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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> | |
5a0e3ad6 | 8 | #include <linux/gfp.h> |
86db1e29 JA |
9 | |
10 | #include "blk.h" | |
11 | ||
12 | /** | |
13 | * blk_queue_ordered - does this queue support ordered writes | |
14 | * @q: the request queue | |
15 | * @ordered: one of QUEUE_ORDERED_* | |
16 | * @prepare_flush_fn: rq setup helper for cache flush ordered writes | |
17 | * | |
18 | * Description: | |
19 | * For journalled file systems, doing ordered writes on a commit | |
20 | * block instead of explicitly doing wait_on_buffer (which is bad | |
21 | * for performance) can be a big win. Block drivers supporting this | |
22 | * feature should call this function and indicate so. | |
23 | * | |
24 | **/ | |
25 | int blk_queue_ordered(struct request_queue *q, unsigned ordered, | |
26 | prepare_flush_fn *prepare_flush_fn) | |
27 | { | |
86db1e29 JA |
28 | if (ordered != QUEUE_ORDERED_NONE && |
29 | ordered != QUEUE_ORDERED_DRAIN && | |
30 | ordered != QUEUE_ORDERED_DRAIN_FLUSH && | |
31 | ordered != QUEUE_ORDERED_DRAIN_FUA && | |
32 | ordered != QUEUE_ORDERED_TAG && | |
33 | ordered != QUEUE_ORDERED_TAG_FLUSH && | |
34 | ordered != QUEUE_ORDERED_TAG_FUA) { | |
35 | printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); | |
36 | return -EINVAL; | |
37 | } | |
38 | ||
39 | q->ordered = ordered; | |
40 | q->next_ordered = ordered; | |
41 | q->prepare_flush_fn = prepare_flush_fn; | |
42 | ||
43 | return 0; | |
44 | } | |
86db1e29 JA |
45 | EXPORT_SYMBOL(blk_queue_ordered); |
46 | ||
47 | /* | |
48 | * Cache flushing for ordered writes handling | |
49 | */ | |
6f6a036e | 50 | unsigned blk_ordered_cur_seq(struct request_queue *q) |
86db1e29 JA |
51 | { |
52 | if (!q->ordseq) | |
53 | return 0; | |
54 | return 1 << ffz(q->ordseq); | |
55 | } | |
56 | ||
57 | unsigned blk_ordered_req_seq(struct request *rq) | |
58 | { | |
59 | struct request_queue *q = rq->q; | |
60 | ||
61 | BUG_ON(q->ordseq == 0); | |
62 | ||
63 | if (rq == &q->pre_flush_rq) | |
64 | return QUEUE_ORDSEQ_PREFLUSH; | |
65 | if (rq == &q->bar_rq) | |
66 | return QUEUE_ORDSEQ_BAR; | |
67 | if (rq == &q->post_flush_rq) | |
68 | return QUEUE_ORDSEQ_POSTFLUSH; | |
69 | ||
70 | /* | |
71 | * !fs requests don't need to follow barrier ordering. Always | |
72 | * put them at the front. This fixes the following deadlock. | |
73 | * | |
74 | * http://thread.gmane.org/gmane.linux.kernel/537473 | |
75 | */ | |
33659ebb | 76 | if (rq->cmd_type != REQ_TYPE_FS) |
86db1e29 JA |
77 | return QUEUE_ORDSEQ_DRAIN; |
78 | ||
79 | if ((rq->cmd_flags & REQ_ORDERED_COLOR) == | |
80 | (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) | |
81 | return QUEUE_ORDSEQ_DRAIN; | |
82 | else | |
83 | return QUEUE_ORDSEQ_DONE; | |
84 | } | |
85 | ||
8f11b3e9 | 86 | bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error) |
86db1e29 JA |
87 | { |
88 | struct request *rq; | |
89 | ||
90 | if (error && !q->orderr) | |
91 | q->orderr = error; | |
92 | ||
93 | BUG_ON(q->ordseq & seq); | |
94 | q->ordseq |= seq; | |
95 | ||
96 | if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) | |
8f11b3e9 | 97 | return false; |
86db1e29 JA |
98 | |
99 | /* | |
100 | * Okay, sequence complete. | |
101 | */ | |
102 | q->ordseq = 0; | |
103 | rq = q->orig_bar_rq; | |
40cbbb78 | 104 | __blk_end_request_all(rq, q->orderr); |
8f11b3e9 | 105 | return true; |
86db1e29 JA |
106 | } |
107 | ||
108 | static void pre_flush_end_io(struct request *rq, int error) | |
109 | { | |
110 | elv_completed_request(rq->q, rq); | |
111 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); | |
112 | } | |
113 | ||
114 | static void bar_end_io(struct request *rq, int error) | |
115 | { | |
116 | elv_completed_request(rq->q, rq); | |
117 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); | |
118 | } | |
119 | ||
120 | static void post_flush_end_io(struct request *rq, int error) | |
121 | { | |
122 | elv_completed_request(rq->q, rq); | |
123 | blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); | |
124 | } | |
125 | ||
126 | static void queue_flush(struct request_queue *q, unsigned which) | |
127 | { | |
128 | struct request *rq; | |
129 | rq_end_io_fn *end_io; | |
130 | ||
313e4299 | 131 | if (which == QUEUE_ORDERED_DO_PREFLUSH) { |
86db1e29 JA |
132 | rq = &q->pre_flush_rq; |
133 | end_io = pre_flush_end_io; | |
134 | } else { | |
135 | rq = &q->post_flush_rq; | |
136 | end_io = post_flush_end_io; | |
137 | } | |
138 | ||
2a4aa30c | 139 | blk_rq_init(q, rq); |
8749534f | 140 | rq->cmd_flags = REQ_HARDBARRIER | REQ_FLUSH; |
86db1e29 JA |
141 | rq->rq_disk = q->bar_rq.rq_disk; |
142 | rq->end_io = end_io; | |
b6a90315 FT |
143 | if (q->prepare_flush_fn) |
144 | q->prepare_flush_fn(q, rq); | |
86db1e29 JA |
145 | |
146 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
147 | } | |
148 | ||
8f11b3e9 | 149 | static inline bool start_ordered(struct request_queue *q, struct request **rqp) |
86db1e29 | 150 | { |
8f11b3e9 TH |
151 | struct request *rq = *rqp; |
152 | unsigned skip = 0; | |
153 | ||
86db1e29 JA |
154 | q->orderr = 0; |
155 | q->ordered = q->next_ordered; | |
156 | q->ordseq |= QUEUE_ORDSEQ_STARTED; | |
157 | ||
58eea927 TH |
158 | /* |
159 | * For an empty barrier, there's no actual BAR request, which | |
160 | * in turn makes POSTFLUSH unnecessary. Mask them off. | |
161 | */ | |
5b93629b | 162 | if (!blk_rq_sectors(rq)) { |
58eea927 TH |
163 | q->ordered &= ~(QUEUE_ORDERED_DO_BAR | |
164 | QUEUE_ORDERED_DO_POSTFLUSH); | |
a185eb4b TH |
165 | /* |
166 | * Empty barrier on a write-through device w/ ordered | |
167 | * tag has no command to issue and without any command | |
168 | * to issue, ordering by tag can't be used. Drain | |
169 | * instead. | |
170 | */ | |
171 | if ((q->ordered & QUEUE_ORDERED_BY_TAG) && | |
172 | !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) { | |
173 | q->ordered &= ~QUEUE_ORDERED_BY_TAG; | |
174 | q->ordered |= QUEUE_ORDERED_BY_DRAIN; | |
175 | } | |
176 | } | |
58eea927 | 177 | |
f671620e | 178 | /* stash away the original request */ |
9934c8c0 | 179 | blk_dequeue_request(rq); |
86db1e29 | 180 | q->orig_bar_rq = rq; |
f671620e | 181 | rq = NULL; |
86db1e29 JA |
182 | |
183 | /* | |
184 | * Queue ordered sequence. As we stack them at the head, we | |
185 | * need to queue in reverse order. Note that we rely on that | |
186 | * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs | |
58eea927 | 187 | * request gets inbetween ordered sequence. |
86db1e29 | 188 | */ |
58eea927 | 189 | if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) { |
313e4299 | 190 | queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH); |
f671620e TH |
191 | rq = &q->post_flush_rq; |
192 | } else | |
8f11b3e9 | 193 | skip |= QUEUE_ORDSEQ_POSTFLUSH; |
86db1e29 | 194 | |
f671620e TH |
195 | if (q->ordered & QUEUE_ORDERED_DO_BAR) { |
196 | rq = &q->bar_rq; | |
197 | ||
198 | /* initialize proxy request and queue it */ | |
199 | blk_rq_init(q, rq); | |
200 | if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) | |
7b6d91da | 201 | rq->cmd_flags |= REQ_WRITE; |
f671620e TH |
202 | if (q->ordered & QUEUE_ORDERED_DO_FUA) |
203 | rq->cmd_flags |= REQ_FUA; | |
204 | init_request_from_bio(rq, q->orig_bar_rq->bio); | |
205 | rq->end_io = bar_end_io; | |
206 | ||
207 | elv_insert(q, rq, ELEVATOR_INSERT_FRONT); | |
208 | } else | |
8f11b3e9 | 209 | skip |= QUEUE_ORDSEQ_BAR; |
86db1e29 | 210 | |
313e4299 TH |
211 | if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) { |
212 | queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH); | |
86db1e29 JA |
213 | rq = &q->pre_flush_rq; |
214 | } else | |
8f11b3e9 | 215 | skip |= QUEUE_ORDSEQ_PREFLUSH; |
86db1e29 | 216 | |
0a7ae2ff | 217 | if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && queue_in_flight(q)) |
86db1e29 | 218 | rq = NULL; |
f671620e | 219 | else |
8f11b3e9 | 220 | skip |= QUEUE_ORDSEQ_DRAIN; |
86db1e29 | 221 | |
8f11b3e9 TH |
222 | *rqp = rq; |
223 | ||
224 | /* | |
225 | * Complete skipped sequences. If whole sequence is complete, | |
226 | * return false to tell elevator that this request is gone. | |
227 | */ | |
228 | return !blk_ordered_complete_seq(q, skip, 0); | |
86db1e29 JA |
229 | } |
230 | ||
8f11b3e9 | 231 | bool blk_do_ordered(struct request_queue *q, struct request **rqp) |
86db1e29 JA |
232 | { |
233 | struct request *rq = *rqp; | |
33659ebb CH |
234 | const int is_barrier = rq->cmd_type == REQ_TYPE_FS && |
235 | (rq->cmd_flags & REQ_HARDBARRIER); | |
86db1e29 JA |
236 | |
237 | if (!q->ordseq) { | |
238 | if (!is_barrier) | |
8f11b3e9 | 239 | return true; |
86db1e29 | 240 | |
8f11b3e9 TH |
241 | if (q->next_ordered != QUEUE_ORDERED_NONE) |
242 | return start_ordered(q, rqp); | |
243 | else { | |
86db1e29 | 244 | /* |
a7384677 TH |
245 | * Queue ordering not supported. Terminate |
246 | * with prejudice. | |
86db1e29 | 247 | */ |
9934c8c0 | 248 | blk_dequeue_request(rq); |
40cbbb78 | 249 | __blk_end_request_all(rq, -EOPNOTSUPP); |
86db1e29 | 250 | *rqp = NULL; |
8f11b3e9 | 251 | return false; |
86db1e29 JA |
252 | } |
253 | } | |
254 | ||
255 | /* | |
256 | * Ordered sequence in progress | |
257 | */ | |
258 | ||
259 | /* Special requests are not subject to ordering rules. */ | |
33659ebb | 260 | if (rq->cmd_type != REQ_TYPE_FS && |
86db1e29 | 261 | rq != &q->pre_flush_rq && rq != &q->post_flush_rq) |
8f11b3e9 | 262 | return true; |
86db1e29 | 263 | |
313e4299 | 264 | if (q->ordered & QUEUE_ORDERED_BY_TAG) { |
86db1e29 JA |
265 | /* Ordered by tag. Blocking the next barrier is enough. */ |
266 | if (is_barrier && rq != &q->bar_rq) | |
267 | *rqp = NULL; | |
268 | } else { | |
269 | /* Ordered by draining. Wait for turn. */ | |
270 | WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); | |
271 | if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) | |
272 | *rqp = NULL; | |
273 | } | |
274 | ||
8f11b3e9 | 275 | return true; |
86db1e29 JA |
276 | } |
277 | ||
278 | static void bio_end_empty_barrier(struct bio *bio, int err) | |
279 | { | |
cc66b451 JA |
280 | if (err) { |
281 | if (err == -EOPNOTSUPP) | |
282 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
86db1e29 | 283 | clear_bit(BIO_UPTODATE, &bio->bi_flags); |
cc66b451 | 284 | } |
f17e232e DM |
285 | if (bio->bi_private) |
286 | complete(bio->bi_private); | |
287 | bio_put(bio); | |
86db1e29 JA |
288 | } |
289 | ||
290 | /** | |
291 | * blkdev_issue_flush - queue a flush | |
292 | * @bdev: blockdev to issue flush for | |
fbd9b09a | 293 | * @gfp_mask: memory allocation flags (for bio_alloc) |
86db1e29 | 294 | * @error_sector: error sector |
fbd9b09a | 295 | * @flags: BLKDEV_IFL_* flags to control behaviour |
86db1e29 JA |
296 | * |
297 | * Description: | |
298 | * Issue a flush for the block device in question. Caller can supply | |
299 | * room for storing the error offset in case of a flush error, if they | |
f17e232e DM |
300 | * wish to. If WAIT flag is not passed then caller may check only what |
301 | * request was pushed in some internal queue for later handling. | |
86db1e29 | 302 | */ |
fbd9b09a DM |
303 | int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, |
304 | sector_t *error_sector, unsigned long flags) | |
86db1e29 JA |
305 | { |
306 | DECLARE_COMPLETION_ONSTACK(wait); | |
307 | struct request_queue *q; | |
308 | struct bio *bio; | |
fbd9b09a | 309 | int ret = 0; |
86db1e29 JA |
310 | |
311 | if (bdev->bd_disk == NULL) | |
312 | return -ENXIO; | |
313 | ||
314 | q = bdev_get_queue(bdev); | |
315 | if (!q) | |
316 | return -ENXIO; | |
317 | ||
fbd9b09a | 318 | bio = bio_alloc(gfp_mask, 0); |
86db1e29 | 319 | bio->bi_end_io = bio_end_empty_barrier; |
86db1e29 | 320 | bio->bi_bdev = bdev; |
f17e232e DM |
321 | if (test_bit(BLKDEV_WAIT, &flags)) |
322 | bio->bi_private = &wait; | |
86db1e29 | 323 | |
f17e232e DM |
324 | bio_get(bio); |
325 | submit_bio(WRITE_BARRIER, bio); | |
326 | if (test_bit(BLKDEV_WAIT, &flags)) { | |
327 | wait_for_completion(&wait); | |
328 | /* | |
329 | * The driver must store the error location in ->bi_sector, if | |
330 | * it supports it. For non-stacked drivers, this should be | |
331 | * copied from blk_rq_pos(rq). | |
332 | */ | |
333 | if (error_sector) | |
334 | *error_sector = bio->bi_sector; | |
335 | } | |
86db1e29 | 336 | |
cc66b451 JA |
337 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
338 | ret = -EOPNOTSUPP; | |
339 | else if (!bio_flagged(bio, BIO_UPTODATE)) | |
86db1e29 JA |
340 | ret = -EIO; |
341 | ||
342 | bio_put(bio); | |
343 | return ret; | |
344 | } | |
86db1e29 | 345 | EXPORT_SYMBOL(blkdev_issue_flush); |