SUNRPC: Fix a client regression when handling oversized replies

If the server sends a reply that is larger than the pre-allocated
buffer, then the current code may fail to register how much of
the stream that it has finished reading. This again can lead to
hangs.

Fixes: e92053a5 ("SUNRPC: Handle zero length fragments correctly")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/xprtsock.c

@@ -453,7 +453,7 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags,
 			goto out;
 		if (ret != want)
 			goto out;
-	} else
+	} else if (offset < seek_init)
 		offset = seek_init;
 	ret = -EMSGSIZE;
 out: