[Linux-cachefs] Adventures in NFS re-exporting

[Frank Filz]

> On Thu, Dec 03, 2020 at 10:53:26PM +0000, Trond Myklebust wrote:
> > 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.
> 
> No, as I said, the client performs reboot recovery for any state that it holds
> when we do this.

Yea, but the original sever goes through a period where it has dropped all state and isn't in grace, and if it's coordinating with non-NFS users, they don't know anything about grace anyway.

Frank