[root@demo1 vz-scripts]# cat mysql_mount 
#!/bin/sh

MODE=${0##*\.}

SRC=/vz/root/10002/var/lib/mysql
DST=/vz/root/10003/var/lib/mysql

MOUNTED=$(grep $DST /proc/mounts  | wc -l)

mnt() {
        if [ $MOUNTED -lt 1 ] && [ -d $DST ]; then
            mount --bind $SRC $DST >/dev/null 2>&1
        fi
}

umnt() {
        if [ $MOUNTED -gt 0 ]; then
                umount $DST >/dev/null 2>&1
        fi
}

case "$MODE" in
    mount)
        mnt
        ;;
    
    umount)
        umnt
        ;;

    *)
        echo "Unknown mode ($MODE)"
        exit -1
        ;;
esac

[root@demo1 vz-scripts]# ls -la 1000[23].*mount
lrwxrwxrwx  1 root root 11 Nov 10 07:07 10002.mount -> mysql_mount
lrwxrwxrwx  1 root root 11 Nov 10 07:07 10002.umount -> mysql_mount
lrwxrwxrwx  1 root root 11 Nov 10 07:07 10003.mount -> mysql_mount
lrwxrwxrwx  1 root root 11 Nov 10 07:07 10003.umount -> mysql_mount