diff --git a/ceph/config.cc b/ceph/config.cc
index dc14b8c709d..4f856c2d75f 100644
--- a/ceph/config.cc
+++ b/ceph/config.cc
@@ -156,6 +156,7 @@ md_config_t g_conf = {
   bdev_el_bw_max_ms: 300,       // restart elevator at least once every 300 ms
   bdev_el_bidir: true,          // bidirectional elevator?
   bdev_iov_max: 512,            // max # iov's to collect into a single readv()/writev() call
+  bdev_debug_check_io_overlap: true,   // [DEBUG] check for any pending io overlaps
 
   // --- fakeclient (mds regression testing) (ancient history) ---
   num_fakeclient: 100,
diff --git a/ceph/config.h b/ceph/config.h
index 35240ba28ed..aaffdd806ef 100644
--- a/ceph/config.h
+++ b/ceph/config.h
@@ -129,6 +129,7 @@ struct md_config_t {
   int   bdev_el_bw_max_ms;
   bool  bdev_el_bidir;
   int   bdev_iov_max;
+  bool  bdev_debug_check_io_overlap;
 
   // fake client
   int      num_fakeclient;
diff --git a/ceph/ebofs/BlockDevice.cc b/ceph/ebofs/BlockDevice.cc
index 2d26b8cdc11..1e6834473ab 100644
--- a/ceph/ebofs/BlockDevice.cc
+++ b/ceph/ebofs/BlockDevice.cc
@@ -382,7 +382,7 @@ void BlockDevice::_submit_io(biovec *b)
 	io_wakeup.SignalAll();
 
   // [DEBUG] check for overlapping ios
-  if (0) {
+  if (g_conf.bdev_debug_check_io_overlap) {
 	// BUG: this doesn't catch everything!  eg 1~10000000 will be missed....
 	multimap<block_t, biovec*>::iterator p = io_queue.lower_bound(b->start);
 	if ((p != io_queue.end() &&
diff --git a/ceph/osd/FakeStore.cc b/ceph/osd/FakeStore.cc
index d6422966ebf..f7fc256e8fc 100644
--- a/ceph/osd/FakeStore.cc
+++ b/ceph/osd/FakeStore.cc
@@ -2,6 +2,7 @@
 #include "FakeStore.h"
 #include "include/types.h"
 
+#include "common/Timer.h"
 
 #include <unistd.h>
 #include <stdlib.h>
diff --git a/ceph/osd/OSDMap.h b/ceph/osd/OSDMap.h
index dab80c6ca1d..97c5166a9fd 100644
--- a/ceph/osd/OSDMap.h
+++ b/ceph/osd/OSDMap.h
@@ -88,7 +88,7 @@ class OSDMap {
   // oid -> ps
   ps_t object_to_ps(object_t oid) {
 	static crush::Hash H(777);
-	return H( (oid & 0xffffffffUL) ^ (oid >> 32) ) & PG_PS_MASK;
+	return H( oid ^ (oid >> 32) ) & PG_PS_MASK;
   }
 
   // (ps, nrep) -> pg
@@ -112,8 +112,9 @@ class OSDMap {
   int pg_to_osds(pg_t pg,
 				 vector<int>& osds) {       // list of osd addr's
 	int num_rep = pg_to_nrep(pg);
+	pg_t ps = pg_to_ps(pg);
 	crush.do_rule(crush.rules[num_rep],
-				  (pg & 0xffffffff) ^ (pg >> 32),
+				  ps ^ (ps >> 32),
 				  osds);
 	return osds.size();
   }