Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block/qcow2-cluster.c | 55 ++++++++++++++++++++++++++++++++-----------------
1 files changed, 36 insertions(+), 19 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index a791bbe..903454d 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -677,6 +677,41 @@ err:
}
/*
+ * 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,
+ * which must copy from the backing file)
+ */
+static int count_cow_clusters(BDRVQcowState *s, int nb_clusters,
+ uint64_t *l2_table, int l2_index)
+{
+ int i = 0;
+ uint64_t cluster_offset;
+
+ while (i < nb_clusters) {
+ i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,
+ &l2_table[l2_index], i, 0);
+ if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) {
+ break;
+ }
+
+ i += count_contiguous_free_clusters(nb_clusters - i,
+ &l2_table[l2_index + i]);
+ if (i >= nb_clusters) {
+ break;
+ }
+
+ cluster_offset = be64_to_cpu(l2_table[l2_index + i]);
+
+ if ((cluster_offset & QCOW_OFLAG_COPIED) ||
+ (cluster_offset & QCOW_OFLAG_COMPRESSED))
+ break;
+ }
+
+ assert(i <= nb_clusters);
+ return i;
+}
+
+/*
* alloc_cluster_offset
*
* For a given offset of the disk image, return cluster offset in qcow2 file.
@@ -739,25 +774,7 @@ again:
/* how many available clusters ? */
- while (i < nb_clusters) {
- i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,
- &l2_table[l2_index], i, 0);
- if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) {
- break;
- }
-
- i += count_contiguous_free_clusters(nb_clusters - i,
- &l2_table[l2_index + i]);
- if (i >= nb_clusters) {
- break;
- }
-
- cluster_offset = be64_to_cpu(l2_table[l2_index + i]);
-
- if ((cluster_offset & QCOW_OFLAG_COPIED) ||
- (cluster_offset & QCOW_OFLAG_COMPRESSED))
- break;
- }
+ i = count_cow_clusters(s, nb_clusters, l2_table, l2_index);
assert(i <= nb_clusters);
nb_clusters = i;
--
1.7.6.5
