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Date: Thu, 19 Jul 2007 07:33:02 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
       Andy Whitcroft <apw@shadowen.org>, Paul Mackerras <paulus@samba.org>,
       "James E.J. Bottomley" <James.Bottomley@SteelEye.com>,
       Alessandro Rubini <rubini@vision.unipv.it>, linuxppc-dev@ozlabs.org,
       linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
       Geoff Levand <geoffrey.levand@am.sony.com>
Subject: Re: [patch 1/3] ps3: Disk Storage Driver
Message-ID: <20070719053302.GO11657@kernel.dk>
References: <20070716161539.075822000@pademelon.sonytel.be> <20070716162206.392129000@pademelon.sonytel.be> <20070718163637.3f0e0164.akpm@linux-foundation.org>
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On Wed, Jul 18 2007, Andrew Morton wrote:
> On Mon, 16 Jul 2007 18:15:40 +0200
> Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> wrote:
> 
> > From: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
> > 
> > Add a Disk Storage Driver for the PS3:
> 
> Your patchset significantly hits powerpc, scsi and block.  So who gets to
> merge this?  Jens?  James?  Paul?
> 
> Me, I guess ;)

I think Paul was going to take it, or at least Geert hinted as such.

> > +#define PS3DISK_MAX_DISKS	16
> > +#define PS3DISK_MINORS		16
> > +
> > +#define KERNEL_SECTOR_SIZE	512
> 
> Sigh.  We have at least ten separate definitions of SECTOR_SIZE< none of
> them in the right place.  Cleanup opportunity for someone.

Indeed, it's universally 512 or << 9, just use that...

> > +#ifdef DEBUG
> > +	unsigned int n = 0;
> > +	struct bio *bio;
> > +	rq_for_each_bio(bio, req)
> > +		n++;
> 
> I'm surprised that the block core doesn't have a helper to count the number
> of bios in a request.

What would be the point of such a helper? I've never seen a need for it.
Geert uses it as debug code here, but the fact is that the number of
bios in a request is a pretty pointless number. It doesn't tell you
anything. There's no 1:1 mapping between bios and segments (or anything
else for that matter), so the exercise is purely pointless.

-- 
Jens Axboe