journald fsync() errors

[vcaputo@xxxxxxxxxxx (vcaputo@xxxxxxxxxxx)]

On Wed, Apr 04, 2018 at 04:49:29PM +0200, Lennart Poettering wrote:
> On Di, 03.04.18 14:10, vcaputo at pengaru.com (vcaputo at pengaru.com) wrote:
> 
> > Back when I worked on making fsync() in journald asynchronous, I
> > preserved the existing strategy of ignoring fsync() errors.
> > 
> > In reading [1], I am reminded of this situation and am again wondering
> > why this is the case.  Shouldn't journald trigger a journal rotate when
> > fsync() realizes an IO error, marking the previous journal as corrupt?
> > 
> > Can someone remind me of the rationale behind the existing approach?
> 
> Hmm, you are right, we should rotate if fsync() fails, indeed.
> 
> Would love to review/merge a patch for that.
> 

Slapped this [1] together today.  I did not scrutinize the higher-order
functions to verify they Do The Right Thing when the -EIO propagates
out, but considering mmap_cache_got_sigbus() already produced -EIO, I
assume things work.

As mentioned in the PR, this is 100% untested.  But I should be able to
make time to iterate on the PR if it's desirable and review requires
some changes.

Regards,
Vito Caputo

[1] https://github.com/systemd/systemd/pull/8654