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Date:   Sun, 27 Feb 2022 22:15:16 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     jhubbard.send.patches@gmail.com
Cc:     Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
        Christoph Hellwig <hch@infradead.org>,
        Dave Chinner <dchinner@redhat.com>,
        "Darrick J . Wong" <djwong@kernel.org>,
        Theodore Ts'o <tytso@mit.edu>,
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        linux-xfs@vger.kernel.org, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>,
        John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH 3/6] block, fs: assert that key paths use iovecs, and
 nothing else
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References: <20220227093434.2889464-1-jhubbard@nvidia.com>
 <20220227093434.2889464-4-jhubbard@nvidia.com>
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On Sun, Feb 27, 2022 at 01:34:31AM -0800, jhubbard.send.patches@gmail.com wrote:
> From: John Hubbard <jhubbard@nvidia.com>
> 
> Upcoming changes to Direct IO will change it from acquiring pages via
> get_user_pages_fast(), to calling pin_user_pages_fast() instead.
> 
> Place a few assertions at key points, that the pages are IOVEC (user
> pages), to enforce the assumptions that there are no kernel or pipe or
> other odd variations being passed.

Umm...  And what should happen when O_DIRECT file gets passed to splice()?