[Qemu-devel] [PATCH v3 0/2] qcow2: Snapshot update for zero clusters

[Max Reitz]

When creating a snapshots, the refcount adjustment function basically
adjusted the refcounts of any cluster with a non-zero L2 entry. However,
the L2 entry of unallocated zero clusters is exactly one (therefore
non-zero) which led to wrong refcount updates on cluster 0 (the main
qcow2 header), since the cluster index for these unallocated zero clusters
is 0.

This series fixes this by taking all cluster types specifically into
account using qcow2_get_cluster_type and handling them accordingly.
Furthermore, a short test is added.

v3:
 - forgot 062.out in v2; now added

v2:
 - more thorough commit message
 - take pre-allocated zero clusters into account
 - abort on unknown cluster type
 - a test case

Max Reitz (2):
  qcow2-refcount: Snapshot update for zero clusters
  qemu-iotests: Snapshotting zero clusters

 block/qcow2-refcount.c     | 52 +++++++++++++++++++++++++------------
 tests/qemu-iotests/062     | 64 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/062.out |  9 +++++++
 tests/qemu-iotests/group   |  1 +
 4 files changed, 109 insertions(+), 17 deletions(-)
 create mode 100755 tests/qemu-iotests/062
 create mode 100644 tests/qemu-iotests/062.out

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1.8.3.1