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

Block layer patches

# gpg: Signature made Thu 17 Mar 2016 15:49:29 GMT using RSA key ID C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"

* remotes/kevin/tags/for-upstream: (29 commits)
  iotests: Test QUORUM_REPORT_BAD in fifo mode
  quorum: Emit QUORUM_REPORT_BAD for reads in fifo mode
  block: Use blk_co_pwritev() in blk_co_write_zeroes()
  block: Use blk_aio_prwv() for aio_read/write/write_zeroes
  block: Use blk_prw() in blk_pread()/blk_pwrite()
  block: Use blk_co_pwritev() in blk_write_zeroes()
  block: Pull up blk_read_unthrottled() implementation
  block: Use blk_co_pwritev() for blk_write()
  block: Use blk_co_preadv() for blk_read()
  block: Use BdrvChild in BlockBackend
  block: Remove bdrv_states list
  block: Use bdrv_next() instead of bdrv_states
  block: Rewrite bdrv_next()
  block: Add blk_next_root_bs()
  block: Add bdrv_next_monitor_owned()
  block: Move some bdrv_*_all() functions to BB
  blockdev: Remove blk_hide_on_behalf_of_hmp_drive_del()
  blockdev: Split monitor reference from BB creation
  blockdev: Separate BB name management
  blockdev: Add list of all BlockBackends
  ...

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