+
+static int pos_overwritten_in_snapshot(struct btree_trans *trans, enum btree_id btree,
+ struct bpos pos, u32 snapshot)
+{
+ struct bch_fs *c = trans->c;
+ struct btree_iter iter;
+ struct bkey_s_c k;
+ int ret;
+
+ for_each_btree_key_norestart(trans, iter,
+ btree, SPOS(pos.inode, pos.offset, snapshot),
+ BTREE_ITER_ALL_SNAPSHOTS|
+ BTREE_ITER_NOPRESERVE, k, ret) {
+ if (bpos_ge(k.k->p, pos))
+ break;
+
+ if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) {
+ ret = 1;
+ break;
+ }
+ }
+ bch2_trans_iter_exit(trans, &iter);
+
+ return ret;
+}
+
+int __bch2_insert_snapshot_whiteouts(struct btree_trans *trans,
+ enum btree_id btree,
+ struct bpos old_pos,
+ struct bpos new_pos)
+{
+ struct bch_fs *c = trans->c;
+ struct btree_iter old_iter, new_iter;
+ struct bkey_s_c k;
+ snapshot_id_list s;
+ struct bkey_i *update;
+ int ret;
+
+ if (!bch2_snapshot_has_children(c, old_pos.snapshot))
+ return 0;
+
+ darray_init(&s);
+
+ bch2_trans_iter_init(trans, &old_iter, btree, old_pos,
+ BTREE_ITER_NOT_EXTENTS|
+ BTREE_ITER_ALL_SNAPSHOTS);
+ while ((k = bch2_btree_iter_prev(&old_iter)).k &&
+ !(ret = bkey_err(k)) &&
+ bkey_eq(old_pos, k.k->p)) {
+
+ if (!bch2_snapshot_is_ancestor(c, k.k->p.snapshot, old_pos.snapshot) ||
+ snapshot_list_has_ancestor(c, &s, k.k->p.snapshot))
+ continue;
+
+ ret = pos_overwritten_in_snapshot(trans, btree,
+ new_pos, k.k->p.snapshot);
+ if (ret < 0)
+ break;
+
+ if (!ret) {
+ struct bpos whiteout_pos =
+ SPOS(new_pos.inode, new_pos.offset, k.k->p.snapshot);;
+
+ bch2_trans_iter_init(trans, &new_iter, btree, whiteout_pos,
+ BTREE_ITER_NOT_EXTENTS|
+ BTREE_ITER_INTENT);
+ update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i));
+ ret = PTR_ERR_OR_ZERO(update);
+ if (ret)
+ break;
+
+ bkey_init(&update->k);
+ update->k.p = whiteout_pos;
+ update->k.type = KEY_TYPE_whiteout;
+
+ ret = bch2_btree_iter_traverse(&new_iter) ?:
+ bch2_trans_update(trans, &new_iter, update,
+ BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+ bch2_trans_iter_exit(trans, &new_iter);
+ }
+
+ ret = snapshot_list_add(c, &s, k.k->p.snapshot);
+ if (ret)
+ break;
+ }
+ bch2_trans_iter_exit(trans, &old_iter);
+ darray_exit(&s);
+
+ return ret;
+}
+