I claim the ornamental design for a barrier post, as shown and described.
FIG. 1 is a perspective view of a barrier post illustrating the folded feet in a fully extended position.
FIG. 2 is a perspective view of a barrier post according to the present invention showing the folding feet being moved between the extended position and a retracted position; and,
FIG. 3 is a perspective view of a barrier post according to the present invention showing the folding feet in a fully retracted position.