From: Taylor Blau <me@ttaylorr.com>
Date: Thu, 09 Sep 2021 21:13:04 GMT
Subject: Re: [PATCH 9/9] pack-objects: rename .idx files into place after .bitmap files
Message-ID: <YTp44A+kPOf8U+7w@nand.local>
In-Reply-To: <xmqqr1dxy1b0.fsf@gitster.g>

On Thu, Sep 09, 2021 at 12:52:03PM -0700, Junio C Hamano wrote:
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
> >     We fsync() the file descriptors we're writing out for all the
> >     auxiliary files, but we don't yet fsync() the file descriptor for
> >     the containing directory. Therefore our data might have been written
> >     out, but it's anyone's guess what the state of the directory
> >     containing the file is after we write the *.idx.
> >
> >     In practice modern OS's are known to be forgiving on that point, so
> >     this will probably solve races in practice for most users. It will
> >     almost certainly make them better than they were before when we
> >     didn't write *.idx files last. We should more generally improve our
> >     use of fsync() to cover containing directories, but that'll
> >     hopefully be addressed by some follow-up series.
>
> I'd probably drop the last paragraph, and replace it with a single
> sentence "we may want to fsync the containing directory once after
> placing *.idx file in place, but it is outside of the scope of this
> series", if I were doing this series.

Yep, I think that this makes things clearer, and I prefer it to Ævar's
suggestion (which conveys more information than I think is necessary
here).

Thanks,
Taylor