Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
  fs/9p: Add hardlink support to .u extension
  9P2010.L handshake: .L protocol negotiation
  9P2010.L handshake: Remove "dotu" variable
  9P2010.L handshake: Add mount option
  9P2010.L handshake: Add VFS flags
  net/9p: Handle mount errors correctly.
  net/9p: Remove MAX_9P_CHAN limit
  net/9p: Add multi channel support.

12 files changed, 238 insertions, 144 deletions

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index 14d944204571..08b2eb157048 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -151,7 +151,7 @@ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
 			if (access == V9FS_ACCESS_SINGLE)
 				return ERR_PTR(-EPERM);
 
-			if (v9fs_extended(v9ses))
+			if (v9fs_proto_dotu(v9ses))
 				uname = NULL;
 			else
 				uname = v9ses->uname;
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 7d6c2139891d..6c7f6a251115 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -241,7 +241,7 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 	list_add(&v9ses->slist, &v9fs_sessionlist);
 	spin_unlock(&v9fs_sessionlist_lock);
 
-	v9ses->flags = V9FS_EXTENDED | V9FS_ACCESS_USER;
+	v9ses->flags = V9FS_PROTO_2000U | V9FS_ACCESS_USER;
 	strcpy(v9ses->uname, V9FS_DEFUSER);
 	strcpy(v9ses->aname, V9FS_DEFANAME);
 	v9ses->uid = ~0;
@@ -262,13 +262,13 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 		goto error;
 	}
 
-	if (!v9ses->clnt->dotu)
-		v9ses->flags &= ~V9FS_EXTENDED;
+	if (!p9_is_proto_dotu(v9ses->clnt))
+		v9ses->flags &= ~V9FS_PROTO_2000U;
 
 	v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;
 
 	/* for legacy mode, fall back to V9FS_ACCESS_ANY */
-	if (!v9fs_extended(v9ses) &&
+	if (!v9fs_proto_dotu(v9ses) &&
 		((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
 
 		v9ses->flags &= ~V9FS_ACCESS_MASK;
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 019f4ccb70c1..79000bf62491 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -23,7 +23,8 @@
 
 /**
  * enum p9_session_flags - option flags for each 9P session
- * @V9FS_EXTENDED: whether or not to use 9P2000.u extensions
+ * @V9FS_PROTO_2000U: whether or not to use 9P2000.u extensions
+ * @V9FS_PROTO_2010L: whether or not to use 9P2010.l extensions
  * @V9FS_ACCESS_SINGLE: only the mounting user can access the hierarchy
  * @V9FS_ACCESS_USER: a new attach will be issued for every user (default)
  * @V9FS_ACCESS_ANY: use a single attach for all users
@@ -32,11 +33,12 @@
  * Session flags reflect options selected by users at mount time
  */
 enum p9_session_flags {
-	V9FS_EXTENDED		= 0x01,
-	V9FS_ACCESS_SINGLE	= 0x02,
-	V9FS_ACCESS_USER	= 0x04,
-	V9FS_ACCESS_ANY		= 0x06,
-	V9FS_ACCESS_MASK	= 0x06,
+	V9FS_PROTO_2000U	= 0x01,
+	V9FS_PROTO_2010L	= 0x02,
+	V9FS_ACCESS_SINGLE	= 0x04,
+	V9FS_ACCESS_USER	= 0x08,
+	V9FS_ACCESS_ANY		= 0x0C,
+	V9FS_ACCESS_MASK	= 0x0C,
 };
 
 /* possible values of ->cache */
@@ -121,7 +123,12 @@ static inline struct v9fs_session_info *v9fs_inode2v9ses(struct inode *inode)
 	return (inode->i_sb->s_fs_info);
 }
 
-static inline int v9fs_extended(struct v9fs_session_info *v9ses)
+static inline int v9fs_proto_dotu(struct v9fs_session_info *v9ses)
 {
-	return v9ses->flags & V9FS_EXTENDED;
+	return v9ses->flags & V9FS_PROTO_2000U;
+}
+
+static inline int v9fs_proto_dotl(struct v9fs_session_info *v9ses)
+{
+	return v9ses->flags & V9FS_PROTO_2010L;
 }
diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 15cce53bf61e..6580aa449541 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -135,7 +135,7 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		while (rdir->head < rdir->tail) {
 			err = p9stat_read(rdir->buf + rdir->head,
 						buflen - rdir->head, &st,
-						fid->clnt->dotu);
+						fid->clnt->proto_version);
 			if (err) {
 				P9_DPRINTK(P9_DEBUG_VFS, "returned %d\n", err);
 				err = -EIO;
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 74a0461a9ac0..36122683fae8 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -61,7 +61,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
 	P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p \n", inode, file);
 	v9ses = v9fs_inode2v9ses(inode);
-	omode = v9fs_uflags2omode(file->f_flags, v9fs_extended(v9ses));
+	omode = v9fs_uflags2omode(file->f_flags, v9fs_proto_dotu(v9ses));
 	fid = file->private_data;
 	if (!fid) {
 		fid = v9fs_fid_clone(file->f_path.dentry);
@@ -77,7 +77,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 			i_size_write(inode, 0);
 			inode->i_blocks = 0;
 		}
-		if ((file->f_flags & O_APPEND) && (!v9fs_extended(v9ses)))
+		if ((file->f_flags & O_APPEND) && (!v9fs_proto_dotu(v9ses)))
 			generic_file_llseek(file, 0, SEEK_END);
 	}
 
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index a407fa3388c0..5fe45d692c9f 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -60,7 +60,7 @@ static int unixmode2p9mode(struct v9fs_session_info *v9ses, int mode)
 	res = mode & 0777;
 	if (S_ISDIR(mode))
 		res |= P9_DMDIR;
-	if (v9fs_extended(v9ses)) {
+	if (v9fs_proto_dotu(v9ses)) {
 		if (S_ISLNK(mode))
 			res |= P9_DMSYMLINK;
 		if (v9ses->nodev == 0) {
@@ -102,21 +102,21 @@ static int p9mode2unixmode(struct v9fs_session_info *v9ses, int mode)
 
 	if ((mode & P9_DMDIR) == P9_DMDIR)
 		res |= S_IFDIR;
-	else if ((mode & P9_DMSYMLINK) && (v9fs_extended(v9ses)))
+	else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
 		res |= S_IFLNK;
-	else if ((mode & P9_DMSOCKET) && (v9fs_extended(v9ses))
+	else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
 		 && (v9ses->nodev == 0))
 		res |= S_IFSOCK;
-	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_extended(v9ses))
+	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
 		 && (v9ses->nodev == 0))
 		res |= S_IFIFO;
-	else if ((mode & P9_DMDEVICE) && (v9fs_extended(v9ses))
+	else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
 		 && (v9ses->nodev == 0))
 		res |= S_IFBLK;
 	else
 		res |= S_IFREG;
 
-	if (v9fs_extended(v9ses)) {
+	if (v9fs_proto_dotu(v9ses)) {
 		if ((mode & P9_DMSETUID) == P9_DMSETUID)
 			res |= S_ISUID;
 
@@ -265,7 +265,7 @@ struct inode *v9fs_get_inode(struct super_block *sb, int mode)
 	case S_IFBLK:
 	case S_IFCHR:
 	case S_IFSOCK:
-		if (!v9fs_extended(v9ses)) {
+		if (!v9fs_proto_dotu(v9ses)) {
 			P9_DPRINTK(P9_DEBUG_ERROR,
 				   "special files without extended mode\n");
 			err = -EINVAL;
@@ -278,7 +278,7 @@ struct inode *v9fs_get_inode(struct super_block *sb, int mode)
 		inode->i_fop = &v9fs_file_operations;
 		break;
 	case S_IFLNK:
-		if (!v9fs_extended(v9ses)) {
+		if (!v9fs_proto_dotu(v9ses)) {
 			P9_DPRINTK(P9_DEBUG_ERROR,
 				   "extended modes used w/o 9P2000.u\n");
 			err = -EINVAL;
@@ -288,7 +288,7 @@ struct inode *v9fs_get_inode(struct super_block *sb, int mode)
 		break;
 	case S_IFDIR:
 		inc_nlink(inode);
-		if (v9fs_extended(v9ses))
+		if (v9fs_proto_dotu(v9ses))
 			inode->i_op = &v9fs_dir_inode_operations_ext;
 		else
 			inode->i_op = &v9fs_dir_inode_operations;
@@ -575,7 +575,8 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, int mode,
 		flags = O_RDWR;
 
 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
-				v9fs_uflags2omode(flags, v9fs_extended(v9ses)));
+				v9fs_uflags2omode(flags,
+						v9fs_proto_dotu(v9ses)));
 	if (IS_ERR(fid)) {
 		err = PTR_ERR(fid);
 		fid = NULL;
@@ -858,7 +859,7 @@ static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 	if (iattr->ia_valid & ATTR_SIZE)
 		wstat.length = iattr->ia_size;
 
-	if (v9fs_extended(v9ses)) {
+	if (v9fs_proto_dotu(v9ses)) {
 		if (iattr->ia_valid & ATTR_UID)
 			wstat.n_uid = iattr->ia_uid;
 
@@ -886,6 +887,8 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
 	struct super_block *sb)
 {
 	char ext[32];
+	char tag_name[14];
+	unsigned int i_nlink;
 	struct v9fs_session_info *v9ses = sb->s_fs_info;
 
 	inode->i_nlink = 1;
@@ -897,11 +900,26 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
 	inode->i_uid = v9ses->dfltuid;
 	inode->i_gid = v9ses->dfltgid;
 
-	if (v9fs_extended(v9ses)) {
+	if (v9fs_proto_dotu(v9ses)) {
 		inode->i_uid = stat->n_uid;
 		inode->i_gid = stat->n_gid;
 	}
-
+	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
+		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
+			/*
+			 * Hadlink support got added later to
+			 * to the .u extension. So there can be
+			 * server out there that doesn't support
+			 * this even with .u extension. So check
+			 * for non NULL stat->extension
+			 */
+			strncpy(ext, stat->extension, sizeof(ext));
+			/* HARDLINKCOUNT %u */
+			sscanf(ext, "%13s %u", tag_name, &i_nlink);
+			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
+				inode->i_nlink = i_nlink;
+		}
+	}
 	inode->i_mode = p9mode2unixmode(v9ses, stat->mode);
 	if ((S_ISBLK(inode->i_mode)) || (S_ISCHR(inode->i_mode))) {
 		char type = 0;
@@ -976,7 +994,7 @@ static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen)
 	if (IS_ERR(fid))
 		return PTR_ERR(fid);
 
-	if (!v9fs_extended(v9ses))
+	if (!v9fs_proto_dotu(v9ses))
 		return -EBADF;
 
 	st = p9_client_stat(fid);
@@ -1066,7 +1084,7 @@ static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
 	struct p9_fid *fid;
 
 	v9ses = v9fs_inode2v9ses(dir);
-	if (!v9fs_extended(v9ses)) {
+	if (!v9fs_proto_dotu(v9ses)) {
 		P9_DPRINTK(P9_DEBUG_ERROR, "not extended\n");
 		return -EPERM;
 	}
diff --git a/include/linux/virtio_9p.h b/include/linux/virtio_9p.h
index 095e10d148b4..332275080083 100644
--- a/include/linux/virtio_9p.h
+++ b/include/linux/virtio_9p.h
@@ -5,7 +5,4 @@
 #include <linux/virtio_ids.h>
 #include <linux/virtio_config.h>
 
-/* Maximum number of virtio channels per partition (1 for now) */
-#define MAX_9P_CHAN	1
-
 #endif /* _LINUX_VIRTIO_9P_H */
diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index fb00b329f0d3..52e1fff709e4 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -29,6 +29,19 @@
 /* Number of requests per row */
 #define P9_ROW_MAXTAG 255
 
+/** enum p9_proto_versions - 9P protocol versions
+ * @p9_proto_legacy: 9P Legacy mode, pre-9P2000.u
+ * @p9_proto_2000u: 9P2000.u extension
+ * @p9_proto_2010L: 9P2010.L extension
+ */
+
+enum p9_proto_versions{
+	p9_proto_legacy = 0,
+	p9_proto_2000u = 1,
+	p9_proto_2010L = 2,
+};
+
+
 /**
  * enum p9_trans_status - different states of underlying transports
  * @Connected: transport is connected and healthy
@@ -111,6 +124,7 @@ struct p9_req_t {
  * @lock: protect @fidlist
  * @msize: maximum data size negotiated by protocol
  * @dotu: extension flags negotiated by protocol
+ * @proto_version: 9P protocol version to use
  * @trans_mod: module API instantiated with this client
  * @trans: tranport instance state and API
  * @conn: connection state information used by trans_fd
@@ -137,7 +151,7 @@ struct p9_req_t {
 struct p9_client {
 	spinlock_t lock; /* protect client structure */
 	int msize;
-	unsigned char dotu;
+	unsigned char proto_version;
 	struct p9_trans_module *trans_mod;
 	enum p9_trans_status status;
 	void *trans;
@@ -209,5 +223,7 @@ int p9_parse_header(struct p9_fcall *, int32_t *, int8_t *, int16_t *, int);
 int p9stat_read(char *, int, struct p9_wstat *, int);
 void p9stat_free(struct p9_wstat *);
 
+int p9_is_proto_dotu(struct p9_client *clnt);
+int p9_is_proto_dotl(struct p9_client *clnt);
 
 #endif /* NET_9P_CLIENT_H */
diff --git a/net/9p/client.c b/net/9p/client.c
index 09d4f1e2e4a8..bde9f3d38c57 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -46,6 +46,7 @@ enum {
 	Opt_msize,
 	Opt_trans,
 	Opt_legacy,
+	Opt_version,
 	Opt_err,
 };
 
@@ -53,9 +54,42 @@ static const match_table_t tokens = {
 	{Opt_msize, "msize=%u"},
 	{Opt_legacy, "noextend"},
 	{Opt_trans, "trans=%s"},
+	{Opt_version, "version=%s"},
 	{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)
+{
+	unsigned char version = -EINVAL;
+	if (!strncmp("9p2000", name->from, name->to-name->from)) {
+		version = p9_proto_legacy;
+		P9_DPRINTK(P9_DEBUG_9P, "Protocol version: Legacy\n");
+	} else if (!strncmp("9p2000.u", name->from, name->to-name->from)) {
+		version = p9_proto_2000u;
+		P9_DPRINTK(P9_DEBUG_9P, "Protocol version: 9P2000.u\n");
+	} else if (!strncmp("9p2010.L", name->from, name->to-name->from)) {
+		version = p9_proto_2010L;
+		P9_DPRINTK(P9_DEBUG_9P, "Protocol version: 9P2010.L\n");
+	} else {
+		P9_DPRINTK(P9_DEBUG_ERROR, "Unknown protocol version %s. ",
+							name->from);
+	}
+	return version;
+}
+
 static struct p9_req_t *
 p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...);
 
@@ -75,7 +109,7 @@ static int parse_opts(char *opts, struct p9_client *clnt)
 	int option;
 	int ret = 0;
 
-	clnt->dotu = 1;
+	clnt->proto_version = p9_proto_2000u;
 	clnt->msize = 8192;
 
 	if (!opts)
@@ -118,7 +152,13 @@ static int parse_opts(char *opts, struct p9_client *clnt)
 			}
 			break;
 		case Opt_legacy:
-			clnt->dotu = 0;
+			clnt->proto_version = p9_proto_legacy;
+			break;
+		case Opt_version:
+			ret = get_protocol_version(&args[0]);
+			if (ret == -EINVAL)
+				goto free_and_return;
+			clnt->proto_version = ret;
 			break;
 		default:
 			continue;
@@ -410,14 +450,15 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
 		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))
@@ -515,7 +556,7 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
 	/* 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);
 
@@ -627,14 +668,31 @@ int p9_client_version(struct p9_client *c)
 	char *version;
 	int msize;
 
-	P9_DPRINTK(P9_DEBUG_9P, ">>> TVERSION msize %d extended %d\n",
-							c->msize, c->dotu);
-	req = p9_client_rpc(c, P9_TVERSION, "ds", c->msize,
-				c->dotu ? "9P2000.u" : "9P2000");
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TVERSION msize %d protocol %d\n",
+						c->msize, c->proto_version);
+
+	switch (c->proto_version) {
+	case p9_proto_2010L:
+		req = p9_client_rpc(c, P9_TVERSION, "ds",
+					c->msize, "9P2010.L");
+		break;
+	case p9_proto_2000u:
+		req = p9_client_rpc(c, P9_TVERSION, "ds",
+					c->msize, "9P2000.u");
+		break;
+	case p9_proto_legacy:
+		req = p9_client_rpc(c, P9_TVERSION, "ds",
+					c->msize, "9P2000");
+		break;
+	default:
+		return -EINVAL;
+		break;
+	}
+
 	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);
@@ -642,10 +700,12 @@ int p9_client_version(struct p9_client *c)
 	}
 
 	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, "9P2010.L", 8))
+		c->proto_version = p9_proto_2010L;
+	else 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;
@@ -700,8 +760,8 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 		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)
@@ -784,7 +844,7 @@ struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
 		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);
@@ -833,7 +893,7 @@ p9_client_auth(struct p9_client *clnt, char *uname, u32 n_uname, char *aname)
 		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);
@@ -891,7 +951,7 @@ struct p9_fid *p9_client_walk(struct p9_fid *oldfid, int nwname, char **wnames,
 		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);
@@ -952,7 +1012,7 @@ int p9_client_open(struct p9_fid *fid, int mode)
 		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;
@@ -997,7 +1057,7 @@ int p9_client_fcreate(struct p9_fid *fid, char *name, u32 perm, int mode,
 		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;
@@ -1098,7 +1158,7 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
 		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;
@@ -1159,7 +1219,7 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
 		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;
@@ -1199,7 +1259,7 @@ struct p9_wstat *p9_client_stat(struct p9_fid *fid)
 		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);
@@ -1226,7 +1286,7 @@ error:
 }
 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;
 
@@ -1245,7 +1305,7 @@ static int p9_client_statsize(struct p9_wstat *wst, int optional)
 	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);
@@ -1262,7 +1322,7 @@ int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst)
 
 	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 fc70147c771e..94f5a8f65e9c 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 @@ pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
 */
 
 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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 
 					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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				*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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 
 					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 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 			}
 			break;
 		case '?':
-			if (!optional)
+			if (proto_version != p9_proto_2000u)
 				return 0;
 			break;
 		default:
@@ -352,7 +356,8 @@ p9pdu_vreadf(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 }
 
 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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 				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 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 			}
 			break;
 		case '?':
-			if (!optional)
+			if (proto_version != p9_proto_2000u)
 				return 0;
 			break;
 		default:
@@ -494,32 +502,32 @@ p9pdu_vwritef(struct p9_fcall *pdu, int optional, const char *fmt, va_list ap)
 	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 @@ int p9stat_read(char *buf, int len, struct p9_wstat *st, int dotu)
 	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 ccde462e7ac5..2431c0f38d56 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 *);
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index cb50f4ae5eef..0aaed4819379 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -49,8 +49,6 @@
 
 /* a single mutex to manage channel initialization and attachment */
 static DEFINE_MUTEX(virtio_9p_lock);
-/* global which tracks highest initialized channel */
-static int chan_index;
 
 /**
  * struct virtio_chan - per-instance transport information
@@ -68,8 +66,7 @@ static int chan_index;
  *
  */
 
-static struct virtio_chan {
-	bool initialized;
+struct virtio_chan {
 	bool inuse;
 
 	spinlock_t lock;
@@ -80,7 +77,11 @@ static struct virtio_chan {
 
 	/* Scatterlist: can be too big for stack. */
 	struct scatterlist sg[VIRTQUEUE_NUM];
-} channels[MAX_9P_CHAN];
+
+	struct list_head chan_list;
+};
+
+static struct list_head virtio_chan_list;
 
 /* How many bytes left in this page. */
 static unsigned int rest_of_page(void *data)
@@ -217,9 +218,7 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
  * p9_virtio_probe - probe for existence of 9P virtio channels
  * @vdev: virtio device to probe
  *
- * This probes for existing virtio channels.  At present only
- * a single channel is in use, so in the future more work may need
- * to be done here.
+ * This probes for existing virtio channels.
  *
  */
 
@@ -227,16 +226,10 @@ static int p9_virtio_probe(struct virtio_device *vdev)
 {
 	int err;
 	struct virtio_chan *chan;
-	int index;
 
-	mutex_lock(&virtio_9p_lock);
-	index = chan_index++;
-	chan = &channels[index];
-	mutex_unlock(&virtio_9p_lock);
-
-	if (chan_index > MAX_9P_CHAN) {
-		printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
-		BUG();
+	chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
+	if (!chan) {
+		printk(KERN_ERR "9p: Failed to allocate virtio 9P channel\n");
 		err = -ENOMEM;
 		goto fail;
 	}
@@ -255,15 +248,15 @@ static int p9_virtio_probe(struct virtio_device *vdev)
 	sg_init_table(chan->sg, VIRTQUEUE_NUM);
 
 	chan->inuse = false;
-	chan->initialized = true;
+	mutex_lock(&virtio_9p_lock);
+	list_add_tail(&chan->chan_list, &virtio_chan_list);
+	mutex_unlock(&virtio_9p_lock);
 	return 0;
 
 out_free_vq:
 	vdev->config->del_vqs(vdev);
+	kfree(chan);
 fail:
-	mutex_lock(&virtio_9p_lock);
-	chan_index--;
-	mutex_unlock(&virtio_9p_lock);
 	return err;
 }
 
@@ -280,35 +273,31 @@ fail:
  * We use a simple reference count mechanism to ensure that only a single
  * mount has a channel open at a time.
  *
- * Bugs: doesn't allow identification of a specific channel
- * to allocate, channels are allocated sequentially. This was
- * a pragmatic decision to get things rolling, but ideally some
- * way of identifying the channel to attach to would be nice
- * if we are going to support multiple channels.
- *
  */
 
 static int
 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
 {
-	struct virtio_chan *chan = channels;
-	int index = 0;
+	struct virtio_chan *chan;
+	int ret = -ENOENT;
+	int found = 0;
 
 	mutex_lock(&virtio_9p_lock);
-	while (index < MAX_9P_CHAN) {
-		if (chan->initialized && !chan->inuse) {
-			chan->inuse = true;
-			break;
-		} else {
-			index++;
-			chan = &channels[index];
+	list_for_each_entry(chan, &virtio_chan_list, chan_list) {
+		if (!strcmp(devname, dev_name(&chan->vdev->dev))) {
+			if (!chan->inuse) {
+				chan->inuse = true;
+				found = 1;
+				break;
+			}
+			ret = -EBUSY;
 		}
 	}
 	mutex_unlock(&virtio_9p_lock);
 
-	if (index >= MAX_9P_CHAN) {
+	if (!found) {
 		printk(KERN_ERR "9p: no channels available\n");
-		return -ENODEV;
+		return ret;
 	}
 
 	client->trans = (void *)chan;
@@ -329,11 +318,13 @@ static void p9_virtio_remove(struct virtio_device *vdev)
 	struct virtio_chan *chan = vdev->priv;
 
 	BUG_ON(chan->inuse);
+	vdev->config->del_vqs(vdev);
+
+	mutex_lock(&virtio_9p_lock);
+	list_del(&chan->chan_list);
+	mutex_unlock(&virtio_9p_lock);
+	kfree(chan);
 
-	if (chan->initialized) {
-		vdev->config->del_vqs(vdev);
-		chan->initialized = false;
-	}
 }
 
 static struct virtio_device_id id_table[] = {
@@ -364,10 +355,7 @@ static struct p9_trans_module p9_virtio_trans = {
 /* The standard init function */
 static int __init p9_virtio_init(void)
 {
-	int count;
-
-	for (count = 0; count < MAX_9P_CHAN; count++)
-		channels[count].initialized = false;
+	INIT_LIST_HEAD(&virtio_chan_list);
 
 	v9fs_register_trans(&p9_virtio_trans);
 	return register_virtio_driver(&p9_virtio_drv);