Re: [Qemu-devel] [PATCH v12 10/19] block: Add QMP support for streaming to an intermediate layer

[Kevin Wolf]

Am 26.10.2016 um 12:29 hat Alberto Garcia geschrieben:
> This patch makes the 'device' parameter of the 'block-stream' command
> accept a node name that is not a root node.
> 
> In addition to that, operation blockers will be checked in all
> intermediate nodes between the top and the base node.
> 
> Signed-off-by: Alberto Garcia <address@hidden>

> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -1464,6 +1464,10 @@
>  # with query-block-jobs.  The operation can be stopped before it has 
> completed
>  # using the block-job-cancel command.
>  #
> +# The node that receives the data is called the top image, can be located in
> +# any part of the chain (but always above the base image; see below) and can 
> be
> +# specified using its device or node name.
> +#
>  # If a base file is specified then sectors are not copied from that base 
> file and
>  # its backing chain.  When streaming completes the image file will have the 
> base
>  # file as its backing file.  This can be used to stream a subset of the 
> backing
> @@ -1475,12 +1479,12 @@
>  # @job-id: #optional identifier for the newly-created block job. If
>  #          omitted, the device name will be used. (Since 2.7)
>  #
> -# @device: the device name or node-name of a root node
> +# @device: the device or node name of the top image
>  #
>  # @base:   #optional the common backing file name
>  #
> -# @backing-file: #optional The backing file string to write into the active
> -#                          layer. This filename is not validated.
> +# @backing-file: #optional The backing file string to write into the top
> +#                          image. This filename is not validated.
>  #
>  #                          If a pathname string is such that it cannot be
>  #                          resolved by QEMU, that means that subsequent QMP 
> or

As we discussed in v10, this is not discoverable through introspection.
You added patch 18 which introduces a base-node option and can serve as
a witness for the changed semantics, which is good. Should this be
documented here?

Kevin