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 for 2.4.0-rc1

# gpg: Signature made Tue Jul 14 16:15:35 2015 BST using RSA key ID C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"

* remotes/kevin/tags/for-upstream:
  rbd: fix ceph settings precedence
  rbd: make qemu's cache setting override any ceph setting
  MAINTAINERS: update email address
  rbd: remove unused constants and fields
  block: Fix backing file child when modifying graph
  block: Reorder cleanups in bdrv_close()
  block: Introduce bdrv_unref_child()
  block: Introduce bdrv_open_child()
  block: Move bdrv_attach_child() calls up the call chain
  nvme: properly report volatile write caches
  nvme: implement the Flush command

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