ext4: 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: Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: linux-ext4@vger.kernel.org

fs/ext4/super.c

@@ -2794,14 +2794,11 @@ static int ext4_feature_set_ok(struct super_block *sb, int readonly)
  * This function is called once a day if we have errors logged
  * on the file system
  */
-static void print_daily_error_info(unsigned long arg)
+static void print_daily_error_info(struct timer_list *t)
 {
-	struct super_block *sb = (struct super_block *) arg;
-	struct ext4_sb_info *sbi;
-	struct ext4_super_block *es;
-
-	sbi = EXT4_SB(sb);
-	es = sbi->s_es;
+	struct ext4_sb_info *sbi = from_timer(sbi, t, s_err_report);
+	struct super_block *sb = sbi->s_sb;
+	struct ext4_super_block *es = sbi->s_es;
 
 	if (es->s_error_count)
 		/* fsck newer than v1.41.13 is needed to clean this condition. */
@@ -3988,8 +3985,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 	spin_lock_init(&sbi->s_next_gen_lock);
 
-	setup_timer(&sbi->s_err_report, print_daily_error_info,
-		(unsigned long) sb);
+	timer_setup(&sbi->s_err_report, print_daily_error_info, 0);
 
 	/* Register extent status tree shrinker */
 	if (ext4_es_register_shrinker(sbi))