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 -- 2.21.3
