UBIFS: Implement read-only UBIFS support in U-Boot

The U-Boot UBIFS implementation is largely a direct copy from the current
Linux version (2.6.29-rc6). As already done in the UBI version we have an
"abstraction layer" to redefine or remove some OS calls (e.g. mutex_lock()
...). This makes it possible to use the original Linux code with very
little changes. And by this we can better update to later Linux versions.

I removed some of the Linux features that are not used in the U-Boot
version (e.g. garbage-collection, write support).

Signed-off-by: Stefan Roese <sr@denx.de>
CC: Artem Bityutskiy <dedekind@infradead.org>
CC: Adrian Hunter <ext-Adrian.Hunter@nokia.com>

1 files changed, 1070 insertions, 0 deletions

diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
new file mode 100644
index 0000000000..da33a14ab6
--- /dev/null
+++ b/fs/ubifs/replay.c
@@ -0,0 +1,1070 @@
+/*
+ * 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 contains journal replay code. It runs when the file-system is being
+ * mounted and requires no locking.
+ *
+ * The larger is the journal, the longer it takes to scan it, so the longer it
+ * takes to mount UBIFS. This is why the journal has limited size which may be
+ * changed depending on the system requirements. But a larger journal gives
+ * faster I/O speed because it writes the index less frequently. So this is a
+ * trade-off. Also, the journal is indexed by the in-memory index (TNC), so the
+ * larger is the journal, the more memory its index may consume.
+ */
+
+#include "ubifs.h"
+
+/*
+ * Replay flags.
+ *
+ * REPLAY_DELETION: node was deleted
+ * REPLAY_REF: node is a reference node
+ */
+enum {
+	REPLAY_DELETION = 1,
+	REPLAY_REF = 2,
+};
+
+/**
+ * struct replay_entry - replay tree entry.
+ * @lnum: logical eraseblock number of the node
+ * @offs: node offset
+ * @len: node length
+ * @sqnum: node sequence number
+ * @flags: replay flags
+ * @rb: links the replay tree
+ * @key: node key
+ * @nm: directory entry name
+ * @old_size: truncation old size
+ * @new_size: truncation new size
+ * @free: amount of free space in a bud
+ * @dirty: amount of dirty space in a bud from padding and deletion nodes
+ *
+ * UBIFS journal replay must compare node sequence numbers, which means it must
+ * build a tree of node information to insert into the TNC.
+ */
+struct replay_entry {
+	int lnum;
+	int offs;
+	int len;
+	unsigned long long sqnum;
+	int flags;
+	struct rb_node rb;
+	union ubifs_key key;
+	union {
+		struct qstr nm;
+		struct {
+			loff_t old_size;
+			loff_t new_size;
+		};
+		struct {
+			int free;
+			int dirty;
+		};
+	};
+};
+
+/**
+ * struct bud_entry - entry in the list of buds to replay.
+ * @list: next bud in the list
+ * @bud: bud description object
+ * @free: free bytes in the bud
+ * @sqnum: reference node sequence number
+ */
+struct bud_entry {
+	struct list_head list;
+	struct ubifs_bud *bud;
+	int free;
+	unsigned long long sqnum;
+};
+
+/**
+ * set_bud_lprops - set free and dirty space used by a bud.
+ * @c: UBIFS file-system description object
+ * @r: replay entry of bud
+ */
+static int set_bud_lprops(struct ubifs_info *c, struct replay_entry *r)
+{
+	const struct ubifs_lprops *lp;
+	int err = 0, dirty;
+
+	ubifs_get_lprops(c);
+
+	lp = ubifs_lpt_lookup_dirty(c, r->lnum);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	dirty = lp->dirty;
+	if (r->offs == 0 && (lp->free != c->leb_size || lp->dirty != 0)) {
+		/*
+		 * The LEB was added to the journal with a starting offset of
+		 * zero which means the LEB must have been empty. The LEB
+		 * property values should be lp->free == c->leb_size and
+		 * lp->dirty == 0, but that is not the case. The reason is that
+		 * the LEB was garbage collected. The garbage collector resets
+		 * the free and dirty space without recording it anywhere except
+		 * lprops, so if there is not a commit then lprops does not have
+		 * that information next time the file system is mounted.
+		 *
+		 * We do not need to adjust free space because the scan has told
+		 * us the exact value which is recorded in the replay entry as
+		 * r->free.
+		 *
+		 * However we do need to subtract from the dirty space the
+		 * amount of space that the garbage collector reclaimed, which
+		 * is the whole LEB minus the amount of space that was free.
+		 */
+		dbg_mnt("bud LEB %d was GC'd (%d free, %d dirty)", r->lnum,
+			lp->free, lp->dirty);
+		dbg_gc("bud LEB %d was GC'd (%d free, %d dirty)", r->lnum,
+			lp->free, lp->dirty);
+		dirty -= c->leb_size - lp->free;
+		/*
+		 * If the replay order was perfect the dirty space would now be
+		 * zero. The order is not perfect because the the journal heads
+		 * race with each other. This is not a problem but is does mean
+		 * that the dirty space may temporarily exceed c->leb_size
+		 * during the replay.
+		 */
+		if (dirty != 0)
+			dbg_msg("LEB %d lp: %d free %d dirty "
+				"replay: %d free %d dirty", r->lnum, lp->free,
+				lp->dirty, r->free, r->dirty);
+	}
+	lp = ubifs_change_lp(c, lp, r->free, dirty + r->dirty,
+			     lp->flags | LPROPS_TAKEN, 0);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+out:
+	ubifs_release_lprops(c);
+	return err;
+}
+
+/**
+ * trun_remove_range - apply a replay entry for a truncation to the TNC.
+ * @c: UBIFS file-system description object
+ * @r: replay entry of truncation
+ */
+static int trun_remove_range(struct ubifs_info *c, struct replay_entry *r)
+{
+	unsigned min_blk, max_blk;
+	union ubifs_key min_key, max_key;
+	ino_t ino;
+
+	min_blk = r->new_size / UBIFS_BLOCK_SIZE;
+	if (r->new_size & (UBIFS_BLOCK_SIZE - 1))
+		min_blk += 1;
+
+	max_blk = r->old_size / UBIFS_BLOCK_SIZE;
+	if ((r->old_size & (UBIFS_BLOCK_SIZE - 1)) == 0)
+		max_blk -= 1;
+
+	ino = key_inum(c, &r->key);
+
+	data_key_init(c, &min_key, ino, min_blk);
+	data_key_init(c, &max_key, ino, max_blk);
+
+	return ubifs_tnc_remove_range(c, &min_key, &max_key);
+}
+
+/**
+ * apply_replay_entry - apply a replay entry to the TNC.
+ * @c: UBIFS file-system description object
+ * @r: replay entry to apply
+ *
+ * Apply a replay entry to the TNC.
+ */
+static int apply_replay_entry(struct ubifs_info *c, struct replay_entry *r)
+{
+	int err, deletion = ((r->flags & REPLAY_DELETION) != 0);
+
+	dbg_mnt("LEB %d:%d len %d flgs %d sqnum %llu %s", r->lnum,
+		r->offs, r->len, r->flags, r->sqnum, DBGKEY(&r->key));
+
+	/* Set c->replay_sqnum to help deal with dangling branches. */
+	c->replay_sqnum = r->sqnum;
+
+	if (r->flags & REPLAY_REF)
+		err = set_bud_lprops(c, r);
+	else if (is_hash_key(c, &r->key)) {
+		if (deletion)
+			err = ubifs_tnc_remove_nm(c, &r->key, &r->nm);
+		else
+			err = ubifs_tnc_add_nm(c, &r->key, r->lnum, r->offs,
+					       r->len, &r->nm);
+	} else {
+		if (deletion)
+			switch (key_type(c, &r->key)) {
+			case UBIFS_INO_KEY:
+			{
+				ino_t inum = key_inum(c, &r->key);
+
+				err = ubifs_tnc_remove_ino(c, inum);
+				break;
+			}
+			case UBIFS_TRUN_KEY:
+				err = trun_remove_range(c, r);
+				break;
+			default:
+				err = ubifs_tnc_remove(c, &r->key);
+				break;
+			}
+		else
+			err = ubifs_tnc_add(c, &r->key, r->lnum, r->offs,
+					    r->len);
+		if (err)
+			return err;
+
+		if (c->need_recovery)
+			err = ubifs_recover_size_accum(c, &r->key, deletion,
+						       r->new_size);
+	}
+
+	return err;
+}
+
+/**
+ * destroy_replay_tree - destroy the replay.
+ * @c: UBIFS file-system description object
+ *
+ * Destroy the replay tree.
+ */
+static void destroy_replay_tree(struct ubifs_info *c)
+{
+	struct rb_node *this = c->replay_tree.rb_node;
+	struct replay_entry *r;
+
+	while (this) {
+		if (this->rb_left) {
+			this = this->rb_left;
+			continue;
+		} else if (this->rb_right) {
+			this = this->rb_right;
+			continue;
+		}
+		r = rb_entry(this, struct replay_entry, rb);
+		this = rb_parent(this);
+		if (this) {
+			if (this->rb_left == &r->rb)
+				this->rb_left = NULL;
+			else
+				this->rb_right = NULL;
+		}
+		if (is_hash_key(c, &r->key))
+			kfree((void *)r->nm.name);
+		kfree(r);
+	}
+	c->replay_tree = RB_ROOT;
+}
+
+/**
+ * apply_replay_tree - apply the replay tree to the TNC.
+ * @c: UBIFS file-system description object
+ *
+ * Apply the replay tree.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int apply_replay_tree(struct ubifs_info *c)
+{
+	struct rb_node *this = rb_first(&c->replay_tree);
+
+	while (this) {
+		struct replay_entry *r;
+		int err;
+
+		cond_resched();
+
+		r = rb_entry(this, struct replay_entry, rb);
+		err = apply_replay_entry(c, r);
+		if (err)
+			return err;
+		this = rb_next(this);
+	}
+	return 0;
+}
+
+/**
+ * insert_node - insert a node to the replay tree.
+ * @c: UBIFS file-system description object
+ * @lnum: node logical eraseblock number
+ * @offs: node offset
+ * @len: node length
+ * @key: node key
+ * @sqnum: sequence number
+ * @deletion: non-zero if this is a deletion
+ * @used: number of bytes in use in a LEB
+ * @old_size: truncation old size
+ * @new_size: truncation new size
+ *
+ * This function inserts a scanned non-direntry node to the replay tree. The
+ * replay tree is an RB-tree containing @struct replay_entry elements which are
+ * indexed by the sequence number. The replay tree is applied at the very end
+ * of the replay process. Since the tree is sorted in sequence number order,
+ * the older modifications are applied first. This function returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+static int insert_node(struct ubifs_info *c, int lnum, int offs, int len,
+		       union ubifs_key *key, unsigned long long sqnum,
+		       int deletion, int *used, loff_t old_size,
+		       loff_t new_size)
+{
+	struct rb_node **p = &c->replay_tree.rb_node, *parent = NULL;
+	struct replay_entry *r;
+
+	if (key_inum(c, key) >= c->highest_inum)
+		c->highest_inum = key_inum(c, key);
+
+	dbg_mnt("add LEB %d:%d, key %s", lnum, offs, DBGKEY(key));
+	while (*p) {
+		parent = *p;
+		r = rb_entry(parent, struct replay_entry, rb);
+		if (sqnum < r->sqnum) {
+			p = &(*p)->rb_left;
+			continue;
+		} else if (sqnum > r->sqnum) {
+			p = &(*p)->rb_right;
+			continue;
+		}
+		ubifs_err("duplicate sqnum in replay");
+		return -EINVAL;
+	}
+
+	r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	if (!deletion)
+		*used += ALIGN(len, 8);
+	r->lnum = lnum;
+	r->offs = offs;
+	r->len = len;
+	r->sqnum = sqnum;
+	r->flags = (deletion ? REPLAY_DELETION : 0);
+	r->old_size = old_size;
+	r->new_size = new_size;
+	key_copy(c, key, &r->key);
+
+	rb_link_node(&r->rb, parent, p);
+	rb_insert_color(&r->rb, &c->replay_tree);
+	return 0;
+}
+
+/**
+ * insert_dent - insert a directory entry node into the replay tree.
+ * @c: UBIFS file-system description object
+ * @lnum: node logical eraseblock number
+ * @offs: node offset
+ * @len: node length
+ * @key: node key
+ * @name: directory entry name
+ * @nlen: directory entry name length
+ * @sqnum: sequence number
+ * @deletion: non-zero if this is a deletion
+ * @used: number of bytes in use in a LEB
+ *
+ * This function inserts a scanned directory entry node to the replay tree.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ *
+ * This function is also used for extended attribute entries because they are
+ * implemented as directory entry nodes.
+ */
+static int insert_dent(struct ubifs_info *c, int lnum, int offs, int len,
+		       union ubifs_key *key, const char *name, int nlen,
+		       unsigned long long sqnum, int deletion, int *used)
+{
+	struct rb_node **p = &c->replay_tree.rb_node, *parent = NULL;
+	struct replay_entry *r;
+	char *nbuf;
+
+	if (key_inum(c, key) >= c->highest_inum)
+		c->highest_inum = key_inum(c, key);
+
+	dbg_mnt("add LEB %d:%d, key %s", lnum, offs, DBGKEY(key));
+	while (*p) {
+		parent = *p;
+		r = rb_entry(parent, struct replay_entry, rb);
+		if (sqnum < r->sqnum) {
+			p = &(*p)->rb_left;
+			continue;
+		}
+		if (sqnum > r->sqnum) {
+			p = &(*p)->rb_right;
+			continue;
+		}
+		ubifs_err("duplicate sqnum in replay");
+		return -EINVAL;
+	}
+
+	r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+	nbuf = kmalloc(nlen + 1, GFP_KERNEL);
+	if (!nbuf) {
+		kfree(r);
+		return -ENOMEM;
+	}
+
+	if (!deletion)
+		*used += ALIGN(len, 8);
+	r->lnum = lnum;
+	r->offs = offs;
+	r->len = len;
+	r->sqnum = sqnum;
+	r->nm.len = nlen;
+	memcpy(nbuf, name, nlen);
+	nbuf[nlen] = '\0';
+	r->nm.name = nbuf;
+	r->flags = (deletion ? REPLAY_DELETION : 0);
+	key_copy(c, key, &r->key);
+
+	ubifs_assert(!*p);
+	rb_link_node(&r->rb, parent, p);
+	rb_insert_color(&r->rb, &c->replay_tree);
+	return 0;
+}
+
+/**
+ * ubifs_validate_entry - validate directory or extended attribute entry node.
+ * @c: UBIFS file-system description object
+ * @dent: the node to validate
+ *
+ * This function validates directory or extended attribute entry node @dent.
+ * Returns zero if the node is all right and a %-EINVAL if not.
+ */
+int ubifs_validate_entry(struct ubifs_info *c,
+			 const struct ubifs_dent_node *dent)
+{
+	int key_type = key_type_flash(c, dent->key);
+	int nlen = le16_to_cpu(dent->nlen);
+
+	if (le32_to_cpu(dent->ch.len) != nlen + UBIFS_DENT_NODE_SZ + 1 ||
+	    dent->type >= UBIFS_ITYPES_CNT ||
+	    nlen > UBIFS_MAX_NLEN || dent->name[nlen] != 0 ||
+	    strnlen((char *)dent->name, nlen) != nlen ||
+	    le64_to_cpu(dent->inum) > MAX_INUM) {
+		ubifs_err("bad %s node", key_type == UBIFS_DENT_KEY ?
+			  "directory entry" : "extended attribute entry");
+		return -EINVAL;
+	}
+
+	if (key_type != UBIFS_DENT_KEY && key_type != UBIFS_XENT_KEY) {
+		ubifs_err("bad key type %d", key_type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * replay_bud - replay a bud logical eraseblock.
+ * @c: UBIFS file-system description object
+ * @lnum: bud logical eraseblock number to replay
+ * @offs: bud start offset
+ * @jhead: journal head to which this bud belongs
+ * @free: amount of free space in the bud is returned here
+ * @dirty: amount of dirty space from padding and deletion nodes is returned
+ * here
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
+		      int *free, int *dirty)
+{
+	int err = 0, used = 0;
+	struct ubifs_scan_leb *sleb;
+	struct ubifs_scan_node *snod;
+	struct ubifs_bud *bud;
+
+	dbg_mnt("replay bud LEB %d, head %d", lnum, jhead);
+	if (c->need_recovery)
+		sleb = ubifs_recover_leb(c, lnum, offs, c->sbuf, jhead != GCHD);
+	else
+		sleb = ubifs_scan(c, lnum, offs, c->sbuf);
+	if (IS_ERR(sleb))
+		return PTR_ERR(sleb);
+
+	/*
+	 * The bud does not have to start from offset zero - the beginning of
+	 * the 'lnum' LEB may contain previously committed data. One of the
+	 * things we have to do in replay is to correctly update lprops with
+	 * newer information about this LEB.
+	 *
+	 * At this point lprops thinks that this LEB has 'c->leb_size - offs'
+	 * bytes of free space because it only contain information about
+	 * committed data.
+	 *
+	 * But we know that real amount of free space is 'c->leb_size -
+	 * sleb->endpt', and the space in the 'lnum' LEB between 'offs' and
+	 * 'sleb->endpt' is used by bud data. We have to correctly calculate
+	 * how much of these data are dirty and update lprops with this
+	 * information.
+	 *
+	 * The dirt in that LEB region is comprised of padding nodes, deletion
+	 * nodes, truncation nodes and nodes which are obsoleted by subsequent
+	 * nodes in this LEB. So instead of calculating clean space, we
+	 * calculate used space ('used' variable).
+	 */
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+		int deletion = 0;
+
+		cond_resched();
+
+		if (snod->sqnum >= SQNUM_WATERMARK) {
+			ubifs_err("file system's life ended");
+			goto out_dump;
+		}
+
+		if (snod->sqnum > c->max_sqnum)
+			c->max_sqnum = snod->sqnum;
+
+		switch (snod->type) {
+		case UBIFS_INO_NODE:
+		{
+			struct ubifs_ino_node *ino = snod->node;
+			loff_t new_size = le64_to_cpu(ino->size);
+
+			if (le32_to_cpu(ino->nlink) == 0)
+				deletion = 1;
+			err = insert_node(c, lnum, snod->offs, snod->len,
+					  &snod->key, snod->sqnum, deletion,
+					  &used, 0, new_size);
+			break;
+		}
+		case UBIFS_DATA_NODE:
+		{
+			struct ubifs_data_node *dn = snod->node;
+			loff_t new_size = le32_to_cpu(dn->size) +
+					  key_block(c, &snod->key) *
+					  UBIFS_BLOCK_SIZE;
+
+			err = insert_node(c, lnum, snod->offs, snod->len,
+					  &snod->key, snod->sqnum, deletion,
+					  &used, 0, new_size);
+			break;
+		}
+		case UBIFS_DENT_NODE:
+		case UBIFS_XENT_NODE:
+		{
+			struct ubifs_dent_node *dent = snod->node;
+
+			err = ubifs_validate_entry(c, dent);
+			if (err)
+				goto out_dump;
+
+			err = insert_dent(c, lnum, snod->offs, snod->len,
+					  &snod->key, (char *)dent->name,
+					  le16_to_cpu(dent->nlen), snod->sqnum,
+					  !le64_to_cpu(dent->inum), &used);
+			break;
+		}
+		case UBIFS_TRUN_NODE:
+		{
+			struct ubifs_trun_node *trun = snod->node;
+			loff_t old_size = le64_to_cpu(trun->old_size);
+			loff_t new_size = le64_to_cpu(trun->new_size);
+			union ubifs_key key;
+
+			/* Validate truncation node */
+			if (old_size < 0 || old_size > c->max_inode_sz ||
+			    new_size < 0 || new_size > c->max_inode_sz ||
+			    old_size <= new_size) {
+				ubifs_err("bad truncation node");
+				goto out_dump;
+			}
+
+			/*
+			 * Create a fake truncation key just to use the same
+			 * functions which expect nodes to have keys.
+			 */
+			trun_key_init(c, &key, le32_to_cpu(trun->inum));
+			err = insert_node(c, lnum, snod->offs, snod->len,
+					  &key, snod->sqnum, 1, &used,
+					  old_size, new_size);
+			break;
+		}
+		default:
+			ubifs_err("unexpected node type %d in bud LEB %d:%d",
+				  snod->type, lnum, snod->offs);
+			err = -EINVAL;
+			goto out_dump;
+		}
+		if (err)
+			goto out;
+	}
+
+	bud = ubifs_search_bud(c, lnum);
+	if (!bud)
+		BUG();
+
+	ubifs_assert(sleb->endpt - offs >= used);
+	ubifs_assert(sleb->endpt % c->min_io_size == 0);
+
+	*dirty = sleb->endpt - offs - used;
+	*free = c->leb_size - sleb->endpt;
+
+out:
+	ubifs_scan_destroy(sleb);
+	return err;
+
+out_dump:
+	ubifs_err("bad node is at LEB %d:%d", lnum, snod->offs);
+	dbg_dump_node(c, snod->node);
+	ubifs_scan_destroy(sleb);
+	return -EINVAL;
+}
+
+/**
+ * insert_ref_node - insert a reference node to the replay tree.
+ * @c: UBIFS file-system description object
+ * @lnum: node logical eraseblock number
+ * @offs: node offset
+ * @sqnum: sequence number
+ * @free: amount of free space in bud
+ * @dirty: amount of dirty space from padding and deletion nodes
+ *
+ * This function inserts a reference node to the replay tree and returns zero
+ * in case of success or a negative error code in case of failure.
+ */
+static int insert_ref_node(struct ubifs_info *c, int lnum, int offs,
+			   unsigned long long sqnum, int free, int dirty)
+{
+	struct rb_node **p = &c->replay_tree.rb_node, *parent = NULL;
+	struct replay_entry *r;
+
+	dbg_mnt("add ref LEB %d:%d", lnum, offs);
+	while (*p) {
+		parent = *p;
+		r = rb_entry(parent, struct replay_entry, rb);
+		if (sqnum < r->sqnum) {
+			p = &(*p)->rb_left;
+			continue;
+		} else if (sqnum > r->sqnum) {
+			p = &(*p)->rb_right;
+			continue;
+		}
+		ubifs_err("duplicate sqnum in replay tree");
+		return -EINVAL;
+	}
+
+	r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	r->lnum = lnum;
+	r->offs = offs;
+	r->sqnum = sqnum;
+	r->flags = REPLAY_REF;
+	r->free = free;
+	r->dirty = dirty;
+
+	rb_link_node(&r->rb, parent, p);
+	rb_insert_color(&r->rb, &c->replay_tree);
+	return 0;
+}
+
+/**
+ * replay_buds - replay all buds.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int replay_buds(struct ubifs_info *c)
+{
+	struct bud_entry *b;
+	int err, uninitialized_var(free), uninitialized_var(dirty);
+
+	list_for_each_entry(b, &c->replay_buds, list) {
+		err = replay_bud(c, b->bud->lnum, b->bud->start, b->bud->jhead,
+				 &free, &dirty);
+		if (err)
+			return err;
+		err = insert_ref_node(c, b->bud->lnum, b->bud->start, b->sqnum,
+				      free, dirty);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * destroy_bud_list - destroy the list of buds to replay.
+ * @c: UBIFS file-system description object
+ */
+static void destroy_bud_list(struct ubifs_info *c)
+{
+	struct bud_entry *b;
+
+	while (!list_empty(&c->replay_buds)) {
+		b = list_entry(c->replay_buds.next, struct bud_entry, list);
+		list_del(&b->list);
+		kfree(b);
+	}
+}
+
+/**
+ * add_replay_bud - add a bud to the list of buds to replay.
+ * @c: UBIFS file-system description object
+ * @lnum: bud logical eraseblock number to replay
+ * @offs: bud start offset
+ * @jhead: journal head to which this bud belongs
+ * @sqnum: reference node sequence number
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int add_replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
+			  unsigned long long sqnum)
+{
+	struct ubifs_bud *bud;
+	struct bud_entry *b;
+
+	dbg_mnt("add replay bud LEB %d:%d, head %d", lnum, offs, jhead);
+
+	bud = kmalloc(sizeof(struct ubifs_bud), GFP_KERNEL);
+	if (!bud)
+		return -ENOMEM;
+
+	b = kmalloc(sizeof(struct bud_entry), GFP_KERNEL);
+	if (!b) {
+		kfree(bud);
+		return -ENOMEM;
+	}
+
+	bud->lnum = lnum;
+	bud->start = offs;
+	bud->jhead = jhead;
+	ubifs_add_bud(c, bud);
+
+	b->bud = bud;
+	b->sqnum = sqnum;
+	list_add_tail(&b->list, &c->replay_buds);
+
+	return 0;
+}
+
+/**
+ * validate_ref - validate a reference node.
+ * @c: UBIFS file-system description object
+ * @ref: the reference node to validate
+ * @ref_lnum: LEB number of the reference node
+ * @ref_offs: reference node offset
+ *
+ * This function returns %1 if a bud reference already exists for the LEB. %0 is
+ * returned if the reference node is new, otherwise %-EINVAL is returned if
+ * validation failed.
+ */
+static int validate_ref(struct ubifs_info *c, const struct ubifs_ref_node *ref)
+{
+	struct ubifs_bud *bud;
+	int lnum = le32_to_cpu(ref->lnum);
+	unsigned int offs = le32_to_cpu(ref->offs);
+	unsigned int jhead = le32_to_cpu(ref->jhead);
+
+	/*
+	 * ref->offs may point to the end of LEB when the journal head points
+	 * to the end of LEB and we write reference node for it during commit.
+	 * So this is why we require 'offs > c->leb_size'.
+	 */
+	if (jhead >= c->jhead_cnt || lnum >= c->leb_cnt ||
+	    lnum < c->main_first || offs > c->leb_size ||
+	    offs & (c->min_io_size - 1))
+		return -EINVAL;
+
+	/* Make sure we have not already looked at this bud */
+	bud = ubifs_search_bud(c, lnum);
+	if (bud) {
+		if (bud->jhead == jhead && bud->start <= offs)
+			return 1;
+		ubifs_err("bud at LEB %d:%d was already referred", lnum, offs);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * replay_log_leb - replay a log logical eraseblock.
+ * @c: UBIFS file-system description object
+ * @lnum: log logical eraseblock to replay
+ * @offs: offset to start replaying from
+ * @sbuf: scan buffer
+ *
+ * This function replays a log LEB and returns zero in case of success, %1 if
+ * this is the last LEB in the log, and a negative error code in case of
+ * failure.
+ */
+static int replay_log_leb(struct ubifs_info *c, int lnum, int offs, void *sbuf)
+{
+	int err;
+	struct ubifs_scan_leb *sleb;
+	struct ubifs_scan_node *snod;
+	const struct ubifs_cs_node *node;
+
+	dbg_mnt("replay log LEB %d:%d", lnum, offs);
+	sleb = ubifs_scan(c, lnum, offs, sbuf);
+	if (IS_ERR(sleb)) {
+		if (c->need_recovery)
+			sleb = ubifs_recover_log_leb(c, lnum, offs, sbuf);
+		if (IS_ERR(sleb))
+			return PTR_ERR(sleb);
+	}
+
+	if (sleb->nodes_cnt == 0) {
+		err = 1;
+		goto out;
+	}
+
+	node = sleb->buf;
+
+	snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list);
+	if (c->cs_sqnum == 0) {
+		/*
+		 * This is the first log LEB we are looking at, make sure that
+		 * the first node is a commit start node. Also record its
+		 * sequence number so that UBIFS can determine where the log
+		 * ends, because all nodes which were have higher sequence
+		 * numbers.
+		 */
+		if (snod->type != UBIFS_CS_NODE) {
+			dbg_err("first log node at LEB %d:%d is not CS node",
+				lnum, offs);
+			goto out_dump;
+		}
+		if (le64_to_cpu(node->cmt_no) != c->cmt_no) {
+			dbg_err("first CS node at LEB %d:%d has wrong "
+				"commit number %llu expected %llu",
+				lnum, offs,
+				(unsigned long long)le64_to_cpu(node->cmt_no),
+				c->cmt_no);
+			goto out_dump;
+		}
+
+		c->cs_sqnum = le64_to_cpu(node->ch.sqnum);
+		dbg_mnt("commit start sqnum %llu", c->cs_sqnum);
+	}
+
+	if (snod->sqnum < c->cs_sqnum) {
+		/*
+		 * This means that we reached end of log and now
+		 * look to the older log data, which was already
+		 * committed but the eraseblock was not erased (UBIFS
+		 * only un-maps it). So this basically means we have to
+		 * exit with "end of log" code.
+		 */
+		err = 1;
+		goto out;
+	}
+
+	/* Make sure the first node sits at offset zero of the LEB */
+	if (snod->offs != 0) {
+		dbg_err("first node is not at zero offset");
+		goto out_dump;
+	}
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+
+		cond_resched();
+
+		if (snod->sqnum >= SQNUM_WATERMARK) {
+			ubifs_err("file system's life ended");
+			goto out_dump;
+		}
+
+		if (snod->sqnum < c->cs_sqnum) {
+			dbg_err("bad sqnum %llu, commit sqnum %llu",
+				snod->sqnum, c->cs_sqnum);
+			goto out_dump;
+		}
+
+		if (snod->sqnum > c->max_sqnum)
+			c->max_sqnum = snod->sqnum;
+
+		switch (snod->type) {
+		case UBIFS_REF_NODE: {
+			const struct ubifs_ref_node *ref = snod->node;
+
+			err = validate_ref(c, ref);
+			if (err == 1)
+				break; /* Already have this bud */
+			if (err)
+				goto out_dump;
+
+			err = add_replay_bud(c, le32_to_cpu(ref->lnum),
+					     le32_to_cpu(ref->offs),
+					     le32_to_cpu(ref->jhead),
+					     snod->sqnum);
+			if (err)
+				goto out;
+
+			break;
+		}
+		case UBIFS_CS_NODE:
+			/* Make sure it sits at the beginning of LEB */
+			if (snod->offs != 0) {
+				ubifs_err("unexpected node in log");
+				goto out_dump;
+			}
+			break;
+		default:
+			ubifs_err("unexpected node in log");
+			goto out_dump;
+		}
+	}
+
+	if (sleb->endpt || c->lhead_offs >= c->leb_size) {
+		c->lhead_lnum = lnum;
+		c->lhead_offs = sleb->endpt;
+	}
+
+	err = !sleb->endpt;
+out:
+	ubifs_scan_destroy(sleb);
+	return err;
+
+out_dump:
+	ubifs_err("log error detected while replying the log at LEB %d:%d",
+		  lnum, offs + snod->offs);
+	dbg_dump_node(c, snod->node);
+	ubifs_scan_destroy(sleb);
+	return -EINVAL;
+}
+
+/**
+ * take_ihead - update the status of the index head in lprops to 'taken'.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns the amount of free space in the index head LEB or a
+ * negative error code.
+ */
+static int take_ihead(struct ubifs_info *c)
+{
+	const struct ubifs_lprops *lp;
+	int err, free;
+
+	ubifs_get_lprops(c);
+
+	lp = ubifs_lpt_lookup_dirty(c, c->ihead_lnum);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	free = lp->free;
+
+	lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
+			     lp->flags | LPROPS_TAKEN, 0);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	err = free;
+out:
+	ubifs_release_lprops(c);
+	return err;
+}
+
+/**
+ * ubifs_replay_journal - replay journal.
+ * @c: UBIFS file-system description object
+ *
+ * This function scans the journal, replays and cleans it up. It makes sure all
+ * memory data structures related to uncommitted journal are built (dirty TNC
+ * tree, tree of buds, modified lprops, etc).
+ */
+int ubifs_replay_journal(struct ubifs_info *c)
+{
+	int err, i, lnum, offs, _free;
+	void *sbuf = NULL;
+
+	BUILD_BUG_ON(UBIFS_TRUN_KEY > 5);
+
+	/* Update the status of the index head in lprops to 'taken' */
+	_free = take_ihead(c);
+	if (_free < 0)
+		return _free; /* Error code */
+
+	if (c->ihead_offs != c->leb_size - _free) {
+		ubifs_err("bad index head LEB %d:%d", c->ihead_lnum,
+			  c->ihead_offs);
+		return -EINVAL;
+	}
+
+	sbuf = vmalloc(c->leb_size);
+	if (!sbuf)
+		return -ENOMEM;
+
+	dbg_mnt("start replaying the journal");
+
+	c->replaying = 1;
+
+	lnum = c->ltail_lnum = c->lhead_lnum;
+	offs = c->lhead_offs;
+
+	for (i = 0; i < c->log_lebs; i++, lnum++) {
+		if (lnum >= UBIFS_LOG_LNUM + c->log_lebs) {
+			/*
+			 * The log is logically circular, we reached the last
+			 * LEB, switch to the first one.
+			 */
+			lnum = UBIFS_LOG_LNUM;
+			offs = 0;
+		}
+		err = replay_log_leb(c, lnum, offs, sbuf);
+		if (err == 1)
+			/* We hit the end of the log */
+			break;
+		if (err)
+			goto out;
+		offs = 0;
+	}
+
+	err = replay_buds(c);
+	if (err)
+		goto out;
+
+	err = apply_replay_tree(c);
+	if (err)
+		goto out;
+
+	ubifs_assert(c->bud_bytes <= c->max_bud_bytes || c->need_recovery);
+	dbg_mnt("finished, log head LEB %d:%d, max_sqnum %llu, "
+		"highest_inum %lu", c->lhead_lnum, c->lhead_offs, c->max_sqnum,
+		(unsigned long)c->highest_inum);
+out:
+	destroy_replay_tree(c);
+	destroy_bud_list(c);
+	vfree(sbuf);
+	c->replaying = 0;
+	return err;
+}