NFS server fails to export XFS volume directory

[Naoyuki Tai]

Xubuntu 14.04.01 LTS, x86-64.
Linux akhenaten 3.13.0-39-generic #66-Ubuntu SMP Tue Oct 28 13:30:27 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

On this machine, "/var" volume is formatted with XFS. XFS is formatted during the installation of Xubuntu.

/etc/exports has an entry to export "/var/www":
/var/www 192.168.10.0/24(rw,sync,no_root_squash,no_subtree_check,insecure)

The Linux NFS client can mount the NFS export but trying to access it returns an error. (And incorrect message of it.)
mount akhenaten:/var/www /mnt/www
ls /mnt/www

This does not work. I have tried a few variations, and this is what I know.
(1) If you export the root of XFS volume ("/var" this case), it works.
(2) If you create a direcotry such as /exports/www, use "mount -o bind" to bind /var/www with /exports/www and export it, the client times out.
(3) If the file system is EXT4, the NFS export works. (I copied the XFS /var to another disk with EXT4 formatted volume, changed /etc/fstab and rebooted, without any other changes.)

Here is the nfs-kernel-server

Package: nfs-kernel-server
State: installed
Automatically installed: no
Version: 1:1.2.8-6ubuntu1.1
Priority: optional
Section: net
Maintainer: Ubuntu Developers <email address hidden>
Architecture: amd64
Uncompressed Size: 524 k
Depends: libblkid1 (>= 2.16), libc6 (>= 2.15), libcap2 (>= 2.10), libsqlite3-0 (>= 3.5.9), libtirpc1, libwrap0
         (>= 7.6-4~), nfs-common (= 1:1.2.8-6ubuntu1.1), ucf, lsb-base (>= 1.3-9ubuntu3)
Conflicts: knfs, knfs, nfs-server, nfs-server, nfs-kernel-server
Replaces: knfs, knfs, nfs-server, nfs-server
Provides: knfs, nfs-server
Description: support for NFS kernel server

ntai@akhenaten:~$ aptitude show xfsprogs
Package: xfsprogs
State: installed
Automatically installed: no
Version: 3.1.9ubuntu2
Priority: optional
Section: admin
Maintainer: Ubuntu Developers <email address hidden>
Architecture: amd64
Uncompressed Size: 2,691 k
Depends: libblkid1 (>= 2.17.2), libc6 (>= 2.14), libreadline5 (>= 5.2), libuuid1 (>= 2.16)
Suggests: xfsdump, acl, attr, quota
Conflicts: xfsprogs
Breaks: xfsdump (< 3.0.0), xfsdump (< 3.0.0)
Replaces: xfsdump (< 3.0.0), xfsdump (< 3.0.0)
Provides: fsck-backend
Description: Utilities for managing the XFS filesystem
 A set of commands to use the XFS filesystem, including mkfs.xfs.

[Bryan Quigley (bryanquigley)]

This looks like it might be the issue described in - http://xfs.org/index.php/XFS_FAQ#Q:_Why_doesn.27t_NFS-exporting_subdirectories_of_inode64-mounted_filesystem_work.3F