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

[Eric Blake <eblake@redhat.com>]

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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.

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.

>  
>  ##
> +# @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

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


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