From: Abhijith Das <adas@redhat.com>
Date: Wed, 19 Dec 2012 15:48:01 +0000 (-0500)
Subject: GFS2: Fix race in gfs2_rs_alloc
X-Git-Tag: v3.8-rc3~27^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1213cacc7ffc7d4cdef3692f22b28a2df3216f5;p=pandora-kernel.git

GFS2: Fix race in gfs2_rs_alloc

QE aio tests uncovered a race condition in gfs2_rs_alloc where it's possible
to come out of the function with a valid ip->i_res allocation but it gets
freed before use resulting in a NULL ptr dereference.

This patch envelopes the initial short-circuit check for non-NULL ip->i_res
into the mutex lock. With this patch, I was able to successfully run the
reproducer test multiple times.

Resolves: rhbz#878476
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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