Nearest non-negative solution for $Av=b$

Question

Let $A$ be a $n\times m$ matrix. Let us define the system $$Av=b$$ $$v\geq 0$$

I want to find a solution $v$ of this system that is the closest (euclidean norm) to $v_0$, a given $n$-dimensional vector.

What is the simplest way to solve this ?

Thanks.