diff --git a/Documentation/filesystems/ubifs.txt b/Documentation/filesystems/ubifs.txt
index 8e4fab6..a0a61d2 100644
--- a/Documentation/filesystems/ubifs.txt
+++ b/Documentation/filesystems/ubifs.txt
@@ -111,34 +111,6 @@
 to UBI and mount volume "rootfs":
 ubi.mtd=0 root=ubi0:rootfs rootfstype=ubifs
 
-
-Module Parameters for Debugging
-===============================
-
-When UBIFS has been compiled with debugging enabled, there are 2 module
-parameters that are available to control aspects of testing and debugging.
-
-debug_chks	Selects extra checks that UBIFS can do while running:
-
-		Check					Flag value
-
-		General checks				1
-		Check Tree Node Cache (TNC)		2
-		Check indexing tree size		4
-		Check orphan area			8
-		Check old indexing tree			16
-		Check LEB properties (lprops)		32
-		Check leaf nodes and inodes		64
-
-debug_tsts	Selects a mode of testing, as follows:
-
-		Test mode				Flag value
-
-		Failure mode for recovery testing	4
-
-For example, set debug_chks to 3 to enable general and TNC checks.
-
-
 References
 ==========
 
diff --git a/MAINTAINERS b/MAINTAINERS
index 187282d..72b979d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1,4 +1,5 @@
 
+
 	List of maintainers and how to submit kernel changes
 
 Please try to follow the guidelines below.  This will make things
@@ -6321,7 +6322,7 @@
 
 UBI FILE SYSTEM (UBIFS)
 M:	Artem Bityutskiy <dedekind1@gmail.com>
-M:	Adrian Hunter <adrian.hunter@nokia.com>
+M:	Adrian Hunter <adrian.hunter@intel.com>
 L:	linux-mtd@lists.infradead.org
 T:	git git://git.infradead.org/ubifs-2.6.git
 W:	http://www.linux-mtd.infradead.org/doc/ubifs.html
diff --git a/fs/ubifs/commit.c b/fs/ubifs/commit.c
index 87cd0ea..fb3b5c8 100644
--- a/fs/ubifs/commit.c
+++ b/fs/ubifs/commit.c
@@ -78,7 +78,7 @@
 	 * If the root TNC node is dirty, we definitely have something to
 	 * commit.
 	 */
-	if (c->zroot.znode && test_bit(DIRTY_ZNODE, &c->zroot.znode->flags))
+	if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode))
 		return 0;
 
 	/*
@@ -418,7 +418,7 @@
 
 	spin_lock(&c->cs_lock);
 	if (c->cmt_state == COMMIT_BROKEN) {
-		err = -EINVAL;
+		err = -EROFS;
 		goto out;
 	}
 
@@ -444,7 +444,7 @@
 	 * re-check it.
 	 */
 	if (c->cmt_state == COMMIT_BROKEN) {
-		err = -EINVAL;
+		err = -EROFS;
 		goto out_cmt_unlock;
 	}
 
@@ -576,7 +576,7 @@
 	struct idx_node *i;
 	size_t sz;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_OLD_IDX))
+	if (!dbg_is_chk_index(c))
 		return 0;
 
 	INIT_LIST_HEAD(&list);
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 0bb2bce..eef109a 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -27,13 +27,12 @@
  * various local functions of those subsystems.
  */
 
-#define UBIFS_DBG_PRESERVE_UBI
-
-#include "ubifs.h"
 #include <linux/module.h>
-#include <linux/moduleparam.h>
 #include <linux/debugfs.h>
 #include <linux/math64.h>
+#include <linux/uaccess.h>
+#include <linux/random.h>
+#include "ubifs.h"
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
 
@@ -42,15 +41,6 @@
 static char dbg_key_buf0[128];
 static char dbg_key_buf1[128];
 
-unsigned int ubifs_chk_flags;
-unsigned int ubifs_tst_flags;
-
-module_param_named(debug_chks, ubifs_chk_flags, uint, S_IRUGO | S_IWUSR);
-module_param_named(debug_tsts, ubifs_tst_flags, uint, S_IRUGO | S_IWUSR);
-
-MODULE_PARM_DESC(debug_chks, "Debug check flags");
-MODULE_PARM_DESC(debug_tsts, "Debug special test flags");
-
 static const char *get_key_fmt(int fmt)
 {
 	switch (fmt) {
@@ -91,6 +81,28 @@
 	}
 }
 
+static const char *get_dent_type(int type)
+{
+	switch (type) {
+	case UBIFS_ITYPE_REG:
+		return "file";
+	case UBIFS_ITYPE_DIR:
+		return "dir";
+	case UBIFS_ITYPE_LNK:
+		return "symlink";
+	case UBIFS_ITYPE_BLK:
+		return "blkdev";
+	case UBIFS_ITYPE_CHR:
+		return "char dev";
+	case UBIFS_ITYPE_FIFO:
+		return "fifo";
+	case UBIFS_ITYPE_SOCK:
+		return "socket";
+	default:
+		return "unknown/invalid type";
+	}
+}
+
 static void sprintf_key(const struct ubifs_info *c, const union ubifs_key *key,
 			char *buffer)
 {
@@ -234,9 +246,13 @@
 	printk(KERN_DEBUG "\tlen            %u\n", le32_to_cpu(ch->len));
 }
 
-void dbg_dump_inode(const struct ubifs_info *c, const struct inode *inode)
+void dbg_dump_inode(struct ubifs_info *c, const struct inode *inode)
 {
 	const struct ubifs_inode *ui = ubifs_inode(inode);
+	struct qstr nm = { .name = NULL };
+	union ubifs_key key;
+	struct ubifs_dent_node *dent, *pdent = NULL;
+	int count = 2;
 
 	printk(KERN_DEBUG "Dump in-memory inode:");
 	printk(KERN_DEBUG "\tinode          %lu\n", inode->i_ino);
@@ -270,6 +286,32 @@
 	printk(KERN_DEBUG "\tlast_page_read %lu\n", ui->last_page_read);
 	printk(KERN_DEBUG "\tread_in_a_row  %lu\n", ui->read_in_a_row);
 	printk(KERN_DEBUG "\tdata_len       %d\n", ui->data_len);
+
+	if (!S_ISDIR(inode->i_mode))
+		return;
+
+	printk(KERN_DEBUG "List of directory entries:\n");
+	ubifs_assert(!mutex_is_locked(&c->tnc_mutex));
+
+	lowest_dent_key(c, &key, inode->i_ino);
+	while (1) {
+		dent = ubifs_tnc_next_ent(c, &key, &nm);
+		if (IS_ERR(dent)) {
+			if (PTR_ERR(dent) != -ENOENT)
+				printk(KERN_DEBUG "error %ld\n", PTR_ERR(dent));
+			break;
+		}
+
+		printk(KERN_DEBUG "\t%d: %s (%s)\n",
+		       count++, dent->name, get_dent_type(dent->type));
+
+		nm.name = dent->name;
+		nm.len = le16_to_cpu(dent->nlen);
+		kfree(pdent);
+		pdent = dent;
+		key_read(c, &dent->key, &key);
+	}
+	kfree(pdent);
 }
 
 void dbg_dump_node(const struct ubifs_info *c, const void *node)
@@ -278,7 +320,7 @@
 	union ubifs_key key;
 	const struct ubifs_ch *ch = node;
 
-	if (dbg_failure_mode)
+	if (dbg_is_tst_rcvry(c))
 		return;
 
 	/* If the magic is incorrect, just hexdump the first bytes */
@@ -834,7 +876,7 @@
 	struct ubifs_scan_node *snod;
 	void *buf;
 
-	if (dbg_failure_mode)
+	if (dbg_is_tst_rcvry(c))
 		return;
 
 	printk(KERN_DEBUG "(pid %d) start dumping LEB %d\n",
@@ -1080,6 +1122,7 @@
 
 /**
  * dbg_check_synced_i_size - check synchronized inode size.
+ * @c: UBIFS file-system description object
  * @inode: inode to check
  *
  * If inode is clean, synchronized inode size has to be equivalent to current
@@ -1087,12 +1130,12 @@
  * has to be locked). Returns %0 if synchronized inode size if correct, and
  * %-EINVAL if not.
  */
-int dbg_check_synced_i_size(struct inode *inode)
+int dbg_check_synced_i_size(const struct ubifs_info *c, struct inode *inode)
 {
 	int err = 0;
 	struct ubifs_inode *ui = ubifs_inode(inode);
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 	if (!S_ISREG(inode->i_mode))
 		return 0;
@@ -1125,7 +1168,7 @@
  * Note, it is good idea to make sure the @dir->i_mutex is locked before
  * calling this function.
  */
-int dbg_check_dir_size(struct ubifs_info *c, const struct inode *dir)
+int dbg_check_dir(struct ubifs_info *c, const struct inode *dir)
 {
 	unsigned int nlink = 2;
 	union ubifs_key key;
@@ -1133,7 +1176,7 @@
 	struct qstr nm = { .name = NULL };
 	loff_t size = UBIFS_INO_NODE_SZ;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 
 	if (!S_ISDIR(dir->i_mode))
@@ -1167,12 +1210,14 @@
 			  "but calculated size is %llu", dir->i_ino,
 			  (unsigned long long)i_size_read(dir),
 			  (unsigned long long)size);
+		dbg_dump_inode(c, dir);
 		dump_stack();
 		return -EINVAL;
 	}
 	if (dir->i_nlink != nlink) {
 		ubifs_err("directory inode %lu has nlink %u, but calculated "
 			  "nlink is %u", dir->i_ino, dir->i_nlink, nlink);
+		dbg_dump_inode(c, dir);
 		dump_stack();
 		return -EINVAL;
 	}
@@ -1489,7 +1534,7 @@
 	long clean_cnt = 0, dirty_cnt = 0;
 	int err, last;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_TNC))
+	if (!dbg_is_chk_index(c))
 		return 0;
 
 	ubifs_assert(mutex_is_locked(&c->tnc_mutex));
@@ -1736,7 +1781,7 @@
 	int err;
 	long long calc = 0;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_IDX_SZ))
+	if (!dbg_is_chk_index(c))
 		return 0;
 
 	err = dbg_walk_index(c, NULL, add_size, &calc);
@@ -2312,7 +2357,7 @@
 	int err;
 	struct fsck_data fsckd;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_FS))
+	if (!dbg_is_chk_fs(c))
 		return 0;
 
 	fsckd.inodes = RB_ROOT;
@@ -2347,7 +2392,7 @@
 	struct list_head *cur;
 	struct ubifs_scan_node *sa, *sb;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 
 	for (cur = head->next; cur->next != head; cur = cur->next) {
@@ -2414,7 +2459,7 @@
 	struct list_head *cur;
 	struct ubifs_scan_node *sa, *sb;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 
 	for (cur = head->next; cur->next != head; cur = cur->next) {
@@ -2491,214 +2536,141 @@
 	return 0;
 }
 
-int dbg_force_in_the_gaps(void)
+static inline int chance(unsigned int n, unsigned int out_of)
 {
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
-		return 0;
+	return !!((random32() % out_of) + 1 <= n);
 
-	return !(random32() & 7);
 }
 
-/* Failure mode for recovery testing */
-
-#define chance(n, d) (simple_rand() <= (n) * 32768LL / (d))
-
-struct failure_mode_info {
-	struct list_head list;
-	struct ubifs_info *c;
-};
-
-static LIST_HEAD(fmi_list);
-static DEFINE_SPINLOCK(fmi_lock);
-
-static unsigned int next;
-
-static int simple_rand(void)
+static int power_cut_emulated(struct ubifs_info *c, int lnum, int write)
 {
-	if (next == 0)
-		next = current->pid;
-	next = next * 1103515245 + 12345;
-	return (next >> 16) & 32767;
-}
+	struct ubifs_debug_info *d = c->dbg;
 
-static void failure_mode_init(struct ubifs_info *c)
-{
-	struct failure_mode_info *fmi;
+	ubifs_assert(dbg_is_tst_rcvry(c));
 
-	fmi = kmalloc(sizeof(struct failure_mode_info), GFP_NOFS);
-	if (!fmi) {
-		ubifs_err("Failed to register failure mode - no memory");
-		return;
-	}
-	fmi->c = c;
-	spin_lock(&fmi_lock);
-	list_add_tail(&fmi->list, &fmi_list);
-	spin_unlock(&fmi_lock);
-}
-
-static void failure_mode_exit(struct ubifs_info *c)
-{
-	struct failure_mode_info *fmi, *tmp;
-
-	spin_lock(&fmi_lock);
-	list_for_each_entry_safe(fmi, tmp, &fmi_list, list)
-		if (fmi->c == c) {
-			list_del(&fmi->list);
-			kfree(fmi);
-		}
-	spin_unlock(&fmi_lock);
-}
-
-static struct ubifs_info *dbg_find_info(struct ubi_volume_desc *desc)
-{
-	struct failure_mode_info *fmi;
-
-	spin_lock(&fmi_lock);
-	list_for_each_entry(fmi, &fmi_list, list)
-		if (fmi->c->ubi == desc) {
-			struct ubifs_info *c = fmi->c;
-
-			spin_unlock(&fmi_lock);
-			return c;
-		}
-	spin_unlock(&fmi_lock);
-	return NULL;
-}
-
-static int in_failure_mode(struct ubi_volume_desc *desc)
-{
-	struct ubifs_info *c = dbg_find_info(desc);
-
-	if (c && dbg_failure_mode)
-		return c->dbg->failure_mode;
-	return 0;
-}
-
-static int do_fail(struct ubi_volume_desc *desc, int lnum, int write)
-{
-	struct ubifs_info *c = dbg_find_info(desc);
-	struct ubifs_debug_info *d;
-
-	if (!c || !dbg_failure_mode)
-		return 0;
-	d = c->dbg;
-	if (d->failure_mode)
-		return 1;
-	if (!d->fail_cnt) {
-		/* First call - decide delay to failure */
+	if (!d->pc_cnt) {
+		/* First call - decide delay to the power cut */
 		if (chance(1, 2)) {
-			unsigned int delay = 1 << (simple_rand() >> 11);
+			unsigned long delay;
 
 			if (chance(1, 2)) {
-				d->fail_delay = 1;
-				d->fail_timeout = jiffies +
-						  msecs_to_jiffies(delay);
-				dbg_rcvry("failing after %ums", delay);
+				d->pc_delay = 1;
+				/* Fail withing 1 minute */
+				delay = random32() % 60000;
+				d->pc_timeout = jiffies;
+				d->pc_timeout += msecs_to_jiffies(delay);
+				ubifs_warn("failing after %lums", delay);
 			} else {
-				d->fail_delay = 2;
-				d->fail_cnt_max = delay;
-				dbg_rcvry("failing after %u calls", delay);
+				d->pc_delay = 2;
+				delay = random32() % 10000;
+				/* Fail within 10000 operations */
+				d->pc_cnt_max = delay;
+				ubifs_warn("failing after %lu calls", delay);
 			}
 		}
-		d->fail_cnt += 1;
+
+		d->pc_cnt += 1;
 	}
+
 	/* Determine if failure delay has expired */
-	if (d->fail_delay == 1) {
-		if (time_before(jiffies, d->fail_timeout))
+	if (d->pc_delay == 1 && time_before(jiffies, d->pc_timeout))
 			return 0;
-	} else if (d->fail_delay == 2)
-		if (d->fail_cnt++ < d->fail_cnt_max)
+	if (d->pc_delay == 2 && d->pc_cnt++ < d->pc_cnt_max)
 			return 0;
+
 	if (lnum == UBIFS_SB_LNUM) {
-		if (write) {
-			if (chance(1, 2))
-				return 0;
-		} else if (chance(19, 20))
+		if (write && chance(1, 2))
 			return 0;
-		dbg_rcvry("failing in super block LEB %d", lnum);
+		if (chance(19, 20))
+			return 0;
+		ubifs_warn("failing in super block LEB %d", lnum);
 	} else if (lnum == UBIFS_MST_LNUM || lnum == UBIFS_MST_LNUM + 1) {
 		if (chance(19, 20))
 			return 0;
-		dbg_rcvry("failing in master LEB %d", lnum);
+		ubifs_warn("failing in master LEB %d", lnum);
 	} else if (lnum >= UBIFS_LOG_LNUM && lnum <= c->log_last) {
-		if (write) {
-			if (chance(99, 100))
-				return 0;
-		} else if (chance(399, 400))
+		if (write && chance(99, 100))
 			return 0;
-		dbg_rcvry("failing in log LEB %d", lnum);
+		if (chance(399, 400))
+			return 0;
+		ubifs_warn("failing in log LEB %d", lnum);
 	} else if (lnum >= c->lpt_first && lnum <= c->lpt_last) {
-		if (write) {
-			if (chance(7, 8))
-				return 0;
-		} else if (chance(19, 20))
+		if (write && chance(7, 8))
 			return 0;
-		dbg_rcvry("failing in LPT LEB %d", lnum);
+		if (chance(19, 20))
+			return 0;
+		ubifs_warn("failing in LPT LEB %d", lnum);
 	} else if (lnum >= c->orph_first && lnum <= c->orph_last) {
-		if (write) {
-			if (chance(1, 2))
-				return 0;
-		} else if (chance(9, 10))
+		if (write && chance(1, 2))
 			return 0;
-		dbg_rcvry("failing in orphan LEB %d", lnum);
+		if (chance(9, 10))
+			return 0;
+		ubifs_warn("failing in orphan LEB %d", lnum);
 	} else if (lnum == c->ihead_lnum) {
 		if (chance(99, 100))
 			return 0;
-		dbg_rcvry("failing in index head LEB %d", lnum);
+		ubifs_warn("failing in index head LEB %d", lnum);
 	} else if (c->jheads && lnum == c->jheads[GCHD].wbuf.lnum) {
 		if (chance(9, 10))
 			return 0;
-		dbg_rcvry("failing in GC head LEB %d", lnum);
+		ubifs_warn("failing in GC head LEB %d", lnum);
 	} else if (write && !RB_EMPTY_ROOT(&c->buds) &&
 		   !ubifs_search_bud(c, lnum)) {
 		if (chance(19, 20))
 			return 0;
-		dbg_rcvry("failing in non-bud LEB %d", lnum);
+		ubifs_warn("failing in non-bud LEB %d", lnum);
 	} else if (c->cmt_state == COMMIT_RUNNING_BACKGROUND ||
 		   c->cmt_state == COMMIT_RUNNING_REQUIRED) {
 		if (chance(999, 1000))
 			return 0;
-		dbg_rcvry("failing in bud LEB %d commit running", lnum);
+		ubifs_warn("failing in bud LEB %d commit running", lnum);
 	} else {
 		if (chance(9999, 10000))
 			return 0;
-		dbg_rcvry("failing in bud LEB %d commit not running", lnum);
+		ubifs_warn("failing in bud LEB %d commit not running", lnum);
 	}
-	ubifs_err("*** SETTING FAILURE MODE ON (LEB %d) ***", lnum);
-	d->failure_mode = 1;
+
+	d->pc_happened = 1;
+	ubifs_warn("========== Power cut emulated ==========");
 	dump_stack();
 	return 1;
 }
 
-static void cut_data(const void *buf, int len)
+static void cut_data(const void *buf, unsigned int len)
 {
-	int flen, i;
+	unsigned int from, to, i, ffs = chance(1, 2);
 	unsigned char *p = (void *)buf;
 
-	flen = (len * (long long)simple_rand()) >> 15;
-	for (i = flen; i < len; i++)
-		p[i] = 0xff;
+	from = random32() % (len + 1);
+	if (chance(1, 2))
+		to = random32() % (len - from + 1);
+	else
+		to = len;
+
+	if (from < to)
+		ubifs_warn("filled bytes %u-%u with %s", from, to - 1,
+			   ffs ? "0xFFs" : "random data");
+
+	if (ffs)
+		for (i = from; i < to; i++)
+			p[i] = 0xFF;
+	else
+		for (i = from; i < to; i++)
+			p[i] = random32() % 0x100;
 }
 
-int dbg_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
-		 int len, int check)
-{
-	if (in_failure_mode(desc))
-		return -EROFS;
-	return ubi_leb_read(desc, lnum, buf, offset, len, check);
-}
-
-int dbg_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
-		  int offset, int len, int dtype)
+int dbg_leb_write(struct ubifs_info *c, int lnum, const void *buf,
+		  int offs, int len, int dtype)
 {
 	int err, failing;
 
-	if (in_failure_mode(desc))
+	if (c->dbg->pc_happened)
 		return -EROFS;
-	failing = do_fail(desc, lnum, 1);
+
+	failing = power_cut_emulated(c, lnum, 1);
 	if (failing)
 		cut_data(buf, len);
-	err = ubi_leb_write(desc, lnum, buf, offset, len, dtype);
+	err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
 	if (err)
 		return err;
 	if (failing)
@@ -2706,162 +2678,207 @@
 	return 0;
 }
 
-int dbg_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
+int dbg_leb_change(struct ubifs_info *c, int lnum, const void *buf,
 		   int len, int dtype)
 {
 	int err;
 
-	if (do_fail(desc, lnum, 1))
+	if (c->dbg->pc_happened)
 		return -EROFS;
-	err = ubi_leb_change(desc, lnum, buf, len, dtype);
+	if (power_cut_emulated(c, lnum, 1))
+		return -EROFS;
+	err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
 	if (err)
 		return err;
-	if (do_fail(desc, lnum, 1))
+	if (power_cut_emulated(c, lnum, 1))
 		return -EROFS;
 	return 0;
 }
 
-int dbg_leb_erase(struct ubi_volume_desc *desc, int lnum)
+int dbg_leb_unmap(struct ubifs_info *c, int lnum)
 {
 	int err;
 
-	if (do_fail(desc, lnum, 0))
+	if (c->dbg->pc_happened)
 		return -EROFS;
-	err = ubi_leb_erase(desc, lnum);
+	if (power_cut_emulated(c, lnum, 0))
+		return -EROFS;
+	err = ubi_leb_unmap(c->ubi, lnum);
 	if (err)
 		return err;
-	if (do_fail(desc, lnum, 0))
+	if (power_cut_emulated(c, lnum, 0))
 		return -EROFS;
 	return 0;
 }
 
-int dbg_leb_unmap(struct ubi_volume_desc *desc, int lnum)
+int dbg_leb_map(struct ubifs_info *c, int lnum, int dtype)
 {
 	int err;
 
-	if (do_fail(desc, lnum, 0))
+	if (c->dbg->pc_happened)
 		return -EROFS;
-	err = ubi_leb_unmap(desc, lnum);
+	if (power_cut_emulated(c, lnum, 0))
+		return -EROFS;
+	err = ubi_leb_map(c->ubi, lnum, dtype);
 	if (err)
 		return err;
-	if (do_fail(desc, lnum, 0))
+	if (power_cut_emulated(c, lnum, 0))
 		return -EROFS;
 	return 0;
 }
 
-int dbg_is_mapped(struct ubi_volume_desc *desc, int lnum)
-{
-	if (in_failure_mode(desc))
-		return -EROFS;
-	return ubi_is_mapped(desc, lnum);
-}
-
-int dbg_leb_map(struct ubi_volume_desc *desc, int lnum, int dtype)
-{
-	int err;
-
-	if (do_fail(desc, lnum, 0))
-		return -EROFS;
-	err = ubi_leb_map(desc, lnum, dtype);
-	if (err)
-		return err;
-	if (do_fail(desc, lnum, 0))
-		return -EROFS;
-	return 0;
-}
-
-/**
- * ubifs_debugging_init - initialize UBIFS debugging.
- * @c: UBIFS file-system description object
- *
- * This function initializes debugging-related data for the file system.
- * Returns zero in case of success and a negative error code in case of
- * failure.
- */
-int ubifs_debugging_init(struct ubifs_info *c)
-{
-	c->dbg = kzalloc(sizeof(struct ubifs_debug_info), GFP_KERNEL);
-	if (!c->dbg)
-		return -ENOMEM;
-
-	failure_mode_init(c);
-	return 0;
-}
-
-/**
- * ubifs_debugging_exit - free debugging data.
- * @c: UBIFS file-system description object
- */
-void ubifs_debugging_exit(struct ubifs_info *c)
-{
-	failure_mode_exit(c);
-	kfree(c->dbg);
-}
-
 /*
  * Root directory for UBIFS stuff in debugfs. Contains sub-directories which
  * contain the stuff specific to particular file-system mounts.
  */
 static struct dentry *dfs_rootdir;
 
-/**
- * dbg_debugfs_init - initialize debugfs file-system.
- *
- * UBIFS uses debugfs file-system to expose various debugging knobs to
- * user-space. This function creates "ubifs" directory in the debugfs
- * file-system. Returns zero in case of success and a negative error code in
- * case of failure.
- */
-int dbg_debugfs_init(void)
-{
-	dfs_rootdir = debugfs_create_dir("ubifs", NULL);
-	if (IS_ERR(dfs_rootdir)) {
-		int err = PTR_ERR(dfs_rootdir);
-		ubifs_err("cannot create \"ubifs\" debugfs directory, "
-			  "error %d\n", err);
-		return err;
-	}
-
-	return 0;
-}
-
-/**
- * dbg_debugfs_exit - remove the "ubifs" directory from debugfs file-system.
- */
-void dbg_debugfs_exit(void)
-{
-	debugfs_remove(dfs_rootdir);
-}
-
-static int open_debugfs_file(struct inode *inode, struct file *file)
+static int dfs_file_open(struct inode *inode, struct file *file)
 {
 	file->private_data = inode->i_private;
 	return nonseekable_open(inode, file);
 }
 
-static ssize_t write_debugfs_file(struct file *file, const char __user *buf,
-				  size_t count, loff_t *ppos)
+/**
+ * provide_user_output - provide output to the user reading a debugfs file.
+ * @val: boolean value for the answer
+ * @u: the buffer to store the answer at
+ * @count: size of the buffer
+ * @ppos: position in the @u output buffer
+ *
+ * This is a simple helper function which stores @val boolean value in the user
+ * buffer when the user reads one of UBIFS debugfs files. Returns amount of
+ * bytes written to @u in case of success and a negative error code in case of
+ * failure.
+ */
+static int provide_user_output(int val, char __user *u, size_t count,
+			       loff_t *ppos)
+{
+	char buf[3];
+
+	if (val)
+		buf[0] = '1';
+	else
+		buf[0] = '0';
+	buf[1] = '\n';
+	buf[2] = 0x00;
+
+	return simple_read_from_buffer(u, count, ppos, buf, 2);
+}
+
+static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
+			     loff_t *ppos)
+{
+	struct dentry *dent = file->f_path.dentry;
+	struct ubifs_info *c = file->private_data;
+	struct ubifs_debug_info *d = c->dbg;
+	int val;
+
+	if (dent == d->dfs_chk_gen)
+		val = d->chk_gen;
+	else if (dent == d->dfs_chk_index)
+		val = d->chk_index;
+	else if (dent == d->dfs_chk_orph)
+		val = d->chk_orph;
+	else if (dent == d->dfs_chk_lprops)
+		val = d->chk_lprops;
+	else if (dent == d->dfs_chk_fs)
+		val = d->chk_fs;
+	else if (dent == d->dfs_tst_rcvry)
+		val = d->tst_rcvry;
+	else
+		return -EINVAL;
+
+	return provide_user_output(val, u, count, ppos);
+}
+
+/**
+ * interpret_user_input - interpret user debugfs file input.
+ * @u: user-provided buffer with the input
+ * @count: buffer size
+ *
+ * This is a helper function which interpret user input to a boolean UBIFS
+ * debugfs file. Returns %0 or %1 in case of success and a negative error code
+ * in case of failure.
+ */
+static int interpret_user_input(const char __user *u, size_t count)
+{
+	size_t buf_size;
+	char buf[8];
+
+	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
+	if (copy_from_user(buf, u, buf_size))
+		return -EFAULT;
+
+	if (buf[0] == '1')
+		return 1;
+	else if (buf[0] == '0')
+		return 0;
+
+	return -EINVAL;
+}
+
+static ssize_t dfs_file_write(struct file *file, const char __user *u,
+			      size_t count, loff_t *ppos)
 {
 	struct ubifs_info *c = file->private_data;
 	struct ubifs_debug_info *d = c->dbg;
+	struct dentry *dent = file->f_path.dentry;
+	int val;
 
-	if (file->f_path.dentry == d->dfs_dump_lprops)
+	/*
+	 * TODO: this is racy - the file-system might have already been
+	 * unmounted and we'd oops in this case. The plan is to fix it with
+	 * help of 'iterate_supers_type()' which we should have in v3.0: when
+	 * a debugfs opened, we rember FS's UUID in file->private_data. Then
+	 * whenever we access the FS via a debugfs file, we iterate all UBIFS
+	 * superblocks and fine the one with the same UUID, and take the
+	 * locking right.
+	 *
+	 * The other way to go suggested by Al Viro is to create a separate
+	 * 'ubifs-debug' file-system instead.
+	 */
+	if (file->f_path.dentry == d->dfs_dump_lprops) {
 		dbg_dump_lprops(c);
-	else if (file->f_path.dentry == d->dfs_dump_budg)
+		return count;
+	}
+	if (file->f_path.dentry == d->dfs_dump_budg) {
 		dbg_dump_budg(c, &c->bi);
-	else if (file->f_path.dentry == d->dfs_dump_tnc) {
+		return count;
+	}
+	if (file->f_path.dentry == d->dfs_dump_tnc) {
 		mutex_lock(&c->tnc_mutex);
 		dbg_dump_tnc(c);
 		mutex_unlock(&c->tnc_mutex);
-	} else
+		return count;
+	}
+
+	val = interpret_user_input(u, count);
+	if (val < 0)
+		return val;
+
+	if (dent == d->dfs_chk_gen)
+		d->chk_gen = val;
+	else if (dent == d->dfs_chk_index)
+		d->chk_index = val;
+	else if (dent == d->dfs_chk_orph)
+		d->chk_orph = val;
+	else if (dent == d->dfs_chk_lprops)
+		d->chk_lprops = val;
+	else if (dent == d->dfs_chk_fs)
+		d->chk_fs = val;
+	else if (dent == d->dfs_tst_rcvry)
+		d->tst_rcvry = val;
+	else
 		return -EINVAL;
 
 	return count;
 }
 
 static const struct file_operations dfs_fops = {
-	.open = open_debugfs_file,
-	.write = write_debugfs_file,
+	.open = dfs_file_open,
+	.read = dfs_file_read,
+	.write = dfs_file_write,
 	.owner = THIS_MODULE,
 	.llseek = no_llseek,
 };
@@ -2880,12 +2897,20 @@
  */
 int dbg_debugfs_init_fs(struct ubifs_info *c)
 {
-	int err;
+	int err, n;
 	const char *fname;
 	struct dentry *dent;
 	struct ubifs_debug_info *d = c->dbg;
 
-	sprintf(d->dfs_dir_name, "ubi%d_%d", c->vi.ubi_num, c->vi.vol_id);
+	n = snprintf(d->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 */
+		fname = UBIFS_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))
@@ -2910,13 +2935,55 @@
 		goto out_remove;
 	d->dfs_dump_tnc = dent;
 
+	fname = "chk_general";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_gen = dent;
+
+	fname = "chk_index";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_index = dent;
+
+	fname = "chk_orphans";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_orph = dent;
+
+	fname = "chk_lprops";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_lprops = dent;
+
+	fname = "chk_fs";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_fs = dent;
+
+	fname = "tst_recovery";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, d->dfs_dir, c,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_tst_rcvry = dent;
+
 	return 0;
 
 out_remove:
 	debugfs_remove_recursive(d->dfs_dir);
 out:
 	err = dent ? PTR_ERR(dent) : -ENODEV;
-	ubifs_err("cannot create \"%s\" debugfs directory, error %d\n",
+	ubifs_err("cannot create \"%s\" debugfs file or directory, error %d\n",
 		  fname, err);
 	return err;
 }
@@ -2930,4 +2997,179 @@
 	debugfs_remove_recursive(c->dbg->dfs_dir);
 }
 
+struct ubifs_global_debug_info ubifs_dbg;
+
+static struct dentry *dfs_chk_gen;
+static struct dentry *dfs_chk_index;
+static struct dentry *dfs_chk_orph;
+static struct dentry *dfs_chk_lprops;
+static struct dentry *dfs_chk_fs;
+static struct dentry *dfs_tst_rcvry;
+
+static ssize_t dfs_global_file_read(struct file *file, char __user *u,
+				    size_t count, loff_t *ppos)
+{
+	struct dentry *dent = file->f_path.dentry;
+	int val;
+
+	if (dent == dfs_chk_gen)
+		val = ubifs_dbg.chk_gen;
+	else if (dent == dfs_chk_index)
+		val = ubifs_dbg.chk_index;
+	else if (dent == dfs_chk_orph)
+		val = ubifs_dbg.chk_orph;
+	else if (dent == dfs_chk_lprops)
+		val = ubifs_dbg.chk_lprops;
+	else if (dent == dfs_chk_fs)
+		val = ubifs_dbg.chk_fs;
+	else if (dent == dfs_tst_rcvry)
+		val = ubifs_dbg.tst_rcvry;
+	else
+		return -EINVAL;
+
+	return provide_user_output(val, u, count, ppos);
+}
+
+static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
+				     size_t count, loff_t *ppos)
+{
+	struct dentry *dent = file->f_path.dentry;
+	int val;
+
+	val = interpret_user_input(u, count);
+	if (val < 0)
+		return val;
+
+	if (dent == dfs_chk_gen)
+		ubifs_dbg.chk_gen = val;
+	else if (dent == dfs_chk_index)
+		ubifs_dbg.chk_index = val;
+	else if (dent == dfs_chk_orph)
+		ubifs_dbg.chk_orph = val;
+	else if (dent == dfs_chk_lprops)
+		ubifs_dbg.chk_lprops = val;
+	else if (dent == dfs_chk_fs)
+		ubifs_dbg.chk_fs = val;
+	else if (dent == dfs_tst_rcvry)
+		ubifs_dbg.tst_rcvry = val;
+	else
+		return -EINVAL;
+
+	return count;
+}
+
+static const struct file_operations dfs_global_fops = {
+	.read = dfs_global_file_read,
+	.write = dfs_global_file_write,
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+};
+
+/**
+ * dbg_debugfs_init - initialize debugfs file-system.
+ *
+ * UBIFS uses debugfs file-system to expose various debugging knobs to
+ * user-space. This function creates "ubifs" directory in the debugfs
+ * file-system. Returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int dbg_debugfs_init(void)
+{
+	int err;
+	const char *fname;
+	struct dentry *dent;
+
+	fname = "ubifs";
+	dent = debugfs_create_dir(fname, NULL);
+	if (IS_ERR_OR_NULL(dent))
+		goto out;
+	dfs_rootdir = dent;
+
+	fname = "chk_general";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, dfs_rootdir, NULL,
+				   &dfs_global_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	dfs_chk_gen = dent;
+
+	fname = "chk_index";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, dfs_rootdir, NULL,
+				   &dfs_global_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	dfs_chk_index = dent;
+
+	fname = "chk_orphans";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, dfs_rootdir, NULL,
+				   &dfs_global_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	dfs_chk_orph = dent;
+
+	fname = "chk_lprops";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, dfs_rootdir, NULL,
+				   &dfs_global_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	dfs_chk_lprops = dent;
+
+	fname = "chk_fs";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, dfs_rootdir, NULL,
+				   &dfs_global_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	dfs_chk_fs = dent;
+
+	fname = "tst_recovery";
+	dent = debugfs_create_file(fname, S_IRUSR | S_IWUSR, dfs_rootdir, NULL,
+				   &dfs_global_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	dfs_tst_rcvry = dent;
+
+	return 0;
+
+out_remove:
+	debugfs_remove_recursive(dfs_rootdir);
+out:
+	err = dent ? PTR_ERR(dent) : -ENODEV;
+	ubifs_err("cannot create \"%s\" debugfs file or directory, error %d\n",
+		  fname, err);
+	return err;
+}
+
+/**
+ * dbg_debugfs_exit - remove the "ubifs" directory from debugfs file-system.
+ */
+void dbg_debugfs_exit(void)
+{
+	debugfs_remove_recursive(dfs_rootdir);
+}
+
+/**
+ * ubifs_debugging_init - initialize UBIFS debugging.
+ * @c: UBIFS file-system description object
+ *
+ * This function initializes debugging-related data for the file system.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubifs_debugging_init(struct ubifs_info *c)
+{
+	c->dbg = kzalloc(sizeof(struct ubifs_debug_info), GFP_KERNEL);
+	if (!c->dbg)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * ubifs_debugging_exit - free debugging data.
+ * @c: UBIFS file-system description object
+ */
+void ubifs_debugging_exit(struct ubifs_info *c)
+{
+	kfree(c->dbg);
+}
+
 #endif /* CONFIG_UBIFS_FS_DEBUG */
diff --git a/fs/ubifs/debug.h b/fs/ubifs/debug.h
index a811ac4..45174b5 100644
--- a/fs/ubifs/debug.h
+++ b/fs/ubifs/debug.h
@@ -31,18 +31,25 @@
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
 
-#include <linux/random.h>
+/*
+ * The UBIFS debugfs 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_debug_info - per-FS debugging information.
  * @old_zroot: old index root - used by 'dbg_check_old_index()'
  * @old_zroot_level: old index root level - used by 'dbg_check_old_index()'
  * @old_zroot_sqnum: old index root sqnum - used by 'dbg_check_old_index()'
- * @failure_mode: failure mode for recovery testing
- * @fail_delay: 0=>don't delay, 1=>delay a time, 2=>delay a number of calls
- * @fail_timeout: time in jiffies when delay of failure mode expires
- * @fail_cnt: current number of calls to failure mode I/O functions
- * @fail_cnt_max: number of calls by which to delay failure mode
+ *
+ * @pc_happened: non-zero if an emulated power cut happened
+ * @pc_delay: 0=>don't delay, 1=>delay a time, 2=>delay a number of calls
+ * @pc_timeout: time in jiffies when delay of failure mode expires
+ * @pc_cnt: current number of calls to failure mode I/O functions
+ * @pc_cnt_max: number of calls by which to delay failure mode
+ *
  * @chk_lpt_sz: used by LPT tree size checker
  * @chk_lpt_sz2: used by LPT tree size checker
  * @chk_lpt_wastage: used by LPT tree size checker
@@ -56,21 +63,36 @@
  * @saved_free: saved amount of free space
  * @saved_idx_gc_cnt: saved value of @c->idx_gc_cnt
  *
+ * @chk_gen: if general extra checks are enabled
+ * @chk_index: if index xtra checks are enabled
+ * @chk_orph: if orphans extra checks are enabled
+ * @chk_lprops: if lprops extra checks are enabled
+ * @chk_fs: if UBIFS contents extra checks are enabled
+ * @tst_rcvry: if UBIFS recovery testing mode enabled
+ *
  * @dfs_dir_name: name of debugfs directory containing this file-system's files
  * @dfs_dir: direntry object of the file-system debugfs directory
  * @dfs_dump_lprops: "dump lprops" debugfs knob
  * @dfs_dump_budg: "dump budgeting information" debugfs knob
  * @dfs_dump_tnc: "dump TNC" debugfs knob
+ * @dfs_chk_gen: debugfs knob to enable UBIFS general extra checks
+ * @dfs_chk_index: debugfs knob to enable UBIFS index extra checks
+ * @dfs_chk_orph: debugfs knob to enable UBIFS orphans extra checks
+ * @dfs_chk_lprops: debugfs knob to enable UBIFS LEP properties extra checks
+ * @dfs_chk_fs: debugfs knob to enable UBIFS contents extra checks
+ * @dfs_tst_rcvry: debugfs knob to enable UBIFS recovery testing
  */
 struct ubifs_debug_info {
 	struct ubifs_zbranch old_zroot;
 	int old_zroot_level;
 	unsigned long long old_zroot_sqnum;
-	int failure_mode;
-	int fail_delay;
-	unsigned long fail_timeout;
-	unsigned int fail_cnt;
-	unsigned int fail_cnt_max;
+
+	int pc_happened;
+	int pc_delay;
+	unsigned long pc_timeout;
+	unsigned int pc_cnt;
+	unsigned int pc_cnt_max;
+
 	long long chk_lpt_sz;
 	long long chk_lpt_sz2;
 	long long chk_lpt_wastage;
@@ -84,11 +106,43 @@
 	long long saved_free;
 	int saved_idx_gc_cnt;
 
-	char dfs_dir_name[100];
+	unsigned int chk_gen:1;
+	unsigned int chk_index:1;
+	unsigned int chk_orph:1;
+	unsigned int chk_lprops:1;
+	unsigned int chk_fs:1;
+	unsigned int tst_rcvry:1;
+
+	char dfs_dir_name[UBIFS_DFS_DIR_LEN + 1];
 	struct dentry *dfs_dir;
 	struct dentry *dfs_dump_lprops;
 	struct dentry *dfs_dump_budg;
 	struct dentry *dfs_dump_tnc;
+	struct dentry *dfs_chk_gen;
+	struct dentry *dfs_chk_index;
+	struct dentry *dfs_chk_orph;
+	struct dentry *dfs_chk_lprops;
+	struct dentry *dfs_chk_fs;
+	struct dentry *dfs_tst_rcvry;
+};
+
+/**
+ * ubifs_global_debug_info - global (not per-FS) UBIFS debugging information.
+ *
+ * @chk_gen: if general extra checks are enabled
+ * @chk_index: if index xtra checks are enabled
+ * @chk_orph: if orphans extra checks are enabled
+ * @chk_lprops: if lprops extra checks are enabled
+ * @chk_fs: if UBIFS contents extra checks are enabled
+ * @tst_rcvry: if UBIFS recovery testing mode enabled
+ */
+struct ubifs_global_debug_info {
+	unsigned int chk_gen:1;
+	unsigned int chk_index:1;
+	unsigned int chk_orph:1;
+	unsigned int chk_lprops:1;
+	unsigned int chk_fs:1;
+	unsigned int tst_rcvry:1;
 };
 
 #define ubifs_assert(expr) do {                                                \
@@ -127,6 +181,8 @@
 #define DBGKEY(key) dbg_key_str0(c, (key))
 #define DBGKEY1(key) dbg_key_str1(c, (key))
 
+extern spinlock_t dbg_lock;
+
 #define ubifs_dbg_msg(type, fmt, ...) do {                        \
 	spin_lock(&dbg_lock);                                     \
 	pr_debug("UBIFS DBG " type ": " fmt "\n", ##__VA_ARGS__); \
@@ -162,41 +218,36 @@
 /* Additional recovery messages */
 #define dbg_rcvry(fmt, ...) ubifs_dbg_msg("rcvry", fmt, ##__VA_ARGS__)
 
-/*
- * Debugging check flags.
- *
- * UBIFS_CHK_GEN: general checks
- * UBIFS_CHK_TNC: check TNC
- * UBIFS_CHK_IDX_SZ: check index size
- * UBIFS_CHK_ORPH: check orphans
- * UBIFS_CHK_OLD_IDX: check the old index
- * UBIFS_CHK_LPROPS: check lprops
- * UBIFS_CHK_FS: check the file-system
- */
-enum {
-	UBIFS_CHK_GEN     = 0x1,
-	UBIFS_CHK_TNC     = 0x2,
-	UBIFS_CHK_IDX_SZ  = 0x4,
-	UBIFS_CHK_ORPH    = 0x8,
-	UBIFS_CHK_OLD_IDX = 0x10,
-	UBIFS_CHK_LPROPS  = 0x20,
-	UBIFS_CHK_FS      = 0x40,
-};
+extern struct ubifs_global_debug_info ubifs_dbg;
 
-/*
- * Special testing flags.
- *
- * UBIFS_TST_RCVRY: failure mode for recovery testing
- */
-enum {
-	UBIFS_TST_RCVRY             = 0x4,
-};
-
-extern spinlock_t dbg_lock;
-
-extern unsigned int ubifs_msg_flags;
-extern unsigned int ubifs_chk_flags;
-extern unsigned int ubifs_tst_flags;
+static inline int dbg_is_chk_gen(const struct ubifs_info *c)
+{
+	return !!(ubifs_dbg.chk_gen || c->dbg->chk_gen);
+}
+static inline int dbg_is_chk_index(const struct ubifs_info *c)
+{
+	return !!(ubifs_dbg.chk_index || c->dbg->chk_index);
+}
+static inline int dbg_is_chk_orph(const struct ubifs_info *c)
+{
+	return !!(ubifs_dbg.chk_orph || c->dbg->chk_orph);
+}
+static inline int dbg_is_chk_lprops(const struct ubifs_info *c)
+{
+	return !!(ubifs_dbg.chk_lprops || c->dbg->chk_lprops);
+}
+static inline int dbg_is_chk_fs(const struct ubifs_info *c)
+{
+	return !!(ubifs_dbg.chk_fs || c->dbg->chk_fs);
+}
+static inline int dbg_is_tst_rcvry(const struct ubifs_info *c)
+{
+	return !!(ubifs_dbg.tst_rcvry || c->dbg->tst_rcvry);
+}
+static inline int dbg_is_power_cut(const struct ubifs_info *c)
+{
+	return !!c->dbg->pc_happened;
+}
 
 int ubifs_debugging_init(struct ubifs_info *c);
 void ubifs_debugging_exit(struct ubifs_info *c);
@@ -207,7 +258,7 @@
 const char *dbg_jhead(int jhead);
 const char *dbg_get_key_dump(const struct ubifs_info *c,
 			     const union ubifs_key *key);
-void dbg_dump_inode(const struct ubifs_info *c, const struct inode *inode);
+void dbg_dump_inode(struct ubifs_info *c, const struct inode *inode);
 void dbg_dump_node(const struct ubifs_info *c, const void *node);
 void dbg_dump_lpt_node(const struct ubifs_info *c, void *node, int lnum,
 		       int offs);
@@ -240,8 +291,8 @@
 int dbg_check_ltab(struct ubifs_info *c);
 int dbg_chk_lpt_free_spc(struct ubifs_info *c);
 int dbg_chk_lpt_sz(struct ubifs_info *c, int action, int len);
-int dbg_check_synced_i_size(struct inode *inode);
-int dbg_check_dir_size(struct ubifs_info *c, const struct inode *dir);
+int dbg_check_synced_i_size(const struct ubifs_info *c, struct inode *inode);
+int dbg_check_dir(struct ubifs_info *c, const struct inode *dir);
 int dbg_check_tnc(struct ubifs_info *c, int extra);
 int dbg_check_idx_size(struct ubifs_info *c, long long idx_size);
 int dbg_check_filesystem(struct ubifs_info *c);
@@ -254,54 +305,12 @@
 int dbg_check_data_nodes_order(struct ubifs_info *c, struct list_head *head);
 int dbg_check_nondata_nodes_order(struct ubifs_info *c, struct list_head *head);
 
-/* Force the use of in-the-gaps method for testing */
-static inline int dbg_force_in_the_gaps_enabled(void)
-{
-	return ubifs_chk_flags & UBIFS_CHK_GEN;
-}
-int dbg_force_in_the_gaps(void);
-
-/* Failure mode for recovery testing */
-#define dbg_failure_mode (ubifs_tst_flags & UBIFS_TST_RCVRY)
-
-#ifndef UBIFS_DBG_PRESERVE_UBI
-#define ubi_leb_read   dbg_leb_read
-#define ubi_leb_write  dbg_leb_write
-#define ubi_leb_change dbg_leb_change
-#define ubi_leb_erase  dbg_leb_erase
-#define ubi_leb_unmap  dbg_leb_unmap
-#define ubi_is_mapped  dbg_is_mapped
-#define ubi_leb_map    dbg_leb_map
-#endif
-
-int dbg_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
-		 int len, int check);
-int dbg_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
-		  int offset, int len, int dtype);
-int dbg_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
-		   int len, int dtype);
-int dbg_leb_erase(struct ubi_volume_desc *desc, int lnum);
-int dbg_leb_unmap(struct ubi_volume_desc *desc, int lnum);
-int dbg_is_mapped(struct ubi_volume_desc *desc, int lnum);
-int dbg_leb_map(struct ubi_volume_desc *desc, int lnum, int dtype);
-
-static inline int dbg_read(struct ubi_volume_desc *desc, int lnum, char *buf,
-			   int offset, int len)
-{
-	return dbg_leb_read(desc, lnum, buf, offset, len, 0);
-}
-
-static inline int dbg_write(struct ubi_volume_desc *desc, int lnum,
-			    const void *buf, int offset, int len)
-{
-	return dbg_leb_write(desc, lnum, buf, offset, len, UBI_UNKNOWN);
-}
-
-static inline int dbg_change(struct ubi_volume_desc *desc, int lnum,
-				    const void *buf, int len)
-{
-	return dbg_leb_change(desc, lnum, buf, len, UBI_UNKNOWN);
-}
+int dbg_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
+		  int len, int dtype);
+int dbg_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len,
+		   int dtype);
+int dbg_leb_unmap(struct ubifs_info *c, int lnum);
+int dbg_leb_map(struct ubifs_info *c, int lnum, int dtype);
 
 /* Debugfs-related stuff */
 int dbg_debugfs_init(void);
@@ -313,7 +322,7 @@
 
 /* Use "if (0)" to make compiler check arguments even if debugging is off */
 #define ubifs_assert(expr)  do {                                               \
-	if (0 && (expr))                                                       \
+	if (0)                                                                 \
 		printk(KERN_CRIT "UBIFS assert failed in %s at %u (pid %d)\n", \
 		       __func__, __LINE__, current->pid);                      \
 } while (0)
@@ -323,6 +332,9 @@
 		ubifs_err(fmt, ##__VA_ARGS__);     \
 } while (0)
 
+#define DBGKEY(key)  ((char *)(key))
+#define DBGKEY1(key) ((char *)(key))
+
 #define ubifs_dbg_msg(fmt, ...) do {               \
 	if (0)                                     \
 		pr_debug(fmt "\n", ##__VA_ARGS__); \
@@ -346,9 +358,6 @@
 #define dbg_scan(fmt, ...)  ubifs_dbg_msg(fmt, ##__VA_ARGS__)
 #define dbg_rcvry(fmt, ...) ubifs_dbg_msg(fmt, ##__VA_ARGS__)
 
-#define DBGKEY(key)  ((char *)(key))
-#define DBGKEY1(key) ((char *)(key))
-
 static inline int ubifs_debugging_init(struct ubifs_info *c)      { return 0; }
 static inline void ubifs_debugging_exit(struct ubifs_info *c)     { return; }
 static inline const char *dbg_ntype(int type)                     { return ""; }
@@ -357,7 +366,7 @@
 static inline const char *
 dbg_get_key_dump(const struct ubifs_info *c,
 		 const union ubifs_key *key)                      { return ""; }
-static inline void dbg_dump_inode(const struct ubifs_info *c,
+static inline void dbg_dump_inode(struct ubifs_info *c,
 				  const struct inode *inode)      { return; }
 static inline void dbg_dump_node(const struct ubifs_info *c,
 				 const void *node)                { return; }
@@ -409,9 +418,11 @@
 static inline int dbg_chk_lpt_free_spc(struct ubifs_info *c)      { return 0; }
 static inline int dbg_chk_lpt_sz(struct ubifs_info *c,
 				 int action, int len)             { return 0; }
-static inline int dbg_check_synced_i_size(struct inode *inode)    { return 0; }
-static inline int dbg_check_dir_size(struct ubifs_info *c,
-				     const struct inode *dir)     { return 0; }
+static inline int
+dbg_check_synced_i_size(const struct ubifs_info *c,
+			struct inode *inode)                      { return 0; }
+static inline int dbg_check_dir(struct ubifs_info *c,
+				const struct inode *dir)          { return 0; }
 static inline int dbg_check_tnc(struct ubifs_info *c, int extra)  { return 0; }
 static inline int dbg_check_idx_size(struct ubifs_info *c,
 				     long long idx_size)          { return 0; }
@@ -431,9 +442,23 @@
 dbg_check_nondata_nodes_order(struct ubifs_info *c,
 			      struct list_head *head)             { return 0; }
 
-static inline int dbg_force_in_the_gaps(void)                     { return 0; }
-#define dbg_force_in_the_gaps_enabled() 0
-#define dbg_failure_mode                0
+static inline int dbg_leb_write(struct ubifs_info *c, int lnum,
+				const void *buf, int offset,
+				int len, int dtype)               { return 0; }
+static inline int dbg_leb_change(struct ubifs_info *c, int lnum,
+				 const void *buf, int len,
+				 int dtype)                       { return 0; }
+static inline int dbg_leb_unmap(struct ubifs_info *c, int lnum)   { return 0; }
+static inline int dbg_leb_map(struct ubifs_info *c, int lnum,
+			      int dtype)                          { return 0; }
+
+static inline int dbg_is_chk_gen(const struct ubifs_info *c)      { return 0; }
+static inline int dbg_is_chk_index(const struct ubifs_info *c)    { return 0; }
+static inline int dbg_is_chk_orph(const struct ubifs_info *c)     { return 0; }
+static inline int dbg_is_chk_lprops(const struct ubifs_info *c)   { return 0; }
+static inline int dbg_is_chk_fs(const struct ubifs_info *c)       { return 0; }
+static inline int dbg_is_tst_rcvry(const struct ubifs_info *c)    { return 0; }
+static inline int dbg_is_power_cut(const struct ubifs_info *c)    { return 0; }
 
 static inline int dbg_debugfs_init(void)                          { return 0; }
 static inline void dbg_debugfs_exit(void)                         { return; }
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index ef5abd3..6834920 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -102,7 +102,7 @@
 	 * UBIFS has to fully control "clean <-> dirty" transitions of inodes
 	 * to make budgeting work.
 	 */
-	inode->i_flags |= (S_NOCMTIME);
+	inode->i_flags |= S_NOCMTIME;
 
 	inode_init_owner(inode, dir, mode);
 	inode->i_mtime = inode->i_atime = inode->i_ctime =
@@ -172,9 +172,11 @@
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
 
-static int dbg_check_name(struct ubifs_dent_node *dent, struct qstr *nm)
+static int dbg_check_name(const struct ubifs_info *c,
+			  const struct ubifs_dent_node *dent,
+			  const struct qstr *nm)
 {
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 	if (le16_to_cpu(dent->nlen) != nm->len)
 		return -EINVAL;
@@ -185,7 +187,7 @@
 
 #else
 
-#define dbg_check_name(dent, nm) 0
+#define dbg_check_name(c, dent, nm) 0
 
 #endif
 
@@ -219,7 +221,7 @@
 		goto out;
 	}
 
-	if (dbg_check_name(dent, &dentry->d_name)) {
+	if (dbg_check_name(c, dent, &dentry->d_name)) {
 		err = -EINVAL;
 		goto out;
 	}
@@ -522,7 +524,7 @@
 	ubifs_assert(mutex_is_locked(&dir->i_mutex));
 	ubifs_assert(mutex_is_locked(&inode->i_mutex));
 
-	err = dbg_check_synced_i_size(inode);
+	err = dbg_check_synced_i_size(c, inode);
 	if (err)
 		return err;
 
@@ -577,7 +579,7 @@
 		inode->i_nlink, dir->i_ino);
 	ubifs_assert(mutex_is_locked(&dir->i_mutex));
 	ubifs_assert(mutex_is_locked(&inode->i_mutex));
-	err = dbg_check_synced_i_size(inode);
+	err = dbg_check_synced_i_size(c, inode);
 	if (err)
 		return err;
 
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 5e7fccf..7cf738a 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1263,7 +1263,7 @@
 	if (err)
 		return err;
 
-	err = dbg_check_synced_i_size(inode);
+	err = dbg_check_synced_i_size(c, inode);
 	if (err)
 		return err;
 
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 3be645e..9228950 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -86,8 +86,125 @@
 		c->no_chk_data_crc = 0;
 		c->vfs_sb->s_flags |= MS_RDONLY;
 		ubifs_warn("switched to read-only mode, error %d", err);
+		dump_stack();
+	}
+}
+
+/*
+ * Below are simple wrappers over UBI I/O functions which include some
+ * additional checks and UBIFS debugging stuff. See corresponding UBI function
+ * for more information.
+ */
+
+int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
+		   int len, int even_ebadmsg)
+{
+	int err;
+
+	err = ubi_read(c->ubi, lnum, buf, offs, len);
+	/*
+	 * In case of %-EBADMSG print the error message only if the
+	 * @even_ebadmsg is true.
+	 */
+	if (err && (err != -EBADMSG || even_ebadmsg)) {
+		ubifs_err("reading %d bytes from LEB %d:%d failed, error %d",
+			  len, lnum, offs, err);
 		dbg_dump_stack();
 	}
+	return err;
+}
+
+int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
+		    int len, int dtype)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
+	else
+		err = dbg_leb_write(c, lnum, buf, offs, len, dtype);
+	if (err) {
+		ubifs_err("writing %d bytes to LEB %d:%d failed, error %d",
+			  len, lnum, offs, err);
+		ubifs_ro_mode(c, err);
+		dbg_dump_stack();
+	}
+	return err;
+}
+
+int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len,
+		     int dtype)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
+	else
+		err = dbg_leb_change(c, lnum, buf, len, dtype);
+	if (err) {
+		ubifs_err("changing %d bytes in LEB %d failed, error %d",
+			  len, lnum, err);
+		ubifs_ro_mode(c, err);
+		dbg_dump_stack();
+	}
+	return err;
+}
+
+int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_unmap(c->ubi, lnum);
+	else
+		err = dbg_leb_unmap(c, lnum);
+	if (err) {
+		ubifs_err("unmap LEB %d failed, error %d", lnum, err);
+		ubifs_ro_mode(c, err);
+		dbg_dump_stack();
+	}
+	return err;
+}
+
+int ubifs_leb_map(struct ubifs_info *c, int lnum, int dtype)
+{
+	int err;
+
+	ubifs_assert(!c->ro_media && !c->ro_mount);
+	if (c->ro_error)
+		return -EROFS;
+	if (!dbg_is_tst_rcvry(c))
+		err = ubi_leb_map(c->ubi, lnum, dtype);
+	else
+		err = dbg_leb_map(c, lnum, dtype);
+	if (err) {
+		ubifs_err("mapping LEB %d failed, error %d", lnum, err);
+		ubifs_ro_mode(c, err);
+		dbg_dump_stack();
+	}
+	return err;
+}
+
+int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
+{
+	int err;
+
+	err = ubi_is_mapped(c->ubi, lnum);
+	if (err < 0) {
+		ubifs_err("ubi_is_mapped failed for LEB %d, error %d",
+			  lnum, err);
+		dbg_dump_stack();
+	}
+	return err;
 }
 
 /**
@@ -406,14 +523,10 @@
 	dirt = sync_len - wbuf->used;
 	if (dirt)
 		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
-	err = ubi_leb_write(c->ubi, wbuf->lnum, wbuf->buf, wbuf->offs,
-			    sync_len, wbuf->dtype);
-	if (err) {
-		ubifs_err("cannot write %d bytes to LEB %d:%d",
-			  sync_len, wbuf->lnum, wbuf->offs);
-		dbg_dump_stack();
+	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len,
+			      wbuf->dtype);
+	if (err)
 		return err;
-	}
 
 	spin_lock(&wbuf->lock);
 	wbuf->offs += sync_len;
@@ -605,9 +718,9 @@
 		if (aligned_len == wbuf->avail) {
 			dbg_io("flush jhead %s wbuf to LEB %d:%d",
 			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
-			err = ubi_leb_write(c->ubi, wbuf->lnum, wbuf->buf,
-					    wbuf->offs, wbuf->size,
-					    wbuf->dtype);
+			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
+					      wbuf->offs, wbuf->size,
+					      wbuf->dtype);
 			if (err)
 				goto out;
 
@@ -642,8 +755,8 @@
 		dbg_io("flush jhead %s wbuf to LEB %d:%d",
 		       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
 		memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
-		err = ubi_leb_write(c->ubi, wbuf->lnum, wbuf->buf, wbuf->offs,
-				    wbuf->size, wbuf->dtype);
+		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
+				      wbuf->size, wbuf->dtype);
 		if (err)
 			goto out;
 
@@ -661,8 +774,8 @@
 		 */
 		dbg_io("write %d bytes to LEB %d:%d",
 		       wbuf->size, wbuf->lnum, wbuf->offs);
-		err = ubi_leb_write(c->ubi, wbuf->lnum, buf, wbuf->offs,
-				    wbuf->size, wbuf->dtype);
+		err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
+				      wbuf->size, wbuf->dtype);
 		if (err)
 			goto out;
 
@@ -683,8 +796,8 @@
 		n <<= c->max_write_shift;
 		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
 		       wbuf->offs);
-		err = ubi_leb_write(c->ubi, wbuf->lnum, buf + written,
-				    wbuf->offs, n, wbuf->dtype);
+		err = ubifs_leb_write(c, wbuf->lnum, buf + written,
+				      wbuf->offs, n, wbuf->dtype);
 		if (err)
 			goto out;
 		wbuf->offs += n;
@@ -766,13 +879,9 @@
 		return -EROFS;
 
 	ubifs_prepare_node(c, buf, len, 1);
-	err = ubi_leb_write(c->ubi, lnum, buf, offs, buf_len, dtype);
-	if (err) {
-		ubifs_err("cannot write %d bytes to LEB %d:%d, error %d",
-			  buf_len, lnum, offs, err);
+	err = ubifs_leb_write(c, lnum, buf, offs, buf_len, dtype);
+	if (err)
 		dbg_dump_node(c, buf);
-		dbg_dump_stack();
-	}
 
 	return err;
 }
@@ -824,13 +933,9 @@
 
 	if (rlen > 0) {
 		/* Read everything that goes before write-buffer */
-		err = ubi_read(c->ubi, lnum, buf, offs, rlen);
-		if (err && err != -EBADMSG) {
-			ubifs_err("failed to read node %d from LEB %d:%d, "
-				  "error %d", type, lnum, offs, err);
-			dbg_dump_stack();
+		err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
+		if (err && err != -EBADMSG)
 			return err;
-		}
 	}
 
 	if (type != ch->node_type) {
@@ -885,12 +990,9 @@
 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
 	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
 
-	err = ubi_read(c->ubi, lnum, buf, offs, len);
-	if (err && err != -EBADMSG) {
-		ubifs_err("cannot read node %d from LEB %d:%d, error %d",
-			  type, lnum, offs, err);
+	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
+	if (err && err != -EBADMSG)
 		return err;
-	}
 
 	if (type != ch->node_type) {
 		ubifs_err("bad node type (%d but expected %d)",
diff --git a/fs/ubifs/log.c b/fs/ubifs/log.c
index affea94..f9fd068 100644
--- a/fs/ubifs/log.c
+++ b/fs/ubifs/log.c
@@ -262,7 +262,7 @@
 		 * an unclean reboot, because the target LEB might have been
 		 * unmapped, but not yet physically erased.
 		 */
-		err = ubi_leb_map(c->ubi, bud->lnum, UBI_SHORTTERM);
+		err = ubifs_leb_map(c, bud->lnum, UBI_SHORTTERM);
 		if (err)
 			goto out_unlock;
 	}
@@ -283,8 +283,6 @@
 	return 0;
 
 out_unlock:
-	if (err != -EAGAIN)
-		ubifs_ro_mode(c, err);
 	mutex_unlock(&c->log_mutex);
 	kfree(ref);
 	kfree(bud);
@@ -752,7 +750,7 @@
 	struct ubifs_bud *bud;
 	long long bud_bytes = 0;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 
 	spin_lock(&c->buds_lock);
diff --git a/fs/ubifs/lprops.c b/fs/ubifs/lprops.c
index 667884f..f8a181e 100644
--- a/fs/ubifs/lprops.c
+++ b/fs/ubifs/lprops.c
@@ -504,7 +504,7 @@
 	pnode = (struct ubifs_pnode *)container_of(lprops - pos,
 						   struct ubifs_pnode,
 						   lprops[0]);
-	return !test_bit(COW_ZNODE, &pnode->flags) &&
+	return !test_bit(COW_CNODE, &pnode->flags) &&
 	       test_bit(DIRTY_CNODE, &pnode->flags);
 }
 
@@ -860,7 +860,7 @@
 	struct list_head *pos;
 	int i, cat;
 
-	if (!(ubifs_chk_flags & (UBIFS_CHK_GEN | UBIFS_CHK_LPROPS)))
+	if (!dbg_is_chk_gen(c) && !dbg_is_chk_lprops(c))
 		return 0;
 
 	list_for_each_entry(lprops, &c->empty_list, list) {
@@ -958,7 +958,7 @@
 {
 	int i = 0, j, err = 0;
 
-	if (!(ubifs_chk_flags & (UBIFS_CHK_GEN | UBIFS_CHK_LPROPS)))
+	if (!dbg_is_chk_gen(c) && !dbg_is_chk_lprops(c))
 		return;
 
 	for (i = 0; i < heap->cnt; i++) {
@@ -1262,7 +1262,7 @@
 	int i, err;
 	struct ubifs_lp_stats lst;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+	if (!dbg_is_chk_lprops(c))
 		return 0;
 
 	/*
diff --git a/fs/ubifs/lpt.c b/fs/ubifs/lpt.c
index ef5155e..6189c74 100644
--- a/fs/ubifs/lpt.c
+++ b/fs/ubifs/lpt.c
@@ -701,8 +701,8 @@
 			alen = ALIGN(len, c->min_io_size);
 			set_ltab(c, lnum, c->leb_size - alen, alen - len);
 			memset(p, 0xff, alen - len);
-			err = ubi_leb_change(c->ubi, lnum++, buf, alen,
-					     UBI_SHORTTERM);
+			err = ubifs_leb_change(c, lnum++, buf, alen,
+					       UBI_SHORTTERM);
 			if (err)
 				goto out;
 			p = buf;
@@ -732,8 +732,8 @@
 				set_ltab(c, lnum, c->leb_size - alen,
 					    alen - len);
 				memset(p, 0xff, alen - len);
-				err = ubi_leb_change(c->ubi, lnum++, buf, alen,
-						     UBI_SHORTTERM);
+				err = ubifs_leb_change(c, lnum++, buf, alen,
+						       UBI_SHORTTERM);
 				if (err)
 					goto out;
 				p = buf;
@@ -780,8 +780,8 @@
 			alen = ALIGN(len, c->min_io_size);
 			set_ltab(c, lnum, c->leb_size - alen, alen - len);
 			memset(p, 0xff, alen - len);
-			err = ubi_leb_change(c->ubi, lnum++, buf, alen,
-					     UBI_SHORTTERM);
+			err = ubifs_leb_change(c, lnum++, buf, alen,
+					       UBI_SHORTTERM);
 			if (err)
 				goto out;
 			p = buf;
@@ -806,7 +806,7 @@
 		alen = ALIGN(len, c->min_io_size);
 		set_ltab(c, lnum, c->leb_size - alen, alen - len);
 		memset(p, 0xff, alen - len);
-		err = ubi_leb_change(c->ubi, lnum++, buf, alen, UBI_SHORTTERM);
+		err = ubifs_leb_change(c, lnum++, buf, alen, UBI_SHORTTERM);
 		if (err)
 			goto out;
 		p = buf;
@@ -826,7 +826,7 @@
 
 	/* Write remaining buffer */
 	memset(p, 0xff, alen - len);
-	err = ubi_leb_change(c->ubi, lnum, buf, alen, UBI_SHORTTERM);
+	err = ubifs_leb_change(c, lnum, buf, alen, UBI_SHORTTERM);
 	if (err)
 		goto out;
 
@@ -1222,7 +1222,7 @@
 		if (c->big_lpt)
 			nnode->num = calc_nnode_num_from_parent(c, parent, iip);
 	} else {
-		err = ubi_read(c->ubi, lnum, buf, offs, c->nnode_sz);
+		err = ubifs_leb_read(c, lnum, buf, offs, c->nnode_sz, 1);
 		if (err)
 			goto out;
 		err = ubifs_unpack_nnode(c, buf, nnode);
@@ -1247,6 +1247,7 @@
 
 out:
 	ubifs_err("error %d reading nnode at %d:%d", err, lnum, offs);
+	dbg_dump_stack();
 	kfree(nnode);
 	return err;
 }
@@ -1290,7 +1291,7 @@
 			lprops->flags = ubifs_categorize_lprops(c, lprops);
 		}
 	} else {
-		err = ubi_read(c->ubi, lnum, buf, offs, c->pnode_sz);
+		err = ubifs_leb_read(c, lnum, buf, offs, c->pnode_sz, 1);
 		if (err)
 			goto out;
 		err = unpack_pnode(c, buf, pnode);
@@ -1312,6 +1313,7 @@
 out:
 	ubifs_err("error %d reading pnode at %d:%d", err, lnum, offs);
 	dbg_dump_pnode(c, pnode, parent, iip);
+	dbg_dump_stack();
 	dbg_msg("calc num: %d", calc_pnode_num_from_parent(c, parent, iip));
 	kfree(pnode);
 	return err;
@@ -1331,7 +1333,7 @@
 	buf = vmalloc(c->ltab_sz);
 	if (!buf)
 		return -ENOMEM;
-	err = ubi_read(c->ubi, c->ltab_lnum, buf, c->ltab_offs, c->ltab_sz);
+	err = ubifs_leb_read(c, c->ltab_lnum, buf, c->ltab_offs, c->ltab_sz, 1);
 	if (err)
 		goto out;
 	err = unpack_ltab(c, buf);
@@ -1354,7 +1356,8 @@
 	buf = vmalloc(c->lsave_sz);
 	if (!buf)
 		return -ENOMEM;
-	err = ubi_read(c->ubi, c->lsave_lnum, buf, c->lsave_offs, c->lsave_sz);
+	err = ubifs_leb_read(c, c->lsave_lnum, buf, c->lsave_offs,
+			     c->lsave_sz, 1);
 	if (err)
 		goto out;
 	err = unpack_lsave(c, buf);
@@ -1814,8 +1817,8 @@
 		if (c->big_lpt)
 			nnode->num = calc_nnode_num_from_parent(c, parent, iip);
 	} else {
-		err = ubi_read(c->ubi, branch->lnum, buf, branch->offs,
-			       c->nnode_sz);
+		err = ubifs_leb_read(c, branch->lnum, buf, branch->offs,
+				     c->nnode_sz, 1);
 		if (err)
 			return ERR_PTR(err);
 		err = ubifs_unpack_nnode(c, buf, nnode);
@@ -1883,8 +1886,8 @@
 		ubifs_assert(branch->lnum >= c->lpt_first &&
 			     branch->lnum <= c->lpt_last);
 		ubifs_assert(branch->offs >= 0 && branch->offs < c->leb_size);
-		err = ubi_read(c->ubi, branch->lnum, buf, branch->offs,
-			       c->pnode_sz);
+		err = ubifs_leb_read(c, branch->lnum, buf, branch->offs,
+				     c->pnode_sz, 1);
 		if (err)
 			return ERR_PTR(err);
 		err = unpack_pnode(c, buf, pnode);
@@ -2224,7 +2227,7 @@
 	struct ubifs_cnode *cn;
 	int num, iip = 0, err;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+	if (!dbg_is_chk_lprops(c))
 		return 0;
 
 	while (cnode) {
diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
index dfcb574..cddd6bd 100644
--- a/fs/ubifs/lpt_commit.c
+++ b/fs/ubifs/lpt_commit.c
@@ -27,6 +27,7 @@
 
 #include <linux/crc16.h>
 #include <linux/slab.h>
+#include <linux/random.h>
 #include "ubifs.h"
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
@@ -116,8 +117,8 @@
 		return 0;
 	cnt += 1;
 	while (1) {
-		ubifs_assert(!test_bit(COW_ZNODE, &cnode->flags));
-		__set_bit(COW_ZNODE, &cnode->flags);
+		ubifs_assert(!test_bit(COW_CNODE, &cnode->flags));
+		__set_bit(COW_CNODE, &cnode->flags);
 		cnext = next_dirty_cnode(cnode);
 		if (!cnext) {
 			cnode->cnext = c->lpt_cnext;
@@ -465,7 +466,7 @@
 		 */
 		clear_bit(DIRTY_CNODE, &cnode->flags);
 		smp_mb__before_clear_bit();
-		clear_bit(COW_ZNODE, &cnode->flags);
+		clear_bit(COW_CNODE, &cnode->flags);
 		smp_mb__after_clear_bit();
 		offs += len;
 		dbg_chk_lpt_sz(c, 1, len);
@@ -1160,11 +1161,11 @@
 	void *buf = c->lpt_buf;
 
 	dbg_lp("LEB %d", lnum);
-	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
-	if (err) {
-		ubifs_err("cannot read LEB %d, error %d", lnum, err);
+
+	err = ubifs_leb_read(c, lnum, buf, 0, c->leb_size, 1);
+	if (err)
 		return err;
-	}
+
 	while (1) {
 		if (!is_a_node(c, buf, len)) {
 			int pad_len;
@@ -1640,7 +1641,7 @@
 	int ret;
 	void *buf, *p;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+	if (!dbg_is_chk_lprops(c))
 		return 0;
 
 	buf = p = __vmalloc(c->leb_size, GFP_NOFS, PAGE_KERNEL);
@@ -1650,11 +1651,11 @@
 	}
 
 	dbg_lp("LEB %d", lnum);
-	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
-	if (err) {
-		dbg_msg("ubi_read failed, LEB %d, error %d", lnum, err);
+
+	err = ubifs_leb_read(c, lnum, buf, 0, c->leb_size, 1);
+	if (err)
 		goto out;
-	}
+
 	while (1) {
 		if (!is_a_node(c, p, len)) {
 			int i, pad_len;
@@ -1711,7 +1712,7 @@
 {
 	int lnum, err, i, cnt;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+	if (!dbg_is_chk_lprops(c))
 		return 0;
 
 	/* Bring the entire tree into memory */
@@ -1754,7 +1755,7 @@
 	long long free = 0;
 	int i;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+	if (!dbg_is_chk_lprops(c))
 		return 0;
 
 	for (i = 0; i < c->lpt_lebs; i++) {
@@ -1796,7 +1797,7 @@
 	long long chk_lpt_sz, lpt_sz;
 	int err = 0;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+	if (!dbg_is_chk_lprops(c))
 		return 0;
 
 	switch (action) {
@@ -1901,11 +1902,10 @@
 		return;
 	}
 
-	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
-	if (err) {
-		ubifs_err("cannot read LEB %d, error %d", lnum, err);
+	err = ubifs_leb_read(c, lnum, buf, 0, c->leb_size, 1);
+	if (err)
 		goto out;
-	}
+
 	while (1) {
 		offs = c->leb_size - len;
 		if (!is_a_node(c, p, len)) {
@@ -2019,7 +2019,7 @@
 	struct ubifs_lpt_heap *heap;
 	int i;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 	if (random32() & 3)
 		return 0;
diff --git a/fs/ubifs/misc.h b/fs/ubifs/misc.h
index 0b5296a..ee7cb5e 100644
--- a/fs/ubifs/misc.h
+++ b/fs/ubifs/misc.h
@@ -39,6 +39,29 @@
 }
 
 /**
+ * ubifs_zn_obsolete - check if znode is obsolete.
+ * @znode: znode to check
+ *
+ * This helper function returns %1 if @znode is obsolete and %0 otherwise.
+ */
+static inline int ubifs_zn_obsolete(const struct ubifs_znode *znode)
+{
+	return !!test_bit(OBSOLETE_ZNODE, &znode->flags);
+}
+
+/**
+ * ubifs_zn_cow - check if znode has to be copied on write.
+ * @znode: znode to check
+ *
+ * This helper function returns %1 if @znode is has COW flag set and %0
+ * otherwise.
+ */
+static inline int ubifs_zn_cow(const struct ubifs_znode *znode)
+{
+	return !!test_bit(COW_ZNODE, &znode->flags);
+}
+
+/**
  * ubifs_wake_up_bgt - wake up background thread.
  * @c: UBIFS file-system description object
  */
@@ -122,86 +145,6 @@
 }
 
 /**
- * ubifs_leb_unmap - unmap an LEB.
- * @c: UBIFS file-system description object
- * @lnum: LEB number to unmap
- *
- * This function returns %0 on success and a negative error code on failure.
- */
-static inline int ubifs_leb_unmap(const struct ubifs_info *c, int lnum)
-{
-	int err;
-
-	ubifs_assert(!c->ro_media && !c->ro_mount);
-	if (c->ro_error)
-		return -EROFS;
-	err = ubi_leb_unmap(c->ubi, lnum);
-	if (err) {
-		ubifs_err("unmap LEB %d failed, error %d", lnum, err);
-		return err;
-	}
-
-	return 0;
-}
-
-/**
- * ubifs_leb_write - write to a LEB.
- * @c: UBIFS file-system description object
- * @lnum: LEB number to write
- * @buf: buffer to write from
- * @offs: offset within LEB to write to
- * @len: length to write
- * @dtype: data type
- *
- * This function returns %0 on success and a negative error code on failure.
- */
-static inline int ubifs_leb_write(const struct ubifs_info *c, int lnum,
-				  const void *buf, int offs, int len, int dtype)
-{
-	int err;
-
-	ubifs_assert(!c->ro_media && !c->ro_mount);
-	if (c->ro_error)
-		return -EROFS;
-	err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
-	if (err) {
-		ubifs_err("writing %d bytes at %d:%d, error %d",
-			  len, lnum, offs, err);
-		return err;
-	}
-
-	return 0;
-}
-
-/**
- * ubifs_leb_change - atomic LEB change.
- * @c: UBIFS file-system description object
- * @lnum: LEB number to write
- * @buf: buffer to write from
- * @len: length to write
- * @dtype: data type
- *
- * This function returns %0 on success and a negative error code on failure.
- */
-static inline int ubifs_leb_change(const struct ubifs_info *c, int lnum,
-				   const void *buf, int len, int dtype)
-{
-	int err;
-
-	ubifs_assert(!c->ro_media && !c->ro_mount);
-	if (c->ro_error)
-		return -EROFS;
-	err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
-	if (err) {
-		ubifs_err("changing %d bytes in LEB %d, error %d",
-			  len, lnum, err);
-		return err;
-	}
-
-	return 0;
-}
-
-/**
  * ubifs_encode_dev - encode device node IDs.
  * @dev: UBIFS device node information
  * @rdev: device IDs to encode
diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
index a5422ff..c542c73 100644
--- a/fs/ubifs/orphan.c
+++ b/fs/ubifs/orphan.c
@@ -929,7 +929,7 @@
 	struct check_info ci;
 	int err;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_ORPH))
+	if (!dbg_is_chk_orph(c))
 		return 0;
 
 	ci.last_ino = 0;
diff --git a/fs/ubifs/recovery.c b/fs/ubifs/recovery.c
index 783d8e0..af02790 100644
--- a/fs/ubifs/recovery.c
+++ b/fs/ubifs/recovery.c
@@ -117,7 +117,7 @@
 	if (!sbuf)
 		return -ENOMEM;
 
-	err = ubi_read(c->ubi, lnum, sbuf, 0, c->leb_size);
+	err = ubifs_leb_read(c, lnum, sbuf, 0, c->leb_size, 0);
 	if (err && err != -EBADMSG)
 		goto out_free;
 
@@ -213,10 +213,10 @@
 	mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);
 
 	ubifs_prepare_node(c, mst, UBIFS_MST_NODE_SZ, 1);
-	err = ubi_leb_change(c->ubi, lnum, mst, sz, UBI_SHORTTERM);
+	err = ubifs_leb_change(c, lnum, mst, sz, UBI_SHORTTERM);
 	if (err)
 		goto out;
-	err = ubi_leb_change(c->ubi, lnum + 1, mst, sz, UBI_SHORTTERM);
+	err = ubifs_leb_change(c, lnum + 1, mst, sz, UBI_SHORTTERM);
 	if (err)
 		goto out;
 out:
@@ -274,7 +274,8 @@
 				if (cor1)
 					goto out_err;
 				mst = mst1;
-			} else if (offs1 == 0 && offs2 + sz >= c->leb_size) {
+			} else if (offs1 == 0 &&
+				   c->leb_size - offs2 - sz < sz) {
 				/* 1st LEB was unmapped and written, 2nd not */
 				if (cor1)
 					goto out_err;
@@ -539,8 +540,8 @@
 			int len = ALIGN(endpt, c->min_io_size);
 
 			if (start) {
-				err = ubi_read(c->ubi, lnum, sleb->buf, 0,
-					       start);
+				err = ubifs_leb_read(c, lnum, sleb->buf, 0,
+						     start, 1);
 				if (err)
 					return err;
 			}
@@ -554,8 +555,8 @@
 					ubifs_pad(c, buf, pad_len);
 				}
 			}
-			err = ubi_leb_change(c->ubi, lnum, sleb->buf, len,
-					     UBI_UNKNOWN);
+			err = ubifs_leb_change(c, lnum, sleb->buf, len,
+					       UBI_UNKNOWN);
 			if (err)
 				return err;
 		}
@@ -819,7 +820,8 @@
 		return -ENOMEM;
 	if (c->leb_size - offs < UBIFS_CS_NODE_SZ)
 		goto out_err;
-	err = ubi_read(c->ubi, lnum, (void *)cs_node, offs, UBIFS_CS_NODE_SZ);
+	err = ubifs_leb_read(c, lnum, (void *)cs_node, offs,
+			     UBIFS_CS_NODE_SZ, 0);
 	if (err && err != -EBADMSG)
 		goto out_free;
 	ret = ubifs_scan_a_node(c, cs_node, UBIFS_CS_NODE_SZ, lnum, offs, 0);
@@ -919,8 +921,7 @@
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int recover_head(const struct ubifs_info *c, int lnum, int offs,
-			void *sbuf)
+static int recover_head(struct ubifs_info *c, int lnum, int offs, void *sbuf)
 {
 	int len = c->max_write_size, err;
 
@@ -931,15 +932,15 @@
 		return 0;
 
 	/* Read at the head location and check it is empty flash */
-	err = ubi_read(c->ubi, lnum, sbuf, offs, len);
+	err = ubifs_leb_read(c, lnum, sbuf, offs, len, 1);
 	if (err || !is_empty(sbuf, len)) {
 		dbg_rcvry("cleaning head at %d:%d", lnum, offs);
 		if (offs == 0)
 			return ubifs_leb_unmap(c, lnum);
-		err = ubi_read(c->ubi, lnum, sbuf, 0, offs);
+		err = ubifs_leb_read(c, lnum, sbuf, 0, offs, 1);
 		if (err)
 			return err;
-		return ubi_leb_change(c->ubi, lnum, sbuf, offs, UBI_UNKNOWN);
+		return ubifs_leb_change(c, lnum, sbuf, offs, UBI_UNKNOWN);
 	}
 
 	return 0;
@@ -962,7 +963,7 @@
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-int ubifs_recover_inl_heads(const struct ubifs_info *c, void *sbuf)
+int ubifs_recover_inl_heads(struct ubifs_info *c, void *sbuf)
 {
 	int err;
 
@@ -993,7 +994,7 @@
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int clean_an_unclean_leb(const struct ubifs_info *c,
+static int clean_an_unclean_leb(struct ubifs_info *c,
 				struct ubifs_unclean_leb *ucleb, void *sbuf)
 {
 	int err, lnum = ucleb->lnum, offs = 0, len = ucleb->endpt, quiet = 1;
@@ -1009,7 +1010,7 @@
 		return 0;
 	}
 
-	err = ubi_read(c->ubi, lnum, buf, offs, len);
+	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
 	if (err && err != -EBADMSG)
 		return err;
 
@@ -1069,7 +1070,7 @@
 	}
 
 	/* Write back the LEB atomically */
-	err = ubi_leb_change(c->ubi, lnum, sbuf, len, UBI_UNKNOWN);
+	err = ubifs_leb_change(c, lnum, sbuf, len, UBI_UNKNOWN);
 	if (err)
 		return err;
 
@@ -1089,7 +1090,7 @@
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-int ubifs_clean_lebs(const struct ubifs_info *c, void *sbuf)
+int ubifs_clean_lebs(struct ubifs_info *c, void *sbuf)
 {
 	dbg_rcvry("recovery");
 	while (!list_empty(&c->unclean_leb_list)) {
@@ -1454,7 +1455,7 @@
 	if (i_size >= e->d_size)
 		return 0;
 	/* Read the LEB */
-	err = ubi_read(c->ubi, lnum, c->sbuf, 0, c->leb_size);
+	err = ubifs_leb_read(c, lnum, c->sbuf, 0, c->leb_size, 1);
 	if (err)
 		goto out;
 	/* Change the size field and recalculate the CRC */
@@ -1470,7 +1471,7 @@
 		len -= 1;
 	len = ALIGN(len + 1, c->min_io_size);
 	/* Atomically write the fixed LEB back again */
-	err = ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);
+	err = ubifs_leb_change(c, lnum, c->sbuf, len, UBI_UNKNOWN);
 	if (err)
 		goto out;
 	dbg_rcvry("inode %lu at %d:%d size %lld -> %lld",
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 5e97161..ccabaf1 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -523,8 +523,7 @@
 	if (!list_is_last(&next->list, &jh->buds_list))
 		return 0;
 
-	err = ubi_read(c->ubi, next->lnum, (char *)&data,
-		       next->start, 4);
+	err = ubifs_leb_read(c, next->lnum, (char *)&data, next->start, 4, 1);
 	if (err)
 		return 0;
 
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index c606f01..93d938a 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -674,15 +674,15 @@
 
 	if (len == 0) {
 		dbg_mnt("unmap empty LEB %d", lnum);
-		return ubi_leb_unmap(c->ubi, lnum);
+		return ubifs_leb_unmap(c, lnum);
 	}
 
 	dbg_mnt("fixup LEB %d, data len %d", lnum, len);
-	err = ubi_read(c->ubi, lnum, c->sbuf, 0, len);
+	err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
 	if (err)
 		return err;
 
-	return ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);
+	return ubifs_leb_change(c, lnum, c->sbuf, len, UBI_UNKNOWN);
 }
 
 /**
diff --git a/fs/ubifs/scan.c b/fs/ubifs/scan.c
index 36216b4..37383e8 100644
--- a/fs/ubifs/scan.c
+++ b/fs/ubifs/scan.c
@@ -148,7 +148,7 @@
 	INIT_LIST_HEAD(&sleb->nodes);
 	sleb->buf = sbuf;
 
-	err = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
+	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
 	if (err && err != -EBADMSG) {
 		ubifs_err("cannot read %d bytes from LEB %d:%d,"
 			  " error %d", c->leb_size - offs, lnum, offs, err);
@@ -240,7 +240,7 @@
 	int len;
 
 	ubifs_err("corruption at LEB %d:%d", lnum, offs);
-	if (dbg_failure_mode)
+	if (dbg_is_tst_rcvry(c))
 		return;
 	len = c->leb_size - offs;
 	if (len > 8192)
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 529be05..b281212 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -85,7 +85,7 @@
 	if (ui->data_len < 0 || ui->data_len > UBIFS_MAX_INO_DATA)
 		return 4;
 
-	if (ui->xattr && (inode->i_mode & S_IFMT) != S_IFREG)
+	if (ui->xattr && !S_ISREG(inode->i_mode))
 		return 5;
 
 	if (!ubifs_compr_present(ui->compr_type)) {
@@ -94,7 +94,7 @@
 			   ubifs_compr_name(ui->compr_type));
 	}
 
-	err = dbg_check_dir_size(c, inode);
+	err = dbg_check_dir(c, inode);
 	return err;
 }
 
@@ -914,7 +914,7 @@
 
 	c->empty = 1;
 	for (lnum = 0; lnum < c->leb_cnt; lnum++) {
-		err = ubi_is_mapped(c->ubi, lnum);
+		err = ubifs_is_mapped(c, lnum);
 		if (unlikely(err < 0))
 			return err;
 		if (err == 1) {
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 91b4213..0667386 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -223,7 +223,7 @@
 	__set_bit(DIRTY_ZNODE, &zn->flags);
 	__clear_bit(COW_ZNODE, &zn->flags);
 
-	ubifs_assert(!test_bit(OBSOLETE_ZNODE, &znode->flags));
+	ubifs_assert(!ubifs_zn_obsolete(znode));
 	__set_bit(OBSOLETE_ZNODE, &znode->flags);
 
 	if (znode->level != 0) {
@@ -271,7 +271,7 @@
 	struct ubifs_znode *zn;
 	int err;
 
-	if (!test_bit(COW_ZNODE, &znode->flags)) {
+	if (!ubifs_zn_cow(znode)) {
 		/* znode is not being committed */
 		if (!test_and_set_bit(DIRTY_ZNODE, &znode->flags)) {
 			atomic_long_inc(&c->dirty_zn_cnt);
@@ -462,7 +462,7 @@
 
 	dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
 
-	err = ubi_read(c->ubi, lnum, buf, offs, len);
+	err = ubifs_leb_read(c, lnum, buf, offs, len, 1);
 	if (err) {
 		ubifs_err("cannot read node type %d from LEB %d:%d, error %d",
 			  type, lnum, offs, err);
@@ -1666,7 +1666,7 @@
 	if (!overlap) {
 		/* We may safely unlock the write-buffer and read the data */
 		spin_unlock(&wbuf->lock);
-		return ubi_read(c->ubi, lnum, buf, offs, len);
+		return ubifs_leb_read(c, lnum, buf, offs, len, 0);
 	}
 
 	/* Don't read under wbuf */
@@ -1680,7 +1680,7 @@
 
 	if (rlen > 0)
 		/* Read everything that goes before write-buffer */
-		return ubi_read(c->ubi, lnum, buf, offs, rlen);
+		return ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
 
 	return 0;
 }
@@ -1767,7 +1767,7 @@
 	if (wbuf)
 		err = read_wbuf(wbuf, bu->buf, len, lnum, offs);
 	else
-		err = ubi_read(c->ubi, lnum, bu->buf, offs, len);
+		err = ubifs_leb_read(c, lnum, bu->buf, offs, len, 0);
 
 	/* Check for a race with GC */
 	if (maybe_leb_gced(c, lnum, bu->gc_seq))
@@ -2423,7 +2423,7 @@
 	 */
 
 	do {
-		ubifs_assert(!test_bit(OBSOLETE_ZNODE, &znode->flags));
+		ubifs_assert(!ubifs_zn_obsolete(znode));
 		ubifs_assert(ubifs_zn_dirty(znode));
 
 		zp = znode->parent;
@@ -2479,9 +2479,8 @@
 			c->zroot.offs = zbr->offs;
 			c->zroot.len = zbr->len;
 			c->zroot.znode = znode;
-			ubifs_assert(!test_bit(OBSOLETE_ZNODE,
-				     &zp->flags));
-			ubifs_assert(test_bit(DIRTY_ZNODE, &zp->flags));
+			ubifs_assert(!ubifs_zn_obsolete(zp));
+			ubifs_assert(ubifs_zn_dirty(zp));
 			atomic_long_dec(&c->dirty_zn_cnt);
 
 			if (zp->cnext) {
@@ -2865,7 +2864,7 @@
 		struct ubifs_znode *znode = cnext;
 
 		cnext = cnext->cnext;
-		if (test_bit(OBSOLETE_ZNODE, &znode->flags))
+		if (ubifs_zn_obsolete(znode))
 			kfree(znode);
 	} while (cnext && cnext != c->cnext);
 }
@@ -3301,7 +3300,7 @@
 
 	if (!S_ISREG(inode->i_mode))
 		return 0;
-	if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
+	if (!dbg_is_chk_gen(c))
 		return 0;
 
 	block = (size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
@@ -3337,9 +3336,10 @@
 	ubifs_err("inode %lu has size %lld, but there are data at offset %lld "
 		  "(data key %s)", (unsigned long)inode->i_ino, size,
 		  ((loff_t)block) << UBIFS_BLOCK_SHIFT, DBGKEY(key));
+	mutex_unlock(&c->tnc_mutex);
 	dbg_dump_inode(c, inode);
 	dbg_dump_stack();
-	err = -EINVAL;
+	return -EINVAL;
 
 out_unlock:
 	mutex_unlock(&c->tnc_mutex);
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
index 41920f3..4c15f07 100644
--- a/fs/ubifs/tnc_commit.c
+++ b/fs/ubifs/tnc_commit.c
@@ -22,6 +22,7 @@
 
 /* This file implements TNC functions for committing */
 
+#include <linux/random.h>
 #include "ubifs.h"
 
 /**
@@ -87,8 +88,12 @@
 	atomic_long_dec(&c->dirty_zn_cnt);
 
 	ubifs_assert(ubifs_zn_dirty(znode));
-	ubifs_assert(test_bit(COW_ZNODE, &znode->flags));
+	ubifs_assert(ubifs_zn_cow(znode));
 
+	/*
+	 * Note, unlike 'write_index()' we do not add memory barriers here
+	 * because this function is called with @c->tnc_mutex locked.
+	 */
 	__clear_bit(DIRTY_ZNODE, &znode->flags);
 	__clear_bit(COW_ZNODE, &znode->flags);
 
@@ -377,7 +382,7 @@
 				c->gap_lebs = NULL;
 				return err;
 			}
-			if (dbg_force_in_the_gaps_enabled()) {
+			if (!dbg_is_chk_index(c)) {
 				/*
 				 * Do not print scary warnings if the debugging
 				 * option which forces in-the-gaps is enabled.
@@ -491,25 +496,6 @@
 		else
 			next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
 
-		if (c->min_io_size == 1) {
-			buf_offs += ALIGN(len, 8);
-			if (next_len) {
-				if (buf_offs + next_len <= c->leb_size)
-					continue;
-				err = ubifs_update_one_lp(c, lnum, 0,
-						c->leb_size - buf_offs, 0, 0);
-				if (err)
-					return err;
-				lnum = -1;
-				continue;
-			}
-			err = ubifs_update_one_lp(c, lnum,
-					c->leb_size - buf_offs, 0, 0, 0);
-			if (err)
-				return err;
-			break;
-		}
-
 		/* Update buffer positions */
 		wlen = used + len;
 		used += ALIGN(len, 8);
@@ -658,7 +644,7 @@
 	}
 	cnt += 1;
 	while (1) {
-		ubifs_assert(!test_bit(COW_ZNODE, &znode->flags));
+		ubifs_assert(!ubifs_zn_cow(znode));
 		__set_bit(COW_ZNODE, &znode->flags);
 		znode->alt = 0;
 		cnext = find_next_dirty(znode);
@@ -704,7 +690,7 @@
 		c->ilebs[c->ileb_cnt++] = lnum;
 		dbg_cmt("LEB %d", lnum);
 	}
-	if (dbg_force_in_the_gaps())
+	if (dbg_is_chk_index(c) && !(random32() & 7))
 		return -ENOSPC;
 	return 0;
 }
@@ -830,7 +816,7 @@
 	struct ubifs_idx_node *idx;
 	struct ubifs_znode *znode, *cnext;
 	int i, lnum, offs, len, next_len, buf_len, buf_offs, used;
-	int avail, wlen, err, lnum_pos = 0;
+	int avail, wlen, err, lnum_pos = 0, blen, nxt_offs;
 
 	cnext = c->enext;
 	if (!cnext)
@@ -907,7 +893,7 @@
 		cnext = znode->cnext;
 
 		ubifs_assert(ubifs_zn_dirty(znode));
-		ubifs_assert(test_bit(COW_ZNODE, &znode->flags));
+		ubifs_assert(ubifs_zn_cow(znode));
 
 		/*
 		 * It is important that other threads should see %DIRTY_ZNODE
@@ -922,6 +908,28 @@
 		clear_bit(COW_ZNODE, &znode->flags);
 		smp_mb__after_clear_bit();
 
+		/*
+		 * We have marked the znode as clean but have not updated the
+		 * @c->clean_zn_cnt counter. If this znode becomes dirty again
+		 * before 'free_obsolete_znodes()' is called, then
+		 * @c->clean_zn_cnt will be decremented before it gets
+		 * incremented (resulting in 2 decrements for the same znode).
+		 * This means that @c->clean_zn_cnt may become negative for a
+		 * while.
+		 *
+		 * Q: why we cannot increment @c->clean_zn_cnt?
+		 * A: because we do not have the @c->tnc_mutex locked, and the
+		 *    following code would be racy and buggy:
+		 *
+		 *    if (!ubifs_zn_obsolete(znode)) {
+		 *            atomic_long_inc(&c->clean_zn_cnt);
+		 *            atomic_long_inc(&ubifs_clean_zn_cnt);
+		 *    }
+		 *
+		 *    Thus, we just delay the @c->clean_zn_cnt update until we
+		 *    have the mutex locked.
+		 */
+
 		/* Do not access znode from this point on */
 
 		/* Update buffer positions */
@@ -938,65 +946,38 @@
 		else
 			next_len = ubifs_idx_node_sz(c, cnext->child_cnt);
 
-		if (c->min_io_size == 1) {
-			/*
-			 * Write the prepared index node immediately if there is
-			 * no minimum IO size
-			 */
-			err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs,
-					      wlen, UBI_SHORTTERM);
-			if (err)
-				return err;
-			buf_offs += ALIGN(wlen, 8);
-			if (next_len) {
-				used = 0;
-				avail = buf_len;
-				if (buf_offs + next_len > c->leb_size) {
-					err = ubifs_update_one_lp(c, lnum,
-						LPROPS_NC, 0, 0, LPROPS_TAKEN);
-					if (err)
-						return err;
-					lnum = -1;
-				}
+		nxt_offs = buf_offs + used + next_len;
+		if (next_len && nxt_offs <= c->leb_size) {
+			if (avail > 0)
 				continue;
-			}
+			else
+				blen = buf_len;
 		} else {
-			int blen, nxt_offs = buf_offs + used + next_len;
+			wlen = ALIGN(wlen, 8);
+			blen = ALIGN(wlen, c->min_io_size);
+			ubifs_pad(c, c->cbuf + wlen, blen - wlen);
+		}
 
-			if (next_len && nxt_offs <= c->leb_size) {
-				if (avail > 0)
-					continue;
-				else
-					blen = buf_len;
-			} else {
-				wlen = ALIGN(wlen, 8);
-				blen = ALIGN(wlen, c->min_io_size);
-				ubifs_pad(c, c->cbuf + wlen, blen - wlen);
+		/* The buffer is full or there are no more znodes to do */
+		err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs, blen,
+				      UBI_SHORTTERM);
+		if (err)
+			return err;
+		buf_offs += blen;
+		if (next_len) {
+			if (nxt_offs > c->leb_size) {
+				err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0,
+							  0, LPROPS_TAKEN);
+				if (err)
+					return err;
+				lnum = -1;
 			}
-			/*
-			 * The buffer is full or there are no more znodes
-			 * to do
-			 */
-			err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs,
-					      blen, UBI_SHORTTERM);
-			if (err)
-				return err;
-			buf_offs += blen;
-			if (next_len) {
-				if (nxt_offs > c->leb_size) {
-					err = ubifs_update_one_lp(c, lnum,
-						LPROPS_NC, 0, 0, LPROPS_TAKEN);
-					if (err)
-						return err;
-					lnum = -1;
-				}
-				used -= blen;
-				if (used < 0)
-					used = 0;
-				avail = buf_len - used;
-				memmove(c->cbuf, c->cbuf + blen, used);
-				continue;
-			}
+			used -= blen;
+			if (used < 0)
+				used = 0;
+			avail = buf_len - used;
+			memmove(c->cbuf, c->cbuf + blen, used);
+			continue;
 		}
 		break;
 	}
@@ -1029,7 +1010,7 @@
 	do {
 		znode = cnext;
 		cnext = znode->cnext;
-		if (test_bit(OBSOLETE_ZNODE, &znode->flags))
+		if (ubifs_zn_obsolete(znode))
 			kfree(znode);
 		else {
 			znode->cnext = NULL;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index f79983d..702b792 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -230,14 +230,14 @@
  * LPT cnode flag bits.
  *
  * DIRTY_CNODE: cnode is dirty
- * COW_CNODE: cnode is being committed and must be copied before writing
  * OBSOLETE_CNODE: cnode is being committed and has been copied (or deleted),
- * so it can (and must) be freed when the commit is finished
+ *                 so it can (and must) be freed when the commit is finished
+ * COW_CNODE: cnode is being committed and must be copied before writing
  */
 enum {
 	DIRTY_CNODE    = 0,
-	COW_CNODE      = 1,
-	OBSOLETE_CNODE = 2,
+	OBSOLETE_CNODE = 1,
+	COW_CNODE      = 2,
 };
 
 /*
@@ -1468,6 +1468,15 @@
 
 /* io.c */
 void ubifs_ro_mode(struct ubifs_info *c, int err);
+int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
+		   int len, int even_ebadmsg);
+int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
+		    int len, int dtype);
+int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len,
+		     int dtype);
+int ubifs_leb_unmap(struct ubifs_info *c, int lnum);
+int ubifs_leb_map(struct ubifs_info *c, int lnum, int dtype);
+int ubifs_is_mapped(const struct ubifs_info *c, int lnum);
 int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len);
 int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs,
 			   int dtype);
@@ -1747,8 +1756,8 @@
 					 int offs, void *sbuf, int jhead);
 struct ubifs_scan_leb *ubifs_recover_log_leb(struct ubifs_info *c, int lnum,
 					     int offs, void *sbuf);
-int ubifs_recover_inl_heads(const struct ubifs_info *c, void *sbuf);
-int ubifs_clean_lebs(const struct ubifs_info *c, void *sbuf);
+int ubifs_recover_inl_heads(struct ubifs_info *c, void *sbuf);
+int ubifs_clean_lebs(struct ubifs_info *c, void *sbuf);
 int ubifs_rcvry_gc_commit(struct ubifs_info *c);
 int ubifs_recover_size_accum(struct ubifs_info *c, union ubifs_key *key,
 			     int deletion, loff_t new_size);