vfs/vnode/file overhaul

Matthew Dillon dillon at apollo.backplane.com
Wed Jul 25 11:08:12 PDT 2007

:as a 1.11 topic I think we should change the vnode/file interface to make more sense.  these are of course just stupid ideas to illustrate what I am thinking of:
:- all per-fdesc-I/O runs through a struct file and not directly to a vnode
:- vnodes only represent logical entities (on disk), NOT devices or whatnot.
:- thus drop specfs, this always seemed switched in at the wrong place in the stack
:- this will allow us to do device cloning
:- a slim vnode interface makes it easier to do support a...
:- userland vfs interface which can support something like the kernel API, so userland drivers have a chance to be easily ported to the kernel.
:do I make sense?  feedback expected!
:  simon

    I actually did implement a direct file-descriptor based interface for
    devices, but quickly found that a lot of bits and pieces in the system
    depend on the access and modified times of the device node in the
    filesystem being updated.  This is a particular requirement for TTYs
    and PTYs.

    In otherwords, we need a devfs.  Once we have that then, yes, we can
    get rid of the vnode API for devices.


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