Re: [PATCH v4 5/5] block: Deprecate transaction type drive-backup

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> On Mon, Oct 25, 2021 at 12:24 AM Markus Armbruster <armbru@redhat.com>
> wrote:
>
>> Several moons ago, Vladimir posted
>>
>>     Subject: [PATCH v2 3/3] qapi: deprecate drive-backup
>>     Date: Wed,  5 May 2021 16:58:03 +0300
>>     Message-Id: <20210505135803.67896-4-vsementsov@virtuozzo.com>
>>     https://lists.gnu.org/archive/html/qemu-devel/2021-05/msg01394.html
>>
>> with this
>>
>>     TODO: We also need to deprecate drive-backup transaction action..
>>     But union members in QAPI doesn't support 'deprecated' feature. I tried
>>     to dig a bit, but failed :/ Markus, could you please help with it? At
>>     least by advice?
>>
>> This is one way to resolve it.  Sorry it took so long.
>>
>>
> I'll share the blame for not pushing back on the other series, but ...
>
>
>> John explored another way, namely adding feature flags to union
>> branches.  Could also be useful, say to add different features to
>> branches in multiple unions sharing the same tag enum.
>>
>>
> ... this way seems simpler for now, and I trust your intuition on what's
> easier to support as I don't have a solid grasp of the C interfaces at play
> for actually parsing the input. We can always revisit the other thing later
> if/when we need it.
>
>
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> ---
>>  qapi/transaction.json | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/qapi/transaction.json b/qapi/transaction.json
>> index d175b5f863..381a2df782 100644
>> --- a/qapi/transaction.json
>> +++ b/qapi/transaction.json
>> @@ -54,6 +54,10 @@
>>  # @blockdev-snapshot-sync: since 1.1
>>  # @drive-backup: Since 1.6
>>  #
>> +# Features:
>> +# @deprecated: Member @drive-backup is deprecated.  Use member
>> +#              @blockdev-backup instead.
>> +#
>>  # Since: 1.1
>>  ##
>>  { 'enum': 'TransactionActionKind',
>> @@ -62,7 +66,7 @@
>>              'block-dirty-bitmap-disable', 'block-dirty-bitmap-merge',
>>              'blockdev-backup', 'blockdev-snapshot',
>>              'blockdev-snapshot-internal-sync', 'blockdev-snapshot-sync',
>> -            'drive-backup' ] }
>> +            { 'name': 'drive-backup', 'features': [ 'deprecated' ] } ] }
>>
>>  ##
>>  # @AbortWrapper:
>> --
>> 2.31.1
>>
>>
> Seems pretty clean to me overall. What's the reason for wanting it to be
> RFC?

I believe it depends on the remainder of Vladimir's series.