diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 77c54749f432..4621b8043021 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -3512,6 +3512,7 @@ static int try_flush_qgroup(struct btrfs_root *root)
 {
 	struct btrfs_trans_handle *trans;
 	int ret;
+	bool can_commit = true;
 
 	/*
 	 * We don't want to run flush again and again, so if there is a running
@@ -3523,6 +3524,20 @@ static int try_flush_qgroup(struct btrfs_root *root)
 		return 0;
 	}
 
+	/*
+	 * If current process holds a transaction, we shouldn't flush, as we
+	 * assume all space reservation happens before a transaction handle is
+	 * held.
+	 *
+	 * But there are cases like btrfs_delayed_item_reserve_metadata() where
+	 * we try to reserve space with one transction handle already held.
+	 * In that case we can't commit transaction, but at least try to end it
+	 * and hope the started data writes can free some space.
+	 */
+	if (current->journal_info &&
+	    current->journal_info != BTRFS_SEND_TRANS_STUB)
+		can_commit = false;
+
 	ret = btrfs_start_delalloc_snapshot(root);
 	if (ret < 0)
 		goto out;
@@ -3534,7 +3549,10 @@ static int try_flush_qgroup(struct btrfs_root *root)
 		goto out;
 	}
 
-	ret = btrfs_commit_transaction(trans);
+	if (can_commit)
+		ret = btrfs_commit_transaction(trans);
+	else
+		ret = btrfs_end_transaction(trans);
 out:
 	clear_bit(BTRFS_ROOT_QGROUP_FLUSHING, &root->state);
 	wake_up(&root->qgroup_flush_wait);