Commit | Line | Data |
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86db1e29 JA |
1 | /* |
2 | * Functions related to barrier IO handling | |
3 | */ | |
4 | #include <linux/kernel.h> | |
5 | #include <linux/module.h> | |
6 | #include <linux/bio.h> | |
7 | #include <linux/blkdev.h> | |
8 | ||
9 | #include "blk.h" | |
10 | ||
11 | /** | |
12 | * blk_queue_ordered - does this queue support ordered writes | |
13 | * @q: the request queue | |
14 | * @ordered: one of QUEUE_ORDERED_* | |
15 | * @prepare_flush_fn: rq setup helper for cache flush ordered writes | |
16 | * | |
17 | * Description: | |
18 | * For journalled file systems, doing ordered writes on a commit | |
19 | * block instead of explicitly doing wait_on_buffer (which is bad | |
20 | * for performance) can be a big win. Block drivers supporting this | |
21 | * feature should call this function and indicate so. | |
22 | * | |
23 | **/ | |
24 | int blk_queue_ordered(struct request_queue *q, unsigned ordered, | |
25 | prepare_flush_fn *prepare_flush_fn) | |
26 | { | |
313e4299 TH |
27 | if (!prepare_flush_fn && (ordered & (QUEUE_ORDERED_DO_PREFLUSH | |
28 | QUEUE_ORDERED_DO_POSTFLUSH))) { | |
24c03d47 | 29 | printk(KERN_ERR "%s: prepare_flush_fn required\n", __func__); |
86db1e29 JA |
30 | return -EINVAL; |
31 | } | |
32 | ||
33 | if (ordered != QUEUE_ORDERED_NONE && | |
34 | ordered != QUEUE_ORDERED_DRAIN && | |
35 | ordered != QUEUE_ORDERED_DRAIN_FLUSH && | |
36 | ordered != QUEUE_ORDERED_DRAIN_FUA && | |
37 | ordered != QUEUE_ORDERED_TAG && | |
38 | ordered != QUEUE_ORDERED_TAG_FLUSH && | |
39 | ordered != QUEUE_ORDERED_TAG_FUA) { | |
40 | printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); | |
41 | return -EINVAL; | |
42 | } | |
43 | ||
44 | q->ordered = ordered; | |
45 | q->next_ordered = ordered; | |
46 | q->prepare_flush_fn = prepare_flush_fn; | |
47 | ||
48 | return 0; | |
49 | } | |
86db1e29 JA |
50 | EXPORT_SYMBOL(blk_queue_ordered); |
51 | ||
52 | /* | |
53 | * Cache flushing for ordered writes handling | |
54 | */ | |
6f6a036e | 55 | unsigned blk_ordered_cur_seq(struct request_queue *q) |
86db1e29 JA |
56 | { |
57 | if (!q->ordseq) | |
58 | return 0; | |
59 | return 1 << ffz(q->ordseq); | |
60 | } | |
61 | ||
62 | unsigned blk_ordered_req_seq(struct request *rq) | |
63 | { | |
64 | struct request_queue *q = rq->q; | |
65 | ||
66 | BUG_ON(q->ordseq == 0); | |
67 | ||
68 | if (rq == &q->pre_flush_rq) | |
69 | return QUEUE_ORDSEQ_PREFLUSH; | |
70 | if (rq == &q->bar_rq) | |
71 | return QUEUE_ORDSEQ_BAR; | |
72 | if (rq == &q->post_flush_rq) | |
73 | return QUEUE_ORDSEQ_POSTFLUSH; | |
74 | ||
75 | /* | |
76 | * !fs requests don't need to follow barrier ordering. Always | |
77 | * put them at the front. This fixes the following deadlock. | |
78 | * | |
79 | * http://thread.gmane.org/gmane.linux.kernel/537473 | |
80 | */ | |
81 | if (!blk_fs_request(rq)) | |
82 | return QUEUE_ORDSEQ_DRAIN; | |
83 | ||
84 | if ((rq->cmd_flags & REQ_ORDERED_COLOR) == | |
85 | (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) | |
86 | return QUEUE_ORDSEQ_DRAIN; | |
87 | else | |
88 | return QUEUE_ORDSEQ_DONE; | |
89 | } | |
90 | ||
8f11b3e9 | 91 | bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error) |
86db1e29 JA |
92 | { |
93 | struct request *rq; | |
94 | ||
95 | if (error && !q->orderr) | |
96 | q->orderr = error; | |
97 | ||
98 | BUG_ON(q->ordseq & seq); | |
99 | q->ordseq |= seq; | |
100 | ||
101 | if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) | |
8f11b3e9 | 102 | return false; |
86db1e29 JA |
103 | |
104 | /* | |
105 | * Okay, sequence complete. | |
106 | */ | |
107 | q->ordseq = 0; | |
108 | rq = q->orig_bar_rq; | |
109 | ||
110 | if (__blk_end_request(rq, q->orderr, blk_rq_bytes(rq))) | |
111 | BUG(); | |
8f11b3e9 TH |
112 | |
113 | return true; | |
86db1e29 JA |
114 | } |
115 | ||
116 | static void pre_flush_end_io(struct request *rq, int error) | |
117 | { | |
118 | elv_completed_request(rq->q, rq); | |
119 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); | |
120 | } | |
121 | ||
122 | static void bar_end_io(struct request *rq, int error) | |
123 | { | |
124 | elv_completed_request(rq->q, rq); | |
125 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); | |
126 | } | |
127 | ||
128 | static void post_flush_end_io(struct request *rq, int error) | |
129 | { | |
130 | elv_completed_request(rq->q, rq); | |
131 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); | |
132 | } | |
133 | ||
134 | static void queue_flush(struct request_queue *q, unsigned which) | |
135 | { | |
136 | struct request *rq; | |
137 | rq_end_io_fn *end_io; | |
138 | ||
313e4299 | 139 | if (which == QUEUE_ORDERED_DO_PREFLUSH) { |
86db1e29 JA |
140 | rq = &q->pre_flush_rq; |
141 | end_io = pre_flush_end_io; | |
142 | } else { | |
143 | rq = &q->post_flush_rq; | |
144 | end_io = post_flush_end_io; | |
145 | } | |
146 | ||
2a4aa30c | 147 | blk_rq_init(q, rq); |
1afb20f3 | 148 | rq->cmd_flags = REQ_HARDBARRIER; |
86db1e29 JA |
149 | rq->rq_disk = q->bar_rq.rq_disk; |
150 | rq->end_io = end_io; | |
151 | q->prepare_flush_fn(q, rq); | |
152 | ||
153 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
154 | } | |
155 | ||
8f11b3e9 | 156 | static inline bool start_ordered(struct request_queue *q, struct request **rqp) |
86db1e29 | 157 | { |
8f11b3e9 TH |
158 | struct request *rq = *rqp; |
159 | unsigned skip = 0; | |
160 | ||
86db1e29 JA |
161 | q->orderr = 0; |
162 | q->ordered = q->next_ordered; | |
163 | q->ordseq |= QUEUE_ORDSEQ_STARTED; | |
164 | ||
f671620e | 165 | /* stash away the original request */ |
53a08807 | 166 | elv_dequeue_request(q, rq); |
86db1e29 | 167 | q->orig_bar_rq = rq; |
f671620e | 168 | rq = NULL; |
86db1e29 JA |
169 | |
170 | /* | |
171 | * Queue ordered sequence. As we stack them at the head, we | |
172 | * need to queue in reverse order. Note that we rely on that | |
173 | * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs | |
174 | * request gets inbetween ordered sequence. If this request is | |
175 | * an empty barrier, we don't need to do a postflush ever since | |
176 | * there will be no data written between the pre and post flush. | |
177 | * Hence a single flush will suffice. | |
178 | */ | |
f671620e TH |
179 | if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) && |
180 | !blk_empty_barrier(q->orig_bar_rq)) { | |
313e4299 | 181 | queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH); |
f671620e TH |
182 | rq = &q->post_flush_rq; |
183 | } else | |
8f11b3e9 | 184 | skip |= QUEUE_ORDSEQ_POSTFLUSH; |
86db1e29 | 185 | |
f671620e TH |
186 | if (q->ordered & QUEUE_ORDERED_DO_BAR) { |
187 | rq = &q->bar_rq; | |
188 | ||
189 | /* initialize proxy request and queue it */ | |
190 | blk_rq_init(q, rq); | |
191 | if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) | |
192 | rq->cmd_flags |= REQ_RW; | |
193 | if (q->ordered & QUEUE_ORDERED_DO_FUA) | |
194 | rq->cmd_flags |= REQ_FUA; | |
195 | init_request_from_bio(rq, q->orig_bar_rq->bio); | |
196 | rq->end_io = bar_end_io; | |
197 | ||
198 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
199 | } else | |
8f11b3e9 | 200 | skip |= QUEUE_ORDSEQ_BAR; |
86db1e29 | 201 | |
313e4299 TH |
202 | if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) { |
203 | queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH); | |
86db1e29 JA |
204 | rq = &q->pre_flush_rq; |
205 | } else | |
8f11b3e9 | 206 | skip |= QUEUE_ORDSEQ_PREFLUSH; |
86db1e29 | 207 | |
f671620e | 208 | if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && q->in_flight) |
86db1e29 | 209 | rq = NULL; |
f671620e | 210 | else |
8f11b3e9 | 211 | skip |= QUEUE_ORDSEQ_DRAIN; |
86db1e29 | 212 | |
8f11b3e9 TH |
213 | *rqp = rq; |
214 | ||
215 | /* | |
216 | * Complete skipped sequences. If whole sequence is complete, | |
217 | * return false to tell elevator that this request is gone. | |
218 | */ | |
219 | return !blk_ordered_complete_seq(q, skip, 0); | |
86db1e29 JA |
220 | } |
221 | ||
8f11b3e9 | 222 | bool blk_do_ordered(struct request_queue *q, struct request **rqp) |
86db1e29 JA |
223 | { |
224 | struct request *rq = *rqp; | |
225 | const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq); | |
226 | ||
227 | if (!q->ordseq) { | |
228 | if (!is_barrier) | |
8f11b3e9 | 229 | return true; |
86db1e29 | 230 | |
8f11b3e9 TH |
231 | if (q->next_ordered != QUEUE_ORDERED_NONE) |
232 | return start_ordered(q, rqp); | |
233 | else { | |
86db1e29 | 234 | /* |
a7384677 TH |
235 | * Queue ordering not supported. Terminate |
236 | * with prejudice. | |
86db1e29 | 237 | */ |
53a08807 | 238 | elv_dequeue_request(q, rq); |
86db1e29 JA |
239 | if (__blk_end_request(rq, -EOPNOTSUPP, |
240 | blk_rq_bytes(rq))) | |
241 | BUG(); | |
242 | *rqp = NULL; | |
8f11b3e9 | 243 | return false; |
86db1e29 JA |
244 | } |
245 | } | |
246 | ||
247 | /* | |
248 | * Ordered sequence in progress | |
249 | */ | |
250 | ||
251 | /* Special requests are not subject to ordering rules. */ | |
252 | if (!blk_fs_request(rq) && | |
253 | rq != &q->pre_flush_rq && rq != &q->post_flush_rq) | |
8f11b3e9 | 254 | return true; |
86db1e29 | 255 | |
313e4299 | 256 | if (q->ordered & QUEUE_ORDERED_BY_TAG) { |
86db1e29 JA |
257 | /* Ordered by tag. Blocking the next barrier is enough. */ |
258 | if (is_barrier && rq != &q->bar_rq) | |
259 | *rqp = NULL; | |
260 | } else { | |
261 | /* Ordered by draining. Wait for turn. */ | |
262 | WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); | |
263 | if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) | |
264 | *rqp = NULL; | |
265 | } | |
266 | ||
8f11b3e9 | 267 | return true; |
86db1e29 JA |
268 | } |
269 | ||
270 | static void bio_end_empty_barrier(struct bio *bio, int err) | |
271 | { | |
cc66b451 JA |
272 | if (err) { |
273 | if (err == -EOPNOTSUPP) | |
274 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
86db1e29 | 275 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
cc66b451 | 276 | } |
86db1e29 JA |
277 | |
278 | complete(bio->bi_private); | |
279 | } | |
280 | ||
281 | /** | |
282 | * blkdev_issue_flush - queue a flush | |
283 | * @bdev: blockdev to issue flush for | |
284 | * @error_sector: error sector | |
285 | * | |
286 | * Description: | |
287 | * Issue a flush for the block device in question. Caller can supply | |
288 | * room for storing the error offset in case of a flush error, if they | |
289 | * wish to. Caller must run wait_for_completion() on its own. | |
290 | */ | |
291 | int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) | |
292 | { | |
293 | DECLARE_COMPLETION_ONSTACK(wait); | |
294 | struct request_queue *q; | |
295 | struct bio *bio; | |
296 | int ret; | |
297 | ||
298 | if (bdev->bd_disk == NULL) | |
299 | return -ENXIO; | |
300 | ||
301 | q = bdev_get_queue(bdev); | |
302 | if (!q) | |
303 | return -ENXIO; | |
304 | ||
305 | bio = bio_alloc(GFP_KERNEL, 0); | |
306 | if (!bio) | |
307 | return -ENOMEM; | |
308 | ||
309 | bio->bi_end_io = bio_end_empty_barrier; | |
310 | bio->bi_private = &wait; | |
311 | bio->bi_bdev = bdev; | |
2ebca85a | 312 | submit_bio(WRITE_BARRIER, bio); |
86db1e29 JA |
313 | |
314 | wait_for_completion(&wait); | |
315 | ||
316 | /* | |
317 | * The driver must store the error location in ->bi_sector, if | |
318 | * it supports it. For non-stacked drivers, this should be copied | |
319 | * from rq->sector. | |
320 | */ | |
321 | if (error_sector) | |
322 | *error_sector = bio->bi_sector; | |
323 | ||
324 | ret = 0; | |
cc66b451 JA |
325 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
326 | ret = -EOPNOTSUPP; | |
327 | else if (!bio_flagged(bio, BIO_UPTODATE)) | |
86db1e29 JA |
328 | ret = -EIO; |
329 | ||
330 | bio_put(bio); | |
331 | return ret; | |
332 | } | |
86db1e29 | 333 | EXPORT_SYMBOL(blkdev_issue_flush); |
fb2dce86 DW |
334 | |
335 | static void blkdev_discard_end_io(struct bio *bio, int err) | |
336 | { | |
337 | if (err) { | |
338 | if (err == -EOPNOTSUPP) | |
339 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
340 | clear_bit(BIO_UPTODATE, &bio->bi_flags); | |
341 | } | |
342 | ||
343 | bio_put(bio); | |
344 | } | |
345 | ||
346 | /** | |
347 | * blkdev_issue_discard - queue a discard | |
348 | * @bdev: blockdev to issue discard for | |
349 | * @sector: start sector | |
350 | * @nr_sects: number of sectors to discard | |
3e6053d7 | 351 | * @gfp_mask: memory allocation flags (for bio_alloc) |
fb2dce86 DW |
352 | * |
353 | * Description: | |
354 | * Issue a discard request for the sectors in question. Does not wait. | |
355 | */ | |
3e6053d7 HD |
356 | int blkdev_issue_discard(struct block_device *bdev, |
357 | sector_t sector, sector_t nr_sects, gfp_t gfp_mask) | |
fb2dce86 DW |
358 | { |
359 | struct request_queue *q; | |
360 | struct bio *bio; | |
361 | int ret = 0; | |
362 | ||
363 | if (bdev->bd_disk == NULL) | |
364 | return -ENXIO; | |
365 | ||
366 | q = bdev_get_queue(bdev); | |
367 | if (!q) | |
368 | return -ENXIO; | |
369 | ||
370 | if (!q->prepare_discard_fn) | |
371 | return -EOPNOTSUPP; | |
372 | ||
373 | while (nr_sects && !ret) { | |
3e6053d7 | 374 | bio = bio_alloc(gfp_mask, 0); |
fb2dce86 DW |
375 | if (!bio) |
376 | return -ENOMEM; | |
377 | ||
378 | bio->bi_end_io = blkdev_discard_end_io; | |
379 | bio->bi_bdev = bdev; | |
380 | ||
381 | bio->bi_sector = sector; | |
382 | ||
383 | if (nr_sects > q->max_hw_sectors) { | |
384 | bio->bi_size = q->max_hw_sectors << 9; | |
385 | nr_sects -= q->max_hw_sectors; | |
386 | sector += q->max_hw_sectors; | |
387 | } else { | |
388 | bio->bi_size = nr_sects << 9; | |
389 | nr_sects = 0; | |
390 | } | |
391 | bio_get(bio); | |
e17fc0a1 | 392 | submit_bio(DISCARD_BARRIER, bio); |
fb2dce86 DW |
393 | |
394 | /* Check if it failed immediately */ | |
395 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
396 | ret = -EOPNOTSUPP; | |
397 | else if (!bio_flagged(bio, BIO_UPTODATE)) | |
398 | ret = -EIO; | |
399 | bio_put(bio); | |
400 | } | |
401 | return ret; | |
402 | } | |
403 | EXPORT_SYMBOL(blkdev_issue_discard); |