SUNRPC: Fix a memory leak in call_encode()

If we retransmit an RPC request, we currently end up clobbering the
value of req->rq_rcv_buf.bvec that was allocated by the initial call to
xprt_request_prepare(req).

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

include/linux/sunrpc/xdr.h

@@ -72,7 +72,6 @@ xdr_buf_init(struct xdr_buf *buf, void *start, size_t len)
 	buf->head[0].iov_base = start;
 	buf->head[0].iov_len = len;
 	buf->tail[0].iov_len = 0;
-	buf->bvec = NULL;
 	buf->pages = NULL;
 	buf->page_len = 0;
 	buf->flags = 0;

net/sunrpc/clnt.c

@@ -2309,6 +2309,7 @@ out_retry:
 	task->tk_status = 0;
 	/* Note: rpc_verify_header() may have freed the RPC slot */
 	if (task->tk_rqstp == req) {
+		xdr_free_bvec(&req->rq_rcv_buf);
 		req->rq_reply_bytes_recvd = req->rq_rcv_buf.len = 0;
 		if (task->tk_client->cl_discrtry)
 			xprt_conditional_disconnect(req->rq_xprt,

net/sunrpc/xprt.c

@@ -1623,6 +1623,8 @@ xprt_request_init(struct rpc_task *task)
 	req->rq_snd_buf.buflen = 0;
 	req->rq_rcv_buf.len = 0;
 	req->rq_rcv_buf.buflen = 0;
+	req->rq_snd_buf.bvec = NULL;
+	req->rq_rcv_buf.bvec = NULL;
 	req->rq_release_snd_buf = NULL;
 	xprt_reset_majortimeo(req);
 	dprintk("RPC: %5u reserved req %p xid %08x\n", task->tk_pid,