rollback create retain snapshot from snapshotClass

Signed-off-by: Lyndon-Li <lyonghui@vmware.com>

pkg/exposer/csi_snapshot.go

@@ -500,7 +500,6 @@ func (e *csiSnapshotExposer) CleanUp(ctx context.Context, ownerObject corev1api.
 	backupPodName := ownerObject.Name
 	backupPVCName := ownerObject.Name
 	backupVSName := ownerObject.Name
-	backupVSCName := ownerObject.Name
 
 	kube.DeletePodIfAny(ctx, e.kubeClient.CoreV1(), backupPodName, ownerObject.Namespace, e.log)
 	kube.DeletePVAndPVCIfAny(ctx, e.kubeClient.CoreV1(), backupPVCName, ownerObject.Namespace, cleanUpTimeout, e.log)
@@ -512,13 +511,6 @@ func (e *csiSnapshotExposer) CleanUp(ctx context.Context, ownerObject corev1api.
 
 	csi.DeleteVolumeSnapshotIfAny(ctx, e.csiSnapshotClient, backupVSName, ownerObject.Namespace, e.log)
 	csi.DeleteVolumeSnapshotIfAny(ctx, e.csiSnapshotClient, vsName, sourceNamespace, e.log)
-
-	// The backup VSC is created by Velero as an internal handle to the source
-	// snapshot. Deleting the backup VS above only cascades to it when its
-	// deletion policy is Delete, so remove it explicitly to avoid leaking the
-	// object under a Retain policy. Deleting a Retain VSC drops only the API
-	// object and leaves the underlying snapshot intact.
-	csi.DeleteVolumeSnapshotContentIfAny(ctx, e.csiSnapshotClient, backupVSCName, e.log)
 }
 
 func getVolumeModeByAccessMode(accessMode string, dataMover string) (corev1api.PersistentVolumeMode, error) {
@@ -583,21 +575,7 @@ func (e *csiSnapshotExposer) createBackupVSC(ctx context.Context, ownerObject co
 			Source: snapshotv1api.VolumeSnapshotContentSource{
 				SnapshotHandle: snapshotVSC.Status.SnapshotHandle,
 			},
-			// The backup VSC is statically provisioned against the same
-			// snapshot handle as the source VSC, so both objects refer to one
-			// physical snapshot. Inherit the source's deletion policy instead
-			// of forcing Delete, otherwise a user who configured Retain on the
-			// VolumeSnapshotClass still loses the snapshot when the backup VSC
-			// is cleaned up.
-			//
-			// For Case 2 storages per the design (design/block-data-mover/block-data-mover.md,
-			// e.g. Ceph RBD), inheriting Retain is not just an option but a requirement for
-			// incrementals to work at all: rbd snap diff needs the base and target snapshots
-			// in the same clone chain, so Delete destroys the base as soon as this backup
-			// completes. The next incremental's delta query then fails and degrades to an
-			// allocated-blocks backup (see the CBT tier ladder) or, without that fix, a full
-			// whole-device transfer.
-			DeletionPolicy:          snapshotVSC.Spec.DeletionPolicy,
+			DeletionPolicy:          snapshotv1api.VolumeSnapshotContentDelete,
 			Driver:                  snapshotVSC.Spec.Driver,
 			VolumeSnapshotClassName: snapshotVSC.Spec.VolumeSnapshotClassName,
 		},

pkg/exposer/csi_snapshot_test.go

@@ -1222,7 +1222,7 @@ func TestExpose(t *testing.T) {
 
 				assert.Equal(t, anno, backupVSC.Annotations)
 				assert.Equal(t, vscObj.Labels, backupVSC.Labels)
-				assert.Equal(t, vscObj.Spec.DeletionPolicy, backupVSC.Spec.DeletionPolicy)
+				assert.Equal(t, snapshotv1api.VolumeSnapshotContentDelete, backupVSC.Spec.DeletionPolicy)
 				assert.Equal(t, vscObj.Spec.Driver, backupVSC.Spec.Driver)
 				assert.Equal(t, *vscObj.Spec.VolumeSnapshotClassName, *backupVSC.Spec.VolumeSnapshotClassName)
 
@@ -2575,17 +2575,16 @@ func TestCreateBackupVSCDeletionPolicy(t *testing.T) {
 		expectedPolicy snapshotv1api.DeletionPolicy
 	}{
 		{
-			name:           "Delete policy is inherited",
+			name:           "Delete source policy uses Delete",
 			sourcePolicy:   snapshotv1api.VolumeSnapshotContentDelete,
 			expectedPolicy: snapshotv1api.VolumeSnapshotContentDelete,
 		},
 		{
-			// The backup VSC points at the same snapshot handle as the source
-			// VSC, so forcing Delete here would destroy a snapshot the user
-			// asked to keep.
-			name:           "Retain policy is inherited",
+			// Data mover cleanup must delete the underlying snapshot even when
+			// the source SnapshotClass uses Retain.
+			name:           "Retain source policy is overridden with Delete",
 			sourcePolicy:   snapshotv1api.VolumeSnapshotContentRetain,
-			expectedPolicy: snapshotv1api.VolumeSnapshotContentRetain,
+			expectedPolicy: snapshotv1api.VolumeSnapshotContentDelete,
 		},
 	}