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authorMartin K. Petersen <martin.petersen@oracle.com>2012-09-18 12:19:27 -0400
committerJens Axboe <axboe@kernel.dk>2012-09-20 14:31:45 +0200
commit4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4 (patch)
tree010b05699eb9544b9cdfe5e1b3affdaea80132e7 /block/blk-core.c
parentf31dc1cd490539e2b62a126bc4dc2495b165d772 (diff)
downloadvexpress-lsk-4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4.tar.gz
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.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 33eded00c5b..3b080541098 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 {