G_ELI_KEY_SHIFT
keyno = (dstoff >> G_ELI_KEY_SHIFT) / secsize;
((mediasize - 1) >> G_ELI_KEY_SHIFT) / blocksize + 1;
new_ekeys_total = ((mediasize - 1) >> G_ELI_KEY_SHIFT) / blocksize + 1;
keyno = (offset >> G_ELI_KEY_SHIFT) / blocksize;