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Date:   Wed, 2 Nov 2022 01:15:55 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Dave Chinner <david@fromorbit.com>
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Subject: Re: [PATCH] xfs: redirty eof folio on truncate to avoid filemap flush
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On Sun, Oct 30, 2022 at 09:01:31AM +1100, Dave Chinner wrote:
> Right, think of iomap_truncate_page() as having exactly the same
> responsibilites as block_truncate_page() has for filesystems using
> bufferheads. i.e. both functions need to ensure the disk contents
> are correctly zeroed such that the caller can safely call
> truncate_setsize() afterwards resulting in both the on-disk state
> and in-memory state remaining coherent.

XFS always had these kinds of hacks even when it was using
block_truncate_page.  That being said, I fully agree that handling
it in iomap is the absolutely right thing to do and we should have
done it earlier.