Initial import

1 files changed, 191 insertions, 0 deletions

diff --git a/fs/aufs/rwsem.h b/fs/aufs/rwsem.h
new file mode 100644
index 000000000..deb813f3e
--- /dev/null
+++ b/fs/aufs/rwsem.h
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2005-2015 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"
+
+struct au_rwsem {
+	struct rw_semaphore	rwsem;
+#ifdef CONFIG_AUFS_DEBUG
+	/* just for debugging, not almighty counter */
+	atomic_t		rcnt, wcnt;
+#endif
+};
+
+#ifdef CONFIG_AUFS_DEBUG
+#define AuDbgCntInit(rw) do { \
+	atomic_set(&(rw)->rcnt, 0); \
+	atomic_set(&(rw)->wcnt, 0); \
+	smp_mb(); /* atomic set */ \
+} while (0)
+
+#define AuDbgRcntInc(rw)	atomic_inc(&(rw)->rcnt)
+#define AuDbgRcntDec(rw)	WARN_ON(atomic_dec_return(&(rw)->rcnt) < 0)
+#define AuDbgWcntInc(rw)	atomic_inc(&(rw)->wcnt)
+#define AuDbgWcntDec(rw)	WARN_ON(atomic_dec_return(&(rw)->wcnt) < 0)
+#else
+#define AuDbgCntInit(rw)	do {} while (0)
+#define AuDbgRcntInc(rw)	do {} while (0)
+#define AuDbgRcntDec(rw)	do {} while (0)
+#define AuDbgWcntInc(rw)	do {} while (0)
+#define AuDbgWcntDec(rw)	do {} while (0)
+#endif /* CONFIG_AUFS_DEBUG */
+
+/* to debug easier, do not make them inlined functions */
+#define AuRwMustNoWaiters(rw)	AuDebugOn(!list_empty(&(rw)->rwsem.wait_list))
+/* rwsem_is_locked() is unusable */
+#define AuRwMustReadLock(rw)	AuDebugOn(atomic_read(&(rw)->rcnt) <= 0)
+#define AuRwMustWriteLock(rw)	AuDebugOn(atomic_read(&(rw)->wcnt) <= 0)
+#define AuRwMustAnyLock(rw)	AuDebugOn(atomic_read(&(rw)->rcnt) <= 0 \
+					&& atomic_read(&(rw)->wcnt) <= 0)
+#define AuRwDestroy(rw)		AuDebugOn(atomic_read(&(rw)->rcnt) \
+					|| atomic_read(&(rw)->wcnt))
+
+#define au_rw_class(rw, key)	lockdep_set_class(&(rw)->rwsem, key)
+
+static inline void au_rw_init(struct au_rwsem *rw)
+{
+	AuDbgCntInit(rw);
+	init_rwsem(&rw->rwsem);
+}
+
+static inline void au_rw_init_wlock(struct au_rwsem *rw)
+{
+	au_rw_init(rw);
+	down_write(&rw->rwsem);
+	AuDbgWcntInc(rw);
+}
+
+static inline void au_rw_init_wlock_nested(struct au_rwsem *rw,
+					   unsigned int lsc)
+{
+	au_rw_init(rw);
+	down_write_nested(&rw->rwsem, lsc);
+	AuDbgWcntInc(rw);
+}
+
+static inline void au_rw_read_lock(struct au_rwsem *rw)
+{
+	down_read(&rw->rwsem);
+	AuDbgRcntInc(rw);
+}
+
+static inline void au_rw_read_lock_nested(struct au_rwsem *rw, unsigned int lsc)
+{
+	down_read_nested(&rw->rwsem, lsc);
+	AuDbgRcntInc(rw);
+}
+
+static inline void au_rw_read_unlock(struct au_rwsem *rw)
+{
+	AuRwMustReadLock(rw);
+	AuDbgRcntDec(rw);
+	up_read(&rw->rwsem);
+}
+
+static inline void au_rw_dgrade_lock(struct au_rwsem *rw)
+{
+	AuRwMustWriteLock(rw);
+	AuDbgRcntInc(rw);
+	AuDbgWcntDec(rw);
+	downgrade_write(&rw->rwsem);
+}
+
+static inline void au_rw_write_lock(struct au_rwsem *rw)
+{
+	down_write(&rw->rwsem);
+	AuDbgWcntInc(rw);
+}
+
+static inline void au_rw_write_lock_nested(struct au_rwsem *rw,
+					   unsigned int lsc)
+{
+	down_write_nested(&rw->rwsem, lsc);
+	AuDbgWcntInc(rw);
+}
+
+static inline void au_rw_write_unlock(struct au_rwsem *rw)
+{
+	AuRwMustWriteLock(rw);
+	AuDbgWcntDec(rw);
+	up_write(&rw->rwsem);
+}
+
+/* why is not _nested version defined */
+static inline int au_rw_read_trylock(struct au_rwsem *rw)
+{
+	int ret;
+
+	ret = down_read_trylock(&rw->rwsem);
+	if (ret)
+		AuDbgRcntInc(rw);
+	return ret;
+}
+
+static inline int au_rw_write_trylock(struct au_rwsem *rw)
+{
+	int ret;
+
+	ret = down_write_trylock(&rw->rwsem);
+	if (ret)
+		AuDbgWcntInc(rw);
+	return ret;
+}
+
+#undef AuDbgCntInit
+#undef AuDbgRcntInc
+#undef AuDbgRcntDec
+#undef AuDbgWcntInc
+#undef AuDbgWcntDec
+
+#define AuSimpleLockRwsemFuncs(prefix, param, rwsem) \
+static inline void prefix##_read_lock(param) \
+{ au_rw_read_lock(rwsem); } \
+static inline void prefix##_write_lock(param) \
+{ au_rw_write_lock(rwsem); } \
+static inline int prefix##_read_trylock(param) \
+{ return au_rw_read_trylock(rwsem); } \
+static inline int prefix##_write_trylock(param) \
+{ return au_rw_write_trylock(rwsem); }
+/* why is not _nested version defined */
+/* static inline void prefix##_read_trylock_nested(param, lsc)
+{ au_rw_read_trylock_nested(rwsem, lsc)); }
+static inline void prefix##_write_trylock_nestd(param, lsc)
+{ au_rw_write_trylock_nested(rwsem, lsc); } */
+
+#define AuSimpleUnlockRwsemFuncs(prefix, param, rwsem) \
+static inline void prefix##_read_unlock(param) \
+{ au_rw_read_unlock(rwsem); } \
+static inline void prefix##_write_unlock(param) \
+{ au_rw_write_unlock(rwsem); } \
+static inline void prefix##_downgrade_lock(param) \
+{ au_rw_dgrade_lock(rwsem); }
+
+#define AuSimpleRwsemFuncs(prefix, param, rwsem) \
+	AuSimpleLockRwsemFuncs(prefix, param, rwsem) \
+	AuSimpleUnlockRwsemFuncs(prefix, param, rwsem)
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_RWSEM_H__ */