vn_bmap_seekhole_locked
error = vn_bmap_seekhole_locked(vp, FIOSEEKDATA, &noff, cred);
error = vn_bmap_seekhole_locked(vp, FIOSEEKHOLE, &noff, cred);
error = vn_bmap_seekhole_locked(vp, cmd, off, cred);
int vn_bmap_seekhole_locked(struct vnode *vp, u_long cmd, off_t *off,