VFS_SYNC
error = VFS_SYNC(mp, MNT_WAIT, stall, p->p_ucred, p);
VFS_SYNC(mp, MNT_LAZY, 0, ap->a_cred, ap->a_p);
(error = VFS_SYNC(mp, MNT_WAIT, 0, p->p_ucred, p)) == 0) ||
VFS_SYNC(mp, MNT_NOWAIT, 0, p->p_ucred, p);
VFS_SYNC(mp, MNT_WAIT, 0, p->p_ucred, p);
VFS_SYNC(mp, MNT_WAIT, 0, p->p_ucred, p);