Re: [PATCH v3 04/21] parallels: Add parallels_mark_unused() helper

[Denis V. Lunev]

On 10/27/23 09:46, Alexander Ivanov wrote:
> Add a helper to set unused areas in the used bitmap.
>
> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
> ---
>   block/parallels.c | 17 +++++++++++++++++
>   block/parallels.h |  2 ++
>   2 files changed, 19 insertions(+)
>
> diff --git a/block/parallels.c b/block/parallels.c
> index e9a8cbe430..a30bb5fe0d 100644
> --- a/block/parallels.c
> +++ b/block/parallels.c
> @@ -195,6 +195,23 @@ int parallels_mark_used(BlockDriverState *bs, unsigned 
> long *bitmap,
>       return 0;
>   }
>   
> +int parallels_mark_unused(BlockDriverState *bs, unsigned long *bitmap,
> +                          uint32_t bitmap_size, int64_t off, uint32_t count)
> +{
> +    BDRVParallelsState *s = bs->opaque;
> +    uint32_t cluster_index = host_cluster_index(s, off);
> +    unsigned long next_unused;
> +    if (cluster_index + count > bitmap_size) {
> +        return -E2BIG;
> +    }
> +    next_unused = find_next_zero_bit(bitmap, bitmap_size, cluster_index);
> +    if (next_unused < cluster_index + count) {
> +        return -EINVAL;
> +    }
I would limit the search with 'off + count'.
There is no necessity to traverse the bitmap further.

Den