multiwrite patches for 2.2

This adds some preparing patches for upcoming multiwrite modifications. I will leave the dangerous patches for after 2.2 release.

Due to oversized lines in the iotest output please pull from:
[email protected]:plieven/qemu.git -b multiwrite_22_v3

v2->v3: - Removed statistic output for merged read requests [Eric]
- Fixed double s-o-b line in Patch 3 [Eric]
- Fixed iotest in Patch 5 [Max]. Renamed from 108 to 109.

v1->v2: - incorporated Max's comments, but did not display the default
value for write merging (Patch 3) in the HMP since we do not do it for other commands. I would change this when the default changes.
- added an iotest for the write-merging cmdline parameter [Max]
- fixed iotest 067 output

Peter Lieven (6):
block: add accounting for merged requests
block: introduce bdrv_runtime_opts
block: add a knob to disable multiwrite_merge hw/virtio-blk: add a constant for max number of merged requests
block: add qemu-iotest for write-merge parameter
block: fix qemu-iotest reference output for test 067

 block.c                    |   49 +++++++++++++++++--
 block/accounting.c         |    7 +++
 block/qapi.c               |    2 +
 hmp.c                      |    8 +++-
 hw/block/virtio-blk.c      |    4 +-
 include/block/accounting.h |    3 ++
 include/block/block_int.h  |    1 +
 qapi/block-core.json       |   17 ++++++-
 qemu-options.hx            |    1 +
 qmp-commands.hx            |    2 +
 tests/qemu-iotests/067.out |   10 ++--
 tests/qemu-iotests/109     |  113 ++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/109.out |   68 ++++++++++++++++++++++++++
 tests/qemu-iotests/group   |    1 +
 14 files changed, 272 insertions(+), 14 deletions(-)
 create mode 100755 tests/qemu-iotests/109
 create mode 100644 tests/qemu-iotests/109.out

1.7.9.5