in gce-containers-startup/volumes/volumes.go [443:450]
func (env Env) unmountDevice(mnt mount) error {
log.Printf("Attempting to unmount device %s at %s.", mnt.device, mnt.mountPoint)
_, err := env.OsCommandRunner.Run(wrapToEnterHostMountNamespace("umount", mnt.mountPoint)...)
if err != nil {
return fmt.Errorf("Failed to unmount %s at %s: %v", mnt.device, mnt.mountPoint, err)
}
return nil
}