Re: [Qemu-devel] [PATCH v2 1/2] block: Allow x-blockdev-del on a BB with a monitor-owned BDS

[Alberto Garcia <berto@igalia.com>]

On Fri 26 Feb 2016 09:58:54 AM CET, Kevin Wolf wrote:
>> I think your case is reasonable, but it's not the only way to get
>> into this situation. See for example this one:
>> 
>> blockdev-add 'drive0', 'node0'
>> blockdev-add 'node1'
>> blockdev-snapshot node='node0' overlay='node1'
>> 
>> Now you have 'drive0' with 'node0' <- 'node1'.
>> 
>> You cannot simply remove 'drive0', you need to eject 'node1' first
>> and then you can remove 'drive0' and 'node1'.
>
> I think this is even more a reason not to introduce any magic but to
> require that node and BB be removed separately. Otherwise it will
> become really confusing to track for management software which node is
> supposed to automatically go away and which isn't.

Note that with this patch you still need to remove the node and the BB
separately, it only spares you to eject a node that was not explicitly
inserted in the first place.

That said, I think Max's example convinced me that this is not as clear
as I initially thought, so if you're not convinced either I have no
problem to withdraw the patch.

Thanks,

Berto