struct child_t {
    haddr_t         addr;
    unsigned        level;
    struct child_t         *next;
    } *head = NULL, *tail = NULL, *prev = NULL, *cur = NULL, *tmp = NULL;
    FUNC_ENTER_NOAPI_NOINIT
    if(0 == ncalls++) {
    if(H5DEBUG(B))
        fprintf(H5DEBUG(B), "H5B: debugging B-trees (expensive)\n");
        HDfprintf(H5DEBUG(B), "H5B: debugging B-trees (expensive)\n");
    } /* end if */
    /* Get shared info for B-tree */
    if(NULL == (rc_shared = (type->get_shared)(f, udata)))
    HGOTO_ERROR(H5E_BTREE, H5E_CANTGET, FAIL, "can't retrieve B-tree's shared ref. count object")
    shared = (H5B_shared_t *)H5RC_GET_OBJ(rc_shared);
    HDassert(shared);
    /* Initialize the queue */
    cache_udata.f = f;