Send barrier requests when updating the exception area. It needs to be ordered w.r.t. data writes, so that the writes are not reordered in hardware disk cache. Signed-off-by: Mikulas Patocka --- drivers/md/dm-snap-persistent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6.29-rc1-devel/drivers/md/dm-snap-persistent.c =================================================================== --- linux-2.6.29-rc1-devel.orig/drivers/md/dm-snap-persistent.c 2009-01-21 17:07:31.000000000 +0100 +++ linux-2.6.29-rc1-devel/drivers/md/dm-snap-persistent.c 2009-01-22 03:36:43.000000000 +0100 @@ -627,7 +627,7 @@ static void persistent_commit_exception( /* * Commit exceptions to disk. */ - if (ps->valid && area_io(ps, WRITE)) + if (ps->valid && area_io(ps, WRITE_BARRIER)) ps->valid = 0; /*