file.c

elinux jffs初始版本 具体了解JFFS的文件系统！

		affs_brelse(bh);
		pt = T_LIST;
		if (ext < EXT_CACHE_SIZE - 1) {
			inode->u.affs_i.i_ext[ext] = key;
			inode->u.affs_i.i_max_ext  = ++ext;
		}
	}
	key = htonl(AFFS_BLOCK(bh->b_data,inode,block));
	affs_brelse(bh);
	if (!key)
		return NULL;
	*blk_key = key;

	return affs_bread(inode->i_dev,key,AFFS_I2BSIZE(inode));
}

/* This could be made static, regardless of what the former comment said.
 * You cannot directly read affs directories.
 */

static int
affs_file_read_ofs(struct inode *inode, struct file *filp, char *buf, int count)
{
	char *start;
	int left, offset, size, sector;
	int blocksize;
	struct buffer_head *bh;
	void *data;

	pr_debug("AFFS: file_read_ofs(ino=%lu,pos=%lu,%d)\n",inode->i_ino,(long)filp->f_pos,count);

	if (!inode) {
		printk("affs_file_read: inode = NULL\n");
		return -EINVAL;
	}
	blocksize = AFFS_I2BSIZE(inode) - 24;
	if (!(S_ISREG(inode->i_mode))) {
		pr_debug("affs_file_read: mode = %07o\n",inode->i_mode);
		return -EINVAL;
	}
	if (filp->f_pos >= inode->i_size || count <= 0)
		return 0;

	start = buf;
	for (;;) {
		left = MIN (inode->i_size - filp->f_pos,count - (buf - start));
		if (!left)
			break;
		sector = affs_bmap(inode,(__u32)filp->f_pos / blocksize);
		if (!sector)
			break;
		offset = (__u32)filp->f_pos % blocksize;
		bh = affs_bread(inode->i_dev,sector,AFFS_I2BSIZE(inode));
		if (!bh)
			break;
		data = bh->b_data + 24;
		size = MIN(blocksize - offset,left);
		filp->f_pos += size;
		memcpy_tofs(buf,data + offset,size);
		buf += size;
		affs_brelse(bh);
	}
	if (start == buf)
		return -EIO;
	return buf - start;
}

static int
affs_file_write(struct inode *inode, struct file *filp, const char *buf, int count)
{
	off_t			 pos;
	int			 written;
	int			 c;
	int			 blocksize;
	struct buffer_head	*bh;
	struct inode		*ino;
	char			*p;

	pr_debug("AFFS: file_write(ino=%lu,pos=%lu,count=%d)\n",inode->i_ino,
		(unsigned long)filp->f_pos,count);

	ino = NULL;
	if (!inode) {
		printk("AFFS: file_write(): inode=NULL\n");
		return -EINVAL;
	}
	if (inode->u.affs_i.i_original) {
		ino = iget(inode->i_sb,inode->u.affs_i.i_original);
		if (!ino) {
			printk("AFFS: could not follow link from inode %lu to %d\n",
			       inode->i_ino,inode->u.affs_i.i_original);
			return -EINVAL;
		}
		inode = ino;
	}
	if (!S_ISREG(inode->i_mode)) {
		printk("AFFS: file_write(): mode=%07o\n",inode->i_mode);
		iput(inode);
		return -EINVAL;
	}
	if (filp->f_flags & O_APPEND) {
		pos = inode->i_size;
	} else
		pos = filp->f_pos;
	written   = 0;
	blocksize = AFFS_I2BSIZE(inode);

	while (written < count) {
		bh = affs_getblock(inode,pos / blocksize);
		if (!bh) {
			if (!written)
				written = -ENOSPC;
			break;
		}
		c = blocksize - (pos % blocksize);
		if (c > count - written)
			c = count - written;
		if (c != blocksize && !buffer_uptodate(bh)) {
			ll_rw_block(READ,1,&bh);
			wait_on_buffer(bh);
			if (!buffer_uptodate(bh)) {
				affs_brelse(bh);
				if (!written)
					written = -EIO;
				break;
			}
		}
		p = (pos % blocksize) + bh->b_data;
		memcpy_fromfs(p,buf,c);
		update_vm_cache(inode,pos,p,c);
		mark_buffer_uptodate(bh,1);
		mark_buffer_dirty(bh,0);
		affs_brelse(bh);
		pos     += c;
		written += c;
		buf     += c;
	}
	if (pos > inode->i_size)
		inode->i_size = pos;
	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	filp->f_pos    = pos;
	inode->i_dirt  = 1;
	iput(ino);
	return written;
}

static int
affs_file_write_ofs(struct inode *inode, struct file *filp, const char *buf, int count)
{
	off_t			 pos;
	int			 written;
	int			 c;
	int			 key;
	int			 blocksize;
	struct buffer_head	*bh;
	struct inode		*ino;
	char			*p;

	pr_debug("AFFS: file_write_ofs(ino=%lu,pos=%lu,count=%d)\n",inode->i_ino,
		(unsigned long)filp->f_pos,count);

	if (!inode) {
		printk("AFFS: file_write_ofs(): inode=NULL\n");
		return -EINVAL;
	}
	ino = NULL;
	if (inode->u.affs_i.i_original) {
		ino = iget(inode->i_sb,inode->u.affs_i.i_original);
		if (!ino) {
			printk("AFFS: could not follow link from inode %lu to %d\n",
			       inode->i_ino,inode->u.affs_i.i_original);
			return -EINVAL;
		}
		inode = ino;
	}
	if (!S_ISREG(inode->i_mode)) {
		printk("AFFS: file_write_ofs(): mode=%07o\n",inode->i_mode);
		iput(inode);
		return -EINVAL;
	}
	if (filp->f_flags & O_APPEND)
		pos = inode->i_size;
	else
		pos = filp->f_pos;

	bh        = NULL;
	blocksize = AFFS_I2BSIZE(inode) - 24;
	written   = 0;
	while (written < count) {
		bh = affs_getblock_ofs(inode,pos / blocksize,&key);
		if (!bh) {
			if (!written)
				written = -ENOSPC;
			break;
		}
		c = blocksize - (pos % blocksize);
		if (c > count - written)
			c = count - written;
		if (c != blocksize && !buffer_uptodate(bh)) {
			ll_rw_block(READ,1,&bh);
			wait_on_buffer(bh);
			if (!buffer_uptodate(bh)) {
				affs_brelse(bh);
				if (!written)
					written = -EIO;
				break;
			}
		}
		p = (pos % blocksize) + bh->b_data + 24;
		memcpy_fromfs(p,buf,c);
		update_vm_cache(inode,pos,p,c);

		pos     += c;
		buf     += c;
		written += c;
		DATA_FRONT(bh)->data_size = ntohl(htonl(DATA_FRONT(bh)->data_size) + c);
		affs_fix_checksum(AFFS_I2BSIZE(inode),bh->b_data,5);
		mark_buffer_uptodate(bh,1);
		mark_buffer_dirty(bh,0);
		affs_brelse(bh);
	}
	if (pos > inode->i_size)
		inode->i_size = pos;
	filp->f_pos = pos;
	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	inode->i_dirt  = 1;
	iput(ino);
	return written;
}

void
affs_truncate(struct inode *inode)
{
	struct buffer_head	*bh;
	struct buffer_head	*ebh;
	struct inode		*ino;
	struct affs_zone	*zone;
	int	 first;
	int	 block;
	int	 key;
	int	*keyp;
	int	 ekey;
	int	 ptype, stype;
	int	 freethis;
	int	 blocksize;
	int	 rem;
	int	 ext;

	pr_debug("AFFS: file_truncate(inode=%ld,size=%lu)\n",inode->i_ino,inode->i_size);

	ino = NULL;
	if (inode->u.affs_i.i_original) {
		ino = iget(inode->i_sb,inode->u.affs_i.i_original);
		if (!ino) {
			printk("AFFS: truncate(): cannot follow link from %lu to %u\n",
			       inode->i_ino,inode->u.affs_i.i_original);
			return;
		}
		inode = ino;
	}
	blocksize = AFFS_I2BSIZE(inode) - ((inode->i_sb->u.affs_sb.s_flags & SF_OFS) ? 24 : 0);
	first = (inode->i_size + blocksize - 1) / blocksize;
	if (inode->u.affs_i.i_lastblock < first - 1) {
		if (inode->i_sb->u.affs_sb.s_flags & SF_OFS)
			bh = affs_getblock_ofs(inode,first - 1,&ekey);
		else
			bh = affs_getblock(inode,first - 1);

		while (inode->u.affs_i.i_pa_cnt) {		/* Free any preallocated blocks */
			affs_free_block(inode->i_sb,
					inode->u.affs_i.i_data[inode->u.affs_i.i_pa_next++]);
			inode->u.affs_i.i_pa_next &= MAX_PREALLOC - 1;
			inode->u.affs_i.i_pa_cnt--;
		}
		if (inode->u.affs_i.i_zone) {
			lock_super(inode->i_sb);
			zone = &inode->i_sb->u.affs_sb.s_zones[inode->u.affs_i.i_zone];
			if (zone->z_ino == inode->i_ino)
				zone->z_ino = 0;
			unlock_super(inode->i_sb);
		}
		if (!bh) {
			printk("AFFS: truncate(): Cannot extend file\n");
			inode->i_size = blocksize * (inode->u.affs_i.i_lastblock + 1);
		} else if (inode->i_sb->u.affs_sb.s_flags & SF_OFS) {
			rem = inode->i_size % blocksize;
			DATA_FRONT(bh)->data_size = ntohl(rem ? rem : blocksize);
			affs_fix_checksum(AFFS_I2BSIZE(inode),bh->b_data,5);
			mark_buffer_dirty(bh,0);
		}
		affs_brelse(bh);
		iput(ino);
		return;
	}
	ekey  = inode->i_ino;
	ext   = 0;

	while (ekey) {
		if (!(bh = affs_bread(inode->i_dev,ekey,AFFS_I2BSIZE(inode)))) {
			printk("AFFS: truncate(): Can't read block %d\n",ekey);
			break;
		}
		ptype = htonl(((struct file_front *)bh->b_data)->primary_type);
		stype = htonl(FILE_END(bh->b_data,inode)->secondary_type);
		if (ekey == inode->i_ino && ptype == T_SHORT && stype == ST_LINKFILE &&
		    LINK_END(bh->b_data,inode)->original == 0) {
			pr_debug("AFFS: truncate(): dumping link\n");
			affs_brelse(bh);
			break;
		}
		if (stype != ST_FILE || (ptype != T_SHORT && ptype != T_LIST)) {
			printk("AFFS: truncate(): bad block (ptype=%d, stype=%d)\n",
			        ptype,stype);
			affs_brelse(bh);
			break;
		}
		/* Do not throw away file header */
		freethis = first == 0 && ekey != inode->i_ino;
		for ( block = first; block < AFFS_I2HSIZE(inode); block++) {
			keyp = &AFFS_BLOCK(bh->b_data,inode,block);
			key  = htonl(*keyp);
			if (key) {
				*keyp = 0;
				affs_free_block(inode->i_sb,key);
			} else {
				block = AFFS_I2HSIZE(inode);
				break;
			}
		}
		keyp = &GET_END_PTR(struct file_end,bh->b_data,AFFS_I2BSIZE(inode))->extension;
		key  = htonl(*keyp);
		if (first <= AFFS_I2HSIZE(inode)) {
			((struct file_front *)bh->b_data)->block_count = htonl(first);
			first = 0;
			*keyp = 0;
			if ((inode->i_sb->u.affs_sb.s_flags & SF_OFS) && first > 0) {
				block = htonl(AFFS_BLOCK(bh->b_data,inode,first - 1));
				if ((ebh = affs_bread(inode->i_dev,block,AFFS_I2BSIZE(inode)))) {
					if(!(affs_checksum_block(AFFS_I2BSIZE(inode),ebh->b_data,
					     &ptype,NULL))) {
						rem = inode->i_size % blocksize;
						rem = ntohl(rem ? blocksize : rem);
						((struct data_front *)ebh->b_data)->data_size = rem;
						((struct data_front *)ebh->b_data)->next_data = 0;
						affs_fix_checksum(AFFS_I2BSIZE(inode),ebh->b_data,5);
						mark_buffer_dirty(ebh,1);
					}
					affs_brelse(ebh);
				}
			}
		} else {
			first -= AFFS_I2HSIZE(inode);
		}
		if (freethis) {		/* Don't bother fixing checksum */
			affs_brelse(bh);
			affs_free_block(inode->i_sb,ekey);
		} else {
			affs_fix_checksum(AFFS_I2BSIZE(inode),bh->b_data,5);
			mark_buffer_dirty(bh,1);
			affs_brelse(bh);
		}
		ekey = key;
	}
	inode->u.affs_i.i_lastblock = ((inode->i_size + blocksize - 1) / blocksize) - 1;
	inode->u.affs_i.i_max_ext   = 0;
	iput(ino);
}

static void
affs_release_file(struct inode *inode, struct file *filp)
{
	struct affs_zone	*zone;

	pr_debug("AFFS: release_file(ino=%lu)\n",inode->i_ino);

	if (filp->f_mode & 2) {		/* Free preallocated blocks */
		while (inode->u.affs_i.i_pa_cnt) {
			affs_free_block(inode->i_sb,
					inode->u.affs_i.i_data[inode->u.affs_i.i_pa_next++]);
			inode->u.affs_i.i_pa_next &= MAX_PREALLOC - 1;
			inode->u.affs_i.i_pa_cnt--;
		}
		if (inode->u.affs_i.i_zone) {
			lock_super(inode->i_sb);
			zone = &inode->i_sb->u.affs_sb.s_zones[inode->u.affs_i.i_zone];
			if (zone->z_ino == inode->i_ino)
				zone->z_ino = 0;
			unlock_super(inode->i_sb);
		}
	}
}