[RFC,PATCH 0/4] Dynamic Pseudo Root

[J. Bruce Fields]

On Fri, Dec 07, 2007 at 06:49:28PM -0500, Trond Myklebust wrote:
> 
> On Fri, 2007-12-07 at 14:57 -0800, Brent Callaghan wrote:
> > This seems like a very complicated way to implement a pseudo root.
> > 
> > Why not implement it the same way as Solaris does it ?
> > 
> > When a Solaris NFSv4 server gets a PUTROOTFH it returns the client
> > the real filehandle for the real system root.  In fact, all  
> > filesystems that
> > may provide a path to a real export are automatically exported, albeit
> > with some simple restrictions:
> > 	
> > 	o LOOKUPs succeed only for path components that lead to
> > 	   exported filesystems.
> > 
> > 	o READDIR shows only path components that lead to exported
> > 	   filesystems.
> > 
> > The pseudo filesystem is the same as the real filesystem, with
> > some restrictions.
> 
> 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.

--b.