Re: [Qemu-devel] [Qemu-block] [PATCH 10/29] qed: Remove callback from qed_write_header()

[Kevin Wolf <kwolf@redhat.com>]

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Am 31.05.2017 um 14:32 hat Stefan Hajnoczi geschrieben:
> On Fri, May 26, 2017 at 10:21:51PM +0200, Kevin Wolf wrote:
> >  static void qed_clear_need_check(void *opaque, int ret)
> >  {
> >      BDRVQEDState *s = opaque;
> >  
> >      if (ret) {
> > -        qed_unplug_allocating_write_reqs(s);
> > -        return;
> > +        goto out;
> >      }
> >  
> >      s->header.features &= ~QED_F_NEED_CHECK;
> > -    qed_write_header(s, qed_flush_after_clear_need_check, s);
> > +    ret = qed_write_header(s);
> > +    (void) ret;
> > +
> > +    ret = bdrv_flush(s->bs);
> > +    (void) ret;
> > +
> > +out:
> > +    qed_unplug_allocating_write_reqs(s);
> >  }
> 
> Should we unplug allocating write reqs before flushing?  The async code
> kicks off a flush but doesn't wait for it to complete.

You're right that moving it up would match the old code. Not sure if it
would make much of a difference, though, isn't the request queue drained
in the kernel anyway while doing a flush? But if you prefer, I can
change it.

Kevin

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