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Linux/block/blk-mq-tag.c

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Diff markup

Differences between /block/blk-mq-tag.c (Version linux-4.17.19) and /block/blk-mq-tag.c (Version linux-5.3.18)


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

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