Re: [Qemu-devel] [RFC PATCH 0/3] Point-in-time snapshot exporting with drive-backup

[Paolo Bonzini]

Il 27/06/2013 10:17, Stefan Hajnoczi ha scritto:
>>> > > Il 26/06/2013 05:59, Fam Zheng ha scritto:
>>> > > This leads to another observation: a sync:'none' block-backup job
>>> > > probably should never complete, and should instead go on until explicit
>>> > > cancellation.  This is because the job does no background writes, and
>>> > > thus completion would only happen after the guest has written the whole
>>> > > disk.  Writing the whole disk is rare enough that it will likely cause
>>> > > bugs in the clients.  It is easier just to never complete the job.
>>> > > 
>> > 
>> > Yes, the sync mode none will simply run forever until cancelled.
> There is a dedicated command to successfully complete a job:
> 
> block-job-complete

block-job-complete should only be called after a BLOCK_JOB_READY event,
but when would the backup job raise it?  Immediately after starting?

There is no behavioral difference in this case between cancel and
complete in fact as far as I understand, so I think cancelling the job
would match existing practice better.

Paolo