27.10.2019 0:25, Alberto Garcia wrote:
> We are going to need it in other places.
>
> Signed-off-by: Alberto Garcia
Reviewed-by: Vladimir Sementsov-Ogievskiy
> ---
> block/qcow2-cluster.c | 34 +++---
> 1 file changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 6c1dcdc781..aa1010a515 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -1068,6 +1068,24 @@ static void calculate_l2_meta(BlockDriverState *bs,
> uint64_t host_offset,
> QLIST_INSERT_HEAD(>cluster_allocs, *m, next_in_flight);
> }
>
> +/* Returns true if writing to a cluster requires COW */
> +static bool cluster_needs_cow(BlockDriverState *bs, uint64_t l2_entry)
> +{
> +switch (qcow2_get_cluster_type(bs, l2_entry)) {
> +case QCOW2_CLUSTER_NORMAL:
> +if (l2_entry & QCOW_OFLAG_COPIED) {
> +return false;
> +}
> +case QCOW2_CLUSTER_UNALLOCATED:
> +case QCOW2_CLUSTER_COMPRESSED:
> +case QCOW2_CLUSTER_ZERO_PLAIN:
> +case QCOW2_CLUSTER_ZERO_ALLOC:
> +return true;
> +default:
> +abort();
> +}
> +}
Not sure how much is it better than just
return !(qcow2_get_cluster_type(bs, l2_entry) == QCOW2_CLUSTER_NORMAL &&
(l2_entry & QCOW_OFLAG_COPIED));
> +
> /*
>* Returns the number of contiguous clusters that can be used for an
> allocating
>* write, but require COW to be performed (this includes yet unallocated
> space,
> @@ -1080,25 +1098,11 @@ static int count_cow_clusters(BlockDriverState *bs,
> int nb_clusters,
>
> for (i = 0; i < nb_clusters; i++) {
> uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
> -QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry);
> -
> -switch(cluster_type) {
> -case QCOW2_CLUSTER_NORMAL:
> -if (l2_entry & QCOW_OFLAG_COPIED) {
> -goto out;
> -}
> +if (!cluster_needs_cow(bs, l2_entry)) {
> break;
> -case QCOW2_CLUSTER_UNALLOCATED:
> -case QCOW2_CLUSTER_COMPRESSED:
> -case QCOW2_CLUSTER_ZERO_PLAIN:
> -case QCOW2_CLUSTER_ZERO_ALLOC:
> -break;
> -default:
> -abort();
> }
> }
>
> -out:
> assert(i <= nb_clusters);
> return i;
> }
>
--
Best regards,
Vladimir
