Merge commit 'ubifs/linux-next'

17 files changed, 731 insertions, 285 deletions

diff --git a/Documentation/filesystems/ubifs.txt b/Documentation/filesystems/ubifs.txt
index dd84ea3c10da..2d0db5482d29 100644
--- a/Documentation/filesystems/ubifs.txt
+++ b/Documentation/filesystems/ubifs.txt
@@ -95,6 +95,9 @@ no_chk_data_crc		skip checking of CRCs on data nodes in order to
 			of this option is that corruption of the contents
 			of a file can go unnoticed.
 chk_data_crc (*)	do not skip checking CRCs on data nodes
+compr=none              override defoult comressor and set it to "none"
+compr=lzo               override defoult comressor and set it to "lzo"
+compr=zlib              override defoult comressor and set it to "zlib"
 
 
 Quick usage instructions
diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
index 4a18f084cc42..4ebe76337c62 100644
--- a/fs/ubifs/budget.c
+++ b/fs/ubifs/budget.c
@@ -32,7 +32,7 @@
 
 #include "ubifs.h"
 #include <linux/writeback.h>
-#include <asm/div64.h>
+#include <linux/math64.h>
 
 /*
  * When pessimistic budget calculations say that there is no enough space,
@@ -258,8 +258,8 @@ static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
  */
 int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
 {
-	int ret;
-	uint64_t idx_size;
+	int idx_lebs, eff_leb_size = c->leb_size - c->max_idx_node_sz;
+	long long idx_size;
 
 	idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;
 
@@ -271,23 +271,16 @@ int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
 	 * pair, nor similarly the two variables for the new index size, so we
 	 * have to do this costly 64-bit division on fast-path.
 	 */
-	if (do_div(idx_size, c->leb_size - c->max_idx_node_sz))
-		ret = idx_size + 1;
-	else
-		ret = idx_size;
+	idx_size += eff_leb_size - 1;
+	idx_lebs = div_u64(idx_size, eff_leb_size);
 	/*
 	 * The index head is not available for the in-the-gaps method, so add an
 	 * extra LEB to compensate.
 	 */
-	ret += 1;
-	/*
-	 * At present the index needs at least 2 LEBs: one for the index head
-	 * and one for in-the-gaps method (which currently does not cater for
-	 * the index head and so excludes it from consideration).
-	 */
-	if (ret < 2)
-		ret = 2;
-	return ret;
+	idx_lebs += 1;
+	if (idx_lebs < MIN_INDEX_LEBS)
+		idx_lebs = MIN_INDEX_LEBS;
+	return idx_lebs;
 }
 
 /**
@@ -713,8 +706,8 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
  * (e.g., via the 'statfs()' call) reports that it has N bytes available, they
  * are able to write a file of size N. UBIFS attaches node headers to each data
  * node and it has to write indexind nodes as well. This introduces additional
- * overhead, and UBIFS it has to report sligtly less free space to meet the
- * above expectetion.
+ * overhead, and UBIFS has to report sligtly less free space to meet the above
+ * expectetions.
  *
  * This function assumes free space is made up of uncompressed data nodes and
  * full index nodes (one per data node, tripled because we always allow enough
@@ -723,7 +716,7 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
  * Note, the calculation is pessimistic, which means that most of the time
  * UBIFS reports less space than it actually has.
  */
-long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
+long long ubifs_reported_space(const struct ubifs_info *c, long long free)
 {
 	int divisor, factor, f;
 
@@ -745,8 +738,7 @@ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
 	divisor = UBIFS_MAX_DATA_NODE_SZ;
 	divisor += (c->max_idx_node_sz * 3) / (f - 1);
 	free *= factor;
-	do_div(free, divisor);
-	return free;
+	return div_u64(free, divisor);
 }
 
 /**
@@ -771,7 +763,8 @@ long long ubifs_get_free_space(struct ubifs_info *c)
 	long long available, outstanding, free;
 
 	spin_lock(&c->space_lock);
-	min_idx_lebs = ubifs_calc_min_idx_lebs(c);
+	min_idx_lebs = c->min_idx_lebs;
+	ubifs_assert(min_idx_lebs == ubifs_calc_min_idx_lebs(c));
 	outstanding = c->budg_data_growth + c->budg_dd_growth;
 
 	/*
diff --git a/fs/ubifs/commit.c b/fs/ubifs/commit.c
index b49884c8c10e..f3a7945527fb 100644
--- a/fs/ubifs/commit.c
+++ b/fs/ubifs/commit.c
@@ -470,12 +470,12 @@ int dbg_old_index_check_init(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 {
 	struct ubifs_idx_node *idx;
 	int lnum, offs, len, err = 0;
+	struct ubifs_debug_info *d = c->dbg;
 
-	c->old_zroot = *zroot;
-
-	lnum = c->old_zroot.lnum;
-	offs = c->old_zroot.offs;
-	len = c->old_zroot.len;
+	d->old_zroot = *zroot;
+	lnum = d->old_zroot.lnum;
+	offs = d->old_zroot.offs;
+	len = d->old_zroot.len;
 
 	idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
 	if (!idx)
@@ -485,8 +485,8 @@ int dbg_old_index_check_init(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 	if (err)
 		goto out;
 
-	c->old_zroot_level = le16_to_cpu(idx->level);
-	c->old_zroot_sqnum = le64_to_cpu(idx->ch.sqnum);
+	d->old_zroot_level = le16_to_cpu(idx->level);
+	d->old_zroot_sqnum = le64_to_cpu(idx->ch.sqnum);
 out:
 	kfree(idx);
 	return err;
@@ -509,6 +509,7 @@ int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 {
 	int lnum, offs, len, err = 0, uninitialized_var(last_level), child_cnt;
 	int first = 1, iip;
+	struct ubifs_debug_info *d = c->dbg;
 	union ubifs_key lower_key, upper_key, l_key, u_key;
 	unsigned long long uninitialized_var(last_sqnum);
 	struct ubifs_idx_node *idx;
@@ -525,9 +526,9 @@ int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 	     UBIFS_IDX_NODE_SZ;
 
 	/* Start at the old zroot */
-	lnum = c->old_zroot.lnum;
-	offs = c->old_zroot.offs;
-	len = c->old_zroot.len;
+	lnum = d->old_zroot.lnum;
+	offs = d->old_zroot.offs;
+	len = d->old_zroot.len;
 	iip = 0;
 
 	/*
@@ -560,11 +561,11 @@ int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 		if (first) {
 			first = 0;
 			/* Check root level and sqnum */
-			if (le16_to_cpu(idx->level) != c->old_zroot_level) {
+			if (le16_to_cpu(idx->level) != d->old_zroot_level) {
 				err = 2;
 				goto out_dump;
 			}
-			if (le64_to_cpu(idx->ch.sqnum) != c->old_zroot_sqnum) {
+			if (le64_to_cpu(idx->ch.sqnum) != d->old_zroot_sqnum) {
 				err = 3;
 				goto out_dump;
 			}
diff --git a/fs/ubifs/compress.c b/fs/ubifs/compress.c
index a0ada596b17c..4c90ee2aef46 100644
--- a/fs/ubifs/compress.c
+++ b/fs/ubifs/compress.c
@@ -33,7 +33,7 @@
 /* Fake description object for the "none" compressor */
 static struct ubifs_compressor none_compr = {
 	.compr_type = UBIFS_COMPR_NONE,
-	.name = "no compression",
+	.name = "none",
 	.capi_name = "",
 };
 
@@ -43,13 +43,13 @@ static DEFINE_MUTEX(lzo_mutex);
 static struct ubifs_compressor lzo_compr = {
 	.compr_type = UBIFS_COMPR_LZO,
 	.comp_mutex = &lzo_mutex,
-	.name = "LZO",
+	.name = "lzo",
 	.capi_name = "lzo",
 };
 #else
 static struct ubifs_compressor lzo_compr = {
 	.compr_type = UBIFS_COMPR_LZO,
-	.name = "LZO",
+	.name = "lzo",
 };
 #endif
 
@@ -119,10 +119,10 @@ void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
 	}
 
 	/*
-	 * Presently, we just require that compression results in less data,
-	 * rather than any defined minimum compression ratio or amount.
+	 * If the data compressed only slightly, it is better to leave it
+	 * uncompressed to improve read speed.
 	 */
-	if (ALIGN(*out_len, 8) >= ALIGN(in_len, 8))
+	if (in_len - *out_len < UBIFS_MIN_COMPRESS_DIFF)
 		goto no_compr;
 
 	return;
@@ -244,7 +244,7 @@ out_lzo:
 /**
  * ubifs_compressors_exit - de-initialize UBIFS compressors.
  */
-void __exit ubifs_compressors_exit(void)
+void ubifs_compressors_exit(void)
 {
 	compr_exit(&lzo_compr);
 	compr_exit(&zlib_compr);
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 510ffa0bbda4..a2be11584ad3 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -32,6 +32,8 @@
 #include "ubifs.h"
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/debugfs.h>
+#include <linux/math64.h>
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
 
@@ -596,7 +598,9 @@ void dbg_dump_budg(struct ubifs_info *c)
 	struct rb_node *rb;
 	struct ubifs_bud *bud;
 	struct ubifs_gced_idx_leb *idx_gc;
+	long long available, outstanding, free;
 
+	ubifs_assert(spin_is_locked(&c->space_lock));
 	spin_lock(&dbg_lock);
 	printk(KERN_DEBUG "(pid %d) Budgeting info: budg_data_growth %lld, "
 	       "budg_dd_growth %lld, budg_idx_growth %lld\n", current->pid,
@@ -629,6 +633,17 @@ void dbg_dump_budg(struct ubifs_info *c)
 		printk(KERN_DEBUG "\tGC'ed idx LEB %d unmap %d\n",
 		       idx_gc->lnum, idx_gc->unmap);
 	printk(KERN_DEBUG "\tcommit state %d\n", c->cmt_state);
+
+	/* Print budgeting predictions */
+	available = ubifs_calc_available(c, c->min_idx_lebs);
+	outstanding = c->budg_data_growth + c->budg_dd_growth;
+	if (available > outstanding)
+		free = ubifs_reported_space(c, available - outstanding);
+	else
+		free = 0;
+	printk(KERN_DEBUG "Budgeting predictions:\n");
+	printk(KERN_DEBUG "\tavailable: %lld, outstanding %lld, free %lld\n",
+	       available, outstanding, free);
 	spin_unlock(&dbg_lock);
 }
 
@@ -645,7 +660,8 @@ void dbg_dump_lprops(struct ubifs_info *c)
 	struct ubifs_lprops lp;
 	struct ubifs_lp_stats lst;
 
-	printk(KERN_DEBUG "(pid %d) Dumping LEB properties\n", current->pid);
+	printk(KERN_DEBUG "(pid %d) start dumping LEB properties\n",
+	       current->pid);
 	ubifs_get_lp_stats(c, &lst);
 	dbg_dump_lstats(&lst);
 
@@ -656,6 +672,8 @@ void dbg_dump_lprops(struct ubifs_info *c)
 
 		dbg_dump_lprop(c, &lp);
 	}
+	printk(KERN_DEBUG "(pid %d) finish dumping LEB properties\n",
+	       current->pid);
 }
 
 void dbg_dump_lpt_info(struct ubifs_info *c)
@@ -663,6 +681,7 @@ void dbg_dump_lpt_info(struct ubifs_info *c)
 	int i;
 
 	spin_lock(&dbg_lock);
+	printk(KERN_DEBUG "(pid %d) dumping LPT information\n", current->pid);
 	printk(KERN_DEBUG "\tlpt_sz:        %lld\n", c->lpt_sz);
 	printk(KERN_DEBUG "\tpnode_sz:      %d\n", c->pnode_sz);
 	printk(KERN_DEBUG "\tnnode_sz:      %d\n", c->nnode_sz);
@@ -703,9 +722,9 @@ void dbg_dump_leb(const struct ubifs_info *c, int lnum)
 	if (dbg_failure_mode)
 		return;
 
-	printk(KERN_DEBUG "(pid %d) Dumping LEB %d\n", current->pid, lnum);
-
-	sleb = ubifs_scan(c, lnum, 0, c->dbg_buf);
+	printk(KERN_DEBUG "(pid %d) start dumping LEB %d\n",
+	       current->pid, lnum);
+	sleb = ubifs_scan(c, lnum, 0, c->dbg->buf);
 	if (IS_ERR(sleb)) {
 		ubifs_err("scan error %d", (int)PTR_ERR(sleb));
 		return;
@@ -721,6 +740,8 @@ void dbg_dump_leb(const struct ubifs_info *c, int lnum)
 		dbg_dump_node(c, snod->node);
 	}
 
+	printk(KERN_DEBUG "(pid %d) finish dumping LEB %d\n",
+	       current->pid, lnum);
 	ubifs_scan_destroy(sleb);
 	return;
 }
@@ -768,7 +789,7 @@ void dbg_dump_heap(struct ubifs_info *c, struct ubifs_lpt_heap *heap, int cat)
 {
 	int i;
 
-	printk(KERN_DEBUG "(pid %d) Dumping heap cat %d (%d elements)\n",
+	printk(KERN_DEBUG "(pid %d) start dumping heap cat %d (%d elements)\n",
 	       current->pid, cat, heap->cnt);
 	for (i = 0; i < heap->cnt; i++) {
 		struct ubifs_lprops *lprops = heap->arr[i];
@@ -777,6 +798,7 @@ void dbg_dump_heap(struct ubifs_info *c, struct ubifs_lpt_heap *heap, int cat)
 		       "flags %d\n", i, lprops->lnum, lprops->hpos,
 		       lprops->free, lprops->dirty, lprops->flags);
 	}
+	printk(KERN_DEBUG "(pid %d) finish dumping heap\n", current->pid);
 }
 
 void dbg_dump_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
@@ -784,7 +806,7 @@ void dbg_dump_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
 {
 	int i;
 
-	printk(KERN_DEBUG "(pid %d) Dumping pnode:\n", current->pid);
+	printk(KERN_DEBUG "(pid %d) dumping pnode:\n", current->pid);
 	printk(KERN_DEBUG "\taddress %zx parent %zx cnext %zx\n",
 	       (size_t)pnode, (size_t)parent, (size_t)pnode->cnext);
 	printk(KERN_DEBUG "\tflags %lu iip %d level %d num %d\n",
@@ -803,7 +825,7 @@ void dbg_dump_tnc(struct ubifs_info *c)
 	int level;
 
 	printk(KERN_DEBUG "\n");
-	printk(KERN_DEBUG "(pid %d) Dumping the TNC tree\n", current->pid);
+	printk(KERN_DEBUG "(pid %d) start dumping TNC tree\n", current->pid);
 	znode = ubifs_tnc_levelorder_next(c->zroot.znode, NULL);
 	level = znode->level;
 	printk(KERN_DEBUG "== Level %d ==\n", level);
@@ -815,8 +837,7 @@ void dbg_dump_tnc(struct ubifs_info *c)
 		dbg_dump_znode(c, znode);
 		znode = ubifs_tnc_levelorder_next(c->zroot.znode, znode);
 	}
-
-	printk(KERN_DEBUG "\n");
+	printk(KERN_DEBUG "(pid %d) finish dumping TNC tree\n", current->pid);
 }
 
 static int dump_znode(struct ubifs_info *c, struct ubifs_znode *znode,
@@ -988,22 +1009,22 @@ static int dbg_check_key_order(struct ubifs_info *c, struct ubifs_zbranch *zbr1,
 	err = 1;
 	key_read(c, &dent1->key, &key);
 	if (keys_cmp(c, &zbr1->key, &key)) {
-		dbg_err("1st entry at %d:%d has key %s", zbr1->lnum,
-			zbr1->offs, DBGKEY(&key));
-		dbg_err("but it should have key %s according to tnc",
-			DBGKEY(&zbr1->key));
-			dbg_dump_node(c, dent1);
-			goto out_free;
+		ubifs_err("1st entry at %d:%d has key %s", zbr1->lnum,
+			  zbr1->offs, DBGKEY(&key));
+		ubifs_err("but it should have key %s according to tnc",
+			  DBGKEY(&zbr1->key));
+		dbg_dump_node(c, dent1);
+		goto out_free;
 	}
 
 	key_read(c, &dent2->key, &key);
 	if (keys_cmp(c, &zbr2->key, &key)) {
-		dbg_err("2nd entry at %d:%d has key %s", zbr1->lnum,
-			zbr1->offs, DBGKEY(&key));
-		dbg_err("but it should have key %s according to tnc",
-			DBGKEY(&zbr2->key));
-			dbg_dump_node(c, dent2);
-			goto out_free;
+		ubifs_err("2nd entry at %d:%d has key %s", zbr1->lnum,
+			  zbr1->offs, DBGKEY(&key));
+		ubifs_err("but it should have key %s according to tnc",
+			  DBGKEY(&zbr2->key));
+		dbg_dump_node(c, dent2);
+		goto out_free;
 	}
 
 	nlen1 = le16_to_cpu(dent1->nlen);
@@ -1015,14 +1036,14 @@ static int dbg_check_key_order(struct ubifs_info *c, struct ubifs_zbranch *zbr1,
 		goto out_free;
 	}
 	if (cmp == 0 && nlen1 == nlen2)
-		dbg_err("2 xent/dent nodes with the same name");
+		ubifs_err("2 xent/dent nodes with the same name");
 	else
-		dbg_err("bad order of colliding key %s",
+		ubifs_err("bad order of colliding key %s",
 			DBGKEY(&key));
 
-	dbg_msg("first node at %d:%d\n", zbr1->lnum, zbr1->offs);
+	ubifs_msg("first node at %d:%d\n", zbr1->lnum, zbr1->offs);
 	dbg_dump_node(c, dent1);
-	dbg_msg("second node at %d:%d\n", zbr2->lnum, zbr2->offs);
+	ubifs_msg("second node at %d:%d\n", zbr2->lnum, zbr2->offs);
 	dbg_dump_node(c, dent2);
 
 out_free:
@@ -2097,13 +2118,13 @@ static int simple_rand(void)
 	return (next >> 16) & 32767;
 }
 
-void dbg_failure_mode_registration(struct ubifs_info *c)
+static void failure_mode_init(struct ubifs_info *c)
 {
 	struct failure_mode_info *fmi;
 
 	fmi = kmalloc(sizeof(struct failure_mode_info), GFP_NOFS);
 	if (!fmi) {
-		dbg_err("Failed to register failure mode - no memory");
+		ubifs_err("Failed to register failure mode - no memory");
 		return;
 	}
 	fmi->c = c;
@@ -2112,7 +2133,7 @@ void dbg_failure_mode_registration(struct ubifs_info *c)
 	spin_unlock(&fmi_lock);
 }
 
-void dbg_failure_mode_deregistration(struct ubifs_info *c)
+static void failure_mode_exit(struct ubifs_info *c)
 {
 	struct failure_mode_info *fmi, *tmp;
 
@@ -2146,42 +2167,44 @@ 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->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;
-	if (c->failure_mode)
+	d = c->dbg;
+	if (d->failure_mode)
 		return 1;
-	if (!c->fail_cnt) {
+	if (!d->fail_cnt) {
 		/* First call - decide delay to failure */
 		if (chance(1, 2)) {
 			unsigned int delay = 1 << (simple_rand() >> 11);
 
 			if (chance(1, 2)) {
-				c->fail_delay = 1;
-				c->fail_timeout = jiffies +
+				d->fail_delay = 1;
+				d->fail_timeout = jiffies +
 						  msecs_to_jiffies(delay);
 				dbg_rcvry("failing after %ums", delay);
 			} else {
-				c->fail_delay = 2;
-				c->fail_cnt_max = delay;
+				d->fail_delay = 2;
+				d->fail_cnt_max = delay;
 				dbg_rcvry("failing after %u calls", delay);
 			}
 		}
-		c->fail_cnt += 1;
+		d->fail_cnt += 1;
 	}
 	/* Determine if failure delay has expired */
-	if (c->fail_delay == 1) {
-		if (time_before(jiffies, c->fail_timeout))
+	if (d->fail_delay == 1) {
+		if (time_before(jiffies, d->fail_timeout))
 			return 0;
-	} else if (c->fail_delay == 2)
-		if (c->fail_cnt++ < c->fail_cnt_max)
+	} else if (d->fail_delay == 2)
+		if (d->fail_cnt++ < d->fail_cnt_max)
 			return 0;
 	if (lnum == UBIFS_SB_LNUM) {
 		if (write) {
@@ -2239,7 +2262,7 @@ static int do_fail(struct ubi_volume_desc *desc, int lnum, int write)
 		dbg_rcvry("failing in bud LEB %d commit not running", lnum);
 	}
 	ubifs_err("*** SETTING FAILURE MODE ON (LEB %d) ***", lnum);
-	c->failure_mode = 1;
+	d->failure_mode = 1;
 	dump_stack();
 	return 1;
 }
@@ -2344,4 +2367,181 @@ int dbg_leb_map(struct ubi_volume_desc *desc, int lnum, int dtype)
 	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;
+
+	c->dbg->buf = vmalloc(c->leb_size);
+	if (!c->dbg->buf)
+		goto out;
+
+	failure_mode_init(c);
+	return 0;
+
+out:
+	kfree(c->dbg);
+	return -ENOMEM;
+}
+
+/**
+ * ubifs_debugging_exit - free debugging data.
+ * @c: UBIFS file-system description object
+ */
+void ubifs_debugging_exit(struct ubifs_info *c)
+{
+	failure_mode_exit(c);
+	vfree(c->dbg->buf);
+	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 *debugfs_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)
+{
+	debugfs_rootdir = debugfs_create_dir("ubifs", NULL);
+	if (IS_ERR(debugfs_rootdir)) {
+		int err = PTR_ERR(debugfs_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(debugfs_rootdir);
+}
+
+static int open_debugfs_file(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t write_debugfs_file(struct file *file, const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct ubifs_info *c = file->private_data;
+	struct ubifs_debug_info *d = c->dbg;
+
+	if (file->f_path.dentry == d->dump_lprops)
+		dbg_dump_lprops(c);
+	else if (file->f_path.dentry == d->dump_budg) {
+		spin_lock(&c->space_lock);
+		dbg_dump_budg(c);
+		spin_unlock(&c->space_lock);
+	} else if (file->f_path.dentry == d->dump_tnc) {
+		mutex_lock(&c->tnc_mutex);
+		dbg_dump_tnc(c);
+		mutex_unlock(&c->tnc_mutex);
+	} else
+		return -EINVAL;
+
+	*ppos += count;
+	return count;
+}
+
+static const struct file_operations debugfs_fops = {
+	.open = open_debugfs_file,
+	.write = write_debugfs_file,
+	.owner = THIS_MODULE,
+};
+
+/**
+ * dbg_debugfs_init_fs - initialize debugfs for UBIFS instance.
+ * @c: UBIFS file-system description object
+ *
+ * This function creates all debugfs files for this instance of UBIFS. Returns
+ * zero in case of success and a negative error code in case of failure.
+ *
+ * Note, the only reason we have not merged this function with the
+ * 'ubifs_debugging_init()' function is because it is better to initialize
+ * debugfs interfaces at the very end of the mount process, and remove them at
+ * the very beginning of the mount process.
+ */
+int dbg_debugfs_init_fs(struct ubifs_info *c)
+{
+	int err;
+	const char *fname;
+	struct dentry *dent;
+	struct ubifs_debug_info *d = c->dbg;
+
+	sprintf(d->debugfs_dir_name, "ubi%d_%d", c->vi.ubi_num, c->vi.vol_id);
+	d->debugfs_dir = debugfs_create_dir(d->debugfs_dir_name,
+					      debugfs_rootdir);
+	if (IS_ERR(d->debugfs_dir)) {
+		err = PTR_ERR(d->debugfs_dir);
+		ubifs_err("cannot create \"%s\" debugfs directory, error %d\n",
+			  d->debugfs_dir_name, err);
+		goto out;
+	}
+
+	fname = "dump_lprops";
+	dent = debugfs_create_file(fname, S_IWUGO, d->debugfs_dir, c,
+				   &debugfs_fops);
+	if (IS_ERR(dent))
+		goto out_remove;
+	d->dump_lprops = dent;
+
+	fname = "dump_budg";
+	dent = debugfs_create_file(fname, S_IWUGO, d->debugfs_dir, c,
+				   &debugfs_fops);
+	if (IS_ERR(dent))
+		goto out_remove;
+	d->dump_budg = dent;
+
+	fname = "dump_tnc";
+	dent = debugfs_create_file(fname, S_IWUGO, d->debugfs_dir, c,
+				   &debugfs_fops);
+	if (IS_ERR(dent))
+		goto out_remove;
+	d->dump_tnc = dent;
+
+	return 0;
+
+out_remove:
+	err = PTR_ERR(dent);
+	ubifs_err("cannot create \"%s\" debugfs directory, error %d\n",
+		  fname, err);
+	debugfs_remove_recursive(d->debugfs_dir);
+out:
+	return err;
+}
+
+/**
+ * dbg_debugfs_exit_fs - remove all debugfs files.
+ * @c: UBIFS file-system description object
+ */
+void dbg_debugfs_exit_fs(struct ubifs_info *c)
+{
+	debugfs_remove_recursive(c->dbg->debugfs_dir);
+}
+
 #endif /* CONFIG_UBIFS_FS_DEBUG */
diff --git a/fs/ubifs/debug.h b/fs/ubifs/debug.h
index 33d6b95071e4..9820d6999f7e 100644
--- a/fs/ubifs/debug.h
+++ b/fs/ubifs/debug.h
@@ -25,7 +25,56 @@
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
 
-#define UBIFS_DBG(op) op
+/**
+ * ubifs_debug_info - per-FS debugging information.
+ * @buf: a buffer of LEB size, used for various purposes
+ * @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
+ * @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
+ * @chk_lpt_lebs: used by LPT tree size checker
+ * @new_nhead_offs: used by LPT tree size checker
+ * @new_ihead_lnum: used by debugging to check ihead_lnum
+ * @new_ihead_offs: used by debugging to check ihead_offs
+ *
+ * debugfs_dir_name: name of debugfs directory containing this file-system's
+ *                   files
+ * debugfs_dir: direntry object of the file-system debugfs directory
+ * dump_lprops: "dump lprops" debugfs knob
+ * dump_budg: "dump budgeting information" debugfs knob
+ * dump_tnc: "dump TNC" debugfs knob
+ */
+struct ubifs_debug_info {
+	void *buf;
+	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;
+	long long chk_lpt_sz;
+	long long chk_lpt_sz2;
+	long long chk_lpt_wastage;
+	int chk_lpt_lebs;
+	int new_nhead_offs;
+	int new_ihead_lnum;
+	int new_ihead_offs;
+
+	char debugfs_dir_name[100];
+	struct dentry *debugfs_dir;
+	struct dentry *dump_lprops;
+	struct dentry *dump_budg;
+	struct dentry *dump_tnc;
+};
 
 #define ubifs_assert(expr) do {                                                \
 	if (unlikely(!(expr))) {                                               \
@@ -211,14 +260,18 @@ extern unsigned int ubifs_msg_flags;
 extern unsigned int ubifs_chk_flags;
 extern unsigned int ubifs_tst_flags;
 
-/* Dump functions */
+int ubifs_debugging_init(struct ubifs_info *c);
+void ubifs_debugging_exit(struct ubifs_info *c);
 
+/* Dump functions */
 const char *dbg_ntype(int type);
 const char *dbg_cstate(int cmt_state);
 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_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);
 void dbg_dump_budget_req(const struct ubifs_budget_req *req);
 void dbg_dump_lstats(const struct ubifs_lp_stats *lst);
 void dbg_dump_budg(struct ubifs_info *c);
@@ -233,9 +286,9 @@ void dbg_dump_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
 		    struct ubifs_nnode *parent, int iip);
 void dbg_dump_tnc(struct ubifs_info *c);
 void dbg_dump_index(struct ubifs_info *c);
+void dbg_dump_lpt_lebs(const struct ubifs_info *c);
 
 /* Checking helper functions */
-
 typedef int (*dbg_leaf_callback)(struct ubifs_info *c,
 				 struct ubifs_zbranch *zbr, void *priv);
 typedef int (*dbg_znode_callback)(struct ubifs_info *c,
@@ -274,9 +327,6 @@ int dbg_force_in_the_gaps(void);
 
 #define dbg_failure_mode (ubifs_tst_flags & UBIFS_TST_RCVRY)
 
-void dbg_failure_mode_registration(struct ubifs_info *c);
-void dbg_failure_mode_deregistration(struct ubifs_info *c);
-
 #ifndef UBIFS_DBG_PRESERVE_UBI
 
 #define ubi_leb_read   dbg_leb_read
@@ -318,9 +368,13 @@ static inline int dbg_change(struct ubi_volume_desc *desc, int lnum,
 	return dbg_leb_change(desc, lnum, buf, len, UBI_UNKNOWN);
 }
 
-#else /* !CONFIG_UBIFS_FS_DEBUG */
+/* Debugfs-related stuff */
+int dbg_debugfs_init(void);
+void dbg_debugfs_exit(void);
+int dbg_debugfs_init_fs(struct ubifs_info *c);
+void dbg_debugfs_exit_fs(struct ubifs_info *c);
 
-#define UBIFS_DBG(op)
+#else /* !CONFIG_UBIFS_FS_DEBUG */
 
 /* Use "if (0)" to make compiler check arguments even if debugging is off */
 #define ubifs_assert(expr)  do {                                               \
@@ -360,23 +414,28 @@ static inline int dbg_change(struct ubi_volume_desc *desc, int lnum,
 #define DBGKEY(key)  ((char *)(key))
 #define DBGKEY1(key) ((char *)(key))
 
-#define dbg_ntype(type)                       ""
-#define dbg_cstate(cmt_state)                 ""
-#define dbg_get_key_dump(c, key)              ({})
-#define dbg_dump_inode(c, inode)              ({})
-#define dbg_dump_node(c, node)                ({})
-#define dbg_dump_budget_req(req)              ({})
-#define dbg_dump_lstats(lst)                  ({})
-#define dbg_dump_budg(c)                      ({})
-#define dbg_dump_lprop(c, lp)                 ({})
-#define dbg_dump_lprops(c)                    ({})
-#define dbg_dump_lpt_info(c)                  ({})
-#define dbg_dump_leb(c, lnum)                 ({})
-#define dbg_dump_znode(c, znode)              ({})
-#define dbg_dump_heap(c, heap, cat)           ({})
-#define dbg_dump_pnode(c, pnode, parent, iip) ({})
-#define dbg_dump_tnc(c)                       ({})
-#define dbg_dump_index(c)                     ({})
+#define ubifs_debugging_init(c)                0
+#define ubifs_debugging_exit(c)                ({})
+
+#define dbg_ntype(type)                        ""
+#define dbg_cstate(cmt_state)                  ""
+#define dbg_get_key_dump(c, key)               ({})
+#define dbg_dump_inode(c, inode)               ({})
+#define dbg_dump_node(c, node)                 ({})
+#define dbg_dump_lpt_node(c, node, lnum, offs) ({})
+#define dbg_dump_budget_req(req)               ({})
+#define dbg_dump_lstats(lst)                   ({})
+#define dbg_dump_budg(c)                       ({})
+#define dbg_dump_lprop(c, lp)                  ({})
+#define dbg_dump_lprops(c)                     ({})
+#define dbg_dump_lpt_info(c)                   ({})
+#define dbg_dump_leb(c, lnum)                  ({})
+#define dbg_dump_znode(c, znode)               ({})
+#define dbg_dump_heap(c, heap, cat)            ({})
+#define dbg_dump_pnode(c, pnode, parent, iip)  ({})
+#define dbg_dump_tnc(c)                        ({})
+#define dbg_dump_index(c)                      ({})
+#define dbg_dump_lpt_lebs(c)                   ({})
 
 #define dbg_walk_index(c, leaf_cb, znode_cb, priv) 0
 #define dbg_old_index_check_init(c, zroot)         0
@@ -396,9 +455,11 @@ static inline int dbg_change(struct ubi_volume_desc *desc, int lnum,
 #define dbg_force_in_the_gaps_enabled              0
 #define dbg_force_in_the_gaps()                    0
 #define dbg_failure_mode                           0
-#define dbg_failure_mode_registration(c)           ({})
-#define dbg_failure_mode_deregistration(c)         ({})
 
-#endif /* !CONFIG_UBIFS_FS_DEBUG */
+#define dbg_debugfs_init()                         0
+#define dbg_debugfs_exit()
+#define dbg_debugfs_init_fs(c)                     0
+#define dbg_debugfs_exit_fs(c)                     0
 
+#endif /* !CONFIG_UBIFS_FS_DEBUG */
 #endif /* !__UBIFS_DEBUG_H__ */
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 2624411d9758..7f1de98e6091 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -254,7 +254,7 @@ static int write_begin_slow(struct address_space *mapping,
 	}
 
 	if (!PageUptodate(page)) {
-		if (!(pos & PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
+		if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
 			SetPageChecked(page);
 		else {
 			err = do_readpage(page);
@@ -444,7 +444,7 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 
 	if (!PageUptodate(page)) {
 		/* The page is not loaded from the flash */
-		if (!(pos & PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
+		if (!(pos & ~PAGE_CACHE_MASK) && len == PAGE_CACHE_SIZE)
 			/*
 			 * We change whole page so no need to load it. But we
 			 * have to set the @PG_checked flag to make the further
diff --git a/fs/ubifs/key.h b/fs/ubifs/key.h
index 3f1f16bc25c9..efb3430a2581 100644
--- a/fs/ubifs/key.h
+++ b/fs/ubifs/key.h
@@ -38,6 +38,22 @@
 #define __UBIFS_KEY_H__
 
 /**
+ * key_mask_hash - mask a valid hash value.
+ * @val: value to be masked
+ *
+ * We use hash values as offset in directories, so values %0 and %1 are
+ * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
+ * function makes sure the reserved values are not used.
+ */
+static inline uint32_t key_mask_hash(uint32_t hash)
+{
+	hash &= UBIFS_S_KEY_HASH_MASK;
+	if (unlikely(hash <= 2))
+		hash += 3;
+	return hash;
+}
+
+/**
  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  * @s: direntry name
  * @len: name length
@@ -54,16 +70,7 @@ static inline uint32_t key_r5_hash(const char *s, int len)
 		str++;
 	}
 
-	a &= UBIFS_S_KEY_HASH_MASK;
-
-	/*
-	 * We use hash values as offset in directories, so values %0 and %1 are
-	 * reserved for "." and "..". %2 is reserved for "end of readdir"
-	 * marker.
-	 */
-	if (unlikely(a >= 0 && a <= 2))
-		a += 3;
-	return a;
+	return key_mask_hash(a);
 }
 
 /**
@@ -77,10 +84,7 @@ static inline uint32_t key_test_hash(const char *str, int len)
 
 	len = min_t(uint32_t, len, 4);
 	memcpy(&a, str, len);
-	a &= UBIFS_S_KEY_HASH_MASK;
-	if (unlikely(a >= 0 && a <= 2))
-		a += 3;
-	return a;
+	return key_mask_hash(a);
 }
 
 /**
diff --git a/fs/ubifs/lprops.c b/fs/ubifs/lprops.c
index f27176e9b70d..dfd2bcece27a 100644
--- a/fs/ubifs/lprops.c
+++ b/fs/ubifs/lprops.c
@@ -520,13 +520,13 @@ static int is_lprops_dirty(struct ubifs_info *c, struct ubifs_lprops *lprops)
  * @flags: new flags
  * @idx_gc_cnt: change to the count of idx_gc list
  *
- * This function changes LEB properties. This function does not change a LEB
- * property (@free, @dirty or @flag) if the value passed is %LPROPS_NC.
+ * This function changes LEB properties (@free, @dirty or @flag). However, the
+ * property which has the %LPROPS_NC value is not changed. Returns a pointer to
+ * the updated LEB properties on success and a negative error code on failure.
  *
- * This function returns a pointer to the updated LEB properties on success
- * and a negative error code on failure. N.B. the LEB properties may have had to
- * be copied (due to COW) and consequently the pointer returned may not be the
- * same as the pointer passed.
+ * Note, the LEB properties may have had to be copied (due to COW) and
+ * consequently the pointer returned may not be the same as the pointer
+ * passed.
  */
 const struct ubifs_lprops *ubifs_change_lp(struct ubifs_info *c,
 					   const struct ubifs_lprops *lp,
@@ -1088,7 +1088,7 @@ static int scan_check_cb(struct ubifs_info *c,
 		}
 	}
 
-	sleb = ubifs_scan(c, lnum, 0, c->dbg_buf);
+	sleb = ubifs_scan(c, lnum, 0, c->dbg->buf);
 	if (IS_ERR(sleb)) {
 		/*
 		 * After an unclean unmount, empty and freeable LEBs
diff --git a/fs/ubifs/lpt.c b/fs/ubifs/lpt.c
index db8bd0e518b2..b2792e84d245 100644
--- a/fs/ubifs/lpt.c
+++ b/fs/ubifs/lpt.c
@@ -36,15 +36,16 @@
  * can be written into a single eraseblock. In that case, garbage collection
  * consists of just writing the whole table, which therefore makes all other
  * eraseblocks reusable. In the case of the big model, dirty eraseblocks are
- * selected for garbage collection, which consists are marking the nodes in
+ * selected for garbage collection, which consists of marking the clean nodes in
  * that LEB as dirty, and then only the dirty nodes are written out. Also, in
  * the case of the big model, a table of LEB numbers is saved so that the entire
  * LPT does not to be scanned looking for empty eraseblocks when UBIFS is first
  * mounted.
  */
 
-#include <linux/crc16.h>
 #include "ubifs.h"
+#include <linux/crc16.h>
+#include <linux/math64.h>
 
 /**
  * do_calc_lpt_geom - calculate sizes for the LPT area.
@@ -135,15 +136,13 @@ static void do_calc_lpt_geom(struct ubifs_info *c)
 int ubifs_calc_lpt_geom(struct ubifs_info *c)
 {
 	int lebs_needed;
-	uint64_t sz;
+	long long sz;
 
 	do_calc_lpt_geom(c);
 
 	/* Verify that lpt_lebs is big enough */
 	sz = c->lpt_sz * 2; /* Must have at least 2 times the size */
-	sz += c->leb_size - 1;
-	do_div(sz, c->leb_size);
-	lebs_needed = sz;
+	lebs_needed = div_u64(sz + c->leb_size - 1, c->leb_size);
 	if (lebs_needed > c->lpt_lebs) {
 		ubifs_err("too few LPT LEBs");
 		return -EINVAL;
@@ -156,7 +155,6 @@ int ubifs_calc_lpt_geom(struct ubifs_info *c)
 	}
 
 	c->check_lpt_free = c->big_lpt;
-
 	return 0;
 }
 
@@ -176,7 +174,7 @@ static int calc_dflt_lpt_geom(struct ubifs_info *c, int *main_lebs,
 			      int *big_lpt)
 {
 	int i, lebs_needed;
-	uint64_t sz;
+	long long sz;
 
 	/* Start by assuming the minimum number of LPT LEBs */
 	c->lpt_lebs = UBIFS_MIN_LPT_LEBS;
@@ -203,9 +201,7 @@ static int calc_dflt_lpt_geom(struct ubifs_info *c, int *main_lebs,
 	/* Now check there are enough LPT LEBs */
 	for (i = 0; i < 64 ; i++) {
 		sz = c->lpt_sz * 4; /* Allow 4 times the size */
-		sz += c->leb_size - 1;
-		do_div(sz, c->leb_size);
-		lebs_needed = sz;
+		lebs_needed = div_u64(sz + c->leb_size - 1, c->leb_size);
 		if (lebs_needed > c->lpt_lebs) {
 			/* Not enough LPT LEBs so try again with more */
 			c->lpt_lebs = lebs_needed;
@@ -558,7 +554,7 @@ static int calc_nnode_num(int row, int col)
  * This function calculates and returns the nnode number based on the parent's
  * nnode number and the index in parent.
  */
-static int calc_nnode_num_from_parent(struct ubifs_info *c,
+static int calc_nnode_num_from_parent(const struct ubifs_info *c,
 				      struct ubifs_nnode *parent, int iip)
 {
 	int num, shft;
@@ -583,7 +579,7 @@ static int calc_nnode_num_from_parent(struct ubifs_info *c,
  * This function calculates and returns the pnode number based on the parent's
  * nnode number and the index in parent.
  */
-static int calc_pnode_num_from_parent(struct ubifs_info *c,
+static int calc_pnode_num_from_parent(const struct ubifs_info *c,
 				      struct ubifs_nnode *parent, int iip)
 {
 	int i, n = c->lpt_hght - 1, pnum = parent->num, num = 0;
@@ -966,7 +962,7 @@ static int check_lpt_type(uint8_t **addr, int *pos, int type)
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int unpack_pnode(struct ubifs_info *c, void *buf,
+static int unpack_pnode(const struct ubifs_info *c, void *buf,
 			struct ubifs_pnode *pnode)
 {
 	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
@@ -996,15 +992,15 @@ static int unpack_pnode(struct ubifs_info *c, void *buf,
 }
 
 /**
- * unpack_nnode - unpack a nnode.
+ * ubifs_unpack_nnode - unpack a nnode.
  * @c: UBIFS file-system description object
  * @buf: buffer containing packed nnode to unpack
  * @nnode: nnode structure to fill
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int unpack_nnode(struct ubifs_info *c, void *buf,
-			struct ubifs_nnode *nnode)
+int ubifs_unpack_nnode(const struct ubifs_info *c, void *buf,
+		       struct ubifs_nnode *nnode)
 {
 	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
 	int i, pos = 0, err;
@@ -1036,7 +1032,7 @@ static int unpack_nnode(struct ubifs_info *c, void *buf,
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int unpack_ltab(struct ubifs_info *c, void *buf)
+static int unpack_ltab(const struct ubifs_info *c, void *buf)
 {
 	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
 	int i, pos = 0, err;
@@ -1068,7 +1064,7 @@ static int unpack_ltab(struct ubifs_info *c, void *buf)
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int unpack_lsave(struct ubifs_info *c, void *buf)
+static int unpack_lsave(const struct ubifs_info *c, void *buf)
 {
 	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
 	int i, pos = 0, err;
@@ -1096,7 +1092,7 @@ static int unpack_lsave(struct ubifs_info *c, void *buf)
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int validate_nnode(struct ubifs_info *c, struct ubifs_nnode *nnode,
+static int validate_nnode(const struct ubifs_info *c, struct ubifs_nnode *nnode,
 			  struct ubifs_nnode *parent, int iip)
 {
 	int i, lvl, max_offs;
@@ -1140,7 +1136,7 @@ static int validate_nnode(struct ubifs_info *c, struct ubifs_nnode *nnode,
  *
  * This function returns %0 on success and a negative error code on failure.
  */
-static int validate_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
+static int validate_pnode(const struct ubifs_info *c, struct ubifs_pnode *pnode,
 			  struct ubifs_nnode *parent, int iip)
 {
 	int i;
@@ -1174,7 +1170,8 @@ static int validate_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
  * This function calculates the LEB numbers for the LEB properties it contains
  * based on the pnode number.
  */
-static void set_pnode_lnum(struct ubifs_info *c, struct ubifs_pnode *pnode)
+static void set_pnode_lnum(const struct ubifs_info *c,
+			   struct ubifs_pnode *pnode)
 {
 	int i, lnum;
 
@@ -1227,7 +1224,7 @@ int ubifs_read_nnode(struct ubifs_info *c, struct ubifs_nnode *parent, int iip)
 		err = ubi_read(c->ubi, lnum, buf, offs, c->nnode_sz);
 		if (err)
 			goto out;
-		err = unpack_nnode(c, buf, nnode);
+		err = ubifs_unpack_nnode(c, buf, nnode);
 		if (err)
 			goto out;
 	}
@@ -1816,7 +1813,7 @@ static struct ubifs_nnode *scan_get_nnode(struct ubifs_info *c,
 			       c->nnode_sz);
 		if (err)
 			return ERR_PTR(err);
-		err = unpack_nnode(c, buf, nnode);
+		err = ubifs_unpack_nnode(c, buf, nnode);
 		if (err)
 			return ERR_PTR(err);
 	}
diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
index a41434b42785..da60b5a0fab9 100644
--- a/fs/ubifs/lpt_commit.c
+++ b/fs/ubifs/lpt_commit.c
@@ -320,6 +320,8 @@ no_space:
 	dbg_err("LPT out of space at LEB %d:%d needing %d, done_ltab %d, "
 		"done_lsave %d", lnum, offs, len, done_ltab, done_lsave);
 	dbg_dump_lpt_info(c);
+	dbg_dump_lpt_lebs(c);
+	dump_stack();
 	return err;
 }
 
@@ -548,6 +550,8 @@ no_space:
 	dbg_err("LPT out of space mismatch at LEB %d:%d needing %d, done_ltab "
 	        "%d, done_lsave %d", lnum, offs, len, done_ltab, done_lsave);
 	dbg_dump_lpt_info(c);
+	dbg_dump_lpt_lebs(c);
+	dump_stack();
 	return err;
 }
 
@@ -1025,7 +1029,7 @@ static int make_node_dirty(struct ubifs_info *c, int node_type, int node_num,
  * @c: UBIFS file-system description object
  * @node_type: LPT node type
  */
-static int get_lpt_node_len(struct ubifs_info *c, int node_type)
+static int get_lpt_node_len(const struct ubifs_info *c, int node_type)
 {
 	switch (node_type) {
 	case UBIFS_LPT_NNODE:
@@ -1046,7 +1050,7 @@ static int get_lpt_node_len(struct ubifs_info *c, int node_type)
  * @buf: buffer
  * @len: length of buffer
  */
-static int get_pad_len(struct ubifs_info *c, uint8_t *buf, int len)
+static int get_pad_len(const struct ubifs_info *c, uint8_t *buf, int len)
 {
 	int offs, pad_len;
 
@@ -1063,7 +1067,8 @@ static int get_pad_len(struct ubifs_info *c, uint8_t *buf, int len)
  * @buf: buffer
  * @node_num: node number is returned here
  */
-static int get_lpt_node_type(struct ubifs_info *c, uint8_t *buf, int *node_num)
+static int get_lpt_node_type(const struct ubifs_info *c, uint8_t *buf,
+			     int *node_num)
 {
 	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
 	int pos = 0, node_type;
@@ -1081,7 +1086,7 @@ static int get_lpt_node_type(struct ubifs_info *c, uint8_t *buf, int *node_num)
  *
  * This function returns %1 if the buffer contains a node or %0 if it does not.
  */
-static int is_a_node(struct ubifs_info *c, uint8_t *buf, int len)
+static int is_a_node(const struct ubifs_info *c, uint8_t *buf, int len)
 {
 	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
 	int pos = 0, node_type, node_len;
@@ -1105,7 +1110,6 @@ static int is_a_node(struct ubifs_info *c, uint8_t *buf, int len)
 	return 1;
 }
 
-
 /**
  * lpt_gc_lnum - garbage collect a LPT LEB.
  * @c: UBIFS file-system description object
@@ -1602,7 +1606,10 @@ static int dbg_check_ltab_lnum(struct ubifs_info *c, int lnum)
 {
 	int err, len = c->leb_size, dirty = 0, node_type, node_num, node_len;
 	int ret;
-	void *buf = c->dbg_buf;
+	void *buf = c->dbg->buf;
+
+	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+		return 0;
 
 	dbg_lp("LEB %d", lnum);
 	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
@@ -1704,6 +1711,9 @@ int dbg_chk_lpt_free_spc(struct ubifs_info *c)
 	long long free = 0;
 	int i;
 
+	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+		return 0;
+
 	for (i = 0; i < c->lpt_lebs; i++) {
 		if (c->ltab[i].tgc || c->ltab[i].cmt)
 			continue;
@@ -1716,6 +1726,8 @@ int dbg_chk_lpt_free_spc(struct ubifs_info *c)
 		dbg_err("LPT space error: free %lld lpt_sz %lld",
 			free, c->lpt_sz);
 		dbg_dump_lpt_info(c);
+		dbg_dump_lpt_lebs(c);
+		dump_stack();
 		return -EINVAL;
 	}
 	return 0;
@@ -1731,15 +1743,19 @@ int dbg_chk_lpt_free_spc(struct ubifs_info *c)
  */
 int dbg_chk_lpt_sz(struct ubifs_info *c, int action, int len)
 {
+	struct ubifs_debug_info *d = c->dbg;
 	long long chk_lpt_sz, lpt_sz;
 	int err = 0;
 
+	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+		return 0;
+
 	switch (action) {
 	case 0:
-		c->chk_lpt_sz = 0;
-		c->chk_lpt_sz2 = 0;
-		c->chk_lpt_lebs = 0;
-		c->chk_lpt_wastage = 0;
+		d->chk_lpt_sz = 0;
+		d->chk_lpt_sz2 = 0;
+		d->chk_lpt_lebs = 0;
+		d->chk_lpt_wastage = 0;
 		if (c->dirty_pn_cnt > c->pnode_cnt) {
 			dbg_err("dirty pnodes %d exceed max %d",
 				c->dirty_pn_cnt, c->pnode_cnt);
@@ -1752,35 +1768,35 @@ int dbg_chk_lpt_sz(struct ubifs_info *c, int action, int len)
 		}
 		return err;
 	case 1:
-		c->chk_lpt_sz += len;
+		d->chk_lpt_sz += len;
 		return 0;
 	case 2:
-		c->chk_lpt_sz += len;
-		c->chk_lpt_wastage += len;
-		c->chk_lpt_lebs += 1;
+		d->chk_lpt_sz += len;
+		d->chk_lpt_wastage += len;
+		d->chk_lpt_lebs += 1;
 		return 0;
 	case 3:
 		chk_lpt_sz = c->leb_size;
-		chk_lpt_sz *= c->chk_lpt_lebs;
+		chk_lpt_sz *= d->chk_lpt_lebs;
 		chk_lpt_sz += len - c->nhead_offs;
-		if (c->chk_lpt_sz != chk_lpt_sz) {
+		if (d->chk_lpt_sz != chk_lpt_sz) {
 			dbg_err("LPT wrote %lld but space used was %lld",
-				c->chk_lpt_sz, chk_lpt_sz);
+				d->chk_lpt_sz, chk_lpt_sz);
 			err = -EINVAL;
 		}
-		if (c->chk_lpt_sz > c->lpt_sz) {
+		if (d->chk_lpt_sz > c->lpt_sz) {
 			dbg_err("LPT wrote %lld but lpt_sz is %lld",
-				c->chk_lpt_sz, c->lpt_sz);
+				d->chk_lpt_sz, c->lpt_sz);
 			err = -EINVAL;
 		}
-		if (c->chk_lpt_sz2 && c->chk_lpt_sz != c->chk_lpt_sz2) {
+		if (d->chk_lpt_sz2 && d->chk_lpt_sz != d->chk_lpt_sz2) {
 			dbg_err("LPT layout size %lld but wrote %lld",
-				c->chk_lpt_sz, c->chk_lpt_sz2);
+				d->chk_lpt_sz, d->chk_lpt_sz2);
 			err = -EINVAL;
 		}
-		if (c->chk_lpt_sz2 && c->new_nhead_offs != len) {
+		if (d->chk_lpt_sz2 && d->new_nhead_offs != len) {
 			dbg_err("LPT new nhead offs: expected %d was %d",
-				c->new_nhead_offs, len);
+				d->new_nhead_offs, len);
 			err = -EINVAL;
 		}
 		lpt_sz = (long long)c->pnode_cnt * c->pnode_sz;
@@ -1788,26 +1804,146 @@ int dbg_chk_lpt_sz(struct ubifs_info *c, int action, int len)
 		lpt_sz += c->ltab_sz;
 		if (c->big_lpt)
 			lpt_sz += c->lsave_sz;
-		if (c->chk_lpt_sz - c->chk_lpt_wastage > lpt_sz) {
+		if (d->chk_lpt_sz - d->chk_lpt_wastage > lpt_sz) {
 			dbg_err("LPT chk_lpt_sz %lld + waste %lld exceeds %lld",
-				c->chk_lpt_sz, c->chk_lpt_wastage, lpt_sz);
+				d->chk_lpt_sz, d->chk_lpt_wastage, lpt_sz);
 			err = -EINVAL;
 		}
-		if (err)
+		if (err) {
 			dbg_dump_lpt_info(c);
-		c->chk_lpt_sz2 = c->chk_lpt_sz;
-		c->chk_lpt_sz = 0;
-		c->chk_lpt_wastage = 0;
-		c->chk_lpt_lebs = 0;
-		c->new_nhead_offs = len;
+			dbg_dump_lpt_lebs(c);
+			dump_stack();
+		}
+		d->chk_lpt_sz2 = d->chk_lpt_sz;
+		d->chk_lpt_sz = 0;
+		d->chk_lpt_wastage = 0;
+		d->chk_lpt_lebs = 0;
+		d->new_nhead_offs = len;
 		return err;
 	case 4:
-		c->chk_lpt_sz += len;
-		c->chk_lpt_wastage += len;
+		d->chk_lpt_sz += len;
+		d->chk_lpt_wastage += len;
 		return 0;
 	default:
 		return -EINVAL;
 	}
 }
 
+/**
+ * dbg_dump_lpt_leb - dump an LPT LEB.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number to dump
+ *
+ * This function dumps an LEB from LPT area. Nodes in this area are very
+ * different to nodes in the main area (e.g., they do not have common headers,
+ * they do not have 8-byte alignments, etc), so we have a separate function to
+ * dump LPT area LEBs. Note, LPT has to be locked by the coller.
+ */
+static void dump_lpt_leb(const struct ubifs_info *c, int lnum)
+{
+	int err, len = c->leb_size, node_type, node_num, node_len, offs;
+	void *buf = c->dbg->buf;
+
+	printk(KERN_DEBUG "(pid %d) start dumping LEB %d\n",
+	       current->pid, lnum);
+	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
+	if (err) {
+		ubifs_err("cannot read LEB %d, error %d", lnum, err);
+		return;
+	}
+	while (1) {
+		offs = c->leb_size - len;
+		if (!is_a_node(c, buf, len)) {
+			int pad_len;
+
+			pad_len = get_pad_len(c, buf, len);
+			if (pad_len) {
+				printk(KERN_DEBUG "LEB %d:%d, pad %d bytes\n",
+				       lnum, offs, pad_len);
+				buf += pad_len;
+				len -= pad_len;
+				continue;
+			}
+			if (len)
+				printk(KERN_DEBUG "LEB %d:%d, free %d bytes\n",
+				       lnum, offs, len);
+			break;
+		}
+
+		node_type = get_lpt_node_type(c, buf, &node_num);
+		switch (node_type) {
+		case UBIFS_LPT_PNODE:
+		{
+			node_len = c->pnode_sz;
+			if (c->big_lpt)
+				printk(KERN_DEBUG "LEB %d:%d, pnode num %d\n",
+				       lnum, offs, node_num);
+			else
+				printk(KERN_DEBUG "LEB %d:%d, pnode\n",
+				       lnum, offs);
+			break;
+		}
+		case UBIFS_LPT_NNODE:
+		{
+			int i;
+			struct ubifs_nnode nnode;
+
+			node_len = c->nnode_sz;
+			if (c->big_lpt)
+				printk(KERN_DEBUG "LEB %d:%d, nnode num %d, ",
+				       lnum, offs, node_num);
+			else
+				printk(KERN_DEBUG "LEB %d:%d, nnode, ",
+				       lnum, offs);
+			err = ubifs_unpack_nnode(c, buf, &nnode);
+			for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
+				printk("%d:%d", nnode.nbranch[i].lnum,
+				       nnode.nbranch[i].offs);
+				if (i != UBIFS_LPT_FANOUT - 1)
+					printk(", ");
+			}
+			printk("\n");
+			break;
+		}
+		case UBIFS_LPT_LTAB:
+			node_len = c->ltab_sz;
+			printk(KERN_DEBUG "LEB %d:%d, ltab\n",
+			       lnum, offs);
+			break;
+		case UBIFS_LPT_LSAVE:
+			node_len = c->lsave_sz;
+			printk(KERN_DEBUG "LEB %d:%d, lsave len\n", lnum, offs);
+			break;
+		default:
+			ubifs_err("LPT node type %d not recognized", node_type);
+			return;
+		}
+
+		buf += node_len;
+		len -= node_len;
+	}
+
+	printk(KERN_DEBUG "(pid %d) finish dumping LEB %d\n",
+	       current->pid, lnum);
+}
+
+/**
+ * dbg_dump_lpt_lebs - dump LPT lebs.
+ * @c: UBIFS file-system description object
+ *
+ * This function dumps all LPT LEBs. The caller has to make sure the LPT is
+ * locked.
+ */
+void dbg_dump_lpt_lebs(const struct ubifs_info *c)
+{
+	int i;
+
+	printk(KERN_DEBUG "(pid %d) start dumping all LPT LEBs\n",
+	       current->pid);
+	for (i = 0; i < c->lpt_lebs; i++)
+		dump_lpt_leb(c, i + c->lpt_first);
+	printk(KERN_DEBUG "(pid %d) finish dumping all LPT LEBs\n",
+	       current->pid);
+}
+
 #endif /* CONFIG_UBIFS_FS_DEBUG */
diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
index 9bd5a43d4526..9e6f403f170e 100644
--- a/fs/ubifs/orphan.c
+++ b/fs/ubifs/orphan.c
@@ -899,7 +899,7 @@ static int dbg_scan_orphans(struct ubifs_info *c, struct check_info *ci)
 	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
 		struct ubifs_scan_leb *sleb;
 
-		sleb = ubifs_scan(c, lnum, 0, c->dbg_buf);
+		sleb = ubifs_scan(c, lnum, 0, c->dbg->buf);
 		if (IS_ERR(sleb)) {
 			err = PTR_ERR(sleb);
 			break;
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 0f392351dc5a..e070c643d1bb 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -28,6 +28,7 @@
 
 #include "ubifs.h"
 #include <linux/random.h>
+#include <linux/math64.h>
 
 /*
  * Default journal size in logical eraseblocks as a percent of total
@@ -80,7 +81,7 @@ static int create_default_filesystem(struct ubifs_info *c)
 	int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
 	int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
 	int min_leb_cnt = UBIFS_MIN_LEB_CNT;
-	uint64_t tmp64, main_bytes;
+	long long tmp64, main_bytes;
 	__le64 tmp_le64;
 
 	/* Some functions called from here depend on the @c->key_len filed */
@@ -160,7 +161,7 @@ static int create_default_filesystem(struct ubifs_info *c)
 	if (!sup)
 		return -ENOMEM;
 
-	tmp64 = (uint64_t)max_buds * c->leb_size;
+	tmp64 = (long long)max_buds * c->leb_size;
 	if (big_lpt)
 		sup_flags |= UBIFS_FLG_BIGLPT;
 
@@ -179,14 +180,16 @@ static int create_default_filesystem(struct ubifs_info *c)
 	sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
 	sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
 	sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
-	sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
 	sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
+	if (c->mount_opts.override_compr)
+		sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
+	else
+		sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
 
 	generate_random_uuid(sup->uuid);
 
-	main_bytes = (uint64_t)main_lebs * c->leb_size;
-	tmp64 = main_bytes * DEFAULT_RP_PERCENT;
-	do_div(tmp64, 100);
+	main_bytes = (long long)main_lebs * c->leb_size;
+	tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
 	if (tmp64 > DEFAULT_MAX_RP_SIZE)
 		tmp64 = DEFAULT_MAX_RP_SIZE;
 	sup->rp_size = cpu_to_le64(tmp64);
@@ -582,16 +585,15 @@ int ubifs_read_superblock(struct ubifs_info *c)
 	c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
 	c->fanout        = le32_to_cpu(sup->fanout);
 	c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
-	c->default_compr = le16_to_cpu(sup->default_compr);
 	c->rp_size       = le64_to_cpu(sup->rp_size);
 	c->rp_uid        = le32_to_cpu(sup->rp_uid);
 	c->rp_gid        = le32_to_cpu(sup->rp_gid);
 	sup_flags        = le32_to_cpu(sup->flags);
+	if (!c->mount_opts.override_compr)
+		c->default_compr = le16_to_cpu(sup->default_compr);
 
 	c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
-
 	memcpy(&c->uuid, &sup->uuid, 16);
-
 	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
 
 	/* Automatically increase file system size to the maximum size */
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index d80b2aef42b6..c3cefc841374 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -34,6 +34,7 @@
 #include <linux/parser.h>
 #include <linux/seq_file.h>
 #include <linux/mount.h>
+#include <linux/math64.h>
 #include "ubifs.h"
 
 /*
@@ -417,6 +418,11 @@ static int ubifs_show_options(struct seq_file *s, struct vfsmount *mnt)
 	else if (c->mount_opts.chk_data_crc == 1)
 		seq_printf(s, ",no_chk_data_crc");
 
+	if (c->mount_opts.override_compr) {
+		seq_printf(s, ",compr=");
+		seq_printf(s, ubifs_compr_name(c->mount_opts.compr_type));
+	}
+
 	return 0;
 }
 
@@ -607,7 +613,7 @@ static int bud_wbuf_callback(struct ubifs_info *c, int lnum, int free, int pad)
 static int init_constants_late(struct ubifs_info *c)
 {
 	int tmp, err;
-	uint64_t tmp64;
+	long long tmp64;
 
 	c->main_bytes = (long long)c->main_lebs * c->leb_size;
 	c->max_znode_sz = sizeof(struct ubifs_znode) +
@@ -634,9 +640,8 @@ static int init_constants_late(struct ubifs_info *c)
 	 * Make sure that the log is large enough to fit reference nodes for
 	 * all buds plus one reserved LEB.
 	 */
-	tmp64 = c->max_bud_bytes;
-	tmp = do_div(tmp64, c->leb_size);
-	c->max_bud_cnt = tmp64 + !!tmp;
+	tmp64 = c->max_bud_bytes + c->leb_size - 1;
+	c->max_bud_cnt = div_u64(tmp64, c->leb_size);
 	tmp = (c->ref_node_alsz * c->max_bud_cnt + c->leb_size - 1);
 	tmp /= c->leb_size;
 	tmp += 1;
@@ -672,7 +677,7 @@ static int init_constants_late(struct ubifs_info *c)
 	 * Consequently, if the journal is too small, UBIFS will treat it as
 	 * always full.
 	 */
-	tmp64 = (uint64_t)(c->jhead_cnt + 1) * c->leb_size + 1;
+	tmp64 = (long long)(c->jhead_cnt + 1) * c->leb_size + 1;
 	if (c->bg_bud_bytes < tmp64)
 		c->bg_bud_bytes = tmp64;
 	if (c->max_bud_bytes < tmp64 + c->leb_size)
@@ -690,10 +695,11 @@ static int init_constants_late(struct ubifs_info *c)
 	 * necessary to report something for the 'statfs()' call.
 	 *
 	 * Subtract the LEB reserved for GC, the LEB which is reserved for
-	 * deletions, and assume only one journal head is available.
+	 * deletions, minimum LEBs for the index, and assume only one journal
+	 * head is available.
 	 */
-	tmp64 = c->main_lebs - 2 - c->jhead_cnt + 1;
-	tmp64 *= (uint64_t)c->leb_size - c->leb_overhead;
+	tmp64 = c->main_lebs - 1 - 1 - MIN_INDEX_LEBS - c->jhead_cnt + 1;
+	tmp64 *= (long long)c->leb_size - c->leb_overhead;
 	tmp64 = ubifs_reported_space(c, tmp64);
 	c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;
 
@@ -878,6 +884,7 @@ static int check_volume_empty(struct ubifs_info *c)
  * Opt_no_bulk_read: disable bulk-reads
  * Opt_chk_data_crc: check CRCs when reading data nodes
  * Opt_no_chk_data_crc: do not check CRCs when reading data nodes
+ * Opt_override_compr: override default compressor
  * Opt_err: just end of array marker
  */
 enum {
@@ -887,6 +894,7 @@ enum {
 	Opt_no_bulk_read,
 	Opt_chk_data_crc,
 	Opt_no_chk_data_crc,
+	Opt_override_compr,
 	Opt_err,
 };
 
@@ -897,6 +905,7 @@ static const match_table_t tokens = {
 	{Opt_no_bulk_read, "no_bulk_read"},
 	{Opt_chk_data_crc, "chk_data_crc"},
 	{Opt_no_chk_data_crc, "no_chk_data_crc"},
+	{Opt_override_compr, "compr=%s"},
 	{Opt_err, NULL},
 };
 
@@ -950,6 +959,28 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 			c->mount_opts.chk_data_crc = 1;
 			c->no_chk_data_crc = 1;
 			break;
+		case Opt_override_compr:
+		{
+			char *name = match_strdup(&args[0]);
+
+			if (!name)
+				return -ENOMEM;
+			if (!strcmp(name, "none"))
+				c->mount_opts.compr_type = UBIFS_COMPR_NONE;
+			else if (!strcmp(name, "lzo"))
+				c->mount_opts.compr_type = UBIFS_COMPR_LZO;
+			else if (!strcmp(name, "zlib"))
+				c->mount_opts.compr_type = UBIFS_COMPR_ZLIB;
+			else {
+				ubifs_err("unknown compressor \"%s\"", name);
+				kfree(name);
+				return -EINVAL;
+			}
+			kfree(name);
+			c->mount_opts.override_compr = 1;
+			c->default_compr = c->mount_opts.compr_type;
+			break;
+		}
 		default:
 			ubifs_err("unrecognized mount option \"%s\" "
 				  "or missing value", p);
@@ -1039,11 +1070,9 @@ static int mount_ubifs(struct ubifs_info *c)
 	if (err)
 		return err;
 
-#ifdef CONFIG_UBIFS_FS_DEBUG
-	c->dbg_buf = vmalloc(c->leb_size);
-	if (!c->dbg_buf)
-		return -ENOMEM;
-#endif
+	err = ubifs_debugging_init(c);
+	if (err)
+		return err;
 
 	err = check_volume_empty(c);
 	if (err)
@@ -1100,27 +1129,25 @@ static int mount_ubifs(struct ubifs_info *c)
 		goto out_free;
 
 	/*
-	 * Make sure the compressor which is set as the default on in the
-	 * superblock was actually compiled in.
+	 * Make sure the compressor which is set as default in the superblock
+	 * or overriden by mount options is actually compiled in.
 	 */
 	if (!ubifs_compr_present(c->default_compr)) {
-		ubifs_warn("'%s' compressor is set by superblock, but not "
-			   "compiled in", ubifs_compr_name(c->default_compr));
-		c->default_compr = UBIFS_COMPR_NONE;
+		ubifs_err("'compressor \"%s\" is not compiled in",
+			  ubifs_compr_name(c->default_compr));
+		goto out_free;
 	}
 
-	dbg_failure_mode_registration(c);
-
 	err = init_constants_late(c);
 	if (err)
-		goto out_dereg;
+		goto out_free;
 
 	sz = ALIGN(c->max_idx_node_sz, c->min_io_size);
 	sz = ALIGN(sz + c->max_idx_node_sz, c->min_io_size);
 	c->cbuf = kmalloc(sz, GFP_NOFS);
 	if (!c->cbuf) {
 		err = -ENOMEM;
-		goto out_dereg;
+		goto out_free;
 	}
 
 	sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);
@@ -1232,6 +1259,10 @@ static int mount_ubifs(struct ubifs_info *c)
 		}
 	}
 
+	err = dbg_debugfs_init_fs(c);
+	if (err)
+		goto out_infos;
+
 	err = dbg_check_filesystem(c);
 	if (err)
 		goto out_infos;
@@ -1320,14 +1351,12 @@ out_wbufs:
 	free_wbufs(c);
 out_cbuf:
 	kfree(c->cbuf);
-out_dereg:
-	dbg_failure_mode_deregistration(c);
 out_free:
 	kfree(c->bu.buf);
 	vfree(c->ileb_buf);
 	vfree(c->sbuf);
 	kfree(c->bottom_up_buf);
-	UBIFS_DBG(vfree(c->dbg_buf));
+	ubifs_debugging_exit(c);
 	return err;
 }
 
@@ -1345,6 +1374,7 @@ static void ubifs_umount(struct ubifs_info *c)
 	dbg_gen("un-mounting UBI device %d, volume %d", c->vi.ubi_num,
 		c->vi.vol_id);
 
+	dbg_debugfs_exit_fs(c);
 	spin_lock(&ubifs_infos_lock);
 	list_del(&c->infos_list);
 	spin_unlock(&ubifs_infos_lock);
@@ -1364,8 +1394,7 @@ static void ubifs_umount(struct ubifs_info *c)
 	vfree(c->ileb_buf);
 	vfree(c->sbuf);
 	kfree(c->bottom_up_buf);
-	UBIFS_DBG(vfree(c->dbg_buf));
-	dbg_failure_mode_deregistration(c);
+	ubifs_debugging_exit(c);
 }
 
 /**
@@ -1849,7 +1878,6 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
 		goto out_iput;
 
 	mutex_unlock(&c->umount_mutex);
-
 	return 0;
 
 out_iput:
@@ -2021,6 +2049,14 @@ static int __init ubifs_init(void)
 	BUILD_BUG_ON(UBIFS_REF_NODE_SZ != 64);
 
 	/*
+	 * We use 2 bit wide bit-fields to store compression type, which should
+	 * be amended if more compressors are added. The bit-fields are:
+	 * @compr_type in 'struct ubifs_inode', @default_compr in
+	 * 'struct ubifs_info' and @compr_type in 'struct ubifs_mount_opts'.
+	 */
+	BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);
+
+	/*
 	 * We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
 	 * UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
 	 */
@@ -2049,11 +2085,17 @@ static int __init ubifs_init(void)
 
 	err = ubifs_compressors_init();
 	if (err)
+		goto out_shrinker;
+
+	err = dbg_debugfs_init();
+	if (err)
 		goto out_compr;
 
 	return 0;
 
 out_compr:
+	ubifs_compressors_exit();
+out_shrinker:
 	unregister_shrinker(&ubifs_shrinker_info);
 	kmem_cache_destroy(ubifs_inode_slab);
 out_reg:
@@ -2068,6 +2110,7 @@ static void __exit ubifs_exit(void)
 	ubifs_assert(list_empty(&ubifs_infos));
 	ubifs_assert(atomic_long_read(&ubifs_clean_zn_cnt) == 0);
 
+	dbg_debugfs_exit();
 	ubifs_compressors_exit();
 	unregister_shrinker(&ubifs_shrinker_info);
 	kmem_cache_destroy(ubifs_inode_slab);
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
index 8ac76b1c2d55..fde8d127c768 100644
--- a/fs/ubifs/tnc_commit.c
+++ b/fs/ubifs/tnc_commit.c
@@ -553,8 +553,8 @@ static int layout_in_empty_space(struct ubifs_info *c)
 	}
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
-	c->new_ihead_lnum = lnum;
-	c->new_ihead_offs = buf_offs;
+	c->dbg->new_ihead_lnum = lnum;
+	c->dbg->new_ihead_offs = buf_offs;
 #endif
 
 	return 0;
@@ -802,8 +802,10 @@ int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 	 * budgeting subsystem to assume the index is already committed,
 	 * even though it is not.
 	 */
+	ubifs_assert(c->min_idx_lebs == ubifs_calc_min_idx_lebs(c));
 	c->old_idx_sz = c->calc_idx_sz;
 	c->budg_uncommitted_idx = 0;
+	c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
 	spin_unlock(&c->space_lock);
 	mutex_unlock(&c->tnc_mutex);
 
@@ -1002,7 +1004,8 @@ static int write_index(struct ubifs_info *c)
 	}
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
-	if (lnum != c->new_ihead_lnum || buf_offs != c->new_ihead_offs) {
+	if (lnum != c->dbg->new_ihead_lnum ||
+	    buf_offs != c->dbg->new_ihead_offs) {
 		ubifs_err("inconsistent ihead");
 		return -EINVAL;
 	}
diff --git a/fs/ubifs/ubifs-media.h b/fs/ubifs/ubifs-media.h
index 0b378042a3a2..b25fc36cf72f 100644
--- a/fs/ubifs/ubifs-media.h
+++ b/fs/ubifs/ubifs-media.h
@@ -51,6 +51,13 @@
  */
 #define UBIFS_MIN_COMPR_LEN 128
 
+/*
+ * If compressed data length is less than %UBIFS_MIN_COMPRESS_DIFF bytes
+ * shorter than uncompressed data length, UBIFS preferes to leave this data
+ * node uncompress, because it'll be read faster.
+ */
+#define UBIFS_MIN_COMPRESS_DIFF 64
+
 /* Root inode number */
 #define UBIFS_ROOT_INO 1
 
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 46b172560a06..a17dd794ae92 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -63,6 +63,14 @@
 #define SQNUM_WARN_WATERMARK 0xFFFFFFFF00000000ULL
 #define SQNUM_WATERMARK      0xFFFFFFFFFF000000ULL
 
+/*
+ * Minimum amount of LEBs reserved for the index. At present the index needs at
+ * least 2 LEBs: one for the index head and one for in-the-gaps method (which
+ * currently does not cater for the index head and so excludes it from
+ * consideration).
+ */
+#define MIN_INDEX_LEBS 2
+
 /* Minimum amount of data UBIFS writes to the flash */
 #define MIN_WRITE_SZ (UBIFS_DATA_NODE_SZ + 8)
 
@@ -386,12 +394,12 @@ struct ubifs_inode {
 	unsigned int dirty:1;
 	unsigned int xattr:1;
 	unsigned int bulk_read:1;
+	unsigned int compr_type:2;
 	struct mutex ui_mutex;
 	spinlock_t ui_lock;
 	loff_t synced_i_size;
 	loff_t ui_size;
 	int flags;
-	int compr_type;
 	pgoff_t last_page_read;
 	pgoff_t read_in_a_row;
 	int data_len;
@@ -419,7 +427,7 @@ struct ubifs_unclean_leb {
  *
  * LPROPS_UNCAT: not categorized
  * LPROPS_DIRTY: dirty > 0, not index
- * LPROPS_DIRTY_IDX: dirty + free > UBIFS_CH_SZ and index
+ * LPROPS_DIRTY_IDX: dirty + free > @c->min_idx_node_sze and index
  * LPROPS_FREE: free > 0, not empty, not index
  * LPROPS_HEAP_CNT: number of heaps used for storing categorized LEBs
  * LPROPS_EMPTY: LEB is empty, not taken
@@ -482,24 +490,26 @@ struct ubifs_lpt_lprops {
  * @empty_lebs: number of empty LEBs
  * @taken_empty_lebs: number of taken LEBs
  * @idx_lebs: number of indexing LEBs
- * @total_free: total free space in bytes
- * @total_dirty: total dirty space in bytes
- * @total_used: total used space in bytes (includes only data LEBs)
- * @total_dead: total dead space in bytes (includes only data LEBs)
- * @total_dark: total dark space in bytes (includes only data LEBs)
+ * @total_free: total free space in bytes (includes all LEBs)
+ * @total_dirty: total dirty space in bytes (includes all LEBs)
+ * @total_used: total used space in bytes (does not include index LEBs)
+ * @total_dead: total dead space in bytes (does not include index LEBs)
+ * @total_dark: total dark space in bytes (does not include index LEBs)
+ *
+ * The @taken_empty_lebs field counts the LEBs that are in the transient state
+ * of having been "taken" for use but not yet written to. @taken_empty_lebs is
+ * needed to account correctly for @gc_lnum, otherwise @empty_lebs could be
+ * used by itself (in which case 'unused_lebs' would be a better name). In the
+ * case of @gc_lnum, it is "taken" at mount time or whenever a LEB is retained
+ * by GC, but unlike other empty LEBs that are "taken", it may not be written
+ * straight away (i.e. before the next commit start or unmount), so either
+ * @gc_lnum must be specially accounted for, or the current approach followed
+ * i.e. count it under @taken_empty_lebs.
  *
- * N.B. total_dirty and total_used are different to other total_* fields,
- * because they account _all_ LEBs, not just data LEBs.
+ * @empty_lebs includes @taken_empty_lebs.
  *
- * 'taken_empty_lebs' counts the LEBs that are in the transient state of having
- * been 'taken' for use but not yet written to. 'taken_empty_lebs' is needed
- * to account correctly for gc_lnum, otherwise 'empty_lebs' could be used
- * by itself (in which case 'unused_lebs' would be a better name). In the case
- * of gc_lnum, it is 'taken' at mount time or whenever a LEB is retained by GC,
- * but unlike other empty LEBs that are 'taken', it may not be written straight
- * away (i.e. before the next commit start or unmount), so either gc_lnum must
- * be specially accounted for, or the current approach followed i.e. count it
- * under 'taken_empty_lebs'.
+ * @total_used, @total_dead and @total_dark fields do not account indexing
+ * LEBs.
  */
 struct ubifs_lp_stats {
 	int empty_lebs;
@@ -893,15 +903,25 @@ struct ubifs_orphan {
 /**
  * struct ubifs_mount_opts - UBIFS-specific mount options information.
  * @unmount_mode: selected unmount mode (%0 default, %1 normal, %2 fast)
- * @bulk_read: enable bulk-reads
- * @chk_data_crc: check CRCs when reading data nodes
+ * @bulk_read: enable/disable bulk-reads (%0 default, %1 disabe, %2 enable)
+ * @chk_data_crc: enable/disable CRC data checking when reading data nodes
+ *                (%0 default, %1 disabe, %2 enable)
+ * @override_compr: override default compressor (%0 - do not override and use
+ *                  superblock compressor, %1 - override and use compressor
+ *                  specified in @compr_type)
+ * @compr_type: compressor type to override the superblock compressor with
+ *              (%UBIFS_COMPR_NONE, etc)
  */
 struct ubifs_mount_opts {
 	unsigned int unmount_mode:2;
 	unsigned int bulk_read:2;
 	unsigned int chk_data_crc:2;
+	unsigned int override_compr:1;
+	unsigned int compr_type:2;
 };
 
+struct ubifs_debug_info;
+
 /**
  * struct ubifs_info - UBIFS file-system description data structure
  * (per-superblock).
@@ -946,6 +966,7 @@ struct ubifs_mount_opts {
  * @no_chk_data_crc: do not check CRCs when reading data nodes (except during
  *                   recovery)
  * @bulk_read: enable bulk-reads
+ * @default_compr: default compression algorithm (%UBIFS_COMPR_LZO, etc)
  *
  * @tnc_mutex: protects the Tree Node Cache (TNC), @zroot, @cnext, @enext, and
  *             @calc_idx_sz
@@ -963,8 +984,6 @@ struct ubifs_mount_opts {
  * @ileb_nxt: next pre-allocated index LEBs
  * @old_idx: tree of index nodes obsoleted since the last commit start
  * @bottom_up_buf: a buffer which is used by 'dirty_cow_bottom_up()' in tnc.c
- * @new_ihead_lnum: used by debugging to check ihead_lnum
- * @new_ihead_offs: used by debugging to check ihead_offs
  *
  * @mst_node: master node
  * @mst_offs: offset of valid master node
@@ -986,7 +1005,6 @@ struct ubifs_mount_opts {
  * @main_lebs: count of LEBs in the main area
  * @main_first: first LEB of the main area
  * @main_bytes: main area size in bytes
- * @default_compr: default compression algorithm (%UBIFS_COMPR_LZO, etc)
  *
  * @key_hash_type: type of the key hash
  * @key_hash: direntry key hash function
@@ -1149,15 +1167,8 @@ struct ubifs_mount_opts {
  * @always_chk_crc: always check CRCs (while mounting and remounting rw)
  * @mount_opts: UBIFS-specific mount options
  *
- * @dbg_buf: a buffer of LEB size used for debugging purposes
- * @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
+ * @dbg: debugging-related information
+ * @dfs: debugfs support-related information
  */
 struct ubifs_info {
 	struct super_block *vfs_sb;
@@ -1196,6 +1207,7 @@ struct ubifs_info {
 	unsigned int big_lpt:1;
 	unsigned int no_chk_data_crc:1;
 	unsigned int bulk_read:1;
+	unsigned int default_compr:2;
 
 	struct mutex tnc_mutex;
 	struct ubifs_zbranch zroot;
@@ -1212,10 +1224,6 @@ struct ubifs_info {
 	int ileb_nxt;
 	struct rb_root old_idx;
 	int *bottom_up_buf;
-#ifdef CONFIG_UBIFS_FS_DEBUG
-	int new_ihead_lnum;
-	int new_ihead_offs;
-#endif
 
 	struct ubifs_mst_node *mst_node;
 	int mst_offs;
@@ -1237,7 +1245,6 @@ struct ubifs_info {
 	int main_lebs;
 	int main_first;
 	long long main_bytes;
-	int default_compr;
 
 	uint8_t key_hash_type;
 	uint32_t (*key_hash)(const char *str, int len);
@@ -1391,21 +1398,7 @@ struct ubifs_info {
 	struct ubifs_mount_opts mount_opts;
 
 #ifdef CONFIG_UBIFS_FS_DEBUG
-	void *dbg_buf;
-	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;
-	long long chk_lpt_sz;
-	long long chk_lpt_sz2;
-	long long chk_lpt_wastage;
-	int chk_lpt_lebs;
-	int new_nhead_lnum;
-	int new_nhead_offs;
+	struct ubifs_debug_info *dbg;
 #endif
 };
 
@@ -1505,7 +1498,7 @@ void ubifs_cancel_ino_op(struct ubifs_info *c, struct inode *inode,
 long long ubifs_get_free_space(struct ubifs_info *c);
 int ubifs_calc_min_idx_lebs(struct ubifs_info *c);
 void ubifs_convert_page_budget(struct ubifs_info *c);
-long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free);
+long long ubifs_reported_space(const struct ubifs_info *c, long long free);
 long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs);
 
 /* find.c */
@@ -1639,6 +1632,9 @@ void ubifs_add_lpt_dirt(struct ubifs_info *c, int lnum, int dirty);
 void ubifs_add_nnode_dirt(struct ubifs_info *c, struct ubifs_nnode *nnode);
 uint32_t ubifs_unpack_bits(uint8_t **addr, int *pos, int nrbits);
 struct ubifs_nnode *ubifs_first_nnode(struct ubifs_info *c, int *hght);
+/* Needed only in debugging code in lpt_commit.c */
+int ubifs_unpack_nnode(const struct ubifs_info *c, void *buf,
+		       struct ubifs_nnode *nnode);
 
 /* lpt_commit.c */
 int ubifs_lpt_start_commit(struct ubifs_info *c);
@@ -1714,7 +1710,7 @@ long ubifs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 
 /* compressor.c */
 int __init ubifs_compressors_init(void);
-void __exit ubifs_compressors_exit(void);
+void ubifs_compressors_exit(void);
 void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
 		    int *compr_type);
 int ubifs_decompress(const void *buf, int len, void *out, int *out_len,