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 -- 2.21.3