vti4: eliminated some duplicate code.
[linux/fpc-iii.git] / block / blk-mq-tag.c
blob41317c50a44628e9ef4930e9f17ad6d8297c9190
1 /*
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.
6 * Copyright (C) 2013-2014 Jens Axboe
7 */
8 #include <linux/kernel.h>
9 #include <linux/module.h>
11 #include <linux/blk-mq.h>
12 #include "blk.h"
13 #include "blk-mq.h"
14 #include "blk-mq-tag.h"
16 bool blk_mq_has_free_tags(struct blk_mq_tags *tags)
18 if (!tags)
19 return true;
21 return sbitmap_any_bit_clear(&tags->bitmap_tags.sb);
25 * If a previously inactive queue goes active, bump the active user count.
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.
30 bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
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);
36 return true;
40 * Wakeup all potentially sleeping on tags
42 void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve)
44 sbitmap_queue_wake_all(&tags->bitmap_tags);
45 if (include_reserve)
46 sbitmap_queue_wake_all(&tags->breserved_tags);
50 * If a previously busy queue goes inactive, potential waiters could now
51 * be allowed to queue. Wake them up and check.
53 void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
55 struct blk_mq_tags *tags = hctx->tags;
57 if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
58 return;
60 atomic_dec(&tags->active_queues);
62 blk_mq_tag_wakeup_all(tags, false);
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.
69 static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
70 struct sbitmap_queue *bt)
72 unsigned int depth, users;
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;
80 * Don't try dividing an ant
82 if (bt->sb.depth == 1)
83 return true;
85 users = atomic_read(&hctx->tags->active_queues);
86 if (!users)
87 return true;
90 * Allow at least some tags
92 depth = max((bt->sb.depth + users - 1) / users, 4U);
93 return atomic_read(&hctx->nr_active) < depth;
96 static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
97 struct sbitmap_queue *bt)
99 if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&
100 !hctx_may_queue(data->hctx, bt))
101 return -1;
102 if (data->shallow_depth)
103 return __sbitmap_queue_get_shallow(bt, data->shallow_depth);
104 else
105 return __sbitmap_queue_get(bt);
108 unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
110 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
111 struct sbitmap_queue *bt;
112 struct sbq_wait_state *ws;
113 DEFINE_WAIT(wait);
114 unsigned int tag_offset;
115 bool drop_ctx;
116 int tag;
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;
123 bt = &tags->breserved_tags;
124 tag_offset = 0;
125 } else {
126 bt = &tags->bitmap_tags;
127 tag_offset = tags->nr_reserved_tags;
130 tag = __blk_mq_get_tag(data, bt);
131 if (tag != -1)
132 goto found_tag;
134 if (data->flags & BLK_MQ_REQ_NOWAIT)
135 return BLK_MQ_TAG_FAIL;
137 ws = bt_wait_ptr(bt, data->hctx);
138 drop_ctx = data->ctx == NULL;
139 do {
140 struct sbitmap_queue *bt_prev;
143 * We're out of tags on this hardware queue, kick any
144 * pending IO submits before going to sleep waiting for
145 * some to complete.
147 blk_mq_run_hw_queue(data->hctx, false);
150 * Retry tag allocation after running the hardware queue,
151 * as running the queue may also have found completions.
153 tag = __blk_mq_get_tag(data, bt);
154 if (tag != -1)
155 break;
157 prepare_to_wait_exclusive(&ws->wait, &wait,
158 TASK_UNINTERRUPTIBLE);
160 tag = __blk_mq_get_tag(data, bt);
161 if (tag != -1)
162 break;
164 if (data->ctx)
165 blk_mq_put_ctx(data->ctx);
167 bt_prev = bt;
168 io_schedule();
170 data->ctx = blk_mq_get_ctx(data->q);
171 data->hctx = blk_mq_map_queue(data->q, data->ctx->cpu);
172 tags = blk_mq_tags_from_data(data);
173 if (data->flags & BLK_MQ_REQ_RESERVED)
174 bt = &tags->breserved_tags;
175 else
176 bt = &tags->bitmap_tags;
178 finish_wait(&ws->wait, &wait);
181 * If destination hw queue is changed, fake wake up on
182 * previous queue for compensating the wake up miss, so
183 * other allocations on previous queue won't be starved.
185 if (bt != bt_prev)
186 sbitmap_queue_wake_up(bt_prev);
188 ws = bt_wait_ptr(bt, data->hctx);
189 } while (1);
191 if (drop_ctx && data->ctx)
192 blk_mq_put_ctx(data->ctx);
194 finish_wait(&ws->wait, &wait);
196 found_tag:
197 return tag + tag_offset;
200 void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags,
201 struct blk_mq_ctx *ctx, unsigned int tag)
203 if (!blk_mq_tag_is_reserved(tags, tag)) {
204 const int real_tag = tag - tags->nr_reserved_tags;
206 BUG_ON(real_tag >= tags->nr_tags);
207 sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu);
208 } else {
209 BUG_ON(tag >= tags->nr_reserved_tags);
210 sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu);
214 struct bt_iter_data {
215 struct blk_mq_hw_ctx *hctx;
216 busy_iter_fn *fn;
217 void *data;
218 bool reserved;
221 static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
223 struct bt_iter_data *iter_data = data;
224 struct blk_mq_hw_ctx *hctx = iter_data->hctx;
225 struct blk_mq_tags *tags = hctx->tags;
226 bool reserved = iter_data->reserved;
227 struct request *rq;
229 if (!reserved)
230 bitnr += tags->nr_reserved_tags;
231 rq = tags->rqs[bitnr];
234 * We can hit rq == NULL here, because the tagging functions
235 * test and set the bit before assining ->rqs[].
237 if (rq && rq->q == hctx->queue)
238 iter_data->fn(hctx, rq, iter_data->data, reserved);
239 return true;
242 static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt,
243 busy_iter_fn *fn, void *data, bool reserved)
245 struct bt_iter_data iter_data = {
246 .hctx = hctx,
247 .fn = fn,
248 .data = data,
249 .reserved = reserved,
252 sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data);
255 struct bt_tags_iter_data {
256 struct blk_mq_tags *tags;
257 busy_tag_iter_fn *fn;
258 void *data;
259 bool reserved;
262 static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
264 struct bt_tags_iter_data *iter_data = data;
265 struct blk_mq_tags *tags = iter_data->tags;
266 bool reserved = iter_data->reserved;
267 struct request *rq;
269 if (!reserved)
270 bitnr += tags->nr_reserved_tags;
273 * We can hit rq == NULL here, because the tagging functions
274 * test and set the bit before assining ->rqs[].
276 rq = tags->rqs[bitnr];
277 if (rq && blk_mq_request_started(rq))
278 iter_data->fn(rq, iter_data->data, reserved);
280 return true;
283 static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt,
284 busy_tag_iter_fn *fn, void *data, bool reserved)
286 struct bt_tags_iter_data iter_data = {
287 .tags = tags,
288 .fn = fn,
289 .data = data,
290 .reserved = reserved,
293 if (tags->rqs)
294 sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data);
297 static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags,
298 busy_tag_iter_fn *fn, void *priv)
300 if (tags->nr_reserved_tags)
301 bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true);
302 bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false);
305 void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
306 busy_tag_iter_fn *fn, void *priv)
308 int i;
310 for (i = 0; i < tagset->nr_hw_queues; i++) {
311 if (tagset->tags && tagset->tags[i])
312 blk_mq_all_tag_busy_iter(tagset->tags[i], fn, priv);
315 EXPORT_SYMBOL(blk_mq_tagset_busy_iter);
317 void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn,
318 void *priv)
320 struct blk_mq_hw_ctx *hctx;
321 int i;
324 * __blk_mq_update_nr_hw_queues will update the nr_hw_queues and
325 * queue_hw_ctx after freeze the queue, so we use q_usage_counter
326 * to avoid race with it.
328 if (!percpu_ref_tryget(&q->q_usage_counter))
329 return;
331 queue_for_each_hw_ctx(q, hctx, i) {
332 struct blk_mq_tags *tags = hctx->tags;
335 * If not software queues are currently mapped to this
336 * hardware queue, there's nothing to check
338 if (!blk_mq_hw_queue_mapped(hctx))
339 continue;
341 if (tags->nr_reserved_tags)
342 bt_for_each(hctx, &tags->breserved_tags, fn, priv, true);
343 bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false);
345 blk_queue_exit(q);
348 static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth,
349 bool round_robin, int node)
351 return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL,
352 node);
355 static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
356 int node, int alloc_policy)
358 unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
359 bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR;
361 if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node))
362 goto free_tags;
363 if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin,
364 node))
365 goto free_bitmap_tags;
367 return tags;
368 free_bitmap_tags:
369 sbitmap_queue_free(&tags->bitmap_tags);
370 free_tags:
371 kfree(tags);
372 return NULL;
375 struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
376 unsigned int reserved_tags,
377 int node, int alloc_policy)
379 struct blk_mq_tags *tags;
381 if (total_tags > BLK_MQ_TAG_MAX) {
382 pr_err("blk-mq: tag depth too large\n");
383 return NULL;
386 tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node);
387 if (!tags)
388 return NULL;
390 tags->nr_tags = total_tags;
391 tags->nr_reserved_tags = reserved_tags;
393 return blk_mq_init_bitmap_tags(tags, node, alloc_policy);
396 void blk_mq_free_tags(struct blk_mq_tags *tags)
398 sbitmap_queue_free(&tags->bitmap_tags);
399 sbitmap_queue_free(&tags->breserved_tags);
400 kfree(tags);
403 int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
404 struct blk_mq_tags **tagsptr, unsigned int tdepth,
405 bool can_grow)
407 struct blk_mq_tags *tags = *tagsptr;
409 if (tdepth <= tags->nr_reserved_tags)
410 return -EINVAL;
413 * If we are allowed to grow beyond the original size, allocate
414 * a new set of tags before freeing the old one.
416 if (tdepth > tags->nr_tags) {
417 struct blk_mq_tag_set *set = hctx->queue->tag_set;
418 struct blk_mq_tags *new;
419 bool ret;
421 if (!can_grow)
422 return -EINVAL;
425 * We need some sort of upper limit, set it high enough that
426 * no valid use cases should require more.
428 if (tdepth > 16 * BLKDEV_MAX_RQ)
429 return -EINVAL;
431 new = blk_mq_alloc_rq_map(set, hctx->queue_num, tdepth,
432 tags->nr_reserved_tags);
433 if (!new)
434 return -ENOMEM;
435 ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth);
436 if (ret) {
437 blk_mq_free_rq_map(new);
438 return -ENOMEM;
441 blk_mq_free_rqs(set, *tagsptr, hctx->queue_num);
442 blk_mq_free_rq_map(*tagsptr);
443 *tagsptr = new;
444 } else {
446 * Don't need (or can't) update reserved tags here, they
447 * remain static and should never need resizing.
449 sbitmap_queue_resize(&tags->bitmap_tags,
450 tdepth - tags->nr_reserved_tags);
453 return 0;
457 * blk_mq_unique_tag() - return a tag that is unique queue-wide
458 * @rq: request for which to compute a unique tag
460 * The tag field in struct request is unique per hardware queue but not over
461 * all hardware queues. Hence this function that returns a tag with the
462 * hardware context index in the upper bits and the per hardware queue tag in
463 * the lower bits.
465 * Note: When called for a request that is queued on a non-multiqueue request
466 * queue, the hardware context index is set to zero.
468 u32 blk_mq_unique_tag(struct request *rq)
470 struct request_queue *q = rq->q;
471 struct blk_mq_hw_ctx *hctx;
472 int hwq = 0;
474 if (q->mq_ops) {
475 hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
476 hwq = hctx->queue_num;
479 return (hwq << BLK_MQ_UNIQUE_TAG_BITS) |
480 (rq->tag & BLK_MQ_UNIQUE_TAG_MASK);
482 EXPORT_SYMBOL(blk_mq_unique_tag);