9p: add 9P2000.L rename operation

I made a V2 of this patch on top of my patches for VFS switches.
All the changes were due to change in some offsets.

rename - change name of file or directory

size[4] Trename tag[2] fid[4] newdirfid[4] name[s]
size[4] Rrename tag[2]

The rename message is used to change the name of a file, possibly moving it
to a new directory.  The 9P wstat message can only rename a file within the
same directory.
Signed-off-by: Jim Garlick <garlick@llnl.gov>
Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_inode.c

@@ -794,6 +794,13 @@ v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		goto clunk_olddir;
 	}
 
+	if (v9fs_proto_dotl(v9ses)) {
+		retval = p9_client_rename(oldfid, newdirfid,
+					(char *) new_dentry->d_name.name);
+		if (retval != -ENOSYS)
+			goto clunk_newdir;
+	}
+
 	/* 9P can only handle file rename in the same directory */
 	if (memcmp(&olddirfid->qid, &newdirfid->qid, sizeof(newdirfid->qid))) {
 		P9_DPRINTK(P9_DEBUG_ERROR,

include/net/9p/9p.h

@@ -88,6 +88,8 @@ do { \
  * enum p9_msg_t - 9P message types
  * @P9_TSTATFS: file system status request
  * @P9_RSTATFS: file system status response
+ * @P9_TRENAME: rename request
+ * @P9_RRENAME: rename response
  * @P9_TVERSION: version handshake request
  * @P9_RVERSION: version handshake response
  * @P9_TAUTH: request to establish authentication channel
@@ -129,6 +131,8 @@ do { \
 enum p9_msg_t {
 	P9_TSTATFS = 8,
 	P9_RSTATFS,
+	P9_TRENAME = 20,
+	P9_RRENAME,
 	P9_TVERSION = 100,
 	P9_RVERSION,
 	P9_TAUTH = 102,
@@ -370,6 +374,15 @@ struct p9_rstatfs {
 	u32 namelen;
 };
 
+struct p9_trename {
+	u32 fid;
+	u32 newdirfid;
+	struct p9_str name;
+};
+
+struct p9_rrename {
+};
+
 struct p9_tversion {
 	u32 msize;
 	struct p9_str version;

include/net/9p/client.h

@@ -196,6 +196,7 @@ struct p9_fid {
 };
 
 int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb);
+int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid, char *name);
 int p9_client_version(struct p9_client *);
 struct p9_client *p9_client_create(const char *dev_name, char *options);
 void p9_client_destroy(struct p9_client *clnt);

net/9p/client.c

@@ -1404,3 +1404,31 @@ int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb)
 	return err;
 }
 EXPORT_SYMBOL(p9_client_statfs);
+
+int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid, char *name)
+{
+	int err;
+	struct p9_req_t *req;
+	struct p9_client *clnt;
+
+	err = 0;
+	clnt = fid->clnt;
+
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TRENAME fid %d newdirfid %d name %s\n",
+			fid->fid, newdirfid->fid, name);
+
+	req = p9_client_rpc(clnt, P9_TRENAME, "dds", fid->fid,
+			newdirfid->fid, name);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto error;
+	}
+
+	P9_DPRINTK(P9_DEBUG_9P, "<<< RRENAME fid %d\n", fid->fid);
+
+	p9_free_req(clnt, req);
+error:
+	return err;
+}
+EXPORT_SYMBOL(p9_client_rename);
+