From 4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4 Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Tue, 18 Sep 2012 12:19:27 -0400 Subject: 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 Acked-by: Mike Snitzer Signed-off-by: Jens Axboe --- block/blk-merge.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'block/blk-merge.c') 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; } -- cgit v1.2.3-70-g09d2