[SCSI] fix check of PQ and PDT bits for WLUNs

For IBM z series certain LUNs can no longer be accessed.

This is because kernel version 2.6.19 a check was introduced not to
create a generic SCSI device for devices that return PQ=1 and
PDT=0x1f. For WLUNs (see SAM-3, p. 41ff) generic SCSI devices should
be created unconditionally without looking at the PQ bit, so add a
check for WLUNs in with this test.

Acked-by: Martin Petermann <martin@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

include/scsi/scsi.h

@@ -308,6 +308,20 @@ struct scsi_lun {
 	__u8 scsi_lun[8];
 };
 
+/*
+ * The Well Known LUNS (SAM-3) in our int representation of a LUN
+ */
+#define SCSI_W_LUN_BASE 0xc100
+#define SCSI_W_LUN_REPORT_LUNS (SCSI_W_LUN_BASE + 1)
+#define SCSI_W_LUN_ACCESS_CONTROL (SCSI_W_LUN_BASE + 2)
+#define SCSI_W_LUN_TARGET_LOG_PAGE (SCSI_W_LUN_BASE + 3)
+
+static inline int scsi_is_wlun(unsigned int lun)
+{
+	return (lun & 0xff00) == SCSI_W_LUN_BASE;
+}
+
+
 /*
  *  MESSAGE CODES
  */