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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-merge.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-merge.c')
| -rw-r--r-- | block/blk-merge.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 642b862608a1..936a110de0b9 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -419,6 +419,10 @@ static int attempt_merge(struct request_queue *q, struct request *req, || next->special) return 0; + if (req->cmd_flags & REQ_WRITE_SAME && + !blk_write_same_mergeable(req->bio, next->bio)) + return 0; + /* * If we are allowed to merge, then append bio list * from next to rq and release next. merge_requests_fn @@ -518,6 +522,11 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) if (bio_integrity(bio) != blk_integrity_rq(rq)) return false; + /* must be using the same buffer */ + if (rq->cmd_flags & REQ_WRITE_SAME && + !blk_write_same_mergeable(rq->bio, bio)) + return false; + return true; } |