linux-kernel - [PATCH 4/6] cifs: smbd: Don't use RDMA read/write when signing is used

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Message-Id: <20180417004918.29213-4-longli@linuxonhyperv.com>
Date:   Mon, 16 Apr 2018 17:49:16 -0700
From:   Long Li <longli@...uxonhyperv.com>
To:     Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, stable@...r.kernel.org
Cc:     Long Li <longli@...rosoft.com>
Subject: [PATCH 4/6] cifs: smbd: Don't use RDMA read/write when signing is used

From: Long Li <longli@...rosoft.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@...rosoft.com>
---
 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 abbefe2..6759035 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2596,7 +2596,7 @@ 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;
@@ -2974,7 +2974,7 @@ 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