xfs: Add caller function output to xfs_log_force tracepoint

I had sent this patch yesterday, but for some reason it didn't reach
xfs list, sending again.

Output the caller of xfs_log_force might be useful when tracing log
checkpoint problems without the need to build kernel with DEBUG.
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_log.c

@@ -3378,7 +3378,7 @@ xfs_log_force(
 {
 	int	error;
 
-	trace_xfs_log_force(mp, 0);
+	trace_xfs_log_force(mp, 0, _RET_IP_);
 	error = _xfs_log_force(mp, flags, NULL);
 	if (error)
 		xfs_warn(mp, "%s: error %d returned.", __func__, error);
@@ -3527,7 +3527,7 @@ xfs_log_force_lsn(
 {
 	int	error;
 
-	trace_xfs_log_force(mp, lsn);
+	trace_xfs_log_force(mp, lsn, _RET_IP_);
 	error = _xfs_log_force_lsn(mp, lsn, flags, NULL);
 	if (error)
 		xfs_warn(mp, "%s: error %d returned.", __func__, error);

fs/xfs/xfs_trace.h

@@ -1053,19 +1053,21 @@ DECLARE_EVENT_CLASS(xfs_log_item_class,
 )
 
 TRACE_EVENT(xfs_log_force,
-	TP_PROTO(struct xfs_mount *mp, xfs_lsn_t lsn),
-	TP_ARGS(mp, lsn),
+	TP_PROTO(struct xfs_mount *mp, xfs_lsn_t lsn, unsigned long caller_ip),
+	TP_ARGS(mp, lsn, caller_ip),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_lsn_t, lsn)
+		__field(unsigned long, caller_ip)
 	),
 	TP_fast_assign(
 		__entry->dev = mp->m_super->s_dev;
 		__entry->lsn = lsn;
+		__entry->caller_ip = caller_ip;
 	),
-	TP_printk("dev %d:%d lsn 0x%llx",
+	TP_printk("dev %d:%d lsn 0x%llx caller %ps",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
-		  __entry->lsn)
+		  __entry->lsn, (void *)__entry->caller_ip)
 )
 
 #define DEFINE_LOG_ITEM_EVENT(name) \