[PATCH 01/11] xfs: explicitly define inode timestamp range

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: darrick.wong@oracle.com
Cc: Amir Goldstein <amir73il@gmail.com>,
	linux-xfs@vger.kernel.org, amir73il@gmail.com,
	sandeen@sandeen.net
Subject: [PATCH 01/11] xfs: explicitly define inode timestamp range
Date: Thu, 20 Aug 2020 19:11:34 -0700	[thread overview]
Message-ID: <159797589388.965217.3068074933916806311.stgit@magnolia> (raw)
In-Reply-To: <159797588727.965217.7260803484540460144.stgit@magnolia>

From: Darrick J. Wong <darrick.wong@oracle.com>

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>
---
 fs/xfs/libxfs/xfs_format.h |   19 +++++++++++++++++++
 fs/xfs/xfs_ondisk.h        |   12 ++++++++++++
 fs/xfs/xfs_super.c         |    5 +++--
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index be86fa1a5556..b1b8a5c05cea 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/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.
  *
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index acb9b737fe6b..48a64fa49f91 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -15,6 +15,18 @@
 		"XFS: offsetof(" #structname ", " #member ") is wrong, " \
 		"expected " #off)
 
+#define XFS_CHECK_VALUE(value, expected) \
+	BUILD_BUG_ON_MSG((value) != (expected), \
+		"XFS: value of " #value " is wrong, expected " #expected)
+
+static inline void __init
+xfs_check_limits(void)
+{
+	/* make sure timestamp limits are correct */
+	XFS_CHECK_VALUE(XFS_INO_TIME_MIN,			-2147483648LL);
+	XFS_CHECK_VALUE(XFS_INO_TIME_MAX,			2147483647LL);
+}
+
 static inline void __init
 xfs_check_ondisk_structs(void)
 {
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index c7ffcb57b586..375f05a47ba4 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1484,8 +1484,8 @@ xfs_fc_fill_super(
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_max_links = XFS_MAXLINK;
 	sb->s_time_gran = 1;
-	sb->s_time_min = S32_MIN;
-	sb->s_time_max = S32_MAX;
+	sb->s_time_min = XFS_INO_TIME_MIN;
+	sb->s_time_max = XFS_INO_TIME_MAX;
 	sb->s_iflags |= SB_I_CGROUPWB;
 
 	set_posix_acl_flag(sb);
@@ -2077,6 +2077,7 @@ init_xfs_fs(void)
 {
 	int			error;
 
+	xfs_check_limits();
 	xfs_check_ondisk_structs();
 
 	printk(KERN_INFO XFS_VERSION_STRING " with "

