LU-6808 ptlrpc: no need to reassign mbits for replay

It's not necessary reassgin & re-adjust rq_mbits for replay
request in ptlrpc_set_bulk_mbits(), they all must have already
been correctly assigned before.

Such unecessary reassign could make the first matchbit not
PTLRPC_BULK_OPS_MASK aligned, that'll trigger LASSERT in
ptlrpc_register_bulk():

- ptlrpc_set_bulk_mbits() is called when first time sending
  request, rq_mbits is set as xid, which is BULK_OPS aligned;

- ptlrpc_set_bulk_mbits() continue to adjust the mbits for
  multi-bulk RPC, rq_mbits is not aligned anymore, then rq_xid
  is changed accordingly if client is connecting to an old
  server, so rq_xid became unaligned too;

- The request is replayed, ptlrpc_set_bulk_mbits() reassign
  the rq_mbits as rq_xid, which isn't aligned already, but
  ptlrpc_register_bulk() still assumes this value as the
  first matchbits and LASSERT it's BULK_OPS aligned.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: Ib5d5a969702d3b621fb44643586cc19bf931c365
Reviewed-on: http://review.whamcloud.com/23048
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/ptlrpc/client.c b/lustre/ptlrpc/client.c
index f340fc2..1541b2e 100644 (file)
--- a/lustre/ptlrpc/client.c
+++ b/lustre/ptlrpc/client.c
@@ -3240,24 +3240,36 @@ void ptlrpc_set_bulk_mbits(struct ptlrpc_request *req)
 
        LASSERT(bd != NULL);
 
-       if (!req->rq_resend) {
-               /* this request has a new xid, just use it as bulk matchbits */
-               req->rq_mbits = req->rq_xid;
-
-       } else { /* needs to generate a new matchbits for resend */
-               __u64   old_mbits = req->rq_mbits;
-
+       /* Generate new matchbits for all resend requests, including
+        * resend replay. */
+       if (req->rq_resend) {
+               __u64 old_mbits = req->rq_mbits;
+
+               /* First time resend on -EINPROGRESS will generate new xid,
+                * so we can actually use the rq_xid as rq_mbits in such case,
+                * however, it's bit hard to distinguish such resend with a
+                * 'resend for the -EINPROGRESS resend'. To make it simple,
+                * we opt to generate mbits for all resend cases. */
                if (OCD_HAS_FLAG(&bd->bd_import->imp_connect_data, BULK_MBITS)){
                        req->rq_mbits = ptlrpc_next_xid();
-               } else {/* old version transfers rq_xid to peer as matchbits */
+               } else {
+                       /* Old version transfers rq_xid to peer as
+                        * matchbits. */
                        spin_lock(&req->rq_import->imp_lock);
                        list_del_init(&req->rq_unreplied_list);
                        ptlrpc_assign_next_xid_nolock(req);
-                       req->rq_mbits = req->rq_xid;
                        spin_unlock(&req->rq_import->imp_lock);
+                       req->rq_mbits = req->rq_xid;
                }
                CDEBUG(D_HA, "resend bulk old x%llu new x%llu\n",
                       old_mbits, req->rq_mbits);
+       } else if (!(lustre_msg_get_flags(req->rq_reqmsg) & MSG_REPLAY)) {
+               /* Request being sent first time, use xid as matchbits. */
+               req->rq_mbits = req->rq_xid;
+       } else {
+               /* Replay request, xid and matchbits have already been
+                * correctly assigned. */
+               return;
        }
 
        /* For multi-bulk RPCs, rq_mbits is the last mbits needed for bulks so
@@ -3267,7 +3279,10 @@ void ptlrpc_set_bulk_mbits(struct ptlrpc_request *req)
                          LNET_MAX_IOV) - 1;
 
        /* Set rq_xid as rq_mbits to indicate the final bulk for the old
-        * server which does not support OBD_CONNECT_BULK_MBITS. LU-6808 */
+        * server which does not support OBD_CONNECT_BULK_MBITS. LU-6808.
+        *
+        * It's ok to directly set the rq_xid here, since this xid bump
+        * won't affect the request position in unreplied list. */
        if (!OCD_HAS_FLAG(&bd->bd_import->imp_connect_data, BULK_MBITS))
                req->rq_xid = req->rq_mbits;
 }