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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Ira Weiny <ira.weiny@intel.com>
Cc: "Matthew Wilcox" <willy@infradead.org>,
	"Dave Chinner" <david@fromorbit.com>, "Jan Kara" <jack@suse.cz>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	"Jeff Layton" <jlayton@kernel.org>,
	linux-xfs@vger.kernel.org,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-ext4@vger.kernel.org,
	linux-mm@kvack.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH RFC 00/10] RDMA/FS DAX truncate proposal
Date: Thu, 13 Jun 2019 20:45:30 -0300	[thread overview]
Message-ID: <20190613234530.GK22901@ziepe.ca> (raw)
In-Reply-To: <20190613211321.GC32404@iweiny-DESK2.sc.intel.com>

On Thu, Jun 13, 2019 at 02:13:21PM -0700, Ira Weiny wrote:
> On Thu, Jun 13, 2019 at 08:27:55AM -0700, Matthew Wilcox wrote:
> > On Thu, Jun 13, 2019 at 10:25:55AM +1000, Dave Chinner wrote:
> > > e.g. Process A has an exclusive layout lease on file F. It does an
> > > IO to file F. The filesystem IO path checks that Process A owns the
> > > lease on the file and so skips straight through layout breaking
> > > because it owns the lease and is allowed to modify the layout. It
> > > then takes the inode metadata locks to allocate new space and write
> > > new data.
> > > 
> > > Process B now tries to write to file F. The FS checks whether
> > > Process B owns a layout lease on file F. It doesn't, so then it
> > > tries to break the layout lease so the IO can proceed. The layout
> > > breaking code sees that process A has an exclusive layout lease
> > > granted, and so returns -ETXTBSY to process B - it is not allowed to
> > > break the lease and so the IO fails with -ETXTBSY.
> > 
> > This description doesn't match the behaviour that RDMA wants either.
> > Even if Process A has a lease on the file, an IO from Process A which
> > results in blocks being freed from the file is going to result in the
> > RDMA device being able to write to blocks which are now freed (and
> > potentially reallocated to another file).
> 
> I don't understand why this would not work for RDMA?  As long as the layout
> does not change the page pins can remain in place.

Because process A had a layout lease (and presumably a MR) and the
layout was still modified in way that invalidates the RDMA MR.

Jason

  reply	other threads:[~2019-06-13 23:45 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-06  1:45 [PATCH RFC 00/10] RDMA/FS DAX truncate proposal ira.weiny
2019-06-06  1:45 ` [PATCH RFC 01/10] fs/locks: Add trace_leases_conflict ira.weiny
2019-06-09 12:52   ` Jeff Layton
2019-06-06  1:45 ` [PATCH RFC 02/10] fs/locks: Export F_LAYOUT lease to user space ira.weiny
2019-06-09 13:00   ` Jeff Layton
2019-06-11 21:38     ` Ira Weiny
2019-06-12  9:46       ` Jan Kara
2019-06-06  1:45 ` [PATCH RFC 03/10] mm/gup: Pass flags down to __gup_device_huge* calls ira.weiny
2019-06-06  6:18   ` Christoph Hellwig
2019-06-06 16:10     ` Ira Weiny
2019-06-06  1:45 ` [PATCH RFC 04/10] mm/gup: Ensure F_LAYOUT lease is held prior to GUP'ing pages ira.weiny
2019-06-06  1:45 ` [PATCH RFC 05/10] fs/ext4: Teach ext4 to break layout leases ira.weiny
2019-06-06  1:45 ` [PATCH RFC 06/10] fs/ext4: Teach dax_layout_busy_page() to operate on a sub-range ira.weiny
2019-06-06  1:45 ` [PATCH RFC 07/10] fs/ext4: Fail truncate if pages are GUP pinned ira.weiny
2019-06-06 10:58   ` Jan Kara
2019-06-06 16:17     ` Ira Weiny
2019-06-06  1:45 ` [PATCH RFC 08/10] fs/xfs: Teach xfs to use new dax_layout_busy_page() ira.weiny
2019-06-06  1:45 ` [PATCH RFC 09/10] fs/xfs: Fail truncate if pages are GUP pinned ira.weiny
2019-06-06  1:45 ` [PATCH RFC 10/10] mm/gup: Remove FOLL_LONGTERM DAX exclusion ira.weiny
2019-06-06  5:52 ` [PATCH RFC 00/10] RDMA/FS DAX truncate proposal John Hubbard
2019-06-06 17:11   ` Ira Weiny
2019-06-06 19:46     ` Jason Gunthorpe
2019-06-06 10:42 ` Jan Kara
2019-06-06 15:35   ` Dan Williams
2019-06-06 19:51   ` Jason Gunthorpe
2019-06-06 22:22     ` Ira Weiny
2019-06-07 10:36       ` Jan Kara
2019-06-07 12:17         ` Jason Gunthorpe
2019-06-07 14:52           ` Ira Weiny
2019-06-07 15:10             ` Jason Gunthorpe
2019-06-12 10:29             ` Jan Kara
2019-06-12 11:47               ` Jason Gunthorpe
2019-06-12 12:09                 ` Jan Kara
2019-06-12 18:41                   ` Dan Williams
2019-06-13  7:17                     ` Jan Kara
2019-06-12 19:14                   ` Jason Gunthorpe
2019-06-12 22:13                     ` Ira Weiny
2019-06-12 22:54                       ` Dan Williams
2019-06-12 23:33                         ` Ira Weiny
2019-06-13  1:14                           ` Dan Williams
2019-06-13 15:13                             ` Jason Gunthorpe
2019-06-13 16:25                               ` Dan Williams
2019-06-13 17:18                                 ` Jason Gunthorpe
2019-06-13 16:53                           ` Dan Williams
2019-06-13 15:12                         ` Jason Gunthorpe
2019-06-13  7:53                       ` Jan Kara
2019-06-12 18:49               ` Dan Williams
2019-06-13  7:43                 ` Jan Kara
2019-06-06 22:03   ` Ira Weiny
2019-06-06 22:26     ` Ira Weiny
2019-06-06 22:28     ` Dave Chinner
2019-06-07 11:04     ` Jan Kara
2019-06-07 18:25       ` Ira Weiny
2019-06-07 18:50         ` Jason Gunthorpe
2019-06-08  0:10         ` Dave Chinner
2019-06-09  1:29           ` Ira Weiny
2019-06-12 12:37           ` Matthew Wilcox
2019-06-12 23:30             ` Ira Weiny
2019-06-13  0:55               ` Dave Chinner
2019-06-13 20:34                 ` Ira Weiny
2019-06-14  3:42                   ` Dave Chinner
2019-06-13  0:25             ` Dave Chinner
2019-06-13  3:23               ` Matthew Wilcox
2019-06-13  4:36                 ` Dave Chinner
2019-06-13 10:47                   ` Matthew Wilcox
2019-06-13 15:29                 ` Jason Gunthorpe
2019-06-13 15:27               ` Matthew Wilcox
2019-06-13 21:13                 ` Ira Weiny
2019-06-13 23:45                   ` Jason Gunthorpe [this message]
2019-06-14  0:00                     ` Ira Weiny
2019-06-14  2:09                     ` Dave Chinner
2019-06-14  2:31                       ` Matthew Wilcox
2019-06-14  3:07                         ` Dave Chinner
2019-06-20 14:52                 ` Jan Kara
2019-06-13 20:34               ` Ira Weiny
2019-06-14  2:58                 ` Dave Chinner

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