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From:   Christian Brauner <christian@brauner.io>
Date:   Wed, 22 May 2019 10:12:11 +0200
Message-ID: <CAHrFyr4NV_5Z7TRSXTaurd4KCTLiHqKb47dN=bdY46HiL9ZY3Q@mail.gmail.com>
Subject: Re: [PATCH 1/2] open: add close_range()
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     David Howells <dhowells@redhat.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
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On Tue, May 21, 2019 at 10:23 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Tue, May 21, 2019 at 9:41 AM Christian Brauner <christian@brauner.io> wrote:
> >
> > Yeah, you mentioned this before. I do like being able to specify an
> > upper bound to have the ability to place fds strategically after said
> > upper bound.
>
> I suspect that's the case.
>
> And if somebody really wants to just close everything and uses a large
> upper bound, we can - if we really want to - just compare the upper
> bound to the file table size, and do an optimized case for that. We do
> that upper bound comparison anyway to limit the size of the walk, so
> *if* it's a big deal, that case could then do the whole "shrink
> fdtable" case too.

Makes sense.

>
> But I don't believe it's worth optimizing for unless somebody really
> has a load where that is shown to be a big deal.   Just do the silly
> and simple loop, and add a cond_resched() in the loop, like
> close_files() does for the "we have a _lot_ of files open" case.

Ok. I will resend a v1 later with the cond_resched() logic you and Al
suggested added.

Thanks!
Christian