Re: [RFC PATCH 0/2] Allow changing bs->file on reopen

[Alberto Garcia <berto@igalia.com>]

On Thu 21 Jan 2021 11:52:17 AM CET, Kevin Wolf wrote:
>> Hmm, still, removing a filter which want to unshare WRITE even when
>> doesn't have any parents will be a problem anyway, so we'll need a
>> new command to drop filter with a logic like in bdrv_drop_filter in
>> my series.
>> 
>> Or, we can introduce multiple reopen.. So that x-blockdev-reopen will
>> take a list of BlockdevOptions, and do all modifications in one
>> transaction. Than we'll be able to drop filter by transactional
>> update of top node child and removing filter child link.
>
> Internally, we already have reopen queues anyway, so it would make
> sense to me to expose them externally and take a list of
> BlockdevOptions.  This way we should be able to do even complex
> changes of the graph where adding some edges requires the removal of
> other edges in a single atomic operation.

So you mean changing the signature to something like this?

{ 'command': 'x-blockdev-reopen',
  'data': { 'options': ['BlockdevOptions'] } }

It should be easy to make that change, I can have a look.

Berto