fs/ext4/block_validity.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/block_validity.c
   4  *
   5  * Copyright (C) 2009
   6  * Theodore Ts'o (tytso@mit.edu)
   7  *
   8  * Track which blocks in the filesystem are metadata blocks that
   9  * should never be used as data blocks by files or directories.
  10  */
  11
  12 #include <linux/time.h>
  13 #include <linux/fs.h>
  14 #include <linux/namei.h>
  15 #include <linux/quotaops.h>
  16 #include <linux/buffer_head.h>
  17 #include <linux/swap.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/blkdev.h>
  20 #include <linux/slab.h>
  21 #include "ext4.h"
  22
  23 struct ext4_system_zone {
  24         struct rb_node  node;
  25         ext4_fsblk_t    start_blk;
  26         unsigned int    count;
  27         u32             ino;
  28 };
  29
  30 static struct kmem_cache *ext4_system_zone_cachep;
  31
  32 int __init ext4_init_system_zone(void)
  33 {
  34         ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0);
  35         if (ext4_system_zone_cachep == NULL)
  36                 return -ENOMEM;
  37         return 0;
  38 }
  39
  40 void ext4_exit_system_zone(void)
  41 {
  42         kmem_cache_destroy(ext4_system_zone_cachep);
  43 }
  44
  45 static inline int can_merge(struct ext4_system_zone *entry1,
  46                      struct ext4_system_zone *entry2)
  47 {
  48         if ((entry1->start_blk + entry1->count) == entry2->start_blk &&
  49             entry1->ino == entry2->ino)
  50                 return 1;
  51         return 0;
  52 }
  53
  54 /*
  55  * Mark a range of blocks as belonging to the "system zone" --- that
  56  * is, filesystem metadata blocks which should never be used by
  57  * inodes.
  58  */
  59 static int add_system_zone(struct ext4_sb_info *sbi,
  60                            ext4_fsblk_t start_blk,
  61                            unsigned int count, u32 ino)
  62 {
  63         struct ext4_system_zone *new_entry, *entry;
  64         struct rb_node **n = &sbi->system_blks.rb_node, *node;
  65         struct rb_node *parent = NULL, *new_node = NULL;
  66
  67         while (*n) {
  68                 parent = *n;
  69                 entry = rb_entry(parent, struct ext4_system_zone, node);
  70                 if (start_blk < entry->start_blk)
  71                         n = &(*n)->rb_left;
  72                 else if (start_blk >= (entry->start_blk + entry->count))
  73                         n = &(*n)->rb_right;
  74                 else    /* Unexpected overlap of system zones. */
  75                         return -EFSCORRUPTED;
  76         }
  77
  78         new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
  79                                      GFP_KERNEL);
  80         if (!new_entry)
  81                 return -ENOMEM;
  82         new_entry->start_blk = start_blk;
  83         new_entry->count = count;
  84         new_entry->ino = ino;
  85         new_node = &new_entry->node;
  86
  87         rb_link_node(new_node, parent, n);
  88         rb_insert_color(new_node, &sbi->system_blks);
  89
  90         /* Can we merge to the left? */
  91         node = rb_prev(new_node);
  92         if (node) {
  93                 entry = rb_entry(node, struct ext4_system_zone, node);
  94                 if (can_merge(entry, new_entry)) {
  95                         new_entry->start_blk = entry->start_blk;
  96                         new_entry->count += entry->count;
  97                         rb_erase(node, &sbi->system_blks);
  98                         kmem_cache_free(ext4_system_zone_cachep, entry);
  99                 }
 100         }
 101
 102         /* Can we merge to the right? */
 103         node = rb_next(new_node);
 104         if (node) {
 105                 entry = rb_entry(node, struct ext4_system_zone, node);
 106                 if (can_merge(new_entry, entry)) {
 107                         new_entry->count += entry->count;
 108                         rb_erase(node, &sbi->system_blks);
 109                         kmem_cache_free(ext4_system_zone_cachep, entry);
 110                 }
 111         }
 112         return 0;
 113 }
 114
 115 static void debug_print_tree(struct ext4_sb_info *sbi)
 116 {
 117         struct rb_node *node;
 118         struct ext4_system_zone *entry;
 119         int first = 1;
 120
 121         printk(KERN_INFO "System zones: ");
 122         node = rb_first(&sbi->system_blks);
 123         while (node) {
 124                 entry = rb_entry(node, struct ext4_system_zone, node);
 125                 printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
 126                        entry->start_blk, entry->start_blk + entry->count - 1);
 127                 first = 0;
 128                 node = rb_next(node);
 129         }
 130         printk(KERN_CONT "\n");
 131 }
 132
 133 static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino)
 134 {
 135         struct inode *inode;
 136         struct ext4_sb_info *sbi = EXT4_SB(sb);
 137         struct ext4_map_blocks map;
 138         u32 i = 0, num;
 139         int err = 0, n;
 140
 141         if ((ino < EXT4_ROOT_INO) ||
 142             (ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
 143                 return -EINVAL;
 144         inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
 145         if (IS_ERR(inode))
 146                 return PTR_ERR(inode);
 147         num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 148         while (i < num) {
 149                 cond_resched();
 150                 map.m_lblk = i;
 151                 map.m_len = num - i;
 152                 n = ext4_map_blocks(NULL, inode, &map, 0);
 153                 if (n < 0) {
 154                         err = n;
 155                         break;
 156                 }
 157                 if (n == 0) {
 158                         i++;
 159                 } else {
 160                         err = add_system_zone(sbi, map.m_pblk, n, ino);
 161                         if (err < 0) {
 162                                 if (err == -EFSCORRUPTED) {
 163                                         ext4_error(sb,
 164                                            "blocks %llu-%llu from inode %u "
 165                                            "overlap system zone", map.m_pblk,
 166                                            map.m_pblk + map.m_len - 1, ino);
 167                                 }
 168                                 break;
 169                         }
 170                         i += n;
 171                 }
 172         }
 173         iput(inode);
 174         return err;
 175 }
 176
 177 int ext4_setup_system_zone(struct super_block *sb)
 178 {
 179         ext4_group_t ngroups = ext4_get_groups_count(sb);
 180         struct ext4_sb_info *sbi = EXT4_SB(sb);
 181         struct ext4_group_desc *gdp;
 182         ext4_group_t i;
 183         int flex_size = ext4_flex_bg_size(sbi);
 184         int ret;
 185
 186         if (!test_opt(sb, BLOCK_VALIDITY)) {
 187                 if (EXT4_SB(sb)->system_blks.rb_node)
 188                         ext4_release_system_zone(sb);
 189                 return 0;
 190         }
 191         if (EXT4_SB(sb)->system_blks.rb_node)
 192                 return 0;
 193
 194         for (i=0; i < ngroups; i++) {
 195                 if (ext4_bg_has_super(sb, i) &&
 196                     ((i < 5) || ((i % flex_size) == 0)))
 197                         add_system_zone(sbi, ext4_group_first_block_no(sb, i),
 198                                         ext4_bg_num_gdb(sb, i) + 1, 0);
 199                 gdp = ext4_get_group_desc(sb, i, NULL);
 200                 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1, 0);
 201                 if (ret)
 202                         return ret;
 203                 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1, 0);
 204                 if (ret)
 205                         return ret;
 206                 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
 207                                 sbi->s_itb_per_group, 0);
 208                 if (ret)
 209                         return ret;
 210         }
 211         if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) {
 212                 ret = ext4_protect_reserved_inode(sb,
 213                                 le32_to_cpu(sbi->s_es->s_journal_inum));
 214                 if (ret)
 215                         return ret;
 216         }
 217
 218         if (test_opt(sb, DEBUG))
 219                 debug_print_tree(EXT4_SB(sb));
 220         return 0;
 221 }
 222
 223 /* Called when the filesystem is unmounted */
 224 void ext4_release_system_zone(struct super_block *sb)
 225 {
 226         struct ext4_system_zone *entry, *n;
 227
 228         rbtree_postorder_for_each_entry_safe(entry, n,
 229                         &EXT4_SB(sb)->system_blks, node)
 230                 kmem_cache_free(ext4_system_zone_cachep, entry);
 231
 232         EXT4_SB(sb)->system_blks = RB_ROOT;
 233 }
 234
 235 /*
 236  * Returns 1 if the passed-in block region (start_blk,
 237  * start_blk+count) is valid; 0 if some part of the block region
 238  * overlaps with filesystem metadata blocks.
 239  */
 240 int ext4_inode_block_valid(struct inode *inode, ext4_fsblk_t start_blk,
 241                            unsigned int count)
 242 {
 243         struct ext4_system_zone *entry;
 244         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 245         struct rb_node *n = sbi->system_blks.rb_node;
 246
 247         if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
 248             (start_blk + count < start_blk) ||
 249             (start_blk + count > ext4_blocks_count(sbi->s_es))) {
 250                 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
 251                 return 0;
 252         }
 253         while (n) {
 254                 entry = rb_entry(n, struct ext4_system_zone, node);
 255                 if (start_blk + count - 1 < entry->start_blk)
 256                         n = n->rb_left;
 257                 else if (start_blk >= (entry->start_blk + entry->count))
 258                         n = n->rb_right;
 259                 else {
 260                         if (entry->ino == inode->i_ino)
 261                                 return 1;
 262                         sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
 263                         return 0;
 264                 }
 265         }
 266         return 1;
 267 }
 268
 269 int ext4_check_blockref(const char *function, unsigned int line,
 270                         struct inode *inode, __le32 *p, unsigned int max)
 271 {
 272         struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
 273         __le32 *bref = p;
 274         unsigned int blk;
 275
 276         if (ext4_has_feature_journal(inode->i_sb) &&
 277             (inode->i_ino ==
 278              le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
 279                 return 0;
 280
 281         while (bref < p+max) {
 282                 blk = le32_to_cpu(*bref++);
 283                 if (blk &&
 284                     unlikely(!ext4_inode_block_valid(inode, blk, 1))) {
 285                         es->s_last_error_block = cpu_to_le64(blk);
 286                         ext4_error_inode(inode, function, line, blk,
 287                                          "invalid block");
 288                         return -EFSCORRUPTED;
 289                 }
 290         }
 291         return 0;
 292 }
 293