On 10.06.2016 20:57, Max Reitz wrote: > Issue #1: If the target image does not have a backing BDS before mirror > completion, qemu tries really hard to give it a backing BDS. If the > source has a backing BDS, it will actually always "succeed". > In some cases, the target is not supposed to have a backing BDS, though > (absolute-paths: because of sync=full; existing: because the target > image does not have a backing file; blockdev-mirror: because of an > explicit "backing": ""). Then, this is pretty bad behavior. > > This should generally not change the target's visible data, but it still > is ugly. > > Issue #2: Currently the backing chain of the target is basically opened > using bdrv_open_backing_file() (except for sometimes™). This results in > multiple BDSs for a single physical file, which is bad. In most use > cases, this is only temporary, but it still is bad. > > If we can reuse the existing backing chain of the source (which is with > drive-mirror in "absolute-paths" mode), we should just do so.
Following encouragement from Kevin on IRC, and apparently his acceptance of my commit message proposal for patch 3, I have applied the series to my block branch with said commit message added to patch 3 and the superfluous imports removed from patch 4 (thanks, Fam!). Max
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