cciss: add support for multi lun tape devices

This patch adds support for multi-lun devices in a SAS environment. It's
required for the support of media changers.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 37 insertions, 3 deletions

diff --git a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
index c673ff14126a..e1233aabda77 100644
--- a/drivers/block/cciss_scsi.c
+++ b/drivers/block/cciss_scsi.c
@@ -371,16 +371,50 @@ cciss_scsi_add_entry(int ctlr, int hostno,
         /* assumes hba[ctlr]->scsi_ctlr->lock is held */ 
         int n = ccissscsi[ctlr].ndevices;
         struct cciss_scsi_dev_t *sd;
+        int i, bus, target, lun;
+        unsigned char addr1[8], addr2[8];
 
         if (n >= CCISS_MAX_SCSI_DEVS_PER_HBA) {
                 printk("cciss%d: Too many devices, "
                         "some will be inaccessible.\n", ctlr);
                 return -1;
         }
-        sd = &ccissscsi[ctlr].dev[n];
-        if (find_bus_target_lun(ctlr, &sd->bus, &sd->target, &sd->lun) != 0)
-                return -1;
 
+        bus = target = -1;
+        lun = 0;
+        /* Is this device a non-zero lun of a multi-lun device */
+        /* byte 4 of the 8-byte LUN addr will contain the logical unit no. */
+        if (scsi3addr[4] != 0) {
+                /* Search through our list and find the device which */
+                /* has the same 8 byte LUN address, excepting byte 4. */
+                /* Assign the same bus and target for this new LUN. */
+                /* Use the logical unit number from the firmware. */
+                memcpy(addr1, scsi3addr, 8);
+                addr1[4] = 0;
+                for (i = 0; i < n; i++) {
+                        sd = &ccissscsi[ctlr].dev[i];
+                        memcpy(addr2, sd->scsi3addr, 8);
+                        addr2[4] = 0;
+                        /* differ only in byte 4? */
+                        if (memcmp(addr1, addr2, 8) == 0) {
+                                bus = sd->bus;
+                                target = sd->target;
+                                lun = scsi3addr[4];
+                                break;
+                        }
+                }
+        }
+
+        sd = &ccissscsi[ctlr].dev[n];
+        if (lun == 0) {
+                if (find_bus_target_lun(ctlr,
+                        &sd->bus, &sd->target, &sd->lun) != 0)
+                        return -1;
+        } else {
+                sd->bus = bus;
+                sd->target = target;
+                sd->lun = lun;
+        }
         added[*nadded].bus = sd->bus;
         added[*nadded].target = sd->target;
         added[*nadded].lun = sd->lun;