δΊ 2013-4-10 23:11, Markus Armbruster ει:
> Eric Blake <[email protected]> writes:
>
>> On 04/02/2013 05:47 AM, Wenchao Xia wrote:
>>> This patch adds function bdrv_query_snapshot_info_list(), which will
>>> retrieve snapshot info of an image in qmp object format. The implementation
>>> is based on the code moved from qemu-img.c with modification to fit more
>>> for qmp based block layer API.
>>>
>>> Signed-off-by: Wenchao Xia <[email protected]>
>>> ---
>>> block/qapi.c | 55
>>> ++++++++++++++++++++++++++++++++++++++-----------
>>> include/block/qapi.h | 4 ++-
>>> qemu-img.c | 5 +++-
>>> 3 files changed, 49 insertions(+), 15 deletions(-)
>>
>>> +/*
>>> + * return 0 on success, @p_list will be set only on success, and caller
>>> need to
>>
>> s/need/needs/
>>
>>> + * check *p_list on success.
>>
>> I wonder if this wording would be any better:
>>
>> Returns 0 on success, with *p_list either set to describe snapshot
>> information, or NULL because there are no snapshots. Returns -1 on
>> error, with *p_list untouched.
>
> It actually returns -errno then, doesn't it?
>
Yes, I forgot change the comments in the version changing, thank you
for the carefully review.
>>
>>> + */
>>> +int bdrv_query_snapshot_info_list(BlockDriverState *bs,
>>> + SnapshotInfoList **p_list,
>>> + Error **errp)
>>> {
>>
>> At any rate, my only commentary was on grammar and a possible wording
>> for a comment, while the code itself is fine from my viewpoint; so feel
>> free to add:
>>
>> Reviewed-by: Eric Blake <[email protected]>
>>
>>> +++ b/qemu-img.c
>>> @@ -1735,7 +1735,10 @@ static ImageInfoList
>>> *collect_image_info_list(const char *filename,
>>>
>>> info = g_new0(ImageInfo, 1);
>>> bdrv_collect_image_info(bs, info, filename);
>>> - bdrv_collect_snapshots(bs, info);
>>> + if (!bdrv_query_snapshot_info_list(bs, &info->snapshots, NULL) &&
>>> + info->snapshots) {
>>> + info->has_snapshots = true;
>>> + }
>>
>> Hmm. info->snapshots starts life as NULL (thanks to g_new0), and is
>> untouched on error. Since you are ignoring any errors, you technically
>> could write:
>>
>> bdrv_query_snapshot_info_list(bs, &info->snapshots, NULL);
>> if (info->snapshots) {
>> info->has_snapshots = true;
>> }
>>
>> for the same semantics. That means that as of this commit, no caller
>> cares about the return value of bdrv_query_snapshot_info_list (they only
>> care about whether info->snapshots was changed to non-null), so it could
>> return void for a slightly simpler implementation.
>
> Return the list, or NULL.
>
>> But I don't know if any later patches in the series start to care about
>> which error was returned.
>
> Me neither :)
>
--
Best Regards
Wenchao Xia
