file system collection Code

#include "ext2.h"
#include "bitmap.h"
#include "cache.h"

extern struct ext2_fs fs;


/*
 * 修改bitmap, 保留块组(group) 里面的super block backup
 * group desc blocks backup, block bitmap, inode bitmap
 * inode table
 * 返回除去这些块以外改块组中的剩余块(空块)数目
 */
long reserve_super_and_bgd(long group)
{
	int i;
	long block;
	long cnt = 0;
	/* 保留启动块 */
	/*
	if(group == 0 && fs.super_i->s_es->s_first_data_block != 0)
	{
		_bitmap_block_used(group, 0);
		cnt++;
	}
	*/
	/* 保留超级块 */
	block = fs.super_i->s_es->s_first_data_block + group * fs.super_i->s_blocks_per_group;
	_bitmap_block_used(group, block);
	cnt++;
	/* 保留组描述符所使用的块 */
	block++;
	for(i = 0; i < fs.super_i->s_gdb_count; i++)
	{
		_bitmap_block_used(group, block + i);
	}
	cnt += i;
	/* 保留数据块位图所使用的(1)块 */
	block += i;
	_bitmap_block_used(group, block);
	cnt++;
	/* 保留inode位图所使用的(1)块 */
	block++;
	_bitmap_block_used(group, block);
	cnt++;
	/* 保留inode table所使用的块 */
	block++;
	for(i = 0; i < fs.super_i->s_itb_per_group; i++)
	{
		_bitmap_block_used(group, block + i);
	}
	cnt += i;
	if(group == fs.super_i->s_groups_count - 1)
	{
		//padding at the end of the last group block bitmap 
		long tmp;
		tmp = fs.super_i->s_es->s_blocks_count
			- fs.super_i->s_es->s_first_data_block
			- group * fs.super_i->s_blocks_per_group;
		block = fs.super_i->s_es->s_first_data_block + group * fs.super_i->s_blocks_per_group;
		for(i = 0; i < fs.super_i->s_blocks_per_group - tmp; i++)
		{
			_bitmap_block_used(group, block + i + tmp);
			cnt++;
		}
	}
	return fs.super_i->s_frags_per_group - cnt;
}

void _bitmap_block_used(long group, long block)
{
	unsigned char *buf;
	long block_in_group;
	read_group_block_bitmap(group, &buf);
	block_in_group = block - fs.super_i->s_es->s_first_data_block 
		- group * fs.super_i->s_blocks_per_group;
	buf[block_in_group / 8] |= (1 << (block_in_group % 8));
	write_group_block_bitmap(group, 0);

	//fs.group_desc_cache.cache.group_desc[group].bg_free_blocks_count--;
	//fs.super_i->s_es->s_free_blocks_count--;
}

void bitmap_block_used(long group, long block)
{
	unsigned char *buf;
	long block_in_group;
	read_group_block_bitmap(group, &buf);
	block_in_group = block - fs.super_i->s_es->s_first_data_block 
		- group * fs.super_i->s_blocks_per_group;
	buf[block_in_group / 8] |= (1 << (block_in_group % 8));
	write_group_block_bitmap(group, 0);

	fs.group_desc_cache.cache.group_desc[group].bg_free_blocks_count--;
	fs.super_i->s_es->s_free_blocks_count--;
}
	
void bitmap_block_unused(long group, long block)
{
	unsigned char *buf;
	long block_in_group;
	read_group_block_bitmap(group, &buf);
	block_in_group = block - fs.super_i->s_es->s_first_data_block 
		- group * fs.super_i->s_blocks_per_group;
	buf[block_in_group / 8] &= ~(1 << (block_in_group % 8));
	write_group_block_bitmap(group, 0);

	fs.group_desc_cache.cache.group_desc[group].bg_free_blocks_count++;
	fs.super_i->s_es->s_free_blocks_count++;
}

void bitmap_inode_used(long group, long inode)
{
	unsigned char *buf;
	long inode_in_group;
	read_group_inode_bitmap(group, &buf);
	inode_in_group = inode - group * fs.super_i->s_inodes_per_group - 1;
	buf[inode_in_group / 8] |= (1 << (inode_in_group % 8));
	write_group_inode_bitmap(group, 0);

	fs.group_desc_cache.cache.group_desc[group].bg_free_inodes_count--;
	fs.super_i->s_es->s_free_inodes_count--;
}
	
void bitmap_inode_unused(long group, long inode)
{
	unsigned char *buf;
	long inode_in_group;
	read_group_inode_bitmap(group, &buf);
	inode_in_group = inode - group * fs.super_i->s_inodes_per_group - 1;
	buf[inode_in_group / 8] &= ~(1 << (inode_in_group % 8));
	write_group_inode_bitmap(group, 0);

	fs.group_desc_cache.cache.group_desc[group].bg_free_inodes_count++;
	fs.super_i->s_es->s_free_inodes_count++;
}

int block_stat(long group, long block)
{
	unsigned char *buf;
	long block_in_group;
	read_group_block_bitmap(group, &buf);
	block_in_group = block - fs.super_i->s_es->s_first_data_block 
		- group * fs.super_i->s_blocks_per_group;
	return buf[block_in_group / 8] & (1 << (block_in_group % 8));
}