Description of problem:

Instead of passing over the respective values obtained from backend, fuse xlator specifies stavfs values (in particular, f_{b,fr}size) on its own.

This is confusing as the size granularity, and therefore the fs sizes reported by df and similar tools will differ within different protocols.

See http://lists.gluster.org/pipermail/gluster-devel/2018-March/054660.html for more background on the phenomenon.