[PATCH v3 00/12] preallocate filter

[Vladimir Sementsov-Ogievskiy]

Hi all!

Here is a filter, which does preallocation on write.

In Virtuozzo we have to deal with some custom distributed storage
solution, where allocation is relatively expensive operation. We have to
workaround it in Qemu, so here is a new filter.

Patches 1-10 introduces the new filter and suggested to be merged
to master.

Patches 11,12 are here just to show how we are going to use the feature.
I don't know can they be somehow generally useful, ideas are welcome.

Difference from v1:
1-6 are new and substitutes bdrv_co_range_try_lock mechanism used in v1
07: add note to docs/system/qemu-block-drivers.rst.inc
    add open options
    rebase on new BDRV_REQ_NO_WAIT flag
    drop bs->file check in _co_flush()
    add active logic, to make it possible to insert filter dynamically
08,09: new
10: - use new iotests.verify_o_direct()
10: - add qemu-img check call
11,12: not for commit

Vladimir Sementsov-Ogievskiy (12):
  block: simplify comment to BDRV_REQ_SERIALISING
  block/io.c: drop assertion on double waiting for request serialisation
  block/io: split out bdrv_find_conflicting_request
  block/io: bdrv_wait_serialising_requests_locked: drop extra bs arg
  block: bdrv_mark_request_serialising: split non-waiting function
  block: introduce BDRV_REQ_NO_WAIT flag
  block: introduce preallocate filter
  iotests.py: add verify_o_direct helper
  iotests.py: add filter_img_check
  iotests: add 298 to test new preallocate filter driver
  block: add bdrv_is_file_on_fuse helper
  block/qcow2: automatically insert preallocate filter when on FUSE

 docs/system/qemu-block-drivers.rst.inc |  26 +++
 qapi/block-core.json                   |  20 +-
 include/block/block.h                  |  22 +-
 include/block/block_int.h              |   3 +-
 block/file-posix.c                     |  23 +-
 block/io.c                             | 131 ++++++-----
 block/preallocate.c                    | 291 +++++++++++++++++++++++++
 block/qcow2.c                          |  38 ++++
 block/Makefile.objs                    |   1 +
 tests/qemu-iotests/298                 |  50 +++++
 tests/qemu-iotests/298.out             |   6 +
 tests/qemu-iotests/group               |   1 +
 tests/qemu-iotests/iotests.py          |  10 +
 13 files changed, 554 insertions(+), 68 deletions(-)
 create mode 100644 block/preallocate.c
 create mode 100644 tests/qemu-iotests/298
 create mode 100644 tests/qemu-iotests/298.out

-- 
2.18.0