fo_shutdown
error = fo_shutdown(fp, how);
.fo_shutdown = badfo_shutdown,
.fo_shutdown = nofo_shutdown,
return(fo_shutdown(fp, how));
.fo_shutdown = badfo_shutdown,
.fo_shutdown = pipe_shutdown,
.fo_shutdown = soo_shutdown,
.fo_shutdown = nofo_shutdown,
int (*fo_shutdown)(struct file *fp, int how);
return ((*fp->f_ops->fo_shutdown)(fp, how));
.fo_shutdown = nofo_shutdown,