GFS2: Log the reason for log flushes in every log header

This patch just adds the capability for GFS2 to track which function
called gfs2_log_flush. This should make it easier to diagnose
problems based on the sequence of events found in the journals.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/aops.c

@@ -448,7 +448,8 @@ static int gfs2_jdata_writepages(struct address_space *mapping,
 
 	ret = gfs2_write_cache_jdata(mapping, wbc);
 	if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
-		gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL);
+		gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
+			       GFS2_LFC_JDATA_WPAGES);
 		ret = gfs2_write_cache_jdata(mapping, wbc);
 	}
 	return ret;