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Date:   Wed, 9 Aug 2023 06:41:17 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Hugh Dickins <hughd@google.com>
Cc:     Christian Brauner <brauner@kernel.org>,
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        Topi Miettinen <toiwoton@gmail.com>,
        Yu Kuai <yukuai3@huawei.com>, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH vfs.tmpfs 4/5] tmpfs: trivial support for direct IO
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Please do not add a new ->direct_IO method.  I'm currently working hard
on removing it, just set FMODE_CAN_ODIRECT and handle the fallback in
your read_iter/write_iter methods.

But if we just start claiming direct I/O support for file systems that
don't actually support it, I'm starting to seriously wonder why we
bother with the flag at all and don't just allow O_DIRECT opens
to always succeed..