| Message ID | 1658052449-567-1-git-send-email-hexiaole1994@126.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/2] xfsdocs: fix inode timestamps lower limit value | expand |
On Sun, Jul 17, 2022 at 06:07:28PM +0800, Xiaole He wrote: > 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' as below: > > /* fs/xfs/libxfs/xfs_format.h begin */ > struct xfs_legacy_timestamp { > __be32 t_sec; /* timestamp seconds */ > __be32 t_nsec; /* timestamp nanoseconds */ > }; > #define XFS_LEGACY_TIME_MIN ((int64_t)S32_MIN) > #define XFS_LEGACY_TIME_MAX ((int64_t)S32_MAX) > /* fs/xfs/libxfs/xfs_format.h end */ > /* include/linux/limits.h begin */ > #define U32_MAX ((u32)~0U) > #define S32_MAX ((s32)(U32_MAX >> 1)) > #define S32_MIN ((s32)(-S32_MAX - 1)) > /* 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@~]# date --utc -d '@0' +'%Y-%m-%d %H:%M:%S' > 1970-01-01 00:00:00 > [root@~]# date --utc -d "@`echo '-(2^31)'|bc`" +'%Y-%m-%d %H:%M:%S' > 1901-12-13 20:45:52 > [root@~]# > /* 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 '31st' to '13st'. > > Signed-off-by: Xiaole He <hexiaole@kylinos.cn> Looks correct, will commit... Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > V1 -> V2: Wrap line at 72 column, add Signed-off-by, add one more > 'date' command for explanation, remove the question section. > > 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]] > -- > 1.8.3.1 >
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]]
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' as below: /* fs/xfs/libxfs/xfs_format.h begin */ struct xfs_legacy_timestamp { __be32 t_sec; /* timestamp seconds */ __be32 t_nsec; /* timestamp nanoseconds */ }; #define XFS_LEGACY_TIME_MIN ((int64_t)S32_MIN) #define XFS_LEGACY_TIME_MAX ((int64_t)S32_MAX) /* fs/xfs/libxfs/xfs_format.h end */ /* include/linux/limits.h begin */ #define U32_MAX ((u32)~0U) #define S32_MAX ((s32)(U32_MAX >> 1)) #define S32_MIN ((s32)(-S32_MAX - 1)) /* 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@~]# date --utc -d '@0' +'%Y-%m-%d %H:%M:%S' 1970-01-01 00:00:00 [root@~]# date --utc -d "@`echo '-(2^31)'|bc`" +'%Y-%m-%d %H:%M:%S' 1901-12-13 20:45:52 [root@~]# /* 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 '31st' to '13st'. Signed-off-by: Xiaole He <hexiaole@kylinos.cn> --- V1 -> V2: Wrap line at 72 column, add Signed-off-by, add one more 'date' command for explanation, remove the question section. design/XFS_Filesystem_Structure/timestamps.asciidoc | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)