Re: [Qemu-devel] [PATCH v6 8/8] vmdk: Make vmdk_get_cluster_offset() return cluster offset only

[Fam Zheng]

On Mon, 06/05 13:22, Ashijeet Acharya wrote:
> vmdk_alloc_clusters() introduced earlier now handles the task of
> allocating clusters and performing COW when needed. Thus we can change
> vmdk_get_cluster_offset() to stick to the sole purpose of returning
> cluster offset using sector number. Update the changes at all call
> sites.
> 
> Signed-off-by: Ashijeet Acharya <address@hidden>
> ---
>  block/vmdk.c | 56 ++++++++++++--------------------------------------------
>  1 file changed, 12 insertions(+), 44 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 9fa2414..accf1c3 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1485,25 +1485,16 @@ static int vmdk_alloc_clusters(BlockDriverState *bs,
>   * For flat extents, the start offset as parsed from the description file is
>   * returned.
>   *
> - * For sparse extents, look up in L1, L2 table. If allocate is true, return 
> an
> - * offset for a new cluster and update L2 cache. If there is a backing file,
> - * COW is done before returning; otherwise, zeroes are written to the 
> allocated
> - * cluster. Both COW and zero writing skips the sector range
> - * address@hidden, @skip_end_sector) passed in by caller, because caller
> - * has new data to write there.
> + * For sparse extents, look up the L1, L2 table.
>   *
>   * Returns: VMDK_OK if cluster exists and mapped in the image.
> - *          VMDK_UNALLOC if cluster is not mapped and @allocate is false.
> - *          VMDK_ERROR if failed.
> + *          VMDK_UNALLOC if cluster is not mapped.
> + *          VMDK_ERROR if failed
>   */
>  static int vmdk_get_cluster_offset(BlockDriverState *bs,
>                                     VmdkExtent *extent,
> -                                   VmdkMetaData *m_data,
>                                     uint64_t offset,
> -                                   bool allocate,
> -                                   uint64_t *cluster_offset,
> -                                   uint64_t skip_start_bytes,
> -                                   uint64_t skip_end_bytes)
> +                                   uint64_t *cluster_offset)
>  {
>      int l1_index, l2_offset, l2_index;
>      uint32_t *l2_table;
> @@ -1528,31 +1519,9 @@ static int vmdk_get_cluster_offset(BlockDriverState 
> *bs,
>      }
>  
>      if (!cluster_sector || zeroed) {
> -        if (!allocate) {
> -            return zeroed ? VMDK_ZEROED : VMDK_UNALLOC;
> -        }
> -
> -        cluster_sector = extent->next_cluster_sector;
> -        extent->next_cluster_sector += extent->cluster_sectors;
> -
> -        /* First of all we write grain itself, to avoid race condition
> -         * that may to corrupt the image.
> -         * This problem may occur because of insufficient space on host disk
> -         * or inappropriate VM shutdown.
> -         */
> -        ret = vmdk_perform_cow(bs, extent, cluster_sector * BDRV_SECTOR_SIZE,
> -                                offset, skip_start_bytes, skip_end_bytes);
> -        if (ret) {
> -            return ret;
> -        }
> -        if (m_data) {
> -            m_data->valid = 1;
> -            m_data->l1_index = l1_index;
> -            m_data->l2_index = l2_index;
> -            m_data->l2_offset = l2_offset;
> -            m_data->l2_cache_entry = &l2_table[l2_index];
> -        }
> +        return zeroed ? VMDK_ZEROED : VMDK_UNALLOC;
>      }
> +
>      *cluster_offset = cluster_sector << BDRV_SECTOR_BITS;
>      return VMDK_OK;
>  }
> @@ -1595,9 +1564,7 @@ static int64_t coroutine_fn 
> vmdk_co_get_block_status(BlockDriverState *bs,
>          return 0;
>      }
>      qemu_co_mutex_lock(&s->lock);
> -    ret = vmdk_get_cluster_offset(bs, extent, NULL,
> -                                  sector_num * 512, false, &offset,
> -                                  0, 0);
> +    ret = vmdk_get_cluster_offset(bs, extent, sector_num * 512, &offset);
>      qemu_co_mutex_unlock(&s->lock);
>  
>      index_in_cluster = vmdk_find_index_in_cluster(extent, sector_num);
> @@ -1788,13 +1755,14 @@ vmdk_co_preadv(BlockDriverState *bs, uint64_t offset, 
> uint64_t bytes,
>              ret = -EIO;
>              goto fail;
>          }
> -        ret = vmdk_get_cluster_offset(bs, extent, NULL,
> -                                      offset, false, &cluster_offset, 0, 0);
> +
>          offset_in_cluster = vmdk_find_offset_in_cluster(extent, offset);
>  
>          n_bytes = MIN(bytes, extent->cluster_sectors * BDRV_SECTOR_SIZE
>                               - offset_in_cluster);
>  
> +        ret = vmdk_get_cluster_offset(bs, extent, offset, &cluster_offset);
> +
>          if (ret != VMDK_OK) {
>              /* if not allocated, try to read from parent image, if exist */
>              if (bs->backing && ret != VMDK_ZEROED) {
> @@ -2541,9 +2509,9 @@ static int vmdk_check(BlockDriverState *bs, 
> BdrvCheckResult *result,
>                      sector_num);
>              break;
>          }
> -        ret = vmdk_get_cluster_offset(bs, extent, NULL,
> +        ret = vmdk_get_cluster_offset(bs, extent,
>                                        sector_num << BDRV_SECTOR_BITS,
> -                                      false, &cluster_offset, 0, 0);
> +                                      &cluster_offset);
>          if (ret == VMDK_ERROR) {
>              fprintf(stderr,
>                      "ERROR: could not get cluster_offset for sector %"
> -- 
> 2.6.2
> 

Reviewed-by: Fam Zheng <address@hidden>