Re: [PATCH] linux-aio: add IO_CMD_FDSYNC command support

[Prasad Pandit <ppandit@redhat.com>]

Hi,

On Thu, 7 Mar 2024 at 19:21, Kevin Wolf <kwolf@redhat.com> wrote:
> Kernel support for this is "relatively" new, added in 2018. Should we
> fall back to the thread pool if we receive -EINVAL?

laio_co_submit
  laio_do_submit
    ioq_submit
      io_submit

* When an aio operation is not supported by the kernel, io_submit()
call would return '-EINVAL', indicating that the specified (_FDSYNC)
operation is invalid for the file descriptor. ie. an error (-EINVAL)
needs to reach the 'laio_co_submit' routine above, to make its caller
fall back on the thread-pool functionality as default.

* Strangely the 'ioq_submit' routine above ignores the return value
from io_submit and returns void. I think we need to change that to be
able to fall back on the thread-pool functionality. I'll try to see if
such a change works as expected. Please let me know if there's another
way to fix this.

Thank you.
---
  - Prasad