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Date: Mon, 17 Feb 2014 21:21:24 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v13 03/14] block: Replace in_use with
 operation blocker
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To: =?iso-8859-1?Q?Beno=EEt?= Canet <benoit.canet@irqsave.net>
Cc: kwolf@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com

On Thu, 02/13 13:34, Beno=EEt Canet wrote:
> The Wednesday 29 Jan 2014 =E0 13:07:30 (+0800), Fam Zheng wrote :
> > @@ -368,6 +371,7 @@ void virtio_blk_data_plane_create(VirtIODevice *v=
dev, VirtIOBlkConf *blk,
> >  {
> >      VirtIOBlockDataPlane *s;
> >      int fd;
> > +    Error *local_err =3D NULL;
> > =20
> >      *dataplane =3D NULL;
> > =20
> > @@ -390,9 +394,10 @@ void virtio_blk_data_plane_create(VirtIODevice *=
vdev, VirtIOBlkConf *blk,
> >      /* If dataplane is (re-)enabled while the guest is running there=
 could be
> >       * block jobs that can conflict.
> >       */
> > -    if (bdrv_in_use(blk->conf.bs)) {
> > -        error_setg(errp,
> > -                   "cannot start dataplane thread while device is in=
 use");
> > +    if (bdrv_op_is_blocked(blk->conf.bs, BLOCK_OP_TYPE_DATAPLANE, &l=
ocal_err)) {
> > +        error_report("cannot start dataplane thread: %s",
> > +                      error_get_pretty(local_err));
> > +        error_free(local_err);
> >          return;
> >      }
> > =20
> > @@ -407,9 +412,8 @@ void virtio_blk_data_plane_create(VirtIODevice *v=
dev, VirtIOBlkConf *blk,
> >      s->vdev =3D vdev;
> >      s->fd =3D fd;
> >      s->blk =3D blk;
> > -
> > -    /* Prevent block operations that conflict with data plane thread=
 */
> The comment was not really an extra.
>=20

But the code is even more self-explanatory now :)

Fam

> > -    bdrv_set_in_use(blk->conf.bs, 1);
> > +    error_setg(&s->blocker, "block device is in use by data plane");
> > +    bdrv_op_block_all(blk->conf.bs, s->blocker);
> > =20
> >      *dataplane =3D s;
> >  }