Merge tag 'rds-odp-for-5.5' of https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma

Leon Romanovsky says:

====================
Use ODP MRs for kernel ULPs

The following series extends MR creation routines to allow creation of
user MRs through kernel ULPs as a proxy. The immediate use case is to
allow RDS to work over FS-DAX, which requires ODP (on-demand-paging)
MRs to be created and such MRs were not possible to create prior this
series.

The first part of this patchset extends RDMA to have special verb
ib_reg_user_mr(). The common use case that uses this function is a
userspace application that allocates memory for HCA access but the
responsibility to register the memory at the HCA is on an kernel ULP.
This ULP acts as an agent for the userspace application.

The second part provides advise MR functionality for ULPs. This is
integral part of ODP flows and used to trigger pagefaults in advance
to prepare memory before running working set.

The third part is actual user of those in-kernel APIs.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 31 insertions, 13 deletions

diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index d1cc1d7778d8..dfe778220657 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -39,6 +39,7 @@
 #include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
+#include "ib_mr.h"
 
 /*
  * Convert IB-specific error message to RDS error message and call core
@@ -635,6 +636,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
 		send->s_sge[0].addr = ic->i_send_hdrs_dma[pos];
 
 		send->s_sge[0].length = sizeof(struct rds_header);
+		send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
 
 		memcpy(ic->i_send_hdrs[pos], &rm->m_inc.i_hdr,
 		       sizeof(struct rds_header));
@@ -650,6 +652,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
 			send->s_sge[1].addr = sg_dma_address(scat);
 			send->s_sge[1].addr += rm->data.op_dmaoff;
 			send->s_sge[1].length = len;
+			send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
 
 			bytes_sent += len;
 			rm->data.op_dmaoff += len;
@@ -858,20 +861,29 @@ int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
 	int ret;
 	int num_sge;
 	int nr_sig = 0;
+	u64 odp_addr = op->op_odp_addr;
+	u32 odp_lkey = 0;
 
 	/* map the op the first time we see it */
-	if (!op->op_mapped) {
-		op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
-					     op->op_sg, op->op_nents, (op->op_write) ?
-					     DMA_TO_DEVICE : DMA_FROM_DEVICE);
-		rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
-		if (op->op_count == 0) {
-			rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
-			ret = -ENOMEM; /* XXX ? */
-			goto out;
+	if (!op->op_odp_mr) {
+		if (!op->op_mapped) {
+			op->op_count =
+				ib_dma_map_sg(ic->i_cm_id->device, op->op_sg,
+					      op->op_nents,
+					      (op->op_write) ? DMA_TO_DEVICE :
+							       DMA_FROM_DEVICE);
+			rdsdebug("ic %p mapping op %p: %d\n", ic, op,
+				 op->op_count);
+			if (op->op_count == 0) {
+				rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
+				ret = -ENOMEM; /* XXX ? */
+				goto out;
+			}
+			op->op_mapped = 1;
 		}
-
-		op->op_mapped = 1;
+	} else {
+		op->op_count = op->op_nents;
+		odp_lkey = rds_ib_get_lkey(op->op_odp_mr->r_trans_private);
 	}
 
 	/*
@@ -923,14 +935,20 @@ int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
 		for (j = 0; j < send->s_rdma_wr.wr.num_sge &&
 		     scat != &op->op_sg[op->op_count]; j++) {
 			len = sg_dma_len(scat);
-			send->s_sge[j].addr = sg_dma_address(scat);
+			if (!op->op_odp_mr) {
+				send->s_sge[j].addr = sg_dma_address(scat);
+				send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
+			} else {
+				send->s_sge[j].addr = odp_addr;
+				send->s_sge[j].lkey = odp_lkey;
+			}
 			send->s_sge[j].length = len;
-			send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
 
 			sent += len;
 			rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
 
 			remote_addr += len;
+			odp_addr += len;
 			scat++;
 		}