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Date:   Tue, 12 Dec 2023 10:16:13 -0500
From:   "Theodore Ts'o" <tytso@mit.edu>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     John Garry <john.g.garry@oracle.com>,
        Ojaswin Mujoo <ojaswin@linux.ibm.com>,
        linux-ext4@vger.kernel.org, Ritesh Harjani <ritesh.list@gmail.com>,
        linux-kernel@vger.kernel.org,
        "Darrick J . Wong" <djwong@kernel.org>,
        linux-block@vger.kernel.org, linux-xfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, dchinner@redhat.com
Subject: Re: [RFC 0/7] ext4: Allocator changes for atomic write support with
 DIO
Message-ID: <20231212151613.GA142380@mit.edu>
References: <cover.1701339358.git.ojaswin@linux.ibm.com>
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On Tue, Dec 12, 2023 at 05:10:42AM -0800, Christoph Hellwig wrote:
> On Tue, Dec 12, 2023 at 07:46:51AM +0000, John Garry wrote:
> > It is assumed that the user will fallocate/dd the complete file before
> > issuing atomic writes, and we will have extent alignment and length as
> > required.
> 
> I don't think that's a long time maintainable usage model.

For databases that are trying to use this to significantly improve
their performance by eliminating double writes, the allocation and
writes are being done by a single process.  So for *that* use case, it
is quite maintainable.

Cheers,

						- Ted