ubifs: Export filesystem error counters

Not all ubifs filesystem errors are propagated to userspace.

Export bad magic, bad node and crc errors via sysfs. This allows userspace
to notice filesystem errors:

 /sys/fs/ubifs/ubiX_Y/errors_magic
 /sys/fs/ubifs/ubiX_Y/errors_node
 /sys/fs/ubifs/ubiX_Y/errors_crc

The counters are reset to 0 with a remount.

Signed-off-by: Stefan Schaeckeler <sschaeck@cisco.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 153 insertions, 0 deletions

diff --git a/fs/ubifs/sysfs.c b/fs/ubifs/sysfs.c
new file mode 100644
index 000000000000..0eb3d7d12450
--- /dev/null
+++ b/fs/ubifs/sysfs.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2021 Cisco Systems
+ *
+ * Author: Stefan Schaeckeler
+ */
+
+
+#include <linux/fs.h>
+#include "ubifs.h"
+
+enum attr_id_t {
+	attr_errors_magic,
+	attr_errors_node,
+	attr_errors_crc,
+};
+
+struct ubifs_attr {
+	struct attribute attr;
+	enum attr_id_t attr_id;
+};
+
+#define UBIFS_ATTR(_name, _mode, _id)					\
+static struct ubifs_attr ubifs_attr_##_name = {				\
+	.attr = {.name = __stringify(_name), .mode = _mode },		\
+	.attr_id = attr_##_id,						\
+}
+
+#define UBIFS_ATTR_FUNC(_name, _mode) UBIFS_ATTR(_name, _mode, _name)
+
+UBIFS_ATTR_FUNC(errors_magic, 0444);
+UBIFS_ATTR_FUNC(errors_crc, 0444);
+UBIFS_ATTR_FUNC(errors_node, 0444);
+
+#define ATTR_LIST(name) (&ubifs_attr_##name.attr)
+
+static struct attribute *ubifs_attrs[] = {
+	ATTR_LIST(errors_magic),
+	ATTR_LIST(errors_node),
+	ATTR_LIST(errors_crc),
+	NULL,
+};
+
+static ssize_t ubifs_attr_show(struct kobject *kobj,
+			       struct attribute *attr, char *buf)
+{
+	struct ubifs_info *sbi = container_of(kobj, struct ubifs_info,
+					      kobj);
+
+	struct ubifs_attr *a = container_of(attr, struct ubifs_attr, attr);
+
+	switch (a->attr_id) {
+	case attr_errors_magic:
+		return sysfs_emit(buf, "%u\n", sbi->stats->magic_errors);
+	case attr_errors_node:
+		return sysfs_emit(buf, "%u\n", sbi->stats->node_errors);
+	case attr_errors_crc:
+		return sysfs_emit(buf, "%u\n", sbi->stats->crc_errors);
+	}
+	return 0;
+};
+
+static void ubifs_sb_release(struct kobject *kobj)
+{
+	struct ubifs_info *c = container_of(kobj, struct ubifs_info, kobj);
+
+	complete(&c->kobj_unregister);
+}
+
+static const struct sysfs_ops ubifs_attr_ops = {
+	.show	= ubifs_attr_show,
+};
+
+static struct kobj_type ubifs_sb_ktype = {
+	.default_attrs	= ubifs_attrs,
+	.sysfs_ops	= &ubifs_attr_ops,
+	.release	= ubifs_sb_release,
+};
+
+static struct kobj_type ubifs_ktype = {
+	.sysfs_ops	= &ubifs_attr_ops,
+};
+
+static struct kset ubifs_kset = {
+	.kobj	= {.ktype = &ubifs_ktype},
+};
+
+int ubifs_sysfs_register(struct ubifs_info *c)
+{
+	int ret, n;
+	char dfs_dir_name[UBIFS_DFS_DIR_LEN+1];
+
+	c->stats = kzalloc(sizeof(struct ubifs_stats_info), GFP_KERNEL);
+	if (!c->stats) {
+		ret = -ENOMEM;
+		goto out_last;
+	}
+	n = snprintf(dfs_dir_name, UBIFS_DFS_DIR_LEN + 1, UBIFS_DFS_DIR_NAME,
+		     c->vi.ubi_num, c->vi.vol_id);
+
+	if (n == UBIFS_DFS_DIR_LEN) {
+		/* The array size is too small */
+		ret = -EINVAL;
+		goto out_free;
+	}
+
+	c->kobj.kset = &ubifs_kset;
+	init_completion(&c->kobj_unregister);
+
+	ret = kobject_init_and_add(&c->kobj, &ubifs_sb_ktype, NULL,
+				   "%s", dfs_dir_name);
+	if (ret)
+		goto out_put;
+
+	return 0;
+
+out_put:
+	kobject_put(&c->kobj);
+	wait_for_completion(&c->kobj_unregister);
+out_free:
+	kfree(c->stats);
+out_last:
+	ubifs_err(c, "cannot create sysfs entry for ubifs%d_%d, error %d\n",
+		  c->vi.ubi_num, c->vi.vol_id, ret);
+	return ret;
+}
+
+void ubifs_sysfs_unregister(struct ubifs_info *c)
+{
+	kobject_del(&c->kobj);
+	kobject_put(&c->kobj);
+	wait_for_completion(&c->kobj_unregister);
+
+	kfree(c->stats);
+}
+
+int __init ubifs_sysfs_init(void)
+{
+	int ret;
+
+	kobject_set_name(&ubifs_kset.kobj, "ubifs");
+	ubifs_kset.kobj.parent = fs_kobj;
+	ret = kset_register(&ubifs_kset);
+
+	return ret;
+}
+
+void ubifs_sysfs_exit(void)
+{
+	kset_unregister(&ubifs_kset);
+}