EXT2_SBSIZE
char fs_pad[EXT2_SBSIZE - sizeof(struct ext2fs_disk)];
EXT2_SBLOCK, EXT2_SBSIZE, (char *)fs, &buf_size);
if (buf_size != EXT2_SBSIZE || fs->fs_magic != EXT2_MAGIC) {
EXT2_SBLOCK + EXT2_SBSIZE / DEV_BSIZE, len,