Re: [Qemu-devel] [PATCH v5 12/22] block: Allow recursive "file"s

[Kevin Wolf <kwolf@redhat.com>]

Am 13.12.2013 um 18:10 hat Max Reitz geschrieben:
> It should be possible to use a format as a driver for a file which in
> turn requires another file, i.e., nesting file formats.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>

Hm, does this do what I think it does?

$ ./qemu-img convert -O qcow2 /home/kwolf/images/hd.img /tmp/hd.qcow2
$ ./qemu-img convert -f raw -O qcow2 /tmp/hd.qcow2 /tmp/hd.qcow2.qcow2
$ x86_64-softmmu/qemu-system-x86_64 -drive driver=qcow2,file.driver=qcow2,file.file.driver=file,file.file.filename=/tmp/hd.qcow2.qcow2

I can't decide whether this is awesomeness or insanity, but in any case
it works with this patch. :-)

Worth a qemu-iotests case, I think.

>  block.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 9659eb5..9222669 100644
> --- a/block.c
> +++ b/block.c
> @@ -948,14 +948,19 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
>          goto fail;
>      }
>  
> -    ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err);
> +    if (!drv->bdrv_file_open) {
> +        ret = bdrv_open(bs, filename, options, flags, drv, &local_err);
> +        options = NULL;
> +    } else {
> +        ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err);
> +    }
>      if (ret < 0) {
>          error_propagate(errp, local_err);
>          goto fail;
>      }
>  
>      /* Check if any unknown options were used */
> -    if (qdict_size(options) != 0) {
> +    if (options && (qdict_size(options) != 0)) {
>          const QDictEntry *entry = qdict_first(options);
>          error_setg(errp, "Block protocol '%s' doesn't support the option '%s'",
>                     drv->format_name, entry->key);
> @@ -970,10 +975,12 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
>  
>  fail:
>      QDECREF(options);
> -    if (!bs->drv) {
> -        QDECREF(bs->options);
> +    if (bs) {
> +        if (!bs->drv) {
> +            QDECREF(bs->options);
> +        }
> +        bdrv_unref(bs);
>      }
> -    bdrv_unref(bs);
>      return ret;
>  }

Not sure why this hunk is needed, but anyway:

Reviewed-by: Kevin Wolf <kwolf@redhat.com>