bug fix

src/csi/backend/backend.go

@@ -123,12 +123,20 @@ func newBackend(backendName string, config map[string]interface{}) (*Backend, er
 	}
 
 	supportedTopologies := make([]map[string]string, 0)
-	if _, exist = config[SupportedTopologies]; exist {
-		topologies, ok := config[SupportedTopologies].([]map[string]string)
+	if topologies, exist := config[SupportedTopologies]; exist {
+		topologyArray , ok := topologies.([]map[string]interface{})
 		if !ok {
 			return nil, errors.New("invalid supported topologies configuration")
 		}
-		supportedTopologies = topologies
+		for _, topologyMap := range topologyArray {
+			tempMap := make(map[string]string, 0)
+			for topologyKey, value := range topologyMap {
+				if topologyValue, ok := value.(string); ok {
+					tempMap[topologyKey] = topologyValue
+				}
+			}
+			supportedTopologies = append(supportedTopologies, tempMap)
+		}
 	}
 
 	plugin := plugin.GetPlugin(storage)