- 根目录:
- fs
- ubifs
- tnc_misc.c
/*
* 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"
/**
* ubifs_tnc_levelorder_next - next TNC tree element in levelorder traversal.
* @zr: root of the subtree to traverse
* @znode: previous znode
*
* This function implements levelorder TNC traversal. The LNC is ignored.
* Returns the next element or %NULL if @znode is already the last one.
*/
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;
}
}
}
/**
* ubifs_search_zbranch - search znode branch.
* @c: UBIFS file-system description object
* @znode: znode to search in
* @key: key to search for
* @n: znode branch slot number is returned here
*
* This is a helper function which search branch with key @key in @znode using
* binary search. The result of the search may be:
* o exact match, then %1 is returned, and the slot number of the branch is
* stored in @n;
* o no exact match, then %0 is returned and the slot number of the left
* closest branch is returned in @n; the slot if all keys in this znode are
* greater than @key, then %-1 is returned in @n.
*/
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;
}
/**
* ubifs_tnc_postorder_first - find first znode to do postorder tree traversal.
* @znode: znode to start at (root of the sub-tree to traverse)
*
* Find the lowest leftmost znode in a subtree of the TNC tree. The LNC is
* ignored.
*/
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;
}
/**
* ubifs_tnc_postorder_next - next TNC tree element in postorder traversal.
* @znode: previous znode
*
* This function implements postorder TNC traversal. The LNC is ignored.
* Returns the next element or %NULL if @znode is already the last one.
*/
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);
}
/**
* ubifs_destroy_tnc_subtree - destroy all znodes connected to a subtree.
* @znode: znode defining subtree to destroy
*
* This function destroys subtree of the TNC tree. Returns number of clean
* znodes in the subtree.
*/
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);
}
}
/**
* read_znode - read an indexing node from flash and fill znode.
* @c: UBIFS file-system description object
* @lnum: LEB of the indexing node to read
* @offs: node offset
* @len: node length
* @znode: znode to read to
*
* This function reads an indexing node from the flash media and fills znode
* with the read data. Returns zero in case of success and a negative error
* code in case of failure. The read indexing node is validated and if anything
* is wrong with it, this function prints complaint messages and returns
* %-EINVAL.
*/
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(c, "current fanout %d, branch count %d",
c->fanout, znode->child_cnt);
ubifs_err(c, "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(c, "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(c, "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(c, "bad target node (type %d) length (%d)",
type, zbr->len);
ubifs_err(c, "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(c, "bad target node (type %d) length (%d)",
type, zbr->len);
ubifs_err(c, "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(c, "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(c, "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(c, "bad indexing node at LEB %d:%d, error %d", lnum, offs, err);
ubifs_dump_node(c, idx);
kfree(idx);
return -EINVAL;
}
/**
* ubifs_load_znode - load znode to TNC cache.
* @c: UBIFS file-system description object
* @zbr: znode branch
* : znode's parent
* @iip: index in parent
*
* This function loads znode pointed to by @zbr into the TNC cache and
* returns pointer to it in case of success and a negative error code in case
* of failure.
*/
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);
}
/**
* ubifs_tnc_read_node - read a leaf node from the flash media.
* @c: UBIFS file-system description object
* @zbr: key and position of the node
* @node: node is returned here
*
* This function reads a node defined by @zbr from the flash media. Returns
* zero in case of success or a negative negative error code in case of
* failure.
*/
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(c, "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;
}