[v2,2/2] qcow2: Fix bdrv_write_compressed error handling

If during allocation of compressed clusters the cluster was already allocated
uncompressed, fail and properly release the l2_table (the latter avoids a
failed assertion).

While at it, make it return some real error numbers instead of -1.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-cluster.c |    6 ++++--
 block/qcow2.c         |   29 ++++++++++++++++++-----------
 2 files changed, 22 insertions(+), 13 deletions(-)

Reviewed-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>



引用 Kevin Wolf <kwolf@redhat.com>：

> If during allocation of compressed clusters the cluster was already allocated
> uncompressed, fail and properly release the l2_table (the latter avoids a
> failed assertion).
>
> While at it, make it return some real error numbers instead of -1.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/qcow2-cluster.c |    6 ++++--
>  block/qcow2.c         |   29 ++++++++++++++++++-----------
>  2 files changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 2f76311..f4e049f 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -568,8 +568,10 @@ uint64_t  
> qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
>      }
>
>      cluster_offset = be64_to_cpu(l2_table[l2_index]);
> -    if (cluster_offset & QCOW_OFLAG_COPIED)
> -        return cluster_offset & ~QCOW_OFLAG_COPIED;
> +    if (cluster_offset & QCOW_OFLAG_COPIED) {
> +        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +        return 0;
> +    }
>
>      if (cluster_offset)
>          qcow2_free_any_clusters(bs, cluster_offset, 1);
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 4dc980c..91f4f04 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1053,8 +1053,8 @@ static int  
> qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
>                         Z_DEFLATED, -12,
>                         9, Z_DEFAULT_STRATEGY);
>      if (ret != 0) {
> -        g_free(out_buf);
> -        return -1;
> +        ret = -EINVAL;
> +        goto fail;
>      }
>
>      strm.avail_in = s->cluster_size;
> @@ -1064,9 +1064,9 @@ static int  
> qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
>
>      ret = deflate(&strm, Z_FINISH);
>      if (ret != Z_STREAM_END && ret != Z_OK) {
> -        g_free(out_buf);
>          deflateEnd(&strm);
> -        return -1;
> +        ret = -EINVAL;
> +        goto fail;
>      }
>      out_len = strm.next_out - out_buf;
>
> @@ -1074,22 +1074,29 @@ static int  
> qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
>
>      if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
>          /* could not compress: write normal cluster */
> -        bdrv_write(bs, sector_num, buf, s->cluster_sectors);
> +        ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
> +        if (ret < 0) {
> +            goto fail;
> +        }
>      } else {
>          cluster_offset = qcow2_alloc_compressed_cluster_offset(bs,
>              sector_num << 9, out_len);
> -        if (!cluster_offset)
> -            return -1;
> +        if (!cluster_offset) {
> +            ret = -EIO;
> +            goto fail;
> +        }
>          cluster_offset &= s->cluster_offset_mask;
>          BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
> -        if (bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len)  
> != out_len) {
> -            g_free(out_buf);
> -            return -1;
> +        ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len);
> +        if (ret < 0) {
> +            goto fail;
>          }
>      }
>
> +    ret = 0;
> +fail:
>      g_free(out_buf);
> -    return 0;
> +    return ret;
>  }
>
>  static BlockDriverAIOCB *qcow2_aio_flush(BlockDriverState *bs,
> --
> 1.7.6.4