xfs: explicitly define inode timestamp range

Source kernel commit: 876fdc7c4f366a709ac272ef3336ae7dce58f2af

Formally define the inode timestamp ranges that existing filesystems
support, and switch the vfs timetamp ranges to use it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/include/xfs_fs_compat.h b/include/xfs_fs_compat.h
index d0ffc9775875b0ed5dd9abe097e0344f3e193b62..0077f00cb9490421ca5a348f07e2d82fc6508e65 100644 (file)
--- a/include/xfs_fs_compat.h
+++ b/include/xfs_fs_compat.h
@@ -93,4 +93,8 @@ struct timespec64 {
        long            tv_nsec;                /* nanoseconds */
 };
 
+#define U32_MAX                ((uint32_t)~0U)
+#define S32_MAX                ((int32_t)(U32_MAX >> 1))
+#define S32_MIN                ((int32_t)(-S32_MAX - 1))
+
 #endif /* __XFS_FS_COMPAT_H__ */

diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 01544f9d5a574853a2de31a4f12b1150363dfe2d..5683071558823d3c7861d4841acca955c1327845 100644 (file)
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -847,11 +847,33 @@ struct xfs_agfl {
            ASSERT(xfs_daddr_to_agno(mp, d) == \
                   xfs_daddr_to_agno(mp, (d) + (len) - 1)))
 
+/*
+ * XFS Timestamps
+ * ==============
+ *
+ * Traditional ondisk inode timestamps consist of signed 32-bit counters for
+ * seconds and nanoseconds; time zero is the Unix epoch, Jan  1 00:00:00 UTC
+ * 1970, which means that the timestamp epoch is the same as the Unix epoch.
+ * Therefore, the ondisk min and max defined here can be used directly to
+ * constrain the incore timestamps on a Unix system.
+ */
 typedef struct xfs_timestamp {
        __be32          t_sec;          /* timestamp seconds */
        __be32          t_nsec;         /* timestamp nanoseconds */
 } xfs_timestamp_t;
 
+/*
+ * Smallest possible ondisk seconds value with traditional timestamps.  This
+ * corresponds exactly with the incore timestamp Dec 13 20:45:52 UTC 1901.
+ */
+#define XFS_LEGACY_TIME_MIN    ((int64_t)S32_MIN)
+
+/*
+ * Largest possible ondisk seconds value with traditional timestamps.  This
+ * corresponds exactly with the incore timestamp Jan 19 03:14:07 UTC 2038.
+ */
+#define XFS_LEGACY_TIME_MAX    ((int64_t)S32_MAX)
+
 /*
  * On-disk inode structure.
  *