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>

vendor/github.com/ceph/go-ceph/rbd/snapshot_nautilus.go

@@ -168,6 +168,50 @@ func (image *Image) ListChildren() (pools []string, images []string, err error)
 	return pools, images, nil
 }
 
+// ListChildrenAttributes returns an array of struct with the names and ids of the
+// images and pools and the trash of the images that are children of the given image.
+//
+// Implements:
+//
+//	int rbd_list_children3(rbd_image_t image, rbd_linked_image_spec_t *images,
+//	                       size_t *max_images);
+func (image *Image) ListChildrenAttributes() (imgSpec []ImageSpec, err error) {
+	if err := image.validate(imageIsOpen); err != nil {
+		return nil, err
+	}
+	var (
+		csize    C.size_t
+		children []C.rbd_linked_image_spec_t
+	)
+	retry.WithSizes(16, 4096, func(size int) retry.Hint {
+		csize = C.size_t(size)
+		children = make([]C.rbd_linked_image_spec_t, csize)
+		ret := C.rbd_list_children3(
+			image.image,
+			(*C.rbd_linked_image_spec_t)(unsafe.Pointer(&children[0])),
+			&csize)
+		err = getErrorIfNegative(ret)
+		return retry.Size(int(csize)).If(err == errRange)
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer C.rbd_linked_image_spec_list_cleanup((*C.rbd_linked_image_spec_t)(unsafe.Pointer(&children[0])), csize)
+
+	imgSpec = make([]ImageSpec, csize)
+	for i, child := range children[:csize] {
+		imgSpec[i] = ImageSpec{
+			ImageName:     C.GoString(child.image_name),
+			ImageID:       C.GoString(child.image_id),
+			PoolName:      C.GoString(child.pool_name),
+			PoolNamespace: C.GoString(child.pool_namespace),
+			PoolID:        uint64(child.pool_id),
+			Trash:         bool(child.trash),
+		}
+	}
+	return imgSpec, nil
+}
+
 // SetSnapByID updates the rbd image (not the Snapshot) such that the snapshot
 // is the source of readable data.
 //