diff options
| -rw-r--r-- | block/qcow2-cluster.c | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 6447222ba0..369689b27c 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1088,6 +1088,24 @@ static void calculate_l2_meta(BlockDriverState *bs, 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(); + } +} + /* * 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, @@ -1100,25 +1118,11 @@ 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; } |