ext4: super: extend timestamps to 40 bits

The inode timestamps use 34 bits in ext4, but the various timestamps in
the superblock are limited to 32 bits. If every user accesses these as
'unsigned', then this is good until year 2106, but it seems better to
extend this a bit further in the process of removing the deprecated
get_seconds() function.

This adds another byte for each timestamp in the superblock, making
them long enough to store timestamps beyond what is in the inodes,
which seems good enough here (in ocfs2, they are already 64-bit wide,
which is appropriate for a new layout).

I did not modify e2fsprogs, which obviously needs the same change to
actually interpret future timestamps correctly.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 30 insertions, 9 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b7f7922061be..67f4310edd0a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -312,6 +312,24 @@ void ext4_itable_unused_set(struct super_block *sb,
 		bg->bg_itable_unused_hi = cpu_to_le16(count >> 16);
 }
 
+static void __ext4_update_tstamp(__le32 *lo, __u8 *hi)
+{
+	time64_t now = ktime_get_real_seconds();
+
+	now = clamp_val(now, 0, (1ull << 40) - 1);
+
+	*lo = cpu_to_le32(lower_32_bits(now));
+	*hi = upper_32_bits(now);
+}
+
+static time64_t __ext4_get_tstamp(__le32 *lo, __u8 *hi)
+{
+	return ((time64_t)(*hi) << 32) + le32_to_cpu(*lo);
+}
+#define ext4_update_tstamp(es, tstamp) \
+	__ext4_update_tstamp(&(es)->tstamp, &(es)->tstamp ## _hi)
+#define ext4_get_tstamp(es, tstamp) \
+	__ext4_get_tstamp(&(es)->tstamp, &(es)->tstamp ## _hi)
 
 static void __save_error_info(struct super_block *sb, const char *func,
 			    unsigned int line)
@@ -322,11 +340,12 @@ static void __save_error_info(struct super_block *sb, const char *func,
 	if (bdev_read_only(sb->s_bdev))
 		return;
 	es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
-	es->s_last_error_time = cpu_to_le32(get_seconds());
+	ext4_update_tstamp(es, s_last_error_time);
 	strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func));
 	es->s_last_error_line = cpu_to_le32(line);
 	if (!es->s_first_error_time) {
 		es->s_first_error_time = es->s_last_error_time;
+		es->s_first_error_time_hi = es->s_last_error_time_hi;
 		strncpy(es->s_first_error_func, func,
 			sizeof(es->s_first_error_func));
 		es->s_first_error_line = cpu_to_le32(line);
@@ -2174,8 +2193,8 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 			 "warning: maximal mount count reached, "
 			 "running e2fsck is recommended");
 	else if (le32_to_cpu(es->s_checkinterval) &&
-		(le32_to_cpu(es->s_lastcheck) +
-			le32_to_cpu(es->s_checkinterval) <= get_seconds()))
+		 (ext4_get_tstamp(es, s_lastcheck) +
+		  le32_to_cpu(es->s_checkinterval) <= ktime_get_real_seconds()))
 		ext4_msg(sb, KERN_WARNING,
 			 "warning: checktime reached, "
 			 "running e2fsck is recommended");
@@ -2184,7 +2203,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 	if (!(__s16) le16_to_cpu(es->s_max_mnt_count))
 		es->s_max_mnt_count = cpu_to_le16(EXT4_DFL_MAX_MNT_COUNT);
 	le16_add_cpu(&es->s_mnt_count, 1);
-	es->s_mtime = cpu_to_le32(get_seconds());
+	ext4_update_tstamp(es, s_mtime);
 	ext4_update_dynamic_rev(sb);
 	if (sbi->s_journal)
 		ext4_set_feature_journal_needs_recovery(sb);
@@ -2875,8 +2894,9 @@ static void print_daily_error_info(struct timer_list *t)
 		ext4_msg(sb, KERN_NOTICE, "error count since last fsck: %u",
 			 le32_to_cpu(es->s_error_count));
 	if (es->s_first_error_time) {
-		printk(KERN_NOTICE "EXT4-fs (%s): initial error at time %u: %.*s:%d",
-		       sb->s_id, le32_to_cpu(es->s_first_error_time),
+		printk(KERN_NOTICE "EXT4-fs (%s): initial error at time %llu: %.*s:%d",
+		       sb->s_id,
+		       ext4_get_tstamp(es, s_first_error_time),
 		       (int) sizeof(es->s_first_error_func),
 		       es->s_first_error_func,
 		       le32_to_cpu(es->s_first_error_line));
@@ -2889,8 +2909,9 @@ static void print_daily_error_info(struct timer_list *t)
 		printk(KERN_CONT "\n");
 	}
 	if (es->s_last_error_time) {
-		printk(KERN_NOTICE "EXT4-fs (%s): last error at time %u: %.*s:%d",
-		       sb->s_id, le32_to_cpu(es->s_last_error_time),
+		printk(KERN_NOTICE "EXT4-fs (%s): last error at time %llu: %.*s:%d",
+		       sb->s_id,
+		       ext4_get_tstamp(es, s_last_error_time),
 		       (int) sizeof(es->s_last_error_func),
 		       es->s_last_error_func,
 		       le32_to_cpu(es->s_last_error_line));
@@ -4813,7 +4834,7 @@ static int ext4_commit_super(struct super_block *sb, int sync)
 	 * to complain and force a full file system check.
 	 */
 	if (!(sb->s_flags & SB_RDONLY))
-		es->s_wtime = cpu_to_le32(get_seconds());
+		ext4_update_tstamp(es, s_wtime);
 	if (sb->s_bdev->bd_part)
 		es->s_kbytes_written =
 			cpu_to_le64(EXT4_SB(sb)->s_kbytes_written +