_scratch_unmount
+# Convert it to btrfs, mount it and delete "ext2_saved"
+$BTRFS_CONVERT_PROG $SCRATCH_DEV >> $seqres.full 2>&1 || \
+ _fail "btrfs-convert failed"
+_scratch_mount || _fail "Could not mount new btrfs fs"
+$BTRFS_UTIL_PROG subvolume delete $SCRATCH_MNT/ext2_saved >> $seqres.full 2>&1 ||
+ _fail "failed to delete ext2_saved subvolume"
+_scratch_unmount
+
+# Now restore the ext4 device, expecting a failure
+$BTRFS_CONVERT_PROG -r $SCRATCH_DEV >> $seqres.full 2>&1
+[ $? -eq 1 ] || _fail "Failure is expected, but btrfs-convert returns with rollback complete"
+
# success, all done
status=0
exit