Merge PR #36359 into master

* refs/pull/36359/head:
	mds: place MDSGatherBuilder on the stack

Reviewed-by: Zheng Yan <zyan@redhat.com>

src/mds/MDSRank.cc

@@ -151,26 +151,25 @@ private:
     dout(20) << __func__ << dendl;
 
     // Attach contexts to wait for all expiring segments to expire
-    MDSGatherBuilder *expiry_gather = new MDSGatherBuilder(g_ceph_context);
+    MDSGatherBuilder expiry_gather(g_ceph_context);
 
     const auto &expiring_segments = mdlog->get_expiring_segments();
     for (auto p : expiring_segments) {
-      p->wait_for_expiry(expiry_gather->new_sub());
+      p->wait_for_expiry(expiry_gather.new_sub());
     }
-    dout(5) << __func__ << ": waiting for " << expiry_gather->num_subs_created()
+    dout(5) << __func__ << ": waiting for " << expiry_gather.num_subs_created()
             << " segments to expire" << dendl;
 
-    if (!expiry_gather->has_subs()) {
+    if (!expiry_gather.has_subs()) {
       trim_segments();
-      delete expiry_gather;
       return;
     }
 
     Context *ctx = new LambdaContext([this](int r) {
         handle_expire_segments(r);
       });
-    expiry_gather->set_finisher(new MDSInternalContextWrapper(mds, ctx));
-    expiry_gather->activate();
+    expiry_gather.set_finisher(new MDSInternalContextWrapper(mds, ctx));
+    expiry_gather.activate();
   }
 
   void handle_expire_segments(int r) {
@@ -331,9 +330,9 @@ private:
     auto now = mono_clock::now();
     auto duration = std::chrono::duration<double>(now-recall_start).count();
 
-    MDSGatherBuilder *gather = new MDSGatherBuilder(g_ceph_context);
+    MDSGatherBuilder gather(g_ceph_context);
     auto flags = Server::RecallFlags::STEADY|Server::RecallFlags::TRIM;
-    auto [throttled, count] = server->recall_client_state(gather, flags);
+    auto [throttled, count] = server->recall_client_state(&gather, flags);
     dout(10) << __func__
              << (throttled ? " (throttled)" : "")
              << " recalled " << count << " caps" << dendl;
@@ -345,17 +344,16 @@ private:
           recall_client_state();
       }));
       ctx->start_timer();
-      gather->set_finisher(new MDSInternalContextWrapper(mds, ctx));
-      gather->activate();
+      gather.set_finisher(new MDSInternalContextWrapper(mds, ctx));
+      gather.activate();
       mdlog->flush(); /* use down-time to incrementally flush log */
       do_trim(); /* use down-time to incrementally trim cache */
     } else {
-      if (!gather->has_subs()) {
-        delete gather;
+      if (!gather.has_subs()) {
         return handle_recall_client_state(0);
       } else if (recall_timeout > 0 && duration > recall_timeout) {
-        gather->set_finisher(new C_MDSInternalNoop);
-        gather->activate();
+        gather.set_finisher(new C_MDSInternalNoop);
+        gather.activate();
         return handle_recall_client_state(-ETIMEDOUT);
       } else {
         uint64_t remaining = (recall_timeout == 0 ? 0 : recall_timeout-duration);
@@ -365,8 +363,8 @@ private:
             }));
 
         ctx->start_timer();
-        gather->set_finisher(new MDSInternalContextWrapper(mds, ctx));
-        gather->activate();
+        gather.set_finisher(new MDSInternalContextWrapper(mds, ctx));
+        gather.activate();
       }
     }
   }

src/mds/Server.cc

@@ -741,24 +741,24 @@ void Server::handle_client_session(const cref_t<MClientSession> &m)
   }
 }
 
-void Server::flush_session(Session *session, MDSGatherBuilder *gather) {
+void Server::flush_session(Session *session, MDSGatherBuilder& gather) {
   if (!session->is_open() ||
       !session->get_connection() ||
       !session->get_connection()->has_feature(CEPH_FEATURE_EXPORT_PEER)) {
     return;
   }
 
-  version_t seq = session->wait_for_flush(gather->new_sub());
+  version_t seq = session->wait_for_flush(gather.new_sub());
   mds->send_message_client(
     make_message<MClientSession>(CEPH_SESSION_FLUSHMSG, seq), session);
 }
 
 void Server::flush_client_sessions(set<client_t>& client_set, MDSGatherBuilder& gather)
 {
-  for (set<client_t>::iterator p = client_set.begin(); p != client_set.end(); ++p) {
-    Session *session = mds->sessionmap.get_session(entity_name_t::CLIENT(p->v));
+  for (const auto& client : client_set) {
+    Session *session = mds->sessionmap.get_session(entity_name_t::CLIENT(client.v));
     ceph_assert(session);
-    flush_session(session, &gather);
+    flush_session(session, gather);
   }
 }
 
@@ -1814,7 +1814,7 @@ std::pair<bool, uint64_t> Server::recall_client_state(MDSGatherBuilder* gather,
       m->head.max_caps = newlim;
       mds->send_message_client(m, session);
       if (gather) {
-        flush_session(session, gather);
+        flush_session(session, *gather);
       }
       caps_recalled += session->notify_recall_sent(newlim);
       recall_throttle.hit(recall);

src/mds/Server.h

@@ -319,7 +319,7 @@ private:
   friend class Batch_Getattr_Lookup;
 
   void reply_client_request(MDRequestRef& mdr, const ref_t<MClientReply> &reply);
-  void flush_session(Session *session, MDSGatherBuilder *gather);
+  void flush_session(Session *session, MDSGatherBuilder& gather);
 
   MDSRank *mds;
   MDCache *mdcache;