Re: [patch 6/9] signalfd/timerfd v1 - timerfd core ...

Nicholas Miell
2007-03-11T06:18:41Z

On Sat, 2007-03-10 at 21:31 -0800, Linus Torvalds wrote:
>
> On Sat, 10 Mar 2007, Nicholas Miell wrote:
> >
> > Ah, I see. You're just interested in fds as a generic handle concept,
> > and not a more Plan 9 type thing.
>
> Indeed. It's a "handle".
>
> UNIX has pid's for "process" handles, and "file descriptors" for just
> about everything else.

And I imagine that somebody will come up with way of getting a fd for a
process sooner or later.

> > If that's the goal, somebody should start thinking about reducing the
> > contents of struct file to the bare minimum (i.e. not much more than a
> > file_operations pointer).
>
> Well, there's more there, but it really is fairly close. If you look at
> it, a "struct file" ends up not having a lot more than the minimal stuff
> required to use it as a a handle: it really isn't a very big structure.
>
> The biggest part is actually the read-ahead state, which is arguably a
> generic thing for a file handle, even though not all kinds will be able to
> use it. We *could* make that be behind a pointer (along with the "f_pos"
> thing, that really logically goes along with the read-ahead thing), of
> course, but since most files probably do end up being "traditional file"
> structures, it's probably not wrong to just have it in the file.
>

Actually, I was thinking reducing struct file to the bare minimum, and
then using that as the common header shared by object-specific
structures. I don't know how unpleasant that would be from a memory
allocation perspective, though.

--
Nicholas Miell <nmiell@comcast.net>