From: Linus Torvalds <torvalds@linux-foundation.org>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: Jan Kara <jack@suse.cz>, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
John Stultz <jstultz@google.com>,
"Darrick J. Wong" <djwong@kernel.org>,
Christian Brauner <brauner@kernel.org>,
Chandan Babu R <chandan.babu@oracle.com>,
Hugh Dickins <hughd@google.com>,
linux-xfs <linux-xfs@vger.kernel.org>,
Dave Chinner <david@fromorbit.com>,
Andrew Morton <akpm@linux-foundation.org>,
dsterba@suse.com,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jeff Layton <jlayton@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux-MM <linux-mm@kvack.org>,
"open list:NFS, SUNRPC, AND..." <linux-nfs@vger.kernel.org>,
"Theodore Ts'o" <tytso@mit.edu>,
Al Viro <viro@zeniv.linux.org.uk>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
Amir Goldstein <amir73il@gmail.com>,
linux-btrfs <linux-btrfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Kent Overstreet <kent.overstreet@linux.dev>,
Stephen Boyd <sboyd@kernel.org>,
David Howells <dhowells@redhat.com>, Jan Kara <jack@suse.de>
Subject: Re: [PATCH RFC 2/9] timekeeping: new interfaces for multigrain timestamp handing
Date: Wed, 1 Nov 2023 12:23:44 -1000 [thread overview]
Message-ID: <CAHk-=wi+cVOE3VmJzN3C6TFepszCkrXeAFJY6b7bK=vV493rzQ@mail.gmail.com> (raw)
In-Reply-To: <3ae88800184f03b152aba6e4a95ebf26e854dd63.camel@hammerspace.com>
On Wed, Nov 1, 2023, 11:35 Trond Myklebust <trondmy@hammerspace.com> wrote:
>
> My client writes to the file and immediately reads the ctime. A 3rd
> party client then writes immediately after my ctime read.
> A reboot occurs (maybe minutes later), then I re-read the ctime, and
> get the same value as before the 3rd party write.
>
> Yes, most of the time that is better than the naked ctime, but not
> across a reboot.
Ahh, I knew I was missing something.
But I think it's fixable, with an additional rule:
- when generating STATX_CHANGE_COOKIE, if the ctime matches the
current time and the ctime counter is zero, set the ctime counter to
1.
That means that you will have *spurious* cache invalidations of such
cached data after a reboot, but only for reads that happened right
after the file was written.
Now, it's obviously not unheard of to finish writing a file, and then
immediately reading the results again.
But at least those caches should be somewhat limited (and the problem
then only happens when the nfs server is rebooted).
I *assume* that the whole thundering herd issue with lots of clients
tends to be for stable files, not files that were just written and
then immediately cached?
I dunno. I'm sure there's still some thinko here.
Linus
next prev parent reply other threads:[~2023-11-01 22:24 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-18 17:41 [PATCH RFC 0/9] fs: multigrain timestamps (redux) Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 1/9] fs: switch timespec64 fields in inode to discrete integers Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 2/9] timekeeping: new interfaces for multigrain timestamp handing Jeff Layton
2023-10-18 19:18 ` Linus Torvalds
2023-10-18 20:47 ` Jeff Layton
2023-10-18 21:31 ` Linus Torvalds
2023-10-18 21:52 ` Jeff Layton
2023-10-19 9:29 ` Christian Brauner
2023-10-19 11:28 ` Jeff Layton
2023-10-19 22:02 ` Dave Chinner
2023-10-20 12:12 ` Jeff Layton
2023-10-20 20:06 ` Linus Torvalds
2023-10-20 20:20 ` Linus Torvalds
2023-10-20 21:05 ` Jeff Layton
2023-10-22 22:17 ` Dave Chinner
2023-10-23 14:45 ` Jeff Layton
2023-10-23 23:26 ` Dave Chinner
2023-10-24 0:18 ` Linus Torvalds
2023-10-24 3:40 ` Dave Chinner
2023-10-24 4:10 ` Linus Torvalds
2023-10-24 7:08 ` Amir Goldstein
2023-10-24 18:40 ` Jeff Layton
2023-10-25 8:05 ` Dave Chinner
2023-10-25 10:41 ` Amir Goldstein
2023-10-25 12:25 ` Jeff Layton
2023-10-26 2:20 ` Dave Chinner
2023-10-26 5:42 ` Amir Goldstein
2023-10-27 10:35 ` Jeff Layton
2023-10-30 22:37 ` Dave Chinner
2023-10-30 23:11 ` Linus Torvalds
2023-10-31 1:42 ` Dave Chinner
2023-10-31 7:03 ` Amir Goldstein
2023-10-31 10:30 ` Christian Brauner
2023-10-31 11:29 ` Jeff Layton
2023-10-31 21:57 ` Dave Chinner
2023-10-31 23:02 ` Darrick J. Wong
2023-10-31 23:47 ` Dave Chinner
2023-11-01 10:16 ` Jan Kara
2023-11-01 11:38 ` Amir Goldstein
2023-11-02 10:17 ` Jeff Layton
2023-11-01 20:10 ` Linus Torvalds
2023-11-01 21:34 ` Trond Myklebust
2023-11-01 22:23 ` Linus Torvalds [this message]
2023-11-01 22:45 ` Trond Myklebust
2023-11-01 23:29 ` Dave Chinner
2023-11-02 10:29 ` Jeff Layton
2023-11-02 10:15 ` Jeff Layton
2023-10-31 23:12 ` Darrick J. Wong
2023-11-01 8:08 ` Amir Goldstein
2023-10-31 11:26 ` Jeff Layton
2023-10-31 19:43 ` John Stoffel
2023-10-31 11:04 ` Jeff Layton
2023-10-31 12:22 ` Jan Kara
2023-10-31 12:55 ` Jeff Layton
2023-10-30 23:34 ` ronnie sahlberg
2023-10-24 14:24 ` Jeff Layton
2023-10-24 19:06 ` Jeff Layton
2023-10-24 19:40 ` Linus Torvalds
2023-10-24 20:19 ` Jeff Layton
2023-10-31 10:26 ` Christian Brauner
2023-10-31 13:55 ` Jeff Layton
2023-10-19 22:00 ` Thomas Gleixner
2023-10-19 22:41 ` Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 3/9] timekeeping: add new debugfs file to count multigrain timestamps Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 4/9] fs: add infrastructure for " Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 5/9] fs: have setattr_copy handle multigrain timestamps appropriately Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 6/9] xfs: switch to multigrain timestamps Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 7/9] ext4: " Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 8/9] btrfs: convert " Jeff Layton
2023-10-18 17:41 ` [PATCH RFC 9/9] tmpfs: add support for " Jeff Layton
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