iscsi-target: Disable Immediate + Unsolicited Data with ISER Protection

This patch explicitly disables Immediate + Unsolicited Data for ISER
connections during login in iscsi_login_zero_tsih_s2() when protection
has been enabled for the session by the underlying hardware.

This is currently required because protection / signature memory regions
(MRs) expect T10 PI to occur on RDMA READs + RDMA WRITEs transfers, and
not on a immediate data payload associated with ISCSI_OP_SCSI_CMD, or
unsolicited data-out associated with a ISCSI_OP_SCSI_DATA_OUT.

v2 changes:
  - Add TARGET_PROT_DOUT_INSERT check (Sagi)
  - Add pr_debug noisemaker (Sagi)
  - Add goto to avoid early return from MRDSL check (nab)

Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_login.c

@@ -436,7 +436,7 @@ static int iscsi_login_zero_tsih_s2(
 		}
 		off = mrdsl % PAGE_SIZE;
 		if (!off)
-			return 0;
+			goto check_prot;
 
 		if (mrdsl < PAGE_SIZE)
 			mrdsl = PAGE_SIZE;
@@ -452,6 +452,31 @@ static int iscsi_login_zero_tsih_s2(
 				ISCSI_LOGIN_STATUS_NO_RESOURCES);
 			return -1;
 		}
+		/*
+		 * ISER currently requires that ImmediateData + Unsolicited
+		 * Data be disabled when protection / signature MRs are enabled.
+		 */
+check_prot:
+		if (sess->se_sess->sup_prot_ops &
+		   (TARGET_PROT_DOUT_STRIP | TARGET_PROT_DOUT_PASS |
+		    TARGET_PROT_DOUT_INSERT)) {
+
+			sprintf(buf, "ImmediateData=No");
+			if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
+				iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
+						    ISCSI_LOGIN_STATUS_NO_RESOURCES);
+				return -1;
+			}
+
+			sprintf(buf, "InitialR2T=Yes");
+			if (iscsi_change_param_value(buf, conn->param_list, 0) < 0) {
+				iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
+						    ISCSI_LOGIN_STATUS_NO_RESOURCES);
+				return -1;
+			}
+			pr_debug("Forcing ImmediateData=No + InitialR2T=Yes for"
+				 " T10-PI enabled ISER session\n");
+		}
 	}
 
 	return 0;