iscsi-target: Fix non-immediate TMR handling

This patch addresses two issues with non immediate TMR handling in
iscsit_handle_task_mgt_cmd().  The first involves breakage due to
v3.1-rc conversion of iscsit_sequence_cmd(), which upon good status
would hit the iscsit_add_reject_from_cmd() block of code.  This patch
adds an explict check for CMDSN_ERROR_CANNOT_RECOVER.

The second adds a check to return when non immediate TMR operation is
detected after iscsit_ack_from_expstatsn(), as iscsit_sequence_cmd()
-> iscsit_execute_cmd() will have called transport_generic_handle_tmr()
for the non immediate TMR case already.

Cc: Andy Grover <agrover@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -1821,17 +1821,16 @@ attach:
 		int cmdsn_ret = iscsit_sequence_cmd(conn, cmd, hdr->cmdsn);
 		if (cmdsn_ret == CMDSN_HIGHER_THAN_EXP)
 			out_of_order_cmdsn = 1;
-		else if (cmdsn_ret == CMDSN_LOWER_THAN_EXP) {
+		else if (cmdsn_ret == CMDSN_LOWER_THAN_EXP)
 			return 0;
-		} else { /* (cmdsn_ret == CMDSN_ERROR_CANNOT_RECOVER) */
+		else if (cmdsn_ret == CMDSN_ERROR_CANNOT_RECOVER)
 			return iscsit_add_reject_from_cmd(
 					ISCSI_REASON_PROTOCOL_ERROR,
 					1, 0, buf, cmd);
-		}
 	}
 	iscsit_ack_from_expstatsn(conn, hdr->exp_statsn);
 
-	if (out_of_order_cmdsn)
+	if (out_of_order_cmdsn || !(hdr->opcode & ISCSI_OP_IMMEDIATE))
 		return 0;
 	/*
 	 * Found the referenced task, send to transport for processing.