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

Block layer patches:

- qcow2: Skip copy-on-write when allocating a zero cluster
- qemu-img: add support for rate limit in qemu-img convert/commit
- Fix deadlock when deleting a block node during drain_all

# gpg: Signature made Tue 27 Oct 2020 15:14:07 GMT
# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  block: End quiescent sections when a BDS is deleted
  qcow2: Skip copy-on-write when allocating a zero cluster
  qcow2: Report BDRV_BLOCK_ZERO more accurately in bdrv_co_block_status()
  qemu-img: add support for rate limit in qemu-img convert
  qemu-img: add support for rate limit in qemu-img commit

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>