On 11/17/2017 10:25 AM, Kashyap Chamarthy wrote: > When you cancel an in-progress live block operation with QMP > `block-job-cancel`, it emits the event: BLOCK_JOB_CANCELLED. However, > when `block-job-cancel` is issued after `drive-mirror` has indicated (by > emitting the event BLOCK_JOB_READY) that the source and destination > remain synchronized: >
> But this is expected behaviour, where the _COMPLETED event indicates
> that synchronization has successfully ended (and the destination has a
> point-in-time copy, which is at the time of cancel).
>
> So add a small note to this effect in 'block-core.json'. While at it,
> also update the "Live disk synchronization -- drive-mirror and
> blockdev-mirror" section in 'live-block-operations.rst'.
>
> (Thanks: Max Reitz for reminding me of this caveat on IRC.)
Sorry for not wordsmithing on earlier versions:
>
> Signed-off-by: Kashyap Chamarthy <kcham...@redhat.com>
> ---
> +.. note::
> +
> + When you cancel an in-progress 'mirror' job *before* the source and
> + target are synchronized, ``block-job-cancel`` will emit the event
> + ``BLOCK_JOB_CANCELLED``. However, note that if you cancel a
> + 'mirror' job *after* it has indicated (by emitting the event
> + ``BLOCK_JOB_READY``) that the source and target now remain
> + synchronized, then ``block-job-cancel`` will emit the event
Might read slightly nicer as:
the source and target have reached synchronization,
> +++ b/qapi/block-core.json
> @@ -2065,6 +2065,14 @@
> # BLOCK_JOB_CANCELLED event. Before that happens the job is still visible
> when
> # enumerated using query-block-jobs.
> #
> +# Note that the 'block-job-cancel' command will emit the event
> +# BLOCK_JOB_COMPLETED if you issue it ('block-job-cancel') after
> 'drive-mirror'
> +# has indicated (by emitting the event BLOCK_JOB_READY) that the source and
> +# destination remain synchronized. In this case, the BLOCK_JOB_COMPLETED
> +# event indicates that synchronization (from 'drive-mirror') has successfully
> +# ended and the destination now has a point-in-time copy, which is at the
> time
> +# of cancel.
Accurate, but a bit hard to follow the flow of the sentence. Might read
nicer as:
Note that if you issue 'block-job-cancel' after 'drive-mirror' has
indicated (via the event BLOCK_JOB_READY) that the source and
destination are synchronized, then the event triggered by this command
changes to BLOCK_JOB_COMPLETED, to indicate that the mirroring has ended
and the destination now has a point-in-time copy tied to the time of the
cancellation.
Documentation is worth of inclusion in 2.11. Whether you keep your
wording, or incorporate mine in a v4, you can add:
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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