Description of problem:
This is a regression - unable to umount a exported path which is a symlink.

Full description is in published article and below in reproduction steps:
https://access.redhat.com/knowledge/solutions/72203

Version-Release number of selected component (if applicable):
nfs-utils-1.2.3-15.el6.x86_64

Downgrading to nfs-utils-1.2.3-7.el6.x86_64 resolves the issue.

How reproducible:
Every time.

Steps to Reproduce:
NFS Server

# mkdir /export
# mkdir /export/foodir
# ln -s /export/foodir /export/foosymlink
# echo '/export *(ro)' > /etc/exports
# cat /etc/exports 
/export         *(ro)
    NFS CLIENT

    # mount -t nfs4 -v rhel6-nfs-server:/export/foosymlink/ /mnt/nfs         
    mount.nfs4: timeout set for Thu Feb 23 16:28:51 2012
    mount.nfs4: trying text-based options 'addr=192.168.122.121,clientaddr=192.168.122.120'
    rhel6-nfs-server:/export/foosymlink on /mnt/nfs type nfs4 (rw)

    # fgrep /export /etc/mtab /proc/mounts    
    /etc/mtab:rhel6-nfs-server:/export/foosymlink /mnt/nfs nfs4         rw,addr=192.168.122.121,clientaddr=192.168.122.120 0 0
    /proc/mounts:rhel6-nfs-server:/export/foodir /mnt/nfs nfs4 rw,relatime,vers=4,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.120,minorversion=0,local_lock=none,addr=192.168.122.121 0 0

    # umount -v /mnt/nfs                   
    /mnt/nfs was not found in /proc/mounts
    /mnt/nfs was not found in /proc/mounts
    # 
    # fgrep /export /etc/mtab /proc/mounts    
    /etc/mtab:rhel6-nfs-server:/export/foosymlink /mnt/nfs nfs4         rw,addr=192.168.122.121,clientaddr=192.168.122.120 0 0
    /proc/mounts:rhel6-nfs-server:/export/foodir /mnt/nfs nfs4 rw,relatime,vers=4,rsize=65536,wsize=65536,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.120,minorversion=0,local_lock=none,addr=192.168.122.121 0 0

    # umount.nfs /mnt/nfs/ -v     <===== This is the only way that works 
    Could not find /mnt/nfs/ in mtab
    /mnt/nfs/ umounted
    # fgrep /export /etc/mtab /proc/mounts    
    /etc/mtab:rhel6-nfs-server:/export/foosymlink /mnt/nfs nfs4 rw,addr=192.168.122.121,clientaddr=192.168.122.120 0 0 <====mount         is gone, but still in /etc/mtab
    # df -h
    Filesystem            Size  Used Avail Use% Mounted on
    /dev/mapper/VolGroup-lv_root
                          6.5G  5.5G  642M  90% /
    tmpfs                 246M     0  246M   0% /dev/shm
    /dev/vda1             485M  110M  351M  24% /boot
    rhel6-nfs-server:/export/foosymlink
                          6.5G  5.5G  642M  90% /mnt/nfs <====  after unmounting, still its there.
  
Actual results:
umount fails to unmount the volume

Expected results:
umount succeeding

Additional info:
I've narrowed the problem to nfs-utils somewhere between -7 and -12.  Confirmed downgrade to -7 fixes the problem.  Kernel doesn't have anything to do with it - strictly a nfs-utils bug.

This should be fairly straightforward to track down.

* Mon Sep 19 2011 Steve Dickson <steved> 1.2.3-12
- Removed the stripping of debugging information from rpcdebug (bz 729001)

* Fri Sep 16 2011 Steve Dickson <steved> 1.2.3-11
- mount.nfs: Fixed problem in mount error verbosity patch (bz 731693)

* Thu Sep 15 2011 Steve Dickson <steved> 1.2.3-10
- mount.nfs: add error verbosity to invalid versions (bz 731693)

* Tue Sep 13 2011 Steve Dickson <steved> 1.2.3-9
- umount.nfs: Got IPV6 unmounts working again (bz 732673)
- mountd: return multiple hosts exporting the same directory (bz 726112)
- mount: Better error message for invalid version (bz 723780)

* Thu Aug 11 2011 Steve Dickson <steved> 1.2.3-8
- initscripts: just try to mount rpc_pipefs always (bz 692702)
- Rely on crypto module autoloading in init scripts
- svcgssd: Document "-n" for svcgssd (bz 697359)
- mount.nfs: anticipate RLIMIT_FSIZE (bz 697981)
- exportfs manpage: Ipv6 update (bz 715078)
- mountd: Stop segfault in mtab code (bz 723438)
- exportfs: wilcards in exports can lead to unintended mounts (bz 715391)
- umount: allow spaces in unmount paths (bz 702273)
- specfile: reordered how libgssglue is linked in (bz 720479)