Re: [Qemu-devel] [PATCH 6/8] qcow2: add autoclear bit for dirty bitmaps

[Stefan Hajnoczi]

On Mon, Jun 08, 2015 at 06:21:24PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 406e55d..f85a55a 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -182,6 +182,14 @@ static int qcow2_read_extensions(BlockDriverState *bs, 
> uint64_t start_offset,
>                  return ret;
>              }
>  
> +            if (!(s->autoclear_features & QCOW2_AUTOCLEAR_DIRTY_BITMAPS) &&
> +                s->nb_dirty_bitmaps > 0) {
> +                ret = qcow2_delete_all_dirty_bitmaps(bs, errp);
> +                if (ret < 0) {
> +                    return ret;
> +                }
> +            }
> +

What if the file is read-only?

We shouldn't modify the file in qcow2_read_extensions().

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