jbd2: Provide trace event for handle restarts

Provide trace event for handle restarts to ease debugging.

Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191105164437.32602-24-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/jbd2/transaction.c

@@ -747,6 +747,7 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, int revoke_records,
 	journal_t *journal;
 	tid_t		tid;
 	int		need_to_start;
+	int		ret;
 
 	/* If we've had an abort of any type, don't even think about
 	 * actually doing the restart! */
@@ -776,7 +777,12 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, int revoke_records,
 		DIV_ROUND_UP(revoke_records,
 			     journal->j_revoke_records_per_block);
 	handle->h_revoke_credits = revoke_records;
-	return start_this_handle(journal, handle, gfp_mask);
+	ret = start_this_handle(journal, handle, gfp_mask);
+	trace_jbd2_handle_restart(journal->j_fs_dev->bd_dev,
+				 ret ? 0 : handle->h_transaction->t_tid,
+				 handle->h_type, handle->h_line_no,
+				 handle->h_total_credits);
+	return ret;
 }
 EXPORT_SYMBOL(jbd2__journal_restart);
 

include/trace/events/jbd2.h

@@ -133,7 +133,7 @@ TRACE_EVENT(jbd2_submit_inode_data,
 		  (unsigned long) __entry->ino)
 );
 
-TRACE_EVENT(jbd2_handle_start,
+DECLARE_EVENT_CLASS(jbd2_handle_start_class,
 	TP_PROTO(dev_t dev, unsigned long tid, unsigned int type,
 		 unsigned int line_no, int requested_blocks),
 
@@ -161,6 +161,20 @@ TRACE_EVENT(jbd2_handle_start,
 		  __entry->type, __entry->line_no, __entry->requested_blocks)
 );
 
+DEFINE_EVENT(jbd2_handle_start_class, jbd2_handle_start,
+	TP_PROTO(dev_t dev, unsigned long tid, unsigned int type,
+		 unsigned int line_no, int requested_blocks),
+
+	TP_ARGS(dev, tid, type, line_no, requested_blocks)
+);
+
+DEFINE_EVENT(jbd2_handle_start_class, jbd2_handle_restart,
+	TP_PROTO(dev_t dev, unsigned long tid, unsigned int type,
+		 unsigned int line_no, int requested_blocks),
+
+	TP_ARGS(dev, tid, type, line_no, requested_blocks)
+);
+
 TRACE_EVENT(jbd2_handle_extend,
 	TP_PROTO(dev_t dev, unsigned long tid, unsigned int type,
 		 unsigned int line_no, int buffer_credits,