Re: Busy inodes after umount

[Neil Brown]

On Tuesday July 31, [e-mail] wrote:
> On Thu, Jul 19, 2001 at 07:38:15PM -0500, Tad Dolphay wrote:
> > > > I've now been able to reproduce:
> > > >
> > > > * make a filesystem
> > > > * mount it
> > > > * export it (nfs)
> > > > * mount on remote machine
> > > > * lock file (fcntl)
> > > > * unexport
> > > > * unmount
> > > >
> > > > Then you get the VFS message about self-destruct. Tested with both ext2
> > > > and xfs.
> > > >
> > > > The lock is still present in /proc/locks after the umount.
> > > >
> > > > With ext2 I can remount the filesystem successfully, but with XFS I get
> > > > the message about duplicate UUIDs and the mount failes. I believe this is a totally
> > > > different problem from the one you were experiencing. (and blockdev doesn't help for me)
> > > >
> > > > I suppose this is a generic kernel bug?

Yep.  It is not filesystem specific.  
nfsd does not flush locks when a filesystem is un-exported, only when
a client is removed, and that actually never happens.
In fs/nfsd/lockd.c there is a comment:

/*
 * When removing an NFS client entry, notify lockd that it is gone.
 * FIXME: We should do the same when unexporting an NFS volume.
 */

That FIXME needs to be fixed.  I need to read through some more code
before I am sure how to do it, but it shouldn't be too hard.

NeilBrown