1 files changed, 73 insertions, 0 deletions
diff --git a/fs/aufs/rwsem.h b/fs/aufs/rwsem.h
new file mode 100644
index 000000000000..370eae159348
--- /dev/null
+++ b/fs/aufs/rwsem.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2005-2020 Junjiro R. Okajima
+ *
+ * This program, aufs 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * simple read-write semaphore wrappers
+ */
+
+#ifndef __AUFS_RWSEM_H__
+#define __AUFS_RWSEM_H__
+
+#ifdef __KERNEL__
+
+#include "debug.h"
+
+/* in the future, the name 'au_rwsem' will be totally gone */
+#define au_rwsem	rw_semaphore
+
+/* to debug easier, do not make them inlined functions */
+#define AuRwMustNoWaiters(rw)	AuDebugOn(rwsem_is_contended(rw))
+/* rwsem_is_locked() is unusable */
+#define AuRwMustReadLock(rw)	AuDebugOn(!lockdep_recursing(current) \
+					  && debug_locks \
+					  && !lockdep_is_held_type(rw, 1))
+#define AuRwMustWriteLock(rw)	AuDebugOn(!lockdep_recursing(current) \
+					  && debug_locks \
+					  && !lockdep_is_held_type(rw, 0))
+#define AuRwMustAnyLock(rw)	AuDebugOn(!lockdep_recursing(current) \
+					  && debug_locks \
+					  && !lockdep_is_held(rw))
+#define AuRwDestroy(rw)		AuDebugOn(!lockdep_recursing(current) \
+					  && debug_locks \
+					  && lockdep_is_held(rw))
+
+#define au_rw_init(rw)	init_rwsem(rw)
+
+#define au_rw_init_wlock(rw) do {		\
+		au_rw_init(rw);			\
+		down_write(rw);			\
+	} while (0)
+
+#define au_rw_init_wlock_nested(rw, lsc) do {	\
+		au_rw_init(rw);			\
+		down_write_nested(rw, lsc);	\
+	} while (0)
+
+#define au_rw_read_lock(rw)		down_read(rw)
+#define au_rw_read_lock_nested(rw, lsc)	down_read_nested(rw, lsc)
+#define au_rw_read_unlock(rw)		up_read(rw)
+#define au_rw_dgrade_lock(rw)		downgrade_write(rw)
+#define au_rw_write_lock(rw)		down_write(rw)
+#define au_rw_write_lock_nested(rw, lsc) down_write_nested(rw, lsc)
+#define au_rw_write_unlock(rw)		up_write(rw)
+/* why is not _nested version defined? */
+#define au_rw_read_trylock(rw)		down_read_trylock(rw)
+#define au_rw_write_trylock(rw)		down_write_trylock(rw)
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_RWSEM_H__ */