ovl_decode_real_fh
upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), true);
origin = ovl_decode_real_fh(ofs, fh, ofs->layers[i].mnt,
upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), connected);
struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,