Re: Possible NFSv4 locking bug

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Mar 01, 2011 at 05:31:06PM -0500, Rick Koshi wrote:
> "J. Bruce Fields" writes:
> > On Mon, Feb 28, 2011 at 10:27:23AM -0500, Rick Koshi wrote:
> > > 
> > > I've found that when I lock an NFS-mounted file on a client, the server
> > > reserves an open file descriptor (as seen in /proc/sys/fs/file-nr).
> > 
> > So it looks like that's the total number of allocated struct file's
> > across the system?
> 
> That sounds about right.  To be honest, I'm not 100% sure exactly
> what that file reports.  But I do know that when it got that large,
> I stopped being able to open new files as any non-root user.  Running
> basic things like 'ls' gave me errors, as they were unable to open
> shared libraries to run.
> 
> If you like, you can read the post I originally submitted
> on serverfault.com, when I was trying to figure this out.
> It documents a lot of what I tried:
> 
>    http://serverfault.com/questions/235059/vfs-file-max-limit-1231582-reached

Yeah, this is an nfsv4-specific bug, and I can reproduce it easily by
e.g. running cthon -l in a loop on the client while monitoring file-nr
on the server.  I see the problem, but there's more than one thing to
fix there, so it needs more thought; I'll try to have a patch out by the
end of the day.

--b.