Re: [Qemu-devel] [PATCH 22/54] block: Request real permissions in bdrv_attach_child()

[Kevin Wolf]

Am 22.02.2017 um 15:31 hat Max Reitz geschrieben:
> On 21.02.2017 15:58, Kevin Wolf wrote:
> > Now that all block drivers with children tell us what permissions they
> > need from each of their children, bdrv_attach_child() can use this
> > information and make the right requirements while trying to attach new
> > children.
> > 
> > Signed-off-by: Kevin Wolf <address@hidden>
> > ---
> >  block.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/block.c b/block.c
> > index 1c5f211..054e6f0 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -1659,10 +1659,14 @@ BdrvChild *bdrv_attach_child(BlockDriverState 
> > *parent_bs,
> >                               Error **errp)
> >  {
> >      BdrvChild *child;
> > +    uint64_t perm, shared_perm;
> > +
> > +    assert(parent_bs->drv);
> > +    parent_bs->drv->bdrv_child_perm(parent_bs, NULL, child_role,
> > +                                    0, BLK_PERM_ALL, &perm, &shared_perm);
> 
> Another Second Thought™: Why do we request no permissions for the new
> child here? Seems weird to me. Shouldn't the caller specify the
> necessary permissions and what can be shared?

Actually not the caller, but we should calculate the cumulative
permissions of parent_bs, like in bdrv_update_perm().

Kevin

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