bitmap.c

阿基米德操作系统的源代码

///////////////////////////////////////////////////////////////////////////
#include "general.h"
#include "clear_block.h"
#include "set_clear_bit.h"
#include "find_first_zero.h"

#include "hd_info_struct.h"
#include "dir_entry.h"
#include "msdos_dir_entry.h"
#include "d_inode.h"
#include "m_inode.h"
#include "buffer_head.h"
#include "fat_cache.h"
#include "file.h"
#include "hd_request_struct.h"
#include "super_block.h"

#include "common_head.h"
///////////////////////////////////////////////////////////////////////////

void free_block(int dev, int block)
{
	struct super_block * sb;
	struct buffer_head * bh;

	
	if (dev >= nr_super_blocks)
		return;
	sb = &the_super_block[dev];
	if ((block < sb->s_firstdatazone) || (block >= sb->s_nzones))
		return;

	block -= sb->s_firstdatazone;
	if (!(bh = sb->s_zmap[block >> 13]))
		return;
	while (bh->b_lock);

	if (clear_bit(block & 8191,bh->b_data)) 
		return;
	bh->b_dirt = 1;
	return;
}

int new_block(int dev)
{
	struct super_block * sb;
	struct buffer_head * bh, * bh0;
	int    i,j,j0;


	if (dev >= nr_super_blocks)
		return 0;
	sb = &the_super_block[dev];

	j = 8192;
	for (i = 0 ; i<8 ; i++)
		if ((bh = sb->s_zmap[i]) != NULL){
			while (bh->b_lock);
			if ((j = find_first_zero(bh->b_data)) < 8192)
				break;
		}
	if ((j >= 8192) || ((j0 = sb->s_firstdatazone + i * 8192 + j) >= sb->s_nzones))
		return 0;
	if (!(bh0 = bread(dev,j0,0)))
		return 0;
	clear_block(bh0->b_data);
	bh0->b_dirt = 1;
	brelse(bh0);

	set_bit(j,bh->b_data);
	bh->b_dirt = 1;

	return j0;
}

void free_inode(struct m_inode * inode)
{
	struct super_block * sb;
	struct buffer_head * bh;

	if (!inode || (inode->i_dev >= nr_super_blocks))
		return;
	sb = &the_super_block[inode->i_dev];
	if ((inode->i_num < 1) || (inode->i_num > sb->s_ninodes))
		return;

	if (!(bh = sb->s_imap[inode->i_num >> 13]))
		return;
	while (bh->b_lock);
	if (clear_bit(inode->i_num & 8191,bh->b_data))
		return;
	bh->b_dirt = 1;
	memset(inode,0,sizeof(*inode));
	return;
}

struct m_inode * new_inode(int dev)
{
	struct super_block * sb;
	struct buffer_head * bh;
	struct m_inode     * inode;
	int    i,j;


	if (dev >= nr_super_blocks)
		return NULL;
	sb = &the_super_block[dev];
	if (!(inode = get_empty_inode()))
		return NULL;

	j = 8192;
	for (i = 0 ; i < 8 ; i++)
		if ((bh = sb->s_imap[i]) != NULL){
			while (bh->b_lock);
			if ((j = find_first_zero(bh->b_data)) < 8192)
				break;
		}
	if ((j >= 8192) || (i * 8192 + j > sb->s_ninodes)) {
		inode->i_count = 0;
		return NULL;
	}

	set_bit(j,bh->b_data);
	bh->b_dirt = 1;

	inode->i_nlinks = 1;
	inode->i_mtime  = file_datetime;	
	inode->i_dev    = dev;
	inode->i_num    = i * 8192 + j;
	inode->i_dirt   = 1;

	return inode;
}