Re: [PATCH v4 4/4] qapi: Allow introspecting fix for savevm's cooperation with blockdev

[Markus Armbruster]

Kevin Wolf <address@hidden> writes:

> Am 11.10.2019 um 10:50 hat Markus Armbruster geschrieben:
>> From: Peter Krempa <address@hidden>
>> 
>> 'savevm' was buggy as it considered all monitor-owned block device
>> nodes for snapshot. With the introduction of -blockdev, the common
>> usage made all nodes including protocol and backing file nodes be
>> monitor-owned and thus considered for snapshot.
>> 
>> This is a problem since the 'file' protocol nodes can't have internal
>> snapshots and it does not make sense to take snapshot of nodes
>> representing backing files.
>> 
>> This was fixed by commit 05f4aced658a02b02. Clients need to be able to
>> detect whether this fix is present.
>> 
>> Since savevm does not have an QMP alternative, add the feature for the
>> 'human-monitor-command' backdoor which is used to call this command in
>> modern use.
>> 
>> Signed-off-by: Peter Krempa <address@hidden>
>> Reviewed-by: Markus Armbruster <address@hidden>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>  qapi/misc.json | 10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>> 
>> diff --git a/qapi/misc.json b/qapi/misc.json
>> index 6bd11f50e6..35dca86ce7 100644
>> --- a/qapi/misc.json
>> +++ b/qapi/misc.json
>> @@ -1020,6 +1020,13 @@
>>  #
>>  # @cpu-index: The CPU to use for commands that require an implicit CPU
>>  #
>> +# Features:
>> +
>
> I think you want a # in this empty line.

I'll delete the line instead, so the Features part looks like the one we
already have in block-core.json.

>> +# @savevm-monitor-nodes: If present, HMP command savevm only snapshots
>> +#                        monitor-owned nodes if they have no parents.
>> +#                        This allows the use of 'savevm' with
>> +#                        -blockdev. (since 4.2)
>> +#
>>  # Returns: the output of the command as a string
>>  #
>>  # Since: 0.14.0
>> @@ -1047,7 +1054,8 @@
>>  ##
>>  { 'command': 'human-monitor-command',
>>    'data': {'command-line': 'str', '*cpu-index': 'int'},
>> -  'returns': 'str' }
>> +  'returns': 'str',
>> +  'features': [ 'savevm-monitor-nodes' ] }
>
> With this fixed:
>
> Reviewed-by: Kevin Wolf <address@hidden>

Thanks!