Merge PR #17657 into master

* refs/remotes/upstream/pull/17657/head:
	mds: optimize MDCache::rejoin_scour_survivor_replicas()
	mds: fix MDSCacheObject::clear_replica_map
	mds: support limiting cache by memory
	common: refactor of lru
	mds: resolve unsigned coercion compiler warning
	common: use safer uint64_t for list size
	common: add bytes2str pretty print function
	mds: check if waiting is allocated before use
	mds: go back to compact_map for replicas
	mds: use mempool for cache objects
	mds: cleanup replica_map access
	common: add alloc_ptr smart pointer
	common: add warning on base class use of mempool
	common: use atomic uin64_t for counter

Reviewed-by: Zheng Yan <zyan@redhat.com>

diff --cc src/client/Client.cc
Simple merge

diff --cc src/common/legacy_config_opts.h
Simple merge

diff --cc src/common/options.cc
Simple merge

diff --cc src/mds/MDCache.cc
Simple merge

diff --cc src/mds/MDSRank.cc
index b4e196b5ddeb59f800978a58de1de86c5ca7f4d0,5b0d76d82cf50765eb5c3ee562820fd7d4ebe9ea..77f1819788fc5977338a2821ac6c34f04d3317d0
--- 1/src/mds/MDSRank.cc
--- 2/src/mds/MDSRank.cc
+++ b/src/mds/MDSRank.cc
@@@ -1937,8 -1937,13 +1937,14 @@@ bool MDSRankDispatcher::handle_asok_com
  
      if (r != 0) {
        ss << "Failed to dump cache: " << cpp_strerror(r);
 +      f->reset();
      }
+   } else if (command == "cache status") {
+     Mutex::Locker l(mds_lock);
+     int r = mdcache->cache_status(f);
+     if (r != 0) {
+       ss << "Failed to get cache status: " << cpp_strerror(r);
+     }
    } else if (command == "dump tree") {
      string root;
      int64_t depth;

diff --cc src/mds/Migrator.cc
Simple merge