DIR_ROUNDUP
(dp->d_reclen & (DIR_ROUNDUP - 1)) != 0)
unused = roundup2(namlen + 1, DIR_ROUNDUP) - (namlen + 1);
(roundup2(__offsetof(struct direct, d_name) + (namlen) + 1, DIR_ROUNDUP))
*(uint32_t *)(&newdirp->d_name[namelen & ~(DIR_ROUNDUP - 1)]) = 0;