CIFS: SMBD: Upper layer connects to SMBDirect session

When "rdma" is specified in the mount option, make CIFS connect to
SMB Direct.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>

fs/cifs/connect.c

@@ -44,7 +44,6 @@
 #include <net/ipv6.h>
 #include <linux/parser.h>
 #include <linux/bvec.h>
-
 #include "cifspdu.h"
 #include "cifsglob.h"
 #include "cifsproto.h"
@@ -56,6 +55,7 @@
 #include "rfc1002pdu.h"
 #include "fscache.h"
 #include "smb2proto.h"
+#include "smbdirect.h"
 
 #define CIFS_PORT 445
 #define RFC1001_PORT 139
@@ -2310,13 +2310,29 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 		tcp_ses->echo_interval = volume_info->echo_interval * HZ;
 	else
 		tcp_ses->echo_interval = SMB_ECHO_INTERVAL_DEFAULT * HZ;
-
+	if (tcp_ses->rdma) {
+#ifndef CONFIG_CIFS_SMB_DIRECT
+		cifs_dbg(VFS, "CONFIG_CIFS_SMB_DIRECT is not enabled\n");
+		rc = -ENOENT;
+		goto out_err_crypto_release;
+#endif
+		tcp_ses->smbd_conn = smbd_get_connection(
+			tcp_ses, (struct sockaddr *)&volume_info->dstaddr);
+		if (tcp_ses->smbd_conn) {
+			cifs_dbg(VFS, "RDMA transport established\n");
+			rc = 0;
+			goto smbd_connected;
+		} else {
+			rc = -ENOENT;
+			goto out_err_crypto_release;
+		}
+	}
 	rc = ip_connect(tcp_ses);
 	if (rc < 0) {
 		cifs_dbg(VFS, "Error connecting to socket. Aborting operation.\n");
 		goto out_err_crypto_release;
 	}
-
+smbd_connected:
 	/*
 	 * since we're in a cifs function already, we know that
 	 * this will succeed. No need for try_module_get().