Revert "tty: hvc: Fix data abort due to race in hvc_open"

[linux/fpc-iii.git] / fs / ubifs / orphan.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * 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 orphan 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.
 */

static int dbg_check_orphans(struct ubifs_info *c);

static struct ubifs_orphan *orphan_add(struct ubifs_info *c, ino_t inum,
                                       struct ubifs_orphan *parent_orphan)
{
        struct ubifs_orphan *orphan, *o;
        struct rb_node **p, *parent = NULL;

        orphan = kzalloc(sizeof(struct ubifs_orphan), GFP_NOFS);
        if (!orphan)
                return ERR_PTR(-ENOMEM);
        orphan->inum = inum;
        orphan->new = 1;
        INIT_LIST_HEAD(&orphan->child_list);

        spin_lock(&c->orphan_lock);
        if (c->tot_orphans >= c->max_orphans) {
                spin_unlock(&c->orphan_lock);
                kfree(orphan);
                return ERR_PTR(-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 {
                        ubifs_err(c, "orphaned twice");
                        spin_unlock(&c->orphan_lock);
                        kfree(orphan);
                        return ERR_PTR(-EINVAL);
                }
        }
        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);

        if (parent_orphan) {
                list_add_tail(&orphan->child_list,
                              &parent_orphan->child_list);
        }

        spin_unlock(&c->orphan_lock);
        dbg_gen("ino %lu", (unsigned long)inum);
        return orphan;
}

static struct ubifs_orphan *lookup_orphan(struct ubifs_info *c, ino_t inum)
{
        struct ubifs_orphan *o;
        struct rb_node *p;

        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 {
                        return o;
                }
        }
        return NULL;
}

static void __orphan_drop(struct ubifs_info *c, struct ubifs_orphan *o)
{
        rb_erase(&o->rb, &c->orph_tree);
        list_del(&o->list);
        c->tot_orphans -= 1;

        if (o->new) {
                list_del(&o->new_list);
                c->new_orphans -= 1;
        }

        kfree(o);
}

static void orphan_delete(struct ubifs_info *c, struct ubifs_orphan *orph)
{
        if (orph->del) {
                dbg_gen("deleted twice ino %lu", (unsigned long)orph->inum);
                return;
        }

        if (orph->cmt) {
                orph->del = 1;
                orph->dnext = c->orph_dnext;
                c->orph_dnext = orph;
                dbg_gen("delete later ino %lu", (unsigned long)orph->inum);
                return;
        }

        __orphan_drop(c, orph);
}

/**
 * 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)
{
        int err = 0;
        ino_t xattr_inum;
        union ubifs_key key;
        struct ubifs_dent_node *xent, *pxent = NULL;
        struct fscrypt_name nm = {0};
        struct ubifs_orphan *xattr_orphan;
        struct ubifs_orphan *orphan;

        orphan = orphan_add(c, inum, NULL);
        if (IS_ERR(orphan))
                return PTR_ERR(orphan);

        lowest_xent_key(c, &key, inum);
        while (1) {
                xent = ubifs_tnc_next_ent(c, &key, &nm);
                if (IS_ERR(xent)) {
                        err = PTR_ERR(xent);
                        if (err == -ENOENT)
                                break;
                        return err;
                }

                fname_name(&nm) = xent->name;
                fname_len(&nm) = le16_to_cpu(xent->nlen);
                xattr_inum = le64_to_cpu(xent->inum);

                xattr_orphan = orphan_add(c, xattr_inum, orphan);
                if (IS_ERR(xattr_orphan)) {
                        kfree(xent);
                        return PTR_ERR(xattr_orphan);
                }

                kfree(pxent);
                pxent = xent;
                key_read(c, &xent->key, &key);
        }
        kfree(pxent);

        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 *orph, *child_orph, *tmp_o;

        spin_lock(&c->orphan_lock);

        orph = lookup_orphan(c, inum);
        if (!orph) {
                spin_unlock(&c->orphan_lock);
                ubifs_err(c, "missing orphan ino %lu", (unsigned long)inum);
                dump_stack();

                return;
        }

        list_for_each_entry_safe(child_orph, tmp_o, &orph->child_list, child_list) {
                list_del(&child_orph->child_list);
                orphan_delete(c, child_orph);
        }
        
        orphan_delete(c, orph);

        spin_unlock(&c->orphan_lock);
}

/**
 * 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(c, orphan->new);
                ubifs_assert(c, !orphan->cmt);
                orphan->new = 0;
                orphan->cmt = 1;
                *last = orphan;
                last = &orphan->cnext;
        }
        *last = NULL;
        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 to the orphan head.
 * @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, 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);
        } 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);
        }
        return err;
}

/**
 * write_orph_node - write an orphan node.
 * @c: UBIFS file-system description object
 * @atomic: write atomically
 *
 * This function builds an orphan 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, 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(c, "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, 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;
                ubifs_assert(c, orphan->cmt);
                orph->inos[i] = cpu_to_le64(orphan->inum);
                orphan->cmt = 0;
                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);
        else
                /* Mark the last node of the commit */
                orph->cmt_no = cpu_to_le64((c->cmt_no) | (1ULL << 63));
        ubifs_assert(c, c->ohead_offs + len <= c->leb_size);
        ubifs_assert(c, c->ohead_lnum >= c->orph_first);
        ubifs_assert(c, 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 orphan nodes until there are no more to commit.
 * @c: UBIFS file-system description object
 * @atomic: write atomically
 *
 * This function writes orphan 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 */
                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;
                        orphan->cmt = 1;
                        *last = orphan;
                        last = &orphan->cnext;
                        cnt += 1;
                }
                *last = NULL;
                ubifs_assert(c, 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(c, "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, 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(c, !orphan->new);
                ubifs_assert(c, orphan->del);
                rb_erase(&orphan->rb, &c->orph_tree);
                list_del(&orphan->list);
                c->tot_orphans -= 1;
                dbg_gen("deleting orphan ino %lu", (unsigned long)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;
}

/**
 * ubifs_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.
 */
int ubifs_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->del = 1;
        orphan->dnext = c->orph_dnext;
        c->orph_dnext = orphan;
        dbg_mnt("ino %lu, new %d, tot %d", (unsigned long)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 orphan node read is passed and returned here
 * @outofdate: whether the LEB is out of date is returned here
 * @last_flagged: whether the end orphan 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;
        struct ubifs_ino_node *ino = NULL;
        unsigned long long cmt_no;
        ino_t inum;
        int i, n, err, first = 1;

        ino = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);
        if (!ino)
                return -ENOMEM;

        list_for_each_entry(snod, &sleb->nodes, list) {
                if (snod->type != UBIFS_ORPH_NODE) {
                        ubifs_err(c, "invalid node type %d in orphan area at %d:%d",
                                  snod->type, sleb->lnum, snod->offs);
                        ubifs_dump_node(c, snod->node);
                        err = -EINVAL;
                        goto out_free;
                }

                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 orphan 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 orphan node had a higher commit number and
                         * was flagged as the last written for that commit
                         * number. That makes this orphan node, out of date.
                         */
                        if (!first) {
                                ubifs_err(c, "out of order commit number %llu in orphan node at %d:%d",
                                          cmt_no, sleb->lnum, snod->offs);
                                ubifs_dump_node(c, snod->node);
                                err = -EINVAL;
                                goto out_free;
                        }
                        dbg_rcvry("out of date LEB %d", sleb->lnum);
                        *outofdate = 1;
                        err = 0;
                        goto out_free;
                }

                if (first)
                        first = 0;

                n = (le32_to_cpu(orph->ch.len) - UBIFS_ORPH_NODE_SZ) >> 3;
                for (i = 0; i < n; i++) {
                        union ubifs_key key1, key2;

                        inum = le64_to_cpu(orph->inos[i]);

                        ino_key_init(c, &key1, inum);
                        err = ubifs_tnc_lookup(c, &key1, ino);
                        if (err && err != -ENOENT)
                                goto out_free;

                        /*
                         * Check whether an inode can really get deleted.
                         * linkat() with O_TMPFILE allows rebirth of an inode.
                         */
                        if (err == 0 && ino->nlink == 0) {
                                dbg_rcvry("deleting orphaned inode %lu",
                                          (unsigned long)inum);

                                lowest_ino_key(c, &key1, inum);
                                highest_ino_key(c, &key2, inum);

                                err = ubifs_tnc_remove_range(c, &key1, &key2);
                                if (err)
                                        goto out_ro;
                        }

                        err = insert_dead_orphan(c, inum);
                        if (err)
                                goto out_free;
                }

                *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;
        }

        err = 0;
out_free:
        kfree(ino);
        return err;

out_ro:
        ubifs_ro_mode(c, err);
        kfree(ino);
        return err;
}

/**
 * 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 orphan nodes if the unmap didn't go
         * through. In addition, the last orphan node written for each commit is
         * marked (top bit of orph->cmt_no is set to 1). It is possible that
         * there are orphan 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, 1);
                if (IS_ERR(sleb)) {
                        if (PTR_ERR(sleb) == -EUCLEAN)
                                sleb = ubifs_recover_leb(c, lnum, 0,
                                                         c->sbuf, -1);
                        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 = ubifs_clear_orphans(c);

        return err;
}

/*
 * Everything below is related to debugging.
 */

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 bool dbg_find_orphan(struct ubifs_info *c, ino_t inum)
{
        bool found = false;

        spin_lock(&c->orphan_lock);
        found = !!lookup_orphan(c, inum);
        spin_unlock(&c->orphan_lock);

        return found;
}

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 check_orphan *o, *n;

        rbtree_postorder_for_each_entry_safe(o, n, root, rb)
                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(c, "found orphan node ino %lu, type %d",
                                  (unsigned long)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(c, "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(c, "missing orphan, ino %lu",
                                          (unsigned long)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;
        void *buf;

        /* Check no-orphans flag and skip this if no orphans */
        if (c->no_orphs)
                return 0;

        buf = __vmalloc(c->leb_size, GFP_NOFS, PAGE_KERNEL);
        if (!buf) {
                ubifs_err(c, "cannot allocate memory to check orphans");
                return 0;
        }

        for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
                struct ubifs_scan_leb *sleb;

                sleb = ubifs_scan(c, lnum, 0, buf, 0);
                if (IS_ERR(sleb)) {
                        err = PTR_ERR(sleb);
                        break;
                }

                err = dbg_read_orphans(ci, sleb);
                ubifs_scan_destroy(sleb);
                if (err)
                        break;
        }

        vfree(buf);
        return err;
}

static int dbg_check_orphans(struct ubifs_info *c)
{
        struct check_info ci;
        int err;

        if (!dbg_is_chk_orph(c))
                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(c, "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(c, "cannot scan TNC, error %d", err);
                goto out;
        }

        if (ci.missing) {
                ubifs_err(c, "%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;
}