diff --git a/common/rc b/common/rc
index d5e3aff0..435f74f4 100644
--- a/common/rc
+++ b/common/rc
@@ -571,7 +571,9 @@ _scratch_mkfs()
         _scratch_cleanup_files
 	;;
     cifs)
-	# do nothing for cifs
+	# unable to re-create CIFS, just remove all files in $SCRATCH_MNT to
+	# avoid EEXIST caused by the leftover files created in previous runs
+        _scratch_cleanup_files
 	;;
     udf)
         $MKFS_UDF_PROG $MKFS_OPTIONS $* $SCRATCH_DEV > /dev/null
@@ -1053,7 +1055,13 @@ _require_scratch_nocheck()
 		fi
 		;;
 	cifs)
-		_notrun "requires a scratch device"
+		echo $SCRATCH_DEV | grep -q "//" > /dev/null 2>&1
+		if [ -z "$SCRATCH_DEV" -o "$?" != "0" ]; then
+			_notrun "this test requires a valid \$SCRATCH_DEV"
+		fi
+		if [ ! -d "$SCRATCH_MNT" ]; then
+		     _notrun "this test requires a valid \$SCRATCH_MNT"
+		fi
 		;;
 	tmpfs)
 		if [ -z "$SCRATCH_DEV" -o ! -d "$SCRATCH_MNT" ];