From: Dave Chinner <david@fromorbit.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
joseph@codesourcery.com, john.stultz@linaro.org,
hch@infradead.org, tglx@linutronix.de, geert@linux-m68k.org,
lftan@altera.com, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: [RFC 11/32] xfs: convert to struct inode_time
Date: Tue, 3 Jun 2014 18:41:30 +1000 [thread overview]
Message-ID: <20140603084130.GF14410@dastard> (raw)
In-Reply-To: <5082342.alZgfaU1Q0@wuerfel>
On Tue, Jun 03, 2014 at 09:33:36AM +0200, Arnd Bergmann wrote:
> On Tuesday 03 June 2014 10:32:27 Dave Chinner wrote:
> > On Mon, Jun 02, 2014 at 01:43:44PM +0200, Arnd Bergmann wrote:
> > > On Monday 02 June 2014 10:28:22 Dave Chinner wrote:
> > > > On Sun, Jun 01, 2014 at 10:24:37AM +1000, Dave Chinner wrote:
> > > > > On Sat, May 31, 2014 at 05:37:52PM +0200, Arnd Bergmann wrote:
> > > My patch set
> > > (at least with the 64-bit tv_sec) just gets 32-bit kernels to behave
> > > more like 64-bit kernels regarding inode time stamps, which does
> > > impact all the file systems that the a 64-bit time or the NFS
> > > unsigned epoch (1970-2106), while your patch extends the file
> > > system internal epoch (1901-2038 for XFS) so it can be used by
> > > anything that knows how to handle larger than 32-bit second values
> > > (either 64-bit kernel or 32-bit with inode_time patch).
> >
> > Right, but the issue is that 64 bit second counters are broken right
> > now because most filesystems can't support more than 32 bit values.
> > So it doesn't matter whether it's 32 bit or 64 bit machines, just
> > adding explicit support for >32 bit second counters without doing
> > anything else just extends that brokenness into the indefinite
> > future.
>
> Of course, "most filesystems" are obsolete, and most of the modern
> file systems already support >32 bit timestamps: ext4, btrfs, cifs,
> f2fs, 9p, nfsv4, ntfs, gfs2, ocfs2, fuse, ufs2. Everything else
> except xfs, ext2/3 and exofs uses the nfsv3 interpretation on
> 64-bit systems, which interprets time stamps with the high bit
> set as years 2038-2106 rather than 1903-1969.
I'm not sure that's an entirely correct representation - the
remainder of the 32 bit-only timestamp filesystems don't actively
interpret the time stamp at all - it's just an opaque 32 bit value.
hence the interpretation of the value is dependent on whether the
kernel treats it as signed or unsigned....
> > infrastructure), then we'll *never be able to fix it* and we'll be
> > stuck with timestamps that do really weird things when you pass
> > arbitrary future dates to the kernel.
>
> We already have that. I agree it's fixable and we should fix it,
> but I don't see how this is different from what we had 20 years
> ago when Linux on Alpha first introduced a 64-bit time_t. It's
> been this way on every 64-bit Linux system since.
I see it differently: we've got 20 years more experience than when
the 64 bit time_t was introduced. That experience tells us that best
practices for API design are to range check every input to prevent
unintended side effects from occurring due to out-of-range data....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2014-06-03 8:41 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
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 [this message]
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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