btrfs: check quota status earlier and don't do unnecessary frees

Status of quotas should be the first check in
btrfs_qgroup_account_extent and we can return immediatelly, no need to
do no-op ulist frees.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/qgroup.c

@@ -1945,13 +1945,14 @@ btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans,
 	u64 nr_old_roots = 0;
 	int ret = 0;
 
+	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
+		return 0;
+
 	if (new_roots)
 		nr_new_roots = new_roots->nnodes;
 	if (old_roots)
 		nr_old_roots = old_roots->nnodes;
 
-	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
-		goto out_free;
 	BUG_ON(!fs_info->quota_root);
 
 	trace_btrfs_qgroup_account_extent(fs_info, bytenr, num_bytes,