diff --git a/net/9p/client.c b/net/9p/client.c
index 3b5f3c9..9994676 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -58,6 +58,18 @@
 	{Opt_err, NULL},
 };
 
+inline int p9_is_proto_dotl(struct p9_client *clnt)
+{
+	return (clnt->proto_version == p9_proto_2010L);
+}
+EXPORT_SYMBOL(p9_is_proto_dotl);
+
+inline int p9_is_proto_dotu(struct p9_client *clnt)
+{
+	return (clnt->proto_version == p9_proto_2000u);
+}
+EXPORT_SYMBOL(p9_is_proto_dotu);
+
 /* Interpret mount option for protocol version */
 static unsigned char get_protocol_version(const substring_t *name)
 {
@@ -97,7 +109,7 @@
 	int option;
 	int ret = 0;
 
-	clnt->dotu = 1;
+	clnt->proto_version = p9_proto_2000u;
 	clnt->msize = 8192;
 
 	if (!opts)
@@ -140,7 +152,7 @@
 			}
 			break;
 		case Opt_legacy:
-			clnt->dotu = 0;
+			clnt->proto_version = p9_proto_legacy;
 			break;
 		case Opt_version:
 			ret = get_protocol_version(&args[0]);
@@ -438,14 +450,15 @@
 		int ecode;
 		char *ename;
 
-		err = p9pdu_readf(req->rc, c->dotu, "s?d", &ename, &ecode);
+		err = p9pdu_readf(req->rc, c->proto_version, "s?d",
+							&ename, &ecode);
 		if (err) {
 			P9_DPRINTK(P9_DEBUG_ERROR, "couldn't parse error%d\n",
 									err);
 			return err;
 		}
 
-		if (c->dotu)
+		if (p9_is_proto_dotu(c))
 			err = -ecode;
 
 		if (!err || !IS_ERR_VALUE(err))
@@ -543,7 +556,7 @@
 	/* marshall the data */
 	p9pdu_prepare(req->tc, tag, type);
 	va_start(ap, fmt);
-	err = p9pdu_vwritef(req->tc, c->dotu, fmt, ap);
+	err = p9pdu_vwritef(req->tc, c->proto_version, fmt, ap);
 	va_end(ap);
 	p9pdu_finalize(req->tc);
 
@@ -655,14 +668,14 @@
 	char *version;
 	int msize;
 
-	P9_DPRINTK(P9_DEBUG_9P, ">>> TVERSION msize %d extended %d\n",
-							c->msize, c->dotu);
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
+						c->msize, c->proto_version);
 	req = p9_client_rpc(c, P9_TVERSION, "ds", c->msize,
-				c->dotu ? "9P2000.u" : "9P2000");
+				p9_is_proto_dotu(c) ? "9P2000.u" : "9P2000");
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	err = p9pdu_readf(req->rc, c->dotu, "ds", &msize, &version);
+	err = p9pdu_readf(req->rc, c->proto_version, "ds", &msize, &version);
 	if (err) {
 		P9_DPRINTK(P9_DEBUG_9P, "version error %d\n", err);
 		p9pdu_dump(1, req->rc);
@@ -670,10 +683,10 @@
 	}
 
 	P9_DPRINTK(P9_DEBUG_9P, "<<< RVERSION msize %d %s\n", msize, version);
-	if (!memcmp(version, "9P2000.u", 8))
-		c->dotu = 1;
-	else if (!memcmp(version, "9P2000", 6))
-		c->dotu = 0;
+	if (!strncmp(version, "9P2000.u", 8))
+		c->proto_version = p9_proto_2000u;
+	else if (!strncmp(version, "9P2000", 6))
+		c->proto_version = p9_proto_legacy;
 	else {
 		err = -EREMOTEIO;
 		goto error;
@@ -728,8 +741,8 @@
 		goto put_trans;
 	}
 
-	P9_DPRINTK(P9_DEBUG_MUX, "clnt %p trans %p msize %d dotu %d\n",
-		clnt, clnt->trans_mod, clnt->msize, clnt->dotu);
+	P9_DPRINTK(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n",
+		clnt, clnt->trans_mod, clnt->msize, clnt->proto_version);
 
 	err = clnt->trans_mod->create(clnt, dev_name, options);
 	if (err)
@@ -812,7 +825,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "Q", &qid);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "Q", &qid);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		p9_free_req(clnt, req);
@@ -861,7 +874,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "Q", &qid);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "Q", &qid);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		p9_free_req(clnt, req);
@@ -919,7 +932,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "R", &nwqids, &wqids);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "R", &nwqids, &wqids);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		p9_free_req(clnt, req);
@@ -980,7 +993,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "Qd", &qid, &iounit);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "Qd", &qid, &iounit);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		goto free_and_error;
@@ -1025,7 +1038,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "Qd", &qid, &iounit);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "Qd", &qid, &iounit);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		goto free_and_error;
@@ -1126,7 +1139,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "D", &count, &dataptr);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "D", &count, &dataptr);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		goto free_and_error;
@@ -1187,7 +1200,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "d", &count);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "d", &count);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		goto free_and_error;
@@ -1227,7 +1240,7 @@
 		goto error;
 	}
 
-	err = p9pdu_readf(req->rc, clnt->dotu, "wS", &ignored, ret);
+	err = p9pdu_readf(req->rc, clnt->proto_version, "wS", &ignored, ret);
 	if (err) {
 		p9pdu_dump(1, req->rc);
 		p9_free_req(clnt, req);
@@ -1254,7 +1267,7 @@
 }
 EXPORT_SYMBOL(p9_client_stat);
 
-static int p9_client_statsize(struct p9_wstat *wst, int optional)
+static int p9_client_statsize(struct p9_wstat *wst, int proto_version)
 {
 	int ret;
 
@@ -1273,7 +1286,7 @@
 	if (wst->muid)
 		ret += strlen(wst->muid);
 
-	if (optional) {
+	if (proto_version == p9_proto_2000u) {
 		ret += 2+4+4+4;	/* extension[s] n_uid[4] n_gid[4] n_muid[4] */
 		if (wst->extension)
 			ret += strlen(wst->extension);
@@ -1290,7 +1303,7 @@
 
 	err = 0;
 	clnt = fid->clnt;
-	wst->size = p9_client_statsize(wst, clnt->dotu);
+	wst->size = p9_client_statsize(wst, clnt->proto_version);
 	P9_DPRINTK(P9_DEBUG_9P, ">>> TWSTAT fid %d\n", fid->fid);
 	P9_DPRINTK(P9_DEBUG_9P,
 		"     sz=%x type=%x dev=%x qid=%x.%llx.%x\n"
diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index fc70147..94f5a8f 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -52,7 +52,7 @@
 #endif
 
 static int
-p9pdu_writef(struct p9_fcall *pdu, int optional, const char *fmt, ...);
+p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...);
 
 #ifdef CONFIG_NET_9P_DEBUG
 void
@@ -144,7 +144,8 @@
 */
 
 static int
-p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
+p9pdu_vreadf(struct p9_fcall *pdu, int proto_version, const char *fmt,
+	va_list ap)
 {
 	const char *ptr;
 	int errcode = 0;
@@ -194,7 +195,8 @@
 				int16_t len;
 				int size;
 
-				errcode = p9pdu_readf(pdu, optional, "w", &len);
+				errcode = p9pdu_readf(pdu, proto_version,
+								"w", &len);
 				if (errcode)
 					break;
 
@@ -217,7 +219,7 @@
 				struct p9_qid *qid =
 				    va_arg(ap, struct p9_qid *);
 
-				errcode = p9pdu_readf(pdu, optional, "bdq",
+				errcode = p9pdu_readf(pdu, proto_version, "bdq",
 						      &qid->type, &qid->version,
 						      &qid->path);
 			}
@@ -230,7 +232,7 @@
 				stbuf->n_uid = stbuf->n_gid = stbuf->n_muid =
 									-1;
 				errcode =
-				    p9pdu_readf(pdu, optional,
+				    p9pdu_readf(pdu, proto_version,
 						"wwdQdddqssss?sddd",
 						&stbuf->size, &stbuf->type,
 						&stbuf->dev, &stbuf->qid,
@@ -250,7 +252,7 @@
 				void **data = va_arg(ap, void **);
 
 				errcode =
-				    p9pdu_readf(pdu, optional, "d", count);
+				    p9pdu_readf(pdu, proto_version, "d", count);
 				if (!errcode) {
 					*count =
 					    MIN(*count,
@@ -263,8 +265,8 @@
 				int16_t *nwname = va_arg(ap, int16_t *);
 				char ***wnames = va_arg(ap, char ***);
 
-				errcode =
-				    p9pdu_readf(pdu, optional, "w", nwname);
+				errcode = p9pdu_readf(pdu, proto_version,
+								"w", nwname);
 				if (!errcode) {
 					*wnames =
 					    kmalloc(sizeof(char *) * *nwname,
@@ -278,7 +280,8 @@
 
 					for (i = 0; i < *nwname; i++) {
 						errcode =
-						    p9pdu_readf(pdu, optional,
+						    p9pdu_readf(pdu,
+								proto_version,
 								"s",
 								&(*wnames)[i]);
 						if (errcode)
@@ -306,7 +309,7 @@
 				*wqids = NULL;
 
 				errcode =
-				    p9pdu_readf(pdu, optional, "w", nwqid);
+				    p9pdu_readf(pdu, proto_version, "w", nwqid);
 				if (!errcode) {
 					*wqids =
 					    kmalloc(*nwqid *
@@ -321,7 +324,8 @@
 
 					for (i = 0; i < *nwqid; i++) {
 						errcode =
-						    p9pdu_readf(pdu, optional,
+						    p9pdu_readf(pdu,
+								proto_version,
 								"Q",
 								&(*wqids)[i]);
 						if (errcode)
@@ -336,7 +340,7 @@
 			}
 			break;
 		case '?':
-			if (!optional)
+			if (proto_version != p9_proto_2000u)
 				return 0;
 			break;
 		default:
@@ -352,7 +356,8 @@
 }
 
 int
-p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
+p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
+	va_list ap)
 {
 	const char *ptr;
 	int errcode = 0;
@@ -389,7 +394,8 @@
 				if (sptr)
 					len = MIN(strlen(sptr), USHORT_MAX);
 
-				errcode = p9pdu_writef(pdu, optional, "w", len);
+				errcode = p9pdu_writef(pdu, proto_version,
+								"w", len);
 				if (!errcode && pdu_write(pdu, sptr, len))
 					errcode = -EFAULT;
 			}
@@ -398,7 +404,7 @@
 				const struct p9_qid *qid =
 				    va_arg(ap, const struct p9_qid *);
 				errcode =
-				    p9pdu_writef(pdu, optional, "bdq",
+				    p9pdu_writef(pdu, proto_version, "bdq",
 						 qid->type, qid->version,
 						 qid->path);
 			} break;
@@ -406,7 +412,7 @@
 				const struct p9_wstat *stbuf =
 				    va_arg(ap, const struct p9_wstat *);
 				errcode =
-				    p9pdu_writef(pdu, optional,
+				    p9pdu_writef(pdu, proto_version,
 						 "wwdQdddqssss?sddd",
 						 stbuf->size, stbuf->type,
 						 stbuf->dev, &stbuf->qid,
@@ -421,8 +427,8 @@
 				int32_t count = va_arg(ap, int32_t);
 				const void *data = va_arg(ap, const void *);
 
-				errcode =
-				    p9pdu_writef(pdu, optional, "d", count);
+				errcode = p9pdu_writef(pdu, proto_version, "d",
+									count);
 				if (!errcode && pdu_write(pdu, data, count))
 					errcode = -EFAULT;
 			}
@@ -431,8 +437,8 @@
 				int32_t count = va_arg(ap, int32_t);
 				const char __user *udata =
 						va_arg(ap, const void __user *);
-				errcode =
-				    p9pdu_writef(pdu, optional, "d", count);
+				errcode = p9pdu_writef(pdu, proto_version, "d",
+									count);
 				if (!errcode && pdu_write_u(pdu, udata, count))
 					errcode = -EFAULT;
 			}
@@ -441,14 +447,15 @@
 				int16_t nwname = va_arg(ap, int);
 				const char **wnames = va_arg(ap, const char **);
 
-				errcode =
-				    p9pdu_writef(pdu, optional, "w", nwname);
+				errcode = p9pdu_writef(pdu, proto_version, "w",
+									nwname);
 				if (!errcode) {
 					int i;
 
 					for (i = 0; i < nwname; i++) {
 						errcode =
-						    p9pdu_writef(pdu, optional,
+						    p9pdu_writef(pdu,
+								proto_version,
 								 "s",
 								 wnames[i]);
 						if (errcode)
@@ -462,14 +469,15 @@
 				struct p9_qid *wqids =
 				    va_arg(ap, struct p9_qid *);
 
-				errcode =
-				    p9pdu_writef(pdu, optional, "w", nwqid);
+				errcode = p9pdu_writef(pdu, proto_version, "w",
+									nwqid);
 				if (!errcode) {
 					int i;
 
 					for (i = 0; i < nwqid; i++) {
 						errcode =
-						    p9pdu_writef(pdu, optional,
+						    p9pdu_writef(pdu,
+								proto_version,
 								 "Q",
 								 &wqids[i]);
 						if (errcode)
@@ -479,7 +487,7 @@
 			}
 			break;
 		case '?':
-			if (!optional)
+			if (proto_version != p9_proto_2000u)
 				return 0;
 			break;
 		default:
@@ -494,32 +502,32 @@
 	return errcode;
 }
 
-int p9pdu_readf(struct p9_fcall *pdu, int optional, const char *fmt, ...)
+int p9pdu_readf(struct p9_fcall *pdu, int proto_version, const char *fmt, ...)
 {
 	va_list ap;
 	int ret;
 
 	va_start(ap, fmt);
-	ret = p9pdu_vreadf(pdu, optional, fmt, ap);
+	ret = p9pdu_vreadf(pdu, proto_version, fmt, ap);
 	va_end(ap);
 
 	return ret;
 }
 
 static int
-p9pdu_writef(struct p9_fcall *pdu, int optional, const char *fmt, ...)
+p9pdu_writef(struct p9_fcall *pdu, int proto_version, const char *fmt, ...)
 {
 	va_list ap;
 	int ret;
 
 	va_start(ap, fmt);
-	ret = p9pdu_vwritef(pdu, optional, fmt, ap);
+	ret = p9pdu_vwritef(pdu, proto_version, fmt, ap);
 	va_end(ap);
 
 	return ret;
 }
 
-int p9stat_read(char *buf, int len, struct p9_wstat *st, int dotu)
+int p9stat_read(char *buf, int len, struct p9_wstat *st, int proto_version)
 {
 	struct p9_fcall fake_pdu;
 	int ret;
@@ -529,7 +537,7 @@
 	fake_pdu.sdata = buf;
 	fake_pdu.offset = 0;
 
-	ret = p9pdu_readf(&fake_pdu, dotu, "S", st);
+	ret = p9pdu_readf(&fake_pdu, proto_version, "S", st);
 	if (ret) {
 		P9_DPRINTK(P9_DEBUG_9P, "<<< p9stat_read failed: %d\n", ret);
 		p9pdu_dump(1, &fake_pdu);
diff --git a/net/9p/protocol.h b/net/9p/protocol.h
index ccde462..2431c0f 100644
--- a/net/9p/protocol.h
+++ b/net/9p/protocol.h
@@ -25,9 +25,9 @@
  *
  */
 
-int
-p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap);
-int p9pdu_readf(struct p9_fcall *pdu, int optional, const char *fmt, ...);
+int p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
+								va_list ap);
+int p9pdu_readf(struct p9_fcall *pdu, int proto_version, const char *fmt, ...);
 int p9pdu_prepare(struct p9_fcall *pdu, int16_t tag, int8_t type);
 int p9pdu_finalize(struct p9_fcall *pdu);
 void p9pdu_dump(int, struct p9_fcall *);