xprtrdma: Simplify rpcrdma_rep_create

Clean up.

Commit 7c8d9e7c ("xprtrdma: Move Receive posting to Receive
handler") reduced the number of rpcrdma_rep_create call sites to
one. After that commit, the backchannel code no longer invokes it.

Therefore the free list logic added by commit d698c4a0
("xprtrdma: Fix backchannel allocation of extra rpcrdma_reps") is
no longer necessary, and in fact adds some extra overhead that we
can do without.

Simply post any newly created reps. They will get added back to
the rb_recv_bufs list when they subsequently complete.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/verbs.c

@@ -1036,9 +1036,9 @@ struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size,
 	return NULL;
 }
 
-static bool rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt, bool temp)
+static struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
+					      bool temp)
 {
-	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
 	struct rpcrdma_rep *rep;
 
 	rep = kzalloc(sizeof(*rep), GFP_KERNEL);
@@ -1049,9 +1049,9 @@ static bool rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt, bool temp)
 					       DMA_FROM_DEVICE, GFP_KERNEL);
 	if (!rep->rr_rdmabuf)
 		goto out_free;
+
 	xdr_buf_init(&rep->rr_hdrbuf, rdmab_data(rep->rr_rdmabuf),
 		     rdmab_length(rep->rr_rdmabuf));
-
 	rep->rr_cqe.done = rpcrdma_wc_receive;
 	rep->rr_rxprt = r_xprt;
 	rep->rr_recv_wr.next = NULL;
@@ -1059,16 +1059,12 @@ static bool rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt, bool temp)
 	rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
 	rep->rr_recv_wr.num_sge = 1;
 	rep->rr_temp = temp;
-
-	spin_lock(&buf->rb_lock);
-	list_add(&rep->rr_list, &buf->rb_recv_bufs);
-	spin_unlock(&buf->rb_lock);
-	return true;
+	return rep;
 
 out_free:
 	kfree(rep);
 out:
-	return false;
+	return NULL;
 }
 
 /**
@@ -1497,7 +1493,6 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
 	count = 0;
 	wr = NULL;
 	while (needed) {
-		struct rpcrdma_regbuf *rb;
 		struct rpcrdma_rep *rep;
 
 		spin_lock(&buf->rb_lock);
@@ -1507,13 +1502,12 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
 			list_del(&rep->rr_list);
 		spin_unlock(&buf->rb_lock);
 		if (!rep) {
-			if (!rpcrdma_rep_create(r_xprt, temp))
+			rep = rpcrdma_rep_create(r_xprt, temp);
+			if (!rep)
 				break;
-			continue;
 		}
 
-		rb = rep->rr_rdmabuf;
-		if (!rpcrdma_regbuf_dma_map(r_xprt, rb)) {
+		if (!rpcrdma_regbuf_dma_map(r_xprt, rep->rr_rdmabuf)) {
 			rpcrdma_recv_buffer_put(rep);
 			break;
 		}