mount nfs4 ....No such file or directory

今天用nfs的时候遇到奇怪的问题：

先是：
bee@Thinkpad-x201:/mnt$ sudo mount 192.168.1.177:/share/mnt/test/
mount.nfs: access denied by server while mounting192.168.1.177:/share

发现是nfs版本的问题，我是通过apt-get install安装的nfs，估计是更新到了nfs v4版本，所以需要加上特殊的参数-t nfs4

但加上-t nfs4参数后server没有拒绝，但是却又有一个错误：
bee@Thinkpad-x201:/mnt$ 

sudo mount -t nfs4192.168.1.177:/share /mnt/test/
mount.nfs4: 192.168.1.177:/share failed, reason given by server: Nosuch file or directory

这就奇怪了，明明有文件有目录，怎么会视而不见呢？

原来针对NFS4，exports需要一个新的参数fsid，
如我的exports：
/home/bee  *(rw,fsid=0,sync,no_root_squash)

查看exports的帮助：
bee@Thinkpad-x201:~$man exports


fsid=num|root|uuid
                          NFS needs to  be  able  to  identify  each  filesystem  that  it
                          exports.  Normally it will use a UUID for thefilesystem (if the
                          filesystem has such a thing) or the device number ofthe  device
                          holding  the  filesystem  (if  the  filesystem  is stored onthe
                          device).

                          As not all filesystems  are  stored  on  devices,  and  not  all
                          filesystems  have UUIDs, it is sometimes necessaryto explicitly
                          tell NFS how to identify a filesystem.  Thisis  done  with  the
                          fsid= option.

                          For NFSv4, there is a distinguished filesystem which is theroot
                          of all exported filesystem.  This is specifiedwith fsid=root or
                          fsid=0 both of which mean exactly the same thing.

                          Other  filesystems  can beidentified with a small integer, or a
                          UUID which should contain 32 hex digits and  arbitrary  punctua‐
                          tion.

                          Linux  kernels  version 2.6.20and earlier do not understand the