Read/Write operations

[Peix Fabrice]

Yops,

	In struct file_operations read and write are define as follow
	ssize_t (*read) (struct file *fops, char *buf, size_t count, loff_t
*ppos);
	ssize_t (*write) (struct file *fops, const char *buf, size_t count,
loff_t *ppos);

	Just a little question, in which case the value of *ppos is different
of fops->f_pos.

	Thanks.