bcachefs: Fix btree_path leaks in bch2_trans_update()

bch2_trans_update() had some dodgy gets() and puts() - this fixes a few
leaks.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/btree_update_leaf.c

@@ -1336,8 +1336,6 @@ int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 		.ip_allocated	= _RET_IP_,
 	};
 
-	__btree_path_get(n.path, true);
-
 #ifdef CONFIG_BCACHEFS_DEBUG
 	trans_for_each_update(trans, i)
 		BUG_ON(i != trans->updates &&
@@ -1374,16 +1372,17 @@ int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 		if (n.cached && !i->cached) {
 			i->k = n.k;
 			i->flags = n.flags;
-
-			__btree_path_get(n.path, false);
-		} else {
-			bch2_path_put(trans, i->path, true);
-			*i = n;
+			return 0;
 		}
+
+		bch2_path_put(trans, i->path, true);
+		*i = n;
 	} else
 		array_insert_item(trans->updates, trans->nr_updates,
 				  i - trans->updates, n);
 
+	__btree_path_get(n.path, true);
+
 	return 0;
 }