[RFC,PATCH 0/4] Dynamic Pseudo Root

[J. Bruce Fields]

On Fri, Dec 07, 2007 at 07:18:39PM -0500, Trond Myklebust wrote:
> 
> On Fri, 2007-12-07 at 19:08 -0500, J. Bruce Fields wrote:
> > On Fri, Dec 07, 2007 at 06:49:28PM -0500, Trond Myklebust wrote:
> > > Agreed. You are almost forced to do something like this if you want the
> > > filehandles to remain valid when the administrator changes the export
> > > options to allow access to path components that were previously part of
> > > the pseudo-fs. Otherwise, you have to use volatile filehandles, which
> > > are poorly supported by existing clients.
> > 
> > I agree.  On the other hand, this will normally only happen during the
> > initial lookup of a mountpoint (on mount, or maybe on
> > migration/failover).  Which I think is the simplest volatile-filehandle
> > case for a client to handle.
> 
> I can easily construct situations where this is not the case. Imagine if
> I export
> 
> /foo/bar
> 
> and the administrator on the NFSv4 client decides, for some reason or
> another, to mount '/'.

Yeah, I'm assuming people only mount "real" exported filesystems.  But
since the v4 protocol allows it, OK, it's probably not fair to assume we
can get away with second-class support for it.

> When I change the export to '/foo' or '/', then the filehandle for
> 'foo', which is not a mountpoint on the client, may change.

This is still pretty easy to recover from, isn't it?  But, OK, more
annoying than during the initial lookup on mount.

--b.