Message-Id: <20210907214034.11676-2-schaecsn@gmx.net>
Date:   Tue,  7 Sep 2021 14:40:34 -0700
From:   Stefan Schaeckeler <schaecsn@....net>
To:     richard@....at, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Stefan Schaeckeler <schaecsn@....net>,
        Stefan Schaeckeler <sschaeck@...co.com>
Subject: [PATCH 1/1] ubifs: ubifs to 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. Writing anything into the
counters also clears them.

Signed-off-by: Stefan Schaeckeler <sschaeck@...co.com>
---
 fs/ubifs/Makefile |   2 +-
 fs/ubifs/io.c     |   6 ++
 fs/ubifs/super.c  |  17 ++++-
 fs/ubifs/sysfs.c  | 187 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/ubifs/sysfs.h  |  39 ++++++++++
 fs/ubifs/ubifs.h  |  11 +++
 6 files changed, 260 insertions(+), 2 deletions(-)
 create mode 100644 fs/ubifs/sysfs.c
 create mode 100644 fs/ubifs/sysfs.h

diff --git a/fs/ubifs/Makefile b/fs/ubifs/Makefile
index 5c4b845754a7..314c80b24a76 100644
--- a/fs/ubifs/Makefile
+++ b/fs/ubifs/Makefile
@@ -5,7 +5,7 @@ ubifs-y += shrinker.o journal.o file.o dir.o super.o sb.o io.o
 ubifs-y += tnc.o master.o scan.o replay.o log.o commit.o gc.o orphan.o
 ubifs-y += budget.o find.o tnc_commit.o compress.o lpt.o lprops.o
 ubifs-y += recovery.o ioctl.o lpt_commit.o tnc_misc.o debug.o
-ubifs-y += misc.o
+ubifs-y += misc.o sysfs.o
 ubifs-$(CONFIG_FS_ENCRYPTION) += crypto.o
 ubifs-$(CONFIG_UBIFS_FS_XATTR) += xattr.o
 ubifs-$(CONFIG_UBIFS_FS_AUTHENTICATION) += auth.o
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 00b61dba62b7..0b158e420cc1 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -238,6 +238,8 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int len,
 		if (!quiet)
 			ubifs_err(c, "bad magic %#08x, expected %#08x",
 				  magic, UBIFS_NODE_MAGIC);
+		if (c->stats)
+			c->stats->magic_errors++;
 		err = -EUCLEAN;
 		goto out;
 	}
@@ -246,6 +248,8 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int len,
 	if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
 		if (!quiet)
 			ubifs_err(c, "bad node type %d", type);
+		if (c->stats)
+			c->stats->node_errors++;
 		goto out;
 	}

@@ -270,6 +274,8 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int len,
 		if (!quiet)
 			ubifs_err(c, "bad CRC: calculated %#08x, read %#08x",
 				  crc, node_crc);
+		if (c->stats)
+			c->stats->crc_errors++;
 		err = -EUCLEAN;
 		goto out;
 	}
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index f0fb25727d96..50b934854a84 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -24,6 +24,7 @@
 #include <linux/mount.h>
 #include <linux/math64.h>
 #include <linux/writeback.h>
+#include "sysfs.h"
 #include "ubifs.h"

 static int ubifs_default_version_set(const char *val, const struct kernel_param *kp)
@@ -1264,6 +1265,10 @@ static int mount_ubifs(struct ubifs_info *c)
 	if (err)
 		return err;

+	err = ubifs_sysfs_register(c);
+	if (err)
+		goto out_debugging;
+
 	err = check_volume_empty(c);
 	if (err)
 		goto out_free;
@@ -1641,6 +1646,8 @@ static int mount_ubifs(struct ubifs_info *c)
 	vfree(c->sbuf);
 	kfree(c->bottom_up_buf);
 	kfree(c->sup_node);
+	ubifs_sysfs_unregister(c);
+out_debugging:
 	ubifs_debugging_exit(c);
 	return err;
 }
@@ -1684,6 +1691,7 @@ static void ubifs_umount(struct ubifs_info *c)
 	kfree(c->bottom_up_buf);
 	kfree(c->sup_node);
 	ubifs_debugging_exit(c);
+	ubifs_sysfs_unregister(c);
 }

 /**
@@ -2436,14 +2444,20 @@ static int __init ubifs_init(void)

 	dbg_debugfs_init();

+	err = ubifs_sysfs_init();
+	if (err)
+		goto out_dbg;
+
 	err = register_filesystem(&ubifs_fs_type);
 	if (err) {
 		pr_err("UBIFS error (pid %d): cannot register file system, error %d",
 		       current->pid, err);
-		goto out_dbg;
+		goto out_sysfs;
 	}
 	return 0;

+out_sysfs:
+	ubifs_sysfs_exit();
 out_dbg:
 	dbg_debugfs_exit();
 	ubifs_compressors_exit();
@@ -2462,6 +2476,7 @@ static void __exit ubifs_exit(void)
 	WARN_ON(atomic_long_read(&ubifs_clean_zn_cnt) != 0);

 	dbg_debugfs_exit();
+	ubifs_sysfs_exit();
 	ubifs_compressors_exit();
 	unregister_shrinker(&ubifs_shrinker_info);

diff --git a/fs/ubifs/sysfs.c b/fs/ubifs/sysfs.c
new file mode 100644
index 000000000000..bac53a0f0451
--- /dev/null
+++ b/fs/ubifs/sysfs.c
@@ -0,0 +1,187 @@
+// 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 "sysfs.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, 0644);
+UBIFS_ATTR_FUNC(errors_crc, 0644);
+UBIFS_ATTR_FUNC(errors_node, 0644);
+
+#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 snprintf(buf, PAGE_SIZE, "%u\n",
+				sbi->stats->magic_errors);
+	case attr_errors_node:
+		return snprintf(buf, PAGE_SIZE, "%u\n",
+				sbi->stats->node_errors);
+	case attr_errors_crc:
+		return snprintf(buf, PAGE_SIZE, "%u\n",
+				sbi->stats->crc_errors);
+	}
+	return 0;
+};
+
+
+static ssize_t ubifs_attr_store(struct kobject *kobj,
+			       struct attribute *attr,
+			       const char *buf, size_t len)
+{
+	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:
+		sbi->stats->magic_errors = 0;
+		break;
+	case attr_errors_node:
+		sbi->stats->node_errors = 0;
+		break;
+	case attr_errors_crc:
+		sbi->stats->crc_errors = 0;
+		break;
+	}
+	return len;
+}
+
+
+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,
+	.store	= ubifs_attr_store,
+};
+
+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_last;
+	}
+
+	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_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);
+}
diff --git a/fs/ubifs/sysfs.h b/fs/ubifs/sysfs.h
new file mode 100644
index 000000000000..a10a82585af8
--- /dev/null
+++ b/fs/ubifs/sysfs.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2021 Cisco Systems
+ *
+ * Author: Stefan Schaeckeler
+ */
+
+#ifndef __UBIFS_SYSFS_H__
+#define __UBIFS_SYSFS_H__
+
+struct ubifs_info;
+
+/*
+ * The UBIFS sysfs directory name pattern and maximum name length (3 for "ubi"
+ * + 1 for "_" and plus 2x2 for 2 UBI numbers and 1 for the trailing zero byte.
+ */
+#define UBIFS_DFS_DIR_NAME "ubi%d_%d"
+#define UBIFS_DFS_DIR_LEN  (3 + 1 + 2*2 + 1)
+
+/**
+ * ubifs_stats_info - per-FS statistics information.
+ * @magic_errors: number of bad magic numbers (will be reset with a new mount).
+ * @node_errors: number of bad nodes (will be reset with a new mount).
+ * @crc_errors: number of bad crcs (will be reset with a new mount).
+ */
+struct ubifs_stats_info {
+	unsigned int magic_errors;
+	unsigned int node_errors;
+	unsigned int crc_errors;
+};
+
+int ubifs_sysfs_init(void);
+void ubifs_sysfs_exit(void);
+int ubifs_sysfs_register(struct ubifs_info *c);
+void ubifs_sysfs_unregister(struct ubifs_info *c);
+
+#endif
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index c38066ce9ab0..bfc0f20b41a1 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -27,12 +27,15 @@
 #include <linux/security.h>
 #include <linux/xattr.h>
 #include <linux/random.h>
+#include <linux/sysfs.h>
+#include <linux/completion.h>
 #include <crypto/hash_info.h>
 #include <crypto/hash.h>
 #include <crypto/algapi.h>

 #include <linux/fscrypt.h>

+#include "sysfs.h"
 #include "ubifs-media.h"

 /* Version of this UBIFS implementation */
@@ -1251,6 +1254,10 @@ struct ubifs_debug_info;
  * @mount_opts: UBIFS-specific mount options
  *
  * @dbg: debugging-related information
+ * @stats: statistics exported over sysfs
+ *
+ * @kobj: kobject for /sys/fs/ubifs/
+ * @kobj_unregister: completion to unregister sysfs kobject
  */
 struct ubifs_info {
 	struct super_block *vfs_sb;
@@ -1286,6 +1293,9 @@ struct ubifs_info {
 	spinlock_t cs_lock;
 	wait_queue_head_t cmt_wq;

+	struct kobject kobj;
+	struct completion kobj_unregister;
+
 	unsigned int big_lpt:1;
 	unsigned int space_fixup:1;
 	unsigned int double_hash:1;
@@ -1493,6 +1503,7 @@ struct ubifs_info {
 	struct ubifs_mount_opts mount_opts;

 	struct ubifs_debug_info *dbg;
+	struct ubifs_stats_info *stats;
 };

 extern struct list_head ubifs_infos;
--
2.32.0

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