2 * linux/fs/ext4/block_validity.c
5 * Theodore Ts'o (tytso@mit.edu)
7 * Track which blocks in the filesystem are metadata blocks that
8 * should never be used as data blocks by files or directories.
11 #include <linux/time.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>
24 struct ext4_system_zone {
26 ext4_fsblk_t start_blk;
30 static struct kmem_cache *ext4_system_zone_cachep;
32 int __init init_ext4_system_zone(void)
34 ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone,
35 SLAB_RECLAIM_ACCOUNT);
36 if (ext4_system_zone_cachep == NULL)
41 void exit_ext4_system_zone(void)
43 kmem_cache_destroy(ext4_system_zone_cachep);
46 static inline int can_merge(struct ext4_system_zone *entry1,
47 struct ext4_system_zone *entry2)
49 if ((entry1->start_blk + entry1->count) == entry2->start_blk)
55 * Mark a range of blocks as belonging to the "system zone" --- that
56 * is, filesystem metadata blocks which should never be used by
59 static int add_system_zone(struct ext4_sb_info *sbi,
60 ext4_fsblk_t start_blk,
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;
69 entry = rb_entry(parent, struct ext4_system_zone, node);
70 if (start_blk < entry->start_blk)
72 else if (start_blk >= (entry->start_blk + entry->count))
75 if (start_blk + count > (entry->start_blk +
77 entry->count = (start_blk + count -
80 new_entry = rb_entry(new_node, struct ext4_system_zone,
87 new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
91 new_entry->start_blk = start_blk;
92 new_entry->count = count;
93 new_node = &new_entry->node;
95 rb_link_node(new_node, parent, n);
96 rb_insert_color(new_node, &sbi->system_blks);
99 /* Can we merge to the left? */
100 node = rb_prev(new_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);
111 /* Can we merge to the right? */
112 node = rb_next(new_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);
124 static void debug_print_tree(struct ext4_sb_info *sbi)
126 struct rb_node *node;
127 struct ext4_system_zone *entry;
130 printk(KERN_INFO "System zones: ");
131 node = rb_first(&sbi->system_blks);
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);
137 node = rb_next(node);
142 int ext4_setup_system_zone(struct super_block *sb)
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;
148 int flex_size = ext4_flex_bg_size(sbi);
151 if (!test_opt(sb, BLOCK_VALIDITY)) {
152 if (EXT4_SB(sb)->system_blks.rb_node)
153 ext4_release_system_zone(sb);
156 if (EXT4_SB(sb)->system_blks.rb_node)
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),
163 ext4_bg_num_gdb(sb, i) + 1);
164 gdp = ext4_get_group_desc(sb, i, NULL);
165 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
168 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
171 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
172 sbi->s_itb_per_group);
177 if (test_opt(sb, DEBUG))
178 debug_print_tree(EXT4_SB(sb));
182 /* Called when the filesystem is unmounted */
183 void ext4_release_system_zone(struct super_block *sb)
185 struct rb_node *n = EXT4_SB(sb)->system_blks.rb_node;
186 struct rb_node *parent;
187 struct ext4_system_zone *entry;
190 /* Do the node's children first */
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
205 parent = rb_parent(n);
206 entry = rb_entry(n, struct ext4_system_zone, node);
207 kmem_cache_free(ext4_system_zone_cachep, entry);
209 EXT4_SB(sb)->system_blks = RB_ROOT;
210 else if (parent->rb_left == n)
211 parent->rb_left = NULL;
212 else if (parent->rb_right == n)
213 parent->rb_right = NULL;
216 EXT4_SB(sb)->system_blks = RB_ROOT;
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.
224 int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
227 struct ext4_system_zone *entry;
228 struct rb_node *n = sbi->system_blks.rb_node;
230 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
231 (start_blk + count < start_blk) ||
232 (start_blk + count > ext4_blocks_count(sbi->s_es)))
235 entry = rb_entry(n, struct ext4_system_zone, node);
236 if (start_blk + count - 1 < entry->start_blk)
238 else if (start_blk >= (entry->start_blk + entry->count))