Re: [Qemu-devel] [RFC v2 PATCH 6/6] QAPI: add command for live block commit, 'block-commit'

[Jeff Cody <jcody@redhat.com>]

On 08/30/2012 07:06 PM, Eric Blake wrote:
> On 08/30/2012 11:47 AM, Jeff Cody wrote:
>> The command for live block commit is added, which has the following
>> arguments:
>>
>> device: the block device to perform the commit on (mandatory)
>> base:   the base image to commit into; optional (if not specified,
>>         it is the underlying original image)
>> top:    the top image of the commit - all data from inside top down
>>         to base will be committed into base. optional (if not specified,
>>         it is the active image) - see note below
>> speed:  maximum speed, in bytes/sec
>>
>> note: eventually this will support merging down the active layer,
>>       but that code is not yet complete.  If the active layer is passed
>>       in currently as top, or top is left to the default, then the error
>>       QERR_TOP_NOT_FOUND will be returned.
>>
>> The is done as a block job, so upon completion a BLOCK_JOB_COMPLETED will
>> be emitted.
> 
> Likewise, the job can be canceled, and it is possible to track progress
> of the job or change the speed on the fly, using existing block job
> commands.

Correct.

> 
> Will the BLOCK_JOB_COMPLETED event have a new category listing that it
> was a commit job instead of a stream job that completed?  That is, I
> think this patch is incomplete, and that you also need to modify
> QMP/qmp-events.txt to modify the 'type' field of
> BLOCK_JOB_{CANCELLED,COMPLETED} to distinguish this new sub-type of event.
>

You are right, I should add the sub-type info into QMP/qmp-events.txt; the
type is 'commit'.

Here is what the BLOCK_JOB_COMPLETED event looks like for commit:

{"timestamp": {"seconds": 1346423249, "microseconds": 551295},
  "event": "BLOCK_JOB_COMPLETED",
  "data": {"device": "virtio0", "len": 6442450944, "offset": 6442450944,
            "speed": 140732751976032, "type": "commit"}}


>>  
>>  ##
>> +# @block-commit
>> +#
>> +# Live commit of data from child image nodes into parent nodes - i.e.,
>> +# writes data between 'top' and 'base' into 'base'.
>> +#
>> +# @device:  the name of the device
>> +#
>> +# @base:   #optional The parent image of the device to write data into.
>> +#                    If not specified, this is the original parent image.
>> +#
>> +# @top:    #optional The child image, above which data will not be committed
>> +#                    down.  If not specified, this is the active layer.
>> +#
>> +# @speed:  #optional the maximum speed, in bytes per second
>> +#
>> +# Returns: Nothing on success
>> +#          If commit or stream is already active on this device, DeviceInUse
>> +#          If @device does not exist, DeviceNotFound
>> +#          If image commit is not supported by this device, NotSupported
>> +#          If @base does not exist, BaseNotFound
>> +#          If @top does not exist, TopNotFound
>> +#          If @speed is invalid, InvalidParameter
>> +#
>> +# Since: 1.2
> 
> 1.3
>