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Date:   Sun, 22 May 2022 10:36:00 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        linux-fsdevel@vger.kernel.org
Subject: Re: [RFC] what to do with IOCB_DSYNC?
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On Sun, May 22, 2022 at 11:23:43AM +0100, Matthew Wilcox wrote:
> On Sun, May 22, 2022 at 09:45:09AM +0200, Christoph Hellwig wrote:
> > On Sat, May 21, 2022 at 04:14:07PM -0600, Jens Axboe wrote:
> > > Then we're almost on par, and it looks like we just need to special case
> > > iov_iter_advance() for the nr_segs == 1 as well to be on par. This is on
> > > top of your patch as well, fwiw.
> > > 
> > > It might make sense to special case the single segment cases, for both
> > > setup, iteration, and advancing. With that, I think we'll be where we
> > > want to be, and there will be no discernable difference between the iter
> > > paths and the old style paths.
> > 
> > A while ago willy posted patches to support a new ITER type for direct
> > userspace pointer without iov.  It might be worth looking through the
> > archives and test that.
> 
> https://lore.kernel.org/linux-fsdevel/Yba+YSF6mkM%2FGYlK@casper.infradead.org/

	Direct kernel pointer, surely?  And from a quick look,
iov_iter_is_kaddr() checks for the wrong value...