Re: pagecache locking (was: bcachefs status update) merged)

[Linus Torvalds]

On Thu, Jun 13, 2019 at 5:08 PM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> I do not believe that posix itself actually requires that at all,
> although extended standards may.

So I tried to see if I could find what this perhaps alludes to.

And I suspect it's not in the read/write thing, but the pthreads side
talks about atomicity.

Interesting, but I doubt if that's actually really intentional, since
the non-thread read/write behavior specifically seems to avoid the
whole concurrency issue.

The pthreads atomicity thing seems to be about not splitting up IO and
doing it in chunks when you have m:n threading models, but can be
(mis-)construed to have threads given higher atomicity guarantees than
processes.

               Linus