[Linux-cachefs] Adventures in NFS re-exporting

[Trond Myklebust]

On Thu, 2020-12-03 at 17:45 -0500, bfields at fieldses.org wrote:
> On Thu, Dec 03, 2020 at 09:34:26PM +0000, Trond Myklebust wrote:
> > I've been wanting such a function for quite a while anyway in order
> > to
> > allow the client to detect state leaks (either due to soft
> > timeouts, or
> > due to reordered close/open operations).
> 
> One sure way to fix any state leaks is to reboot the server.  The
> server
> throws everything away, the clients reclaim, all that's left is stuff
> they still actually care about.
> 
> It's very disruptive.
> 
> But you could do a limited version of that: the server throws away
> the
> state from one client (keeping the underlying locks on the exported
> filesystem), lets the client go through its normal reclaim process,
> at
> the end of that throws away anything that wasn't reclaimed.  The only
> delay is to anyone trying to acquire new locks that conflict with
> that
> set of locks, and only for as long as it takes for the one client to
> reclaim.

One could do that, but that requires the existence of a quiescent
period where the client holds no state at all on the server. There are
definitely cases where that is not an option.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust at hammerspace.com