eulerfs: add interfaces for page wear

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

--------------------------------------

Page wears are preallocated ints for all pages, each of the ints
records the number of writes to the page. This is used to
coarse-grainedly show the degree of wear.
Signed-off-by: NMingkai Dong <dongmingkai1@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/wear.c

+// 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.
+ */
+
+#include "wear.h"
+#include <linux/vmalloc.h>
+#include "euler.h"
+
+void wear_init(struct super_block *sb)
+{
+	struct eufs_sb_info *sbi = EUFS_SB(sb);
+
+	if (!wear_control)
+		return;
+	sbi->page_wears = vmalloc(sizeof(struct page_wear) * sbi->npages);
+	memset(sbi->page_wears, 0, sizeof(struct page_wear) * sbi->npages);
+}
+
+void wear_fini(struct super_block *sb)
+{
+	struct eufs_sb_info *sbi = EUFS_SB(sb);
+
+	if (!wear_control)
+		return;
+	if (sbi->page_wears)
+		vfree(sbi->page_wears);
+	sbi->page_wears = NULL;
+}
+
+/* Return whether it's in a good state */
+bool wear_inc(struct super_block *sb, void *page)
+{
+	struct eufs_sb_info *sbi = EUFS_SB(sb);
+
+	if (!wear_control)
+		return true;
+	return sbi->page_wears[(page - sbi->data_start) / PAGE_SIZE].wear++ <=
+	       wear_threshold;
+}

fs/eulerfs/wear.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_WEAR_H
+#define EUFS_WEAR_H
+
+#include <linux/fs.h>
+
+extern int wear_threshold;
+extern int wear_control;
+
+struct page_wear {
+	int wear;
+};
+
+void wear_init(struct super_block *sb);
+void wear_fini(struct super_block *sb);
+bool wear_inc(struct super_block *sb, void *page);
+
+#endif /* EUFS_WEAR_H */