From: hexiaole <hexiaole@xxxxxxxxxx> 1. Fix description In kernel source tree 'fs/xfs/libxfs/xfs_format.h', there defined inode timestamps as 'xfs_legacy_timestamp' if the 'bigtime' feature disabled, and also defined the min and max time constants 'XFS_LEGACY_TIME_MIN' and 'XFS_LEGACY_TIME_MAX': /* fs/xfs/libxfs/xfs_format.h begin */ struct xfs_legacy_timestamp { __be32 t_sec; /* timestamp seconds */ __be32 t_nsec; /* timestamp nanoseconds */ }; /* fs/xfs/libxfs/xfs_format.h end */ /* include/linux/limits.h begin */ /* include/linux/limits.h end */ When the 't_sec' and 't_nsec' are 0, the time value it represents is 1970-01-01 00:00:00 UTC, the 'XFS_LEGACY_TIME_MIN', that is -(2^31), represents the min second offset relative to the 1970-01-01 00:00:00 UTC, it can be converted to human-friendly time value by 'date' command: /* command begin */ [root@DESKTOP-G0RBR07 sources]# date --utc -d "@`echo '-(2^31)'|bc`" +'%Y-%m-%d %H:%M:%S' 1901-12-13 20:45:52 [root@DESKTOP-G0RBR07 sources]# /* command end */ That is, the min time value is 1901-12-13 20:45:52 UTC, but the 'design/XFS_Filesystem_Structure/timestamps.asciidoc' write the min time value as 'The smalle st date this format can represent is 20:45:52 UTC on December 31st', there should be a typo, and this patch correct 2 places of wrong min time value, from '3 1st' to '13st'. 2. Question In the section 'Quota Timers' of 'design/XFS_Filesystem_Structure/timestamps.asciidoc': /* timestamps.asciidoc begin */ With the introduction of the bigtime feature, the ondisk field now encodes the upper 32 bits of an unsigned 34-bit seconds counter. ... The smallest quota expiration date is now 00:00:04 UTC on January 1st, 1970; and the largest is 20:20:24 UTC on July 2nd, 2486. /* timestamps.asciidoc end */ It seems hard to understand the the relationship among the '32 bits of an unsigned 34-bit seconds counter', '00:00:04 UTC on January 1st, 1970', and 00:00:04 UTC on January 1st, 1970', is it there a typo for '34-bit' and the expected one is '64-bit'? --- design/XFS_Filesystem_Structure/timestamps.asciidoc | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/design/XFS_Filesystem_Structure/timestamps.asciidoc b/design/XFS_Filesystem_Structure/timestamps.asciidoc index 08baa1e..56d4dc9 100644 --- a/design/XFS_Filesystem_Structure/timestamps.asciidoc +++ b/design/XFS_Filesystem_Structure/timestamps.asciidoc @@ -26,13 +26,13 @@ struct xfs_legacy_timestamp { }; ---- -The smallest date this format can represent is 20:45:52 UTC on December 31st, +The smallest date this format can represent is 20:45:52 UTC on December 13st, 1901, and the largest date supported is 03:14:07 UTC on January 19, 2038. With the introduction of the bigtime feature, the format is changed to interpret the timestamp as a 64-bit count of nanoseconds since the smallest date supported by the old encoding. This means that the smallest date -supported is still 20:45:52 UTC on December 31st, 1901; but now the largest +supported is still 20:45:52 UTC on December 13st, 1901; but now the largest date supported is 20:20:24 UTC on July 2nd, 2486. [[Quota_Timers]] -- 2.27.0