mon/MDSMonitor: plug paxos when maybe manipulating the osdmap

Instead of tracking where exactly we're plugging PAXOS, just do it
unconditionally whenever we modify pending and may change the osdmap.
There is no downside to doing so; it simplifies the code.

Fixes: https://tracker.ceph.com/issues/59314
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

Author: batrick

src/mon/FSCommands.cc

@@ -146,10 +146,6 @@ class FsNewHandler : public FileSystemCommandHandler
   {
   }
 
-  bool batched_propose() override {
-    return true;
-  }
-
   int handle(
       Monitor *mon,
       FSMap& fsmap,
@@ -934,10 +930,6 @@ class AddDataPoolHandler : public FileSystemCommandHandler
     : FileSystemCommandHandler("fs add_data_pool"), m_paxos(paxos)
   {}
 
-  bool batched_propose() override {
-    return true;
-  }
-
   int handle(
       Monitor *mon,
       FSMap& fsmap,
@@ -1159,10 +1151,6 @@ class RenameFilesystemHandler : public FileSystemCommandHandler
   {
   }
 
-  bool batched_propose() override {
-    return true;
-  }
-
   int handle(
       Monitor *mon,
       FSMap& fsmap,

src/mon/FSCommands.h

@@ -79,10 +79,6 @@ class FileSystemCommandHandler : protected CommandHandler
 
   static std::list<std::shared_ptr<FileSystemCommandHandler> > load(Paxos *paxos);
 
-  virtual bool batched_propose() {
-    return false;
-  }
-
   virtual int handle(
     Monitor *mon,
     FSMap &fsmap,

src/mon/MDSMonitor.cc

@@ -550,28 +550,35 @@ bool MDSMonitor::prepare_update(MonOpRequestRef op)
   auto m = op->get_req<PaxosServiceMessage>();
   dout(7) << "prepare_update " << *m << dendl;
 
-  switch (m->get_type()) {
-    
-  case MSG_MDS_BEACON:
-    return prepare_beacon(op);
+  bool r = false;
 
-  case MSG_MON_COMMAND:
-    try {
-      return prepare_command(op);
-    } catch (const bad_cmd_get& e) {
-      bufferlist bl;
-      mon.reply_command(op, -EINVAL, e.what(), bl, get_last_committed());
-      return false; /* nothing to propose */
-    }
+  /* batch any changes to pending with any changes to osdmap */
+  paxos.plug();
 
-  case MSG_MDS_OFFLOAD_TARGETS:
-    return prepare_offload_targets(op);
-  
-  default:
-    ceph_abort();
+  switch (m->get_type()) {
+    case MSG_MDS_BEACON:
+      r = prepare_beacon(op);
+      break;
+    case MSG_MON_COMMAND:
+      try {
+        r = prepare_command(op);
+      } catch (const bad_cmd_get& e) {
+        bufferlist bl;
+        mon.reply_command(op, -EINVAL, e.what(), bl, get_last_committed());
+        r = false;
+      }
+      break;
+    case MSG_MDS_OFFLOAD_TARGETS:
+      r = prepare_offload_targets(op);
+      break;
+    default:
+      ceph_abort();
+      break;
   }
 
-  return false; /* nothing to propose! */
+  paxos.unplug();
+
+  return r;
 }
 
 bool MDSMonitor::prepare_beacon(MonOpRequestRef op)
@@ -1389,7 +1396,6 @@ bool MDSMonitor::prepare_command(MonOpRequestRef op)
 
   auto &pending = get_pending_fsmap_writeable();
 
-  bool batched_propose = false;
   for (const auto &h : handlers) {
     r = h->can_handle(prefix, op, pending, cmdmap, ss);
     if (r == 1) {
@@ -1400,14 +1406,7 @@ bool MDSMonitor::prepare_command(MonOpRequestRef op)
       goto out;
     }
 
-    batched_propose = h->batched_propose();
-    if (batched_propose) {
-      paxos.plug();
-    }
     r = h->handle(&mon, pending, op, cmdmap, ss);
-    if (batched_propose) {
-      paxos.unplug();
-    }
 
     if (r == -EAGAIN) {
       // message has been enqueued for retry; return.
@@ -1448,9 +1447,6 @@ bool MDSMonitor::prepare_command(MonOpRequestRef op)
     // success.. delay reply
     wait_for_finished_proposal(op, new Monitor::C_Command(mon, op, r, rs,
 					      get_last_committed() + 1));
-    if (batched_propose) {
-      force_immediate_propose();
-    }
     return true;
   } else {
     // reply immediately
@@ -2321,6 +2317,9 @@ void MDSMonitor::tick()
 
   auto &pending = get_pending_fsmap_writeable();
 
+  /* batch any changes to pending with any changes to osdmap */
+  paxos.plug();
+
   bool do_propose = false;
   bool propose_osdmap = false;
 
@@ -2376,6 +2375,9 @@ void MDSMonitor::tick()
     request_proposal(mon.osdmon());
   }
 
+  /* allow MDSMonitor::propose_pending() to push the proposal through */
+  paxos.unplug();
+
   if (do_propose) {
     propose_pending();
   }