Re: [PATCH v5 2/3] block: io-uring: add READV_PI/WRITEV_PI operations

[Jens Axboe <axboe@kernel.dk>]

On 9/20/22 8:46 AM, Alexander V. Buev wrote:
> Added new READV_PI/WRITEV_PI operations to io_uring.
> Added new pi_addr & pi_len fields to SQE struct.
> Added new IOCB_USE_PI flag to kiocb struct.
> Use kiocb->private pointer to pass PI data
> iterator to low layer.

Minor nit - please format commit message lines to 72-74 chars.

In general, I think this feature is useful. I do echo Keith's response
that it should probably be named a bit differently, as PI is just one
use case of this.

But for this patch in particular, not a huge fan of the rote copying of
rw.c into a new file. Now we have to patch two different spots whenever
a bug is found in there, that's not very maintainable. I do appreciate
the fact that this keeps the PI work out of the fast path for
read/write, but I do think this warrants a bit of refactoring work first
to ensure that there are helpers that can be shared between rw and
rw_pi. That definitely needs to be solved before this can be considered
for inclusion.

-- 
Jens Axboe