Re: [Qemu-devel] [PATCH 3/3] block: change rollback sequence in qmp_transaction

[Kevin Wolf]

Am 03.04.2013 um 07:35 hat Wenchao Xia geschrieben:
> 于 2013-4-2 21:59, Kevin Wolf 写道:
> >Am 01.04.2013 um 12:01 hat Wenchao Xia geschrieben:
> >>   Last operaton should be cancelled first.
> >>
> >>Signed-off-by: Wenchao Xia <xiaw...@linux.vnet.ibm.com>
> >
> >Should it? This commit message does little to convince me.
> >
> >Kevin
> >
>   I think so, if two request are "snapshot_blkdev ide0 newimage.qcow2",
> "snapshot_blkdev_internal ide0 snap0", then in rollback delete of
> snap0 would be wrong.

I think this problem exists only because you didn't properly separate
the prepare and the commit stage. If any changes only took effect in a
non-failing commit stage, then you don't ever have to delete a snapshot.
Instead, you just abort the creation of the snapshot.

Kevin