--- /dev/null
+/*
+ * 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/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 ext4_system_zone *entry, *n;
+
+ rbtree_postorder_for_each_entry_safe(entry, n,
+ &EXT4_SB(sb)->system_blks, node)
+ kmem_cache_free(ext4_system_zone_cachep, entry);
+
+ 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;
+}
+
Code Review / kvmfornfv.git / blobdiff