Re: server mountpoint busy after unexporting nfs4 share

[Martin Hicks <mort@bork.org>]

On Wed, Aug 21, 2013 at 7:27 AM, J. Bruce Fields <bfields@fieldses.org> wrote:
> On Wed, Aug 21, 2013 at 12:43:43PM +1000, NeilBrown wrote:
>> On Fri, 16 Aug 2013 17:12:18 -0400 "J. Bruce Fields" <bfields@fieldses.org>
>> wrote:
>>
>> > On Thu, Aug 15, 2013 at 12:04:33PM -0400, Martin Hicks wrote:
>> > > I'm wondering if I'm missing something or if this is a bug.
>> > >
>> > > A NFS4 export has active clients.  The mount is removed from
>> > > /etc/exports and 'exportfs -r' is run.  Clients immediately start
>> > > getting 'Stale file handle' errors, but the mountpoint is still busy
>> > > and cannot be unmounted.  Killing off nfsd solves the problem, but is
>> > > undesirable for obvious reasons.
>> > >
>> > > On debian linux, kernel version 3.10-2-amd64,  with nfs-utils 1.2.8.
>> >
>> > Yeah, the clients may hold opens or locks on the filesystem and those
>> > don't get removed on exports -r.
>> >
>> > For now shutting down the server is the only solution.
>>
>> How far does:
>>   echo /path/to/export > /proc/fs/nfsd/unlock_filesystem
>> get you? Or does that just drop 'lockd' locks and not NFSv4 locks?
>
> Right, it just does lockd locks.  It should also do NFSv4 locks, opens,
> and delegations.  Happy if somebody wants to finish that job off--it
> probably wouldn't be too hard?  Although there may be a bit of work to
> get the error returns right in the v4 case--I think we'd want to keep
> the relevant stateid's around and return NFS4ERR_ADMIN_REVOKED when a
> client continues to use them.

I don't have the bandwidth to take this on right now, but I may in the future.
Thanks for your help,
mh

-- 
Martin Hicks P.Eng.      |         mort@bork.org
Bork Consulting Inc.     |   +1 (613) 266-2296