bcachefs: bch2_trans_node_add no longer uses trans_for_each_path()

In the future we'll be making trans->paths resizable and potentially
having _many_ more paths (for fsck); we need to start fixing algorithms
that walk each path in a transaction where possible.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -674,14 +674,22 @@ static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, str
  * A btree node is being replaced - update the iterator to point to the new
  * node:
  */
-void bch2_trans_node_add(struct btree_trans *trans, struct btree *b)
+void bch2_trans_node_add(struct btree_trans *trans,
+			 struct btree_path *path,
+			 struct btree *b)
 {
-	struct btree_path *path;
+	struct btree_path *prev;
 
-	trans_for_each_path(trans, path)
-		if (path->uptodate == BTREE_ITER_UPTODATE &&
-		    !path->cached &&
-		    btree_path_pos_in_node(path, b)) {
+	BUG_ON(!btree_path_pos_in_node(path, b));
+
+	while ((prev = prev_btree_path(trans, path)) &&
+	       btree_path_pos_in_node(prev, b))
+		path = prev;
+
+	for (;
+	     path && btree_path_pos_in_node(path, b);
+	     path = next_btree_path(trans, path))
+		if (path->uptodate == BTREE_ITER_UPTODATE && !path->cached) {
 			enum btree_node_locked_type t =
 				btree_lock_want(path, b->c.level);
 

fs/bcachefs/btree_iter.h

@@ -322,7 +322,7 @@ static inline void bch2_btree_path_downgrade(struct btree_trans *trans,
 
 void bch2_trans_downgrade(struct btree_trans *);
 
-void bch2_trans_node_add(struct btree_trans *trans, struct btree *);
+void bch2_trans_node_add(struct btree_trans *trans, struct btree_path *, struct btree *);
 void bch2_trans_node_reinit_iter(struct btree_trans *, struct btree *);
 
 int __must_check __bch2_btree_iter_traverse(struct btree_iter *iter);

fs/bcachefs/btree_update_interior.c

@@ -1601,10 +1601,10 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans,
 	bch2_btree_node_free_inmem(trans, path, b);
 
 	if (n3)
-		bch2_trans_node_add(trans, n3);
+		bch2_trans_node_add(trans, path, n3);
 	if (n2)
-		bch2_trans_node_add(trans, n2);
-	bch2_trans_node_add(trans, n1);
+		bch2_trans_node_add(trans, path2, n2);
+	bch2_trans_node_add(trans, path1, n1);
 
 	if (n3)
 		six_unlock_intent(&n3->c.lock);
@@ -1913,7 +1913,7 @@ int __bch2_foreground_maybe_merge(struct btree_trans *trans,
 	bch2_btree_node_free_inmem(trans, path, b);
 	bch2_btree_node_free_inmem(trans, sib_path, m);
 
-	bch2_trans_node_add(trans, n);
+	bch2_trans_node_add(trans, path, n);
 
 	bch2_trans_verify_paths(trans);
 
@@ -1985,7 +1985,7 @@ int bch2_btree_node_rewrite(struct btree_trans *trans,
 
 	bch2_btree_node_free_inmem(trans, iter->path, b);
 
-	bch2_trans_node_add(trans, n);
+	bch2_trans_node_add(trans, iter->path, n);
 	six_unlock_intent(&n->c.lock);
 
 	bch2_btree_update_done(as, trans);