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Date: Wed, 18 Feb 2026 07:51:07 +0100
From: Christoph Hellwig <hch@lst.de>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>, Pankaj Raghav <pankaj.raghav@linux.dev>,
	linux-xfs@vger.kernel.org, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org, lsf-pc@lists.linux-foundation.org,
	Andres Freund <andres@anarazel.de>, djwong@kernel.org,
	john.g.garry@oracle.com, willy@infradead.org, ritesh.list@gmail.com,
	jack@suse.cz, ojaswin@linux.ibm.com,
	Luis Chamberlain <mcgrof@kernel.org>, dchinner@redhat.com,
	Javier Gonzalez <javier.gonz@samsung.com>, gost.dev@samsung.com,
	tytso@mit.edu, p.raghav@samsung.com, vi.shah@samsung.com
Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Buffered atomic writes
Message-ID: <20260218065107.GA9019@lst.de>
References: <d0c4d95b-8064-4a7e-996d-7ad40eb4976b@linux.dev> <20260217055103.GA6174@lst.de> <CAOQ4uxgdWvJPAi6QMWQjWJ2TnjO=JP84WCgQ+ShM3GiikF=bSw@mail.gmail.com>
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On Tue, Feb 17, 2026 at 10:23:36AM +0100, Amir Goldstein wrote:
> On Tue, Feb 17, 2026 at 8:00 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > I think a better session would be how we can help postgres to move
> > off buffered I/O instead of adding more special cases for them.
> 
> Respectfully, I disagree that DIO is the only possible solution.
> Direct I/O is a legit solution for databases and so is buffered I/O
> each with their own caveats.

Maybe.  Classic buffered I/O is not a legit solution for doing atomic
I/Os, and if Postgres is desperate to use that, something like direct
I/O (including the proposed write though semantics) are the only sensible
choice.