typedef unsigned long long u64;
struct super_block {
	unsigned s_blocksize;
	struct block_device *s_bdev;
};
struct buffer_head {
	u64 b_blocknr;
};
int sb_bread(struct super_block *sb, u64 block)
{
	return __bread(sb->s_bdev, block, sb->s_blocksize);
}
int sysv_fill_super(struct super_block *sb)
{
	struct buffer_head *bh;
	unsigned blocknr;
	if (test()) {
		blocknr = bh->b_blocknr >> 1;
		bh = sb_bread(sb, blocknr);
	}
}