https://bugzilla.kernel.org/show_bug.cgi?id=38642 Summary: ext4 timestamp format unable to uniquely represent times Product: File System Version: 2.5 Kernel Version: all Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 AssignedTo: fs_ext4@xxxxxxxxxxxxxxxxxxxx ReportedBy: ersmith.nospam@xxxxxxxxxxxxxxxx Regression: No The presence of the extra bits in the ext4 timestamps implies a desire to represent file times to sub-second accuracy. Unfortunately, standard posix timestamps are not uniformly 1 SI second long, due to the presence of leap seconds. For example, the Posix timestamp 1230768000 corresponds to the UTC times "2008-12-31 23:59:60" and "2009-01-01 00:00:00". Since there are only 30 bits in the nanosecond field, ext4 cannot accurately keep track of file times during a leap second. One possible solution would be to add another bit to the nanosecond field, allowing nanoseconds to range from 0 to 1999999999 and hence allowing sufficient range to keep accurate time even during "long" posix timestamps. Another would be to specify that the seconds fields of ext4 time stamps should hold actual SI seconds elapsed, rather than POSIX timestamps; this would be considerably more complicated, though. -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
