Commit 8ac0f15f335 accidently broke the COW of non changed areas
of newly allocated clusters, when the write spans multiple clusters,
and needs COW both prior and after the write.
This results in 'after' COW area being encrypted with wrong
sector address, which render it corrupted.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1745922

CC: qemu-stable <qemu-stable@nongnu.org>

V2: grammar, spelling and code style fixes.
V3: more fixes after the review.
V4: addressed review comments from Max Reitz,
    and futher refactored the qcow2_co_encrypt to just take full host and guest offset
    which simplifies everything.

V5: reworked the patches so one of them fixes the bug
    only and other one is just refactoring

Best regards,
	Maxim Levitsky

Maxim Levitsky (3):
  Fix qcow2+luks corruption introduced by commit 8ac0f15f335
  block/qcow2: refactor threaded encryption code
  qemu-iotests: Add test for bz #1745922

 block/qcow2-cluster.c      | 29 +++++++-----
 block/qcow2-threads.c      | 62 ++++++++++++++++++++------
 block/qcow2.c              |  5 ++-
 block/qcow2.h              |  8 ++--
 tests/qemu-iotests/263     | 91 ++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/263.out | 40 +++++++++++++++++
 tests/qemu-iotests/group   |  2 +
 7 files changed, 206 insertions(+), 31 deletions(-)
 create mode 100755 tests/qemu-iotests/263
 create mode 100644 tests/qemu-iotests/263.out

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2.17.2