fix incorrect logic in glusterfs.go#canSupport

pkg/volume/glusterfs/glusterfs.go

@@ -110,12 +110,8 @@ func (plugin *glusterfsPlugin) GetVolumeName(spec *volume.Spec) (string, error)
 }
 
 func (plugin *glusterfsPlugin) CanSupport(spec *volume.Spec) bool {
-	if (spec.PersistentVolume != nil && spec.PersistentVolume.Spec.Glusterfs == nil) ||
-		(spec.Volume != nil && spec.Volume.Glusterfs == nil) {
-		return false
-	}
-
-	return true
+	return (spec.PersistentVolume != nil && spec.PersistentVolume.Spec.Glusterfs != nil) ||
+		(spec.Volume != nil && spec.Volume.Glusterfs != nil)
 }
 
 func (plugin *glusterfsPlugin) RequiresRemount() bool {

pkg/volume/glusterfs/glusterfs_test.go

@@ -51,12 +51,24 @@ func TestCanSupport(t *testing.T) {
 	if plug.GetPluginName() != "kubernetes.io/glusterfs" {
 		t.Errorf("Wrong name: %s", plug.GetPluginName())
 	}
-	if plug.CanSupport(&volume.Spec{PersistentVolume: &v1.PersistentVolume{Spec: v1.PersistentVolumeSpec{PersistentVolumeSource: v1.PersistentVolumeSource{}}}}) {
+	if plug.CanSupport(&volume.Spec{}) {
 		t.Errorf("Expected false")
 	}
 	if plug.CanSupport(&volume.Spec{Volume: &v1.Volume{VolumeSource: v1.VolumeSource{}}}) {
 		t.Errorf("Expected false")
 	}
+	if !plug.CanSupport(&volume.Spec{Volume: &v1.Volume{VolumeSource: v1.VolumeSource{Glusterfs: &v1.GlusterfsVolumeSource{}}}}) {
+		t.Errorf("Expected true")
+	}
+	if plug.CanSupport(&volume.Spec{PersistentVolume: &v1.PersistentVolume{Spec: v1.PersistentVolumeSpec{}}}) {
+		t.Errorf("Expected false")
+	}
+	if plug.CanSupport(&volume.Spec{PersistentVolume: &v1.PersistentVolume{Spec: v1.PersistentVolumeSpec{PersistentVolumeSource: v1.PersistentVolumeSource{}}}}) {
+		t.Errorf("Expected false")
+	}
+	if !plug.CanSupport(&volume.Spec{PersistentVolume: &v1.PersistentVolume{Spec: v1.PersistentVolumeSpec{PersistentVolumeSource: v1.PersistentVolumeSource{Glusterfs: &v1.GlusterfsVolumeSource{}}}}}) {
+		t.Errorf("Expected true")
+	}
 }
 
 func TestGetAccessModes(t *testing.T) {