xprtrdma: Destroy reps from previous connection instance

To safely get rid of all rpcrdma_reps from a particular connection
instance, xprtrdma has to wait until each of those reps is finished
being used. A rep may be backing the rq_rcv_buf of an RPC that has
just completed, for example.

Since it is safe to invoke rpcrdma_rep_destroy() only in the Receive
completion handler, simply mark reps remaining in the rb_all_reps
list after the transport is drained. These will then be deleted as
rpcrdma_post_recvs pulls them off the rep free list.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/verbs.c

@@ -1174,8 +1174,10 @@ static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt)
 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
 	struct rpcrdma_rep *rep;
 
-	list_for_each_entry(rep, &buf->rb_all_reps, rr_all)
+	list_for_each_entry(rep, &buf->rb_all_reps, rr_all) {
 		rpcrdma_regbuf_dma_unmap(rep->rr_rdmabuf);
+		rep->rr_temp = true;
+	}
 }
 
 static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf)