rbd: use RbdSnapName to check the image details

RbdSnapName holds the actual RBD image name which
got created during the CreateSnapshot operation.
RbdImageName holds the name of the parent from
which the snapshot is created. and the parent
is independent of snapshot and it can be deleted
any time for the same reason using the RbdSnapName
to check the rbd image details.

generate a temporary volume from the snapshot which
replaces the rbdImageName with RbdSnapName and use
it to check the image metadata.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>
(cherry picked from commit 6d14eeee70)

internal/rbd/rbd_util.go

@@ -1566,3 +1566,31 @@ func (ri *rbdImage) isCompatibleThickProvision(dst *rbdVolume) error {
 
 	return nil
 }
+
+// FIXME: merge isCompatibleThickProvision of rbdSnapshot and rbdImage to a single
+// function.
+func (rs *rbdSnapshot) isCompatibleThickProvision(dst *rbdVolume) error {
+	// During CreateSnapshot the rbd image will be created with the
+	// snapshot name. Replacing RbdImageName with RbdSnapName so that we
+	// can check if the image is thick provisioned
+	vol := generateVolFromSnap(rs)
+	err := vol.Connect(rs.conn.Creds)
+	if err != nil {
+		return err
+	}
+	defer vol.Destroy()
+
+	thick, err := vol.isThickProvisioned()
+	if err != nil {
+		return err
+	}
+	switch {
+	case thick && !dst.ThickProvision:
+		return fmt.Errorf("cannot create thin volume from thick volume %q", vol)
+
+	case !thick && dst.ThickProvision:
+		return fmt.Errorf("cannot create thick volume from thin volume %q", vol)
+	}
+
+	return nil
+}