xref: /openbmc/linux/fs/ext4/block_validity.c (revision a2cce7a9)
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/slab.h>
20 #include "ext4.h"
21 
22 struct ext4_system_zone {
23 	struct rb_node	node;
24 	ext4_fsblk_t	start_blk;
25 	unsigned int	count;
26 };
27 
28 static struct kmem_cache *ext4_system_zone_cachep;
29 
30 int __init ext4_init_system_zone(void)
31 {
32 	ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0);
33 	if (ext4_system_zone_cachep == NULL)
34 		return -ENOMEM;
35 	return 0;
36 }
37 
38 void ext4_exit_system_zone(void)
39 {
40 	kmem_cache_destroy(ext4_system_zone_cachep);
41 }
42 
43 static inline int can_merge(struct ext4_system_zone *entry1,
44 		     struct ext4_system_zone *entry2)
45 {
46 	if ((entry1->start_blk + entry1->count) == entry2->start_blk)
47 		return 1;
48 	return 0;
49 }
50 
51 /*
52  * Mark a range of blocks as belonging to the "system zone" --- that
53  * is, filesystem metadata blocks which should never be used by
54  * inodes.
55  */
56 static int add_system_zone(struct ext4_sb_info *sbi,
57 			   ext4_fsblk_t start_blk,
58 			   unsigned int count)
59 {
60 	struct ext4_system_zone *new_entry = NULL, *entry;
61 	struct rb_node **n = &sbi->system_blks.rb_node, *node;
62 	struct rb_node *parent = NULL, *new_node = NULL;
63 
64 	while (*n) {
65 		parent = *n;
66 		entry = rb_entry(parent, struct ext4_system_zone, node);
67 		if (start_blk < entry->start_blk)
68 			n = &(*n)->rb_left;
69 		else if (start_blk >= (entry->start_blk + entry->count))
70 			n = &(*n)->rb_right;
71 		else {
72 			if (start_blk + count > (entry->start_blk +
73 						 entry->count))
74 				entry->count = (start_blk + count -
75 						entry->start_blk);
76 			new_node = *n;
77 			new_entry = rb_entry(new_node, struct ext4_system_zone,
78 					     node);
79 			break;
80 		}
81 	}
82 
83 	if (!new_entry) {
84 		new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
85 					     GFP_KERNEL);
86 		if (!new_entry)
87 			return -ENOMEM;
88 		new_entry->start_blk = start_blk;
89 		new_entry->count = count;
90 		new_node = &new_entry->node;
91 
92 		rb_link_node(new_node, parent, n);
93 		rb_insert_color(new_node, &sbi->system_blks);
94 	}
95 
96 	/* Can we merge to the left? */
97 	node = rb_prev(new_node);
98 	if (node) {
99 		entry = rb_entry(node, struct ext4_system_zone, node);
100 		if (can_merge(entry, new_entry)) {
101 			new_entry->start_blk = entry->start_blk;
102 			new_entry->count += entry->count;
103 			rb_erase(node, &sbi->system_blks);
104 			kmem_cache_free(ext4_system_zone_cachep, entry);
105 		}
106 	}
107 
108 	/* Can we merge to the right? */
109 	node = rb_next(new_node);
110 	if (node) {
111 		entry = rb_entry(node, struct ext4_system_zone, node);
112 		if (can_merge(new_entry, entry)) {
113 			new_entry->count += entry->count;
114 			rb_erase(node, &sbi->system_blks);
115 			kmem_cache_free(ext4_system_zone_cachep, entry);
116 		}
117 	}
118 	return 0;
119 }
120 
121 static void debug_print_tree(struct ext4_sb_info *sbi)
122 {
123 	struct rb_node *node;
124 	struct ext4_system_zone *entry;
125 	int first = 1;
126 
127 	printk(KERN_INFO "System zones: ");
128 	node = rb_first(&sbi->system_blks);
129 	while (node) {
130 		entry = rb_entry(node, struct ext4_system_zone, node);
131 		printk("%s%llu-%llu", first ? "" : ", ",
132 		       entry->start_blk, entry->start_blk + entry->count - 1);
133 		first = 0;
134 		node = rb_next(node);
135 	}
136 	printk("\n");
137 }
138 
139 int ext4_setup_system_zone(struct super_block *sb)
140 {
141 	ext4_group_t ngroups = ext4_get_groups_count(sb);
142 	struct ext4_sb_info *sbi = EXT4_SB(sb);
143 	struct ext4_group_desc *gdp;
144 	ext4_group_t i;
145 	int flex_size = ext4_flex_bg_size(sbi);
146 	int ret;
147 
148 	if (!test_opt(sb, BLOCK_VALIDITY)) {
149 		if (EXT4_SB(sb)->system_blks.rb_node)
150 			ext4_release_system_zone(sb);
151 		return 0;
152 	}
153 	if (EXT4_SB(sb)->system_blks.rb_node)
154 		return 0;
155 
156 	for (i=0; i < ngroups; i++) {
157 		if (ext4_bg_has_super(sb, i) &&
158 		    ((i < 5) || ((i % flex_size) == 0)))
159 			add_system_zone(sbi, ext4_group_first_block_no(sb, i),
160 					ext4_bg_num_gdb(sb, i) + 1);
161 		gdp = ext4_get_group_desc(sb, i, NULL);
162 		ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
163 		if (ret)
164 			return ret;
165 		ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
166 		if (ret)
167 			return ret;
168 		ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
169 				sbi->s_itb_per_group);
170 		if (ret)
171 			return ret;
172 	}
173 
174 	if (test_opt(sb, DEBUG))
175 		debug_print_tree(EXT4_SB(sb));
176 	return 0;
177 }
178 
179 /* Called when the filesystem is unmounted */
180 void ext4_release_system_zone(struct super_block *sb)
181 {
182 	struct ext4_system_zone	*entry, *n;
183 
184 	rbtree_postorder_for_each_entry_safe(entry, n,
185 			&EXT4_SB(sb)->system_blks, node)
186 		kmem_cache_free(ext4_system_zone_cachep, entry);
187 
188 	EXT4_SB(sb)->system_blks = RB_ROOT;
189 }
190 
191 /*
192  * Returns 1 if the passed-in block region (start_blk,
193  * start_blk+count) is valid; 0 if some part of the block region
194  * overlaps with filesystem metadata blocks.
195  */
196 int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
197 			  unsigned int count)
198 {
199 	struct ext4_system_zone *entry;
200 	struct rb_node *n = sbi->system_blks.rb_node;
201 
202 	if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
203 	    (start_blk + count < start_blk) ||
204 	    (start_blk + count > ext4_blocks_count(sbi->s_es))) {
205 		sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
206 		return 0;
207 	}
208 	while (n) {
209 		entry = rb_entry(n, struct ext4_system_zone, node);
210 		if (start_blk + count - 1 < entry->start_blk)
211 			n = n->rb_left;
212 		else if (start_blk >= (entry->start_blk + entry->count))
213 			n = n->rb_right;
214 		else {
215 			sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
216 			return 0;
217 		}
218 	}
219 	return 1;
220 }
221 
222 int ext4_check_blockref(const char *function, unsigned int line,
223 			struct inode *inode, __le32 *p, unsigned int max)
224 {
225 	struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
226 	__le32 *bref = p;
227 	unsigned int blk;
228 
229 	while (bref < p+max) {
230 		blk = le32_to_cpu(*bref++);
231 		if (blk &&
232 		    unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
233 						    blk, 1))) {
234 			es->s_last_error_block = cpu_to_le64(blk);
235 			ext4_error_inode(inode, function, line, blk,
236 					 "invalid block");
237 			return -EIO;
238 		}
239 	}
240 	return 0;
241 }
242 
243