--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -976,7 +976,24 @@ int bch2_fsck_update_backpointers(struct btree_trans *trans,
 	int ret = 0;
 
 	if (d->v.d_type == DT_SUBVOL) {
-		BUG();
+		struct bch_subvolume subvol;
+
+		ret = bch2_subvolume_get(trans, le32_to_cpu(d->v.d_child_subvol),
+					     false, &subvol);
+		if (ret && !bch2_err_matches(ret, ENOENT))
+			goto err;
+
+		ret = get_visible_inodes(trans, &target, s, le64_to_cpu(subvol.inode));
+		if (ret)
+			goto err;
+
+		if (target.inodes.nr) {
+			target.inodes.data[0].inode.bi_dir_offset = d->k.p.offset;
+			ret = __bch2_fsck_write_inode(trans, &target.inodes.data[0].inode);
+			if (ret)
+				goto err;
+		}
+
 	} else {
 		ret = get_visible_inodes(trans, &target, s, le64_to_cpu(d->v.d_inum));
 		if (ret)