Re: [PATCH v3 06/10] block/dirty-bitmap: add _next_dirty API

[Max Reitz <mreitz@redhat.com>]

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On 19.12.19 11:03, Vladimir Sementsov-Ogievskiy wrote:
> We have bdrv_dirty_bitmap_next_zero, let's add corresponding
> bdrv_dirty_bitmap_next_dirty, which is more comfortable to use than
> bitmap iterators in some cases.
> 
> For test modify test_hbitmap_next_zero_check_range to check both
> next_zero and next_dirty and add some new checks.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  include/block/dirty-bitmap.h |   2 +
>  include/qemu/hbitmap.h       |  13 ++++
>  block/dirty-bitmap.c         |   6 ++
>  tests/test-hbitmap.c         | 130 ++++++++++++++++++++---------------
>  util/hbitmap.c               |  60 ++++++++--------
>  5 files changed, 126 insertions(+), 85 deletions(-)

[...]

> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
> index b6e85f3d5d..a4b032b270 100644
> --- a/include/qemu/hbitmap.h
> +++ b/include/qemu/hbitmap.h
> @@ -297,6 +297,19 @@ void hbitmap_free(HBitmap *hb);
>   */
>  void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);
>  
> +/*
> + * hbitmap_next_dirty:
> + *
> + * Find next dirty bit within selected range. If not found, return -1.
> + *
> + * @hb: The HBitmap to operate on
> + * @start: The bit to start from.
> + * @count: Number of bits to proceed. If @start+@count > bitmap size, the whole
> + * bitmap is looked through. You can use UINT64_MAX as @count to search up to

I would’ve said s/looked through/scanned/, but it matches
hbitmap_next_zero()’s documentation, so it’s fine.

But definitely s/UINT64_MAX/INT64_MAX/.

> + * the bitmap end.
> + */
> +int64_t hbitmap_next_dirty(const HBitmap *hb, int64_t start, int64_t count);
> +
>  /* hbitmap_next_zero:
>   *
>   * Find next not dirty bit within selected range. If not found, return -1.

[...]

> diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c
> index 0e1e5c64dd..e3f1b3f361 100644
> --- a/tests/test-hbitmap.c
> +++ b/tests/test-hbitmap.c
> @@ -816,92 +816,108 @@ static void test_hbitmap_iter_and_reset(TestHBitmapData *data,
>      hbitmap_iter_next(&hbi);
>  }
>  
> -static void test_hbitmap_next_zero_check_range(TestHBitmapData *data,
> -                                               uint64_t start,
> -                                               uint64_t count)
> +static void test_hbitmap_next_x_check_range(TestHBitmapData *data,
> +                                            uint64_t start,
> +                                            uint64_t count)

Why not change the parameters to be signed while we’re already here?

[...]

> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index df22f06be6..d23f4b9678 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -193,6 +193,30 @@ void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first)
>      }
>  }
>  
> +int64_t hbitmap_next_dirty(const HBitmap *hb, int64_t start, int64_t count)
> +{
> +    HBitmapIter hbi;
> +    int64_t firt_dirty_off;

Pre-existing, but isn’t this just a typo that you could fix here?  (i.e.
s/firt/first/)

Apart from this minor things:

Reviewed-by: Max Reitz <mreitz@redhat.com>

> +    uint64_t end;
> +
> +    assert(start >= 0 && count >= 0);
> +
> +    if (start >= hb->orig_size || count == 0) {
> +        return -1;
> +    }
> +
> +    end = count > hb->orig_size - start ? 


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