Re: [Qemu-devel] [Qemu-block] [PATCH] vmdk: Fix next_cluster_sector for compressed write

[Max Reitz <mreitz@redhat.com>]

On 06.05.2015 14:23, Fam Zheng wrote:
> This fixes the bug introduced by commit c6ac36e (vmdk: Optimize cluster
> allocation).
>
> Sometimes, write_len could be larger than cluster size, because it
> contains both data and marker.  We must advance next_cluster_sector in
> this case, otherwise the image gets corrupted.
>
> Reported-by: Antoni Villalonga <qemu-list@friki.cat>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>   block/vmdk.c | 14 ++++++++++----
>   1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 1c5e2ef..4b4a862 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1302,6 +1302,8 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
>       uLongf buf_len;
>       const uint8_t *write_buf = buf;
>       int write_len = nb_sectors * 512;
> +    int64_t write_offset;
> +    int64_t write_end_sector;
>   
>       if (extent->compressed) {
>           if (!extent->has_marker) {
> @@ -1320,10 +1322,14 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
>           write_buf = (uint8_t *)data;
>           write_len = buf_len + sizeof(VmdkGrainMarker);
>       }
> -    ret = bdrv_pwrite(extent->file,
> -                        cluster_offset + offset_in_cluster,
> -                        write_buf,
> -                        write_len);
> +    write_offset = cluster_offset + offset_in_cluster,
> +    ret = bdrv_pwrite(extent->file, write_offset, write_buf, write_len);
> +
> +    write_end_sector = DIV_ROUND_UP(write_offset + write_len, BDRV_SECTOR_SIZE);
> +
> +    extent->next_cluster_sector = MAX(extent->next_cluster_sector,
> +                                      write_end_sector);
> +
>       if (ret != write_len) {
>           ret = ret < 0 ? ret : -EIO;
>           goto out;

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