mgr,mgr/MgrClient: use fsid to signal mon-mgr vs cli MCommands

We can't use the feature bit for the MCommand connection to tell whether
it is a tell or CLI command because new clients may have to send CLI
commands via MCommand for old clusters, and they don't always know whether
this mgr is new or old yet.

Prior to octopus, MCommand contained a mon/mgr CLI command, and did not
have the fsid field set.  Start populating the fsid field, and use this
to signal whether a client is a new MgrClient that knows MCommand vs
MMgrCommand.  If we get an MCommand with the fsid set, that means it is
a tell command; otherwise, it's an old client sending a CLI command.

Signed-off-by: Sage Weil <sage@redhat.com>

src/librados/RadosClient.cc

@@ -62,7 +62,7 @@ librados::RadosClient::RadosClient(CephContext *cct_)
     conf(cct_->_conf),
     state(DISCONNECTED),
     monclient(cct_),
-    mgrclient(cct_, nullptr),
+    mgrclient(cct_, nullptr, &monclient.monmap),
     messenger(NULL),
     instance_id(0),
     objecter(NULL),

src/mds/MDSDaemon.cc

@@ -71,7 +71,7 @@ MDSDaemon::MDSDaemon(std::string_view n, Messenger *m, MonClient *mc) :
   name(n),
   messenger(m),
   monc(mc),
-  mgrc(m->cct, m),
+  mgrc(m->cct, m, &mc->monmap),
   log_client(m->cct, messenger, &mc->monmap, LogClient::NO_FLAGS),
   mds_rank(NULL),
   asok_hook(NULL),

src/messages/MMonCommand.h

@@ -22,6 +22,10 @@
 
 class MMonCommand : public PaxosServiceMessage {
 public:
+  // weird note: prior to octopus, MgrClient would leave fsid blank when
+  // sending commands to the mgr.  Starting with octopus, this is either
+  // populated with a valid fsid (tell command) or an MMgrCommand is sent
+  // instead.
   uuid_d fsid;
   std::vector<std::string> cmd;
 

src/mgr/DaemonServer.cc

@@ -791,7 +791,9 @@ public:
 bool DaemonServer::handle_command(const ref_t<MCommand>& m)
 {
   std::lock_guard l(lock);
-  if (HAVE_FEATURE(m->get_connection()->get_features(), SERVER_OCTOPUS)) {
+  // a blank fsid in MCommand signals a legacy client sending a "mon-mgr" CLI
+  // command.
+  if (m->fsid != uuid_d()) {
     cct->get_admin_socket()->queue_tell_command(m);
     return true;
   } else {

src/mgr/MgrClient.cc

@@ -15,6 +15,7 @@
 #include "MgrClient.h"
 
 #include "mgr/MgrContext.h"
+#include "mon/MonMap.h"
 
 #include "msg/Messenger.h"
 #include "messages/MMgrMap.h"
@@ -37,9 +38,12 @@ using ceph::bufferlist;
 #undef dout_prefix
 #define dout_prefix *_dout << "mgrc " << __func__ << " "
 
-MgrClient::MgrClient(CephContext *cct_, Messenger *msgr_)
-    : Dispatcher(cct_), cct(cct_), msgr(msgr_),
-      timer(cct_, lock)
+MgrClient::MgrClient(CephContext *cct_, Messenger *msgr_, MonMap *monmap_)
+  : Dispatcher(cct_),
+    cct(cct_),
+    msgr(msgr_),
+    monmap(monmap_),
+    timer(cct_, lock)
 {
   ceph_assert(cct != nullptr);
 }
@@ -472,7 +476,8 @@ int MgrClient::start_command(const vector<string>& cmd, const bufferlist& inbl,
   op.on_finish = onfinish;
 
   if (session && session->con) {
-    // Leaving fsid argument null because it isn't used.
+    // Leaving fsid argument null because it isn't used historically, and
+    // we can use it as a signal that we are sending a non-tell command.
     auto m = op.get_message(
       {},
       HAVE_FEATURE(map.active_mgr_features, SERVER_OCTOPUS));
@@ -508,10 +513,9 @@ int MgrClient::start_tell_command(
   op.on_finish = onfinish;
 
   if (session && session->con && (name.size() == 0 || map.active_name == name)) {
-    // Leaving fsid argument null because it isn't used.
-    // Note: this simply won't work we pre-octopus mgrs because they route
-    // MCommand to the cluster command handler.
-    auto m = op.get_message({}, false);
+    // Set fsid argument to signal that this is really a tell message (and
+    // we are not a legacy client sending a non-tell command via MCommand).
+    auto m = op.get_message(monmap->fsid, false);
     session->con->send_message2(std::move(m));
   } else {
     ldout(cct, 5) << "no mgr session (no running mgr daemon?), or "

src/mgr/MgrClient.h

@@ -32,6 +32,7 @@ class MMgrClose;
 class Messenger;
 class MCommandReply;
 class MPGStats;
+class MonMap;
 
 class MgrSessionState
 {
@@ -59,6 +60,7 @@ protected:
   CephContext *cct;
   MgrMap map;
   Messenger *msgr;
+  MonMap *monmap;
 
   std::unique_ptr<MgrSessionState> session;
 
@@ -105,7 +107,7 @@ protected:
   bool mgr_optional = false;
 
 public:
-  MgrClient(CephContext *cct_, Messenger *msgr_);
+  MgrClient(CephContext *cct_, Messenger *msgr_, MonMap *monmap);
 
   void set_messenger(Messenger *msgr_) { msgr = msgr_; }
 

src/mgr/MgrStandby.cc

@@ -48,7 +48,7 @@ MgrStandby::MgrStandby(int argc, const char **argv) :
 		     0)),
   objecter{g_ceph_context, client_messenger.get(), &monc, NULL, 0, 0},
   client{client_messenger.get(), &monc, &objecter},
-  mgrc(g_ceph_context, client_messenger.get()),
+  mgrc(g_ceph_context, client_messenger.get(), &monc.monmap),
   log_client(g_ceph_context, client_messenger.get(), &monc.monmap, LogClient::NO_FLAGS),
   clog(log_client.create_channel(CLOG_CHANNEL_CLUSTER)),
   audit_clog(log_client.create_channel(CLOG_CHANNEL_AUDIT)),

src/mon/Monitor.cc

@@ -146,7 +146,7 @@ Monitor::Monitor(CephContext* cct_, string nm, MonitorDBStore *s,
 			cct->_conf->auth_supported.empty() ?
 			cct->_conf->auth_service_required : cct->_conf->auth_supported),
   mgr_messenger(mgr_m),
-  mgr_client(cct_, mgr_m),
+  mgr_client(cct_, mgr_m, monmap),
   gss_ktfile_client(cct->_conf.get_val<std::string>("gss_ktab_client_file")),
   store(s),
   

src/osd/OSD.cc

@@ -2117,7 +2117,7 @@ OSD::OSD(CephContext *cct_, ObjectStore *store_,
   client_messenger(external_messenger),
   objecter_messenger(osdc_messenger),
   monc(mc),
-  mgrc(cct_, client_messenger),
+  mgrc(cct_, client_messenger, &mc->monmap),
   logger(NULL),
   recoverystate_perf(NULL),
   store(store_),