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

On Tue, Nov 7, 2017 at 10:54 PM, Raphael Hertzog <hertzog(at)debian(dot)org> wrote:
> This has been explained by the overlayfs upstream developer
> (to which I reported this bug initially, thinking it was an
> overlayfs regression):
> https://marc.info/?l=linux-unionfs&m=151005246512873&w=2
> https://marc.info/?l=linux-unionfs&m=151005699414227&w=2
>
> My request is thus that PostgreSQL should fsync that directory only after
> it has made changes to the directory or its content. PostgreSQL 9.6 was
> working fine in the same setup and I would like PostgreSQL 10 to do the
> same. :)
>
> I'm ccing Teodor Sigaev <teodor(at)sigaev(dot)ru> because I believe that
> the problematic fsync() has been added by him in this commit:
> https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=1b02be21f271db6bd3cd43abb23fa596fcb6bac3

Hm. I am wondering if we should change fsync_fname_ext() so as EINVAL
is considered as a no-op. EIO and EINTR should really be caught with a
proper error, but I am not sure about this one. Thoughts?
--
Michael