[3.16.y-ckt,060/104] jbd2: avoid infinite loop when destroying aborted journal

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index b892355f1944..d4c7e470dec8 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -475,14 +475,15 @@  int jbd2_cleanup_journal_tail(journal_t *journal)
  * journal_clean_one_cp_list
  *
  * Find all the written-back checkpoint buffers in the given list and
- * release them.
+ * release them. If 'destroy' is set, clean all buffers unconditionally.
  *
  * Called with the journal locked.
  * Called with j_list_lock held.
  * Returns number of buffers reaped (for debug)
  */
 
-static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
+static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy,
+				     int *released)
 {
 	struct journal_head *last_jh;
 	struct journal_head *next_jh = jh;
@@ -496,7 +497,10 @@  static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
 	do {
 		jh = next_jh;
 		next_jh = jh->b_cpnext;
-		ret = __try_to_free_cp_buf(jh);
+		if (!destroy)
+			ret = __try_to_free_cp_buf(jh);
+		else
+			ret = __jbd2_journal_remove_checkpoint(jh) + 1;
 		if (ret) {
 			freed++;
 			if (ret == 2) {
@@ -521,13 +525,14 @@  static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
  * journal_clean_checkpoint_list
  *
  * Find all the written-back checkpoint buffers in the journal and release them.
+ * If 'destroy' is set, release all buffers unconditionally.
  *
  * Called with the journal locked.
  * Called with j_list_lock held.
  * Returns number of buffers reaped (for debug)
  */
 
-int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
+int __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
 {
 	transaction_t *transaction, *last_transaction, *next_transaction;
 	int ret = 0;
@@ -543,7 +548,7 @@  int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
 		transaction = next_transaction;
 		next_transaction = transaction->t_cpnext;
 		ret += journal_clean_one_cp_list(transaction->
-				t_checkpoint_list, &released);
+				t_checkpoint_list, destroy, &released);
 		/*
 		 * This function only frees up some memory if possible so we
 		 * dont have an obligation to finish processing. Bail out if
@@ -559,7 +564,7 @@  int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
 		 * we can possibly see not yet submitted buffers on io_list
 		 */
 		ret += journal_clean_one_cp_list(transaction->
-				t_checkpoint_io_list, &released);
+				t_checkpoint_io_list, destroy, &released);
 		if (need_resched())
 			goto out;
 	} while (transaction != last_transaction);
@@ -568,6 +573,28 @@  out:
 }
 
 /*
+ * Remove buffers from all checkpoint lists as journal is aborted and we just
+ * need to free memory
+ */
+void jbd2_journal_destroy_checkpoint(journal_t *journal)
+{
+	/*
+	 * We loop because __jbd2_journal_clean_checkpoint_list() may abort
+	 * early due to a need of rescheduling.
+	 */
+	while (1) {
+		spin_lock(&journal->j_list_lock);
+		if (!journal->j_checkpoint_transactions) {
+			spin_unlock(&journal->j_list_lock);
+			break;
+		}
+		__jbd2_journal_clean_checkpoint_list(journal, true);
+		spin_unlock(&journal->j_list_lock);
+		cond_resched();
+	}
+}
+
+/*
  * journal_remove_checkpoint: called after a buffer has been committed
  * to disk (either by being write-back flushed to disk, or being
  * committed to the log).
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index b73e0215baa7..362e5f614450 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -510,7 +510,7 @@  void jbd2_journal_commit_transaction(journal_t *journal)
 	 * frees some memory
 	 */
 	spin_lock(&journal->j_list_lock);
-	__jbd2_journal_clean_checkpoint_list(journal);
+	__jbd2_journal_clean_checkpoint_list(journal, false);
 	spin_unlock(&journal->j_list_lock);
 
 	jbd_debug(3, "JBD2: commit phase 1\n");
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 72e238b50ad1..8c649c3f0a80 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1708,8 +1708,17 @@  int jbd2_journal_destroy(journal_t *journal)
 	while (journal->j_checkpoint_transactions != NULL) {
 		spin_unlock(&journal->j_list_lock);
 		mutex_lock(&journal->j_checkpoint_mutex);
-		jbd2_log_do_checkpoint(journal);
+		err = jbd2_log_do_checkpoint(journal);
 		mutex_unlock(&journal->j_checkpoint_mutex);
+		/*
+		 * If checkpointing failed, just free the buffers to avoid
+		 * looping forever
+		 */
+		if (err) {
+			jbd2_journal_destroy_checkpoint(journal);
+			spin_lock(&journal->j_list_lock);
+			break;
+		}
 		spin_lock(&journal->j_list_lock);
 	}
 
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index e1fb0f613a99..385593d748f6 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1042,8 +1042,9 @@  void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
 extern void jbd2_journal_commit_transaction(journal_t *);
 
 /* Checkpoint list management */
-int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
+int __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
 int __jbd2_journal_remove_checkpoint(struct journal_head *);
+void jbd2_journal_destroy_checkpoint(journal_t *journal);
 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);