From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Garzik <jeff@garzik.org>
Subject: Re: [RFC 0/13] extents and 48bit ext3
Date: Fri, 09 Jun 2006 13:50:03 -0400
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Cc: Andrew Morton <akpm@osdl.org>,
	ext2-devel <ext2-devel@lists.sourceforge.net>,
	linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>,
	cmm@us.ibm.com, linux-fsdevel@vger.kernel.org,
	Alex Tomas <alex@clusterfs.com>,
	Andreas Dilger <adilger@clusterfs.com>
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To: Matthew Wilcox <matthew@wil.cx>
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Matthew Wilcox wrote:
> On Fri, Jun 09, 2006 at 10:30:06AM -0700, Linus Torvalds wrote:
>> And I'm not saying that just because it's a filesystem, and people get 
>> upset if they lose data. No, I'm saying it because from a maintenance 
>> standpoint, such a filesystem has almost zero cost.
> 
> One of the costs (and I'm not disagreeing with your main point;
> I think forking ext3 to ext4 at this point is reasonable), is that
> bugfixes applied to one don't necessarily get applied to the other.
> I found some recently between ext2 and ext3, and submitted those, but I
> only audited one file.  There's lots more to look at and I just haven't
> found the time recently.  Going to three variations is a lot more work
> for auditing, and it might be worth splitting some bits which genuinely
> are the same into common code.

With extents and 48bit, you have multiple code paths to audit, regardless.

If applied to ext3, you have to audit

	fs/ext3/*.c:
		if (extents)
			...
		else
			...

as opposed to

	fs/ext3/*.c:
		...	non-extent code
	fs/ext4/*.c:
		...	extent code