inode.c

阿基米德操作系统的源代码

///////////////////////////////////////////////////
#include "general.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 sync_inodes(void)
{
	struct m_inode * inode;
	int i;

	for (i = 0, inode = inode_table; i < NR_INODE ; i++ , inode++) 
	{
		if (inode->i_dirt)
		{
			if (inode->i_dev)
				write_inode(inode);
			else
				msdos_write_inode(inode);
		}
	}
	return;
}

int _bmap(struct m_inode * inode,int block,int create)
{
	struct buffer_head * bh;
	unsigned long i;

	if ((block < 0) || (block >= 8 + 256 + 256 * 256))
		return 0;
	if (block < 8) {
		if (create && !inode->i_zone[block])
			if ((inode->i_zone[block] = new_block(inode->i_dev)) != 0){
				inode->i_mtime       = file_datetime;
				inode->i_dirt        = 1;
			}
		return inode->i_zone[block];
	}
	block -= 8;
	if (block < 256) {
		if (create && !inode->i_zone[8])
			if ((inode->i_zone[8] = new_block(inode->i_dev)) != 0){
				inode->i_mtime   = file_datetime;
				inode->i_dirt    = 1;
			}
		if (!inode->i_zone[8])
			return 0;
		if (!(bh = bread(inode->i_dev,inode->i_zone[8],0)))
			return 0;
		i = ((unsigned long *) (bh->b_data))[block];
		if (create && !i)
			if ((i = new_block(inode->i_dev)) != 0){
				((unsigned long *) (bh->b_data))[block] = i;
				bh->b_dirt		= 1;
				inode->i_mtime	= file_datetime;
				inode->i_dirt	= 1;
			}
		brelse(bh);
		return i;
	}
	block -= 256;
	if (create && !inode->i_zone[9])
		if ((inode->i_zone[9] = new_block(inode->i_dev)) != 0){
			inode->i_mtime = file_datetime;
			inode->i_dirt  = 1;
		}
	if (!inode->i_zone[9])
		return 0;
	if (!(bh = bread(inode->i_dev,inode->i_zone[9],0)))
		return 0;
	i = ((unsigned long *)bh->b_data)[block >> 8];
	if (create && !i)
		if ((i = new_block(inode->i_dev)) != 0){
			((unsigned long *) (bh->b_data))[block >> 8] = i;
			bh->b_dirt		= 1;
			inode->i_mtime	= file_datetime;
			inode->i_dirt	= 1;
		}
	brelse(bh);
	if (!i)
		return 0;
	if (!(bh = bread(inode->i_dev,i,0)))
		return 0;
	i = ((unsigned long *)bh->b_data)[block & 255];
	if (create && !i)
		if ((i = new_block(inode->i_dev)) != 0){
			((unsigned long *) (bh->b_data))[block & 255] = i;
			bh->b_dirt		= 1;
			inode->i_mtime	= file_datetime;
			inode->i_dirt	= 1;
		}
	brelse(bh);
	return i;
}

int bmap(struct m_inode * inode,int block)
{
	return _bmap(inode,block,0);
}

int create_block(struct m_inode * inode, int block)
{
	return _bmap(inode,block,1);
}

struct m_inode * get_empty_inode(void)
{
	struct m_inode * inode;
	int    inr;

	inr   = last_allocated_inode;
	do {
		if (!inode_table[inr].i_count) {
			last_allocated_inode = inr;			
			inode = inode_table + inr;
			memset(inode,0,sizeof(*inode));
			inode->i_count = 1;
			return inode;
		}
		inr++;
		if (inr == NR_INODE)
			inr=0;
	} while (inr != last_allocated_inode);

	return NULL;
}
		
void iput(struct m_inode * inode)
{
	if (!inode || (!inode->i_count))
		return;
	inode->i_count--;
	if (inode->i_count)
		return;

	if (!inode->i_nlinks) {
		truncate(inode);
		free_inode(inode);
		return;
	}
	if (inode->i_dirt)
		write_inode(inode);	
	return;
}

struct m_inode * iget(int dev,int nr)
{
	struct m_inode * inode;

	inode = inode_table;
	while (inode < inode_table + NR_INODE) {
		if (inode->i_dev == dev && inode->i_num == nr) {
			inode->i_count++;
			return inode;
		}
		inode++;
	}
	inode = get_empty_inode();
	if (!inode)
		return NULL;
	inode->i_dev = dev;
	inode->i_num = nr;
	if (read_inode(inode))
		return inode;
	else
	{
		memset(inode,0,sizeof(*inode));
		return NULL;
	}
}

int read_inode(struct m_inode * inode)
{
	struct super_block * sb;
	struct buffer_head * bh;
	int    block;

	if (!inode || (inode->i_dev >= nr_super_blocks))
		return 0;
	sb = &the_super_block[inode->i_dev];

	block = 1 + sb->s_imap_blocks + sb->s_zmap_blocks + (inode->i_num - 1) / INODES_PER_BLOCK;
	bh = bread(inode->i_dev,block,0);
	if (bh){
		*(struct d_inode *)inode = ((struct d_inode *)bh->b_data)[(inode->i_num - 1) % INODES_PER_BLOCK];
		brelse(bh);
		inode->i_dirt = 0;
		return 1;
	}
	return 0;
}

int write_inode(struct m_inode * inode)
{
	struct super_block * sb;
	struct buffer_head * bh;
	int    block;

	if (!inode || (inode->i_dev >= nr_super_blocks))
		return 0;
	sb = &the_super_block[inode->i_dev];

	block = 1 + sb->s_imap_blocks + sb->s_zmap_blocks + (inode->i_num - 1) / INODES_PER_BLOCK;
	bh = bread(inode->i_dev,block,0);
	if (bh){
		((struct d_inode *)bh->b_data)[(inode->i_num - 1) % INODES_PER_BLOCK] = *(struct d_inode *)inode;
		bh->b_dirt    = 1;
		brelse(bh);
		inode->i_dirt = 0;
		return 1;
	}
	return 0;
}