[PATCH v2 18/20] xprtrdma: Allocate RPC/RDMA receive buffer separately from struct rpcrdma_rep

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

The rr_base field is the buffer where each RPC/RDMA reply header
lands.

In some cases the RPC reply header also lands in this buffer, just
after the RPC/RDMA header.

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

The size of the rr_base buffer is currently dependent on
RPCRDMA_MAX_DATA_SEGS. When the server 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 won't
change.

Therefore the inline size is the real limit on the size of the
RPC/RDMA header. The largest RPC reply the client can receive via
RDMA SEND is also no bigger than the inline size.

Thus the size of the pre-posted receive buffer should be exactly the
inline size * 2. The MAX_RPCRDMAHDR term should be replaced, and
rounding up ( 1 << fls(yada) ) is not necessary.

RPC replies received via RDMA WRITE (long replies) are caught in
rq_rcv_buf, which is the second half of the RPC send buffer. Ie,
such replies are not involved in any way with rr_base.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
 net/sunrpc/xprtrdma/rpc_rdma.c  |    5 +++--
 net/sunrpc/xprtrdma/verbs.c     |   27 ++++++++++++++-------------
 net/sunrpc/xprtrdma/xprt_rdma.h |   14 ++++++--------
 3 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index c1d4a09..02efcaa 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -572,6 +572,7 @@ rpcrdma_count_chunks(struct rpcrdma_rep *rep, unsigned int max, int wrchunk, __b
 {
 	unsigned int i, total_len;
 	struct rpcrdma_write_chunk *cur_wchunk;
+	char *base = (char *)rdmab_to_msg(rep->rr_rdmabuf);
 
 	i = be32_to_cpu(**iptrp);
 	if (i > max)
@@ -599,7 +600,7 @@ rpcrdma_count_chunks(struct rpcrdma_rep *rep, unsigned int max, int wrchunk, __b
 			return -1;
 		cur_wchunk = (struct rpcrdma_write_chunk *) w;
 	}
-	if ((char *) cur_wchunk > rep->rr_base + rep->rr_len)
+	if ((char *)cur_wchunk > base + rep->rr_len)
 		return -1;
 
 	*iptrp = (__be32 *) cur_wchunk;
@@ -753,7 +754,7 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
 		dprintk("RPC:       %s: short/invalid reply\n", __func__);
 		goto repost;
 	}
-	headerp = (struct rpcrdma_msg *) rep->rr_base;
+	headerp = rdmab_to_msg(rep->rr_rdmabuf);
 	if (headerp->rm_vers != rpcrdma_version) {
 		dprintk("RPC:       %s: invalid version %d\n",
 			__func__, be32_to_cpu(headerp->rm_vers));
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index c81749b..7aac422 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -298,8 +298,9 @@ rpcrdma_recvcq_process_wc(struct ib_wc *wc, struct list_head *sched_list)
 
 	rep->rr_len = wc->byte_len;
 	ib_dma_sync_single_for_cpu(rdmab_to_ia(rep->rr_buffer)->ri_id->device,
-			rep->rr_iov.addr, rep->rr_len, DMA_FROM_DEVICE);
-	prefetch(rep->rr_base);
+				   rdmab_addr(rep->rr_rdmabuf),
+				   rep->rr_len, DMA_FROM_DEVICE);
+	prefetch(rdmab_to_msg(rep->rr_rdmabuf));
 
 out_schedule:
 	list_add_tail(&rep->rr_list, sched_list);
@@ -1092,23 +1093,21 @@ static struct rpcrdma_rep *
 rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
 {
 	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
-	size_t rlen = 1 << fls(cdata->inline_rsize +
-			       sizeof(struct rpcrdma_rep));
+	size_t rlen = cdata->inline_rsize << 1;
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	struct rpcrdma_rep *rep;
 	int rc;
 
 	rc = -ENOMEM;
-	rep = kmalloc(rlen, GFP_KERNEL);
+	rep = kzalloc(sizeof(*rep), GFP_KERNEL);
 	if (rep == NULL)
 		goto out;
-	memset(rep, 0, sizeof(*rep));
 
-	rc = rpcrdma_register_internal(ia, rep->rr_base, rlen -
-				       offsetof(struct rpcrdma_rep, rr_base),
-				       &rep->rr_handle, &rep->rr_iov);
-	if (rc)
+	rep->rr_rdmabuf = rpcrdma_alloc_regbuf(ia, rlen, GFP_KERNEL);
+	if (IS_ERR(rep->rr_rdmabuf)) {
+		rc = PTR_ERR(rep->rr_rdmabuf);
 		goto out_free;
+	}
 
 	rep->rr_buffer = &r_xprt->rx_buf;
 	return rep;
@@ -1306,7 +1305,7 @@ rpcrdma_destroy_rep(struct rpcrdma_ia *ia, struct rpcrdma_rep *rep)
 	if (!rep)
 		return;
 
-	rpcrdma_deregister_internal(ia, rep->rr_handle, &rep->rr_iov);
+	rpcrdma_free_regbuf(ia, rep->rr_rdmabuf);
 	kfree(rep);
 }
 
@@ -2209,11 +2208,13 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
 
 	recv_wr.next = NULL;
 	recv_wr.wr_id = (u64) (unsigned long) rep;
-	recv_wr.sg_list = &rep->rr_iov;
+	recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
 	recv_wr.num_sge = 1;
 
 	ib_dma_sync_single_for_cpu(ia->ri_id->device,
-		rep->rr_iov.addr, rep->rr_iov.length, DMA_BIDIRECTIONAL);
+				   rdmab_addr(rep->rr_rdmabuf),
+				   rdmab_length(rep->rr_rdmabuf),
+				   DMA_BIDIRECTIONAL);
 
 	rc = ib_post_recv(ia->ri_id->qp, &recv_wr, &recv_wr_fail);
 
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 84ad863..2b69316 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -180,14 +180,12 @@ enum rpcrdma_chunktype {
 struct rpcrdma_buffer;
 
 struct rpcrdma_rep {
-	unsigned int	rr_len;		/* actual received reply length */
-	struct rpcrdma_buffer *rr_buffer; /* home base for this structure */
-	struct rpc_xprt	*rr_xprt;	/* needed for request/reply matching */
-	void (*rr_func)(struct rpcrdma_rep *);/* called by tasklet in softint */
-	struct list_head rr_list;	/* tasklet list */
-	struct ib_sge	rr_iov;		/* for posting */
-	struct ib_mr	*rr_handle;	/* handle for mem in rr_iov */
-	char	rr_base[MAX_RPCRDMAHDR]; /* minimal inline receive buffer */
+	unsigned int		rr_len;
+	struct rpcrdma_buffer	*rr_buffer;
+	struct rpc_xprt		*rr_xprt;
+	void			(*rr_func)(struct rpcrdma_rep *);
+	struct list_head	rr_list;
+	struct rpcrdma_regbuf	*rr_rdmabuf;
 };
 
 /*

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