title: Why is the close function is called release in `struct file_operations` in the Linux kernel?
body: <p>I'm trying to make a linux kernel module, which supports open, close, read and write operations.
  So I want to register these functions via struct file_operations, however I can't find 'close' entry in the struct.
  I think I should use 'release' instead of 'close', but I wonder why the name is 'release' and not 'close'?</p>