[libvirt] [PATCHv2] qemu: Stop recursive detection of image chains when an image is missing

Eric Blake eblake at redhat.com
Thu Nov 22 15:02:00 UTC 2012


On 11/22/2012 07:50 AM, Peter Krempa wrote:
> Commit e0c469e58b93f852a72265919703cb6abd3779f8 that fixes the detection
> of image chain wasn't complete. Iteration through the backing image
> chain has to stop at the last existing image if some of the images are
> missing otherwise the backing chain that is cached contains entries with
> paths being set to NULL resulting to:
> 
> error: Unable to allow access for disk path (null): Bad address
> 
> Fortunately stat() is kind enough not to crash when it's presented with
> a NULL argument. At least on Linux.
> ---
> Left meta->backingStoreRaw in place to mark broken chains, added a comment and a warning.
> ---
>  src/util/storage_file.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

ACK.

> 
> diff --git a/src/util/storage_file.c b/src/util/storage_file.c
> index 2249212..4417404 100644
> --- a/src/util/storage_file.c
> +++ b/src/util/storage_file.c
> @@ -728,8 +728,13 @@ virStorageFileGetMetadataFromBuf(int format,
>                  meta->backingStore = absolutePathFromBaseFile(path, backing);
>                  if (meta->backingStore == NULL) {
>                      /* the backing file is (currently) unavailable, treat this
> -                     * file as standalone */
> +                     * file as standalone:
> +                     * backingStoreRaw is kept to mark broken image chains */
> +                    meta->backingStoreIsFile = false;
>                      backingFormat = VIR_STORAGE_FILE_NONE;
> +                    VIR_WARN("Backing file '%s' of image '%s' is missing.",
> +                             meta->backingStoreRaw, path);
> +
>                  }
>              }
>              VIR_FREE(backing);
> 

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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