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Date:   Tue, 10 May 2022 11:54:37 -0700
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Amir Goldstein <amir73il@gmail.com>,
        Dave Chinner <david@fromorbit.com>,
        linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: [QUESTION] Upgrade xfs filesystem to reflink support?
Message-ID: <20220510185437.GB27195@magnolia>
References: <CAOQ4uxjBR_Z-j_g8teFBih7XPiUCtELgf=k8=_ye84J00ro+RA@mail.gmail.com>
 <20220509182043.GW27195@magnolia>
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On Tue, May 10, 2022 at 02:29:35AM -0700, Christoph Hellwig wrote:
> On Mon, May 09, 2022 at 11:20:43AM -0700, Darrick J. Wong wrote:
> > > Is there any a priori NACK or exceptional challenges w.r.t implementing
> > > upgrade of xfs to reflink support?
> > 
> > No, just lack of immediate user demand + time to develop and merge code
> > + time to QA the whole mess to make sure it doesn't introduce any
> > messes.
> 
> I also have vague memory I did an in-kernel online upgrade back in the
> day but we decided to not bother in the end.  Maybe some list archive
> search could find it.

https://lore.kernel.org/linux-xfs/1464877150-20457-1-git-send-email-hch@lst.de/

Note that your version did live upgrades of mounted filesystems
whereas the one I wrote does it as part of xfs_repair, which means we
have a somewhat better guarantee that the fs will be in decent shape
afterwards.

--D