SUNRPC: svc_tcp_sendmsg() should handle errors from xdr_alloc_bvec()

The allocation is done with GFP_KERNEL, but it could still fail in a low
memory situation.

Fixes: 4a85a6a3 ("SUNRPC: Handle TCP socket sends with kernel_sendpage() again")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/svcsock.c

@@ -1096,7 +1096,9 @@ static int svc_tcp_sendmsg(struct socket *sock, struct xdr_buf *xdr,
 	int ret;
 
 	*sentp = 0;
-	xdr_alloc_bvec(xdr, GFP_KERNEL);
+	ret = xdr_alloc_bvec(xdr, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
 
 	ret = kernel_sendmsg(sock, &msg, &rm, 1, rm.iov_len);
 	if (ret < 0)