net/9p: fix statsize inside twstat

stat structures contain a size prefix.  In our twstat messages
we were including the size of the size prefix in the prefix, which is not
what the protocol wants, and Inferno servers would complain.
Signed-off-by: NEric Van Hensbergen <ericvh@gmail.com>

net/9p/client.c

@@ -1222,10 +1222,11 @@ static int p9_client_statsize(struct p9_wstat *wst, int optional)
 {
 	int ret;
 
+	/* NOTE: size shouldn't include its own length */
 	/* size[2] type[2] dev[4] qid[13] */
 	/* mode[4] atime[4] mtime[4] length[8]*/
 	/* name[s] uid[s] gid[s] muid[s] */
-	ret = 2+2+4+13+4+4+4+8+2+2+2+2;
+	ret = 2+4+13+4+4+4+8+2+2+2+2;
 
 	if (wst->name)
 		ret += strlen(wst->name);
@@ -1266,7 +1267,7 @@ int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst)
 		wst->name, wst->uid, wst->gid, wst->muid, wst->extension,
 		wst->n_uid, wst->n_gid, wst->n_muid);
 
-	req = p9_client_rpc(clnt, P9_TWSTAT, "dwS", fid->fid, wst->size, wst);
+	req = p9_client_rpc(clnt, P9_TWSTAT, "dwS", fid->fid, wst->size+2, wst);
 	if (IS_ERR(req)) {
 		err = PTR_ERR(req);
 		goto error;