#include <linux/fs.h>

LDD3 chapter 3

struct file_operations
	owner = THIS_MODULE
	read
	write
	ioctl vs unlocked_ioctl vs compat_ioctl

	unlocked_ioctl does not grab the kernel lock
	unlocked_ioctl and compat_ioctl does not receive the inode structure
	compat_ioctl (32bit vs 64bit)

	open
	release
	flush
	mmap
	poll
	llseek

struct file
	f_op
	f_flags
	f_pos
	private_data

we will not mess with inode
struct inode

iminor
imajor