[Qemu-devel] [PATCH v2 0/2] Optimize alignment probing

[Nir Soffer <nirsof@gmail.com>]

When probing unallocated area on XFS filesystem we cannot detect request
alignment and we fallback to safe value which may not be optimal. Avoid this
fallback by always allocating the first block when creating a new image or
resizing empty image.

I tested v1 only with -raw format, and missed some changes in qcow2
tests creating raw images during the tests. This time I tested with both
-raw and -qcow2.

Changes in v2:
- Support file descriptor opened with O_DIRECT (e.g. in block_resize) (Max)
- Remove unneeded change in 160 (Max)
- Fix block filter in 175 on filesystem allocating extra blocks (Max)
- Comment why we ignore errors in allocte_first_block() (Max)
- Comment why allocate_first_block() is needed in FALLOC mode (Max)
- Clarify commit message about user visible changes (Maxim)
- Fix 178.out.qcow2
- Fix 150.out with -qcow2 by spliting to 150.out.{raw,qcow2}
- Add test for allocate_first_block() with block_resize (Max)
- Drop provisioing tests results since I ran them only once

v1 was here:
https://lists.nongnu.org/archive/html/qemu-block/2019-08/msg00821.html

Nir Soffer (2):
  block: posix: Always allocate the first block
  iotests: Test allocate_first_block() with O_DIRECT

 block/file-posix.c                            | 43 ++++++++++++++++++
 tests/qemu-iotests/{150.out => 150.out.qcow2} |  0
 tests/qemu-iotests/150.out.raw                | 12 +++++
 tests/qemu-iotests/175                        | 44 ++++++++++++++++---
 tests/qemu-iotests/175.out                    | 16 +++++--
 tests/qemu-iotests/178.out.qcow2              |  4 +-
 tests/qemu-iotests/221.out                    | 12 +++--
 tests/qemu-iotests/253.out                    | 12 +++--
 8 files changed, 123 insertions(+), 20 deletions(-)
 rename tests/qemu-iotests/{150.out => 150.out.qcow2} (100%)
 create mode 100644 tests/qemu-iotests/150.out.raw

-- 
2.20.1