Re: [Qemu-devel] [PATCH 1/2] block: allow live commit of active image

[Paolo Bonzini]

Il 22/07/2013 08:48, Fam Zheng ha scritto:
>> > I have only skimmed the patch, but I think this is incomplete.
>> > Management needs to know the moment when 'active' is not valid anymore,
>> > thus this job needs to be completed manually with "block-job-complete".
> Does management need access to 'active' image outside of QEMU process?
> Although original 'active' it is "dropped" by bdrv_drop_intermediate,
> the pointers to original 'active' is still valid because 'base' is moved
> to this address (with bdrv_swap). I don't know, what is the problem here
> for management?

Management needs to know, in case of a crash in QEMU or management
itself at exactly the right time, whether any I/O have been issued by
the guest to the 'base'.  The only way to do this is, at this time,
something like

    stop
    block-job-complete ide0-hd0
    cont

Paolo