devmapper: small fixes in error reporting

devmapper/deviceset_devmapper.go

@@ -365,8 +365,7 @@ func (devices *DeviceSetDM) initDevmapper() error {
 
 	st, err := os.Stat(data)
 	if err != nil {
-		utils.Debugf("\n--->Err: %s\n", err)
-		return err
+		return fmt.Errorf("Error looking up data image %s: %s", data, err)
 	}
 	sysSt := st.Sys().(*syscall.Stat_t)
 	// "reg-" stands for "regular file".

devmapper/devmapper.go

@@ -247,9 +247,6 @@ func (t *Task) SetName(name string) error {
 	defer free(c_name)
 
 	if res := C.dm_task_set_name(t.unmanaged, c_name); res != 1 {
-		if os.Getenv("DEBUG") != "" {
-			C.perror(C.CString(fmt.Sprintf("[debug] Error dm_task_set_name(%s, %#v)", name, t.unmanaged)))
-		}
 		return ErrTaskSetName
 	}
 	return nil