Re: [PATCH 2/2] vhost-user-blk: support inflight migration

[Markus Armbruster <armbru@redhat.com>]

Alexandr Moshkov <dtalexundeer@yandex-team.ru> writes:

> In vhost_user_blk_stop() on incoming migration make force_stop = true,
> so GET_VRING_BASE will not be executed.
>
> Signed-off-by: Alexandr Moshkov <dtalexundeer@yandex-team.ru>

Your cover letter explains why this is useful.  Please work it into your
commit message.

[...]

> diff --git a/qapi/migration.json b/qapi/migration.json
> index be0f3fcc12..c9fea59515 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -517,9 +517,13 @@
>  #     each RAM page.  Requires a migration URI that supports seeking,
>  #     such as a file.  (since 9.0)
>  #
> +# @inflight-vhost-user-blk: If enabled, QEMU will migrate inflight
> +#    region for vhost-user-blk.  (since 10.2)
> +#

Any guidance why and when users would want to enable it?

Is it a good idea to have device-specific capabilities?

>  # Features:
>  #
> -# @unstable: Members @x-colo and @x-ignore-shared are experimental.
> +# @unstable: Members @x-colo and @x-ignore-shared,
> +#     @inflight-vhost-user-blk are experimental.

"and" is misplaced now.  Fix:

   # @unstable: Members @x-colo, @x-ignore-shared, and
   #     @inflight-vhost-user-blk are experimental.

Use the opportunity and insert a blank line here.

>  # @deprecated: Member @zero-blocks is deprecated as being part of
>  #     block migration which was already removed.
>  #
> @@ -536,7 +540,8 @@
>             { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
>             'validate-uuid', 'background-snapshot',
>             'zero-copy-send', 'postcopy-preempt', 'switchover-ack',
> -           'dirty-limit', 'mapped-ram'] }
> +           'dirty-limit', 'mapped-ram',
> +           { 'name': 'inflight-vhost-user-blk', 'features': [ 'unstable' ] } ] }

Long line.  Obvious line break:

              { 'name': 'inflight-vhost-user-blk',
                'features': [ 'unstable' ] } ] }

>  
>  ##
>  # @MigrationCapabilityStatus: