get_snap_max
res = zfs_iter_snapshots(zhp, B_FALSE, get_snap_max, data);
if (zfs_iter_snapshots(zhp, B_FALSE, get_snap_max, &cb) != 0)
if (zfs_iter_snapshots(cln_zhp, B_FALSE, get_snap_max, &sd) != 0)
if (zfs_iter_snapshots(src_zhp, B_FALSE, get_snap_max, &sd) != 0)