AFBC_HEADER_SIZE
kfb->offset_payload = ALIGN(n_blocks * AFBC_HEADER_SIZE,
afbc_size = ALIGN(n_superblocks * AFBC_HEADER_SIZE, AFBC_SUPERBLK_ALIGNMENT);
afbc_fb->afbc_size = ALIGN(n_blocks * AFBC_HEADER_SIZE, hdr_alignment);