Re: [PATCH 3/8] io_uring/rw: implement vectored registered rw

[Pavel Begunkov <asml.silence@gmail.com>]

On 3/3/25 23:01, Caleb Sander Mateos wrote:
...
>> +       /* pad iovec to the right */
>> +       iovec_off = io->vec.nr - uvec_segs;
>> +       iov = io->vec.iovec + iovec_off;
>> +       uvec = u64_to_user_ptr(rw->addr);
>> +       res = iovec_from_user(uvec, uvec_segs, uvec_segs, iov,
>> +                             io_is_compat(req->ctx));
>> +       if (IS_ERR(res))
>> +               return PTR_ERR(res);
>> +
>> +       ret = io_import_reg_vec(ddir, &io->iter, req, &io->vec,
>> +                               uvec_segs, iovec_off, 0);
> 
> So the iovecs are being imported at prep time rather than issue time?
> I suppose since only user registered buffers are allowed and not
> kernel bvecs, you aren't concerned about interactions with the ublk

It's a question of generic io_uring policy and has nothing
to do with ublk. Thinking about it in terms of a specific
user wouldn't be productive.

-- 
Pavel Begunkov