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From:   Steve French <smfrench@gmail.com>
Date:   Mon, 23 Apr 2018 10:34:55 -0500
Message-ID: <CAH2r5msFfBuTb5AF7inHVnA0B=miTc-S3kw_cKV_SfmeEd0_cw@mail.gmail.com>
Subject: Re: [Patch v2 4/6] cifs: smbd: Don't use RDMA read/write when signing
 is used
To:     Long Li <longli@microsoft.com>
Cc:     Steve French <sfrench@samba.org>,
        CIFS <linux-cifs@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-rdma@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org
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merged into cifs-2.6.git for-next

On Tue, Apr 17, 2018 at 2:17 PM, Long Li <longli@linuxonhyperv.com> wrote:
> From: Long Li <longli@microsoft.com>
>
> SMB server will not sign data transferred through RDMA read/write. When
> signing is used, it's a good idea to have all the data signed.
>
> In this case, use RDMA send/recv for all data transfers. This will degrade
> performance as this is not generally configured in RDMA environemnt. So
> warn the user on signing and RDMA send/recv.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> Cc: stable@vger.kernel.org
> ---
>  fs/cifs/cifssmb.c |  3 +++
>  fs/cifs/smb2ops.c | 18 ++++++++++++++----
>  fs/cifs/smb2pdu.c |  4 ++--
>  3 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index 6d3e40d..1529a08 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -455,6 +455,9 @@ cifs_enable_signing(struct TCP_Server_Info *server, bool mnt_sign_required)
>                 server->sign = true;
>         }
>
> +       if (cifs_rdma_enabled(server) && server->sign)
> +               cifs_dbg(VFS, "Signing is enabled, and RDMA read/write will be disabled");
> +
>         return 0;
>  }
>
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index 38ebf3f..b76b858 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -252,9 +252,14 @@ smb2_negotiate_wsize(struct cifs_tcon *tcon, struct smb_vol *volume_info)
>         wsize = volume_info->wsize ? volume_info->wsize : CIFS_DEFAULT_IOSIZE;
>         wsize = min_t(unsigned int, wsize, server->max_write);
>  #ifdef CONFIG_CIFS_SMB_DIRECT
> -       if (server->rdma)
> -               wsize = min_t(unsigned int,
> +       if (server->rdma) {
> +               if (server->sign)
> +                       wsize = min_t(unsigned int,
> +                               wsize, server->smbd_conn->max_fragmented_send_size);
> +               else
> +                       wsize = min_t(unsigned int,
>                                 wsize, server->smbd_conn->max_readwrite_size);
> +       }
>  #endif
>         if (!(server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
>                 wsize = min_t(unsigned int, wsize, SMB2_MAX_BUFFER_SIZE);
> @@ -272,9 +277,14 @@ smb2_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *volume_info)
>         rsize = volume_info->rsize ? volume_info->rsize : CIFS_DEFAULT_IOSIZE;
>         rsize = min_t(unsigned int, rsize, server->max_read);
>  #ifdef CONFIG_CIFS_SMB_DIRECT
> -       if (server->rdma)
> -               rsize = min_t(unsigned int,
> +       if (server->rdma) {
> +               if (server->sign)
> +                       rsize = min_t(unsigned int,
> +                               rsize, server->smbd_conn->max_fragmented_recv_size);
> +               else
> +                       rsize = min_t(unsigned int,
>                                 rsize, server->smbd_conn->max_readwrite_size);
> +       }
>  #endif
>
>         if (!(server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 41625e4..33f612f 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -2595,7 +2595,7 @@ smb2_new_read_req(void **buf, unsigned int *total_len,
>          * If we want to do a RDMA write, fill in and append
>          * smbd_buffer_descriptor_v1 to the end of read request
>          */
> -       if (server->rdma && rdata &&
> +       if (server->rdma && rdata && !server->sign &&
>                 rdata->bytes >= server->smbd_conn->rdma_readwrite_threshold) {
>
>                 struct smbd_buffer_descriptor_v1 *v1;
> @@ -2973,7 +2973,7 @@ smb2_async_writev(struct cifs_writedata *wdata,
>          * If we want to do a server RDMA read, fill in and append
>          * smbd_buffer_descriptor_v1 to the end of write request
>          */
> -       if (server->rdma && wdata->bytes >=
> +       if (server->rdma && !server->sign && wdata->bytes >=
>                 server->smbd_conn->rdma_readwrite_threshold) {
>
>                 struct smbd_buffer_descriptor_v1 *v1;
> --
> 2.7.4
>
> --
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-- 
Thanks,

Steve