[Qemu-devel] [PATCH v2 0/2] blockdev: Overlays are not snapshots

[Max Reitz]

QEMU’s always been confused over what a snapshot is: Is it the overlay?
Is it the backing image?

Confusion is rarely a good thing.  I can’t think of any objective reason
why the overlay would be a snapshot.  A snapshot is something that does
not change over time; the overlay does.

(I suppose historically the reason is that “Taking an overlay” makes no
sense, so the operations are called “Taking a snapshot”.  Somehow, this
meaning carried over to the new file that is created during that
operation; if “Creating a snapshot” creates a file, that file must be
the snapshot, right?  Well, no, it isn’t.)

Let’s fix this as best as we can.  Better Nate than lever.


v2:
- Don’t break the iotests for a change
  (kept Eric’s R-b, because it felt like the right thing to do)


git backport-diff against v1:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/2:[----] [--] 'qapi/block-core: Overlays are not snapshots'
002/2:[0010] [FC] 'blockdev: Overlays are not snapshots'


Max Reitz (2):
  qapi/block-core: Overlays are not snapshots
  blockdev: Overlays are not snapshots

 qapi/block-core.json       | 20 ++++++++++----------
 blockdev.c                 | 10 +++++-----
 tests/qemu-iotests/085.out | 10 +++++-----
 3 files changed, 20 insertions(+), 20 deletions(-)

-- 
2.21.0