Re: [Qemu-devel] [PATCH 01/16] block: Introduce BDS.file_child

[Max Reitz <mreitz@redhat.com>]

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On 17.09.2015 15:48, Kevin Wolf wrote:
> Store the BdrvChild for bs->file. At this point, bs->file_child->bs just
> duplicates the bs->file pointer. Later, it will completely replace it.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c                   | 12 +++++++++---
>  include/block/block_int.h |  1 +
>  2 files changed, 10 insertions(+), 3 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>

Although I have a small comment below:

> 
> diff --git a/block.c b/block.c
> index 6268e37..2e9e5e2 100644
> --- a/block.c
> +++ b/block.c
> @@ -1487,11 +1487,17 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
>  
>          assert(file == NULL);

This looks strange now, without the direct connection to
bdrv_open_image(). I'd drop this...

>          bs->open_flags = flags;
> -        ret = bdrv_open_image(&file, filename, options, "file",
> -                              bs, &child_file, true, &local_err);
> -        if (ret < 0) {
> +
> +        bs->file_child = bdrv_open_child(filename, options, "file", bs,
> +                                         &child_file, true, &local_err);
> +        if (local_err) {
> +            ret = -EINVAL;
>              goto fail;
>          }
> +
> +        if (bs->file_child) {
> +            file = bs->file_child->bs;
> +        }

And make this file = bs->file_child ? bs->file_child->bs : NULL (or the
respective long form, i.e.
if (bs->file_child) { ... } else { file = NULL; }).

We could even put this after this if block and drop the NULL
initialization of file, but that might go overboard.

Max

>      }
>  
>      /* Image format probing */
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 14ad4c3..d0dd93e 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -381,6 +381,7 @@ struct BlockDriverState {
>      BlockDriverState *backing_hd;
>      BdrvChild *backing_child;
>      BlockDriverState *file;
> +    BdrvChild *file_child;
>  
>      NotifierList close_notifiers;
>  
> 



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