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Date: Fri, 26 Jan 2024 13:32:05 -0800
From: Luis Chamberlain <mcgrof@kernel.org>
To: Matthew Wilcox <willy@infradead.org>,
	Eric Biggers <ebiggers@google.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
	Yangtao Li <frank.li@vivo.com>, chao@kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, fengnanchang@gmail.com,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	vishal.moola@gmail.com,
	Javier =?iso-8859-1?Q?Gonz=E1lez?= <javier.gonz@samsung.com>,
	Adam Manzanares <a.manzanares@samsung.com>
Subject: Re: [PATCH] f2fs: Support enhanced hot/cold data separation for f2fs
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Sender: Luis Chamberlain <mcgrof@infradead.org>

On Fri, Jan 26, 2024 at 09:01:06PM +0000, Matthew Wilcox wrote:
> On Thu, Jan 25, 2024 at 12:54:47PM -0800, Luis Chamberlain wrote:
> > On Thu, Jan 25, 2024 at 08:47:39PM +0000, Matthew Wilcox wrote:
> > > On Wed, Dec 07, 2022 at 12:51:13PM -0800, Luis Chamberlain wrote:
> > > > Me and Pankaj are very interested in helping on this front. And so we'll
> > > > start to organize and talk every week about this to see what is missing.
> > > > First order of business however will be testing so we'll have to
> > > > establish a public baseline to ensure we don't regress. For this we intend
> > > > on using kdevops so that'll be done first.
> > > > 
> > > > If folks have patches they want to test in consideration for folio /
> > > > iomap enhancements feel free to Cc us :)
> > > > 
> > > > After we establish a baseline we can move forward with taking on tasks
> > > > which will help with this conversion.
> > > 
> > > So ... it's been a year.  How is this project coming along?  There
> > > weren't a lot of commits to f2fs in 2023 that were folio related.
> > 
> > The review at LSFMM revealed iomap based filesystems were the priority
> > and so that has been the priority. Once we tackle that and get XFS
> > support we can revisit which next fs to help out with. Testing has been
> > a *huge* part of our endeavor, and naturally getting XFS patches up to
> > what is required has just taken a bit more time. But you can expect
> > patches for that within a month or so.
> 
> Is anyone working on the iomap conversion for f2fs?

It already has been done for direct IO by Eric as per commit a1e09b03e6f5
("f2fs: use iomap for direct I/O"), not clear to me if anyone is working
on buffered-io. Then f2fs_commit_super() seems to be the last buffer-head
user, and its not clear what the replacement could be yet.

Jaegeuk, Eric, have you guys considered this?

  Luis