[PATCH v4 00/10] 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.

v4:
01-04: add r-bs
05: add coroutine_fn tag
06: use QEMU_LOCK_GUARD and fix reqs_lock leak
07: grammar
08-10: add r-b

I decided to not resend patches 11-12, for which I don't know
how they can be applied universally. I think I'll keep them
downstream only for now, and probably drop in future if we
can insert filter in libvirt.

Vladimir Sementsov-Ogievskiy (10):
  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

 docs/system/qemu-block-drivers.rst.inc |  26 +++
 qapi/block-core.json                   |  20 +-
 include/block/block.h                  |  20 +-
 include/block/block_int.h              |   3 +-
 block/file-posix.c                     |   2 +-
 block/io.c                             | 130 ++++++-----
 block/preallocate.c                    | 291 +++++++++++++++++++++++++
 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 +
 12 files changed, 492 insertions(+), 68 deletions(-)
 create mode 100644 block/preallocate.c
 create mode 100644 tests/qemu-iotests/298
 create mode 100644 tests/qemu-iotests/298.out

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2.21.3