ocfs2: Add ocfs2_trace.h.

About one year ago, Wengang Wang tried some first steps
to add tracepoints to ocfs2. Hiss original patch is here:
http://oss.oracle.com/pipermail/ocfs2-devel/2009-November/005512.html

But as Steven Rostedt indicated in his article
http://lwn.net/Articles/383362/, we'd better have our trace
files resides in fs/ocfs2, so I rewrited the patch using the
method Steven mentioned in that article.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>

fs/ocfs2/ocfs2_trace.h

+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM ocfs2
+
+#if !defined(_TRACE_OCFS2_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_OCFS2_H
+
+#include <linux/tracepoint.h>
+
+
+#endif /* _TRACE_OCFS2_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE ocfs2_trace
+#include <trace/define_trace.h>

fs/ocfs2/super.c

@@ -42,6 +42,9 @@
 #include <linux/seq_file.h>
 #include <linux/quotaops.h>
 
+#define CREATE_TRACE_POINTS
+#include "ocfs2_trace.h"
+
 #define MLOG_MASK_PREFIX ML_SUPER
 #include <cluster/masklog.h>