diff --git a/src/os/bluestore/bluestore_types.cc b/src/os/bluestore/bluestore_types.cc
index 1d9212623e7f4..18669678a8e4f 100644
--- a/src/os/bluestore/bluestore_types.cc
+++ b/src/os/bluestore/bluestore_types.cc
@@ -147,7 +147,7 @@ void bluestore_extent_ref_map_t::_check() const
   }
 }
 
-void bluestore_extent_ref_map_t::_maybe_merge_left(map<uint64_t,record_t>::iterator& p)
+void bluestore_extent_ref_map_t::_maybe_merge_left(map<uint32_t,record_t>::iterator& p)
 {
   if (p == ref_map.begin())
     return;
@@ -161,9 +161,9 @@ void bluestore_extent_ref_map_t::_maybe_merge_left(map<uint64_t,record_t>::itera
   }
 }
 
-void bluestore_extent_ref_map_t::get(uint64_t offset, uint32_t length)
+void bluestore_extent_ref_map_t::get(uint32_t offset, uint32_t length)
 {
-  map<uint64_t,record_t>::iterator p = ref_map.lower_bound(offset);
+  map<uint32_t,record_t>::iterator p = ref_map.lower_bound(offset);
   if (p != ref_map.begin()) {
     --p;
     if (p->first + p->second.length <= offset) {
@@ -179,9 +179,9 @@ void bluestore_extent_ref_map_t::get(uint64_t offset, uint32_t length)
     }
     if (p->first > offset) {
       // gap
-      uint64_t newlen = MIN(p->first - offset, length);
+      uint32_t newlen = MIN(p->first - offset, length);
       p = ref_map.insert(
-	map<uint64_t,record_t>::value_type(offset,
+	map<uint32_t,record_t>::value_type(offset,
 					   record_t(newlen, 1))).first;
       offset += newlen;
       length -= newlen;
@@ -192,9 +192,9 @@ void bluestore_extent_ref_map_t::get(uint64_t offset, uint32_t length)
     if (p->first < offset) {
       // split off the portion before offset
       assert(p->first + p->second.length > offset);
-      uint64_t left = p->first + p->second.length - offset;
+      uint32_t left = p->first + p->second.length - offset;
       p->second.length = offset - p->first;
-      p = ref_map.insert(map<uint64_t,record_t>::value_type(
+      p = ref_map.insert(map<uint32_t,record_t>::value_type(
 			   offset, record_t(left, p->second.refs))).first;
       // continue below
     }
@@ -219,10 +219,10 @@ void bluestore_extent_ref_map_t::get(uint64_t offset, uint32_t length)
 }
 
 void bluestore_extent_ref_map_t::put(
-  uint64_t offset, uint32_t length,
+  uint32_t offset, uint32_t length,
   vector<bluestore_pextent_t> *release)
 {
-  map<uint64_t,record_t>::iterator p = ref_map.lower_bound(offset);
+  map<uint32_t,record_t>::iterator p = ref_map.lower_bound(offset);
   if (p == ref_map.end() || p->first > offset) {
     if (p == ref_map.begin()) {
       assert(0 == "put on missing extent (nothing before)");
@@ -233,9 +233,9 @@ void bluestore_extent_ref_map_t::put(
     }
   }
   if (p->first < offset) {
-    uint64_t left = p->first + p->second.length - offset;
+    uint32_t left = p->first + p->second.length - offset;
     p->second.length = offset - p->first;
-    p = ref_map.insert(map<uint64_t,record_t>::value_type(
+    p = ref_map.insert(map<uint32_t,record_t>::value_type(
 			 offset, record_t(left, p->second.refs))).first;
   }
   while (length > 0) {
@@ -272,9 +272,9 @@ void bluestore_extent_ref_map_t::put(
   _check();
 }
 
-bool bluestore_extent_ref_map_t::contains(uint64_t offset, uint32_t length) const
+bool bluestore_extent_ref_map_t::contains(uint32_t offset, uint32_t length) const
 {
-  map<uint64_t,record_t>::const_iterator p = ref_map.lower_bound(offset);
+  map<uint32_t,record_t>::const_iterator p = ref_map.lower_bound(offset);
   if (p == ref_map.end() || p->first > offset) {
     if (p == ref_map.begin()) {
       return false; // nothing before
@@ -291,7 +291,7 @@ bool bluestore_extent_ref_map_t::contains(uint64_t offset, uint32_t length) cons
       return false;
     if (p->first + p->second.length >= offset + length)
       return true;
-    uint64_t overlap = p->first + p->second.length - offset;
+    uint32_t overlap = p->first + p->second.length - offset;
     offset += overlap;
     length -= overlap;
     ++p;
@@ -300,10 +300,10 @@ bool bluestore_extent_ref_map_t::contains(uint64_t offset, uint32_t length) cons
 }
 
 bool bluestore_extent_ref_map_t::intersects(
-  uint64_t offset,
+  uint32_t offset,
   uint32_t length) const
 {
-  map<uint64_t,record_t>::const_iterator p = ref_map.lower_bound(offset);
+  map<uint32_t,record_t>::const_iterator p = ref_map.lower_bound(offset);
   if (p != ref_map.begin()) {
     --p;
     if (p->first + p->second.length <= offset) {
diff --git a/src/os/bluestore/bluestore_types.h b/src/os/bluestore/bluestore_types.h
index fd4eff8fee93b..66ef4697be1fe 100644
--- a/src/os/bluestore/bluestore_types.h
+++ b/src/os/bluestore/bluestore_types.h
@@ -150,10 +150,10 @@ struct bluestore_extent_ref_map_t {
   };
   WRITE_CLASS_ENCODER(record_t)
 
-  map<uint64_t,record_t> ref_map;
+  map<uint32_t,record_t> ref_map;
 
   void _check() const;
-  void _maybe_merge_left(map<uint64_t,record_t>::iterator& p);
+  void _maybe_merge_left(map<uint32_t,record_t>::iterator& p);
 
   void clear() {
     ref_map.clear();
@@ -162,11 +162,11 @@ struct bluestore_extent_ref_map_t {
     return ref_map.empty();
   }
 
-  void get(uint64_t offset, uint32_t len);
-  void put(uint64_t offset, uint32_t len, vector<bluestore_pextent_t> *release);
+  void get(uint32_t offset, uint32_t len);
+  void put(uint32_t offset, uint32_t len, vector<bluestore_pextent_t> *release);
 
-  bool contains(uint64_t offset, uint32_t len) const;
-  bool intersects(uint64_t offset, uint32_t len) const;
+  bool contains(uint32_t offset, uint32_t len) const;
+  bool intersects(uint32_t offset, uint32_t len) const;
 
   void encode(bufferlist& bl) const;
   void decode(bufferlist::iterator& p);