v5 was here:
https://lists.gnu.org/archive/html/qemu-devel/2018-04/msg04542.html

since then:
- 5/6: update iotest number, add R-b

(git-backport-diff doesn't handle renames well)

001/6:[----] [--] 'qcow2: Prefer byte-based calls into bs->file'
002/6:[----] [--] 'qcow2: Document some maximum size constraints'
003/6:[----] [--] 'qcow2: Reduce REFT_OFFSET_MASK'
004/6:[----] [--] 'qcow2: Don't allow overflow during cluster allocation'
005/6:[down] 'iotests: Add new test 220 for max compressed cluster offset'
006/6:[----] [--] 'qcow2: Avoid memory over-allocation on compressed images'

Eric Blake (6):
  qcow2: Prefer byte-based calls into bs->file
  qcow2: Document some maximum size constraints
  qcow2: Reduce REFT_OFFSET_MASK
  qcow2: Don't allow overflow during cluster allocation
  iotests: Add new test 220 for max compressed cluster offset
  qcow2: Avoid memory over-allocation on compressed images

 docs/interop/qcow2.txt     | 40 +++++++++++++++++--
 block/qcow2.h              |  8 +++-
 block/qcow2-cluster.c      | 32 +++++++++------
 block/qcow2-refcount.c     | 27 ++++++++-----
 block/qcow2.c              |  2 +-
 tests/qemu-iotests/220     | 97 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/220.out | 54 ++++++++++++++++++++++++++
 tests/qemu-iotests/group   |  1 +
 8 files changed, 234 insertions(+), 27 deletions(-)
 create mode 100755 tests/qemu-iotests/220
 create mode 100644 tests/qemu-iotests/220.out

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2.14.4