Re: [PATCH 3/4] block: Add blk_make_empty()

[Eric Blake <eblake@redhat.com>]

On 4/28/20 8:26 AM, Max Reitz wrote:
> Two callers of BlockDriver.bdrv_make_empty() remain that should not call
> this method directly.  Both do not have access to a BdrvChild, but they
> can use a BlockBackend, so we add this function that lets them use it.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   include/sysemu/block-backend.h | 2 ++
>   block/block-backend.c          | 5 +++++
>   2 files changed, 7 insertions(+)
> 
> diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
> index d37c1244dd..14338b76dc 100644
> --- a/include/sysemu/block-backend.h
> +++ b/include/sysemu/block-backend.h
> @@ -266,4 +266,6 @@ int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
>   
>   const BdrvChild *blk_root(BlockBackend *blk);
>   
> +int blk_make_empty(BlockBackend *blk, Error **errp);
> +

Again, a flag parameter to allow use of BDRV_REQ_NO_FALLBACK would be nice.

>   #endif
> diff --git a/block/block-backend.c b/block/block-backend.c
> index 3592066b42..5d36efd32f 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -2402,3 +2402,8 @@ const BdrvChild *blk_root(BlockBackend *blk)
>   {
>       return blk->root;
>   }
> +
> +int blk_make_empty(BlockBackend *blk, Error **errp)
> +{
> +    return bdrv_make_empty(blk->root, errp);
> +}
> 

Otherwise looks fine.

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