linux-kernel - Re: [PATCH] gfs2 endianness bug: be16 assigned to be32 field

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Message-ID: <Pine.LNX.4.64.0610141123580.3952@g5.osdl.org>
Date:	Sat, 14 Oct 2006 11:32:09 -0700 (PDT)
From:	Linus Torvalds <torvalds@...l.org>
To:	Al Viro <viro@....linux.org.uk>
cc:	swhiteho@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gfs2 endianness bug: be16 assigned to be32 field

On Sat, 14 Oct 2006, Al Viro wrote:
>
> -	leaf->lf_dirent_format = cpu_to_be16(GFS2_FORMAT_DE);
> +	leaf->lf_dirent_format = cpu_to_be32(GFS2_FORMAT_DE);

Hmm. Doesn't this change the on-disk format on a LE machine (eg x86)?

In other words, this change makes me nervous. A quick grep seems to 
indicate that nothing actually _uses_ this field, so maybe we don't really 
care, but I think we should double-check that this is what the GFS2 people 
really want.

If we don't want to change the format on a LE machine, then maybe the 
gfs2_leaf structure should be changed to be

	..
	__be16 lf_dirent_format;
	__be16 lf_unused;
	..

which should keep the bits in the same position on LE.

Regardless, the old code was clearly wrong, since it gives different 
on-disk format for a big-endian and a little-endian machine. Al's fix is 
proper, but perhaps people would prefer something that breaks the BE 
format rather than the LE format. Hmm?

Steven?

		Linus
-
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