Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1588 insertions, 0 deletions

diff --git a/fs/ubifs/recovery.c b/fs/ubifs/recovery.c
new file mode 100644
index 000000000..f0d51dd21
--- /dev/null
+++ b/fs/ubifs/recovery.c
@@ -0,0 +1,1588 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation
+ *
+ * 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.
+ */
+
+#include <linux/crc32.h>
+#include <linux/slab.h>
+#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);
+
+	err = ubifs_prepare_node_hmac(c, mst, UBIFS_MST_NODE_SZ,
+				      offsetof(struct ubifs_mst_node, hmac), 1);
+	if (err)
+		goto out;
+	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 (ubifs_compare_master_node(c, mst1, mst2))
+					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);
+	} 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;
+	}
+
+	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, c->leb_size - ((void *)mst1 - buf1));
+	}
+	if (mst2) {
+		ubifs_err(c, "dumping second master node");
+		ubifs_dump_node(c, mst2, c->leb_size - ((void *)mst2 - buf2));
+	}
+	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;
+
+	dbg_rcvry("cleaning corruption at %d:%d", lnum, *offs);
+
+	ubifs_assert(c, !(*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, len, 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);
+	} 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;
+		}
+	}
+	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(c, 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, 0);
+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, "Not 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, !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;
+}
+
+/**
+ * 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(c, !(lp.flags & LPROPS_INDEX));
+	ubifs_assert(c, 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(c, 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;
+}
+
+/**
+ * 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) {
+		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;
+}
+
+/**
+ * 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;
+}
+
+/**
+ * inode_fix_size - fix inode size
+ * @c: UBIFS file-system description object
+ * @e: inode size information for recovery
+ */
+static int inode_fix_size(struct ubifs_info *c, struct size_entry *e)
+{
+	struct inode *inode;
+	struct ubifs_inode *ui;
+	int err;
+
+	if (c->ro_mount)
+		ubifs_assert(c, !e->inode);
+
+	if (e->inode) {
+		/* Remounting rw, pick up inode we stored earlier */
+		inode = e->inode;
+	} else {
+		inode = ubifs_iget(c->vfs_sb, e->inum);
+		if (IS_ERR(inode))
+			return PTR_ERR(inode);
+
+		if (inode->i_size >= e->d_size) {
+			/*
+			 * The original inode in the index already has a size
+			 * big enough, nothing to do
+			 */
+			iput(inode);
+			return 0;
+		}
+
+		dbg_rcvry("ino %lu size %lld -> %lld",
+			  (unsigned long)e->inum,
+			  inode->i_size, e->d_size);
+
+		ui = ubifs_inode(inode);
+
+		inode->i_size = e->d_size;
+		ui->ui_size = e->d_size;
+		ui->synced_i_size = e->d_size;
+
+		e->inode = inode;
+	}
+
+	/*
+	 * In readonly mode just keep the inode pinned in memory until we go
+	 * readwrite. In readwrite mode write the inode to the journal with the
+	 * fixed size.
+	 */
+	if (c->ro_mount)
+		return 0;
+
+	err = ubifs_jnl_write_inode(c, inode);
+
+	iput(inode);
+
+	if (err)
+		return err;
+
+	rb_erase(&e->rb, &c->size_tree);
+	kfree(e);
+
+	return 0;
+}
+
+/**
+ * ubifs_recover_size - recover inode size.
+ * @c: UBIFS file-system description object
+ * @in_place: If true, do a in-place size fixup
+ *
+ * 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, bool in_place)
+{
+	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);
+
+		this = rb_next(this);
+
+		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) {
+			ubifs_assert(c, !(c->ro_mount && in_place));
+
+			/*
+			 * We found data that is outside the found inode size,
+			 * fixup the inode size
+			 */
+
+			if (in_place) {
+				err = fix_size_in_place(c, e);
+				if (err)
+					return err;
+				iput(e->inode);
+			} else {
+				err = inode_fix_size(c, e);
+				if (err)
+					return err;
+				continue;
+			}
+		}
+
+		rb_erase(&e->rb, &c->size_tree);
+		kfree(e);
+	}
+
+	return 0;
+}