bcachefs: Fix a btree iter assertion pop

This fixes a (harmless) broken invariant in __bch2_btree_path_set_pos():
iterators to interior nodes should point to the first non whiteout.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index ecb6f27e49177b1ba51b37b2dab5a29e3ab1855e..ff796a74fd2faeb12e81aa61a392210c23868205 100644 (file)
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -1202,7 +1202,7 @@ __bch2_btree_path_set_pos(struct btree_trans *trans,
                          struct btree_path *path, struct bpos new_pos,
                          bool intent, int cmp)
 {
-       unsigned l = path->level;
+       unsigned level = path->level;
 
        EBUG_ON(trans->restarted);
        EBUG_ON(!path->ref);
@@ -1219,10 +1219,12 @@ __bch2_btree_path_set_pos(struct btree_trans *trans,
                goto out;
        }
 
-       l = btree_path_up_until_good_node(trans, path, cmp);
+       level = btree_path_up_until_good_node(trans, path, cmp);
 
-       if (btree_path_node(path, l)) {
-               BUG_ON(!btree_node_locked(path, l));
+       if (btree_path_node(path, level)) {
+               struct btree_path_level *l = &path->l[level];
+
+               BUG_ON(!btree_node_locked(path, level));
                /*
                 * We might have to skip over many keys, or just a few: try
                 * advancing the node iterator, and if we have to skip over too
@@ -1230,11 +1232,18 @@ __bch2_btree_path_set_pos(struct btree_trans *trans,
                 * is expensive).
                 */
                if (cmp < 0 ||
-                   !btree_path_advance_to_pos(path, &path->l[l], 8))
-                       __btree_path_level_init(path, l);
+                   !btree_path_advance_to_pos(path, l, 8))
+                       bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
+
+               /*
+                * Iterators to interior nodes should always be pointed at the first non
+                * whiteout:
+                */
+               if (unlikely(level))
+                       bch2_btree_node_iter_peek(&l->iter, l->b);
        }
 
-       if (l != path->level) {
+       if (unlikely(level != path->level)) {
                btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
                __bch2_btree_path_unlock(trans, path);
        }