"nbd-server-add -w" doesn't work when we are in "-incoming defer" state:

    (qemu) nbd_server_add -w drive-virtio-disk0
    Block node is read-only

Two problems are faced:

  - nbd_export_new() calls bdrv_invalidate_cache() too late.
  - bdrv_invalidate_cache() restores qdev permission (which are temporarily
    masked by BlockBackend.disable_perm during INMIGRATE) too early.

Fix both, and add a regression iotest.

Fam Zheng (3):
  stubs: Add vm state change handler stubs
  block-backend: Defer shared_perm tightening migration completion
  iotests: Add non-shared storage migration case 192

Kevin Wolf (1):
  nbd: Fix order of bdrv_set_perm and bdrv_invalidate_cache

 block/block-backend.c        | 37 ++++++++++++++++++++++++++
 nbd/server.c                 | 20 +++++++-------
 stubs/Makefile.objs          |  1 +
 stubs/change-state-handler.c | 14 ++++++++++
 tests/qemu-iotests/192       | 63 ++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/192.out   |  7 +++++
 tests/qemu-iotests/group     |  1 +
 7 files changed, 134 insertions(+), 9 deletions(-)
 create mode 100644 stubs/change-state-handler.c
 create mode 100755 tests/qemu-iotests/192
 create mode 100644 tests/qemu-iotests/192.out

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2.13.4