From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andreas Dilger <adilger@sun.com>
Subject: Re: [RFC] quota: 64-bit limits with vfs, updated
Date: Fri, 21 Mar 2008 09:04:03 +0800
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Cc: Jan Kara <jack@suse.cz>, linux-fsdevel@vger.kernel.org,
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On Mar 21, 2008  00:37 +0300, Andrew Perepechko wrote:
> +#define REV_ASSERT(r) BUG_ON((rev) != 0 && (rev) != 1)

Umm, "r" and "rev" are not consistent above...

Since this assertion is only on the in-memory quota structure, it would
probably be better to have something like

#define REV_R0  0x12340000
#define REV_R1  0x12340001

and when unpacking the on-disk revision number or it with REV_OFFSET and

#define REV_ASSERT(revno) BUG_ON((revno) != REV_R0 && (revno) != REV_R1)

That detects the common case of memory being zeroed for some reason.  It
will also easily detect if you aren't properly swabbing the revision
and unmasking the 0x1234000 from the in-memory structure.

Just a thought...  some people may not like this idea, but I dislike
using "0" as a magic number for anything.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.