target: Make standard INQUIRY return 'not connected' for tpg_virt_lun0

This patch changes target_emulate_inquiry_std() to set the 'not connected'
(0x35) bit in standard INQUIRY response data when we are processing a
request to a virtual LUN=0 mapping from struct se_device *g_lun0_dev that
have been setup for us in transport_lookup_cmd_lun().

This addresses an issue where qla2xxx FC clients need to be able
to create demo-mode I_T FC Nexuses by default, but should not be
exposing the default set of TPG LUNs to all FC clients.  This includes
adding an new optional target_core_fabric_ops->tpg_check_demo_mode_login_only()
caller to allow demo_mode nexuses to skip the old default of bulding
a demo-mode MappedLUNs list via core_tpg_add_node_to_devs().

(roland: Add missing tpg_check_demo_mode_login_only check in core_dev_add_lun)

Reported-by: Roland Dreier <roland@purestorage.com>
Cc: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@risingtidesystems.com>

3 files changed, 21 insertions, 6 deletions

diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index 8ae09a1bdf74..d095408dbd5f 100644
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -67,6 +67,7 @@ target_emulate_inquiry_std(struct se_cmd *cmd)
 {
         struct se_lun *lun = cmd->se_lun;
         struct se_device *dev = cmd->se_dev;
+        struct se_portal_group *tpg = lun->lun_sep->sep_tpg;
         unsigned char *buf;
 
         /*
@@ -81,9 +82,13 @@ target_emulate_inquiry_std(struct se_cmd *cmd)
 
         buf = transport_kmap_first_data_page(cmd);
 
-        buf[0] = dev->transport->get_device_type(dev);
-        if (buf[0] == TYPE_TAPE)
-                buf[1] = 0x80;
+        if (dev == tpg->tpg_virt_lun0.lun_se_dev) {
+                buf[0] = 0x3f; /* Not connected */
+        } else {
+                buf[0] = dev->transport->get_device_type(dev);
+                if (buf[0] == TYPE_TAPE)
+                        buf[1] = 0x80;
+        }
         buf[2] = dev->transport->get_device_rev(dev);
 
         /*
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index b38b6c993e65..ec3fbcda3e3c 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1346,7 +1346,9 @@ struct se_lun *core_dev_add_lun(
                 struct se_node_acl *acl;
                 spin_lock_bh(&tpg->acl_node_lock);
                 list_for_each_entry(acl, &tpg->acl_node_list, acl_list) {
-                        if (acl->dynamic_node_acl) {
+                        if (acl->dynamic_node_acl &&
+                            (!tpg->se_tpg_tfo->tpg_check_demo_mode_login_only ||
+                             !tpg->se_tpg_tfo->tpg_check_demo_mode_login_only(tpg))) {
                                 spin_unlock_bh(&tpg->acl_node_lock);
                                 core_tpg_add_node_to_devs(acl, tpg);
                                 spin_lock_bh(&tpg->acl_node_lock);
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 4f1ba4c5ef11..718ccd1348b1 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -298,8 +298,16 @@ struct se_node_acl *core_tpg_check_initiator_node_acl(
                 tpg->se_tpg_tfo->tpg_release_fabric_acl(tpg, acl);
                 return NULL;
         }
-
-        core_tpg_add_node_to_devs(acl, tpg);
+        /*
+         * Here we only create demo-mode MappedLUNs from the active
+         * TPG LUNs if the fabric is not explictly asking for
+         * tpg_check_demo_mode_login_only() == 1.
+         */
+        if ((tpg->se_tpg_tfo->tpg_check_demo_mode_login_only != NULL) &&
+            (tpg->se_tpg_tfo->tpg_check_demo_mode_login_only(tpg) == 1))
+                do { ; } while (0);
+        else
+                core_tpg_add_node_to_devs(acl, tpg);
 
         spin_lock_bh(&tpg->acl_node_lock);
         list_add_tail(&acl->acl_list, &tpg->acl_node_list);