Re: [PATCH 1/2] block: make bdrv_drop_intermediate() less wrong

[Vladimir Sementsov-Ogievskiy]

05.11.2020 18:14, Alberto Garcia wrote:
> On Sat 31 Oct 2020 01:35:01 PM CET, Vladimir Sementsov-Ogievskiy wrote:
> > -    QLIST_FOREACH_SAFE(c, &top->parents, next_parent, next) {
>    /* ... */
> > +    QLIST_FOREACH_SAFE(c, &base->parents, next_parent, next) {
>
> I also wonder, is top->parents and base->parents guaranteed to be the
> same list in this case?
>
> If not you could store the list of top->parents before calling
> bdrv_replace_node() and use it afterwards.
>
>      QLIST_FOREACH(c, &top->parents, next_parent) {
>          parents = g_slist_prepend(parents, c);
>      }
>
> Berto

Hmm... We should not touch other parents of base, which it had prior to 
bdrv_replace_node().

On the other hand, it should be safe to call update_filename for not-updated 
parents..

And we should keep in mind that bdrv_replace_node may replace not all children. 
Still, in this
case we must replace all of them. Seems, we need additional argument for 
bdrv_replace_node()
to fail, if it want's to skip some children replacement.

So, I'm going to resend to add this parameter to bdrv_replace_node() and will 
use your
suggestion to be stricter on what we update, thanks!


--
Best regards,
Vladimir