[PATCH] Check for immutable flag in fallocate path

[Marco Stornelli]

2011/2/21 Christoph Hellwig <hch at infradead.org>:
> On Mon, Feb 21, 2011 at 09:26:32AM +0100, Marco Stornelli wrote:
>> From: Marco Stornelli <marco.stornelli at 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.
>
>

The check should be done after the fs got the inode mutex lock.

Marco