/usr/share/glusterfs/scripts/stop-all-gluster-processes.sh is in glusterfs-common 3.7.6-1ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | #! /bin/sh
main()
{
    for pidfile in $(find /var/lib/glusterd/ -iname '*pid');
    do
        pid=$(cat ${pidfile});
        echo "sending SIGTERM to process $pid";
        kill -TERM $pid;
    done
    # for geo-replication, only 'monitor' has pid file written, other
    # processes are not having a pid file, so get it through 'ps' and
    # handle these processes
    gsyncpid=`ps aux | grep gluster | grep gsync | awk '{print $2}'`;
    test -n "$gsyncpid" && kill -TERM $gsyncpid;
    sleep 5;
    # if pid file still exists, its something to KILL
    for pidfile in $(find /var/lib/glusterd/ -iname '*pid');
    do
        pid=$(cat ${pidfile});
        echo "sending SIGKILL to process $pid";
        kill -KILL $pid;
    done
    # handle 'KILL' of geo-replication
    gsyncpid=`ps aux | grep gluster | grep gsync | awk '{print $2}'`;
    test -n "$gsyncpid" && kill -KILL $gsyncpid;
}
main "$@";
 |