ext4: fix up rb_root initializations to use RB_ROOT
[linux-2.6.git] / fs / ext4 / block_validity.c
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/module.h>
17 #include <linux/swap.h>
18 #include <linux/pagemap.h>
19 #include <linux/blkdev.h>
20 #include <linux/mutex.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
31 int __init init_ext4_system_zone(void)
32 {
33         ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone,
34                                              SLAB_RECLAIM_ACCOUNT);
35         if (ext4_system_zone_cachep == NULL)
36                 return -ENOMEM;
37         return 0;
38 }
39
40 void exit_ext4_system_zone(void)
41 {
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
53 /*
54  * Mark a range of blocks as belonging to the "system zone" --- that
55  * is, filesystem metadata blocks which should never be used by
56  * inodes.
57  */
58 static int add_system_zone(struct ext4_sb_info *sbi,
59                            ext4_fsblk_t start_blk,
60                            unsigned int count)
61 {
62         struct ext4_system_zone *new_entry = NULL, *entry;
63         struct rb_node **n = &sbi->system_blks.rb_node, *node;
64         struct rb_node *parent = NULL, *new_node = NULL;
65
66         while (*n) {
67                 parent = *n;
68                 entry = rb_entry(parent, struct ext4_system_zone, node);
69                 if (start_blk < entry->start_blk)
70                         n = &(*n)->rb_left;
71                 else if (start_blk >= (entry->start_blk + entry->count))
72                         n = &(*n)->rb_right;
73                 else {
74                         if (start_blk + count > (entry->start_blk + 
75                                                  entry->count))
76                                 entry->count = (start_blk + count - 
77                                                 entry->start_blk);
78                         new_node = *n;
79                         new_entry = rb_entry(new_node, struct ext4_system_zone,
80                                              node);
81                         break;
82                 }
83         }
84
85         if (!new_entry) {
86                 new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
87                                              GFP_KERNEL);
88                 if (!new_entry)
89                         return -ENOMEM;
90                 new_entry->start_blk = start_blk;
91                 new_entry->count = count;
92                 new_node = &new_entry->node;
93
94                 rb_link_node(new_node, parent, n);
95                 rb_insert_color(new_node, &sbi->system_blks);
96         }
97
98         /* Can we merge to the left? */
99         node = rb_prev(new_node);
100         if (node) {
101                 entry = rb_entry(node, struct ext4_system_zone, node);
102                 if (can_merge(entry, new_entry)) {
103                         new_entry->start_blk = entry->start_blk;
104                         new_entry->count += entry->count;
105                         rb_erase(node, &sbi->system_blks);
106                         kmem_cache_free(ext4_system_zone_cachep, entry);
107                 }
108         }
109
110         /* Can we merge to the right? */
111         node = rb_next(new_node);
112         if (node) {
113                 entry = rb_entry(node, struct ext4_system_zone, node);
114                 if (can_merge(new_entry, entry)) {
115                         new_entry->count += entry->count;
116                         rb_erase(node, &sbi->system_blks);
117                         kmem_cache_free(ext4_system_zone_cachep, entry);
118                 }
119         }
120         return 0;
121 }
122
123 static void debug_print_tree(struct ext4_sb_info *sbi)
124 {
125         struct rb_node *node;
126         struct ext4_system_zone *entry;
127         int first = 1;
128
129         printk(KERN_INFO "System zones: ");
130         node = rb_first(&sbi->system_blks);
131         while (node) {
132                 entry = rb_entry(node, struct ext4_system_zone, node);
133                 printk("%s%llu-%llu", first ? "" : ", ",
134                        entry->start_blk, entry->start_blk + entry->count - 1);
135                 first = 0;
136                 node = rb_next(node);
137         }
138         printk("\n");
139 }
140
141 int ext4_setup_system_zone(struct super_block *sb)
142 {
143         ext4_group_t ngroups = ext4_get_groups_count(sb);
144         struct ext4_sb_info *sbi = EXT4_SB(sb);
145         struct ext4_group_desc *gdp;
146         ext4_group_t i;
147         int flex_size = ext4_flex_bg_size(sbi);
148         int ret;
149
150         if (!test_opt(sb, BLOCK_VALIDITY)) {
151                 if (EXT4_SB(sb)->system_blks.rb_node)
152                         ext4_release_system_zone(sb);
153                 return 0;
154         }
155         if (EXT4_SB(sb)->system_blks.rb_node)
156                 return 0;
157
158         for (i=0; i < ngroups; i++) {
159                 if (ext4_bg_has_super(sb, i) &&
160                     ((i < 5) || ((i % flex_size) == 0)))
161                         add_system_zone(sbi, ext4_group_first_block_no(sb, i),
162                                         ext4_bg_num_gdb(sb, i) + 1);
163                 gdp = ext4_get_group_desc(sb, i, NULL);
164                 ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
165                 if (ret)
166                         return ret;
167                 ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
168                 if (ret)
169                         return ret;
170                 ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
171                                 sbi->s_itb_per_group);
172                 if (ret)
173                         return ret;
174         }
175
176         if (test_opt(sb, DEBUG))
177                 debug_print_tree(EXT4_SB(sb));
178         return 0;
179 }
180
181 /* Called when the filesystem is unmounted */
182 void ext4_release_system_zone(struct super_block *sb)
183 {
184         struct rb_node  *n = EXT4_SB(sb)->system_blks.rb_node;
185         struct rb_node  *parent;
186         struct ext4_system_zone *entry;
187
188         while (n) {
189                 /* Do the node's children first */
190                 if (n->rb_left) {
191                         n = n->rb_left;
192                         continue;
193                 }
194                 if (n->rb_right) {
195                         n = n->rb_right;
196                         continue;
197                 }
198                 /*
199                  * The node has no children; free it, and then zero
200                  * out parent's link to it.  Finally go to the
201                  * beginning of the loop and try to free the parent
202                  * node.
203                  */
204                 parent = rb_parent(n);
205                 entry = rb_entry(n, struct ext4_system_zone, node);
206                 kmem_cache_free(ext4_system_zone_cachep, entry);
207                 if (!parent)
208                         EXT4_SB(sb)->system_blks = RB_ROOT;
209                 else if (parent->rb_left == n)
210                         parent->rb_left = NULL;
211                 else if (parent->rb_right == n)
212                         parent->rb_right = NULL;
213                 n = parent;
214         }
215         EXT4_SB(sb)->system_blks = RB_ROOT;
216 }
217
218 /*
219  * Returns 1 if the passed-in block region (start_blk,
220  * start_blk+count) is valid; 0 if some part of the block region
221  * overlaps with filesystem metadata blocks.
222  */
223 int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
224                           unsigned int count)
225 {
226         struct ext4_system_zone *entry;
227         struct rb_node *n = sbi->system_blks.rb_node;
228
229         if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
230             (start_blk + count < start_blk) ||
231             (start_blk + count > ext4_blocks_count(sbi->s_es)))
232                 return 0;
233         while (n) {
234                 entry = rb_entry(n, struct ext4_system_zone, node);
235                 if (start_blk + count - 1 < entry->start_blk)
236                         n = n->rb_left;
237                 else if (start_blk >= (entry->start_blk + entry->count))
238                         n = n->rb_right;
239                 else
240                         return 0;
241         }
242         return 1;
243 }
244