ext4: use 64-bit timestamps for mmp_time

The mmp_time field is 64 bits wide, which is good, but calling
get_seconds() results in a 32-bit value on 32-bit architectures. Using
ktime_get_real_seconds() instead returns 64 bits everywhere.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/mmp.c

@@ -147,7 +147,7 @@ static int kmmpd(void *data)
 
 	mmp_block = le64_to_cpu(es->s_mmp_block);
 	mmp = (struct mmp_struct *)(bh->b_data);
-	mmp->mmp_time = cpu_to_le64(get_seconds());
+	mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds());
 	/*
 	 * Start with the higher mmp_check_interval and reduce it if
 	 * the MMP block is being updated on time.
@@ -165,7 +165,7 @@ static int kmmpd(void *data)
 			seq = 1;
 
 		mmp->mmp_seq = cpu_to_le32(seq);
-		mmp->mmp_time = cpu_to_le64(get_seconds());
+		mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds());
 		last_update_time = jiffies;
 
 		retval = write_mmp_block(sb, bh);
@@ -241,7 +241,7 @@ static int kmmpd(void *data)
 	 * Unmount seems to be clean.
 	 */
 	mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
-	mmp->mmp_time = cpu_to_le64(get_seconds());
+	mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds());
 
 	retval = write_mmp_block(sb, bh);