298 lines
7.4 KiB
C
298 lines
7.4 KiB
C
/*
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* linux/fs/ext4/block_validity.c
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*
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* Copyright (C) 2009
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* Theodore Ts'o (tytso@mit.edu)
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*
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* Track which blocks in the filesystem are metadata blocks that
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* should never be used as data blocks by files or directories.
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*/
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#include <linux/time.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/quotaops.h>
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#include <linux/buffer_head.h>
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#include <linux/swap.h>
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#include <linux/pagemap.h>
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#include <linux/blkdev.h>
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#include <linux/slab.h>
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#include "ext4.h"
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struct ext4_system_zone {
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struct rb_node node;
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ext4_fsblk_t start_blk;
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unsigned int count;
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};
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static struct kmem_cache *ext4_system_zone_cachep;
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int __init ext4_init_system_zone(void)
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{
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ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0);
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if (ext4_system_zone_cachep == NULL)
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return -ENOMEM;
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return 0;
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}
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void ext4_exit_system_zone(void)
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{
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kmem_cache_destroy(ext4_system_zone_cachep);
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}
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static inline int can_merge(struct ext4_system_zone *entry1,
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struct ext4_system_zone *entry2)
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{
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if ((entry1->start_blk + entry1->count) == entry2->start_blk)
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return 1;
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return 0;
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}
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/*
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* Mark a range of blocks as belonging to the "system zone" --- that
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* is, filesystem metadata blocks which should never be used by
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* inodes.
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*/
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static int add_system_zone(struct ext4_sb_info *sbi,
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ext4_fsblk_t start_blk,
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unsigned int count)
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{
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struct ext4_system_zone *new_entry = NULL, *entry;
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struct rb_node **n = &sbi->system_blks.rb_node, *node;
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struct rb_node *parent = NULL, *new_node = NULL;
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while (*n) {
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parent = *n;
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entry = rb_entry(parent, struct ext4_system_zone, node);
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if (start_blk < entry->start_blk)
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n = &(*n)->rb_left;
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else if (start_blk >= (entry->start_blk + entry->count))
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n = &(*n)->rb_right;
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else {
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if (start_blk + count > (entry->start_blk +
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entry->count))
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entry->count = (start_blk + count -
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entry->start_blk);
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new_node = *n;
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new_entry = rb_entry(new_node, struct ext4_system_zone,
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node);
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break;
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}
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}
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if (!new_entry) {
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new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
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GFP_KERNEL);
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if (!new_entry)
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return -ENOMEM;
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new_entry->start_blk = start_blk;
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new_entry->count = count;
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new_node = &new_entry->node;
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rb_link_node(new_node, parent, n);
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rb_insert_color(new_node, &sbi->system_blks);
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}
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/* Can we merge to the left? */
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node = rb_prev(new_node);
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if (node) {
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entry = rb_entry(node, struct ext4_system_zone, node);
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if (can_merge(entry, new_entry)) {
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new_entry->start_blk = entry->start_blk;
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new_entry->count += entry->count;
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rb_erase(node, &sbi->system_blks);
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kmem_cache_free(ext4_system_zone_cachep, entry);
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}
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}
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/* Can we merge to the right? */
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node = rb_next(new_node);
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if (node) {
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entry = rb_entry(node, struct ext4_system_zone, node);
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if (can_merge(new_entry, entry)) {
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new_entry->count += entry->count;
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rb_erase(node, &sbi->system_blks);
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kmem_cache_free(ext4_system_zone_cachep, entry);
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}
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}
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return 0;
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}
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static void debug_print_tree(struct ext4_sb_info *sbi)
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{
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struct rb_node *node;
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struct ext4_system_zone *entry;
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int first = 1;
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printk(KERN_INFO "System zones: ");
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node = rb_first(&sbi->system_blks);
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while (node) {
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entry = rb_entry(node, struct ext4_system_zone, node);
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printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
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entry->start_blk, entry->start_blk + entry->count - 1);
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first = 0;
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node = rb_next(node);
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}
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printk(KERN_CONT "\n");
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}
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static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino)
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{
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struct inode *inode;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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struct ext4_map_blocks map;
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u32 i = 0, num;
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int err = 0, n;
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if ((ino < EXT4_ROOT_INO) ||
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(ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
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return -EINVAL;
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inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
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if (IS_ERR(inode))
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return PTR_ERR(inode);
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num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
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while (i < num) {
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cond_resched();
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map.m_lblk = i;
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map.m_len = num - i;
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n = ext4_map_blocks(NULL, inode, &map, 0);
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if (n < 0) {
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err = n;
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break;
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}
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if (n == 0) {
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i++;
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} else {
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if (!ext4_data_block_valid(sbi, map.m_pblk, n)) {
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ext4_error(sb, "blocks %llu-%llu from inode %u "
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"overlap system zone", map.m_pblk,
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map.m_pblk + map.m_len - 1, ino);
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err = -EFSCORRUPTED;
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break;
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}
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err = add_system_zone(sbi, map.m_pblk, n);
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if (err < 0)
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break;
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i += n;
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}
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}
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iput(inode);
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return err;
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}
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int ext4_setup_system_zone(struct super_block *sb)
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{
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ext4_group_t ngroups = ext4_get_groups_count(sb);
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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struct ext4_group_desc *gdp;
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ext4_group_t i;
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int flex_size = ext4_flex_bg_size(sbi);
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int ret;
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if (!test_opt(sb, BLOCK_VALIDITY)) {
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if (EXT4_SB(sb)->system_blks.rb_node)
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ext4_release_system_zone(sb);
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return 0;
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}
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if (EXT4_SB(sb)->system_blks.rb_node)
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return 0;
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for (i=0; i < ngroups; i++) {
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if (ext4_bg_has_super(sb, i) &&
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((i < 5) || ((i % flex_size) == 0)))
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add_system_zone(sbi, ext4_group_first_block_no(sb, i),
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ext4_bg_num_gdb(sb, i) + 1);
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gdp = ext4_get_group_desc(sb, i, NULL);
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ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
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if (ret)
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return ret;
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ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
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if (ret)
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return ret;
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ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
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sbi->s_itb_per_group);
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if (ret)
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return ret;
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}
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if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) {
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ret = ext4_protect_reserved_inode(sb,
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le32_to_cpu(sbi->s_es->s_journal_inum));
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if (ret)
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return ret;
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}
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if (test_opt(sb, DEBUG))
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debug_print_tree(EXT4_SB(sb));
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return 0;
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}
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/* Called when the filesystem is unmounted */
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void ext4_release_system_zone(struct super_block *sb)
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{
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struct ext4_system_zone *entry, *n;
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rbtree_postorder_for_each_entry_safe(entry, n,
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&EXT4_SB(sb)->system_blks, node)
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kmem_cache_free(ext4_system_zone_cachep, entry);
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EXT4_SB(sb)->system_blks = RB_ROOT;
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}
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/*
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* Returns 1 if the passed-in block region (start_blk,
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* start_blk+count) is valid; 0 if some part of the block region
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* overlaps with filesystem metadata blocks.
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*/
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int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
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unsigned int count)
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{
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struct ext4_system_zone *entry;
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struct rb_node *n = sbi->system_blks.rb_node;
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if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
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(start_blk + count < start_blk) ||
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(start_blk + count > ext4_blocks_count(sbi->s_es))) {
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sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
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return 0;
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}
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while (n) {
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entry = rb_entry(n, struct ext4_system_zone, node);
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if (start_blk + count - 1 < entry->start_blk)
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n = n->rb_left;
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else if (start_blk >= (entry->start_blk + entry->count))
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n = n->rb_right;
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else {
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sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
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return 0;
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}
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}
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return 1;
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}
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int ext4_check_blockref(const char *function, unsigned int line,
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struct inode *inode, __le32 *p, unsigned int max)
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{
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struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
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__le32 *bref = p;
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unsigned int blk;
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if (ext4_has_feature_journal(inode->i_sb) &&
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(inode->i_ino ==
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le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
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return 0;
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while (bref < p+max) {
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blk = le32_to_cpu(*bref++);
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if (blk &&
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unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
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blk, 1))) {
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es->s_last_error_block = cpu_to_le64(blk);
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ext4_error_inode(inode, function, line, blk,
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"invalid block");
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return -EFSCORRUPTED;
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}
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}
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return 0;
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}
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