UBIFS: add new flash file system

This is a new flash file system. See
http://www.linux-mtd.infradead.org/doc/ubifs.html

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>

1 files changed, 958 insertions, 0 deletions

diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
new file mode 100644
index 00000000000..3afeb9242c6
--- /dev/null
+++ b/fs/ubifs/orphan.c
@@ -0,0 +1,958 @@
+/*
+ * 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
+ *
+ * Author: Adrian Hunter
+ */
+
+#include "ubifs.h"
+
+/*
+ * An orphan is an inode number whose inode node has been committed to the index
+ * with a link count of zero. That happens when an open file is deleted
+ * (unlinked) and then a commit is run. In the normal course of events the inode
+ * would be deleted when the file is closed. However in the case of an unclean
+ * unmount, orphans need to be accounted for. After an unclean unmount, the
+ * orphans' inodes must be deleted which means either scanning the entire index
+ * looking for them, or keeping a list on flash somewhere. This unit implements
+ * the latter approach.
+ *
+ * The orphan area is a fixed number of LEBs situated between the LPT area and
+ * the main area. The number of orphan area LEBs is specified when the file
+ * system is created. The minimum number is 1. The size of the orphan area
+ * should be so that it can hold the maximum number of orphans that are expected
+ * to ever exist at one time.
+ *
+ * The number of orphans that can fit in a LEB is:
+ *
+ *         (c->leb_size - UBIFS_ORPH_NODE_SZ) / sizeof(__le64)
+ *
+ * For example: a 15872 byte LEB can fit 1980 orphans so 1 LEB may be enough.
+ *
+ * Orphans are accumulated in a rb-tree. When an inode's link count drops to
+ * zero, the inode number is added to the rb-tree. It is removed from the tree
+ * when the inode is deleted.  Any new orphans that are in the orphan tree when
+ * the commit is run, are written to the orphan area in 1 or more orph nodes.
+ * If the orphan area is full, it is consolidated to make space.  There is
+ * always enough space because validation prevents the user from creating more
+ * than the maximum number of orphans allowed.
+ */
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+static int dbg_check_orphans(struct ubifs_info *c);
+#else
+#define dbg_check_orphans(c) 0
+#endif
+
+/**
+ * ubifs_add_orphan - add an orphan.
+ * @c: UBIFS file-system description object
+ * @inum: orphan inode number
+ *
+ * Add an orphan. This function is called when an inodes link count drops to
+ * zero.
+ */
+int ubifs_add_orphan(struct ubifs_info *c, ino_t inum)
+{
+	struct ubifs_orphan *orphan, *o;
+	struct rb_node **p, *parent = NULL;
+
+	orphan = kzalloc(sizeof(struct ubifs_orphan), GFP_NOFS);
+	if (!orphan)
+		return -ENOMEM;
+	orphan->inum = inum;
+	orphan->new = 1;
+
+	spin_lock(&c->orphan_lock);
+	if (c->tot_orphans >= c->max_orphans) {
+		spin_unlock(&c->orphan_lock);
+		kfree(orphan);
+		return -ENFILE;
+	}
+	p = &c->orph_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		o = rb_entry(parent, struct ubifs_orphan, rb);
+		if (inum < o->inum)
+			p = &(*p)->rb_left;
+		else if (inum > o->inum)
+			p = &(*p)->rb_right;
+		else {
+			dbg_err("orphaned twice");
+			spin_unlock(&c->orphan_lock);
+			kfree(orphan);
+			return 0;
+		}
+	}
+	c->tot_orphans += 1;
+	c->new_orphans += 1;
+	rb_link_node(&orphan->rb, parent, p);
+	rb_insert_color(&orphan->rb, &c->orph_tree);
+	list_add_tail(&orphan->list, &c->orph_list);
+	list_add_tail(&orphan->new_list, &c->orph_new);
+	spin_unlock(&c->orphan_lock);
+	dbg_gen("ino %lu", inum);
+	return 0;
+}
+
+/**
+ * ubifs_delete_orphan - delete an orphan.
+ * @c: UBIFS file-system description object
+ * @inum: orphan inode number
+ *
+ * Delete an orphan. This function is called when an inode is deleted.
+ */
+void ubifs_delete_orphan(struct ubifs_info *c, ino_t inum)
+{
+	struct ubifs_orphan *o;
+	struct rb_node *p;
+
+	spin_lock(&c->orphan_lock);
+	p = c->orph_tree.rb_node;
+	while (p) {
+		o = rb_entry(p, struct ubifs_orphan, rb);
+		if (inum < o->inum)
+			p = p->rb_left;
+		else if (inum > o->inum)
+			p = p->rb_right;
+		else {
+			if (o->dnext) {
+				spin_unlock(&c->orphan_lock);
+				dbg_gen("deleted twice ino %lu", inum);
+				return;
+			}
+			if (o->cnext) {
+				o->dnext = c->orph_dnext;
+				c->orph_dnext = o;
+				spin_unlock(&c->orphan_lock);
+				dbg_gen("delete later ino %lu", inum);
+				return;
+			}
+			rb_erase(p, &c->orph_tree);
+			list_del(&o->list);
+			c->tot_orphans -= 1;
+			if (o->new) {
+				list_del(&o->new_list);
+				c->new_orphans -= 1;
+			}
+			spin_unlock(&c->orphan_lock);
+			kfree(o);
+			dbg_gen("inum %lu", inum);
+			return;
+		}
+	}
+	spin_unlock(&c->orphan_lock);
+	dbg_err("missing orphan ino %lu", inum);
+	dbg_dump_stack();
+}
+
+/**
+ * ubifs_orphan_start_commit - start commit of orphans.
+ * @c: UBIFS file-system description object
+ *
+ * Start commit of orphans.
+ */
+int ubifs_orphan_start_commit(struct ubifs_info *c)
+{
+	struct ubifs_orphan *orphan, **last;
+
+	spin_lock(&c->orphan_lock);
+	last = &c->orph_cnext;
+	list_for_each_entry(orphan, &c->orph_new, new_list) {
+		ubifs_assert(orphan->new);
+		orphan->new = 0;
+		*last = orphan;
+		last = &orphan->cnext;
+	}
+	*last = orphan->cnext;
+	c->cmt_orphans = c->new_orphans;
+	c->new_orphans = 0;
+	dbg_cmt("%d orphans to commit", c->cmt_orphans);
+	INIT_LIST_HEAD(&c->orph_new);
+	if (c->tot_orphans == 0)
+		c->no_orphs = 1;
+	else
+		c->no_orphs = 0;
+	spin_unlock(&c->orphan_lock);
+	return 0;
+}
+
+/**
+ * avail_orphs - calculate available space.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns the number of orphans that can be written in the
+ * available space.
+ */
+static int avail_orphs(struct ubifs_info *c)
+{
+	int avail_lebs, avail, gap;
+
+	avail_lebs = c->orph_lebs - (c->ohead_lnum - c->orph_first) - 1;
+	avail = avail_lebs *
+	       ((c->leb_size - UBIFS_ORPH_NODE_SZ) / sizeof(__le64));
+	gap = c->leb_size - c->ohead_offs;
+	if (gap >= UBIFS_ORPH_NODE_SZ + sizeof(__le64))
+		avail += (gap - UBIFS_ORPH_NODE_SZ) / sizeof(__le64);
+	return avail;
+}
+
+/**
+ * tot_avail_orphs - calculate total space.
+ * @c: UBIFS file-system description object
+ *
+ * This function returns the number of orphans that can be written in half
+ * the total space. That leaves half the space for adding new orphans.
+ */
+static int tot_avail_orphs(struct ubifs_info *c)
+{
+	int avail_lebs, avail;
+
+	avail_lebs = c->orph_lebs;
+	avail = avail_lebs *
+	       ((c->leb_size - UBIFS_ORPH_NODE_SZ) / sizeof(__le64));
+	return avail / 2;
+}
+
+/**
+ * do_write_orph_node - write a node
+ * @c: UBIFS file-system description object
+ * @len: length of node
+ * @atomic: write atomically
+ *
+ * This function writes a node to the orphan head from the orphan buffer. If
+ * %atomic is not zero, then the write is done atomically. On success, %0 is
+ * returned, otherwise a negative error code is returned.
+ */
+static int do_write_orph_node(struct ubifs_info *c, int len, int atomic)
+{
+	int err = 0;
+
+	if (atomic) {
+		ubifs_assert(c->ohead_offs == 0);
+		ubifs_prepare_node(c, c->orph_buf, len, 1);
+		len = ALIGN(len, c->min_io_size);
+		err = ubifs_leb_change(c, c->ohead_lnum, c->orph_buf, len,
+				       UBI_SHORTTERM);
+	} else {
+		if (c->ohead_offs == 0) {
+			/* Ensure LEB has been unmapped */
+			err = ubifs_leb_unmap(c, c->ohead_lnum);
+			if (err)
+				return err;
+		}
+		err = ubifs_write_node(c, c->orph_buf, len, c->ohead_lnum,
+				       c->ohead_offs, UBI_SHORTTERM);
+	}
+	return err;
+}
+
+/**
+ * write_orph_node - write an orph node
+ * @c: UBIFS file-system description object
+ * @atomic: write atomically
+ *
+ * This function builds an orph node from the cnext list and writes it to the
+ * orphan head. On success, %0 is returned, otherwise a negative error code
+ * is returned.
+ */
+static int write_orph_node(struct ubifs_info *c, int atomic)
+{
+	struct ubifs_orphan *orphan, *cnext;
+	struct ubifs_orph_node *orph;
+	int gap, err, len, cnt, i;
+
+	ubifs_assert(c->cmt_orphans > 0);
+	gap = c->leb_size - c->ohead_offs;
+	if (gap < UBIFS_ORPH_NODE_SZ + sizeof(__le64)) {
+		c->ohead_lnum += 1;
+		c->ohead_offs = 0;
+		gap = c->leb_size;
+		if (c->ohead_lnum > c->orph_last) {
+			/*
+			 * We limit the number of orphans so that this should
+			 * never happen.
+			 */
+			ubifs_err("out of space in orphan area");
+			return -EINVAL;
+		}
+	}
+	cnt = (gap - UBIFS_ORPH_NODE_SZ) / sizeof(__le64);
+	if (cnt > c->cmt_orphans)
+		cnt = c->cmt_orphans;
+	len = UBIFS_ORPH_NODE_SZ + cnt * sizeof(__le64);
+	ubifs_assert(c->orph_buf);
+	orph = c->orph_buf;
+	orph->ch.node_type = UBIFS_ORPH_NODE;
+	spin_lock(&c->orphan_lock);
+	cnext = c->orph_cnext;
+	for (i = 0; i < cnt; i++) {
+		orphan = cnext;
+		orph->inos[i] = cpu_to_le64(orphan->inum);
+		cnext = orphan->cnext;
+		orphan->cnext = NULL;
+	}
+	c->orph_cnext = cnext;
+	c->cmt_orphans -= cnt;
+	spin_unlock(&c->orphan_lock);
+	if (c->cmt_orphans)
+		orph->cmt_no = cpu_to_le64(c->cmt_no + 1);
+	else
+		/* Mark the last node of the commit */
+		orph->cmt_no = cpu_to_le64((c->cmt_no + 1) | (1ULL << 63));
+	ubifs_assert(c->ohead_offs + len <= c->leb_size);
+	ubifs_assert(c->ohead_lnum >= c->orph_first);
+	ubifs_assert(c->ohead_lnum <= c->orph_last);
+	err = do_write_orph_node(c, len, atomic);
+	c->ohead_offs += ALIGN(len, c->min_io_size);
+	c->ohead_offs = ALIGN(c->ohead_offs, 8);
+	return err;
+}
+
+/**
+ * write_orph_nodes - write orph nodes until there are no more to commit
+ * @c: UBIFS file-system description object
+ * @atomic: write atomically
+ *
+ * This function writes orph nodes for all the orphans to commit. On success,
+ * %0 is returned, otherwise a negative error code is returned.
+ */
+static int write_orph_nodes(struct ubifs_info *c, int atomic)
+{
+	int err;
+
+	while (c->cmt_orphans > 0) {
+		err = write_orph_node(c, atomic);
+		if (err)
+			return err;
+	}
+	if (atomic) {
+		int lnum;
+
+		/* Unmap any unused LEBs after consolidation */
+		lnum = c->ohead_lnum + 1;
+		for (lnum = c->ohead_lnum + 1; lnum <= c->orph_last; lnum++) {
+			err = ubifs_leb_unmap(c, lnum);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
+/**
+ * consolidate - consolidate the orphan area.
+ * @c: UBIFS file-system description object
+ *
+ * This function enables consolidation by putting all the orphans into the list
+ * to commit. The list is in the order that the orphans were added, and the
+ * LEBs are written atomically in order, so at no time can orphans be lost by
+ * an unclean unmount.
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int consolidate(struct ubifs_info *c)
+{
+	int tot_avail = tot_avail_orphs(c), err = 0;
+
+	spin_lock(&c->orphan_lock);
+	dbg_cmt("there is space for %d orphans and there are %d",
+		tot_avail, c->tot_orphans);
+	if (c->tot_orphans - c->new_orphans <= tot_avail) {
+		struct ubifs_orphan *orphan, **last;
+		int cnt = 0;
+
+		/* Change the cnext list to include all non-new orphans */
+		last = &c->orph_cnext;
+		list_for_each_entry(orphan, &c->orph_list, list) {
+			if (orphan->new)
+				continue;
+			*last = orphan;
+			last = &orphan->cnext;
+			cnt += 1;
+		}
+		*last = orphan->cnext;
+		ubifs_assert(cnt == c->tot_orphans - c->new_orphans);
+		c->cmt_orphans = cnt;
+		c->ohead_lnum = c->orph_first;
+		c->ohead_offs = 0;
+	} else {
+		/*
+		 * We limit the number of orphans so that this should
+		 * never happen.
+		 */
+		ubifs_err("out of space in orphan area");
+		err = -EINVAL;
+	}
+	spin_unlock(&c->orphan_lock);
+	return err;
+}
+
+/**
+ * commit_orphans - commit orphans.
+ * @c: UBIFS file-system description object
+ *
+ * This function commits orphans to flash. On success, %0 is returned,
+ * otherwise a negative error code is returned.
+ */
+static int commit_orphans(struct ubifs_info *c)
+{
+	int avail, atomic = 0, err;
+
+	ubifs_assert(c->cmt_orphans > 0);
+	avail = avail_orphs(c);
+	if (avail < c->cmt_orphans) {
+		/* Not enough space to write new orphans, so consolidate */
+		err = consolidate(c);
+		if (err)
+			return err;
+		atomic = 1;
+	}
+	err = write_orph_nodes(c, atomic);
+	return err;
+}
+
+/**
+ * erase_deleted - erase the orphans marked for deletion.
+ * @c: UBIFS file-system description object
+ *
+ * During commit, the orphans being committed cannot be deleted, so they are
+ * marked for deletion and deleted by this function. Also, the recovery
+ * adds killed orphans to the deletion list, and therefore they are deleted
+ * here too.
+ */
+static void erase_deleted(struct ubifs_info *c)
+{
+	struct ubifs_orphan *orphan, *dnext;
+
+	spin_lock(&c->orphan_lock);
+	dnext = c->orph_dnext;
+	while (dnext) {
+		orphan = dnext;
+		dnext = orphan->dnext;
+		ubifs_assert(!orphan->new);
+		rb_erase(&orphan->rb, &c->orph_tree);
+		list_del(&orphan->list);
+		c->tot_orphans -= 1;
+		dbg_gen("deleting orphan ino %lu", orphan->inum);
+		kfree(orphan);
+	}
+	c->orph_dnext = NULL;
+	spin_unlock(&c->orphan_lock);
+}
+
+/**
+ * ubifs_orphan_end_commit - end commit of orphans.
+ * @c: UBIFS file-system description object
+ *
+ * End commit of orphans.
+ */
+int ubifs_orphan_end_commit(struct ubifs_info *c)
+{
+	int err;
+
+	if (c->cmt_orphans != 0) {
+		err = commit_orphans(c);
+		if (err)
+			return err;
+	}
+	erase_deleted(c);
+	err = dbg_check_orphans(c);
+	return err;
+}
+
+/**
+ * clear_orphans - erase all LEBs used for orphans.
+ * @c: UBIFS file-system description object
+ *
+ * If recovery is not required, then the orphans from the previous session
+ * are not needed. This function locates the LEBs used to record
+ * orphans, and un-maps them.
+ */
+static int clear_orphans(struct ubifs_info *c)
+{
+	int lnum, err;
+
+	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
+		err = ubifs_leb_unmap(c, lnum);
+		if (err)
+			return err;
+	}
+	c->ohead_lnum = c->orph_first;
+	c->ohead_offs = 0;
+	return 0;
+}
+
+/**
+ * insert_dead_orphan - insert an orphan.
+ * @c: UBIFS file-system description object
+ * @inum: orphan inode number
+ *
+ * This function is a helper to the 'do_kill_orphans()' function. The orphan
+ * must be kept until the next commit, so it is added to the rb-tree and the
+ * deletion list.
+ */
+static int insert_dead_orphan(struct ubifs_info *c, ino_t inum)
+{
+	struct ubifs_orphan *orphan, *o;
+	struct rb_node **p, *parent = NULL;
+
+	orphan = kzalloc(sizeof(struct ubifs_orphan), GFP_KERNEL);
+	if (!orphan)
+		return -ENOMEM;
+	orphan->inum = inum;
+
+	p = &c->orph_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		o = rb_entry(parent, struct ubifs_orphan, rb);
+		if (inum < o->inum)
+			p = &(*p)->rb_left;
+		else if (inum > o->inum)
+			p = &(*p)->rb_right;
+		else {
+			/* Already added - no problem */
+			kfree(orphan);
+			return 0;
+		}
+	}
+	c->tot_orphans += 1;
+	rb_link_node(&orphan->rb, parent, p);
+	rb_insert_color(&orphan->rb, &c->orph_tree);
+	list_add_tail(&orphan->list, &c->orph_list);
+	orphan->dnext = c->orph_dnext;
+	c->orph_dnext = orphan;
+	dbg_mnt("ino %lu, new %d, tot %d",
+		inum, c->new_orphans, c->tot_orphans);
+	return 0;
+}
+
+/**
+ * do_kill_orphans - remove orphan inodes from the index.
+ * @c: UBIFS file-system description object
+ * @sleb: scanned LEB
+ * @last_cmt_no: cmt_no of last orph node read is passed and returned here
+ * @outofdate: whether the LEB is out of date is returned here
+ * @last_flagged: whether the end orph node is encountered
+ *
+ * This function is a helper to the 'kill_orphans()' function. It goes through
+ * every orphan node in a LEB and for every inode number recorded, removes
+ * all keys for that inode from the TNC.
+ */
+static int do_kill_orphans(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
+			   unsigned long long *last_cmt_no, int *outofdate,
+			   int *last_flagged)
+{
+	struct ubifs_scan_node *snod;
+	struct ubifs_orph_node *orph;
+	unsigned long long cmt_no;
+	ino_t inum;
+	int i, n, err, first = 1;
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+		if (snod->type != UBIFS_ORPH_NODE) {
+			ubifs_err("invalid node type %d in orphan area at "
+				  "%d:%d", snod->type, sleb->lnum, snod->offs);
+			dbg_dump_node(c, snod->node);
+			return -EINVAL;
+		}
+
+		orph = snod->node;
+
+		/* Check commit number */
+		cmt_no = le64_to_cpu(orph->cmt_no) & LLONG_MAX;
+		/*
+		 * The commit number on the master node may be less, because
+		 * of a failed commit. If there are several failed commits in a
+		 * row, the commit number written on orph nodes will continue to
+		 * increase (because the commit number is adjusted here) even
+		 * though the commit number on the master node stays the same
+		 * because the master node has not been re-written.
+		 */
+		if (cmt_no > c->cmt_no)
+			c->cmt_no = cmt_no;
+		if (cmt_no < *last_cmt_no && *last_flagged) {
+			/*
+			 * The last orph node had a higher commit number and was
+			 * flagged as the last written for that commit number.
+			 * That makes this orph node, out of date.
+			 */
+			if (!first) {
+				ubifs_err("out of order commit number %llu in "
+					  "orphan node at %d:%d",
+					  cmt_no, sleb->lnum, snod->offs);
+				dbg_dump_node(c, snod->node);
+				return -EINVAL;
+			}
+			dbg_rcvry("out of date LEB %d", sleb->lnum);
+			*outofdate = 1;
+			return 0;
+		}
+
+		if (first)
+			first = 0;
+
+		n = (le32_to_cpu(orph->ch.len) - UBIFS_ORPH_NODE_SZ) >> 3;
+		for (i = 0; i < n; i++) {
+			inum = le64_to_cpu(orph->inos[i]);
+			dbg_rcvry("deleting orphaned inode %lu", inum);
+			err = ubifs_tnc_remove_ino(c, inum);
+			if (err)
+				return err;
+			err = insert_dead_orphan(c, inum);
+			if (err)
+				return err;
+		}
+
+		*last_cmt_no = cmt_no;
+		if (le64_to_cpu(orph->cmt_no) & (1ULL << 63)) {
+			dbg_rcvry("last orph node for commit %llu at %d:%d",
+				  cmt_no, sleb->lnum, snod->offs);
+			*last_flagged = 1;
+		} else
+			*last_flagged = 0;
+	}
+
+	return 0;
+}
+
+/**
+ * kill_orphans - remove all orphan inodes from the index.
+ * @c: UBIFS file-system description object
+ *
+ * If recovery is required, then orphan inodes recorded during the previous
+ * session (which ended with an unclean unmount) must be deleted from the index.
+ * This is done by updating the TNC, but since the index is not updated until
+ * the next commit, the LEBs where the orphan information is recorded are not
+ * erased until the next commit.
+ */
+static int kill_orphans(struct ubifs_info *c)
+{
+	unsigned long long last_cmt_no = 0;
+	int lnum, err = 0, outofdate = 0, last_flagged = 0;
+
+	c->ohead_lnum = c->orph_first;
+	c->ohead_offs = 0;
+	/* Check no-orphans flag and skip this if no orphans */
+	if (c->no_orphs) {
+		dbg_rcvry("no orphans");
+		return 0;
+	}
+	/*
+	 * Orph nodes always start at c->orph_first and are written to each
+	 * successive LEB in turn. Generally unused LEBs will have been unmapped
+	 * but may contain out of date orph nodes if the unmap didn't go
+	 * through. In addition, the last orph node written for each commit is
+	 * marked (top bit of orph->cmt_no is set to 1). It is possible that
+	 * there are orph nodes from the next commit (i.e. the commit did not
+	 * complete successfully). In that case, no orphans will have been lost
+	 * due to the way that orphans are written, and any orphans added will
+	 * be valid orphans anyway and so can be deleted.
+	 */
+	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
+		struct ubifs_scan_leb *sleb;
+
+		dbg_rcvry("LEB %d", lnum);
+		sleb = ubifs_scan(c, lnum, 0, c->sbuf);
+		if (IS_ERR(sleb)) {
+			sleb = ubifs_recover_leb(c, lnum, 0, c->sbuf, 0);
+			if (IS_ERR(sleb)) {
+				err = PTR_ERR(sleb);
+				break;
+			}
+		}
+		err = do_kill_orphans(c, sleb, &last_cmt_no, &outofdate,
+				      &last_flagged);
+		if (err || outofdate) {
+			ubifs_scan_destroy(sleb);
+			break;
+		}
+		if (sleb->endpt) {
+			c->ohead_lnum = lnum;
+			c->ohead_offs = sleb->endpt;
+		}
+		ubifs_scan_destroy(sleb);
+	}
+	return err;
+}
+
+/**
+ * ubifs_mount_orphans - delete orphan inodes and erase LEBs that recorded them.
+ * @c: UBIFS file-system description object
+ * @unclean: indicates recovery from unclean unmount
+ * @read_only: indicates read only mount
+ *
+ * This function is called when mounting to erase orphans from the previous
+ * session. If UBIFS was not unmounted cleanly, then the inodes recorded as
+ * orphans are deleted.
+ */
+int ubifs_mount_orphans(struct ubifs_info *c, int unclean, int read_only)
+{
+	int err = 0;
+
+	c->max_orphans = tot_avail_orphs(c);
+
+	if (!read_only) {
+		c->orph_buf = vmalloc(c->leb_size);
+		if (!c->orph_buf)
+			return -ENOMEM;
+	}
+
+	if (unclean)
+		err = kill_orphans(c);
+	else if (!read_only)
+		err = clear_orphans(c);
+
+	return err;
+}
+
+#ifdef CONFIG_UBIFS_FS_DEBUG
+
+struct check_orphan {
+	struct rb_node rb;
+	ino_t inum;
+};
+
+struct check_info {
+	unsigned long last_ino;
+	unsigned long tot_inos;
+	unsigned long missing;
+	unsigned long long leaf_cnt;
+	struct ubifs_ino_node *node;
+	struct rb_root root;
+};
+
+static int dbg_find_orphan(struct ubifs_info *c, ino_t inum)
+{
+	struct ubifs_orphan *o;
+	struct rb_node *p;
+
+	spin_lock(&c->orphan_lock);
+	p = c->orph_tree.rb_node;
+	while (p) {
+		o = rb_entry(p, struct ubifs_orphan, rb);
+		if (inum < o->inum)
+			p = p->rb_left;
+		else if (inum > o->inum)
+			p = p->rb_right;
+		else {
+			spin_unlock(&c->orphan_lock);
+			return 1;
+		}
+	}
+	spin_unlock(&c->orphan_lock);
+	return 0;
+}
+
+static int dbg_ins_check_orphan(struct rb_root *root, ino_t inum)
+{
+	struct check_orphan *orphan, *o;
+	struct rb_node **p, *parent = NULL;
+
+	orphan = kzalloc(sizeof(struct check_orphan), GFP_NOFS);
+	if (!orphan)
+		return -ENOMEM;
+	orphan->inum = inum;
+
+	p = &root->rb_node;
+	while (*p) {
+		parent = *p;
+		o = rb_entry(parent, struct check_orphan, rb);
+		if (inum < o->inum)
+			p = &(*p)->rb_left;
+		else if (inum > o->inum)
+			p = &(*p)->rb_right;
+		else {
+			kfree(orphan);
+			return 0;
+		}
+	}
+	rb_link_node(&orphan->rb, parent, p);
+	rb_insert_color(&orphan->rb, root);
+	return 0;
+}
+
+static int dbg_find_check_orphan(struct rb_root *root, ino_t inum)
+{
+	struct check_orphan *o;
+	struct rb_node *p;
+
+	p = root->rb_node;
+	while (p) {
+		o = rb_entry(p, struct check_orphan, rb);
+		if (inum < o->inum)
+			p = p->rb_left;
+		else if (inum > o->inum)
+			p = p->rb_right;
+		else
+			return 1;
+	}
+	return 0;
+}
+
+static void dbg_free_check_tree(struct rb_root *root)
+{
+	struct rb_node *this = root->rb_node;
+	struct check_orphan *o;
+
+	while (this) {
+		if (this->rb_left) {
+			this = this->rb_left;
+			continue;
+		} else if (this->rb_right) {
+			this = this->rb_right;
+			continue;
+		}
+		o = rb_entry(this, struct check_orphan, rb);
+		this = rb_parent(this);
+		if (this) {
+			if (this->rb_left == &o->rb)
+				this->rb_left = NULL;
+			else
+				this->rb_right = NULL;
+		}
+		kfree(o);
+	}
+}
+
+static int dbg_orphan_check(struct ubifs_info *c, struct ubifs_zbranch *zbr,
+			    void *priv)
+{
+	struct check_info *ci = priv;
+	ino_t inum;
+	int err;
+
+	inum = key_inum(c, &zbr->key);
+	if (inum != ci->last_ino) {
+		/* Lowest node type is the inode node, so it comes first */
+		if (key_type(c, &zbr->key) != UBIFS_INO_KEY)
+			ubifs_err("found orphan node ino %lu, type %d", inum,
+				  key_type(c, &zbr->key));
+		ci->last_ino = inum;
+		ci->tot_inos += 1;
+		err = ubifs_tnc_read_node(c, zbr, ci->node);
+		if (err) {
+			ubifs_err("node read failed, error %d", err);
+			return err;
+		}
+		if (ci->node->nlink == 0)
+			/* Must be recorded as an orphan */
+			if (!dbg_find_check_orphan(&ci->root, inum) &&
+			    !dbg_find_orphan(c, inum)) {
+				ubifs_err("missing orphan, ino %lu", inum);
+				ci->missing += 1;
+			}
+	}
+	ci->leaf_cnt += 1;
+	return 0;
+}
+
+static int dbg_read_orphans(struct check_info *ci, struct ubifs_scan_leb *sleb)
+{
+	struct ubifs_scan_node *snod;
+	struct ubifs_orph_node *orph;
+	ino_t inum;
+	int i, n, err;
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+		cond_resched();
+		if (snod->type != UBIFS_ORPH_NODE)
+			continue;
+		orph = snod->node;
+		n = (le32_to_cpu(orph->ch.len) - UBIFS_ORPH_NODE_SZ) >> 3;
+		for (i = 0; i < n; i++) {
+			inum = le64_to_cpu(orph->inos[i]);
+			err = dbg_ins_check_orphan(&ci->root, inum);
+			if (err)
+				return err;
+		}
+	}
+	return 0;
+}
+
+static int dbg_scan_orphans(struct ubifs_info *c, struct check_info *ci)
+{
+	int lnum, err = 0;
+
+	/* Check no-orphans flag and skip this if no orphans */
+	if (c->no_orphs)
+		return 0;
+
+	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
+		struct ubifs_scan_leb *sleb;
+
+		sleb = ubifs_scan(c, lnum, 0, c->dbg_buf);
+		if (IS_ERR(sleb)) {
+			err = PTR_ERR(sleb);
+			break;
+		}
+
+		err = dbg_read_orphans(ci, sleb);
+		ubifs_scan_destroy(sleb);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
+static int dbg_check_orphans(struct ubifs_info *c)
+{
+	struct check_info ci;
+	int err;
+
+	if (!(ubifs_chk_flags & UBIFS_CHK_ORPH))
+		return 0;
+
+	ci.last_ino = 0;
+	ci.tot_inos = 0;
+	ci.missing  = 0;
+	ci.leaf_cnt = 0;
+	ci.root = RB_ROOT;
+	ci.node = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);
+	if (!ci.node) {
+		ubifs_err("out of memory");
+		return -ENOMEM;
+	}
+
+	err = dbg_scan_orphans(c, &ci);
+	if (err)
+		goto out;
+
+	err = dbg_walk_index(c, &dbg_orphan_check, NULL, &ci);
+	if (err) {
+		ubifs_err("cannot scan TNC, error %d", err);
+		goto out;
+	}
+
+	if (ci.missing) {
+		ubifs_err("%lu missing orphan(s)", ci.missing);
+		err = -EINVAL;
+		goto out;
+	}
+
+	dbg_cmt("last inode number is %lu", ci.last_ino);
+	dbg_cmt("total number of inodes is %lu", ci.tot_inos);
+	dbg_cmt("total number of leaf nodes is %llu", ci.leaf_cnt);
+
+out:
+	dbg_free_check_tree(&ci.root);
+	kfree(ci.node);
+	return err;
+}
+
+#endif /* CONFIG_UBIFS_FS_DEBUG */