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>

1 files changed, 10 insertions, 2 deletions

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);