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Date: Mon, 17 Jun 2024 08:46:03 +0200
From: Christoph Hellwig <hch@lst.de>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>, "Darrick J. Wong" <djwong@kernel.org>,
	chandanbabu@kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/5] xfs: don't treat append-only files as having
 preallocations
Message-ID: <20240617064603.GA18484@lst.de>
References: <171821431745.3202459.12391135011047294097.stgit@frogsfrogsfrogs> <171821431777.3202459.4876836906447539030.stgit@frogsfrogsfrogs> <ZmqLyfdH5KGzSYDY@dread.disaster.area> <20240613082855.GA22403@lst.de> <Zm/DoN5npLCd+Y/n@dread.disaster.area>
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On Mon, Jun 17, 2024 at 03:03:28PM +1000, Dave Chinner wrote:
> > That case should be covered by the XFS_IDIRTY_RELEASE, at least
> > except for O_SYNC workloads. 
> 
> Ah, so I fixed the problem independently 7 or 8 years later to fix
> Linux NFS server performance issues. Ok, that makes removing the
> flag less bad, but I still don't see the harm in keeping it there
> given that behaviour has existed for the past 20 years....

I'm really kinda worried about these unaccounted preallocations lingering
around basically forever.  Note that in current mainline there actually
is a path removing them more or less accidentally when there are
delalloc blocks in a can_free_eofblocks path with force == true,
but that's going away with the next patch.