Re: [Qemu-devel] [RFC PATCH v3 1/2] block: parse "backing" option to reference existing BDS

[Fam Zheng <famz@redhat.com>]

On Thu, 10/17 13:36, Fam Zheng wrote:
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block.c | 27 ++++++++++++++++++++++-----
>  1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/block.c b/block.c
> index fd05a80..38b3e80 100644
> --- a/block.c
> +++ b/block.c
> @@ -1158,11 +1158,28 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
>      /* If there is a backing file, use it */
>      if ((flags & BDRV_O_NO_BACKING) == 0) {
>          QDict *backing_options;
> -
> -        qdict_extract_subqdict(options, &backing_options, "backing.");
> -        ret = bdrv_open_backing_file(bs, backing_options, &local_err);
> -        if (ret < 0) {
> -            goto close_and_fail;
> +        const char *backing_bs;
> +
> +        backing_bs = qdict_get_try_str(options, "backing");
> +        if (backing_bs) {
> +            bs->backing_hd = bdrv_find(backing_bs);
> +            bdrv_ref(bs->backing_hd);

This should be moved down into if.

Fam

> +            qdict_del(options, "backing");
> +            if (bs->backing_hd) {
> +                pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> +                        bs->backing_hd->filename);
> +                pstrcpy(bs->backing_format, sizeof(bs->backing_format),
> +                        bs->backing_hd->drv->format_name);
> +            } else {
> +                error_setg(errp, "Backing device not found: %s", backing_bs);
> +                goto close_and_fail;
> +            }
> +        } else {
> +            qdict_extract_subqdict(options, &backing_options, "backing.");
> +            ret = bdrv_open_backing_file(bs, backing_options, &local_err);
> +            if (ret < 0) {
> +                goto close_and_fail;
> +            }
>          }
>      }
>  
> -- 
> 1.8.3.1
> 
>