/*
   * 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"

  #include <linux/list_sort.h>

  /**

   * struct replay_entry - replay list entry.

   * @lnum: logical eraseblock number of the node
   * @offs: node offset
   * @len: node length

   * @deletion: non-zero if this entry corresponds to a node deletion

   * @sqnum: node sequence number

   * @list: links the replay list

   * @key: node key
   * @nm: directory entry name
   * @old_size: truncation old size
   * @new_size: truncation new size

   *

   * The replay process first scans all buds and builds the replay list, then
   * sorts the replay list in nodes sequence number order, and then inserts all
   * the replay entries to the TNC.

   */
  struct replay_entry {
  	int lnum;
  	int offs;
  	int len;

  	unsigned int deletion:1;

  	unsigned long long sqnum;

  	struct list_head list;

  	union ubifs_key key;
  	union {
  		struct qstr nm;
  		struct {
  			loff_t old_size;
  			loff_t new_size;
  		};

  	};
  };
  
  /**
   * struct bud_entry - entry in the list of buds to replay.
   * @list: next bud in the list
   * @bud: bud description object

   * @sqnum: reference node sequence number

   * @free: free bytes in the bud
   * @dirty: dirty bytes in the bud

   */
  struct bud_entry {
  	struct list_head list;
  	struct ubifs_bud *bud;

  	unsigned long long sqnum;

  	int free;
  	int dirty;

  };
  
  /**
   * set_bud_lprops - set free and dirty space used by a bud.
   * @c: UBIFS file-system description object

   * @b: bud entry which describes the bud
   *
   * This function makes sure the LEB properties of bud @b are set correctly
   * after the replay. Returns zero in case of success and a negative error code
   * in case of failure.

   */

  static int set_bud_lprops(struct ubifs_info *c, struct bud_entry *b)

  {
  	const struct ubifs_lprops *lp;
  	int err = 0, dirty;
  
  	ubifs_get_lprops(c);

  	lp = ubifs_lpt_lookup_dirty(c, b->bud->lnum);

  	if (IS_ERR(lp)) {
  		err = PTR_ERR(lp);
  		goto out;
  	}
  
  	dirty = lp->dirty;

  	if (b->bud->start == 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 had been garbage collected before it became the bud,
  		 * and there was not commit inbetween. The garbage collector
  		 * resets the free and dirty space without recording it
  		 * anywhere except lprops, so if there was no commit then
  		 * lprops does not have that information.

  		 *
  		 * 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

  		 * @b->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)", b->bud->lnum,

  			lp->free, lp->dirty);

  		dbg_gc("bud LEB %d was GC'd (%d free, %d dirty)", b->bud->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 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", b->bud->lnum,
  				lp->free, lp->dirty, b->free, b->dirty);

  	}

  	lp = ubifs_change_lp(c, lp, b->free, dirty + b->dirty,

  			     lp->flags | LPROPS_TAKEN, 0);
  	if (IS_ERR(lp)) {
  		err = PTR_ERR(lp);
  		goto out;
  	}

  
  	/* Make sure the journal head points to the latest bud */

  	err = ubifs_wbuf_seek_nolock(&c->jheads[b->bud->jhead].wbuf,
  				     b->bud->lnum, c->leb_size - b->free,
  				     UBI_SHORTTERM);

  out:
  	ubifs_release_lprops(c);
  	return err;
  }
  
  /**

   * set_buds_lprops - set free and dirty space for all replayed buds.
   * @c: UBIFS file-system description object
   *
   * This function sets LEB properties for all replayed buds. Returns zero in
   * case of success and a negative error code in case of failure.
   */
  static int set_buds_lprops(struct ubifs_info *c)
  {
  	struct bud_entry *b;
  	int err;
  
  	list_for_each_entry(b, &c->replay_buds, list) {
  		err = set_bud_lprops(c, b);
  		if (err)
  			return err;
  	}
  
  	return 0;
  }
  
  /**

   * 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;

  	dbg_mntk(&r->key, "LEB %d:%d len %d deletion %d sqnum %llu key ",
  		 r->lnum, r->offs, r->len, r->deletion, r->sqnum);

  
  	/* Set c->replay_sqnum to help deal with dangling branches. */
  	c->replay_sqnum = r->sqnum;

  	if (is_hash_key(c, &r->key)) {
  		if (r->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 (r->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, r->deletion,

  						       r->new_size);
  	}
  
  	return err;
  }
  
  /**

   * replay_entries_cmp - compare 2 replay entries.
   * @priv: UBIFS file-system description object
   * @a: first replay entry
   * @a: second replay entry

   *

   * This is a comparios function for 'list_sort()' which compares 2 replay
   * entries @a and @b by comparing their sequence numer.  Returns %1 if @a has
   * greater sequence number and %-1 otherwise.

   */

  static int replay_entries_cmp(void *priv, struct list_head *a,
  			      struct list_head *b)

  {

  	struct replay_entry *ra, *rb;
  
  	cond_resched();
  	if (a == b)
  		return 0;
  
  	ra = list_entry(a, struct replay_entry, list);
  	rb = list_entry(b, struct replay_entry, list);
  	ubifs_assert(ra->sqnum != rb->sqnum);
  	if (ra->sqnum > rb->sqnum)
  		return 1;
  	return -1;

  }
  
  /**

   * apply_replay_list - apply the replay list to the TNC.

   * @c: UBIFS file-system description object
   *

   * Apply all entries in the replay list to the TNC. Returns zero in case of
   * success and a negative error code in case of failure.

   */

  static int apply_replay_list(struct ubifs_info *c)

  {

  	struct replay_entry *r;
  	int err;

  	list_sort(c, &c->replay_list, &replay_entries_cmp);

  	list_for_each_entry(r, &c->replay_list, list) {

  		cond_resched();

  		err = apply_replay_entry(c, r);
  		if (err)
  			return err;

  	}

  	return 0;
  }
  
  /**

   * destroy_replay_list - destroy the replay.
   * @c: UBIFS file-system description object
   *
   * Destroy the replay list.
   */
  static void destroy_replay_list(struct ubifs_info *c)
  {
  	struct replay_entry *r, *tmp;
  
  	list_for_each_entry_safe(r, tmp, &c->replay_list, list) {
  		if (is_hash_key(c, &r->key))
  			kfree(r->nm.name);
  		list_del(&r->list);
  		kfree(r);
  	}
  }
  
  /**
   * insert_node - insert a node to the replay list

   * @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 list. The
   * replay list contains @struct replay_entry elements, and we sort this list in
   * sequence number order before applying it. The replay list is applied at the
   * very end of the replay process. Since the list 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 replay_entry *r;

  	dbg_mntk(key, "add LEB %d:%d, key ", lnum, offs);

  	if (key_inum(c, key) >= c->highest_inum)
  		c->highest_inum = key_inum(c, key);

  	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->deletion = !!deletion;

  	r->sqnum = sqnum;

  	key_copy(c, key, &r->key);

  	r->old_size = old_size;
  	r->new_size = new_size;

  	list_add_tail(&r->list, &c->replay_list);

  	return 0;
  }
  
  /**

   * insert_dent - insert a directory entry node into the replay list.

   * @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 or an extended
   * attribute entry to the replay list. Returns zero in case of success and a
   * negative error code in case of failure.

   */
  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 replay_entry *r;
  	char *nbuf;

  	dbg_mntk(key, "add LEB %d:%d, key ", lnum, offs);

  	if (key_inum(c, key) >= c->highest_inum)
  		c->highest_inum = key_inum(c, key);

  	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->deletion = !!deletion;

  	r->sqnum = sqnum;

  	key_copy(c, key, &r->key);

  	r->nm.len = nlen;
  	memcpy(nbuf, name, nlen);
  	nbuf[nlen] = '\0';
  	r->nm.name = nbuf;

  	list_add_tail(&r->list, &c->replay_list);

  	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(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;
  }
  
  /**

   * is_last_bud - check if the bud is the last in the journal head.
   * @c: UBIFS file-system description object
   * @bud: bud description object
   *
   * This function checks if bud @bud is the last bud in its journal head. This
   * information is then used by 'replay_bud()' to decide whether the bud can
   * have corruptions or not. Indeed, only last buds can be corrupted by power
   * cuts. Returns %1 if this is the last bud, and %0 if not.
   */
  static int is_last_bud(struct ubifs_info *c, struct ubifs_bud *bud)
  {
  	struct ubifs_jhead *jh = &c->jheads[bud->jhead];
  	struct ubifs_bud *next;
  	uint32_t data;
  	int err;
  
  	if (list_is_last(&bud->list, &jh->buds_list))
  		return 1;
  
  	/*
  	 * The following is a quirk to make sure we work correctly with UBIFS
  	 * images used with older UBIFS.
  	 *
  	 * Normally, the last bud will be the last in the journal head's list
  	 * of bud. However, there is one exception if the UBIFS image belongs
  	 * to older UBIFS. This is fairly unlikely: one would need to use old
  	 * UBIFS, then have a power cut exactly at the right point, and then
  	 * try to mount this image with new UBIFS.
  	 *
  	 * The exception is: it is possible to have 2 buds A and B, A goes
  	 * before B, and B is the last, bud B is contains no data, and bud A is
  	 * corrupted at the end. The reason is that in older versions when the
  	 * journal code switched the next bud (from A to B), it first added a
  	 * log reference node for the new bud (B), and only after this it
  	 * synchronized the write-buffer of current bud (A). But later this was
  	 * changed and UBIFS started to always synchronize the write-buffer of
  	 * the bud (A) before writing the log reference for the new bud (B).
  	 *
  	 * But because older UBIFS always synchronized A's write-buffer before
  	 * writing to B, we can recognize this exceptional situation but
  	 * checking the contents of bud B - if it is empty, then A can be
  	 * treated as the last and we can recover it.
  	 *
  	 * TODO: remove this piece of code in a couple of years (today it is
  	 * 16.05.2011).
  	 */
  	next = list_entry(bud->list.next, struct ubifs_bud, list);
  	if (!list_is_last(&next->list, &jh->buds_list))
  		return 0;

  	err = ubifs_leb_read(c, next->lnum, (char *)&data, next->start, 4, 1);

  	if (err)
  		return 0;
  
  	return data == 0xFFFFFFFF;
  }
  
  /**

   * replay_bud - replay a bud logical eraseblock.
   * @c: UBIFS file-system description object

   * @b: bud entry which describes the bud

   *

   * This function replays bud @bud, recovers it if needed, and adds all nodes
   * from this bud to the replay list. Returns zero in case of success and a
   * negative error code in case of failure.

   */

  static int replay_bud(struct ubifs_info *c, struct bud_entry *b)

  {

  	int is_last = is_last_bud(c, b->bud);

  	int err = 0, used = 0, lnum = b->bud->lnum, offs = b->bud->start;

  	struct ubifs_scan_leb *sleb;
  	struct ubifs_scan_node *snod;

  	dbg_mnt("replay bud LEB %d, head %d, offs %d, is_last %d",
  		lnum, b->bud->jhead, offs, is_last);

  	if (c->need_recovery && is_last)
  		/*
  		 * Recover only last LEBs in the journal heads, because power
  		 * cuts may cause corruptions only in these LEBs, because only
  		 * these LEBs could possibly be written to at the power cut
  		 * time.
  		 */

  		sleb = ubifs_recover_leb(c, lnum, offs, c->sbuf, b->bud->jhead);

  	else

  		sleb = ubifs_scan(c, lnum, offs, c->sbuf, 0);

  	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, 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;
  	}

  	ubifs_assert(ubifs_search_bud(c, lnum));

  	ubifs_assert(sleb->endpt - offs >= used);
  	ubifs_assert(sleb->endpt % c->min_io_size == 0);

  	b->dirty = sleb->endpt - offs - used;
  	b->free = c->leb_size - sleb->endpt;
  	dbg_mnt("bud LEB %d replied: dirty %d, free %d", lnum, b->dirty, b->free);

  
  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;
  }
  
  /**

   * 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;

  	unsigned long long prev_sqnum = 0;

  
  	list_for_each_entry(b, &c->replay_buds, list) {

  		err = replay_bud(c, b);

  		if (err)
  			return err;

  
  		ubifs_assert(b->sqnum > prev_sqnum);
  		prev_sqnum = b->sqnum;

  	}
  
  	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, c->need_recovery);
  	if (IS_ERR(sleb)) {

  		if (PTR_ERR(sleb) != -EUCLEAN || !c->need_recovery)
  			return PTR_ERR(sleb);

  		/*
  		 * Note, the below function will recover this log LEB only if
  		 * it is the last, because unclean reboots can possibly corrupt
  		 * only the tail of the log.
  		 */

  		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 replaying 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;

  
  	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;
  	}

  	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, c->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_list(c);

  	if (err)
  		goto out;

  	err = set_buds_lprops(c);
  	if (err)
  		goto out;

  	/*

  	 * UBIFS budgeting calculations use @c->bi.uncommitted_idx variable
  	 * to roughly estimate index growth. Things like @c->bi.min_idx_lebs

  	 * depend on it. This means we have to initialize it to make sure
  	 * budgeting works properly.
  	 */

  	c->bi.uncommitted_idx = atomic_long_read(&c->dirty_zn_cnt);
  	c->bi.uncommitted_idx *= c->max_idx_node_sz;

  	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_list(c);

  	destroy_bud_list(c);

  	c->replaying = 0;
  	return err;
  }