Re: [PATCH v2 11/15] block/export: Add option to allow export of inactive nodes

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Fri, Jan 31, 2025 at 10:50:47AM +0100, Kevin Wolf wrote:
> Add an option in BlockExportOptions to allow creating an export on an
> inactive node without activating the node. This mode needs to be
> explicitly supported by the export type (so that it doesn't perform any
> operations that are forbidden for inactive nodes), so this patch alone
> doesn't allow this option to be successfully used yet.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  qapi/block-export.json             | 10 +++++++++-
>  include/block/block-global-state.h |  3 +++
>  include/block/export.h             |  3 +++
>  block.c                            |  4 ++++
>  block/export/export.c              | 31 ++++++++++++++++++++----------
>  5 files changed, 40 insertions(+), 11 deletions(-)
> 
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index ce33fe378d..117b05d13c 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
> @@ -372,6 +372,13 @@
>  #     cannot be moved to the iothread.  The default is false.
>  #     (since: 5.2)
>  #
> +# @allow-inactive: If true, the export allows the exported node to be inactive.
> +#     If it is created for an inactive block node, the node remains inactive. If
> +#     the export type doesn't support running on an inactive node, an error is
> +#     returned. If false, inactive block nodes are automatically activated before
> +#     creating the export and trying to inactivate them later fails.
> +#     (since: 10.0; default: false)

Exposing activation in the API is ugly but I don't see a cleaner option
given that we cannot change block-export-add's existing behavior of
activating the node by default. :(

Ideally block-export-add would not modify active/inactive and leave it
up to user to provide a node in the desired state.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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