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Date: Tue, 7 Apr 2015 15:01:46 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH for-2.3] qcow2: Fix header update with
 overridden backing file
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To: qemu-block@nongnu.org
Cc: mjt@tls.msk.ru, qemu-devel@nongnu.org, stefanha@redhat.com

Am 07.04.2015 um 14:51 hat Kevin Wolf geschrieben:
> In recent qemu versions, it is possible to override the backing file
> name and format that is stored in the image file with values given at
> runtime. In such cases, the temporary override could end up in the
> image header if the qcow2 header was updated, while obviously correct
> behaviour would be to leave the on-disk backing file path/format
> unchanged.
> 
> Fix this and add a test case for it.
> 
> Reported-by: Michael Tokarev <mjt@tls.msk.ru>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -283,6 +283,12 @@ typedef struct BDRVQcowState {
>      QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
>      QTAILQ_HEAD (, Qcow2DiscardRegion) discards;
>      bool cache_discards;
> +
> +    /* Backing file path and format as stored in the image (this is not the
> +     * effective path/format, which may be the result of a runtime option
> +     * override) */
> +    char *image_backing_file;
> +    char *image_backing_format;
>  } BDRVQcowState;

*sigh* I guess freeing these in qcow2_close() wouldn't hurt either.
Sending v2.

Kevin