Re: [PATCH 0/3] implement direct IO with integrity

[Jens Axboe <axboe@kernel.dk>]

On 10/28/21 9:18 AM, Christoph Hellwig wrote:
> On Thu, Oct 28, 2021 at 09:13:07AM -0600, Jens Axboe wrote:
>> A couple of suggestions on this:
>>
>> 1) Don't think we need an IOSQE flag, those are mostly reserved for
>>    modifiers that apply to (mostly) all kinds of requests
>> 2) I think this would be cleaner as a separate command, rather than
>>    need odd adjustments and iov assumptions. That also gets it out
>>    of the fast path.
>>
>> I'd add IORING_OP_READV_PI and IORING_OP_WRITEV_PI for this, I think
>> you'd end up with a much cleaner implementation that way.
> 
> Agreed.  I also wonder if we could do saner paramter passing.
> E.g. pass a separate pointer to the PI data if we find space for
> that somewhere in the SQE.

Yeah, the whole "put PI in the last iovec" makes the code really ugly
dealing with it. Would be a lot cleaner to separate the two. IMHO this
is largely a work-around that you'd apply to syscall interfaces that
only take the iovec, but we don't need to work around it here if we can
define a clean command upfront.

And if we don't need vectored requests for the data part, then even
better. That one might not be feasible, but figured I'd toss it out
there.

-- 
Jens Axboe