~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/block/blk-tag.c

Version: ~ [ linux-5.12 ] ~ [ linux-5.11.16 ] ~ [ linux-5.10.32 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.114 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.188 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.231 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.267 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.267 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Functions related to tagged command queuing
  4  */
  5 #include <linux/kernel.h>
  6 #include <linux/module.h>
  7 #include <linux/bio.h>
  8 #include <linux/blkdev.h>
  9 #include <linux/slab.h>
 10 
 11 #include "blk.h"
 12 
 13 /**
 14  * blk_queue_find_tag - find a request by its tag and queue
 15  * @q:   The request queue for the device
 16  * @tag: The tag of the request
 17  *
 18  * Notes:
 19  *    Should be used when a device returns a tag and you want to match
 20  *    it with a request.
 21  *
 22  *    no locks need be held.
 23  **/
 24 struct request *blk_queue_find_tag(struct request_queue *q, int tag)
 25 {
 26         return blk_map_queue_find_tag(q->queue_tags, tag);
 27 }
 28 EXPORT_SYMBOL(blk_queue_find_tag);
 29 
 30 /**
 31  * blk_free_tags - release a given set of tag maintenance info
 32  * @bqt:        the tag map to free
 33  *
 34  * Drop the reference count on @bqt and frees it when the last reference
 35  * is dropped.
 36  */
 37 void blk_free_tags(struct blk_queue_tag *bqt)
 38 {
 39         if (atomic_dec_and_test(&bqt->refcnt)) {
 40                 BUG_ON(find_first_bit(bqt->tag_map, bqt->max_depth) <
 41                                                         bqt->max_depth);
 42 
 43                 kfree(bqt->tag_index);
 44                 bqt->tag_index = NULL;
 45 
 46                 kfree(bqt->tag_map);
 47                 bqt->tag_map = NULL;
 48 
 49                 kfree(bqt);
 50         }
 51 }
 52 EXPORT_SYMBOL(blk_free_tags);
 53 
 54 /**
 55  * __blk_queue_free_tags - release tag maintenance info
 56  * @q:  the request queue for the device
 57  *
 58  *  Notes:
 59  *    blk_cleanup_queue() will take care of calling this function, if tagging
 60  *    has been used. So there's no need to call this directly.
 61  **/
 62 void __blk_queue_free_tags(struct request_queue *q)
 63 {
 64         struct blk_queue_tag *bqt = q->queue_tags;
 65 
 66         if (!bqt)
 67                 return;
 68 
 69         blk_free_tags(bqt);
 70 
 71         q->queue_tags = NULL;
 72         queue_flag_clear_unlocked(QUEUE_FLAG_QUEUED, q);
 73 }
 74 
 75 /**
 76  * blk_queue_free_tags - release tag maintenance info
 77  * @q:  the request queue for the device
 78  *
 79  *  Notes:
 80  *      This is used to disable tagged queuing to a device, yet leave
 81  *      queue in function.
 82  **/
 83 void blk_queue_free_tags(struct request_queue *q)
 84 {
 85         queue_flag_clear_unlocked(QUEUE_FLAG_QUEUED, q);
 86 }
 87 EXPORT_SYMBOL(blk_queue_free_tags);
 88 
 89 static int
 90 init_tag_map(struct request_queue *q, struct blk_queue_tag *tags, int depth)
 91 {
 92         struct request **tag_index;
 93         unsigned long *tag_map;
 94         int nr_ulongs;
 95 
 96         if (q && depth > q->nr_requests * 2) {
 97                 depth = q->nr_requests * 2;
 98                 printk(KERN_ERR "%s: adjusted depth to %d\n",
 99                        __func__, depth);
100         }
101 
102         tag_index = kcalloc(depth, sizeof(struct request *), GFP_ATOMIC);
103         if (!tag_index)
104                 goto fail;
105 
106         nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
107         tag_map = kcalloc(nr_ulongs, sizeof(unsigned long), GFP_ATOMIC);
108         if (!tag_map)
109                 goto fail;
110 
111         tags->real_max_depth = depth;
112         tags->max_depth = depth;
113         tags->tag_index = tag_index;
114         tags->tag_map = tag_map;
115 
116         return 0;
117 fail:
118         kfree(tag_index);
119         return -ENOMEM;
120 }
121 
122 static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
123                                                 int depth, int alloc_policy)
124 {
125         struct blk_queue_tag *tags;
126 
127         tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
128         if (!tags)
129                 goto fail;
130 
131         if (init_tag_map(q, tags, depth))
132                 goto fail;
133 
134         atomic_set(&tags->refcnt, 1);
135         tags->alloc_policy = alloc_policy;
136         tags->next_tag = 0;
137         return tags;
138 fail:
139         kfree(tags);
140         return NULL;
141 }
142 
143 /**
144  * blk_init_tags - initialize the tag info for an external tag map
145  * @depth:      the maximum queue depth supported
146  * @alloc_policy: tag allocation policy
147  **/
148 struct blk_queue_tag *blk_init_tags(int depth, int alloc_policy)
149 {
150         return __blk_queue_init_tags(NULL, depth, alloc_policy);
151 }
152 EXPORT_SYMBOL(blk_init_tags);
153 
154 /**
155  * blk_queue_init_tags - initialize the queue tag info
156  * @q:  the request queue for the device
157  * @depth:  the maximum queue depth supported
158  * @tags: the tag to use
159  * @alloc_policy: tag allocation policy
160  *
161  * Queue lock must be held here if the function is called to resize an
162  * existing map.
163  **/
164 int blk_queue_init_tags(struct request_queue *q, int depth,
165                         struct blk_queue_tag *tags, int alloc_policy)
166 {
167         int rc;
168 
169         BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
170 
171         if (!tags && !q->queue_tags) {
172                 tags = __blk_queue_init_tags(q, depth, alloc_policy);
173 
174                 if (!tags)
175                         return -ENOMEM;
176 
177         } else if (q->queue_tags) {
178                 rc = blk_queue_resize_tags(q, depth);
179                 if (rc)
180                         return rc;
181                 queue_flag_set(QUEUE_FLAG_QUEUED, q);
182                 return 0;
183         } else
184                 atomic_inc(&tags->refcnt);
185 
186         /*
187          * assign it, all done
188          */
189         q->queue_tags = tags;
190         queue_flag_set_unlocked(QUEUE_FLAG_QUEUED, q);
191         return 0;
192 }
193 EXPORT_SYMBOL(blk_queue_init_tags);
194 
195 /**
196  * blk_queue_resize_tags - change the queueing depth
197  * @q:  the request queue for the device
198  * @new_depth: the new max command queueing depth
199  *
200  *  Notes:
201  *    Must be called with the queue lock held.
202  **/
203 int blk_queue_resize_tags(struct request_queue *q, int new_depth)
204 {
205         struct blk_queue_tag *bqt = q->queue_tags;
206         struct request **tag_index;
207         unsigned long *tag_map;
208         int max_depth, nr_ulongs;
209 
210         if (!bqt)
211                 return -ENXIO;
212 
213         /*
214          * if we already have large enough real_max_depth.  just
215          * adjust max_depth.  *NOTE* as requests with tag value
216          * between new_depth and real_max_depth can be in-flight, tag
217          * map can not be shrunk blindly here.
218          */
219         if (new_depth <= bqt->real_max_depth) {
220                 bqt->max_depth = new_depth;
221                 return 0;
222         }
223 
224         /*
225          * Currently cannot replace a shared tag map with a new
226          * one, so error out if this is the case
227          */
228         if (atomic_read(&bqt->refcnt) != 1)
229                 return -EBUSY;
230 
231         /*
232          * save the old state info, so we can copy it back
233          */
234         tag_index = bqt->tag_index;
235         tag_map = bqt->tag_map;
236         max_depth = bqt->real_max_depth;
237 
238         if (init_tag_map(q, bqt, new_depth))
239                 return -ENOMEM;
240 
241         memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
242         nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG;
243         memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long));
244 
245         kfree(tag_index);
246         kfree(tag_map);
247         return 0;
248 }
249 EXPORT_SYMBOL(blk_queue_resize_tags);
250 
251 /**
252  * blk_queue_end_tag - end tag operations for a request
253  * @q:  the request queue for the device
254  * @rq: the request that has completed
255  *
256  *  Description:
257  *    Typically called when end_that_request_first() returns %0, meaning
258  *    all transfers have been done for a request. It's important to call
259  *    this function before end_that_request_last(), as that will put the
260  *    request back on the free list thus corrupting the internal tag list.
261  **/
262 void blk_queue_end_tag(struct request_queue *q, struct request *rq)
263 {
264         struct blk_queue_tag *bqt = q->queue_tags;
265         unsigned tag = rq->tag; /* negative tags invalid */
266 
267         lockdep_assert_held(q->queue_lock);
268 
269         BUG_ON(tag >= bqt->real_max_depth);
270 
271         list_del_init(&rq->queuelist);
272         rq->rq_flags &= ~RQF_QUEUED;
273         rq->tag = -1;
274         rq->internal_tag = -1;
275 
276         if (unlikely(bqt->tag_index[tag] == NULL))
277                 printk(KERN_ERR "%s: tag %d is missing\n",
278                        __func__, tag);
279 
280         bqt->tag_index[tag] = NULL;
281 
282         if (unlikely(!test_bit(tag, bqt->tag_map))) {
283                 printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
284                        __func__, tag);
285                 return;
286         }
287         /*
288          * The tag_map bit acts as a lock for tag_index[bit], so we need
289          * unlock memory barrier semantics.
290          */
291         clear_bit_unlock(tag, bqt->tag_map);
292 }
293 
294 /**
295  * blk_queue_start_tag - find a free tag and assign it
296  * @q:  the request queue for the device
297  * @rq:  the block request that needs tagging
298  *
299  *  Description:
300  *    This can either be used as a stand-alone helper, or possibly be
301  *    assigned as the queue &prep_rq_fn (in which case &struct request
302  *    automagically gets a tag assigned). Note that this function
303  *    assumes that any type of request can be queued! if this is not
304  *    true for your device, you must check the request type before
305  *    calling this function.  The request will also be removed from
306  *    the request queue, so it's the drivers responsibility to readd
307  *    it if it should need to be restarted for some reason.
308  **/
309 int blk_queue_start_tag(struct request_queue *q, struct request *rq)
310 {
311         struct blk_queue_tag *bqt = q->queue_tags;
312         unsigned max_depth;
313         int tag;
314 
315         lockdep_assert_held(q->queue_lock);
316 
317         if (unlikely((rq->rq_flags & RQF_QUEUED))) {
318                 printk(KERN_ERR
319                        "%s: request %p for device [%s] already tagged %d",
320                        __func__, rq,
321                        rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
322                 BUG();
323         }
324 
325         /*
326          * Protect against shared tag maps, as we may not have exclusive
327          * access to the tag map.
328          *
329          * We reserve a few tags just for sync IO, since we don't want
330          * to starve sync IO on behalf of flooding async IO.
331          */
332         max_depth = bqt->max_depth;
333         if (!rq_is_sync(rq) && max_depth > 1) {
334                 switch (max_depth) {
335                 case 2:
336                         max_depth = 1;
337                         break;
338                 case 3:
339                         max_depth = 2;
340                         break;
341                 default:
342                         max_depth -= 2;
343                 }
344                 if (q->in_flight[BLK_RW_ASYNC] > max_depth)
345                         return 1;
346         }
347 
348         do {
349                 if (bqt->alloc_policy == BLK_TAG_ALLOC_FIFO) {
350                         tag = find_first_zero_bit(bqt->tag_map, max_depth);
351                         if (tag >= max_depth)
352                                 return 1;
353                 } else {
354                         int start = bqt->next_tag;
355                         int size = min_t(int, bqt->max_depth, max_depth + start);
356                         tag = find_next_zero_bit(bqt->tag_map, size, start);
357                         if (tag >= size && start + size > bqt->max_depth) {
358                                 size = start + size - bqt->max_depth;
359                                 tag = find_first_zero_bit(bqt->tag_map, size);
360                         }
361                         if (tag >= size)
362                                 return 1;
363                 }
364 
365         } while (test_and_set_bit_lock(tag, bqt->tag_map));
366         /*
367          * We need lock ordering semantics given by test_and_set_bit_lock.
368          * See blk_queue_end_tag for details.
369          */
370 
371         bqt->next_tag = (tag + 1) % bqt->max_depth;
372         rq->rq_flags |= RQF_QUEUED;
373         rq->tag = tag;
374         bqt->tag_index[tag] = rq;
375         blk_start_request(rq);
376         return 0;
377 }
378 EXPORT_SYMBOL(blk_queue_start_tag);
379 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp