Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1146 insertions, 0 deletions

diff --git a/src/mds/MDSMap.cc b/src/mds/MDSMap.cc
new file mode 100644
index 000000000..f611d86a5
--- /dev/null
+++ b/src/mds/MDSMap.cc
@@ -0,0 +1,1146 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- 
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software 
+ * Foundation.  See file COPYING.
+ * 
+ */
+
+#include <ostream>
+
+#include "common/debug.h"
+#include "mon/health_check.h"
+
+#include "MDSMap.h"
+
+using std::dec;
+using std::hex;
+using std::list;
+using std::make_pair;
+using std::map;
+using std::multimap;
+using std::ostream;
+using std::pair;
+using std::string;
+using std::set;
+
+using ceph::bufferlist;
+using ceph::Formatter;
+
+#define dout_context g_ceph_context
+#define dout_subsys ceph_subsys_
+
+// features
+CompatSet MDSMap::get_compat_set_all() {
+  CompatSet::FeatureSet feature_compat;
+  CompatSet::FeatureSet feature_ro_compat;
+  CompatSet::FeatureSet feature_incompat;
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_BASE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_CLIENTRANGES);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILELAYOUT);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_DIRINODE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_ENCODING);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_OMAPDIRFRAG);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_INLINE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_NOANCHOR);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILE_LAYOUT_V2);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_SNAPREALM_V2);
+
+  return CompatSet(feature_compat, feature_ro_compat, feature_incompat);
+}
+
+CompatSet MDSMap::get_compat_set_default() {
+  CompatSet::FeatureSet feature_compat;
+  CompatSet::FeatureSet feature_ro_compat;
+  CompatSet::FeatureSet feature_incompat;
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_BASE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_CLIENTRANGES);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILELAYOUT);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_DIRINODE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_ENCODING);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_OMAPDIRFRAG);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_NOANCHOR);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILE_LAYOUT_V2);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_SNAPREALM_V2);
+
+  return CompatSet(feature_compat, feature_ro_compat, feature_incompat);
+}
+
+// base (pre v0.20)
+CompatSet MDSMap::get_compat_set_base() {
+  CompatSet::FeatureSet feature_compat_base;
+  CompatSet::FeatureSet feature_incompat_base;
+  feature_incompat_base.insert(MDS_FEATURE_INCOMPAT_BASE);
+  CompatSet::FeatureSet feature_ro_compat_base;
+
+  return CompatSet(feature_compat_base, feature_ro_compat_base, feature_incompat_base);
+}
+
+// pre-v16.2.5 CompatSet in MDS beacon
+CompatSet MDSMap::get_compat_set_v16_2_4() {
+  CompatSet::FeatureSet feature_compat;
+  CompatSet::FeatureSet feature_ro_compat;
+  CompatSet::FeatureSet feature_incompat;
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_BASE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_CLIENTRANGES);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILELAYOUT);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_DIRINODE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_ENCODING);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_OMAPDIRFRAG);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_INLINE);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_NOANCHOR);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_FILE_LAYOUT_V2);
+  feature_incompat.insert(MDS_FEATURE_INCOMPAT_SNAPREALM_V2);
+  return CompatSet(feature_compat, feature_ro_compat, feature_incompat);
+}
+
+void MDSMap::mds_info_t::dump(Formatter *f) const
+{
+  f->dump_unsigned("gid", global_id);
+  f->dump_string("name", name);
+  f->dump_int("rank", rank);
+  f->dump_int("incarnation", inc);
+  f->dump_stream("state") << ceph_mds_state_name(state);
+  f->dump_int("state_seq", state_seq);
+  f->dump_stream("addr") << addrs.get_legacy_str();
+  f->dump_object("addrs", addrs);
+  f->dump_int("join_fscid", join_fscid);
+  if (laggy_since != utime_t())
+    f->dump_stream("laggy_since") << laggy_since;
+  
+  f->open_array_section("export_targets");
+  for (set<mds_rank_t>::iterator p = export_targets.begin();
+       p != export_targets.end(); ++p) {
+    f->dump_int("mds", *p);
+  }
+  f->close_section();
+  f->dump_unsigned("features", mds_features);
+  f->dump_unsigned("flags", flags);
+  f->dump_object("compat", compat);
+}
+
+void MDSMap::mds_info_t::dump(std::ostream& o) const
+{
+  o << "[mds." << name << "{" <<  rank << ":" << global_id << "}"
+       << " state " << ceph_mds_state_name(state)
+       << " seq " << state_seq;
+  if (laggy()) {
+    o << " laggy since " << laggy_since;
+  }
+  if (!export_targets.empty()) {
+    o << " export targets " << export_targets;
+  }
+  if (is_frozen()) {
+    o << " frozen";
+  }
+  if (join_fscid != FS_CLUSTER_ID_NONE) {
+    o << " join_fscid=" << join_fscid;
+  }
+  o << " addr " << addrs;
+  o << " compat ";
+  compat.printlite(o);
+  o << "]";
+}
+
+void MDSMap::mds_info_t::generate_test_instances(std::list<mds_info_t*>& ls)
+{
+  mds_info_t *sample = new mds_info_t();
+  ls.push_back(sample);
+  sample = new mds_info_t();
+  sample->global_id = 1;
+  sample->name = "test_instance";
+  sample->rank = 0;
+  ls.push_back(sample);
+}
+
+void MDSMap::dump(Formatter *f) const
+{
+  f->dump_int("epoch", epoch);
+  f->dump_unsigned("flags", flags);
+  f->dump_unsigned("ever_allowed_features", ever_allowed_features);
+  f->dump_unsigned("explicitly_allowed_features", explicitly_allowed_features);
+  f->dump_stream("created") << created;
+  f->dump_stream("modified") << modified;
+  f->dump_int("tableserver", tableserver);
+  f->dump_int("root", root);
+  f->dump_int("session_timeout", session_timeout);
+  f->dump_int("session_autoclose", session_autoclose);
+  f->open_object_section("required_client_features");
+  cephfs_dump_features(f, required_client_features);
+  f->close_section();
+  f->dump_int("max_file_size", max_file_size);
+  f->dump_int("last_failure", last_failure);
+  f->dump_int("last_failure_osd_epoch", last_failure_osd_epoch);
+  f->open_object_section("compat");
+  compat.dump(f);
+  f->close_section();
+  f->dump_int("max_mds", max_mds);
+  f->open_array_section("in");
+  for (set<mds_rank_t>::const_iterator p = in.begin(); p != in.end(); ++p)
+    f->dump_int("mds", *p);
+  f->close_section();
+  f->open_object_section("up");
+  for (map<mds_rank_t,mds_gid_t>::const_iterator p = up.begin(); p != up.end(); ++p) {
+    char s[14];
+    sprintf(s, "mds_%d", int(p->first));
+    f->dump_int(s, p->second);
+  }
+  f->close_section();
+  f->open_array_section("failed");
+  for (set<mds_rank_t>::const_iterator p = failed.begin(); p != failed.end(); ++p)
+    f->dump_int("mds", *p);
+  f->close_section();
+  f->open_array_section("damaged");
+  for (set<mds_rank_t>::const_iterator p = damaged.begin(); p != damaged.end(); ++p)
+    f->dump_int("mds", *p);
+  f->close_section();
+  f->open_array_section("stopped");
+  for (set<mds_rank_t>::const_iterator p = stopped.begin(); p != stopped.end(); ++p)
+    f->dump_int("mds", *p);
+  f->close_section();
+  f->open_object_section("info");
+  for (const auto& [gid, info] : mds_info) {
+    char s[25]; // 'gid_' + len(str(ULLONG_MAX)) + '\0'
+    sprintf(s, "gid_%llu", (long long unsigned)gid);
+    f->open_object_section(s);
+    info.dump(f);
+    f->close_section();
+  }
+  f->close_section();
+  f->open_array_section("data_pools");
+  for (const auto& p: data_pools)
+    f->dump_int("pool", p);
+  f->close_section();
+  f->dump_int("metadata_pool", metadata_pool);
+  f->dump_bool("enabled", enabled);
+  f->dump_string("fs_name", fs_name);
+  f->dump_string("balancer", balancer);
+  f->dump_int("standby_count_wanted", std::max(0, standby_count_wanted));
+}
+
+void MDSMap::generate_test_instances(std::list<MDSMap*>& ls)
+{
+  MDSMap *m = new MDSMap();
+  m->max_mds = 1;
+  m->data_pools.push_back(0);
+  m->metadata_pool = 1;
+  m->cas_pool = 2;
+  m->compat = get_compat_set_all();
+
+  // these aren't the defaults, just in case anybody gets confused
+  m->session_timeout = 61;
+  m->session_autoclose = 301;
+  m->max_file_size = 1<<24;
+  ls.push_back(m);
+}
+
+void MDSMap::print(ostream& out) const
+{
+  out << "fs_name\t" << fs_name << "\n";
+  out << "epoch\t" << epoch << "\n";
+  out << "flags\t" << hex << flags << dec << "\n";
+  out << "created\t" << created << "\n";
+  out << "modified\t" << modified << "\n";
+  out << "tableserver\t" << tableserver << "\n";
+  out << "root\t" << root << "\n";
+  out << "session_timeout\t" << session_timeout << "\n"
+      << "session_autoclose\t" << session_autoclose << "\n";
+  out << "max_file_size\t" << max_file_size << "\n";
+  out << "required_client_features\t" << cephfs_stringify_features(required_client_features) << "\n";
+  out << "last_failure\t" << last_failure << "\n"
+      << "last_failure_osd_epoch\t" << last_failure_osd_epoch << "\n";
+  out << "compat\t" << compat << "\n";
+  out << "max_mds\t" << max_mds << "\n";
+  out << "in\t" << in << "\n"
+      << "up\t" << up << "\n"
+      << "failed\t" << failed << "\n"
+      << "damaged\t" << damaged << "\n"
+      << "stopped\t" << stopped << "\n";
+  out << "data_pools\t" << data_pools << "\n";
+  out << "metadata_pool\t" << metadata_pool << "\n";
+  out << "inline_data\t" << (inline_data_enabled ? "enabled" : "disabled") << "\n";
+  out << "balancer\t" << balancer << "\n";
+  out << "standby_count_wanted\t" << std::max(0, standby_count_wanted) << "\n";
+
+  multimap< pair<mds_rank_t, unsigned>, mds_gid_t > foo;
+  for (const auto &p : mds_info) {
+    foo.insert(std::make_pair(
+          std::make_pair(p.second.rank, p.second.inc-1), p.first));
+  }
+
+  for (const auto &p : foo) {
+    out << mds_info.at(p.second) << "\n";
+  }
+}
+
+void MDSMap::print_summary(Formatter *f, ostream *out) const
+{
+  map<mds_rank_t,string> by_rank;
+  map<string,int> by_state;
+
+  if (f) {
+    f->dump_unsigned("epoch", get_epoch());
+    f->dump_unsigned("up", up.size());
+    f->dump_unsigned("in", in.size());
+    f->dump_unsigned("max", max_mds);
+  } else {
+    *out << "e" << get_epoch() << ": " << up.size() << "/" << in.size() << "/" << max_mds << " up";
+  }
+
+  if (f)
+    f->open_array_section("by_rank");
+  for (const auto &p : mds_info) {
+    string s = ceph_mds_state_name(p.second.state);
+    if (p.second.laggy())
+      s += "(laggy or crashed)";
+
+    if (p.second.rank >= 0 && p.second.state != MDSMap::STATE_STANDBY_REPLAY) {
+      if (f) {
+	f->open_object_section("mds");
+	f->dump_unsigned("rank", p.second.rank);
+	f->dump_string("name", p.second.name);
+	f->dump_string("status", s);
+	f->close_section();
+      } else {
+	by_rank[p.second.rank] = p.second.name + "=" + s;
+      }
+    } else {
+      by_state[s]++;
+    }
+  }
+  if (f) {
+    f->close_section();
+  } else {
+    if (!by_rank.empty())
+      *out << " " << by_rank;
+  }
+
+  for (map<string,int>::reverse_iterator p = by_state.rbegin(); p != by_state.rend(); ++p) {
+    if (f) {
+      f->dump_unsigned(p->first.c_str(), p->second);
+    } else {
+      *out << ", " << p->second << " " << p->first;
+    }
+  }
+
+  if (!failed.empty()) {
+    if (f) {
+      f->dump_unsigned("failed", failed.size());
+    } else {
+      *out << ", " << failed.size() << " failed";
+    }
+  }
+
+  if (!damaged.empty()) {
+    if (f) {
+      f->dump_unsigned("damaged", damaged.size());
+    } else {
+      *out << ", " << damaged.size() << " damaged";
+    }
+  }
+  //if (stopped.size())
+  //out << ", " << stopped.size() << " stopped";
+}
+
+void MDSMap::get_health(list<pair<health_status_t,string> >& summary,
+			list<pair<health_status_t,string> > *detail) const
+{
+  if (!failed.empty()) {
+    CachedStackStringStream css;
+    *css << "mds rank"
+	<< ((failed.size() > 1) ? "s ":" ")
+	<< failed
+	<< ((failed.size() > 1) ? " have":" has")
+	<< " failed";
+    summary.push_back(make_pair(HEALTH_ERR, css->str()));
+    if (detail) {
+      for (const auto& r : failed) {
+        CachedStackStringStream css;
+	*css << "mds." << r << " has failed";
+	detail->push_back(make_pair(HEALTH_ERR, css->str()));
+      }
+    }
+  }
+
+  if (!damaged.empty()) {
+    CachedStackStringStream css;
+    *css << "mds rank"
+	 << ((damaged.size() > 1) ? "s ":" ")
+	 << damaged
+	 << ((damaged.size() > 1) ? " are":" is")
+	 << " damaged";
+    summary.push_back(make_pair(HEALTH_ERR, css->str()));
+    if (detail) {
+      for (const auto& r : damaged) {
+        CachedStackStringStream css;
+	*css << "mds." << r << " is damaged";
+	detail->push_back(make_pair(HEALTH_ERR, css->str()));
+      }
+    }
+  }
+
+  if (is_degraded()) {
+    summary.push_back(make_pair(HEALTH_WARN, "mds cluster is degraded"));
+    if (detail) {
+      detail->push_back(make_pair(HEALTH_WARN, "mds cluster is degraded"));
+      for (mds_rank_t i = mds_rank_t(0); i< get_max_mds(); i++) {
+	if (!is_up(i))
+	  continue;
+	mds_gid_t gid = up.find(i)->second;
+	const auto& info = mds_info.at(gid);
+        CachedStackStringStream css;
+	if (is_resolve(i))
+	  *css << "mds." << info.name << " at " << info.addrs
+	     << " rank " << i << " is resolving";
+	if (is_replay(i))
+	  *css << "mds." << info.name << " at " << info.addrs
+	     << " rank " << i << " is replaying journal";
+	if (is_rejoin(i))
+	  *css << "mds." << info.name << " at " << info.addrs
+	     << " rank " << i << " is rejoining";
+	if (is_reconnect(i))
+	  *css << "mds." << info.name << " at " << info.addrs
+	     << " rank " << i << " is reconnecting to clients";
+	if (css->strv().length())
+	  detail->push_back(make_pair(HEALTH_WARN, css->str()));
+      }
+    }
+  }
+
+  {
+    CachedStackStringStream css;
+    *css << fs_name << " max_mds " << max_mds;
+    summary.push_back(make_pair(HEALTH_WARN, css->str()));
+  }
+
+  if ((mds_rank_t)up.size() < max_mds) {
+    CachedStackStringStream css;
+    *css << fs_name << " has " << up.size()
+         << " active MDS(s), but has max_mds of " << max_mds;
+    summary.push_back(make_pair(HEALTH_WARN, css->str()));
+  }
+
+  set<string> laggy;
+  for (const auto &u : up) {
+    const auto& info = mds_info.at(u.second);
+    if (info.laggy()) {
+      laggy.insert(info.name);
+      if (detail) {
+        CachedStackStringStream css;
+	*css << "mds." << info.name << " at " << info.addrs
+	    << " is laggy/unresponsive";
+	detail->push_back(make_pair(HEALTH_WARN, css->str()));
+      }
+    }
+  }
+
+  if (!laggy.empty()) {
+    CachedStackStringStream css;
+    *css << "mds " << laggy
+	 << ((laggy.size() > 1) ? " are":" is")
+	 << " laggy";
+    summary.push_back(make_pair(HEALTH_WARN, css->str()));
+  }
+
+  if (get_max_mds() > 1 &&
+      was_snaps_ever_allowed() && !allows_multimds_snaps()) {
+    CachedStackStringStream css;
+    *css << "multi-active mds while there are snapshots possibly created by pre-mimic MDS";
+    summary.push_back(make_pair(HEALTH_WARN, css->str()));
+  }
+}
+
+void MDSMap::get_health_checks(health_check_map_t *checks) const
+{
+  // MDS_DAMAGE
+  if (!damaged.empty()) {
+    health_check_t& check = checks->get_or_add("MDS_DAMAGE", HEALTH_ERR,
+					       "%num% mds daemon%plurals% damaged",
+					       damaged.size());
+    for (const auto& p : damaged) {
+      CachedStackStringStream css;
+      *css << "fs " << fs_name << " mds." << p << " is damaged";
+      check.detail.push_back(css->str());
+    }
+  }
+
+  // FS_DEGRADED
+  if (is_degraded()) {
+    health_check_t& fscheck = checks->get_or_add(
+      "FS_DEGRADED", HEALTH_WARN,
+      "%num% filesystem%plurals% %isorare% degraded", 1);
+    CachedStackStringStream css;
+    *css << "fs " << fs_name << " is degraded";
+    fscheck.detail.push_back(css->str());
+
+    list<string> detail;
+    for (mds_rank_t i = mds_rank_t(0); i< get_max_mds(); i++) {
+      if (!is_up(i))
+	continue;
+      mds_gid_t gid = up.find(i)->second;
+      const auto& info = mds_info.at(gid);
+      CachedStackStringStream css;
+      *css << "fs " << fs_name << " mds." << info.name << " at "
+	 << info.addrs << " rank " << i;
+      if (is_resolve(i))
+	*css << " is resolving";
+      if (is_replay(i))
+	*css << " is replaying journal";
+      if (is_rejoin(i))
+	*css << " is rejoining";
+      if (is_reconnect(i))
+	*css << " is reconnecting to clients";
+      if (css->strv().length())
+	detail.push_back(css->str());
+    }
+  }
+
+  // MDS_UP_LESS_THAN_MAX
+  if ((mds_rank_t)get_num_in_mds() < get_max_mds()) {
+    health_check_t& check = checks->add(
+      "MDS_UP_LESS_THAN_MAX", HEALTH_WARN,
+      "%num% filesystem%plurals% %isorare% online with fewer MDS than max_mds", 1);
+    CachedStackStringStream css;
+    *css << "fs " << fs_name << " has " << get_num_in_mds()
+         << " MDS online, but wants " << get_max_mds();
+    check.detail.push_back(css->str());
+  }
+
+  // MDS_ALL_DOWN
+  if ((mds_rank_t)get_num_up_mds() == 0 && get_max_mds() > 0) {
+    health_check_t &check = checks->add(
+      "MDS_ALL_DOWN", HEALTH_ERR,
+      "%num% filesystem%plurals% %isorare% offline", 1);
+    CachedStackStringStream css;
+    *css << "fs " << fs_name << " is offline because no MDS is active for it.";
+    check.detail.push_back(css->str());
+  }
+
+  if (get_max_mds() > 1 &&
+      was_snaps_ever_allowed() && !allows_multimds_snaps()) {
+    health_check_t &check = checks->add(
+      "MULTIMDS_WITH_OLDSNAPS", HEALTH_ERR,
+      "%num% filesystem%plurals% %isorare% multi-active mds with old snapshots", 1);
+    CachedStackStringStream css;
+    *css << "multi-active mds while there are snapshots possibly created by pre-mimic MDS";
+    check.detail.push_back(css->str());
+  }
+
+  if (get_inline_data_enabled()) {
+    health_check_t &check = checks->add(
+      "FS_INLINE_DATA_DEPRECATED", HEALTH_WARN,
+      "%num% filesystem%plurals% with deprecated feature inline_data", 1);
+    CachedStackStringStream css;
+    *css << "fs " << fs_name << " has deprecated feature inline_data enabled.";
+    check.detail.push_back(css->str());
+  }
+}
+
+void MDSMap::mds_info_t::encode_versioned(bufferlist& bl, uint64_t features) const
+{
+  __u8 v = 10;
+  if (!HAVE_FEATURE(features, SERVER_NAUTILUS)) {
+    v = 7;
+  }
+  ENCODE_START(v, 4, bl);
+  encode(global_id, bl);
+  encode(name, bl);
+  encode(rank, bl);
+  encode(inc, bl);
+  encode((int32_t)state, bl);
+  encode(state_seq, bl);
+  if (v < 8) {
+    encode(addrs.legacy_addr(), bl, features);
+  } else {
+    encode(addrs, bl, features);
+  }
+  encode(laggy_since, bl);
+  encode(MDS_RANK_NONE, bl); /* standby_for_rank */
+  encode(std::string(), bl); /* standby_for_name */
+  encode(export_targets, bl);
+  encode(mds_features, bl);
+  encode(join_fscid, bl); /* formerly: standby_for_fscid */
+  encode(false, bl);
+  if (v >= 9) {
+    encode(flags, bl);
+  }
+  if (v >= 10) {
+    encode(compat, bl);
+  }
+  ENCODE_FINISH(bl);
+}
+
+void MDSMap::mds_info_t::encode_unversioned(bufferlist& bl) const
+{
+  __u8 struct_v = 3;
+  using ceph::encode;
+  encode(struct_v, bl);
+  encode(global_id, bl);
+  encode(name, bl);
+  encode(rank, bl);
+  encode(inc, bl);
+  encode((int32_t)state, bl);
+  encode(state_seq, bl);
+  encode(addrs.legacy_addr(), bl, 0);
+  encode(laggy_since, bl);
+  encode(MDS_RANK_NONE, bl);
+  encode(std::string(), bl);
+  encode(export_targets, bl);
+}
+
+void MDSMap::mds_info_t::decode(bufferlist::const_iterator& bl)
+{
+  DECODE_START_LEGACY_COMPAT_LEN(10, 4, 4, bl);
+  decode(global_id, bl);
+  decode(name, bl);
+  decode(rank, bl);
+  decode(inc, bl);
+  int32_t raw_state;
+  decode(raw_state, bl);
+  state = (MDSMap::DaemonState)raw_state;
+  decode(state_seq, bl);
+  decode(addrs, bl);
+  decode(laggy_since, bl);
+  {
+    mds_rank_t standby_for_rank;
+    decode(standby_for_rank, bl);
+  }
+  {
+    std::string standby_for_name;
+    decode(standby_for_name, bl);
+  }
+  if (struct_v >= 2)
+    decode(export_targets, bl);
+  if (struct_v >= 5)
+    decode(mds_features, bl);
+  if (struct_v >= 6) {
+    decode(join_fscid, bl);
+  }
+  if (struct_v >= 7) {
+    bool standby_replay;
+    decode(standby_replay, bl);
+  }
+  if (struct_v >= 9) {
+    decode(flags, bl);
+  }
+  if (struct_v >= 10) {
+    decode(compat, bl);
+  } else {
+    compat = MDSMap::get_compat_set_v16_2_4();
+  }
+  DECODE_FINISH(bl);
+}
+
+std::string MDSMap::mds_info_t::human_name() const
+{
+  // Like "daemon mds.myhost restarted", "Activating daemon mds.myhost"
+  CachedStackStringStream css;
+  *css << "daemon mds." << name;
+  return css->str();
+}
+
+void MDSMap::encode(bufferlist& bl, uint64_t features) const
+{
+  std::map<mds_rank_t,int32_t> inc;  // Legacy field, fake it so that
+                                     // old-mon peers have something sane
+                                     // during upgrade
+  for (const auto rank : in) {
+    inc.insert(std::make_pair(rank, epoch));
+  }
+
+  using ceph::encode;
+  if ((features & CEPH_FEATURE_PGID64) == 0) {
+    __u16 v = 2;
+    encode(v, bl);
+    encode(epoch, bl);
+    encode(flags, bl);
+    encode(last_failure, bl);
+    encode(root, bl);
+    encode(session_timeout, bl);
+    encode(session_autoclose, bl);
+    encode(max_file_size, bl);
+    encode(max_mds, bl);
+    __u32 n = mds_info.size();
+    encode(n, bl);
+    for (map<mds_gid_t, mds_info_t>::const_iterator i = mds_info.begin();
+	i != mds_info.end(); ++i) {
+      encode(i->first, bl);
+      encode(i->second, bl, features);
+    }
+    n = data_pools.size();
+    encode(n, bl);
+    for (const auto p: data_pools) {
+      n = p;
+      encode(n, bl);
+    }
+
+    int32_t m = cas_pool;
+    encode(m, bl);
+    return;
+  } else if ((features & CEPH_FEATURE_MDSENC) == 0) {
+    __u16 v = 3;
+    encode(v, bl);
+    encode(epoch, bl);
+    encode(flags, bl);
+    encode(last_failure, bl);
+    encode(root, bl);
+    encode(session_timeout, bl);
+    encode(session_autoclose, bl);
+    encode(max_file_size, bl);
+    encode(max_mds, bl);
+    __u32 n = mds_info.size();
+    encode(n, bl);
+    for (map<mds_gid_t, mds_info_t>::const_iterator i = mds_info.begin();
+	i != mds_info.end(); ++i) {
+      encode(i->first, bl);
+      encode(i->second, bl, features);
+    }
+    encode(data_pools, bl);
+    encode(cas_pool, bl);
+
+    __u16 ev = 5;
+    encode(ev, bl);
+    encode(compat, bl);
+    encode(metadata_pool, bl);
+    encode(created, bl);
+    encode(modified, bl);
+    encode(tableserver, bl);
+    encode(in, bl);
+    encode(inc, bl);
+    encode(up, bl);
+    encode(failed, bl);
+    encode(stopped, bl);
+    encode(last_failure_osd_epoch, bl);
+    return;
+  }
+
+  ENCODE_START(5, 4, bl);
+  encode(epoch, bl);
+  encode(flags, bl);
+  encode(last_failure, bl);
+  encode(root, bl);
+  encode(session_timeout, bl);
+  encode(session_autoclose, bl);
+  encode(max_file_size, bl);
+  encode(max_mds, bl);
+  encode(mds_info, bl, features);
+  encode(data_pools, bl);
+  encode(cas_pool, bl);
+
+  __u16 ev = 16;
+  encode(ev, bl);
+  encode(compat, bl);
+  encode(metadata_pool, bl);
+  encode(created, bl);
+  encode(modified, bl);
+  encode(tableserver, bl);
+  encode(in, bl);
+  encode(inc, bl);
+  encode(up, bl);
+  encode(failed, bl);
+  encode(stopped, bl);
+  encode(last_failure_osd_epoch, bl);
+  encode(ever_allowed_features, bl);
+  encode(explicitly_allowed_features, bl);
+  encode(inline_data_enabled, bl);
+  encode(enabled, bl);
+  encode(fs_name, bl);
+  encode(damaged, bl);
+  encode(balancer, bl);
+  encode(standby_count_wanted, bl);
+  encode(old_max_mds, bl);
+  {
+    ceph_release_t min_compat_client = ceph_release_t::unknown;
+    encode(min_compat_client, bl);
+  }
+  encode(required_client_features, bl);
+  ENCODE_FINISH(bl);
+}
+
+void MDSMap::sanitize(const std::function<bool(int64_t pool)>& pool_exists)
+{
+  /* Before we did stricter checking, it was possible to remove a data pool
+   * without also deleting it from the MDSMap. Check for that here after
+   * decoding the data pools.
+   */
+
+  for (auto it = data_pools.begin(); it != data_pools.end();) {
+    if (!pool_exists(*it)) {
+      dout(0) << "removed non-existant data pool " << *it << " from MDSMap" << dendl;
+      it = data_pools.erase(it);
+    } else {
+      it++;
+    }
+  }
+}
+
+void MDSMap::decode(bufferlist::const_iterator& p)
+{
+  std::map<mds_rank_t,int32_t> inc;  // Legacy field, parse and drop
+
+  cached_up_features = 0;
+  DECODE_START_LEGACY_COMPAT_LEN_16(5, 4, 4, p);
+  decode(epoch, p);
+  decode(flags, p);
+  decode(last_failure, p);
+  decode(root, p);
+  decode(session_timeout, p);
+  decode(session_autoclose, p);
+  decode(max_file_size, p);
+  decode(max_mds, p);
+  decode(mds_info, p);
+  if (struct_v < 3) {
+    __u32 n;
+    decode(n, p);
+    while (n--) {
+      __u32 m;
+      decode(m, p);
+      data_pools.push_back(m);
+    }
+    __s32 s;
+    decode(s, p);
+    cas_pool = s;
+  } else {
+    decode(data_pools, p);
+    decode(cas_pool, p);
+  }
+
+  // kclient ignores everything from here
+  __u16 ev = 1;
+  if (struct_v >= 2)
+    decode(ev, p);
+  if (ev >= 3)
+    decode(compat, p);
+  else
+    compat = get_compat_set_base();
+  if (ev < 5) {
+    __u32 n;
+    decode(n, p);
+    metadata_pool = n;
+  } else {
+    decode(metadata_pool, p);
+  }
+  decode(created, p);
+  decode(modified, p);
+  decode(tableserver, p);
+  decode(in, p);
+  decode(inc, p);
+  decode(up, p);
+  decode(failed, p);
+  decode(stopped, p);
+  if (ev >= 4)
+    decode(last_failure_osd_epoch, p);
+  if (ev >= 6) {
+    if (ev < 10) {
+      // previously this was a bool about snaps, not a flag map
+      bool flag;
+      decode(flag, p);
+      ever_allowed_features = flag ? CEPH_MDSMAP_ALLOW_SNAPS : 0;
+      decode(flag, p);
+      explicitly_allowed_features = flag ? CEPH_MDSMAP_ALLOW_SNAPS : 0;
+    } else {
+      decode(ever_allowed_features, p);
+      decode(explicitly_allowed_features, p);
+    }
+  } else {
+    ever_allowed_features = 0;
+    explicitly_allowed_features = 0;
+  }
+  if (ev >= 7)
+    decode(inline_data_enabled, p);
+
+  if (ev >= 8) {
+    ceph_assert(struct_v >= 5);
+    decode(enabled, p);
+    decode(fs_name, p);
+  } else {
+    if (epoch > 1) {
+      // If an MDS has ever been started, epoch will be greater than 1,
+      // assume filesystem is enabled.
+      enabled = true;
+    } else {
+      // Upgrading from a cluster that never used an MDS, switch off
+      // filesystem until it's explicitly enabled.
+      enabled = false;
+    }
+  }
+
+  if (ev >= 9) {
+    decode(damaged, p);
+  }
+
+  if (ev >= 11) {
+    decode(balancer, p);
+  }
+
+  if (ev >= 12) {
+    decode(standby_count_wanted, p);
+  }
+
+  if (ev >= 13) {
+    decode(old_max_mds, p);
+  }
+
+  if (ev >= 14) {
+    ceph_release_t min_compat_client;
+    if (ev == 14) {
+      int8_t r;
+      decode(r, p);
+      if (r < 0) {
+	min_compat_client = ceph_release_t::unknown;
+      } else {
+	min_compat_client = ceph_release_t{static_cast<uint8_t>(r)};
+      }
+    } else if (ev >= 15) {
+      decode(min_compat_client, p);
+    }
+    if (ev >= 16) {
+      decode(required_client_features, p);
+    } else {
+      set_min_compat_client(min_compat_client);
+    }
+  }
+
+  /* All MDS since at least v14.0.0 understand INLINE */
+  /* TODO: remove after R is released */
+  compat.incompat.insert(MDS_FEATURE_INCOMPAT_INLINE);
+
+  for (auto& p: mds_info) {
+    static const CompatSet empty;
+    auto& info = p.second;
+    if (empty.compare(info.compat) == 0) {
+      /* bootstrap old compat; mds_info_t::decode does not have access to MDSMap */
+      info.compat = compat;
+    }
+    /* All MDS since at least v14.0.0 understand INLINE */
+    /* TODO: remove after R is released */
+    info.compat.incompat.insert(MDS_FEATURE_INCOMPAT_INLINE);
+  }
+
+  DECODE_FINISH(p);
+}
+
+MDSMap::availability_t MDSMap::is_cluster_available() const
+{
+  if (epoch == 0) {
+    // If I'm a client, this means I'm looking at an MDSMap instance
+    // that was never actually initialized from the mons.  Client should
+    // wait.
+    return TRANSIENT_UNAVAILABLE;
+  }
+
+  // If a rank is marked damage (unavailable until operator intervenes)
+  if (damaged.size()) {
+    return STUCK_UNAVAILABLE;
+  }
+
+  // If no ranks are created (filesystem not initialized)
+  if (in.empty()) {
+    return STUCK_UNAVAILABLE;
+  }
+
+  for (const auto rank : in) {
+    if (up.count(rank) && mds_info.at(up.at(rank)).laggy()) {
+      // This might only be transient, but because we can't see
+      // standbys, we have no way of knowing whether there is a
+      // standby available to replace the laggy guy.
+      return STUCK_UNAVAILABLE;
+    }
+  }
+
+  if (get_num_mds(CEPH_MDS_STATE_ACTIVE) > 0) {
+    // Nobody looks stuck, so indicate to client they should go ahead
+    // and try mounting if anybody is active.  This may include e.g.
+    // one MDS failing over and another active: the client should
+    // proceed to start talking to the active one and let the
+    // transiently-unavailable guy catch up later.
+    return AVAILABLE;
+  } else {
+    // Nothing indicating we were stuck, but nobody active (yet)
+    //return TRANSIENT_UNAVAILABLE;
+
+    // Because we don't have standbys in the MDSMap any more, we can't
+    // reliably indicate transient vs. stuck, so always say stuck so
+    // that the client doesn't block.
+    return STUCK_UNAVAILABLE;
+  }
+}
+
+bool MDSMap::state_transition_valid(DaemonState prev, DaemonState next)
+{
+  if (next == prev)
+    return true;
+  if (next == MDSMap::STATE_DAMAGED)
+    return true;
+
+  if (prev == MDSMap::STATE_BOOT) {
+    return next == MDSMap::STATE_STANDBY;
+  } else if (prev == MDSMap::STATE_STANDBY) {
+    return next == MDSMap::STATE_STANDBY_REPLAY ||
+           next == MDSMap::STATE_REPLAY ||
+           next == MDSMap::STATE_CREATING ||
+           next == MDSMap::STATE_STARTING;
+  } else if (prev == MDSMap::STATE_CREATING || prev == MDSMap::STATE_STARTING) {
+    return next == MDSMap::STATE_ACTIVE;
+  } else if (prev == MDSMap::STATE_STANDBY_REPLAY) {
+    return next == MDSMap::STATE_REPLAY;
+  } else if (prev == MDSMap::STATE_REPLAY) {
+    return next == MDSMap::STATE_RESOLVE ||
+           next == MDSMap::STATE_RECONNECT;
+  } else if (prev >= MDSMap::STATE_RESOLVE && prev < MDSMap::STATE_ACTIVE) {
+    // Once I have entered replay, the only allowable transitions are to
+    // the next next along in the sequence.
+    // Except...
+    if (prev == MDSMap::STATE_REJOIN &&
+        (next == MDSMap::STATE_ACTIVE ||    // No need to do client replay
+         next == MDSMap::STATE_STOPPED)) {  // no subtrees
+      return true;         
+    }
+    return next == prev + 1;
+  } else if (prev == MDSMap::STATE_ACTIVE) {
+    return next == MDSMap::STATE_STOPPING;
+  } else if (prev == MDSMap::STATE_STOPPING) {
+    return next == MDSMap::STATE_STOPPED;
+  } else {
+    derr << __func__ << ": Unknown prev state "
+         << ceph_mds_state_name(prev) << "(" << prev << ")" << dendl;
+    return false;
+  }
+}
+
+bool MDSMap::check_health(mds_rank_t standby_daemon_count)
+{
+  std::set<mds_rank_t> standbys;
+  get_standby_replay_mds_set(standbys);
+  std::set<mds_rank_t> actives;
+  get_active_mds_set(actives);
+  mds_rank_t standbys_avail = (mds_rank_t)standbys.size()+standby_daemon_count;
+
+  /* If there are standby daemons available/replaying and
+   * standby_count_wanted is unset (default), then we set it to 1. This will
+   * happen during health checks by the mons. Also, during initial creation
+   * of the FS we will have no actives so we don't want to change the default
+   * yet.
+   */
+  if (standby_count_wanted == -1 && actives.size() > 0 && standbys_avail > 0) {
+    set_standby_count_wanted(1);
+    return true;
+  }
+  return false;
+}
+
+mds_gid_t MDSMap::find_mds_gid_by_name(std::string_view s) const {
+  for (const auto& [gid, info] : mds_info) {
+    if (info.name == s) {
+      return gid;
+    }
+  }
+  return MDS_GID_NONE;
+}
+
+unsigned MDSMap::get_num_mds(int state) const {
+  unsigned n = 0;
+  for (std::map<mds_gid_t,mds_info_t>::const_iterator p = mds_info.begin();
+       p != mds_info.end();
+       ++p)
+    if (p->second.state == state) ++n;
+  return n;
+}
+
+void MDSMap::get_up_mds_set(std::set<mds_rank_t>& s) const {
+  for (std::map<mds_rank_t, mds_gid_t>::const_iterator p = up.begin();
+       p != up.end();
+       ++p)
+    s.insert(p->first);
+}
+
+uint64_t MDSMap::get_up_features() {
+  if (!cached_up_features) {
+    bool first = true;
+    for (std::map<mds_rank_t, mds_gid_t>::const_iterator p = up.begin();
+         p != up.end();
+         ++p) {
+      std::map<mds_gid_t, mds_info_t>::const_iterator q =
+        mds_info.find(p->second);
+      ceph_assert(q != mds_info.end());
+      if (first) {
+        cached_up_features = q->second.mds_features;
+        first = false;
+      } else {
+        cached_up_features &= q->second.mds_features;
+      }
+    }
+  }
+  return cached_up_features;
+}
+
+void MDSMap::get_recovery_mds_set(std::set<mds_rank_t>& s) const {
+  s = failed;
+  for (const auto& p : damaged)
+    s.insert(p);
+  for (const auto& p : mds_info)
+    if (p.second.state >= STATE_REPLAY && p.second.state <= STATE_STOPPING)
+      s.insert(p.second.rank);
+}
+
+void MDSMap::get_mds_set_lower_bound(std::set<mds_rank_t>& s, DaemonState first) const {
+  for (std::map<mds_gid_t, mds_info_t>::const_iterator p = mds_info.begin();
+       p != mds_info.end();
+       ++p)
+    if (p->second.state >= first && p->second.state <= STATE_STOPPING)
+      s.insert(p->second.rank);
+}
+
+void MDSMap::get_mds_set(std::set<mds_rank_t>& s, DaemonState state) const {
+  for (std::map<mds_gid_t, mds_info_t>::const_iterator p = mds_info.begin();
+       p != mds_info.end();
+       ++p)
+    if (p->second.state == state)
+      s.insert(p->second.rank);
+}
+
+mds_gid_t MDSMap::get_standby_replay(mds_rank_t r) const {
+  for (auto& [gid,info] : mds_info) {
+    if (info.rank == r && info.state == STATE_STANDBY_REPLAY) {
+      return gid;
+    }
+  }
+  return MDS_GID_NONE;
+}
+
+bool MDSMap::is_degraded() const {
+  if (!failed.empty() || !damaged.empty())
+    return true;
+  for (const auto& p : mds_info) {
+    if (p.second.is_degraded())
+      return true;
+  }
+  return false;
+}
+
+void MDSMap::set_min_compat_client(ceph_release_t version)
+{
+  vector<size_t> bits = CEPHFS_FEATURES_MDS_REQUIRED;
+
+  if (version >= ceph_release_t::octopus)
+    bits.push_back(CEPHFS_FEATURE_OCTOPUS);
+  else if (version >= ceph_release_t::nautilus)
+    bits.push_back(CEPHFS_FEATURE_NAUTILUS);
+  else if (version >= ceph_release_t::mimic)
+    bits.push_back(CEPHFS_FEATURE_MIMIC);
+  else if (version >= ceph_release_t::luminous)
+    bits.push_back(CEPHFS_FEATURE_LUMINOUS);
+  else if (version >= ceph_release_t::kraken)
+    bits.push_back(CEPHFS_FEATURE_KRAKEN);
+  else if (version >= ceph_release_t::jewel)
+    bits.push_back(CEPHFS_FEATURE_JEWEL);
+
+  std::sort(bits.begin(), bits.end());
+  required_client_features = feature_bitset_t(bits);
+}