[PATCH v2 0/9] 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.

For the details refer to original cover-letter
"[PATCH 0/5] preallocate filter"
https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg06443.html

v2:
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()
08: new
09: use new iotests.verify_o_direct()

Vladimir Sementsov-Ogievskiy (9):
  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: 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                             | 131 +++++++-----
 block/preallocate.c                    | 264 +++++++++++++++++++++++++
 block/Makefile.objs                    |   1 +
 tests/qemu-iotests/298                 |  46 +++++
 tests/qemu-iotests/298.out             |   5 +
 tests/qemu-iotests/group               |   1 +
 tests/qemu-iotests/iotests.py          |   6 +
 12 files changed, 457 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