diff --git a/src/osd/OSD.cc b/src/osd/OSD.cc
index a3955785e35..d7733c89c71 100644
--- a/src/osd/OSD.cc
+++ b/src/osd/OSD.cc
@@ -181,7 +181,7 @@ int OSD::mkfs(const char *dev, const char *jdev, ceph_fsid_t fsid, int whoami)
     for (int i=0; i<1000; i++) {
       ObjectStore::Transaction *t = new ObjectStore::Transaction;
       t->write(meta_coll, sobject_t(oid, 0), i*bl.length(), bl.length(), bl);
-      store->queue_transaction(t);
+      store->queue_transaction(NULL, t);
     }
     store->sync();
     utime_t end = g_clock.now();
@@ -2052,7 +2052,7 @@ void OSD::handle_osd_map(MOSDMap *m)
     dout(10) << "handle_osd_map got full map epoch " << p->first << dendl;
     ObjectStore::Transaction *ft = new ObjectStore::Transaction;
     ft->write(meta_coll, poid, 0, p->second.length(), p->second);  // store _outside_ transaction; activate_map reads it.
-    int r = store->queue_transaction(ft);
+    int r = store->queue_transaction(NULL, ft);
     assert(r == 0);
 
     if (p->first > superblock.newest_map)
@@ -2079,7 +2079,7 @@ void OSD::handle_osd_map(MOSDMap *m)
     dout(10) << "handle_osd_map got incremental map epoch " << p->first << dendl;
     ObjectStore::Transaction *ft = new ObjectStore::Transaction;
     ft->write(meta_coll, poid, 0, p->second.length(), p->second);  // store _outside_ transaction; activate_map reads it.
-    int r = store->queue_transaction(ft);
+    int r = store->queue_transaction(NULL, ft);
     assert(r == 0);
 
     if (p->first > superblock.newest_map)
@@ -2818,7 +2818,7 @@ void OSD::kick_pg_split_queue()
       pg->unlock();
       created++;
     }
-    int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+    int tr = store->queue_transaction(NULL, t, new ObjectStore::C_DeleteTransaction(t), fin);
     assert(tr == 0);
 
     // remove from queue
@@ -3035,7 +3035,7 @@ void OSD::handle_pg_create(MOSDPGCreate *m)
     pg->unlock();
   }
 
-  int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+  int tr = store->queue_transaction(NULL, t, new ObjectStore::C_DeleteTransaction(t), fin);
   assert(tr == 0);
 
   do_queries(query_map);
@@ -3211,7 +3211,7 @@ void OSD::handle_pg_notify(MOSDPGNotify *m)
     pg->unlock();
   }
   
-  int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+  int tr = store->queue_transaction(NULL, t, new ObjectStore::C_DeleteTransaction(t), fin);
   assert(tr == 0);
 
   do_queries(query_map);
@@ -3323,7 +3323,7 @@ void OSD::_process_pg_info(epoch_t epoch, int from,
     }
   }
 
-  int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+  int tr = store->queue_transaction(NULL, t, new ObjectStore::C_DeleteTransaction(t), fin);
   assert(tr == 0);
 
   pg->unlock();
@@ -3402,7 +3402,7 @@ void OSD::handle_pg_trim(MOSDPGTrim *m)
       ObjectStore::Transaction *t = new ObjectStore::Transaction;
       pg->trim(*t, m->trim_to);
       pg->write_info(*t);
-      int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t));
+      int tr = store->queue_transaction(&pg->osr, t, new ObjectStore::C_DeleteTransaction(t));
       assert(tr == 0);
     }
     pg->unlock();
@@ -3474,7 +3474,7 @@ void OSD::handle_pg_query(MOSDPGQuery *m)
       pg->info.history = history;
       pg->write_info(*t);
       pg->write_log(*t);
-      int tr = store->queue_transaction(t);
+      int tr = store->queue_transaction(&pg->osr, t);
       assert(tr == 0);
       created++;
 
@@ -3611,7 +3611,7 @@ void OSD::_remove_pg(PG *pg)
     ObjectStore::Transaction *t = new ObjectStore::Transaction;
     pg->write_info(*t);
     t->remove(meta_coll, pg->log_oid);
-    int tr = store->queue_transaction(t);
+    int tr = store->queue_transaction(&pg->osr, t);
     assert(tr == 0);
   }
 
@@ -3632,7 +3632,7 @@ void OSD::_remove_pg(PG *pg)
       ObjectStore::Transaction *t = new ObjectStore::Transaction;
       t->remove(coll_t::build_snap_pg_coll(pgid, *p), *q);
       t->remove(coll_t::build_pg_coll(pgid), *q);          // we may hit this twice, but it's harmless
-      int tr = store->queue_transaction(t);
+      int tr = store->queue_transaction(&pg->osr, t);
       assert(tr == 0);
 
       if ((++n & 0xff) == 0) {
@@ -3657,7 +3657,7 @@ void OSD::_remove_pg(PG *pg)
        p++) {
     ObjectStore::Transaction *t = new ObjectStore::Transaction;
     t->remove(coll_t::build_pg_coll(pgid), *p);
-    int tr = store->queue_transaction(t);
+    int tr = store->queue_transaction(&pg->osr, t);
     assert(tr == 0);
 
     if ((++n & 0xff) == 0) {
@@ -3690,7 +3690,7 @@ void OSD::_remove_pg(PG *pg)
 
   {
     rmt->remove_collection(coll_t::build_pg_coll(pgid));
-    int tr = store->queue_transaction(rmt);
+    int tr = store->queue_transaction(NULL, rmt);
     assert(tr == 0);
   }
   
@@ -3794,7 +3794,7 @@ void OSD::generate_backlog(PG *pg)
       pg->write_info(*t);
     if (pg->dirty_log)
       pg->write_log(*t);
-    int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+    int tr = store->queue_transaction(&pg->osr, t, new ObjectStore::C_DeleteTransaction(t), fin);
     assert(tr == 0);
   }
 
@@ -3841,7 +3841,7 @@ void OSD::activate_pg(pg_t pgid, utime_t activate_at)
       ObjectStore::Transaction *t = new ObjectStore::Transaction;
       C_Contexts *fin = new C_Contexts;
       pg->activate(*t, fin->contexts);
-      int tr = store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+      int tr = store->queue_transaction(&pg->osr, t, new ObjectStore::C_DeleteTransaction(t), fin);
       assert(tr == 0);
     }
     pg->unlock();
diff --git a/src/osd/PG.cc b/src/osd/PG.cc
index 9f18cccd0ab..d240173e60d 100644
--- a/src/osd/PG.cc
+++ b/src/osd/PG.cc
@@ -1803,7 +1803,7 @@ void PG::_finish_recovery(Context *c)
       drop_backlog();
       write_info(*t);
       write_log(*t);
-      int tr = osd->store->queue_transaction(t);
+      int tr = osd->store->queue_transaction(&osr, t);
       assert(tr == 0);
     }
   } else {
@@ -2255,7 +2255,7 @@ void PG::read_log(ObjectStore *store)
 	::encode(oi, bl);
 	ObjectStore::Transaction *t = new ObjectStore::Transaction;
 	t->setattr(coll_t::build_pg_coll(info.pgid), i->soid, OI_ATTR, bl);
-	int tr = osd->store->queue_transaction(t);
+	int tr = osd->store->queue_transaction(&osr, t);
 	assert(tr == 0);
 
 	stringstream ss;
diff --git a/src/osd/PG.h b/src/osd/PG.h
index 1d45245b619..8c7d230ff6b 100644
--- a/src/osd/PG.h
+++ b/src/osd/PG.h
@@ -760,6 +760,9 @@ public:
   bool pg_stats_valid;
   pg_stat_t pg_stats_stable;
 
+  // for ordering writes
+  ObjectStore::Sequencer osr;
+
   void update_stats();
   void clear_stats();
 
diff --git a/src/osd/ReplicatedPG.cc b/src/osd/ReplicatedPG.cc
index 3e076cc7103..6988efc7972 100644
--- a/src/osd/ReplicatedPG.cc
+++ b/src/osd/ReplicatedPG.cc
@@ -835,7 +835,7 @@ bool ReplicatedPG::snap_trimmer()
 	t->setattr(coll_t::build_pg_coll(info.pgid), snapoid, SS_ATTR, bl);
       }
 
-      int tr = osd->store->queue_transaction(t);
+      int tr = osd->store->queue_transaction(&osr, t);
       assert(tr == 0);
 
       // give other threads a chance at this pg
@@ -849,7 +849,7 @@ bool ReplicatedPG::snap_trimmer()
     snap_collections.erase(sn);
     write_info(*t);
     t->remove_collection(c);
-    int tr = osd->store->queue_transaction(t);
+    int tr = osd->store->queue_transaction(&osr, t);
     assert(tr == 0);
  
     info.snap_trimq.erase(sn);
@@ -860,7 +860,7 @@ bool ReplicatedPG::snap_trimmer()
 
   ObjectStore::Transaction *t = new ObjectStore::Transaction;
   write_info(*t);
-  int tr = osd->store->queue_transaction(t);
+  int tr = osd->store->queue_transaction(&osr, t);
   assert(tr == 0);
   unlock();
   return true;
@@ -1773,7 +1773,7 @@ void ReplicatedPG::apply_repop(RepGather *repop)
   Context *oncommit = new C_OSD_OpCommit(this, repop);
   Context *onapplied = new C_OSD_OpApplied(this, repop);
   Context *onapplied_sync = new C_OSD_OndiskWriteUnlock(repop->obc);
-  int r = osd->store->queue_transactions(repop->tls, onapplied, oncommit, onapplied_sync);
+  int r = osd->store->queue_transactions(&osr, repop->tls, onapplied, oncommit, onapplied_sync);
   if (r) {
     dout(-10) << "apply_repop  queue_transactions returned " << r << " on " << *repop << dendl;
     assert(0);
@@ -2444,7 +2444,7 @@ void ReplicatedPG::sub_op_modify(MOSDSubOp *op)
   
   Context *oncommit = new C_OSD_RepModifyCommit(rm);
   Context *onapply = new C_OSD_RepModifyApply(rm);
-  int r = osd->store->queue_transactions(rm->tls, onapply, oncommit);
+  int r = osd->store->queue_transactions(&osr, rm->tls, onapply, oncommit);
   if (r) {
     derr(0) << "error applying transaction: r = " << r << dendl;
     assert(0);
@@ -3146,7 +3146,7 @@ void ReplicatedPG::sub_op_push(MOSDSubOp *op)
 
   // apply to disk!
   write_info(*t);
-  int r = osd->store->queue_transaction(t,
+  int r = osd->store->queue_transaction(&osr, t,
 					onreadable,
 					new C_OSD_Commit(this, info.history.same_acting_since,
 							 info.last_complete),
@@ -3380,7 +3380,7 @@ int ReplicatedPG::recover_primary(int max)
 	    put_object_context(headobc);
 
 	    // XXX: track objectcontext!
-	    int tr = osd->store->queue_transaction(t);
+	    int tr = osd->store->queue_transaction(&osr, t);
 	    assert(tr == 0);
 	    missing.got(latest->soid, latest->version);
 	    missing_loc.erase(latest->soid);
@@ -3429,7 +3429,7 @@ int ReplicatedPG::recover_primary(int max)
     ObjectStore::Transaction *t = new ObjectStore::Transaction;
     C_Contexts *fin = new C_Contexts;
     finish_recovery(*t, fin->contexts);
-    int tr = osd->store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+    int tr = osd->store->queue_transaction(&osr, t, new ObjectStore::C_DeleteTransaction(t), fin);
     assert(tr == 0);
   } else {
     dout(-10) << "recover_primary primary now complete, starting peer recovery" << dendl;
@@ -3494,7 +3494,7 @@ int ReplicatedPG::recover_replicas(int max)
     ObjectStore::Transaction *t = new ObjectStore::Transaction;
     C_Contexts *fin = new C_Contexts;
     finish_recovery(*t, fin->contexts);
-    int tr = osd->store->queue_transaction(t, new ObjectStore::C_DeleteTransaction(t), fin);
+    int tr = osd->store->queue_transaction(&osr, t, new ObjectStore::C_DeleteTransaction(t), fin);
     assert(tr == 0);
   } else {
     dout(10) << "recover_replicas not all uptodate, acting " << acting << ", uptodate " << uptodate_set << dendl;
diff --git a/src/streamtest.cc b/src/streamtest.cc
index c3f5b8571f9..d46ffa8af98 100644
--- a/src/streamtest.cc
+++ b/src/streamtest.cc
@@ -144,7 +144,7 @@ int main(int argc, const char **argv)
     set_start(pos, g_clock.now());
     ObjectStore::Transaction *t = new ObjectStore::Transaction;
     t->write(coll_t(), poid, pos, bytes, bl);
-    fs->queue_transaction(t, new C_Ack(pos), new C_Commit(pos));
+    fs->queue_transaction(NULL, t, new C_Ack(pos), new C_Commit(pos));
     pos += bytes;
 
     throttle();