From 04b7e9da288256072db0882ce74e51a51fc207d3 Mon Sep 17 00:00:00 2001
From: thantry <thantry>
Date: Thu, 5 Sep 2002 21:20:50 +0000
Subject: [PATCH] Re-added lock(s) as library

---
 lustre/lib/l_lock.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 lustre/lib/l_lock.c

diff --git a/lustre/lib/l_lock.c b/lustre/lib/l_lock.c
new file mode 100644
index 0000000..db072e0
--- /dev/null
+++ b/lustre/lib/l_lock.c
@@ -0,0 +1,96 @@
+/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
+ * vim:expandtab:shiftwidth=8:tabstop=8:
+ *
+ * Copyright (C) 2001, 2002 Cluster File Systems, Inc.
+ *
+ *   This file is part of Lustre, http://www.sf.net/projects/lustre/
+ *
+ *   Lustre is free software; you can redistribute it and/or
+ *   modify it under the terms of version 2 of the GNU General Public
+ *   License as published by the Free Software Foundation.
+ *
+ *   Lustre is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with Lustre; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/locks.h>
+#include <linux/unistd.h>
+#include <linux/version.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <asm/uaccess.h>
+#include <asm/segment.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/smp_lock.h>
+
+#define DEBUG_SUBSYSTEM S_LDLM
+
+#include <linux/obd_class.h>
+#include <linux/lustre_lib.h>
+
+/* invariants:
+ - only the owner of the lock changes l_owner/l_depth
+ - if a non-owner changes or checks the variables a spin lock is taken
+*/
+
+void l_lock_init(struct lustre_lock *lock)
+{
+        sema_init(&lock->l_sem, 1);
+        spin_lock_init(&lock->l_spin);
+}
+
+void l_lock(struct lustre_lock *lock)
+{
+        int owner = 0;
+        spin_lock(&lock->l_spin);
+        if (lock->l_owner == current) { 
+                owner = 1;
+        }
+        spin_unlock(&lock->l_spin);
+        if (owner)
+                 ++lock->l_depth;
+        else { 
+                down(&lock->l_sem);
+                spin_lock(&lock->l_spin);
+                lock->l_owner = current;
+                lock->l_depth = 0;
+                spin_unlock(&lock->l_spin);
+        }
+}
+
+void l_unlock(struct lustre_lock *lock)
+{
+        if (lock->l_owner != current)
+                LBUG();
+        if (lock->l_depth < 0)
+                LBUG();
+
+        spin_lock(&lock->l_spin); 
+        if (--lock->l_depth < 0) { 
+                lock->l_owner = NULL;
+                spin_unlock(&lock->l_spin);
+                up(&lock->l_sem);
+                return ;
+        }
+        spin_unlock(&lock->l_spin);
+}
-- 
1.8.3.1