GFS2: Add origin indicator to glock demote tracing

This adds the origin indicator to the trace point for glock
demotion, so that it is possible to see where demote requests
have come from.

Note that requests generated from the demote_rq sysfs interface
will show as remote, since they are intended to replicate
exactly the effect of a demote reuqest from a remote node. It
is still possible to tell these apart by looking at the process
which initiated the demote request.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glock.c

@@ -926,7 +926,7 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 	}
 	if (gl->gl_ops->go_callback)
 		gl->gl_ops->go_callback(gl, remote);
-	trace_gfs2_demote_rq(gl);
+	trace_gfs2_demote_rq(gl, remote);
 }
 
 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)

fs/gfs2/trace_gfs2.h

@@ -159,9 +159,9 @@ TRACE_EVENT(gfs2_glock_put,
 /* Callback (local or remote) requesting lock demotion */
 TRACE_EVENT(gfs2_demote_rq,
 
-	TP_PROTO(const struct gfs2_glock *gl),
+	TP_PROTO(const struct gfs2_glock *gl, bool remote),
 
-	TP_ARGS(gl),
+	TP_ARGS(gl, remote),
 
 	TP_STRUCT__entry(
 		__field(        dev_t,  dev                     )
@@ -170,6 +170,7 @@ TRACE_EVENT(gfs2_demote_rq,
 		__field(	u8,	cur_state		)
 		__field(	u8,	dmt_state		)
 		__field(	unsigned long,	flags		)
+		__field(	bool,	remote			)
 	),
 
 	TP_fast_assign(
@@ -179,14 +180,16 @@ TRACE_EVENT(gfs2_demote_rq,
 		__entry->cur_state	= glock_trace_state(gl->gl_state);
 		__entry->dmt_state	= glock_trace_state(gl->gl_demote_state);
 		__entry->flags		= gl->gl_flags  | (gl->gl_object ? (1UL<<GLF_OBJECT) : 0);
+		__entry->remote		= remote;
 	),
 
-	TP_printk("%u,%u glock %d:%lld demote %s to %s flags:%s",
+	TP_printk("%u,%u glock %d:%lld demote %s to %s flags:%s %s",
 		  MAJOR(__entry->dev), MINOR(__entry->dev), __entry->gltype,
 		  (unsigned long long)__entry->glnum,
                   glock_trace_name(__entry->cur_state),
                   glock_trace_name(__entry->dmt_state),
-		  show_glock_flags(__entry->flags))
+		  show_glock_flags(__entry->flags),
+		  __entry->remote ? "remote" : "local")
 
 );