/*
   * This file is part of UBIFS.
   *
   * Copyright (C) 2006-2008 Nokia Corporation
   *

   * SPDX-License-Identifier:	GPL-2.0+

   *
   * Authors: Adrian Hunter
   *          Artem Bityutskiy (Битюцкий Артём)
   */
  
  /*
   * This file implements functions needed to recover from unclean un-mounts.
   * When UBIFS is mounted, it checks a flag on the master node to determine if

   * an un-mount was completed successfully. If not, the process of mounting
   * incorporates additional checking and fixing of on-flash data structures.

   * UBIFS always cleans away all remnants of an unclean un-mount, so that
   * errors do not accumulate. However UBIFS defers recovery if it is mounted
   * read-only, and the flash is not modified in that case.

   *
   * The general UBIFS approach to the recovery is that it recovers from
   * corruptions which could be caused by power cuts, but it refuses to recover
   * from corruption caused by other reasons. And UBIFS tries to distinguish
   * between these 2 reasons of corruptions and silently recover in the former
   * case and loudly complain in the latter case.
   *
   * UBIFS writes only to erased LEBs, so it writes only to the flash space
   * containing only 0xFFs. UBIFS also always writes strictly from the beginning
   * of the LEB to the end. And UBIFS assumes that the underlying flash media
   * writes in @c->max_write_size bytes at a time.
   *
   * Hence, if UBIFS finds a corrupted node at offset X, it expects only the min.
   * I/O unit corresponding to offset X to contain corrupted data, all the
   * following min. I/O units have to contain empty space (all 0xFFs). If this is
   * not true, the corruption cannot be the result of a power cut, and UBIFS
   * refuses to mount.

   */

  #ifndef __UBOOT__
  #include <linux/crc32.h>
  #include <linux/slab.h>
  #else
  #include <linux/err.h>
  #endif

  #include "ubifs.h"
  
  /**
   * is_empty - determine whether a buffer is empty (contains all 0xff).
   * @buf: buffer to clean
   * @len: length of buffer
   *
   * This function returns %1 if the buffer is empty (contains all 0xff) otherwise
   * %0 is returned.
   */
  static int is_empty(void *buf, int len)
  {
  	uint8_t *p = buf;
  	int i;
  
  	for (i = 0; i < len; i++)
  		if (*p++ != 0xff)
  			return 0;
  	return 1;
  }
  
  /**

   * first_non_ff - find offset of the first non-0xff byte.
   * @buf: buffer to search in
   * @len: length of buffer
   *
   * This function returns offset of the first non-0xff byte in @buf or %-1 if
   * the buffer contains only 0xff bytes.
   */
  static int first_non_ff(void *buf, int len)
  {
  	uint8_t *p = buf;
  	int i;
  
  	for (i = 0; i < len; i++)
  		if (*p++ != 0xff)
  			return i;
  	return -1;
  }
  
  /**

   * get_master_node - get the last valid master node allowing for corruption.
   * @c: UBIFS file-system description object
   * @lnum: LEB number
   * @pbuf: buffer containing the LEB read, is returned here
   * @mst: master node, if found, is returned here
   * @cor: corruption, if found, is returned here
   *
   * This function allocates a buffer, reads the LEB into it, and finds and
   * returns the last valid master node allowing for one area of corruption.
   * The corrupt area, if there is one, must be consistent with the assumption
   * that it is the result of an unclean unmount while the master node was being
   * written. Under those circumstances, it is valid to use the previously written
   * master node.
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  static int get_master_node(const struct ubifs_info *c, int lnum, void **pbuf,
  			   struct ubifs_mst_node **mst, void **cor)
  {
  	const int sz = c->mst_node_alsz;
  	int err, offs, len;
  	void *sbuf, *buf;
  
  	sbuf = vmalloc(c->leb_size);
  	if (!sbuf)
  		return -ENOMEM;

  	err = ubifs_leb_read(c, lnum, sbuf, 0, c->leb_size, 0);

  	if (err && err != -EBADMSG)
  		goto out_free;
  
  	/* Find the first position that is definitely not a node */
  	offs = 0;
  	buf = sbuf;
  	len = c->leb_size;
  	while (offs + UBIFS_MST_NODE_SZ <= c->leb_size) {
  		struct ubifs_ch *ch = buf;
  
  		if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
  			break;
  		offs += sz;
  		buf  += sz;
  		len  -= sz;
  	}
  	/* See if there was a valid master node before that */
  	if (offs) {
  		int ret;
  
  		offs -= sz;
  		buf  -= sz;
  		len  += sz;
  		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
  		if (ret != SCANNED_A_NODE && offs) {
  			/* Could have been corruption so check one place back */
  			offs -= sz;
  			buf  -= sz;
  			len  += sz;
  			ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
  			if (ret != SCANNED_A_NODE)
  				/*
  				 * We accept only one area of corruption because
  				 * we are assuming that it was caused while
  				 * trying to write a master node.
  				 */
  				goto out_err;
  		}
  		if (ret == SCANNED_A_NODE) {
  			struct ubifs_ch *ch = buf;
  
  			if (ch->node_type != UBIFS_MST_NODE)
  				goto out_err;
  			dbg_rcvry("found a master node at %d:%d", lnum, offs);
  			*mst = buf;
  			offs += sz;
  			buf  += sz;
  			len  -= sz;
  		}
  	}
  	/* Check for corruption */
  	if (offs < c->leb_size) {
  		if (!is_empty(buf, min_t(int, len, sz))) {
  			*cor = buf;
  			dbg_rcvry("found corruption at %d:%d", lnum, offs);
  		}
  		offs += sz;
  		buf  += sz;
  		len  -= sz;
  	}
  	/* Check remaining empty space */
  	if (offs < c->leb_size)
  		if (!is_empty(buf, len))
  			goto out_err;
  	*pbuf = sbuf;
  	return 0;
  
  out_err:
  	err = -EINVAL;
  out_free:
  	vfree(sbuf);
  	*mst = NULL;
  	*cor = NULL;
  	return err;
  }
  
  /**
   * write_rcvrd_mst_node - write recovered master node.
   * @c: UBIFS file-system description object
   * @mst: master node
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  static int write_rcvrd_mst_node(struct ubifs_info *c,
  				struct ubifs_mst_node *mst)
  {
  	int err = 0, lnum = UBIFS_MST_LNUM, sz = c->mst_node_alsz;
  	__le32 save_flags;
  
  	dbg_rcvry("recovery");
  
  	save_flags = mst->flags;
  	mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);
  
  	ubifs_prepare_node(c, mst, UBIFS_MST_NODE_SZ, 1);

  	err = ubifs_leb_change(c, lnum, mst, sz);

  	if (err)
  		goto out;

  	err = ubifs_leb_change(c, lnum + 1, mst, sz);

  	if (err)
  		goto out;
  out:
  	mst->flags = save_flags;
  	return err;
  }
  
  /**
   * ubifs_recover_master_node - recover the master node.
   * @c: UBIFS file-system description object
   *
   * This function recovers the master node from corruption that may occur due to
   * an unclean unmount.
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  int ubifs_recover_master_node(struct ubifs_info *c)
  {
  	void *buf1 = NULL, *buf2 = NULL, *cor1 = NULL, *cor2 = NULL;
  	struct ubifs_mst_node *mst1 = NULL, *mst2 = NULL, *mst;
  	const int sz = c->mst_node_alsz;
  	int err, offs1, offs2;
  
  	dbg_rcvry("recovery");
  
  	err = get_master_node(c, UBIFS_MST_LNUM, &buf1, &mst1, &cor1);
  	if (err)
  		goto out_free;
  
  	err = get_master_node(c, UBIFS_MST_LNUM + 1, &buf2, &mst2, &cor2);
  	if (err)
  		goto out_free;
  
  	if (mst1) {
  		offs1 = (void *)mst1 - buf1;
  		if ((le32_to_cpu(mst1->flags) & UBIFS_MST_RCVRY) &&
  		    (offs1 == 0 && !cor1)) {
  			/*
  			 * mst1 was written by recovery at offset 0 with no
  			 * corruption.
  			 */
  			dbg_rcvry("recovery recovery");
  			mst = mst1;
  		} else if (mst2) {
  			offs2 = (void *)mst2 - buf2;
  			if (offs1 == offs2) {
  				/* Same offset, so must be the same */
  				if (memcmp((void *)mst1 + UBIFS_CH_SZ,
  					   (void *)mst2 + UBIFS_CH_SZ,
  					   UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))
  					goto out_err;
  				mst = mst1;
  			} else if (offs2 + sz == offs1) {
  				/* 1st LEB was written, 2nd was not */
  				if (cor1)
  					goto out_err;
  				mst = mst1;

  			} else if (offs1 == 0 &&
  				   c->leb_size - offs2 - sz < sz) {

  				/* 1st LEB was unmapped and written, 2nd not */
  				if (cor1)
  					goto out_err;
  				mst = mst1;
  			} else
  				goto out_err;
  		} else {
  			/*
  			 * 2nd LEB was unmapped and about to be written, so
  			 * there must be only one master node in the first LEB
  			 * and no corruption.
  			 */
  			if (offs1 != 0 || cor1)
  				goto out_err;
  			mst = mst1;
  		}
  	} else {
  		if (!mst2)
  			goto out_err;
  		/*
  		 * 1st LEB was unmapped and about to be written, so there must
  		 * be no room left in 2nd LEB.
  		 */
  		offs2 = (void *)mst2 - buf2;
  		if (offs2 + sz + sz <= c->leb_size)
  			goto out_err;
  		mst = mst2;
  	}

  	ubifs_msg(c, "recovered master node from LEB %d",

  		  (mst == mst1 ? UBIFS_MST_LNUM : UBIFS_MST_LNUM + 1));
  
  	memcpy(c->mst_node, mst, UBIFS_MST_NODE_SZ);

  	if (c->ro_mount) {

  		/* Read-only mode. Keep a copy for switching to rw mode */
  		c->rcvrd_mst_node = kmalloc(sz, GFP_KERNEL);
  		if (!c->rcvrd_mst_node) {
  			err = -ENOMEM;
  			goto out_free;
  		}
  		memcpy(c->rcvrd_mst_node, c->mst_node, UBIFS_MST_NODE_SZ);

  
  		/*
  		 * We had to recover the master node, which means there was an
  		 * unclean reboot. However, it is possible that the master node
  		 * is clean at this point, i.e., %UBIFS_MST_DIRTY is not set.
  		 * E.g., consider the following chain of events:
  		 *
  		 * 1. UBIFS was cleanly unmounted, so the master node is clean
  		 * 2. UBIFS is being mounted R/W and starts changing the master
  		 *    node in the first (%UBIFS_MST_LNUM). A power cut happens,
  		 *    so this LEB ends up with some amount of garbage at the
  		 *    end.
  		 * 3. UBIFS is being mounted R/O. We reach this place and
  		 *    recover the master node from the second LEB
  		 *    (%UBIFS_MST_LNUM + 1). But we cannot update the media
  		 *    because we are being mounted R/O. We have to defer the
  		 *    operation.
  		 * 4. However, this master node (@c->mst_node) is marked as
  		 *    clean (since the step 1). And if we just return, the
  		 *    mount code will be confused and won't recover the master
  		 *    node when it is re-mounter R/W later.
  		 *
  		 *    Thus, to force the recovery by marking the master node as
  		 *    dirty.
  		 */
  		c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
  #ifndef __UBOOT__
  	} else {
  		/* Write the recovered master node */
  		c->max_sqnum = le64_to_cpu(mst->ch.sqnum) - 1;
  		err = write_rcvrd_mst_node(c, c->mst_node);
  		if (err)
  			goto out_free;
  #endif

  	}
  
  	vfree(buf2);
  	vfree(buf1);
  
  	return 0;
  
  out_err:
  	err = -EINVAL;
  out_free:

  	ubifs_err(c, "failed to recover master node");

  	if (mst1) {

  		ubifs_err(c, "dumping first master node");

  		ubifs_dump_node(c, mst1);

  	}
  	if (mst2) {

  		ubifs_err(c, "dumping second master node");

  		ubifs_dump_node(c, mst2);

  	}
  	vfree(buf2);
  	vfree(buf1);
  	return err;
  }
  
  /**
   * ubifs_write_rcvrd_mst_node - write the recovered master node.
   * @c: UBIFS file-system description object
   *
   * This function writes the master node that was recovered during mounting in
   * read-only mode and must now be written because we are remounting rw.
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  int ubifs_write_rcvrd_mst_node(struct ubifs_info *c)
  {
  	int err;
  
  	if (!c->rcvrd_mst_node)
  		return 0;
  	c->rcvrd_mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
  	c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
  	err = write_rcvrd_mst_node(c, c->rcvrd_mst_node);
  	if (err)
  		return err;
  	kfree(c->rcvrd_mst_node);
  	c->rcvrd_mst_node = NULL;
  	return 0;
  }
  
  /**
   * is_last_write - determine if an offset was in the last write to a LEB.
   * @c: UBIFS file-system description object
   * @buf: buffer to check
   * @offs: offset to check
   *
   * This function returns %1 if @offs was in the last write to the LEB whose data

   * is in @buf, otherwise %0 is returned. The determination is made by checking
   * for subsequent empty space starting from the next @c->max_write_size
   * boundary.

   */
  static int is_last_write(const struct ubifs_info *c, void *buf, int offs)
  {

  	int empty_offs, check_len;

  	uint8_t *p;

  	/*

  	 * Round up to the next @c->max_write_size boundary i.e. @offs is in
  	 * the last wbuf written. After that should be empty space.

  	 */

  	empty_offs = ALIGN(offs + 1, c->max_write_size);

  	check_len = c->leb_size - empty_offs;
  	p = buf + empty_offs - offs;

  	return is_empty(p, check_len);

  }
  
  /**
   * clean_buf - clean the data from an LEB sitting in a buffer.
   * @c: UBIFS file-system description object
   * @buf: buffer to clean
   * @lnum: LEB number to clean
   * @offs: offset from which to clean
   * @len: length of buffer
   *
   * This function pads up to the next min_io_size boundary (if there is one) and
   * sets empty space to all 0xff. @buf, @offs and @len are updated to the next

   * @c->min_io_size boundary.

   */
  static void clean_buf(const struct ubifs_info *c, void **buf, int lnum,
  		      int *offs, int *len)
  {
  	int empty_offs, pad_len;
  
  	lnum = lnum;
  	dbg_rcvry("cleaning corruption at %d:%d", lnum, *offs);

  	ubifs_assert(!(*offs & 7));
  	empty_offs = ALIGN(*offs, c->min_io_size);
  	pad_len = empty_offs - *offs;
  	ubifs_pad(c, *buf, pad_len);
  	*offs += pad_len;
  	*buf += pad_len;
  	*len -= pad_len;
  	memset(*buf, 0xff, c->leb_size - empty_offs);
  }
  
  /**
   * no_more_nodes - determine if there are no more nodes in a buffer.
   * @c: UBIFS file-system description object
   * @buf: buffer to check
   * @len: length of buffer
   * @lnum: LEB number of the LEB from which @buf was read
   * @offs: offset from which @buf was read
   *

   * This function ensures that the corrupted node at @offs is the last thing
   * written to a LEB. This function returns %1 if more data is not found and
   * %0 if more data is found.

   */
  static int no_more_nodes(const struct ubifs_info *c, void *buf, int len,
  			int lnum, int offs)
  {

  	struct ubifs_ch *ch = buf;
  	int skip, dlen = le32_to_cpu(ch->len);

  	/* Check for empty space after the corrupt node's common header */

  	skip = ALIGN(offs + UBIFS_CH_SZ, c->max_write_size) - offs;

  	if (is_empty(buf + skip, len - skip))
  		return 1;
  	/*
  	 * The area after the common header size is not empty, so the common
  	 * header must be intact. Check it.
  	 */
  	if (ubifs_check_node(c, buf, lnum, offs, 1, 0) != -EUCLEAN) {
  		dbg_rcvry("unexpected bad common header at %d:%d", lnum, offs);
  		return 0;

  	}

  	/* Now we know the corrupt node's length we can skip over it */

  	skip = ALIGN(offs + dlen, c->max_write_size) - offs;

  	/* After which there should be empty space */
  	if (is_empty(buf + skip, len - skip))
  		return 1;
  	dbg_rcvry("unexpected data at %d:%d", lnum, offs + skip);
  	return 0;

  }
  
  /**
   * fix_unclean_leb - fix an unclean LEB.
   * @c: UBIFS file-system description object
   * @sleb: scanned LEB information
   * @start: offset where scan started
   */
  static int fix_unclean_leb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
  			   int start)
  {
  	int lnum = sleb->lnum, endpt = start;
  
  	/* Get the end offset of the last node we are keeping */
  	if (!list_empty(&sleb->nodes)) {
  		struct ubifs_scan_node *snod;
  
  		snod = list_entry(sleb->nodes.prev,
  				  struct ubifs_scan_node, list);
  		endpt = snod->offs + snod->len;
  	}

  	if (c->ro_mount && !c->remounting_rw) {

  		/* Add to recovery list */
  		struct ubifs_unclean_leb *ucleb;
  
  		dbg_rcvry("need to fix LEB %d start %d endpt %d",
  			  lnum, start, sleb->endpt);
  		ucleb = kzalloc(sizeof(struct ubifs_unclean_leb), GFP_NOFS);
  		if (!ucleb)
  			return -ENOMEM;
  		ucleb->lnum = lnum;
  		ucleb->endpt = endpt;
  		list_add_tail(&ucleb->list, &c->unclean_leb_list);

  #ifndef __UBOOT__
  	} else {
  		/* Write the fixed LEB back to flash */
  		int err;
  
  		dbg_rcvry("fixing LEB %d start %d endpt %d",
  			  lnum, start, sleb->endpt);
  		if (endpt == 0) {
  			err = ubifs_leb_unmap(c, lnum);
  			if (err)
  				return err;
  		} else {
  			int len = ALIGN(endpt, c->min_io_size);
  
  			if (start) {
  				err = ubifs_leb_read(c, lnum, sleb->buf, 0,
  						     start, 1);
  				if (err)
  					return err;
  			}
  			/* Pad to min_io_size */
  			if (len > endpt) {
  				int pad_len = len - ALIGN(endpt, 8);
  
  				if (pad_len > 0) {
  					void *buf = sleb->buf + len - pad_len;
  
  					ubifs_pad(c, buf, pad_len);
  				}
  			}
  			err = ubifs_leb_change(c, lnum, sleb->buf, len);
  			if (err)
  				return err;
  		}
  #endif

  	}
  	return 0;
  }
  
  /**

   * drop_last_group - drop the last group of nodes.

   * @sleb: scanned LEB information
   * @offs: offset of dropped nodes is returned here
   *

   * This is a helper function for 'ubifs_recover_leb()' which drops the last
   * group of nodes of the scanned LEB.

   */

  static void drop_last_group(struct ubifs_scan_leb *sleb, int *offs)

  {

  	while (!list_empty(&sleb->nodes)) {
  		struct ubifs_scan_node *snod;
  		struct ubifs_ch *ch;
  
  		snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
  				  list);
  		ch = snod->node;
  		if (ch->group_type != UBIFS_IN_NODE_GROUP)

  			break;
  
  		dbg_rcvry("dropping grouped node at %d:%d",
  			  sleb->lnum, snod->offs);
  		*offs = snod->offs;
  		list_del(&snod->list);
  		kfree(snod);
  		sleb->nodes_cnt -= 1;
  	}
  }
  
  /**
   * drop_last_node - drop the last node.
   * @sleb: scanned LEB information
   * @offs: offset of dropped nodes is returned here

   *
   * This is a helper function for 'ubifs_recover_leb()' which drops the last
   * node of the scanned LEB.
   */
  static void drop_last_node(struct ubifs_scan_leb *sleb, int *offs)
  {
  	struct ubifs_scan_node *snod;
  
  	if (!list_empty(&sleb->nodes)) {
  		snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
  				  list);
  
  		dbg_rcvry("dropping last node at %d:%d",
  			  sleb->lnum, snod->offs);

  		*offs = snod->offs;
  		list_del(&snod->list);
  		kfree(snod);
  		sleb->nodes_cnt -= 1;

  	}

  }
  
  /**
   * ubifs_recover_leb - scan and recover a LEB.
   * @c: UBIFS file-system description object
   * @lnum: LEB number
   * @offs: offset
   * @sbuf: LEB-sized buffer to use

   * @jhead: journal head number this LEB belongs to (%-1 if the LEB does not
   *         belong to any journal head)

   *
   * This function does a scan of a LEB, but caters for errors that might have
   * been caused by the unclean unmount from which we are attempting to recover.

   * Returns the scanned information on success and a negative error code on
   * failure.

   */
  struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,

  					 int offs, void *sbuf, int jhead)

  {

  	int ret = 0, err, len = c->leb_size - offs, start = offs, min_io_unit;
  	int grouped = jhead == -1 ? 0 : c->jheads[jhead].grouped;

  	struct ubifs_scan_leb *sleb;
  	void *buf = sbuf + offs;

  	dbg_rcvry("%d:%d, jhead %d, grouped %d", lnum, offs, jhead, grouped);

  
  	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
  	if (IS_ERR(sleb))
  		return sleb;

  	ubifs_assert(len >= 8);

  	while (len >= 8) {

  		dbg_scan("look at LEB %d:%d (%d bytes left)",
  			 lnum, offs, len);
  
  		cond_resched();
  
  		/*
  		 * Scan quietly until there is an error from which we cannot
  		 * recover
  		 */

  		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);

  		if (ret == SCANNED_A_NODE) {
  			/* A valid node, and not a padding node */
  			struct ubifs_ch *ch = buf;
  			int node_len;
  
  			err = ubifs_add_snod(c, sleb, buf, offs);
  			if (err)
  				goto error;
  			node_len = ALIGN(le32_to_cpu(ch->len), 8);
  			offs += node_len;
  			buf += node_len;
  			len -= node_len;

  		} else if (ret > 0) {

  			/* Padding bytes or a valid padding node */
  			offs += ret;
  			buf += ret;
  			len -= ret;

  		} else if (ret == SCANNED_EMPTY_SPACE ||
  			   ret == SCANNED_GARBAGE     ||
  			   ret == SCANNED_A_BAD_PAD_NODE ||
  			   ret == SCANNED_A_CORRUPT_NODE) {
  			dbg_rcvry("found corruption (%d) at %d:%d",
  				  ret, lnum, offs);

  			break;

  		} else {

  			ubifs_err(c, "unexpected return value %d", ret);

  			err = -EINVAL;
  			goto error;

  		}

  	}

  	if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE) {
  		if (!is_last_write(c, buf, offs))
  			goto corrupted_rescan;
  	} else if (ret == SCANNED_A_CORRUPT_NODE) {
  		if (!no_more_nodes(c, buf, len, lnum, offs))
  			goto corrupted_rescan;
  	} else if (!is_empty(buf, len)) {
  		if (!is_last_write(c, buf, offs)) {
  			int corruption = first_non_ff(buf, len);

  			/*
  			 * See header comment for this file for more
  			 * explanations about the reasons we have this check.
  			 */

  			ubifs_err(c, "corrupt empty space LEB %d:%d, corruption starts at %d",

  				  lnum, offs, corruption);
  			/* Make sure we dump interesting non-0xFF data */
  			offs += corruption;
  			buf += corruption;

  			goto corrupted;
  		}
  	}

  	min_io_unit = round_down(offs, c->min_io_size);
  	if (grouped)
  		/*
  		 * If nodes are grouped, always drop the incomplete group at
  		 * the end.
  		 */
  		drop_last_group(sleb, &offs);

  	if (jhead == GCHD) {
  		/*
  		 * If this LEB belongs to the GC head then while we are in the
  		 * middle of the same min. I/O unit keep dropping nodes. So
  		 * basically, what we want is to make sure that the last min.
  		 * I/O unit where we saw the corruption is dropped completely
  		 * with all the uncorrupted nodes which may possibly sit there.
  		 *
  		 * In other words, let's name the min. I/O unit where the
  		 * corruption starts B, and the previous min. I/O unit A. The
  		 * below code tries to deal with a situation when half of B
  		 * contains valid nodes or the end of a valid node, and the
  		 * second half of B contains corrupted data or garbage. This
  		 * means that UBIFS had been writing to B just before the power
  		 * cut happened. I do not know how realistic is this scenario
  		 * that half of the min. I/O unit had been written successfully
  		 * and the other half not, but this is possible in our 'failure
  		 * mode emulation' infrastructure at least.
  		 *
  		 * So what is the problem, why we need to drop those nodes? Why
  		 * can't we just clean-up the second half of B by putting a
  		 * padding node there? We can, and this works fine with one
  		 * exception which was reproduced with power cut emulation
  		 * testing and happens extremely rarely.
  		 *
  		 * Imagine the file-system is full, we run GC which starts
  		 * moving valid nodes from LEB X to LEB Y (obviously, LEB Y is
  		 * the current GC head LEB). The @c->gc_lnum is -1, which means
  		 * that GC will retain LEB X and will try to continue. Imagine
  		 * that LEB X is currently the dirtiest LEB, and the amount of
  		 * used space in LEB Y is exactly the same as amount of free
  		 * space in LEB X.
  		 *
  		 * And a power cut happens when nodes are moved from LEB X to
  		 * LEB Y. We are here trying to recover LEB Y which is the GC
  		 * head LEB. We find the min. I/O unit B as described above.
  		 * Then we clean-up LEB Y by padding min. I/O unit. And later
  		 * 'ubifs_rcvry_gc_commit()' function fails, because it cannot
  		 * find a dirty LEB which could be GC'd into LEB Y! Even LEB X
  		 * does not match because the amount of valid nodes there does
  		 * not fit the free space in LEB Y any more! And this is
  		 * because of the padding node which we added to LEB Y. The
  		 * user-visible effect of this which I once observed and
  		 * analysed is that we cannot mount the file-system with
  		 * -ENOSPC error.
  		 *
  		 * So obviously, to make sure that situation does not happen we
  		 * should free min. I/O unit B in LEB Y completely and the last
  		 * used min. I/O unit in LEB Y should be A. This is basically
  		 * what the below code tries to do.
  		 */
  		while (offs > min_io_unit)
  			drop_last_node(sleb, &offs);

  	}

  	buf = sbuf + offs;
  	len = c->leb_size - offs;

  	clean_buf(c, &buf, lnum, &offs, &len);

  	ubifs_end_scan(c, sleb, lnum, offs);

  	err = fix_unclean_leb(c, sleb, start);
  	if (err)
  		goto error;

  
  	return sleb;

  corrupted_rescan:
  	/* Re-scan the corrupted data with verbose messages */

  	ubifs_err(c, "corruption %d", ret);

  	ubifs_scan_a_node(c, buf, len, lnum, offs, 1);

  corrupted:
  	ubifs_scanned_corruption(c, lnum, offs, buf);
  	err = -EUCLEAN;
  error:

  	ubifs_err(c, "LEB %d scanning failed", lnum);

  	ubifs_scan_destroy(sleb);
  	return ERR_PTR(err);
  }
  
  /**
   * get_cs_sqnum - get commit start sequence number.
   * @c: UBIFS file-system description object
   * @lnum: LEB number of commit start node
   * @offs: offset of commit start node
   * @cs_sqnum: commit start sequence number is returned here
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  static int get_cs_sqnum(struct ubifs_info *c, int lnum, int offs,
  			unsigned long long *cs_sqnum)
  {
  	struct ubifs_cs_node *cs_node = NULL;
  	int err, ret;
  
  	dbg_rcvry("at %d:%d", lnum, offs);
  	cs_node = kmalloc(UBIFS_CS_NODE_SZ, GFP_KERNEL);
  	if (!cs_node)
  		return -ENOMEM;
  	if (c->leb_size - offs < UBIFS_CS_NODE_SZ)
  		goto out_err;

  	err = ubifs_leb_read(c, lnum, (void *)cs_node, offs,
  			     UBIFS_CS_NODE_SZ, 0);

  	if (err && err != -EBADMSG)
  		goto out_free;
  	ret = ubifs_scan_a_node(c, cs_node, UBIFS_CS_NODE_SZ, lnum, offs, 0);
  	if (ret != SCANNED_A_NODE) {

  		ubifs_err(c, "Not a valid node");

  		goto out_err;
  	}
  	if (cs_node->ch.node_type != UBIFS_CS_NODE) {

  		ubifs_err(c, "Node a CS node, type is %d", cs_node->ch.node_type);

  		goto out_err;
  	}
  	if (le64_to_cpu(cs_node->cmt_no) != c->cmt_no) {

  		ubifs_err(c, "CS node cmt_no %llu != current cmt_no %llu",

  			  (unsigned long long)le64_to_cpu(cs_node->cmt_no),
  			  c->cmt_no);

  		goto out_err;
  	}
  	*cs_sqnum = le64_to_cpu(cs_node->ch.sqnum);
  	dbg_rcvry("commit start sqnum %llu", *cs_sqnum);
  	kfree(cs_node);
  	return 0;
  
  out_err:
  	err = -EINVAL;
  out_free:

  	ubifs_err(c, "failed to get CS sqnum");

  	kfree(cs_node);
  	return err;
  }
  
  /**
   * ubifs_recover_log_leb - scan and recover a log LEB.
   * @c: UBIFS file-system description object
   * @lnum: LEB number
   * @offs: offset
   * @sbuf: LEB-sized buffer to use
   *
   * This function does a scan of a LEB, but caters for errors that might have

   * been caused by unclean reboots from which we are attempting to recover
   * (assume that only the last log LEB can be corrupted by an unclean reboot).

   *
   * This function returns %0 on success and a negative error code on failure.
   */
  struct ubifs_scan_leb *ubifs_recover_log_leb(struct ubifs_info *c, int lnum,
  					     int offs, void *sbuf)
  {
  	struct ubifs_scan_leb *sleb;
  	int next_lnum;
  
  	dbg_rcvry("LEB %d", lnum);
  	next_lnum = lnum + 1;
  	if (next_lnum >= UBIFS_LOG_LNUM + c->log_lebs)
  		next_lnum = UBIFS_LOG_LNUM;
  	if (next_lnum != c->ltail_lnum) {
  		/*
  		 * We can only recover at the end of the log, so check that the
  		 * next log LEB is empty or out of date.
  		 */

  		sleb = ubifs_scan(c, next_lnum, 0, sbuf, 0);

  		if (IS_ERR(sleb))
  			return sleb;
  		if (sleb->nodes_cnt) {
  			struct ubifs_scan_node *snod;
  			unsigned long long cs_sqnum = c->cs_sqnum;
  
  			snod = list_entry(sleb->nodes.next,
  					  struct ubifs_scan_node, list);
  			if (cs_sqnum == 0) {
  				int err;
  
  				err = get_cs_sqnum(c, lnum, offs, &cs_sqnum);
  				if (err) {
  					ubifs_scan_destroy(sleb);
  					return ERR_PTR(err);
  				}
  			}
  			if (snod->sqnum > cs_sqnum) {

  				ubifs_err(c, "unrecoverable log corruption in LEB %d",

  					  lnum);

  				ubifs_scan_destroy(sleb);
  				return ERR_PTR(-EUCLEAN);
  			}
  		}
  		ubifs_scan_destroy(sleb);
  	}

  	return ubifs_recover_leb(c, lnum, offs, sbuf, -1);

  }
  
  /**
   * recover_head - recover a head.
   * @c: UBIFS file-system description object
   * @lnum: LEB number of head to recover
   * @offs: offset of head to recover
   * @sbuf: LEB-sized buffer to use
   *
   * This function ensures that there is no data on the flash at a head location.
   *
   * This function returns %0 on success and a negative error code on failure.
   */

  static int recover_head(struct ubifs_info *c, int lnum, int offs, void *sbuf)

  {

  	int len = c->max_write_size, err;

  	if (offs + len > c->leb_size)
  		len = c->leb_size - offs;
  
  	if (!len)
  		return 0;
  
  	/* Read at the head location and check it is empty flash */

  	err = ubifs_leb_read(c, lnum, sbuf, offs, len, 1);
  	if (err || !is_empty(sbuf, len)) {

  		dbg_rcvry("cleaning head at %d:%d", lnum, offs);
  		if (offs == 0)
  			return ubifs_leb_unmap(c, lnum);

  		err = ubifs_leb_read(c, lnum, sbuf, 0, offs, 1);

  		if (err)
  			return err;

  		return ubifs_leb_change(c, lnum, sbuf, offs);

  	}
  
  	return 0;
  }
  
  /**
   * ubifs_recover_inl_heads - recover index and LPT heads.
   * @c: UBIFS file-system description object
   * @sbuf: LEB-sized buffer to use
   *
   * This function ensures that there is no data on the flash at the index and
   * LPT head locations.
   *
   * This deals with the recovery of a half-completed journal commit. UBIFS is
   * careful never to overwrite the last version of the index or the LPT. Because
   * the index and LPT are wandering trees, data from a half-completed commit will
   * not be referenced anywhere in UBIFS. The data will be either in LEBs that are
   * assumed to be empty and will be unmapped anyway before use, or in the index
   * and LPT heads.
   *
   * This function returns %0 on success and a negative error code on failure.
   */

  int ubifs_recover_inl_heads(struct ubifs_info *c, void *sbuf)

  {
  	int err;

  	ubifs_assert(!c->ro_mount || c->remounting_rw);

  
  	dbg_rcvry("checking index head at %d:%d", c->ihead_lnum, c->ihead_offs);
  	err = recover_head(c, c->ihead_lnum, c->ihead_offs, sbuf);
  	if (err)
  		return err;
  
  	dbg_rcvry("checking LPT head at %d:%d", c->nhead_lnum, c->nhead_offs);

  	return recover_head(c, c->nhead_lnum, c->nhead_offs, sbuf);

  }
  
  /**

   * clean_an_unclean_leb - read and write a LEB to remove corruption.

   * @c: UBIFS file-system description object
   * @ucleb: unclean LEB information
   * @sbuf: LEB-sized buffer to use
   *
   * This function reads a LEB up to a point pre-determined by the mount recovery,
   * checks the nodes, and writes the result back to the flash, thereby cleaning
   * off any following corruption, or non-fatal ECC errors.
   *
   * This function returns %0 on success and a negative error code on failure.
   */

  static int clean_an_unclean_leb(struct ubifs_info *c,

  				struct ubifs_unclean_leb *ucleb, void *sbuf)
  {
  	int err, lnum = ucleb->lnum, offs = 0, len = ucleb->endpt, quiet = 1;
  	void *buf = sbuf;
  
  	dbg_rcvry("LEB %d len %d", lnum, len);
  
  	if (len == 0) {
  		/* Nothing to read, just unmap it */

  		return ubifs_leb_unmap(c, lnum);

  	}

  	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);

  	if (err && err != -EBADMSG)
  		return err;
  
  	while (len >= 8) {
  		int ret;
  
  		cond_resched();
  
  		/* Scan quietly until there is an error */
  		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
  
  		if (ret == SCANNED_A_NODE) {
  			/* A valid node, and not a padding node */
  			struct ubifs_ch *ch = buf;
  			int node_len;
  
  			node_len = ALIGN(le32_to_cpu(ch->len), 8);
  			offs += node_len;
  			buf += node_len;
  			len -= node_len;
  			continue;
  		}
  
  		if (ret > 0) {
  			/* Padding bytes or a valid padding node */
  			offs += ret;
  			buf += ret;
  			len -= ret;
  			continue;
  		}
  
  		if (ret == SCANNED_EMPTY_SPACE) {

  			ubifs_err(c, "unexpected empty space at %d:%d",

  				  lnum, offs);
  			return -EUCLEAN;
  		}
  
  		if (quiet) {
  			/* Redo the last scan but noisily */
  			quiet = 0;
  			continue;
  		}
  
  		ubifs_scanned_corruption(c, lnum, offs, buf);
  		return -EUCLEAN;
  	}
  
  	/* Pad to min_io_size */
  	len = ALIGN(ucleb->endpt, c->min_io_size);
  	if (len > ucleb->endpt) {
  		int pad_len = len - ALIGN(ucleb->endpt, 8);
  
  		if (pad_len > 0) {
  			buf = c->sbuf + len - pad_len;
  			ubifs_pad(c, buf, pad_len);
  		}
  	}
  
  	/* Write back the LEB atomically */

  	err = ubifs_leb_change(c, lnum, sbuf, len);

  	if (err)
  		return err;
  
  	dbg_rcvry("cleaned LEB %d", lnum);
  
  	return 0;
  }
  
  /**
   * ubifs_clean_lebs - clean LEBs recovered during read-only mount.
   * @c: UBIFS file-system description object
   * @sbuf: LEB-sized buffer to use
   *
   * This function cleans a LEB identified during recovery that needs to be
   * written but was not because UBIFS was mounted read-only. This happens when
   * remounting to read-write mode.
   *
   * This function returns %0 on success and a negative error code on failure.
   */

  int ubifs_clean_lebs(struct ubifs_info *c, void *sbuf)

  {
  	dbg_rcvry("recovery");
  	while (!list_empty(&c->unclean_leb_list)) {
  		struct ubifs_unclean_leb *ucleb;
  		int err;
  
  		ucleb = list_entry(c->unclean_leb_list.next,
  				   struct ubifs_unclean_leb, list);
  		err = clean_an_unclean_leb(c, ucleb, sbuf);
  		if (err)
  			return err;
  		list_del(&ucleb->list);
  		kfree(ucleb);
  	}
  	return 0;
  }

  #ifndef __UBOOT__
  /**
   * grab_empty_leb - grab an empty LEB to use as GC LEB and run commit.
   * @c: UBIFS file-system description object
   *
   * This is a helper function for 'ubifs_rcvry_gc_commit()' which grabs an empty
   * LEB to be used as GC LEB (@c->gc_lnum), and then runs the commit. Returns
   * zero in case of success and a negative error code in case of failure.
   */
  static int grab_empty_leb(struct ubifs_info *c)
  {
  	int lnum, err;
  
  	/*
  	 * Note, it is very important to first search for an empty LEB and then
  	 * run the commit, not vice-versa. The reason is that there might be
  	 * only one empty LEB at the moment, the one which has been the
  	 * @c->gc_lnum just before the power cut happened. During the regular
  	 * UBIFS operation (not now) @c->gc_lnum is marked as "taken", so no
  	 * one but GC can grab it. But at this moment this single empty LEB is
  	 * not marked as taken, so if we run commit - what happens? Right, the
  	 * commit will grab it and write the index there. Remember that the
  	 * index always expands as long as there is free space, and it only
  	 * starts consolidating when we run out of space.
  	 *
  	 * IOW, if we run commit now, we might not be able to find a free LEB
  	 * after this.
  	 */
  	lnum = ubifs_find_free_leb_for_idx(c);
  	if (lnum < 0) {

  		ubifs_err(c, "could not find an empty LEB");

  		ubifs_dump_lprops(c);
  		ubifs_dump_budg(c, &c->bi);
  		return lnum;
  	}
  
  	/* Reset the index flag */
  	err = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
  				  LPROPS_INDEX, 0);
  	if (err)
  		return err;
  
  	c->gc_lnum = lnum;
  	dbg_rcvry("found empty LEB %d, run commit", lnum);
  
  	return ubifs_run_commit(c);
  }
  
  /**
   * ubifs_rcvry_gc_commit - recover the GC LEB number and run the commit.
   * @c: UBIFS file-system description object
   *
   * Out-of-place garbage collection requires always one empty LEB with which to
   * start garbage collection. The LEB number is recorded in c->gc_lnum and is
   * written to the master node on unmounting. In the case of an unclean unmount
   * the value of gc_lnum recorded in the master node is out of date and cannot
   * be used. Instead, recovery must allocate an empty LEB for this purpose.
   * However, there may not be enough empty space, in which case it must be
   * possible to GC the dirtiest LEB into the GC head LEB.
   *
   * This function also runs the commit which causes the TNC updates from
   * size-recovery and orphans to be written to the flash. That is important to
   * ensure correct replay order for subsequent mounts.
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  int ubifs_rcvry_gc_commit(struct ubifs_info *c)
  {
  	struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
  	struct ubifs_lprops lp;
  	int err;
  
  	dbg_rcvry("GC head LEB %d, offs %d", wbuf->lnum, wbuf->offs);
  
  	c->gc_lnum = -1;
  	if (wbuf->lnum == -1 || wbuf->offs == c->leb_size)
  		return grab_empty_leb(c);
  
  	err = ubifs_find_dirty_leb(c, &lp, wbuf->offs, 2);
  	if (err) {
  		if (err != -ENOSPC)
  			return err;
  
  		dbg_rcvry("could not find a dirty LEB");
  		return grab_empty_leb(c);
  	}
  
  	ubifs_assert(!(lp.flags & LPROPS_INDEX));
  	ubifs_assert(lp.free + lp.dirty >= wbuf->offs);
  
  	/*
  	 * We run the commit before garbage collection otherwise subsequent
  	 * mounts will see the GC and orphan deletion in a different order.
  	 */
  	dbg_rcvry("committing");
  	err = ubifs_run_commit(c);
  	if (err)
  		return err;
  
  	dbg_rcvry("GC'ing LEB %d", lp.lnum);
  	mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
  	err = ubifs_garbage_collect_leb(c, &lp);
  	if (err >= 0) {
  		int err2 = ubifs_wbuf_sync_nolock(wbuf);
  
  		if (err2)
  			err = err2;
  	}
  	mutex_unlock(&wbuf->io_mutex);
  	if (err < 0) {

  		ubifs_err(c, "GC failed, error %d", err);

  		if (err == -EAGAIN)
  			err = -EINVAL;
  		return err;
  	}
  
  	ubifs_assert(err == LEB_RETAINED);
  	if (err != LEB_RETAINED)
  		return -EINVAL;
  
  	err = ubifs_leb_unmap(c, c->gc_lnum);
  	if (err)
  		return err;
  
  	dbg_rcvry("allocated LEB %d for GC", lp.lnum);
  	return 0;
  }
  #else
  int ubifs_rcvry_gc_commit(struct ubifs_info *c)
  {
  	return 0;
  }
  #endif

  /**
   * struct size_entry - inode size information for recovery.
   * @rb: link in the RB-tree of sizes
   * @inum: inode number
   * @i_size: size on inode
   * @d_size: maximum size based on data nodes
   * @exists: indicates whether the inode exists
   * @inode: inode if pinned in memory awaiting rw mode to fix it
   */
  struct size_entry {
  	struct rb_node rb;
  	ino_t inum;
  	loff_t i_size;
  	loff_t d_size;
  	int exists;
  	struct inode *inode;
  };
  
  /**
   * add_ino - add an entry to the size tree.
   * @c: UBIFS file-system description object
   * @inum: inode number
   * @i_size: size on inode
   * @d_size: maximum size based on data nodes
   * @exists: indicates whether the inode exists
   */
  static int add_ino(struct ubifs_info *c, ino_t inum, loff_t i_size,
  		   loff_t d_size, int exists)
  {
  	struct rb_node **p = &c->size_tree.rb_node, *parent = NULL;
  	struct size_entry *e;
  
  	while (*p) {
  		parent = *p;
  		e = rb_entry(parent, struct size_entry, rb);
  		if (inum < e->inum)
  			p = &(*p)->rb_left;
  		else
  			p = &(*p)->rb_right;
  	}
  
  	e = kzalloc(sizeof(struct size_entry), GFP_KERNEL);
  	if (!e)
  		return -ENOMEM;
  
  	e->inum = inum;
  	e->i_size = i_size;
  	e->d_size = d_size;
  	e->exists = exists;
  
  	rb_link_node(&e->rb, parent, p);
  	rb_insert_color(&e->rb, &c->size_tree);
  
  	return 0;
  }
  
  /**
   * find_ino - find an entry on the size tree.
   * @c: UBIFS file-system description object
   * @inum: inode number
   */
  static struct size_entry *find_ino(struct ubifs_info *c, ino_t inum)
  {
  	struct rb_node *p = c->size_tree.rb_node;
  	struct size_entry *e;
  
  	while (p) {
  		e = rb_entry(p, struct size_entry, rb);
  		if (inum < e->inum)
  			p = p->rb_left;
  		else if (inum > e->inum)
  			p = p->rb_right;
  		else
  			return e;
  	}
  	return NULL;
  }
  
  /**
   * remove_ino - remove an entry from the size tree.
   * @c: UBIFS file-system description object
   * @inum: inode number
   */
  static void remove_ino(struct ubifs_info *c, ino_t inum)
  {
  	struct size_entry *e = find_ino(c, inum);
  
  	if (!e)
  		return;
  	rb_erase(&e->rb, &c->size_tree);
  	kfree(e);
  }
  
  /**

   * ubifs_destroy_size_tree - free resources related to the size tree.
   * @c: UBIFS file-system description object
   */
  void ubifs_destroy_size_tree(struct ubifs_info *c)
  {
  	struct size_entry *e, *n;
  
  	rbtree_postorder_for_each_entry_safe(e, n, &c->size_tree, rb) {
  		if (e->inode)
  			iput(e->inode);
  		kfree(e);
  	}
  
  	c->size_tree = RB_ROOT;
  }
  
  /**

   * ubifs_recover_size_accum - accumulate inode sizes for recovery.
   * @c: UBIFS file-system description object
   * @key: node key
   * @deletion: node is for a deletion
   * @new_size: inode size
   *
   * This function has two purposes:
   *     1) to ensure there are no data nodes that fall outside the inode size
   *     2) to ensure there are no data nodes for inodes that do not exist
   * To accomplish those purposes, a rb-tree is constructed containing an entry
   * for each inode number in the journal that has not been deleted, and recording
   * the size from the inode node, the maximum size of any data node (also altered
   * by truncations) and a flag indicating a inode number for which no inode node
   * was present in the journal.
   *
   * Note that there is still the possibility that there are data nodes that have
   * been committed that are beyond the inode size, however the only way to find
   * them would be to scan the entire index. Alternatively, some provision could
   * be made to record the size of inodes at the start of commit, which would seem
   * very cumbersome for a scenario that is quite unlikely and the only negative
   * consequence of which is wasted space.
   *
   * This functions returns %0 on success and a negative error code on failure.
   */
  int ubifs_recover_size_accum(struct ubifs_info *c, union ubifs_key *key,
  			     int deletion, loff_t new_size)
  {
  	ino_t inum = key_inum(c, key);
  	struct size_entry *e;
  	int err;
  
  	switch (key_type(c, key)) {
  	case UBIFS_INO_KEY:
  		if (deletion)
  			remove_ino(c, inum);
  		else {
  			e = find_ino(c, inum);
  			if (e) {
  				e->i_size = new_size;
  				e->exists = 1;
  			} else {
  				err = add_ino(c, inum, new_size, 0, 1);
  				if (err)
  					return err;
  			}
  		}
  		break;
  	case UBIFS_DATA_KEY:
  		e = find_ino(c, inum);
  		if (e) {
  			if (new_size > e->d_size)
  				e->d_size = new_size;
  		} else {
  			err = add_ino(c, inum, 0, new_size, 0);
  			if (err)
  				return err;
  		}
  		break;
  	case UBIFS_TRUN_KEY:
  		e = find_ino(c, inum);
  		if (e)
  			e->d_size = new_size;
  		break;
  	}
  	return 0;
  }

  #ifndef __UBOOT__
  /**
   * fix_size_in_place - fix inode size in place on flash.
   * @c: UBIFS file-system description object
   * @e: inode size information for recovery
   */
  static int fix_size_in_place(struct ubifs_info *c, struct size_entry *e)
  {
  	struct ubifs_ino_node *ino = c->sbuf;
  	unsigned char *p;
  	union ubifs_key key;
  	int err, lnum, offs, len;
  	loff_t i_size;
  	uint32_t crc;
  
  	/* Locate the inode node LEB number and offset */
  	ino_key_init(c, &key, e->inum);
  	err = ubifs_tnc_locate(c, &key, ino, &lnum, &offs);
  	if (err)
  		goto out;
  	/*
  	 * If the size recorded on the inode node is greater than the size that
  	 * was calculated from nodes in the journal then don't change the inode.
  	 */
  	i_size = le64_to_cpu(ino->size);
  	if (i_size >= e->d_size)
  		return 0;
  	/* Read the LEB */
  	err = ubifs_leb_read(c, lnum, c->sbuf, 0, c->leb_size, 1);
  	if (err)
  		goto out;
  	/* Change the size field and recalculate the CRC */
  	ino = c->sbuf + offs;
  	ino->size = cpu_to_le64(e->d_size);
  	len = le32_to_cpu(ino->ch.len);
  	crc = crc32(UBIFS_CRC32_INIT, (void *)ino + 8, len - 8);
  	ino->ch.crc = cpu_to_le32(crc);
  	/* Work out where data in the LEB ends and free space begins */
  	p = c->sbuf;
  	len = c->leb_size - 1;
  	while (p[len] == 0xff)
  		len -= 1;
  	len = ALIGN(len + 1, c->min_io_size);
  	/* Atomically write the fixed LEB back again */
  	err = ubifs_leb_change(c, lnum, c->sbuf, len);
  	if (err)
  		goto out;
  	dbg_rcvry("inode %lu at %d:%d size %lld -> %lld",
  		  (unsigned long)e->inum, lnum, offs, i_size, e->d_size);
  	return 0;
  
  out:

  	ubifs_warn(c, "inode %lu failed to fix size %lld -> %lld error %d",

  		   (unsigned long)e->inum, e->i_size, e->d_size, err);
  	return err;
  }
  #endif

  /**
   * ubifs_recover_size - recover inode size.
   * @c: UBIFS file-system description object
   *
   * This function attempts to fix inode size discrepancies identified by the
   * 'ubifs_recover_size_accum()' function.
   *
   * This functions returns %0 on success and a negative error code on failure.
   */
  int ubifs_recover_size(struct ubifs_info *c)
  {
  	struct rb_node *this = rb_first(&c->size_tree);
  
  	while (this) {
  		struct size_entry *e;
  		int err;
  
  		e = rb_entry(this, struct size_entry, rb);
  		if (!e->exists) {
  			union ubifs_key key;
  
  			ino_key_init(c, &key, e->inum);
  			err = ubifs_tnc_lookup(c, &key, c->sbuf);
  			if (err && err != -ENOENT)
  				return err;
  			if (err == -ENOENT) {
  				/* Remove data nodes that have no inode */
  				dbg_rcvry("removing ino %lu",
  					  (unsigned long)e->inum);
  				err = ubifs_tnc_remove_ino(c, e->inum);
  				if (err)
  					return err;
  			} else {
  				struct ubifs_ino_node *ino = c->sbuf;
  
  				e->exists = 1;
  				e->i_size = le64_to_cpu(ino->size);
  			}
  		}

  		if (e->exists && e->i_size < e->d_size) {

  			if (c->ro_mount) {

  				/* Fix the inode size and pin it in memory */
  				struct inode *inode;

  				struct ubifs_inode *ui;
  
  				ubifs_assert(!e->inode);

  
  				inode = ubifs_iget(c->vfs_sb, e->inum);
  				if (IS_ERR(inode))
  					return PTR_ERR(inode);

  
  				ui = ubifs_inode(inode);

  				if (inode->i_size < e->d_size) {
  					dbg_rcvry("ino %lu size %lld -> %lld",
  						  (unsigned long)e->inum,

  						  inode->i_size, e->d_size);

  					inode->i_size = e->d_size;

  					ui->ui_size = e->d_size;
  					ui->synced_i_size = e->d_size;

  					e->inode = inode;
  					this = rb_next(this);
  					continue;
  				}
  				iput(inode);

  #ifndef __UBOOT__
  			} else {
  				/* Fix the size in place */
  				err = fix_size_in_place(c, e);
  				if (err)
  					return err;
  				if (e->inode)
  					iput(e->inode);
  #endif

  			}
  		}

  		this = rb_next(this);
  		rb_erase(&e->rb, &c->size_tree);
  		kfree(e);
  	}

  	return 0;
  }