From: bfields@fieldses.org (J. Bruce Fields)
To: Jeff Layton <jlayton@kernel.org>
Cc: Florian Weimer <fweimer@redhat.com>,
Theodore Ts'o <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
NeilBrown <neilb@suse.de>,
adilger.kernel@dilger.ca, djwong@kernel.org, david@fromorbit.com,
trondmy@hammerspace.com, viro@zeniv.linux.org.uk,
zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com,
lczerner@redhat.com, brauner@kernel.org,
linux-man@vger.kernel.org, linux-api@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org,
linux-xfs@vger.kernel.org
Subject: Re: [man-pages RFC PATCH v4] statx, inode: document the new STATX_INO_VERSION field
Date: Mon, 12 Sep 2022 10:47:30 -0400 [thread overview]
Message-ID: <20220912144730.GD9304@fieldses.org> (raw)
In-Reply-To: <1abae98579030d437224ae24f73fffaabb3f64c1.camel@kernel.org>
On Mon, Sep 12, 2022 at 10:02:27AM -0400, Jeff Layton wrote:
> On Mon, 2022-09-12 at 09:51 -0400, J. Bruce Fields wrote:
> > On Mon, Sep 12, 2022 at 08:55:04AM -0400, Jeff Layton wrote:
> > > Because of the "seen" flag, we have a 63 bit counter to play with. Could
> > > we use a similar scheme to the one we use to handle when "jiffies"
> > > wraps? Assume that we'd never compare two values that were more than
> > > 2^62 apart? We could add i_version_before/i_version_after macros to make
> > > it simple to handle this.
> >
> > As far as I recall the protocol just assumes it can never wrap. I guess
> > you could add a new change_attr_type that works the way you describe.
> > But without some new protocol clients aren't going to know what to do
> > with a change attribute that wraps.
> >
>
> Right, I think that's the case now, and with contemporary hardware that
> shouldn't ever happen, but in 10 years when we're looking at femtosecond
> latencies, could this be different? I don't know.
That doesn't sound likely. We probably need not just 2^63 writes to a
single file, but a dependent sequence of 2^63 interspersed writes and
change attribute reads.
Then there's the question of how many crashes and remounts are possible
for a single filesystem in the worst case.
>
> > I think this just needs to be designed so that wrapping is impossible in
> > any realistic scenario. I feel like that's doable?
> >
> > If we feel we have to catch that case, the only 100% correct behavior
> > would probably be to make the filesystem readonly.
>
> What would be the recourse at that point? Rebuild the fs from scratch, I
> guess?
I guess.
--b.
next prev parent reply other threads:[~2022-09-12 14:47 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-07 11:16 [man-pages RFC PATCH v4] statx, inode: document the new STATX_INO_VERSION field Jeff Layton
2022-09-07 11:37 ` NeilBrown
2022-09-07 12:20 ` J. Bruce Fields
2022-09-07 12:58 ` Jeff Layton
2022-09-07 12:47 ` Jeff Layton
2022-09-07 12:52 ` J. Bruce Fields
2022-09-07 13:12 ` Jeff Layton
2022-09-07 13:51 ` Jan Kara
2022-09-07 14:43 ` Jeff Layton
2022-09-08 0:44 ` NeilBrown
2022-09-08 8:33 ` Jan Kara
2022-09-08 15:21 ` Theodore Ts'o
2022-09-08 15:44 ` J. Bruce Fields
2022-09-08 15:44 ` Jeff Layton
2022-09-08 15:56 ` J. Bruce Fields
2022-09-08 16:15 ` Chuck Lever III
2022-09-08 17:40 ` Jeff Layton
2022-09-08 18:22 ` J. Bruce Fields
2022-09-08 19:07 ` Jeff Layton
2022-09-08 23:01 ` NeilBrown
2022-09-08 23:23 ` Jeff Layton
2022-09-08 23:45 ` NeilBrown
2022-09-09 15:45 ` J. Bruce Fields
2022-09-09 16:36 ` Jeff Layton
2022-09-10 14:56 ` J. Bruce Fields
2022-09-12 11:42 ` Jeff Layton
2022-09-12 12:13 ` Florian Weimer
2022-09-12 12:55 ` Jeff Layton
2022-09-12 13:20 ` Florian Weimer
2022-09-12 13:49 ` Jeff Layton
2022-09-12 13:51 ` J. Bruce Fields
2022-09-12 14:02 ` Jeff Layton
2022-09-12 14:47 ` J. Bruce Fields [this message]
2022-09-12 14:15 ` Trond Myklebust
2022-09-12 14:50 ` J. Bruce Fields
2022-09-12 14:56 ` Trond Myklebust
2022-09-12 15:32 ` Trond Myklebust
2022-09-12 15:49 ` Jeff Layton
2022-09-12 12:54 ` J. Bruce Fields
2022-09-12 12:59 ` Jeff Layton
2022-09-13 0:29 ` John Stoffel
2022-09-13 0:41 ` Dave Chinner
2022-09-13 1:49 ` NeilBrown
2022-09-13 2:41 ` Dave Chinner
2022-09-13 3:30 ` NeilBrown
2022-09-13 9:38 ` Theodore Ts'o
2022-09-13 19:02 ` J. Bruce Fields
2022-09-13 23:19 ` NeilBrown
2022-09-14 0:08 ` J. Bruce Fields
2022-09-09 20:34 ` John Stoffel
2022-09-10 22:13 ` NeilBrown
2022-09-12 10:43 ` Jeff Layton
2022-09-12 13:42 ` J. Bruce Fields
2022-09-12 23:14 ` NeilBrown
2022-09-15 14:06 ` J. Bruce Fields
2022-09-15 15:08 ` Trond Myklebust
2022-09-15 16:45 ` Jeff Layton
2022-09-15 17:49 ` Trond Myklebust
2022-09-15 18:11 ` Jeff Layton
2022-09-15 19:03 ` Trond Myklebust
2022-09-15 19:25 ` Jeff Layton
2022-09-15 22:23 ` NeilBrown
2022-09-16 6:54 ` Theodore Ts'o
2022-09-16 11:36 ` Jeff Layton
2022-09-16 15:11 ` Jeff Layton
2022-09-18 23:53 ` Dave Chinner
2022-09-19 13:13 ` Jeff Layton
2022-09-20 0:16 ` Dave Chinner
2022-09-20 10:26 ` Jeff Layton
2022-09-21 0:00 ` Dave Chinner
2022-09-21 10:33 ` Jeff Layton
2022-09-21 21:41 ` Dave Chinner
2022-09-22 10:18 ` Jeff Layton
2022-09-22 20:18 ` Jeff Layton
2022-09-23 9:56 ` Jan Kara
2022-09-23 10:19 ` Jeff Layton
2022-09-23 13:44 ` Trond Myklebust
2022-09-23 13:50 ` Jeff Layton
2022-09-23 14:58 ` Frank Filz
2022-09-26 22:43 ` NeilBrown
2022-09-27 11:14 ` Jeff Layton
2022-09-27 13:18 ` Jeff Layton
2022-09-15 15:41 ` Jeff Layton
2022-09-15 22:42 ` NeilBrown
2022-09-16 11:32 ` Jeff Layton
2022-09-09 12:11 ` Theodore Ts'o
2022-09-09 12:47 ` Jeff Layton
2022-09-09 13:48 ` Theodore Ts'o
2022-09-09 14:43 ` Jeff Layton
2022-09-09 14:58 ` Theodore Ts'o
2022-09-08 22:55 ` NeilBrown
2022-09-08 23:59 ` Trond Myklebust
2022-09-09 0:51 ` NeilBrown
2022-09-09 1:05 ` Trond Myklebust
2022-09-09 1:07 ` NeilBrown
2022-09-09 1:10 ` Trond Myklebust
2022-09-09 2:14 ` Trond Myklebust
2022-09-09 6:41 ` NeilBrown
2022-09-10 12:39 ` Jeff Layton
2022-09-10 22:53 ` NeilBrown
2022-09-12 10:25 ` Jeff Layton
2022-09-12 23:29 ` NeilBrown
2022-09-13 1:15 ` Dave Chinner
2022-09-13 1:41 ` NeilBrown
2022-09-13 19:01 ` Jeff Layton
2022-09-13 23:24 ` NeilBrown
2022-09-14 11:51 ` Jeff Layton
2022-09-14 22:45 ` NeilBrown
2022-09-14 23:02 ` NeilBrown
2022-09-08 22:40 ` NeilBrown
2022-09-07 13:55 ` Trond Myklebust
2022-09-07 14:05 ` Jeff Layton
2022-09-07 15:04 ` Trond Myklebust
2022-09-07 15:11 ` Jeff Layton
2022-09-08 0:40 ` NeilBrown
2022-09-08 11:34 ` Jeff Layton
2022-09-08 22:29 ` NeilBrown
2022-09-09 11:53 ` Jeff Layton
2022-09-10 22:58 ` NeilBrown
2022-09-10 19:46 ` Al Viro
2022-09-10 23:00 ` NeilBrown
2022-09-08 0:31 ` NeilBrown
2022-09-08 0:41 ` Trond Myklebust
2022-09-08 0:53 ` NeilBrown
2022-09-08 11:37 ` Jeff Layton
2022-09-08 12:40 ` Trond Myklebust
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