Merge branch 'linux-next' of git://git.infradead.org/ubi-2.6

* 'linux-next' of git://git.infradead.org/ubi-2.6:
  UBI: clarify the volume notification types' doc
  UBI: remove dead code
  UBI: dump stack when switching to R/O mode
  UBI: fix oops in error path
  UBI: switch debugging tests knobs to debugfs
  UBI: make it possible to use struct ubi_device in debug.h
  UBI: prepare debugging stuff to further debugfs conversion
  UBI: use debugfs for the extra checks knobs
  UBI: change the interface of a debugging check function

10 files changed, 406 insertions, 110 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 65626c1c446..6c3fb5ab20f 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -953,10 +953,14 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	if (!ubi->peb_buf2)
 		goto out_free;
 
+	err = ubi_debugging_init_dev(ubi);
+	if (err)
+		goto out_free;
+
 	err = attach_by_scanning(ubi);
 	if (err) {
 		dbg_err("failed to attach by scanning, error %d", err);
-		goto out_free;
+		goto out_debugging;
 	}
 
 	if (ubi->autoresize_vol_id != -1) {
@@ -969,12 +973,16 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	if (err)
 		goto out_detach;
 
+	err = ubi_debugfs_init_dev(ubi);
+	if (err)
+		goto out_uif;
+
 	ubi->bgt_thread = kthread_create(ubi_thread, ubi, ubi->bgt_name);
 	if (IS_ERR(ubi->bgt_thread)) {
 		err = PTR_ERR(ubi->bgt_thread);
 		ubi_err("cannot spawn \"%s\", error %d", ubi->bgt_name,
 			err);
-		goto out_uif;
+		goto out_debugfs;
 	}
 
 	ubi_msg("attached mtd%d to ubi%d", mtd->index, ubi_num);
@@ -1008,12 +1016,18 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
 	return ubi_num;
 
+out_debugfs:
+	ubi_debugfs_exit_dev(ubi);
 out_uif:
+	get_device(&ubi->dev);
+	ubi_assert(ref);
 	uif_close(ubi);
 out_detach:
 	ubi_wl_close(ubi);
 	free_internal_volumes(ubi);
 	vfree(ubi->vtbl);
+out_debugging:
+	ubi_debugging_exit_dev(ubi);
 out_free:
 	vfree(ubi->peb_buf1);
 	vfree(ubi->peb_buf2);
@@ -1080,11 +1094,13 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
 	 */
 	get_device(&ubi->dev);
 
+	ubi_debugfs_exit_dev(ubi);
 	uif_close(ubi);
 	ubi_wl_close(ubi);
 	free_internal_volumes(ubi);
 	vfree(ubi->vtbl);
 	put_mtd_device(ubi->mtd);
+	ubi_debugging_exit_dev(ubi);
 	vfree(ubi->peb_buf1);
 	vfree(ubi->peb_buf2);
 	ubi_msg("mtd%d is detached from ubi%d", ubi->mtd->index, ubi->ubi_num);
@@ -1199,6 +1215,11 @@ static int __init ubi_init(void)
 	if (!ubi_wl_entry_slab)
 		goto out_dev_unreg;
 
+	err = ubi_debugfs_init();
+	if (err)
+		goto out_slab;
+
+
 	/* Attach MTD devices */
 	for (i = 0; i < mtd_devs; i++) {
 		struct mtd_dev_param *p = &mtd_dev_param[i];
@@ -1247,6 +1268,8 @@ out_detach:
 			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
 			mutex_unlock(&ubi_devices_mutex);
 		}
+	ubi_debugfs_exit();
+out_slab:
 	kmem_cache_destroy(ubi_wl_entry_slab);
 out_dev_unreg:
 	misc_deregister(&ubi_ctrl_cdev);
@@ -1270,6 +1293,7 @@ static void __exit ubi_exit(void)
 			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
 			mutex_unlock(&ubi_devices_mutex);
 		}
+	ubi_debugfs_exit();
 	kmem_cache_destroy(ubi_wl_entry_slab);
 	misc_deregister(&ubi_ctrl_cdev);
 	class_remove_file(ubi_class, &ubi_version);
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 2224cbe41dd..ab80c0debac 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -27,17 +27,9 @@
 #ifdef CONFIG_MTD_UBI_DEBUG
 
 #include "ubi.h"
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
 #include <linux/module.h>
-#include <linux/moduleparam.h>
-
-unsigned int ubi_chk_flags;
-unsigned int ubi_tst_flags;
-
-module_param_named(debug_chks, ubi_chk_flags, uint, S_IRUGO | S_IWUSR);
-module_param_named(debug_tsts, ubi_chk_flags, uint, S_IRUGO | S_IWUSR);
-
-MODULE_PARM_DESC(debug_chks, "Debug check flags");
-MODULE_PARM_DESC(debug_tsts, "Debug special test flags");
 
 /**
  * ubi_dbg_dump_ec_hdr - dump an erase counter header.
@@ -239,4 +231,261 @@ out:
 	return;
 }
 
+/**
+ * ubi_debugging_init_dev - initialize debugging for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function initializes debugging-related data for UBI device @ubi.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubi_debugging_init_dev(struct ubi_device *ubi)
+{
+	ubi->dbg = kzalloc(sizeof(struct ubi_debug_info), GFP_KERNEL);
+	if (!ubi->dbg)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * ubi_debugging_exit_dev - free debugging data for an UBI device.
+ * @ubi: UBI device description object
+ */
+void ubi_debugging_exit_dev(struct ubi_device *ubi)
+{
+	kfree(ubi->dbg);
+}
+
+/*
+ * Root directory for UBI stuff in debugfs. Contains sub-directories which
+ * contain the stuff specific to particular UBI devices.
+ */
+static struct dentry *dfs_rootdir;
+
+/**
+ * ubi_debugfs_init - create UBI debugfs directory.
+ *
+ * Create UBI debugfs directory. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+int ubi_debugfs_init(void)
+{
+	dfs_rootdir = debugfs_create_dir("ubi", NULL);
+	if (IS_ERR_OR_NULL(dfs_rootdir)) {
+		int err = dfs_rootdir ? -ENODEV : PTR_ERR(dfs_rootdir);
+
+		ubi_err("cannot create \"ubi\" debugfs directory, error %d\n",
+			err);
+		return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit - remove UBI debugfs directory.
+ */
+void ubi_debugfs_exit(void)
+{
+	debugfs_remove(dfs_rootdir);
+}
+
+/* Read an UBI debugfs file */
+static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
+			     size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	char buf[3];
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = ubi->dbg;
+
+	if (dent == d->dfs_chk_gen)
+		val = d->chk_gen;
+	else if (dent == d->dfs_chk_io)
+		val = d->chk_io;
+	else if (dent == d->dfs_disable_bgt)
+		val = d->disable_bgt;
+	else if (dent == d->dfs_emulate_bitflips)
+		val = d->emulate_bitflips;
+	else if (dent == d->dfs_emulate_io_failures)
+		val = d->emulate_io_failures;
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (val)
+		buf[0] = '1';
+	else
+		buf[0] = '0';
+	buf[1] = '\n';
+	buf[2] = 0x00;
+
+	count = simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* Write an UBI debugfs file */
+static ssize_t dfs_file_write(struct file *file, const char __user *user_buf,
+			      size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	size_t buf_size;
+	char buf[8];
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = ubi->dbg;
+
+	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
+	if (copy_from_user(buf, user_buf, buf_size)) {
+		count = -EFAULT;
+		goto out;
+	}
+
+	if (buf[0] == '1')
+		val = 1;
+	else if (buf[0] == '0')
+		val = 0;
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (dent == d->dfs_chk_gen)
+		d->chk_gen = val;
+	else if (dent == d->dfs_chk_io)
+		d->chk_io = val;
+	else if (dent == d->dfs_disable_bgt)
+		d->disable_bgt = val;
+	else if (dent == d->dfs_emulate_bitflips)
+		d->emulate_bitflips = val;
+	else if (dent == d->dfs_emulate_io_failures)
+		d->emulate_io_failures = val;
+	else
+		count = -EINVAL;
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+static int default_open(struct inode *inode, struct file *file)
+{
+	if (inode->i_private)
+		file->private_data = inode->i_private;
+
+	return 0;
+}
+
+/* File operations for all UBI debugfs files */
+static const struct file_operations dfs_fops = {
+	.read   = dfs_file_read,
+	.write  = dfs_file_write,
+	.open   = default_open,
+	.llseek = no_llseek,
+	.owner  = THIS_MODULE,
+};
+
+/**
+ * ubi_debugfs_init_dev - initialize debugfs for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function creates all debugfs files for UBI device @ubi. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+int ubi_debugfs_init_dev(struct ubi_device *ubi)
+{
+	int err, n;
+	unsigned long ubi_num = ubi->ubi_num;
+	const char *fname;
+	struct dentry *dent;
+	struct ubi_debug_info *d = ubi->dbg;
+
+	n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
+		     ubi->ubi_num);
+	if (n == UBI_DFS_DIR_LEN) {
+		/* The array size is too small */
+		fname = UBI_DFS_DIR_NAME;
+		dent = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	fname = d->dfs_dir_name;
+	dent = debugfs_create_dir(fname, dfs_rootdir);
+	if (IS_ERR_OR_NULL(dent))
+		goto out;
+	d->dfs_dir = dent;
+
+	fname = "chk_gen";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_gen = dent;
+
+	fname = "chk_io";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_io = dent;
+
+	fname = "tst_disable_bgt";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_disable_bgt = dent;
+
+	fname = "tst_emulate_bitflips";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_emulate_bitflips = dent;
+
+	fname = "tst_emulate_io_failures";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_emulate_io_failures = dent;
+
+	return 0;
+
+out_remove:
+	debugfs_remove_recursive(d->dfs_dir);
+out:
+	err = dent ? PTR_ERR(dent) : -ENODEV;
+	ubi_err("cannot create \"%s\" debugfs file or directory, error %d\n",
+		fname, err);
+	return err;
+}
+
+/**
+ * dbg_debug_exit_dev - free all debugfs files corresponding to device @ubi
+ * @ubi: UBI device description object
+ */
+void ubi_debugfs_exit_dev(struct ubi_device *ubi)
+{
+	debugfs_remove_recursive(ubi->dbg->dfs_dir);
+}
+
 #endif /* CONFIG_MTD_UBI_DEBUG */
diff --git a/drivers/mtd/ubi/debug.h b/drivers/mtd/ubi/debug.h
index 3f1a09c5c43..65b5b76cc37 100644
--- a/drivers/mtd/ubi/debug.h
+++ b/drivers/mtd/ubi/debug.h
@@ -21,14 +21,6 @@
 #ifndef __UBI_DEBUG_H__
 #define __UBI_DEBUG_H__
 
-struct ubi_ec_hdr;
-struct ubi_vid_hdr;
-struct ubi_volume;
-struct ubi_vtbl_record;
-struct ubi_scan_volume;
-struct ubi_scan_leb;
-struct ubi_mkvol_req;
-
 #ifdef CONFIG_MTD_UBI_DEBUG
 #include <linux/random.h>
 
@@ -71,86 +63,103 @@ void ubi_dbg_dump_sv(const struct ubi_scan_volume *sv);
 void ubi_dbg_dump_seb(const struct ubi_scan_leb *seb, int type);
 void ubi_dbg_dump_mkvol_req(const struct ubi_mkvol_req *req);
 void ubi_dbg_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len);
-
-extern unsigned int ubi_chk_flags;
-
-/*
- * Debugging check flags.
- *
- * UBI_CHK_GEN: general checks
- * UBI_CHK_IO: check writes and erases
- */
-enum {
-	UBI_CHK_GEN = 0x1,
-	UBI_CHK_IO  = 0x2,
-};
-
 int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len);
 int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
 			int offset, int len);
-
-extern unsigned int ubi_tst_flags;
+int ubi_debugging_init_dev(struct ubi_device *ubi);
+void ubi_debugging_exit_dev(struct ubi_device *ubi);
+int ubi_debugfs_init(void);
+void ubi_debugfs_exit(void);
+int ubi_debugfs_init_dev(struct ubi_device *ubi);
+void ubi_debugfs_exit_dev(struct ubi_device *ubi);
 
 /*
- * Special testing flags.
+ * The UBI debugfs directory name pattern and maximum name length (3 for "ubi"
+ * + 2 for the number plus 1 for the trailing zero byte.
+ */
+#define UBI_DFS_DIR_NAME "ubi%d"
+#define UBI_DFS_DIR_LEN  (3 + 2 + 1)
+
+/**
+ * struct ubi_debug_info - debugging information for an UBI device.
  *
- * UBIFS_TST_DISABLE_BGT: disable the background thread
- * UBI_TST_EMULATE_BITFLIPS: emulate bit-flips
- * UBI_TST_EMULATE_WRITE_FAILURES: emulate write failures
- * UBI_TST_EMULATE_ERASE_FAILURES: emulate erase failures
+ * @chk_gen: if UBI general extra checks are enabled
+ * @chk_io: if UBI I/O extra checks are enabled
+ * @disable_bgt: disable the background task for testing purposes
+ * @emulate_bitflips: emulate bit-flips for testing purposes
+ * @emulate_io_failures: emulate write/erase failures for testing purposes
+ * @dfs_dir_name: name of debugfs directory containing files of this UBI device
+ * @dfs_dir: direntry object of the UBI device debugfs directory
+ * @dfs_chk_gen: debugfs knob to enable UBI general extra checks
+ * @dfs_chk_io: debugfs knob to enable UBI I/O extra checks
+ * @dfs_disable_bgt: debugfs knob to disable the background task
+ * @dfs_emulate_bitflips: debugfs knob to emulate bit-flips
+ * @dfs_emulate_io_failures: debugfs knob to emulate write/erase failures
  */
-enum {
-	UBI_TST_DISABLE_BGT            = 0x1,
-	UBI_TST_EMULATE_BITFLIPS       = 0x2,
-	UBI_TST_EMULATE_WRITE_FAILURES = 0x4,
-	UBI_TST_EMULATE_ERASE_FAILURES = 0x8,
+struct ubi_debug_info {
+	unsigned int chk_gen:1;
+	unsigned int chk_io:1;
+	unsigned int disable_bgt:1;
+	unsigned int emulate_bitflips:1;
+	unsigned int emulate_io_failures:1;
+	char dfs_dir_name[UBI_DFS_DIR_LEN + 1];
+	struct dentry *dfs_dir;
+	struct dentry *dfs_chk_gen;
+	struct dentry *dfs_chk_io;
+	struct dentry *dfs_disable_bgt;
+	struct dentry *dfs_emulate_bitflips;
+	struct dentry *dfs_emulate_io_failures;
 };
 
 /**
  * ubi_dbg_is_bgt_disabled - if the background thread is disabled.
+ * @ubi: UBI device description object
  *
  * Returns non-zero if the UBI background thread is disabled for testing
  * purposes.
  */
-static inline int ubi_dbg_is_bgt_disabled(void)
+static inline int ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)
 {
-	return ubi_tst_flags & UBI_TST_DISABLE_BGT;
+	return ubi->dbg->disable_bgt;
 }
 
 /**
  * ubi_dbg_is_bitflip - if it is time to emulate a bit-flip.
+ * @ubi: UBI device description object
  *
  * Returns non-zero if a bit-flip should be emulated, otherwise returns zero.
  */
-static inline int ubi_dbg_is_bitflip(void)
+static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
 {
-	if (ubi_tst_flags & UBI_TST_EMULATE_BITFLIPS)
+	if (ubi->dbg->emulate_bitflips)
 		return !(random32() % 200);
 	return 0;
 }
 
 /**
  * ubi_dbg_is_write_failure - if it is time to emulate a write failure.
+ * @ubi: UBI device description object
  *
  * Returns non-zero if a write failure should be emulated, otherwise returns
  * zero.
  */
-static inline int ubi_dbg_is_write_failure(void)
+static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
 {
-	if (ubi_tst_flags & UBI_TST_EMULATE_WRITE_FAILURES)
+	if (ubi->dbg->emulate_io_failures)
 		return !(random32() % 500);
 	return 0;
 }
 
 /**
  * ubi_dbg_is_erase_failure - if its time to emulate an erase failure.
+ * @ubi: UBI device description object
  *
  * Returns non-zero if an erase failure should be emulated, otherwise returns
  * zero.
  */
-static inline int ubi_dbg_is_erase_failure(void)
+static inline int ubi_dbg_is_erase_failure(const struct ubi_device *ubi)
 {
-	if (ubi_tst_flags & UBI_TST_EMULATE_ERASE_FAILURES)
+	if (ubi->dbg->emulate_io_failures)
 		return !(random32() % 400);
 	return 0;
 }
@@ -201,11 +210,6 @@ static inline void ubi_dbg_dump_flash(struct ubi_device *ubi,
 static inline void
 ubi_dbg_print_hex_dump(const char *l, const char *ps, int pt, int r,
 		       int g, const void *b, size_t len, bool a)     { return; }
-
-static inline int ubi_dbg_is_bgt_disabled(void)                    { return 0; }
-static inline int ubi_dbg_is_bitflip(void)                         { return 0; }
-static inline int ubi_dbg_is_write_failure(void)                   { return 0; }
-static inline int ubi_dbg_is_erase_failure(void)                   { return 0; }
 static inline int ubi_dbg_check_all_ff(struct ubi_device *ubi,
 				       int pnum, int offset,
 				       int len)                    { return 0; }
@@ -213,5 +217,20 @@ static inline int ubi_dbg_check_write(struct ubi_device *ubi,
 				      const void *buf, int pnum,
 				      int offset, int len)         { return 0; }
 
+static inline int ubi_debugging_init_dev(struct ubi_device *ubi)   { return 0; }
+static inline void ubi_debugging_exit_dev(struct ubi_device *ubi)  { return; }
+static inline int ubi_debugfs_init(void)                           { return 0; }
+static inline void ubi_debugfs_exit(void)                          { return; }
+static inline int ubi_debugfs_init_dev(struct ubi_device *ubi)     { return 0; }
+static inline void ubi_debugfs_exit_dev(struct ubi_device *ubi)    { return; }
+
+static inline int
+ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)              { return 0; }
+static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi) { return 0; }
+static inline int
+ubi_dbg_is_write_failure(const struct ubi_device *ubi)             { return 0; }
+static inline int
+ubi_dbg_is_erase_failure(const struct ubi_device *ubi)             { return 0; }
+
 #endif /* !CONFIG_MTD_UBI_DEBUG */
 #endif /* !__UBI_DEBUG_H__ */
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 8c1b1c7bc4a..6ba55c23587 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -212,7 +212,7 @@ retry:
 	} else {
 		ubi_assert(len == read);
 
-		if (ubi_dbg_is_bitflip()) {
+		if (ubi_dbg_is_bitflip(ubi)) {
 			dbg_gen("bit-flip (emulated)");
 			err = UBI_IO_BITFLIPS;
 		}
@@ -281,7 +281,7 @@ int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
 			return err;
 	}
 
-	if (ubi_dbg_is_write_failure()) {
+	if (ubi_dbg_is_write_failure(ubi)) {
 		dbg_err("cannot write %d bytes to PEB %d:%d "
 			"(emulated)", len, pnum, offset);
 		ubi_dbg_dump_stack();
@@ -396,7 +396,7 @@ retry:
 	if (err)
 		return err;
 
-	if (ubi_dbg_is_erase_failure()) {
+	if (ubi_dbg_is_erase_failure(ubi)) {
 		dbg_err("cannot erase PEB %d (emulated)", pnum);
 		return -EIO;
 	}
@@ -1146,7 +1146,7 @@ static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum)
 {
 	int err;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	err = ubi_io_is_bad(ubi, pnum);
@@ -1173,7 +1173,7 @@ static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
 	int err;
 	uint32_t magic;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	magic = be32_to_cpu(ec_hdr->magic);
@@ -1211,7 +1211,7 @@ static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum)
 	uint32_t crc, hdr_crc;
 	struct ubi_ec_hdr *ec_hdr;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
@@ -1255,7 +1255,7 @@ static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
 	int err;
 	uint32_t magic;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	magic = be32_to_cpu(vid_hdr->magic);
@@ -1296,7 +1296,7 @@ static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
 	struct ubi_vid_hdr *vid_hdr;
 	void *p;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
@@ -1348,7 +1348,7 @@ int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
 	void *buf1;
 	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	buf1 = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);
@@ -1412,7 +1412,7 @@ int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
 	void *buf;
 	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	buf = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index 2135a53732f..a3a198f9b98 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -1347,7 +1347,7 @@ static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si)
 	struct ubi_scan_leb *seb, *last_seb;
 	uint8_t *buf;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	/*
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index c6c22295898..dc64c767fd2 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -44,7 +44,6 @@
 
 #include "ubi-media.h"
 #include "scan.h"
-#include "debug.h"
 
 /* Maximum number of supported UBI devices */
 #define UBI_MAX_DEVICES 32
@@ -390,6 +389,8 @@ struct ubi_wl_entry;
  * @peb_buf2: another buffer of PEB size used for different purposes
  * @buf_mutex: protects @peb_buf1 and @peb_buf2
  * @ckvol_mutex: serializes static volume checking when opening
+ *
+ * @dbg: debugging information for this UBI device
  */
 struct ubi_device {
 	struct cdev cdev;
@@ -472,8 +473,12 @@ struct ubi_device {
 	void *peb_buf2;
 	struct mutex buf_mutex;
 	struct mutex ckvol_mutex;
+
+	struct ubi_debug_info *dbg;
 };
 
+#include "debug.h"
+
 extern struct kmem_cache *ubi_wl_entry_slab;
 extern const struct file_operations ubi_ctrl_cdev_operations;
 extern const struct file_operations ubi_cdev_operations;
@@ -662,6 +667,7 @@ static inline void ubi_ro_mode(struct ubi_device *ubi)
 	if (!ubi->ro_mode) {
 		ubi->ro_mode = 1;
 		ubi_warn("switch to read-only mode");
+		ubi_dbg_dump_stack();
 	}
 }
 
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 366eb70219a..97e093d1967 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -871,7 +871,7 @@ static int paranoid_check_volumes(struct ubi_device *ubi)
 {
 	int i, err = 0;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	for (i = 0; i < ubi->vtbl_slots; i++) {
diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index fd3bf770f51..4b50a3029b8 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -307,8 +307,7 @@ static int create_vtbl(struct ubi_device *ubi, struct ubi_scan_info *si,
 {
 	int err, tries = 0;
 	static struct ubi_vid_hdr *vid_hdr;
-	struct ubi_scan_volume *sv;
-	struct ubi_scan_leb *new_seb, *old_seb = NULL;
+	struct ubi_scan_leb *new_seb;
 
 	ubi_msg("create volume table (copy #%d)", copy + 1);
 
@@ -316,15 +315,6 @@ static int create_vtbl(struct ubi_device *ubi, struct ubi_scan_info *si,
 	if (!vid_hdr)
 		return -ENOMEM;
 
-	/*
-	 * Check if there is a logical eraseblock which would have to contain
-	 * this volume table copy was found during scanning. It has to be wiped
-	 * out.
-	 */
-	sv = ubi_scan_find_sv(si, UBI_LAYOUT_VOLUME_ID);
-	if (sv)
-		old_seb = ubi_scan_find_seb(sv, copy);
-
 retry:
 	new_seb = ubi_scan_get_free_peb(ubi, si);
 	if (IS_ERR(new_seb)) {
@@ -351,8 +341,8 @@ retry:
 		goto write_error;
 
 	/*
-	 * And add it to the scanning information. Don't delete the old
-	 * @old_seb as it will be deleted and freed in 'ubi_scan_add_used()'.
+	 * And add it to the scanning information. Don't delete the old version
+	 * of this LEB as it will be deleted and freed in 'ubi_scan_add_used()'.
 	 */
 	err = ubi_scan_add_used(ubi, si, new_seb->pnum, new_seb->ec,
 				vid_hdr, 0);
@@ -876,7 +866,7 @@ out_free:
  */
 static void paranoid_vtbl_check(const struct ubi_device *ubi)
 {
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return;
 
 	if (vtbl_check(ubi, ubi->vtbl)) {
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index ff2c4956eef..42c684cf368 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1,4 +1,5 @@
 /*
+ * @ubi: UBI device description object
  * Copyright (c) International Business Machines Corp., 2006
  *
  * This program is free software; you can redistribute it and/or modify
@@ -163,12 +164,14 @@ struct ubi_work {
 
 #ifdef CONFIG_MTD_UBI_DEBUG
 static int paranoid_check_ec(struct ubi_device *ubi, int pnum, int ec);
-static int paranoid_check_in_wl_tree(struct ubi_wl_entry *e,
+static int paranoid_check_in_wl_tree(const struct ubi_device *ubi,
+				     struct ubi_wl_entry *e,
 				     struct rb_root *root);
-static int paranoid_check_in_pq(struct ubi_device *ubi, struct ubi_wl_entry *e);
+static int paranoid_check_in_pq(const struct ubi_device *ubi,
+				struct ubi_wl_entry *e);
 #else
 #define paranoid_check_ec(ubi, pnum, ec) 0
-#define paranoid_check_in_wl_tree(e, root)
+#define paranoid_check_in_wl_tree(ubi, e, root)
 #define paranoid_check_in_pq(ubi, e) 0
 #endif
 
@@ -449,7 +452,7 @@ retry:
 		BUG();
 	}
 
-	paranoid_check_in_wl_tree(e, &ubi->free);
+	paranoid_check_in_wl_tree(ubi, e, &ubi->free);
 
 	/*
 	 * Move the physical eraseblock to the protection queue where it will
@@ -613,7 +616,7 @@ static void schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
 	list_add_tail(&wrk->list, &ubi->works);
 	ubi_assert(ubi->works_count >= 0);
 	ubi->works_count += 1;
-	if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled())
+	if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled(ubi))
 		wake_up_process(ubi->bgt_thread);
 	spin_unlock(&ubi->wl_lock);
 }
@@ -712,7 +715,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 			       e1->ec, e2->ec);
 			goto out_cancel;
 		}
-		paranoid_check_in_wl_tree(e1, &ubi->used);
+		paranoid_check_in_wl_tree(ubi, e1, &ubi->used);
 		rb_erase(&e1->u.rb, &ubi->used);
 		dbg_wl("move PEB %d EC %d to PEB %d EC %d",
 		       e1->pnum, e1->ec, e2->pnum, e2->ec);
@@ -721,12 +724,12 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 		scrubbing = 1;
 		e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, u.rb);
 		e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF);
-		paranoid_check_in_wl_tree(e1, &ubi->scrub);
+		paranoid_check_in_wl_tree(ubi, e1, &ubi->scrub);
 		rb_erase(&e1->u.rb, &ubi->scrub);
 		dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum);
 	}
 
-	paranoid_check_in_wl_tree(e2, &ubi->free);
+	paranoid_check_in_wl_tree(ubi, e2, &ubi->free);
 	rb_erase(&e2->u.rb, &ubi->free);
 	ubi->move_from = e1;
 	ubi->move_to = e2;
@@ -1169,13 +1172,13 @@ retry:
 		return 0;
 	} else {
 		if (in_wl_tree(e, &ubi->used)) {
-			paranoid_check_in_wl_tree(e, &ubi->used);
+			paranoid_check_in_wl_tree(ubi, e, &ubi->used);
 			rb_erase(&e->u.rb, &ubi->used);
 		} else if (in_wl_tree(e, &ubi->scrub)) {
-			paranoid_check_in_wl_tree(e, &ubi->scrub);
+			paranoid_check_in_wl_tree(ubi, e, &ubi->scrub);
 			rb_erase(&e->u.rb, &ubi->scrub);
 		} else if (in_wl_tree(e, &ubi->erroneous)) {
-			paranoid_check_in_wl_tree(e, &ubi->erroneous);
+			paranoid_check_in_wl_tree(ubi, e, &ubi->erroneous);
 			rb_erase(&e->u.rb, &ubi->erroneous);
 			ubi->erroneous_peb_count -= 1;
 			ubi_assert(ubi->erroneous_peb_count >= 0);
@@ -1242,7 +1245,7 @@ retry:
 	}
 
 	if (in_wl_tree(e, &ubi->used)) {
-		paranoid_check_in_wl_tree(e, &ubi->used);
+		paranoid_check_in_wl_tree(ubi, e, &ubi->used);
 		rb_erase(&e->u.rb, &ubi->used);
 	} else {
 		int err;
@@ -1364,7 +1367,7 @@ int ubi_thread(void *u)
 
 		spin_lock(&ubi->wl_lock);
 		if (list_empty(&ubi->works) || ubi->ro_mode ||
-		    !ubi->thread_enabled || ubi_dbg_is_bgt_disabled()) {
+		    !ubi->thread_enabled || ubi_dbg_is_bgt_disabled(ubi)) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			spin_unlock(&ubi->wl_lock);
 			schedule();
@@ -1579,7 +1582,7 @@ static int paranoid_check_ec(struct ubi_device *ubi, int pnum, int ec)
 	long long read_ec;
 	struct ubi_ec_hdr *ec_hdr;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
@@ -1609,16 +1612,18 @@ out_free:
 
 /**
  * paranoid_check_in_wl_tree - check that wear-leveling entry is in WL RB-tree.
+ * @ubi: UBI device description object
  * @e: the wear-leveling entry to check
  * @root: the root of the tree
  *
  * This function returns zero if @e is in the @root RB-tree and %-EINVAL if it
  * is not.
  */
-static int paranoid_check_in_wl_tree(struct ubi_wl_entry *e,
+static int paranoid_check_in_wl_tree(const struct ubi_device *ubi,
+				     struct ubi_wl_entry *e,
 				     struct rb_root *root)
 {
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	if (in_wl_tree(e, root))
@@ -1638,12 +1643,13 @@ static int paranoid_check_in_wl_tree(struct ubi_wl_entry *e,
  *
  * This function returns zero if @e is in @ubi->pq and %-EINVAL if it is not.
  */
-static int paranoid_check_in_pq(struct ubi_device *ubi, struct ubi_wl_entry *e)
+static int paranoid_check_in_pq(const struct ubi_device *ubi,
+				struct ubi_wl_entry *e)
 {
 	struct ubi_wl_entry *p;
 	int i;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i)
diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
index 15da0e99f48..db4836bed51 100644
--- a/include/linux/mtd/ubi.h
+++ b/include/linux/mtd/ubi.h
@@ -155,12 +155,14 @@ struct ubi_device_info {
 };
 
 /*
- * enum - volume notification types.
- * @UBI_VOLUME_ADDED: volume has been added
- * @UBI_VOLUME_REMOVED: start volume volume
- * @UBI_VOLUME_RESIZED: volume size has been re-sized
- * @UBI_VOLUME_RENAMED: volume name has been re-named
- * @UBI_VOLUME_UPDATED: volume name has been updated
+ * Volume notification types.
+ * @UBI_VOLUME_ADDED: a volume has been added (an UBI device was attached or a
+ *                    volume was created)
+ * @UBI_VOLUME_REMOVED: a volume has been removed (an UBI device was detached
+ *			or a volume was removed)
+ * @UBI_VOLUME_RESIZED: a volume has been re-sized
+ * @UBI_VOLUME_RENAMED: a volume has been re-named
+ * @UBI_VOLUME_UPDATED: data has been written to a volume
  *
  * These constants define which type of event has happened when a volume
  * notification function is invoked.