Re: [PATCH RFC] io_uring: extend io_uring_sqe flags bits

[Ming Lei <ming.lei@redhat.com>]

On Thu, Oct 31, 2024 at 03:22:18PM -0600, Jens Axboe wrote:
> In hindsight everything is clearer, but it probably should've been known
> that 8 bits of ->flags would run out sooner than later. Rather than
> gobble up the last bit for a random use case, add a bit that controls
> whether or not ->personality is used as a flags2 argument. If that is
> the case, then there's a new IOSQE2_PERSONALITY flag that tells io_uring
> which personality field to read.
> 
> While this isn't the prettiest, it does allow extending with 15 extra
> flags, and retains being able to use personality with any kind of
> command. The exception is uring cmd, where personality2 will overlap
> with the space set aside for SQE128. If they really need that, then that

The space is the 1st `short` for uring_cmd, instead of SQE128 only.

Also it is overlapped with ->optval and ->addr3, so just wondering why not
use ->__pad2?

Another ways is to use __pad2 for sqe2_flags for non-uring_cmd, and for
uring_cmd, use its top 16 as sqe2_flags, this way does work, but it is
just a bit ugly to use.


Thanks,
Ming