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

[Kevin Wolf <kwolf@redhat.com>]

Am 11.10.2019 um 10:50 hat Markus Armbruster geschrieben:
> From: Peter Krempa <pkrempa@redhat.com>
> 
> '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 <pkrempa@redhat.com>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  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.

> +# @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 <kwolf@redhat.com>