xfs: add tracing to high level transaction operations

Because currently we have no idea what the transaction context we
are operating in is, and I need to know that information to track
down bugs in multiple log item joins to transactions.
Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_log_cil.c

@@ -1013,6 +1013,7 @@ xfs_log_commit_cil(
 		*commit_lsn = xc_commit_lsn;
 
 	xfs_log_done(mp, tp->t_ticket, NULL, regrant);
+	tp->t_ticket = NULL;
 	xfs_trans_unreserve_and_mod_sb(tp);
 
 	/*

fs/xfs/xfs_trace.h

@@ -3351,6 +3351,43 @@ TRACE_EVENT(xfs_trans_resv_calc,
 		  __entry->logflags)
 );
 
+DECLARE_EVENT_CLASS(xfs_trans_class,
+	TP_PROTO(struct xfs_trans *tp, unsigned long caller_ip),
+	TP_ARGS(tp, caller_ip),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(uint32_t, tid)
+		__field(uint32_t, flags)
+		__field(unsigned long, caller_ip)
+	),
+	TP_fast_assign(
+		__entry->dev = tp->t_mountp->m_super->s_dev;
+		__entry->tid = 0;
+		if (tp->t_ticket)
+			__entry->tid = tp->t_ticket->t_tid;
+		__entry->flags = tp->t_flags;
+		__entry->caller_ip = caller_ip;
+	),
+	TP_printk("dev %d:%d trans %x flags 0x%x caller %pS",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->tid,
+		  __entry->flags,
+		  (char *)__entry->caller_ip)
+)
+
+#define DEFINE_TRANS_EVENT(name) \
+DEFINE_EVENT(xfs_trans_class, name, \
+	TP_PROTO(struct xfs_trans *tp, unsigned long caller_ip), \
+	TP_ARGS(tp, caller_ip))
+DEFINE_TRANS_EVENT(xfs_trans_alloc);
+DEFINE_TRANS_EVENT(xfs_trans_cancel);
+DEFINE_TRANS_EVENT(xfs_trans_commit);
+DEFINE_TRANS_EVENT(xfs_trans_dup);
+DEFINE_TRANS_EVENT(xfs_trans_free);
+DEFINE_TRANS_EVENT(xfs_trans_roll);
+DEFINE_TRANS_EVENT(xfs_trans_add_item);
+DEFINE_TRANS_EVENT(xfs_trans_free_items);
+
 #endif /* _TRACE_XFS_H */
 
 #undef TRACE_INCLUDE_PATH

fs/xfs/xfs_trans.c

@@ -80,6 +80,7 @@ xfs_trans_free(
 	xfs_extent_busy_sort(&tp->t_busy);
 	xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false);
 
+	trace_xfs_trans_free(tp, _RET_IP_);
 	atomic_dec(&tp->t_mountp->m_active_trans);
 	if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT))
 		sb_end_intwrite(tp->t_mountp->m_super);
@@ -101,6 +102,8 @@ xfs_trans_dup(
 {
 	struct xfs_trans	*ntp;
 
+	trace_xfs_trans_dup(tp, _RET_IP_);
+
 	ntp = kmem_zone_zalloc(xfs_trans_zone, KM_SLEEP);
 
 	/*
@@ -285,6 +288,8 @@ xfs_trans_alloc(
 		return error;
 	}
 
+	trace_xfs_trans_alloc(tp, _RET_IP_);
+
 	*tpp = tp;
 	return 0;
 }
@@ -751,6 +756,8 @@ xfs_trans_add_item(
 	list_add_tail(&lidp->lid_trans, &tp->t_items);
 
 	lip->li_desc = lidp;
+
+	trace_xfs_trans_add_item(tp, _RET_IP_);
 }
 
 STATIC void
@@ -784,6 +791,8 @@ xfs_trans_free_items(
 {
 	struct xfs_log_item_desc *lidp, *next;
 
+	trace_xfs_trans_free_items(tp, _RET_IP_);
+
 	list_for_each_entry_safe(lidp, next, &tp->t_items, lid_trans) {
 		struct xfs_log_item	*lip = lidp->lid_item;
 
@@ -941,6 +950,8 @@ __xfs_trans_commit(
 	ASSERT(!tp->t_agfl_dfops ||
 	       !xfs_defer_has_unfinished_work(tp->t_agfl_dfops) || regrant);
 
+	trace_xfs_trans_commit(tp, _RET_IP_);
+
 	/*
 	 * If there is nothing to be logged by the transaction,
 	 * then unlock all of the items associated with the
@@ -996,6 +1007,7 @@ __xfs_trans_commit(
 		commit_lsn = xfs_log_done(mp, tp->t_ticket, NULL, regrant);
 		if (commit_lsn == -1 && !error)
 			error = -EIO;
+		tp->t_ticket = NULL;
 	}
 	current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
 	xfs_trans_free_items(tp, NULLCOMMITLSN, !!error);
@@ -1027,6 +1039,8 @@ xfs_trans_cancel(
 	struct xfs_mount	*mp = tp->t_mountp;
 	bool			dirty = (tp->t_flags & XFS_TRANS_DIRTY);
 
+	trace_xfs_trans_cancel(tp, _RET_IP_);
+
 	/*
 	 * See if the caller is relying on us to shut down the
 	 * filesystem.  This happens in paths where we detect
@@ -1047,8 +1061,10 @@ xfs_trans_cancel(
 	xfs_trans_unreserve_and_mod_sb(tp);
 	xfs_trans_unreserve_and_mod_dquots(tp);
 
-	if (tp->t_ticket)
+	if (tp->t_ticket) {
 		xfs_log_done(mp, tp->t_ticket, NULL, false);
+		tp->t_ticket = NULL;
+	}
 
 	/* mark this thread as no longer being in a transaction */
 	current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
@@ -1072,6 +1088,8 @@ xfs_trans_roll(
 	struct xfs_trans_res	tres;
 	int			error;
 
+	trace_xfs_trans_roll(trans, _RET_IP_);
+
 	/*
 	 * Copy the critical parameters from one trans to the next.
 	 */