On 04/23/2015 05:00 PM, Kevin Wolf wrote: > Am 22.04.2015 um 12:12 hat Paolo Bonzini geschrieben: >> On 22/04/2015 11:31, Kevin Wolf wrote: >>>> Actually I liked the "foo+colo" names. >>>> >>>> These are just internal details of the implementations and the >>>> primary/secondary disks actually can be any format. >>>> >>>> Stefan, what was your worry with the +colo block drivers? >>> >>> I haven't read the patches yet, so I may be misunderstanding, but >>> wouldn't a separate filter driver be more appropriate than modifying >>> qcow2 with logic that has nothing to do with the image format? >> >> Possibly; on the other hand, why multiply the size of the test matrix >> with options that no one will use and that will bitrot? > > Because it may be the right design. > > If you're really worried about the test matrix, put a check in the > filter block driver that its bs->file is qcow2. Of course, such an > artificial restriction looks a bit ugly, but using a bad design just > in order to get the same restriction is even worse.
The bs->file->driver should support backing file, and use backing reference already. What about the primary side? We should control when to connect to NBD server, not in nbd_open(). Thanks Wen Congyang > > Stefan originally wanted to put image streaming in the QED driver. I > think we'll agree today that it was right to reject that. It's simply > not functionality related to the format. Adding replication logic to > qcow2 looks similar to me in that respect. > > Kevin > . >
