jbd2: remove CONFIG_JBD2_DEBUG to update t_max_wait

CONFIG_JBD2_DEBUG and jbd2_journal_enable_debug knobs were added in
update_t_max_wait(), since earlier it used to take a spinlock for
updating t_max_wait, which could cause a bottleneck while starting a
txn (start_this_handle()).

Since in previous patch, we have killed t_handle_lock completely, we
could get rid of this debug config and knob to let t_max_wait be
updated by default again.
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/ad7319a601fd501079310747ce87d908e0944763.1644992076.git.riteshh@linux.ibm.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/jbd2/transaction.c

@@ -141,20 +141,19 @@ static void jbd2_get_transaction(journal_t *journal,
  * t_max_wait is carefully updated here with use of atomic compare exchange.
  * Note that there could be multiplre threads trying to do this simultaneously
  * hence using cmpxchg to avoid any use of locks in this case.
+ * With this t_max_wait can be updated w/o enabling jbd2_journal_enable_debug.
  */
 static inline void update_t_max_wait(transaction_t *transaction,
 				     unsigned long ts)
 {
-#ifdef CONFIG_JBD2_DEBUG
 	unsigned long oldts, newts;
-	if (jbd2_journal_enable_debug &&
-	    time_after(transaction->t_start, ts)) {
+
+	if (time_after(transaction->t_start, ts)) {
 		newts = jbd2_time_diff(ts, transaction->t_start);
 		oldts = READ_ONCE(transaction->t_max_wait);
 		while (oldts < newts)
 			oldts = cmpxchg(&transaction->t_max_wait, oldts, newts);
 	}
-#endif
 }
 
 /*