Re: [PATCH 09/17] file: Implement fnext_task

Christian Brauner
2020-08-18T11:06:08Z

On Mon, Aug 17, 2020 at 06:17:35PM -0700, Linus Torvalds wrote:
> On Mon, Aug 17, 2020 at 6:06 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
> >
> > I struggle with the fcheck name as I have not seen or at least not
> > registed on the the user that just checks to see if the result is NULL.
> > So the name fcheck never made a bit of sense to me.
>
> Yeah, that name is not great. I just don't want to make things even worse.
>
> > I will see if I can come up with some good descriptive comments around
> > these functions. Along with describing what these things are doing I am
> > thinking maybe I should put "_rcu" in their names and have a debug check
> > that verifies "_rcu" is held.
>
> Yeah, something along the lines of "rcu_lookup_fd_task(tsk,fd)" would
> be a *lot* more descriptive than fcheck_task().
>
> And I think "fnext_task()" could be "rcu_lookup_next_fd_task(tsk,fd)".
>
> Yes, those are much longer names, but it's not like you end up typing
> them all that often, and I think being descriptive would be worth it.
>
> And "fcheck()" and "fcheck_files()" would be good to rename too along
> the same lines.
>
> Something like "rcu_lookup_fd()" and "rcu_lookup_fd_files()" respectively?
>
> I'm obviously trying to go for a "rcu_lookup_fd*()" kind of pattern,
> and I'm not married to _that_ particular pattern but I think it would
> be better than what we have now.

In fs/inode.c and a few other places we have the *_rcu suffix pattern
already so maybe:

fcheck() -> fd_file_rcu() or lookup_fd_rcu()
fcheck_files() -> fd_files_rcu() or lookup_fd_files_rcu()
fnext_task() -> fd_file_from_task_rcu() or lookup_next_fd_from_task_rcu()

rather than as prefix or sm.

Christian