Re: [Qemu-devel] [PATCH v6 12/21] qmp: Add dirty bitmap status field in query-block

[Eric Blake <eblake@redhat.com>]

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On 04/17/2015 05:50 PM, John Snow wrote:
> Add the "frozen" status booleans, to inform clients
> when a bitmap is occupied doing a task.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> ---
>  block.c              | 1 +
>  qapi/block-core.json | 5 ++++-
>  2 files changed, 5 insertions(+), 1 deletion(-)

> +++ b/qapi/block-core.json
> @@ -336,10 +336,13 @@
>  #
>  # @granularity: granularity of the dirty bitmap in bytes (since 1.4)
>  #
> +# @frozen: whether the dirty bitmap is frozen (Since 2.4)
> +#
>  # Since: 1.3
>  ##
>  { 'type': 'BlockDirtyInfo',
> -  'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32'} }
> +  'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32',
> +           'frozen': 'bool'} }

Just thinking aloud here - internally, we have a tri-state situation
(enabled, disabled, or frozen).  I know we aren't exposing disabled to
the end user yet (no use case for that), but would it be better to make
this output an enum type (two values for now, 'enabled' and 'frozen') to
make it easier to add a third value later, without having to add yet
another boolean?

But it's not the end of the world to expose a single boolean now (we'd
just have to maintain it forever, even if we add later states), and
adding an enum now just adds complexity that we may not need, so:

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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