Introduce _mkfs_scratch_clone() to mkfs the scratch device and clone it to
the next device in SCRATCH_DEV_POOL.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 common/rc | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/common/rc b/common/rc
index 9db8b3e88996..2253438ef0f6 100644
--- a/common/rc
+++ b/common/rc
@@ -1503,6 +1503,38 @@ _scratch_resvblks()
 	esac
 }
 
+_scratch_mkfs_sized_clone()
+{
+	local devs=($SCRATCH_DEV_POOL)
+	local scratch_data="$1"
+	local size=$(_small_fs_size_mb 128) # Smallest possible
+
+	size=$((size * 1024 * 1024))
+
+	# make sure there are two devices
+	if [ "${#devs[@]}" -ne 2 ]; then
+		_notrun "Test requires exactly 2 devices"
+	fi
+
+	case "$FSTYP" in
+	"btrfs")
+		_scratch_mkfs_sized $size
+		_scratch_mount
+		$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/sv1
+		_scratch_unmount
+		;;
+	"xfs"|"ext4")
+		_scratch_mkfs_sized $size
+		;;
+	*)
+		_notrun "fstests clone op unsupported for FS $FSTYP"
+		;;
+	esac
+
+	# clone SCRATCH_DEV devs[0] to devs[1].
+	dd if=$SCRATCH_DEV of=${devs[1]} bs=$size status=none count=1 || \
+							_fail "Clone failed"
+}
 
 # Repair scratch filesystem.  Returns 0 if the FS is good to go (either no
 # errors found or errors were fixed) and nonzero otherwise; also spits out
-- 
2.43.0