Message-Id: <1206629746-4298-24-git-send-email-Artem.Bityutskiy@nokia.com>
Date:	Thu, 27 Mar 2008 16:55:43 +0200
From:	Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Adrian Hunter <ext-adrian.hunter@...ia.com>,
	Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
Subject: [RFC PATCH 23/26] UBIFS: add orphans handling sub-system

This sub-system keeps track of orphans - the files which were deleted
but are still kept open. These files should be deleted only when the
last reference goes. But if an unclean reboot happens, UBIFS has to
also delete the orphans. This is why the orphans sub-system exists -
it records information about all orphans to the on-flash orphan area.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@...ia.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@...ia.com>
---
 fs/ubifs/orphan.c |  952 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 952 insertions(+), 0 deletions(-)

diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
new file mode 100644
index 0000000..4173fa9
--- /dev/null
+++ b/fs/ubifs/orphan.c
@@ -0,0 +1,952 @@
+/*
+ * 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_CHK_ORPH
+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 = ubi_leb_change(c->ubi, 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 != NULL);
+	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 'delete-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_mnt("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_mnt("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_mnt("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_mnt("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_mnt("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: %1 => recover from unclean unmount
+ *
+ * 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 err = 0;
+
+	c->max_orphans = tot_avail_orphs(c);
+
+	c->orph_buf = vmalloc(c->leb_size);
+	if (!c->orph_buf)
+		return -ENOMEM;
+
+	if (unclean)
+		err = kill_orphans(c);
+	else
+		err = clear_orphans(c);
+
+	return err;
+}
+
+#ifdef CONFIG_UBIFS_FS_DEBUG_CHK_ORPH
+
+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_ino(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 = dbg_read_leaf_nolock(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;
+
+	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_CHK_ORPH */
-- 
1.5.4.1

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