linux-kernel - Re: [PATCH] NFS: simplify check for freeing cn

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Date:   Sun, 16 Jan 2022 15:47:14 +0000
From:   Trond Myklebust <trondmy@...merspace.com>
To:     "anna.schumaker@...app.com" <anna.schumaker@...app.com>,
        "trix@...hat.com" <trix@...hat.com>
CC:     "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] NFS: simplify check for freeing cn_resp

Hi Tom,

On Sun, 2022-01-16 at 06:43 -0800, trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
> 
> nfs42_files_from_same_server() is called to check if freeing
> cn_resp is required.  Instead of calling a function, check
> the pointer.
> 
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  fs/nfs/nfs4file.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index e79ae4cbc395e..677631ea4cfb3 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -180,7 +180,7 @@ static ssize_t __nfs4_copy_file_range(struct file
> *file_in, loff_t pos_in,
>         ret = nfs42_proc_copy(file_in, pos_in, file_out, pos_out,
> count,
>                                 nss, cnrs, sync);
>  out:
> -       if (!nfs42_files_from_same_server(file_in, file_out))
> +       if (cn_resp)
>                 kfree(cn_resp);

The kernel convention in these circumstances is to just skip the NULL
pointer check, since kfree() does that anyway.

>         if (ret == -EAGAIN)
>                 goto retry;

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@...merspace.com