Date: Wed, 7 Dec 2011 12:11:33 -0500
From: "J. Bruce Fields" <bfields@fieldses.org>
To: Benny Halevy <bhalevy@tonian.com>
Cc: Tigran Mkrtchyan <kofemann@googlemail.com>, linux-nfs@vger.kernel.org,
        Tigran Mkrtchyan <kofemann@gmail.com>
Subject: Re: [PATCH] nfsd41: handle current stateid in open and close
Message-ID: <20111207171133.GD20079@fieldses.org>
References: <1323207847-19118-1-git-send-email-tigran.mkrtchyan@desy.de>
 <20111206230823.GH12640@fieldses.org>
 <4EDF677C.7030209@tonian.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
In-Reply-To: <4EDF677C.7030209@tonian.com>
Sender: linux-nfs-owner@vger.kernel.org

On Wed, Dec 07, 2011 at 03:17:48PM +0200, Benny Halevy wrote:
> On 2011-12-07 01:08, J. Bruce Fields wrote:
> > It's a little verbose, but yes it does nicely collect the current
> > stateid getting/setting into one place.  Benny, is the more or less what
> > you were thinking of?
> 
> Yes it is, though I also liked your direction of just using the current
> stateid for xdr decoding and encoding.

I'd still have a slight preference for doing it that way, just because
it would take fewer lines of code--but I can live with this too, so I'll
leave the choice to Tigran's excellent taste....

> { ~0, { { ~0, ~0 }, ~0 } } is ugly but compact :)
> 
> And the following may be an overkill...
> {
> 	.si_generation = ~0,
> 	.si_opaque = {
> 		.so_clid = {
> 			.cl_boot = ~0,
> 			.cl_id = ~0,
> 		},
> 		.so_id = ~0
> 	}
> };

Reminding myself of http://tools.ietf.org/html/rfc5661#section-8.2.3...
"Stateid values whose "other" field is either all zeros or all ones are
reserved."

Maybe:

#define all_ones   {{~0,~0 },~0}
#define all_zeroes {{ 0, 0 }, 0}
const stateid_t one_stateid = {
	.si_generation = ~0,
	.si_opaque = all_ones
};
const stateid_t current_stateid = {
	.si_generation = 1,
	.si_opaque = all_zeroes
};
...

Or you could ditch the all_zeroes; it's just there for some kind of
symmetry.

--b.