Re: [PATCH] Fix mountpoint reference leakage in linkat

[Al Viro <viro@ZenIV.linux.org.uk>]

On Fri, Jan 31, 2014 at 03:41:58PM -0500, Oleg Drokin wrote:
> Recent changes to retry on ESTALE in linkat
> (commit 442e31ca5a49e398351b2954b51f578353fdf210)
> introduced a mountpoint reference leak and a small memory
> leak in case a filesystem link operation returns ESTALE
> which is pretty normal for distributed filesystems like
> lustre, nfs and so on.
> Free old_path in such a case.
> 
> Signed-off-by: Oleg Drokin: <green@linuxhacker.ru>
> ---
>  fs/namei.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index bcb838e..e620937 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3931,6 +3931,7 @@ out_dput:
>  			goto retry;
>  	}
>  	if (retry_estale(error, how)) {
> +		path_put(&old_path);
>  		how |= LOOKUP_REVAL;
>  		goto retry;
>  	}

Umm...  That obviously can't be right - we have another goto retry
in the same situation (see in your diff context).  I agree that
we have a leak there, but you've fixed only a half of it.