Re: Fails to work on live images due to fsync() on pg_commit_ts before doing any write there

On Tue, 07 Nov 2017, Tom Lane wrote:
> Yeah, it does sound more like a filesystem bug than anything else.
> (I completely reject the notion that it's an application error to
> fsync a directory when you haven't modified it.)
>
> In view of the fact that we just wrapped 10.1, it'd be 3 months before
> any change from our side would reach the wild. I think a key question
> here is whether the Kali developers are likely to fix it from their side
> in less time than that.

Fix what?

Following your logic, if anything needs to be fixed, it's the Linux kernel
that has to be fixed, and in particular its overlayfs filesystem. The time
to get a fix there is also relatively long. If they work on a fix quickly,
it might get merged for Linux 3.15 which we will not have in Kali before
2-3 months too.

But I can always cherry-pick a patch, either in PostgreSQL or in Linux.
BTW I'm happy to test a PostgreSQL patch for instance.

For now, I have added an ugly work-around that creates a file in the
pg_commit_ts directory (and immediately drops it) just before starting
PostgreSQL:
http://git.kali.org/gitweb/?p=packages/kali-defaults.git;a=commitdiff;h=f4287fd774f8d0686ba919f57355215a6b9633e3

Note that it's perfectly fine for me if you decide to resolve this issue
by ignoring EINVAL and/or EROFS on fsync on directories.

Cheers,
--
Raphaël Hertzog ◈ Debian Developer

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