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From: Ira Weiny <ira.weiny@intel.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Dan Williams <dan.j.williams@intel.com>,
	Matthew Wilcox <willy@infradead.org>,
	Theodore Ts'o <tytso@mit.edu>, Michal Hocko <mhocko@suse.com>,
	linux-xfs@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-ext4@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-)
Date: Wed, 21 Aug 2019 12:09:04 -0700	[thread overview]
Message-ID: <20190821190904.GD5965@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <29c89d84-d847-0221-70a7-9e5a3d472cda@nvidia.com>

On Wed, Aug 21, 2019 at 11:43:30AM -0700, John Hubbard wrote:
> On 8/19/19 8:36 PM, Dave Chinner wrote:
> > On Mon, Aug 19, 2019 at 08:09:33PM -0700, John Hubbard wrote:
> > > On 8/19/19 6:20 PM, Dave Chinner wrote:
> > > > On Mon, Aug 19, 2019 at 05:05:53PM -0700, John Hubbard wrote:
> > > > > On 8/19/19 2:24 AM, Dave Chinner wrote:
> > > > > > On Mon, Aug 19, 2019 at 08:34:12AM +0200, Jan Kara wrote:
> > > > > > > On Sat 17-08-19 12:26:03, Dave Chinner wrote:
> > > > > > > > On Fri, Aug 16, 2019 at 12:05:28PM -0700, Ira Weiny wrote:
> > > > > > > > > On Thu, Aug 15, 2019 at 03:05:58PM +0200, Jan Kara wrote:
> > > > > > > > > > On Wed 14-08-19 11:08:49, Ira Weiny wrote:
> > > > > > > > > > > On Wed, Aug 14, 2019 at 12:17:14PM +0200, Jan Kara wrote:
> > > > > ...
> > AFAIA, there is no struct file here - the memory that has been pinned
> > is just something mapped into the application's address space.
> > 
> > It seems to me that the socket here is equivalent of the RDMA handle
> > that that owns the hardware that pins the pages. Again, that RDMA
> > handle is not aware of waht the mapping represents, hence need to
> > hold a layout lease if it's a file mapping.
> > 
> > SO from the filesystem persepctive, there's no difference between
> > XDP or RDMA - if it's a FSDAX mapping then it is DMAing directly
> > into the filesystem's backing store and that will require use of
> > layout leases to perform safely.
> > 
> 
> OK, got it! Makes perfect sense.

Just to chime in here... Yea from the FS perspective it is the same.

But on the driver side it is more complicated because of how the references to
the pins can be shared among other processes.

See the other branch of this thread

https://lkml.org/lkml/2019/8/21/828

Ira

> 
> thanks,
> -- 
> John Hubbard
> NVIDIA

      reply	other threads:[~2019-08-21 19:09 UTC|newest]

Thread overview: 110+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 22:58 [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 01/19] fs/locks: Export F_LAYOUT lease to user space ira.weiny
2019-08-09 23:52   ` Dave Chinner
2019-08-12 17:36     ` Ira Weiny
2019-08-14  8:05       ` Dave Chinner
2019-08-14 11:21         ` Jeff Layton
2019-08-14 11:38           ` Dave Chinner
2019-08-09 22:58 ` [RFC PATCH v2 02/19] fs/locks: Add Exclusive flag to user Layout lease ira.weiny
2019-08-14 14:15   ` Jeff Layton
2019-08-14 21:56     ` Dave Chinner
2019-08-26 10:41       ` Jeff Layton
2019-08-29 23:34         ` Ira Weiny
2019-09-04 12:52           ` Jeff Layton
2019-09-04 23:12   ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 03/19] mm/gup: Pass flags down to __gup_device_huge* calls ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 04/19] mm/gup: Ensure F_LAYOUT lease is held prior to GUP'ing pages ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 05/19] fs/ext4: Teach ext4 to break layout leases ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 06/19] fs/ext4: Teach dax_layout_busy_page() to operate on a sub-range ira.weiny
2019-08-23 15:18   ` Vivek Goyal
2019-08-29 18:52     ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 07/19] fs/xfs: Teach xfs to use new dax_layout_busy_page() ira.weiny
2019-08-09 23:30   ` Dave Chinner
2019-08-12 18:05     ` Ira Weiny
2019-08-14  8:04       ` Dave Chinner
2019-08-09 22:58 ` [RFC PATCH v2 08/19] fs/xfs: Fail truncate if page lease can't be broken ira.weiny
2019-08-09 23:22   ` Dave Chinner
2019-08-12 18:08     ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 09/19] mm/gup: Introduce vaddr_pin structure ira.weiny
2019-08-10  0:06   ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 10/19] mm/gup: Pass a NULL vaddr_pin through GUP fast ira.weiny
2019-08-10  0:06   ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 11/19] mm/gup: Pass follow_page_context further down the call stack ira.weiny
2019-08-10  0:18   ` John Hubbard
2019-08-12 19:01     ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 12/19] mm/gup: Prep put_user_pages() to take an vaddr_pin struct ira.weiny
2019-08-10  0:30   ` John Hubbard
2019-08-12 20:46     ` Ira Weiny
2019-08-09 22:58 ` [RFC PATCH v2 13/19] {mm,file}: Add file_pins objects ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 14/19] fs/locks: Associate file pins while performing GUP ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 15/19] mm/gup: Introduce vaddr_pin_pages() ira.weiny
2019-08-10  0:09   ` John Hubbard
2019-08-12 21:00     ` Ira Weiny
2019-08-12 21:20       ` John Hubbard
2019-08-11 23:07   ` John Hubbard
2019-08-12 21:01     ` Ira Weiny
2019-08-12 12:28   ` Jason Gunthorpe
2019-08-12 21:48     ` Ira Weiny
2019-08-13 11:47       ` Jason Gunthorpe
2019-08-13 17:46         ` Ira Weiny
2019-08-13 17:56           ` John Hubbard
2019-08-09 22:58 ` [RFC PATCH v2 16/19] RDMA/uverbs: Add back pointer to system file object ira.weiny
2019-08-12 13:00   ` Jason Gunthorpe
2019-08-12 17:28     ` Ira Weiny
2019-08-12 17:56       ` Jason Gunthorpe
2019-08-12 21:15         ` Ira Weiny
2019-08-13 11:48           ` Jason Gunthorpe
2019-08-13 17:41             ` Ira Weiny
2019-08-13 18:00               ` Jason Gunthorpe
2019-08-13 20:38                 ` Ira Weiny
2019-08-14 12:23                   ` Jason Gunthorpe
2019-08-14 17:50                     ` Ira Weiny
2019-08-14 18:15                       ` Jason Gunthorpe
2019-09-04 22:25                     ` Ira Weiny
2019-09-11  8:19                       ` Jason Gunthorpe
2019-08-09 22:58 ` [RFC PATCH v2 17/19] RDMA/umem: Convert to vaddr_[pin|unpin]* operations ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 18/19] {mm,procfs}: Add display file_pins proc ira.weiny
2019-08-09 22:58 ` [RFC PATCH v2 19/19] mm/gup: Remove FOLL_LONGTERM DAX exclusion ira.weiny
2019-08-14 10:17 ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Jan Kara
2019-08-14 18:08   ` Ira Weiny
2019-08-15 13:05     ` Jan Kara
2019-08-16 19:05       ` Ira Weiny
2019-08-16 23:20         ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ; -) Ira Weiny
2019-08-19  6:36           ` Jan Kara
2019-08-17  2:26         ` [RFC PATCH v2 00/19] RDMA/FS DAX truncate proposal V1,000,002 ;-) Dave Chinner
2019-08-19  6:34           ` Jan Kara
2019-08-19  9:24             ` Dave Chinner
2019-08-19 12:38               ` Jason Gunthorpe
2019-08-19 21:53                 ` Ira Weiny
2019-08-20  1:12                 ` Dave Chinner
2019-08-20 11:55                   ` Jason Gunthorpe
2019-08-21 18:02                     ` Ira Weiny
2019-08-21 18:13                       ` Jason Gunthorpe
2019-08-21 18:22                         ` John Hubbard
2019-08-21 18:57                         ` Ira Weiny
2019-08-21 19:06                           ` Ira Weiny
2019-08-21 19:48                           ` Jason Gunthorpe
2019-08-21 20:44                             ` Ira Weiny
2019-08-21 23:49                               ` Jason Gunthorpe
2019-08-23  3:23                               ` Dave Chinner
2019-08-23 12:04                                 ` Jason Gunthorpe
2019-08-24  0:11                                   ` Dave Chinner
2019-08-24  5:08                                     ` Ira Weiny
2019-08-26  5:55                                       ` Dave Chinner
2019-08-29  2:02                                         ` Ira Weiny
2019-08-29  3:27                                           ` John Hubbard
2019-08-29 16:16                                             ` Ira Weiny
2019-09-02 22:26                                           ` Dave Chinner
2019-09-04 16:54                                             ` Ira Weiny
2019-08-25 19:39                                     ` Jason Gunthorpe
2019-08-24  4:49                                 ` Ira Weiny
2019-08-25 19:40                                   ` Jason Gunthorpe
2019-08-23  0:59                       ` Dave Chinner
2019-08-23 17:15                         ` Ira Weiny
2019-08-24  0:18                           ` Dave Chinner
2019-08-20  0:05               ` John Hubbard
2019-08-20  1:20                 ` Dave Chinner
2019-08-20  3:09                   ` John Hubbard
2019-08-20  3:36                     ` Dave Chinner
2019-08-21 18:43                       ` John Hubbard
2019-08-21 19:09                         ` Ira Weiny [this message]

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