/* *  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;}