Index: head/UPDATING
===================================================================
--- head/UPDATING
+++ head/UPDATING
@@ -31,6 +31,16 @@
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20160527:
+	CAM will now strip leading spaces from SCSI disks' serial numbers.
+	This will effect users who create UFS filesystems on SCSI disks using
+	those disk's diskid device nodes.  For example, if /etc/fstab
+	previously contained a line like
+	"/dev/diskid/DISK-%20%20%20%20%20%20%20ABCDEFG0123456", you should
+	change it to "/dev/diskid/DISK-ABCDEFG0123456".  Users of geom
+	transfers like gmirror may also be affected.  ZFS users should
+	generally be fine.
+
 20160523:
 	The bitstring(3) API has been updated with new functionality and
 	improved performance.  But it is binary-incompatible with the old API.
Index: head/sys/cam/scsi/scsi_xpt.c
===================================================================
--- head/sys/cam/scsi/scsi_xpt.c
+++ head/sys/cam/scsi/scsi_xpt.c
@@ -1559,13 +1559,22 @@
 				(u_int8_t *)malloc((serial_buf->length + 1),
 						   M_CAMXPT, M_NOWAIT);
 			if (path->device->serial_num != NULL) {
+				int start, slen;
+
+				start = strspn(serial_buf->serial_num, " ");
+				slen = serial_buf->length - start;
+				if (slen <= 0) {
+					/* 
+					 * SPC5r05 says that an all-space serial
+					 * number means no product serial number
+					 * is available
+					 */
+					slen = 0;
+				}
 				memcpy(path->device->serial_num,
-				       serial_buf->serial_num,
-				       serial_buf->length);
-				path->device->serial_num_len =
-				    serial_buf->length;
-				path->device->serial_num[serial_buf->length]
-				    = '\0';
+				       &serial_buf->serial_num[start], slen);
+				path->device->serial_num_len = slen;
+				path->device->serial_num[slen] = '\0';
 			}
 		} else if (cam_periph_error(done_ccb, 0,
 					    SF_RETRY_UA|SF_NO_PRINT,