[PATCH take 2 19/28] UBIFS: add LEB properties tree

[Artem Bityutskiy]

This is the commit-related part of the lprops sub-system.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@xxxxxxxxx>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@xxxxxxxxx>
---
 fs/ubifs/lpt_commit.c | 1625 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 1625 insertions(+), 0 deletions(-)

diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
new file mode 100644
index 0000000..797c56d
--- /dev/null
+++ b/fs/ubifs/lpt_commit.c
@@ -0,0 +1,1625 @@
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors: Adrian Hunter
+ *          Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file implements commit-related functionality of the LEB properties
+ * subsystem.
+ */
+
+#include <linux/crc16.h>
+#include "ubifs.h"
+
+/**
+ * first_dirty_cnode - find first dirty cnode.
+ * @c: UBIFS file-system description object
+ * @nnode: nnode at which to start
+ *
+ * This function returns the first dirty cnode or %NULL if there is not one.
+ */
+static struct ubifs_cnode *first_dirty_cnode(struct ubifs_nnode *nnode)
+{
+	ubifs_assert(nnode);
+	while (1) {
+		int i, cont = 0;
+
+		for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
+			struct ubifs_cnode *cnode;
+
+			cnode = nnode->nbranch[i].cnode;
+			if (cnode &&
+			    test_bit(DIRTY_CNODE, &cnode->flags)) {
+				if (cnode->level == 0)
+					return cnode;
+				nnode = (struct ubifs_nnode *)cnode;
+				cont = 1;
+				break;
+			}
+		}
+		if (!cont)
+			return (struct ubifs_cnode *)nnode;
+	}
+}
+
+/**
+ * next_dirty_cnode - find next dirty cnode.
+ * @cnode: cnode from which to begin searching
+ *
+ * This function returns the next dirty cnode or %NULL if there is not one.
+ */
+static struct ubifs_cnode *next_dirty_cnode(struct ubifs_cnode *cnode)
+{
+	struct ubifs_nnode *nnode;
+	int i;
+
+	ubifs_assert(cnode);
+	nnode = cnode->parent;
+	if (!nnode)
+		return NULL;
+	for (i = cnode->iip + 1; i < UBIFS_LPT_FANOUT; i++) {
+		cnode = nnode->nbranch[i].cnode;
+		if (cnode && test_bit(DIRTY_CNODE, &cnode->flags)) {
+			if (cnode->level == 0)
+				return cnode; /* cnode is a pnode */
+			/* cnode is a nnode */
+			return first_dirty_cnode((struct ubifs_nnode *)cnode);
+		}
+	}
+	return (struct ubifs_cnode *)nnode;
+}
+
+/**
+ * get_cnodes_to_commit - create list of dirty cnodes to commit.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns the number of cnodes to commit.
+ */
+static int get_cnodes_to_commit(struct ubifs_info *c)
+{
+	struct ubifs_cnode *cnode, *cnext;
+	int cnt = 0;
+
+	if (!c->nroot)
+		return 0;
+
+	if (!test_bit(DIRTY_CNODE, &c->nroot->flags))
+		return 0;
+
+	c->lpt_cnext = first_dirty_cnode(c->nroot);
+	cnode = c->lpt_cnext;
+	if (!cnode)
+		return 0;
+	cnt += 1;
+	while (1) {
+		ubifs_assert(!test_bit(COW_ZNODE, &cnode->flags));
+		set_bit(COW_ZNODE, &cnode->flags);
+		cnext = next_dirty_cnode(cnode);
+		if (!cnext) {
+			cnode->cnext = c->lpt_cnext;
+			break;
+		}
+		cnode->cnext = cnext;
+		cnode = cnext;
+		cnt += 1;
+	}
+	dbg_cmt("committing %d cnodes", cnt);
+	dbg_lp("committing %d cnodes", cnt);
+	ubifs_assert(cnt == c->dirty_nn_cnt + c->dirty_pn_cnt);
+	return cnt;
+}
+
+/**
+ * upd_ltab - update LPT LEB properties.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number
+ * @free: amount of free space
+ * @dirty: amount of dirty space to add
+ */
+static void upd_ltab(struct ubifs_info *c, int lnum, int free, int dirty)
+{
+	dbg_lp("LEB %d free %d dirty %d to %d +%d",
+	       lnum, c->ltab[lnum - c->lpt_first].free,
+	       c->ltab[lnum - c->lpt_first].dirty, free, dirty);
+	ubifs_assert(lnum >= c->lpt_first && lnum <= c->lpt_last);
+	c->ltab[lnum - c->lpt_first].free = free;
+	c->ltab[lnum - c->lpt_first].dirty += dirty;
+}
+
+/**
+ * alloc_lpt_leb - allocate an LPT LEB that is empty.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number is passed and returned here
+ *
+ * This function finds the next empty LEB in the ltab starting from @lnum. If a
+ * an empty LEB is found it is returned in @lnum and the function returns %0.
+ * Otherwise the function returns -ENOSPC.  Note however, that LPT is designed
+ * never to run out of space.
+ */
+static int alloc_lpt_leb(struct ubifs_info *c, int *lnum)
+{
+	int i, n;
+
+	n = *lnum - c->lpt_first + 1;
+	for (i = n; i < c->lpt_lebs; i++) {
+		if (c->ltab[i].tgc || c->ltab[i].cmt)
+			continue;
+		if (c->ltab[i].free == c->leb_size) {
+			c->ltab[i].cmt = 1;
+			*lnum = i + c->lpt_first;
+			return 0;
+		}
+	}
+
+	for (i = 0; i < n; i++) {
+		if (c->ltab[i].tgc || c->ltab[i].cmt)
+			continue;
+		if (c->ltab[i].free == c->leb_size) {
+			c->ltab[i].cmt = 1;
+			*lnum = i + c->lpt_first;
+			return 0;
+		}
+	}
+	dbg_err("last LEB %d", *lnum);
+	dump_stack();
+	return -ENOSPC;
+}
+
+/**
+ * layout_cnodes - layout cnodes for commit.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int layout_cnodes(struct ubifs_info *c)
+{
+	int lnum, offs, len, alen, done_lsave, done_ltab, err;
+	struct ubifs_cnode *cnode;
+
+	cnode = c->lpt_cnext;
+	if (!cnode)
+		return 0;
+	lnum = c->nhead_lnum;
+	offs = c->nhead_offs;
+	/* Try to place lsave and ltab nicely */
+	done_lsave = !c->big_lpt;
+	done_ltab = 0;
+	if (!done_lsave && offs + c->lsave_sz <= c->leb_size) {
+		done_lsave = 1;
+		c->lsave_lnum = lnum;
+		c->lsave_offs = offs;
+		offs += c->lsave_sz;
+	}
+
+	if (offs + c->ltab_sz <= c->leb_size) {
+		done_ltab = 1;
+		c->ltab_lnum = lnum;
+		c->ltab_offs = offs;
+		offs += c->ltab_sz;
+	}
+
+	do {
+		if (cnode->level) {
+			len = c->nnode_sz;
+			c->dirty_nn_cnt -= 1;
+		} else {
+			len = c->pnode_sz;
+			c->dirty_pn_cnt -= 1;
+		}
+		while (offs + len > c->leb_size) {
+			alen = ALIGN(offs, c->min_io_size);
+			upd_ltab(c, lnum, c->leb_size - alen, alen - offs);
+			err = alloc_lpt_leb(c, &lnum);
+			if (err)
+				return err;
+			offs = 0;
+			ubifs_assert(lnum >= c->lpt_first &&
+				     lnum <= c->lpt_last);
+			/* Try to place lsave and ltab nicely */
+			if (!done_lsave) {
+				done_lsave = 1;
+				c->lsave_lnum = lnum;
+				c->lsave_offs = offs;
+				offs += c->lsave_sz;
+				continue;
+			}
+			if (!done_ltab) {
+				done_ltab = 1;
+				c->ltab_lnum = lnum;
+				c->ltab_offs = offs;
+				offs += c->ltab_sz;
+				continue;
+			}
+			break;
+		}
+		if (cnode->parent) {
+			cnode->parent->nbranch[cnode->iip].lnum = lnum;
+			cnode->parent->nbranch[cnode->iip].offs = offs;
+		} else {
+			c->lpt_lnum = lnum;
+			c->lpt_offs = offs;
+		}
+		offs += len;
+		cnode = cnode->cnext;
+	} while (cnode && cnode != c->lpt_cnext);
+
+	/* Make sure to place LPT's save table */
+	if (!done_lsave) {
+		if (offs + c->lsave_sz > c->leb_size) {
+			alen = ALIGN(offs, c->min_io_size);
+			upd_ltab(c, lnum, c->leb_size - alen, alen - offs);
+			err = alloc_lpt_leb(c, &lnum);
+			if (err)
+				return err;
+			offs = 0;
+			ubifs_assert(lnum >= c->lpt_first &&
+				     lnum <= c->lpt_last);
+		}
+		done_lsave = 1;
+		c->lsave_lnum = lnum;
+		c->lsave_offs = offs;
+		offs += c->lsave_sz;
+	}
+
+	/* Make sure to place LPT's own lprops table */
+	if (!done_ltab) {
+		if (offs + c->ltab_sz > c->leb_size) {
+			alen = ALIGN(offs, c->min_io_size);
+			upd_ltab(c, lnum, c->leb_size - alen, alen - offs);
+			err = alloc_lpt_leb(c, &lnum);
+			if (err)
+				return err;
+			offs = 0;
+			ubifs_assert(lnum >= c->lpt_first &&
+				     lnum <= c->lpt_last);
+		}
+		done_ltab = 1;
+		c->ltab_lnum = lnum;
+		c->ltab_offs = offs;
+		offs += c->ltab_sz;
+	}
+
+	alen = ALIGN(offs, c->min_io_size);
+	upd_ltab(c, lnum, c->leb_size - alen, alen - offs);
+	return 0;
+}
+
+/**
+ * realloc_lpt_leb - allocate an LPT LEB that is empty.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number is passed and returned here
+ *
+ * This function duplicates exactly the results of the function alloc_lpt_leb.
+ * It is used during end commit to reallocate the same LEB numbers that were
+ * allocated by alloc_lpt_leb during start commit.
+ *
+ * This function finds the next LEB that was allocated by the alloc_lpt_leb
+ * function starting from @lnum. If a LEB is found it is returned in @lnum and
+ * the function returns %0. Otherwise the function returns -ENOSPC.
+ * Note however, that LPT is designed never to run out of space.
+ */
+static int realloc_lpt_leb(struct ubifs_info *c, int *lnum)
+{
+	int i, n;
+
+	n = *lnum - c->lpt_first + 1;
+	for (i = n; i < c->lpt_lebs; i++)
+		if (c->ltab[i].cmt) {
+			c->ltab[i].cmt = 0;
+			*lnum = i + c->lpt_first;
+			return 0;
+		}
+
+	for (i = 0; i < n; i++)
+		if (c->ltab[i].cmt) {
+			c->ltab[i].cmt = 0;
+			*lnum = i + c->lpt_first;
+			return 0;
+		}
+	dbg_err("last LEB %d", *lnum);
+	dump_stack();
+	return -ENOSPC;
+}
+
+/**
+ * write_cnodes - write cnodes for commit.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int write_cnodes(struct ubifs_info *c)
+{
+	int lnum, offs, len, from, err, wlen, alen, done_ltab, done_lsave;
+	struct ubifs_cnode *cnode;
+	void *buf = c->lpt_buf;
+
+	cnode = c->lpt_cnext;
+	if (!cnode)
+		return 0;
+	lnum = c->nhead_lnum;
+	offs = c->nhead_offs;
+	from = offs;
+	/* Ensure empty LEB is unmapped */
+	if (offs == 0) {
+		err = ubifs_leb_unmap(c, lnum);
+		if (err)
+			return err;
+	}
+	/* Try to place lsave and ltab nicely */
+	done_lsave = !c->big_lpt;
+	done_ltab = 0;
+	if (!done_lsave && offs + c->lsave_sz <= c->leb_size) {
+		done_lsave = 1;
+		ubifs_pack_lsave(c, buf + offs, c->lsave);
+		offs += c->lsave_sz;
+	}
+
+	if (offs + c->ltab_sz <= c->leb_size) {
+		done_ltab = 1;
+		ubifs_pack_ltab(c, buf + offs, c->ltab_cmt);
+		offs += c->ltab_sz;
+	}
+
+	/* Loop for each cnode */
+	do {
+		if (cnode->level)
+			len = c->nnode_sz;
+		else
+			len = c->pnode_sz;
+		while (offs + len > c->leb_size) {
+			wlen = offs - from;
+			if (wlen) {
+				alen = ALIGN(wlen, c->min_io_size);
+				memset(buf + offs, 0xff, alen - wlen);
+				err = ubifs_leb_write(c, lnum, buf + from, from,
+						       alen, UBI_SHORTTERM);
+				if (err)
+					return err;
+			}
+			err = realloc_lpt_leb(c, &lnum);
+			if (err)
+				return err;
+			offs = 0;
+			from = 0;
+			ubifs_assert(lnum >= c->lpt_first &&
+				     lnum <= c->lpt_last);
+			err = ubifs_leb_unmap(c, lnum);
+			if (err)
+				return err;
+			/* Try to place lsave and ltab nicely */
+			if (!done_lsave) {
+				done_lsave = 1;
+				ubifs_pack_lsave(c, buf + offs, c->lsave);
+				offs += c->lsave_sz;
+				continue;
+			}
+			if (!done_ltab) {
+				done_ltab = 1;
+				ubifs_pack_ltab(c, buf + offs, c->ltab_cmt);
+				offs += c->ltab_sz;
+				continue;
+			}
+			break;
+		}
+		if (cnode->level)
+			ubifs_pack_nnode(c, buf + offs,
+					 (struct ubifs_nnode *)cnode);
+		else
+			ubifs_pack_pnode(c, buf + offs,
+					 (struct ubifs_pnode *)cnode);
+		clear_bit(DIRTY_CNODE, &cnode->flags);
+		smp_mb__before_clear_bit();
+		clear_bit(COW_ZNODE, &cnode->flags);
+		smp_mb__after_clear_bit();
+		offs += len;
+		cnode = cnode->cnext;
+	} while (cnode && cnode != c->lpt_cnext);
+
+	/* Make sure to place LPT's save table */
+	if (!done_lsave) {
+		if (offs + c->lsave_sz > c->leb_size) {
+			wlen = offs - from;
+			alen = ALIGN(wlen, c->min_io_size);
+			memset(buf + offs, 0xff, alen - wlen);
+			err = ubifs_leb_write(c, lnum, buf + from, from, alen,
+					      UBI_SHORTTERM);
+			if (err)
+				return err;
+			err = realloc_lpt_leb(c, &lnum);
+			if (err)
+				return err;
+			offs = 0;
+			ubifs_assert(lnum >= c->lpt_first &&
+				     lnum <= c->lpt_last);
+			err = ubifs_leb_unmap(c, lnum);
+			if (err)
+				return err;
+		}
+		done_lsave = 1;
+		ubifs_pack_lsave(c, buf + offs, c->lsave);
+		offs += c->lsave_sz;
+	}
+
+	/* Make sure to place LPT's own lprops table */
+	if (!done_ltab) {
+		if (offs + c->ltab_sz > c->leb_size) {
+			wlen = offs - from;
+			alen = ALIGN(wlen, c->min_io_size);
+			memset(buf + offs, 0xff, alen - wlen);
+			err = ubifs_leb_write(c, lnum, buf + from, from, alen,
+					      UBI_SHORTTERM);
+			if (err)
+				return err;
+			err = realloc_lpt_leb(c, &lnum);
+			if (err)
+				return err;
+			offs = 0;
+			ubifs_assert(lnum >= c->lpt_first &&
+				     lnum <= c->lpt_last);
+			err = ubifs_leb_unmap(c, lnum);
+			if (err)
+				return err;
+		}
+		done_ltab = 1;
+		ubifs_pack_ltab(c, buf + offs, c->ltab_cmt);
+		offs += c->ltab_sz;
+	}
+
+	/* Write remaining data in buffer */
+	wlen = offs - from;
+	alen = ALIGN(wlen, c->min_io_size);
+	memset(buf + offs, 0xff, alen - wlen);
+	err = ubifs_leb_write(c, lnum, buf + from, from, alen, UBI_SHORTTERM);
+	if (err)
+		return err;
+	c->nhead_lnum = lnum;
+	c->nhead_offs = ALIGN(offs, c->min_io_size);
+
+	dbg_lp("LPT root is at %d:%d", c->lpt_lnum, c->lpt_offs);
+	dbg_lp("LPT head is at %d:%d", c->nhead_lnum, c->nhead_offs);
+	dbg_lp("LPT ltab is at %d:%d", c->ltab_lnum, c->ltab_offs);
+	if (c->big_lpt)
+		dbg_lp("LPT lsave is at %d:%d", c->lsave_lnum, c->lsave_offs);
+	return 0;
+}
+
+/**
+ * next_pnode - find next pnode.
+ * @c: UBIFS file-system description object
+ * @pnode: pnode
+ *
+ * This function returns the next pnode or %NULL if there are no more pnodes.
+ */
+static struct ubifs_pnode *next_pnode(struct ubifs_info *c,
+				      struct ubifs_pnode *pnode)
+{
+	struct ubifs_nnode *nnode;
+	int iip;
+
+	/* Try to go right */
+	nnode = pnode->parent;
+	iip = pnode->iip + 1;
+	if (iip < UBIFS_LPT_FANOUT) {
+		/* We assume here that LEB zero is never an LPT LEB */
+		if (nnode->nbranch[iip].lnum)
+			return ubifs_get_pnode(c, nnode, iip);
+		else
+			return NULL;
+	}
+
+	/* Go up while can't go right */
+	do {
+		iip = nnode->iip + 1;
+		nnode = nnode->parent;
+		if (!nnode)
+			return NULL;
+		/* We assume here that LEB zero is never an LPT LEB */
+	} while (iip >= UBIFS_LPT_FANOUT || !nnode->nbranch[iip].lnum);
+
+	/* Go right */
+	nnode = ubifs_get_nnode(c, nnode, iip);
+	if (IS_ERR(nnode))
+		return (void *)nnode;
+
+	/* Go down to level 1 */
+	while (nnode->level > 1) {
+		nnode = ubifs_get_nnode(c, nnode, 0);
+		if (IS_ERR(nnode))
+			return (void *)nnode;
+	}
+
+	return ubifs_get_pnode(c, nnode, 0);
+}
+
+/**
+ * pnode_lookup - lookup a pnode in the LPT.
+ * @c: UBIFS file-system description object
+ * @i: pnode number (0 to main_lebs - 1)
+ *
+ * This function returns a pointer to the pnode on success or a negative
+ * error code on failure.
+ */
+static struct ubifs_pnode *pnode_lookup(struct ubifs_info *c, int i)
+{
+	int err, h, iip, shft;
+	struct ubifs_nnode *nnode;
+
+	if (!c->nroot) {
+		err = ubifs_read_nnode(c, NULL, 0);
+		if (err)
+			return ERR_PTR(err);
+	}
+	i <<= UBIFS_LPT_FANOUT_SHIFT;
+	nnode = c->nroot;
+	shft = c->lpt_hght * UBIFS_LPT_FANOUT_SHIFT;
+	for (h = 1; h < c->lpt_hght; h++) {
+		iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
+		shft -= UBIFS_LPT_FANOUT_SHIFT;
+		nnode = ubifs_get_nnode(c, nnode, iip);
+		if (IS_ERR(nnode))
+			return ERR_PTR(PTR_ERR(nnode));
+	}
+	iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
+	return ubifs_get_pnode(c, nnode, iip);
+}
+
+/**
+ * add_pnode_dirt - add dirty space to LPT LEB properties.
+ * @c: UBIFS file-system description object
+ * @pnode: pnode for which to add dirt
+ */
+static void add_pnode_dirt(struct ubifs_info *c, struct ubifs_pnode *pnode)
+{
+	ubifs_add_lpt_dirt(c, pnode->parent->nbranch[pnode->iip].lnum,
+			   c->pnode_sz);
+}
+
+/**
+ * do_make_pnode_dirty - mark a pnode dirty.
+ * @c: UBIFS file-system description object
+ * @pnode: pnode to mark dirty
+ */
+static void do_make_pnode_dirty(struct ubifs_info *c, struct ubifs_pnode *pnode)
+{
+	/* Assumes cnext list is empty i.e. not called during commit */
+	if (!test_and_set_bit(DIRTY_CNODE, &pnode->flags)) {
+		struct ubifs_nnode *nnode;
+
+		c->dirty_pn_cnt += 1;
+		add_pnode_dirt(c, pnode);
+		/* Mark parent and ancestors dirty too */
+		nnode = pnode->parent;
+		while (nnode) {
+			if (!test_and_set_bit(DIRTY_CNODE, &nnode->flags)) {
+				c->dirty_nn_cnt += 1;
+				ubifs_add_nnode_dirt(c, nnode);
+				nnode = nnode->parent;
+			} else
+				break;
+		}
+	}
+}
+
+/**
+ * make_tree_dirty - mark the entire LEB properties tree dirty.
+ * @c: UBIFS file-system description object
+ *
+ * This function is used by the "small" LPT model to cause the entire LEB
+ * properties tree to be written.  The "small" LPT model does not use LPT
+ * garbage collection because it is more efficient to write the entire tree
+ * (because it is small).
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int make_tree_dirty(struct ubifs_info *c)
+{
+	struct ubifs_pnode *pnode;
+
+	pnode = pnode_lookup(c, 0);
+	while (pnode) {
+		do_make_pnode_dirty(c, pnode);
+		pnode = next_pnode(c, pnode);
+		if (IS_ERR(pnode))
+			return PTR_ERR(pnode);
+	}
+	return 0;
+}
+
+/**
+ * need_write_all - determine if the LPT area is running out of free space.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns %1 if the LPT area is running out of free space and %0
+ * if it is not.
+ */
+static int need_write_all(struct ubifs_info *c)
+{
+	long long free = 0;
+	int i;
+
+	for (i = 0; i < c->lpt_lebs; i++) {
+		if (i + c->lpt_first == c->nhead_lnum)
+			free += c->leb_size - c->nhead_offs;
+		else if (c->ltab[i].free == c->leb_size)
+			free += c->leb_size;
+		else if (c->ltab[i].free + c->ltab[i].dirty == c->leb_size)
+			free += c->leb_size;
+	}
+	/* Less than twice the size left */
+	if (free <= c->lpt_sz * 2)
+		return 1;
+	return 0;
+}
+
+/**
+ * lpt_tgc_start - start trivial garbage collection of LPT LEBs.
+ * @c: UBIFS file-system description object
+ *
+ * LPT trivial garbage collection is where a LPT LEB contains only dirty and
+ * free space and so may be reused as soon as the next commit is completed.
+ * This function is called during start commit to mark LPT LEBs for trivial GC.
+ */
+static void lpt_tgc_start(struct ubifs_info *c)
+{
+	int i;
+
+	for (i = 0; i < c->lpt_lebs; i++) {
+		if (i + c->lpt_first == c->nhead_lnum)
+			continue;
+		if (c->ltab[i].dirty > 0 &&
+		    c->ltab[i].free + c->ltab[i].dirty == c->leb_size) {
+			c->ltab[i].tgc = 1;
+			c->ltab[i].free = c->leb_size;
+			c->ltab[i].dirty = 0;
+			dbg_lp("LEB %d", i + c->lpt_first);
+		}
+	}
+}
+
+/**
+ * lpt_tgc_end - end trivial garbage collection of LPT LEBs.
+ * @c: UBIFS file-system description object
+ *
+ * LPT trivial garbage collection is where a LPT LEB contains only dirty and
+ * free space and so may be reused as soon as the next commit is completed.
+ * This function is called after the commit is completed (master node has been
+ * written) and unmaps LPT LEBs that were marked for trivial GC.
+ */
+static int lpt_tgc_end(struct ubifs_info *c)
+{
+	int i, err;
+
+	for (i = 0; i < c->lpt_lebs; i++)
+		if (c->ltab[i].tgc) {
+			err = ubifs_leb_unmap(c, i + c->lpt_first);
+			if (err)
+				return err;
+			c->ltab[i].tgc = 0;
+			dbg_lp("LEB %d", i + c->lpt_first);
+		}
+	return 0;
+}
+
+/**
+ * populate_lsave - fill the lsave array with important LEB numbers.
+ * @c: the UBIFS file-system description object
+ *
+ * This function is only called for the "big" model. It records a small number
+ * of LEB numbers of important LEBs.  Important LEBs are ones that are (from
+ * most important to least important): empty, freeable, freeable index, dirty
+ * index, dirty or free. Upon mount, we read this list of LEB numbers and bring
+ * their pnodes into memory.  That will stop us from having to scan the LPT
+ * straight away. For the "small" model we assume that scanning the LPT is no
+ * big deal.
+ */
+static void populate_lsave(struct ubifs_info *c)
+{
+	struct ubifs_lprops *lprops;
+	struct ubifs_lpt_heap *heap;
+	int i, cnt = 0;
+
+	ubifs_assert(c->big_lpt);
+	if (!(c->lpt_drty_flgs & LSAVE_DIRTY)) {
+		c->lpt_drty_flgs |= LSAVE_DIRTY;
+		ubifs_add_lpt_dirt(c, c->lsave_lnum, c->lsave_sz);
+	}
+	list_for_each_entry(lprops, &c->empty_list, list) {
+		c->lsave[cnt++] = lprops->lnum;
+		if (cnt >= c->lsave_cnt)
+			return;
+	}
+	list_for_each_entry(lprops, &c->freeable_list, list) {
+		c->lsave[cnt++] = lprops->lnum;
+		if (cnt >= c->lsave_cnt)
+			return;
+	}
+	list_for_each_entry(lprops, &c->frdi_idx_list, list) {
+		c->lsave[cnt++] = lprops->lnum;
+		if (cnt >= c->lsave_cnt)
+			return;
+	}
+	heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
+	for (i = 0; i < heap->cnt; i++) {
+		c->lsave[cnt++] = heap->arr[i]->lnum;
+		if (cnt >= c->lsave_cnt)
+			return;
+	}
+	heap = &c->lpt_heap[LPROPS_DIRTY - 1];
+	for (i = 0; i < heap->cnt; i++) {
+		c->lsave[cnt++] = heap->arr[i]->lnum;
+		if (cnt >= c->lsave_cnt)
+			return;
+	}
+	heap = &c->lpt_heap[LPROPS_FREE - 1];
+	for (i = 0; i < heap->cnt; i++) {
+		c->lsave[cnt++] = heap->arr[i]->lnum;
+		if (cnt >= c->lsave_cnt)
+			return;
+	}
+	/* Fill it up completely */
+	while (cnt < c->lsave_cnt)
+		c->lsave[cnt++] = c->main_first;
+}
+
+/**
+ * ubifs_lpt_start_commit - UBIFS commit starts.
+ * @c: the UBIFS file-system description object
+ *
+ * This function has to be called when UBIFS starts the commit operation.
+ * This function "freezes" all currently dirty LEB properties and does not
+ * change them anymore. Further changes are saved and tracked separately
+ * because they are not part of this commit. This function returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+int ubifs_lpt_start_commit(struct ubifs_info *c)
+{
+	int err, cnt;
+
+	dbg_lp("");
+
+	mutex_lock(&c->lp_mutex);
+	err = dbg_check_ltab(c);
+	if (err)
+		goto out;
+
+	lpt_tgc_start(c);
+
+	if (!c->dirty_pn_cnt) {
+		dbg_cmt("no cnodes to commit");
+		err = 0;
+		goto out;
+	}
+
+	if (!c->big_lpt && need_write_all(c)) {
+		/* If needed, write everything */
+		err = make_tree_dirty(c);
+		if (err)
+			goto out;
+		lpt_tgc_start(c);
+	}
+
+	if (c->big_lpt)
+		populate_lsave(c);
+
+	cnt = get_cnodes_to_commit(c);
+	ubifs_assert(cnt != 0);
+
+	err = layout_cnodes(c);
+	if (err)
+		goto out;
+
+	/* Copy the LPT's own lprops for end commit to write */
+	memcpy(c->ltab_cmt, c->ltab,
+	       sizeof(struct ubifs_lpt_lprops) * c->lpt_lebs);
+	c->lpt_drty_flgs &= ~(LTAB_DIRTY | LSAVE_DIRTY);
+
+out:
+	mutex_unlock(&c->lp_mutex);
+	return err;
+}
+
+/**
+ * free_obsolete_cnodes - free obsolete cnodes for commit end.
+ * @c: UBIFS file-system description object
+ */
+static void free_obsolete_cnodes(struct ubifs_info *c)
+{
+	struct ubifs_cnode *cnode, *cnext;
+
+	cnext = c->lpt_cnext;
+	if (!cnext)
+		return;
+	do {
+		cnode = cnext;
+		cnext = cnode->cnext;
+		if (test_bit(OBSOLETE_CNODE, &cnode->flags))
+			kfree(cnode);
+		else
+			cnode->cnext = NULL;
+	} while (cnext != c->lpt_cnext);
+	c->lpt_cnext = NULL;
+}
+
+/**
+ * ubifs_lpt_end_commit - finish the commit operation.
+ * @c: the UBIFS file-system description object
+ *
+ * This function has to be called when the commit operation finishes. It
+ * flushes the changes which were "frozen" by 'ubifs_lprops_start_commit()' to
+ * the media. Returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+int ubifs_lpt_end_commit(struct ubifs_info *c)
+{
+	int err;
+
+	dbg_lp("");
+
+	if (!c->lpt_cnext)
+		return 0;
+
+	err = write_cnodes(c);
+	if (err)
+		return err;
+
+	mutex_lock(&c->lp_mutex);
+	free_obsolete_cnodes(c);
+	mutex_unlock(&c->lp_mutex);
+
+	return 0;
+}
+
+/**
+ * nnode_lookup - lookup a nnode in the LPT.
+ * @c: UBIFS file-system description object
+ * @i: nnode number
+ *
+ * This function returns a pointer to the nnode on success or a negative
+ * error code on failure.
+ */
+static struct ubifs_nnode *nnode_lookup(struct ubifs_info *c, int i)
+{
+	int err, iip;
+	struct ubifs_nnode *nnode;
+
+	if (!c->nroot) {
+		err = ubifs_read_nnode(c, NULL, 0);
+		if (err)
+			return ERR_PTR(err);
+	}
+	nnode = c->nroot;
+	while (1) {
+		iip = i & (UBIFS_LPT_FANOUT - 1);
+		i >>= UBIFS_LPT_FANOUT_SHIFT;
+		if (!i)
+			break;
+		nnode = ubifs_get_nnode(c, nnode, iip);
+		if (IS_ERR(nnode))
+			return nnode;
+	}
+	return nnode;
+}
+
+/**
+ * make_nnode_dirty - find a nnode and, if found, make it dirty.
+ * @c: UBIFS file-system description object
+ * @node_num: nnode number of nnode to make dirty
+ * @lnum: LEB number where nnode was written
+ * @offs: offset where nnode was written
+ *
+ * This function is used by LPT garbage collection.  LPT garbage collection is
+ * used only for the "big" LPT model (c->big_lpt == 1).  Garbage collection
+ * simply involves marking all the nodes in the LEB being garbage-collected as
+ * dirty.  The dirty nodes are written next commit, after which the LEB is free
+ * to be reused.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int make_nnode_dirty(struct ubifs_info *c, int node_num, int lnum,
+			    int offs)
+{
+	struct ubifs_nnode *nnode;
+
+	nnode = nnode_lookup(c, node_num);
+	if (IS_ERR(nnode))
+		return PTR_ERR(nnode);
+	if (nnode->parent) {
+		struct ubifs_nbranch *branch;
+
+		branch = &nnode->parent->nbranch[nnode->iip];
+		if (branch->lnum != lnum || branch->offs != offs)
+			return 0; /* nnode is obsolete */
+	} else if (c->lpt_lnum != lnum || c->lpt_offs != offs)
+			return 0; /* nnode is obsolete */
+	/* Assumes cnext list is empty i.e. not called during commit */
+	if (!test_and_set_bit(DIRTY_CNODE, &nnode->flags)) {
+		c->dirty_nn_cnt += 1;
+		ubifs_add_nnode_dirt(c, nnode);
+		/* Mark parent and ancestors dirty too */
+		nnode = nnode->parent;
+		while (nnode) {
+			if (!test_and_set_bit(DIRTY_CNODE, &nnode->flags)) {
+				c->dirty_nn_cnt += 1;
+				ubifs_add_nnode_dirt(c, nnode);
+				nnode = nnode->parent;
+			} else
+				break;
+		}
+	}
+	return 0;
+}
+
+/**
+ * make_pnode_dirty - find a pnode and, if found, make it dirty.
+ * @c: UBIFS file-system description object
+ * @node_num: pnode number of pnode to make dirty
+ * @lnum: LEB number where pnode was written
+ * @offs: offset where pnode was written
+ *
+ * This function is used by LPT garbage collection.  LPT garbage collection is
+ * used only for the "big" LPT model (c->big_lpt == 1).  Garbage collection
+ * simply involves marking all the nodes in the LEB being garbage-collected as
+ * dirty.  The dirty nodes are written next commit, after which the LEB is free
+ * to be reused.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int make_pnode_dirty(struct ubifs_info *c, int node_num, int lnum,
+			    int offs)
+{
+	struct ubifs_pnode *pnode;
+	struct ubifs_nbranch *branch;
+
+	pnode = pnode_lookup(c, node_num);
+	if (IS_ERR(pnode))
+		return PTR_ERR(pnode);
+	branch = &pnode->parent->nbranch[pnode->iip];
+	if (branch->lnum != lnum || branch->offs != offs)
+		return 0;
+	do_make_pnode_dirty(c, pnode);
+	return 0;
+}
+
+/**
+ * make_ltab_dirty - make ltab node dirty.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number where ltab was written
+ * @offs: offset where ltab was written
+ *
+ * This function is used by LPT garbage collection.  LPT garbage collection is
+ * used only for the "big" LPT model (c->big_lpt == 1).  Garbage collection
+ * simply involves marking all the nodes in the LEB being garbage-collected as
+ * dirty.  The dirty nodes are written next commit, after which the LEB is free
+ * to be reused.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int make_ltab_dirty(struct ubifs_info *c, int lnum, int offs)
+{
+	if (lnum != c->ltab_lnum || offs != c->ltab_offs)
+		return 0; /* This ltab node is obsolete */
+	if (!(c->lpt_drty_flgs & LTAB_DIRTY)) {
+		c->lpt_drty_flgs |= LTAB_DIRTY;
+		ubifs_add_lpt_dirt(c, c->ltab_lnum, c->ltab_sz);
+	}
+	return 0;
+}
+
+/**
+ * make_lsave_dirty - make lsave node dirty.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number where lsave was written
+ * @offs: offset where lsave was written
+ *
+ * This function is used by LPT garbage collection.  LPT garbage collection is
+ * used only for the "big" LPT model (c->big_lpt == 1).  Garbage collection
+ * simply involves marking all the nodes in the LEB being garbage-collected as
+ * dirty.  The dirty nodes are written next commit, after which the LEB is free
+ * to be reused.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int make_lsave_dirty(struct ubifs_info *c, int lnum, int offs)
+{
+	if (lnum != c->lsave_lnum || offs != c->lsave_offs)
+		return 0; /* This lsave node is obsolete */
+	if (!(c->lpt_drty_flgs & LSAVE_DIRTY)) {
+		c->lpt_drty_flgs |= LSAVE_DIRTY;
+		ubifs_add_lpt_dirt(c, c->lsave_lnum, c->lsave_sz);
+	}
+	return 0;
+}
+
+/**
+ * make_node_dirty - make node dirty.
+ * @c: UBIFS file-system description object
+ * @node_type: LPT node type
+ * @node_num: node number
+ * @lnum: LEB number where node was written
+ * @offs: offset where node was written
+ *
+ * This function is used by LPT garbage collection.  LPT garbage collection is
+ * used only for the "big" LPT model (c->big_lpt == 1).  Garbage collection
+ * simply involves marking all the nodes in the LEB being garbage-collected as
+ * dirty.  The dirty nodes are written next commit, after which the LEB is free
+ * to be reused.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int make_node_dirty(struct ubifs_info *c, int node_type, int node_num,
+			   int lnum, int offs)
+{
+	switch (node_type) {
+	case UBIFS_LPT_NNODE:
+		return make_nnode_dirty(c, node_num, lnum, offs);
+	case UBIFS_LPT_PNODE:
+		return make_pnode_dirty(c, node_num, lnum, offs);
+	case UBIFS_LPT_LTAB:
+		return make_ltab_dirty(c, lnum, offs);
+	case UBIFS_LPT_LSAVE:
+		return make_lsave_dirty(c, lnum, offs);
+	}
+	return -EINVAL;
+}
+
+/**
+ * get_lpt_node_len - return the length of a node based on its type.
+ * @c: UBIFS file-system description object
+ * @node_type: LPT node type
+ */
+static int get_lpt_node_len(struct ubifs_info *c, int node_type)
+{
+	switch (node_type) {
+	case UBIFS_LPT_NNODE:
+		return c->nnode_sz;
+	case UBIFS_LPT_PNODE:
+		return c->pnode_sz;
+	case UBIFS_LPT_LTAB:
+		return c->ltab_sz;
+	case UBIFS_LPT_LSAVE:
+		return c->lsave_sz;
+	}
+	return 0;
+}
+
+/**
+ * get_pad_len - return the length of padding in a buffer.
+ * @c: UBIFS file-system description object
+ * @buf: buffer
+ * @len: length of buffer
+ */
+static int get_pad_len(struct ubifs_info *c, uint8_t *buf, int len)
+{
+	int offs, pad_len;
+
+	if (c->min_io_size == 1)
+		return 0;
+	offs = c->leb_size - len;
+	pad_len = ALIGN(offs, c->min_io_size) - offs;
+	return pad_len;
+}
+
+/**
+ * get_lpt_node_type - return type (and node number) of a node in a buffer.
+ * @c: UBIFS file-system description object
+ * @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)
+{
+	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
+	int pos = 0, node_type;
+
+	node_type = ubifs_unpack_bits(&addr, &pos, UBIFS_LPT_TYPE_BITS);
+	*node_num = ubifs_unpack_bits(&addr, &pos, c->pcnt_bits);
+	return node_type;
+}
+
+/**
+ * is_a_node - determine if a buffer contains a node.
+ * @c: UBIFS file-system description object
+ * @buf: buffer
+ * @len: length of buffer
+ *
+ * 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)
+{
+	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
+	int pos = 0, node_type, node_len;
+	uint16_t crc, calc_crc;
+
+	node_type = ubifs_unpack_bits(&addr, &pos, UBIFS_LPT_TYPE_BITS);
+	if (node_type == UBIFS_LPT_NOT_A_NODE)
+		return 0;
+	node_len = get_lpt_node_len(c, node_type);
+	if (!node_len || node_len > len)
+		return 0;
+	pos = 0;
+	addr = buf;
+	crc = ubifs_unpack_bits(&addr, &pos, UBIFS_LPT_CRC_BITS);
+	calc_crc = crc16(-1, buf + UBIFS_LPT_CRC_BYTES,
+			 node_len - UBIFS_LPT_CRC_BYTES);
+	if (crc != calc_crc)
+		return 0;
+	return 1;
+}
+
+
+/**
+ * lpt_gc_lnum - garbage collect a LPT LEB.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number to garbage collect
+ *
+ * LPT garbage collection is used only for the "big" LPT model
+ * (c->big_lpt == 1).  Garbage collection simply involves marking all the nodes
+ * in the LEB being garbage-collected as dirty.  The dirty nodes are written
+ * next commit, after which the LEB is free to be reused.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int lpt_gc_lnum(struct ubifs_info *c, int lnum)
+{
+	int err, len = c->leb_size, node_type, node_num, node_len, offs;
+	void *buf = c->lpt_buf;
+
+	dbg_lp("LEB %d", lnum);
+	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
+	if (err) {
+		ubifs_err("cannot read LEB %d, error %d", lnum, err);
+		return err;
+	}
+	while (1) {
+		if (!is_a_node(c, buf, len)) {
+			int pad_len;
+
+			pad_len = get_pad_len(c, buf, len);
+			if (pad_len) {
+				buf += pad_len;
+				len -= pad_len;
+				continue;
+			}
+			return 0;
+		}
+		node_type = get_lpt_node_type(c, buf, &node_num);
+		node_len = get_lpt_node_len(c, node_type);
+		offs = c->leb_size - len;
+		ubifs_assert(node_len != 0);
+		mutex_lock(&c->lp_mutex);
+		err = make_node_dirty(c, node_type, node_num, lnum, offs);
+		mutex_unlock(&c->lp_mutex);
+		if (err)
+			return err;
+		buf += node_len;
+		len -= node_len;
+	}
+	return 0;
+}
+
+/**
+ * lpt_gc - LPT garbage collection.
+ * @c: UBIFS file-system description object
+ *
+ * Select a LPT LEB for LPT garbage collection and call 'lpt_gc_lnum()'.
+ * Returns %0 on success and a negative error code on failure.
+ */
+static int lpt_gc(struct ubifs_info *c)
+{
+	int i, lnum = -1, dirty = 0;
+
+	mutex_lock(&c->lp_mutex);
+	for (i = 0; i < c->lpt_lebs; i++) {
+		ubifs_assert(!c->ltab[i].tgc);
+		if (i + c->lpt_first == c->nhead_lnum ||
+		    c->ltab[i].free + c->ltab[i].dirty == c->leb_size)
+			continue;
+		if (c->ltab[i].dirty > dirty) {
+			dirty = c->ltab[i].dirty;
+			lnum = i + c->lpt_first;
+		}
+	}
+	mutex_unlock(&c->lp_mutex);
+	if (lnum == -1)
+		return -ENOSPC;
+	return lpt_gc_lnum(c, lnum);
+}
+
+/**
+ * ubifs_lpt_post_commit - post commit LPT trivial GC and LPT GC.
+ * @c: UBIFS file-system description object
+ *
+ * LPT trivial GC is completed after a commit. Also LPT GC is done after a
+ * commit for the "big" LPT model.
+ */
+int ubifs_lpt_post_commit(struct ubifs_info *c)
+{
+	int err;
+
+	mutex_lock(&c->lp_mutex);
+	err = lpt_tgc_end(c);
+	if (err)
+		goto out;
+	if (c->big_lpt)
+		while (need_write_all(c)) {
+			mutex_unlock(&c->lp_mutex);
+			err = lpt_gc(c);
+			if (err)
+				return err;
+			mutex_lock(&c->lp_mutex);
+		}
+out:
+	mutex_unlock(&c->lp_mutex);
+	return err;
+}
+
+/**
+ * first_nnode - find the first nnode in memory.
+ * @c: UBIFS file-system description object
+ * @hght: height of tree where nnode found is returned here
+ *
+ * This function returns a pointer to the nnode found or %NULL if no nnode is
+ * found. This function is a helper to 'ubifs_lpt_free()'.
+ */
+static struct ubifs_nnode *first_nnode(struct ubifs_info *c, int *hght)
+{
+	struct ubifs_nnode *nnode;
+	int h, i, found;
+
+	nnode = c->nroot;
+	*hght = 0;
+	if (!nnode)
+		return NULL;
+	for (h = 1; h < c->lpt_hght; h++) {
+		found = 0;
+		for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
+			if (nnode->nbranch[i].nnode) {
+				found = 1;
+				nnode = nnode->nbranch[i].nnode;
+				*hght = h;
+				break;
+			}
+		}
+		if (!found)
+			break;
+	}
+	return nnode;
+}
+
+/**
+ * next_nnode - find the next nnode in memory.
+ * @c: UBIFS file-system description object
+ * @nnode: nnode from which to start.
+ * @hght: height of tree where nnode is, is passed and returned here
+ *
+ * This function returns a pointer to the nnode found or %NULL if no nnode is
+ * found. This function is a helper to 'ubifs_lpt_free()'.
+ */
+static struct ubifs_nnode *next_nnode(struct ubifs_info *c,
+				      struct ubifs_nnode *nnode, int *hght)
+{
+	struct ubifs_nnode *parent;
+	int iip, h, i, found;
+
+	parent = nnode->parent;
+	if (!parent)
+		return NULL;
+	if (nnode->iip == UBIFS_LPT_FANOUT - 1) {
+		*hght -= 1;
+		return parent;
+	}
+	for (iip = nnode->iip + 1; iip < UBIFS_LPT_FANOUT; iip++) {
+		nnode = parent->nbranch[iip].nnode;
+		if (nnode)
+			break;
+	}
+	if (!nnode) {
+		*hght -= 1;
+		return parent;
+	}
+	for (h = *hght + 1; h < c->lpt_hght; h++) {
+		found = 0;
+		for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
+			if (nnode->nbranch[i].nnode) {
+				found = 1;
+				nnode = nnode->nbranch[i].nnode;
+				*hght = h;
+				break;
+			}
+		}
+		if (!found)
+			break;
+	}
+	return nnode;
+}
+
+/**
+ * ubifs_lpt_free - free resources owned by the LPT.
+ * @c: UBIFS file-system description object
+ * @wr_only: free only resources used for writing
+ */
+void ubifs_lpt_free(struct ubifs_info *c, int wr_only)
+{
+	struct ubifs_nnode *nnode;
+	int i, hght;
+
+	/* Free write-only things first */
+
+	free_obsolete_cnodes(c); /* Leftover from a failed commit */
+
+	vfree(c->ltab_cmt);
+	c->ltab_cmt = NULL;
+	vfree(c->lpt_buf);
+	c->lpt_buf = NULL;
+	kfree(c->lsave);
+	c->lsave = NULL;
+
+	if (wr_only)
+		return;
+
+	/* Now free the rest */
+
+	nnode = first_nnode(c, &hght);
+	while (nnode) {
+		for (i = 0; i < UBIFS_LPT_FANOUT; i++)
+			kfree(nnode->nbranch[i].nnode);
+		nnode = next_nnode(c, nnode, &hght);
+	}
+	for (i = 0; i < LPROPS_HEAP_CNT; i++)
+		kfree(c->lpt_heap[i].arr);
+	kfree(c->dirty_idx.arr);
+	kfree(c->nroot);
+	vfree(c->ltab);
+	kfree(c->lpt_nod_buf);
+}
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+
+/**
+ * dbg_is_all_ff - determine if a buffer contains only 0xff bytes.
+ * @buf: buffer
+ * @len: buffer length
+ */
+static int dbg_is_all_ff(uint8_t *buf, int len)
+{
+	int i;
+
+	for (i = 0; i < len; i++)
+		if (buf[i] != 0xff)
+			return 0;
+	return 1;
+}
+
+/**
+ * dbg_is_nnode_dirty - determine if a nnode is dirty.
+ * @c: the UBIFS file-system description object
+ * @lnum: LEB number where nnode was written
+ * @offs: offset where nnode was written
+ */
+static int dbg_is_nnode_dirty(struct ubifs_info *c, int lnum, int offs)
+{
+	struct ubifs_nnode *nnode;
+	int hght;
+
+	/* Entire tree is in memory so first_nnode / next_nnode are ok */
+	nnode = first_nnode(c, &hght);
+	for (; nnode; nnode = next_nnode(c, nnode, &hght)) {
+		struct ubifs_nbranch *branch;
+
+		cond_resched();
+		if (nnode->parent) {
+			branch = &nnode->parent->nbranch[nnode->iip];
+			if (branch->lnum != lnum || branch->offs != offs)
+				continue;
+			if (test_bit(DIRTY_CNODE, &nnode->flags))
+				return 1;
+			return 0;
+		} else {
+			if (c->lpt_lnum != lnum || c->lpt_offs != offs)
+				continue;
+			if (test_bit(DIRTY_CNODE, &nnode->flags))
+				return 1;
+			return 0;
+		}
+	}
+	return 1;
+}
+
+/**
+ * dbg_is_pnode_dirty - determine if a pnode is dirty.
+ * @c: the UBIFS file-system description object
+ * @lnum: LEB number where pnode was written
+ * @offs: offset where pnode was written
+ */
+static int dbg_is_pnode_dirty(struct ubifs_info *c, int lnum, int offs)
+{
+	int i, cnt;
+
+	cnt = DIV_ROUND_UP(c->main_lebs, UBIFS_LPT_FANOUT);
+	for (i = 0; i < cnt; i++) {
+		struct ubifs_pnode *pnode;
+		struct ubifs_nbranch *branch;
+
+		cond_resched();
+		pnode = pnode_lookup(c, i);
+		if (IS_ERR(pnode))
+			return PTR_ERR(pnode);
+		branch = &pnode->parent->nbranch[pnode->iip];
+		if (branch->lnum != lnum || branch->offs != offs)
+			continue;
+		if (test_bit(DIRTY_CNODE, &pnode->flags))
+			return 1;
+		return 0;
+	}
+	return 1;
+}
+
+/**
+ * dbg_is_ltab_dirty - determine if a ltab node is dirty.
+ * @c: the UBIFS file-system description object
+ * @lnum: LEB number where ltab node was written
+ * @offs: offset where ltab node was written
+ */
+static int dbg_is_ltab_dirty(struct ubifs_info *c, int lnum, int offs)
+{
+	if (lnum != c->ltab_lnum || offs != c->ltab_offs)
+		return 1;
+	return (c->lpt_drty_flgs & LTAB_DIRTY) != 0;
+}
+
+/**
+ * dbg_is_lsave_dirty - determine if a lsave node is dirty.
+ * @c: the UBIFS file-system description object
+ * @lnum: LEB number where lsave node was written
+ * @offs: offset where lsave node was written
+ */
+static int dbg_is_lsave_dirty(struct ubifs_info *c, int lnum, int offs)
+{
+	if (lnum != c->lsave_lnum || offs != c->lsave_offs)
+		return 1;
+	return (c->lpt_drty_flgs & LSAVE_DIRTY) != 0;
+}
+
+/**
+ * dbg_is_node_dirty - determine if a node is dirty.
+ * @c: the UBIFS file-system description object
+ * @node_type: node type
+ * @lnum: LEB number where node was written
+ * @offs: offset where node was written
+ */
+static int dbg_is_node_dirty(struct ubifs_info *c, int node_type, int lnum,
+			     int offs)
+{
+	switch (node_type) {
+	case UBIFS_LPT_NNODE:
+		return dbg_is_nnode_dirty(c, lnum, offs);
+	case UBIFS_LPT_PNODE:
+		return dbg_is_pnode_dirty(c, lnum, offs);
+	case UBIFS_LPT_LTAB:
+		return dbg_is_ltab_dirty(c, lnum, offs);
+	case UBIFS_LPT_LSAVE:
+		return dbg_is_lsave_dirty(c, lnum, offs);
+	}
+	return 1;
+}
+
+/**
+ * dbg_check_ltab_lnum - check the ltab for a LPT LEB number.
+ * @c: the UBIFS file-system description object
+ * @lnum: LEB number where node was written
+ * @offs: offset where node was written
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+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;
+
+	dbg_lp("LEB %d", lnum);
+	err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
+	if (err) {
+		dbg_msg("ubi_read failed, LEB %d, error %d", lnum, err);
+		return err;
+	}
+	while (1) {
+		if (!is_a_node(c, buf, len)) {
+			int i, pad_len;
+
+			pad_len = get_pad_len(c, buf, len);
+			if (pad_len) {
+				buf += pad_len;
+				len -= pad_len;
+				dirty += pad_len;
+				continue;
+			}
+			if (!dbg_is_all_ff(buf, len)) {
+				dbg_msg("invalid empty space in LEB %d at %d",
+					lnum, c->leb_size - len);
+				err = -EINVAL;
+			}
+			i = lnum - c->lpt_first;
+			if (len != c->ltab[i].free) {
+				dbg_msg("invalid free space in LEB %d "
+					"(free %d, expected %d)",
+					lnum, len, c->ltab[i].free);
+				err = -EINVAL;
+			}
+			if (dirty != c->ltab[i].dirty) {
+				dbg_msg("invalid dirty space in LEB %d "
+					"(dirty %d, expected %d)",
+					lnum, dirty, c->ltab[i].dirty);
+				err = -EINVAL;
+			}
+			return err;
+		}
+		node_type = get_lpt_node_type(c, buf, &node_num);
+		node_len = get_lpt_node_len(c, node_type);
+		ret = dbg_is_node_dirty(c, node_type, lnum, c->leb_size - len);
+		if (ret == 1)
+			dirty += node_len;
+		buf += node_len;
+		len -= node_len;
+	}
+}
+
+/**
+ * dbg_check_ltab - check the free and dirty space in the ltab.
+ * @c: the UBIFS file-system description object
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+int dbg_check_ltab(struct ubifs_info *c)
+{
+	int lnum, err, i, cnt;
+
+	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
+		return 0;
+
+	/* Bring the entire tree into memory */
+	cnt = DIV_ROUND_UP(c->main_lebs, UBIFS_LPT_FANOUT);
+	for (i = 0; i < cnt; i++) {
+		struct ubifs_pnode *pnode;
+
+		pnode = pnode_lookup(c, i);
+		if (IS_ERR(pnode))
+			return PTR_ERR(pnode);
+		cond_resched();
+	}
+
+	/* Check nodes */
+	err = dbg_check_lpt_nodes(c, (struct ubifs_cnode *)c->nroot, 0, 0);
+	if (err)
+		return err;
+
+	/* Check each LEB */
+	for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
+		err = dbg_check_ltab_lnum(c, lnum);
+		if (err) {
+			dbg_err("failed at LEB %d", lnum);
+			return err;
+		}
+	}
+
+	dbg_lp("succeeded");
+	return 0;
+}
+
+#endif /* CONFIG_UBIFS_FS_DEBUG */
-- 
1.5.4.1

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