target: Pass in transport supported PI at session initialization

In order to support local WRITE_INSERT + READ_STRIP operations for
non PI enabled fabrics, the fabric driver needs to be able signal
what protection offload operations are supported.

This is done at session initialization time so the modes can be
signaled by individual se_wwn + se_portal_group endpoints, as well
as optionally across different transports on the same endpoint.

For iser-target, set TARGET_PROT_ALL if the underlying ib_device
has already signaled PI offload support, and allow this to be
exposed via a new iscsit_transport->iscsit_get_sup_prot_ops()
callback.

For loopback, set TARGET_PROT_ALL to signal SCSI initiator mode
operation.

For all other drivers, set TARGET_PROT_NORMAL to disable fabric
level PI.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Quinn Tran <quinn.tran@qlogic.com>
Cc: Giridhar Malavali <giridhar.malavali@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 9393544..9c820ba 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -235,7 +235,7 @@
 	sub_api_initialized = 1;
 }
 
-struct se_session *transport_init_session(void)
+struct se_session *transport_init_session(enum target_prot_op sup_prot_ops)
 {
 	struct se_session *se_sess;
 
@@ -251,6 +251,7 @@
 	INIT_LIST_HEAD(&se_sess->sess_wait_list);
 	spin_lock_init(&se_sess->sess_cmd_lock);
 	kref_init(&se_sess->sess_kref);
+	se_sess->sup_prot_ops = sup_prot_ops;
 
 	return se_sess;
 }
@@ -288,12 +289,13 @@
 EXPORT_SYMBOL(transport_alloc_session_tags);
 
 struct se_session *transport_init_session_tags(unsigned int tag_num,
-					       unsigned int tag_size)
+					       unsigned int tag_size,
+					       enum target_prot_op sup_prot_ops)
 {
 	struct se_session *se_sess;
 	int rc;
 
-	se_sess = transport_init_session();
+	se_sess = transport_init_session(sup_prot_ops);
 	if (IS_ERR(se_sess))
 		return se_sess;