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

Block layer patches:

- file-posix: Check correct file type (regular file for 'file',
  character or block device for 'host_device'/'host_cdrom')
- scsi-disk: Block Device Characteristics emulation fix
- qemu-img: Consider required alignment for sparse area detection
- Documentation and test improvements

# gpg: Signature made Thu 12 Jul 2018 17:29:17 BST
# gpg:                using RSA key 7F09B272C88F2FD6
# 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:
  qemu-img: align result of is_allocated_sectors
  scsi-disk: Block Device Characteristics emulation fix
  iotests: add test 226 for file driver types
  file-posix: specify expected filetypes
  qemu-img: Document copy offloading implications with -S and -c
  iotests: nbd: Stop qemu-nbd before remaking image
  iotests: 153: Fix dead code

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