XREP_AGF_RMAPBT
!xrep_check_btree_root(sc, &fab[XREP_AGF_RMAPBT]))
if (fab[XREP_AGF_RMAPBT].root != be32_to_cpu(old_agf->agf_rmap_root))
agf->agf_rmap_root = cpu_to_be32(fab[XREP_AGF_RMAPBT].root);
agf->agf_rmap_level = cpu_to_be32(fab[XREP_AGF_RMAPBT].height);
[XREP_AGF_RMAPBT] = {