UFS_NINDIR
bound = UFS_NINDIR(SUPERBLOCK);
bound *= UFS_NINDIR(SUPERBLOCK);
bound /= UFS_NINDIR(SUPERBLOCK);
index = (bn / bound) % UFS_NINDIR(SUPERBLOCK);
bound /= UFS_NINDIR(SUPERBLOCK);
index = (bn / bound) % UFS_NINDIR(SUPERBLOCK);