bug fix

src/csi/backend/backend.go

@@ -39,8 +39,6 @@ var (
 	}
 )
 
-type FilterFunction func(interface{}, []*StoragePool) []*StoragePool
-
 type AccessibleTopology struct {
 	RequisiteTopologies []map[string]string
 	PreferredTopologies []map[string]string
@@ -124,9 +122,13 @@ func newBackend(backendName string, config map[string]interface{}) (*Backend, er
 		return nil, errors.New("parameters must be configured for backend")
 	}
 
-	supportedTopologies, exists := config[SupportedTopologies].([]map[string]string)
-	if !exists {
-		supportedTopologies = make([]map[string]string, 0)
+	supportedTopologies := make([]map[string]string, 0)
+	if _, exist = config[SupportedTopologies]; exist {
+		topologies, ok := config[SupportedTopologies].([]map[string]string)
+		if !ok {
+			return nil, errors.New("invalid supported topologies configuration")
+		}
+		supportedTopologies = topologies
 	}
 
 	plugin := plugin.GetPlugin(storage)
@@ -290,7 +292,7 @@ func selectOnePool(requestSize int64,
 	}
 
 	for _, i := range filterFuncs {
-		key, filter := i[0].(string), i[1].(FilterFunction)
+		key, filter := i[0].(string), i[1].(func(interface{}, []*StoragePool) []*StoragePool)
 		value, exists := parameters[key]
 		if exists {
 			filterPools = filter(value, filterPools)
@@ -599,7 +601,6 @@ func sortPoolsByPreferredTopologies(candidatePools []*StoragePool, preferredTopo
 	orderedPools := make([]*StoragePool, 0)
 
 	for _, preferred := range preferredTopologies {
-
 		newRemainingPools := make([]*StoragePool, 0)
 		poolBucket := make([]*StoragePool, 0)