[PATCH v2 17/20] xprtrdma: Allocate RPC/RDMA send buffer separately from struct rpcrdma_req

[Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

The rl_base field is the buffer where each RPC/RDMA send header is
built.

Pre-posted send buffers are supposed to be the same size on the
client and server. For Solaris and Linux, that size is currently
1024 bytes, the inline threshold.

The size of the rl_base buffer is currently dependent on
RPCRDMA_MAX_DATA_SEGS. When the client constructs a chunk list in
the RPC/RDMA header, each segment in the list takes up a little
room in the buffer.

If we want a large r/wsize maximum, MAX_SEGS will grow
significantly, but notice that the inline threshold size is not
supposed to change (since it should match on the client and server).

Therefore the inline size is the real limit on the size of the
RPC/RDMA send header.

No longer use RPCRDMA_MAX_DATA_SEGS to determine the size or
placement of the RPC/RDMA header send buffer. The buffer size should
always be the same as the inline threshold size.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
 net/sunrpc/xprtrdma/rpc_rdma.c  |   11 +++++------
 net/sunrpc/xprtrdma/transport.c |    9 +++++++++
 net/sunrpc/xprtrdma/verbs.c     |   22 +++-------------------
 net/sunrpc/xprtrdma/xprt_rdma.h |    6 ++----
 4 files changed, 19 insertions(+), 29 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 8a6bdbd..c1d4a09 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -294,7 +294,7 @@ ssize_t
 rpcrdma_marshal_chunks(struct rpc_rqst *rqst, ssize_t result)
 {
 	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
-	struct rpcrdma_msg *headerp = (struct rpcrdma_msg *)req->rl_base;
+	struct rpcrdma_msg *headerp = rdmab_to_msg(req->rl_rdmabuf);
 
 	if (req->rl_rtype != rpcrdma_noch)
 		result = rpcrdma_create_chunks(rqst, &rqst->rq_snd_buf,
@@ -406,8 +406,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	base = rqst->rq_svec[0].iov_base;
 	rpclen = rqst->rq_svec[0].iov_len;
 
-	/* build RDMA header in private area at front */
-	headerp = (struct rpcrdma_msg *) req->rl_base;
+	headerp = rdmab_to_msg(req->rl_rdmabuf);
 	/* don't byte-swap XID, it's already done in request */
 	headerp->rm_xid = rqst->rq_xid;
 	headerp->rm_vers = rpcrdma_version;
@@ -528,7 +527,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	dprintk("RPC:       %s: %s: hdrlen %zd rpclen %zd padlen %zd"
 		" headerp 0x%p base 0x%p lkey 0x%x\n",
 		__func__, transfertypes[req->rl_wtype], hdrlen, rpclen, padlen,
-		headerp, base, req->rl_iov.lkey);
+		headerp, base, rdmab_lkey(req->rl_rdmabuf));
 
 	/*
 	 * initialize send_iov's - normally only two: rdma chunk header and
@@ -537,9 +536,9 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	 * header and any write data. In all non-rdma cases, any following
 	 * data has been copied into the RPC header buffer.
 	 */
-	req->rl_send_iov[0].addr = req->rl_iov.addr;
+	req->rl_send_iov[0].addr = rdmab_addr(req->rl_rdmabuf);
 	req->rl_send_iov[0].length = hdrlen;
-	req->rl_send_iov[0].lkey = req->rl_iov.lkey;
+	req->rl_send_iov[0].lkey = rdmab_lkey(req->rl_rdmabuf);
 
 	req->rl_send_iov[1].addr = rdmab_addr(req->rl_sendbuf);
 	req->rl_send_iov[1].length = rpclen;
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index a9d5662..2c2fabe 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -470,6 +470,8 @@ xprt_rdma_allocate(struct rpc_task *task, size_t size)
 	if (req == NULL)
 		return NULL;
 
+	if (req->rl_rdmabuf == NULL)
+		goto out_rdmabuf;
 	if (req->rl_sendbuf == NULL)
 		goto out_sendbuf;
 	if (size > req->rl_sendbuf->rg_size)
@@ -480,6 +482,13 @@ out:
 	req->rl_connect_cookie = 0;	/* our reserved value */
 	return req->rl_sendbuf->rg_base;
 
+out_rdmabuf:
+	min_size = RPCRDMA_INLINE_WRITE_THRESHOLD(task->tk_rqstp);
+	rb = rpcrdma_alloc_regbuf(&r_xprt->rx_ia, min_size, flags);
+	if (IS_ERR(rb))
+		goto out_fail;
+	req->rl_rdmabuf = rb;
+
 out_sendbuf:
 	/* XDR encoding and RPC/RDMA marshaling of this request has not
 	 * yet occurred. Thus a lower bound is needed to prevent buffer
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 4089440..c81749b 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1078,30 +1078,14 @@ rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 static struct rpcrdma_req *
 rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
 {
-	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
-	size_t wlen = cdata->inline_wsize;
-	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	struct rpcrdma_req *req;
-	int rc;
 
-	rc = -ENOMEM;
-	req = kmalloc(sizeof(*req) + wlen, GFP_KERNEL);
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
 	if (req == NULL)
-		goto out;
-	memset(req, 0, sizeof(*req));
-
-	rc = rpcrdma_register_internal(ia, req->rl_base, wlen,
-				       &req->rl_handle, &req->rl_iov);
-	if (rc)
-		goto out_free;
+		return ERR_PTR(-ENOMEM);
 
 	req->rl_buffer = &r_xprt->rx_buf;
 	return req;
-
-out_free:
-	kfree(req);
-out:
-	return ERR_PTR(rc);
 }
 
 static struct rpcrdma_rep *
@@ -1333,7 +1317,7 @@ rpcrdma_destroy_req(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
 		return;
 
 	rpcrdma_free_regbuf(ia, req->rl_sendbuf);
-	rpcrdma_deregister_internal(ia, req->rl_handle, &req->rl_iov);
+	rpcrdma_free_regbuf(ia, req->rl_rdmabuf);
 	kfree(req);
 }
 
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index aa82f8d..84ad863 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -268,12 +268,10 @@ struct rpcrdma_req {
 	enum rpcrdma_chunktype	rl_rtype, rl_wtype;
 	struct rpcrdma_buffer *rl_buffer; /* home base for this structure */
 	struct rpcrdma_rep	*rl_reply;/* holder for reply buffer */
-	struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];/* chunk segments */
 	struct ib_sge	rl_send_iov[4];	/* for active requests */
+	struct rpcrdma_regbuf *rl_rdmabuf;
 	struct rpcrdma_regbuf *rl_sendbuf;
-	struct ib_sge	rl_iov;		/* for posting */
-	struct ib_mr	*rl_handle;	/* handle for mem in rl_iov */
-	char		rl_base[MAX_RPCRDMAHDR]; /* start of actual buffer */
+	struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];
 };
 
 static inline struct rpcrdma_req *

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