get_leaf
error = get_leaf(dip, leaf_no, &obh);
error = get_leaf(ip, lfn, &bh);
error = get_leaf(ip, lfn, &bh);
error = get_leaf(ip, bn, &obh);
error = get_leaf(dip, blk, &bh);
error = get_leaf(dip, blk, &bh);
error = get_leaf(dip, leaf_no, &bh);
error = get_leaf(dip, leaf_no, bh_out);
error = get_leaf(ip, ln, &bh);