diff --git a/src/crimson/os/alienstore/alien_store.cc b/src/crimson/os/alienstore/alien_store.cc
index aa9758147df..091e438466c 100644
--- a/src/crimson/os/alienstore/alien_store.cc
+++ b/src/crimson/os/alienstore/alien_store.cc
@@ -338,13 +338,7 @@ AlienStore::get_attrs(CollectionRef ch,
   return seastar::do_with(attrs_t{}, [=] (auto &aset) {
     return tp->submit(ch->get_cid().hash_to_shard(tp->size()), [=, &aset] {
       auto c = static_cast<AlienCollection*>(ch.get());
-      std::map<std::string, ceph::bufferptr> blueaset;
-      const auto r = store->getattrs(c->collection, oid, blueaset);
-      for (auto& [bluekey, blueval] : blueaset) {
-        ceph::bufferlist bl;
-        bl.push_back(std::move(blueval));
-        aset.emplace(std::move(bluekey), std::move(bl));
-      }
+      const auto r = store->getattrs(c->collection, oid, aset);
       return r;
     }).then([&aset] (int r) -> get_attrs_ertr::future<attrs_t> {
       if (r == -ENOENT) {
diff --git a/src/crimson/osd/replicated_recovery_backend.cc b/src/crimson/osd/replicated_recovery_backend.cc
index 79e39c6fed3..927551d0768 100644
--- a/src/crimson/osd/replicated_recovery_backend.cc
+++ b/src/crimson/osd/replicated_recovery_backend.cc
@@ -927,7 +927,7 @@ ReplicatedRecoveryBackend::prep_push_target(
   bool complete,
   bool clear_omap,
   ObjectStore::Transaction* t,
-  const map<string, bufferlist>& attrs,
+  const map<string, bufferlist, less<>>& attrs,
   bufferlist&& omap_header)
 {
   if (!first) {
@@ -1003,7 +1003,7 @@ ReplicatedRecoveryBackend::submit_push_data(
   interval_set<uint64_t>&& intervals_included,
   bufferlist&& data_included,
   bufferlist&& omap_header,
-  const map<string, bufferlist> &attrs,
+  const map<string, bufferlist, less<>> &attrs,
   map<string, bufferlist>&& omap_entries,
   ObjectStore::Transaction *t)
 {
diff --git a/src/crimson/osd/replicated_recovery_backend.h b/src/crimson/osd/replicated_recovery_backend.h
index 55cd0f17861..1d9b6042b9b 100644
--- a/src/crimson/osd/replicated_recovery_backend.h
+++ b/src/crimson/osd/replicated_recovery_backend.h
@@ -82,7 +82,7 @@ protected:
     interval_set<uint64_t>&& intervals_included,
     ceph::bufferlist&& data_included,
     ceph::bufferlist&& omap_header,
-    const std::map<string, bufferlist> &attrs,
+    const std::map<std::string, bufferlist, std::less<>> &attrs,
     std::map<string, bufferlist>&& omap_entries,
     ceph::os::Transaction *t);
   void submit_push_complete(
@@ -161,7 +161,7 @@ private:
     bool complete,
     bool clear_omap,
     ObjectStore::Transaction* t,
-    const map<string, bufferlist> &attrs,
+    const std::map<std::string, bufferlist, std::less<>> &attrs,
     bufferlist&& omap_header);
   using interruptor = crimson::interruptible::interruptor<
     crimson::osd::IOInterruptCondition>;
diff --git a/src/os/FuseStore.cc b/src/os/FuseStore.cc
index e06131ce33c..dd9833e0861 100644
--- a/src/os/FuseStore.cc
+++ b/src/os/FuseStore.cc
@@ -554,7 +554,7 @@ static int os_readdir(const char *path,
 
   case FN_OBJECT_ATTR:
     {
-      map<string,bufferptr> aset;
+      map<string,bufferptr,less<>> aset;
       fs->store->getattrs(ch, oid, aset);
       unsigned skip = offset;
       for (auto a : aset) {
diff --git a/src/os/ObjectStore.h b/src/os/ObjectStore.h
index fb58b0ad520..3b8d3370615 100644
--- a/src/os/ObjectStore.h
+++ b/src/os/ObjectStore.h
@@ -601,7 +601,7 @@ public:
    * @returns 0 on success, negative error code on failure.
    */
   virtual int getattrs(CollectionHandle &c, const ghobject_t& oid,
-		       std::map<std::string,ceph::buffer::ptr>& aset) = 0;
+		       std::map<std::string,ceph::buffer::ptr, std::less<>>& aset) = 0;
 
   /**
    * getattrs -- get all of the xattrs of an object
@@ -612,8 +612,8 @@ public:
    * @returns 0 on success, negative error code on failure.
    */
   int getattrs(CollectionHandle &c, const ghobject_t& oid,
-	       std::map<std::string,ceph::buffer::list>& aset) {
-    std::map<std::string,ceph::buffer::ptr> bmap;
+	       std::map<std::string,ceph::buffer::list,std::less<>>& aset) {
+    std::map<std::string,ceph::buffer::ptr,std::less<>> bmap;
     int r = getattrs(c, oid, bmap);
     for (auto i = bmap.begin(); i != bmap.end(); ++i) {
       aset[i->first].append(i->second);
diff --git a/src/os/Transaction.cc b/src/os/Transaction.cc
index af82da3406d..ac3513ef4a4 100644
--- a/src/os/Transaction.cc
+++ b/src/os/Transaction.cc
@@ -554,7 +554,7 @@ void Transaction::generate_test_instances(list<Transaction*>& o)
 
   t = new Transaction;
   t->setattr(c, o1, "key", bl);
-  map<string,bufferptr> m;
+  map<string,bufferptr,less<>> m;
   m["a"] = buffer::copy("this", 4);
   m["b"] = buffer::copy("that", 4);
   t->setattrs(c, o1, m);
diff --git a/src/os/Transaction.h b/src/os/Transaction.h
index 93b6272254c..f016aa6c315 100644
--- a/src/os/Transaction.h
+++ b/src/os/Transaction.h
@@ -912,7 +912,9 @@ public:
     data.ops = data.ops + 1;
   }
   /// Set multiple xattrs of an object
-  void setattrs(const coll_t& cid, const ghobject_t& oid, const std::map<std::string,ceph::buffer::ptr>& attrset) {
+  void setattrs(const coll_t& cid,
+		const ghobject_t& oid,
+		const std::map<std::string,ceph::buffer::ptr,std::less<>>& attrset) {
     using ceph::encode;
     Op* _op = _get_next_op();
     _op->op = OP_SETATTRS;
@@ -922,7 +924,9 @@ public:
     data.ops = data.ops + 1;
   }
   /// Set multiple xattrs of an object
-  void setattrs(const coll_t& cid, const ghobject_t& oid, const std::map<std::string,ceph::buffer::list>& attrset) {
+  void setattrs(const coll_t& cid,
+		const ghobject_t& oid,
+		const std::map<std::string,ceph::buffer::list,std::less<>>& attrset) {
     using ceph::encode;
     Op* _op = _get_next_op();
     _op->op = OP_SETATTRS;
diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index 7520b5de0ea..ce189310377 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -10431,7 +10431,7 @@ int BlueStore::getattr(
 int BlueStore::getattrs(
   CollectionHandle &c_,
   const ghobject_t& oid,
-  map<string,bufferptr>& aset)
+  map<string,bufferptr,less<>>& aset)
 {
   Collection *c = static_cast<Collection *>(c_.get());
   dout(15) << __func__ << " " << c->cid << " " << oid << dendl;
diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index a1249607a4d..c08cc6d61aa 100644
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -2836,7 +2836,7 @@ public:
 	      ceph::buffer::ptr& value) override;
 
   int getattrs(CollectionHandle &c, const ghobject_t& oid,
-	       std::map<std::string,ceph::buffer::ptr>& aset) override;
+	       std::map<std::string,ceph::buffer::ptr, std::less<>>& aset) override;
 
   int list_collections(std::vector<coll_t>& ls) override;
 
diff --git a/src/os/filestore/FileStore.cc b/src/os/filestore/FileStore.cc
index 0c143d57213..323bb6521ce 100644
--- a/src/os/filestore/FileStore.cc
+++ b/src/os/filestore/FileStore.cc
@@ -3861,7 +3861,7 @@ int FileStore::_clone(const coll_t& cid, const ghobject_t& oldoid, const ghobjec
 
   {
     char buf[2];
-    map<string, bufferptr> aset;
+    map<string, bufferptr, less<>> aset;
     r = _fgetattrs(**o, aset);
     if (r < 0)
       goto out3;
@@ -4469,7 +4469,7 @@ int FileStore::_fgetattr(int fd, const char *name, bufferptr& bp)
   return l;
 }
 
-int FileStore::_fgetattrs(int fd, map<string,bufferptr>& aset)
+int FileStore::_fgetattrs(int fd, map<string,bufferptr,less<>>& aset)
 {
   // get attr list
   char names1[100];
@@ -4520,7 +4520,7 @@ int FileStore::_fgetattrs(int fd, map<string,bufferptr>& aset)
   return 0;
 }
 
-int FileStore::_fsetattrs(int fd, map<string, bufferptr> &aset)
+int FileStore::_fsetattrs(int fd, map<string, bufferptr, less<>> &aset)
 {
   for (map<string, bufferptr>::iterator p = aset.begin();
        p != aset.end();
@@ -4635,7 +4635,9 @@ int FileStore::getattr(CollectionHandle& ch, const ghobject_t& oid, const char *
   }
 }
 
-int FileStore::getattrs(CollectionHandle& ch, const ghobject_t& oid, map<string,bufferptr>& aset)
+int FileStore::getattrs(CollectionHandle& ch,
+			const ghobject_t& oid,
+			std::map<std::string,bufferptr,std::less<>>& aset)
 {
   tracepoint(objectstore, getattrs_enter, ch->cid.c_str());
   const coll_t& cid = !_need_temp_object_collection(ch->cid, oid) ? ch->cid : ch->cid.get_temp();
@@ -4718,8 +4720,8 @@ int FileStore::_setattrs(const coll_t& cid, const ghobject_t& oid, map<string,bu
 {
   map<string, bufferlist> omap_set;
   set<string> omap_remove;
-  map<string, bufferptr> inline_set;
-  map<string, bufferptr> inline_to_set;
+  map<string, bufferptr, less<>> inline_set;
+  map<string, bufferptr, less<>> inline_to_set;
   FDRef fd;
   int spill_out = -1;
   bool incomplete_inline = false;
@@ -4862,7 +4864,7 @@ int FileStore::_rmattrs(const coll_t& cid, const ghobject_t& oid,
 {
   dout(15) << __FUNC__ << ": " << cid << "/" << oid << dendl;
 
-  map<string,bufferptr> aset;
+  map<string,bufferptr,less<>> aset;
   FDRef fd;
   set<string> omap_attrs;
   Index index;
diff --git a/src/os/filestore/FileStore.h b/src/os/filestore/FileStore.h
index 324dbbe4daf..e975abc3d48 100644
--- a/src/os/filestore/FileStore.h
+++ b/src/os/filestore/FileStore.h
@@ -646,8 +646,8 @@ public:
   int _remove(const coll_t& cid, const ghobject_t& oid, const SequencerPosition &spos);
 
   int _fgetattr(int fd, const char *name, ceph::bufferptr& bp);
-  int _fgetattrs(int fd, std::map<std::string, ceph::bufferptr>& aset);
-  int _fsetattrs(int fd, std::map<std::string, ceph::bufferptr> &aset);
+  int _fgetattrs(int fd, std::map<std::string, ceph::bufferptr,std::less<>>& aset);
+  int _fsetattrs(int fd, std::map<std::string, ceph::bufferptr,std::less<>>& aset);
 
   void do_force_sync();
   void start_sync(Context *onsafe);
@@ -692,7 +692,7 @@ public:
   using ObjectStore::getattr;
   using ObjectStore::getattrs;
   int getattr(CollectionHandle& c, const ghobject_t& oid, const char *name, ceph::bufferptr &bp) override;
-  int getattrs(CollectionHandle& c, const ghobject_t& oid, std::map<std::string,ceph::bufferptr>& aset) override;
+  int getattrs(CollectionHandle& c, const ghobject_t& oid, std::map<std::string,ceph::bufferptr,std::less<>>& aset) override;
 
   int _setattrs(const coll_t& cid, const ghobject_t& oid, std::map<std::string,ceph::bufferptr>& aset,
 		const SequencerPosition &spos);
diff --git a/src/os/kstore/KStore.cc b/src/os/kstore/KStore.cc
index 8f6b19bda38..fe030859e22 100644
--- a/src/os/kstore/KStore.cc
+++ b/src/os/kstore/KStore.cc
@@ -1362,7 +1362,7 @@ int KStore::getattr(
 int KStore::getattrs(
   CollectionHandle& ch,
   const ghobject_t& oid,
-  map<string,bufferptr>& aset)
+  map<string,bufferptr,less<>>& aset)
 {
   dout(15) << __func__ << " " << ch->cid << " " << oid << dendl;
   Collection *c = static_cast<Collection*>(ch.get());
diff --git a/src/os/kstore/KStore.h b/src/os/kstore/KStore.h
index 16c4266ee8e..d7d95acdfbd 100644
--- a/src/os/kstore/KStore.h
+++ b/src/os/kstore/KStore.h
@@ -486,7 +486,9 @@ public:
   using ObjectStore::getattr;
   int getattr(CollectionHandle& c, const ghobject_t& oid, const char *name, ceph::buffer::ptr& value) override;
   using ObjectStore::getattrs;
-  int getattrs(CollectionHandle& c, const ghobject_t& oid, std::map<std::string,ceph::buffer::ptr>& aset) override;
+  int getattrs(CollectionHandle& c,
+	       const ghobject_t& oid,
+	       std::map<std::string,ceph::buffer::ptr,std::less<>>& aset) override;
 
   int list_collections(std::vector<coll_t>& ls) override;
   bool collection_exists(const coll_t& c) override;
diff --git a/src/os/kstore/kstore_types.h b/src/os/kstore/kstore_types.h
index 859ea8f7dc8..f264642e274 100644
--- a/src/os/kstore/kstore_types.h
+++ b/src/os/kstore/kstore_types.h
@@ -41,7 +41,7 @@ WRITE_CLASS_ENCODER(kstore_cnode_t)
 struct kstore_onode_t {
   uint64_t nid;                        ///< numeric id (locally unique)
   uint64_t size;                       ///< object size
-  std::map<std::string, ceph::buffer::ptr> attrs;        ///< attrs
+  std::map<std::string, ceph::buffer::ptr, std::less<>> attrs;        ///< attrs
   uint64_t omap_head;                  ///< id for omap root node
   uint32_t stripe_size;                ///< stripe size
 
diff --git a/src/os/memstore/MemStore.cc b/src/os/memstore/MemStore.cc
index dc29ab1b6fd..6c6140df809 100644
--- a/src/os/memstore/MemStore.cc
+++ b/src/os/memstore/MemStore.cc
@@ -384,7 +384,7 @@ int MemStore::getattr(CollectionHandle &c_, const ghobject_t& oid,
 }
 
 int MemStore::getattrs(CollectionHandle &c_, const ghobject_t& oid,
-		       std::map<std::string,ceph::buffer::ptr>& aset)
+		       std::map<std::string,ceph::buffer::ptr,std::less<>>& aset)
 {
   Collection *c = static_cast<Collection*>(c_.get());
   dout(10) << __func__ << " " << c->cid << " " << oid << dendl;
diff --git a/src/os/memstore/MemStore.h b/src/os/memstore/MemStore.h
index 7f0f58e423c..2a123fae151 100644
--- a/src/os/memstore/MemStore.h
+++ b/src/os/memstore/MemStore.h
@@ -32,7 +32,7 @@ public:
   struct Object : public RefCountedObject {
     ceph::mutex xattr_mutex{ceph::make_mutex("MemStore::Object::xattr_mutex")};
     ceph::mutex omap_mutex{ceph::make_mutex("MemStore::Object::omap_mutex")};
-    std::map<std::string,ceph::buffer::ptr> xattr;
+    std::map<std::string,ceph::buffer::ptr,std::less<>> xattr;
     ceph::buffer::list omap_header;
     std::map<std::string,ceph::buffer::list> omap;
 
@@ -310,7 +310,7 @@ public:
   int getattr(CollectionHandle &c, const ghobject_t& oid, const char *name,
 	      ceph::buffer::ptr& value) override;
   int getattrs(CollectionHandle &c, const ghobject_t& oid,
-	       std::map<std::string,ceph::buffer::ptr>& aset) override;
+	       std::map<std::string,ceph::buffer::ptr,std::less<>>& aset) override;
 
   int list_collections(std::vector<coll_t>& ls) override;
 
diff --git a/src/osd/ECBackend.cc b/src/osd/ECBackend.cc
index 7938f5c0eb7..f9398c17220 100644
--- a/src/osd/ECBackend.cc
+++ b/src/osd/ECBackend.cc
@@ -433,7 +433,7 @@ void ECBackend::handle_recovery_push_reply(
 void ECBackend::handle_recovery_read_complete(
   const hobject_t &hoid,
   boost::tuple<uint64_t, uint64_t, map<pg_shard_t, bufferlist> > &to_read,
-  std::optional<map<string, bufferlist> > attrs,
+  std::optional<map<string, bufferlist, less<>> > attrs,
   RecoveryMessages *m)
 {
   dout(10) << __func__ << ": returned " << hoid << " "
@@ -478,7 +478,7 @@ void ECBackend::handle_recovery_read_complete(
       }
       // Need to remove ECUtil::get_hinfo_key() since it should not leak out
       // of the backend (see bug #12983)
-      map<string, bufferlist> sanitized_attrs(op.xattrs);
+      map<string, bufferlist, less<>> sanitized_attrs(op.xattrs);
       sanitized_attrs.erase(ECUtil::get_hinfo_key());
       op.obc = get_parent()->get_obc(hoid, sanitized_attrs);
       ceph_assert(op.obc);
@@ -1231,7 +1231,7 @@ void ECBackend::handle_sub_read_reply(
       dout(20) << __func__ << " to_read skipping" << dendl;
       continue;
     }
-    rop.complete[i->first].attrs = map<string, bufferlist>();
+    rop.complete[i->first].attrs.emplace();
     (*(rop.complete[i->first].attrs)).swap(i->second);
   }
   for (auto i = op.errors.begin();
@@ -1817,7 +1817,7 @@ void ECBackend::do_read_op(ReadOp &op)
 }
 
 ECUtil::HashInfoRef ECBackend::get_hash_info(
-  const hobject_t &hoid, bool checks, const map<string,bufferptr> *attrs)
+  const hobject_t &hoid, bool checks, const map<string,bufferptr,less<>> *attrs)
 {
   dout(10) << __func__ << ": Getting attr on " << hoid << dendl;
   ECUtil::HashInfoRef ref = unstable_hashinfo_registry.lookup(hoid);
@@ -2481,7 +2481,7 @@ int ECBackend::send_all_remaining_reads(
 
 int ECBackend::objects_get_attrs(
   const hobject_t &hoid,
-  map<string, bufferlist> *out)
+  map<string, bufferlist, less<>> *out)
 {
   int r = store->getattrs(
     ch,
diff --git a/src/osd/ECBackend.h b/src/osd/ECBackend.h
index c39de1bfeeb..e5e4acee870 100644
--- a/src/osd/ECBackend.h
+++ b/src/osd/ECBackend.h
@@ -275,7 +275,7 @@ private:
 
     // must be filled if state == WRITING
     std::map<int, ceph::buffer::list> returned_data;
-    std::map<std::string, ceph::buffer::list> xattrs;
+    std::map<std::string, ceph::buffer::list, std::less<>> xattrs;
     ECUtil::HashInfoRef hinfo;
     ObjectContextRef obc;
     std::set<pg_shard_t> waiting_on_pushes;
@@ -298,7 +298,7 @@ private:
   void handle_recovery_read_complete(
     const hobject_t &hoid,
     boost::tuple<uint64_t, uint64_t, std::map<pg_shard_t, ceph::buffer::list> > &to_read,
-    std::optional<std::map<std::string, ceph::buffer::list> > attrs,
+    std::optional<std::map<std::string, ceph::buffer::list, std::less<>> > attrs,
     RecoveryMessages *m);
   void handle_recovery_push(
     const PushOp &op,
@@ -340,7 +340,7 @@ public:
   struct read_result_t {
     int r;
     std::map<pg_shard_t, int> errors;
-    std::optional<std::map<std::string, ceph::buffer::list> > attrs;
+    std::optional<std::map<std::string, ceph::buffer::list, std::less<>> > attrs;
     std::list<
       boost::tuple<
 	uint64_t, uint64_t, std::map<pg_shard_t, ceph::buffer::list> > > returned;
@@ -630,7 +630,7 @@ public:
   /// If modified, ensure that the ref is held until the update is applied
   SharedPtrRegistry<hobject_t, ECUtil::HashInfo> unstable_hashinfo_registry;
   ECUtil::HashInfoRef get_hash_info(const hobject_t &hoid, bool checks = true,
-				    const std::map<std::string, ceph::buffer::ptr> *attr = NULL);
+				    const std::map<std::string, ceph::buffer::ptr, std::less<>> *attr = NULL);
 
 public:
   ECBackend(
@@ -661,7 +661,7 @@ public:
 
   int objects_get_attrs(
     const hobject_t &hoid,
-    std::map<std::string, ceph::buffer::list> *out) override;
+    std::map<std::string, ceph::buffer::list, std::less<>> *out) override;
 
   void rollback_append(
     const hobject_t &hoid,
diff --git a/src/osd/ECMsgTypes.h b/src/osd/ECMsgTypes.h
index 77b4222b28b..bf10704125c 100644
--- a/src/osd/ECMsgTypes.h
+++ b/src/osd/ECMsgTypes.h
@@ -119,7 +119,7 @@ struct ECSubReadReply {
   pg_shard_t from;
   ceph_tid_t tid;
   std::map<hobject_t, std::list<std::pair<uint64_t, ceph::buffer::list> >> buffers_read;
-  std::map<hobject_t, std::map<std::string, ceph::buffer::list>> attrs_read;
+  std::map<hobject_t, std::map<std::string, ceph::buffer::list, std::less<>>> attrs_read;
   std::map<hobject_t, int> errors;
   void encode(ceph::buffer::list &bl) const;
   void decode(ceph::buffer::list::const_iterator &bl);
diff --git a/src/osd/ECTransaction.cc b/src/osd/ECTransaction.cc
index 603f9af0ea3..2a6c67d13eb 100644
--- a/src/osd/ECTransaction.cc
+++ b/src/osd/ECTransaction.cc
@@ -330,7 +330,7 @@ void ECTransaction::generate_transactions(
       ceph_assert(op.omap_updates.empty());
 
       if (!op.attr_updates.empty()) {
-	map<string, bufferlist> to_set;
+	map<string, bufferlist, less<>> to_set;
 	for (auto &&j: op.attr_updates) {
 	  if (j.second) {
 	    to_set[j.first] = *(j.second);
diff --git a/src/osd/PGBackend.cc b/src/osd/PGBackend.cc
index b6357b12639..3b1525bd271 100644
--- a/src/osd/PGBackend.cc
+++ b/src/osd/PGBackend.cc
@@ -467,7 +467,7 @@ int PGBackend::objects_get_attr(
 
 int PGBackend::objects_get_attrs(
   const hobject_t &hoid,
-  map<string, bufferlist> *out)
+  map<string, bufferlist, less<>> *out)
 {
   return store->getattrs(
     ch,
@@ -479,7 +479,7 @@ void PGBackend::rollback_setattrs(
   const hobject_t &hoid,
   map<string, std::optional<bufferlist> > &old_attrs,
   ObjectStore::Transaction *t) {
-  map<string, bufferlist> to_set;
+  map<string, bufferlist, less<>> to_set;
   ceph_assert(!hoid.is_temp());
   for (map<string, std::optional<bufferlist> >::iterator i = old_attrs.begin();
        i != old_attrs.end();
diff --git a/src/osd/PGBackend.h b/src/osd/PGBackend.h
index 12bdfc0d113..34d74025173 100644
--- a/src/osd/PGBackend.h
+++ b/src/osd/PGBackend.h
@@ -212,7 +212,7 @@ typedef std::shared_ptr<const OSDMap> OSDMapRef;
 
      virtual ObjectContextRef get_obc(
        const hobject_t &hoid,
-       const std::map<std::string, ceph::buffer::list> &attrs) = 0;
+       const std::map<std::string, ceph::buffer::list, std::less<>> &attrs) = 0;
 
      virtual bool try_lock_for_read(
        const hobject_t &hoid,
@@ -557,7 +557,7 @@ typedef std::shared_ptr<const OSDMap> OSDMapRef;
 
    virtual int objects_get_attrs(
      const hobject_t &hoid,
-     std::map<std::string, ceph::buffer::list> *out);
+     std::map<std::string, ceph::buffer::list, std::less<>> *out);
 
    virtual int objects_read_sync(
      const hobject_t &hoid,
diff --git a/src/osd/PGTransaction.h b/src/osd/PGTransaction.h
index 3b5b9e72cfa..e6f57c90fa1 100644
--- a/src/osd/PGTransaction.h
+++ b/src/osd/PGTransaction.h
@@ -359,12 +359,12 @@ public:
   /// Attr ops
   void setattrs(
     const hobject_t &hoid,         ///< [in] object to write
-    std::map<std::string, ceph::buffer::list> &attrs ///< [in] attrs, may be cleared
+    std::map<std::string, ceph::buffer::list, std::less<>> &attrs ///< [in] attrs, may be cleared
     ) {
     auto &op = get_object_op_for_modify(hoid);
-    for (auto &&i: attrs) {
-      auto& d = op.attr_updates[i.first];
-      d = i.second;
+    for (auto &[key, val]: attrs) {
+      auto& d = op.attr_updates[key];
+      d = val;
       d->rebuild();
     }
   }
diff --git a/src/osd/PrimaryLogPG.cc b/src/osd/PrimaryLogPG.cc
index 7663170f043..25545e07961 100644
--- a/src/osd/PrimaryLogPG.cc
+++ b/src/osd/PrimaryLogPG.cc
@@ -4846,7 +4846,7 @@ int PrimaryLogPG::trim_object(
     head_obc->obs.oi.prior_version = head_obc->obs.oi.version;
     head_obc->obs.oi.version = ctx->at_version;
 
-    map <string, bufferlist> attrs;
+    map <string, bufferlist, less<>> attrs;
     bl.clear();
     encode(snapset, bl);
     attrs[SS_ATTR] = std::move(bl);
@@ -6341,7 +6341,7 @@ int PrimaryLogPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
       ++ctx->num_read;
       {
 	tracepoint(osd, do_osd_op_pre_getxattrs, soid.oid.name.c_str(), soid.snap.val);
-	map<string, bufferlist> out;
+	map<string, bufferlist,less<>> out;
 	result = getattrs_maybe_cache(
 	  ctx->obc,
 	  &out);
@@ -7137,7 +7137,7 @@ int PrimaryLogPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
 	  oi.user_version = target_version;
 	  ctx->user_at_version = target_version;
 	  /* rm_attrs */
-	  map<string,bufferlist> rmattrs;
+	  map<string,bufferlist,less<>> rmattrs;
 	  result = getattrs_maybe_cache(ctx->obc, &rmattrs);
 	  if (result < 0) {
 	    dout(10) << __func__ << " error: " << cpp_strerror(result) << dendl;
@@ -8937,7 +8937,7 @@ void PrimaryLogPG::finish_ctx(OpContext *ctx, int log_op_type, int result)
     }
 
     // object_info_t
-    map <string, bufferlist> attrs;
+    map <string, bufferlist, less<>> attrs;
     bufferlist bv(sizeof(ctx->new_obs.oi));
     encode(ctx->new_obs.oi, bv,
 	     get_osdmap()->get_features(CEPH_ENTITY_TYPE_OSD, nullptr));
@@ -9189,7 +9189,7 @@ int PrimaryLogPG::do_copy_get(OpContext *ctx, bufferlist::const_iterator& bp,
   reply_obj.truncate_size = oi.truncate_size;
 
   // attrs
-  map<string,bufferlist>& out_attrs = reply_obj.attrs;
+  map<string,bufferlist,less<>>& out_attrs = reply_obj.attrs;
   if (!cursor.attr_complete) {
     result = getattrs_maybe_cache(
       ctx->obc,
@@ -11776,7 +11776,7 @@ ObjectContextRef PrimaryLogPG::create_object_context(const object_info_t& oi,
 ObjectContextRef PrimaryLogPG::get_object_context(
   const hobject_t& soid,
   bool can_create,
-  const map<string, bufferlist> *attrs)
+  const map<string, bufferlist, less<>> *attrs)
 {
   auto it_objects = recovery_state.get_pg_log().get_log().objects.find(soid);
   ceph_assert(
@@ -12196,7 +12196,7 @@ void PrimaryLogPG::kick_object_context_blocked(ObjectContextRef obc)
 SnapSetContext *PrimaryLogPG::get_snapset_context(
   const hobject_t& oid,
   bool can_create,
-  const map<string, bufferlist> *attrs,
+  const map<string, bufferlist, less<>> *attrs,
   bool oid_existed)
 {
   std::lock_guard l(snapset_contexts_lock);
@@ -14579,9 +14579,10 @@ void PrimaryLogPG::hit_set_persist()
         0, bl.length());
     ctx->clean_regions.mark_data_region_dirty(0, bl.length());
   }
-  map <string, bufferlist> attrs;
-  attrs[OI_ATTR] = std::move(boi);
-  attrs[SS_ATTR] = std::move(bss);
+  map<string, bufferlist, std::less<>> attrs = {
+    {OI_ATTR, std::move(boi)},
+    {SS_ATTR, std::move(bss)}
+  };
   setattrs_maybe_cache(ctx->obc, ctx->op_t.get(), attrs);
   ctx->log.push_back(
     pg_log_entry_t(
@@ -15684,7 +15685,7 @@ void PrimaryLogPG::setattr_maybe_cache(
 void PrimaryLogPG::setattrs_maybe_cache(
   ObjectContextRef obc,
   PGTransaction *t,
-  map<string, bufferlist> &attrs)
+  map<string, bufferlist, less<>> &attrs)
 {
   t->setattrs(obc->obs.oi.soid, attrs);
 }
@@ -15717,7 +15718,7 @@ int PrimaryLogPG::getattr_maybe_cache(
 
 int PrimaryLogPG::getattrs_maybe_cache(
   ObjectContextRef obc,
-  map<string, bufferlist> *out)
+  map<string, bufferlist, less<>> *out)
 {
   int r = 0;
   ceph_assert(out);
@@ -15726,12 +15727,11 @@ int PrimaryLogPG::getattrs_maybe_cache(
   } else {
     r = pgbackend->objects_get_attrs(obc->obs.oi.soid, out);
   }
-  map<string, bufferlist> tmp;
-  for (map<string, bufferlist>::iterator i = out->begin();
-       i != out->end();
-       ++i) {
-    if (i->first.size() > 1 && i->first[0] == '_')
-      tmp[i->first.substr(1, i->first.size())] = std::move(i->second);
+  map<string, bufferlist, less<>> tmp;
+  for (auto& [key, val]: *out) {
+    if (key.size() > 1 && key[0] == '_') {
+      tmp[key.substr(1, key.size())] = std::move(val);
+    }
   }
   tmp.swap(*out);
   return r;
diff --git a/src/osd/PrimaryLogPG.h b/src/osd/PrimaryLogPG.h
index 6018f366ca2..45cee803385 100644
--- a/src/osd/PrimaryLogPG.h
+++ b/src/osd/PrimaryLogPG.h
@@ -97,7 +97,7 @@ public:
     uint32_t data_digest, omap_digest;
     mempool::osd_pglog::vector<std::pair<osd_reqid_t, version_t> > reqids; // [(reqid, user_version)]
     mempool::osd_pglog::map<uint32_t, int> reqid_return_codes; // std::map reqids by index to error code
-    std::map<std::string, ceph::buffer::list> attrs; // xattrs
+    std::map<std::string, ceph::buffer::list, std::less<>> attrs; // xattrs
     uint64_t truncate_seq;
     uint64_t truncate_size;
     bool is_data_digest() {
@@ -135,7 +135,7 @@ public:
     ceph_tid_t objecter_tid2;
 
     object_copy_cursor_t cursor;
-    std::map<std::string,ceph::buffer::list> attrs;
+    std::map<std::string,ceph::buffer::list,std::less<>> attrs;
     ceph::buffer::list data;
     ceph::buffer::list omap_header;
     ceph::buffer::list omap_data;
@@ -422,7 +422,7 @@ public:
 
   ObjectContextRef get_obc(
     const hobject_t &hoid,
-    const std::map<std::string, ceph::buffer::list> &attrs) override {
+    const std::map<std::string, ceph::buffer::list, std::less<>> &attrs) override {
     return get_object_context(hoid, true, &attrs);
   }
 
@@ -1019,7 +1019,7 @@ protected:
   ObjectContextRef get_object_context(
     const hobject_t& soid,
     bool can_create,
-    const std::map<std::string, ceph::buffer::list> *attrs = 0
+    const std::map<std::string, ceph::buffer::list, std::less<>> *attrs = 0
     );
 
   void context_registry_on_change();
@@ -1039,7 +1039,7 @@ protected:
   SnapSetContext *get_snapset_context(
     const hobject_t& oid,
     bool can_create,
-    const std::map<std::string, ceph::buffer::list> *attrs = 0,
+    const std::map<std::string, ceph::buffer::list, std::less<>> *attrs = 0,
     bool oid_existed = true //indicate this oid whether exsited in backend
     );
   void register_snapset_context(SnapSetContext *ssc) {
@@ -1909,7 +1909,7 @@ public:
   void setattrs_maybe_cache(
     ObjectContextRef obc,
     PGTransaction *t,
-    std::map<std::string, ceph::buffer::list> &attrs);
+    std::map<std::string, ceph::buffer::list, std::less<>> &attrs);
   void rmattr_maybe_cache(
     ObjectContextRef obc,
     PGTransaction *t,
@@ -1920,7 +1920,7 @@ public:
     ceph::buffer::list *val);
   int getattrs_maybe_cache(
     ObjectContextRef obc,
-    std::map<std::string, ceph::buffer::list> *out);
+    std::map<std::string, ceph::buffer::list, std::less<>> *out);
 
 public:
   void set_dynamic_perf_stats_queries(
diff --git a/src/osd/ReplicatedBackend.cc b/src/osd/ReplicatedBackend.cc
index 669cdbce020..f26650bb86d 100644
--- a/src/osd/ReplicatedBackend.cc
+++ b/src/osd/ReplicatedBackend.cc
@@ -382,7 +382,7 @@ void generate_transaction(
       }
 
       if (!op.attr_updates.empty()) {
-	map<string, bufferlist> attrs;
+	map<string, bufferlist, less<>> attrs;
 	for (auto &&p: op.attr_updates) {
 	  if (p.second)
 	    attrs[p.first] = *(p.second);
@@ -1599,7 +1599,7 @@ void ReplicatedBackend::submit_push_data(
   const interval_set<uint64_t> &intervals_included,
   bufferlist data_included,
   bufferlist omap_header,
-  const map<string, bufferlist> &attrs,
+  const map<string, bufferlist, less<>> &attrs,
   const map<string, bufferlist> &omap_entries,
   ObjectStore::Transaction *t)
 {
diff --git a/src/osd/ReplicatedBackend.h b/src/osd/ReplicatedBackend.h
index f4b5063579a..b1cfe4dd270 100644
--- a/src/osd/ReplicatedBackend.h
+++ b/src/osd/ReplicatedBackend.h
@@ -280,7 +280,7 @@ private:
 			const interval_set<uint64_t> &intervals_included,
 			ceph::buffer::list data_included,
 			ceph::buffer::list omap_header,
-			const std::map<std::string, ceph::buffer::list> &attrs,
+			const std::map<std::string, ceph::buffer::list, std::less<>> &attrs,
 			const std::map<std::string, ceph::buffer::list> &omap_entries,
 			ObjectStore::Transaction *t);
   void submit_push_complete(const ObjectRecoveryInfo &recovery_info,
diff --git a/src/osd/osd_internal_types.h b/src/osd/osd_internal_types.h
index 17f4f314643..80ecb67a889 100644
--- a/src/osd/osd_internal_types.h
+++ b/src/osd/osd_internal_types.h
@@ -41,7 +41,7 @@ public:
   std::map<std::pair<uint64_t, entity_name_t>, WatchRef> watchers;
 
   // attr cache
-  std::map<std::string, ceph::buffer::list> attr_cache;
+  std::map<std::string, ceph::buffer::list, std::less<>> attr_cache;
 
   RWState rwstate;
   std::list<OpRequestRef> waiters;  ///< ops waiting on state change
diff --git a/src/osd/osd_types.h b/src/osd/osd_types.h
index fe2fe7defa9..94693bdfc0f 100644
--- a/src/osd/osd_types.h
+++ b/src/osd/osd_types.h
@@ -5310,7 +5310,7 @@ struct object_copy_data_t {
   utime_t mtime;
   uint32_t data_digest, omap_digest;
   uint32_t flags;
-  std::map<std::string, ceph::buffer::list> attrs;
+  std::map<std::string, ceph::buffer::list, std::less<>> attrs;
   ceph::buffer::list data;
   ceph::buffer::list omap_header;
   ceph::buffer::list omap_data;
@@ -6031,7 +6031,7 @@ struct PushOp {
   interval_set<uint64_t> data_included;
   ceph::buffer::list omap_header;
   std::map<std::string, ceph::buffer::list> omap_entries;
-  std::map<std::string, ceph::buffer::list> attrset;
+  std::map<std::string, ceph::buffer::list, std::less<>> attrset;
 
   ObjectRecoveryInfo recovery_info;
   ObjectRecoveryProgress before_progress;
@@ -6056,7 +6056,7 @@ enum class scrub_type_t : bool { not_repair = false, do_repair = true };
  */
 struct ScrubMap {
   struct object {
-    std::map<std::string, ceph::buffer::ptr> attrs;
+    std::map<std::string, ceph::buffer::ptr, std::less<>> attrs;
     uint64_t size;
     __u32 omap_digest;         ///< omap crc32c
     __u32 digest;              ///< data crc32c
diff --git a/src/osdc/Objecter.h b/src/osdc/Objecter.h
index de1e7adf319..e4c7ab4b4b6 100644
--- a/src/osdc/Objecter.h
+++ b/src/osdc/Objecter.h
@@ -1028,7 +1028,7 @@ struct ObjectOperation {
     object_copy_cursor_t *cursor;
     uint64_t *out_size;
     ceph::real_time *out_mtime;
-    std::map<std::string,ceph::buffer::list> *out_attrs;
+    std::map<std::string,ceph::buffer::list,std::less<>> *out_attrs;
     ceph::buffer::list *out_data, *out_omap_header, *out_omap_data;
     std::vector<snapid_t> *out_snaps;
     snapid_t *out_snap_seq;
@@ -1043,7 +1043,7 @@ struct ObjectOperation {
     C_ObjectOperation_copyget(object_copy_cursor_t *c,
 			      uint64_t *s,
 			      ceph::real_time *m,
-			      std::map<std::string,ceph::buffer::list> *a,
+			      std::map<std::string,ceph::buffer::list,std::less<>> *a,
 			      ceph::buffer::list *d, ceph::buffer::list *oh,
 			      ceph::buffer::list *o,
 			      std::vector<snapid_t> *osnaps,
@@ -1122,7 +1122,7 @@ struct ObjectOperation {
 		uint64_t max,
 		uint64_t *out_size,
 		ceph::real_time *out_mtime,
-		std::map<std::string,ceph::buffer::list> *out_attrs,
+		std::map<std::string,ceph::buffer::list,std::less<>> *out_attrs,
 		ceph::buffer::list *out_data,
 		ceph::buffer::list *out_omap_header,
 		ceph::buffer::list *out_omap_data,
diff --git a/src/test/fio/fio_ceph_objectstore.cc b/src/test/fio/fio_ceph_objectstore.cc
index 86d38919426..0846904b1bc 100644
--- a/src/test/fio/fio_ceph_objectstore.cc
+++ b/src/test/fio/fio_ceph_objectstore.cc
@@ -743,7 +743,7 @@ enum fio_q_status fio_ceph_os_queue(thread_data* td, io_u* u)
     bl.push_back(buffer::copy(reinterpret_cast<char*>(u->xfer_buf),
                               u->xfer_buflen ) );
 
-    map<string,bufferptr> attrset;
+    map<string,bufferptr,less<>> attrset;
     map<string, bufferlist> omaps;
     // enqueue a write transaction on the collection's handle
     ObjectStore::Transaction t;
@@ -827,7 +827,7 @@ enum fio_q_status fio_ceph_os_queue(thread_data* td, io_u* u)
       }
     }
 
-    if (attrset.size()) {
+    if (!attrset.empty()) {
       t.setattrs(coll.cid, object.oid, attrset);
     }
     t.write(coll.cid, object.oid, u->offset, u->xfer_buflen, bl, flags);
diff --git a/src/test/objectstore/FileStoreDiff.cc b/src/test/objectstore/FileStoreDiff.cc
index e6848570110..a99e6f3d7d4 100644
--- a/src/test/objectstore/FileStoreDiff.cc
+++ b/src/test/objectstore/FileStoreDiff.cc
@@ -43,12 +43,12 @@ FileStoreDiff::~FileStoreDiff()
 }
 
 
-bool FileStoreDiff::diff_attrs(std::map<std::string,bufferptr>& b,
-    std::map<std::string,bufferptr>& a)
+bool FileStoreDiff::diff_attrs(std::map<std::string,bufferptr,std::less<>>& b,
+    std::map<std::string,bufferptr,std::less<>>& a)
 {
   bool ret = false;
-  std::map<std::string, bufferptr>::iterator b_it = b.begin();
-  std::map<std::string, bufferptr>::iterator a_it = a.begin();
+  auto b_it = b.begin();
+  auto a_it = a.begin();
   for (; b_it != b.end(); ++b_it, ++a_it) {
     if (b_it->first != a_it->first) {
       cout << "diff_attrs name mismatch (verify: " << b_it->first
@@ -204,7 +204,7 @@ bool FileStoreDiff::diff_objects(FileStore *a_store, FileStore *b_store, coll_t
       ret = true;
     }
 
-    std::map<std::string, bufferptr> a_obj_attrs_map, b_obj_attrs_map;
+    std::map<std::string, bufferptr, std::less<>> a_obj_attrs_map, b_obj_attrs_map;
     err = a_store->getattrs(a_ch, a_obj, a_obj_attrs_map);
     if (err < 0) {
       cout << "diff_objects getattrs on A object " << coll << "/" << a_obj
diff --git a/src/test/objectstore/FileStoreDiff.h b/src/test/objectstore/FileStoreDiff.h
index ba9cfb9837b..56b53dddb1f 100644
--- a/src/test/objectstore/FileStoreDiff.h
+++ b/src/test/objectstore/FileStoreDiff.h
@@ -29,8 +29,8 @@ class FileStoreDiff {
 
   bool diff_objects(FileStore *a_store, FileStore *b_store, coll_t coll);
   bool diff_objects_stat(struct stat& a, struct stat& b);
-  bool diff_attrs(std::map<std::string,bufferptr>& b,
-      std::map<std::string,bufferptr>& a);
+  bool diff_attrs(std::map<std::string,bufferptr,std::less<>>& b,
+      std::map<std::string,bufferptr,std::less<>>& a);
 
 public:
   FileStoreDiff(FileStore *a, FileStore *b);
diff --git a/src/test/objectstore/store_test.cc b/src/test/objectstore/store_test.cc
index 176d1d48b84..c77929b0c22 100644
--- a/src/test/objectstore/store_test.cc
+++ b/src/test/objectstore/store_test.cc
@@ -2805,7 +2805,7 @@ TEST_P(StoreTest, SimpleAttrTest) {
     bl.append(bp);
     ASSERT_TRUE(bl_eq(val, bl));
 
-    map<string,bufferptr> bm;
+    map<string,bufferptr,less<>> bm;
     r = store->getattrs(ch, hoid, bm);
     ASSERT_EQ(0, r);
 
@@ -4565,7 +4565,7 @@ public:
     boost::uniform_int<> u3(0, 100);
     uint64_t size = u0(*rng);
     uint64_t name_len;
-    map<string, bufferlist> attrs;
+    map<string, bufferlist, less<>> attrs;
     set<string> keys;
     for (map<string, bufferlist>::iterator it = contents[obj].attrs.begin();
          it != contents[obj].attrs.end(); ++it)
@@ -4607,7 +4607,7 @@ public:
     available_objects.erase(obj);
     ObjectStore::Transaction t;
 
-    map<string, bufferlist> attrs;
+    map<string, bufferlist, less<>> attrs;
     set<string> keys;
 
     while (entries--) {
@@ -4644,7 +4644,7 @@ public:
       } while (contents[obj].attrs.empty());
       expected = contents[obj].attrs;
     }
-    map<string, bufferlist> attrs;
+    map<string, bufferlist, less<>> attrs;
     int r = store->getattrs(ch, obj, attrs);
     ASSERT_TRUE(r == 0);
     ASSERT_TRUE(attrs.size() == expected.size());
@@ -5736,7 +5736,7 @@ TEST_P(StoreTest, XattrTest) {
     ASSERT_EQ(r, 0);
   }
 
-  map<string, bufferptr> aset;
+  map<string, bufferptr, less<>> aset;
   store->getattrs(ch, hoid, aset);
   ASSERT_EQ(aset.size(), attrs.size());
   for (map<string, bufferptr>::iterator i = aset.begin();
diff --git a/src/tools/RadosDump.h b/src/tools/RadosDump.h
index 83f02e69d51..213351e17b0 100644
--- a/src/tools/RadosDump.h
+++ b/src/tools/RadosDump.h
@@ -219,9 +219,9 @@ struct data_section {
 };
 
 struct attr_section {
-  map<string,bufferlist> data;
-  explicit attr_section(const map<string,bufferlist> &data) : data(data) { }
-  explicit attr_section(map<string, bufferptr> &data_)
+  map<string,bufferlist,less<>> data;
+  explicit attr_section(const map<string,bufferlist,less<>> &data) : data(data) { }
+  explicit attr_section(map<string, bufferptr, less<>> &data_)
   {
     for (std::map<std::string, bufferptr>::iterator i = data_.begin();
          i != data_.end(); ++i) {
diff --git a/src/tools/ceph_objectstore_tool.cc b/src/tools/ceph_objectstore_tool.cc
index 202695d89b0..5035e367d81 100644
--- a/src/tools/ceph_objectstore_tool.cc
+++ b/src/tools/ceph_objectstore_tool.cc
@@ -806,7 +806,7 @@ int ObjectStoreTool::export_file(ObjectStore *store, coll_t cid, ghobject_t &obj
   }
 
   //Handle attrs for this object
-  map<string,bufferptr> aset;
+  map<string,bufferptr,less<>> aset;
   ret = store->getattrs(ch, obj, aset);
   if (ret) return ret;
   attr_section as(aset);
@@ -2143,7 +2143,7 @@ int do_remove_object(ObjectStore *store, coll_t coll,
 int do_list_attrs(ObjectStore *store, coll_t coll, ghobject_t &ghobj)
 {
   auto ch = store->open_collection(coll);
-  map<string,bufferptr> aset;
+  map<string,bufferptr,less<>> aset;
   int r = store->getattrs(ch, ghobj, aset);
   if (r < 0) {
     cerr << "getattrs: " << cpp_strerror(r) << std::endl;
@@ -3005,7 +3005,7 @@ int dup(string srcpath, ObjectStore *src, string dstpath, ObjectStore *dst)
 	ObjectStore::Transaction t;
 	t.touch(cid, oid);
 
-	map<string,bufferptr> attrs;
+	map<string,bufferptr,less<>> attrs;
 	src->getattrs(ch, oid, attrs);
 	if (!attrs.empty()) {
 	  t.setattrs(cid, oid, attrs);
diff --git a/src/tools/rados/PoolDump.cc b/src/tools/rados/PoolDump.cc
index 9bfafa107dc..207017036ee 100644
--- a/src/tools/rados/PoolDump.cc
+++ b/src/tools/rados/PoolDump.cc
@@ -96,7 +96,7 @@ int PoolDump::dump(IoCtx *io_ctx)
     // Compose TYPE_ATTRS chunk
     // ========================
     std::map<std::string, bufferlist> raw_xattrs;
-    std::map<std::string, bufferlist> xattrs;
+    std::map<std::string, bufferlist,less<>> xattrs;
     r = io_ctx->getxattrs(oid, raw_xattrs);
     if (r < 0) {
       cerr << "error getting xattr set " << oid << ": " << cpp_strerror(r)