From: Matthew Wilcox <willy@infradead.org>
To: Amir Goldstein <amir73il@gmail.com>
Cc: lsf-pc@lists.linux-foundation.org,
Al Viro <viro@zeniv.linux.org.uk>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
Chris Mason <clm@fb.com>, Miklos Szeredi <miklos@szeredi.hu>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>
Subject: Re: [LSF/MM TOPIC] Sharing file backed pages
Date: Wed, 23 Jan 2019 11:10:47 -0800 [thread overview]
Message-ID: <20190123191046.GA15311@bombadil.infradead.org> (raw)
In-Reply-To: <CAOQ4uxj4DiU=vFqHCuaHQ=4XVkTeJrXci0Y6YUX=22dE+iygqA@mail.gmail.com>
On Wed, Jan 23, 2019 at 10:48:58AM +0200, Amir Goldstein wrote:
> Hi,
>
> In his session about "reflink" in LSF/MM 2016 [1], Darrick Wong brought
> up the subject of sharing pages between cloned files and the general vibe
> in room was that it could be done.
>
> In his talk about XFS subvolumes and snapshots [2], Dave Chinner said
> that Matthew Willcox was "working on that problem".
My solution is to move the DAX hacks into the page cache proper. For a
reflinked file, the filesystem would create a canonical address_space
to own the pages, and this is what ->mapping and ->index would refer to.
Instances of that reflinked file would each have their own address_space,
just as they have their own inode. The i_pages array would contain only
PFN entries (until the COWs start).
I'm currently at LCA; please excuse me for not participating more fully
right now.
prev parent reply other threads:[~2019-01-23 19:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-23 8:48 [LSF/MM TOPIC] Sharing file backed pages Amir Goldstein
2019-01-23 14:54 ` Jan Kara
2019-01-23 15:12 ` Jerome Glisse
2019-01-23 15:26 ` Jerome Glisse
2019-01-23 17:57 ` Amir Goldstein
2019-01-24 10:39 ` Kirill A. Shutemov
2019-01-25 8:39 ` Amir Goldstein
2019-01-23 17:06 ` James Bottomley
2019-01-23 19:10 ` Matthew Wilcox [this message]
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