From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] Check for immutable flag in fallocate path
Date: Mon, 21 Feb 2011 07:46:35 -0500
Message-ID: <20110221124635.GA5525@infradead.org>
References: <4D6221B8.9040303@gmail.com>
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Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
	cluster-devel@redhat.com,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org,
	xfs@oss.sgi.com
To: Marco Stornelli <marco.stornelli@gmail.com>
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On Mon, Feb 21, 2011 at 09:26:32AM +0100, Marco Stornelli wrote:
> From: Marco Stornelli <marco.stornelli@gmail.com>
> 
> All fs must check for the immutable flag in their fallocate callback.
> It's possible to have a race condition in this scenario: an application
> open a file in read/write and it does something, meanwhile root set the
> immutable flag on the file, the application at that point can call
> fallocate with success. Only Ocfs2 check for the immutable flag at the
> moment.

Please add the check in fs/open.c:do_fallocate() so that it covers all
filesystems.