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/swap.h>
17 #include <linux/pagemap.h>
18 #include <linux/blkdev.h>
19 #include <linux/mutex.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 };
28
29 static struct kmem_cache *ext4_system_zone_cachep;
30
ext4_init_system_zone(void)31 int __init ext4_init_system_zone(void)
32 {
33 ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0);
34 if (ext4_system_zone_cachep == NULL)
35 return -ENOMEM;
36 return 0;
37 }
38
ext4_exit_system_zone(void)39 void ext4_exit_system_zone(void)
40 {
41 kmem_cache_destroy(ext4_system_zone_cachep);
42 }
43
can_merge(struct ext4_system_zone * entry1,struct ext4_system_zone * entry2)44 static inline int can_merge(struct ext4_system_zone *entry1,
45 struct ext4_system_zone *entry2)
46 {
47 if ((entry1->start_blk + entry1->count) == entry2->start_blk)
48 return 1;
49 return 0;
50 }
51
52 /*
53 * Mark a range of blocks as belonging to the "system zone" --- that
54 * is, filesystem metadata blocks which should never be used by
55 * inodes.
56 */
add_system_zone(struct ext4_sb_info * sbi,ext4_fsblk_t start_blk,unsigned int count)57 static int add_system_zone(struct ext4_sb_info *sbi,
58 ext4_fsblk_t start_blk,
59 unsigned int count)
60 {
61 struct ext4_system_zone *new_entry = NULL, *entry;
62 struct rb_node **n = &sbi->system_blks.rb_node, *node;
63 struct rb_node *parent = NULL, *new_node = NULL;
64
65 while (*n) {
66 parent = *n;
67 entry = rb_entry(parent, struct ext4_system_zone, node);
68 if (start_blk < entry->start_blk)
69 n = &(*n)->rb_left;
70 else if (start_blk >= (entry->start_blk + entry->count))
71 n = &(*n)->rb_right;
72 else {
73 if (start_blk + count > (entry->start_blk +
74 entry->count))
75 entry->count = (start_blk + count -
76 entry->start_blk);
77 new_node = *n;
78 new_entry = rb_entry(new_node, struct ext4_system_zone,
79 node);
80 break;
81 }
82 }
83
84 if (!new_entry) {
85 new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
86 GFP_KERNEL);
87 if (!new_entry)
88 return -ENOMEM;
89 new_entry->start_blk = start_blk;
90 new_entry->count = count;
91 new_node = &new_entry->node;
92
93 rb_link_node(new_node, parent, n);
94 rb_insert_color(new_node, &sbi->system_blks);
95 }
96
97 /* Can we merge to the left? */
98 node = rb_prev(new_node);
99 if (node) {
100 entry = rb_entry(node, struct ext4_system_zone, node);
101 if (can_merge(entry, new_entry)) {
102 new_entry->start_blk = entry->start_blk;
103 new_entry->count += entry->count;
104 rb_erase(node, &sbi->system_blks);
105 kmem_cache_free(ext4_system_zone_cachep, entry);
106 }
107 }
108
109 /* Can we merge to the right? */
110 node = rb_next(new_node);
111 if (node) {
112 entry = rb_entry(node, struct ext4_system_zone, node);
113 if (can_merge(new_entry, entry)) {
114 new_entry->count += entry->count;
115 rb_erase(node, &sbi->system_blks);
116 kmem_cache_free(ext4_system_zone_cachep, entry);
117 }
118 }
119 return 0;
120 }
121
debug_print_tree(struct ext4_sb_info * sbi)122 static void debug_print_tree(struct ext4_sb_info *sbi)
123 {
124 struct rb_node *node;
125 struct ext4_system_zone *entry;
126 int first = 1;
127
128 printk(KERN_INFO "System zones: ");
129 node = rb_first(&sbi->system_blks);
130 while (node) {
131 entry = rb_entry(node, struct ext4_system_zone, node);
132 printk("%s%llu-%llu", first ? "" : ", ",
133 entry->start_blk, entry->start_blk + entry->count - 1);
134 first = 0;
135 node = rb_next(node);
136 }
137 printk("\n");
138 }
139
ext4_setup_system_zone(struct super_block * sb)140 int ext4_setup_system_zone(struct super_block *sb)
141 {
142 ext4_group_t ngroups = ext4_get_groups_count(sb);
143 struct ext4_sb_info *sbi = EXT4_SB(sb);
144 struct ext4_group_desc *gdp;
145 ext4_group_t i;
146 int flex_size = ext4_flex_bg_size(sbi);
147 int ret;
148
149 if (!test_opt(sb, BLOCK_VALIDITY)) {
150 if (EXT4_SB(sb)->system_blks.rb_node)
151 ext4_release_system_zone(sb);
152 return 0;
153 }
154 if (EXT4_SB(sb)->system_blks.rb_node)
155 return 0;
156
157 for (i=0; i < ngroups; i++) {
158 if (ext4_bg_has_super(sb, i) &&
159 ((i < 5) || ((i % flex_size) == 0)))
160 add_system_zone(sbi, ext4_group_first_block_no(sb, i),
161 ext4_bg_num_gdb(sb, i) + 1);
162 gdp = ext4_get_group_desc(sb, i, NULL);
163 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
164 if (ret)
165 return ret;
166 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
167 if (ret)
168 return ret;
169 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
170 sbi->s_itb_per_group);
171 if (ret)
172 return ret;
173 }
174
175 if (test_opt(sb, DEBUG))
176 debug_print_tree(EXT4_SB(sb));
177 return 0;
178 }
179
180 /* Called when the filesystem is unmounted */
ext4_release_system_zone(struct super_block * sb)181 void ext4_release_system_zone(struct super_block *sb)
182 {
183 struct ext4_system_zone *entry, *n;
184
185 rbtree_postorder_for_each_entry_safe(entry, n,
186 &EXT4_SB(sb)->system_blks, node)
187 kmem_cache_free(ext4_system_zone_cachep, entry);
188
189 EXT4_SB(sb)->system_blks = RB_ROOT;
190 }
191
192 /*
193 * Returns 1 if the passed-in block region (start_blk,
194 * start_blk+count) is valid; 0 if some part of the block region
195 * overlaps with filesystem metadata blocks.
196 */
ext4_data_block_valid(struct ext4_sb_info * sbi,ext4_fsblk_t start_blk,unsigned int count)197 int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
198 unsigned int count)
199 {
200 struct ext4_system_zone *entry;
201 struct rb_node *n = sbi->system_blks.rb_node;
202
203 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
204 (start_blk + count < start_blk) ||
205 (start_blk + count > ext4_blocks_count(sbi->s_es))) {
206 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
207 return 0;
208 }
209 while (n) {
210 entry = rb_entry(n, struct ext4_system_zone, node);
211 if (start_blk + count - 1 < entry->start_blk)
212 n = n->rb_left;
213 else if (start_blk >= (entry->start_blk + entry->count))
214 n = n->rb_right;
215 else {
216 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
217 return 0;
218 }
219 }
220 return 1;
221 }
222
ext4_check_blockref(const char * function,unsigned int line,struct inode * inode,__le32 * p,unsigned int max)223 int ext4_check_blockref(const char *function, unsigned int line,
224 struct inode *inode, __le32 *p, unsigned int max)
225 {
226 struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
227 __le32 *bref = p;
228 unsigned int blk;
229
230 while (bref < p+max) {
231 blk = le32_to_cpu(*bref++);
232 if (blk &&
233 unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
234 blk, 1))) {
235 es->s_last_error_block = cpu_to_le64(blk);
236 ext4_error_inode(inode, function, line, blk,
237 "invalid block");
238 return -EIO;
239 }
240 }
241 return 0;
242 }
243
244