From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Whitehouse <swhiteho@redhat.com>
Date: Wed, 09 Mar 2011 11:38:13 +0000
Subject: [Cluster-devel] GFS2: Remove potential race in flock code
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List-Id: <cluster-devel.redhat.com>
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This patch ensures that we always wait for glock demotion when
dropping flocks on a file in order to prevent any race
conditions associated with further flock calls or closing
the file.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 216ad27..2878481 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -981,8 +981,10 @@ static void do_unflock(struct file *file, struct file_lock *fl)
 
 	mutex_lock(&fp->f_fl_mutex);
 	flock_lock_file_wait(file, fl);
-	if (fl_gh->gh_gl)
-		gfs2_glock_dq_uninit(fl_gh);
+	if (fl_gh->gh_gl) {
+		gfs2_glock_dq_wait(fl_gh);
+		gfs2_holder_uninit(fl_gh);
+	}
 	mutex_unlock(&fp->f_fl_mutex);
 }