tnc_misc.c

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/*
 * 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 miscelanious TNC-related functions shared betweend
 * different files. This file does not form any logically separate TNC
 * sub-system. The file was created because there is a lot of TNC code and
 * putting it all in one file would make that file too big and unreadable.
 */

#include "ubifs.h"

struct ubifs_znode *ubifs_tnc_levelorder_next(struct ubifs_znode *zr,
                          struct ubifs_znode *znode)
{
    int level, iip, level_search = 0;
    struct ubifs_znode *zn;

    ubifs_assert(zr);

    if (unlikely(!znode))
        return zr;

    if (unlikely(znode == zr)) {
        if (znode->level == 0)
            return NULL;
        return ubifs_tnc_find_child(zr, 0);
    }

    level = znode->level;

    iip = znode->iip;
    while (1) {
        ubifs_assert(znode->level <= zr->level);

        /*
         * First walk up until there is a znode with next branch to
         * look at.
         */
        while (znode->parent != zr && iip >= znode->parent->child_cnt) {
            znode = znode->parent;
            iip = znode->iip;
        }

        if (unlikely(znode->parent == zr &&
                 iip >= znode->parent->child_cnt)) {
            /* This level is done, switch to the lower one */
            level -= 1;
            if (level_search || level < 0)
                /*
                 * We were already looking for znode at lower
                 * level ('level_search'). As we are here
                 * again, it just does not exist. Or all levels
                 * were finished ('level < 0').
                 */
                return NULL;

            level_search = 1;
            iip = -1;
            znode = ubifs_tnc_find_child(zr, 0);
            ubifs_assert(znode);
        }

        /* Switch to the next index */
        zn = ubifs_tnc_find_child(znode->parent, iip + 1);
        if (!zn) {
            /* No more children to look at, we have walk up */
            iip = znode->parent->child_cnt;
            continue;
        }

        /* Walk back down to the level we came from ('level') */
        while (zn->level != level) {
            znode = zn;
            zn = ubifs_tnc_find_child(zn, 0);
            if (!zn) {
                /*
                 * This path is not too deep so it does not
                 * reach 'level'. Try next path.
                 */
                iip = znode->iip;
                break;
            }
        }

        if (zn) {
            ubifs_assert(zn->level >= 0);
            return zn;
        }
    }
}

int ubifs_search_zbranch(const struct ubifs_info *c,
             const struct ubifs_znode *znode,
             const union ubifs_key *key, int *n)
{
    int beg = 0, end = znode->child_cnt, uninitialized_var(mid);
    int uninitialized_var(cmp);
    const struct ubifs_zbranch *zbr = &znode->zbranch[0];

    ubifs_assert(end > beg);

    while (end > beg) {
        mid = (beg + end) >> 1;
        cmp = keys_cmp(c, key, &zbr[mid].key);
        if (cmp > 0)
            beg = mid + 1;
        else if (cmp < 0)
            end = mid;
        else {
            *n = mid;
            return 1;
        }
    }

    *n = end - 1;

    /* The insert point is after *n */
    ubifs_assert(*n >= -1 && *n < znode->child_cnt);
    if (*n == -1)
        ubifs_assert(keys_cmp(c, key, &zbr[0].key) < 0);
    else
        ubifs_assert(keys_cmp(c, key, &zbr[*n].key) > 0);
    if (*n + 1 < znode->child_cnt)
        ubifs_assert(keys_cmp(c, key, &zbr[*n + 1].key) < 0);

    return 0;
}

struct ubifs_znode *ubifs_tnc_postorder_first(struct ubifs_znode *znode)
{
    if (unlikely(!znode))
        return NULL;

    while (znode->level > 0) {
        struct ubifs_znode *child;

        child = ubifs_tnc_find_child(znode, 0);
        if (!child)
            return znode;
        znode = child;
    }

    return znode;
}

struct ubifs_znode *ubifs_tnc_postorder_next(struct ubifs_znode *znode)
{
    struct ubifs_znode *zn;

    ubifs_assert(znode);
    if (unlikely(!znode->parent))
        return NULL;

    /* Switch to the next index in the parent */
    zn = ubifs_tnc_find_child(znode->parent, znode->iip + 1);
    if (!zn)
        /* This is in fact the last child, return parent */
        return znode->parent;

    /* Go to the first znode in this new subtree */
    return ubifs_tnc_postorder_first(zn);
}

long ubifs_destroy_tnc_subtree(struct ubifs_znode *znode)
{
    struct ubifs_znode *zn = ubifs_tnc_postorder_first(znode);
    long clean_freed = 0;
    int n;

    ubifs_assert(zn);
    while (1) {
        for (n = 0; n < zn->child_cnt; n++) {
            if (!zn->zbranch[n].znode)
                continue;

            if (zn->level > 0 &&
                !ubifs_zn_dirty(zn->zbranch[n].znode))
                clean_freed += 1;

            cond_resched();
            kfree(zn->zbranch[n].znode);
        }

        if (zn == znode) {
            if (!ubifs_zn_dirty(zn))
                clean_freed += 1;
            kfree(zn);
            return clean_freed;
        }

        zn = ubifs_tnc_postorder_next(zn);
    }
}

static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
              struct ubifs_znode *znode)
{
    int i, err, type, cmp;
    struct ubifs_idx_node *idx;

    idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
    if (!idx)
        return -ENOMEM;

    err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
    if (err < 0) {
        kfree(idx);
        return err;
    }

    znode->child_cnt = le16_to_cpu(idx->child_cnt);
    znode->level = le16_to_cpu(idx->level);

    dbg_tnc("LEB %d:%d, level %d, %d branch",
        lnum, offs, znode->level, znode->child_cnt);

    if (znode->child_cnt > c->fanout || znode->level > UBIFS_MAX_LEVELS) {
        ubifs_err("current fanout %d, branch count %d",
              c->fanout, znode->child_cnt);
        ubifs_err("max levels %d, znode level %d",
              UBIFS_MAX_LEVELS, znode->level);
        err = 1;
        goto out_dump;
    }

    for (i = 0; i < znode->child_cnt; i++) {
        const struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
        struct ubifs_zbranch *zbr = &znode->zbranch[i];

        key_read(c, &br->key, &zbr->key);
        zbr->lnum = le32_to_cpu(br->lnum);
        zbr->offs = le32_to_cpu(br->offs);
        zbr->len  = le32_to_cpu(br->len);
        zbr->znode = NULL;

        /* Validate branch */

        if (zbr->lnum < c->main_first ||
            zbr->lnum >= c->leb_cnt || zbr->offs < 0 ||
            zbr->offs + zbr->len > c->leb_size || zbr->offs & 7) {
            ubifs_err("bad branch %d", i);
            err = 2;
            goto out_dump;
        }

        switch (key_type(c, &zbr->key)) {
        case UBIFS_INO_KEY:
        case UBIFS_DATA_KEY:
        case UBIFS_DENT_KEY:
        case UBIFS_XENT_KEY:
            break;
        default:
            ubifs_err("bad key type at slot %d: %d",
                  i, key_type(c, &zbr->key));
            err = 3;
            goto out_dump;
        }

        if (znode->level)
            continue;

        type = key_type(c, &zbr->key);
        if (c->ranges[type].max_len == 0) {
            if (zbr->len != c->ranges[type].len) {
                ubifs_err("bad target node (type %d) length (%d)",
                      type, zbr->len);
                ubifs_err("have to be %d", c->ranges[type].len);
                err = 4;
                goto out_dump;
            }
        } else if (zbr->len < c->ranges[type].min_len ||
               zbr->len > c->ranges[type].max_len) {
            ubifs_err("bad target node (type %d) length (%d)",
                  type, zbr->len);
            ubifs_err("have to be in range of %d-%d",
                  c->ranges[type].min_len,
                  c->ranges[type].max_len);
            err = 5;
            goto out_dump;
        }
    }

    /*
     * Ensure that the next key is greater or equivalent to the
     * previous one.
     */
    for (i = 0; i < znode->child_cnt - 1; i++) {
        const union ubifs_key *key1, *key2;

        key1 = &znode->zbranch[i].key;
        key2 = &znode->zbranch[i + 1].key;

        cmp = keys_cmp(c, key1, key2);
        if (cmp > 0) {
            ubifs_err("bad key order (keys %d and %d)", i, i + 1);
            err = 6;
            goto out_dump;
        } else if (cmp == 0 && !is_hash_key(c, key1)) {
            /* These can only be keys with colliding hash */
            ubifs_err("keys %d and %d are not hashed but equivalent",
                  i, i + 1);
            err = 7;
            goto out_dump;
        }
    }

    kfree(idx);
    return 0;

out_dump:
    ubifs_err("bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
    ubifs_dump_node(c, idx);
    kfree(idx);
    return -EINVAL;
}

struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
                     struct ubifs_zbranch *zbr,
                     struct ubifs_znode *parent, int iip)
{
    int err;
    struct ubifs_znode *znode;

    ubifs_assert(!zbr->znode);
    /*
     * A slab cache is not presently used for znodes because the znode size
     * depends on the fanout which is stored in the superblock.
     */
    znode = kzalloc(c->max_znode_sz, GFP_NOFS);
    if (!znode)
        return ERR_PTR(-ENOMEM);

    err = read_znode(c, zbr->lnum, zbr->offs, zbr->len, znode);
    if (err)
        goto out;

    atomic_long_inc(&c->clean_zn_cnt);

    /*
     * Increment the global clean znode counter as well. It is OK that
     * global and per-FS clean znode counters may be inconsistent for some
     * short time (because we might be preempted at this point), the global
     * one is only used in shrinker.
     */
    atomic_long_inc(&ubifs_clean_zn_cnt);

    zbr->znode = znode;
    znode->parent = parent;
    znode->time = get_seconds();
    znode->iip = iip;

    return znode;

out:
    kfree(znode);
    return ERR_PTR(err);
}

int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
            void *node)
{
    union ubifs_key key1, *key = &zbr->key;
    int err, type = key_type(c, key);
    struct ubifs_wbuf *wbuf;

    /*
     * 'zbr' has to point to on-flash node. The node may sit in a bud and
     * may even be in a write buffer, so we have to take care about this.
     */
    wbuf = ubifs_get_wbuf(c, zbr->lnum);
    if (wbuf)
        err = ubifs_read_node_wbuf(wbuf, node, type, zbr->len,
                       zbr->lnum, zbr->offs);
    else
        err = ubifs_read_node(c, node, type, zbr->len, zbr->lnum,
                      zbr->offs);

    if (err) {
        dbg_tnck(key, "key ");
        return err;
    }

    /* Make sure the key of the read node is correct */
    key_read(c, node + UBIFS_KEY_OFFSET, &key1);
    if (!keys_eq(c, key, &key1)) {
        ubifs_err("bad key in node at LEB %d:%d",
              zbr->lnum, zbr->offs);
        dbg_tnck(key, "looked for key ");
        dbg_tnck(&key1, "but found node's key ");
        ubifs_dump_node(c, node);
        return -EINVAL;
    }

    return 0;
}