[dm-devel] [PATCH] dm-writecache: commit just one block, not a full page

[Mikulas Patocka]

When comitting superblock, we need to write just one block, we don't need
to write full page. Some architectures have pages larger than 4k and
committing full page is needless overhead.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

Index: linux-2.6/drivers/md/dm-writecache.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-writecache.c
+++ linux-2.6/drivers/md/dm-writecache.c
@@ -532,11 +532,7 @@ static void ssd_commit_superblock(struct
 
 	region.bdev = wc->ssd_dev->bdev;
 	region.sector = 0;
-	region.count = PAGE_SIZE >> SECTOR_SHIFT;
-
-	if (unlikely(region.sector + region.count > wc->metadata_sectors))
-		region.count = wc->metadata_sectors - region.sector;
-
+	region.count = wc->block_size >> SECTOR_SHIFT;
 	region.sector += wc->start_sector;
 
 	req.bi_op = REQ_OP_WRITE;