Re: Direct I/O

On Wed, Apr 12, 2023 at 2:56 PM Christoph Berg <myon(at)debian(dot)org> wrote:
> I'm hitting a panic in t_004_io_direct. The build is running on
> overlayfs on tmpfs/ext4 (upper/lower) which is probably a weird
> combination but has worked well for building everything over the last
> decade. On Debian unstable:
>
> PANIC: could not open file "pg_wal/000000010000000000000001": Invalid argument

Hi Christoph,

That's an interesting one. I was half expecting to see that on some
unusual systems, which is why I made the test check which OS it is and
exclude those that are known to fail with EINVAL or ENOTSUPP on their
common/typical file systems. But if it's going to be Linux, that's
not going to work. I have a new idea: perhaps it is possible to try
to open a file with O_DIRECT from perl, and if it fails like that,
skip the test. Looking into that now.