target/iscsi: Allocate session IDs from an IDA

Since the session is never looked up by ID, we can use the more
space-efficient IDA instead of the IDR.

Signed-off-by: Matthew Wilcox <[e-mail]>

drivers/target/iscsi/iscsi_target.c

···
 static DEFINE_MUTEX(np_lock);
 
 static struct idr tiqn_idr;
-struct idr sess_idr;
+DEFINE_IDA(sess_ida);
 struct mutex auth_id_lock;
-spinlock_t sess_idr_lock;
 
 struct iscsit_global *iscsit_global;
 
···
 
 	spin_lock_init(&iscsit_global->ts_bitmap_lock);
 	mutex_init(&auth_id_lock);
-	spin_lock_init(&sess_idr_lock);
 	idr_init(&tiqn_idr);
-	idr_init(&sess_idr);
 
 	ret = target_register_template(&iscsi_ops);
 	if (ret)
···
 	pr_debug("Decremented number of active iSCSI Sessions on"
 		" iSCSI TPG: %hu to %u\n", tpg->tpgt, tpg->nsessions);
 
-	spin_lock(&sess_idr_lock);
-	idr_remove(&sess_idr, sess->session_index);
-	spin_unlock(&sess_idr_lock);
-
+	ida_free(&sess_ida, sess->session_index);
 	kfree(sess->sess_ops);
 	sess->sess_ops = NULL;
 	spin_unlock_bh(&se_tpg->session_lock);

drivers/target/iscsi/iscsi_target.h

···
 extern struct kmem_cache *lio_qr_cache;
 extern struct kmem_cache *lio_r2t_cache;
 
-extern struct idr sess_idr;
+extern struct ida sess_ida;
 extern struct mutex auth_id_lock;
-extern spinlock_t sess_idr_lock;
-
 
 #endif   /*** ISCSI_TARGET_H ***/

drivers/target/iscsi/iscsi_target_login.c

···
 	timer_setup(&sess->time2retain_timer,
 		    iscsit_handle_time2retain_timeout, 0);
 
-	idr_preload(GFP_KERNEL);
-	spin_lock_bh(&sess_idr_lock);
-	ret = idr_alloc(&sess_idr, NULL, 0, 0, GFP_NOWAIT);
-	if (ret >= 0)
-		sess->session_index = ret;
-	spin_unlock_bh(&sess_idr_lock);
-	idr_preload_end();
-
+	ret = ida_alloc(&sess_ida, GFP_KERNEL);
 	if (ret < 0) {
-		pr_err("idr_alloc() for sess_idr failed\n");
+		pr_err("Session ID allocation failed %d\n", ret);
 		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
 				ISCSI_LOGIN_STATUS_NO_RESOURCES);
 		goto free_sess;
 	}
 
+	sess->session_index = ret;
 	sess->creation_time = get_jiffies_64();
 	/*
 	 * The FFP CmdSN window values will be allocated from the TPG's
···
 				ISCSI_LOGIN_STATUS_NO_RESOURCES);
 		pr_err("Unable to allocate memory for"
 				" struct iscsi_sess_ops.\n");
-		goto remove_idr;
+		goto free_id;
 	}
 
 	sess->se_sess = transport_init_session(TARGET_PROT_NORMAL);
···
 
 free_ops:
 	kfree(sess->sess_ops);
-remove_idr:
-	spin_lock_bh(&sess_idr_lock);
-	idr_remove(&sess_idr, sess->session_index);
-	spin_unlock_bh(&sess_idr_lock);
+free_id:
+	ida_free(&sess_ida, sess->session_index);
 free_sess:
 	kfree(sess);
 	conn->sess = NULL;
···
 		goto old_sess_out;
 
 	transport_free_session(conn->sess->se_sess);
-
-	spin_lock_bh(&sess_idr_lock);
-	idr_remove(&sess_idr, conn->sess->session_index);
-	spin_unlock_bh(&sess_idr_lock);
-
+	ida_free(&sess_ida, conn->sess->session_index);
 	kfree(conn->sess->sess_ops);
 	kfree(conn->sess);
 	conn->sess = NULL;