Merge tag 'for-linus-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs

Pull JFFS2, UBI and UBIFS updates from Richard Weinberger:
 "JFFS2:
   - Fix for a deadlock in jffs2_write_begin()

  UBI:
   - Fixes in comments

  UBIFS:
   - Expose error counters in sysfs
   - Many bugfixes found by Hulk Robot and others"

* tag 'for-linus-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
  jffs2: GC deadlock reading a page that is used in jffs2_write_begin()
  ubifs: read-only if LEB may always be taken in ubifs_garbage_collect
  ubifs: fix double return leb in ubifs_garbage_collect
  ubifs: fix slab-out-of-bounds in ubifs_change_lp
  ubifs: fix snprintf() length check
  ubifs: Document sysfs nodes
  ubifs: Export filesystem error counters
  ubifs: Error path in ubifs_remount_rw() seems to wrongly free write buffers
  ubifs: Make use of the helper macro kthread_run()
  ubi: Fix a mistake in comment
  ubifs: Fix spelling mistakes

12 files changed, 309 insertions, 28 deletions

diff --git a/Documentation/ABI/testing/sysfs-fs-ubifs b/Documentation/ABI/testing/sysfs-fs-ubifs
new file mode 100644
index 000000000000..af5afda30220
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-fs-ubifs
@@ -0,0 +1,35 @@
+What:		/sys/fs/ubifsX_Y/error_magic
+Date:		October 2021
+KernelVersion:	5.16
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Exposes magic errors: every node starts with a magic number.
+
+		This counter keeps track of the number of accesses of nodes
+		with a corrupted magic number.
+
+		The counter is reset to 0 with a remount.
+
+What:		/sys/fs/ubifsX_Y/error_node
+Date:		October 2021
+KernelVersion:	5.16
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Exposes node errors. Every node embeds its type.
+
+		This counter keeps track of the number of accesses of nodes
+		with a corrupted node type.
+
+		The counter is reset to 0 with a remount.
+
+What:		/sys/fs/ubifsX_Y/error_crc
+Date:		October 2021
+KernelVersion:	5.16
+Contact:	linux-mtd@lists.infradead.org
+Description:
+		Exposes crc errors: every node embeds a crc checksum.
+
+		This counter keeps track of the number of accesses of nodes
+		with a bad crc checksum.
+
+		The counter is reset to 0 with a remount.
diff --git a/MAINTAINERS b/MAINTAINERS
index baba3eceb1f0..03916ac8a4ac 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19603,6 +19603,7 @@ S:	Supported
 W:	http://www.linux-mtd.infradead.org/doc/ubifs.html
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs.git next
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs.git fixes
+F:	Documentation/ABI/testing/sysfs-fs-ubifs
 F:	Documentation/filesystems/ubifs-authentication.rst
 F:	Documentation/filesystems/ubifs.rst
 F:	fs/ubifs/
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 3c0c8eca4d51..31d427ee191a 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -562,7 +562,7 @@ int ubi_debugfs_init_dev(struct ubi_device *ubi)
 }
 
 /**
- * dbg_debug_exit_dev - free all debugfs files corresponding to device @ubi
+ * ubi_debugfs_exit_dev - free all debugfs files corresponding to device @ubi
  * @ubi: UBI device description object
  */
 void ubi_debugfs_exit_dev(struct ubi_device *ubi)
diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
index 4fc8cd698d1a..bd7d58d27bfc 100644
--- a/fs/jffs2/file.c
+++ b/fs/jffs2/file.c
@@ -136,20 +136,15 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 	struct page *pg;
 	struct inode *inode = mapping->host;
 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
+	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
 	pgoff_t index = pos >> PAGE_SHIFT;
 	uint32_t pageofs = index << PAGE_SHIFT;
 	int ret = 0;
 
-	pg = grab_cache_page_write_begin(mapping, index, flags);
-	if (!pg)
-		return -ENOMEM;
-	*pagep = pg;
-
 	jffs2_dbg(1, "%s()\n", __func__);
 
 	if (pageofs > inode->i_size) {
 		/* Make new hole frag from old EOF to new page */
-		struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
 		struct jffs2_raw_inode ri;
 		struct jffs2_full_dnode *fn;
 		uint32_t alloc_len;
@@ -160,7 +155,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 		ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
 					  ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
 		if (ret)
-			goto out_page;
+			goto out_err;
 
 		mutex_lock(&f->sem);
 		memset(&ri, 0, sizeof(ri));
@@ -190,7 +185,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 			ret = PTR_ERR(fn);
 			jffs2_complete_reservation(c);
 			mutex_unlock(&f->sem);
-			goto out_page;
+			goto out_err;
 		}
 		ret = jffs2_add_full_dnode_to_inode(c, f, fn);
 		if (f->metadata) {
@@ -205,7 +200,7 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 			jffs2_free_full_dnode(fn);
 			jffs2_complete_reservation(c);
 			mutex_unlock(&f->sem);
-			goto out_page;
+			goto out_err;
 		}
 		jffs2_complete_reservation(c);
 		inode->i_size = pageofs;
@@ -213,6 +208,19 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 	}
 
 	/*
+	 * While getting a page and reading data in, lock c->alloc_sem until
+	 * the page is Uptodate. Otherwise GC task may attempt to read the same
+	 * page in read_cache_page(), which causes a deadlock.
+	 */
+	mutex_lock(&c->alloc_sem);
+	pg = grab_cache_page_write_begin(mapping, index, flags);
+	if (!pg) {
+		ret = -ENOMEM;
+		goto release_sem;
+	}
+	*pagep = pg;
+
+	/*
 	 * Read in the page if it wasn't already present. Cannot optimize away
 	 * the whole page write case until jffs2_write_end can handle the
 	 * case of a short-copy.
@@ -221,15 +229,17 @@ static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
 		mutex_lock(&f->sem);
 		ret = jffs2_do_readpage_nolock(inode, pg);
 		mutex_unlock(&f->sem);
-		if (ret)
-			goto out_page;
+		if (ret) {
+			unlock_page(pg);
+			put_page(pg);
+			goto release_sem;
+		}
 	}
 	jffs2_dbg(1, "end write_begin(). pg->flags %lx\n", pg->flags);
-	return ret;
 
-out_page:
-	unlock_page(pg);
-	put_page(pg);
+release_sem:
+	mutex_unlock(&c->alloc_sem);
+out_err:
 	return ret;
 }
 
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/dir.c b/fs/ubifs/dir.c
index 7c61d0ec0159..dbe72f664abf 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1207,7 +1207,7 @@ out_budg:
  * @inode1: first inode
  * @inode2: second inode
  * @inode3: third inode
- * @inode4: fouth inode
+ * @inode4: fourth inode
  *
  * This function is used for 'ubifs_rename()' and @inode1 may be the same as
  * @inode2 whereas @inode3 and @inode4 may be %NULL.
@@ -1233,7 +1233,7 @@ static void lock_4_inodes(struct inode *inode1, struct inode *inode2,
  * @inode1: first inode
  * @inode2: second inode
  * @inode3: third inode
- * @inode4: fouth inode
+ * @inode4: fourth inode
  */
 static void unlock_4_inodes(struct inode *inode1, struct inode *inode2,
 			    struct inode *inode3, struct inode *inode4)
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index dc3e26e9ed7b..3134d070fcc0 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -692,6 +692,9 @@ int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
 	for (i = 0; ; i++) {
 		int space_before, space_after;
 
+		/* Maybe continue after find and break before find */
+		lp.lnum = -1;
+
 		cond_resched();
 
 		/* Give the commit an opportunity to run */
@@ -753,8 +756,19 @@ int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
 				 * caller instead of the original '-EAGAIN'.
 				 */
 				err = ubifs_return_leb(c, lp.lnum);
-				if (err)
+				if (err) {
 					ret = err;
+					/*
+					 * An LEB may always be "taken",
+					 * so setting ubifs to read-only,
+					 * and then executing sync wbuf will
+					 * return -EROFS and enter the "out"
+					 * error branch.
+					 */
+					ubifs_ro_mode(c, ret);
+				}
+				/*  Maybe double return LEB if goto out */
+				lp.lnum = -1;
 				break;
 			}
 			goto out;
@@ -843,7 +857,8 @@ out:
 	ubifs_wbuf_sync_nolock(wbuf);
 	ubifs_ro_mode(c, ret);
 	mutex_unlock(&wbuf->io_mutex);
-	ubifs_return_leb(c, lp.lnum);
+	if (lp.lnum != -1)
+		ubifs_return_leb(c, lp.lnum);
 	return ret;
 }
 
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 00b61dba62b7..789a7813f3fa 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -194,6 +194,24 @@ int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
 	return err;
 }
 
+static void record_magic_error(struct ubifs_stats_info *stats)
+{
+	if (stats)
+		stats->magic_errors++;
+}
+
+static void record_node_error(struct ubifs_stats_info *stats)
+{
+	if (stats)
+		stats->node_errors++;
+}
+
+static void record_crc_error(struct ubifs_stats_info *stats)
+{
+	if (stats)
+		stats->crc_errors++;
+}
+
 /**
  * ubifs_check_node - check node.
  * @c: UBIFS file-system description object
@@ -238,6 +256,7 @@ 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);
+		record_magic_error(c->stats);
 		err = -EUCLEAN;
 		goto out;
 	}
@@ -246,6 +265,7 @@ 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);
+		record_node_error(c->stats);
 		goto out;
 	}
 
@@ -270,6 +290,7 @@ 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);
+		record_crc_error(c->stats);
 		err = -EUCLEAN;
 		goto out;
 	}
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 5260d3e531bb..4211e4456b1e 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -106,7 +106,7 @@ static int set_bud_lprops(struct ubifs_info *c, struct bud_entry *b)
 		 * property values should be @lp->free == @c->leb_size and
 		 * @lp->dirty == 0, but that is not the case. The reason is that
 		 * the LEB had been garbage collected before it became the bud,
-		 * and there was not commit inbetween. The garbage collector
+		 * and there was no commit in between. The garbage collector
 		 * resets the free and dirty space without recording it
 		 * anywhere except lprops, so if there was no commit then
 		 * lprops does not have that information.
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index f0fb25727d96..aa7a1381c457 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1264,6 +1264,10 @@ 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;
@@ -1367,7 +1371,7 @@ static int mount_ubifs(struct ubifs_info *c)
 	sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);
 	if (!c->ro_mount) {
 		/* Create background thread */
-		c->bgt = kthread_create(ubifs_bg_thread, c, "%s", c->bgt_name);
+		c->bgt = kthread_run(ubifs_bg_thread, c, "%s", c->bgt_name);
 		if (IS_ERR(c->bgt)) {
 			err = PTR_ERR(c->bgt);
 			c->bgt = NULL;
@@ -1375,7 +1379,6 @@ static int mount_ubifs(struct ubifs_info *c)
 				  c->bgt_name, err);
 			goto out_wbufs;
 		}
-		wake_up_process(c->bgt);
 	}
 
 	err = ubifs_read_master(c);
@@ -1641,6 +1644,8 @@ out_free:
 	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 +1689,7 @@ 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);
 }
 
 /**
@@ -1780,7 +1786,7 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 		goto out;
 
 	/* Create background thread */
-	c->bgt = kthread_create(ubifs_bg_thread, c, "%s", c->bgt_name);
+	c->bgt = kthread_run(ubifs_bg_thread, c, "%s", c->bgt_name);
 	if (IS_ERR(c->bgt)) {
 		err = PTR_ERR(c->bgt);
 		c->bgt = NULL;
@@ -1788,7 +1794,6 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 			  c->bgt_name, err);
 		goto out;
 	}
-	wake_up_process(c->bgt);
 
 	c->orph_buf = vmalloc(c->leb_size);
 	if (!c->orph_buf) {
@@ -1853,7 +1858,6 @@ out:
 		kthread_stop(c->bgt);
 		c->bgt = NULL;
 	}
-	free_wbufs(c);
 	kfree(c->write_reserve_buf);
 	c->write_reserve_buf = NULL;
 	vfree(c->ileb_buf);
@@ -2436,14 +2440,20 @@ 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 +2472,7 @@ 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..7acc5a74e5fa
--- /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);
+}
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index c38066ce9ab0..f55828c0a300 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -27,6 +27,8 @@
 #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>
@@ -156,6 +158,13 @@
 #endif
 
 /*
+ * 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)
+
+/*
  * Lockdep classes for UBIFS inode @ui_mutex.
  */
 enum {
@@ -990,6 +999,18 @@ struct ubifs_budg_info {
 	int dent_budget;
 };
 
+/**
+ * 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;
+};
+
 struct ubifs_debug_info;
 
 /**
@@ -1251,6 +1272,10 @@ 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 +1311,9 @@ 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 +1521,7 @@ 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;
@@ -2072,6 +2101,12 @@ void ubifs_compress(const struct ubifs_info *c, const void *in_buf, int in_len,
 int ubifs_decompress(const struct ubifs_info *c, const void *buf, int len,
 		     void *out, int *out_len, int compr_type);
 
+/* sysfs.c */
+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);
+
 #include "debug.h"
 #include "misc.h"
 #include "key.h"