The writeback error handling test requires that you put the journal on a
separate device. This allows us to use dmerror to simulate data
writeback failure, without affecting the journal.

xfs already has infrastructure for this (a'la $SCRATCH_LOGDEV), so wire
up the ext4 code so that it can do the same thing when _scratch_mkfs is
called.

Signed-off-by: Jeff Layton <redacted>
Reviewed-by: Darrick J. Wong <redacted>
---
 common/rc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/common/rc b/common/rc
index ff1b75c9cd25..57001b47a8b7 100644
--- a/common/rc
+++ b/common/rc

@@ -679,6 +679,9 @@ _scratch_mkfs_ext4()
 	local tmp=`mktemp`
 	local mkfs_status
 
+	[ "$USE_EXTERNAL" = yes -a ! -z "$SCRATCH_LOGDEV" ] && \
+	    $mkfs_cmd -O journal_dev $MKFS_OPTIONS $SCRATCH_LOGDEV && \
+	    mkfs_cmd="$mkfs_cmd -J device=$SCRATCH_LOGDEV"
 
 	_scratch_do_mkfs "$mkfs_cmd" "$mkfs_filter" $* 2>$tmp.mkfserr 1>$tmp.mkfsstd
 	mkfs_status=$?

-- 
2.13.0