Adding upstream version 14.2.21.upstream/14.2.21upstream

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

1 files changed, 1363 insertions, 0 deletions

diff --git a/src/mds/MDCache.h b/src/mds/MDCache.h
new file mode 100644
index 00000000..ab5adb68
--- /dev/null
+++ b/src/mds/MDCache.h
@@ -0,0 +1,1363 @@
+// -*- 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.
+ * 
+ */
+
+
+
+#ifndef CEPH_MDCACHE_H
+#define CEPH_MDCACHE_H
+
+#include <atomic>
+#include <string_view>
+#include <thread>
+
+#include "common/DecayCounter.h"
+#include "include/types.h"
+#include "include/filepath.h"
+#include "include/elist.h"
+
+#include "messages/MCacheExpire.h"
+#include "messages/MClientQuota.h"
+#include "messages/MClientRequest.h"
+#include "messages/MClientSnap.h"
+#include "messages/MDentryLink.h"
+#include "messages/MDentryUnlink.h"
+#include "messages/MDirUpdate.h"
+#include "messages/MDiscover.h"
+#include "messages/MDiscoverReply.h"
+#include "messages/MGatherCaps.h"
+#include "messages/MGenericMessage.h"
+#include "messages/MInodeFileCaps.h"
+#include "messages/MLock.h"
+#include "messages/MMDSCacheRejoin.h"
+#include "messages/MMDSFindIno.h"
+#include "messages/MMDSFindInoReply.h"
+#include "messages/MMDSFragmentNotify.h"
+#include "messages/MMDSFragmentNotifyAck.h"
+#include "messages/MMDSOpenIno.h"
+#include "messages/MMDSOpenInoReply.h"
+#include "messages/MMDSResolve.h"
+#include "messages/MMDSResolveAck.h"
+#include "messages/MMDSSlaveRequest.h"
+#include "messages/MMDSSnapUpdate.h"
+
+
+#include "osdc/Filer.h"
+#include "CInode.h"
+#include "CDentry.h"
+#include "CDir.h"
+#include "include/Context.h"
+#include "events/EMetaBlob.h"
+#include "RecoveryQueue.h"
+#include "StrayManager.h"
+#include "OpenFileTable.h"
+#include "MDSContext.h"
+#include "MDSMap.h"
+#include "Mutation.h"
+
+
+class PerfCounters;
+
+class MDSRank;
+class Session;
+class Migrator;
+
+class Session;
+
+class ESubtreeMap;
+
+enum {
+  l_mdc_first = 3000,
+  // How many inodes currently in stray dentries
+  l_mdc_num_strays,
+  // How many stray dentries are currently delayed for purge due to refs
+  l_mdc_num_strays_delayed,
+  // How many stray dentries are currently being enqueued for purge
+  l_mdc_num_strays_enqueuing,
+
+  // How many dentries have ever been added to stray dir
+  l_mdc_strays_created,
+  // How many dentries have been passed on to PurgeQueue
+  l_mdc_strays_enqueued,
+  // How many strays have been reintegrated?
+  l_mdc_strays_reintegrated,
+  // How many strays have been migrated?
+  l_mdc_strays_migrated,
+
+  // How many inode sizes currently being recovered
+  l_mdc_num_recovering_processing,
+  // How many inodes currently waiting to have size recovered
+  l_mdc_num_recovering_enqueued,
+  // How many inodes waiting with elevated priority for recovery
+  l_mdc_num_recovering_prioritized,
+  // How many inodes ever started size recovery
+  l_mdc_recovery_started,
+  // How many inodes ever completed size recovery
+  l_mdc_recovery_completed,
+
+  l_mdss_ireq_enqueue_scrub,
+  l_mdss_ireq_exportdir,
+  l_mdss_ireq_flush,
+  l_mdss_ireq_fragmentdir,
+  l_mdss_ireq_fragstats,
+  l_mdss_ireq_inodestats,
+
+  l_mdc_last,
+};
+
+
+// flags for predirty_journal_parents()
+static const int PREDIRTY_PRIMARY = 1; // primary dn, adjust nested accounting
+static const int PREDIRTY_DIR = 2;     // update parent dir mtime/size
+static const int PREDIRTY_SHALLOW = 4; // only go to immediate parent (for easier rollback)
+
+class MDCache {
+ public:
+  using clock = ceph::coarse_mono_clock;
+  using time = ceph::coarse_mono_time;
+
+  typedef std::map<mds_rank_t, MCacheExpire::ref> expiremap;
+
+  // my master
+  MDSRank *mds;
+
+  // -- my cache --
+  LRU lru;   // dentry lru for expiring items from cache
+  LRU bottom_lru; // dentries that should be trimmed ASAP
+ protected:
+  ceph::unordered_map<inodeno_t,CInode*> inode_map;  // map of head inodes by ino
+  map<vinodeno_t, CInode*> snap_inode_map;  // map of snap inodes by ino
+  CInode *root = nullptr; // root inode
+  CInode *myin = nullptr; // .ceph/mds%d dir
+
+  bool readonly = false;
+  void set_readonly() { readonly = true; }
+
+  std::array<CInode *, NUM_STRAY> strays{}; // my stray dir
+  int stray_index = 0;
+
+  CInode *get_stray() {
+    return strays[stray_index];
+  }
+
+  set<CInode*> base_inodes;
+
+  std::unique_ptr<PerfCounters> logger;
+
+  Filer filer;
+
+  bool exceeded_size_limit = false;
+
+private:
+  uint64_t cache_inode_limit;
+  uint64_t cache_memory_limit;
+  double cache_reservation;
+  double cache_health_threshold;
+  bool forward_all_requests_to_auth;
+
+public:
+  uint64_t cache_limit_inodes(void) {
+    return cache_inode_limit;
+  }
+  bool forward_all_reqs_to_auth() const { 
+    return forward_all_requests_to_auth;
+  }
+  uint64_t cache_limit_memory(void) {
+    return cache_memory_limit;
+  }
+  double cache_toofull_ratio(void) const {
+    double inode_reserve = cache_inode_limit*(1.0-cache_reservation);
+    double memory_reserve = cache_memory_limit*(1.0-cache_reservation);
+    return fmax(0.0, fmax((cache_size()-memory_reserve)/memory_reserve, cache_inode_limit == 0 ? 0.0 : (CInode::count()-inode_reserve)/inode_reserve));
+  }
+  bool cache_toofull(void) const {
+    return cache_toofull_ratio() > 0.0;
+  }
+  uint64_t cache_size(void) const {
+    return mempool::get_pool(mempool::mds_co::id).allocated_bytes();
+  }
+  bool cache_overfull(void) const {
+    return (cache_inode_limit > 0 && CInode::count() > cache_inode_limit*cache_health_threshold) || (cache_size() > cache_memory_limit*cache_health_threshold);
+  }
+
+  void advance_stray() {
+    stray_index = (stray_index+1)%NUM_STRAY;
+  }
+
+  /**
+   * Call this when you know that a CDentry is ready to be passed
+   * on to StrayManager (i.e. this is a stray you've just created)
+   */
+  void notify_stray(CDentry *dn) {
+    ceph_assert(dn->get_dir()->get_inode()->is_stray());
+    if (dn->state_test(CDentry::STATE_PURGING))
+      return;
+
+    stray_manager.eval_stray(dn);
+  }
+
+  void maybe_eval_stray(CInode *in, bool delay=false);
+  void clear_dirty_bits_for_stray(CInode* diri);
+
+  bool is_readonly() { return readonly; }
+  void force_readonly();
+
+  DecayRate decayrate;
+
+  int num_shadow_inodes = 0;
+
+  int num_inodes_with_caps = 0;
+
+  unsigned max_dir_commit_size;
+
+  static file_layout_t gen_default_file_layout(const MDSMap &mdsmap);
+  static file_layout_t gen_default_log_layout(const MDSMap &mdsmap);
+
+  file_layout_t default_file_layout;
+  file_layout_t default_log_layout;
+
+  void register_perfcounters();
+
+  // -- client leases --
+public:
+  static constexpr std::size_t client_lease_pools = 3;
+  std::array<float, client_lease_pools> client_lease_durations{5.0, 30.0, 300.0};
+
+protected:
+  std::array<xlist<ClientLease*>, client_lease_pools> client_leases{};
+public:
+  void touch_client_lease(ClientLease *r, int pool, utime_t ttl) {
+    client_leases[pool].push_back(&r->item_lease);
+    r->ttl = ttl;
+  }
+
+  void notify_stray_removed()
+  {
+    stray_manager.notify_stray_removed();
+  }
+
+  void notify_stray_created()
+  {
+    stray_manager.notify_stray_created();
+  }
+
+  void eval_remote(CDentry *dn)
+  {
+    stray_manager.eval_remote(dn);
+  }
+
+  // -- client caps --
+  uint64_t last_cap_id = 0;
+
+  // -- discover --
+  struct discover_info_t {
+    ceph_tid_t tid;
+    mds_rank_t mds;
+    inodeno_t ino;
+    frag_t frag;
+    snapid_t snap;
+    filepath want_path;
+    CInode *basei;
+    bool want_base_dir;
+    bool want_xlocked;
+
+    discover_info_t() :
+      tid(0), mds(-1), snap(CEPH_NOSNAP), basei(NULL),
+      want_base_dir(false), want_xlocked(false) {}
+    ~discover_info_t() {
+      if (basei)
+	basei->put(MDSCacheObject::PIN_DISCOVERBASE);
+    }
+    void pin_base(CInode *b) {
+      basei = b;
+      basei->get(MDSCacheObject::PIN_DISCOVERBASE);
+    }
+  };
+
+  map<ceph_tid_t, discover_info_t> discovers;
+  ceph_tid_t discover_last_tid = 0;
+
+  void _send_discover(discover_info_t& dis);
+  discover_info_t& _create_discover(mds_rank_t mds) {
+    ceph_tid_t t = ++discover_last_tid;
+    discover_info_t& d = discovers[t];
+    d.tid = t;
+    d.mds = mds;
+    return d;
+  }
+
+  // waiters
+  map<int, map<inodeno_t, MDSContext::vec > > waiting_for_base_ino;
+
+  void discover_base_ino(inodeno_t want_ino, MDSContext *onfinish, mds_rank_t from=MDS_RANK_NONE);
+  void discover_dir_frag(CInode *base, frag_t approx_fg, MDSContext *onfinish,
+			 mds_rank_t from=MDS_RANK_NONE);
+  void discover_path(CInode *base, snapid_t snap, filepath want_path, MDSContext *onfinish,
+		     bool want_xlocked=false, mds_rank_t from=MDS_RANK_NONE);
+  void discover_path(CDir *base, snapid_t snap, filepath want_path, MDSContext *onfinish,
+		     bool want_xlocked=false);
+  void kick_discovers(mds_rank_t who);  // after a failure.
+
+
+  // -- subtrees --
+private:
+  static const unsigned int SUBTREES_COUNT_THRESHOLD = 5;
+  static const unsigned int SUBTREES_DEPTH_THRESHOLD = 5;
+protected:
+  /* subtree keys and each tree's non-recursive nested subtrees (the "bounds") */
+  map<CDir*,set<CDir*> > subtrees;
+  map<CInode*,list<pair<CDir*,CDir*> > > projected_subtree_renames;  // renamed ino -> target dir
+  
+  // adjust subtree auth specification
+  //  dir->dir_auth
+  //  imports/exports/nested_exports
+  //  join/split subtrees as appropriate
+public:
+  bool is_subtrees() { return !subtrees.empty(); }
+  template<typename T>
+  void get_subtrees(T& c) {
+    if constexpr (std::is_same_v<T, std::vector<CDir*>>)
+      c.reserve(c.size() + subtrees.size());
+    for (const auto& p : subtrees) {
+      c.push_back(p.first);
+    }
+  }
+  void adjust_subtree_auth(CDir *root, mds_authority_t auth, bool adjust_pop=true);
+  void adjust_subtree_auth(CDir *root, mds_rank_t a, mds_rank_t b=CDIR_AUTH_UNKNOWN) {
+    adjust_subtree_auth(root, mds_authority_t(a,b));
+  }
+  void adjust_bounded_subtree_auth(CDir *dir, const set<CDir*>& bounds, mds_authority_t auth);
+  void adjust_bounded_subtree_auth(CDir *dir, const set<CDir*>& bounds, mds_rank_t a) {
+    adjust_bounded_subtree_auth(dir, bounds, mds_authority_t(a, CDIR_AUTH_UNKNOWN));
+  }
+  void adjust_bounded_subtree_auth(CDir *dir, const vector<dirfrag_t>& bounds, const mds_authority_t &auth);
+  void adjust_bounded_subtree_auth(CDir *dir, const vector<dirfrag_t>& bounds, mds_rank_t a) {
+    adjust_bounded_subtree_auth(dir, bounds, mds_authority_t(a, CDIR_AUTH_UNKNOWN));
+  }
+  void map_dirfrag_set(const list<dirfrag_t>& dfs, set<CDir*>& result);
+  void try_subtree_merge(CDir *root);
+  void try_subtree_merge_at(CDir *root, set<CInode*> *to_eval, bool adjust_pop=true);
+  void subtree_merge_writebehind_finish(CInode *in, MutationRef& mut);
+  void eval_subtree_root(CInode *diri);
+  CDir *get_subtree_root(CDir *dir);
+  CDir *get_projected_subtree_root(CDir *dir);
+  bool is_leaf_subtree(CDir *dir) {
+    ceph_assert(subtrees.count(dir));
+    return subtrees[dir].empty();
+  }
+  void remove_subtree(CDir *dir);
+  bool is_subtree(CDir *root) {
+    return subtrees.count(root);
+  }
+  void get_subtree_bounds(CDir *root, set<CDir*>& bounds);
+  void get_wouldbe_subtree_bounds(CDir *root, set<CDir*>& bounds);
+  void verify_subtree_bounds(CDir *root, const set<CDir*>& bounds);
+  void verify_subtree_bounds(CDir *root, const list<dirfrag_t>& bounds);
+
+  void project_subtree_rename(CInode *diri, CDir *olddir, CDir *newdir);
+  void adjust_subtree_after_rename(CInode *diri, CDir *olddir, bool pop);
+
+  auto get_auth_subtrees() {
+    std::vector<CDir*> c;
+    for (auto& p : subtrees) {
+      auto& root = p.first;
+      if (root->is_auth()) {
+        c.push_back(root);
+      }
+    }
+    return c;
+  }
+
+  auto get_fullauth_subtrees() {
+    std::vector<CDir*> c;
+    for (auto& p : subtrees) {
+      auto& root = p.first;
+      if (root->is_full_dir_auth()) {
+        c.push_back(root);
+      }
+    }
+    return c;
+  }
+  auto num_subtrees_fullauth() const {
+    std::size_t n = 0;
+    for (auto& p : subtrees) {
+      auto& root = p.first;
+      if (root->is_full_dir_auth()) {
+        ++n;
+      }
+    }
+    return n;
+  }
+
+  auto num_subtrees_fullnonauth() const {
+    std::size_t n = 0;
+    for (auto& p : subtrees) {
+      auto& root = p.first;
+      if (root->is_full_dir_nonauth()) {
+        ++n;
+      }
+    }
+    return n;
+  }
+
+  auto num_subtrees() const {
+    return subtrees.size();
+  }
+
+  
+protected:
+  // -- requests --
+  ceph::unordered_map<metareqid_t, MDRequestRef> active_requests;
+
+public:
+  int get_num_client_requests();
+
+  MDRequestRef request_start(const MClientRequest::const_ref& req);
+  MDRequestRef request_start_slave(metareqid_t rid, __u32 attempt, const Message::const_ref &m);
+  MDRequestRef request_start_internal(int op);
+  bool have_request(metareqid_t rid) {
+    return active_requests.count(rid);
+  }
+  MDRequestRef request_get(metareqid_t rid);
+  void request_pin_ref(MDRequestRef& r, CInode *ref, vector<CDentry*>& trace);
+  void request_finish(MDRequestRef& mdr);
+  void request_forward(MDRequestRef& mdr, mds_rank_t mds, int port=0);
+  void dispatch_request(MDRequestRef& mdr);
+  void request_drop_foreign_locks(MDRequestRef& mdr);
+  void request_drop_non_rdlocks(MDRequestRef& r);
+  void request_drop_locks(MDRequestRef& r);
+  void request_cleanup(MDRequestRef& r);
+  
+  void request_kill(MDRequestRef& r);  // called when session closes
+
+  // journal/snap helpers
+  CInode *pick_inode_snap(CInode *in, snapid_t follows);
+  CInode *cow_inode(CInode *in, snapid_t last);
+  void journal_cow_dentry(MutationImpl *mut, EMetaBlob *metablob, CDentry *dn,
+                          snapid_t follows=CEPH_NOSNAP,
+			  CInode **pcow_inode=0, CDentry::linkage_t *dnl=0);
+  void journal_cow_inode(MutationRef& mut, EMetaBlob *metablob, CInode *in, snapid_t follows=CEPH_NOSNAP,
+			  CInode **pcow_inode=0);
+  void journal_dirty_inode(MutationImpl *mut, EMetaBlob *metablob, CInode *in, snapid_t follows=CEPH_NOSNAP);
+
+  void project_rstat_inode_to_frag(CInode *cur, CDir *parent, snapid_t first,
+				   int linkunlink, SnapRealm *prealm);
+  void _project_rstat_inode_to_frag(CInode::mempool_inode & inode, snapid_t ofirst, snapid_t last,
+				    CDir *parent, int linkunlink, bool update_inode);
+  void project_rstat_frag_to_inode(nest_info_t& rstat, nest_info_t& accounted_rstat,
+				   snapid_t ofirst, snapid_t last, 
+				   CInode *pin, bool cow_head);
+  void broadcast_quota_to_client(CInode *in, client_t exclude_ct = -1, bool quota_change = false);
+  void predirty_journal_parents(MutationRef mut, EMetaBlob *blob,
+				CInode *in, CDir *parent,
+				int flags, int linkunlink=0,
+				snapid_t follows=CEPH_NOSNAP);
+
+  // slaves
+  void add_uncommitted_master(metareqid_t reqid, LogSegment *ls, set<mds_rank_t> &slaves, bool safe=false) {
+    uncommitted_masters[reqid].ls = ls;
+    uncommitted_masters[reqid].slaves = slaves;
+    uncommitted_masters[reqid].safe = safe;
+  }
+  void wait_for_uncommitted_master(metareqid_t reqid, MDSContext *c) {
+    uncommitted_masters[reqid].waiters.push_back(c);
+  }
+  bool have_uncommitted_master(metareqid_t reqid, mds_rank_t from) {
+    auto p = uncommitted_masters.find(reqid);
+    return p != uncommitted_masters.end() && p->second.slaves.count(from) > 0;
+  }
+  void log_master_commit(metareqid_t reqid);
+  void logged_master_update(metareqid_t reqid);
+  void _logged_master_commit(metareqid_t reqid);
+  void committed_master_slave(metareqid_t r, mds_rank_t from);
+  void finish_committed_masters();
+
+  void add_uncommitted_slave(metareqid_t reqid, LogSegment*, mds_rank_t, MDSlaveUpdate *su=nullptr);
+  void wait_for_uncommitted_slave(metareqid_t reqid, MDSContext *c) {
+    uncommitted_slaves.at(reqid).waiters.push_back(c);
+  }
+  void finish_uncommitted_slave(metareqid_t reqid, bool assert_exist=true);
+  MDSlaveUpdate* get_uncommitted_slave(metareqid_t reqid, mds_rank_t master);
+  void _logged_slave_commit(mds_rank_t from, metareqid_t reqid);
+
+  // -- recovery --
+protected:
+  set<mds_rank_t> recovery_set;
+
+public:
+  void set_recovery_set(set<mds_rank_t>& s);
+  void handle_mds_failure(mds_rank_t who);
+  void handle_mds_recovery(mds_rank_t who);
+
+protected:
+  // [resolve]
+  // from EImportStart w/o EImportFinish during journal replay
+  map<dirfrag_t, vector<dirfrag_t> >            my_ambiguous_imports;  
+  // from MMDSResolves
+  map<mds_rank_t, map<dirfrag_t, vector<dirfrag_t> > > other_ambiguous_imports;  
+
+  map<CInode*, int> uncommitted_slave_rename_olddir;  // slave: preserve the non-auth dir until seeing commit.
+  map<CInode*, int> uncommitted_slave_unlink;  // slave: preserve the unlinked inode until seeing commit.
+
+  // track master requests whose slaves haven't acknowledged commit
+  struct umaster {
+    set<mds_rank_t> slaves;
+    LogSegment *ls;
+    MDSContext::vec waiters;
+    bool safe;
+    bool committing;
+    bool recovering;
+    umaster() : ls(NULL), safe(false), committing(false), recovering(false) {}
+  };
+  map<metareqid_t, umaster>                 uncommitted_masters;         // master: req -> slave set
+
+  struct uslave {
+    uslave() {}
+    mds_rank_t master;
+    LogSegment *ls = nullptr;
+    MDSlaveUpdate *su = nullptr;
+    MDSContext::vec waiters;
+  };
+  map<metareqid_t, uslave> uncommitted_slaves;  // slave: preserve the slave req until seeing commit.
+
+  set<metareqid_t>		pending_masters;
+  map<int, set<metareqid_t> >	ambiguous_slave_updates;
+
+  friend class ESlaveUpdate;
+  friend class ECommitted;
+
+  bool resolves_pending = false;
+  set<mds_rank_t> resolve_gather;	// nodes i need resolves from
+  set<mds_rank_t> resolve_ack_gather;	// nodes i need a resolve_ack from
+  set<version_t> resolve_snapclient_commits;
+  map<metareqid_t, mds_rank_t> resolve_need_rollback;  // rollbacks i'm writing to the journal
+  map<mds_rank_t, MMDSResolve::const_ref> delayed_resolve;
+  
+  void handle_resolve(const MMDSResolve::const_ref &m);
+  void handle_resolve_ack(const MMDSResolveAck::const_ref &m);
+  void process_delayed_resolve();
+  void discard_delayed_resolve(mds_rank_t who);
+  void maybe_resolve_finish();
+  void disambiguate_my_imports();
+  void disambiguate_other_imports();
+  void trim_unlinked_inodes();
+
+  void send_slave_resolves();
+  void send_subtree_resolves();
+  void maybe_finish_slave_resolve();
+
+public:
+  void recalc_auth_bits(bool replay);
+  void remove_inode_recursive(CInode *in);
+
+  bool is_ambiguous_slave_update(metareqid_t reqid, mds_rank_t master) {
+    auto p = ambiguous_slave_updates.find(master);
+    return p != ambiguous_slave_updates.end() && p->second.count(reqid);
+  }
+  void add_ambiguous_slave_update(metareqid_t reqid, mds_rank_t master) {
+    ambiguous_slave_updates[master].insert(reqid);
+  }
+  void remove_ambiguous_slave_update(metareqid_t reqid, mds_rank_t master) {
+    auto p = ambiguous_slave_updates.find(master);
+    auto q = p->second.find(reqid);
+    ceph_assert(q != p->second.end());
+    p->second.erase(q);
+    if (p->second.empty())
+      ambiguous_slave_updates.erase(p);
+  }
+
+  void add_rollback(metareqid_t reqid, mds_rank_t master) {
+    resolve_need_rollback[reqid] = master;
+  }
+  void finish_rollback(metareqid_t reqid, MDRequestRef& mdr);
+
+  // ambiguous imports
+  void add_ambiguous_import(dirfrag_t base, const vector<dirfrag_t>& bounds);
+  void add_ambiguous_import(CDir *base, const set<CDir*>& bounds);
+  bool have_ambiguous_import(dirfrag_t base) {
+    return my_ambiguous_imports.count(base);
+  }
+  void get_ambiguous_import_bounds(dirfrag_t base, vector<dirfrag_t>& bounds) {
+    ceph_assert(my_ambiguous_imports.count(base));
+    bounds = my_ambiguous_imports[base];
+  }
+  void cancel_ambiguous_import(CDir *);
+  void finish_ambiguous_import(dirfrag_t dirino);
+  void resolve_start(MDSContext *resolve_done_);
+  void send_resolves();
+  void maybe_send_pending_resolves() {
+    if (resolves_pending)
+      send_subtree_resolves();
+  }
+  
+  void _move_subtree_map_bound(dirfrag_t df, dirfrag_t oldparent, dirfrag_t newparent,
+			       map<dirfrag_t,vector<dirfrag_t> >& subtrees);
+  ESubtreeMap *create_subtree_map();
+
+
+  void clean_open_file_lists();
+  void dump_openfiles(Formatter *f);
+  bool dump_inode(Formatter *f, uint64_t number);
+protected:
+  // [rejoin]
+  bool rejoins_pending = false;
+  set<mds_rank_t> rejoin_gather;      // nodes from whom i need a rejoin
+  set<mds_rank_t> rejoin_sent;        // nodes i sent a rejoin to
+  set<mds_rank_t> rejoin_ack_sent;    // nodes i sent a rejoin to
+  set<mds_rank_t> rejoin_ack_gather;  // nodes from whom i need a rejoin ack
+  map<mds_rank_t,map<inodeno_t,map<client_t,Capability::Import> > > rejoin_imported_caps;
+  map<inodeno_t,pair<mds_rank_t,map<client_t,Capability::Export> > > rejoin_slave_exports;
+
+  map<client_t,entity_inst_t> rejoin_client_map;
+  map<client_t,client_metadata_t> rejoin_client_metadata_map;
+  map<client_t,pair<Session*,uint64_t> > rejoin_session_map;
+
+  map<inodeno_t,pair<mds_rank_t,map<client_t,cap_reconnect_t> > > cap_exports; // ino -> target, client -> capex
+
+  map<inodeno_t,map<client_t,map<mds_rank_t,cap_reconnect_t> > > cap_imports;  // ino -> client -> frommds -> capex
+  set<inodeno_t> cap_imports_missing;
+  map<inodeno_t, MDSContext::vec > cap_reconnect_waiters;
+  int cap_imports_num_opening = 0;
+  
+  set<CInode*> rejoin_undef_inodes;
+  set<CInode*> rejoin_potential_updated_scatterlocks;
+  set<CDir*>   rejoin_undef_dirfrags;
+  map<mds_rank_t, set<CInode*> > rejoin_unlinked_inodes;
+
+  vector<CInode*> rejoin_recover_q, rejoin_check_q;
+  list<SimpleLock*> rejoin_eval_locks;
+  MDSContext::vec rejoin_waiters;
+
+  void rejoin_walk(CDir *dir, const MMDSCacheRejoin::ref &rejoin);
+  void handle_cache_rejoin(const MMDSCacheRejoin::const_ref &m);
+  void handle_cache_rejoin_weak(const MMDSCacheRejoin::const_ref &m);
+  CInode* rejoin_invent_inode(inodeno_t ino, snapid_t last);
+  CDir* rejoin_invent_dirfrag(dirfrag_t df);
+  void handle_cache_rejoin_strong(const MMDSCacheRejoin::const_ref &m);
+  void rejoin_scour_survivor_replicas(mds_rank_t from, const MMDSCacheRejoin::const_ref &ack,
+				      set<vinodeno_t>& acked_inodes,
+				      set<SimpleLock *>& gather_locks);
+  void handle_cache_rejoin_ack(const MMDSCacheRejoin::const_ref &m);
+  void rejoin_send_acks();
+  void rejoin_trim_undef_inodes();
+  void maybe_send_pending_rejoins() {
+    if (rejoins_pending)
+      rejoin_send_rejoins();
+  }
+  std::unique_ptr<MDSContext> rejoin_done;
+  std::unique_ptr<MDSContext> resolve_done;
+public:
+  void rejoin_start(MDSContext *rejoin_done_);
+  void rejoin_gather_finish();
+  void rejoin_send_rejoins();
+  void rejoin_export_caps(inodeno_t ino, client_t client, const cap_reconnect_t& icr,
+			  int target=-1, bool drop_path=false) {
+    auto& ex = cap_exports[ino];
+    ex.first = target;
+    auto &_icr = ex.second[client] = icr;
+    if (drop_path)
+      _icr.path.clear();
+  }
+  void rejoin_recovered_caps(inodeno_t ino, client_t client, const cap_reconnect_t& icr, 
+			     mds_rank_t frommds=MDS_RANK_NONE, bool drop_path=false) {
+    auto &_icr = cap_imports[ino][client][frommds] = icr;
+    if (drop_path)
+      _icr.path.clear();
+  }
+  void rejoin_recovered_client(client_t client, const entity_inst_t& inst) {
+    rejoin_client_map.emplace(client, inst);
+  }
+  bool rejoin_has_cap_reconnect(inodeno_t ino) const {
+    return cap_imports.count(ino);
+  }
+  void add_replay_ino_alloc(inodeno_t ino) {
+    cap_imports_missing.insert(ino); // avoid opening ino during cache rejoin
+  }
+  const cap_reconnect_t *get_replay_cap_reconnect(inodeno_t ino, client_t client) {
+    if (cap_imports.count(ino) &&
+	cap_imports[ino].count(client) &&
+	cap_imports[ino][client].count(MDS_RANK_NONE)) {
+      return &cap_imports[ino][client][MDS_RANK_NONE];
+    }
+    return NULL;
+  }
+  void remove_replay_cap_reconnect(inodeno_t ino, client_t client) {
+    ceph_assert(cap_imports[ino].size() == 1);
+    ceph_assert(cap_imports[ino][client].size() == 1);
+    cap_imports.erase(ino);
+  }
+  void wait_replay_cap_reconnect(inodeno_t ino, MDSContext *c) {
+    cap_reconnect_waiters[ino].push_back(c);
+  }
+
+  // [reconnect/rejoin caps]
+  struct reconnected_cap_info_t {
+    inodeno_t realm_ino;
+    snapid_t snap_follows;
+    int dirty_caps;
+    bool snapflush;
+    reconnected_cap_info_t() :
+      realm_ino(0), snap_follows(0), dirty_caps(0), snapflush(false) {}
+  };
+  map<inodeno_t,map<client_t, reconnected_cap_info_t> >  reconnected_caps;   // inode -> client -> snap_follows,realmino
+  map<inodeno_t,map<client_t, snapid_t> > reconnected_snaprealms;  // realmino -> client -> realmseq
+
+  void add_reconnected_cap(client_t client, inodeno_t ino, const cap_reconnect_t& icr) {
+    reconnected_cap_info_t &info = reconnected_caps[ino][client];
+    info.realm_ino = inodeno_t(icr.capinfo.snaprealm);
+    info.snap_follows = icr.snap_follows;
+  }
+  void set_reconnected_dirty_caps(client_t client, inodeno_t ino, int dirty, bool snapflush) {
+    reconnected_cap_info_t &info = reconnected_caps[ino][client];
+    info.dirty_caps |= dirty;
+    if (snapflush)
+      info.snapflush = snapflush;
+  }
+  void add_reconnected_snaprealm(client_t client, inodeno_t ino, snapid_t seq) {
+    reconnected_snaprealms[ino][client] = seq;
+  }
+
+  friend class C_MDC_RejoinOpenInoFinish;
+  friend class C_MDC_RejoinSessionsOpened;
+  void rejoin_open_ino_finish(inodeno_t ino, int ret);
+  void rejoin_prefetch_ino_finish(inodeno_t ino, int ret);
+  void rejoin_open_sessions_finish(map<client_t,pair<Session*,uint64_t> >& session_map);
+  bool process_imported_caps();
+  void choose_lock_states_and_reconnect_caps();
+  void prepare_realm_split(SnapRealm *realm, client_t client, inodeno_t ino,
+			   map<client_t,MClientSnap::ref>& splits);
+  void prepare_realm_merge(SnapRealm *realm, SnapRealm *parent_realm, map<client_t,MClientSnap::ref>& splits);
+  void send_snaps(map<client_t,MClientSnap::ref>& splits);
+  Capability* rejoin_import_cap(CInode *in, client_t client, const cap_reconnect_t& icr, mds_rank_t frommds);
+  void finish_snaprealm_reconnect(client_t client, SnapRealm *realm, snapid_t seq,
+				  map<client_t,MClientSnap::ref>& updates);
+  Capability* try_reconnect_cap(CInode *in, Session *session);
+  void export_remaining_imported_caps();
+
+  //  realm inodes
+  set<CInode*> rejoin_pending_snaprealms;
+  // cap imports.  delayed snap parent opens.
+  map<client_t,set<CInode*> > delayed_imported_caps;
+
+  void do_cap_import(Session *session, CInode *in, Capability *cap,
+		     uint64_t p_cap_id, ceph_seq_t p_seq, ceph_seq_t p_mseq,
+		     int peer, int p_flags);
+  void do_delayed_cap_imports();
+  void rebuild_need_snapflush(CInode *head_in, SnapRealm *realm, client_t client,
+			      snapid_t snap_follows);
+  void open_snaprealms();
+
+  bool open_undef_inodes_dirfrags();
+  void opened_undef_inode(CInode *in);
+  void opened_undef_dirfrag(CDir *dir) {
+    rejoin_undef_dirfrags.erase(dir);
+  }
+
+  void reissue_all_caps();
+  
+
+  friend class Locker;
+  friend class Migrator;
+  friend class MDBalancer;
+
+  // StrayManager needs to be able to remove_inode() from us
+  // when it is done purging
+  friend class StrayManager;
+
+  // File size recovery
+private:
+  RecoveryQueue recovery_queue;
+  void identify_files_to_recover();
+public:
+  void start_files_to_recover();
+  void do_file_recover();
+  void queue_file_recover(CInode *in);
+  void _queued_file_recover_cow(CInode *in, MutationRef& mut);
+
+  // subsystems
+  std::unique_ptr<Migrator> migrator;
+
+ public:
+  explicit MDCache(MDSRank *m, PurgeQueue &purge_queue_);
+  ~MDCache();
+  void handle_conf_change(const std::set<std::string>& changed, const MDSMap& mds_map);
+  
+  // debug
+  void log_stat();
+
+  // root inode
+  CInode *get_root() { return root; }
+  CInode *get_myin() { return myin; }
+
+  size_t get_cache_size() { return lru.lru_get_size(); }
+
+  // trimming
+  std::pair<bool, uint64_t> trim(uint64_t count=0);
+private:
+  std::pair<bool, uint64_t> trim_lru(uint64_t count, expiremap& expiremap);
+  bool trim_dentry(CDentry *dn, expiremap& expiremap);
+  void trim_dirfrag(CDir *dir, CDir *con, expiremap& expiremap);
+  bool trim_inode(CDentry *dn, CInode *in, CDir *con, expiremap&);
+  void send_expire_messages(expiremap& expiremap);
+  void trim_non_auth();      // trim out trimmable non-auth items
+public:
+  bool trim_non_auth_subtree(CDir *directory);
+  void standby_trim_segment(LogSegment *ls);
+  void try_trim_non_auth_subtree(CDir *dir);
+  bool can_trim_non_auth_dirfrag(CDir *dir) {
+    return my_ambiguous_imports.count((dir)->dirfrag()) == 0 &&
+	   uncommitted_slave_rename_olddir.count(dir->inode) == 0;
+  }
+
+  /**
+   * For all unreferenced inodes, dirs, dentries below an inode, compose
+   * expiry messages.  This is used when giving up all replicas of entities
+   * for an MDS peer in the 'stopping' state, such that the peer can
+   * empty its cache and finish shutting down.
+   *
+   * We have to make sure we're only expiring un-referenced items to
+   * avoid interfering with ongoing stray-movement (we can't distinguish
+   * between the "moving my strays" and "waiting for my cache to empty"
+   * phases within 'stopping')
+   *
+   * @return false if we completed cleanly, true if caller should stop
+   *         expiring because we hit something with refs.
+   */
+  bool expire_recursive(CInode *in, expiremap& expiremap);
+
+  void trim_client_leases();
+  void check_memory_usage();
+
+  // shutdown
+private:
+  set<inodeno_t> shutdown_exporting_strays;
+  pair<dirfrag_t, string> shutdown_export_next;
+public:
+  void shutdown_start();
+  void shutdown_check();
+  bool shutdown_pass();
+  bool shutdown();                    // clear cache (ie at shutodwn)
+  bool shutdown_export_strays();
+  void shutdown_export_stray_finish(inodeno_t ino) {
+    if (shutdown_exporting_strays.erase(ino))
+      shutdown_export_strays();
+  }
+
+  bool did_shutdown_log_cap = false;
+
+  // inode_map
+  bool have_inode(vinodeno_t vino) {
+    if (vino.snapid == CEPH_NOSNAP)
+      return inode_map.count(vino.ino) ? true : false;
+    else
+      return snap_inode_map.count(vino) ? true : false;
+  }
+  bool have_inode(inodeno_t ino, snapid_t snap=CEPH_NOSNAP) {
+    return have_inode(vinodeno_t(ino, snap));
+  }
+  CInode* get_inode(vinodeno_t vino) {
+    if (vino.snapid == CEPH_NOSNAP) {
+      auto p = inode_map.find(vino.ino);
+      if (p != inode_map.end())
+	return p->second;
+    } else {
+      auto p = snap_inode_map.find(vino);
+      if (p != snap_inode_map.end())
+	return p->second;
+    }
+    return NULL;
+  }
+  CInode* get_inode(inodeno_t ino, snapid_t s=CEPH_NOSNAP) {
+    return get_inode(vinodeno_t(ino, s));
+  }
+  CInode* lookup_snap_inode(vinodeno_t vino) {
+    auto p = snap_inode_map.lower_bound(vino);
+    if (p != snap_inode_map.end() &&
+	p->second->ino() == vino.ino && p->second->first <= vino.snapid)
+      return p->second;
+    return NULL;
+  }
+
+  CDir* get_dirfrag(dirfrag_t df) {
+    CInode *in = get_inode(df.ino);
+    if (!in)
+      return NULL;
+    return in->get_dirfrag(df.frag);
+  }
+  CDir* get_dirfrag(inodeno_t ino, std::string_view dn) {
+    CInode *in = get_inode(ino);
+    if (!in)
+      return NULL;
+    frag_t fg = in->pick_dirfrag(dn);
+    return in->get_dirfrag(fg);
+  }
+  CDir* get_force_dirfrag(dirfrag_t df, bool replay) {
+    CInode *diri = get_inode(df.ino);
+    if (!diri)
+      return NULL;
+    CDir *dir = force_dir_fragment(diri, df.frag, replay);
+    if (!dir)
+      dir = diri->get_dirfrag(df.frag);
+    return dir;
+  }
+
+  MDSCacheObject *get_object(const MDSCacheObjectInfo &info);
+
+  
+
+ public:
+  void add_inode(CInode *in);
+
+  void remove_inode(CInode *in);
+ protected:
+  void touch_inode(CInode *in) {
+    if (in->get_parent_dn())
+      touch_dentry(in->get_projected_parent_dn());
+  }
+public:
+  void touch_dentry(CDentry *dn) {
+    if (dn->state_test(CDentry::STATE_BOTTOMLRU)) {
+      bottom_lru.lru_midtouch(dn);
+    } else {
+      if (dn->is_auth())
+	lru.lru_touch(dn);
+      else
+	lru.lru_midtouch(dn);
+    }
+  }
+  void touch_dentry_bottom(CDentry *dn) {
+    if (dn->state_test(CDentry::STATE_BOTTOMLRU))
+      return;
+    lru.lru_bottouch(dn);
+  }
+protected:
+
+  void inode_remove_replica(CInode *in, mds_rank_t rep, bool rejoin,
+			    set<SimpleLock *>& gather_locks);
+  void dentry_remove_replica(CDentry *dn, mds_rank_t rep, set<SimpleLock *>& gather_locks);
+
+  void rename_file(CDentry *srcdn, CDentry *destdn);
+
+ public:
+  // truncate
+  void truncate_inode(CInode *in, LogSegment *ls);
+  void _truncate_inode(CInode *in, LogSegment *ls);
+  void truncate_inode_finish(CInode *in, LogSegment *ls);
+  void truncate_inode_logged(CInode *in, MutationRef& mut);
+
+  void add_recovered_truncate(CInode *in, LogSegment *ls);
+  void remove_recovered_truncate(CInode *in, LogSegment *ls);
+  void start_recovered_truncates();
+
+
+ public:
+  CDir *get_auth_container(CDir *in);
+  CDir *get_export_container(CDir *dir);
+  void find_nested_exports(CDir *dir, set<CDir*>& s);
+  void find_nested_exports_under(CDir *import, CDir *dir, set<CDir*>& s);
+
+
+private:
+  bool opening_root = false, open = false;
+  MDSContext::vec waiting_for_open;
+
+public:
+  void init_layouts();
+  void create_unlinked_system_inode(CInode *in, inodeno_t ino,
+                                    int mode) const;
+  CInode *create_system_inode(inodeno_t ino, int mode);
+  CInode *create_root_inode();
+
+  void create_empty_hierarchy(MDSGather *gather);
+  void create_mydir_hierarchy(MDSGather *gather);
+
+  bool is_open() { return open; }
+  void wait_for_open(MDSContext *c) {
+    waiting_for_open.push_back(c);
+  }
+
+  void open_root_inode(MDSContext *c);
+  void open_root();
+  void open_mydir_inode(MDSContext *c);
+  void open_mydir_frag(MDSContext *c);
+  void populate_mydir();
+
+  void _create_system_file(CDir *dir, std::string_view name, CInode *in, MDSContext *fin);
+  void _create_system_file_finish(MutationRef& mut, CDentry *dn,
+                                  version_t dpv, MDSContext *fin);
+
+  void open_foreign_mdsdir(inodeno_t ino, MDSContext *c);
+  CDir *get_stray_dir(CInode *in);
+  CDentry *get_or_create_stray_dentry(CInode *in);
+
+  /**
+   * Find the given dentry (and whether it exists or not), its ancestors,
+   * and get them all into memory and usable on this MDS. This function
+   * makes a best-effort attempt to load everything; if it needs to
+   * go away and do something then it will put the request on a waitlist.
+   * It prefers the mdr, then the req, then the fin. (At least one of these
+   * must be non-null.)
+   *
+   * At least one of the params mdr, req, and fin must be non-null.
+   *
+   * @param mdr The MDRequest associated with the path. Can be null.
+   * @param cf A MDSContextFactory for waiter building.
+   * @param path The path to traverse to.
+   * @param pdnvec Data return parameter -- on success, contains a
+   * vector of dentries. On failure, is either empty or contains the
+   * full trace of traversable dentries.
+   * @param pin Data return parameter -- if successful, points to the inode
+   * associated with filepath. If unsuccessful, is null.
+   * @param onfail Specifies different lookup failure behaviors. If set to
+   * MDS_TRAVERSE_DISCOVERXLOCK, path_traverse will succeed on null
+   * dentries (instead of returning -ENOENT). If set to
+   * MDS_TRAVERSE_FORWARD, it will forward the request to the auth
+   * MDS if that becomes appropriate (ie, if it doesn't know the contents
+   * of a directory). If set to MDS_TRAVERSE_DISCOVER, it
+   * will attempt to look up the path from a different MDS (and bring them
+   * into its cache as replicas).
+   *
+   * @returns 0 on success, 1 on "not done yet", 2 on "forwarding", -errno otherwise.
+   * If it returns 1, the requester associated with this call has been placed
+   * on the appropriate waitlist, and it should unwind itself and back out.
+   * If it returns 2 the request has been forwarded, and again the requester
+   * should unwind itself and back out.
+   */
+  int path_traverse(MDRequestRef& mdr, MDSContextFactory& cf, const filepath& path,
+		    vector<CDentry*> *pdnvec, CInode **pin, int onfail);
+
+  CInode *cache_traverse(const filepath& path);
+
+  void open_remote_dirfrag(CInode *diri, frag_t fg, MDSContext *fin);
+  CInode *get_dentry_inode(CDentry *dn, MDRequestRef& mdr, bool projected=false);
+
+  bool parallel_fetch(map<inodeno_t,filepath>& pathmap, set<inodeno_t>& missing);
+  bool parallel_fetch_traverse_dir(inodeno_t ino, filepath& path, 
+				   set<CDir*>& fetch_queue, set<inodeno_t>& missing,
+				   C_GatherBuilder &gather_bld);
+
+  void open_remote_dentry(CDentry *dn, bool projected, MDSContext *fin,
+			  bool want_xlocked=false);
+  void _open_remote_dentry_finish(CDentry *dn, inodeno_t ino, MDSContext *fin,
+				  bool want_xlocked, int r);
+
+  void make_trace(vector<CDentry*>& trace, CInode *in);
+
+protected:
+  struct open_ino_info_t {
+    vector<inode_backpointer_t> ancestors;
+    set<mds_rank_t> checked;
+    mds_rank_t checking;
+    mds_rank_t auth_hint;
+    bool check_peers;
+    bool fetch_backtrace;
+    bool discover;
+    bool want_replica;
+    bool want_xlocked;
+    version_t tid;
+    int64_t pool;
+    int last_err;
+    MDSContext::vec waiters;
+    open_ino_info_t() : checking(MDS_RANK_NONE), auth_hint(MDS_RANK_NONE),
+      check_peers(true), fetch_backtrace(true), discover(false),
+      want_replica(false), want_xlocked(false), tid(0), pool(-1),
+      last_err(0) {}
+  };
+  ceph_tid_t open_ino_last_tid = 0;
+  map<inodeno_t,open_ino_info_t> opening_inodes;
+
+  void _open_ino_backtrace_fetched(inodeno_t ino, bufferlist& bl, int err);
+  void _open_ino_parent_opened(inodeno_t ino, int ret);
+  void _open_ino_traverse_dir(inodeno_t ino, open_ino_info_t& info, int err);
+  void _open_ino_fetch_dir(inodeno_t ino, const MMDSOpenIno::const_ref &m, CDir *dir, bool parent);
+  int open_ino_traverse_dir(inodeno_t ino, const MMDSOpenIno::const_ref &m,
+			    const vector<inode_backpointer_t>& ancestors,
+			    bool discover, bool want_xlocked, mds_rank_t *hint);
+  void open_ino_finish(inodeno_t ino, open_ino_info_t& info, int err);
+  void do_open_ino(inodeno_t ino, open_ino_info_t& info, int err);
+  void do_open_ino_peer(inodeno_t ino, open_ino_info_t& info);
+  void handle_open_ino(const MMDSOpenIno::const_ref &m, int err=0);
+  void handle_open_ino_reply(const MMDSOpenInoReply::const_ref &m);
+  friend class C_IO_MDC_OpenInoBacktraceFetched;
+  friend struct C_MDC_OpenInoTraverseDir;
+  friend struct C_MDC_OpenInoParentOpened;
+
+public:
+  void kick_open_ino_peers(mds_rank_t who);
+  void open_ino(inodeno_t ino, int64_t pool, MDSContext *fin,
+		bool want_replica=true, bool want_xlocked=false);
+  
+  // -- find_ino_peer --
+  struct find_ino_peer_info_t {
+    inodeno_t ino;
+    ceph_tid_t tid;
+    MDSContext *fin;
+    mds_rank_t hint;
+    mds_rank_t checking;
+    set<mds_rank_t> checked;
+
+    find_ino_peer_info_t() : tid(0), fin(NULL), hint(MDS_RANK_NONE), checking(MDS_RANK_NONE) {}
+  };
+
+  map<ceph_tid_t, find_ino_peer_info_t> find_ino_peer;
+  ceph_tid_t find_ino_peer_last_tid = 0;
+
+  void find_ino_peers(inodeno_t ino, MDSContext *c, mds_rank_t hint=MDS_RANK_NONE);
+  void _do_find_ino_peer(find_ino_peer_info_t& fip);
+  void handle_find_ino(const MMDSFindIno::const_ref &m);
+  void handle_find_ino_reply(const MMDSFindInoReply::const_ref &m);
+  void kick_find_ino_peers(mds_rank_t who);
+
+  // -- snaprealms --
+private:
+  SnapRealm *global_snaprealm = nullptr;
+public:
+  SnapRealm *get_global_snaprealm() const { return global_snaprealm; }
+  void create_global_snaprealm();
+  void do_realm_invalidate_and_update_notify(CInode *in, int snapop, bool notify_clients=true);
+  void send_snap_update(CInode *in, version_t stid, int snap_op);
+  void handle_snap_update(const MMDSSnapUpdate::const_ref &m);
+  void notify_global_snaprealm_update(int snap_op);
+
+  // -- stray --
+public:
+  void fetch_backtrace(inodeno_t ino, int64_t pool, bufferlist& bl, Context *fin);
+  uint64_t get_num_strays() const { return stray_manager.get_num_strays(); }
+
+protected:
+  void scan_stray_dir(dirfrag_t next=dirfrag_t());
+  StrayManager stray_manager;
+  friend struct C_MDC_RetryScanStray;
+
+  // == messages ==
+ public:
+  void dispatch(const Message::const_ref &m);
+
+ protected:
+  // -- replicas --
+  void handle_discover(const MDiscover::const_ref &dis);
+  void handle_discover_reply(const MDiscoverReply::const_ref &m);
+  friend class C_MDC_Join;
+
+public:
+  void replicate_dir(CDir *dir, mds_rank_t to, bufferlist& bl);
+  void replicate_dentry(CDentry *dn, mds_rank_t to, bufferlist& bl);
+  void replicate_inode(CInode *in, mds_rank_t to, bufferlist& bl,
+		       uint64_t features);
+  
+  CDir* add_replica_dir(bufferlist::const_iterator& p, CInode *diri, mds_rank_t from, MDSContext::vec& finished);
+  CDentry *add_replica_dentry(bufferlist::const_iterator& p, CDir *dir, MDSContext::vec& finished);
+  CInode *add_replica_inode(bufferlist::const_iterator& p, CDentry *dn, MDSContext::vec& finished);
+
+  void replicate_stray(CDentry *straydn, mds_rank_t who, bufferlist& bl);
+  CDentry *add_replica_stray(const bufferlist &bl, mds_rank_t from);
+
+  // -- namespace --
+public:
+  void send_dentry_link(CDentry *dn, MDRequestRef& mdr);
+  void send_dentry_unlink(CDentry *dn, CDentry *straydn, MDRequestRef& mdr);
+protected:
+  void handle_dentry_link(const MDentryLink::const_ref &m);
+  void handle_dentry_unlink(const MDentryUnlink::const_ref &m);
+
+
+  // -- fragmenting --
+private:
+  struct ufragment {
+    int bits;
+    bool committed;
+    LogSegment *ls;
+    MDSContext::vec waiters;
+    frag_vec_t old_frags;
+    bufferlist rollback;
+    ufragment() : bits(0), committed(false), ls(NULL) {}
+  };
+  map<dirfrag_t, ufragment> uncommitted_fragments;
+
+  struct fragment_info_t {
+    int bits;
+    list<CDir*> dirs;
+    list<CDir*> resultfrags;
+    MDRequestRef mdr;
+    set<mds_rank_t> notify_ack_waiting;
+    bool finishing = false;
+
+    // for deadlock detection
+    bool all_frozen = false;
+    utime_t last_cum_auth_pins_change;
+    int last_cum_auth_pins = 0;
+    int num_remote_waiters = 0;	// number of remote authpin waiters
+    fragment_info_t() {}
+    bool is_fragmenting() { return !resultfrags.empty(); }
+    uint64_t get_tid() { return mdr ? mdr->reqid.tid : 0; }
+  };
+  map<dirfrag_t,fragment_info_t> fragments;
+  typedef map<dirfrag_t,fragment_info_t>::iterator fragment_info_iterator;
+
+  void adjust_dir_fragments(CInode *diri, frag_t basefrag, int bits,
+			    list<CDir*>& frags, MDSContext::vec& waiters, bool replay);
+  void adjust_dir_fragments(CInode *diri,
+			    list<CDir*>& srcfrags,
+			    frag_t basefrag, int bits,
+			    list<CDir*>& resultfrags, 
+			    MDSContext::vec& waiters,
+			    bool replay);
+  CDir *force_dir_fragment(CInode *diri, frag_t fg, bool replay=true);
+  void get_force_dirfrag_bound_set(const vector<dirfrag_t>& dfs, set<CDir*>& bounds);
+
+  bool can_fragment(CInode *diri, list<CDir*>& dirs);
+  void fragment_freeze_dirs(list<CDir*>& dirs);
+  void fragment_mark_and_complete(MDRequestRef& mdr);
+  void fragment_frozen(MDRequestRef& mdr, int r);
+  void fragment_unmark_unfreeze_dirs(list<CDir*>& dirs);
+  void fragment_drop_locks(fragment_info_t &info);
+  void fragment_maybe_finish(const fragment_info_iterator& it);
+  void dispatch_fragment_dir(MDRequestRef& mdr);
+  void _fragment_logged(MDRequestRef& mdr);
+  void _fragment_stored(MDRequestRef& mdr);
+  void _fragment_committed(dirfrag_t f, const MDRequestRef& mdr);
+  void _fragment_old_purged(dirfrag_t f, int bits, const MDRequestRef& mdr);
+
+  friend class EFragment;
+  friend class C_MDC_FragmentFrozen;
+  friend class C_MDC_FragmentMarking;
+  friend class C_MDC_FragmentPrep;
+  friend class C_MDC_FragmentStore;
+  friend class C_MDC_FragmentCommit;
+  friend class C_IO_MDC_FragmentPurgeOld;
+
+  void handle_fragment_notify(const MMDSFragmentNotify::const_ref &m);
+  void handle_fragment_notify_ack(const MMDSFragmentNotifyAck::const_ref &m);
+
+  void add_uncommitted_fragment(dirfrag_t basedirfrag, int bits, const frag_vec_t& old_frag,
+				LogSegment *ls, bufferlist *rollback=NULL);
+  void finish_uncommitted_fragment(dirfrag_t basedirfrag, int op);
+  void rollback_uncommitted_fragment(dirfrag_t basedirfrag, frag_vec_t&& old_frags);
+
+
+  DecayCounter trim_counter;
+
+public:
+  void wait_for_uncommitted_fragment(dirfrag_t dirfrag, MDSContext *c) {
+    uncommitted_fragments.at(dirfrag).waiters.push_back(c);
+  }
+  bool is_any_uncommitted_fragment() const {
+    return !uncommitted_fragments.empty();
+  }
+  void wait_for_uncommitted_fragments(MDSContext* finisher);
+  void rollback_uncommitted_fragments();
+
+  void split_dir(CDir *dir, int byn);
+  void merge_dir(CInode *diri, frag_t fg);
+
+  void find_stale_fragment_freeze();
+  void fragment_freeze_inc_num_waiters(CDir *dir);
+  bool fragment_are_all_frozen(CDir *dir);
+  int get_num_fragmenting_dirs() { return fragments.size(); }
+
+  // -- updates --
+  //int send_inode_updates(CInode *in);
+  //void handle_inode_update(MInodeUpdate *m);
+
+  int send_dir_updates(CDir *in, bool bcast=false);
+  void handle_dir_update(const MDirUpdate::const_ref &m);
+
+  // -- cache expiration --
+  void handle_cache_expire(const MCacheExpire::const_ref &m);
+  // delayed cache expire
+  map<CDir*, expiremap> delayed_expire; // subtree root -> expire msg
+  void process_delayed_expire(CDir *dir);
+  void discard_delayed_expire(CDir *dir);
+
+  // -- mdsmap --
+  void handle_mdsmap(const MDSMap &mdsmap);
+
+protected:
+  int dump_cache(std::string_view fn, Formatter *f);
+public:
+  int dump_cache() { return dump_cache(NULL, NULL); }
+  int dump_cache(std::string_view filename);
+  int dump_cache(Formatter *f);
+  void dump_tree(CInode *in, const int cur_depth, const int max_depth, Formatter *f);
+
+  void cache_status(Formatter *f);
+
+  void dump_resolve_status(Formatter *f) const;
+  void dump_rejoin_status(Formatter *f) const;
+
+  // == crap fns ==
+ public:
+  void show_cache();
+  void show_subtrees(int dbl=10, bool force_print=false);
+
+  CInode *hack_pick_random_inode() {
+    ceph_assert(!inode_map.empty());
+    int n = rand() % inode_map.size();
+    auto p = inode_map.begin();
+    while (n--) ++p;
+    return p->second;
+  }
+
+protected:
+  void flush_dentry_work(MDRequestRef& mdr);
+  /**
+   * Resolve path to a dentry and pass it onto the ScrubStack.
+   *
+   * TODO: return enough information to the original mdr formatter
+   * and completion that they can subsequeuntly check the progress of
+   * this scrub (we won't block them on a whole scrub as it can take a very
+   * long time)
+   */
+  void enqueue_scrub_work(MDRequestRef& mdr);
+  void recursive_scrub_finish(const ScrubHeaderRef& header);
+  void repair_inode_stats_work(MDRequestRef& mdr);
+  void repair_dirfrag_stats_work(MDRequestRef& mdr);
+  void upgrade_inode_snaprealm_work(MDRequestRef& mdr);
+  friend class C_MDC_RespondInternalRequest;
+public:
+  void flush_dentry(std::string_view path, Context *fin);
+  /**
+   * Create and start an OP_ENQUEUE_SCRUB
+   */
+  void enqueue_scrub(std::string_view path, std::string_view tag,
+                     bool force, bool recursive, bool repair,
+		     Formatter *f, Context *fin);
+  void repair_inode_stats(CInode *diri);
+  void repair_dirfrag_stats(CDir *dir);
+  void upgrade_inode_snaprealm(CInode *in);
+
+public:
+  /* Because exports may fail, this set lets us keep track of inodes that need exporting. */
+  std::set<CInode *> export_pin_queue;
+  std::set<CInode *> export_pin_delayed_queue;
+
+  OpenFileTable open_file_table;
+
+private:
+  std::thread upkeeper;
+  ceph::mutex upkeep_mutex = ceph::make_mutex("MDCache::upkeep_mutex");
+  ceph::condition_variable upkeep_cvar;
+  time upkeep_last_trim = time::min();
+  time upkeep_last_release = time::min();
+  std::atomic<bool> upkeep_trim_shutdown{false};
+};
+
+class C_MDS_RetryRequest : public MDSInternalContext {
+  MDCache *cache;
+  MDRequestRef mdr;
+ public:
+  C_MDS_RetryRequest(MDCache *c, MDRequestRef& r);
+  void finish(int r) override;
+};
+
+#endif