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>
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 13a8ed6..de9a395 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -794,6 +794,13 @@
 		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,