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From: "J. Bruce Fields" <bfields@fieldses.org>
To: Jeff Layton <jlayton@kernel.org>
Cc: "J. Bruce Fields" <bfields@redhat.com>,
	Daire Byrne <daire@dneg.com>,
	Trond Myklebust <trondmy@hammerspace.com>,
	linux-cachefs <linux-cachefs@redhat.com>,
	linux-nfs <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 2/4] nfsd: pre/post attr is using wrong change attribute
Date: Fri, 20 Nov 2020 17:38:31 -0500	[thread overview]
Message-ID: <20201120223831.GB7705@fieldses.org> (raw)
In-Reply-To: <725499c144317aac1a03f0334a22005588dbdefc.camel@kernel.org>

On Tue, Nov 17, 2020 at 10:34:57AM -0500, Jeff Layton wrote:
> On Tue, 2020-11-17 at 10:26 -0500, J. Bruce Fields wrote:
> > On Tue, Nov 17, 2020 at 07:34:49AM -0500, Jeff Layton wrote:
> > > I don't think I described what I was thinking well. Let me try again...
> > > 
> > > There should be no need to change the code in iversion.h -- I think we
> > > can do this in a way that's confined to just nfsd/export code.
> > > 
> > > What I would suggest is to have nfsd4_change_attribute call the
> > > fetch_iversion op if it exists, instead of checking IS_I_VERSION and
> > > doing the stuff in that block. If fetch_iversion is NULL, then just use
> > > the ctime.
> > > 
> > > Then, you just need to make sure that the filesystems' export_ops have
> > > an appropriate fetch_iversion vector. xfs, ext4 and btrfs can just call
> > > inode_query_iversion, and NFS and Ceph can call inode_peek_iversion_raw.
> > > The rest of the filesystems can leave fetch_iversion as NULL (since we
> > > don't want to use it on them).
> > 
> > Thanks for your patience, that makes sense, I'll try it.
> > 
> 
> There is one gotcha in here though... ext4 needs to also handle the case
> where SB_I_VERSION is not set. The simple fix might be to just have
> different export ops for ext4 based on whether it was mounted with -o
> iversion or not, but maybe there is some better way to do it?

I was thinking ext4's export op could check for I_VERSION on its own and
vary behavior based on that.

I'll follow up with new patches in a moment.

I think the first one's all that's needed to fix the problem Daire
identified.  I'm a little less sure of the rest.

Lightly tested, just by running them through my usual regression tests
(which don't re-export) and then running connectathon on a 4.2 re-export
of a 4.2 mount.

The latter triggered a crash preceded by a KASAN use-after free warning.
Looks like it might be a problem with blocking lock notifications,
probably not related to these patches.

--b.

  reply	other threads:[~2020-11-20 22:38 UTC|newest]

Thread overview: 129+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-07 17:31 Adventures in NFS re-exporting Daire Byrne
2020-09-08  9:40 ` Mkrtchyan, Tigran
2020-09-08 11:06   ` Daire Byrne
2020-09-15 17:21 ` J. Bruce Fields
2020-09-15 19:59   ` Trond Myklebust
2020-09-16 16:01     ` Daire Byrne
2020-10-19 16:19       ` Daire Byrne
2020-10-19 17:53         ` [PATCH 0/2] Add NFSv3 emulation of the lookupp operation trondmy
2020-10-19 17:53           ` [PATCH 1/2] NFSv3: Refactor nfs3_proc_lookup() to split out the dentry trondmy
2020-10-19 17:53             ` [PATCH 2/2] NFSv3: Add emulation of the lookupp() operation trondmy
2020-10-19 20:05         ` [PATCH v2 0/2] Add NFSv3 emulation of the lookupp operation trondmy
2020-10-19 20:05           ` [PATCH v2 1/2] NFSv3: Refactor nfs3_proc_lookup() to split out the dentry trondmy
2020-10-19 20:05             ` [PATCH v2 2/2] NFSv3: Add emulation of the lookupp() operation trondmy
2020-10-20 18:37         ` [PATCH v3 0/3] Add NFSv3 emulation of the lookupp operation trondmy
2020-10-20 18:37           ` [PATCH v3 1/3] NFSv3: Refactor nfs3_proc_lookup() to split out the dentry trondmy
2020-10-20 18:37             ` [PATCH v3 2/3] NFSv3: Add emulation of the lookupp() operation trondmy
2020-10-20 18:37               ` [PATCH v3 3/3] NFSv4: Observe the NFS_MOUNT_SOFTREVAL flag in _nfs4_proc_lookupp trondmy
2020-10-21  9:33         ` Adventures in NFS re-exporting Daire Byrne
2020-11-09 16:02           ` bfields
2020-11-12 13:01             ` Daire Byrne
2020-11-12 13:57               ` bfields
2020-11-12 18:33                 ` Daire Byrne
2020-11-12 20:55                   ` bfields
2020-11-12 23:05                     ` Daire Byrne
2020-11-13 14:50                       ` bfields
2020-11-13 22:26                         ` bfields
2020-11-14 12:57                           ` Daire Byrne
2020-11-16 15:18                             ` bfields
2020-11-16 15:53                             ` bfields
2020-11-16 19:21                               ` Daire Byrne
2020-11-16 15:29                           ` Jeff Layton
2020-11-16 15:56                             ` bfields
2020-11-16 16:03                               ` Jeff Layton
2020-11-16 16:14                                 ` bfields
2020-11-16 16:38                                   ` Jeff Layton
2020-11-16 19:03                                     ` bfields
2020-11-16 20:03                                       ` Jeff Layton
2020-11-17  3:16                                         ` bfields
2020-11-17  3:18                                           ` [PATCH 1/4] nfsd: move fill_{pre,post}_wcc to nfsfh.c J. Bruce Fields
2020-11-17  3:18                                             ` [PATCH 2/4] nfsd: pre/post attr is using wrong change attribute J. Bruce Fields
2020-11-17 12:34                                               ` Jeff Layton
2020-11-17 15:26                                                 ` J. Bruce Fields
2020-11-17 15:34                                                   ` Jeff Layton
2020-11-20 22:38                                                     ` J. Bruce Fields [this message]
2020-11-20 22:39                                                       ` [PATCH 1/8] nfsd: only call inode_query_iversion in the I_VERSION case J. Bruce Fields
2020-11-20 22:39                                                         ` [PATCH 2/8] nfsd: simplify nfsd4_change_info J. Bruce Fields
2020-11-20 22:39                                                         ` [PATCH 3/8] nfsd: minor nfsd4_change_attribute cleanup J. Bruce Fields
2020-11-21  0:34                                                           ` Jeff Layton
2020-11-20 22:39                                                         ` [PATCH 4/8] nfsd4: don't query change attribute in v2/v3 case J. Bruce Fields
2020-11-20 22:39                                                         ` [PATCH 5/8] nfs: use change attribute for NFS re-exports J. Bruce Fields
2020-11-20 22:39                                                         ` [PATCH 6/8] nfsd: move change attribute generation to filesystem J. Bruce Fields
2020-11-21  0:58                                                           ` Jeff Layton
2020-11-21  1:01                                                             ` J. Bruce Fields
2020-11-21 13:00                                                           ` Jeff Layton
2020-11-20 22:39                                                         ` [PATCH 7/8] nfsd: skip some unnecessary stats in the v4 case J. Bruce Fields
2020-11-20 22:39                                                         ` [PATCH 8/8] Revert "nfsd4: support change_attr_type attribute" J. Bruce Fields
2020-11-20 22:44                                                       ` [PATCH 2/4] nfsd: pre/post attr is using wrong change attribute J. Bruce Fields
2020-11-21  1:03                                                         ` Jeff Layton
2020-11-21 21:44                                                           ` Daire Byrne
2020-11-22  0:02                                                             ` bfields
2020-11-22  1:55                                                               ` Daire Byrne
2020-11-22  3:03                                                                 ` bfields
2020-11-23 20:07                                                                   ` Daire Byrne
2020-11-17 15:25                                               ` J. Bruce Fields
2020-11-17  3:18                                             ` [PATCH 3/4] nfs: don't mangle i_version on NFS J. Bruce Fields
2020-11-17 12:27                                               ` Jeff Layton
2020-11-17 14:14                                                 ` J. Bruce Fields
2020-11-17  3:18                                             ` [PATCH 4/4] nfs: support i_version in the NFSv4 case J. Bruce Fields
2020-11-17 12:34                                               ` Jeff Layton
2020-11-24 20:35               ` Adventures in NFS re-exporting Daire Byrne
2020-11-24 21:15                 ` bfields
2020-11-24 22:15                   ` Frank Filz
2020-11-25 14:47                     ` 'bfields'
2020-11-25 16:25                       ` Frank Filz
2020-11-25 19:03                         ` 'bfields'
2020-11-26  0:04                           ` Frank Filz
2020-11-25 17:14                   ` Daire Byrne
2020-11-25 19:31                     ` bfields
2020-12-03 12:20                     ` Daire Byrne
2020-12-03 18:51                       ` bfields
2020-12-03 20:27                         ` Trond Myklebust
2020-12-03 21:13                           ` bfields
2020-12-03 21:32                             ` Frank Filz
2020-12-03 21:34                             ` Trond Myklebust
2020-12-03 21:45                               ` Frank Filz
2020-12-03 21:57                                 ` Trond Myklebust
2020-12-03 22:04                                   ` bfields
2020-12-03 22:14                                     ` Trond Myklebust
2020-12-03 22:39                                       ` Frank Filz
2020-12-03 22:50                                         ` Trond Myklebust
2020-12-03 23:34                                           ` Frank Filz
2020-12-03 22:44                                       ` bfields
2020-12-03 21:54                               ` bfields
2020-12-03 22:45                               ` bfields
2020-12-03 22:53                                 ` Trond Myklebust
2020-12-03 23:16                                   ` bfields
2020-12-03 23:28                                     ` Frank Filz
2020-12-04  1:02                                     ` Trond Myklebust
2020-12-04  1:41                                       ` bfields
2020-12-04  2:27                                         ` Trond Myklebust
2020-09-17 16:01   ` Daire Byrne
2020-09-17 19:09     ` bfields
2020-09-17 20:23       ` Frank van der Linden
2020-09-17 21:57         ` bfields
2020-09-19 11:08           ` Daire Byrne
2020-09-22 16:43         ` Chuck Lever
2020-09-23 20:25           ` Daire Byrne
2020-09-23 21:01             ` Frank van der Linden
2020-09-26  9:00               ` Daire Byrne
2020-09-28 15:49                 ` Frank van der Linden
2020-09-28 16:08                   ` Chuck Lever
2020-09-28 17:42                     ` Frank van der Linden
2020-09-22 12:31 ` Daire Byrne
2020-09-22 13:52   ` Trond Myklebust
2020-09-23 12:40     ` J. Bruce Fields
2020-09-23 13:09       ` Trond Myklebust
2020-09-23 17:07         ` bfields
2020-09-30 19:30   ` [Linux-cachefs] " Jeff Layton
2020-10-01  0:09     ` Daire Byrne
2020-10-01 10:36       ` Jeff Layton
2020-10-01 12:38         ` Trond Myklebust
2020-10-01 16:39           ` Jeff Layton
2020-10-05 12:54         ` Daire Byrne
2020-10-13  9:59           ` Daire Byrne
2020-10-01 18:41     ` J. Bruce Fields
2020-10-01 19:24       ` Trond Myklebust
2020-10-01 19:26         ` bfields
2020-10-01 19:29           ` Trond Myklebust
2020-10-01 19:51             ` bfields

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