Re: [Qemu-devel] [PATCH v6 1/4] block: Add zoned device model property

[Stefano Garzarella]

On Fri, Sep 06, 2019 at 04:17:12PM +0000, Dmitry Fomichev wrote:
> On Fri, 2019-09-06 at 10:11 +0200, Stefano Garzarella wrote:
> > On Wed, Sep 04, 2019 at 05:00:57PM -0400, Dmitry Fomichev wrote:
> > > This commit adds Zoned Device Model (as defined in T10 ZBC and
> > > T13 ZAC standards) as a block driver property, along with some
> > > useful access functions.
> > > 
> > > A new backend driver permission, BLK_PERM_SUPPORT_HM_ZONED, is also
> > > introduced. Only the drivers having this permission will be allowed
> > > to open host managed zoned block devices.
> > > 
> > > No code is added yet to initialize or check the value of this new
> > > property, therefore this commit doesn't change any functionality.
> > > 
> > > Signed-off-by: Dmitry Fomichev <address@hidden>
> > > ---
> > >  block.c                   | 15 +++++++++++++++
> > >  include/block/block.h     | 19 ++++++++++++++++++-
> > >  include/block/block_int.h |  3 +++
> > >  3 files changed, 36 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/block.c b/block.c
> > > index 874a29a983..69f565e1e9 100644
> > > --- a/block.c
> > > +++ b/block.c
> > > @@ -4679,6 +4679,21 @@ void bdrv_get_geometry(BlockDriverState *bs, 
> > > uint64_t *nb_sectors_ptr)
> > >      *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
> > >  }
> > >  
> > > +BdrvZonedModel bdrv_get_zoned_model(BlockDriverState *bs)
> > > +{
> > > +    return bs->bl.zoned_model;
> > > +}
> > > +
> > > +bool bdrv_is_hm_zoned(BlockDriverState *bs)
> > > +{
> > > +    /*
> > > +     * Host Aware zone devices are supposed to be able to work
> > > +     * just like regular block devices. Thus, we only consider
> > > +     * Host Managed devices to be zoned here.
> > > +     */
> > > +    return bdrv_get_zoned_model(bs) == BDRV_ZONED_MODEL_HM;
> > > +}
> > > +
> > >  bool bdrv_is_sg(BlockDriverState *bs)
> > >  {
> > >      return bs->sg;
> > > diff --git a/include/block/block.h b/include/block/block.h
> > > index 124ad40809..28d065ed80 100644
> > > --- a/include/block/block.h
> > > +++ b/include/block/block.h
> > > @@ -271,18 +271,33 @@ enum {
> > >       */
> > >      BLK_PERM_GRAPH_MOD          = 0x10,
> > >  
> > > +    /**
> > > +     * This permission is required to open host-managed zoned block 
> > > devices.
> > > +     */
> > > +    BLK_PERM_SUPPORT_HM_ZONED   = 0x20,
> > > +
> > >      BLK_PERM_ALL                = 0x1f,
> > 
> > Should we update BLK_PERM_ALL to 0x3f?
> > 
> Stefano, good catch! Will update and resend...
> 

Good!

Looking better, if we update it, maybe we should also change something in
xdbg_graph_add_edge() since there is this line:

    QEMU_BUILD_BUG_ON(1UL << (ARRAY_SIZE(permissions) - 1) != BLK_PERM_ALL + 1);

We should extend the permissions array or change this check.

Thanks,
Stefano