__vb2_init_fileio
static int __vb2_init_fileio(struct vb2_queue *q, int read);
if (__vb2_init_fileio(q, 1))
if (__vb2_init_fileio(q, 0))
ret = __vb2_init_fileio(q, read);
ret = __vb2_init_fileio(q, !q->is_output);