Re: [Qemu-block] [Qemu-devel] [PATCH 2/3] virtio-blk: Use blk_drain() to drain IO requests

[Stefan Hajnoczi]

On Thu, Jun 11, 2015 at 10:51:54AM +0800, Fam Zheng wrote:
> On Wed, 06/10 14:38, Alexander Yarygin wrote:
> > Each call of the virtio_blk_reset() function calls blk_drain_all(),
> > which works for all existing BlockDriverStates, while draining only
> > one is needed.
> > 
> > This patch replaces blk_drain_all() by blk_drain() in virtio_blk_reset().
> 
> Please add a note "virtio_blk_data_plane_stop should be called after draining
> because it restores vblk->complete_request" as well.
> > 
> > Cc: Christian Borntraeger <address@hidden>
> > Cc: Cornelia Huck <address@hidden>
> > Cc: Kevin Wolf <address@hidden>
> > Cc: Paolo Bonzini <address@hidden>
> > Cc: Stefan Hajnoczi <address@hidden>
> 
> Cc: address@hidden
> 
> > Signed-off-by: Alexander Yarygin <address@hidden>
> > ---
> >  hw/block/virtio-blk.c | 11 ++++++-----
> >  1 file changed, 6 insertions(+), 5 deletions(-)
> > 
> > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> > index e6afe97..2009092 100644
> > --- a/hw/block/virtio-blk.c
> > +++ b/hw/block/virtio-blk.c
> > @@ -652,15 +652,16 @@ static void virtio_blk_reset(VirtIODevice *vdev)
> >  {
> >      VirtIOBlock *s = VIRTIO_BLK(vdev);
> >  
> > -    if (s->dataplane) {
> > -        virtio_blk_data_plane_stop(s->dataplane);
> > -    }
> > -
> >      /*
> >       * This should cancel pending requests, but can't do nicely until there
> >       * are per-device request lists.
> >       */
> 
> This comment can be dropped now.

The comment still has value.

bdrv_drain != cancel pending requests

We're using the per-device request list now but we're not cancelling
yet.  The comment hasn't been fully addressed.

Stefan

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