[PATCH v2 10/20] xprtrdma: Refactor rpcrdma_create_req()

[Chuck Lever <chuck.lever@oracle.com>]

In a subsequent patch, we'll be invoking rpcrdma_create_req() during
the call_reserve step. Memory allocation there needs to use
GFP_NOFS.

As an additional clean up, just return a pointer or NULL, because
the only error return code here is -ENOMEM.

Lastly, rename rpcrdma_create_req to match rpcrdma_req_destroy.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/backchannel.c |    6 +++---
 net/sunrpc/xprtrdma/verbs.c       |   28 ++++++++++++++++------------
 net/sunrpc/xprtrdma/xprt_rdma.h   |    3 ++-
 3 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
index 41d263c..c8a3d45 100644
--- a/net/sunrpc/xprtrdma/backchannel.c
+++ b/net/sunrpc/xprtrdma/backchannel.c
@@ -31,9 +31,9 @@ static int rpcrdma_bc_setup_reqs(struct rpcrdma_xprt *r_xprt,
 		struct rpcrdma_regbuf *rb;
 		size_t size;
 
-		req = rpcrdma_create_req(r_xprt);
-		if (IS_ERR(req))
-			return PTR_ERR(req);
+		req = rpcrdma_req_create(&r_xprt->rx_buf, GFP_KERNEL);
+		if (!req)
+			return -ENOMEM;
 		rqst = &req->rl_slot;
 
 		rqst->rq_xprt = xprt;
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index bd6bc45..42a6ef6 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1061,22 +1061,28 @@ struct rpcrdma_sendctx *rpcrdma_sendctx_get_locked(struct rpcrdma_buffer *buf)
 	rpcrdma_mrs_create(r_xprt);
 }
 
+/**
+ * rpcrdma_req_create - Allocate an rpcrdma_req object
+ * @buffer: controlling rpcrdma_buf (and r_xprt)
+ * @flags: GFP flags passed to memory allocators
+ *
+ * Returns an allocated and fully initialized rpcrdma_req or NULL.
+ */
 struct rpcrdma_req *
-rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
+rpcrdma_req_create(struct rpcrdma_buffer *buffer, gfp_t flags)
 {
-	struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
 	struct rpcrdma_regbuf *rb;
 	struct rpcrdma_req *req;
 
-	req = kzalloc(sizeof(*req), GFP_KERNEL);
+	req = kzalloc(sizeof(*req), flags);
 	if (req == NULL)
-		return ERR_PTR(-ENOMEM);
+		return NULL;
 
 	rb = rpcrdma_alloc_regbuf(RPCRDMA_HDRBUF_SIZE,
-				  DMA_TO_DEVICE, GFP_KERNEL);
+				  DMA_TO_DEVICE, flags);
 	if (IS_ERR(rb)) {
 		kfree(req);
-		return ERR_PTR(-ENOMEM);
+		return NULL;
 	}
 	req->rl_rdmabuf = rb;
 	xdr_buf_init(&req->rl_hdrbuf, rb->rg_base, rdmab_length(rb));
@@ -1153,16 +1159,14 @@ struct rpcrdma_req *
 
 	INIT_LIST_HEAD(&buf->rb_send_bufs);
 	INIT_LIST_HEAD(&buf->rb_allreqs);
+
+	rc = -ENOMEM;
 	for (i = 0; i < buf->rb_max_requests; i++) {
 		struct rpcrdma_req *req;
 
-		req = rpcrdma_create_req(r_xprt);
-		if (IS_ERR(req)) {
-			dprintk("RPC:       %s: request buffer %d alloc"
-				" failed\n", __func__, i);
-			rc = PTR_ERR(req);
+		req = rpcrdma_req_create(buf, GFP_KERNEL);
+		if (!req)
 			goto out;
-		}
 		list_add(&req->rl_list, &buf->rb_send_bufs);
 	}
 
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index e1c6235..685b65f 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -564,7 +564,8 @@ int rpcrdma_ep_post(struct rpcrdma_ia *, struct rpcrdma_ep *,
 /*
  * Buffer calls - xprtrdma/verbs.c
  */
-struct rpcrdma_req *rpcrdma_create_req(struct rpcrdma_xprt *);
+struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_buffer *buf,
+				       gfp_t flags);
 void rpcrdma_req_destroy(struct rpcrdma_req *req);
 int rpcrdma_buffer_create(struct rpcrdma_xprt *);
 void rpcrdma_buffer_destroy(struct rpcrdma_buffer *);