1 files changed, 510 insertions, 37 deletions

diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 00c9cd31a01..fc0194aa267 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -3,18 +3,7 @@
  *
  * 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
+ * SPDX-License-Identifier:	GPL-2.0+
  *
  * Authors: Artem Bityutskiy (Битюцкий Артём)
  *          Adrian Hunter
@@ -27,6 +16,18 @@
  */
 
 #include "ubifs.h"
+#define __UBOOT__
+#ifndef __UBOOT__
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/math64.h>
+#else
+
+#include <linux/compat.h>
+#include <linux/err.h>
+#include <ubi_uboot.h>
+#include <linux/stat.h>
+#endif
 
 /*
  * Default journal size in logical eraseblocks as a percent of total
@@ -60,6 +61,282 @@
 /* Default time granularity in nanoseconds */
 #define DEFAULT_TIME_GRAN 1000000000
 
+#ifndef __UBOOT__
+/**
+ * create_default_filesystem - format empty UBI volume.
+ * @c: UBIFS file-system description object
+ *
+ * This function creates default empty file-system. Returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+static int create_default_filesystem(struct ubifs_info *c)
+{
+	struct ubifs_sb_node *sup;
+	struct ubifs_mst_node *mst;
+	struct ubifs_idx_node *idx;
+	struct ubifs_branch *br;
+	struct ubifs_ino_node *ino;
+	struct ubifs_cs_node *cs;
+	union ubifs_key key;
+	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;
+	long long tmp64, main_bytes;
+	__le64 tmp_le64;
+
+	/* Some functions called from here depend on the @c->key_len filed */
+	c->key_len = UBIFS_SK_LEN;
+
+	/*
+	 * First of all, we have to calculate default file-system geometry -
+	 * log size, journal size, etc.
+	 */
+	if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
+		/* We can first multiply then divide and have no overflow */
+		jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
+	else
+		jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
+
+	if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
+		jnl_lebs = UBIFS_MIN_JNL_LEBS;
+	if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
+		jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
+
+	/*
+	 * The log should be large enough to fit reference nodes for all bud
+	 * LEBs. Because buds do not have to start from the beginning of LEBs
+	 * (half of the LEB may contain committed data), the log should
+	 * generally be larger, make it twice as large.
+	 */
+	tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
+	log_lebs = tmp / c->leb_size;
+	/* Plus one LEB reserved for commit */
+	log_lebs += 1;
+	if (c->leb_cnt - min_leb_cnt > 8) {
+		/* And some extra space to allow writes while committing */
+		log_lebs += 1;
+		min_leb_cnt += 1;
+	}
+
+	max_buds = jnl_lebs - log_lebs;
+	if (max_buds < UBIFS_MIN_BUD_LEBS)
+		max_buds = UBIFS_MIN_BUD_LEBS;
+
+	/*
+	 * Orphan nodes are stored in a separate area. One node can store a lot
+	 * of orphan inode numbers, but when new orphan comes we just add a new
+	 * orphan node. At some point the nodes are consolidated into one
+	 * orphan node.
+	 */
+	orph_lebs = UBIFS_MIN_ORPH_LEBS;
+	if (c->leb_cnt - min_leb_cnt > 1)
+		/*
+		 * For debugging purposes it is better to have at least 2
+		 * orphan LEBs, because the orphan subsystem would need to do
+		 * consolidations and would be stressed more.
+		 */
+		orph_lebs += 1;
+
+	main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
+	main_lebs -= orph_lebs;
+
+	lpt_first = UBIFS_LOG_LNUM + log_lebs;
+	c->lsave_cnt = DEFAULT_LSAVE_CNT;
+	c->max_leb_cnt = c->leb_cnt;
+	err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
+				    &big_lpt);
+	if (err)
+		return err;
+
+	dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
+		lpt_first + lpt_lebs - 1);
+
+	main_first = c->leb_cnt - main_lebs;
+
+	/* Create default superblock */
+	tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
+	sup = kzalloc(tmp, GFP_KERNEL);
+	if (!sup)
+		return -ENOMEM;
+
+	tmp64 = (long long)max_buds * c->leb_size;
+	if (big_lpt)
+		sup_flags |= UBIFS_FLG_BIGLPT;
+
+	sup->ch.node_type  = UBIFS_SB_NODE;
+	sup->key_hash      = UBIFS_KEY_HASH_R5;
+	sup->flags         = cpu_to_le32(sup_flags);
+	sup->min_io_size   = cpu_to_le32(c->min_io_size);
+	sup->leb_size      = cpu_to_le32(c->leb_size);
+	sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
+	sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
+	sup->max_bud_bytes = cpu_to_le64(tmp64);
+	sup->log_lebs      = cpu_to_le32(log_lebs);
+	sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
+	sup->orph_lebs     = cpu_to_le32(orph_lebs);
+	sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
+	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->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 = (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);
+	sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
+
+	err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
+	kfree(sup);
+	if (err)
+		return err;
+
+	dbg_gen("default superblock created at LEB 0:0");
+
+	/* Create default master node */
+	mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
+	if (!mst)
+		return -ENOMEM;
+
+	mst->ch.node_type = UBIFS_MST_NODE;
+	mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
+	mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
+	mst->cmt_no       = 0;
+	mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
+	mst->root_offs    = 0;
+	tmp = ubifs_idx_node_sz(c, 1);
+	mst->root_len     = cpu_to_le32(tmp);
+	mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
+	mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
+	mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
+	mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
+	mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
+	mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
+	mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
+	mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
+	mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
+	mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
+	mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
+	mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
+	mst->lscan_lnum   = cpu_to_le32(main_first);
+	mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
+	mst->idx_lebs     = cpu_to_le32(1);
+	mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
+
+	/* Calculate lprops statistics */
+	tmp64 = main_bytes;
+	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
+	tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
+	mst->total_free = cpu_to_le64(tmp64);
+
+	tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
+	ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
+			  UBIFS_INO_NODE_SZ;
+	tmp64 += ino_waste;
+	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
+	mst->total_dirty = cpu_to_le64(tmp64);
+
+	/*  The indexing LEB does not contribute to dark space */
+	tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
+	mst->total_dark = cpu_to_le64(tmp64);
+
+	mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
+
+	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
+	if (err) {
+		kfree(mst);
+		return err;
+	}
+	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1,
+			       0);
+	kfree(mst);
+	if (err)
+		return err;
+
+	dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
+
+	/* Create the root indexing node */
+	tmp = ubifs_idx_node_sz(c, 1);
+	idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
+	if (!idx)
+		return -ENOMEM;
+
+	c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
+	c->key_hash = key_r5_hash;
+
+	idx->ch.node_type = UBIFS_IDX_NODE;
+	idx->child_cnt = cpu_to_le16(1);
+	ino_key_init(c, &key, UBIFS_ROOT_INO);
+	br = ubifs_idx_branch(c, idx, 0);
+	key_write_idx(c, &key, &br->key);
+	br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
+	br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
+	err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0);
+	kfree(idx);
+	if (err)
+		return err;
+
+	dbg_gen("default root indexing node created LEB %d:0",
+		main_first + DEFAULT_IDX_LEB);
+
+	/* Create default root inode */
+	tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
+	ino = kzalloc(tmp, GFP_KERNEL);
+	if (!ino)
+		return -ENOMEM;
+
+	ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
+	ino->ch.node_type = UBIFS_INO_NODE;
+	ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
+	ino->nlink = cpu_to_le32(2);
+	tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
+	ino->atime_sec   = tmp_le64;
+	ino->ctime_sec   = tmp_le64;
+	ino->mtime_sec   = tmp_le64;
+	ino->atime_nsec  = 0;
+	ino->ctime_nsec  = 0;
+	ino->mtime_nsec  = 0;
+	ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
+	ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
+
+	/* Set compression enabled by default */
+	ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
+
+	err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
+			       main_first + DEFAULT_DATA_LEB, 0);
+	kfree(ino);
+	if (err)
+		return err;
+
+	dbg_gen("root inode created at LEB %d:0",
+		main_first + DEFAULT_DATA_LEB);
+
+	/*
+	 * The first node in the log has to be the commit start node. This is
+	 * always the case during normal file-system operation. Write a fake
+	 * commit start node to the log.
+	 */
+	tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
+	cs = kzalloc(tmp, GFP_KERNEL);
+	if (!cs)
+		return -ENOMEM;
+
+	cs->ch.node_type = UBIFS_CS_NODE;
+	err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
+	kfree(cs);
+
+	ubifs_msg("default file-system created");
+	return 0;
+}
+#endif
+
 /**
  * validate_sb - validate superblock node.
  * @c: UBIFS file-system description object
@@ -114,9 +391,8 @@ static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
 	min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
 
 	if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
-		ubifs_err("bad LEB count: %d in superblock, %d on UBI volume, "
-			  "%d minimum required", c->leb_cnt, c->vi.size,
-			  min_leb_cnt);
+		ubifs_err("bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
+			  c->leb_cnt, c->vi.size, min_leb_cnt);
 		goto failed;
 	}
 
@@ -127,13 +403,22 @@ static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
 	}
 
 	if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
-		err = 7;
+		ubifs_err("too few main LEBs count %d, must be at least %d",
+			  c->main_lebs, UBIFS_MIN_MAIN_LEBS);
+		goto failed;
+	}
+
+	max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
+	if (c->max_bud_bytes < max_bytes) {
+		ubifs_err("too small journal (%lld bytes), must be at least %lld bytes",
+			  c->max_bud_bytes, max_bytes);
 		goto failed;
 	}
 
-	if (c->max_bud_bytes < (long long)c->leb_size * UBIFS_MIN_BUD_LEBS ||
-	    c->max_bud_bytes > (long long)c->leb_size * c->main_lebs) {
-		err = 8;
+	max_bytes = (long long)c->leb_size * c->main_lebs;
+	if (c->max_bud_bytes > max_bytes) {
+		ubifs_err("too large journal size (%lld bytes), only %lld bytes available in the main area",
+			  c->max_bud_bytes, max_bytes);
 		goto failed;
 	}
 
@@ -167,7 +452,6 @@ static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
 		goto failed;
 	}
 
-	max_bytes = c->main_lebs * (long long)c->leb_size;
 	if (c->rp_size < 0 || max_bytes < c->rp_size) {
 		err = 14;
 		goto failed;
@@ -183,7 +467,7 @@ static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
 
 failed:
 	ubifs_err("bad superblock, error %d", err);
-	dbg_dump_node(c, sup);
+	ubifs_dump_node(c, sup);
 	return -EINVAL;
 }
 
@@ -192,7 +476,8 @@ failed:
  * @c: UBIFS file-system description object
  *
  * This function returns a pointer to the superblock node or a negative error
- * code.
+ * code. Note, the user of this function is responsible of kfree()'ing the
+ * returned superblock buffer.
  */
 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
 {
@@ -214,6 +499,21 @@ struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
 }
 
 /**
+ * ubifs_write_sb_node - write superblock node.
+ * @c: UBIFS file-system description object
+ * @sup: superblock node read with 'ubifs_read_sb_node()'
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
+{
+	int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
+
+	ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
+	return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
+}
+
+/**
  * ubifs_read_superblock - read superblock.
  * @c: UBIFS file-system description object
  *
@@ -227,8 +527,14 @@ int ubifs_read_superblock(struct ubifs_info *c)
 	struct ubifs_sb_node *sup;
 
 	if (c->empty) {
+#ifndef __UBOOT__
+		err = create_default_filesystem(c);
+		if (err)
+			return err;
+#else
 		printf("No UBIFS filesystem found!\n");
 		return -1;
+#endif
 	}
 
 	sup = ubifs_read_sb_node(c);
@@ -243,16 +549,12 @@ int ubifs_read_superblock(struct ubifs_info *c)
 	 * due to the unavailability of time-travelling equipment.
 	 */
 	if (c->fmt_version > UBIFS_FORMAT_VERSION) {
-		struct super_block *sb = c->vfs_sb;
-		int mounting_ro = sb->s_flags & MS_RDONLY;
-
-		ubifs_assert(!c->ro_media || mounting_ro);
-		if (!mounting_ro ||
+		ubifs_assert(!c->ro_media || c->ro_mount);
+		if (!c->ro_mount ||
 		    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
-			ubifs_err("on-flash format version is w%d/r%d, but "
-				  "software only supports up to version "
-				  "w%d/r%d", c->fmt_version,
-				  c->ro_compat_version, UBIFS_FORMAT_VERSION,
+			ubifs_err("on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
+				  c->fmt_version, c->ro_compat_version,
+				  UBIFS_FORMAT_VERSION,
 				  UBIFS_RO_COMPAT_VERSION);
 			if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
 				ubifs_msg("only R/O mounting is possible");
@@ -310,22 +612,41 @@ 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);
+#ifndef __UBOOT__
+	c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
+	c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
+#else
+	c->rp_uid.val    = le32_to_cpu(sup->rp_uid);
+	c->rp_gid.val    = le32_to_cpu(sup->rp_gid);
+#endif
 	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);
+	c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
 
 	/* Automatically increase file system size to the maximum size */
 	c->old_leb_cnt = c->leb_cnt;
 	if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
 		c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
-		dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
-			c->old_leb_cnt,	c->leb_cnt);
+		if (c->ro_mount)
+			dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
+				c->old_leb_cnt,	c->leb_cnt);
+#ifndef __UBOOT__
+		else {
+			dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
+				c->old_leb_cnt, c->leb_cnt);
+			sup->leb_cnt = cpu_to_le32(c->leb_cnt);
+			err = ubifs_write_sb_node(c, sup);
+			if (err)
+				goto out;
+			c->old_leb_cnt = c->leb_cnt;
+		}
+#endif
 	}
 
 	c->log_bytes = (long long)c->log_lebs * c->leb_size;
@@ -337,10 +658,162 @@ int ubifs_read_superblock(struct ubifs_info *c)
 	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
 	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
 	c->main_first = c->leb_cnt - c->main_lebs;
-	c->report_rp_size = ubifs_reported_space(c, c->rp_size);
 
 	err = validate_sb(c, sup);
 out:
 	kfree(sup);
 	return err;
 }
+
+/**
+ * fixup_leb - fixup/unmap an LEB containing free space.
+ * @c: UBIFS file-system description object
+ * @lnum: the LEB number to fix up
+ * @len: number of used bytes in LEB (starting at offset 0)
+ *
+ * This function reads the contents of the given LEB number @lnum, then fixes
+ * it up, so that empty min. I/O units in the end of LEB are actually erased on
+ * flash (rather than being just all-0xff real data). If the LEB is completely
+ * empty, it is simply unmapped.
+ */
+static int fixup_leb(struct ubifs_info *c, int lnum, int len)
+{
+	int err;
+
+	ubifs_assert(len >= 0);
+	ubifs_assert(len % c->min_io_size == 0);
+	ubifs_assert(len < c->leb_size);
+
+	if (len == 0) {
+		dbg_mnt("unmap empty LEB %d", lnum);
+		return ubifs_leb_unmap(c, lnum);
+	}
+
+	dbg_mnt("fixup LEB %d, data len %d", lnum, len);
+	err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
+	if (err)
+		return err;
+
+	return ubifs_leb_change(c, lnum, c->sbuf, len);
+}
+
+/**
+ * fixup_free_space - find & remap all LEBs containing free space.
+ * @c: UBIFS file-system description object
+ *
+ * This function walks through all LEBs in the filesystem and fiexes up those
+ * containing free/empty space.
+ */
+static int fixup_free_space(struct ubifs_info *c)
+{
+	int lnum, err = 0;
+	struct ubifs_lprops *lprops;
+
+	ubifs_get_lprops(c);
+
+	/* Fixup LEBs in the master area */
+	for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
+		err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
+		if (err)
+			goto out;
+	}
+
+	/* Unmap unused log LEBs */
+	lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
+	while (lnum != c->ltail_lnum) {
+		err = fixup_leb(c, lnum, 0);
+		if (err)
+			goto out;
+		lnum = ubifs_next_log_lnum(c, lnum);
+	}
+
+	/*
+	 * Fixup the log head which contains the only a CS node at the
+	 * beginning.
+	 */
+	err = fixup_leb(c, c->lhead_lnum,
+			ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
+	if (err)
+		goto out;
+
+	/* Fixup LEBs in the LPT area */
+	for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
+		int free = c->ltab[lnum - c->lpt_first].free;
+
+		if (free > 0) {
+			err = fixup_leb(c, lnum, c->leb_size - free);
+			if (err)
+				goto out;
+		}
+	}
+
+	/* Unmap LEBs in the orphans area */
+	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
+		err = fixup_leb(c, lnum, 0);
+		if (err)
+			goto out;
+	}
+
+	/* Fixup LEBs in the main area */
+	for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
+		lprops = ubifs_lpt_lookup(c, lnum);
+		if (IS_ERR(lprops)) {
+			err = PTR_ERR(lprops);
+			goto out;
+		}
+
+		if (lprops->free > 0) {
+			err = fixup_leb(c, lnum, c->leb_size - lprops->free);
+			if (err)
+				goto out;
+		}
+	}
+
+out:
+	ubifs_release_lprops(c);
+	return err;
+}
+
+/**
+ * ubifs_fixup_free_space - find & fix all LEBs with free space.
+ * @c: UBIFS file-system description object
+ *
+ * This function fixes up LEBs containing free space on first mount, if the
+ * appropriate flag was set when the FS was created. Each LEB with one or more
+ * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
+ * the free space is actually erased. E.g., this is necessary for some NAND
+ * chips, since the free space may have been programmed like real "0xff" data
+ * (generating a non-0xff ECC), causing future writes to the not-really-erased
+ * NAND pages to behave badly. After the space is fixed up, the superblock flag
+ * is cleared, so that this is skipped for all future mounts.
+ */
+int ubifs_fixup_free_space(struct ubifs_info *c)
+{
+	int err;
+	struct ubifs_sb_node *sup;
+
+	ubifs_assert(c->space_fixup);
+	ubifs_assert(!c->ro_mount);
+
+	ubifs_msg("start fixing up free space");
+
+	err = fixup_free_space(c);
+	if (err)
+		return err;
+
+	sup = ubifs_read_sb_node(c);
+	if (IS_ERR(sup))
+		return PTR_ERR(sup);
+
+	/* Free-space fixup is no longer required */
+	c->space_fixup = 0;
+	sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
+
+	err = ubifs_write_sb_node(c, sup);
+	kfree(sup);
+	if (err)
+		return err;
+
+	ubifs_msg("free space fixup complete");
+	return err;
+}