27.10.2019 0:25, Alberto Garcia wrote:
> We are going to need it in other places.
>
> Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
> 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(&s->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