[02/18] xfs: explicitly define inode timestamp range

Commit Message

Darrick J. Wong Aug. 17, 2020, 10:59 p.m. UTC

From: Darrick J. Wong <[e-mail]>

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 <[e-mail]>
---
 libxfs/libxfs_api_defs.h |    4 ++++
 libxfs/xfs_format.h      |   19 +++++++++++++++++++
 2 files changed, 23 insertions(+)

Comments

Amir Goldstein Aug. 18, 2020, 2:17 p.m. UTC | #1

On Tue, Aug 18, 2020 at 2:23 AM Darrick J. Wong <[e-mail]> wrote:
>
> From: Darrick J. Wong <[e-mail]>
>
> 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 <[e-mail]>

Reviewed-by: Amir Goldstein <[e-mail]>

Patch

diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
index 99bc5b936da7..4ee02473df0d 100644
--- a/libxfs/libxfs_api_defs.h
+++ b/libxfs/libxfs_api_defs.h
@@ -14,6 +14,10 @@  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))
+
 /*
  * This file defines all the kernel based functions we expose to userspace
  * via the libxfs_* namespace. This is kept in a separate header file so
diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 88cbcb7950c3..f2a851e49ec3 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -849,11 +849,30 @@  struct xfs_agfl {
 	    ASSERT(xfs_daddr_to_agno(mp, d) == \
 		   xfs_daddr_to_agno(mp, (d) + (len) - 1)))
 
+/*
+ * XFS Timestamps
+ * ==============
+ *
+ * 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.
+ */
 typedef struct xfs_timestamp {
 	__be32		t_sec;		/* timestamp seconds */
 	__be32		t_nsec;		/* timestamp nanoseconds */
 } xfs_timestamp_t;
 
+/*
+ * Smallest possible timestamp with traditional timestamps, which is
+ * Dec 13 20:45:52 UTC 1901.
+ */
+#define XFS_INO_TIME_MIN	((int64_t)S32_MIN)
+
+/*
+ * Largest possible timestamp with traditional timestamps, which is
+ * Jan 19 03:14:07 UTC 2038.
+ */
+#define XFS_INO_TIME_MAX	((int64_t)S32_MAX)
+
 /*
  * On-disk inode structure.
  *