Re: [Qemu-devel] [PATCH v3 02/22] qcow2: Add refcount_width to format-specific info

[Stefan Hajnoczi]

On Thu, Nov 20, 2014 at 06:06:18PM +0100, Max Reitz wrote:
> Add the bit width of every refcount entry to the format-specific
> information.
> 
> In contrast to lazy_refcounts and the corrupt flag, this should be
> always emitted, even for compat=0.10 although it does not support any
> refcount width other than 16 bits. This is because if a boolean is
> optional, one normally assumes it to be false when omitted; but if an
> integer is not specified, it is rather difficult to guess its value.
> 
> This new field breaks some test outputs, fix them.
> 
> Signed-off-by: Max Reitz <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> ---
>  block/qcow2.c              |  4 +++-
>  qapi/block-core.json       |  5 ++++-
>  tests/qemu-iotests/060.out |  1 +
>  tests/qemu-iotests/065     | 23 +++++++++++++++--------
>  tests/qemu-iotests/067.out |  5 +++++
>  tests/qemu-iotests/082.out |  7 +++++++
>  tests/qemu-iotests/089.out |  2 ++
>  7 files changed, 37 insertions(+), 10 deletions(-)
> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index f57aff9..d70e927 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -2475,7 +2475,8 @@ static ImageInfoSpecific 
> *qcow2_get_specific_info(BlockDriverState *bs)
>      };
>      if (s->qcow_version == 2) {
>          *spec_info->qcow2 = (ImageInfoSpecificQCow2){
> -            .compat = g_strdup("0.10"),
> +            .compat             = g_strdup("0.10"),
> +            .refcount_width     = s->refcount_bits,

Why call it "width" in ImageInfoSpecificQCow2 when the qcow2 code calls
it "bits"?  IMO "bits" is clearer because it tells you the units, and
it's more consistent.

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