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. v5: rewrite patch 08 as Nir suggested 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 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 | 16 ++ 12 files changed, 498 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