Re: [PATCH 3/4] block: add dbg_dump_block_layer()

[Eric Blake <eblake@redhat.com>]

On 11/19/20 7:16 AM, Vladimir Sementsov-Ogievskiy wrote:
> Add function for debugging: we already have x-debug-query-block-graph
> qmp command and scripts/render_block_graph.py which can dump
> block-layer graph for running vm using qmp command. But when debug
> block layer code, its often needed to dump some intermediate state
> during some operation, so separate qmp command doesn't help.
> 
> So, let's introduce a function which can dump needed information into
> json file.
> 
> In next commit we'll update scripts/render_block_graph.py so that it
> will be able to parse json files.
> 
> For new function to not crash if we have mirror_top filter node not yet
> bdrv_append()ed (to debug why it can't be appended), make
> bdrv_get_allocated_file_size() and bdrv_refresh_filename() not crash on
> filters without a child.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---

> +++ b/qapi/block-core.json
> @@ -1908,6 +1908,19 @@
>  ##
>  { 'command': 'x-debug-query-block-graph', 'returns': 'XDbgBlockGraph' }
>  
> +##
> +# @XDbgBlockLayerDump:
> +#
> +# Unite query-named-block-nodes, query-block-jobs and
> +# x-debug-query-block-graph results into one structure for block_layer_dump()
> +# function.
> +#
> +# Since: 5.3

The next release will be numbered 6.0, not 5.3.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org