如何在 docker 中成功启用 udev 同步？

Question

我已经docker 1.6.1从该站点下载并安装了静态链接，并在以下位置运行它RHEL 7.1：

[root@localhost bin]# ./docker -d

WARN[0000] Udev sync is not supported. This will lead to unexpected behavior, data loss and errors

INFO[0000] +job init_networkdriver()

INFO[0000] +job serveapi(unix:///var/run/docker.sock)

INFO[0000] Listening for HTTP on unix (/var/run/docker.sock)

INFO[0000] -job init_networkdriver() = OK (0)

INFO[0000] Loading containers: start.

INFO[0000] Loading containers: done.

INFO[0000] docker daemon: 1.6.1 97cd073; execdriver: native-0.2; graphdriver: devicemapper

INFO[0000] +job acceptconnections()

INFO[0000] -job acceptconnections() = OK (0)

INFO[0000] Daemon has completed initialization

我可以看到有一个警告：“ Udev sync is not supported. This will lead to unexpected behavior, data loss and errors”，检查docker源代码后，我发现警告日志来自deviceset.go：

func (devices *DeviceSet) initDevmapper(doInit bool) error {

    ......

    // https://github.com/docker/docker/issues/4036

    if supported := devicemapper.UdevSetSyncSupport(true); !supported {

        log.Warnf("Udev sync is not supported. This will lead to unexpected behavior, data loss and errors")

    }

    log.Debugf("devicemapper: udev sync support: %v", devicemapper.UdevSyncSupported())

    ......

}

该devicemapper.UdevSetSyncSupport是这样的：

// UdevSyncSupported returns whether device-mapper is able to sync with udev

//

// This is essential otherwise race conditions can arise where both udev and

// device-mapper attempt to create and destroy devices.

func UdevSyncSupported() bool {

    return DmUdevGetSyncSupport() != 0

}

// UdevSetSyncSupport allows setting whether the udev sync should be enabled.

// The return bool indicates the state of whether the sync is enabled.

func UdevSetSyncSupport(enable bool) bool {

    if enable {

        DmUdevSetSyncSupport(1)

    } else {

        DmUdevSetSyncSupport(0)

    }

    return UdevSyncSupported()

}

我可以看到原因是启用udev同步失败。如何udev成功启用同步？