/* Mergesort */
-void bch2_btree_keys_stats(struct btree *b, struct bset_stats *stats)
+void bch2_btree_keys_stats(const struct btree *b, struct bset_stats *stats)
{
- struct bset_tree *t;
+ const struct bset_tree *t;
for_each_bset(b, t) {
enum bset_aux_tree_type type = bset_aux_tree_type(t);