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Date:   Sun, 21 Aug 2022 01:53:33 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Jaegeuk Kim <jaegeuk@kernel.org>, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
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        linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH v4 6/9] f2fs: don't allow DIO reads but not DIO writes
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On Mon, Aug 15, 2022 at 05:55:45PM -0700, Eric Biggers wrote:
> So if the zoned device feature becomes widely adopted, then STATX_DIOALIGN will
> be useless on all Android devices?  That sounds undesirable.  Are you sure that

We just need to fix f2fs to support direct I/O on zone devices.  There
is not good reason not to support it, in fact the way how zoned devices
requires appends with the Zone Append semantics makes direct I/O way
safer than how f2fs does direct I/O currently on non-zoned devices.

Until then just supporting direct I/O reads on zoned devices for f2fs
seems like a really bad choice given that it will lead to nasty cache
incoherency.