[PATCH v2 0/7] block: Relax restrictions for blockdev-snapshot

[Kevin Wolf <kwolf@redhat.com>]

This series allows libvirt to fix a regression that its switch from
drive-mirror to blockdev-mirror caused: It currently requires that the
backing chain of the target image is already available when the mirror
operation is started.

In reality, the backing chain may only be copied while the operation is
in progress, so the backing file of the target image needs to stay
disabled until the operation completes and should be attached only at
that point. Without this series, we don't have a supported API to attach
the backing file at that later point.

v2:
- Added a fix and test case for iothreads [Peter]
- Added a blockdev-snapshot feature flag to indicate that it's usable
  for attaching a backing chain to an overlay that is already in
  write-only use (e.g. as a mirror target) [Peter]

Kevin Wolf (6):
  block: Make bdrv_get_cumulative_perm() public
  block: Relax restrictions for blockdev-snapshot
  iotests: Fix run_job() with use_log=False
  iotests: Test mirror with temporarily disabled target backing file
  block: Fix cross-AioContext blockdev-snapshot
  iotests: Add iothread cases to 155

Peter Krempa (1):
  qapi: Add '@allow-write-only-overlay' feature for 'blockdev-snapshot'

 qapi/block-core.json          |  9 +++-
 include/block/block_int.h     |  3 ++
 block.c                       |  7 ++-
 blockdev.c                    | 30 ++++--------
 tests/qemu-iotests/iotests.py |  5 +-
 tests/qemu-iotests/085.out    |  4 +-
 tests/qemu-iotests/155        | 88 +++++++++++++++++++++++++++++------
 tests/qemu-iotests/155.out    |  4 +-
 8 files changed, 104 insertions(+), 46 deletions(-)

-- 
2.20.1