Re: [PATCH v2 4/8] qemu-img: add chunk size parameter to compare_buffers()

[Eric Blake]

On Fri, Sep 15, 2023 at 07:20:12PM +0300, Andrey Drobyshev wrote:
> Add @chsize param to the function which, if non-zero, would represent
> the chunk size to be used for comparison.  If it's zero, then
> BDRV_SECTOR_SIZE is used as default chunk size, which is the previous
> behaviour.
> 
> In particular, we're going to use this param in img_rebase() to make the
> write requests aligned to a predefined alignment value.
> 
> Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
> ---
>  qemu-img.c | 22 ++++++++++++++--------
>  1 file changed, 14 insertions(+), 8 deletions(-)
> 
> diff --git a/qemu-img.c b/qemu-img.c
> index d12e4a4753..fcd31d7b5b 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1274,23 +1274,29 @@ static int is_allocated_sectors_min(const uint8_t 
> *buf, int n, int *pnum,
>  }
>  
>  /*
> - * Compares two buffers sector by sector. Returns 0 if the first
> - * sector of each buffer matches, non-zero otherwise.
> + * Compares two buffers chunk by chunk, where @chsize is the chunk size.
> + * If @chsize is 0, default chunk size of BDRV_SECTOR_SIZE is used.
> + * Returns 0 if the first chunk of each buffer matches, non-zero otherwise.
>   *
> - * pnum is set to the sector-aligned size of the buffer prefix that
> + * @pnum is set to the size of the buffer prefix aligned to @chsize that
>   * has the same matching status as the first sector.

s/sector/chunk/

With that,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization:  qemu.org | libguestfs.org