From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Linux API <linux-api@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Dave Chinner <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-xfs@vger.kernel.org, Linux MM <linux-mm@kvack.org>,
Jeff Moyer <jmoyer@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andy Lutomirski <luto@kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
xen-devel@lists.xen.org
Subject: Re: [PATCH v6 4/5] fs, xfs: introduce MAP_DIRECT for creating block-map-atomic file ranges
Date: Thu, 24 Aug 2017 09:31:17 -0700 [thread overview]
Message-ID: <CAPcyv4jjNi_+c5DW9nsBLEnYMBtsR_v67+bF6bC4Cb9mY7T+Ww@mail.gmail.com> (raw)
In-Reply-To: <20170824161152.GB27591@lst.de>
[ adding Xen ]
On Thu, Aug 24, 2017 at 9:11 AM, Christoph Hellwig <hch@lst.de> wrote:
> I still can't make any sense of this description. What is an external
> agent? Userspace obviously can't ever see a change in the extent
> map, so it can't be meant.
External agent is a DMA device, or a hypervisor like Xen. In the DMA
case perhaps we can use the fcntl lease mechanism, I'll investigate.
In the Xen case it actually would need to use fiemap() to discover the
physical addresses that back the file to setup their M2P tables.
Here's the discussion where we discovered that physical address
dependency:
https://lists.xen.org/archives/html/xen-devel/2017-04/msg00419.html
> It would help a lot if you could come up with a concrete user for this,
> including example code.
Will do.
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next prev parent reply other threads:[~2017-08-24 16:31 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 23:48 [PATCH v6 0/5] MAP_DIRECT and block-map-atomic files Dan Williams
2017-08-23 23:48 ` [PATCH v6 1/5] vfs: add flags parameter to ->mmap() in 'struct file_operations' Dan Williams
2017-08-24 16:58 ` Christoph Hellwig
2017-08-24 17:42 ` Dan Williams
2017-08-23 23:48 ` [PATCH v6 2/5] fs, xfs: introduce S_IOMAP_SEALED Dan Williams
2017-08-24 16:13 ` Christoph Hellwig
2017-08-25 6:00 ` Dan Williams
2017-08-25 19:44 ` Dan Williams
2017-08-23 23:48 ` [PATCH v6 3/5] mm: introduce mmap3 for safely defining new mmap flags Dan Williams
2017-08-24 13:04 ` Jan Kara
2017-08-24 16:55 ` Christoph Hellwig
2017-08-24 17:36 ` Dan Williams
2017-08-25 13:00 ` Christoph Hellwig
2017-08-25 15:58 ` Kirill A. Shutemov
2017-08-25 16:02 ` Christoph Hellwig
2017-08-25 16:16 ` Kirill A. Shutemov
2017-08-25 16:19 ` Helge Deller
2017-08-25 16:56 ` Kirill A. Shutemov
2017-08-25 20:24 ` Dan Williams
2017-08-26 7:40 ` Helge Deller
2017-08-26 15:15 ` Dan Williams
2017-08-26 19:50 ` Helge Deller
2017-08-26 22:46 ` Dan Williams
2017-08-26 23:56 ` Kirill A. Shutemov
2017-08-23 23:48 ` [PATCH v6 4/5] fs, xfs: introduce MAP_DIRECT for creating block-map-atomic file ranges Dan Williams
2017-08-24 16:11 ` Christoph Hellwig
2017-08-24 16:31 ` Dan Williams [this message]
2017-08-24 16:39 ` Christoph Hellwig
2017-08-24 20:26 ` Dan Williams
2017-08-23 23:49 ` [PATCH v6 5/5] fs, fcntl: add F_MAP_DIRECT Dan Williams
2017-08-24 16:08 ` [PATCH v6 0/5] MAP_DIRECT and block-map-atomic files Christoph Hellwig
2017-08-24 16:25 ` Dan Williams
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