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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.
5 *
6 * Copyright (C) 2013-2014 Jens Axboe
7 */
8#include <linux/kernel.h>
9#include <linux/module.h>
10
11#include <linux/blk-mq.h>
12#include "blk.h"
13#include "blk-mq.h"
14#include "blk-mq-tag.h"
15
16bool blk_mq_has_free_tags(struct blk_mq_tags *tags)
17{
18 if (!tags)
19 return true;
20
21 return sbitmap_any_bit_clear(&tags->bitmap_tags.sb);
22}
23
24/*
25 * If a previously inactive queue goes active, bump the active user count.
26 */
27bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
28{
29 if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) &&
30 !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
31 atomic_inc(&hctx->tags->active_queues);
32
33 return true;
34}
35
36/*
37 * Wakeup all potentially sleeping on tags
38 */
39void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve)
40{
41 sbitmap_queue_wake_all(&tags->bitmap_tags);
42 if (include_reserve)
43 sbitmap_queue_wake_all(&tags->breserved_tags);
44}
45
46/*
47 * If a previously busy queue goes inactive, potential waiters could now
48 * be allowed to queue. Wake them up and check.
49 */
50void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
51{
52 struct blk_mq_tags *tags = hctx->tags;
53
54 if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
55 return;
56
57 atomic_dec(&tags->active_queues);
58
59 blk_mq_tag_wakeup_all(tags, false);
60}
61
62/*
63 * For shared tag users, we track the number of currently active users
64 * and attempt to provide a fair share of the tag depth for each of them.
65 */
66static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
67 struct sbitmap_queue *bt)
68{
69 unsigned int depth, users;
70
71 if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED))
72 return true;
73 if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
74 return true;
75
76 /*
77 * Don't try dividing an ant
78 */
79 if (bt->sb.depth == 1)
80 return true;
81
82 users = atomic_read(&hctx->tags->active_queues);
83 if (!users)
84 return true;
85
86 /*
87 * Allow at least some tags
88 */
89 depth = max((bt->sb.depth + users - 1) / users, 4U);
90 return atomic_read(&hctx->nr_active) < depth;
91}
92
93static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
94 struct sbitmap_queue *bt)
95{
96 if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&
97 !hctx_may_queue(data->hctx, bt))
98 return -1;
99 if (data->shallow_depth)
100 return __sbitmap_queue_get_shallow(bt, data->shallow_depth);
101 else
102 return __sbitmap_queue_get(bt);
103}
104
105unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
106{
107 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
108 struct sbitmap_queue *bt;
109 struct sbq_wait_state *ws;
110 DEFINE_WAIT(wait);
111 unsigned int tag_offset;
112 bool drop_ctx;
113 int tag;
114
115 if (data->flags & BLK_MQ_REQ_RESERVED) {
116 if (unlikely(!tags->nr_reserved_tags)) {
117 WARN_ON_ONCE(1);
118 return BLK_MQ_TAG_FAIL;
119 }
120 bt = &tags->breserved_tags;
121 tag_offset = 0;
122 } else {
123 bt = &tags->bitmap_tags;
124 tag_offset = tags->nr_reserved_tags;
125 }
126
127 tag = __blk_mq_get_tag(data, bt);
128 if (tag != -1)
129 goto found_tag;
130
131 if (data->flags & BLK_MQ_REQ_NOWAIT)
132 return BLK_MQ_TAG_FAIL;
133
134 ws = bt_wait_ptr(bt, data->hctx);
135 drop_ctx = data->ctx == NULL;
136 do {
137 /*
138 * We're out of tags on this hardware queue, kick any
139 * pending IO submits before going to sleep waiting for
140 * some to complete.
141 */
142 blk_mq_run_hw_queue(data->hctx, false);
143
144 /*
145 * Retry tag allocation after running the hardware queue,
146 * as running the queue may also have found completions.
147 */
148 tag = __blk_mq_get_tag(data, bt);
149 if (tag != -1)
150 break;
151
152 prepare_to_wait_exclusive(&ws->wait, &wait,
153 TASK_UNINTERRUPTIBLE);
154
155 tag = __blk_mq_get_tag(data, bt);
156 if (tag != -1)
157 break;
158
159 if (data->ctx)
160 blk_mq_put_ctx(data->ctx);
161
162 io_schedule();
163
164 data->ctx = blk_mq_get_ctx(data->q);
165 data->hctx = blk_mq_map_queue(data->q, data->ctx->cpu);
166 tags = blk_mq_tags_from_data(data);
167 if (data->flags & BLK_MQ_REQ_RESERVED)
168 bt = &tags->breserved_tags;
169 else
170 bt = &tags->bitmap_tags;
171
172 finish_wait(&ws->wait, &wait);
173 ws = bt_wait_ptr(bt, data->hctx);
174 } while (1);
175
176 if (drop_ctx && data->ctx)
177 blk_mq_put_ctx(data->ctx);
178
179 finish_wait(&ws->wait, &wait);
180
181found_tag:
182 return tag + tag_offset;
183}
184
185void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags,
186 struct blk_mq_ctx *ctx, unsigned int tag)
187{
188 if (!blk_mq_tag_is_reserved(tags, tag)) {
189 const int real_tag = tag - tags->nr_reserved_tags;
190
191 BUG_ON(real_tag >= tags->nr_tags);
192 sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu);
193 } else {
194 BUG_ON(tag >= tags->nr_reserved_tags);
195 sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu);
196 }
197}
198
199struct bt_iter_data {
200 struct blk_mq_hw_ctx *hctx;
201 busy_iter_fn *fn;
202 void *data;
203 bool reserved;
204};
205
206static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
207{
208 struct bt_iter_data *iter_data = data;
209 struct blk_mq_hw_ctx *hctx = iter_data->hctx;
210 struct blk_mq_tags *tags = hctx->tags;
211 bool reserved = iter_data->reserved;
212 struct request *rq;
213
214 if (!reserved)
215 bitnr += tags->nr_reserved_tags;
216 rq = tags->rqs[bitnr];
217
218 /*
219 * We can hit rq == NULL here, because the tagging functions
220 * test and set the bit before assining ->rqs[].
221 */
222 if (rq && rq->q == hctx->queue)
223 iter_data->fn(hctx, rq, iter_data->data, reserved);
224 return true;
225}
226
227static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt,
228 busy_iter_fn *fn, void *data, bool reserved)
229{
230 struct bt_iter_data iter_data = {
231 .hctx = hctx,
232 .fn = fn,
233 .data = data,
234 .reserved = reserved,
235 };
236
237 sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data);
238}
239
240struct bt_tags_iter_data {
241 struct blk_mq_tags *tags;
242 busy_tag_iter_fn *fn;
243 void *data;
244 bool reserved;
245};
246
247static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
248{
249 struct bt_tags_iter_data *iter_data = data;
250 struct blk_mq_tags *tags = iter_data->tags;
251 bool reserved = iter_data->reserved;
252 struct request *rq;
253
254 if (!reserved)
255 bitnr += tags->nr_reserved_tags;
256
257 /*
258 * We can hit rq == NULL here, because the tagging functions
259 * test and set the bit before assining ->rqs[].
260 */
261 rq = tags->rqs[bitnr];
262 if (rq)
263 iter_data->fn(rq, iter_data->data, reserved);
264
265 return true;
266}
267
268static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt,
269 busy_tag_iter_fn *fn, void *data, bool reserved)
270{
271 struct bt_tags_iter_data iter_data = {
272 .tags = tags,
273 .fn = fn,
274 .data = data,
275 .reserved = reserved,
276 };
277
278 if (tags->rqs)
279 sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data);
280}
281
282static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags,
283 busy_tag_iter_fn *fn, void *priv)
284{
285 if (tags->nr_reserved_tags)
286 bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true);
287 bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false);
288}
289
290void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
291 busy_tag_iter_fn *fn, void *priv)
292{
293 int i;
294
295 for (i = 0; i < tagset->nr_hw_queues; i++) {
296 if (tagset->tags && tagset->tags[i])
297 blk_mq_all_tag_busy_iter(tagset->tags[i], fn, priv);
298 }
299}
300EXPORT_SYMBOL(blk_mq_tagset_busy_iter);
301
302int blk_mq_tagset_iter(struct blk_mq_tag_set *set, void *data,
303 int (fn)(void *, struct request *))
304{
305 int i, j, ret = 0;
306
307 if (WARN_ON_ONCE(!fn))
308 goto out;
309
310 for (i = 0; i < set->nr_hw_queues; i++) {
311 struct blk_mq_tags *tags = set->tags[i];
312
313 if (!tags)
314 continue;
315
316 for (j = 0; j < tags->nr_tags; j++) {
317 if (!tags->static_rqs[j])
318 continue;
319
320 ret = fn(data, tags->static_rqs[j]);
321 if (ret)
322 goto out;
323 }
324 }
325
326out:
327 return ret;
328}
329EXPORT_SYMBOL_GPL(blk_mq_tagset_iter);
330
331void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn,
332 void *priv)
333{
334 struct blk_mq_hw_ctx *hctx;
335 int i;
336
337
338 queue_for_each_hw_ctx(q, hctx, i) {
339 struct blk_mq_tags *tags = hctx->tags;
340
341 /*
342 * If not software queues are currently mapped to this
343 * hardware queue, there's nothing to check
344 */
345 if (!blk_mq_hw_queue_mapped(hctx))
346 continue;
347
348 if (tags->nr_reserved_tags)
349 bt_for_each(hctx, &tags->breserved_tags, fn, priv, true);
350 bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false);
351 }
352
353}
354
355static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth,
356 bool round_robin, int node)
357{
358 return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL,
359 node);
360}
361
362static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
363 int node, int alloc_policy)
364{
365 unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
366 bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR;
367
368 if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node))
369 goto free_tags;
370 if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin,
371 node))
372 goto free_bitmap_tags;
373
374 return tags;
375free_bitmap_tags:
376 sbitmap_queue_free(&tags->bitmap_tags);
377free_tags:
378 kfree(tags);
379 return NULL;
380}
381
382struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
383 unsigned int reserved_tags,
384 int node, int alloc_policy)
385{
386 struct blk_mq_tags *tags;
387
388 if (total_tags > BLK_MQ_TAG_MAX) {
389 pr_err("blk-mq: tag depth too large\n");
390 return NULL;
391 }
392
393 tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node);
394 if (!tags)
395 return NULL;
396
397 tags->nr_tags = total_tags;
398 tags->nr_reserved_tags = reserved_tags;
399
400 return blk_mq_init_bitmap_tags(tags, node, alloc_policy);
401}
402
403void blk_mq_free_tags(struct blk_mq_tags *tags)
404{
405 sbitmap_queue_free(&tags->bitmap_tags);
406 sbitmap_queue_free(&tags->breserved_tags);
407 kfree(tags);
408}
409
410int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
411 struct blk_mq_tags **tagsptr, unsigned int tdepth,
412 bool can_grow)
413{
414 struct blk_mq_tags *tags = *tagsptr;
415
416 if (tdepth <= tags->nr_reserved_tags)
417 return -EINVAL;
418
419 tdepth -= tags->nr_reserved_tags;
420
421 /*
422 * If we are allowed to grow beyond the original size, allocate
423 * a new set of tags before freeing the old one.
424 */
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
440 new = blk_mq_alloc_rq_map(set, hctx->queue_num, tdepth, 0);
441 if (!new)
442 return -ENOMEM;
443 ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth);
444 if (ret) {
445 blk_mq_free_rq_map(new);
446 return -ENOMEM;
447 }
448
449 blk_mq_free_rqs(set, *tagsptr, hctx->queue_num);
450 blk_mq_free_rq_map(*tagsptr);
451 *tagsptr = new;
452 } else {
453 /*
454 * Don't need (or can't) update reserved tags here, they
455 * remain static and should never need resizing.
456 */
457 sbitmap_queue_resize(&tags->bitmap_tags, tdepth);
458 }
459
460 return 0;
461}
462
463/**
464 * blk_mq_unique_tag() - return a tag that is unique queue-wide
465 * @rq: request for which to compute a unique tag
466 *
467 * The tag field in struct request is unique per hardware queue but not over
468 * all hardware queues. Hence this function that returns a tag with the
469 * hardware context index in the upper bits and the per hardware queue tag in
470 * the lower bits.
471 *
472 * Note: When called for a request that is queued on a non-multiqueue request
473 * queue, the hardware context index is set to zero.
474 */
475u32 blk_mq_unique_tag(struct request *rq)
476{
477 struct request_queue *q = rq->q;
478 struct blk_mq_hw_ctx *hctx;
479 int hwq = 0;
480
481 if (q->mq_ops) {
482 hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
483 hwq = hctx->queue_num;
484 }
485
486 return (hwq << BLK_MQ_UNIQUE_TAG_BITS) |
487 (rq->tag & BLK_MQ_UNIQUE_TAG_MASK);
488}
489EXPORT_SYMBOL(blk_mq_unique_tag);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Tag allocation using scalable bitmaps. Uses active queue tracking to support
4 * fairer distribution of tags between multiple submitters when a shared tag map
5 * is used.
6 *
7 * Copyright (C) 2013-2014 Jens Axboe
8 */
9#include <linux/kernel.h>
10#include <linux/module.h>
11
12#include <linux/blk-mq.h>
13#include <linux/delay.h>
14#include "blk.h"
15#include "blk-mq.h"
16#include "blk-mq-tag.h"
17
18/*
19 * If a previously inactive queue goes active, bump the active user count.
20 * We need to do this before try to allocate driver tag, then even if fail
21 * to get tag when first time, the other shared-tag users could reserve
22 * budget for it.
23 */
24bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
25{
26 if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) &&
27 !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
28 atomic_inc(&hctx->tags->active_queues);
29
30 return true;
31}
32
33/*
34 * Wakeup all potentially sleeping on tags
35 */
36void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve)
37{
38 sbitmap_queue_wake_all(&tags->bitmap_tags);
39 if (include_reserve)
40 sbitmap_queue_wake_all(&tags->breserved_tags);
41}
42
43/*
44 * If a previously busy queue goes inactive, potential waiters could now
45 * be allowed to queue. Wake them up and check.
46 */
47void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
48{
49 struct blk_mq_tags *tags = hctx->tags;
50
51 if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
52 return;
53
54 atomic_dec(&tags->active_queues);
55
56 blk_mq_tag_wakeup_all(tags, false);
57}
58
59static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
60 struct sbitmap_queue *bt)
61{
62 if (!data->q->elevator && !hctx_may_queue(data->hctx, bt))
63 return BLK_MQ_NO_TAG;
64
65 if (data->shallow_depth)
66 return __sbitmap_queue_get_shallow(bt, data->shallow_depth);
67 else
68 return __sbitmap_queue_get(bt);
69}
70
71unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
72{
73 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
74 struct sbitmap_queue *bt;
75 struct sbq_wait_state *ws;
76 DEFINE_SBQ_WAIT(wait);
77 unsigned int tag_offset;
78 int tag;
79
80 if (data->flags & BLK_MQ_REQ_RESERVED) {
81 if (unlikely(!tags->nr_reserved_tags)) {
82 WARN_ON_ONCE(1);
83 return BLK_MQ_NO_TAG;
84 }
85 bt = &tags->breserved_tags;
86 tag_offset = 0;
87 } else {
88 bt = &tags->bitmap_tags;
89 tag_offset = tags->nr_reserved_tags;
90 }
91
92 tag = __blk_mq_get_tag(data, bt);
93 if (tag != BLK_MQ_NO_TAG)
94 goto found_tag;
95
96 if (data->flags & BLK_MQ_REQ_NOWAIT)
97 return BLK_MQ_NO_TAG;
98
99 ws = bt_wait_ptr(bt, data->hctx);
100 do {
101 struct sbitmap_queue *bt_prev;
102
103 /*
104 * We're out of tags on this hardware queue, kick any
105 * pending IO submits before going to sleep waiting for
106 * some to complete.
107 */
108 blk_mq_run_hw_queue(data->hctx, false);
109
110 /*
111 * Retry tag allocation after running the hardware queue,
112 * as running the queue may also have found completions.
113 */
114 tag = __blk_mq_get_tag(data, bt);
115 if (tag != BLK_MQ_NO_TAG)
116 break;
117
118 sbitmap_prepare_to_wait(bt, ws, &wait, TASK_UNINTERRUPTIBLE);
119
120 tag = __blk_mq_get_tag(data, bt);
121 if (tag != BLK_MQ_NO_TAG)
122 break;
123
124 bt_prev = bt;
125 io_schedule();
126
127 sbitmap_finish_wait(bt, ws, &wait);
128
129 data->ctx = blk_mq_get_ctx(data->q);
130 data->hctx = blk_mq_map_queue(data->q, data->cmd_flags,
131 data->ctx);
132 tags = blk_mq_tags_from_data(data);
133 if (data->flags & BLK_MQ_REQ_RESERVED)
134 bt = &tags->breserved_tags;
135 else
136 bt = &tags->bitmap_tags;
137
138 /*
139 * If destination hw queue is changed, fake wake up on
140 * previous queue for compensating the wake up miss, so
141 * other allocations on previous queue won't be starved.
142 */
143 if (bt != bt_prev)
144 sbitmap_queue_wake_up(bt_prev);
145
146 ws = bt_wait_ptr(bt, data->hctx);
147 } while (1);
148
149 sbitmap_finish_wait(bt, ws, &wait);
150
151found_tag:
152 /*
153 * Give up this allocation if the hctx is inactive. The caller will
154 * retry on an active hctx.
155 */
156 if (unlikely(test_bit(BLK_MQ_S_INACTIVE, &data->hctx->state))) {
157 blk_mq_put_tag(tags, data->ctx, tag + tag_offset);
158 return BLK_MQ_NO_TAG;
159 }
160 return tag + tag_offset;
161}
162
163void blk_mq_put_tag(struct blk_mq_tags *tags, struct blk_mq_ctx *ctx,
164 unsigned int tag)
165{
166 if (!blk_mq_tag_is_reserved(tags, tag)) {
167 const int real_tag = tag - tags->nr_reserved_tags;
168
169 BUG_ON(real_tag >= tags->nr_tags);
170 sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu);
171 } else {
172 BUG_ON(tag >= tags->nr_reserved_tags);
173 sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu);
174 }
175}
176
177struct bt_iter_data {
178 struct blk_mq_hw_ctx *hctx;
179 busy_iter_fn *fn;
180 void *data;
181 bool reserved;
182};
183
184static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
185{
186 struct bt_iter_data *iter_data = data;
187 struct blk_mq_hw_ctx *hctx = iter_data->hctx;
188 struct blk_mq_tags *tags = hctx->tags;
189 bool reserved = iter_data->reserved;
190 struct request *rq;
191
192 if (!reserved)
193 bitnr += tags->nr_reserved_tags;
194 rq = tags->rqs[bitnr];
195
196 /*
197 * We can hit rq == NULL here, because the tagging functions
198 * test and set the bit before assigning ->rqs[].
199 */
200 if (rq && rq->q == hctx->queue)
201 return iter_data->fn(hctx, rq, iter_data->data, reserved);
202 return true;
203}
204
205/**
206 * bt_for_each - iterate over the requests associated with a hardware queue
207 * @hctx: Hardware queue to examine.
208 * @bt: sbitmap to examine. This is either the breserved_tags member
209 * or the bitmap_tags member of struct blk_mq_tags.
210 * @fn: Pointer to the function that will be called for each request
211 * associated with @hctx that has been assigned a driver tag.
212 * @fn will be called as follows: @fn(@hctx, rq, @data, @reserved)
213 * where rq is a pointer to a request. Return true to continue
214 * iterating tags, false to stop.
215 * @data: Will be passed as third argument to @fn.
216 * @reserved: Indicates whether @bt is the breserved_tags member or the
217 * bitmap_tags member of struct blk_mq_tags.
218 */
219static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt,
220 busy_iter_fn *fn, void *data, bool reserved)
221{
222 struct bt_iter_data iter_data = {
223 .hctx = hctx,
224 .fn = fn,
225 .data = data,
226 .reserved = reserved,
227 };
228
229 sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data);
230}
231
232struct bt_tags_iter_data {
233 struct blk_mq_tags *tags;
234 busy_tag_iter_fn *fn;
235 void *data;
236 unsigned int flags;
237};
238
239#define BT_TAG_ITER_RESERVED (1 << 0)
240#define BT_TAG_ITER_STARTED (1 << 1)
241#define BT_TAG_ITER_STATIC_RQS (1 << 2)
242
243static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
244{
245 struct bt_tags_iter_data *iter_data = data;
246 struct blk_mq_tags *tags = iter_data->tags;
247 bool reserved = iter_data->flags & BT_TAG_ITER_RESERVED;
248 struct request *rq;
249
250 if (!reserved)
251 bitnr += tags->nr_reserved_tags;
252
253 /*
254 * We can hit rq == NULL here, because the tagging functions
255 * test and set the bit before assigning ->rqs[].
256 */
257 if (iter_data->flags & BT_TAG_ITER_STATIC_RQS)
258 rq = tags->static_rqs[bitnr];
259 else
260 rq = tags->rqs[bitnr];
261 if (!rq)
262 return true;
263 if ((iter_data->flags & BT_TAG_ITER_STARTED) &&
264 !blk_mq_request_started(rq))
265 return true;
266 return iter_data->fn(rq, iter_data->data, reserved);
267}
268
269/**
270 * bt_tags_for_each - iterate over the requests in a tag map
271 * @tags: Tag map to iterate over.
272 * @bt: sbitmap to examine. This is either the breserved_tags member
273 * or the bitmap_tags member of struct blk_mq_tags.
274 * @fn: Pointer to the function that will be called for each started
275 * request. @fn will be called as follows: @fn(rq, @data,
276 * @reserved) where rq is a pointer to a request. Return true
277 * to continue iterating tags, false to stop.
278 * @data: Will be passed as second argument to @fn.
279 * @flags: BT_TAG_ITER_*
280 */
281static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt,
282 busy_tag_iter_fn *fn, void *data, unsigned int flags)
283{
284 struct bt_tags_iter_data iter_data = {
285 .tags = tags,
286 .fn = fn,
287 .data = data,
288 .flags = flags,
289 };
290
291 if (tags->rqs)
292 sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data);
293}
294
295static void __blk_mq_all_tag_iter(struct blk_mq_tags *tags,
296 busy_tag_iter_fn *fn, void *priv, unsigned int flags)
297{
298 WARN_ON_ONCE(flags & BT_TAG_ITER_RESERVED);
299
300 if (tags->nr_reserved_tags)
301 bt_tags_for_each(tags, &tags->breserved_tags, fn, priv,
302 flags | BT_TAG_ITER_RESERVED);
303 bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, flags);
304}
305
306/**
307 * blk_mq_all_tag_iter - iterate over all requests in a tag map
308 * @tags: Tag map to iterate over.
309 * @fn: Pointer to the function that will be called for each
310 * request. @fn will be called as follows: @fn(rq, @priv,
311 * reserved) where rq is a pointer to a request. 'reserved'
312 * indicates whether or not @rq is a reserved request. Return
313 * true to continue iterating tags, false to stop.
314 * @priv: Will be passed as second argument to @fn.
315 *
316 * Caller has to pass the tag map from which requests are allocated.
317 */
318void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn,
319 void *priv)
320{
321 __blk_mq_all_tag_iter(tags, fn, priv, BT_TAG_ITER_STATIC_RQS);
322}
323
324/**
325 * blk_mq_tagset_busy_iter - iterate over all started requests in a tag set
326 * @tagset: Tag set to iterate over.
327 * @fn: Pointer to the function that will be called for each started
328 * request. @fn will be called as follows: @fn(rq, @priv,
329 * reserved) where rq is a pointer to a request. 'reserved'
330 * indicates whether or not @rq is a reserved request. Return
331 * true to continue iterating tags, false to stop.
332 * @priv: Will be passed as second argument to @fn.
333 */
334void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
335 busy_tag_iter_fn *fn, void *priv)
336{
337 int i;
338
339 for (i = 0; i < tagset->nr_hw_queues; i++) {
340 if (tagset->tags && tagset->tags[i])
341 __blk_mq_all_tag_iter(tagset->tags[i], fn, priv,
342 BT_TAG_ITER_STARTED);
343 }
344}
345EXPORT_SYMBOL(blk_mq_tagset_busy_iter);
346
347static bool blk_mq_tagset_count_completed_rqs(struct request *rq,
348 void *data, bool reserved)
349{
350 unsigned *count = data;
351
352 if (blk_mq_request_completed(rq))
353 (*count)++;
354 return true;
355}
356
357/**
358 * blk_mq_tagset_wait_completed_request - wait until all completed req's
359 * complete funtion is run
360 * @tagset: Tag set to drain completed request
361 *
362 * Note: This function has to be run after all IO queues are shutdown
363 */
364void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset)
365{
366 while (true) {
367 unsigned count = 0;
368
369 blk_mq_tagset_busy_iter(tagset,
370 blk_mq_tagset_count_completed_rqs, &count);
371 if (!count)
372 break;
373 msleep(5);
374 }
375}
376EXPORT_SYMBOL(blk_mq_tagset_wait_completed_request);
377
378/**
379 * blk_mq_queue_tag_busy_iter - iterate over all requests with a driver tag
380 * @q: Request queue to examine.
381 * @fn: Pointer to the function that will be called for each request
382 * on @q. @fn will be called as follows: @fn(hctx, rq, @priv,
383 * reserved) where rq is a pointer to a request and hctx points
384 * to the hardware queue associated with the request. 'reserved'
385 * indicates whether or not @rq is a reserved request.
386 * @priv: Will be passed as third argument to @fn.
387 *
388 * Note: if @q->tag_set is shared with other request queues then @fn will be
389 * called for all requests on all queues that share that tag set and not only
390 * for requests associated with @q.
391 */
392void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn,
393 void *priv)
394{
395 struct blk_mq_hw_ctx *hctx;
396 int i;
397
398 /*
399 * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx
400 * while the queue is frozen. So we can use q_usage_counter to avoid
401 * racing with it. __blk_mq_update_nr_hw_queues() uses
402 * synchronize_rcu() to ensure this function left the critical section
403 * below.
404 */
405 if (!percpu_ref_tryget(&q->q_usage_counter))
406 return;
407
408 queue_for_each_hw_ctx(q, hctx, i) {
409 struct blk_mq_tags *tags = hctx->tags;
410
411 /*
412 * If no software queues are currently mapped to this
413 * hardware queue, there's nothing to check
414 */
415 if (!blk_mq_hw_queue_mapped(hctx))
416 continue;
417
418 if (tags->nr_reserved_tags)
419 bt_for_each(hctx, &tags->breserved_tags, fn, priv, true);
420 bt_for_each(hctx, &tags->bitmap_tags, fn, priv, false);
421 }
422 blk_queue_exit(q);
423}
424
425static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth,
426 bool round_robin, int node)
427{
428 return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL,
429 node);
430}
431
432static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
433 int node, int alloc_policy)
434{
435 unsigned int depth = tags->nr_tags - tags->nr_reserved_tags;
436 bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR;
437
438 if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node))
439 goto free_tags;
440 if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin,
441 node))
442 goto free_bitmap_tags;
443
444 return tags;
445free_bitmap_tags:
446 sbitmap_queue_free(&tags->bitmap_tags);
447free_tags:
448 kfree(tags);
449 return NULL;
450}
451
452struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
453 unsigned int reserved_tags,
454 int node, int alloc_policy)
455{
456 struct blk_mq_tags *tags;
457
458 if (total_tags > BLK_MQ_TAG_MAX) {
459 pr_err("blk-mq: tag depth too large\n");
460 return NULL;
461 }
462
463 tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node);
464 if (!tags)
465 return NULL;
466
467 tags->nr_tags = total_tags;
468 tags->nr_reserved_tags = reserved_tags;
469
470 return blk_mq_init_bitmap_tags(tags, node, alloc_policy);
471}
472
473void blk_mq_free_tags(struct blk_mq_tags *tags)
474{
475 sbitmap_queue_free(&tags->bitmap_tags);
476 sbitmap_queue_free(&tags->breserved_tags);
477 kfree(tags);
478}
479
480int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
481 struct blk_mq_tags **tagsptr, unsigned int tdepth,
482 bool can_grow)
483{
484 struct blk_mq_tags *tags = *tagsptr;
485
486 if (tdepth <= tags->nr_reserved_tags)
487 return -EINVAL;
488
489 /*
490 * If we are allowed to grow beyond the original size, allocate
491 * a new set of tags before freeing the old one.
492 */
493 if (tdepth > tags->nr_tags) {
494 struct blk_mq_tag_set *set = hctx->queue->tag_set;
495 struct blk_mq_tags *new;
496 bool ret;
497
498 if (!can_grow)
499 return -EINVAL;
500
501 /*
502 * We need some sort of upper limit, set it high enough that
503 * no valid use cases should require more.
504 */
505 if (tdepth > 16 * BLKDEV_MAX_RQ)
506 return -EINVAL;
507
508 new = blk_mq_alloc_rq_map(set, hctx->queue_num, tdepth,
509 tags->nr_reserved_tags);
510 if (!new)
511 return -ENOMEM;
512 ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth);
513 if (ret) {
514 blk_mq_free_rq_map(new);
515 return -ENOMEM;
516 }
517
518 blk_mq_free_rqs(set, *tagsptr, hctx->queue_num);
519 blk_mq_free_rq_map(*tagsptr);
520 *tagsptr = new;
521 } else {
522 /*
523 * Don't need (or can't) update reserved tags here, they
524 * remain static and should never need resizing.
525 */
526 sbitmap_queue_resize(&tags->bitmap_tags,
527 tdepth - tags->nr_reserved_tags);
528 }
529
530 return 0;
531}
532
533/**
534 * blk_mq_unique_tag() - return a tag that is unique queue-wide
535 * @rq: request for which to compute a unique tag
536 *
537 * The tag field in struct request is unique per hardware queue but not over
538 * all hardware queues. Hence this function that returns a tag with the
539 * hardware context index in the upper bits and the per hardware queue tag in
540 * the lower bits.
541 *
542 * Note: When called for a request that is queued on a non-multiqueue request
543 * queue, the hardware context index is set to zero.
544 */
545u32 blk_mq_unique_tag(struct request *rq)
546{
547 return (rq->mq_hctx->queue_num << BLK_MQ_UNIQUE_TAG_BITS) |
548 (rq->tag & BLK_MQ_UNIQUE_TAG_MASK);
549}
550EXPORT_SYMBOL(blk_mq_unique_tag);