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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; | |
ce9f24cc | 27 | u32 ino; |
6fd058f7 TT |
28 | }; |
29 | ||
30 | static struct kmem_cache *ext4_system_zone_cachep; | |
31 | ||
5dabfc78 | 32 | int __init ext4_init_system_zone(void) |
6fd058f7 | 33 | { |
16828088 | 34 | ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0); |
6fd058f7 TT |
35 | if (ext4_system_zone_cachep == NULL) |
36 | return -ENOMEM; | |
37 | return 0; | |
38 | } | |
39 | ||
5dabfc78 | 40 | void ext4_exit_system_zone(void) |
6fd058f7 | 41 | { |
7727ae52 | 42 | rcu_barrier(); |
6fd058f7 TT |
43 | kmem_cache_destroy(ext4_system_zone_cachep); |
44 | } | |
45 | ||
46 | static inline int can_merge(struct ext4_system_zone *entry1, | |
47 | struct ext4_system_zone *entry2) | |
48 | { | |
ce9f24cc JK |
49 | if ((entry1->start_blk + entry1->count) == entry2->start_blk && |
50 | entry1->ino == entry2->ino) | |
6fd058f7 TT |
51 | return 1; |
52 | return 0; | |
53 | } | |
54 | ||
7727ae52 | 55 | static void release_system_zone(struct ext4_system_blocks *system_blks) |
56 | { | |
57 | struct ext4_system_zone *entry, *n; | |
58 | ||
59 | rbtree_postorder_for_each_entry_safe(entry, n, | |
60 | &system_blks->root, node) | |
61 | kmem_cache_free(ext4_system_zone_cachep, entry); | |
62 | } | |
63 | ||
6fd058f7 TT |
64 | /* |
65 | * Mark a range of blocks as belonging to the "system zone" --- that | |
66 | * is, filesystem metadata blocks which should never be used by | |
67 | * inodes. | |
68 | */ | |
7727ae52 | 69 | static int add_system_zone(struct ext4_system_blocks *system_blks, |
6fd058f7 | 70 | ext4_fsblk_t start_blk, |
ce9f24cc | 71 | unsigned int count, u32 ino) |
6fd058f7 | 72 | { |
bf9a379d | 73 | struct ext4_system_zone *new_entry, *entry; |
7727ae52 | 74 | struct rb_node **n = &system_blks->root.rb_node, *node; |
6fd058f7 TT |
75 | struct rb_node *parent = NULL, *new_node = NULL; |
76 | ||
77 | while (*n) { | |
78 | parent = *n; | |
79 | entry = rb_entry(parent, struct ext4_system_zone, node); | |
80 | if (start_blk < entry->start_blk) | |
81 | n = &(*n)->rb_left; | |
82 | else if (start_blk >= (entry->start_blk + entry->count)) | |
83 | n = &(*n)->rb_right; | |
bf9a379d JK |
84 | else /* Unexpected overlap of system zones. */ |
85 | return -EFSCORRUPTED; | |
6fd058f7 TT |
86 | } |
87 | ||
bf9a379d JK |
88 | new_entry = kmem_cache_alloc(ext4_system_zone_cachep, |
89 | GFP_KERNEL); | |
90 | if (!new_entry) | |
91 | return -ENOMEM; | |
92 | new_entry->start_blk = start_blk; | |
93 | new_entry->count = count; | |
ce9f24cc | 94 | new_entry->ino = ino; |
bf9a379d | 95 | new_node = &new_entry->node; |
6fd058f7 | 96 | |
bf9a379d JK |
97 | rb_link_node(new_node, parent, n); |
98 | rb_insert_color(new_node, &system_blks->root); | |
6fd058f7 TT |
99 | |
100 | /* Can we merge to the left? */ | |
101 | node = rb_prev(new_node); | |
102 | if (node) { | |
103 | entry = rb_entry(node, struct ext4_system_zone, node); | |
104 | if (can_merge(entry, new_entry)) { | |
105 | new_entry->start_blk = entry->start_blk; | |
106 | new_entry->count += entry->count; | |
7727ae52 | 107 | rb_erase(node, &system_blks->root); |
6fd058f7 TT |
108 | kmem_cache_free(ext4_system_zone_cachep, entry); |
109 | } | |
110 | } | |
111 | ||
112 | /* Can we merge to the right? */ | |
113 | node = rb_next(new_node); | |
114 | if (node) { | |
115 | entry = rb_entry(node, struct ext4_system_zone, node); | |
116 | if (can_merge(new_entry, entry)) { | |
117 | new_entry->count += entry->count; | |
7727ae52 | 118 | rb_erase(node, &system_blks->root); |
6fd058f7 TT |
119 | kmem_cache_free(ext4_system_zone_cachep, entry); |
120 | } | |
121 | } | |
122 | return 0; | |
123 | } | |
124 | ||
125 | static void debug_print_tree(struct ext4_sb_info *sbi) | |
126 | { | |
127 | struct rb_node *node; | |
128 | struct ext4_system_zone *entry; | |
69000d82 | 129 | struct ext4_system_blocks *system_blks; |
6fd058f7 TT |
130 | int first = 1; |
131 | ||
132 | printk(KERN_INFO "System zones: "); | |
69000d82 | 133 | rcu_read_lock(); |
dd0db94f | 134 | system_blks = rcu_dereference(sbi->s_system_blks); |
69000d82 | 135 | node = rb_first(&system_blks->root); |
6fd058f7 TT |
136 | while (node) { |
137 | entry = rb_entry(node, struct ext4_system_zone, node); | |
d74f3d25 | 138 | printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ", |
6fd058f7 TT |
139 | entry->start_blk, entry->start_blk + entry->count - 1); |
140 | first = 0; | |
141 | node = rb_next(node); | |
142 | } | |
69000d82 | 143 | rcu_read_unlock(); |
d74f3d25 | 144 | printk(KERN_CONT "\n"); |
6fd058f7 TT |
145 | } |
146 | ||
7727ae52 | 147 | static int ext4_protect_reserved_inode(struct super_block *sb, |
148 | struct ext4_system_blocks *system_blks, | |
149 | u32 ino) | |
345c0dbf TT |
150 | { |
151 | struct inode *inode; | |
152 | struct ext4_sb_info *sbi = EXT4_SB(sb); | |
153 | struct ext4_map_blocks map; | |
fbbbbd2f CIK |
154 | u32 i = 0, num; |
155 | int err = 0, n; | |
345c0dbf TT |
156 | |
157 | if ((ino < EXT4_ROOT_INO) || | |
158 | (ino > le32_to_cpu(sbi->s_es->s_inodes_count))) | |
159 | return -EINVAL; | |
160 | inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL); | |
161 | if (IS_ERR(inode)) | |
162 | return PTR_ERR(inode); | |
163 | num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; | |
164 | while (i < num) { | |
af133ade | 165 | cond_resched(); |
345c0dbf TT |
166 | map.m_lblk = i; |
167 | map.m_len = num - i; | |
168 | n = ext4_map_blocks(NULL, inode, &map, 0); | |
169 | if (n < 0) { | |
170 | err = n; | |
171 | break; | |
172 | } | |
173 | if (n == 0) { | |
174 | i++; | |
175 | } else { | |
ce9f24cc JK |
176 | err = add_system_zone(system_blks, map.m_pblk, n, ino); |
177 | if (err < 0) { | |
178 | if (err == -EFSCORRUPTED) { | |
93c20bc3 JK |
179 | EXT4_ERROR_INODE_ERR(inode, -err, |
180 | "blocks %llu-%llu from inode overlap system zone", | |
181 | map.m_pblk, | |
182 | map.m_pblk + map.m_len - 1); | |
ce9f24cc | 183 | } |
345c0dbf TT |
184 | break; |
185 | } | |
345c0dbf TT |
186 | i += n; |
187 | } | |
188 | } | |
189 | iput(inode); | |
190 | return err; | |
191 | } | |
192 | ||
7727ae52 | 193 | static void ext4_destroy_system_zone(struct rcu_head *rcu) |
194 | { | |
195 | struct ext4_system_blocks *system_blks; | |
196 | ||
197 | system_blks = container_of(rcu, struct ext4_system_blocks, rcu); | |
198 | release_system_zone(system_blks); | |
199 | kfree(system_blks); | |
200 | } | |
201 | ||
202 | /* | |
203 | * Build system zone rbtree which is used for block validity checking. | |
204 | * | |
205 | * The update of system_blks pointer in this function is protected by | |
206 | * sb->s_umount semaphore. However we have to be careful as we can be | |
8041ac64 | 207 | * racing with ext4_inode_block_valid() calls reading system_blks rbtree |
7727ae52 | 208 | * protected only by RCU. That's why we first build the rbtree and then |
209 | * swap it in place. | |
210 | */ | |
6fd058f7 TT |
211 | int ext4_setup_system_zone(struct super_block *sb) |
212 | { | |
213 | ext4_group_t ngroups = ext4_get_groups_count(sb); | |
214 | struct ext4_sb_info *sbi = EXT4_SB(sb); | |
7727ae52 | 215 | struct ext4_system_blocks *system_blks; |
6fd058f7 TT |
216 | struct ext4_group_desc *gdp; |
217 | ext4_group_t i; | |
218 | int flex_size = ext4_flex_bg_size(sbi); | |
219 | int ret; | |
220 | ||
7727ae52 | 221 | system_blks = kzalloc(sizeof(*system_blks), GFP_KERNEL); |
222 | if (!system_blks) | |
223 | return -ENOMEM; | |
224 | ||
6fd058f7 | 225 | for (i=0; i < ngroups; i++) { |
4b99faa2 | 226 | cond_resched(); |
6fd058f7 | 227 | if (ext4_bg_has_super(sb, i) && |
e7bfb5c9 JK |
228 | ((i < 5) || ((i % flex_size) == 0))) { |
229 | ret = add_system_zone(system_blks, | |
7727ae52 | 230 | ext4_group_first_block_no(sb, i), |
ce9f24cc | 231 | ext4_bg_num_gdb(sb, i) + 1, 0); |
e7bfb5c9 JK |
232 | if (ret) |
233 | goto err; | |
234 | } | |
6fd058f7 | 235 | gdp = ext4_get_group_desc(sb, i, NULL); |
7727ae52 | 236 | ret = add_system_zone(system_blks, |
ce9f24cc | 237 | ext4_block_bitmap(sb, gdp), 1, 0); |
6fd058f7 | 238 | if (ret) |
7727ae52 | 239 | goto err; |
240 | ret = add_system_zone(system_blks, | |
ce9f24cc | 241 | ext4_inode_bitmap(sb, gdp), 1, 0); |
6fd058f7 | 242 | if (ret) |
7727ae52 | 243 | goto err; |
244 | ret = add_system_zone(system_blks, | |
245 | ext4_inode_table(sb, gdp), | |
ce9f24cc | 246 | sbi->s_itb_per_group, 0); |
6fd058f7 | 247 | if (ret) |
7727ae52 | 248 | goto err; |
6fd058f7 | 249 | } |
345c0dbf | 250 | if (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) { |
7727ae52 | 251 | ret = ext4_protect_reserved_inode(sb, system_blks, |
345c0dbf TT |
252 | le32_to_cpu(sbi->s_es->s_journal_inum)); |
253 | if (ret) | |
7727ae52 | 254 | goto err; |
345c0dbf | 255 | } |
6fd058f7 | 256 | |
7727ae52 | 257 | /* |
258 | * System blks rbtree complete, announce it once to prevent racing | |
8041ac64 | 259 | * with ext4_inode_block_valid() accessing the rbtree at the same |
7727ae52 | 260 | * time. |
261 | */ | |
dd0db94f | 262 | rcu_assign_pointer(sbi->s_system_blks, system_blks); |
7727ae52 | 263 | |
6fd058f7 | 264 | if (test_opt(sb, DEBUG)) |
49598e04 | 265 | debug_print_tree(sbi); |
6fd058f7 | 266 | return 0; |
7727ae52 | 267 | err: |
268 | release_system_zone(system_blks); | |
269 | kfree(system_blks); | |
270 | return ret; | |
6fd058f7 TT |
271 | } |
272 | ||
7727ae52 | 273 | /* |
274 | * Called when the filesystem is unmounted or when remounting it with | |
275 | * noblock_validity specified. | |
276 | * | |
277 | * The update of system_blks pointer in this function is protected by | |
278 | * sb->s_umount semaphore. However we have to be careful as we can be | |
8041ac64 | 279 | * racing with ext4_inode_block_valid() calls reading system_blks rbtree |
7727ae52 | 280 | * protected only by RCU. So we first clear the system_blks pointer and |
281 | * then free the rbtree only after RCU grace period expires. | |
282 | */ | |
6fd058f7 TT |
283 | void ext4_release_system_zone(struct super_block *sb) |
284 | { | |
7727ae52 | 285 | struct ext4_system_blocks *system_blks; |
d1866bd0 | 286 | |
dd0db94f | 287 | system_blks = rcu_dereference_protected(EXT4_SB(sb)->s_system_blks, |
7727ae52 | 288 | lockdep_is_held(&sb->s_umount)); |
dd0db94f | 289 | rcu_assign_pointer(EXT4_SB(sb)->s_system_blks, NULL); |
d1866bd0 | 290 | |
7727ae52 | 291 | if (system_blks) |
292 | call_rcu(&system_blks->rcu, ext4_destroy_system_zone); | |
6fd058f7 TT |
293 | } |
294 | ||
3f67e7cf JK |
295 | /* |
296 | * Returns 1 if the passed-in block region (start_blk, | |
297 | * start_blk+count) is valid; 0 if some part of the block region | |
298 | * overlaps with some other filesystem metadata blocks. | |
299 | */ | |
ce9f24cc | 300 | int ext4_inode_block_valid(struct inode *inode, ext4_fsblk_t start_blk, |
6fd058f7 TT |
301 | unsigned int count) |
302 | { | |
3f67e7cf | 303 | struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); |
7727ae52 | 304 | struct ext4_system_blocks *system_blks; |
3f67e7cf JK |
305 | struct ext4_system_zone *entry; |
306 | struct rb_node *n; | |
307 | int ret = 1; | |
308 | ||
309 | if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || | |
310 | (start_blk + count < start_blk) || | |
311 | (start_blk + count > ext4_blocks_count(sbi->s_es))) | |
312 | return 0; | |
6fd058f7 | 313 | |
7727ae52 | 314 | /* |
315 | * Lock the system zone to prevent it being released concurrently | |
316 | * when doing a remount which inverse current "[no]block_validity" | |
317 | * mount option. | |
318 | */ | |
319 | rcu_read_lock(); | |
dd0db94f | 320 | system_blks = rcu_dereference(sbi->s_system_blks); |
3f67e7cf JK |
321 | if (system_blks == NULL) |
322 | goto out_rcu; | |
323 | ||
324 | n = system_blks->root.rb_node; | |
325 | while (n) { | |
326 | entry = rb_entry(n, struct ext4_system_zone, node); | |
327 | if (start_blk + count - 1 < entry->start_blk) | |
328 | n = n->rb_left; | |
329 | else if (start_blk >= (entry->start_blk + entry->count)) | |
330 | n = n->rb_right; | |
331 | else { | |
332 | ret = (entry->ino == inode->i_ino); | |
333 | break; | |
334 | } | |
335 | } | |
336 | out_rcu: | |
7727ae52 | 337 | rcu_read_unlock(); |
338 | return ret; | |
6fd058f7 TT |
339 | } |
340 | ||
1f7d1e77 TT |
341 | int ext4_check_blockref(const char *function, unsigned int line, |
342 | struct inode *inode, __le32 *p, unsigned int max) | |
343 | { | |
1f7d1e77 TT |
344 | __le32 *bref = p; |
345 | unsigned int blk; | |
346 | ||
170417c8 TT |
347 | if (ext4_has_feature_journal(inode->i_sb) && |
348 | (inode->i_ino == | |
349 | le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum))) | |
350 | return 0; | |
351 | ||
1f7d1e77 TT |
352 | while (bref < p+max) { |
353 | blk = le32_to_cpu(*bref++); | |
354 | if (blk && | |
ce9f24cc | 355 | unlikely(!ext4_inode_block_valid(inode, blk, 1))) { |
1f7d1e77 TT |
356 | ext4_error_inode(inode, function, line, blk, |
357 | "invalid block"); | |
6a797d27 | 358 | return -EFSCORRUPTED; |
1f7d1e77 TT |
359 | } |
360 | } | |
361 | return 0; | |
362 | } | |
dae1e52c | 363 |