1 files changed, 27 insertions, 19 deletions

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index d95cc9d0401d..f3479d6e0a83 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -82,6 +82,32 @@ jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
  */
 
 /*
+ * Update transiaction's maximum wait time, if debugging is enabled.
+ *
+ * In order for t_max_wait to be reliable, it must be protected by a
+ * lock.  But doing so will mean that start_this_handle() can not be
+ * run in parallel on SMP systems, which limits our scalability.  So
+ * unless debugging is enabled, we no longer update t_max_wait, which
+ * means that maximum wait time reported by the jbd2_run_stats
+ * tracepoint will always be zero.
+ */
+static inline void update_t_max_wait(transaction_t *transaction)
+{
+#ifdef CONFIG_JBD2_DEBUG
+        unsigned long ts = jiffies;
+
+        if (jbd2_journal_enable_debug &&
+            time_after(transaction->t_start, ts)) {
+                ts = jbd2_time_diff(ts, transaction->t_start);
+                spin_lock(&transaction->t_handle_lock);
+                if (ts > transaction->t_max_wait)
+                        transaction->t_max_wait = ts;
+                spin_unlock(&transaction->t_handle_lock);
+        }
+#endif
+}
+
+/*
  * start_this_handle: Given a handle, deal with any locking or stalling
  * needed to make sure that there is enough journal space for the handle
  * to begin.  Attach the handle to a transaction and set up the
@@ -95,7 +121,6 @@ static int start_this_handle(journal_t *journal, handle_t *handle,
         int needed;
         int nblocks = handle->h_buffer_credits;
         transaction_t *new_transaction = NULL;
-        unsigned long ts = jiffies;
 
         if (nblocks > journal->j_max_transaction_buffers) {
                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
@@ -241,25 +266,8 @@ repeat:
 
         /* OK, account for the buffers that this operation expects to
          * use and add the handle to the running transaction. 
-         *
-         * In order for t_max_wait to be reliable, it must be
-         * protected by a lock.  But doing so will mean that
-         * start_this_handle() can not be run in parallel on SMP
-         * systems, which limits our scalability.  So we only enable
-         * it when debugging is enabled.  We may want to use a
-         * separate flag, eventually, so we can enable this
-         * independently of debugging.
          */
-#ifdef CONFIG_JBD2_DEBUG
-        if (jbd2_journal_enable_debug &&
-            time_after(transaction->t_start, ts)) {
-                ts = jbd2_time_diff(ts, transaction->t_start);
-                spin_lock(&transaction->t_handle_lock);
-                if (ts > transaction->t_max_wait)
-                        transaction->t_max_wait = ts;
-                spin_unlock(&transaction->t_handle_lock);
-        }
-#endif
+        update_t_max_wait(transaction);
         handle->h_transaction = transaction;
         atomic_inc(&transaction->t_updates);
         atomic_inc(&transaction->t_handle_count);