How to split given linked list

I am given the linked list node struct as follows:

#[derive(PartialEq, Eq, Clone, Debug)]
pub struct ListNode {
    pub val: i32,
    pub next: Option<Box<ListNode>>,
}

I need to write a method splitting a linked list equally and returning both parts. I could not make it in a single method, so I created two: the first calculates the length of the list, the second splits.

fn get_length(head: &Option<Box<ListNode>>) -> usize {
    let mut res = 0;
    let mut current_node = head;
    while current_node.is_some() {
        current_node = &current_node.as_ref().unwrap().next;
        res += 1;
    }
    res
}

fn split(mut head: Option<Box<ListNode>>, len: usize) -> (Option<Box<ListNode>>, Option<Box<ListNode>>) {
    let mut curr = head.take();
    for _ in 0..len {
        let mut curr_inner = curr.unwrap();
        curr = curr_inner.next.take();
    }
    (head, curr.take())
}

let len = get_length(&node);
let (l1, l2) = split(node, len / 2 + len % 2);

The problem is in split() – I lose the head. I don’t how to keep it.
Could anybody advise?

fn split(
    mut head: Option<Box<ListNode>>,
    len: usize,
) -> (Option<Box<ListNode>>, Option<Box<ListNode>>) {
    let mut curr = &mut head;
    for _ in 0..len {
        let curr_inner = curr.as_mut().unwrap();
        curr = &mut curr_inner.next;
    }
    let tail = curr.take();
    (head, tail)
}