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Date: Tue, 23 Jul 2013 15:39:44 +0200
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20130723133944.GC27684@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 3/3] dataplane: enable virtio-blk
 x-data-plane=on live migration
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Juan Quintela <quintela@redhat.com>

On Wed, Jul 17, 2013 at 12:26:54PM +0200, Paolo Bonzini wrote:
> Il 17/07/2013 11:35, Stefan Hajnoczi ha scritto:
> > @@ -628,6 +629,34 @@ void virtio_blk_set_conf(DeviceState *dev, VirtIOBlkConf *blk)
> >      memcpy(&(s->blk), blk, sizeof(struct VirtIOBlkConf));
> >  }
> >  
> > +#ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
> > +/* Disable dataplane thread during live migration since it does not
> > + * update the dirty memory bitmap yet.
> > + */
> > +static void virtio_blk_migration_state_changed(Notifier *notifier, void *data)
> > +{
> > +    VirtIOBlock *s = container_of(notifier, VirtIOBlock,
> > +                                  migration_state_notifier);
> > +    MigrationState *mig = data;
> > +
> > +    if (migration_is_active(mig)) {
> > +        if (!s->dataplane) {
> > +            return;
> > +        }
> > +        virtio_blk_data_plane_destroy(s->dataplane);
> > +        s->dataplane = NULL;
> > +    } else if (migration_has_finished(mig) ||
> > +               migration_has_failed(mig)) {
> > +        if (s->dataplane) {
> > +            return;
> > +        }
> > +        bdrv_drain_all(); /* complete in-flight non-dataplane requests */
> > +        virtio_blk_data_plane_create(VIRTIO_DEVICE(s), &s->blk,
> > +                                     &s->dataplane);
> > +    }
> > +}
> 
> Perhaps you can call bdrv_set_in_use here (set it to 1 after
> destruction, and to 0 before creation), so that you do not need the
> check in virtio_blk_data_plane_create?

The bdrv_in_use() check fixes a bug that was present before this series.
Therefore I split it into a separate commit in v3 and CCed
qemu-stable@nongnu.org.

Stefan