blob: c8d087655eff8f94aaa0f65047bc9eea99777e25 [file] [log] [blame]
Jens Axboe86db1e22008-01-29 14:53:40 +01001/*
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 **/
24int blk_queue_ordered(struct request_queue *q, unsigned ordered,
25 prepare_flush_fn *prepare_flush_fn)
26{
Tejun Heo313e4292008-11-28 13:32:02 +090027 if (!prepare_flush_fn && (ordered & (QUEUE_ORDERED_DO_PREFLUSH |
28 QUEUE_ORDERED_DO_POSTFLUSH))) {
Harvey Harrison24c03d42008-05-01 04:35:17 -070029 printk(KERN_ERR "%s: prepare_flush_fn required\n", __func__);
Jens Axboe86db1e22008-01-29 14:53:40 +010030 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}
Jens Axboe86db1e22008-01-29 14:53:40 +010050EXPORT_SYMBOL(blk_queue_ordered);
51
52/*
53 * Cache flushing for ordered writes handling
54 */
Adrian Bunk6f6a0362008-04-29 09:49:06 +020055unsigned blk_ordered_cur_seq(struct request_queue *q)
Jens Axboe86db1e22008-01-29 14:53:40 +010056{
57 if (!q->ordseq)
58 return 0;
59 return 1 << ffz(q->ordseq);
60}
61
62unsigned 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
Tejun Heo8f11b3e2008-11-28 13:32:05 +090091bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)
Jens Axboe86db1e22008-01-29 14:53:40 +010092{
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)
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900102 return false;
Jens Axboe86db1e22008-01-29 14:53:40 +0100103
104 /*
105 * Okay, sequence complete.
106 */
107 q->ordseq = 0;
108 rq = q->orig_bar_rq;
Tejun Heo40cbbb72009-04-23 11:05:19 +0900109 __blk_end_request_all(rq, q->orderr);
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900110 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100111}
112
113static void pre_flush_end_io(struct request *rq, int error)
114{
115 elv_completed_request(rq->q, rq);
116 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
117}
118
119static void bar_end_io(struct request *rq, int error)
120{
121 elv_completed_request(rq->q, rq);
122 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
123}
124
125static void post_flush_end_io(struct request *rq, int error)
126{
127 elv_completed_request(rq->q, rq);
128 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
129}
130
131static void queue_flush(struct request_queue *q, unsigned which)
132{
133 struct request *rq;
134 rq_end_io_fn *end_io;
135
Tejun Heo313e4292008-11-28 13:32:02 +0900136 if (which == QUEUE_ORDERED_DO_PREFLUSH) {
Jens Axboe86db1e22008-01-29 14:53:40 +0100137 rq = &q->pre_flush_rq;
138 end_io = pre_flush_end_io;
139 } else {
140 rq = &q->post_flush_rq;
141 end_io = post_flush_end_io;
142 }
143
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200144 blk_rq_init(q, rq);
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200145 rq->cmd_flags = REQ_HARDBARRIER;
Jens Axboe86db1e22008-01-29 14:53:40 +0100146 rq->rq_disk = q->bar_rq.rq_disk;
147 rq->end_io = end_io;
148 q->prepare_flush_fn(q, rq);
149
150 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
151}
152
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900153static inline bool start_ordered(struct request_queue *q, struct request **rqp)
Jens Axboe86db1e22008-01-29 14:53:40 +0100154{
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900155 struct request *rq = *rqp;
156 unsigned skip = 0;
157
Jens Axboe86db1e22008-01-29 14:53:40 +0100158 q->orderr = 0;
159 q->ordered = q->next_ordered;
160 q->ordseq |= QUEUE_ORDSEQ_STARTED;
161
Tejun Heo58eea922008-11-28 13:32:06 +0900162 /*
163 * For an empty barrier, there's no actual BAR request, which
164 * in turn makes POSTFLUSH unnecessary. Mask them off.
165 */
Tejun Heoa185eb42008-11-28 13:32:07 +0900166 if (!rq->hard_nr_sectors) {
Tejun Heo58eea922008-11-28 13:32:06 +0900167 q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
168 QUEUE_ORDERED_DO_POSTFLUSH);
Tejun Heoa185eb42008-11-28 13:32:07 +0900169 /*
170 * Empty barrier on a write-through device w/ ordered
171 * tag has no command to issue and without any command
172 * to issue, ordering by tag can't be used. Drain
173 * instead.
174 */
175 if ((q->ordered & QUEUE_ORDERED_BY_TAG) &&
176 !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) {
177 q->ordered &= ~QUEUE_ORDERED_BY_TAG;
178 q->ordered |= QUEUE_ORDERED_BY_DRAIN;
179 }
180 }
Tejun Heo58eea922008-11-28 13:32:06 +0900181
Tejun Heof6716202008-11-28 13:32:04 +0900182 /* stash away the original request */
Tejun Heo53a08802008-12-03 12:41:26 +0100183 elv_dequeue_request(q, rq);
Jens Axboe86db1e22008-01-29 14:53:40 +0100184 q->orig_bar_rq = rq;
Tejun Heof6716202008-11-28 13:32:04 +0900185 rq = NULL;
Jens Axboe86db1e22008-01-29 14:53:40 +0100186
187 /*
188 * Queue ordered sequence. As we stack them at the head, we
189 * need to queue in reverse order. Note that we rely on that
190 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
Tejun Heo58eea922008-11-28 13:32:06 +0900191 * request gets inbetween ordered sequence.
Jens Axboe86db1e22008-01-29 14:53:40 +0100192 */
Tejun Heo58eea922008-11-28 13:32:06 +0900193 if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) {
Tejun Heo313e4292008-11-28 13:32:02 +0900194 queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
Tejun Heof6716202008-11-28 13:32:04 +0900195 rq = &q->post_flush_rq;
196 } else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900197 skip |= QUEUE_ORDSEQ_POSTFLUSH;
Jens Axboe86db1e22008-01-29 14:53:40 +0100198
Tejun Heof6716202008-11-28 13:32:04 +0900199 if (q->ordered & QUEUE_ORDERED_DO_BAR) {
200 rq = &q->bar_rq;
201
202 /* initialize proxy request and queue it */
203 blk_rq_init(q, rq);
204 if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
205 rq->cmd_flags |= REQ_RW;
206 if (q->ordered & QUEUE_ORDERED_DO_FUA)
207 rq->cmd_flags |= REQ_FUA;
208 init_request_from_bio(rq, q->orig_bar_rq->bio);
209 rq->end_io = bar_end_io;
210
211 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
212 } else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900213 skip |= QUEUE_ORDSEQ_BAR;
Jens Axboe86db1e22008-01-29 14:53:40 +0100214
Tejun Heo313e4292008-11-28 13:32:02 +0900215 if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) {
216 queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH);
Jens Axboe86db1e22008-01-29 14:53:40 +0100217 rq = &q->pre_flush_rq;
218 } else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900219 skip |= QUEUE_ORDSEQ_PREFLUSH;
Jens Axboe86db1e22008-01-29 14:53:40 +0100220
Tejun Heof6716202008-11-28 13:32:04 +0900221 if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && q->in_flight)
Jens Axboe86db1e22008-01-29 14:53:40 +0100222 rq = NULL;
Tejun Heof6716202008-11-28 13:32:04 +0900223 else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900224 skip |= QUEUE_ORDSEQ_DRAIN;
Jens Axboe86db1e22008-01-29 14:53:40 +0100225
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900226 *rqp = rq;
227
228 /*
229 * Complete skipped sequences. If whole sequence is complete,
230 * return false to tell elevator that this request is gone.
231 */
232 return !blk_ordered_complete_seq(q, skip, 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100233}
234
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900235bool blk_do_ordered(struct request_queue *q, struct request **rqp)
Jens Axboe86db1e22008-01-29 14:53:40 +0100236{
237 struct request *rq = *rqp;
238 const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
239
240 if (!q->ordseq) {
241 if (!is_barrier)
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900242 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100243
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900244 if (q->next_ordered != QUEUE_ORDERED_NONE)
245 return start_ordered(q, rqp);
246 else {
Jens Axboe86db1e22008-01-29 14:53:40 +0100247 /*
Tejun Heoa7384672008-11-28 13:32:03 +0900248 * Queue ordering not supported. Terminate
249 * with prejudice.
Jens Axboe86db1e22008-01-29 14:53:40 +0100250 */
Tejun Heo53a08802008-12-03 12:41:26 +0100251 elv_dequeue_request(q, rq);
Tejun Heo40cbbb72009-04-23 11:05:19 +0900252 __blk_end_request_all(rq, -EOPNOTSUPP);
Jens Axboe86db1e22008-01-29 14:53:40 +0100253 *rqp = NULL;
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900254 return false;
Jens Axboe86db1e22008-01-29 14:53:40 +0100255 }
256 }
257
258 /*
259 * Ordered sequence in progress
260 */
261
262 /* Special requests are not subject to ordering rules. */
263 if (!blk_fs_request(rq) &&
264 rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900265 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100266
Tejun Heo313e4292008-11-28 13:32:02 +0900267 if (q->ordered & QUEUE_ORDERED_BY_TAG) {
Jens Axboe86db1e22008-01-29 14:53:40 +0100268 /* Ordered by tag. Blocking the next barrier is enough. */
269 if (is_barrier && rq != &q->bar_rq)
270 *rqp = NULL;
271 } else {
272 /* Ordered by draining. Wait for turn. */
273 WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
274 if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
275 *rqp = NULL;
276 }
277
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900278 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100279}
280
281static void bio_end_empty_barrier(struct bio *bio, int err)
282{
Jens Axboecc66b452008-03-04 11:47:46 +0100283 if (err) {
284 if (err == -EOPNOTSUPP)
285 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
Jens Axboe86db1e22008-01-29 14:53:40 +0100286 clear_bit(BIO_UPTODATE, &bio->bi_flags);
Jens Axboecc66b452008-03-04 11:47:46 +0100287 }
Jens Axboe86db1e22008-01-29 14:53:40 +0100288
289 complete(bio->bi_private);
290}
291
292/**
293 * blkdev_issue_flush - queue a flush
294 * @bdev: blockdev to issue flush for
295 * @error_sector: error sector
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
Theodore Ts'odbdac9b2009-01-13 15:27:32 +0100300 * wish to.
Jens Axboe86db1e22008-01-29 14:53:40 +0100301 */
302int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
303{
304 DECLARE_COMPLETION_ONSTACK(wait);
305 struct request_queue *q;
306 struct bio *bio;
307 int ret;
308
309 if (bdev->bd_disk == NULL)
310 return -ENXIO;
311
312 q = bdev_get_queue(bdev);
313 if (!q)
314 return -ENXIO;
315
316 bio = bio_alloc(GFP_KERNEL, 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100317 bio->bi_end_io = bio_end_empty_barrier;
318 bio->bi_private = &wait;
319 bio->bi_bdev = bdev;
OGAWA Hirofumi2ebca852008-08-11 17:07:08 +0100320 submit_bio(WRITE_BARRIER, bio);
Jens Axboe86db1e22008-01-29 14:53:40 +0100321
322 wait_for_completion(&wait);
323
324 /*
325 * The driver must store the error location in ->bi_sector, if
326 * it supports it. For non-stacked drivers, this should be copied
327 * from rq->sector.
328 */
329 if (error_sector)
330 *error_sector = bio->bi_sector;
331
332 ret = 0;
Jens Axboecc66b452008-03-04 11:47:46 +0100333 if (bio_flagged(bio, BIO_EOPNOTSUPP))
334 ret = -EOPNOTSUPP;
335 else if (!bio_flagged(bio, BIO_UPTODATE))
Jens Axboe86db1e22008-01-29 14:53:40 +0100336 ret = -EIO;
337
338 bio_put(bio);
339 return ret;
340}
Jens Axboe86db1e22008-01-29 14:53:40 +0100341EXPORT_SYMBOL(blkdev_issue_flush);
David Woodhousefb2dce82008-08-05 18:01:53 +0100342
343static void blkdev_discard_end_io(struct bio *bio, int err)
344{
345 if (err) {
346 if (err == -EOPNOTSUPP)
347 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
348 clear_bit(BIO_UPTODATE, &bio->bi_flags);
349 }
350
351 bio_put(bio);
352}
353
354/**
355 * blkdev_issue_discard - queue a discard
356 * @bdev: blockdev to issue discard for
357 * @sector: start sector
358 * @nr_sects: number of sectors to discard
Hugh Dickins3e6053d2008-09-11 10:57:55 +0200359 * @gfp_mask: memory allocation flags (for bio_alloc)
David Woodhousefb2dce82008-08-05 18:01:53 +0100360 *
361 * Description:
362 * Issue a discard request for the sectors in question. Does not wait.
363 */
Hugh Dickins3e6053d2008-09-11 10:57:55 +0200364int blkdev_issue_discard(struct block_device *bdev,
365 sector_t sector, sector_t nr_sects, gfp_t gfp_mask)
David Woodhousefb2dce82008-08-05 18:01:53 +0100366{
367 struct request_queue *q;
368 struct bio *bio;
369 int ret = 0;
370
371 if (bdev->bd_disk == NULL)
372 return -ENXIO;
373
374 q = bdev_get_queue(bdev);
375 if (!q)
376 return -ENXIO;
377
378 if (!q->prepare_discard_fn)
379 return -EOPNOTSUPP;
380
381 while (nr_sects && !ret) {
Hugh Dickins3e6053d2008-09-11 10:57:55 +0200382 bio = bio_alloc(gfp_mask, 0);
David Woodhousefb2dce82008-08-05 18:01:53 +0100383 if (!bio)
384 return -ENOMEM;
385
386 bio->bi_end_io = blkdev_discard_end_io;
387 bio->bi_bdev = bdev;
388
389 bio->bi_sector = sector;
390
391 if (nr_sects > q->max_hw_sectors) {
392 bio->bi_size = q->max_hw_sectors << 9;
393 nr_sects -= q->max_hw_sectors;
394 sector += q->max_hw_sectors;
395 } else {
396 bio->bi_size = nr_sects << 9;
397 nr_sects = 0;
398 }
399 bio_get(bio);
David Woodhousee17fc0a2008-08-09 16:42:20 +0100400 submit_bio(DISCARD_BARRIER, bio);
David Woodhousefb2dce82008-08-05 18:01:53 +0100401
402 /* Check if it failed immediately */
403 if (bio_flagged(bio, BIO_EOPNOTSUPP))
404 ret = -EOPNOTSUPP;
405 else if (!bio_flagged(bio, BIO_UPTODATE))
406 ret = -EIO;
407 bio_put(bio);
408 }
409 return ret;
410}
411EXPORT_SYMBOL(blkdev_issue_discard);