From: Max Reitz <mre...@redhat.com>
Account for all cluster types in qcow2_update_snapshot_refcounts;
this prevents this function from updating the refcount of unallocated
zero clusters which effectively led to wrong adjustments of the refcount
of cluster 0 (the main qcow2 header). This in turn resulted in images
with (unallocated) zero clusters having a cluster 0 refcount greater
than one after creating a snapshot.
Signed-off-by: Max Reitz <mre...@redhat.com>
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block/qcow2-refcount.c | 52 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 35 insertions(+), 17 deletions(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 1244693..a61224a 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -861,11 +861,14 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
for(j = 0; j < s->l2_size; j++) {
+ uint64_t cluster_index;
+
offset = be64_to_cpu(l2_table[j]);
- if (offset != 0) {
- old_offset = offset;
- offset &= ~QCOW_OFLAG_COPIED;
- if (offset & QCOW_OFLAG_COMPRESSED) {
+ old_offset = offset;
+ offset &= ~QCOW_OFLAG_COPIED;
+
+ switch (qcow2_get_cluster_type(offset)) {
+ case QCOW2_CLUSTER_COMPRESSED:
nb_csectors = ((offset >> s->csize_shift) &
s->csize_mask) + 1;
if (addend != 0) {
@@ -880,8 +883,16 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
/* compressed clusters are never modified */
refcount = 2;
- } else {
- uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >>
s->cluster_bits;
+ break;
+
+ case QCOW2_CLUSTER_NORMAL:
+ case QCOW2_CLUSTER_ZERO:
+ cluster_index = (offset & L2E_OFFSET_MASK) >>
s->cluster_bits;
+ if (!cluster_index) {
+ /* unallocated */
+ refcount = 0;
+ break;
+ }
if (addend != 0) {
refcount = update_cluster_refcount(bs,
cluster_index, addend,
QCOW2_DISCARD_SNAPSHOT);
@@ -893,19 +904,26 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
ret = refcount;
goto fail;
}
- }
+ break;
- if (refcount == 1) {
- offset |= QCOW_OFLAG_COPIED;
- }
- if (offset != old_offset) {
- if (addend > 0) {
- qcow2_cache_set_dependency(bs, s->l2_table_cache,
- s->refcount_block_cache);
- }
- l2_table[j] = cpu_to_be64(offset);
- qcow2_cache_entry_mark_dirty(s->l2_table_cache,
l2_table);
+ case QCOW2_CLUSTER_UNALLOCATED:
+ refcount = 0;
+ break;
+
+ default:
+ abort();
+ }
+
+ if (refcount == 1) {
+ offset |= QCOW_OFLAG_COPIED;
+ }
+ if (offset != old_offset) {
+ if (addend > 0) {
+ qcow2_cache_set_dependency(bs, s->l2_table_cache,
+ s->refcount_block_cache);
}
+ l2_table[j] = cpu_to_be64(offset);
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
}
}
--
1.8.1.4
