Re: [PATCH] NFSv4: Change the default setting of the nfs4_disable_idmapping parameter

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

On Thu, Mar 22, 2012 at 08:53:25PM +0000, Myklebust, Trond wrote:
> On Thu, 2012-03-22 at 16:47 -0400, J. Bruce Fields wrote:
> > By the way, I finally got around to looking at the server side.
> > 
> > We don't have any way to negotiate with the client--we don't get an
> > error back if the name we return in a getattr reply isn't one the client
> > likes--so I don't think I can default the new behavior to "on" without
> > breaking existing setups.
> > 
> > Other than that I think I'll just copy the client, module parameter and
> > all.  That allows us to do the numeric case in-kernel and avoid
> > polluting our mapping cache with lots of "obvious" 123<->"123" mappings.
> > 
> > (OK, maybe I shouldn't copy the same parameter name, though--even if it
> > works it might be confusing.)
> 
> Does the idmapper do the right thing for numeric ids these days? If the
> older clients are running a newer idmapper that can deal with numeric
> ids, then even the legacy clients should be able to work cleanly.

If at all possible I really don't want to break clients, even if they
have an easy fix.  (Or maybe I wasn't understanding what you were
suggesting.)

> Otherwise, there is also the alternative of making the whole thing a
> per-client export option...

Hm, maybe that'd be better.

We're currently mapping names to id's when we decode the xdr--before
we've looked up the export--but that's fixable.

--b.