Re: [PATCH v5 net-next 02/36] iov_iter: DDP copy to iter/pages

On Fri, Jul 23, 2021 at 07:03:02AM +0200, Christoph Hellwig wrote:

On Thu, Jul 22, 2021 at 11:23:38PM +0300, Boris Pismenny wrote:

quoted

This routine, like other changes in this file, replicates the logic in
memcpy_to_page. The only difference is that "ddp" avoids copies when the
copy source and destinations buffers are one and the same.

Now why can't we just make that change to the generic routine?

Doable... replace memcpy(base, addr + off, len) with
	base != addr + off && memcpy(base, addr + off, len)
in _copy_to_iter() and be done with that...