1 files changed, 90 insertions, 0 deletions
diff --git a/fs/xfs/mrlock.h b/fs/xfs/mrlock.h
new file mode 100644
index 000000000000..ff6a19873e5c
--- /dev/null
+++ b/fs/xfs/mrlock.h
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would 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 this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#ifndef __XFS_SUPPORT_MRLOCK_H__
+#define __XFS_SUPPORT_MRLOCK_H__
+
+#include <linux/rwsem.h>
+
+typedef struct {
+	struct rw_semaphore	mr_lock;
+#ifdef DEBUG
+	int			mr_writer;
+#endif
+} mrlock_t;
+
+#ifdef DEBUG
+#define mrinit(mrp, name)	\
+	do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
+#else
+#define mrinit(mrp, name)	\
+	do { init_rwsem(&(mrp)->mr_lock); } while (0)
+#endif
+
+#define mrlock_init(mrp, t,n,s)	mrinit(mrp, n)
+#define mrfree(mrp)		do { } while (0)
+
+static inline void mraccess_nested(mrlock_t *mrp, int subclass)
+{
+	down_read_nested(&mrp->mr_lock, subclass);
+}
+
+static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
+{
+	down_write_nested(&mrp->mr_lock, subclass);
+#ifdef DEBUG
+	mrp->mr_writer = 1;
+#endif
+}
+
+static inline int mrtryaccess(mrlock_t *mrp)
+{
+	return down_read_trylock(&mrp->mr_lock);
+}
+
+static inline int mrtryupdate(mrlock_t *mrp)
+{
+	if (!down_write_trylock(&mrp->mr_lock))
+		return 0;
+#ifdef DEBUG
+	mrp->mr_writer = 1;
+#endif
+	return 1;
+}
+
+static inline void mrunlock_excl(mrlock_t *mrp)
+{
+#ifdef DEBUG
+	mrp->mr_writer = 0;
+#endif
+	up_write(&mrp->mr_lock);
+}
+
+static inline void mrunlock_shared(mrlock_t *mrp)
+{
+	up_read(&mrp->mr_lock);
+}
+
+static inline void mrdemote(mrlock_t *mrp)
+{
+#ifdef DEBUG
+	mrp->mr_writer = 0;
+#endif
+	downgrade_write(&mrp->mr_lock);
+}
+
+#endif /* __XFS_SUPPORT_MRLOCK_H__ */