LU-11478 lnet: misleading discovery seqno.

There is a sequence number used when sending discovery messages. This
sequence number is intended to detect stale messages. However it
could be misleading if the peer reboots. In this case the peer's
sequence number will reset. The node will think that all information
being sent to it is stale, while in reality the peer might've
changed configuration.

There is no reliable why to know whether a peer rebooted, so we'll
always assume that the messages we're receiving are valid. So we'll
operate on first come first serve basis.

Lustre-change: https://review.whamcloud.com/33304
Lustre-commit: 42d999ed8f6113724b1ac103b832d5b74b878d55

Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I421a00e47bc93ee60fa37c648d6d9a726d9def9c
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/36041
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lnet/lnet/peer.c b/lnet/lnet/peer.c
index db012f3..1ad2fc2 100644 (file)
--- a/lnet/lnet/peer.c
+++ b/lnet/lnet/peer.c
@@ -1928,38 +1928,9 @@ void lnet_peer_push_event(struct lnet_event *ev)
                goto out;
        }
 
-       /*
-        * Check whether the Put data is stale. Stale data can just be
-        * dropped.
-        */
-       if (pbuf->pb_info.pi_nnis > 1 &&
-           lp->lp_primary_nid == pbuf->pb_info.pi_ni[1].ns_nid &&
-           LNET_PING_BUFFER_SEQNO(pbuf) < lp->lp_peer_seqno) {
-               CDEBUG(D_NET, "Stale Push from %s: got %u have %u\n",
-                      libcfs_nid2str(lp->lp_primary_nid),
-                      LNET_PING_BUFFER_SEQNO(pbuf),
-                      lp->lp_peer_seqno);
-               goto out;
-       }
-
-       /*
-        * Check whether the Put data is new, in which case we clear
-        * the UPTODATE flag and prepare to process it.
-        *
-        * If the Put data is current, and the peer is UPTODATE then
-        * we assome everything is all right and drop the data as
-        * stale.
-        */
-       if (LNET_PING_BUFFER_SEQNO(pbuf) > lp->lp_peer_seqno) {
-               lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
-               lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
-       } else if (lp->lp_state & LNET_PEER_NIDS_UPTODATE) {
-               CDEBUG(D_NET, "Stale Push from %s: got %u have %u\n",
-                      libcfs_nid2str(lp->lp_primary_nid),
-                      LNET_PING_BUFFER_SEQNO(pbuf),
-                      lp->lp_peer_seqno);
-               goto out;
-       }
+       /* always assume new data */
+       lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
+       lp->lp_state &= ~LNET_PEER_NIDS_UPTODATE;
 
        /*
         * If there is data present that hasn't been processed yet,
@@ -2244,16 +2215,13 @@ lnet_discovery_event_reply(struct lnet_peer *lp, struct lnet_event *ev)
        if (pbuf->pb_info.pi_features & LNET_PING_FEAT_MULTI_RAIL &&
            pbuf->pb_info.pi_nnis > 1 &&
            lp->lp_primary_nid == pbuf->pb_info.pi_ni[1].ns_nid) {
-               if (LNET_PING_BUFFER_SEQNO(pbuf) < lp->lp_peer_seqno) {
-                       CDEBUG(D_NET, "Stale Reply from %s: got %u have %u\n",
+               if (LNET_PING_BUFFER_SEQNO(pbuf) < lp->lp_peer_seqno)
+                       CDEBUG(D_NET, "peer %s: seq# got %u have %u. peer rebooted?\n",
                                libcfs_nid2str(lp->lp_primary_nid),
                                LNET_PING_BUFFER_SEQNO(pbuf),
                                lp->lp_peer_seqno);
-                       goto out;
-               }
 
-               if (LNET_PING_BUFFER_SEQNO(pbuf) > lp->lp_peer_seqno)
-                       lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
+               lp->lp_peer_seqno = LNET_PING_BUFFER_SEQNO(pbuf);
        }
 
        /* We're happy with the state of the data in the buffer. */