btrfs: always clear PERTRANS metadata during commit

It is possible to clear a root's IN_TRANS tag from the radix tree, but
not clear its PERTRANS, if there is some error in between. Eliminate
that possibility by moving the free up to where we clear the tag.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/transaction.c

@@ -1494,6 +1494,7 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
 			radix_tree_tag_clear(&fs_info->fs_roots_radix,
 					(unsigned long)root->root_key.objectid,
 					BTRFS_ROOT_TRANS_TAG);
+			btrfs_qgroup_free_meta_all_pertrans(root);
 			spin_unlock(&fs_info->fs_roots_radix_lock);
 
 			btrfs_free_log(trans, root);
@@ -1518,7 +1519,6 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
 			if (ret2)
 				return ret2;
 			spin_lock(&fs_info->fs_roots_radix_lock);
-			btrfs_qgroup_free_meta_all_pertrans(root);
 		}
 	}
 	spin_unlock(&fs_info->fs_roots_radix_lock);