xprtrdma: Allocate and map transport header buffers at connect time

Currently the underlying RDMA device is chosen at transport set-up
time. But it will soon be at connect time instead.

The maximum size of a transport header is based on device
capabilities. Thus transport header buffers have to be allocated
_after_ the underlying device has been chosen (via address and route
resolution); ie, in the connect worker.

Thus, move the allocation of transport header buffers to the connect
worker, after the point at which the underlying RDMA device has been
chosen.

This also means the RDMA device is available to do a DMA mapping of
these buffers at connect time, instead of in the hot I/O path. Make
that optimization as well.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 3 insertions, 7 deletions

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index c6dcea06c754..28020ec104d4 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -580,22 +580,19 @@ void rpcrdma_sendctx_unmap(struct rpcrdma_sendctx *sc)
 
 /* Prepare an SGE for the RPC-over-RDMA transport header.
  */
-static bool rpcrdma_prepare_hdr_sge(struct rpcrdma_xprt *r_xprt,
+static void rpcrdma_prepare_hdr_sge(struct rpcrdma_xprt *r_xprt,
 				    struct rpcrdma_req *req, u32 len)
 {
 	struct rpcrdma_sendctx *sc = req->rl_sendctx;
 	struct rpcrdma_regbuf *rb = req->rl_rdmabuf;
 	struct ib_sge *sge = &sc->sc_sges[req->rl_wr.num_sge++];
 
-	if (!rpcrdma_regbuf_dma_map(r_xprt, rb))
-		return false;
 	sge->addr = rdmab_addr(rb);
 	sge->length = len;
 	sge->lkey = rdmab_lkey(rb);
 
 	ib_dma_sync_single_for_device(rdmab_device(rb), sge->addr, sge->length,
 				      DMA_TO_DEVICE);
-	return true;
 }
 
 /* The head iovec is straightforward, as it is usually already
@@ -836,10 +833,9 @@ inline int rpcrdma_prepare_send_sges(struct rpcrdma_xprt *r_xprt,
 	req->rl_wr.num_sge = 0;
 	req->rl_wr.opcode = IB_WR_SEND;
 
-	ret = -EIO;
-	if (!rpcrdma_prepare_hdr_sge(r_xprt, req, hdrlen))
-		goto out_unmap;
+	rpcrdma_prepare_hdr_sge(r_xprt, req, hdrlen);
 
+	ret = -EIO;
 	switch (rtype) {
 	case rpcrdma_noch_pullup:
 		if (!rpcrdma_prepare_noch_pullup(r_xprt, req, xdr))