1 /* 2 * linux/fs/ext4/block_validity.c 3 * 4 * Copyright (C) 2009 5 * Theodore Ts'o (tytso@mit.edu) 6 * 7 * Track which blocks in the filesystem are metadata blocks that 8 * should never be used as data blocks by files or directories. 9 */ 10 11 #include <linux/time.h> 12 #include <linux/fs.h> 13 #include <linux/namei.h> 14 #include <linux/quotaops.h> 15 #include <linux/buffer_head.h> 16 #include <linux/module.h> 17 #include <linux/swap.h> 18 #include <linux/pagemap.h> 19 #include <linux/blkdev.h> 20 #include <linux/mutex.h> 21 #include <linux/slab.h> 22 #include "ext4.h" 23 24 struct ext4_system_zone { 25 struct rb_node node; 26 ext4_fsblk_t start_blk; 27 unsigned int count; 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 return 1; 50 return 0; 51 } 52 53 /* 54 * Mark a range of blocks as belonging to the "system zone" --- that 55 * is, filesystem metadata blocks which should never be used by 56 * inodes. 57 */ 58 static int add_system_zone(struct ext4_sb_info *sbi, 59 ext4_fsblk_t start_blk, 60 unsigned int count) 61 { 62 struct ext4_system_zone *new_entry = NULL, *entry; 63 struct rb_node **n = &sbi->system_blks.rb_node, *node; 64 struct rb_node *parent = NULL, *new_node = NULL; 65 66 while (*n) { 67 parent = *n; 68 entry = rb_entry(parent, struct ext4_system_zone, node); 69 if (start_blk < entry->start_blk) 70 n = &(*n)->rb_left; 71 else if (start_blk >= (entry->start_blk + entry->count)) 72 n = &(*n)->rb_right; 73 else { 74 if (start_blk + count > (entry->start_blk + 75 entry->count)) 76 entry->count = (start_blk + count - 77 entry->start_blk); 78 new_node = *n; 79 new_entry = rb_entry(new_node, struct ext4_system_zone, 80 node); 81 break; 82 } 83 } 84 85 if (!new_entry) { 86 new_entry = kmem_cache_alloc(ext4_system_zone_cachep, 87 GFP_KERNEL); 88 if (!new_entry) 89 return -ENOMEM; 90 new_entry->start_blk = start_blk; 91 new_entry->count = count; 92 new_node = &new_entry->node; 93 94 rb_link_node(new_node, parent, n); 95 rb_insert_color(new_node, &sbi->system_blks); 96 } 97 98 /* Can we merge to the left? */ 99 node = rb_prev(new_node); 100 if (node) { 101 entry = rb_entry(node, struct ext4_system_zone, node); 102 if (can_merge(entry, new_entry)) { 103 new_entry->start_blk = entry->start_blk; 104 new_entry->count += entry->count; 105 rb_erase(node, &sbi->system_blks); 106 kmem_cache_free(ext4_system_zone_cachep, entry); 107 } 108 } 109 110 /* Can we merge to the right? */ 111 node = rb_next(new_node); 112 if (node) { 113 entry = rb_entry(node, struct ext4_system_zone, node); 114 if (can_merge(new_entry, entry)) { 115 new_entry->count += entry->count; 116 rb_erase(node, &sbi->system_blks); 117 kmem_cache_free(ext4_system_zone_cachep, entry); 118 } 119 } 120 return 0; 121 } 122 123 static void debug_print_tree(struct ext4_sb_info *sbi) 124 { 125 struct rb_node *node; 126 struct ext4_system_zone *entry; 127 int first = 1; 128 129 printk(KERN_INFO "System zones: "); 130 node = rb_first(&sbi->system_blks); 131 while (node) { 132 entry = rb_entry(node, struct ext4_system_zone, node); 133 printk("%s%llu-%llu", first ? "" : ", ", 134 entry->start_blk, entry->start_blk + entry->count - 1); 135 first = 0; 136 node = rb_next(node); 137 } 138 printk("\n"); 139 } 140 141 int ext4_setup_system_zone(struct super_block *sb) 142 { 143 ext4_group_t ngroups = ext4_get_groups_count(sb); 144 struct ext4_sb_info *sbi = EXT4_SB(sb); 145 struct ext4_group_desc *gdp; 146 ext4_group_t i; 147 int flex_size = ext4_flex_bg_size(sbi); 148 int ret; 149 150 if (!test_opt(sb, BLOCK_VALIDITY)) { 151 if (EXT4_SB(sb)->system_blks.rb_node) 152 ext4_release_system_zone(sb); 153 return 0; 154 } 155 if (EXT4_SB(sb)->system_blks.rb_node) 156 return 0; 157 158 for (i=0; i < ngroups; i++) { 159 if (ext4_bg_has_super(sb, i) && 160 ((i < 5) || ((i % flex_size) == 0))) 161 add_system_zone(sbi, ext4_group_first_block_no(sb, i), 162 ext4_bg_num_gdb(sb, i) + 1); 163 gdp = ext4_get_group_desc(sb, i, NULL); 164 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1); 165 if (ret) 166 return ret; 167 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1); 168 if (ret) 169 return ret; 170 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp), 171 sbi->s_itb_per_group); 172 if (ret) 173 return ret; 174 } 175 176 if (test_opt(sb, DEBUG)) 177 debug_print_tree(EXT4_SB(sb)); 178 return 0; 179 } 180 181 /* Called when the filesystem is unmounted */ 182 void ext4_release_system_zone(struct super_block *sb) 183 { 184 struct rb_node *n = EXT4_SB(sb)->system_blks.rb_node; 185 struct rb_node *parent; 186 struct ext4_system_zone *entry; 187 188 while (n) { 189 /* Do the node's children first */ 190 if (n->rb_left) { 191 n = n->rb_left; 192 continue; 193 } 194 if (n->rb_right) { 195 n = n->rb_right; 196 continue; 197 } 198 /* 199 * The node has no children; free it, and then zero 200 * out parent's link to it. Finally go to the 201 * beginning of the loop and try to free the parent 202 * node. 203 */ 204 parent = rb_parent(n); 205 entry = rb_entry(n, struct ext4_system_zone, node); 206 kmem_cache_free(ext4_system_zone_cachep, entry); 207 if (!parent) 208 EXT4_SB(sb)->system_blks = RB_ROOT; 209 else if (parent->rb_left == n) 210 parent->rb_left = NULL; 211 else if (parent->rb_right == n) 212 parent->rb_right = NULL; 213 n = parent; 214 } 215 EXT4_SB(sb)->system_blks = RB_ROOT; 216 } 217 218 /* 219 * Returns 1 if the passed-in block region (start_blk, 220 * start_blk+count) is valid; 0 if some part of the block region 221 * overlaps with filesystem metadata blocks. 222 */ 223 int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, 224 unsigned int count) 225 { 226 struct ext4_system_zone *entry; 227 struct rb_node *n = sbi->system_blks.rb_node; 228 229 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || 230 (start_blk + count < start_blk) || 231 (start_blk + count > ext4_blocks_count(sbi->s_es))) { 232 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); 233 return 0; 234 } 235 while (n) { 236 entry = rb_entry(n, struct ext4_system_zone, node); 237 if (start_blk + count - 1 < entry->start_blk) 238 n = n->rb_left; 239 else if (start_blk >= (entry->start_blk + entry->count)) 240 n = n->rb_right; 241 else { 242 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); 243 return 0; 244 } 245 } 246 return 1; 247 } 248 249 int ext4_check_blockref(const char *function, unsigned int line, 250 struct inode *inode, __le32 *p, unsigned int max) 251 { 252 struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; 253 __le32 *bref = p; 254 unsigned int blk; 255 256 while (bref < p+max) { 257 blk = le32_to_cpu(*bref++); 258 if (blk && 259 unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb), 260 blk, 1))) { 261 es->s_last_error_block = cpu_to_le64(blk); 262 ext4_error_inode(inode, function, line, blk, 263 "invalid block"); 264 return -EIO; 265 } 266 } 267 return 0; 268 } 269