Clarify comments for DataSource

pkg/apis/core/types.go

@@ -415,7 +415,9 @@ type PersistentVolumeClaimSpec struct {
 	VolumeMode *PersistentVolumeMode
 	// If specified, volume will be prepopulated with data from the specified data source.
 	// This depends on the provisioner for this volume being able to use the specified source.
-	// If the provisioner does not support it, it will create an empty volume.
+	// If the provisioner failed to populate the volume with the source, it will return an
+	// error and fail the create volume operation. If the provisioner does not support the
+	// data source, it will also return an error and fail the create volume operation.
 	// It requires the VolumeSnapshotDataSource alpha feature gate to be enabled and
 	// currently VolumeSnapshot is the only supported data source.
 	// In the future, we will allow more data source types when new feature is ready.

staging/src/k8s.io/api/core/v1/types.go

@@ -460,7 +460,9 @@ type PersistentVolumeClaimSpec struct {
 	VolumeMode *PersistentVolumeMode `json:"volumeMode,omitempty" protobuf:"bytes,6,opt,name=volumeMode,casttype=PersistentVolumeMode"`
 	// If specified, volume will be prepopulated with data from the specified data source.
 	// This depends on the provisioner for this volume being able to use the specified source.
-        // If the provisioner does not support it, it will create an empty volume.
+	// If the provisioner failed to populate the volume with the source, it will return an
+	// error and fail the create volume operation. If the provisioner does not support the
+	// data source, it will also return an error and fail the create volume operation.
 	// It requires the VolumeSnapshotDataSource alpha feature gate to be enabled and
 	// currently VolumeSnapshot is the only supported data source.
 	// In the future, we will allow more data source types when new feature is ready.