Add sysctl which enables/disable auto resize of geom part.
In some case when we are working with zfs this can couse some troubles for example:
root@w1:~ # zfs create -V100M test/test root@w1:~ # gpart create -s gpt /dev/zvol/test/test root@w1:~ # zfs set volsize=200M test/test root@w1:~ # zpool export test cannot export 'test': pool is busy root@w1:~ # zpool export -F test cannot export 'test': pool is busy