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From: Dan Williams <dan.j.williams@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: "Jason Gunthorpe" <jgg@ziepe.ca>,
	"Ira Weiny" <ira.weiny@intel.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	"Jeff Layton" <jlayton@kernel.org>,
	"Dave Chinner" <david@fromorbit.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	"Linux MM" <linux-mm@kvack.org>
Subject: Re: [PATCH RFC 00/10] RDMA/FS DAX truncate proposal
Date: Wed, 12 Jun 2019 11:41:53 -0700	[thread overview]
Message-ID: <CAPcyv4ikn219XUgHwsPdYp06vBNAJB9Rk-hjZA-fYT4GB3gi+w@mail.gmail.com> (raw)
In-Reply-To: <20190612120907.GC14578@quack2.suse.cz>

On Wed, Jun 12, 2019 at 5:09 AM Jan Kara <jack@suse.cz> wrote:
>
> On Wed 12-06-19 08:47:21, Jason Gunthorpe wrote:
> > On Wed, Jun 12, 2019 at 12:29:17PM +0200, Jan Kara wrote:
> >
> > > > > The main objection to the current ODP & DAX solution is that very
> > > > > little HW can actually implement it, having the alternative still
> > > > > require HW support doesn't seem like progress.
> > > > >
> > > > > I think we will eventually start seein some HW be able to do this
> > > > > invalidation, but it won't be universal, and I'd rather leave it
> > > > > optional, for recovery from truely catastrophic errors (ie my DAX is
> > > > > on fire, I need to unplug it).
> > > >
> > > > Agreed.  I think software wise there is not much some of the devices can do
> > > > with such an "invalidate".
> > >
> > > So out of curiosity: What does RDMA driver do when userspace just closes
> > > the file pointing to RDMA object? It has to handle that somehow by aborting
> > > everything that's going on... And I wanted similar behavior here.
> >
> > It aborts *everything* connected to that file descriptor. Destroying
> > everything avoids creating inconsistencies that destroying a subset
> > would create.
> >
> > What has been talked about for lease break is not destroying anything
> > but very selectively saying that one memory region linked to the GUP
> > is no longer functional.
>
> OK, so what I had in mind was that if RDMA app doesn't play by the rules
> and closes the file with existing pins (and thus layout lease) we would
> force it to abort everything. Yes, it is disruptive but then the app didn't
> obey the rule that it has to maintain file lease while holding pins. Thus
> such situation should never happen unless the app is malicious / buggy.

When you say 'close' do you mean the final release of the fd? The vma
keeps a reference to a 'struct file' live even after the fd is closed.


  reply	other threads:[~2019-06-12 18:42 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 [this message]
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
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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