Looking as close as I can at the bark, it appears to be forming callus over this injury. Not sure what caused it but it does not appear to be a problem at this time. Keep an eye on the root that is growing around part of the trunk. I cannot see the other side and to tell if it will inhibit the growth of the trunk as it gets bigger. Roots grow in diameter and if they press up against the trunk, they can damage the tissue under the bark of the trunk and disrupt flow of nutrients and water. If it is not pressing on the trunk it is not a problem but if it wraps around the tree and is going to put pressure on the trunk as it grows than it should be removed. I would contact an arborist to take a look at it and determine if it needs to removed.