[SCSI] hpsa: fix physical device lun and target numbering problem

If a physical device exposed to the OS by hpsa
is replaced (e.g. one hot plug tape drive is replaced
by another, or a tape drive is placed into "OBDR" mode
in which it acts like a CD-ROM device) and a rescan is
initiated, the replaced device will be added to the
SCSI midlayer with target and lun numbers set to -1.
After that, a panic is likely to ensue.  When a physical
device is replaced, the lun and target number should be
preserved.
Signed-off-by: NStephen M. Cameron <scameron@beardog.cce.hp.com>
Cc: stable@kernel.org
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/hpsa.c

@@ -676,6 +676,16 @@ static void hpsa_scsi_replace_entry(struct ctlr_info *h, int hostno,
 	BUG_ON(entry < 0 || entry >= HPSA_MAX_SCSI_DEVS_PER_HBA);
 	removed[*nremoved] = h->dev[entry];
 	(*nremoved)++;
+
+	/*
+	 * New physical devices won't have target/lun assigned yet
+	 * so we need to preserve the values in the slot we are replacing.
+	 */
+	if (new_entry->target == -1) {
+		new_entry->target = h->dev[entry]->target;
+		new_entry->lun = h->dev[entry]->lun;
+	}
+
 	h->dev[entry] = new_entry;
 	added[*nadded] = new_entry;
 	(*nadded)++;