Commit 867de40c authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm writecache: write at least 4k when committing 



SSDs perform badly with sub-4k writes (because they perfrorm
read-modify-write internally), so make sure writecache writes at least
4k when committing.

Fixes: 991bd8d7 ("dm writecache: commit just one block, not a full page")
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent ee55b92a

drivers/md/dm-writecache.c

+5 −1
Original line number Diff line number Diff line
@@ -532,7 +532,11 @@ static void ssd_commit_superblock(struct dm_writecache *wc) 


	region.bdev = wc->ssd_dev->bdev;

	region.sector = 0;

	region.count = wc->block_size >> SECTOR_SHIFT;

	region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT;



	if (unlikely(region.sector + region.count > wc->metadata_sectors))

		region.count = wc->metadata_sectors - region.sector;



	region.sector += wc->start_sector;



	req.bi_op = REQ_OP_WRITE;