GFS2: Display nobarrier option in /proc/mounts

Since the default is barriers on, this only displays the
nobarrier option when that is active.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 5e4b314..c282ad4 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1336,6 +1336,9 @@
 		}
 		seq_printf(s, ",errors=%s", state);
 	}
+	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags))
+		seq_printf(s, ",nobarrier");
+
 	return 0;
 }