Re: [Qemu-devel] [PATCH v9 01/13] block/backup: fix backup_cow_with_offload for last cluster

[Max Reitz]

On 26.08.19 18:13, Vladimir Sementsov-Ogievskiy wrote:
> We shouldn't try to copy bytes beyond EOF. Fix it.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
>  block/backup.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/backup.c b/block/backup.c
> index 2baf7bed65..33b144305f 100644
> --- a/block/backup.c
> +++ b/block/backup.c
> @@ -161,7 +161,7 @@ static int coroutine_fn 
> backup_cow_with_offload(BackupBlockJob *job,
>  
>      assert(QEMU_IS_ALIGNED(job->copy_range_size, job->cluster_size));
>      assert(QEMU_IS_ALIGNED(start, job->cluster_size));
> -    nbytes = MIN(job->copy_range_size, end - start);
> +    nbytes = MIN(job->copy_range_size, MIN(end - start, job->len - start));

Might be easier to read as MIN(end, job->len) - start, but either way:

Reviewed-by: Max Reitz <address@hidden>

>      nr_clusters = DIV_ROUND_UP(nbytes, job->cluster_size);
>      bdrv_reset_dirty_bitmap(job->copy_bitmap, start,
>                              job->cluster_size * nr_clusters);
>

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