target: Ensure sess_prot_type is saved across session restart

The following incremental patch saves the current sess_prot_type into
se_node_acl, and will always reset sess_prot_type if a previous saved
value exists.  So the PI setting for the fabric's session with backend
devices not supporting PI is persistent across session restart.

(Fix se_node_acl dereference for discovery sessions - DanCarpenter)

Reviewed-by: Martin Petersen <martin.petersen@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 15 insertions, 7 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 4edb183cf8df..14e324991c34 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -328,13 +328,6 @@ void __transport_register_session(
         se_sess->se_tpg = se_tpg;
         se_sess->fabric_sess_ptr = fabric_sess_ptr;
         /*
-         * Determine if fabric allows for T10-PI feature bits to be exposed
-         * to initiators for device backends with !dev->dev_attrib.pi_prot_type
-         */
-        if (tfo->tpg_check_prot_fabric_only)
-                se_sess->sess_prot_type = tfo->tpg_check_prot_fabric_only(se_tpg);
-
-        /*
          * Used by struct se_node_acl's under ConfigFS to locate active se_session-t
          *
          * Only set for struct se_session's that will actually be moving I/O.
@@ -342,6 +335,21 @@ void __transport_register_session(
          */
         if (se_nacl) {
                 /*
+                 *
+                 * Determine if fabric allows for T10-PI feature bits exposed to
+                 * initiators for device backends with !dev->dev_attrib.pi_prot_type.
+                 *
+                 * If so, then always save prot_type on a per se_node_acl node
+                 * basis and re-instate the previous sess_prot_type to avoid
+                 * disabling PI from below any previously initiator side
+                 * registered LUNs.
+                 */
+                if (se_nacl->saved_prot_type)
+                        se_sess->sess_prot_type = se_nacl->saved_prot_type;
+                else if (tfo->tpg_check_prot_fabric_only)
+                        se_sess->sess_prot_type = se_nacl->saved_prot_type =
+                                        tfo->tpg_check_prot_fabric_only(se_tpg);
+                /*
                  * If the fabric module supports an ISID based TransportID,
                  * save this value in binary from the fabric I_T Nexus now.
                  */