linux-kernel - Re: [PATCH 00/23] per device dirty throttling -v8

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Message-ID: <87r6miza5t.fsf@mid.deneb.enyo.de>
Date:	Sun, 05 Aug 2007 09:57:02 +0200
From:	Florian Weimer <fw@...eb.enyo.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, miklos@...redi.hu, neilb@...e.de,
	dgc@....com, tomoki.sekiyama.qu@...achi.com, nikita@...sterfs.com,
	trond.myklebust@....uio.no, yingchao.zhou@...il.com,
	richard@....demon.co.uk
Subject: Re: [PATCH 00/23] per device dirty throttling -v8

* Andrew Morton:

>>  XFS overwrites that data with zeros upon reboot, which tends to
>> irritate users when it happens.
>
> yup.
>
>> >From this point of view, data=ordered doesn't seem too bad.
>
> If your computer is used by multiple users who don't trust each other,
> sure.  That covers, what?  About 2% of machines?

I wasn't concerned so much with security, but with user experience.
For instance, some editors don't perform fsync-then-rename, but simply
truncate the file when saving (because they want to preserve hard
links).  With XFS, this tends to cause null bytes on crashes.  Since
ext3 has got a much larger install base, this would result in lots of
bug reports, I fear.

Without zeroing, the truncating editor might garble the file in a more
obvious way, but you've got the security issue (and I agree that this
is more of a PR issue).
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