From: Arnd Bergmann <arnd@arndb.de>
To: Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH 06/14] Pramfs: Include files
Date: Sun, 14 Jun 2009 00:59:56 +0200
User-Agent: KMail/1.11.90 (Linux/2.6.30-8-generic; KDE/4.2.85; x86_64; ; )
Cc: Marco <marco.stornelli@gmail.com>,
       Linux FS Devel <linux-fsdevel@vger.kernel.org>,
       Linux Embedded <linux-embedded@vger.kernel.org>,
       Linux Kernel <linux-kernel@vger.kernel.org>,
       Daniel Walker <dwalker@soe.ucsc.edu>
References: <4A33A7EC.6070008@gmail.com> <20090613140459.GC30053@uranus.ravnborg.org>
In-Reply-To: <20090613140459.GC30053@uranus.ravnborg.org>
MIME-Version: 1.0
Content-Type: Text/Plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Message-Id: <200906140059.57362.arnd@arndb.de>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1191
Lines: 29

On Saturday 13 June 2009, Sam Ravnborg wrote:
> > +     union {
> > +             struct {
> > +                     /*
> > +                      * ptr to row block of 2D block pointer array,
> > +                      * file block #'s 0 to (blocksize/4)^2 - 1.
> > +                      */
> > +                     off_t row_block;
> 
> It is my understanding that we shall use: __kernel_off_t
> in exported headers.

That is a correct understanding in general, however this case is
different, because it describes an on-disk data structure,
not a kernel to user space interface. Here, __kernel_off_t is just
as wrong as off_t, because it will differ between 32 and 64 bit
architectures, making the fs layout incompatible. I'd suggest
simply defining this as __u64.

Moreover, file system layout should be described in terms of
big-endian or little-endian types (e.g. __be64 or __le64),
together with the right accessor functions.

	Arnd <><
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/