A patch for Linux LIO iSCSI target to restrict the maximum number of sessions (not connections).

lio.patch

--- linux-3.2.0/drivers/target/iscsi/iscsi_target_login.c       2012-06-07 05:37:34.000000000 +0000
+++ iscsi_target_login.c        2012-06-07 05:34:22.866487169 +0000
@@ -1107,6 +1107,20 @@
                goto new_sess_out;
        }
 
+       /* Cybozu */
+       if (zero_tsih) {
+               int error = 0;
+               spin_lock_bh(&np->np_thread_lock);
+               if( tpg->nsessions > 0 )
+                       error = 1;
+               spin_unlock_bh(&np->np_thread_lock);
+
+               if( error ) {
+                       pr_err("Detected possible split brain\n");
+                       goto new_sess_out;
+               }
+       }
+
        if (zero_tsih) {
                if (iscsi_login_zero_tsih_s2(conn) < 0) {
                        iscsi_target_nego_release(login, conn);