Re: [Qemu-devel] [PATCH v2 5/7] QAPI: add command for live block commit, 'block-commit'

[Kevin Wolf <kwolf@redhat.com>]

Am 25.09.2012 18:29, schrieb Jeff Cody:
> 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 one below 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 an error
>       will be returned.
> 
> The is done as a block job, so upon completion a BLOCK_JOB_COMPLETED will
> be emitted.
> 
> Signed-off-by: Jeff Cody <jcody@redhat.com>

> diff --git a/qapi-schema.json b/qapi-schema.json
> index 14e4419..e614453 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1468,6 +1468,41 @@
>    'returns': 'str' }
>  
>  ##
> +# @block-commit
> +#
> +# Live commit of data from overlay image nodes into backing nodes - i.e.,
> +# writes data between 'top' and 'base' into 'base'.
> +#
> +# @device:  the name of the device
> +#
> +# @base:   #optional The file name of the backing image to write data into.
> +#                    If not specified, this is the deepest backing image
> +#
> +# @top:    #optional The file name of the backing image within the image chain,
> +#                    which contains the topmost data to be committed down.
> +#                    If not specified, this is one layer below the active
> +#                    layer (i.e. active->backing_hd).

Why isn't active the default any more? I know, we don't support it yet,
but long term this is what makes most sense as a default.

> +#
> +#                    If top == base, that is an error.
> +#
> +#
> +# @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, a generic error is returned
> +#          If @top does not exist, a generic error is returned
> +#          If @speed is invalid, InvalidParameter
> +#
> +# Since: 1.3
> +#
> +##
> +{ 'command': 'block-commit',
> +  'data': { 'device': 'str', '*base': 'str', '*top': 'str',
> +            '*speed': 'int' } }

Kevin