Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches for 2.11.0-rc3

# gpg: Signature made Wed 29 Nov 2017 15:25:13 GMT
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <[email protected]>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  block/nfs: fix nfs_client_open for filesize greater than 1TB
  blockjob: reimplement block_job_sleep_ns to allow cancellation
  blockjob: introduce block_job_do_yield
  blockjob: remove clock argument from block_job_sleep_ns
  block: Expect graph changes in bdrv_parent_drained_begin/end
  blockjob: Remove the job from the list earlier in block_job_unref()
  QAPI & interop: Clarify events emitted by 'block-job-cancel'
  qemu-options: Mention locking option of file driver
  docs: Add image locking subsection
  iotests: fix 075 and 078

Signed-off-by: Peter Maydell <[email protected]>