Re: [PATCH] file-posix: Fix alignment after reopen changing O_DIRECT

[Hanna Reitz <hreitz@redhat.com>]

On 04.11.21 12:31, Kevin Wolf wrote:
> At the end of a reopen, we already call bdrv_refresh_limits(), which
> should update bs->request_alignment according to the new file
> descriptor. However, raw_probe_alignment() relies on s->needs_alignment
> and just uses 1 if it isn't set. We neglected to update this field, so
> starting with cache=writeback and then reopening with cache=none means
> that we get an incorrect bs->request_alignment == 1 and unaligned
> requests fail instead of being automatically aligned.
>
> Fix this by recalculating s->needs_alignment in raw_refresh_limits()
> before calling raw_probe_alignment().
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block/file-posix.c         | 20 ++++++++++++++++----
>   tests/qemu-iotests/142     | 22 ++++++++++++++++++++++
>   tests/qemu-iotests/142.out | 15 +++++++++++++++
>   3 files changed, 53 insertions(+), 4 deletions(-)

Reviewed-by: Hanna Reitz <hreitz@redhat.com>