Re: [Qemu-block] [PATCH] qemu-iotests: Extend non-shared storage migration test (194)

[Eric Blake]

On 08/28/2017 06:29 AM, Kashyap Chamarthy wrote:
> This is the follow-up patch that was discussed[*] as part of feedback to
> qemu-iotest 194.
> 
> Changes in this patch:
> 
>   - Supply 'job-id' parameter to `drive-mirror` invocation.
> 
>   - Issue `block-job-cancel` command on the source QEMU to gracefully
>     complete the mirroring operation.
> 
>   - Stop the NBD server on the destination QEMU.
> 
>   - Finally, exit once the event BLOCK_JOB_COMPLETED is emitted.
> 
> With the above, the test will also be (almost) in sync with the
> procedure outlined in the document live-block-operations.rst[+]
> (section: "QMP invocation for live storage migration with
> ``drive-mirror`` + NBD").
> 
> [*] https://lists.nongnu.org/archive/html/qemu-devel/2017-08/msg04820.html
>     -- qemu-iotests: add 194 non-shared storage migration test
> [+] 
> https://git.qemu.org/gitweb.cgi?p=qemu.git;a=blob;f=docs/interop/live-block-operations.rst
> 
> Signed-off-by: Kashyap Chamarthy <address@hidden>
> ---
> I wonder:
>   - Is it worth printing the MIGRATION event state change?

I think waiting for both the BLOCK_JOB_COMPLETED and MIGRATION events
make sense (in other words, let's check both events in the expected
order, rather than just one or the other).

>   - Since we're not checking on the MIGRATION event anymore, can
>     the migration state change events related code (that is triggerred
>     by setting 'migrate-set-capabilities') be simply removed?

If we're going to mirror libvirt's non-shared storage migration
sequence, I think we want to keep everything, rather than drop the
migration half.

> ---
>  tests/qemu-iotests/194     | 17 ++++++++++++-----
>  tests/qemu-iotests/194.out | 14 ++++++++------
>  2 files changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/tests/qemu-iotests/194 b/tests/qemu-iotests/194
> index 
> 8028111e21bed5cf4a2e8e32dc04aa5a9ea9caca..8d746be9d0033f478f11886ee93f95b0fa55bab0
>  100755
> --- a/tests/qemu-iotests/194
> +++ b/tests/qemu-iotests/194
> @@ -46,16 +46,17 @@ iotests.log('Launching NBD server on destination...')
>  iotests.log(dest_vm.qmp('nbd-server-start', addr={'type': 'unix', 'data': 
> {'path': nbd_sock_path}}))
>  iotests.log(dest_vm.qmp('nbd-server-add', device='drive0', writable=True))
>  
> -iotests.log('Starting drive-mirror on source...')
> +iotests.log('Starting `drive-mirror` on source...')
>  iotests.log(source_vm.qmp(
>                'drive-mirror',
>                device='drive0',
>                target='nbd+unix:///drive0?socket={0}'.format(nbd_sock_path),
>                sync='full',
>                format='raw', # always raw, the server handles the format
> -              mode='existing'))
> +              mode='existing',
> +              job_id='mirror-job0'))
>  
> -iotests.log('Waiting for drive-mirror to complete...')
> +iotests.log('Waiting for `drive-mirror` to complete...')

So, up to here is okay,

>  iotests.log(source_vm.event_wait('BLOCK_JOB_READY'),
>              filters=[iotests.filter_qmp_event])
>  
> @@ -66,8 +67,14 @@ dest_vm.qmp('migrate-set-capabilities',
>              capabilities=[{'capability': 'events', 'state': True}])
>  iotests.log(source_vm.qmp('migrate', 
> uri='unix:{0}'.format(migration_sock_path)))
>  
> +iotests.log('Gracefully ending the `drive-mirror` job on source...')
> +iotests.log(source_vm.qmp('block-job-cancel', device='mirror-job0'))
> +
> +iotests.log('Stopping the NBD server on destination...')
> +iotests.log(dest_vm.qmp('nbd-server-stop'))
> +
>  while True:
> -    event = source_vm.event_wait('MIGRATION')
> +    event = source_vm.event_wait('BLOCK_JOB_COMPLETED')

And this event makes sense for catching the block-job-cancel, but I
think you STILL want to keep a while loop for catching migration as well.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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