Re: [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()

[Michael Tokarev]

30.01.2024 03:27, Stefan Hajnoczi wrote:
> The following expression is incorrect because blk_pread_nonzeroes()
> deals in units of bytes, not sectors:
>
>    bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS)
>                                                ^^^^^^^
>
> BDRV_REQUEST_MAX_BYTES is the appropriate constant.
>
> Fixes: a4b15a8b9ef2 ("pflash: Only read non-zero parts of backend image")
> Cc: Xiang Zheng <zhengxiang9@huawei.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>   hw/block/block.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/block/block.c b/hw/block/block.c
> index 9f52ee6e72..ff503002aa 100644
> --- a/hw/block/block.c
> +++ b/hw/block/block.c
> @@ -30,7 +30,7 @@ static int blk_pread_nonzeroes(BlockBackend *blk, hwaddr 
> size, void *buf)
>       BlockDriverState *bs = blk_bs(blk);
>   
>       for (;;) {
> -        bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS);
> +        bytes = MIN(size - offset, BDRV_REQUEST_MAX_BYTES);

Hmm.  This smells like a -stable material, but you know better not
to Cc: qemu-stable@ for unrelated stuff...  Is it not for stable?

Thanks,

/mjt