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author | Martin K. Petersen <martin.petersen@oracle.com> | 2012-09-18 12:19:27 -0400 |
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committer | Jens Axboe <axboe@kernel.dk> | 2012-09-20 14:31:45 +0200 |
commit | 4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4 (patch) | |
tree | 010b05699eb9544b9cdfe5e1b3affdaea80132e7 /block/blk-lib.c | |
parent | f31dc1cd490539e2b62a126bc4dc2495b165d772 (diff) | |
download | linux-stable-4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4.tar.gz linux-stable-4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4.tar.bz2 linux-stable-4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4.zip |
block: Implement support for WRITE SAME
The WRITE SAME command supported on some SCSI devices allows the same
block to be efficiently replicated throughout a block range. Only a
single logical block is transferred from the host and the storage device
writes the same data to all blocks described by the I/O.
This patch implements support for WRITE SAME in the block layer. The
blkdev_issue_write_same() function can be used by filesystems and block
drivers to replicate a buffer across a block range. This can be used to
efficiently initialize software RAID devices, etc.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-lib.c')
-rw-r--r-- | block/blk-lib.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/block/blk-lib.c b/block/blk-lib.c index 19cc761cacb2..a062543c58ac 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -130,6 +130,80 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, EXPORT_SYMBOL(blkdev_issue_discard); /** + * blkdev_issue_write_same - queue a write same operation + * @bdev: target blockdev + * @sector: start sector + * @nr_sects: number of sectors to write + * @gfp_mask: memory allocation flags (for bio_alloc) + * @page: page containing data to write + * + * Description: + * Issue a write same request for the sectors in question. + */ +int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, + sector_t nr_sects, gfp_t gfp_mask, + struct page *page) +{ + DECLARE_COMPLETION_ONSTACK(wait); + struct request_queue *q = bdev_get_queue(bdev); + unsigned int max_write_same_sectors; + struct bio_batch bb; + struct bio *bio; + int ret = 0; + + if (!q) + return -ENXIO; + + max_write_same_sectors = q->limits.max_write_same_sectors; + + if (max_write_same_sectors == 0) + return -EOPNOTSUPP; + + atomic_set(&bb.done, 1); + bb.flags = 1 << BIO_UPTODATE; + bb.wait = &wait; + + while (nr_sects) { + bio = bio_alloc(gfp_mask, 1); + if (!bio) { + ret = -ENOMEM; + break; + } + + bio->bi_sector = sector; + bio->bi_end_io = bio_batch_end_io; + bio->bi_bdev = bdev; + bio->bi_private = &bb; + bio->bi_vcnt = 1; + bio->bi_io_vec->bv_page = page; + bio->bi_io_vec->bv_offset = 0; + bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev); + + if (nr_sects > max_write_same_sectors) { + bio->bi_size = max_write_same_sectors << 9; + nr_sects -= max_write_same_sectors; + sector += max_write_same_sectors; + } else { + bio->bi_size = nr_sects << 9; + nr_sects = 0; + } + + atomic_inc(&bb.done); + submit_bio(REQ_WRITE | REQ_WRITE_SAME, bio); + } + + /* Wait for bios in-flight */ + if (!atomic_dec_and_test(&bb.done)) + wait_for_completion(&wait); + + if (!test_bit(BIO_UPTODATE, &bb.flags)) + ret = -ENOTSUPP; + + return ret; +} +EXPORT_SYMBOL(blkdev_issue_write_same); + +/** * blkdev_issue_zeroout - generate number of zero filed write bios * @bdev: blockdev to issue * @sector: start sector |