Re: [Qemu-devel] [Qemu-block] [PATCH 1/3] qcow2: Fix unaligned preallocated truncation

[Jeff Cody <jcody@redhat.com>]

On Mon, Oct 09, 2017 at 11:55:31PM +0200, Max Reitz wrote:
> A qcow2 image file's length is not required to have a length that is a
> multiple of the cluster size.  However, qcow2_refcount_area() expects an
> aligned value for its @start_offset parameter, so we need to round
> @old_file_size up to the next cluster boundary.
> 
> Reported-by: pingl <pingl@redhat.com>
> Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1414049
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/qcow2.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 2f6a8e1ff8..c3b312cdef 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -3193,6 +3193,7 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset,
>                               "Failed to inquire current file length");
>              return old_file_size;
>          }
> +        old_file_size = ROUND_UP(old_file_size, s->cluster_size);
>  
>          nb_new_data_clusters = DIV_ROUND_UP(offset - old_length,
>                                              s->cluster_size);
> -- 
> 2.13.6
> 
> 

Reviewed-by: Jeff Cody <jcody@redhat.com>