blob: 6d88544b677fe8865922795ccac817d1d301954f [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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +09008#include <linux/gfp.h>
Jens Axboe86db1e22008-01-29 14:53:40 +01009
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 **/
25int blk_queue_ordered(struct request_queue *q, unsigned ordered,
26 prepare_flush_fn *prepare_flush_fn)
27{
Tejun Heo313e4292008-11-28 13:32:02 +090028 if (!prepare_flush_fn && (ordered & (QUEUE_ORDERED_DO_PREFLUSH |
29 QUEUE_ORDERED_DO_POSTFLUSH))) {
Harvey Harrison24c03d42008-05-01 04:35:17 -070030 printk(KERN_ERR "%s: prepare_flush_fn required\n", __func__);
Jens Axboe86db1e22008-01-29 14:53:40 +010031 return -EINVAL;
32 }
33
34 if (ordered != QUEUE_ORDERED_NONE &&
35 ordered != QUEUE_ORDERED_DRAIN &&
36 ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
37 ordered != QUEUE_ORDERED_DRAIN_FUA &&
38 ordered != QUEUE_ORDERED_TAG &&
39 ordered != QUEUE_ORDERED_TAG_FLUSH &&
40 ordered != QUEUE_ORDERED_TAG_FUA) {
41 printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
42 return -EINVAL;
43 }
44
45 q->ordered = ordered;
46 q->next_ordered = ordered;
47 q->prepare_flush_fn = prepare_flush_fn;
48
49 return 0;
50}
Jens Axboe86db1e22008-01-29 14:53:40 +010051EXPORT_SYMBOL(blk_queue_ordered);
52
53/*
54 * Cache flushing for ordered writes handling
55 */
Adrian Bunk6f6a0362008-04-29 09:49:06 +020056unsigned blk_ordered_cur_seq(struct request_queue *q)
Jens Axboe86db1e22008-01-29 14:53:40 +010057{
58 if (!q->ordseq)
59 return 0;
60 return 1 << ffz(q->ordseq);
61}
62
63unsigned blk_ordered_req_seq(struct request *rq)
64{
65 struct request_queue *q = rq->q;
66
67 BUG_ON(q->ordseq == 0);
68
69 if (rq == &q->pre_flush_rq)
70 return QUEUE_ORDSEQ_PREFLUSH;
71 if (rq == &q->bar_rq)
72 return QUEUE_ORDSEQ_BAR;
73 if (rq == &q->post_flush_rq)
74 return QUEUE_ORDSEQ_POSTFLUSH;
75
76 /*
77 * !fs requests don't need to follow barrier ordering. Always
78 * put them at the front. This fixes the following deadlock.
79 *
80 * http://thread.gmane.org/gmane.linux.kernel/537473
81 */
82 if (!blk_fs_request(rq))
83 return QUEUE_ORDSEQ_DRAIN;
84
85 if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
86 (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))
87 return QUEUE_ORDSEQ_DRAIN;
88 else
89 return QUEUE_ORDSEQ_DONE;
90}
91
Tejun Heo8f11b3e2008-11-28 13:32:05 +090092bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)
Jens Axboe86db1e22008-01-29 14:53:40 +010093{
94 struct request *rq;
95
96 if (error && !q->orderr)
97 q->orderr = error;
98
99 BUG_ON(q->ordseq & seq);
100 q->ordseq |= seq;
101
102 if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900103 return false;
Jens Axboe86db1e22008-01-29 14:53:40 +0100104
105 /*
106 * Okay, sequence complete.
107 */
108 q->ordseq = 0;
109 rq = q->orig_bar_rq;
Tejun Heo40cbbb72009-04-23 11:05:19 +0900110 __blk_end_request_all(rq, q->orderr);
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900111 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100112}
113
114static void pre_flush_end_io(struct request *rq, int error)
115{
116 elv_completed_request(rq->q, rq);
117 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
118}
119
120static void bar_end_io(struct request *rq, int error)
121{
122 elv_completed_request(rq->q, rq);
123 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
124}
125
126static void post_flush_end_io(struct request *rq, int error)
127{
128 elv_completed_request(rq->q, rq);
129 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
130}
131
132static void queue_flush(struct request_queue *q, unsigned which)
133{
134 struct request *rq;
135 rq_end_io_fn *end_io;
136
Tejun Heo313e4292008-11-28 13:32:02 +0900137 if (which == QUEUE_ORDERED_DO_PREFLUSH) {
Jens Axboe86db1e22008-01-29 14:53:40 +0100138 rq = &q->pre_flush_rq;
139 end_io = pre_flush_end_io;
140 } else {
141 rq = &q->post_flush_rq;
142 end_io = post_flush_end_io;
143 }
144
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200145 blk_rq_init(q, rq);
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200146 rq->cmd_flags = REQ_HARDBARRIER;
Jens Axboe86db1e22008-01-29 14:53:40 +0100147 rq->rq_disk = q->bar_rq.rq_disk;
148 rq->end_io = end_io;
149 q->prepare_flush_fn(q, rq);
150
151 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
152}
153
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900154static inline bool start_ordered(struct request_queue *q, struct request **rqp)
Jens Axboe86db1e22008-01-29 14:53:40 +0100155{
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900156 struct request *rq = *rqp;
157 unsigned skip = 0;
158
Jens Axboe86db1e22008-01-29 14:53:40 +0100159 q->orderr = 0;
160 q->ordered = q->next_ordered;
161 q->ordseq |= QUEUE_ORDSEQ_STARTED;
162
Tejun Heo58eea922008-11-28 13:32:06 +0900163 /*
164 * For an empty barrier, there's no actual BAR request, which
165 * in turn makes POSTFLUSH unnecessary. Mask them off.
166 */
Tejun Heo5b936292009-05-07 22:24:38 +0900167 if (!blk_rq_sectors(rq)) {
Tejun Heo58eea922008-11-28 13:32:06 +0900168 q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
169 QUEUE_ORDERED_DO_POSTFLUSH);
Tejun Heoa185eb42008-11-28 13:32:07 +0900170 /*
171 * Empty barrier on a write-through device w/ ordered
172 * tag has no command to issue and without any command
173 * to issue, ordering by tag can't be used. Drain
174 * instead.
175 */
176 if ((q->ordered & QUEUE_ORDERED_BY_TAG) &&
177 !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) {
178 q->ordered &= ~QUEUE_ORDERED_BY_TAG;
179 q->ordered |= QUEUE_ORDERED_BY_DRAIN;
180 }
181 }
Tejun Heo58eea922008-11-28 13:32:06 +0900182
Tejun Heof6716202008-11-28 13:32:04 +0900183 /* stash away the original request */
Tejun Heo9934c8c2009-05-08 11:54:16 +0900184 blk_dequeue_request(rq);
Jens Axboe86db1e22008-01-29 14:53:40 +0100185 q->orig_bar_rq = rq;
Tejun Heof6716202008-11-28 13:32:04 +0900186 rq = NULL;
Jens Axboe86db1e22008-01-29 14:53:40 +0100187
188 /*
189 * Queue ordered sequence. As we stack them at the head, we
190 * need to queue in reverse order. Note that we rely on that
191 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
Tejun Heo58eea922008-11-28 13:32:06 +0900192 * request gets inbetween ordered sequence.
Jens Axboe86db1e22008-01-29 14:53:40 +0100193 */
Tejun Heo58eea922008-11-28 13:32:06 +0900194 if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) {
Tejun Heo313e4292008-11-28 13:32:02 +0900195 queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
Tejun Heof6716202008-11-28 13:32:04 +0900196 rq = &q->post_flush_rq;
197 } else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900198 skip |= QUEUE_ORDSEQ_POSTFLUSH;
Jens Axboe86db1e22008-01-29 14:53:40 +0100199
Tejun Heof6716202008-11-28 13:32:04 +0900200 if (q->ordered & QUEUE_ORDERED_DO_BAR) {
201 rq = &q->bar_rq;
202
203 /* initialize proxy request and queue it */
204 blk_rq_init(q, rq);
205 if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
206 rq->cmd_flags |= REQ_RW;
207 if (q->ordered & QUEUE_ORDERED_DO_FUA)
208 rq->cmd_flags |= REQ_FUA;
209 init_request_from_bio(rq, q->orig_bar_rq->bio);
210 rq->end_io = bar_end_io;
211
212 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
213 } else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900214 skip |= QUEUE_ORDSEQ_BAR;
Jens Axboe86db1e22008-01-29 14:53:40 +0100215
Tejun Heo313e4292008-11-28 13:32:02 +0900216 if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) {
217 queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH);
Jens Axboe86db1e22008-01-29 14:53:40 +0100218 rq = &q->pre_flush_rq;
219 } else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900220 skip |= QUEUE_ORDSEQ_PREFLUSH;
Jens Axboe86db1e22008-01-29 14:53:40 +0100221
Jens Axboe0a7ae2f2009-05-20 08:54:31 +0200222 if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && queue_in_flight(q))
Jens Axboe86db1e22008-01-29 14:53:40 +0100223 rq = NULL;
Tejun Heof6716202008-11-28 13:32:04 +0900224 else
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900225 skip |= QUEUE_ORDSEQ_DRAIN;
Jens Axboe86db1e22008-01-29 14:53:40 +0100226
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900227 *rqp = rq;
228
229 /*
230 * Complete skipped sequences. If whole sequence is complete,
231 * return false to tell elevator that this request is gone.
232 */
233 return !blk_ordered_complete_seq(q, skip, 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100234}
235
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900236bool blk_do_ordered(struct request_queue *q, struct request **rqp)
Jens Axboe86db1e22008-01-29 14:53:40 +0100237{
238 struct request *rq = *rqp;
239 const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
240
241 if (!q->ordseq) {
242 if (!is_barrier)
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900243 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100244
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900245 if (q->next_ordered != QUEUE_ORDERED_NONE)
246 return start_ordered(q, rqp);
247 else {
Jens Axboe86db1e22008-01-29 14:53:40 +0100248 /*
Tejun Heoa7384672008-11-28 13:32:03 +0900249 * Queue ordering not supported. Terminate
250 * with prejudice.
Jens Axboe86db1e22008-01-29 14:53:40 +0100251 */
Tejun Heo9934c8c2009-05-08 11:54:16 +0900252 blk_dequeue_request(rq);
Tejun Heo40cbbb72009-04-23 11:05:19 +0900253 __blk_end_request_all(rq, -EOPNOTSUPP);
Jens Axboe86db1e22008-01-29 14:53:40 +0100254 *rqp = NULL;
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900255 return false;
Jens Axboe86db1e22008-01-29 14:53:40 +0100256 }
257 }
258
259 /*
260 * Ordered sequence in progress
261 */
262
263 /* Special requests are not subject to ordering rules. */
264 if (!blk_fs_request(rq) &&
265 rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900266 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100267
Tejun Heo313e4292008-11-28 13:32:02 +0900268 if (q->ordered & QUEUE_ORDERED_BY_TAG) {
Jens Axboe86db1e22008-01-29 14:53:40 +0100269 /* Ordered by tag. Blocking the next barrier is enough. */
270 if (is_barrier && rq != &q->bar_rq)
271 *rqp = NULL;
272 } else {
273 /* Ordered by draining. Wait for turn. */
274 WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
275 if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
276 *rqp = NULL;
277 }
278
Tejun Heo8f11b3e2008-11-28 13:32:05 +0900279 return true;
Jens Axboe86db1e22008-01-29 14:53:40 +0100280}
281
282static void bio_end_empty_barrier(struct bio *bio, int err)
283{
Jens Axboecc66b452008-03-04 11:47:46 +0100284 if (err) {
285 if (err == -EOPNOTSUPP)
286 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
Jens Axboe86db1e22008-01-29 14:53:40 +0100287 clear_bit(BIO_UPTODATE, &bio->bi_flags);
Jens Axboecc66b452008-03-04 11:47:46 +0100288 }
Jens Axboe86db1e22008-01-29 14:53:40 +0100289
290 complete(bio->bi_private);
291}
292
293/**
294 * blkdev_issue_flush - queue a flush
295 * @bdev: blockdev to issue flush for
296 * @error_sector: error sector
297 *
298 * Description:
299 * Issue a flush for the block device in question. Caller can supply
300 * room for storing the error offset in case of a flush error, if they
Theodore Ts'odbdac9b2009-01-13 15:27:32 +0100301 * wish to.
Jens Axboe86db1e22008-01-29 14:53:40 +0100302 */
303int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
304{
305 DECLARE_COMPLETION_ONSTACK(wait);
306 struct request_queue *q;
307 struct bio *bio;
308 int ret;
309
310 if (bdev->bd_disk == NULL)
311 return -ENXIO;
312
313 q = bdev_get_queue(bdev);
314 if (!q)
315 return -ENXIO;
316
317 bio = bio_alloc(GFP_KERNEL, 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100318 bio->bi_end_io = bio_end_empty_barrier;
319 bio->bi_private = &wait;
320 bio->bi_bdev = bdev;
OGAWA Hirofumi2ebca852008-08-11 17:07:08 +0100321 submit_bio(WRITE_BARRIER, bio);
Jens Axboe86db1e22008-01-29 14:53:40 +0100322
323 wait_for_completion(&wait);
324
325 /*
326 * The driver must store the error location in ->bi_sector, if
327 * it supports it. For non-stacked drivers, this should be copied
Tejun Heo83096eb2009-05-07 22:24:39 +0900328 * from blk_rq_pos(rq).
Jens Axboe86db1e22008-01-29 14:53:40 +0100329 */
330 if (error_sector)
331 *error_sector = bio->bi_sector;
332
333 ret = 0;
Jens Axboecc66b452008-03-04 11:47:46 +0100334 if (bio_flagged(bio, BIO_EOPNOTSUPP))
335 ret = -EOPNOTSUPP;
336 else if (!bio_flagged(bio, BIO_UPTODATE))
Jens Axboe86db1e22008-01-29 14:53:40 +0100337 ret = -EIO;
338
339 bio_put(bio);
340 return ret;
341}
Jens Axboe86db1e22008-01-29 14:53:40 +0100342EXPORT_SYMBOL(blkdev_issue_flush);
David Woodhousefb2dce82008-08-05 18:01:53 +0100343
344static void blkdev_discard_end_io(struct bio *bio, int err)
345{
346 if (err) {
347 if (err == -EOPNOTSUPP)
348 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
349 clear_bit(BIO_UPTODATE, &bio->bi_flags);
350 }
351
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200352 if (bio->bi_private)
353 complete(bio->bi_private);
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200354 __free_page(bio_page(bio));
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200355
David Woodhousefb2dce82008-08-05 18:01:53 +0100356 bio_put(bio);
357}
358
359/**
360 * blkdev_issue_discard - queue a discard
361 * @bdev: blockdev to issue discard for
362 * @sector: start sector
363 * @nr_sects: number of sectors to discard
Hugh Dickins3e6053d2008-09-11 10:57:55 +0200364 * @gfp_mask: memory allocation flags (for bio_alloc)
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200365 * @flags: DISCARD_FL_* flags to control behaviour
David Woodhousefb2dce82008-08-05 18:01:53 +0100366 *
367 * Description:
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200368 * Issue a discard request for the sectors in question.
David Woodhousefb2dce82008-08-05 18:01:53 +0100369 */
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200370int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
371 sector_t nr_sects, gfp_t gfp_mask, int flags)
David Woodhousefb2dce82008-08-05 18:01:53 +0100372{
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200373 DECLARE_COMPLETION_ONSTACK(wait);
374 struct request_queue *q = bdev_get_queue(bdev);
375 int type = flags & DISCARD_FL_BARRIER ?
376 DISCARD_BARRIER : DISCARD_NOBARRIER;
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200377 struct bio *bio;
378 struct page *page;
David Woodhousefb2dce82008-08-05 18:01:53 +0100379 int ret = 0;
380
David Woodhousefb2dce82008-08-05 18:01:53 +0100381 if (!q)
382 return -ENXIO;
383
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200384 if (!blk_queue_discard(q))
David Woodhousefb2dce82008-08-05 18:01:53 +0100385 return -EOPNOTSUPP;
386
387 while (nr_sects && !ret) {
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200388 unsigned int sector_size = q->limits.logical_block_size;
Christoph Hellwig67efc922009-09-30 13:54:20 +0200389 unsigned int max_discard_sectors =
390 min(q->limits.max_discard_sectors, UINT_MAX >> 9);
David Woodhousefb2dce82008-08-05 18:01:53 +0100391
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200392 bio = bio_alloc(gfp_mask, 1);
393 if (!bio)
394 goto out;
395 bio->bi_sector = sector;
David Woodhousefb2dce82008-08-05 18:01:53 +0100396 bio->bi_end_io = blkdev_discard_end_io;
397 bio->bi_bdev = bdev;
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200398 if (flags & DISCARD_FL_WAIT)
399 bio->bi_private = &wait;
David Woodhousefb2dce82008-08-05 18:01:53 +0100400
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200401 /*
402 * Add a zeroed one-sector payload as that's what
403 * our current implementations need. If we'll ever need
404 * more the interface will need revisiting.
405 */
OGAWA Hirofumie79e95d2009-12-29 08:53:54 +0100406 page = alloc_page(gfp_mask | __GFP_ZERO);
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200407 if (!page)
408 goto out_free_bio;
409 if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
410 goto out_free_page;
David Woodhousefb2dce82008-08-05 18:01:53 +0100411
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200412 /*
413 * And override the bio size - the way discard works we
414 * touch many more blocks on disk than the actual payload
415 * length.
416 */
Christoph Hellwig67efc922009-09-30 13:54:20 +0200417 if (nr_sects > max_discard_sectors) {
418 bio->bi_size = max_discard_sectors << 9;
419 nr_sects -= max_discard_sectors;
420 sector += max_discard_sectors;
David Woodhousefb2dce82008-08-05 18:01:53 +0100421 } else {
422 bio->bi_size = nr_sects << 9;
423 nr_sects = 0;
424 }
David Woodhousefb2dce82008-08-05 18:01:53 +0100425
Christoph Hellwig746cd1e2009-09-12 07:35:43 +0200426 bio_get(bio);
427 submit_bio(type, bio);
428
429 if (flags & DISCARD_FL_WAIT)
430 wait_for_completion(&wait);
431
David Woodhousefb2dce82008-08-05 18:01:53 +0100432 if (bio_flagged(bio, BIO_EOPNOTSUPP))
433 ret = -EOPNOTSUPP;
434 else if (!bio_flagged(bio, BIO_UPTODATE))
435 ret = -EIO;
436 bio_put(bio);
437 }
438 return ret;
Christoph Hellwigc15227d2009-09-30 13:52:12 +0200439out_free_page:
440 __free_page(page);
441out_free_bio:
442 bio_put(bio);
443out:
444 return -ENOMEM;
David Woodhousefb2dce82008-08-05 18:01:53 +0100445}
446EXPORT_SYMBOL(blkdev_issue_discard);