diff --git a/PendingReleaseNotes b/PendingReleaseNotes
index 5e4b99f4b14f1..5b08cd761be68 100644
--- a/PendingReleaseNotes
+++ b/PendingReleaseNotes
@@ -24,3 +24,9 @@ v0.65
 
     ceph osd crush add osd.123 <weight> <location ...>
     ceph osd crush add 123 <weight> <location ...>
+
+* There is now a maximum RADOS object size, configurable via 'osd max
+  object size', defaulting to 100 GB.  Note that this has no effect on
+  RBD, CephFS, or radosgw, which all stripe over objects.
+
+ 
\ No newline at end of file
diff --git a/src/common/config_opts.h b/src/common/config_opts.h
index 8a02dd5c98eca..094d12401c5cd 100644
--- a/src/common/config_opts.h
+++ b/src/common/config_opts.h
@@ -485,6 +485,8 @@ OPTION(osd_recovery_op_priority, OPT_INT, 10)
 // Max time to wait between notifying mon of shutdown and shutting down
 OPTION(osd_mon_shutdown_timeout, OPT_DOUBLE, 5)
 
+OPTION(osd_max_object_size, OPT_U64, 100*1024L*1024L*1024L) // OSD's maximum object size
+
 OPTION(filestore, OPT_BOOL, false)
 
 /// filestore wb throttle limits
diff --git a/src/osd/ReplicatedPG.cc b/src/osd/ReplicatedPG.cc
index 60e0c889932e8..5f4aa6a05257f 100644
--- a/src/osd/ReplicatedPG.cc
+++ b/src/osd/ReplicatedPG.cc
@@ -1953,6 +1953,19 @@ int ReplicatedPG::do_tmapup(OpContext *ctx, bufferlist::iterator& bp, OSDOp& osd
   return result;
 }
 
+static int check_offset_and_length(__le64 offset, __le64 length)
+{
+  if (length < 1)
+    return -EINVAL;
+
+  if (offset >= g_conf->osd_max_object_size ||
+      length > g_conf->osd_max_object_size ||
+      offset + length > g_conf->osd_max_object_size)
+    return -EFBIG;
+
+  return 0;
+}
+
 int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
 {
   int result = 0;
@@ -2005,7 +2018,14 @@ int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
     // munge ZERO -> TRUNCATE?  (don't munge to DELETE or we risk hosing attributes)
     if (op.op == CEPH_OSD_OP_ZERO &&
 	obs.exists &&
+	op.extent.offset < g_conf->osd_max_object_size &&
+	op.extent.length >= 1 &&
+	op.extent.length <= g_conf->osd_max_object_size &&
 	op.extent.offset + op.extent.length >= oi.size) {
+      if (op.extent.offset >= oi.size) {
+        // no-op
+	goto fail;
+      }
       dout(10) << " munging ZERO " << op.extent.offset << "~" << op.extent.length
 	       << " -> TRUNCATE " << op.extent.offset << " (old size is " << oi.size << ")" << dendl;
       op.op = CEPH_OSD_OP_TRUNCATE;
@@ -2517,6 +2537,9 @@ int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
 	    oi.truncate_size = op.extent.truncate_size;
 	  }
 	}
+	result = check_offset_and_length(op.extent.offset, op.extent.length);
+	if (result < 0)
+	  break;
 	bufferlist nbl;
 	bp.copy(op.extent.length, nbl);
 	t.write(coll, soid, op.extent.offset, op.extent.length, nbl);
@@ -2531,6 +2554,9 @@ int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
       
     case CEPH_OSD_OP_WRITEFULL:
       { // write full object
+	result = check_offset_and_length(op.extent.offset, op.extent.length);
+	if (result < 0)
+	  break;
 	bufferlist nbl;
 	bp.copy(op.extent.length, nbl);
 	if (obs.exists) {
@@ -2560,6 +2586,9 @@ int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
 
     case CEPH_OSD_OP_ZERO:
       { // zero
+	result = check_offset_and_length(op.extent.offset, op.extent.length);
+	if (result < 0)
+	  break;
 	assert(op.extent.length);
 	if (obs.exists) {
 	  t.zero(coll, soid, op.extent.offset, op.extent.length);
@@ -2618,6 +2647,11 @@ int ReplicatedPG::do_osd_ops(OpContext *ctx, vector<OSDOp>& ops)
 	  break;
 	}
 
+	if (op.extent.offset > g_conf->osd_max_object_size) {
+	  result = -EFBIG;
+	  break;
+	}
+
 	if (op.extent.truncate_seq) {
 	  assert(op.extent.offset == op.extent.truncate_size);
 	  if (op.extent.truncate_seq <= oi.truncate_seq) {