ll_rw_block(READA, 1, &bh); brelse(bh);
if (likely(bh)) { ll_rw_block(READA, 1, &bh); brelse(bh); }
void __breadahead(struct block_device *bdev, sector_t block, int size){	struct buffer_head *bh = __getblk(bdev, block, size);	ll_rw_block(READA, 1, &bh);	brelse(bh);}