Re: [Qemu-devel] [PATCH 1/3] mirror: Go through ready -> complete process for 0 len image

[Paolo Bonzini]

Il 05/06/2014 13:17, Stefan Hajnoczi ha scritto:
> On Thu, Jun 05, 2014 at 11:42:34AM +0800, Fam Zheng wrote:
> > diff --git a/block/mirror.c b/block/mirror.c
> > index 94c8661..2bef5f3 100644
> > --- a/block/mirror.c
> > +++ b/block/mirror.c
> > @@ -324,9 +324,18 @@ static void coroutine_fn mirror_run(void *opaque)
> >      }
> >
> >      s->common.len = bdrv_getlength(bs);
> > -    if (s->common.len <= 0) {
> > +    if (s->common.len < 0) {
> >          ret = s->common.len;
> >          goto immediate_exit;
> > +    } else if (s->common.len == 0) {
> > +        /* Report BLOCK_JOB_READY and wait for complete. */
> > +        block_job_ready(&s->common);
> > +        s->synced = true;
> > +        while (!block_job_is_cancelled(&s->common) && !s->should_complete) {
> > +            block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, SLICE_TIME);
>
> Please take a look at block_job_resume() and how it's used when
> cancelling or completing block jobs.  There is no need to sleep, instead
> we can yield until we get resumed.

You still need to set job->busy = false.  So I guess we need a new 
function block_job_yield.

Paolo