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From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Dave Jones <davej@redhat.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	xfs@oss.sgi.com
Subject: Re: fs/attr.c:notify_change locking warning.
Date: Wed, 16 Oct 2013 11:12:34 -0700	[thread overview]
Message-ID: <20131016181234.GA26646@infradead.org> (raw)
In-Reply-To: <20131016102651.GF4446@dastard>

On Wed, Oct 16, 2013 at 09:26:51PM +1100, Dave Chinner wrote:
> The killpriv calls? I couldn't find anything that implemented those
> security hooks nor any documentation about it, so I'm pretty much
> clueless about it. FWIW, ocfs2 doesn't implement them, either....

The killpriv code ends up doing xattr calls for per-file capabilities
(grep security/commoncap.c for killpriv).  Seems like ocfs2 is buggy in
that regard.

I suspect the easiest way to solve it properly in XFS is to simply
retake the iolock exclusive and get the i_mutex as part of it.  This
means direct I/O writes to files with the suid bit won't scale, but I
think we can live with that given that it avoids introducing special
cases that impact more code.

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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Dave Jones <davej@redhat.com>,
	xfs@oss.sgi.com, Linux Kernel <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: fs/attr.c:notify_change locking warning.
Date: Wed, 16 Oct 2013 11:12:34 -0700	[thread overview]
Message-ID: <20131016181234.GA26646@infradead.org> (raw)
In-Reply-To: <20131016102651.GF4446@dastard>

On Wed, Oct 16, 2013 at 09:26:51PM +1100, Dave Chinner wrote:
> The killpriv calls? I couldn't find anything that implemented those
> security hooks nor any documentation about it, so I'm pretty much
> clueless about it. FWIW, ocfs2 doesn't implement them, either....

The killpriv code ends up doing xattr calls for per-file capabilities
(grep security/commoncap.c for killpriv).  Seems like ocfs2 is buggy in
that regard.

I suspect the easiest way to solve it properly in XFS is to simply
retake the iolock exclusive and get the i_mutex as part of it.  This
means direct I/O writes to files with the suid bit won't scale, but I
think we can live with that given that it avoids introducing special
cases that impact more code.


  reply	other threads:[~2013-10-16 18:12 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-05  0:52 fs/attr.c:notify_change locking warning Dave Jones
2013-10-05  0:52 ` Dave Jones
2013-10-05  3:19 ` Dave Chinner
2013-10-05  3:19   ` Dave Chinner
2013-10-15 20:19   ` Christoph Hellwig
2013-10-15 20:19     ` Christoph Hellwig
2013-10-15 21:36     ` Dave Chinner
2013-10-15 21:36       ` Dave Chinner
2013-10-16  7:05       ` Christoph Hellwig
2013-10-16  7:05         ` Christoph Hellwig
2013-10-16 10:26         ` Dave Chinner
2013-10-16 10:26           ` Dave Chinner
2013-10-16 18:12           ` Christoph Hellwig [this message]
2013-10-16 18:12             ` Christoph Hellwig

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