bcachefs: Improve trace_trans_restart_too_many_iters()

We now include the list of paths in use.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -1492,6 +1492,22 @@ static void bch2_trans_update_max_paths(struct btree_trans *trans)
 	trans->nr_max_paths = hweight64(trans->paths_allocated);
 }
 
+noinline __cold
+int __bch2_btree_trans_too_many_iters(struct btree_trans *trans)
+{
+	if (trace_trans_restart_too_many_iters_enabled()) {
+		struct printbuf buf = PRINTBUF;
+
+		bch2_trans_paths_to_text(&buf, trans);
+		trace_trans_restart_too_many_iters(trans, _THIS_IP_, buf.buf);
+		printbuf_exit(&buf);
+	}
+
+	count_event(trans->c, trans_restart_too_many_iters);
+
+	return btree_trans_restart(trans, BCH_ERR_transaction_restart_too_many_iters);
+}
+
 static noinline void btree_path_overflow(struct btree_trans *trans)
 {
 	bch2_dump_trans_paths_updates(trans);

fs/bcachefs/btree_iter.h

@@ -627,12 +627,12 @@ static inline struct bkey_s_c bch2_btree_iter_peek_upto_type(struct btree_iter *
 	return bch2_btree_iter_peek_slot(iter);
 }
 
+int __bch2_btree_trans_too_many_iters(struct btree_trans *);
+
 static inline int btree_trans_too_many_iters(struct btree_trans *trans)
 {
-	if (hweight64(trans->paths_allocated) > BTREE_ITER_MAX - 8) {
-		trace_and_count(trans->c, trans_restart_too_many_iters, trans, _THIS_IP_);
-		return btree_trans_restart(trans, BCH_ERR_transaction_restart_too_many_iters);
-	}
+	if (hweight64(trans->paths_allocated) > BTREE_ITER_MAX - 8)
+		return __bch2_btree_trans_too_many_iters(trans);
 
 	return 0;
 }

fs/bcachefs/trace.h

@@ -32,7 +32,7 @@ DECLARE_EVENT_CLASS(bpos,
 	TP_printk("%llu:%llu:%u", __entry->p_inode, __entry->p_offset, __entry->p_snapshot)
 );
 
-DECLARE_EVENT_CLASS(str,
+DECLARE_EVENT_CLASS(fs_str,
 	TP_PROTO(struct bch_fs *c, const char *str),
 	TP_ARGS(c, str),
 
@@ -49,6 +49,29 @@ DECLARE_EVENT_CLASS(str,
 	TP_printk("%d,%d %s", MAJOR(__entry->dev), MINOR(__entry->dev), __get_str(str))
 );
 
+DECLARE_EVENT_CLASS(trans_str,
+	TP_PROTO(struct btree_trans *trans, unsigned long caller_ip, const char *str),
+	TP_ARGS(trans, caller_ip, str),
+
+	TP_STRUCT__entry(
+		__field(dev_t,		dev			)
+		__array(char,		trans_fn, 32		)
+		__field(unsigned long,	caller_ip		)
+		__string(str,		str			)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= trans->c->dev;
+		strscpy(__entry->trans_fn, trans->fn, sizeof(__entry->trans_fn));
+		__entry->caller_ip		= caller_ip;
+		__assign_str(str, str);
+	),
+
+	TP_printk("%d,%d %s %pS %s",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->trans_fn, (void *) __entry->caller_ip, __get_str(str))
+);
+
 DECLARE_EVENT_CLASS(btree_node,
 	TP_PROTO(struct bch_fs *c, struct btree *b),
 	TP_ARGS(c, b),
@@ -738,22 +761,22 @@ TRACE_EVENT(bucket_evacuate,
 		  __entry->dev_idx, __entry->bucket)
 );
 
-DEFINE_EVENT(str, move_extent,
+DEFINE_EVENT(fs_str, move_extent,
 	TP_PROTO(struct bch_fs *c, const char *k),
 	TP_ARGS(c, k)
 );
 
-DEFINE_EVENT(str, move_extent_read,
+DEFINE_EVENT(fs_str, move_extent_read,
 	TP_PROTO(struct bch_fs *c, const char *k),
 	TP_ARGS(c, k)
 );
 
-DEFINE_EVENT(str, move_extent_write,
+DEFINE_EVENT(fs_str, move_extent_write,
 	TP_PROTO(struct bch_fs *c, const char *k),
 	TP_ARGS(c, k)
 );
 
-DEFINE_EVENT(str, move_extent_finish,
+DEFINE_EVENT(fs_str, move_extent_finish,
 	TP_PROTO(struct bch_fs *c, const char *k),
 	TP_ARGS(c, k)
 );
@@ -775,7 +798,7 @@ TRACE_EVENT(move_extent_fail,
 	TP_printk("%d:%d %s", MAJOR(__entry->dev), MINOR(__entry->dev), __get_str(msg))
 );
 
-DEFINE_EVENT(str, move_extent_start_fail,
+DEFINE_EVENT(fs_str, move_extent_start_fail,
 	TP_PROTO(struct bch_fs *c, const char *str),
 	TP_ARGS(c, str)
 );
@@ -1008,10 +1031,11 @@ DEFINE_EVENT(transaction_event,	trans_restart_key_cache_raced,
 	TP_ARGS(trans, caller_ip)
 );
 
-DEFINE_EVENT(transaction_event,	trans_restart_too_many_iters,
+DEFINE_EVENT(trans_str, trans_restart_too_many_iters,
 	TP_PROTO(struct btree_trans *trans,
-		 unsigned long caller_ip),
-	TP_ARGS(trans, caller_ip)
+		 unsigned long caller_ip,
+		 const char *paths),
+	TP_ARGS(trans, caller_ip, paths)
 );
 
 DECLARE_EVENT_CLASS(transaction_restart_iter,
@@ -1368,12 +1392,12 @@ TRACE_EVENT(write_buffer_flush_slowpath,
 	TP_printk("%zu/%zu", __entry->slowpath, __entry->total)
 );
 
-DEFINE_EVENT(str, rebalance_extent,
+DEFINE_EVENT(fs_str, rebalance_extent,
 	TP_PROTO(struct bch_fs *c, const char *str),
 	TP_ARGS(c, str)
 );
 
-DEFINE_EVENT(str, data_update,
+DEFINE_EVENT(fs_str, data_update,
 	TP_PROTO(struct bch_fs *c, const char *str),
 	TP_ARGS(c, str)
 );