diff options
author | David Woodhouse <David.Woodhouse@intel.com> | 2008-08-05 18:01:53 +0100 |
---|---|---|
committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:01 +0200 |
commit | fb2dce862d9f9a68e6b9374579056ec9eca02a63 (patch) | |
tree | 888e0fd7248c9329fa1aa3981043a2dc2457d488 /block/blk-barrier.c | |
parent | d628eaef310533767ce68664873869c2d7f78f09 (diff) | |
download | kernel_samsung_smdk4412-fb2dce862d9f9a68e6b9374579056ec9eca02a63.tar.gz kernel_samsung_smdk4412-fb2dce862d9f9a68e6b9374579056ec9eca02a63.tar.bz2 kernel_samsung_smdk4412-fb2dce862d9f9a68e6b9374579056ec9eca02a63.zip |
Add 'discard' request handling
Some block devices benefit from a hint that they can forget the contents
of certain sectors. Add basic support for this to the block core, along
with a 'blkdev_issue_discard()' helper function which issues such
requests.
The caller doesn't get to provide an end_io functio, since
blkdev_issue_discard() will automatically split the request up into
multiple bios if appropriate. Neither does the function wait for
completion -- it's expected that callers won't care about when, or even
_if_, the request completes. It's only a hint to the device anyway. By
definition, the file system doesn't _care_ about these sectors any more.
[With feedback from OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> and
Jens Axboe <jens.axboe@oracle.com]
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-barrier.c')
-rw-r--r-- | block/blk-barrier.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/block/blk-barrier.c b/block/blk-barrier.c index a09ead19f9c..273121c0eb8 100644 --- a/block/blk-barrier.c +++ b/block/blk-barrier.c @@ -315,3 +315,72 @@ int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) return ret; } EXPORT_SYMBOL(blkdev_issue_flush); + +static void blkdev_discard_end_io(struct bio *bio, int err) +{ + if (err) { + if (err == -EOPNOTSUPP) + set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); + clear_bit(BIO_UPTODATE, &bio->bi_flags); + } + + bio_put(bio); +} + +/** + * blkdev_issue_discard - queue a discard + * @bdev: blockdev to issue discard for + * @sector: start sector + * @nr_sects: number of sectors to discard + * + * Description: + * Issue a discard request for the sectors in question. Does not wait. + */ +int blkdev_issue_discard(struct block_device *bdev, sector_t sector, + unsigned nr_sects) +{ + struct request_queue *q; + struct bio *bio; + int ret = 0; + + if (bdev->bd_disk == NULL) + return -ENXIO; + + q = bdev_get_queue(bdev); + if (!q) + return -ENXIO; + + if (!q->prepare_discard_fn) + return -EOPNOTSUPP; + + while (nr_sects && !ret) { + bio = bio_alloc(GFP_KERNEL, 0); + if (!bio) + return -ENOMEM; + + bio->bi_end_io = blkdev_discard_end_io; + bio->bi_bdev = bdev; + + bio->bi_sector = sector; + + if (nr_sects > q->max_hw_sectors) { + bio->bi_size = q->max_hw_sectors << 9; + nr_sects -= q->max_hw_sectors; + sector += q->max_hw_sectors; + } else { + bio->bi_size = nr_sects << 9; + nr_sects = 0; + } + bio_get(bio); + submit_bio(WRITE_DISCARD, bio); + + /* Check if it failed immediately */ + if (bio_flagged(bio, BIO_EOPNOTSUPP)) + ret = -EOPNOTSUPP; + else if (!bio_flagged(bio, BIO_UPTODATE)) + ret = -EIO; + bio_put(bio); + } + return ret; +} +EXPORT_SYMBOL(blkdev_issue_discard); |