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Theodore Ts'o6fd058f2009-05-17 15:38:01 -04001/*
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>
Theodore Ts'o6fd058f2009-05-17 15:38:01 -040019#include <linux/blkdev.h>
20#include <linux/mutex.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090021#include <linux/slab.h>
Theodore Ts'o6fd058f2009-05-17 15:38:01 -040022#include "ext4.h"
23
24struct ext4_system_zone {
25 struct rb_node node;
26 ext4_fsblk_t start_blk;
27 unsigned int count;
28};
29
30static struct kmem_cache *ext4_system_zone_cachep;
31
32int __init init_ext4_system_zone(void)
33{
34 ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone,
35 SLAB_RECLAIM_ACCOUNT);
36 if (ext4_system_zone_cachep == NULL)
37 return -ENOMEM;
38 return 0;
39}
40
41void exit_ext4_system_zone(void)
42{
43 kmem_cache_destroy(ext4_system_zone_cachep);
44}
45
46static inline int can_merge(struct ext4_system_zone *entry1,
47 struct ext4_system_zone *entry2)
48{
49 if ((entry1->start_blk + entry1->count) == entry2->start_blk)
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 */
59static int add_system_zone(struct ext4_sb_info *sbi,
60 ext4_fsblk_t start_blk,
61 unsigned int count)
62{
63 struct ext4_system_zone *new_entry = NULL, *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 {
Theodore Ts'o60e66792010-05-17 07:00:00 -040075 if (start_blk + count > (entry->start_blk +
Theodore Ts'o6fd058f2009-05-17 15:38:01 -040076 entry->count))
Theodore Ts'o60e66792010-05-17 07:00:00 -040077 entry->count = (start_blk + count -
Theodore Ts'o6fd058f2009-05-17 15:38:01 -040078 entry->start_blk);
79 new_node = *n;
80 new_entry = rb_entry(new_node, struct ext4_system_zone,
81 node);
82 break;
83 }
84 }
85
86 if (!new_entry) {
87 new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
88 GFP_KERNEL);
89 if (!new_entry)
90 return -ENOMEM;
91 new_entry->start_blk = start_blk;
92 new_entry->count = count;
93 new_node = &new_entry->node;
94
95 rb_link_node(new_node, parent, n);
96 rb_insert_color(new_node, &sbi->system_blks);
97 }
98
99 /* Can we merge to the left? */
100 node = rb_prev(new_node);
101 if (node) {
102 entry = rb_entry(node, struct ext4_system_zone, node);
103 if (can_merge(entry, new_entry)) {
104 new_entry->start_blk = entry->start_blk;
105 new_entry->count += entry->count;
106 rb_erase(node, &sbi->system_blks);
107 kmem_cache_free(ext4_system_zone_cachep, entry);
108 }
109 }
110
111 /* Can we merge to the right? */
112 node = rb_next(new_node);
113 if (node) {
114 entry = rb_entry(node, struct ext4_system_zone, node);
115 if (can_merge(new_entry, entry)) {
116 new_entry->count += entry->count;
117 rb_erase(node, &sbi->system_blks);
118 kmem_cache_free(ext4_system_zone_cachep, entry);
119 }
120 }
121 return 0;
122}
123
124static void debug_print_tree(struct ext4_sb_info *sbi)
125{
126 struct rb_node *node;
127 struct ext4_system_zone *entry;
128 int first = 1;
129
130 printk(KERN_INFO "System zones: ");
131 node = rb_first(&sbi->system_blks);
132 while (node) {
133 entry = rb_entry(node, struct ext4_system_zone, node);
134 printk("%s%llu-%llu", first ? "" : ", ",
135 entry->start_blk, entry->start_blk + entry->count - 1);
136 first = 0;
137 node = rb_next(node);
138 }
139 printk("\n");
140}
141
142int ext4_setup_system_zone(struct super_block *sb)
143{
144 ext4_group_t ngroups = ext4_get_groups_count(sb);
145 struct ext4_sb_info *sbi = EXT4_SB(sb);
146 struct ext4_group_desc *gdp;
147 ext4_group_t i;
148 int flex_size = ext4_flex_bg_size(sbi);
149 int ret;
150
151 if (!test_opt(sb, BLOCK_VALIDITY)) {
152 if (EXT4_SB(sb)->system_blks.rb_node)
153 ext4_release_system_zone(sb);
154 return 0;
155 }
156 if (EXT4_SB(sb)->system_blks.rb_node)
157 return 0;
158
159 for (i=0; i < ngroups; i++) {
160 if (ext4_bg_has_super(sb, i) &&
161 ((i < 5) || ((i % flex_size) == 0)))
162 add_system_zone(sbi, ext4_group_first_block_no(sb, i),
Theodore Ts'o10329882009-11-15 15:29:56 -0500163 ext4_bg_num_gdb(sb, i) + 1);
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400164 gdp = ext4_get_group_desc(sb, i, NULL);
165 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
166 if (ret)
167 return ret;
168 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
169 if (ret)
170 return ret;
171 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
172 sbi->s_itb_per_group);
173 if (ret)
174 return ret;
175 }
176
177 if (test_opt(sb, DEBUG))
178 debug_print_tree(EXT4_SB(sb));
179 return 0;
180}
181
182/* Called when the filesystem is unmounted */
183void ext4_release_system_zone(struct super_block *sb)
184{
185 struct rb_node *n = EXT4_SB(sb)->system_blks.rb_node;
186 struct rb_node *parent;
187 struct ext4_system_zone *entry;
188
189 while (n) {
190 /* Do the node's children first */
191 if (n->rb_left) {
192 n = n->rb_left;
193 continue;
194 }
195 if (n->rb_right) {
196 n = n->rb_right;
197 continue;
198 }
199 /*
200 * The node has no children; free it, and then zero
201 * out parent's link to it. Finally go to the
202 * beginning of the loop and try to free the parent
203 * node.
204 */
205 parent = rb_parent(n);
206 entry = rb_entry(n, struct ext4_system_zone, node);
207 kmem_cache_free(ext4_system_zone_cachep, entry);
208 if (!parent)
Venkatesh Pallipadi64e290e2010-03-04 22:25:21 -0500209 EXT4_SB(sb)->system_blks = RB_ROOT;
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400210 else if (parent->rb_left == n)
211 parent->rb_left = NULL;
212 else if (parent->rb_right == n)
213 parent->rb_right = NULL;
214 n = parent;
215 }
Venkatesh Pallipadi64e290e2010-03-04 22:25:21 -0500216 EXT4_SB(sb)->system_blks = RB_ROOT;
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400217}
218
219/*
220 * Returns 1 if the passed-in block region (start_blk,
221 * start_blk+count) is valid; 0 if some part of the block region
222 * overlaps with filesystem metadata blocks.
223 */
224int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
225 unsigned int count)
226{
227 struct ext4_system_zone *entry;
228 struct rb_node *n = sbi->system_blks.rb_node;
229
230 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
Theodore Ts'o1585d8d2009-11-22 20:48:34 -0500231 (start_blk + count < start_blk) ||
Theodore Ts'o1c13d5c2010-07-27 11:56:03 -0400232 (start_blk + count > ext4_blocks_count(sbi->s_es))) {
233 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400234 return 0;
Theodore Ts'o1c13d5c2010-07-27 11:56:03 -0400235 }
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400236 while (n) {
237 entry = rb_entry(n, struct ext4_system_zone, node);
238 if (start_blk + count - 1 < entry->start_blk)
239 n = n->rb_left;
240 else if (start_blk >= (entry->start_blk + entry->count))
241 n = n->rb_right;
Theodore Ts'o1c13d5c2010-07-27 11:56:03 -0400242 else {
243 sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400244 return 0;
Theodore Ts'o1c13d5c2010-07-27 11:56:03 -0400245 }
Theodore Ts'o6fd058f2009-05-17 15:38:01 -0400246 }
247 return 1;
248}
249