On Tue, Feb 18, 2014 at 10:53 AM, Matthew Wilcox <willy@xxxxxxxxxxxxxxx> wrote:
>
> Yes, I did mean "holepunches and page faults". But here's the race I see:
Hmm. With truncate, we should be protected by i_size being changed
first (iirc - I didn't actually check), but I think you're right that
hole punching might race with a page being mapped at the same time.
> What I'm suggesting is going back to Kirill's earlier patch, but only
> locking the page with the highest index instead of all of the pages.
> truncate() will block on that page and then we'll notice that some or
> all of the other pages are also now past i_size and give up.
Actually, Kirill's latest patch seems to solve the problem with
locking - by simply never locking more than one page at a time. So I
guess it's all moot at least wrt the page preload..
Linus
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