Strip leading spaces off of a SCSI disk's serial number

sys/cam/scsi/scsi_xpt.c
	Strip leading spaces off of a SCSI disk's reported serial number
	when populating the CAM serial number. This affects the output of
	"diskinfo -v" and the names of /dev/diskid/DISK-* device nodes,
	among other things.

	SPC5r05 says that the Product Serial Number field from the Unit
	Serial Number VPD page is right-aligned. So any leading spaces are
	not part of the actual serial number. Most devices don't left-pad
	their serial numbers, but some do. In particular, the SN VPD page
	that an LSI HBA emulates for a SATA drive contains enough
	left-padding to fill a 20-byte field.

UPDATING
	Add a note to UPDATING, because some users may have to update
	/etc/fstab or geom labels.

Reviewed by:	ken, mav
MFC after:	Never
Sponsored by:	Spectra Logic Corp
Differential Revision:	https://reviews.freebsd.org/D6516

2 files changed, 25 insertions, 6 deletions

diff --git a/UPDATING b/UPDATING
index df0542d..d28c4b9 100644
--- a/UPDATING
+++ b/UPDATING
@@ -31,6 +31,16 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 11.x IS SLOW:
 	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.
diff --git a/sys/cam/scsi/scsi_xpt.c b/sys/cam/scsi/scsi_xpt.c
index 30a9104..a8684c1 100644
--- a/sys/cam/scsi/scsi_xpt.c
+++ b/sys/cam/scsi/scsi_xpt.c
@@ -1559,13 +1559,22 @@ probe_device_check:
 				(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,