From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
To: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
Cc: Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
"Darrick J. Wong"
<darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>,
Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Andreas Dilger
<adilger.kernel-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>,
Alexander Viro
<viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"Kirill A. Shutemov"
<kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org>,
linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
Matthew Wilcox <mawilcox-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>,
linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org
Subject: Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite()
Date: Tue, 25 Jul 2017 14:15:22 +0200 [thread overview]
Message-ID: <20170725121522.GA13457@lst.de> (raw)
In-Reply-To: <20170725093508.GA19943-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
On Tue, Jul 25, 2017 at 11:35:08AM +0200, Jan Kara wrote:
> On Tue 25-07-17 10:01:58, Christoph Hellwig wrote:
> > On Tue, Jul 25, 2017 at 01:14:00AM +0300, Kirill A. Shutemov wrote:
> > > I guess it's up to filesystem if it wants to reuse the same spot to write
> > > data or not. I think your assumptions works for ext4 and xfs. I wouldn't
> > > be that sure for btrfs or other filesystems with CoW support.
> >
> > Or XFS with reflinks for that matter. Which currently can't be
> > combined with DAX, but I had a somewhat working version a few month
> > ago.
>
> But in cases like COW when the block mapping changes, the process
> must run unmap_mapping_range() before installing the new PTE so that all
> processes mapping this file offset actually refault and see the new
> mapping. So this would go through pte_none() case. Am I missing something?
Yes, for DAX COW mappings we'd probably need something like this, unlike
the pagecache COW handling for which only the underlying block change,
but not the page.
next prev parent reply other threads:[~2017-07-25 12:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-24 17:06 [PATCH v5 0/5] DAX common 4k zero page Ross Zwisler
2017-07-24 17:06 ` [PATCH v5 4/5] dax: remove DAX code from page_cache_tree_insert() Ross Zwisler
[not found] ` <20170724170616.25810-1-ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-07-24 17:06 ` [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() Ross Zwisler
2017-07-24 22:14 ` Kirill A. Shutemov
2017-07-25 8:01 ` Christoph Hellwig
2017-07-25 9:35 ` Jan Kara
[not found] ` <20170725093508.GA19943-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-07-25 12:15 ` Christoph Hellwig [this message]
[not found] ` <20170725121522.GA13457-jcswGhMUV9g@public.gmane.org>
2017-07-25 12:50 ` Jan Kara
2017-07-25 14:31 ` Kirill A. Shutemov
2017-07-24 17:06 ` [PATCH v5 2/5] dax: relocate some dax functions Ross Zwisler
2017-07-24 17:06 ` [PATCH v5 3/5] dax: use common 4k zero page for dax mmap reads Ross Zwisler
2017-07-24 17:06 ` [PATCH v5 5/5] dax: move all DAX radix tree defs to fs/dax.c Ross Zwisler
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