Re: [Qemu-devel] [PATCH] util/hbitmaps: recalculate count on merge

[Vladimir Sementsov-Ogievskiy]

27.09.2018 00:28, John Snow wrote:
> We have been neglecting to do so, which results in wrong counts
> after merge. In the worst case, we may think the bitmap is empty
> when it has had new writes merged into it.
>
> Reported-by: Eric Blake <address@hidden>
> Signed-off-by: John Snow <address@hidden>
> ---
>   util/hbitmap.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index d5aca5159f..28e9c523ab 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -759,6 +759,9 @@ bool hbitmap_merge(const HBitmap *a, const HBitmap *b, 
> HBitmap *result)
>           }
>       }
>   
> +    /* Recompute the dirty count */
> +    a->count = hb_count_between(a, 0, a->size - 1);

hmm, just looking at function header: shouldn't we update result->count 
instead? This code shouldn't compile (thanks to my const*)

> +
>       return true;
>   }
>   


--
Best regards,
Vladimir