Re: [PATCH -V7 21/26] richacl: xattr mapping functions

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

On Thu, Oct 20, 2011 at 02:00:02PM +0530, Aneesh Kumar K.V wrote:
> On Wed, 19 Oct 2011 18:20:21 -0400, "J. Bruce Fields" <bfields@fieldses.org> wrote:
> > On Tue, Oct 18, 2011 at 09:02:56PM +0530, Aneesh Kumar K.V wrote:
> > > +#define RICHACL_XATTR "system.richacl"
> > > +
> > > +struct richace_xattr {
> > > +	__le16		e_type;
> > > +	__le16		e_flags;
> > > +	__le32		e_mask;
> > > +	__le32		e_id;
> > > +	char		e_who[0];
> > > +};
> > 
> > Does it really make sense to use a string here just to pick between the
> > three choices OWNER@, GROUP@, and EVERYONE@?  Why not just another small
> > integer?  Is the goal to expand this somehow eventually?
> 
> I guess Andreas wanted the disk layout to be able to store user@domain
> format if needed.

Is that likely?  For that to be useful, tasks would need to be able to
run as user@domain strings.  And we'd probably want owners and groups to
also be user@domain strings.

The container people seem to eventually want to add some kind of
namespace identifier everywhere:

	http://marc.info/?l=linux-kernel&m=131836778427871&w=2

in which case I guess we'd likely end up with (uid, user namespace id)
instead of user@domain?

I suppose the variable-length string field could store that too.

I don't hate the idea, it would make life easier for the NFS server.

--b.

> That should make the layout flexible enough so that
> we won't have to add another xattr later.