diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 1b9f4f16d124045ccf90fa3c4654a9f2538eebad..c46ea2ecf1881772d8d85dda78493d483e52d10b 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -579,22 +579,30 @@ bool btrfs_check_quota_leak(struct btrfs_fs_info *fs_info)
 
 /*
  * This is called from close_ctree() or open_ctree() or btrfs_quota_disable(),
- * first two are in single-threaded paths.And for the third one, we have set
- * quota_root to be null with qgroup_lock held before, so it is safe to clean
- * up the in-memory structures without qgroup_lock held.
+ * first two are in single-threaded paths.
  */
 void btrfs_free_qgroup_config(struct btrfs_fs_info *fs_info)
 {
 	struct rb_node *n;
 	struct btrfs_qgroup *qgroup;
 
+	/*
+	 * btrfs_quota_disable() can be called concurrently with
+	 * btrfs_qgroup_rescan() -> qgroup_rescan_zero_tracking(), so take the
+	 * lock.
+	 */
+	spin_lock(&fs_info->qgroup_lock);
 	while ((n = rb_first(&fs_info->qgroup_tree))) {
 		qgroup = rb_entry(n, struct btrfs_qgroup, node);
 		rb_erase(n, &fs_info->qgroup_tree);
 		__del_qgroup_rb(fs_info, qgroup);
+		spin_unlock(&fs_info->qgroup_lock);
 		btrfs_sysfs_del_one_qgroup(fs_info, qgroup);
 		kfree(qgroup);
+		spin_lock(&fs_info->qgroup_lock);
 	}
+	spin_unlock(&fs_info->qgroup_lock);
+
 	/*
 	 * We call btrfs_free_qgroup_config() when unmounting
 	 * filesystem and disabling quota, so we set qgroup_ulist
@@ -3616,12 +3624,21 @@ btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
 	qgroup_rescan_zero_tracking(fs_info);
 
 	mutex_lock(&fs_info->qgroup_rescan_lock);
-	fs_info->qgroup_rescan_running = true;
-	btrfs_queue_work(fs_info->qgroup_rescan_workers,
-			 &fs_info->qgroup_rescan_work);
+	/*
+	 * The rescan worker is only for full accounting qgroups, check if it's
+	 * enabled as it is pointless to queue it otherwise. A concurrent quota
+	 * disable may also have just cleared BTRFS_FS_QUOTA_ENABLED.
+	 */
+	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
+		fs_info->qgroup_rescan_running = true;
+		btrfs_queue_work(fs_info->qgroup_rescan_workers,
+				 &fs_info->qgroup_rescan_work);
+	} else {
+		ret = -ENOTCONN;
+	}
 	mutex_unlock(&fs_info->qgroup_rescan_lock);
 
-	return 0;
+	return ret;
 }
 
 int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,