eulerfs: add interfaces for inode lock transfer

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I40JRR
CVE: NA

--------------------------------------
Signed-off-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/eulerfs/lock.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2021. Huawei Technologies Co., Ltd. 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 version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#ifndef EUFS_LOCK_H
+#define EUFS_LOCK_H
+
+#include "euler_def.h"
+
+static inline void eufs_inode_mark_lock_transferable(struct inode *inode)
+{
+	struct eufs_inode_info *vi = EUFS_I(inode);
+
+	vi->i_lock_transferred = I_TRANS_AVAIL;
+}
+
+static inline void eufs_inode_wait_lock_transfer_done(struct inode *inode)
+{
+	struct eufs_inode_info *vi = EUFS_I(inode);
+
+	while (cmpxchg(&vi->i_lock_transferred, I_TRANS_AVAIL, I_TRANS_NONE) !=
+	       I_TRANS_AVAIL)
+		cond_resched();
+}
+
+/* return true on success, false on failure */
+static inline bool eufs_inode_mark_lock_transferring(struct inode *inode)
+{
+	struct eufs_inode_info *vi = EUFS_I(inode);
+
+	return (cmpxchg(&vi->i_lock_transferred, I_TRANS_AVAIL,
+			I_TRANS_LOCKED) == I_TRANS_AVAIL);
+}
+
+static inline void eufs_inode_lock_transfer_done(struct inode *inode)
+{
+	eufs_inode_mark_lock_transferable(inode);
+}
+
+#endif /* EUFS_LOCK_H */