Re: [PATCH v7 14/47] stream: Deal with filters

[Kevin Wolf]

Am 25.06.2020 um 17:21 hat Max Reitz geschrieben:
> Because of the (not so recent anymore) changes that make the stream job
> independent of the base node and instead track the node above it, we
> have to split that "bottom" node into two cases: The bottom COW node,
> and the node directly above the base node (which may be an R/W filter
> or the bottom COW node).
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  qapi/block-core.json |  4 +++
>  block/stream.c       | 63 ++++++++++++++++++++++++++++++++------------
>  blockdev.c           |  4 ++-
>  3 files changed, 53 insertions(+), 18 deletions(-)
> 
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index b20332e592..df87855429 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2486,6 +2486,10 @@
>  # On successful completion the image file is updated to drop the backing file
>  # and the BLOCK_JOB_COMPLETED event is emitted.
>  #
> +# In case @device is a filter node, block-stream modifies the first 
> non-filter
> +# overlay node below it to point to base's backing node (or NULL if @base was
> +# not specified) instead of modifying @device itself.

Not to @base's backing node, but to @base itself (or actually, to
above_base's backing node, which is initially @base, but may have
changed when the job is completed).

Should we also document what using a filter node for @base means?

The code changes look good.

Kevin