vop_fdatasync
.vop_fdatasync = vop_stdfdatasync,
DO_OPS(ap->a_head.a_ops, error, ap, vop_fdatasync);
DO_OPS(ops, error, &ap, vop_fdatasync);
vop_fdatasync(*(vp)->v_ops, vp, waitfor, flags, fp) /* FUSE*/
int (*vop_fdatasync)(struct vop_fdatasync_args *);
int vop_fdatasync(struct vop_ops *ops, struct vnode *vp, int waitfor, int flags,