On 21/03/2016 18:30, Markus Armbruster wrote: > However, I've now tested my expectation, and it turned out to be wrong. > I'm inclined to call that a bug.
--verbose, what is wrong and what was your expectation? > > In other words, you said "This looks like DriveInfo now owns a reference > > to BlockBackend, even though the pointer still goes in the other > > direction". I say, "I thought this was the idea all along"... > > For me, the DriveInfo doesn't own anything, but a BlockBackend may have > a DriveInfo. Evidence: > > * The pointer goes from the BlockBackend to the DriveInfo > > * To go back, you search the blk_backends for the one that has the > DriveInfo. See blk_by_legacy_dinfo(). > > * There is no list of DriveInfo. If you want to find one, you search > blk_backends. See drive_get() & friends. That's from the point of view of the code. But from the point of view of the user, he specifies a drive=... and the device converts that under the hood to a BlockBackend; and when he calls drive_del on an unassigned drive, the BlockBackend is destroyed. There is no action on a BlockBackend that destroys the DriveInfo---except auto-deletion on unplug, but even then the user in the first place had provided a DriveInfo. So from the point of view of the user it's always been the DriveInfo that owned a BlockBackend. The lack of a list of DriveInfo is just an implementation detail. Paolo
