Re: [PATCH v4 5/5] iotests: add backup-discard-source

[Kevin Wolf <kwolf@redhat.com>]

Am 12.06.2024 um 21:21 hat Vladimir Sementsov-Ogievskiy geschrieben:
> On 11.06.24 20:49, Kevin Wolf wrote:
> > Am 13.03.2024 um 16:28 hat Vladimir Sementsov-Ogievskiy geschrieben:
> > > Add test for a new backup option: discard-source.
> > > 
> > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> > > Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
> > > Tested-by: Fiona Ebner <f.ebner@proxmox.com>
> > 
> > This test fails for me, and it already does so after this commit that
> > introduced it. I haven't checked what get_actual_size(), but I'm running
> > on XFS, so its preallocation could be causing this. We generally avoid
> > checking the number of allocated blocks in image files for this reason.
> > 
> 
> Hmm right, I see that relying on allocated size is bad thing. Better
> is to check block status, to see how many qcow2 clusters are
> allocated.
> 
> Do we have some qmp command to get such information? The simplest way
> I see is to add dirty to temp block-node, and then check its dirty
> count through query-named-block-nodes

Hm, does it have to be QMP in a running QEMU process? I'm not sure what
the best way would be there.

Otherwise, my approach would be 'qemu-img check' or even 'qemu-img map',
depending on what you want to verify with it.

Kevin