1 files changed, 106 insertions, 0 deletions
diff --git a/fs/xfs/linux-2.6/mrlock.h b/fs/xfs/linux-2.6/mrlock.h
new file mode 100644
index 00000000000..d2c11a098ff
--- /dev/null
+++ b/fs/xfs/linux-2.6/mrlock.h
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2000-2004 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ * This program 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.
+ *
+ * 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.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like.  Any license provided herein, whether implied or
+ * otherwise, applies only to this software file.  Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
+ * Mountain View, CA  94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
+ */
+#ifndef __XFS_SUPPORT_MRLOCK_H__
+#define __XFS_SUPPORT_MRLOCK_H__
+
+#include <linux/rwsem.h>
+
+enum { MR_NONE, MR_ACCESS, MR_UPDATE };
+
+typedef struct {
+	struct rw_semaphore	mr_lock;
+	int			mr_writer;
+} mrlock_t;
+
+#define mrinit(mrp, name)	\
+	( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) )
+#define mrlock_init(mrp, t,n,s)	mrinit(mrp, n)
+#define mrfree(mrp)		do { } while (0)
+#define mraccess(mrp)		mraccessf(mrp, 0)
+#define mrupdate(mrp)		mrupdatef(mrp, 0)
+
+static inline void mraccessf(mrlock_t *mrp, int flags)
+{
+	down_read(&mrp->mr_lock);
+}
+
+static inline void mrupdatef(mrlock_t *mrp, int flags)
+{
+	down_write(&mrp->mr_lock);
+	mrp->mr_writer = 1;
+}
+
+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;
+	mrp->mr_writer = 1;
+	return 1;
+}
+
+static inline void mrunlock(mrlock_t *mrp)
+{
+	if (mrp->mr_writer) {
+		mrp->mr_writer = 0;
+		up_write(&mrp->mr_lock);
+	} else {
+		up_read(&mrp->mr_lock);
+	}
+}
+
+static inline void mrdemote(mrlock_t *mrp)
+{
+	mrp->mr_writer = 0;
+	downgrade_write(&mrp->mr_lock);
+}
+
+#ifdef DEBUG
+/*
+ * Debug-only routine, without some platform-specific asm code, we can
+ * now only answer requests regarding whether we hold the lock for write
+ * (reader state is outside our visibility, we only track writer state).
+ * Note: means !ismrlocked would give false positivies, so don't do that.
+ */
+static inline int ismrlocked(mrlock_t *mrp, int type)
+{
+	if (mrp && type == MR_UPDATE)
+		return mrp->mr_writer;
+	return 1;
+}
+#endif
+
+#endif /* __XFS_SUPPORT_MRLOCK_H__ */