; | |
206 | }; | |
207 | ||
208 | static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) | |
320ae51f | 209 | { |
88459642 OS |
210 | struct bt_iter_data *iter_data = data; |
211 | struct blk_mq_hw_ctx *hctx = iter_data->hctx; | |
212 | struct blk_mq_tags *tags = hctx->tags; | |
213 | bool reserved = iter_data->reserved; | |
81481eb4 | 214 | struct request *rq; |
4bb659b1 | 215 | |
88459642 OS |
216 | if (!reserved) |
217 | bitnr += tags->nr_reserved_tags; | |
218 | rq = tags->rqs[bitnr]; | |
4bb659b1 | 219 | |
7f5562d5 JA |
220 | /* |
221 | * We can hit rq == NULL here, because the tagging functions | |
222 | * test and set the bit before assining ->rqs[]. | |
223 | */ | |
224 | if (rq && rq->q == hctx->queue) | |
88459642 OS |
225 | iter_data->fn(hctx, rq, iter_data->data, reserved); |
226 | return true; | |
227 | } | |
4bb659b1 | 228 | |
88459642 OS |
229 | static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt, |
230 | busy_iter_fn *fn, void *data, bool reserved) | |
231 | { | |
232 | struct bt_iter_data iter_data = { | |
233 | .hctx = hctx, | |
234 | .fn = fn, | |
235 | .data = data, | |
236 | .reserved = reserved, | |
237 | }; | |
238 | ||
239 | sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data); | |
320ae51f JA |
240 | } |
241 | ||
88459642 OS |
242 | struct bt_tags_iter_data { |
243 | struct blk_mq_tags *tags; | |
244 | busy_tag_iter_fn *fn; | |
245 | void *data; | |
246 | bool reserved; | |
247 | }; | |
248 | ||
249 | static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) | |
f26cdc85 | 250 | { |
88459642 OS |
251 | struct bt_tags_iter_data *iter_data = data; |
252 | struct blk_mq_tags *tags = iter_data->tags; | |
253 | bool reserved = iter_data->reserved; | |
f26cdc85 | 254 | struct request *rq; |
f26cdc85 | 255 | |
88459642 OS |
256 | if (!reserved) |
257 | bitnr += tags->nr_reserved_tags; | |
7f5562d5 JA |
258 | |
259 | /* | |
260 | * We can hit rq == NULL here, because the tagging functions | |
261 | * test and set the bit before assining ->rqs[]. | |
262 | */ | |
88459642 | 263 | rq = tags->rqs[bitnr]; |
7f5562d5 JA |
264 | if (rq) |
265 | iter_data->fn(rq, iter_data->data, reserved); | |
f26cdc85 | 266 | |
88459642 OS |
267 | return true; |
268 | } | |
269 | ||
270 | static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, | |
271 | busy_tag_iter_fn *fn, void *data, bool reserved) | |
272 | { | |
273 | struct bt_tags_iter_data iter_data = { | |
274 | .tags = tags, | |
275 | .fn = fn, | |
276 | .data = data, | |
277 | .reserved = reserved, | |
278 | }; | |
279 | ||
280 | if (tags->rqs) | |
281 | sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data); | |
f26cdc85 KB |
282 | } |
283 | ||
e8f1e163 SG |
284 | static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, |
285 | busy_tag_iter_fn *fn, void *priv) | |
f26cdc85 KB |
286 | { |
287 | if (tags->nr_reserved_tags) | |
88459642 OS |
288 | bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true); |
289 | bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false); | |
f26cdc85 | 290 | } |
f26cdc85 | 291 | |
e0489487 SG |
292 | void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, |
293 | busy_tag_iter_fn *fn, void *priv) | |
294 | { | |
295 | int i; | |
296 | ||
297 | for (i = 0; i < tagset->nr_hw_queues; i++) { | |
298 | if (tagset->tags && tagset->tags[i]) | |
299 | blk_mq_all_tag_busy_iter(tagset->tags[i], fn, priv); | |
300 | } | |
301 | } | |
302 | EXPORT_SYMBOL(blk_mq_tagset_busy_iter); | |
303 | ||
149e10f8 SG |
304 | int blk_mq_tagset_iter(struct blk_mq_tag_set *set, void *data, |
305 | int (fn)(void *, struct request *)) | |
486cf989 SG |
306 | { |
307 | int i, j, ret = 0; | |
308 | ||
149e10f8 | 309 | if (WARN_ON_ONCE(!fn)) |
486cf989 SG |
310 | goto out; |
311 | ||
312 | for (i = 0; i < set->nr_hw_queues; i++) { | |
313 | struct blk_mq_tags *tags = set->tags[i]; | |
314 | ||
0067d4b0 SG |
315 | if (!tags) |
316 | continue; | |
317 | ||
486cf989 | 318 | for (j = 0; j < tags->nr_tags; j++) { |
2af8cbe3 | 319 | if (!tags->static_rqs[j]) |
486cf989 SG |
320 | continue; |
321 | ||
149e10f8 | 322 | ret = fn(data, tags->static_rqs[j]); |
486cf989 SG |
323 | if (ret) |
324 | goto out; | |
325 | } | |
326 | } | |
327 | ||
328 | out: | |
329 | return ret; | |
330 | } | |
149e10f8 SG |
331 | EXPORT_SYMBOL_GPL(blk_mq_tagset_iter); |
332 | ||
0bf6cd5b | 333 | void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, |
81481eb4 | 334 | void *priv) |
320ae51f | 335 | { |
0bf6cd5b CH |
336 | struct blk_mq_hw_ctx *hctx; |
337 | int i; | |
338 | ||
339 | ||
340 | queue_for_each_hw_ctx(q, hctx, i) { | |
341 | struct blk_mq_tags *tags = hctx->tags; | |
342 | ||
343 | /* | |
344 | * If not software queues are currently mapped to this | |
345 | * hardware queue, there's nothing to check | |
346 | */ | |
347 | if (!blk_mq_hw_queue_mapped(hctx)) | |
348 | continue; | |
349 | ||
350 | if (tags->nr_reserved_tags) | |
88459642 OS |
351 | bt_for_each(hctx, &tags->breserved_tags, fn, priv, true); |
352 | bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false); | |
4bb659b1 JA |
353 | } |
354 | ||
4bb659b1 JA |
355 | } |
356 | ||
f4a644db OS |
357 | static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth, |
358 | bool round_robin, int node) | |
4bb659b1 | 359 | { |
f4a644db OS |
360 | return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL, |
361 | node); | |
4bb659b1 JA |
362 | } |
363 | ||
364 | static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, | |
24391c0d | 365 | int node, int alloc_policy) |
4bb659b1 JA |
366 | { |
367 | unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; | |
f4a644db | 368 | bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; |
4bb659b1 | 369 | |
f4a644db | 370 | if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node)) |
88459642 | 371 | goto free_tags; |
f4a644db OS |
372 | if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin, |
373 | node)) | |
88459642 | 374 | goto free_bitmap_tags; |
4bb659b1 JA |
375 | |
376 | return tags; | |
88459642 OS |
377 | free_bitmap_tags: |
378 | sbitmap_queue_free(&tags->bitmap_tags); | |
379 | free_tags: | |
4bb659b1 JA |
380 | kfree(tags); |
381 | return NULL; | |
382 | } | |
383 | ||
320ae51f | 384 | struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
24391c0d SL |
385 | unsigned int reserved_tags, |
386 | int node, int alloc_policy) | |
320ae51f | 387 | { |
320ae51f | 388 | struct blk_mq_tags *tags; |
320ae51f JA |
389 | |
390 | if (total_tags > BLK_MQ_TAG_MAX) { | |
391 | pr_err("blk-mq: tag depth too large\n"); | |
392 | return NULL; | |
393 | } | |
394 | ||
395 | tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); | |
396 | if (!tags) | |
397 | return NULL; | |
398 | ||
320ae51f JA |
399 | tags->nr_tags = total_tags; |
400 | tags->nr_reserved_tags = reserved_tags; | |
320ae51f | 401 | |
24391c0d | 402 | return blk_mq_init_bitmap_tags(tags, node, alloc_policy); |
320ae51f JA |
403 | } |
404 | ||
405 | void blk_mq_free_tags(struct blk_mq_tags *tags) | |
406 | { | |
88459642 OS |
407 | sbitmap_queue_free(&tags->bitmap_tags); |
408 | sbitmap_queue_free(&tags->breserved_tags); | |
320ae51f JA |
409 | kfree(tags); |
410 | } | |
411 | ||
70f36b60 JA |
412 | int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, |
413 | struct blk_mq_tags **tagsptr, unsigned int tdepth, | |
414 | bool can_grow) | |
e3a2b3f9 | 415 | { |
70f36b60 JA |
416 | struct blk_mq_tags *tags = *tagsptr; |
417 | ||
418 | if (tdepth <= tags->nr_reserved_tags) | |
e3a2b3f9 JA |
419 | return -EINVAL; |
420 | ||
421 | /* | |
70f36b60 JA |
422 | * If we are allowed to grow beyond the original size, allocate |
423 | * a new set of tags before freeing the old one. | |
e3a2b3f9 | 424 | */ |
70f36b60 JA |
425 | if (tdepth > tags->nr_tags) { |
426 | struct blk_mq_tag_set *set = hctx->queue->tag_set; | |
427 | struct blk_mq_tags *new; | |
428 | bool ret; | |
429 | ||
430 | if (!can_grow) | |
431 | return -EINVAL; | |
432 | ||
433 | /* | |
434 | * We need some sort of upper limit, set it high enough that | |
435 | * no valid use cases should require more. | |
436 | */ | |
437 | if (tdepth > 16 * BLKDEV_MAX_RQ) | |
438 | return -EINVAL; | |
439 | ||
bea28a19 ML |
440 | new = blk_mq_alloc_rq_map(set, hctx->queue_num, tdepth, |
441 | tags->nr_reserved_tags); | |
70f36b60 JA |
442 | if (!new) |
443 | return -ENOMEM; | |
444 | ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth); | |
445 | if (ret) { | |
446 | blk_mq_free_rq_map(new); | |
447 | return -ENOMEM; | |
448 | } | |
449 | ||
450 | blk_mq_free_rqs(set, *tagsptr, hctx->queue_num); | |
451 | blk_mq_free_rq_map(*tagsptr); | |
452 | *tagsptr = new; | |
453 | } else { | |
454 | /* | |
455 | * Don't need (or can't) update reserved tags here, they | |
456 | * remain static and should never need resizing. | |
457 | */ | |
bea28a19 ML |
458 | sbitmap_queue_resize(&tags->bitmap_tags, |
459 | tdepth - tags->nr_reserved_tags); | |
70f36b60 | 460 | } |
88459642 | 461 | |
e3a2b3f9 JA |
462 | return 0; |
463 | } | |
464 | ||
205fb5f5 BVA |
465 | /** |
466 | * blk_mq_unique_tag() - return a tag that is unique queue-wide | |
467 | * @rq: request for which to compute a unique tag | |
468 | * | |
469 | * The tag field in struct request is unique per hardware queue but not over | |
470 | * all hardware queues. Hence this function that returns a tag with the | |
471 | * hardware context index in the upper bits and the per hardware queue tag in | |
472 | * the lower bits. | |
473 | * | |
474 | * Note: When called for a request that is queued on a non-multiqueue request | |
475 | * queue, the hardware context index is set to zero. | |
476 | */ | |
477 | u32 blk_mq_unique_tag(struct request *rq) | |
478 | { | |
479 | struct request_queue *q = rq->q; | |
480 | struct blk_mq_hw_ctx *hctx; | |
481 | int hwq = 0; | |
482 | ||
483 | if (q->mq_ops) { | |
7d7e0f90 | 484 | hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu); |
205fb5f5 BVA |
485 | hwq = hctx->queue_num; |
486 | } | |
487 | ||
488 | return (hwq << BLK_MQ_UNIQUE_TAG_BITS) | | |
489 | (rq->tag & BLK_MQ_UNIQUE_TAG_MASK); | |
490 | } | |
491 | EXPORT_SYMBOL(blk_mq_unique_tag); |