rbd: use ListChildrenAttributes() instead of ListChildren()

This commit modifies listSnapAndChildren() to make use of
ListChildrenAttributes() instead of ListChildren() which
allows us to filter out images in trash.
This commit also order the alive images so that temp clone
images are followed by images backing volume snapshots so
that temp clone images are flattened first.

Signed-off-by: Rakshith R <rar@redhat.com>

internal/rbd/rbd_util.go

@@ -84,6 +84,10 @@ const (
 
 	// clusterNameKey cluster Key, set on RBD image.
 	clusterNameKey = "csi.ceph.com/cluster/name"
+
+	// Suffix added to the temp cloned image name.
+	// This will always be (rbd image name + "-temp").
+	tempImageSuffix = "-temp"
 )
 
 // rbdImage contains common attributes and methods for the rbdVolume and
@@ -2025,26 +2029,49 @@ func (ri *rbdImage) DisableDeepFlatten() error {
 	return image.UpdateFeatures(librbd.FeatureDeepFlatten, false)
 }
 
-// listSnapAndChildren returns list of names of snapshots and child images.
-func (ri *rbdImage) listSnapAndChildren() ([]librbd.SnapInfo, []string, error) {
+type snapAndChildrenInfo struct {
+	SnapInfoList           []librbd.SnapInfo
+	TempCloneChildren      []string
+	VolumeSnapshotChildren []string
+}
+
+// listSnapAndChildren returns list of snapshot names, volume snapshot images and
+// child temp clone images. Only child images which are not in trash are returned.
+func (ri *rbdImage) listSnapAndChildren() (*snapAndChildrenInfo, error) {
 	image, err := ri.open()
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 	defer image.Close()
 
 	snaps, err := image.GetSnapshotNames()
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
-	// ListChildren() returns pools, images, err.
-	_, children, err := image.ListChildren()
+	childImageSpecList, err := image.ListChildrenAttributes()
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
-	return snaps, children, nil
+	tempCloneChildren := make([]string, 0)
+	volSnapChildren := make([]string, 0)
+	for _, child := range childImageSpecList {
+		if child.Trash {
+			continue
+		}
+		if isTempClonedImage(child.ImageName) {
+			tempCloneChildren = append(tempCloneChildren, child.ImageName)
+		} else {
+			volSnapChildren = append(volSnapChildren, child.ImageName)
+		}
+	}
+
+	return &snapAndChildrenInfo{
+		SnapInfoList:           snaps,
+		TempCloneChildren:      tempCloneChildren,
+		VolumeSnapshotChildren: volSnapChildren,
+	}, nil
 }
 
 func (ri *rbdImage) isCompatibleEncryption(dst *rbdImage) error {