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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2012-09-18 12:19:27 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-09-20 14:31:45 +0200 |
| commit | 4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4 (patch) | |
| tree | 010b05699eb9544b9cdfe5e1b3affdaea80132e7 /block/blk-core.c | |
| parent | f31dc1cd490539e2b62a126bc4dc2495b165d772 (diff) | |
| download | lwn-4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4.tar.gz lwn-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-core.c')
| -rw-r--r-- | block/blk-core.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 33eded00c5b1..3b080541098e 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1704,6 +1704,11 @@ generic_make_request_checks(struct bio *bio) goto end_io; } + if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) { + err = -EOPNOTSUPP; + goto end_io; + } + /* * Various block parts want %current->io_context and lazy ioc * allocation ends up trading a lot of pain for a small amount of @@ -1809,8 +1814,6 @@ EXPORT_SYMBOL(generic_make_request); */ void submit_bio(int rw, struct bio *bio) { - int count = bio_sectors(bio); - bio->bi_rw |= rw; /* @@ -1818,6 +1821,13 @@ void submit_bio(int rw, struct bio *bio) * go through the normal accounting stuff before submission. */ if (bio_has_data(bio)) { + unsigned int count; + + if (unlikely(rw & REQ_WRITE_SAME)) + count = bdev_logical_block_size(bio->bi_bdev) >> 9; + else + count = bio_sectors(bio); + if (rw & WRITE) { count_vm_events(PGPGOUT, count); } else { |