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From:   Olga Kornievskaia <olga.kornievskaia@gmail.com>
Date:   Mon, 8 Mar 2021 13:35:50 -0500
Message-ID: <CAN-5tyHr6VEfBubU_gBRyCfzkAzGkwiBvO-0S9Kbnpj_LnVdQQ@mail.gmail.com>
Subject: Re: [PATCH] NFSv4.2: destination file needs to be released after
 inter-server copy is done.
To:     Dai Ngo <dai.ngo@oracle.com>
Cc:     Trond Myklebust <trondmy@hammerspace.com>,
        linux-nfs <linux-nfs@vger.kernel.org>
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On Tue, Mar 2, 2021 at 2:47 PM Dai Ngo <dai.ngo@oracle.com> wrote:
>
> This patch is to fix the resource leak problem of the source file
> when doing inter-server copy. The fix is to close and release the
> file in __nfs42_ssc_close after the copy is done.
>
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfs/nfs4file.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index 57b3821d975a..20163fe702a7 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -405,6 +405,12 @@ static void __nfs42_ssc_close(struct file *filep)
>         struct nfs_open_context *ctx = nfs_file_open_context(filep);
>
>         ctx->state->flags = 0;
> +
> +       if (!filep)
> +               return;
> +       get_file(filep);
> +       filp_close(filep, NULL);
> +       fput(filep);
>  }

I don't understand this logic. There is no reason to call
filp_close()? All this would be done by doing a fput(). Also fput()
would drop a reference on the mount point. So we are doing this then
we can't call that extra disconnect that was added by another patch.
Anyway I don't see why there is any reason to call anything but the
fput(), I'm not sure why __nfs42_ssc_close() is a better function and
doesn't lead to the "use_after_free".

>
>  static const struct nfs4_ssc_client_ops nfs4_ssc_clnt_ops_tbl = {
> --
> 2.9.5
>