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Date: Fri, 13 Dec 2024 06:09:14 +0100
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Carlos Maiolino <cem@kernel.org>,
	Hans Holmberg <hans.holmberg@wdc.com>, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 08/43] xfs: report the correct dio alignment for COW
 inodes
Message-ID: <20241213050914.GE5630@lst.de>
References: <20241211085636.1380516-1-hch@lst.de> <20241211085636.1380516-9-hch@lst.de> <20241212212953.GT6678@frogsfrogsfrogs>
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On Thu, Dec 12, 2024 at 01:29:53PM -0800, Darrick J. Wong wrote:
> > +	/*
> > +	 * On COW inodes we are forced to always rewrite an entire file system
> > +	 * block.
> 
> That's not quite accurate -- we're always forced to write an entire file
> allocation unit so that the rest of the bmap code doesn't have to deal
> with a file range that's mapped to multiple different space extents.
> For all the existing reflink scenarios the allocation unit is always an
> fsblock so this is a trifling difference.

Which right now is a block until we support horrors such as reflink
on larget rtextsize inodes or the forcealign stuff.  But yes, it
could use the helper.