nilfs2: use 64-bit superblock timstamps

The mount time field in the superblock uses a 64-bit timestamp, but
calling get_seconds() may truncate the current time to 32 bits.

This changes it to ktime_get_real_seconds() to avoid the potential
overflow.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Ryusuke Konishi <[email protected]>
Cc: David Howells <[email protected]>
Cc: Jeff Layton <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/nilfs2/super.c

@@ -834,7 +834,7 @@ static int nilfs_setup_super(struct super_block *sb, int is_mount)
 		sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
 
 	sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
-	sbp[0]->s_mtime = cpu_to_le64(get_seconds());
+	sbp[0]->s_mtime = cpu_to_le64(ktime_get_real_seconds());
 
 skip_mount_setup:
 	sbp[0]->s_state =