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* [Qemu-devel] [PATCH v2 0/2] blockdev: Overlays are not snapshots
@ 2019-06-03 20:22 Max Reitz
  2019-06-03 20:22 ` [Qemu-devel] [PATCH v2 1/2] qapi/block-core: " Max Reitz
                   ` (4 more replies)
  0 siblings, 5 replies; 7+ messages in thread
From: Max Reitz @ 2019-06-03 20:22 UTC (permalink / raw)
  To: qemu-block; +Cc: Kevin Wolf, Markus Armbruster, qemu-devel, 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



^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-06-13 19:52 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-06-03 20:22 [Qemu-devel] [PATCH v2 0/2] blockdev: Overlays are not snapshots Max Reitz
2019-06-03 20:22 ` [Qemu-devel] [PATCH v2 1/2] qapi/block-core: " Max Reitz
2019-06-05  5:43   ` Markus Armbruster
2019-06-03 20:22 ` [Qemu-devel] [PATCH v2 2/2] blockdev: " Max Reitz
2019-06-03 22:09 ` [Qemu-devel] [Qemu-block] [PATCH v2 0/2] " John Snow
2019-06-04  8:40 ` Alberto Garcia
2019-06-13 19:41 ` [Qemu-devel] " Max Reitz

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