xprtrdma: Remap Receive buffers after a reconnect

On server-initiated disconnect, rpcrdma_xprt_disconnect() was DMA-
unmapping the Receive buffers, but rpcrdma_post_recvs() neglected
to remap them after a new connection had been established. The
result was immediate failure of the new connection with the Receives
flushing with LOCAL_PROT_ERR.

Fixes: 671c450 ("xprtrdma: Fix oops in Receive handler after device removal")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: chucklever

net/sunrpc/xprtrdma/verbs.c

@@ -935,9 +935,6 @@ struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
 	if (!rep->rr_rdmabuf)
 		goto out_free;
 
-	if (!rpcrdma_regbuf_dma_map(r_xprt, rep->rr_rdmabuf))
-		goto out_free_regbuf;
-
 	rep->rr_cid.ci_completion_id =
 		atomic_inc_return(&r_xprt->rx_ep->re_completion_ids);
 
@@ -956,8 +953,6 @@ struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
 	spin_unlock(&buf->rb_lock);
 	return rep;
 
-out_free_regbuf:
-	rpcrdma_regbuf_free(rep->rr_rdmabuf);
 out_free:
 	kfree(rep);
 out:
@@ -1363,6 +1358,10 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp)
 			rep = rpcrdma_rep_create(r_xprt, temp);
 		if (!rep)
 			break;
+		if (!rpcrdma_regbuf_dma_map(r_xprt, rep->rr_rdmabuf)) {
+			rpcrdma_rep_put(buf, rep);
+			break;
+		}
 
 		rep->rr_cid.ci_queue_id = ep->re_attr.recv_cq->res.id;
 		trace_xprtrdma_post_recv(rep);