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Date:   Fri, 30 Nov 2018 21:25:03 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-aio@kvack.org, hch@lst.de
Subject: Re: [PATCH 24/27] block: implement bio helper to add iter kvec pages
 to bio
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On Fri, Nov 30, 2018 at 02:16:38PM -0700, Jens Axboe wrote:
> >> Would this make you happy:
> >>
> >> if (!is_vmalloc_addr(kv->iov_base))
> >>         page = virt_to_page(kv->iov_base);
> >> else
> >>         page = vmalloc_to_page(kv->iov_base);
> > 
> > Free advice: don't ever let Linus see anything along those lines.  Results
> > tend to be colourful...
> 
> We already have those lines in the kernel, XFS for instance. Al, could you
> please try to be helpful instead of being deliberately obtuse?

Again, the last time something like that had been suggested, Linus had replied
with a very impressive rant.  I *did* propose pretty much that, and reaction
was basically "hell no, not in general-purpose primitives".  Precisely about
iov_iter stuff.  A part of that was due to touching page refcounts, but quite
a bit wasn't.