Re: [Qemu-devel] [PATCH] refresh filename after the node is replaced

[Max Reitz]

On 01.07.2015 03:08, Wen Congyang wrote:
> On 06/30/2015 09:17 PM, Max Reitz wrote:
> > On 29.06.2015 03:16, Wen Congyang wrote:
> > > On 06/26/2015 11:16 PM, Max Reitz wrote:
> > > > I see two solutions to this issue: Either, we do it right and that means, if 
> > > > there is a change in the BDS graph (e.g. because of bdrv_swap()),
> > > > we have to call bdrv_refresh_filename() on all of the changed BDS's parents. In 
> > > > order to be able to enumerate a BDS's parents, we need Kevin's
> > > > series, as said before.
> > > IIUC, the BDS can have more than one parent.
> > Indeed. Kevin's series adds a generalized parent-child relationship, which 
> > makes it possible to both enumerate all the children of a BDS and all its 
> > parents.
> How to get all its parents? Is this patch not merged into upstream?

The patch is actually already merged upstream 
(6e93e7c41fdfdee3068770cae79380e1d986b76a), but it does not add a way to 
enumerate a BDS's parents, only a BDS's children. It should not be too 
difficult to implement the reverse however, I guess, based on that patch.
Konsole output
> > > > Or we revive my series "block: Drop BDS.filename" which drops the BDS.filename 
> > > > field completely and always rebuilds it if it is queried.
> > > > This would fix the issue as well, however, there is a reason it has been lying 
> > > > around for nine months now, and that reason is that we did
> > > > not yet fully examine the impacts of dropping that field, especially concerning 
> > > > libvirt.
> > > If BDS.filename is dropped, this problem will go.
> > Right. But we have to make sure there won't be any negative impact if we do so, and 
> > because that is not really trivial, the series hasn't been applied yet and didn't receive 
> > further attention. Also, there was no real reason to do it other than "Because we 
> > can" until now. But I think the issue mentioned here is a good reason why we should 
> > indeed reconsider it.
> I don't find this series.

Maybe because it's pretty old. :-) I sent it last September: 
http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg04878.html

Max