xprtrdma: Remove rpcrdma_req::rl_buffer

Clean up.

There is only one remaining function, rpcrdma_buffer_put(), that
uses this field. Its caller can supply a pointer to the correct
rpcrdma_buffer, enabling the removal of an 8-byte pointer field
from a frequently-allocated shared data structure.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/transport.c

@@ -550,8 +550,11 @@ xprt_rdma_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
 static void
 xprt_rdma_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *rqst)
 {
+	struct rpcrdma_xprt *r_xprt =
+		container_of(xprt, struct rpcrdma_xprt, rx_xprt);
+
 	memset(rqst, 0, sizeof(*rqst));
-	rpcrdma_buffer_put(rpcr_to_rdmar(rqst));
+	rpcrdma_buffer_put(&r_xprt->rx_buf, rpcr_to_rdmar(rqst));
 	rpc_wake_up_next(&xprt->backlog);
 }
 

net/sunrpc/xprtrdma/verbs.c

@@ -1019,7 +1019,6 @@ struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size,
 	if (!req->rl_recvbuf)
 		goto out4;
 
-	req->rl_buffer = buffer;
 	INIT_LIST_HEAD(&req->rl_registered);
 	spin_lock(&buffer->rb_lock);
 	list_add(&req->rl_all, &buffer->rb_allreqs);
@@ -1299,13 +1298,12 @@ rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
 
 /**
  * rpcrdma_buffer_put - Put request/reply buffers back into pool
+ * @buffers: buffer pool
  * @req: object to return
  *
  */
-void
-rpcrdma_buffer_put(struct rpcrdma_req *req)
+void rpcrdma_buffer_put(struct rpcrdma_buffer *buffers, struct rpcrdma_req *req)
 {
-	struct rpcrdma_buffer *buffers = req->rl_buffer;
 	struct rpcrdma_rep *rep = req->rl_reply;
 
 	req->rl_reply = NULL;

net/sunrpc/xprtrdma/xprt_rdma.h

@@ -320,7 +320,6 @@ struct rpcrdma_buffer;
 struct rpcrdma_req {
 	struct list_head	rl_list;
 	struct rpc_rqst		rl_slot;
-	struct rpcrdma_buffer	*rl_buffer;
 	struct rpcrdma_rep	*rl_reply;
 	struct xdr_stream	rl_stream;
 	struct xdr_buf		rl_hdrbuf;
@@ -499,7 +498,8 @@ rpcrdma_mr_recycle(struct rpcrdma_mr *mr)
 }
 
 struct rpcrdma_req *rpcrdma_buffer_get(struct rpcrdma_buffer *);
-void rpcrdma_buffer_put(struct rpcrdma_req *);
+void rpcrdma_buffer_put(struct rpcrdma_buffer *buffers,
+			struct rpcrdma_req *req);
 void rpcrdma_recv_buffer_put(struct rpcrdma_rep *);
 
 bool rpcrdma_regbuf_realloc(struct rpcrdma_regbuf *rb, size_t size,