xprtrdma: Use same device when mapping or syncing DMA buffers

When the underlying device driver is reloaded, ia->ri_device will be
replaced. All cached copies of that device pointer have to be
updated as well.

Commit 54cbd6b0c6b9 ("xprtrdma: Delay DMA mapping Send and Receive
buffers") added the rg_device field to each regbuf. As part of
handling a device removal, rpcrdma_dma_unmap_regbuf is invoked on
all regbufs for a transport.

Simply calling rpcrdma_dma_map_regbuf for each Receive buffer after
the driver has been reloaded should reinitialize rg_device correctly
for every case except rpcrdma_wc_receive, which still uses
rpcrdma_rep::rr_device.

Ensure the same device that was used to map a Receive buffer is also
used to sync it in rpcrdma_wc_receive by using rg_device there
instead of rr_device.

This is the only use of rr_device, so it can be removed.

The use of regbufs in the send path is also updated, for
completeness.

Fixes: 54cbd6b0c6b9 ("xprtrdma: Delay DMA mapping Send and ... ")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index a044be2..e68131b 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -494,7 +494,7 @@ rpcrdma_prepare_hdr_sge(struct rpcrdma_ia *ia, struct rpcrdma_req *req,
 	}
 	sge->length = len;
 
-	ib_dma_sync_single_for_device(ia->ri_device, sge->addr,
+	ib_dma_sync_single_for_device(rdmab_device(rb), sge->addr,
 				      sge->length, DMA_TO_DEVICE);
 	req->rl_send_wr.num_sge++;
 	return true;
@@ -523,7 +523,7 @@ rpcrdma_prepare_msg_sges(struct rpcrdma_ia *ia, struct rpcrdma_req *req,
 	sge[sge_no].addr = rdmab_addr(rb);
 	sge[sge_no].length = xdr->head[0].iov_len;
 	sge[sge_no].lkey = rdmab_lkey(rb);
-	ib_dma_sync_single_for_device(device, sge[sge_no].addr,
+	ib_dma_sync_single_for_device(rdmab_device(rb), sge[sge_no].addr,
 				      sge[sge_no].length, DMA_TO_DEVICE);
 
 	/* If there is a Read chunk, the page list is being handled