Re: [PATCH 4/6] vmdk: Don't update L2 table for zero write on zero cluster

[Eric Blake]

On 4/30/20 8:30 AM, Kevin Wolf wrote:
> If a cluster is already zeroed, we don't have to call vmdk_L2update(),
> which is rather slow because it flushes the image file.
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>   block/vmdk.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Eric Blake <address@hidden>

> diff --git a/block/vmdk.c b/block/vmdk.c
> index da25b8992e..dcd30f1419 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -2013,7 +2013,7 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t 
> offset,
>                       offset_in_cluster == 0 &&
>                       n_bytes >= extent->cluster_sectors * BDRV_SECTOR_SIZE) {
>                   n_bytes = extent->cluster_sectors * BDRV_SECTOR_SIZE;
> -                if (!zero_dry_run) {
> +                if (!zero_dry_run && ret != VMDK_ZEROED) {
>                       /* update L2 tables */
>                       if (vmdk_L2update(extent, &m_data, VMDK_GTE_ZEROED)
>                               != VMDK_OK) {

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org