Index: head/sys/cam/cam_xpt.c
===================================================================
--- head/sys/cam/cam_xpt.c
+++ head/sys/cam/cam_xpt.c
@@ -414,6 +414,10 @@
 		struct cam_eb *bus;
 
 		inccb = (union ccb *)addr;
+#if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
+		if (inccb->ccb_h.func_code == XPT_SCSI_IO)
+			inccb->csio.bio = NULL;
+#endif
 
 		bus = xpt_find_bus(inccb->ccb_h.path_id);
 		if (bus == NULL)
@@ -593,6 +597,10 @@
 		unit = ccb->cgdl.unit_number;
 		name = ccb->cgdl.periph_name;
 		base_periph_found = 0;
+#if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
+		if (ccb->ccb_h.func_code == XPT_SCSI_IO)
+			ccb->csio.bio = NULL;
+#endif
 
 		/*
 		 * Sanity check -- make sure we don't get a null peripheral
Index: head/sys/cam/scsi/scsi_pass.c
===================================================================
--- head/sys/cam/scsi/scsi_pass.c
+++ head/sys/cam/scsi/scsi_pass.c
@@ -1777,6 +1777,10 @@
 		int ccb_malloced;
 
 		inccb = (union ccb *)addr;
+#if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
+		if (inccb->ccb_h.func_code == XPT_SCSI_IO)
+			inccb->csio.bio = NULL;
+#endif
 
 		/*
 		 * Some CCB types, like scan bus and scan lun can only go
@@ -1875,6 +1879,10 @@
 			cam_periph_lock(periph);
 			break;
 		}
+#if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING)
+		if (ccb->ccb_h.func_code == XPT_SCSI_IO)
+			ccb->csio.bio = NULL;
+#endif
 
 		if (ccb->ccb_h.flags & CAM_CDB_POINTER) {
 			if (ccb->csio.cdb_len > IOCDBLEN) {