Re: [PATCH 0/4][RFC] NFSv3: implement extended attribute (XATTR) protocol

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

On Thu, Oct 08, 2009 at 09:19:13AM -0700, Sriram Ramkrishna wrote:
> On Sat, Sep 19, 2009 at 8:09 AM, James Morris <jmorris@namei.org> wrote:
> 
> >
> > Currently, the code is implemented only to support Linux namespace.name
> > xattrs in the "user" namespace.  It could be extended to support other
> > similar name/value pair xattr implementations (and not far from IRIX wire
> > compat), although that's not an aim of this version.  There may also be
> > some scope for limited support of system xattrs (e.g. 'dumb' security
> > label transport), although I've not looked beyond user.* so far.
> >
> >
> James this is great news.  I personally am interested (as a consumer) in
> setting up better ACL list (ala AFS) than the POSIX model we have now and
> trying to implement it using xattr might be the right way.  But my
> frustration of course was that everybody did xattr in different ways and no
> filesystem implementer wanted to go on a limb and implemented such things
> without a RFC.

Yes, we could allow applications on the client to access essentially
arbitrary filesystem-specific functionality.  However, this also would
allow applications to become dependent on particular features of the
exported filesystem.  There's some question whether we'd really want to
do that.

I assume that it was in order to avoid that question that this initial
implementation only exports the user.* namespace, since xattr's in that
name space are by design not given any special interpretation by the
filesystem--they just store and return opaque data.

--b.

> 
> 
> >
> > Note that I'll be giving a talk on this at LinuxCon on Thursday:
> > http://linuxcon.linuxfoundation.org/meetings/1589 So, in addition to
> > discussion here, please come along to the talk if you're at the conf, and
> > we may also be able to discuss it at Plumbers in one of the BoFs.
> >
> 
> 
> Ah, I was there, and I was asking around wanting to talk about the issue!
> Ah well.
> 
> sri