Re: [Qemu-devel] [PATCH 4/4] qmp: Add optional switch "query-nodes" in query-blockstats

[Max Reitz <mreitz@redhat.com>]

On 2014-10-31 at 04:20, Fam Zheng wrote:
> On Wed, 10/29 10:11, Max Reitz wrote:
>> On 2014-10-29 at 06:04, Fam Zheng wrote:
>>> This bool option will allow query all the node names. It iterates all
>>> the BDSes that are assigned a name, also in this case don't query up the
>>> backing chain.
>>>
>>> Signed-off-by: Fam Zheng <famz@redhat.com>
>>> ---
>>>   block/qapi.c         | 20 +++++++++++++-------
>>>   hmp.c                |  2 +-
>>>   qapi/block-core.json |  4 +++-
>>>   qmp-commands.hx      |  2 +-
>>>   4 files changed, 18 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/block/qapi.c b/block/qapi.c
>>> index a4d1a20..e26033e 100644
>>> --- a/block/qapi.c
>>> +++ b/block/qapi.c
>>> @@ -322,7 +322,8 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
>>>       qapi_free_BlockInfo(info);
>>>   }
>>> -static BlockStats *bdrv_query_stats(const BlockDriverState *bs)
>>> +static BlockStats *bdrv_query_stats(const BlockDriverState *bs,
>>> +                                    bool query_backing)
>>>   {
>>>       BlockStats *s;
>>> @@ -352,12 +353,12 @@ static BlockStats *bdrv_query_stats(const BlockDriverState *bs)
>>>       if (bs->file) {
>>>           s->has_parent = true;
>>> -        s->parent = bdrv_query_stats(bs->file);
>>> +        s->parent = bdrv_query_stats(bs->file, query_backing);
>>>       }
>>> -    if (bs->backing_hd) {
>>> +    if (query_backing && bs->backing_hd) {
>>>           s->has_backing = true;
>>> -        s->backing = bdrv_query_stats(bs->backing_hd);
>>> +        s->backing = bdrv_query_stats(bs->backing_hd, query_backing);
>>>       }
>> Is there a specific reason why you're not querying the backing chain but
>> still recurse to bs->file?
> Unlike its backing, there can be some information in ->file which is
> interesting to the node itself, because it is ->file carries out the actual
> read/write on the image. Makes sense?

Ah, I forgot to answer. Well, ->backing carries out reads, too. I 
thought you omitted it because you could give it a node-name as well and 
therefore you'd have some BDS appear twice; but the same applies  to 
->file, that's why I asked.

Max