1 files changed, 38 insertions, 5 deletions

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index c0b66a7a795b..116d8251fbff 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -138,9 +138,9 @@ static inline void update_t_max_wait(transaction_t *transaction,
 }
 
 /*
- * Wait until running transaction passes T_LOCKED state. Also starts the commit
- * if needed. The function expects running transaction to exist and releases
- * j_state_lock.
+ * Wait until running transaction passes to T_FLUSH state and new transaction
+ * can thus be started. Also starts the commit if needed. The function expects
+ * running transaction to exist and releases j_state_lock.
  */
 static void wait_transaction_locked(journal_t *journal)
 	__releases(journal->j_state_lock)
@@ -160,6 +160,32 @@ static void wait_transaction_locked(journal_t *journal)
 	finish_wait(&journal->j_wait_transaction_locked, &wait);
 }
 
+/*
+ * Wait until running transaction transitions from T_SWITCH to T_FLUSH
+ * state and new transaction can thus be started. The function releases
+ * j_state_lock.
+ */
+static void wait_transaction_switching(journal_t *journal)
+	__releases(journal->j_state_lock)
+{
+	DEFINE_WAIT(wait);
+
+	if (WARN_ON(!journal->j_running_transaction ||
+		    journal->j_running_transaction->t_state != T_SWITCH))
+		return;
+	prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
+			TASK_UNINTERRUPTIBLE);
+	read_unlock(&journal->j_state_lock);
+	/*
+	 * We don't call jbd2_might_wait_for_commit() here as there's no
+	 * waiting for outstanding handles happening anymore in T_SWITCH state
+	 * and handling of reserved handles actually relies on that for
+	 * correctness.
+	 */
+	schedule();
+	finish_wait(&journal->j_wait_transaction_locked, &wait);
+}
+
 static void sub_reserved_credits(journal_t *journal, int blocks)
 {
 	atomic_sub(blocks, &journal->j_reserved_credits);
@@ -183,7 +209,8 @@ static int add_transaction_credits(journal_t *journal, int blocks,
 	 * If the current transaction is locked down for commit, wait
 	 * for the lock to be released.
 	 */
-	if (t->t_state == T_LOCKED) {
+	if (t->t_state != T_RUNNING) {
+		WARN_ON_ONCE(t->t_state >= T_FLUSH);
 		wait_transaction_locked(journal);
 		return 1;
 	}
@@ -360,8 +387,14 @@ repeat:
 		/*
 		 * We have handle reserved so we are allowed to join T_LOCKED
 		 * transaction and we don't have to check for transaction size
-		 * and journal space.
+		 * and journal space. But we still have to wait while running
+		 * transaction is being switched to a committing one as it
+		 * won't wait for any handles anymore.
 		 */
+		if (transaction->t_state == T_SWITCH) {
+			wait_transaction_switching(journal);
+			goto repeat;
+		}
 		sub_reserved_credits(journal, blocks);
 		handle->h_reserved = 0;
 	}