jbd2: replace current_kernel_time64 with ktime equivalent

jbd2 is one of the few callers of current_kernel_time64(), which
is a wrapper around ktime_get_coarse_real_ts64(). This calls the
latter directly for consistency with the rest of the kernel that
is moving to the ktime_get_ family of time accessors.
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/jbd2/commit.c

@@ -121,7 +121,7 @@ static int journal_submit_commit_record(journal_t *journal,
 	struct commit_header *tmp;
 	struct buffer_head *bh;
 	int ret;
-	struct timespec64 now = current_kernel_time64();
+	struct timespec64 now;
 
 	*cbh = NULL;
 
@@ -134,6 +134,7 @@ static int journal_submit_commit_record(journal_t *journal,
 		return 1;
 
 	tmp = (struct commit_header *)bh->b_data;
+	ktime_get_coarse_real_ts64(&now);
 	tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
 	tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);