Re: [Qemu-block] [PATCH RFC 2/7] block-backend: Introduce blk_root() helper

[Hailiang Zhang]

On 2016/10/25 17:58, Changlong Xie wrote:
> I know you need blk->root in the next patch, but we strongly don't
> recommend your current solution.  Please refer Kevin's cf2ab8fc
>
> 1409     /* XXX Ugly way to get blk->root, but that's a feature, not a
> bug. This
> 1410      * hack makes it obvious that vhdx_write_header() bypasses the
> BlockBackend
> 1411      * here, which it really shouldn't be doing. */
> 1412     child = QLIST_FIRST(&bs->parents);
> 1413     assert(!QLIST_NEXT(child, next_parent));
>
> Then you can drop this commit.

OK, got it, I'll drop this patch in next version, thanks.

> On 10/20/2016 09:57 PM, zhanghailiang wrote:
> > With this helper function, we can get the BdrvChild struct
> > from BlockBackend
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > ---
> >    block/block-backend.c          | 5 +++++
> >    include/sysemu/block-backend.h | 1 +
> >    2 files changed, 6 insertions(+)
> >
> > diff --git a/block/block-backend.c b/block/block-backend.c
> > index 1a724a8..66387f0 100644
> > --- a/block/block-backend.c
> > +++ b/block/block-backend.c
> > @@ -389,6 +389,11 @@ BlockDriverState *blk_bs(BlockBackend *blk)
> >        return blk->root ? blk->root->bs : NULL;
> >    }
> >
> > +BdrvChild *blk_root(BlockBackend *blk)
> > +{
> > +    return blk->root;
> > +}
> > +
> >    static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
> >    {
> >        BdrvChild *child;
> > diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
> > index b07159b..867f9f5 100644
> > --- a/include/sysemu/block-backend.h
> > +++ b/include/sysemu/block-backend.h
> > @@ -99,6 +99,7 @@ void blk_remove_bs(BlockBackend *blk);
> >    void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs);
> >    bool bdrv_has_blk(BlockDriverState *bs);
> >    bool bdrv_is_root_node(BlockDriverState *bs);
> > +BdrvChild *blk_root(BlockBackend *blk);
> >
> >    void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
> >    void blk_iostatus_enable(BlockBackend *blk);
>
>
>
> .