Merge branch 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied...
[sfrench/cifs-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 <linux/slab.h>
22 #include "ext4.h"
23
24 struct ext4_system_zone {
25         struct rb_node  node;
26         ext4_fsblk_t    start_blk;
27         unsigned int    count;
28 };
29
30 static struct kmem_cache *ext4_system_zone_cachep;
31
32 int __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
41 void exit_ext4_system_zone(void)
42 {
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 {
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  */
59 static 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 {
75                         if (start_blk + count > (entry->start_blk + 
76                                                  entry->count))
77                                 entry->count = (start_blk + count - 
78                                                 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
124 static 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
142 int 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),
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);
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 */
183 void 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)
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;
214                 n = parent;
215         }
216         EXT4_SB(sb)->system_blks = RB_ROOT;
217 }
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  */
224 int 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)) ||
231             (start_blk + count < start_blk) ||
232             (start_blk + count > ext4_blocks_count(sbi->s_es)))
233                 return 0;
234         while (n) {
235                 entry = rb_entry(n, struct ext4_system_zone, node);
236                 if (start_blk + count - 1 < entry->start_blk)
237                         n = n->rb_left;
238                 else if (start_blk >= (entry->start_blk + entry->count))
239                         n = n->rb_right;
240                 else
241                         return 0;
242         }
243         return 1;
244 }
245