linux-kernel - Re: [PATCH #3] reiserfs: Fix permissions on .reiserfs

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Message-ID: <4BBE6F0C.6020207@suse.com>
Date:	Thu, 08 Apr 2010 20:04:28 -0400
From:	Jeff Mahoney <jeffm@...e.com>
To:	Matt McCutchen <matt@...tmccutchen.net>
Cc:	ReiserFS Mailing List <reiserfs-devel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Edward Shishkin <edward.shishkin@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH #3] reiserfs: Fix permissions on .reiserfs_priv

On 04/08/2010 06:39 PM, Matt McCutchen wrote:
> On Thu, 2010-04-08 at 23:38 +0200, Edward Shishkin wrote:
>> Jeff Mahoney wrote:
>>>  [...] This patch resolves the issue by properly hiding .reiserfs_priv. This
>>>  was the intent of the xattr poisoning code, but it appears to have
>>>  never worked as expected. This is fixed by using d_revalidate instead
>>>  of d_compare. [...]
> 
> The patch seems to rely on the fact that the priv_root dentry is stuck
> in the dcache for as long as the filesystem is mounted, so that attempts
> to follow ".reiserfs_priv" are guaranteed to match that dentry in the
> cache and be refused by xattr_hide_revalidate.  Is my understanding
> correct?
> 

Yes. The other half of it is that the priv_root dentry being stuck in
the dcache for as long as the flie system is mounted is a guaranteed
since REISERFS_SB(sb) holds a reference to it until reiserfs_kill_sb is
called.

-Jeff

-- 
Jeff Mahoney
SuSE Labs
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