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

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

Block layer patches:

- Fix slow pre-zeroing in qemu-img convert
- Test case for block job pausing on I/O errors

# gpg: Signature made Tue 26 Mar 2019 15:28:00 GMT
# gpg:                using RSA key 7F09B272C88F2FD6
# 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:
  qemu-io: Add write -n for BDRV_REQ_NO_FALLBACK
  qemu-img: Use BDRV_REQ_NO_FALLBACK for pre-zeroing
  file-posix: Support BDRV_REQ_NO_FALLBACK for zero writes
  block: Advertise BDRV_REQ_NO_FALLBACK in filter drivers
  block: Add BDRV_REQ_NO_FALLBACK
  block: Remove error messages in bdrv_make_zero()
  iotests: add 248: test resume mirror after auto pause on ENOSPC

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