Re: [Qemu-devel] [PATCH V7 08/14] qmp: add interface query-images.

[Wenchao Xia]

于 2013-2-28 0:00, Markus Armbruster 写道:
> Humor me: no period at end of subject, please
> 
  OK.

> First pass, concentrating on interfaces, implementation mostly ignored.
> 
> Wenchao Xia <address@hidden> writes:
> 
>>    This mirror function will return all image info including
>> snapshots, if specified backing image's info will also be returned.
>> Now Qemu have both query-images and query-block interfaces.
>>
>> Signed-off-by: Wenchao Xia <address@hidden>
>> ---
>>   block.c          |   83 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   qapi-schema.json |   34 ++++++++++++++++++++++
>>   qmp-commands.hx  |   76 +++++++++++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 193 insertions(+), 0 deletions(-)
>>
> [...]
>> diff --git a/qapi-schema.json b/qapi-schema.json
>> index cd7ea25..9122bb9 100644
>> --- a/qapi-schema.json
>> +++ b/qapi-schema.json
>> @@ -245,6 +245,22 @@
>>              '*backing-filename-format': 'str', '*snapshots': 
>> ['SnapshotInfo'] } }
>>   
>>   ##
>> +# @DeviceImageInfo:
>> +#
>> +# Information about an image used by a QEMU block device
>> +#
>> +# @device: name of the block device
>> +#
>> +# @image: #optional info of the image used
>> +#
>> +# Since: 1.5
>> +#
>> +##
>> +
>> +{ 'type': 'DeviceImageInfo',
>> +  'data': {'device': 'str', '*image': 'ImageInfo' } }
>> +
>> +##
>>   # @StatusInfo:
>>   #
>>   # Information about VCPU run state
>> @@ -789,6 +805,24 @@
>>   { 'command': 'query-block', 'returns': ['BlockInfo'] }
>>   
>>   ##
>> +# @query-images:
>> +#
>> +# Get a list of DeviceImageInfo for all virtual block devices.
> 
> # Get block device image information
> 
  OK.

>> +#
>> +# @device: #optional the name of the device to get image info from. If not
>> +#          specified, all block devices will be queried
>> +# @backing: #optional true to show information on backing images, false or
>> +#          omitted to show just the top image of a block device
> 
> I'm not sure these flags are necessary.
> 
  These flag seems more flex to me. Always querying all info require
caller do a filter operation on what he got, but in many times caller
may be interested on only one device.

>> +#
>> +# Returns: a list of @DeviceImageInfo describing each virtual block device
>> +#
>> +# Since: 1.5
>> +##
>> +{ 'command': 'query-images',
>> +  'data': { '*device': 'str', '*backing': 'bool' },
>> +  'returns': ['DeviceImageInfo'] }
>> +
>> +##
>>   # @BlockDeviceStats:
>>   #
>>   # Statistics of a virtual block device or a block backing device.
>> diff --git a/qmp-commands.hx b/qmp-commands.hx
>> index 799adea..292d61e 100644
>> --- a/qmp-commands.hx
>> +++ b/qmp-commands.hx
>> @@ -1743,6 +1743,82 @@ EQMP
>>       },
>>   
>>   SQMP
>> +query-images
>> +-----------
>> +
>> +Show the block devices' images.
> 
> Show block device image information
> 
  OK.

>> +
>> +Each block image information is stored in a json-object and the returned 
>> value
>> +is a json-array of all devices' images.
> 
> Each device is represented by a json-object. The returned value is a 
> json-array
> of all devices.
> 
  OK.

>> +
>> +Each json-object contain the following:
>> +
>> +- "device": device name (json-string)
>> +- "image": related image information, it is a optional json-object 
>> containing the following:
> 
> - "image": image information (json-object, optional) containing:
> 
  OK.

>> +         - "filename": image file name (json-string)
>> +         - "format": image format (json-string)
>> +         - "virtual-size": maximum capacity in bytes of the image (json-int)
> 
>              - "virtual-size": image capacity in bytes (json-int)
> 
>> +         - "dirty-flag": true if image is not cleanly closed (json-bool, 
>> optional)
> 
> Long line.
> 
> What's the meaning of dirty-flag not present in object?
> 
>> +         - "actual-size": actual size on disk in bytes of the image 
>> (json-int, optional)
> 
>              - "actual-size": actual on-disk image size in bytes
>                (json-int, optional)
> 
> Can you explain when actual-size is present, and when not?  Same for the
> other optional members.
> 
  OK, will document them.

>> +         - "cluster-size": size of a cluster in bytes (json-int, optional)
>> +         - "encrypted": true if the image is encrypted (json-bool, optional)
>> +         - "backing_file": backing file name (json-string, optional)
>> +         - "full-backing-filename": full path of the backing file 
>> (json-string, optional)
>> +         - "backing-filename-format": the format of the backing file 
>> (json-string, optional)
> 
> Long lines.
> 
>> +         - "snapshots": the internal snapshot info, it is an optional list 
>> of json-object
>> +            containing the following:
> 
>              - "snapshots": internal snapshot info
>                (json-array of json-object, optional)
>                Each object contains:
> 
>> +             - "id": unique snapshot id (json-string)
>> +             - "name": internal snapshot name (json-string)
> 
> Suggest to drop "internal"
> 
>> +             - "vm-state-size": size of the VM state in bytes (json-int)
>> +             - "date-sec": UTC date of the snapshot in seconds (json-int)
>> +             - "date-nsec": fractional part in nano seconds to be used with 
>> date-sec(json-int)
>> +             - "vm-clock-sec": VM clock relative to boot in seconds 
>> (json-int)
>> +             - "vm-clock-nsec": fractional part in nano seconds to be used 
>> with vm-clock-sec (json-int)
> 
> Long lines.
> 
> A year has 86400 s == 8.64e13 ns, thus int64_t is good for more than
> 10000 years.  Why can't we simply measure in ns and dispense with the
> awkward (sec, nsec) pair?
> 
  I am not sure this brings much benefits. In most case the management
stack may need to use the "seconds" to show for end user.

>> +
>> +Example:
>> +
>> +-> { "execute": "query-images" }
>> +<- {
>> +      "return":[
>> +         {
>> +            "device":"ide0-hd0",
>> +            "image":{
>> +               "filename":"disks/test0.img",
>> +               "format":"qcow2",
>> +               "virtual-size":1024000
>> +            }
>> +         },
>> +         {
>> +            "device":"ide0-hd1",
>> +            "image":{
>> +               "filename":"disks/test1.img",
>> +               "format":"qcow2",
>> +               "virtual-size":2048000,
>> +               "snapshots":[
>> +                  {
>> +                     "id": "1",
>> +                     "name": "snapshot1",
>> +                     "vm-state-size": 0,
>> +                     "date-sec": 10000200,
>> +                     "date-nsec": 12,
>> +                     "vm-clock-sec": 206,
>> +                     "vm-clock-nsec": 30
>> +                  }
>> +               ]
>> +            }
>> +         }
>> +      ]
>> +   }
>> +
>> +EQMP
>> +
>> +    {
>> +        .name       = "query-images",
>> +        .args_type  = "device:B?, backing:-b",
>> +        .mhandler.cmd_new = qmp_marshal_input_query_images,
>> +    },
>> +
>> +SQMP
>>   query-blockstats
>>   ----------------
> 


-- 
Best Regards

Wenchao Xia