[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>

2 files changed, 16 insertions, 1 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 84b4879cff11..34d0de6cd511 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1080,7 +1080,8 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
          * PDT=1Fh none (no FDD connected to the requested logical unit)
          */
         if (((result[0] >> 5) == 1 || starget->pdt_1f_for_no_lun) &&
-             (result[0] & 0x1f) == 0x1f) {
+            (result[0] & 0x1f) == 0x1f &&
+            !scsi_is_wlun(lun)) {
                 SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
                                         "scsi scan: peripheral device type"
                                         " of 31, no device added\n"));
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 5c40cc537d4c..192f8716aa9e 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -309,6 +309,20 @@ struct scsi_lun {
 };
 
 /*
+ * 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
  */