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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
6fd058f7 TT |
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> | |
6fd058f7 TT |
17 | #include <linux/swap.h> |
18 | #include <linux/pagemap.h> | |
6fd058f7 | 19 | #include <linux/blkdev.h> |
5a0e3ad6 | 20 | #include <linux/slab.h> |
6fd058f7 TT |
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 | }; | |
28 | ||
29 | static struct kmem_cache *ext4_system_zone_cachep; | |
30 | ||
5dabfc78 | 31 | int __init ext4_init_system_zone(void) |
6fd058f7 | 32 | { |
16828088 | 33 | ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0); |
6fd058f7 TT |
34 | if (ext4_system_zone_cachep == NULL) |
35 | return -ENOMEM; | |
36 | return 0; | |
37 | } | |
38 | ||
5dabfc78 | 39 | void ext4_exit_system_zone(void) |
6fd058f7 | 40 | { |
7727ae52 | 41 | rcu_barrier(); |
6fd058f7 TT |
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 | ||
7727ae52 | 53 | static void release_system_zone(struct ext4_system_blocks *system_blks) |
54 | { | |
55 | struct ext4_system_zone *entry, *n; | |
56 | ||
57 | rbtree_postorder_for_each_entry_safe(entry, n, | |
58 | &system_blks->root, node) | |
59 | kmem_cache_free(ext4_system_zone_cachep, entry); | |
60 | } | |
61 | ||
6fd058f7 TT |
62 | /* |
63 | * Mark a range of blocks as belonging to the "system zone" --- that | |
64 | * is, filesystem metadata blocks which should never be used by | |
65 | * inodes. | |
66 | */ | |
7727ae52 | 67 | static int add_system_zone(struct ext4_system_blocks *system_blks, |
6fd058f7 TT |
68 | ext4_fsblk_t start_blk, |
69 | unsigned int count) | |
70 | { | |
71 | struct ext4_system_zone *new_entry = NULL, *entry; | |
7727ae52 | 72 | struct rb_node **n = &system_blks->root.rb_node, *node; |
6fd058f7 TT |
73 | struct rb_node *parent = NULL, *new_node = NULL; |
74 | ||
75 | while (*n) { | |
76 | parent = *n; | |
77 | entry = rb_entry(parent, struct ext4_system_zone, node); | |
78 | if (start_blk < entry->start_blk) | |
79 | n = &(*n)->rb_left; | |
80 | else if (start_blk >= (entry->start_blk + entry->count)) | |
81 | n = &(*n)->rb_right; | |
82 | else { | |
60e6679e | 83 | if (start_blk + count > (entry->start_blk + |
6fd058f7 | 84 | entry->count)) |
60e6679e | 85 | entry->count = (start_blk + count - |
6fd058f7 TT |
86 | entry->start_blk); |
87 | new_node = *n; | |
88 | new_entry = rb_entry(new_node, struct ext4_system_zone, | |
89 | node); | |
90 | break; | |
91 | } | |
92 | } | |
93 | ||
94 | if (!new_entry) { | |
95 | new_entry = kmem_cache_alloc(ext4_system_zone_cachep, | |
96 | GFP_KERNEL); | |
97 | if (!new_entry) | |
98 | return -ENOMEM; | |
99 | new_entry->start_blk = start_blk; | |
100 | new_entry->count = count; | |
101 | new_node = &new_entry->node; | |
102 | ||
103 | rb_link_node(new_node, parent, n); | |
7727ae52 | 104 | rb_insert_color(new_node, &system_blks->root); |
6fd058f7 TT |
105 | } |
106 | ||
107 | /* Can we merge to the left? */ | |
108 | node = rb_prev(new_node); | |
109 | if (node) { | |
110 | entry = rb_entry(node, struct ext4_system_zone, node); | |
111 | if (can_merge(entry, new_entry)) { | |
112 | new_entry->start_blk = entry->start_blk; | |
113 | new_entry->count += entry->count; | |
7727ae52 | 114 | rb_erase(node, &system_blks->root); |
6fd058f7 TT |
115 | kmem_cache_free(ext4_system_zone_cachep, entry); |
116 | } | |
117 | } | |
118 | ||
119 | /* Can we merge to the right? */ | |
120 | node = rb_next(new_node); | |
121 | if (node) { | |
122 | entry = rb_entry(node, struct ext4_system_zone, node); | |
123 | if (can_merge(new_entry, entry)) { | |
124 | new_entry->count += entry->count; | |
7727ae52 | 125 | rb_erase(node, &system_blks->root); |
6fd058f7 TT |
126 | kmem_cache_free(ext4_system_zone_cachep, entry); |
127 | } | |
128 | } | |
129 | return 0; | |
130 | } | |
131 | ||
132 | static void debug_print_tree(struct ext4_sb_info *sbi) | |
133 | { | |
134 | struct rb_node *node; | |
135 | struct ext4_system_zone *entry; | |
69000d82 | 136 | struct ext4_system_blocks *system_blks; |
6fd058f7 TT |
137 | int first = 1; |
138 | ||
139 | printk(KERN_INFO "System zones: "); | |
69000d82 PT |
140 | rcu_read_lock(); |
141 | system_blks = rcu_dereference(sbi->system_blks); | |
142 | node = rb_first(&system_blks->root); | |
6fd058f7 TT |
143 | while (node) { |
144 | entry = rb_entry(node, struct ext4_system_zone, node); | |
d74f3d25 | 145 | printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ", |
6fd058f7 TT |
146 | entry->start_blk, entry->start_blk + entry->count - 1); |
147 | first = 0; | |
148 | node = rb_next(node); | |
149 | } | |
69000d82 | 150 | rcu_read_unlock(); |
d74f3d25 | 151 | printk(KERN_CONT "\n"); |
6fd058f7 TT |
152 | } |
153 | ||
7727ae52 | 154 | /* |
155 | * Returns 1 if the passed-in block region (start_blk, | |
156 | * start_blk+count) is valid; 0 if some part of the block region | |
157 | * overlaps with filesystem metadata blocks. | |
158 | */ | |
159 | static int ext4_data_block_valid_rcu(struct ext4_sb_info *sbi, | |
160 | struct ext4_system_blocks *system_blks, | |
161 | ext4_fsblk_t start_blk, | |
162 | unsigned int count) | |
163 | { | |
164 | struct ext4_system_zone *entry; | |
165 | struct rb_node *n; | |
166 | ||
167 | if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || | |
168 | (start_blk + count < start_blk) || | |
169 | (start_blk + count > ext4_blocks_count(sbi->s_es))) { | |
170 | sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); | |
171 | return 0; | |
172 | } | |
173 | ||
174 | if (system_blks == NULL) | |
175 | return 1; | |
176 | ||
177 | n = system_blks->root.rb_node; | |
178 | while (n) { | |
179 | entry = rb_entry(n, struct ext4_system_zone, node); | |
180 | if (start_blk + count - 1 < entry->start_blk) | |
181 | n = n->rb_left; | |
182 | else if (start_blk >= (entry->start_blk + entry->count)) | |
183 | n = n->rb_right; | |
184 | else { | |
185 | sbi->s_es->s_last_error_block = cpu_to_le64(start_blk); | |
186 | return 0; | |
187 | } | |
188 | } | |
189 | return 1; | |
190 | } | |
191 | ||
192 | static int ext4_protect_reserved_inode(struct super_block *sb, | |
193 | struct ext4_system_blocks *system_blks, | |
194 | u32 ino) | |
345c0dbf TT |
195 | { |
196 | struct inode *inode; | |
197 | struct ext4_sb_info *sbi = EXT4_SB(sb); | |
198 | struct ext4_map_blocks map; | |
fbbbbd2f CIK |
199 | u32 i = 0, num; |
200 | int err = 0, n; | |
345c0dbf TT |
201 | |
202 | if ((ino < EXT4_ROOT_INO) || | |
203 | (ino > le32_to_cpu(sbi->s_es->s_inodes_count))) | |
204 | return -EINVAL; | |
205 | inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL); | |
206 | if (IS_ERR(inode)) | |
207 | return PTR_ERR(inode); | |
208 | num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; | |
209 | while (i < num) { | |
af133ade | 210 | cond_resched(); |
345c0dbf TT |
211 | map.m_lblk = i; |
212 | map.m_len = num - i; | |
213 | n = ext4_map_blocks(NULL, inode, &map, 0); | |
214 | if (n < 0) { | |
215 | err = n; | |
216 | break; | |
217 | } | |
218 | if (n == 0) { | |
219 | i++; | |
220 | } else { | |
7727ae52 | 221 | if (!ext4_data_block_valid_rcu(sbi, system_blks, |
222 | map.m_pblk, n)) { | |
345c0dbf TT |
223 | ext4_error(sb, "blocks %llu-%llu from inode %u " |
224 | "overlap system zone", map.m_pblk, | |
225 | map.m_pblk + map.m_len - 1, ino); | |
226 | err = -EFSCORRUPTED; | |
227 | break; | |
228 | } | |
7727ae52 | 229 | err = add_system_zone(system_blks, map.m_pblk, n); |
345c0dbf TT |
230 | if (err < 0) |
231 | break; | |
232 | i += n; | |
233 | } | |
234 | } | |
235 | iput(inode); | |
236 | return err; | |
237 | } | |
238 | ||
7727ae52 | 239 | static void ext4_destroy_system_zone(struct rcu_head *rcu) |
240 | { | |
241 | struct ext4_system_blocks *system_blks; | |
242 | ||
243 | system_blks = container_of(rcu, struct ext4_system_blocks, rcu); | |
244 | release_system_zone(system_blks); | |
245 | kfree(system_blks); | |
246 | } | |
247 | ||
248 | /* | |
249 | * Build system zone rbtree which is used for block validity checking. | |
250 | * | |
251 | * The update of system_blks pointer in this function is protected by | |
252 | * sb->s_umount semaphore. However we have to be careful as we can be | |
253 | * racing with ext4_data_block_valid() calls reading system_blks rbtree | |
254 | * protected only by RCU. That's why we first build the rbtree and then | |
255 | * swap it in place. | |
256 | */ | |
6fd058f7 TT |
257 | int ext4_setup_system_zone(struct super_block *sb) |
258 | { | |
259 | ext4_group_t ngroups = ext4_get_groups_count(sb); | |
260 | struct ext4_sb_info *sbi = EXT4_SB(sb); | |
7727ae52 | 261 | struct ext4_system_blocks *system_blks; |
6fd058f7 TT |
262 | struct ext4_group_desc *gdp; |
263 | ext4_group_t i; | |
264 | int flex_size = ext4_flex_bg_size(sbi); | |
265 | int ret; | |
266 | ||
267 | if (!test_opt(sb, BLOCK_VALIDITY)) { | |
7727ae52 | 268 | if (sbi->system_blks) |
6fd058f7 TT |
269 | ext4_release_system_zone(sb); |
270 | return 0; | |
271 | } | |
7727ae52 | 272 | if (sbi->system_blks) |
6fd058f7 TT |
273 | return 0; |
274 | ||
7727ae52 | 275 | system_blks = kzalloc(sizeof(*system_blks), GFP_KERNEL); |
276 | if (!system_blks) | |
277 | return -ENOMEM; | |
278 | ||
6fd058f7 | 279 | for (i=0; i < ngroups; i++) { |
4b99faa2 | 280 | cond_resched(); |
6fd058f7 TT |
281 | if (ext4_bg_has_super(sb, i) && |
282 | ((i < 5) || ((i % flex_size) == 0))) | |
7727ae52 | 283 | add_system_zone(system_blks, |
284 | ext4_group_first_block_no(sb, i), | |
1032988c | 285 | ext4_bg_num_gdb(sb, i) + 1); |
6fd058f7 | 286 | gdp = ext4_get_group_desc(sb, i, NULL); |
7727ae52 | 287 | ret = add_system_zone(system_blks, |
288 | ext4_block_bitmap(sb, gdp), 1); | |
6fd058f7 | 289 | if (ret) |
7727ae52 | 290 | goto err; |
291 | ret = add_system_zone(system_blks, | |
292 | ext4_inode_bitmap(sb, gdp), 1); | |
6fd058f7 | 293 | if (ret) |
7727ae52 | 294 | goto err; |
295 | ret = add_system_zone(system_blks, | |
296 | ext4_inode_table(sb, gdp), | |
6fd058f7 TT |
297 | sbi->s_itb_per_group); |
298 | if (ret) | |
7727ae52 | 299 | goto err; |
6fd058f7 | 300 | } |
345c0dbf | 301 | if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) { |
7727ae52 | 302 | ret = ext4_protect_reserved_inode(sb, system_blks, |
345c0dbf TT |
303 | le32_to_cpu(sbi->s_es->s_journal_inum)); |
304 | if (ret) | |
7727ae52 | 305 | goto err; |
345c0dbf | 306 | } |
6fd058f7 | 307 | |
7727ae52 | 308 | /* |
309 | * System blks rbtree complete, announce it once to prevent racing | |
310 | * with ext4_data_block_valid() accessing the rbtree at the same | |
311 | * time. | |
312 | */ | |
313 | rcu_assign_pointer(sbi->system_blks, system_blks); | |
314 | ||
6fd058f7 | 315 | if (test_opt(sb, DEBUG)) |
49598e04 | 316 | debug_print_tree(sbi); |
6fd058f7 | 317 | return 0; |
7727ae52 | 318 | err: |
319 | release_system_zone(system_blks); | |
320 | kfree(system_blks); | |
321 | return ret; | |
6fd058f7 TT |
322 | } |
323 | ||
7727ae52 | 324 | /* |
325 | * Called when the filesystem is unmounted or when remounting it with | |
326 | * noblock_validity specified. | |
327 | * | |
328 | * The update of system_blks pointer in this function is protected by | |
329 | * sb->s_umount semaphore. However we have to be careful as we can be | |
330 | * racing with ext4_data_block_valid() calls reading system_blks rbtree | |
331 | * protected only by RCU. So we first clear the system_blks pointer and | |
332 | * then free the rbtree only after RCU grace period expires. | |
333 | */ | |
6fd058f7 TT |
334 | void ext4_release_system_zone(struct super_block *sb) |
335 | { | |
7727ae52 | 336 | struct ext4_system_blocks *system_blks; |
d1866bd0 | 337 | |
7727ae52 | 338 | system_blks = rcu_dereference_protected(EXT4_SB(sb)->system_blks, |
339 | lockdep_is_held(&sb->s_umount)); | |
340 | rcu_assign_pointer(EXT4_SB(sb)->system_blks, NULL); | |
d1866bd0 | 341 | |
7727ae52 | 342 | if (system_blks) |
343 | call_rcu(&system_blks->rcu, ext4_destroy_system_zone); | |
6fd058f7 TT |
344 | } |
345 | ||
6fd058f7 TT |
346 | int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk, |
347 | unsigned int count) | |
348 | { | |
7727ae52 | 349 | struct ext4_system_blocks *system_blks; |
350 | int ret; | |
6fd058f7 | 351 | |
7727ae52 | 352 | /* |
353 | * Lock the system zone to prevent it being released concurrently | |
354 | * when doing a remount which inverse current "[no]block_validity" | |
355 | * mount option. | |
356 | */ | |
357 | rcu_read_lock(); | |
358 | system_blks = rcu_dereference(sbi->system_blks); | |
359 | ret = ext4_data_block_valid_rcu(sbi, system_blks, start_blk, | |
360 | count); | |
361 | rcu_read_unlock(); | |
362 | return ret; | |
6fd058f7 TT |
363 | } |
364 | ||
1f7d1e77 TT |
365 | int ext4_check_blockref(const char *function, unsigned int line, |
366 | struct inode *inode, __le32 *p, unsigned int max) | |
367 | { | |
368 | struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; | |
369 | __le32 *bref = p; | |
370 | unsigned int blk; | |
371 | ||
170417c8 TT |
372 | if (ext4_has_feature_journal(inode->i_sb) && |
373 | (inode->i_ino == | |
374 | le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum))) | |
375 | return 0; | |
376 | ||
1f7d1e77 TT |
377 | while (bref < p+max) { |
378 | blk = le32_to_cpu(*bref++); | |
379 | if (blk && | |
380 | unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb), | |
381 | blk, 1))) { | |
382 | es->s_last_error_block = cpu_to_le64(blk); | |
383 | ext4_error_inode(inode, function, line, blk, | |
384 | "invalid block"); | |
6a797d27 | 385 | return -EFSCORRUPTED; |
1f7d1e77 TT |
386 | } |
387 | } | |
388 | return 0; | |
389 | } | |
dae1e52c | 390 |