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8324aa91 JA |
1 | /* |
2 | * Functions related to tagged command queuing | |
3 | */ | |
4 | #include <linux/kernel.h> | |
5 | #include <linux/module.h> | |
6 | #include <linux/bio.h> | |
7 | #include <linux/blkdev.h> | |
8 | ||
9 | /** | |
10 | * blk_queue_find_tag - find a request by its tag and queue | |
11 | * @q: The request queue for the device | |
12 | * @tag: The tag of the request | |
13 | * | |
14 | * Notes: | |
15 | * Should be used when a device returns a tag and you want to match | |
16 | * it with a request. | |
17 | * | |
18 | * no locks need be held. | |
19 | **/ | |
20 | struct request *blk_queue_find_tag(struct request_queue *q, int tag) | |
21 | { | |
22 | return blk_map_queue_find_tag(q->queue_tags, tag); | |
23 | } | |
24 | ||
25 | EXPORT_SYMBOL(blk_queue_find_tag); | |
26 | ||
27 | /** | |
28 | * __blk_free_tags - release a given set of tag maintenance info | |
29 | * @bqt: the tag map to free | |
30 | * | |
31 | * Tries to free the specified @bqt@. Returns true if it was | |
32 | * actually freed and false if there are still references using it | |
33 | */ | |
34 | static int __blk_free_tags(struct blk_queue_tag *bqt) | |
35 | { | |
36 | int retval; | |
37 | ||
38 | retval = atomic_dec_and_test(&bqt->refcnt); | |
39 | if (retval) { | |
40 | BUG_ON(bqt->busy); | |
41 | ||
42 | kfree(bqt->tag_index); | |
43 | bqt->tag_index = NULL; | |
44 | ||
45 | kfree(bqt->tag_map); | |
46 | bqt->tag_map = NULL; | |
47 | ||
48 | kfree(bqt); | |
49 | } | |
50 | ||
51 | return retval; | |
52 | } | |
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 | q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); | |
73 | } | |
74 | ||
75 | /** | |
76 | * blk_free_tags - release a given set of tag maintenance info | |
77 | * @bqt: the tag map to free | |
78 | * | |
79 | * For externally managed @bqt@ frees the map. Callers of this | |
80 | * function must guarantee to have released all the queues that | |
81 | * might have been using this tag map. | |
82 | */ | |
83 | void blk_free_tags(struct blk_queue_tag *bqt) | |
84 | { | |
85 | if (unlikely(!__blk_free_tags(bqt))) | |
86 | BUG(); | |
87 | } | |
88 | EXPORT_SYMBOL(blk_free_tags); | |
89 | ||
90 | /** | |
91 | * blk_queue_free_tags - release tag maintenance info | |
92 | * @q: the request queue for the device | |
93 | * | |
94 | * Notes: | |
95 | * This is used to disabled tagged queuing to a device, yet leave | |
96 | * queue in function. | |
97 | **/ | |
98 | void blk_queue_free_tags(struct request_queue *q) | |
99 | { | |
100 | clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
101 | } | |
102 | ||
103 | EXPORT_SYMBOL(blk_queue_free_tags); | |
104 | ||
105 | static int | |
106 | init_tag_map(struct request_queue *q, struct blk_queue_tag *tags, int depth) | |
107 | { | |
108 | struct request **tag_index; | |
109 | unsigned long *tag_map; | |
110 | int nr_ulongs; | |
111 | ||
112 | if (q && depth > q->nr_requests * 2) { | |
113 | depth = q->nr_requests * 2; | |
114 | printk(KERN_ERR "%s: adjusted depth to %d\n", | |
115 | __FUNCTION__, depth); | |
116 | } | |
117 | ||
118 | tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC); | |
119 | if (!tag_index) | |
120 | goto fail; | |
121 | ||
122 | nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; | |
123 | tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); | |
124 | if (!tag_map) | |
125 | goto fail; | |
126 | ||
127 | tags->real_max_depth = depth; | |
128 | tags->max_depth = depth; | |
129 | tags->tag_index = tag_index; | |
130 | tags->tag_map = tag_map; | |
131 | ||
132 | return 0; | |
133 | fail: | |
134 | kfree(tag_index); | |
135 | return -ENOMEM; | |
136 | } | |
137 | ||
138 | static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q, | |
139 | int depth) | |
140 | { | |
141 | struct blk_queue_tag *tags; | |
142 | ||
143 | tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC); | |
144 | if (!tags) | |
145 | goto fail; | |
146 | ||
147 | if (init_tag_map(q, tags, depth)) | |
148 | goto fail; | |
149 | ||
150 | tags->busy = 0; | |
151 | atomic_set(&tags->refcnt, 1); | |
152 | return tags; | |
153 | fail: | |
154 | kfree(tags); | |
155 | return NULL; | |
156 | } | |
157 | ||
158 | /** | |
159 | * blk_init_tags - initialize the tag info for an external tag map | |
160 | * @depth: the maximum queue depth supported | |
161 | * @tags: the tag to use | |
162 | **/ | |
163 | struct blk_queue_tag *blk_init_tags(int depth) | |
164 | { | |
165 | return __blk_queue_init_tags(NULL, depth); | |
166 | } | |
167 | EXPORT_SYMBOL(blk_init_tags); | |
168 | ||
169 | /** | |
170 | * blk_queue_init_tags - initialize the queue tag info | |
171 | * @q: the request queue for the device | |
172 | * @depth: the maximum queue depth supported | |
173 | * @tags: the tag to use | |
174 | **/ | |
175 | int blk_queue_init_tags(struct request_queue *q, int depth, | |
176 | struct blk_queue_tag *tags) | |
177 | { | |
178 | int rc; | |
179 | ||
180 | BUG_ON(tags && q->queue_tags && tags != q->queue_tags); | |
181 | ||
182 | if (!tags && !q->queue_tags) { | |
183 | tags = __blk_queue_init_tags(q, depth); | |
184 | ||
185 | if (!tags) | |
186 | goto fail; | |
187 | } else if (q->queue_tags) { | |
188 | if ((rc = blk_queue_resize_tags(q, depth))) | |
189 | return rc; | |
190 | set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
191 | return 0; | |
192 | } else | |
193 | atomic_inc(&tags->refcnt); | |
194 | ||
195 | /* | |
196 | * assign it, all done | |
197 | */ | |
198 | q->queue_tags = tags; | |
199 | q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); | |
200 | INIT_LIST_HEAD(&q->tag_busy_list); | |
201 | return 0; | |
202 | fail: | |
203 | kfree(tags); | |
204 | return -ENOMEM; | |
205 | } | |
206 | ||
207 | EXPORT_SYMBOL(blk_queue_init_tags); | |
208 | ||
209 | /** | |
210 | * blk_queue_resize_tags - change the queueing depth | |
211 | * @q: the request queue for the device | |
212 | * @new_depth: the new max command queueing depth | |
213 | * | |
214 | * Notes: | |
215 | * Must be called with the queue lock held. | |
216 | **/ | |
217 | int blk_queue_resize_tags(struct request_queue *q, int new_depth) | |
218 | { | |
219 | struct blk_queue_tag *bqt = q->queue_tags; | |
220 | struct request **tag_index; | |
221 | unsigned long *tag_map; | |
222 | int max_depth, nr_ulongs; | |
223 | ||
224 | if (!bqt) | |
225 | return -ENXIO; | |
226 | ||
227 | /* | |
228 | * if we already have large enough real_max_depth. just | |
229 | * adjust max_depth. *NOTE* as requests with tag value | |
230 | * between new_depth and real_max_depth can be in-flight, tag | |
231 | * map can not be shrunk blindly here. | |
232 | */ | |
233 | if (new_depth <= bqt->real_max_depth) { | |
234 | bqt->max_depth = new_depth; | |
235 | return 0; | |
236 | } | |
237 | ||
238 | /* | |
239 | * Currently cannot replace a shared tag map with a new | |
240 | * one, so error out if this is the case | |
241 | */ | |
242 | if (atomic_read(&bqt->refcnt) != 1) | |
243 | return -EBUSY; | |
244 | ||
245 | /* | |
246 | * save the old state info, so we can copy it back | |
247 | */ | |
248 | tag_index = bqt->tag_index; | |
249 | tag_map = bqt->tag_map; | |
250 | max_depth = bqt->real_max_depth; | |
251 | ||
252 | if (init_tag_map(q, bqt, new_depth)) | |
253 | return -ENOMEM; | |
254 | ||
255 | memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); | |
256 | nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG; | |
257 | memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); | |
258 | ||
259 | kfree(tag_index); | |
260 | kfree(tag_map); | |
261 | return 0; | |
262 | } | |
263 | ||
264 | EXPORT_SYMBOL(blk_queue_resize_tags); | |
265 | ||
266 | /** | |
267 | * blk_queue_end_tag - end tag operations for a request | |
268 | * @q: the request queue for the device | |
269 | * @rq: the request that has completed | |
270 | * | |
271 | * Description: | |
272 | * Typically called when end_that_request_first() returns 0, meaning | |
273 | * all transfers have been done for a request. It's important to call | |
274 | * this function before end_that_request_last(), as that will put the | |
275 | * request back on the free list thus corrupting the internal tag list. | |
276 | * | |
277 | * Notes: | |
278 | * queue lock must be held. | |
279 | **/ | |
280 | void blk_queue_end_tag(struct request_queue *q, struct request *rq) | |
281 | { | |
282 | struct blk_queue_tag *bqt = q->queue_tags; | |
283 | int tag = rq->tag; | |
284 | ||
285 | BUG_ON(tag == -1); | |
286 | ||
287 | if (unlikely(tag >= bqt->real_max_depth)) | |
288 | /* | |
289 | * This can happen after tag depth has been reduced. | |
290 | * FIXME: how about a warning or info message here? | |
291 | */ | |
292 | return; | |
293 | ||
294 | list_del_init(&rq->queuelist); | |
295 | rq->cmd_flags &= ~REQ_QUEUED; | |
296 | rq->tag = -1; | |
297 | ||
298 | if (unlikely(bqt->tag_index[tag] == NULL)) | |
299 | printk(KERN_ERR "%s: tag %d is missing\n", | |
300 | __FUNCTION__, tag); | |
301 | ||
302 | bqt->tag_index[tag] = NULL; | |
303 | ||
304 | if (unlikely(!test_bit(tag, bqt->tag_map))) { | |
305 | printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", | |
306 | __FUNCTION__, tag); | |
307 | return; | |
308 | } | |
309 | /* | |
310 | * The tag_map bit acts as a lock for tag_index[bit], so we need | |
311 | * unlock memory barrier semantics. | |
312 | */ | |
313 | clear_bit_unlock(tag, bqt->tag_map); | |
314 | bqt->busy--; | |
315 | } | |
316 | ||
317 | EXPORT_SYMBOL(blk_queue_end_tag); | |
318 | ||
319 | /** | |
320 | * blk_queue_start_tag - find a free tag and assign it | |
321 | * @q: the request queue for the device | |
322 | * @rq: the block request that needs tagging | |
323 | * | |
324 | * Description: | |
325 | * This can either be used as a stand-alone helper, or possibly be | |
326 | * assigned as the queue &prep_rq_fn (in which case &struct request | |
327 | * automagically gets a tag assigned). Note that this function | |
328 | * assumes that any type of request can be queued! if this is not | |
329 | * true for your device, you must check the request type before | |
330 | * calling this function. The request will also be removed from | |
331 | * the request queue, so it's the drivers responsibility to readd | |
332 | * it if it should need to be restarted for some reason. | |
333 | * | |
334 | * Notes: | |
335 | * queue lock must be held. | |
336 | **/ | |
337 | int blk_queue_start_tag(struct request_queue *q, struct request *rq) | |
338 | { | |
339 | struct blk_queue_tag *bqt = q->queue_tags; | |
340 | int tag; | |
341 | ||
342 | if (unlikely((rq->cmd_flags & REQ_QUEUED))) { | |
343 | printk(KERN_ERR | |
344 | "%s: request %p for device [%s] already tagged %d", | |
345 | __FUNCTION__, rq, | |
346 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); | |
347 | BUG(); | |
348 | } | |
349 | ||
350 | /* | |
351 | * Protect against shared tag maps, as we may not have exclusive | |
352 | * access to the tag map. | |
353 | */ | |
354 | do { | |
355 | tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); | |
356 | if (tag >= bqt->max_depth) | |
357 | return 1; | |
358 | ||
359 | } while (test_and_set_bit_lock(tag, bqt->tag_map)); | |
360 | /* | |
361 | * We need lock ordering semantics given by test_and_set_bit_lock. | |
362 | * See blk_queue_end_tag for details. | |
363 | */ | |
364 | ||
365 | rq->cmd_flags |= REQ_QUEUED; | |
366 | rq->tag = tag; | |
367 | bqt->tag_index[tag] = rq; | |
368 | blkdev_dequeue_request(rq); | |
369 | list_add(&rq->queuelist, &q->tag_busy_list); | |
370 | bqt->busy++; | |
371 | return 0; | |
372 | } | |
373 | ||
374 | EXPORT_SYMBOL(blk_queue_start_tag); | |
375 | ||
376 | /** | |
377 | * blk_queue_invalidate_tags - invalidate all pending tags | |
378 | * @q: the request queue for the device | |
379 | * | |
380 | * Description: | |
381 | * Hardware conditions may dictate a need to stop all pending requests. | |
382 | * In this case, we will safely clear the block side of the tag queue and | |
383 | * readd all requests to the request queue in the right order. | |
384 | * | |
385 | * Notes: | |
386 | * queue lock must be held. | |
387 | **/ | |
388 | void blk_queue_invalidate_tags(struct request_queue *q) | |
389 | { | |
390 | struct list_head *tmp, *n; | |
391 | ||
392 | list_for_each_safe(tmp, n, &q->tag_busy_list) | |
393 | blk_requeue_request(q, list_entry_rq(tmp)); | |
394 | } | |
395 | ||
396 | EXPORT_SYMBOL(blk_queue_invalidate_tags); |