CIFS: SMBD: Add rdma mount option

Add "rdma" to CIFS mount options to connect to SMB Direct.
Add checks to validate this is used on SMB 3.X dialects.

To connect to SMBDirect, use "mount.cifs -o rdma,vers=3.x".
At the time of this patch, 3.x can be 3.0, 3.02 or 3.1.1.
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Ronnie Sahlberg <lsahlber.redhat.com>

fs/cifs/cifs_debug.c

@@ -176,6 +176,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 				ses->ses_count, ses->serverOS, ses->serverNOS,
 				ses->capabilities, ses->status);
 			}
+			if (server->rdma)
+				seq_printf(m, "RDMA\n\t");
 			seq_printf(m, "TCP status: %d\n\tLocal Users To "
 				   "Server: %d SecMode: 0x%x Req On Wire: %d",
 				   server->tcpStatus, server->srv_count,

fs/cifs/cifsfs.c

@@ -327,6 +327,8 @@ cifs_show_address(struct seq_file *s, struct TCP_Server_Info *server)
 	default:
 		seq_puts(s, "(unknown)");
 	}
+	if (server->rdma)
+		seq_puts(s, ",rdma");
 }
 
 static void

fs/cifs/cifsglob.h

@@ -532,6 +532,7 @@ struct smb_vol {
 	bool nopersistent:1;
 	bool resilient:1; /* noresilient not required since not fored for CA */
 	bool domainauto:1;
+	bool rdma:1;
 	unsigned int rsize;
 	unsigned int wsize;
 	bool sockopt_tcp_nodelay:1;
@@ -648,6 +649,10 @@ struct TCP_Server_Info {
 	bool	sec_kerberos;		/* supports plain Kerberos */
 	bool	sec_mskerberos;		/* supports legacy MS Kerberos */
 	bool	large_buf;		/* is current buffer large? */
+	/* use SMBD connection instead of socket */
+	bool	rdma;
+	/* point to the SMBD connection if RDMA is used instead of socket */
+	struct smbd_connection *smbd_conn;
 	struct delayed_work	echo; /* echo ping workqueue job */
 	char	*smallbuf;	/* pointer to current "small" buffer */
 	char	*bigbuf;	/* pointer to current "big" buffer */

fs/cifs/connect.c

@@ -92,7 +92,7 @@ enum {
 	Opt_multiuser, Opt_sloppy, Opt_nosharesock,
 	Opt_persistent, Opt_nopersistent,
 	Opt_resilient, Opt_noresilient,
-	Opt_domainauto,
+	Opt_domainauto, Opt_rdma,
 
 	/* Mount options which take numeric value */
 	Opt_backupuid, Opt_backupgid, Opt_uid,
@@ -183,6 +183,7 @@ static const match_table_t cifs_mount_option_tokens = {
 	{ Opt_resilient, "resilienthandles"},
 	{ Opt_noresilient, "noresilienthandles"},
 	{ Opt_domainauto, "domainauto"},
+	{ Opt_rdma, "rdma"},
 
 	{ Opt_backupuid, "backupuid=%s" },
 	{ Opt_backupgid, "backupgid=%s" },
@@ -1550,6 +1551,9 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 		case Opt_domainauto:
 			vol->domainauto = true;
 			break;
+		case Opt_rdma:
+			vol->rdma = true;
+			break;
 
 		/* Numeric Values */
 		case Opt_backupuid:
@@ -1951,6 +1955,11 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 		goto cifs_parse_mount_err;
 	}
 
+	if (vol->rdma && vol->vals->protocol_id < SMB30_PROT_ID) {
+		cifs_dbg(VFS, "SMB Direct requires Version >=3.0\n");
+		goto cifs_parse_mount_err;
+	}
+
 #ifndef CONFIG_KEYS
 	/* Muliuser mounts require CONFIG_KEYS support */
 	if (vol->multiuser) {
@@ -2162,6 +2171,9 @@ static int match_server(struct TCP_Server_Info *server, struct smb_vol *vol)
 	if (server->echo_interval != vol->echo_interval * HZ)
 		return 0;
 
+	if (server->rdma != vol->rdma)
+		return 0;
+
 	return 1;
 }
 
@@ -2260,6 +2272,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 	tcp_ses->noblocksnd = volume_info->noblocksnd;
 	tcp_ses->noautotune = volume_info->noautotune;
 	tcp_ses->tcp_nodelay = volume_info->sockopt_tcp_nodelay;
+	tcp_ses->rdma = volume_info->rdma;
 	tcp_ses->in_flight = 0;
 	tcp_ses->credits = 1;
 	init_waitqueue_head(&tcp_ses->response_q);