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 <[e-mail]>
Cc: Sagi Grimberg <[e-mail]>
Cc: Or Gerlitz <[e-mail]>
Cc: Quinn Tran <[e-mail]>
Cc: Giridhar Malavali <[e-mail]>
Signed-off-by: Nicholas Bellinger <[e-mail]>

drivers/infiniband/ulp/isert/ib_isert.c

···
 	device->unreg_rdma_mem(isert_cmd, isert_conn);
 }
 
+static enum target_prot_op
+isert_get_sup_prot_ops(struct iscsi_conn *conn)
+{
+	struct isert_conn *isert_conn = (struct isert_conn *)conn->context;
+	struct isert_device *device = isert_conn->conn_device;
+
+	if (device->pi_capable)
+		return TARGET_PROT_ALL;
+
+	return TARGET_PROT_NORMAL;
+}
+
 static int
 isert_put_nopin(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 		bool nopout_response)
···
 	.iscsit_queue_data_in	= isert_put_datain,
 	.iscsit_queue_status	= isert_put_response,
 	.iscsit_aborted_task	= isert_aborted_task,
+	.iscsit_get_sup_prot_ops = isert_get_sup_prot_ops,
 };
 
 static int __init isert_init(void)

drivers/infiniband/ulp/srpt/ib_srpt.c

···
 		goto destroy_ib;
 	}
 
-	ch->sess = transport_init_session();
+	ch->sess = transport_init_session(TARGET_PROT_NORMAL);
 	if (IS_ERR(ch->sess)) {
 		rej->reason = __constant_cpu_to_be32(
 				SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);

drivers/scsi/qla2xxx/tcm_qla2xxx.c

···
 	}
 	se_tpg = &tpg->se_tpg;
 
-	se_sess = transport_init_session();
+	se_sess = transport_init_session(TARGET_PROT_NORMAL);
 	if (IS_ERR(se_sess)) {
 		pr_err("Unable to initialize struct se_session\n");
 		return PTR_ERR(se_sess);

drivers/target/iscsi/iscsi_target.c

···
 	__iscsit_free_cmd(cmd, scsi_cmd, true);
 }
 
+static enum target_prot_op iscsit_get_sup_prot_ops(struct iscsi_conn *conn)
+{
+	return TARGET_PROT_NORMAL;
+}
+
 static struct iscsit_transport iscsi_target_transport = {
 	.name			= "iSCSI/TCP",
 	.transport_type		= ISCSI_TCP,
···
 	.iscsit_queue_data_in	= iscsit_queue_rsp,
 	.iscsit_queue_status	= iscsit_queue_rsp,
 	.iscsit_aborted_task	= iscsit_aborted_task,
+	.iscsit_get_sup_prot_ops = iscsit_get_sup_prot_ops,
 };
 
 static int __init iscsi_target_init_module(void)

drivers/target/iscsi/iscsi_target_login.c

···
 {
 	struct iscsi_session *sess = NULL;
 	struct iscsi_login_req *pdu = (struct iscsi_login_req *)buf;
+	enum target_prot_op sup_pro_ops;
 	int ret;
 
 	sess = kzalloc(sizeof(struct iscsi_session), GFP_KERNEL);
···
 		kfree(sess);
 		return -ENOMEM;
 	}
+	sup_pro_ops = conn->conn_transport->iscsit_get_sup_prot_ops(conn);
 
-	sess->se_sess = transport_init_session();
+	sess->se_sess = transport_init_session(sup_pro_ops);
 	if (IS_ERR(sess->se_sess)) {
 		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
 				ISCSI_LOGIN_STATUS_NO_RESOURCES);

drivers/target/loopback/tcm_loop.c

···
 	/*
 	 * Initialize the struct se_session pointer
 	 */
-	tl_nexus->se_sess = transport_init_session();
+	tl_nexus->se_sess = transport_init_session(TARGET_PROT_ALL);
 	if (IS_ERR(tl_nexus->se_sess)) {
 		ret = PTR_ERR(tl_nexus->se_sess);
 		goto out;

drivers/target/sbp/sbp_target.c

···
 		return ERR_PTR(-ENOMEM);
 	}
 
-	sess->se_sess = transport_init_session();
+	sess->se_sess = transport_init_session(TARGET_PROT_NORMAL);
 	if (IS_ERR(sess->se_sess)) {
 		pr_err("failed to init se_session\n");
 

drivers/target/target_core_transport.c

···
 	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;
 
···
 	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;
 }
···
 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;
 

drivers/target/tcm_fc/tfc_sess.c

···
 		return NULL;
 
 	sess->se_sess = transport_init_session_tags(TCM_FC_DEFAULT_TAGS,
-						    sizeof(struct ft_cmd));
+						    sizeof(struct ft_cmd),
+						    TARGET_PROT_NORMAL);
 	if (IS_ERR(sess->se_sess)) {
 		kfree(sess);
 		return NULL;

drivers/usb/gadget/tcm_usb_gadget.c

···
 		pr_err("Unable to allocate struct tcm_vhost_nexus\n");
 		goto err_unlock;
 	}
-	tv_nexus->tvn_se_sess = transport_init_session();
+	tv_nexus->tvn_se_sess = transport_init_session(TARGET_PROT_NORMAL);
 	if (IS_ERR(tv_nexus->tvn_se_sess))
 		goto err_free;
 

drivers/vhost/scsi.c

···
 	 */
 	tv_nexus->tvn_se_sess = transport_init_session_tags(
 					TCM_VHOST_DEFAULT_TAGS,
-					sizeof(struct tcm_vhost_cmd));
+					sizeof(struct tcm_vhost_cmd),
+					TARGET_PROT_NORMAL);
 	if (IS_ERR(tv_nexus->tvn_se_sess)) {
 		mutex_unlock(&tpg->tv_tpg_mutex);
 		kfree(tv_nexus);

include/target/iscsi/iscsi_transport.h

···
 	int (*iscsit_queue_data_in)(struct iscsi_conn *, struct iscsi_cmd *);
 	int (*iscsit_queue_status)(struct iscsi_conn *, struct iscsi_cmd *);
 	void (*iscsit_aborted_task)(struct iscsi_conn *, struct iscsi_cmd *);
+	enum target_prot_op (*iscsit_get_sup_prot_ops)(struct iscsi_conn *);
 };
 
 static inline void *iscsit_priv_cmd(struct iscsi_cmd *cmd)

include/target/target_core_base.h

···
 };
 
 enum target_prot_op {
-	TARGET_PROT_NORMAL = 0,
-	TARGET_PROT_DIN_INSERT,
-	TARGET_PROT_DOUT_INSERT,
-	TARGET_PROT_DIN_STRIP,
-	TARGET_PROT_DOUT_STRIP,
-	TARGET_PROT_DIN_PASS,
-	TARGET_PROT_DOUT_PASS,
+	TARGET_PROT_NORMAL	= 0,
+	TARGET_PROT_DIN_INSERT	= (1 << 0),
+	TARGET_PROT_DOUT_INSERT	= (1 << 1),
+	TARGET_PROT_DIN_STRIP	= (1 << 2),
+	TARGET_PROT_DOUT_STRIP	= (1 << 3),
+	TARGET_PROT_DIN_PASS	= (1 << 4),
+	TARGET_PROT_DOUT_PASS	= (1 << 5),
 };
+
+#define TARGET_PROT_ALL	TARGET_PROT_DIN_INSERT | TARGET_PROT_DOUT_INSERT | \
+			TARGET_PROT_DIN_STRIP | TARGET_PROT_DOUT_STRIP | \
+			TARGET_PROT_DIN_PASS | TARGET_PROT_DOUT_PASS
 
 enum target_prot_type {
 	TARGET_DIF_TYPE0_PROT,
···
 struct se_session {
 	unsigned		sess_tearing_down:1;
 	u64			sess_bin_isid;
+	enum target_prot_op	sup_prot_ops;
 	struct se_node_acl	*se_node_acl;
 	struct se_portal_group *se_tpg;
 	void			*fabric_sess_ptr;

include/target/target_core_fabric.h

···
 	void (*fabric_drop_nodeacl)(struct se_node_acl *);
 };
 
-struct se_session *transport_init_session(void);
+struct se_session *transport_init_session(enum target_prot_op);
 int transport_alloc_session_tags(struct se_session *, unsigned int,
 		unsigned int);
-struct se_session *transport_init_session_tags(unsigned int, unsigned int);
+struct se_session *transport_init_session_tags(unsigned int, unsigned int,
+		enum target_prot_op);
 void	__transport_register_session(struct se_portal_group *,
 		struct se_node_acl *, struct se_session *, void *);
 void	transport_register_session(struct se_portal_group *,