Adding upstream version 14.2.21.upstream/14.2.21upstream

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

1 files changed, 1178 insertions, 0 deletions

diff --git a/src/rgw/rgw_metadata.cc b/src/rgw/rgw_metadata.cc
new file mode 100644
index 00000000..9741cba9
--- /dev/null
+++ b/src/rgw/rgw_metadata.cc
@@ -0,0 +1,1178 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include <boost/intrusive_ptr.hpp>
+#include "common/ceph_json.h"
+#include "common/errno.h"
+#include "rgw_metadata.h"
+#include "rgw_coroutine.h"
+#include "cls/version/cls_version_types.h"
+
+#include "rgw_rados.h"
+#include "rgw_zone.h"
+#include "rgw_tools.h"
+
+#include "rgw_cr_rados.h"
+
+#include "services/svc_zone.h"
+
+#include "include/ceph_assert.h"
+
+#include <boost/asio/yield.hpp>
+
+#define dout_subsys ceph_subsys_rgw
+
+void LogStatusDump::dump(Formatter *f) const {
+  string s;
+  switch (status) {
+    case MDLOG_STATUS_WRITE:
+      s = "write";
+      break;
+    case MDLOG_STATUS_SETATTRS:
+      s = "set_attrs";
+      break;
+    case MDLOG_STATUS_REMOVE:
+      s = "remove";
+      break;
+    case MDLOG_STATUS_COMPLETE:
+      s = "complete";
+      break;
+    case MDLOG_STATUS_ABORT:
+      s = "abort";
+      break;
+    default:
+      s = "unknown";
+      break;
+  }
+  encode_json("status", s, f);
+}
+
+void RGWMetadataLogData::encode(bufferlist& bl) const {
+  ENCODE_START(1, 1, bl);
+  encode(read_version, bl);
+  encode(write_version, bl);
+  uint32_t s = (uint32_t)status;
+  encode(s, bl);
+  ENCODE_FINISH(bl);
+}
+
+void RGWMetadataLogData::decode(bufferlist::const_iterator& bl) {
+   DECODE_START(1, bl);
+   decode(read_version, bl);
+   decode(write_version, bl);
+   uint32_t s;
+   decode(s, bl);
+   status = (RGWMDLogStatus)s;
+   DECODE_FINISH(bl);
+}
+
+void RGWMetadataLogData::dump(Formatter *f) const {
+  encode_json("read_version", read_version, f);
+  encode_json("write_version", write_version, f);
+  encode_json("status", LogStatusDump(status), f);
+}
+
+void decode_json_obj(RGWMDLogStatus& status, JSONObj *obj) {
+  string s;
+  JSONDecoder::decode_json("status", s, obj);
+  if (s == "complete") {
+    status = MDLOG_STATUS_COMPLETE;
+  } else if (s == "write") {
+    status = MDLOG_STATUS_WRITE;
+  } else if (s == "remove") {
+    status = MDLOG_STATUS_REMOVE;
+  } else if (s == "set_attrs") {
+    status = MDLOG_STATUS_SETATTRS;
+  } else if (s == "abort") {
+    status = MDLOG_STATUS_ABORT;
+  } else {
+    status = MDLOG_STATUS_UNKNOWN;
+  }
+}
+
+void RGWMetadataLogData::decode_json(JSONObj *obj) {
+  JSONDecoder::decode_json("read_version", read_version, obj);
+  JSONDecoder::decode_json("write_version", write_version, obj);
+  JSONDecoder::decode_json("status", status, obj);
+}
+
+
+int RGWMetadataLog::add_entry(RGWMetadataHandler *handler, const string& section, const string& key, bufferlist& bl) {
+  if (!store->svc.zone->need_to_log_metadata())
+    return 0;
+
+  string oid;
+
+  string hash_key;
+  handler->get_hash_key(section, key, hash_key);
+
+  int shard_id;
+  store->shard_name(prefix, cct->_conf->rgw_md_log_max_shards, hash_key, oid, &shard_id);
+  mark_modified(shard_id);
+  real_time now = real_clock::now();
+  return store->time_log_add(oid, now, section, key, bl);
+}
+
+int RGWMetadataLog::store_entries_in_shard(list<cls_log_entry>& entries, int shard_id, librados::AioCompletion *completion)
+{
+  string oid;
+
+  mark_modified(shard_id);
+  store->shard_name(prefix, shard_id, oid);
+  return store->time_log_add(oid, entries, completion, false);
+}
+
+void RGWMetadataLog::init_list_entries(int shard_id, const real_time& from_time, const real_time& end_time, 
+                                       string& marker, void **handle)
+{
+  LogListCtx *ctx = new LogListCtx();
+
+  ctx->cur_shard = shard_id;
+  ctx->from_time = from_time;
+  ctx->end_time  = end_time;
+  ctx->marker    = marker;
+
+  get_shard_oid(ctx->cur_shard, ctx->cur_oid);
+
+  *handle = (void *)ctx;
+}
+
+void RGWMetadataLog::complete_list_entries(void *handle) {
+  LogListCtx *ctx = static_cast<LogListCtx *>(handle);
+  delete ctx;
+}
+
+int RGWMetadataLog::list_entries(void *handle,
+				 int max_entries,
+				 list<cls_log_entry>& entries,
+				 string *last_marker,
+				 bool *truncated) {
+  LogListCtx *ctx = static_cast<LogListCtx *>(handle);
+
+  if (!max_entries) {
+    *truncated = false;
+    return 0;
+  }
+
+  std::string next_marker;
+  int ret = store->time_log_list(ctx->cur_oid, ctx->from_time, ctx->end_time,
+				 max_entries, entries, ctx->marker,
+				 &next_marker, truncated);
+  if ((ret < 0) && (ret != -ENOENT))
+    return ret;
+
+  ctx->marker = std::move(next_marker);
+  if (last_marker) {
+    *last_marker = ctx->marker;
+  }
+
+  if (ret == -ENOENT)
+    *truncated = false;
+
+  return 0;
+}
+
+int RGWMetadataLog::get_info(int shard_id, RGWMetadataLogInfo *info)
+{
+  string oid;
+  get_shard_oid(shard_id, oid);
+
+  cls_log_header header;
+
+  int ret = store->time_log_info(oid, &header);
+  if ((ret < 0) && (ret != -ENOENT))
+    return ret;
+
+  info->marker = header.max_marker;
+  info->last_update = header.max_time.to_real_time();
+
+  return 0;
+}
+
+static void _mdlog_info_completion(librados::completion_t cb, void *arg)
+{
+  auto infoc = static_cast<RGWMetadataLogInfoCompletion *>(arg);
+  infoc->finish(cb);
+  infoc->put(); // drop the ref from get_info_async()
+}
+
+RGWMetadataLogInfoCompletion::RGWMetadataLogInfoCompletion(info_callback_t cb)
+  : completion(librados::Rados::aio_create_completion((void *)this, nullptr,
+                                                      _mdlog_info_completion)),
+    callback(cb)
+{
+}
+
+RGWMetadataLogInfoCompletion::~RGWMetadataLogInfoCompletion()
+{
+  completion->release();
+}
+
+int RGWMetadataLog::get_info_async(int shard_id, RGWMetadataLogInfoCompletion *completion)
+{
+  string oid;
+  get_shard_oid(shard_id, oid);
+
+  completion->get(); // hold a ref until the completion fires
+
+  return store->time_log_info_async(completion->get_io_ctx(), oid,
+                                    &completion->get_header(),
+                                    completion->get_completion());
+}
+
+int RGWMetadataLog::trim(int shard_id, const real_time& from_time, const real_time& end_time,
+                         const string& start_marker, const string& end_marker)
+{
+  string oid;
+  get_shard_oid(shard_id, oid);
+
+  return store->time_log_trim(oid, from_time, end_time, start_marker,
+                              end_marker, nullptr);
+}
+  
+int RGWMetadataLog::lock_exclusive(int shard_id, timespan duration, string& zone_id, string& owner_id) {
+  string oid;
+  get_shard_oid(shard_id, oid);
+
+  return store->lock_exclusive(store->svc.zone->get_zone_params().log_pool, oid, duration, zone_id, owner_id);
+}
+
+int RGWMetadataLog::unlock(int shard_id, string& zone_id, string& owner_id) {
+  string oid;
+  get_shard_oid(shard_id, oid);
+
+  return store->unlock(store->svc.zone->get_zone_params().log_pool, oid, zone_id, owner_id);
+}
+
+void RGWMetadataLog::mark_modified(int shard_id)
+{
+  lock.get_read();
+  if (modified_shards.find(shard_id) != modified_shards.end()) {
+    lock.unlock();
+    return;
+  }
+  lock.unlock();
+
+  RWLock::WLocker wl(lock);
+  modified_shards.insert(shard_id);
+}
+
+void RGWMetadataLog::read_clear_modified(set<int> &modified)
+{
+  RWLock::WLocker wl(lock);
+  modified.swap(modified_shards);
+  modified_shards.clear();
+}
+
+obj_version& RGWMetadataObject::get_version()
+{
+  return objv;
+}
+
+class RGWMetadataTopHandler : public RGWMetadataHandler {
+  struct iter_data {
+    set<string> sections;
+    set<string>::iterator iter;
+  };
+
+public:
+  RGWMetadataTopHandler() {}
+
+  string get_type() override { return string(); }
+
+  int get(RGWRados *store, string& entry, RGWMetadataObject **obj) override { return -ENOTSUP; }
+  int put(RGWRados *store, string& entry, RGWObjVersionTracker& objv_tracker,
+                  real_time mtime, JSONObj *obj, sync_type_t sync_type) override { return -ENOTSUP; }
+
+  virtual void get_pool_and_oid(RGWRados *store, const string& key, rgw_pool& pool, string& oid) override {}
+
+  int remove(RGWRados *store, string& entry, RGWObjVersionTracker& objv_tracker) override { return -ENOTSUP; }
+
+  int list_keys_init(RGWRados *store, const string& marker, void **phandle) override {
+    iter_data *data = new iter_data;
+    list<string> sections;
+    store->meta_mgr->get_sections(sections);
+    for (auto& s : sections) {
+      data->sections.insert(s);
+    }
+    data->iter = data->sections.lower_bound(marker);
+
+    *phandle = data;
+
+    return 0;
+  }
+  int list_keys_next(void *handle, int max, list<string>& keys, bool *truncated) override  {
+    iter_data *data = static_cast<iter_data *>(handle);
+    for (int i = 0; i < max && data->iter != data->sections.end(); ++i, ++(data->iter)) {
+      keys.push_back(*data->iter);
+    }
+
+    *truncated = (data->iter != data->sections.end());
+
+    return 0;
+  }
+  void list_keys_complete(void *handle) override {
+    iter_data *data = static_cast<iter_data *>(handle);
+
+    delete data;
+  }
+
+  virtual string get_marker(void *handle) override {
+    iter_data *data = static_cast<iter_data *>(handle);
+
+    if (data->iter != data->sections.end()) {
+      return *(data->iter);
+    }
+
+    return string();
+  }
+};
+
+static RGWMetadataTopHandler md_top_handler;
+
+
+RGWMetadataManager::RGWMetadataManager(CephContext *_cct, RGWRados *_store)
+  : cct(_cct), store(_store)
+{
+}
+
+RGWMetadataManager::~RGWMetadataManager()
+{
+  map<string, RGWMetadataHandler *>::iterator iter;
+
+  for (iter = handlers.begin(); iter != handlers.end(); ++iter) {
+    delete iter->second;
+  }
+
+  handlers.clear();
+}
+
+const std::string RGWMetadataLogHistory::oid = "meta.history";
+
+namespace {
+
+int read_history(RGWRados *store, RGWMetadataLogHistory *state,
+                 RGWObjVersionTracker *objv_tracker)
+{
+  auto obj_ctx = store->svc.sysobj->init_obj_ctx();
+  auto& pool = store->svc.zone->get_zone_params().log_pool;
+  const auto& oid = RGWMetadataLogHistory::oid;
+  bufferlist bl;
+  int ret = rgw_get_system_obj(store, obj_ctx, pool, oid, bl, objv_tracker, nullptr);
+  if (ret < 0) {
+    return ret;
+  }
+  if (bl.length() == 0) {
+    /* bad history object, remove it */
+    rgw_raw_obj obj(pool, oid);
+    auto sysobj = obj_ctx.get_obj(obj);
+    ret = sysobj.wop().remove();
+    if (ret < 0) {
+      ldout(store->ctx(), 0) << "ERROR: meta history is empty, but cannot remove it (" << cpp_strerror(-ret) << ")" << dendl;
+      return ret;
+    }
+    return -ENOENT;
+  }
+  try {
+    auto p = bl.cbegin();
+    state->decode(p);
+  } catch (buffer::error& e) {
+    ldout(store->ctx(), 1) << "failed to decode the mdlog history: "
+        << e.what() << dendl;
+    return -EIO;
+  }
+  return 0;
+}
+
+int write_history(RGWRados *store, const RGWMetadataLogHistory& state,
+                  RGWObjVersionTracker *objv_tracker, bool exclusive = false)
+{
+  bufferlist bl;
+  state.encode(bl);
+
+  auto& pool = store->svc.zone->get_zone_params().log_pool;
+  const auto& oid = RGWMetadataLogHistory::oid;
+  return rgw_put_system_obj(store, pool, oid, bl,
+                            exclusive, objv_tracker, real_time{});
+}
+
+using Cursor = RGWPeriodHistory::Cursor;
+
+/// read the mdlog history and use it to initialize the given cursor
+class ReadHistoryCR : public RGWCoroutine {
+  RGWRados *store;
+  Cursor *cursor;
+  RGWObjVersionTracker *objv_tracker;
+  RGWMetadataLogHistory state;
+ public:
+  ReadHistoryCR(RGWRados *store, Cursor *cursor,
+                RGWObjVersionTracker *objv_tracker)
+    : RGWCoroutine(store->ctx()), store(store), cursor(cursor),
+      objv_tracker(objv_tracker)
+  {}
+
+  int operate() {
+    reenter(this) {
+      yield {
+        rgw_raw_obj obj{store->svc.zone->get_zone_params().log_pool,
+                        RGWMetadataLogHistory::oid};
+        constexpr bool empty_on_enoent = false;
+
+        using ReadCR = RGWSimpleRadosReadCR<RGWMetadataLogHistory>;
+        call(new ReadCR(store->get_async_rados(), store->svc.sysobj, obj,
+                        &state, empty_on_enoent, objv_tracker));
+      }
+      if (retcode < 0) {
+        ldout(cct, 1) << "failed to read mdlog history: "
+            << cpp_strerror(retcode) << dendl;
+        return set_cr_error(retcode);
+      }
+      *cursor = store->period_history->lookup(state.oldest_realm_epoch);
+      if (!*cursor) {
+        return set_cr_error(cursor->get_error());
+      }
+
+      ldout(cct, 10) << "read mdlog history with oldest period id="
+          << state.oldest_period_id << " realm_epoch="
+          << state.oldest_realm_epoch << dendl;
+      return set_cr_done();
+    }
+    return 0;
+  }
+};
+
+/// write the given cursor to the mdlog history
+class WriteHistoryCR : public RGWCoroutine {
+  RGWRados *store;
+  Cursor cursor;
+  RGWObjVersionTracker *objv;
+  RGWMetadataLogHistory state;
+ public:
+  WriteHistoryCR(RGWRados *store, const Cursor& cursor,
+                 RGWObjVersionTracker *objv)
+    : RGWCoroutine(store->ctx()), store(store), cursor(cursor), objv(objv)
+  {}
+
+  int operate() {
+    reenter(this) {
+      state.oldest_period_id = cursor.get_period().get_id();
+      state.oldest_realm_epoch = cursor.get_epoch();
+
+      yield {
+        rgw_raw_obj obj{store->svc.zone->get_zone_params().log_pool,
+                        RGWMetadataLogHistory::oid};
+
+        using WriteCR = RGWSimpleRadosWriteCR<RGWMetadataLogHistory>;
+        call(new WriteCR(store->get_async_rados(), store->svc.sysobj, obj, state, objv));
+      }
+      if (retcode < 0) {
+        ldout(cct, 1) << "failed to write mdlog history: "
+            << cpp_strerror(retcode) << dendl;
+        return set_cr_error(retcode);
+      }
+
+      ldout(cct, 10) << "wrote mdlog history with oldest period id="
+          << state.oldest_period_id << " realm_epoch="
+          << state.oldest_realm_epoch << dendl;
+      return set_cr_done();
+    }
+    return 0;
+  }
+};
+
+/// update the mdlog history to reflect trimmed logs
+class TrimHistoryCR : public RGWCoroutine {
+  RGWRados *store;
+  const Cursor cursor; //< cursor to trimmed period
+  RGWObjVersionTracker *objv; //< to prevent racing updates
+  Cursor next; //< target cursor for oldest log period
+  Cursor existing; //< existing cursor read from disk
+
+ public:
+  TrimHistoryCR(RGWRados *store, Cursor cursor, RGWObjVersionTracker *objv)
+    : RGWCoroutine(store->ctx()),
+      store(store), cursor(cursor), objv(objv), next(cursor)
+  {
+    next.next(); // advance past cursor
+  }
+
+  int operate() {
+    reenter(this) {
+      // read an existing history, and write the new history if it's newer
+      yield call(new ReadHistoryCR(store, &existing, objv));
+      if (retcode < 0) {
+        return set_cr_error(retcode);
+      }
+      // reject older trims with ECANCELED
+      if (cursor.get_epoch() < existing.get_epoch()) {
+        ldout(cct, 4) << "found oldest log epoch=" << existing.get_epoch()
+            << ", rejecting trim at epoch=" << cursor.get_epoch() << dendl;
+        return set_cr_error(-ECANCELED);
+      }
+      // overwrite with updated history
+      yield call(new WriteHistoryCR(store, next, objv));
+      if (retcode < 0) {
+        return set_cr_error(retcode);
+      }
+      return set_cr_done();
+    }
+    return 0;
+  }
+};
+
+// traverse all the way back to the beginning of the period history, and
+// return a cursor to the first period in a fully attached history
+Cursor find_oldest_period(RGWRados *store)
+{
+  auto cct = store->ctx();
+  auto cursor = store->period_history->get_current();
+
+  while (cursor) {
+    // advance to the period's predecessor
+    if (!cursor.has_prev()) {
+      auto& predecessor = cursor.get_period().get_predecessor();
+      if (predecessor.empty()) {
+        // this is the first period, so our logs must start here
+        ldout(cct, 10) << "find_oldest_period returning first "
+            "period " << cursor.get_period().get_id() << dendl;
+        return cursor;
+      }
+      // pull the predecessor and add it to our history
+      RGWPeriod period;
+      int r = store->period_puller->pull(predecessor, period);
+      if (r < 0) {
+        return cursor;
+      }
+      auto prev = store->period_history->insert(std::move(period));
+      if (!prev) {
+        return prev;
+      }
+      ldout(cct, 20) << "find_oldest_period advancing to "
+          "predecessor period " << predecessor << dendl;
+      ceph_assert(cursor.has_prev());
+    }
+    cursor.prev();
+  }
+  ldout(cct, 10) << "find_oldest_period returning empty cursor" << dendl;
+  return cursor;
+}
+
+} // anonymous namespace
+
+Cursor RGWMetadataManager::init_oldest_log_period()
+{
+  // read the mdlog history
+  RGWMetadataLogHistory state;
+  RGWObjVersionTracker objv;
+  int ret = read_history(store, &state, &objv);
+
+  if (ret == -ENOENT) {
+    // initialize the mdlog history and write it
+    ldout(cct, 10) << "initializing mdlog history" << dendl;
+    auto cursor = find_oldest_period(store);
+    if (!cursor) {
+      return cursor;
+    }
+
+    // write the initial history
+    state.oldest_realm_epoch = cursor.get_epoch();
+    state.oldest_period_id = cursor.get_period().get_id();
+
+    constexpr bool exclusive = true; // don't overwrite
+    int ret = write_history(store, state, &objv, exclusive);
+    if (ret < 0 && ret != -EEXIST) {
+      ldout(cct, 1) << "failed to write mdlog history: "
+          << cpp_strerror(ret) << dendl;
+      return Cursor{ret};
+    }
+    return cursor;
+  } else if (ret < 0) {
+    ldout(cct, 1) << "failed to read mdlog history: "
+        << cpp_strerror(ret) << dendl;
+    return Cursor{ret};
+  }
+
+  // if it's already in the history, return it
+  auto cursor = store->period_history->lookup(state.oldest_realm_epoch);
+  if (cursor) {
+    return cursor;
+  } else {
+    cursor = find_oldest_period(store);
+    state.oldest_realm_epoch = cursor.get_epoch();
+    state.oldest_period_id = cursor.get_period().get_id();
+    ldout(cct, 10) << "rewriting mdlog history" << dendl;
+    ret = write_history(store, state, &objv);
+    if (ret < 0 && ret != -ECANCELED) {
+    ldout(cct, 1) << "failed to write mdlog history: "
+          << cpp_strerror(ret) << dendl;
+    return Cursor{ret};
+    }
+    return cursor;
+  }
+
+  // pull the oldest period by id
+  RGWPeriod period;
+  ret = store->period_puller->pull(state.oldest_period_id, period);
+  if (ret < 0) {
+    ldout(cct, 1) << "failed to read period id=" << state.oldest_period_id
+        << " for mdlog history: " << cpp_strerror(ret) << dendl;
+    return Cursor{ret};
+  }
+  // verify its realm_epoch
+  if (period.get_realm_epoch() != state.oldest_realm_epoch) {
+    ldout(cct, 1) << "inconsistent mdlog history: read period id="
+        << period.get_id() << " with realm_epoch=" << period.get_realm_epoch()
+        << ", expected realm_epoch=" << state.oldest_realm_epoch << dendl;
+    return Cursor{-EINVAL};
+  }
+  // attach the period to our history
+  return store->period_history->attach(std::move(period));
+}
+
+Cursor RGWMetadataManager::read_oldest_log_period() const
+{
+  RGWMetadataLogHistory state;
+  int ret = read_history(store, &state, nullptr);
+  if (ret < 0) {
+    ldout(store->ctx(), 1) << "failed to read mdlog history: "
+        << cpp_strerror(ret) << dendl;
+    return Cursor{ret};
+  }
+
+  ldout(store->ctx(), 10) << "read mdlog history with oldest period id="
+      << state.oldest_period_id << " realm_epoch="
+      << state.oldest_realm_epoch << dendl;
+
+  return store->period_history->lookup(state.oldest_realm_epoch);
+}
+
+RGWCoroutine* RGWMetadataManager::read_oldest_log_period_cr(Cursor *period,
+        RGWObjVersionTracker *objv) const
+{
+  return new ReadHistoryCR(store, period, objv);
+}
+
+RGWCoroutine* RGWMetadataManager::trim_log_period_cr(Cursor period,
+        RGWObjVersionTracker *objv) const
+{
+  return new TrimHistoryCR(store, period, objv);
+}
+
+int RGWMetadataManager::init(const std::string& current_period)
+{
+  // open a log for the current period
+  current_log = get_log(current_period);
+  return 0;
+}
+
+RGWMetadataLog* RGWMetadataManager::get_log(const std::string& period)
+{
+  // construct the period's log in place if it doesn't exist
+  auto insert = md_logs.emplace(std::piecewise_construct,
+                                std::forward_as_tuple(period),
+                                std::forward_as_tuple(cct, store, period));
+  return &insert.first->second;
+}
+
+int RGWMetadataManager::register_handler(RGWMetadataHandler *handler)
+{
+  string type = handler->get_type();
+
+  if (handlers.find(type) != handlers.end())
+    return -EINVAL;
+
+  handlers[type] = handler;
+
+  return 0;
+}
+
+RGWMetadataHandler *RGWMetadataManager::get_handler(const string& type)
+{
+  map<string, RGWMetadataHandler *>::iterator iter = handlers.find(type);
+  if (iter == handlers.end())
+    return NULL;
+
+  return iter->second;
+}
+
+void RGWMetadataManager::parse_metadata_key(const string& metadata_key, string& type, string& entry)
+{
+  auto pos = metadata_key.find(':');
+  if (pos == string::npos) {
+    type = metadata_key;
+  } else {
+    type = metadata_key.substr(0, pos);
+    entry = metadata_key.substr(pos + 1);
+  }
+}
+
+int RGWMetadataManager::find_handler(const string& metadata_key, RGWMetadataHandler **handler, string& entry)
+{
+  string type;
+
+  parse_metadata_key(metadata_key, type, entry);
+
+  if (type.empty()) {
+    *handler = &md_top_handler;
+    return 0;
+  }
+
+  map<string, RGWMetadataHandler *>::iterator iter = handlers.find(type);
+  if (iter == handlers.end())
+    return -ENOENT;
+
+  *handler = iter->second;
+
+  return 0;
+
+}
+
+int RGWMetadataManager::get(string& metadata_key, Formatter *f)
+{
+  RGWMetadataHandler *handler;
+  string entry;
+  int ret = find_handler(metadata_key, &handler, entry);
+  if (ret < 0) {
+    return ret;
+  }
+
+  RGWMetadataObject *obj;
+
+  ret = handler->get(store, entry, &obj);
+  if (ret < 0) {
+    return ret;
+  }
+
+  f->open_object_section("metadata_info");
+  encode_json("key", metadata_key, f);
+  encode_json("ver", obj->get_version(), f);
+  real_time mtime = obj->get_mtime();
+  if (!real_clock::is_zero(mtime)) {
+    utime_t ut(mtime);
+    encode_json("mtime", ut, f);
+  }
+  encode_json("data", *obj, f);
+  f->close_section();
+
+  delete obj;
+
+  return 0;
+}
+
+int RGWMetadataManager::put(string& metadata_key, bufferlist& bl,
+                            RGWMetadataHandler::sync_type_t sync_type,
+                            obj_version *existing_version)
+{
+  RGWMetadataHandler *handler;
+  string entry;
+
+  int ret = find_handler(metadata_key, &handler, entry);
+  if (ret < 0) {
+    return ret;
+  }
+
+  JSONParser parser;
+  if (!parser.parse(bl.c_str(), bl.length())) {
+    return -EINVAL;
+  }
+
+  RGWObjVersionTracker objv_tracker;
+
+  obj_version *objv = &objv_tracker.write_version;
+
+  utime_t mtime;
+
+  try {
+    JSONDecoder::decode_json("key", metadata_key, &parser);
+    JSONDecoder::decode_json("ver", *objv, &parser);
+    JSONDecoder::decode_json("mtime", mtime, &parser);
+  } catch (JSONDecoder::err& e) {
+    return -EINVAL;
+  }
+
+  JSONObj *jo = parser.find_obj("data");
+  if (!jo) {
+    return -EINVAL;
+  }
+
+  ret = handler->put(store, entry, objv_tracker, mtime.to_real_time(), jo, sync_type);
+  if (existing_version) {
+    *existing_version = objv_tracker.read_version;
+  }
+  return ret;
+}
+
+int RGWMetadataManager::prepare_mutate(RGWRados *store,
+                                       rgw_pool& pool, const string& oid,
+                                       const real_time& mtime,
+                                       RGWObjVersionTracker *objv_tracker,
+                                       RGWMetadataHandler::sync_type_t sync_mode)
+{
+  bufferlist bl;
+  real_time orig_mtime;
+  auto obj_ctx = store->svc.sysobj->init_obj_ctx();
+  int ret = rgw_get_system_obj(store, obj_ctx, pool, oid,
+                               bl, objv_tracker, &orig_mtime,
+                               nullptr, nullptr);
+  if (ret < 0 && ret != -ENOENT) {
+    return ret;
+  }
+  if (ret != -ENOENT &&
+      !RGWMetadataHandler::check_versions(objv_tracker->read_version, orig_mtime,
+                                          objv_tracker->write_version, mtime, sync_mode)) {
+    return STATUS_NO_APPLY;
+  }
+
+  if (objv_tracker->write_version.tag.empty()) {
+    if (objv_tracker->read_version.tag.empty()) {
+      objv_tracker->generate_new_write_ver(store->ctx());
+    } else {
+      objv_tracker->write_version = objv_tracker->read_version;
+      objv_tracker->write_version.ver++;
+    }
+  }
+  return 0;
+}
+
+int RGWMetadataManager::remove(string& metadata_key)
+{
+  RGWMetadataHandler *handler;
+  string entry;
+
+  int ret = find_handler(metadata_key, &handler, entry);
+  if (ret < 0) {
+    return ret;
+  }
+
+  RGWMetadataObject *obj;
+  ret = handler->get(store, entry, &obj);
+  if (ret < 0) {
+    return ret;
+  }
+  RGWObjVersionTracker objv_tracker;
+  objv_tracker.read_version = obj->get_version();
+  delete obj;
+
+  return handler->remove(store, entry, objv_tracker);
+}
+
+int RGWMetadataManager::lock_exclusive(string& metadata_key, timespan duration, string& owner_id) {
+  RGWMetadataHandler *handler;
+  string entry;
+  string zone_id;
+
+  int ret = find_handler(metadata_key, &handler, entry);
+  if (ret < 0) 
+    return ret;
+
+  rgw_pool pool;
+  string oid;
+
+  handler->get_pool_and_oid(store, entry, pool, oid);
+
+  return store->lock_exclusive(pool, oid, duration, zone_id, owner_id);  
+}
+
+int RGWMetadataManager::unlock(string& metadata_key, string& owner_id) {
+  librados::IoCtx io_ctx;
+  RGWMetadataHandler *handler;
+  string entry;
+  string zone_id;
+
+  int ret = find_handler(metadata_key, &handler, entry);
+  if (ret < 0) 
+    return ret;
+
+  rgw_pool pool;
+  string oid;
+
+  handler->get_pool_and_oid(store, entry, pool, oid);
+
+  return store->unlock(pool, oid, zone_id, owner_id);  
+}
+
+struct list_keys_handle {
+  void *handle;
+  RGWMetadataHandler *handler;
+};
+
+int RGWMetadataManager::list_keys_init(const string& section, void **handle)
+{
+  return list_keys_init(section, string(), handle);
+}
+
+int RGWMetadataManager::list_keys_init(const string& section,
+                                       const string& marker, void **handle)
+{
+  string entry;
+  RGWMetadataHandler *handler;
+
+  int ret;
+
+  ret = find_handler(section, &handler, entry);
+  if (ret < 0) {
+    return -ENOENT;
+  }
+
+  list_keys_handle *h = new list_keys_handle;
+  h->handler = handler;
+  ret = handler->list_keys_init(store, marker, &h->handle);
+  if (ret < 0) {
+    delete h;
+    return ret;
+  }
+
+  *handle = (void *)h;
+
+  return 0;
+}
+
+int RGWMetadataManager::list_keys_next(void *handle, int max, list<string>& keys, bool *truncated)
+{
+  list_keys_handle *h = static_cast<list_keys_handle *>(handle);
+
+  RGWMetadataHandler *handler = h->handler;
+
+  return handler->list_keys_next(h->handle, max, keys, truncated);
+}
+
+void RGWMetadataManager::list_keys_complete(void *handle)
+{
+  list_keys_handle *h = static_cast<list_keys_handle *>(handle);
+
+  RGWMetadataHandler *handler = h->handler;
+
+  handler->list_keys_complete(h->handle);
+  delete h;
+}
+
+string RGWMetadataManager::get_marker(void *handle)
+{
+  list_keys_handle *h = static_cast<list_keys_handle *>(handle);
+
+  return h->handler->get_marker(h->handle);
+}
+
+void RGWMetadataManager::dump_log_entry(cls_log_entry& entry, Formatter *f)
+{
+  f->open_object_section("entry");
+  f->dump_string("id", entry.id);
+  f->dump_string("section", entry.section);
+  f->dump_string("name", entry.name);
+  entry.timestamp.gmtime_nsec(f->dump_stream("timestamp"));
+
+  try {
+    RGWMetadataLogData log_data;
+    auto iter = entry.data.cbegin();
+    decode(log_data, iter);
+
+    encode_json("data", log_data, f);
+  } catch (buffer::error& err) {
+    lderr(cct) << "failed to decode log entry: " << entry.section << ":" << entry.name<< " ts=" << entry.timestamp << dendl;
+  }
+  f->close_section();
+}
+
+void RGWMetadataManager::get_sections(list<string>& sections)
+{
+  for (map<string, RGWMetadataHandler *>::iterator iter = handlers.begin(); iter != handlers.end(); ++iter) {
+    sections.push_back(iter->first);
+  }
+}
+
+int RGWMetadataManager::pre_modify(RGWMetadataHandler *handler, string& section, const string& key,
+                                   RGWMetadataLogData& log_data, RGWObjVersionTracker *objv_tracker,
+                                   RGWMDLogStatus op_type)
+{
+  section = handler->get_type();
+
+  /* if write version has not been set, and there's a read version, set it so that we can
+   * log it
+   */
+  if (objv_tracker) {
+    if (objv_tracker->read_version.ver && !objv_tracker->write_version.ver) {
+      objv_tracker->write_version = objv_tracker->read_version;
+      objv_tracker->write_version.ver++;
+    }
+    log_data.read_version = objv_tracker->read_version;
+    log_data.write_version = objv_tracker->write_version;
+  }
+
+  log_data.status = op_type;
+
+  bufferlist logbl;
+  encode(log_data, logbl);
+
+  ceph_assert(current_log); // must have called init()
+  int ret = current_log->add_entry(handler, section, key, logbl);
+  if (ret < 0)
+    return ret;
+
+  return 0;
+}
+
+int RGWMetadataManager::post_modify(RGWMetadataHandler *handler, const string& section, const string& key, RGWMetadataLogData& log_data,
+                                    RGWObjVersionTracker *objv_tracker, int ret)
+{
+  if (ret >= 0)
+    log_data.status = MDLOG_STATUS_COMPLETE;
+  else 
+    log_data.status = MDLOG_STATUS_ABORT;
+
+  bufferlist logbl;
+  encode(log_data, logbl);
+
+  ceph_assert(current_log); // must have called init()
+  int r = current_log->add_entry(handler, section, key, logbl);
+  if (ret < 0)
+    return ret;
+
+  if (r < 0)
+    return r;
+
+  return 0;
+}
+
+string RGWMetadataManager::heap_oid(RGWMetadataHandler *handler, const string& key, const obj_version& objv)
+{
+  char buf[objv.tag.size() + 32];
+  snprintf(buf, sizeof(buf), "%s:%lld", objv.tag.c_str(), (long long)objv.ver);
+  return string(".meta:") + handler->get_type() + ":" + key + ":" + buf;
+}
+
+int RGWMetadataManager::store_in_heap(RGWMetadataHandler *handler, const string& key, bufferlist& bl,
+                                      RGWObjVersionTracker *objv_tracker, real_time mtime,
+				      map<string, bufferlist> *pattrs)
+{
+  if (!objv_tracker) {
+    return -EINVAL;
+  }
+
+  rgw_pool heap_pool(store->svc.zone->get_zone_params().metadata_heap);
+
+  if (heap_pool.empty()) {
+    return 0;
+  }
+
+  RGWObjVersionTracker otracker;
+  otracker.write_version = objv_tracker->write_version;
+  string oid = heap_oid(handler, key, objv_tracker->write_version);
+  int ret = rgw_put_system_obj(store, heap_pool, oid,
+                               bl, false, &otracker, mtime, pattrs);
+  if (ret < 0) {
+    ldout(store->ctx(), 0) << "ERROR: rgw_put_system_obj() oid=" << oid << " returned ret=" << ret << dendl;
+    return ret;
+  }
+
+  return 0;
+}
+
+int RGWMetadataManager::remove_from_heap(RGWMetadataHandler *handler, const string& key, RGWObjVersionTracker *objv_tracker)
+{
+  if (!objv_tracker) {
+    return -EINVAL;
+  }
+
+  rgw_pool heap_pool(store->svc.zone->get_zone_params().metadata_heap);
+
+  if (heap_pool.empty()) {
+    return 0;
+  }
+
+  string oid = heap_oid(handler, key, objv_tracker->write_version);
+  rgw_raw_obj obj(heap_pool, oid);
+  auto obj_ctx = store->svc.sysobj->init_obj_ctx();
+  auto sysobj = obj_ctx.get_obj(obj);
+  int ret = sysobj.wop().remove();
+  if (ret < 0) {
+    ldout(store->ctx(), 0) << "ERROR: sysobj.wop().remove() oid=" << oid << " returned ret=" << ret << dendl;
+    return ret;
+  }
+
+  return 0;
+}
+
+int RGWMetadataManager::put_entry(RGWMetadataHandler *handler, const string& key, bufferlist& bl, bool exclusive,
+                                  RGWObjVersionTracker *objv_tracker, real_time mtime, map<string, bufferlist> *pattrs)
+{
+  string section;
+  RGWMetadataLogData log_data;
+  int ret = pre_modify(handler, section, key, log_data, objv_tracker, MDLOG_STATUS_WRITE);
+  if (ret < 0)
+    return ret;
+
+  string oid;
+  rgw_pool pool;
+
+  handler->get_pool_and_oid(store, key, pool, oid);
+
+  ret = store_in_heap(handler, key, bl, objv_tracker, mtime, pattrs);
+  if (ret < 0) {
+    ldout(store->ctx(), 0) << "ERROR: " << __func__ << ": store_in_heap() key=" << key << " returned ret=" << ret << dendl;
+    goto done;
+  }
+
+  ret = rgw_put_system_obj(store, pool, oid, bl, exclusive,
+                           objv_tracker, mtime, pattrs);
+
+  if (ret < 0) {
+    int r = remove_from_heap(handler, key, objv_tracker);
+    if (r < 0) {
+      ldout(store->ctx(), 0) << "ERROR: " << __func__ << ": remove_from_heap() key=" << key << " returned ret=" << r << dendl;
+    }
+  }
+done:
+  /* cascading ret into post_modify() */
+
+  ret = post_modify(handler, section, key, log_data, objv_tracker, ret);
+  if (ret < 0)
+    return ret;
+
+  return 0;
+}
+
+int RGWMetadataManager::remove_entry(RGWMetadataHandler *handler,
+				     const string& key,
+				     RGWObjVersionTracker *objv_tracker)
+{
+  string section;
+  RGWMetadataLogData log_data;
+  int ret = pre_modify(handler, section, key, log_data, objv_tracker, MDLOG_STATUS_REMOVE);
+  if (ret < 0) {
+      return ret;
+  }
+
+  string oid;
+  rgw_pool pool;
+
+  handler->get_pool_and_oid(store, key, pool, oid);
+
+  rgw_raw_obj obj(pool, oid);
+
+  auto obj_ctx = store->svc.sysobj->init_obj_ctx();
+  auto sysobj = obj_ctx.get_obj(obj);
+  ret = sysobj.wop()
+              .set_objv_tracker(objv_tracker)
+              .remove();
+  /* cascading ret into post_modify() */
+
+  ret = post_modify(handler, section, key, log_data, objv_tracker, ret);
+  if (ret < 0) {
+      return ret;
+  }
+
+  return 0;
+}
+
+int RGWMetadataManager::get_log_shard_id(const string& section,
+                                         const string& key, int *shard_id)
+{
+  RGWMetadataHandler *handler = get_handler(section);
+  if (!handler) {
+    return -EINVAL;
+  }
+  string hash_key;
+  handler->get_hash_key(section, key, hash_key);
+  *shard_id = store->key_to_shard_id(hash_key, cct->_conf->rgw_md_log_max_shards);
+  return 0;
+}