diff --git a/src/crimson/os/seastore/cache.cc b/src/crimson/os/seastore/cache.cc
index 9c6ff428a5c..ea0fb10b5dd 100644
--- a/src/crimson/os/seastore/cache.cc
+++ b/src/crimson/os/seastore/cache.cc
@@ -209,8 +209,9 @@ std::optional<record_t> Cache::try_construct_record(Transaction &t)
 {
   // First, validate read set
   for (auto &i: t.read_set) {
-    if (i->state == CachedExtent::extent_state_t::INVALID)
+    if (i->state == CachedExtent::extent_state_t::INVALID) {
       return std::nullopt;
+    }
   }
 
   record_t record;
diff --git a/src/crimson/os/seastore/onode.h b/src/crimson/os/seastore/onode.h
index 21c0fba8aa5..955d3a9d802 100644
--- a/src/crimson/os/seastore/onode.h
+++ b/src/crimson/os/seastore/onode.h
@@ -14,10 +14,29 @@
 namespace crimson::os::seastore {
 
 struct onode_layout_t {
+  // around 350 bytes for fixed fields in object_info_t,
+  // the left are for the variable-sized fields like oid
+  // FIXME: object_info_t may need to shrinked, at least
+  // 	    oid doesn't need to be held in it.
+  static constexpr int MAX_OI_LENGTH = 1024;
+  // We might want to move the ss field out of onode_layout_t.
+  // The reason is that ss_attr may grow to relative large, as
+  // its clone_overlap may grow to a large size, if applications
+  // set objects to a relative large size(for the purpose of reducing
+  // the number of objects per OSD, so that all objects' metadata
+  // can be cached in memory) and do many modifications between
+  // snapshots.
+  static constexpr int MAX_SS_LENGTH = 128;
+
   ceph_le32 size{0};
+  ceph_le32 oi_size{0};
+  ceph_le32 ss_size{0};
   omap_root_le_t omap_root;
 
   object_data_le_t object_data;
+
+  char oi[MAX_OI_LENGTH];
+  char ss[MAX_SS_LENGTH];
 } __attribute__((packed));
 
 class Transaction;
diff --git a/src/crimson/os/seastore/onode_manager.h b/src/crimson/os/seastore/onode_manager.h
index c8b95a4bd42..5031afd33dc 100644
--- a/src/crimson/os/seastore/onode_manager.h
+++ b/src/crimson/os/seastore/onode_manager.h
@@ -37,7 +37,8 @@ public:
     return seastar::make_ready_future<OnodeRef>();
   }
 
-  using get_or_create_onode_ertr = base_ertr;
+  using get_or_create_onode_ertr = base_ertr::extend<
+    crimson::ct_error::value_too_large>;
   using get_or_create_onode_ret = get_or_create_onode_ertr::future<
     OnodeRef>;
   virtual get_or_create_onode_ret get_or_create_onode(
@@ -46,7 +47,8 @@ public:
     return seastar::make_ready_future<OnodeRef>();
   }
 
-  using get_or_create_onodes_ertr = base_ertr;
+  using get_or_create_onodes_ertr = base_ertr::extend<
+    crimson::ct_error::value_too_large>;
   using get_or_create_onodes_ret = get_or_create_onodes_ertr::future<
     std::vector<OnodeRef>>;
   virtual get_or_create_onodes_ret get_or_create_onodes(
diff --git a/src/crimson/os/seastore/onode_manager/staged-fltree/fltree_onode_manager.cc b/src/crimson/os/seastore/onode_manager/staged-fltree/fltree_onode_manager.cc
index 6fd7fee5fe8..b75f85e02eb 100644
--- a/src/crimson/os/seastore/onode_manager/staged-fltree/fltree_onode_manager.cc
+++ b/src/crimson/os/seastore/onode_manager/staged-fltree/fltree_onode_manager.cc
@@ -2,6 +2,7 @@
 // vim: ts=8 sw=2 smarttab
 
 #include "crimson/os/seastore/onode_manager/staged-fltree/fltree_onode_manager.h"
+#include "crimson/os/seastore/onode_manager/staged-fltree/stages/key_layout.h"
 
 namespace {
 [[maybe_unused]] seastar::logger& logger() {
@@ -41,6 +42,10 @@ FLTreeOnodeManager::get_or_create_onode_ret
 FLTreeOnodeManager::get_or_create_onode(
   Transaction &trans,
   const ghobject_t &hoid) {
+  if (hoid.hobj.oid.name.length() + hoid.hobj.nspace.length()
+      > key_view_t::MAX_NS_OID_LENGTH) {
+    return crimson::ct_error::value_too_large::make();
+  }
   return tree.insert(
     trans, hoid,
     OnodeTree::tree_value_config_t{sizeof(onode_layout_t)}
diff --git a/src/crimson/os/seastore/onode_manager/staged-fltree/stages/key_layout.h b/src/crimson/os/seastore/onode_manager/staged-fltree/stages/key_layout.h
index ff3cc305e49..d5513cdce68 100644
--- a/src/crimson/os/seastore/onode_manager/staged-fltree/stages/key_layout.h
+++ b/src/crimson/os/seastore/onode_manager/staged-fltree/stages/key_layout.h
@@ -9,6 +9,7 @@
 #include <ostream>
 
 #include "common/hobject.h"
+#include "crimson/os/seastore/onode.h"
 #include "crimson/os/seastore/onode_manager/staged-fltree/fwd.h"
 
 namespace crimson::os::seastore::onode {
@@ -555,6 +556,13 @@ inline std::ostream& operator<<(std::ostream& os, const key_hobj_t& key) {
  */
 class key_view_t {
  public:
+  //FIXME: the length of ns and oid should be defined by osd_max_object_name_len
+  //       and object_max_object_namespace_len in the future
+  static constexpr int MAX_NS_OID_LENGTH =
+    (4096 - sizeof(onode_layout_t) * 2) / 4
+    - sizeof(shard_pool_t) - sizeof(crush_t) - sizeof(snap_gen_t)
+    - 8; // size of length field of oid and ns
+
   /**
    * common interfaces as a full_key_t
    */
diff --git a/src/crimson/os/seastore/root_block.h b/src/crimson/os/seastore/root_block.h
index 57d64ad7ca1..fe7bdf99316 100644
--- a/src/crimson/os/seastore/root_block.h
+++ b/src/crimson/os/seastore/root_block.h
@@ -38,6 +38,8 @@ struct RootBlock : CachedExtent {
 
   root_t root;
 
+  std::map<std::string, std::string> meta;
+
   RootBlock() : CachedExtent(0) {}
 
   RootBlock(const RootBlock &rhs) = default;
@@ -66,6 +68,11 @@ struct RootBlock : CachedExtent {
     ceph::bufferlist bl = _bl;
     bl.rebuild();
     root = *reinterpret_cast<const root_t*>(bl.front().c_str());
+    if (root.have_meta) {
+      ceph::bufferlist meta_bl;
+      meta_bl.rebuild(ceph::buffer::ptr_node::create(&root.meta[0], root_t::MAX_META_LENGTH));
+      decode(meta, meta_bl);
+    }
     root.adjust_addrs_from_base(base);
   }
 
@@ -83,6 +90,7 @@ struct RootBlock : CachedExtent {
   }
 
   root_t &get_root() { return root; }
+
 };
 using RootBlockRef = RootBlock::Ref;
 
diff --git a/src/crimson/os/seastore/seastore.cc b/src/crimson/os/seastore/seastore.cc
index 899019e0bd3..8a477b591d8 100644
--- a/src/crimson/os/seastore/seastore.cc
+++ b/src/crimson/os/seastore/seastore.cc
@@ -212,7 +212,17 @@ SeaStore::get_attrs_ertr::future<SeaStore::attrs_t> SeaStore::get_attrs(
   auto c = static_cast<SeastoreCollection*>(ch.get());
   logger().debug("{} {} {}",
 		 __func__, c->get_cid(), oid);
-  return crimson::ct_error::enoent::make();
+  return repeat_with_onode<attrs_t>(
+    c, oid, [=](auto &t, auto& onode) {
+    auto& layout = onode.get_layout();
+    SeaStore::attrs_t attrs;
+    attrs[OI_ATTR] = ceph::bufferptr(&layout.oi[0], layout.oi_size);
+    attrs[SS_ATTR] = ceph::bufferptr(&layout.ss[0], layout.ss_size);
+    return attrs;
+  }).handle_error(crimson::ct_error::input_output_error::handle([this] {
+    logger().error("EIO when getting attrs");
+    abort();
+  }), crimson::ct_error::pass_further_all{});
 }
 
 seastar::future<struct stat> SeaStore::stat(
@@ -803,6 +813,31 @@ SeaStore::tm_ret SeaStore::_setattrs(
 {
   logger().debug("{} onode={}",
                 __func__, *onode);
+  auto& layout = onode->get_mutable_layout(*ctx.transaction);
+  for (auto& [key, val] : aset) {
+    if (key == OI_ATTR) {
+      if (__builtin_expect(
+          val.length() > onode_layout_t::MAX_OI_LENGTH,
+          false)) {
+        logger().error("{} onode={} oi attr too long!");
+        return crimson::ct_error::input_output_error::make();
+      }
+      layout.oi_size = val.length();
+      val.copy_out(0, val.length(), &layout.oi[0]);
+    } else if (key == SS_ATTR) {
+      if (__builtin_expect(
+          val.length() > onode_layout_t::MAX_SS_LENGTH,
+          false)) {
+        logger().error("{} onode={} oi attr too long!");
+        return crimson::ct_error::input_output_error::make();
+      }
+      layout.ss_size = val.length();
+      val.copy_out(0, val.length(), &layout.ss[0]);
+    } else {
+      //FIXME: right now, only OI_ATTR and SS_ATTR are supported
+      assert(0 == "only OI_ATTR and SS_ATTR are supported for now");
+    }
+  }
   return tm_ertr::now();
 }
 
@@ -876,13 +911,41 @@ boost::intrusive_ptr<SeastoreCollection> SeaStore::_get_collection(const coll_t&
 seastar::future<> SeaStore::write_meta(const std::string& key,
 					const std::string& value)
 {
-  return seastar::make_ready_future<>();
+  logger().debug("{}, key: {}; value: {}", __func__, key, value);
+  return seastar::do_with(key, value,
+    [this](auto& key, auto& value) {
+    return repeat_eagain([this, &key, &value] {
+      auto t = transaction_manager->create_transaction();
+      return transaction_manager->get_root(*t).safe_then(
+        [this, t=std::move(t), &key, &value](auto root) mutable {
+        transaction_manager->update_root_meta(*t, key, value);
+        return transaction_manager->submit_transaction(std::move(t));
+      });
+    });
+  }).handle_error(
+    crimson::ct_error::assert_all{"Invalid error in Seastar::write_meta"}
+  );
 }
 
 seastar::future<std::tuple<int, std::string>> SeaStore::read_meta(const std::string& key)
 {
-  return seastar::make_ready_future<std::tuple<int, std::string>>(
-    std::make_tuple(0, ""s));
+  logger().debug("{}, key: {}", __func__, key);
+  return seastar::do_with(transaction_manager->create_transaction(), key,
+    [this](auto& t, auto& key) {
+    return transaction_manager->get_root(*t).safe_then(
+      [this, &key](auto root) {
+      auto& meta = root->meta;
+      auto it = meta.find(key);
+      if (it != meta.end()) {
+        return seastar::make_ready_future<std::tuple<int, std::string>>(
+          std::make_tuple(0, it->second));
+      }
+      return seastar::make_ready_future<std::tuple<int, std::string>>(
+        std::make_tuple(-1, std::string("")));
+    });
+  }).handle_error(
+    crimson::ct_error::assert_all{"Invalid error in Seastar::write_meta"}
+  );
 }
 
 uuid_d SeaStore::get_fsid() const
diff --git a/src/crimson/os/seastore/seastore_types.h b/src/crimson/os/seastore/seastore_types.h
index 59b329c0fcc..9b0e43fb801 100644
--- a/src/crimson/os/seastore/seastore_types.h
+++ b/src/crimson/os/seastore/seastore_types.h
@@ -655,9 +655,14 @@ public:
  * TODO: generalize this to permit more than one lba_manager implementation
  */
 struct __attribute__((packed)) root_t {
+
+  static constexpr int MAX_META_LENGTH = 1024;
+
   lba_root_t lba_root;
   laddr_le_t onode_root;
   coll_root_le_t collection_root;
+  char meta[MAX_META_LENGTH];
+  bool have_meta = false;
 
   void adjust_addrs_from_base(paddr_t base) {
     lba_root.adjust_addrs_from_base(base);
diff --git a/src/crimson/os/seastore/transaction.h b/src/crimson/os/seastore/transaction.h
index d17907a3fa9..7a46e5c2993 100644
--- a/src/crimson/os/seastore/transaction.h
+++ b/src/crimson/os/seastore/transaction.h
@@ -15,6 +15,7 @@
 namespace crimson::os::seastore {
 
 struct retired_extent_gate_t;
+class SeaStore;
 
 /**
  * Transaction
@@ -161,6 +162,8 @@ public:
       write_set.erase(*i++);
     }
   }
+
+  friend class crimson::os::seastore::SeaStore;
 };
 using TransactionRef = Transaction::Ref;
 
diff --git a/src/crimson/os/seastore/transaction_manager.h b/src/crimson/os/seastore/transaction_manager.h
index a49af8c9e5c..68736657f09 100644
--- a/src/crimson/os/seastore/transaction_manager.h
+++ b/src/crimson/os/seastore/transaction_manager.h
@@ -374,6 +374,53 @@ public:
     return segment_manager.release(id);
   }
 
+  /**
+   * get_root
+   *
+   * Get root block's ondisk layout
+   */
+  using get_root_ertr = base_ertr;
+  using get_root_ret = get_root_ertr::future<RootBlockRef>;
+  get_root_ret get_root(Transaction &t) {
+    return cache->get_root(t);
+  }
+
+  /**
+   * update_root_meta
+   *
+   * modify root block's meta field
+   */
+  using update_root_meta_ertr = base_ertr::extend<
+    crimson::ct_error::value_too_large>;
+  using update_root_meta_ret = update_root_meta_ertr::future<>;
+  update_root_meta_ret update_root_meta(Transaction& t,
+                                        const std::string& key,
+                                        const std::string& value) {
+    auto root = cache->get_root_fast(t);
+    root = cache->duplicate_for_write(t, root)->cast<RootBlock>();
+    root->meta[key] = value;
+
+    // calculate meta size
+    // TODO: we probably need a uniformal interface for calcuting
+    // the encoded size of data structures
+    uint32_t meta_size = 4; // initial 4 bytes for std::map size
+    for (auto& [key, val] : root->meta) {
+      // sizes of length fields for key and val + sizes of key and val
+      meta_size += 8 + key.length() + val.length();
+    }
+
+    if (meta_size > root_t::MAX_META_LENGTH) {
+      return crimson::ct_error::value_too_large::make();
+    }
+
+    ceph::bufferlist bl(1);
+    bl.rebuild(ceph::buffer::ptr_node::create(
+      &root->get_root().meta[0], root_t::MAX_META_LENGTH));
+    encode(root->meta, bl);
+    root->get_root().have_meta = true;
+    return update_root_meta_ertr::now();
+  }
+
   /**
    * read_onode_root
    *
diff --git a/src/test/crimson/seastore/test_seastore.cc b/src/test/crimson/seastore/test_seastore.cc
index 33837bdbb9e..eb20b965d61 100644
--- a/src/test/crimson/seastore/test_seastore.cc
+++ b/src/test/crimson/seastore/test_seastore.cc
@@ -53,6 +53,17 @@ struct seastore_test_t :
       std::move(t)).get0();
   }
 
+  void set_meta(
+    const std::string& key,
+    const std::string& value) {
+    return seastore->write_meta(key, value).get0();
+  }
+
+  std::tuple<int, std::string> get_meta(
+    const std::string& key) {
+    return seastore->read_meta(key).get();
+  }
+
   struct object_state_t {
     const coll_t cid;
     const CollectionRef coll;
@@ -166,6 +177,21 @@ struct seastore_test_t :
       EXPECT_EQ(contents.length(), st.st_size);
     }
 
+    void set_attr_oi(
+      SeaStore &seastore,
+      bufferlist& val) {
+      CTransaction t;
+      t.setattr(cid, oid, OI_ATTR, val);
+      seastore.do_transaction(
+        coll,
+        std::move(t)).get0();
+    }
+
+    SeaStore::attrs_t get_attr_oi(
+      SeaStore &seastore) {
+      return seastore.get_attrs(
+        coll, oid).handle_error(SeaStore::get_attrs_ertr::discard_all{}).get();
+    }
 
     void check_omap_key(
       SeaStore &seastore,
@@ -268,6 +294,20 @@ TEST_F(seastore_test_t, collection_create_list_remove)
   });
 }
 
+TEST_F(seastore_test_t, meta) {
+  run_async([this] {
+    set_meta("key1", "value1");
+    set_meta("key2", "value2");
+
+    const auto [ret1, value1] = get_meta("key1");
+    const auto [ret2, value2] = get_meta("key2");
+    EXPECT_EQ(ret1, 0);
+    EXPECT_EQ(ret2, 0);
+    EXPECT_EQ(value1, "value1");
+    EXPECT_EQ(value2, "value2");
+  });
+}
+
 TEST_F(seastore_test_t, touch_stat)
 {
   run_async([this] {
@@ -306,6 +346,23 @@ TEST_F(seastore_test_t, omap_test_simple)
   });
 }
 
+TEST_F(seastore_test_t, attr)
+{
+  run_async([this] {
+    auto& test_obj = get_object(make_oid(0));
+    std::string s("asdfasdfasdf");
+    bufferlist bl;
+    encode(s, bl);
+    test_obj.set_attr_oi(*seastore, bl);
+    auto attrs = test_obj.get_attr_oi(*seastore);
+    std::string s2;
+    bufferlist bl2;
+    bl2.push_back(attrs[OI_ATTR]);
+    decode(s2, bl);
+    EXPECT_EQ(s, s2);
+  });
+}
+
 TEST_F(seastore_test_t, omap_test_iterator)
 {
   run_async([this] {