static struct buffer_head *raid5_build_block (struct stripe_head *sh, int i)
{
	raid5_conf_t *conf = sh->raid_conf;
	struct buffer_head *bh = sh->bh_cache[i];
	unsigned long block = sh->sector / (sh->size >> 9);

	init_buffer(bh, raid5_end_read_request, sh);
	bh->b_dev       = conf->disks[i].dev;
	bh->b_blocknr   = block;

	bh->b_state	= (1 << BH_Req) | (1 << BH_Mapped);
	bh->b_size	= sh->size;
	bh->b_list	= BUF_LOCKED;
	return bh;
}
