original development tree for Linux kernel GTP module; now long in mainline.
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/*
* linux/fs/ext4/block_validity.c
*
* Copyright (C) 2009
* Theodore Ts'o (tytso@mit.edu)
*
* Track which blocks in the filesystem are metadata blocks that
* should never be used as data blocks by files or directories.
*/
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/blkdev.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include "ext4.h"
struct ext4_system_zone {
struct rb_node node;
ext4_fsblk_t start_blk;
unsigned int count;
};
static struct kmem_cache *ext4_system_zone_cachep;
int __init ext4_init_system_zone(void)
{
ext4_system_zone_cachep = KMEM_CACHE(ext4_system_zone, 0);
if (ext4_system_zone_cachep == NULL)
return -ENOMEM;
return 0;
}
void ext4_exit_system_zone(void)
{
kmem_cache_destroy(ext4_system_zone_cachep);
}
static inline int can_merge(struct ext4_system_zone *entry1,
struct ext4_system_zone *entry2)
{
if ((entry1->start_blk + entry1->count) == entry2->start_blk)
return 1;
return 0;
}
/*
* Mark a range of blocks as belonging to the "system zone" --- that
* is, filesystem metadata blocks which should never be used by
* inodes.
*/
static int add_system_zone(struct ext4_sb_info *sbi,
ext4_fsblk_t start_blk,
unsigned int count)
{
struct ext4_system_zone *new_entry = NULL, *entry;
struct rb_node **n = &sbi->system_blks.rb_node, *node;
struct rb_node *parent = NULL, *new_node = NULL;
while (*n) {
parent = *n;
entry = rb_entry(parent, struct ext4_system_zone, node);
if (start_blk < entry->start_blk)
n = &(*n)->rb_left;
else if (start_blk >= (entry->start_blk + entry->count))
n = &(*n)->rb_right;
else {
if (start_blk + count > (entry->start_blk +
entry->count))
entry->count = (start_blk + count -
entry->start_blk);
new_node = *n;
new_entry = rb_entry(new_node, struct ext4_system_zone,
node);
break;
}
}
if (!new_entry) {
new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
GFP_KERNEL);
if (!new_entry)
return -ENOMEM;
new_entry->start_blk = start_blk;
new_entry->count = count;
new_node = &new_entry->node;
rb_link_node(new_node, parent, n);
rb_insert_color(new_node, &sbi->system_blks);
}
/* Can we merge to the left? */
node = rb_prev(new_node);
if (node) {
entry = rb_entry(node, struct ext4_system_zone, node);
if (can_merge(entry, new_entry)) {
new_entry->start_blk = entry->start_blk;
new_entry->count += entry->count;
rb_erase(node, &sbi->system_blks);
kmem_cache_free(ext4_system_zone_cachep, entry);
}
}
/* Can we merge to the right? */
node = rb_next(new_node);
if (node) {
entry = rb_entry(node, struct ext4_system_zone, node);
if (can_merge(new_entry, entry)) {
new_entry->count += entry->count;
rb_erase(node, &sbi->system_blks);
kmem_cache_free(ext4_system_zone_cachep, entry);
}
}
return 0;
}
static void debug_print_tree(struct ext4_sb_info *sbi)
{
struct rb_node *node;
struct ext4_system_zone *entry;
int first = 1;
printk(KERN_INFO "System zones: ");
node = rb_first(&sbi->system_blks);
while (node) {
entry = rb_entry(node, struct ext4_system_zone, node);
printk("%s%llu-%llu", first ? "" : ", ",
entry->start_blk, entry->start_blk + entry->count - 1);
first = 0;
node = rb_next(node);
}
printk("\n");
}
int ext4_setup_system_zone(struct super_block *sb)
{
ext4_group_t ngroups = ext4_get_groups_count(sb);
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_group_desc *gdp;
ext4_group_t i;
int flex_size = ext4_flex_bg_size(sbi);
int ret;
if (!test_opt(sb, BLOCK_VALIDITY)) {
if (EXT4_SB(sb)->system_blks.rb_node)
ext4_release_system_zone(sb);
return 0;
}
if (EXT4_SB(sb)->system_blks.rb_node)
return 0;
for (i=0; i < ngroups; i++) {
if (ext4_bg_has_super(sb, i) &&
((i < 5) || ((i % flex_size) == 0)))
add_system_zone(sbi, ext4_group_first_block_no(sb, i),
ext4_bg_num_gdb(sb, i) + 1);
gdp = ext4_get_group_desc(sb, i, NULL);
ret = add_system_zone(sbi, ext4_block_bitmap(sb, gdp), 1);
if (ret)
return ret;
ret = add_system_zone(sbi, ext4_inode_bitmap(sb, gdp), 1);
if (ret)
return ret;
ret = add_system_zone(sbi, ext4_inode_table(sb, gdp),
sbi->s_itb_per_group);
if (ret)
return ret;
}
if (test_opt(sb, DEBUG))
debug_print_tree(EXT4_SB(sb));
return 0;
}
/* Called when the filesystem is unmounted */
void ext4_release_system_zone(struct super_block *sb)
{
struct rb_node *n = EXT4_SB(sb)->system_blks.rb_node;
struct rb_node *parent;
struct ext4_system_zone *entry;
while (n) {
/* Do the node's children first */
if (n->rb_left) {
n = n->rb_left;
continue;
}
if (n->rb_right) {
n = n->rb_right;
continue;
}
/*
* The node has no children; free it, and then zero
* out parent's link to it. Finally go to the
* beginning of the loop and try to free the parent
* node.
*/
parent = rb_parent(n);
entry = rb_entry(n, struct ext4_system_zone, node);
kmem_cache_free(ext4_system_zone_cachep, entry);
if (!parent)
EXT4_SB(sb)->system_blks = RB_ROOT;
else if (parent->rb_left == n)
parent->rb_left = NULL;
else if (parent->rb_right == n)
parent->rb_right = NULL;
n = parent;
}
EXT4_SB(sb)->system_blks = RB_ROOT;
}
/*
* Returns 1 if the passed-in block region (start_blk,
* start_blk+count) is valid; 0 if some part of the block region
* overlaps with filesystem metadata blocks.
*/
int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
unsigned int count)
{
struct ext4_system_zone *entry;
struct rb_node *n = sbi->system_blks.rb_node;
if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
(start_blk + count < start_blk) ||
(start_blk + count > ext4_blocks_count(sbi->s_es))) {
sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
return 0;
}
while (n) {
entry = rb_entry(n, struct ext4_system_zone, node);
if (start_blk + count - 1 < entry->start_blk)
n = n->rb_left;
else if (start_blk >= (entry->start_blk + entry->count))
n = n->rb_right;
else {
sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
return 0;
}
}
return 1;
}
int ext4_check_blockref(const char *function, unsigned int line,
struct inode *inode, __le32 *p, unsigned int max)
{
struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
__le32 *bref = p;
unsigned int blk;
while (bref < p+max) {
blk = le32_to_cpu(*bref++);
if (blk &&
unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
blk, 1))) {
es->s_last_error_block = cpu_to_le64(blk);
ext4_error_inode(inode, function, line, blk,
"invalid block");
return -EIO;
}
}
return 0;
}