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

* 'linux-next' of git://git.infradead.org/ubifs-2.6: (33 commits)
  UBIFS: add more useful debugging prints
  UBIFS: print debugging messages properly
  UBIFS: fix numerous spelling mistakes
  UBIFS: allow mounting when short of space
  UBIFS: fix writing uncompressed files
  UBIFS: fix checkpatch.pl warnings
  UBIFS: fix sparse warnings
  UBIFS: simplify make_free_space
  UBIFS: do not lie about used blocks
  UBIFS: restore budg_uncommitted_idx
  UBIFS: always commit on unmount
  UBIFS: use ubi_sync
  UBIFS: always commit in sync_fs
  UBIFS: fix file-system synchronization
  UBIFS: fix constants initialization
  UBIFS: avoid unnecessary calculations
  UBIFS: re-calculate min_idx_size after the commit
  UBIFS: use nicer 64-bit math
  UBIFS: fix available blocks count
  UBIFS: various comment improvements and fixes
  ...

20 files changed, 924 insertions, 474 deletions

diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
index 4a18f084cc4..0e5e54d8292 100644
--- a/fs/ubifs/budget.c
+++ b/fs/ubifs/budget.c
@@ -32,18 +32,15 @@
 
 #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,
  * UBIFS starts writing back dirty inodes and pages, doing garbage collection,
- * or committing. The below constants define maximum number of times UBIFS
+ * or committing. The below constant defines maximum number of times UBIFS
  * repeats the operations.
  */
-#define MAX_SHRINK_RETRIES 8
-#define MAX_GC_RETRIES     4
-#define MAX_CMT_RETRIES    2
-#define MAX_NOSPC_RETRIES  1
+#define MAX_MKSPC_RETRIES 3
 
 /*
  * The below constant defines amount of dirty pages which should be written
@@ -52,30 +49,6 @@
 #define NR_TO_WRITE 16
 
 /**
- * struct retries_info - information about re-tries while making free space.
- * @prev_liability: previous liability
- * @shrink_cnt: how many times the liability was shrinked
- * @shrink_retries: count of liability shrink re-tries (increased when
- *                  liability does not shrink)
- * @try_gc: GC should be tried first
- * @gc_retries: how many times GC was run
- * @cmt_retries: how many times commit has been done
- * @nospc_retries: how many times GC returned %-ENOSPC
- *
- * Since we consider budgeting to be the fast-path, and this structure has to
- * be allocated on stack and zeroed out, we make it smaller using bit-fields.
- */
-struct retries_info {
-	long long prev_liability;
-	unsigned int shrink_cnt;
-	unsigned int shrink_retries:5;
-	unsigned int try_gc:1;
-	unsigned int gc_retries:4;
-	unsigned int cmt_retries:3;
-	unsigned int nospc_retries:1;
-};
-
-/**
  * shrink_liability - write-back some dirty pages/inodes.
  * @c: UBIFS file-system description object
  * @nr_to_write: how many dirty pages to write-back
@@ -147,9 +120,25 @@ static int run_gc(struct ubifs_info *c)
 }
 
 /**
+ * get_liability - calculate current liability.
+ * @c: UBIFS file-system description object
+ *
+ * This function calculates and returns current UBIFS liability, i.e. the
+ * amount of bytes UBIFS has "promised" to write to the media.
+ */
+static long long get_liability(struct ubifs_info *c)
+{
+	long long liab;
+
+	spin_lock(&c->space_lock);
+	liab = c->budg_idx_growth + c->budg_data_growth + c->budg_dd_growth;
+	spin_unlock(&c->space_lock);
+	return liab;
+}
+
+/**
  * make_free_space - make more free space on the file-system.
  * @c: UBIFS file-system description object
- * @ri: information about previous invocations of this function
  *
  * This function is called when an operation cannot be budgeted because there
  * is supposedly no free space. But in most cases there is some free space:
@@ -165,87 +154,42 @@ static int run_gc(struct ubifs_info *c)
  * Returns %-ENOSPC if it couldn't do more free space, and other negative error
  * codes on failures.
  */
-static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
+static int make_free_space(struct ubifs_info *c)
 {
-	int err;
-
-	/*
-	 * If we have some dirty pages and inodes (liability), try to write
-	 * them back unless this was tried too many times without effect
-	 * already.
-	 */
-	if (ri->shrink_retries < MAX_SHRINK_RETRIES && !ri->try_gc) {
-		long long liability;
-
-		spin_lock(&c->space_lock);
-		liability = c->budg_idx_growth + c->budg_data_growth +
-			    c->budg_dd_growth;
-		spin_unlock(&c->space_lock);
+	int err, retries = 0;
+	long long liab1, liab2;
 
-		if (ri->prev_liability >= liability) {
-			/* Liability does not shrink, next time try GC then */
-			ri->shrink_retries += 1;
-			if (ri->gc_retries < MAX_GC_RETRIES)
-				ri->try_gc = 1;
-			dbg_budg("liability did not shrink: retries %d of %d",
-				 ri->shrink_retries, MAX_SHRINK_RETRIES);
-		}
+	do {
+		liab1 = get_liability(c);
+		/*
+		 * We probably have some dirty pages or inodes (liability), try
+		 * to write them back.
+		 */
+		dbg_budg("liability %lld, run write-back", liab1);
+		shrink_liability(c, NR_TO_WRITE);
 
-		dbg_budg("force write-back (count %d)", ri->shrink_cnt);
-		shrink_liability(c, NR_TO_WRITE + ri->shrink_cnt);
+		liab2 = get_liability(c);
+		if (liab2 < liab1)
+			return -EAGAIN;
 
-		ri->prev_liability = liability;
-		ri->shrink_cnt += 1;
-		return -EAGAIN;
-	}
+		dbg_budg("new liability %lld (not shrinked)", liab2);
 
-	/*
-	 * Try to run garbage collector unless it was already tried too many
-	 * times.
-	 */
-	if (ri->gc_retries < MAX_GC_RETRIES) {
-		ri->gc_retries += 1;
-		dbg_budg("run GC, retries %d of %d",
-			 ri->gc_retries, MAX_GC_RETRIES);
-
-		ri->try_gc = 0;
+		/* Liability did not shrink again, try GC */
+		dbg_budg("Run GC");
 		err = run_gc(c);
 		if (!err)
 			return -EAGAIN;
 
-		if (err == -EAGAIN) {
-			dbg_budg("GC asked to commit");
-			err = ubifs_run_commit(c);
-			if (err)
-				return err;
-			return -EAGAIN;
-		}
-
-		if (err != -ENOSPC)
-			return err;
-
-		/*
-		 * GC could not make any progress. If this is the first time,
-		 * then it makes sense to try to commit, because it might make
-		 * some dirty space.
-		 */
-		dbg_budg("GC returned -ENOSPC, retries %d",
-			 ri->nospc_retries);
-		if (ri->nospc_retries >= MAX_NOSPC_RETRIES)
+		if (err != -EAGAIN && err != -ENOSPC)
+			/* Some real error happened */
 			return err;
-		ri->nospc_retries += 1;
-	}
 
-	/* Neither GC nor write-back helped, try to commit */
-	if (ri->cmt_retries < MAX_CMT_RETRIES) {
-		ri->cmt_retries += 1;
-		dbg_budg("run commit, retries %d of %d",
-			 ri->cmt_retries, MAX_CMT_RETRIES);
+		dbg_budg("Run commit (retries %d)", retries);
 		err = ubifs_run_commit(c);
 		if (err)
 			return err;
-		return -EAGAIN;
-	}
+	} while (retries++ < MAX_MKSPC_RETRIES);
+
 	return -ENOSPC;
 }
 
@@ -258,8 +202,8 @@ 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 +215,16 @@ 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;
 }
 
 /**
@@ -530,8 +467,7 @@ static int calc_dd_growth(const struct ubifs_info *c,
 int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req)
 {
 	int uninitialized_var(cmt_retries), uninitialized_var(wb_retries);
-	int err, idx_growth, data_growth, dd_growth;
-	struct retries_info ri;
+	int err, idx_growth, data_growth, dd_growth, retried = 0;
 
 	ubifs_assert(req->new_page <= 1);
 	ubifs_assert(req->dirtied_page <= 1);
@@ -549,7 +485,6 @@ int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req)
 	if (!data_growth && !dd_growth)
 		return 0;
 	idx_growth = calc_idx_growth(c, req);
-	memset(&ri, 0, sizeof(struct retries_info));
 
 again:
 	spin_lock(&c->space_lock);
@@ -587,12 +522,17 @@ again:
 		return err;
 	}
 
-	err = make_free_space(c, &ri);
+	err = make_free_space(c);
+	cond_resched();
 	if (err == -EAGAIN) {
 		dbg_budg("try again");
-		cond_resched();
 		goto again;
 	} else if (err == -ENOSPC) {
+		if (!retried) {
+			retried = 1;
+			dbg_budg("-ENOSPC, but anyway try once again");
+			goto again;
+		}
 		dbg_budg("FS is full, -ENOSPC");
 		c->nospace = 1;
 		if (can_use_rp(c) || c->rp_size == 0)
@@ -712,9 +652,9 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
  * user-space. User-space application tend to expect that if the file-system
  * (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.
+ * node and it has to write indexing nodes as well. This introduces additional
+ * overhead, and UBIFS has to report slightly less free space to meet the above
+ * expectations.
  *
  * 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 +663,7 @@ 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;
 
@@ -737,7 +677,7 @@ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
 	 * of data nodes, f - fanout. Because effective UBIFS fanout is twice
 	 * as less than maximum fanout, we assume that each data node
 	 * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes.
-	 * Note, the multiplier 3 is because UBIFS reseves thrice as more space
+	 * Note, the multiplier 3 is because UBIFS reserves thrice as more space
 	 * for the index.
 	 */
 	f = c->fanout > 3 ? c->fanout >> 1 : 2;
@@ -745,8 +685,7 @@ 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);
 }
 
 /**
@@ -756,10 +695,10 @@ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
  * This function calculates amount of free space to report to user-space.
  *
  * Because UBIFS may introduce substantial overhead (the index, node headers,
- * alighment, wastage at the end of eraseblocks, etc), it cannot report real
+ * alignment, wastage at the end of eraseblocks, etc), it cannot report real
  * amount of free flash space it has (well, because not all dirty space is
- * reclamable, UBIFS does not actually know the real amount). If UBIFS did so,
- * it would bread user expectetion about what free space is. Users seem to
+ * reclaimable, UBIFS does not actually know the real amount). If UBIFS did so,
+ * it would bread user expectations about what free space is. Users seem to
  * accustomed to assume that if the file-system reports N bytes of free space,
  * they would be able to fit a file of N bytes to the FS. This almost works for
  * traditional file-systems, because they have way less overhead than UBIFS.
@@ -771,18 +710,9 @@ 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;
-
-	/*
-	 * Force the amount available to the total size reported if the used
-	 * space is zero.
-	 */
-	if (c->lst.total_used <= UBIFS_INO_NODE_SZ && !outstanding) {
-		spin_unlock(&c->space_lock);
-		return (long long)c->block_cnt << UBIFS_BLOCK_SHIFT;
-	}
-
 	available = ubifs_calc_available(c, min_idx_lebs);
 
 	/*
diff --git a/fs/ubifs/commit.c b/fs/ubifs/commit.c
index b49884c8c10..f3a7945527f 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 a0ada596b17..11e4132f314 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
 
@@ -108,7 +108,7 @@ void ubifs_compress(const void *in_buf, int in_len, void *out_buf, int *out_len,
 	if (compr->comp_mutex)
 		mutex_lock(compr->comp_mutex);
 	err = crypto_comp_compress(compr->cc, in_buf, in_len, out_buf,
-				   out_len);
+				   (unsigned int *)out_len);
 	if (compr->comp_mutex)
 		mutex_unlock(compr->comp_mutex);
 	if (unlikely(err)) {
@@ -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;
@@ -172,7 +172,7 @@ int ubifs_decompress(const void *in_buf, int in_len, void *out_buf,
 	if (compr->decomp_mutex)
 		mutex_lock(compr->decomp_mutex);
 	err = crypto_comp_decompress(compr->cc, in_buf, in_len, out_buf,
-				     out_len);
+				     (unsigned int *)out_len);
 	if (compr->decomp_mutex)
 		mutex_unlock(compr->decomp_mutex);
 	if (err)
@@ -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 510ffa0bbda..792c5a16c18 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);
@@ -684,7 +703,8 @@ void dbg_dump_lpt_info(struct ubifs_info *c)
 	printk(KERN_DEBUG "\tLPT root is at %d:%d\n", c->lpt_lnum, c->lpt_offs);
 	printk(KERN_DEBUG "\tLPT head is at %d:%d\n",
 	       c->nhead_lnum, c->nhead_offs);
-	printk(KERN_DEBUG "\tLPT ltab is at %d:%d\n", c->ltab_lnum, c->ltab_offs);
+	printk(KERN_DEBUG "\tLPT ltab is at %d:%d\n",
+	       c->ltab_lnum, c->ltab_offs);
 	if (c->big_lpt)
 		printk(KERN_DEBUG "\tLPT lsave is at %d:%d\n",
 		       c->lsave_lnum, c->lsave_offs);
@@ -703,9 +723,9 @@ 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 +741,8 @@ 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 +790,7 @@ 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 +799,7 @@ 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 +807,7 @@ 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 +826,7 @@ 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 +838,7 @@ 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,
@@ -992,8 +1014,8 @@ static int dbg_check_key_order(struct ubifs_info *c, struct ubifs_zbranch *zbr1,
 			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;
+		dbg_dump_node(c, dent1);
+		goto out_free;
 	}
 
 	key_read(c, &dent2->key, &key);
@@ -1002,8 +1024,8 @@ static int dbg_check_key_order(struct ubifs_info *c, struct ubifs_zbranch *zbr1,
 			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;
+		dbg_dump_node(c, dent2);
+		goto out_free;
 	}
 
 	nlen1 = le16_to_cpu(dent1->nlen);
@@ -1020,9 +1042,9 @@ static int dbg_check_key_order(struct ubifs_info *c, struct ubifs_zbranch *zbr1,
 		dbg_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 +2119,13 @@ 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 +2134,7 @@ 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 +2168,44 @@ 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 +2263,7 @@ 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 +2368,181 @@ 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_