linux-kernel - Re: O_DIRECT question

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Date:	Sun, 14 Jan 2007 20:39:50 +0100
From:	Bodo Eggert <7eggert@....de>
To:	Bill Davidsen <davidsen@....com>, Michael Tokarev <mjt@....msk.ru>,
	Chris Mason <chris.mason@...cle.com>,
	dean gaudet <dean@...tic.org>, Viktor <vvp01@...ox.ru>,
	Aubrey <aubreylee@...il.com>, Hua Zhong <hzhong@...il.com>,
	Hugh Dickins <hugh@...itas.com>, linux-kernel@...r.kernel.org,
	hch@...radead.org, kenneth.w.chen@...el.com, akpm@...l.org
Subject: Re: O_DIRECT question

Bill Davidsen <davidsen@....com> wrote:

> My point is, that there is code to handle sparse data now, without
> O_DIRECT involved, and if O_DIRECT bypasses that, it's not a problem
> with the idea of O_DIRECT, the kernel has a security problem.

The idea of O_DIRECT is to bypass the pagecache, and the pagecache is what
provides the security against reading someone else's data using sparse
files or partial-block-IO.
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