LU-12893 lnet: fix peer_ni selection

When selecting a peer-ni we must use the same peer NID
through all the messages which belong to the same RPC.
This is necessary in order to ensure we do the RDMA over
the optimal interface.

Lustre-change: https://review.whamcloud.com/36552
Lustre-commit: 94ee26738884e3f5b241698bc2e7a8da9702d264

Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I0391537da32bc6ac7a8a3d92e207bf172d111981
Reviewed-by: Chris Horn <hornc@cray.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/36643
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lnet/lnet/lib-move.c b/lnet/lnet/lib-move.c
index 8d73fa7..c02c38a 100644 (file)
--- a/lnet/lnet/lib-move.c
+++ b/lnet/lnet/lib-move.c
@@ -1922,8 +1922,11 @@ lnet_handle_spec_local_nmr_dst(struct lnet_send_data *sd)
  * Local Destination
  * MR Peer
  *
- * Run the selection algorithm on the peer NIs unless we're sending
- * a response, in this case just send to the destination
+ * Don't run the selection algorithm on the peer NIs. By specifying the
+ * local NID, we're also saying that we should always use the destination NID
+ * provided. This handles the case where we should be using the same
+ * destination NID for the all the messages which belong to the same RPC
+ * request.
  */
 static int
 lnet_handle_spec_local_mr_dst(struct lnet_send_data *sd)
@@ -1936,17 +1939,6 @@ lnet_handle_spec_local_mr_dst(struct lnet_send_data *sd)
                return -EINVAL;
        }
 
-       /*
-        * only run the selection algorithm to pick the peer_ni if we're
-        * sending a GET or a PUT. Responses are sent to the same
-        * destination NID provided.
-        */
-       if (!(sd->sd_send_case & SND_RESP)) {
-               sd->sd_best_lpni =
-                 lnet_find_best_lpni_on_net(sd, sd->sd_peer,
-                                            sd->sd_best_ni->ni_net->net_id);
-       }
-
        if (sd->sd_best_lpni &&
            sd->sd_best_lpni->lpni_nid == the_lnet.ln_loni->ni_nid)
                return lnet_handle_lo_send(sd);