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From: Roger Willcocks <roger@filmlight.ltd.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	lftan@altera.com, hch@infradead.org, john.stultz@linaro.org,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-fsdevel@vger.kernel.org, geert@linux-m68k.org,
	tglx@linutronix.de, xfs@oss.sgi.com, joseph@codesourcery.com
Subject: Re: [RFC 11/32] xfs: convert to struct inode_time
Date: Mon, 02 Jun 2014 12:35:41 +0100	[thread overview]
Message-ID: <1401708941.6065.51.camel@montana.filmlight.ltd.uk> (raw)
In-Reply-To: <20140602002822.GQ14410@dastard>


On Mon, 2014-06-02 at 10:28 +1000, Dave Chinner wrote:

> 
> The 32 bit second counters in timestamps are too small to represent
> time beyond the unix epoch (jan 2038) correctly. Extend the on-disk
> format for a timestamp to include an 8-bit epoch counter so that we
> can extend time for up to 255 Unix epochs. This should be good for
> representing timestamps from 1970 to somewhere around 19,000 A.D....
> 

I assume you're using an 'epoch' variable and not simply using the
padding byte as an eight-bit prefix to the existing 32-bit counter
because the existing counter is signed ?

For long term sanity it might make more sense for the eight-bit value to
be a simple (sign-extended) prefix from 1970.

So if the feature bit is set it's a 40-bit signed time, which is good
for 1970 +/- 17400 years or so.

--
Roger






  reply	other threads:[~2014-06-02 11:42 UTC|newest]

Thread overview: 124+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-30 20:01 [RFC 00/32] making inode time stamps y2038 ready Arnd Bergmann
2014-05-30 20:01 ` [RFC 01/32] fs: introduce new 'struct inode_time' Arnd Bergmann
2014-05-31  7:56   ` Geert Uytterhoeven
2014-05-31  8:39     ` Andreas Schwab
2014-05-31 13:19       ` Geert Uytterhoeven
2014-05-31 13:46         ` Andreas Schwab
2014-05-31 14:54       ` Arnd Bergmann
2014-05-31 16:15         ` Geert Uytterhoeven
2014-05-31  9:03   ` H. Peter Anvin
2014-05-31 14:53     ` Arnd Bergmann
2014-05-31 14:55       ` H. Peter Anvin
2014-05-30 20:01 ` [RFC 02/32] uapi: add struct __kernel_timespec{32,64} Arnd Bergmann
2014-05-30 20:18   ` H. Peter Anvin
2014-05-31 15:09     ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 03/32] fs: introduce sys_utimens64at Arnd Bergmann
2014-05-31  9:22   ` Andreas Schwab
2014-05-31 14:55     ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 04/32] fs: introduce sys_newfstat64/sys_newfstatat64 Arnd Bergmann
2014-05-30 20:01 ` [RFC 05/32] arch: hook up new stat and utimes syscalls Arnd Bergmann
2014-05-30 20:01 ` [RFC 06/32] isofs: fix timestamps beyond 2027 Arnd Bergmann
2014-05-31  7:59   ` Geert Uytterhoeven
2014-05-31  8:47     ` H. Peter Anvin
2014-05-30 20:01 ` [RFC 07/32] fs/nfs: convert to struct inode_time Arnd Bergmann
2014-05-30 20:01 ` [RFC 08/32] fs/ceph: convert to 'struct inode_time' Arnd Bergmann
2014-05-30 20:01 ` [RFC 09/32] fs/pstore: convert to struct inode_time Arnd Bergmann
2014-05-30 21:14   ` Kees Cook
2014-05-30 20:01 ` [RFC 10/32] fs/coda: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 11/32] xfs: " Arnd Bergmann
2014-05-31  0:37   ` Dave Chinner
2014-05-31  0:41     ` H. Peter Anvin
2014-05-31  1:14       ` Dave Chinner
2014-05-31  1:22         ` H. Peter Anvin
2014-05-31  5:54           ` Dave Chinner
2014-05-31  8:41             ` H. Peter Anvin
2014-05-31 15:46               ` Nicolas Pitre
2014-06-01 19:56                 ` Arnd Bergmann
2014-06-01 20:26                   ` H. Peter Anvin
2014-06-02 11:02                     ` Arnd Bergmann
2014-06-02  1:36                   ` Nicolas Pitre
2014-06-02  2:22                     ` Dave Chinner
2014-06-02  7:09                       ` Geert Uytterhoeven
2014-06-02 10:56                     ` Arnd Bergmann
2014-06-02 11:57                       ` Theodore Ts'o
2014-06-02 12:38                         ` Arnd Bergmann
2014-06-02 13:15                           ` Theodore Ts'o
2014-06-02 12:52                         ` Arnd Bergmann
2014-06-02 13:07                           ` Theodore Ts'o
2014-06-02 15:01                             ` Arnd Bergmann
2014-06-02 14:52                         ` H. Peter Anvin
2014-06-02 15:04                       ` Chuck Lever
2014-06-02 15:31                         ` Theodore Ts'o
2014-06-02 17:12                           ` H. Peter Anvin
2014-06-02 18:50                             ` Arnd Bergmann
2014-06-02 22:29                             ` Theodore Ts'o
2014-06-02 22:32                               ` H. Peter Anvin
2014-06-02 23:32                                 ` Theodore Ts'o
2014-06-02 23:33                                   ` H. Peter Anvin
2014-06-03 13:09                                   ` Roger Willcocks
2014-06-02 18:52                         ` Arnd Bergmann
2014-06-02 18:58                         ` Roger Willcocks
2014-06-02 19:04                           ` Chuck Lever
2014-06-02 19:10                             ` Arnd Bergmann
2014-06-01  0:39               ` Dave Chinner
2014-06-02 14:00             ` Joseph S. Myers
2014-05-31 15:37         ` Arnd Bergmann
2014-06-01  0:24           ` Dave Chinner
2014-06-02  0:28             ` Dave Chinner
2014-06-02 11:35               ` Roger Willcocks [this message]
2014-06-02 11:43               ` Arnd Bergmann
2014-06-03  0:32                 ` Dave Chinner
2014-06-03  7:33                   ` Arnd Bergmann
2014-06-03  8:41                     ` Dave Chinner
2014-06-03  9:16                       ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 12/32] btrfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 13/32] ext3: " Arnd Bergmann
2014-05-31  9:10   ` H. Peter Anvin
2014-05-31 14:32     ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 14/32] ext4: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 15/32] cifs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 16/32] ntfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 17/32] ubifs: " Arnd Bergmann
2014-06-02  7:54   ` Artem Bityutskiy
2014-05-30 20:01 ` [RFC 18/32] ocfs2: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 19/32] fs/fat: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 20/32] afs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 21/32] udf: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 22/32] fs: convert simple fs to inode_time Arnd Bergmann
2014-05-30 23:06   ` Greg Kroah-Hartman
2014-05-30 20:01 ` [RFC 23/32] logfs: convert to struct inode_time Arnd Bergmann
2014-05-30 20:01 ` [RFC 24/32] hfs, hfsplus: " Arnd Bergmann
2014-05-31 14:23   ` Vyacheslav Dubeyko
2014-05-30 20:01 ` [RFC 25/32] gfs2: " Arnd Bergmann
2014-06-02  9:52   ` Steven Whitehouse
2014-05-30 20:01 ` [RFC 26/32] reiserfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 27/32] jffs2: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 28/32] adfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 29/32] f2fs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 30/32] fuse: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 31/32] scsi: fnic: use current_kernel_time() for timestamp Arnd Bergmann
2014-05-30 20:01 ` [RFC 32/32] fs: use new inode_time definition unconditionally Arnd Bergmann
2014-05-31 14:30 ` [RFC 00/32] making inode time stamps y2038 ready Vyacheslav Dubeyko
2014-06-03 12:21   ` Arnd Bergmann
2014-05-31 14:51 ` Richard Cochran
2014-05-31 15:23   ` Arnd Bergmann
2014-05-31 18:22     ` Richard Cochran
2014-05-31 19:34       ` H. Peter Anvin
2014-06-01  4:46         ` Richard Cochran
2014-06-01  4:44     ` Richard Cochran
2014-06-02 13:52 ` Joseph S. Myers
2014-06-02 19:19   ` Arnd Bergmann
2014-06-02 19:26     ` H. Peter Anvin
2014-06-02 19:55       ` Arnd Bergmann
2014-06-02 21:57         ` H. Peter Anvin
2014-06-03 14:22           ` Arnd Bergmann
2014-06-03 14:33             ` Joseph S. Myers
2014-06-03 14:37               ` Arnd Bergmann
2014-06-03 21:38             ` Dave Chinner
2014-06-04 15:03               ` Arnd Bergmann
2014-06-04 17:30                 ` Nicolas Pitre
2014-06-04 19:24                   ` Arnd Bergmann
2014-06-05  0:10                     ` H. Peter Anvin
2014-06-10  9:54                       ` Arnd Bergmann
2014-06-02 21:02     ` Joseph S. Myers
2014-06-04 15:05       ` Arnd Bergmann

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