fs/ext4/block_validity.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  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(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
 		       entry->start_blk, entry->start_blk + entry->count - 1);
 		first = 0;
 		node = rb_next(node);
 	}
 	printk(KERN_CONT "\n");
 }

 static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino)
 {
 	struct inode *inode;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_map_blocks map;
 	u32 i = 0, num;
 	int err = 0, n;

 	if ((ino < EXT4_ROOT_INO) ||
 	    (ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
 		return -EINVAL;
 	inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
 	if (IS_ERR(inode))
 		return PTR_ERR(inode);
 	num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 	while (i < num) {
 		map.m_lblk = i;
 		map.m_len = num - i;
 		n = ext4_map_blocks(NULL, inode, &map, 0);
 		if (n < 0) {
 			err = n;
 			break;
 		}
 		if (n == 0) {
 			i++;
 		} else {
 			if (!ext4_data_block_valid(sbi, map.m_pblk, n)) {
 				ext4_error(sb, "blocks %llu-%llu from inode %u "
 					   "overlap system zone", map.m_pblk,
 					   map.m_pblk + map.m_len - 1, ino);
 				err = -EFSCORRUPTED;
 				break;
 			}
 			err = add_system_zone(sbi, map.m_pblk, n);
 			if (err < 0)
 				break;
 			i += n;
 		}
 	}
 	iput(inode);
 	return err;
 }

 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 (sbi->system_blks.rb_node)
 			ext4_release_system_zone(sb);
 		return 0;
 	}
 	if (sbi->system_blks.rb_node)
 		return 0;

 	for (i=0; i < ngroups; i++) {
 		cond_resched();
 		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 (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) {
 		ret = ext4_protect_reserved_inode(sb,
 				le32_to_cpu(sbi->s_es->s_journal_inum));
 		if (ret)
 			return ret;
 	}

 	if (test_opt(sb, DEBUG))
 		debug_print_tree(sbi);
 	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;

 	if (ext4_has_feature_journal(inode->i_sb) &&
 	    (inode->i_ino ==
 	     le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
 		return 0;

 	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 -EFSCORRUPTED;
 		}
 	}
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 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(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
	entry->start_blk, entry->start_blk + entry->count - 1);
	first = 0;
	node = rb_next(node);
	}
	printk(KERN_CONT "\n");
	}

	static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino)
	{
	struct inode *inode;
	struct ext4_sb_info *sbi = EXT4_SB(sb);
	struct ext4_map_blocks map;
	u32 i = 0, num;
	int err = 0, n;

	if ((ino < EXT4_ROOT_INO) \|\|
	(ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
	return -EINVAL;
	inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
	if (IS_ERR(inode))
	return PTR_ERR(inode);
	num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
	while (i < num) {
	map.m_lblk = i;
	map.m_len = num - i;
	n = ext4_map_blocks(NULL, inode, &map, 0);
	if (n < 0) {
	err = n;
	break;
	}
	if (n == 0) {
	i++;
	} else {
	if (!ext4_data_block_valid(sbi, map.m_pblk, n)) {
	ext4_error(sb, "blocks %llu-%llu from inode %u "
	"overlap system zone", map.m_pblk,
	map.m_pblk + map.m_len - 1, ino);
	err = -EFSCORRUPTED;
	break;
	}
	err = add_system_zone(sbi, map.m_pblk, n);
	if (err < 0)
	break;
	i += n;
	}
	}
	iput(inode);
	return err;
	}

	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 (sbi->system_blks.rb_node)
	ext4_release_system_zone(sb);
	return 0;
	}
	if (sbi->system_blks.rb_node)
	return 0;

	for (i=0; i < ngroups; i++) {
	cond_resched();
	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 (ext4_has_feature_journal(sb) && sbi->s_es->s_journal_inum) {
	ret = ext4_protect_reserved_inode(sb,
	le32_to_cpu(sbi->s_es->s_journal_inum));
	if (ret)
	return ret;
	}

	if (test_opt(sb, DEBUG))
	debug_print_tree(sbi);
	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;

	if (ext4_has_feature_journal(inode->i_sb) &&
	(inode->i_ino ==
	le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
	return 0;

	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 -EFSCORRUPTED;
	}
	}
	return 0;
	}