jbd2: convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.com>
Cc: linux-ext4@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>

fs/jbd2/journal.c

@@ -165,11 +165,11 @@ static void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb)
  * Helper function used to manage commit timeouts
  */
 
-static void commit_timeout(unsigned long __data)
+static void commit_timeout(struct timer_list *t)
 {
-	struct task_struct * p = (struct task_struct *) __data;
+	journal_t *journal = from_timer(journal, t, j_commit_timer);
 
-	wake_up_process(p);
+	wake_up_process(journal->j_task);
 }
 
 /*
@@ -197,8 +197,7 @@ static int kjournald2(void *arg)
 	 * Set up an interval timer which can be used to trigger a commit wakeup
 	 * after the commit interval expires
 	 */
-	setup_timer(&journal->j_commit_timer, commit_timeout,
-			(unsigned long)current);
+	timer_setup(&journal->j_commit_timer, commit_timeout, 0);
 
 	set_freezable();