Am 05.06.2019 um 19:16 hat Vladimir Sementsov-Ogievskiy geschrieben: > 05.06.2019 20:11, Kevin Wolf wrote: > > Am 05.06.2019 um 14:32 hat Vladimir Sementsov-Ogievskiy geschrieben: > >> child_role job already has .stay_at_node=true, so on bdrv_replace_node > >> operation these child are unchanged. Make block job blk behave in same > >> manner, to avoid inconsistent intermediate graph states and workarounds > >> like in mirror. > >> > >> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > > > > This feels dangerous. It does what you want it to do if the only graph > > change below the BlockBackend is the one in mirror_exit_common. But the > > user could also take a snapshot, or in the future hopefully insert a > > filter node, and you would then want the BlockBackend to move. > > > > To be honest, even BdrvChildRole.stay_at_node is a bit of a hack. But at > > least it's only used for permissions and not for the actual data flow. > > Hmm. Than, may be just add a parameter to bdrv_replace_node, which parents > to ignore? Would it work?
I would have to think a bit more about it, but it does sound safer. Or we take a step back and ask why it's even a problem for the mirror block job if the BlockBackend is moved to a different node. The main reason I see is because of bs->job that is set for the root node of the BlockBackend and needs to be unset for the same node. Maybe we can just finally get rid of bs->job? It doesn't have many users any more. Kevin
