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@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
