Re: [PATCH 7/7] block: apply COR-filter to block-stream jobs

[Vladimir Sementsov-Ogievskiy]

20.04.2020 21:36, Andrey Shinkevich wrote:
> The patch completes the series with the COR-filter insertion to any
> block-stream operation. It also makes changes to the iotests 030, 141
> and 245.
>
> Signed-off-by: Andrey Shinkevich <address@hidden>
> ---
>   block/stream.c             | 151 +++++++++++++++++++++++++++++++++++++++------
>   tests/qemu-iotests/030     |   6 +-
>   tests/qemu-iotests/141.out |   2 +-
>   tests/qemu-iotests/245     |   5 +-
>   4 files changed, 141 insertions(+), 23 deletions(-)
>
> diff --git a/block/stream.c b/block/stream.c
> index fab7923..af14ba8 100644
> --- a/block/stream.c
> +++ b/block/stream.c


[..]

> +static int stream_exit(Job *job, bool abort)
> +{
> +    StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
> +    BlockJob *bjob = &s->common;
> +    BlockDriverState *target_bs = s->target_bs;
> +    int ret = 0;
> +
> +    if (s->chain_frozen) {
> +        bdrv_unfreeze_chain(s->target_bs, s->bottom_cow_node);
> +        s->chain_frozen = false;
> +    }
> +
> +    /* Retain the BDS until we complete the graph change. */
> +    bdrv_ref(target_bs);
> +    /* Hold a guest back from writing while permissions are being reset. */
> +    bdrv_drained_begin(target_bs);
> +    /* Drop permissions before the graph change. */
> +    bdrv_child_try_set_perm(bdrv_filtered_rw_child(s->cor_filter_bs),
> +                            0, BLK_PERM_ALL, &error_abort);

Hmm. I don't remember what's wrong with it, but something is. Neither mirror 
nor backup do this now,
instead they use some flag, that permissions are not needed anymore and call 
bdrv_child_refresh_perms()


Also, strange that you have insert_filter function, but don't use it here.

Also, could we keep add/remove filter api in block/copy-on-read.c, like it is 
done for backup-top ?

--
Best regards,
Vladimir