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Date: Thu, 29 Aug 2024 05:54:06 +0200
From: Christoph Hellwig <hch@lst.de>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>, Christian Brauner <brauner@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Chandan Babu R <chandan.babu@oracle.com>,
	Brian Foster <bfoster@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	Jan Kara <jack@suse.cz>, "Darrick J. Wong" <djwong@kernel.org>,
	Theodore Ts'o <tytso@mit.edu>, linux-block@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-ext4@vger.kernel.org
Subject: Re: [PATCH 4/6] xfs: call xfs_flush_unmap_range from
 xfs_free_file_space
Message-ID: <20240829035406.GB4023@lst.de>
References: <20240827065123.1762168-1-hch@lst.de> <20240827065123.1762168-5-hch@lst.de> <Zs/lA5FJoF0Zd9Ip@dread.disaster.area>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, Aug 29, 2024 at 01:03:31PM +1000, Dave Chinner wrote:
> > @@ -848,6 +848,14 @@ xfs_free_file_space(
> >  	if (len <= 0)	/* if nothing being freed */
> >  		return 0;
> >  
> > +	/*
> > +	 * Now AIO and DIO has drained we flush and (if necessary) invalidate
> > +	 * the cached range over the first operation we are about to run.
> > +	 */
> > +	error = xfs_flush_unmap_range(ip, offset, len);
> > +	if (error)
> > +		return error;
> > +
> >  	startoffset_fsb = XFS_B_TO_FSB(mp, offset);
> >  	endoffset_fsb = XFS_B_TO_FSBT(mp, offset + len);
> 
> Ok, so if we ever change the zeroing implementation to not punch a
> hole first, we're going to have to make sure we add this to whatever
> new zeroing implementation we have.
> 
> Can you leave a comment in the FALLOC_FL_ZERO_RANGE implementation
> code that notes it currently relies on the xfs_flush_unmap_range()
> in xfs_free_file_space() for correct operation?

Sure.