Initial import

1 files changed, 1082 insertions, 0 deletions

diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
new file mode 100644
index 000000000..3ca454013
--- /dev/null
+++ b/fs/ubifs/replay.c
@@ -0,0 +1,1082 @@
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors: Adrian Hunter
+ *          Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file contains journal replay code. It runs when the file-system is being
+ * mounted and requires no locking.
+ *
+ * The larger is the journal, the longer it takes to scan it, so the longer it
+ * takes to mount UBIFS. This is why the journal has limited size which may be
+ * changed depending on the system requirements. But a larger journal gives
+ * faster I/O speed because it writes the index less frequently. So this is a
+ * trade-off. Also, the journal is indexed by the in-memory index (TNC), so the
+ * larger is the journal, the more memory its index may consume.
+ */
+
+#include "ubifs.h"
+#include <linux/list_sort.h>
+
+/**
+ * struct replay_entry - replay list entry.
+ * @lnum: logical eraseblock number of the node
+ * @offs: node offset
+ * @len: node length
+ * @deletion: non-zero if this entry corresponds to a node deletion
+ * @sqnum: node sequence number
+ * @list: links the replay list
+ * @key: node key
+ * @nm: directory entry name
+ * @old_size: truncation old size
+ * @new_size: truncation new size
+ *
+ * The replay process first scans all buds and builds the replay list, then
+ * sorts the replay list in nodes sequence number order, and then inserts all
+ * the replay entries to the TNC.
+ */
+struct replay_entry {
+	int lnum;
+	int offs;
+	int len;
+	unsigned int deletion:1;
+	unsigned long long sqnum;
+	struct list_head list;
+	union ubifs_key key;
+	union {
+		struct qstr nm;
+		struct {
+			loff_t old_size;
+			loff_t new_size;
+		};
+	};
+};
+
+/**
+ * struct bud_entry - entry in the list of buds to replay.
+ * @list: next bud in the list
+ * @bud: bud description object
+ * @sqnum: reference node sequence number
+ * @free: free bytes in the bud
+ * @dirty: dirty bytes in the bud
+ */
+struct bud_entry {
+	struct list_head list;
+	struct ubifs_bud *bud;
+	unsigned long long sqnum;
+	int free;
+	int dirty;
+};
+
+/**
+ * set_bud_lprops - set free and dirty space used by a bud.
+ * @c: UBIFS file-system description object
+ * @b: bud entry which describes the bud
+ *
+ * This function makes sure the LEB properties of bud @b are set correctly
+ * after the replay. Returns zero in case of success and a negative error code
+ * in case of failure.
+ */
+static int set_bud_lprops(struct ubifs_info *c, struct bud_entry *b)
+{
+	const struct ubifs_lprops *lp;
+	int err = 0, dirty;
+
+	ubifs_get_lprops(c);
+
+	lp = ubifs_lpt_lookup_dirty(c, b->bud->lnum);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	dirty = lp->dirty;
+	if (b->bud->start == 0 && (lp->free != c->leb_size || lp->dirty != 0)) {
+		/*
+		 * The LEB was added to the journal with a starting offset of
+		 * zero which means the LEB must have been empty. The LEB
+		 * property values should be @lp->free == @c->leb_size and
+		 * @lp->dirty == 0, but that is not the case. The reason is that
+		 * the LEB had been garbage collected before it became the bud,
+		 * and there was not commit inbetween. The garbage collector
+		 * resets the free and dirty space without recording it
+		 * anywhere except lprops, so if there was no commit then
+		 * lprops does not have that information.
+		 *
+		 * We do not need to adjust free space because the scan has told
+		 * us the exact value which is recorded in the replay entry as
+		 * @b->free.
+		 *
+		 * However we do need to subtract from the dirty space the
+		 * amount of space that the garbage collector reclaimed, which
+		 * is the whole LEB minus the amount of space that was free.
+		 */
+		dbg_mnt("bud LEB %d was GC'd (%d free, %d dirty)", b->bud->lnum,
+			lp->free, lp->dirty);
+		dbg_gc("bud LEB %d was GC'd (%d free, %d dirty)", b->bud->lnum,
+			lp->free, lp->dirty);
+		dirty -= c->leb_size - lp->free;
+		/*
+		 * If the replay order was perfect the dirty space would now be
+		 * zero. The order is not perfect because the journal heads
+		 * race with each other. This is not a problem but is does mean
+		 * that the dirty space may temporarily exceed c->leb_size
+		 * during the replay.
+		 */
+		if (dirty != 0)
+			dbg_mnt("LEB %d lp: %d free %d dirty replay: %d free %d dirty",
+				b->bud->lnum, lp->free, lp->dirty, b->free,
+				b->dirty);
+	}
+	lp = ubifs_change_lp(c, lp, b->free, dirty + b->dirty,
+			     lp->flags | LPROPS_TAKEN, 0);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	/* Make sure the journal head points to the latest bud */
+	err = ubifs_wbuf_seek_nolock(&c->jheads[b->bud->jhead].wbuf,
+				     b->bud->lnum, c->leb_size - b->free);
+
+out:
+	ubifs_release_lprops(c);
+	return err;
+}
+
+/**
+ * set_buds_lprops - set free and dirty space for all replayed buds.
+ * @c: UBIFS file-system description object
+ *
+ * This function sets LEB properties for all replayed buds. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+static int set_buds_lprops(struct ubifs_info *c)
+{
+	struct bud_entry *b;
+	int err;
+
+	list_for_each_entry(b, &c->replay_buds, list) {
+		err = set_bud_lprops(c, b);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * trun_remove_range - apply a replay entry for a truncation to the TNC.
+ * @c: UBIFS file-system description object
+ * @r: replay entry of truncation
+ */
+static int trun_remove_range(struct ubifs_info *c, struct replay_entry *r)
+{
+	unsigned min_blk, max_blk;
+	union ubifs_key min_key, max_key;
+	ino_t ino;
+
+	min_blk = r->new_size / UBIFS_BLOCK_SIZE;
+	if (r->new_size & (UBIFS_BLOCK_SIZE - 1))
+		min_blk += 1;
+
+	max_blk = r->old_size / UBIFS_BLOCK_SIZE;
+	if ((r->old_size & (UBIFS_BLOCK_SIZE - 1)) == 0)
+		max_blk -= 1;
+
+	ino = key_inum(c, &r->key);
+
+	data_key_init(c, &min_key, ino, min_blk);
+	data_key_init(c, &max_key, ino, max_blk);
+
+	return ubifs_tnc_remove_range(c, &min_key, &max_key);
+}
+
+/**
+ * apply_replay_entry - apply a replay entry to the TNC.
+ * @c: UBIFS file-system description object
+ * @r: replay entry to apply
+ *
+ * Apply a replay entry to the TNC.
+ */
+static int apply_replay_entry(struct ubifs_info *c, struct replay_entry *r)
+{
+	int err;
+
+	dbg_mntk(&r->key, "LEB %d:%d len %d deletion %d sqnum %llu key ",
+		 r->lnum, r->offs, r->len, r->deletion, r->sqnum);
+
+	/* Set c->replay_sqnum to help deal with dangling branches. */
+	c->replay_sqnum = r->sqnum;
+
+	if (is_hash_key(c, &r->key)) {
+		if (r->deletion)
+			err = ubifs_tnc_remove_nm(c, &r->key, &r->nm);
+		else
+			err = ubifs_tnc_add_nm(c, &r->key, r->lnum, r->offs,
+					       r->len, &r->nm);
+	} else {
+		if (r->deletion)
+			switch (key_type(c, &r->key)) {
+			case UBIFS_INO_KEY:
+			{
+				ino_t inum = key_inum(c, &r->key);
+
+				err = ubifs_tnc_remove_ino(c, inum);
+				break;
+			}
+			case UBIFS_TRUN_KEY:
+				err = trun_remove_range(c, r);
+				break;
+			default:
+				err = ubifs_tnc_remove(c, &r->key);
+				break;
+			}
+		else
+			err = ubifs_tnc_add(c, &r->key, r->lnum, r->offs,
+					    r->len);
+		if (err)
+			return err;
+
+		if (c->need_recovery)
+			err = ubifs_recover_size_accum(c, &r->key, r->deletion,
+						       r->new_size);
+	}
+
+	return err;
+}
+
+/**
+ * replay_entries_cmp - compare 2 replay entries.
+ * @priv: UBIFS file-system description object
+ * @a: first replay entry
+ * @a: second replay entry
+ *
+ * This is a comparios function for 'list_sort()' which compares 2 replay
+ * entries @a and @b by comparing their sequence numer.  Returns %1 if @a has
+ * greater sequence number and %-1 otherwise.
+ */
+static int replay_entries_cmp(void *priv, struct list_head *a,
+			      struct list_head *b)
+{
+	struct replay_entry *ra, *rb;
+
+	cond_resched();
+	if (a == b)
+		return 0;
+
+	ra = list_entry(a, struct replay_entry, list);
+	rb = list_entry(b, struct replay_entry, list);
+	ubifs_assert(ra->sqnum != rb->sqnum);
+	if (ra->sqnum > rb->sqnum)
+		return 1;
+	return -1;
+}
+
+/**
+ * apply_replay_list - apply the replay list to the TNC.
+ * @c: UBIFS file-system description object
+ *
+ * Apply all entries in the replay list to the TNC. Returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+static int apply_replay_list(struct ubifs_info *c)
+{
+	struct replay_entry *r;
+	int err;
+
+	list_sort(c, &c->replay_list, &replay_entries_cmp);
+
+	list_for_each_entry(r, &c->replay_list, list) {
+		cond_resched();
+
+		err = apply_replay_entry(c, r);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * destroy_replay_list - destroy the replay.
+ * @c: UBIFS file-system description object
+ *
+ * Destroy the replay list.
+ */
+static void destroy_replay_list(struct ubifs_info *c)
+{
+	struct replay_entry *r, *tmp;
+
+	list_for_each_entry_safe(r, tmp, &c->replay_list, list) {
+		if (is_hash_key(c, &r->key))
+			kfree(r->nm.name);
+		list_del(&r->list);
+		kfree(r);
+	}
+}
+
+/**
+ * insert_node - insert a node to the replay list
+ * @c: UBIFS file-system description object
+ * @lnum: node logical eraseblock number
+ * @offs: node offset
+ * @len: node length
+ * @key: node key
+ * @sqnum: sequence number
+ * @deletion: non-zero if this is a deletion
+ * @used: number of bytes in use in a LEB
+ * @old_size: truncation old size
+ * @new_size: truncation new size
+ *
+ * This function inserts a scanned non-direntry node to the replay list. The
+ * replay list contains @struct replay_entry elements, and we sort this list in
+ * sequence number order before applying it. The replay list is applied at the
+ * very end of the replay process. Since the list is sorted in sequence number
+ * order, the older modifications are applied first. This function returns zero
+ * in case of success and a negative error code in case of failure.
+ */
+static int insert_node(struct ubifs_info *c, int lnum, int offs, int len,
+		       union ubifs_key *key, unsigned long long sqnum,
+		       int deletion, int *used, loff_t old_size,
+		       loff_t new_size)
+{
+	struct replay_entry *r;
+
+	dbg_mntk(key, "add LEB %d:%d, key ", lnum, offs);
+
+	if (key_inum(c, key) >= c->highest_inum)
+		c->highest_inum = key_inum(c, key);
+
+	r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	if (!deletion)
+		*used += ALIGN(len, 8);
+	r->lnum = lnum;
+	r->offs = offs;
+	r->len = len;
+	r->deletion = !!deletion;
+	r->sqnum = sqnum;
+	key_copy(c, key, &r->key);
+	r->old_size = old_size;
+	r->new_size = new_size;
+
+	list_add_tail(&r->list, &c->replay_list);
+	return 0;
+}
+
+/**
+ * insert_dent - insert a directory entry node into the replay list.
+ * @c: UBIFS file-system description object
+ * @lnum: node logical eraseblock number
+ * @offs: node offset
+ * @len: node length
+ * @key: node key
+ * @name: directory entry name
+ * @nlen: directory entry name length
+ * @sqnum: sequence number
+ * @deletion: non-zero if this is a deletion
+ * @used: number of bytes in use in a LEB
+ *
+ * This function inserts a scanned directory entry node or an extended
+ * attribute entry to the replay list. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int insert_dent(struct ubifs_info *c, int lnum, int offs, int len,
+		       union ubifs_key *key, const char *name, int nlen,
+		       unsigned long long sqnum, int deletion, int *used)
+{
+	struct replay_entry *r;
+	char *nbuf;
+
+	dbg_mntk(key, "add LEB %d:%d, key ", lnum, offs);
+	if (key_inum(c, key) >= c->highest_inum)
+		c->highest_inum = key_inum(c, key);
+
+	r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	nbuf = kmalloc(nlen + 1, GFP_KERNEL);
+	if (!nbuf) {
+		kfree(r);
+		return -ENOMEM;
+	}
+
+	if (!deletion)
+		*used += ALIGN(len, 8);
+	r->lnum = lnum;
+	r->offs = offs;
+	r->len = len;
+	r->deletion = !!deletion;
+	r->sqnum = sqnum;
+	key_copy(c, key, &r->key);
+	r->nm.len = nlen;
+	memcpy(nbuf, name, nlen);
+	nbuf[nlen] = '\0';
+	r->nm.name = nbuf;
+
+	list_add_tail(&r->list, &c->replay_list);
+	return 0;
+}
+
+/**
+ * ubifs_validate_entry - validate directory or extended attribute entry node.
+ * @c: UBIFS file-system description object
+ * @dent: the node to validate
+ *
+ * This function validates directory or extended attribute entry node @dent.
+ * Returns zero if the node is all right and a %-EINVAL if not.
+ */
+int ubifs_validate_entry(struct ubifs_info *c,
+			 const struct ubifs_dent_node *dent)
+{
+	int key_type = key_type_flash(c, dent->key);
+	int nlen = le16_to_cpu(dent->nlen);
+
+	if (le32_to_cpu(dent->ch.len) != nlen + UBIFS_DENT_NODE_SZ + 1 ||
+	    dent->type >= UBIFS_ITYPES_CNT ||
+	    nlen > UBIFS_MAX_NLEN || dent->name[nlen] != 0 ||
+	    strnlen(dent->name, nlen) != nlen ||
+	    le64_to_cpu(dent->inum) > MAX_INUM) {
+		ubifs_err(c, "bad %s node", key_type == UBIFS_DENT_KEY ?
+			  "directory entry" : "extended attribute entry");
+		return -EINVAL;
+	}
+
+	if (key_type != UBIFS_DENT_KEY && key_type != UBIFS_XENT_KEY) {
+		ubifs_err(c, "bad key type %d", key_type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * is_last_bud - check if the bud is the last in the journal head.
+ * @c: UBIFS file-system description object
+ * @bud: bud description object
+ *
+ * This function checks if bud @bud is the last bud in its journal head. This
+ * information is then used by 'replay_bud()' to decide whether the bud can
+ * have corruptions or not. Indeed, only last buds can be corrupted by power
+ * cuts. Returns %1 if this is the last bud, and %0 if not.
+ */
+static int is_last_bud(struct ubifs_info *c, struct ubifs_bud *bud)
+{
+	struct ubifs_jhead *jh = &c->jheads[bud->jhead];
+	struct ubifs_bud *next;
+	uint32_t data;
+	int err;
+
+	if (list_is_last(&bud->list, &jh->buds_list))
+		return 1;
+
+	/*
+	 * The following is a quirk to make sure we work correctly with UBIFS
+	 * images used with older UBIFS.
+	 *
+	 * Normally, the last bud will be the last in the journal head's list
+	 * of bud. However, there is one exception if the UBIFS image belongs
+	 * to older UBIFS. This is fairly unlikely: one would need to use old
+	 * UBIFS, then have a power cut exactly at the right point, and then
+	 * try to mount this image with new UBIFS.
+	 *
+	 * The exception is: it is possible to have 2 buds A and B, A goes
+	 * before B, and B is the last, bud B is contains no data, and bud A is
+	 * corrupted at the end. The reason is that in older versions when the
+	 * journal code switched the next bud (from A to B), it first added a
+	 * log reference node for the new bud (B), and only after this it
+	 * synchronized the write-buffer of current bud (A). But later this was
+	 * changed and UBIFS started to always synchronize the write-buffer of
+	 * the bud (A) before writing the log reference for the new bud (B).
+	 *
+	 * But because older UBIFS always synchronized A's write-buffer before
+	 * writing to B, we can recognize this exceptional situation but
+	 * checking the contents of bud B - if it is empty, then A can be
+	 * treated as the last and we can recover it.
+	 *
+	 * TODO: remove this piece of code in a couple of years (today it is
+	 * 16.05.2011).
+	 */
+	next = list_entry(bud->list.next, struct ubifs_bud, list);
+	if (!list_is_last(&next->list, &jh->buds_list))
+		return 0;
+
+	err = ubifs_leb_read(c, next->lnum, (char *)&data, next->start, 4, 1);
+	if (err)
+		return 0;
+
+	return data == 0xFFFFFFFF;
+}
+
+/**
+ * replay_bud - replay a bud logical eraseblock.
+ * @c: UBIFS file-system description object
+ * @b: bud entry which describes the bud
+ *
+ * This function replays bud @bud, recovers it if needed, and adds all nodes
+ * from this bud to the replay list. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int replay_bud(struct ubifs_info *c, struct bud_entry *b)
+{
+	int is_last = is_last_bud(c, b->bud);
+	int err = 0, used = 0, lnum = b->bud->lnum, offs = b->bud->start;
+	struct ubifs_scan_leb *sleb;
+	struct ubifs_scan_node *snod;
+
+	dbg_mnt("replay bud LEB %d, head %d, offs %d, is_last %d",
+		lnum, b->bud->jhead, offs, is_last);
+
+	if (c->need_recovery && is_last)
+		/*
+		 * Recover only last LEBs in the journal heads, because power
+		 * cuts may cause corruptions only in these LEBs, because only
+		 * these LEBs could possibly be written to at the power cut
+		 * time.
+		 */
+		sleb = ubifs_recover_leb(c, lnum, offs, c->sbuf, b->bud->jhead);
+	else
+		sleb = ubifs_scan(c, lnum, offs, c->sbuf, 0);
+	if (IS_ERR(sleb))
+		return PTR_ERR(sleb);
+
+	/*
+	 * The bud does not have to start from offset zero - the beginning of
+	 * the 'lnum' LEB may contain previously committed data. One of the
+	 * things we have to do in replay is to correctly update lprops with
+	 * newer information about this LEB.
+	 *
+	 * At this point lprops thinks that this LEB has 'c->leb_size - offs'
+	 * bytes of free space because it only contain information about
+	 * committed data.
+	 *
+	 * But we know that real amount of free space is 'c->leb_size -
+	 * sleb->endpt', and the space in the 'lnum' LEB between 'offs' and
+	 * 'sleb->endpt' is used by bud data. We have to correctly calculate
+	 * how much of these data are dirty and update lprops with this
+	 * information.
+	 *
+	 * The dirt in that LEB region is comprised of padding nodes, deletion
+	 * nodes, truncation nodes and nodes which are obsoleted by subsequent
+	 * nodes in this LEB. So instead of calculating clean space, we
+	 * calculate used space ('used' variable).
+	 */
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+		int deletion = 0;
+
+		cond_resched();
+
+		if (snod->sqnum >= SQNUM_WATERMARK) {
+			ubifs_err(c, "file system's life ended");
+			goto out_dump;
+		}
+
+		if (snod->sqnum > c->max_sqnum)
+			c->max_sqnum = snod->sqnum;
+
+		switch (snod->type) {
+		case UBIFS_INO_NODE:
+		{
+			struct ubifs_ino_node *ino = snod->node;
+			loff_t new_size = le64_to_cpu(ino->size);
+
+			if (le32_to_cpu(ino->nlink) == 0)
+				deletion = 1;
+			err = insert_node(c, lnum, snod->offs, snod->len,
+					  &snod->key, snod->sqnum, deletion,
+					  &used, 0, new_size);
+			break;
+		}
+		case UBIFS_DATA_NODE:
+		{
+			struct ubifs_data_node *dn = snod->node;
+			loff_t new_size = le32_to_cpu(dn->size) +
+					  key_block(c, &snod->key) *
+					  UBIFS_BLOCK_SIZE;
+
+			err = insert_node(c, lnum, snod->offs, snod->len,
+					  &snod->key, snod->sqnum, deletion,
+					  &used, 0, new_size);
+			break;
+		}
+		case UBIFS_DENT_NODE:
+		case UBIFS_XENT_NODE:
+		{
+			struct ubifs_dent_node *dent = snod->node;
+
+			err = ubifs_validate_entry(c, dent);
+			if (err)
+				goto out_dump;
+
+			err = insert_dent(c, lnum, snod->offs, snod->len,
+					  &snod->key, dent->name,
+					  le16_to_cpu(dent->nlen), snod->sqnum,
+					  !le64_to_cpu(dent->inum), &used);
+			break;
+		}
+		case UBIFS_TRUN_NODE:
+		{
+			struct ubifs_trun_node *trun = snod->node;
+			loff_t old_size = le64_to_cpu(trun->old_size);
+			loff_t new_size = le64_to_cpu(trun->new_size);
+			union ubifs_key key;
+
+			/* Validate truncation node */
+			if (old_size < 0 || old_size > c->max_inode_sz ||
+			    new_size < 0 || new_size > c->max_inode_sz ||
+			    old_size <= new_size) {
+				ubifs_err(c, "bad truncation node");
+				goto out_dump;
+			}
+
+			/*
+			 * Create a fake truncation key just to use the same
+			 * functions which expect nodes to have keys.
+			 */
+			trun_key_init(c, &key, le32_to_cpu(trun->inum));
+			err = insert_node(c, lnum, snod->offs, snod->len,
+					  &key, snod->sqnum, 1, &used,
+					  old_size, new_size);
+			break;
+		}
+		default:
+			ubifs_err(c, "unexpected node type %d in bud LEB %d:%d",
+				  snod->type, lnum, snod->offs);
+			err = -EINVAL;
+			goto out_dump;
+		}
+		if (err)
+			goto out;
+	}
+
+	ubifs_assert(ubifs_search_bud(c, lnum));
+	ubifs_assert(sleb->endpt - offs >= used);
+	ubifs_assert(sleb->endpt % c->min_io_size == 0);
+
+	b->dirty = sleb->endpt - offs - used;
+	b->free = c->leb_size - sleb->endpt;
+	dbg_mnt("bud LEB %d replied: dirty %d, free %d",
+		lnum, b->dirty, b->free);
+
+out:
+	ubifs_scan_destroy(sleb);
+	return err;
+
+out_dump:
+	ubifs_err(c, "bad node is at LEB %d:%d", lnum, snod->offs);
+	ubifs_dump_node(c, snod->node);
+	ubifs_scan_destroy(sleb);
+	return -EINVAL;
+}
+
+/**
+ * replay_buds - replay all buds.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int replay_buds(struct ubifs_info *c)
+{
+	struct bud_entry *b;
+	int err;
+	unsigned long long prev_sqnum = 0;
+
+	list_for_each_entry(b, &c->replay_buds, list) {
+		err = replay_bud(c, b);
+		if (err)
+			return err;
+
+		ubifs_assert(b->sqnum > prev_sqnum);
+		prev_sqnum = b->sqnum;
+	}
+
+	return 0;
+}
+
+/**
+ * destroy_bud_list - destroy the list of buds to replay.
+ * @c: UBIFS file-system description object
+ */
+static void destroy_bud_list(struct ubifs_info *c)
+{
+	struct bud_entry *b;
+
+	while (!list_empty(&c->replay_buds)) {
+		b = list_entry(c->replay_buds.next, struct bud_entry, list);
+		list_del(&b->list);
+		kfree(b);
+	}
+}
+
+/**
+ * add_replay_bud - add a bud to the list of buds to replay.
+ * @c: UBIFS file-system description object
+ * @lnum: bud logical eraseblock number to replay
+ * @offs: bud start offset
+ * @jhead: journal head to which this bud belongs
+ * @sqnum: reference node sequence number
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int add_replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
+			  unsigned long long sqnum)
+{
+	struct ubifs_bud *bud;
+	struct bud_entry *b;
+
+	dbg_mnt("add replay bud LEB %d:%d, head %d", lnum, offs, jhead);
+
+	bud = kmalloc(sizeof(struct ubifs_bud), GFP_KERNEL);
+	if (!bud)
+		return -ENOMEM;
+
+	b = kmalloc(sizeof(struct bud_entry), GFP_KERNEL);
+	if (!b) {
+		kfree(bud);
+		return -ENOMEM;
+	}
+
+	bud->lnum = lnum;
+	bud->start = offs;
+	bud->jhead = jhead;
+	ubifs_add_bud(c, bud);
+
+	b->bud = bud;
+	b->sqnum = sqnum;
+	list_add_tail(&b->list, &c->replay_buds);
+
+	return 0;
+}
+
+/**
+ * validate_ref - validate a reference node.
+ * @c: UBIFS file-system description object
+ * @ref: the reference node to validate
+ * @ref_lnum: LEB number of the reference node
+ * @ref_offs: reference node offset
+ *
+ * This function returns %1 if a bud reference already exists for the LEB. %0 is
+ * returned if the reference node is new, otherwise %-EINVAL is returned if
+ * validation failed.
+ */
+static int validate_ref(struct ubifs_info *c, const struct ubifs_ref_node *ref)
+{
+	struct ubifs_bud *bud;
+	int lnum = le32_to_cpu(ref->lnum);
+	unsigned int offs = le32_to_cpu(ref->offs);
+	unsigned int jhead = le32_to_cpu(ref->jhead);
+
+	/*
+	 * ref->offs may point to the end of LEB when the journal head points
+	 * to the end of LEB and we write reference node for it during commit.
+	 * So this is why we require 'offs > c->leb_size'.
+	 */
+	if (jhead >= c->jhead_cnt || lnum >= c->leb_cnt ||
+	    lnum < c->main_first || offs > c->leb_size ||
+	    offs & (c->min_io_size - 1))
+		return -EINVAL;
+
+	/* Make sure we have not already looked at this bud */
+	bud = ubifs_search_bud(c, lnum);
+	if (bud) {
+		if (bud->jhead == jhead && bud->start <= offs)
+			return 1;
+		ubifs_err(c, "bud at LEB %d:%d was already referred", lnum, offs);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * replay_log_leb - replay a log logical eraseblock.
+ * @c: UBIFS file-system description object
+ * @lnum: log logical eraseblock to replay
+ * @offs: offset to start replaying from
+ * @sbuf: scan buffer
+ *
+ * This function replays a log LEB and returns zero in case of success, %1 if
+ * this is the last LEB in the log, and a negative error code in case of
+ * failure.
+ */
+static int replay_log_leb(struct ubifs_info *c, int lnum, int offs, void *sbuf)
+{
+	int err;
+	struct ubifs_scan_leb *sleb;
+	struct ubifs_scan_node *snod;
+	const struct ubifs_cs_node *node;
+
+	dbg_mnt("replay log LEB %d:%d", lnum, offs);
+	sleb = ubifs_scan(c, lnum, offs, sbuf, c->need_recovery);
+	if (IS_ERR(sleb)) {
+		if (PTR_ERR(sleb) != -EUCLEAN || !c->need_recovery)
+			return PTR_ERR(sleb);
+		/*
+		 * Note, the below function will recover this log LEB only if
+		 * it is the last, because unclean reboots can possibly corrupt
+		 * only the tail of the log.
+		 */
+		sleb = ubifs_recover_log_leb(c, lnum, offs, sbuf);
+		if (IS_ERR(sleb))
+			return PTR_ERR(sleb);
+	}
+
+	if (sleb->nodes_cnt == 0) {
+		err = 1;
+		goto out;
+	}
+
+	node = sleb->buf;
+	snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list);
+	if (c->cs_sqnum == 0) {
+		/*
+		 * This is the first log LEB we are looking at, make sure that
+		 * the first node is a commit start node. Also record its
+		 * sequence number so that UBIFS can determine where the log
+		 * ends, because all nodes which were have higher sequence
+		 * numbers.
+		 */
+		if (snod->type != UBIFS_CS_NODE) {
+			ubifs_err(c, "first log node at LEB %d:%d is not CS node",
+				  lnum, offs);
+			goto out_dump;
+		}
+		if (le64_to_cpu(node->cmt_no) != c->cmt_no) {
+			ubifs_err(c, "first CS node at LEB %d:%d has wrong commit number %llu expected %llu",
+				  lnum, offs,
+				  (unsigned long long)le64_to_cpu(node->cmt_no),
+				  c->cmt_no);
+			goto out_dump;
+		}
+
+		c->cs_sqnum = le64_to_cpu(node->ch.sqnum);
+		dbg_mnt("commit start sqnum %llu", c->cs_sqnum);
+	}
+
+	if (snod->sqnum < c->cs_sqnum) {
+		/*
+		 * This means that we reached end of log and now
+		 * look to the older log data, which was already
+		 * committed but the eraseblock was not erased (UBIFS
+		 * only un-maps it). So this basically means we have to
+		 * exit with "end of log" code.
+		 */
+		err = 1;
+		goto out;
+	}
+
+	/* Make sure the first node sits at offset zero of the LEB */
+	if (snod->offs != 0) {
+		ubifs_err(c, "first node is not at zero offset");
+		goto out_dump;
+	}
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+		cond_resched();
+
+		if (snod->sqnum >= SQNUM_WATERMARK) {
+			ubifs_err(c, "file system's life ended");
+			goto out_dump;
+		}
+
+		if (snod->sqnum < c->cs_sqnum) {
+			ubifs_err(c, "bad sqnum %llu, commit sqnum %llu",
+				  snod->sqnum, c->cs_sqnum);
+			goto out_dump;
+		}
+
+		if (snod->sqnum > c->max_sqnum)
+			c->max_sqnum = snod->sqnum;
+
+		switch (snod->type) {
+		case UBIFS_REF_NODE: {
+			const struct ubifs_ref_node *ref = snod->node;
+
+			err = validate_ref(c, ref);
+			if (err == 1)
+				break; /* Already have this bud */
+			if (err)
+				goto out_dump;
+
+			err = add_replay_bud(c, le32_to_cpu(ref->lnum),
+					     le32_to_cpu(ref->offs),
+					     le32_to_cpu(ref->jhead),
+					     snod->sqnum);
+			if (err)
+				goto out;
+
+			break;
+		}
+		case UBIFS_CS_NODE:
+			/* Make sure it sits at the beginning of LEB */
+			if (snod->offs != 0) {
+				ubifs_err(c, "unexpected node in log");
+				goto out_dump;
+			}
+			break;
+		default:
+			ubifs_err(c, "unexpected node in log");
+			goto out_dump;
+		}
+	}
+
+	if (sleb->endpt || c->lhead_offs >= c->leb_size) {
+		c->lhead_lnum = lnum;
+		c->lhead_offs = sleb->endpt;
+	}
+
+	err = !sleb->endpt;
+out:
+	ubifs_scan_destroy(sleb);
+	return err;
+
+out_dump:
+	ubifs_err(c, "log error detected while replaying the log at LEB %d:%d",
+		  lnum, offs + snod->offs);
+	ubifs_dump_node(c, snod->node);
+	ubifs_scan_destroy(sleb);
+	return -EINVAL;
+}
+
+/**
+ * take_ihead - update the status of the index head in lprops to 'taken'.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns the amount of free space in the index head LEB or a
+ * negative error code.
+ */
+static int take_ihead(struct ubifs_info *c)
+{
+	const struct ubifs_lprops *lp;
+	int err, free;
+
+	ubifs_get_lprops(c);
+
+	lp = ubifs_lpt_lookup_dirty(c, c->ihead_lnum);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	free = lp->free;
+
+	lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
+			     lp->flags | LPROPS_TAKEN, 0);
+	if (IS_ERR(lp)) {
+		err = PTR_ERR(lp);
+		goto out;
+	}
+
+	err = free;
+out:
+	ubifs_release_lprops(c);
+	return err;
+}
+
+/**
+ * ubifs_replay_journal - replay journal.
+ * @c: UBIFS file-system description object
+ *
+ * This function scans the journal, replays and cleans it up. It makes sure all
+ * memory data structures related to uncommitted journal are built (dirty TNC
+ * tree, tree of buds, modified lprops, etc).
+ */
+int ubifs_replay_journal(struct ubifs_info *c)
+{
+	int err, lnum, free;
+
+	BUILD_BUG_ON(UBIFS_TRUN_KEY > 5);
+
+	/* Update the status of the index head in lprops to 'taken' */
+	free = take_ihead(c);
+	if (free < 0)
+		return free; /* Error code */
+
+	if (c->ihead_offs != c->leb_size - free) {
+		ubifs_err(c, "bad index head LEB %d:%d", c->ihead_lnum,
+			  c->ihead_offs);
+		return -EINVAL;
+	}
+
+	dbg_mnt("start replaying the journal");
+	c->replaying = 1;
+	lnum = c->ltail_lnum = c->lhead_lnum;
+
+	do {
+		err = replay_log_leb(c, lnum, 0, c->sbuf);
+		if (err == 1) {
+			if (lnum != c->lhead_lnum)
+				/* We hit the end of the log */
+				break;
+
+			/*
+			 * The head of the log must always start with the
+			 * "commit start" node on a properly formatted UBIFS.
+			 * But we found no nodes at all, which means that
+			 * someting went wrong and we cannot proceed mounting
+			 * the file-system.
+			 */
+			ubifs_err(c, "no UBIFS nodes found at the log head LEB %d:%d, possibly corrupted",
+				  lnum, 0);
+			err = -EINVAL;
+		}
+		if (err)
+			goto out;
+		lnum = ubifs_next_log_lnum(c, lnum);
+	} while (lnum != c->ltail_lnum);
+
+	err = replay_buds(c);
+	if (err)
+		goto out;
+
+	err = apply_replay_list(c);
+	if (err)
+		goto out;
+
+	err = set_buds_lprops(c);
+	if (err)
+		goto out;
+
+	/*
+	 * UBIFS budgeting calculations use @c->bi.uncommitted_idx variable
+	 * to roughly estimate index growth. Things like @c->bi.min_idx_lebs
+	 * depend on it. This means we have to initialize it to make sure
+	 * budgeting works properly.
+	 */
+	c->bi.uncommitted_idx = atomic_long_read(&c->dirty_zn_cnt);
+	c->bi.uncommitted_idx *= c->max_idx_node_sz;
+
+	ubifs_assert(c->bud_bytes <= c->max_bud_bytes || c->need_recovery);
+	dbg_mnt("finished, log head LEB %d:%d, max_sqnum %llu, highest_inum %lu",
+		c->lhead_lnum, c->lhead_offs, c->max_sqnum,
+		(unsigned long)c->highest_inum);
+out:
+	destroy_replay_list(c);
+	destroy_bud_list(c);
+	c->replaying = 0;
+	return err;
+}