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Date:   Mon, 27 Mar 2023 21:02:26 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org,
        brauner@kernel.org
Subject: Re: [PATCHSET 0/2] Turn single segment imports into ITER_UBUF
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On Mon, Mar 27, 2023 at 12:59:09PM -0600, Jens Axboe wrote:

> > That's a great idea. Two questions - do we want to make that
> > WARN_ON_ONCE()? And then do we want to include a WARN_ON_ONCE for a
> > non-supported type? Doesn't seem like high risk as they've all been used
> > with ITER_IOVEC until now, though.
> 
> Scratch that last one, user_backed should double as that as well. At
> least currently, where ITER_UBUF and ITER_IOVEC are the only two
> iterators that hold user backed memory.

Quite.  As for the WARN_ON_ONCE vs. WARN_ON...  No preferences, really.