The e- pair of ethene's pi orbital donates to metal's dz2 orbital.

My questions are:

Ethene is a pi donor or sigma donor? (just neglect the back-pi-bonding)
This bonding is pi bond or sigma bond?
This is a sigma donation or pi donation?

Ethene uses its pi orbital e- for donation, it should be pi donor, right?
But it forms a sigma bond with metal.
I don't understand the terms donation is referred to the metal or ligand? (from or to)