inode.c

linux 内核源代码

		while (nextblk && (b_off >= (offset + sect_size))) {
			struct inode *ninode;

			offset += sect_size;
			ninode = isofs_iget(inode->i_sb, nextblk, nextoff);
			if (!ninode)
				goto abort;
			firstext  = ISOFS_I(ninode)->i_first_extent;
			sect_size = ISOFS_I(ninode)->i_section_size >> ISOFS_BUFFER_BITS(ninode);
			nextblk   = ISOFS_I(ninode)->i_next_section_block;
			nextoff   = ISOFS_I(ninode)->i_next_section_offset;
			iput(ninode);

			if (++section > 100) {
				printk(KERN_DEBUG "%s: More than 100 file sections ?!?"
					" aborting...\n", __func__);
				printk(KERN_DEBUG "%s: block=%ld firstext=%u sect_size=%u "
					"nextblk=%lu nextoff=%lu\n", __func__,
					iblock, firstext, (unsigned) sect_size,
					nextblk, nextoff);
				goto abort;
			}
		}

		if (*bh) {
			map_bh(*bh, inode->i_sb, firstext + b_off - offset);
		} else {
			*bh = sb_getblk(inode->i_sb, firstext+b_off-offset);
			if (!*bh)
				goto abort;
		}
		bh++;	/* Next buffer head */
		b_off++;	/* Next buffer offset */
		nblocks--;
		rv++;
	}

abort:
	unlock_kernel();
	return rv;
}

/*
 * Used by the standard interfaces.
 */
static int isofs_get_block(struct inode *inode, sector_t iblock,
		    struct buffer_head *bh_result, int create)
{
	if (create) {
		printk(KERN_DEBUG "%s: Kernel tries to allocate a block\n", __func__);
		return -EROFS;
	}

	return isofs_get_blocks(inode, iblock, &bh_result, 1) ? 0 : -EIO;
}

static int isofs_bmap(struct inode *inode, sector_t block)
{
	struct buffer_head dummy;
	int error;

	dummy.b_state = 0;
	dummy.b_blocknr = -1000;
	error = isofs_get_block(inode, block, &dummy, 0);
	if (!error)
		return dummy.b_blocknr;
	return 0;
}

struct buffer_head *isofs_bread(struct inode *inode, sector_t block)
{
	sector_t blknr = isofs_bmap(inode, block);
	if (!blknr)
		return NULL;
	return sb_bread(inode->i_sb, blknr);
}

static int isofs_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page,isofs_get_block);
}

static sector_t _isofs_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping,block,isofs_get_block);
}

static const struct address_space_operations isofs_aops = {
	.readpage = isofs_readpage,
	.sync_page = block_sync_page,
	.bmap = _isofs_bmap
};

static inline void test_and_set_uid(uid_t *p, uid_t value)
{
	if (value)
		*p = value;
}

static inline void test_and_set_gid(gid_t *p, gid_t value)
{
        if (value)
                *p = value;
}

static int isofs_read_level3_size(struct inode *inode)
{
	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
	int high_sierra = ISOFS_SB(inode->i_sb)->s_high_sierra;
	struct buffer_head *bh = NULL;
	unsigned long block, offset, block_saved, offset_saved;
	int i = 0;
	int more_entries = 0;
	struct iso_directory_record *tmpde = NULL;
	struct iso_inode_info *ei = ISOFS_I(inode);

	inode->i_size = 0;

	/* The first 16 blocks are reserved as the System Area.  Thus,
	 * no inodes can appear in block 0.  We use this to flag that
	 * this is the last section. */
	ei->i_next_section_block = 0;
	ei->i_next_section_offset = 0;

	block = ei->i_iget5_block;
	offset = ei->i_iget5_offset;

	do {
		struct iso_directory_record *de;
		unsigned int de_len;

		if (!bh) {
			bh = sb_bread(inode->i_sb, block);
			if (!bh)
				goto out_noread;
		}
		de = (struct iso_directory_record *) (bh->b_data + offset);
		de_len = *(unsigned char *) de;

		if (de_len == 0) {
			brelse(bh);
			bh = NULL;
			++block;
			offset = 0;
			continue;
		}

		block_saved = block;
		offset_saved = offset;
		offset += de_len;

		/* Make sure we have a full directory entry */
		if (offset >= bufsize) {
			int slop = bufsize - offset + de_len;
			if (!tmpde) {
				tmpde = kmalloc(256, GFP_KERNEL);
				if (!tmpde)
					goto out_nomem;
			}
			memcpy(tmpde, de, slop);
			offset &= bufsize - 1;
			block++;
			brelse(bh);
			bh = NULL;
			if (offset) {
				bh = sb_bread(inode->i_sb, block);
				if (!bh)
					goto out_noread;
				memcpy((void *)tmpde+slop, bh->b_data, offset);
			}
			de = tmpde;
		}

		inode->i_size += isonum_733(de->size);
		if (i == 1) {
			ei->i_next_section_block = block_saved;
			ei->i_next_section_offset = offset_saved;
		}

		more_entries = de->flags[-high_sierra] & 0x80;

		i++;
		if (i > 100)
			goto out_toomany;
	} while (more_entries);
out:
	kfree(tmpde);
	if (bh)
		brelse(bh);
	return 0;

out_nomem:
	if (bh)
		brelse(bh);
	return -ENOMEM;

out_noread:
	printk(KERN_INFO "ISOFS: unable to read i-node block %lu\n", block);
	kfree(tmpde);
	return -EIO;

out_toomany:
	printk(KERN_INFO "%s: More than 100 file sections ?!?, aborting...\n"
		"isofs_read_level3_size: inode=%lu\n",
		__func__, inode->i_ino);
	goto out;
}

static void isofs_read_inode(struct inode *inode)
{
	struct super_block *sb = inode->i_sb;
	struct isofs_sb_info *sbi = ISOFS_SB(sb);
	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
	unsigned long block;
	int high_sierra = sbi->s_high_sierra;
	struct buffer_head *bh = NULL;
	struct iso_directory_record *de;
	struct iso_directory_record *tmpde = NULL;
	unsigned int de_len;
	unsigned long offset;
	struct iso_inode_info *ei = ISOFS_I(inode);

	block = ei->i_iget5_block;
	bh = sb_bread(inode->i_sb, block);
	if (!bh)
		goto out_badread;

	offset = ei->i_iget5_offset;

	de = (struct iso_directory_record *) (bh->b_data + offset);
	de_len = *(unsigned char *) de;

	if (offset + de_len > bufsize) {
		int frag1 = bufsize - offset;

		tmpde = kmalloc(de_len, GFP_KERNEL);
		if (tmpde == NULL) {
			printk(KERN_INFO "%s: out of memory\n", __func__);
			goto fail;
		}
		memcpy(tmpde, bh->b_data + offset, frag1);
		brelse(bh);
		bh = sb_bread(inode->i_sb, ++block);
		if (!bh)
			goto out_badread;
		memcpy((char *)tmpde+frag1, bh->b_data, de_len - frag1);
		de = tmpde;
	}

	inode->i_ino = isofs_get_ino(ei->i_iget5_block,
					ei->i_iget5_offset,
					ISOFS_BUFFER_BITS(inode));

	/* Assume it is a normal-format file unless told otherwise */
	ei->i_file_format = isofs_file_normal;

	if (de->flags[-high_sierra] & 2) {
		inode->i_mode = S_IRUGO | S_IXUGO | S_IFDIR;
		inode->i_nlink = 1;	/*
					 * Set to 1.  We know there are 2, but
					 * the find utility tries to optimize
					 * if it is 2, and it screws up.  It is
					 * easier to give 1 which tells find to
					 * do it the hard way.
					 */
	} else {
		/* Everybody gets to read the file. */
		inode->i_mode = sbi->s_mode;
		inode->i_nlink = 1;
		inode->i_mode |= S_IFREG;
	}
	inode->i_uid = sbi->s_uid;
	inode->i_gid = sbi->s_gid;
	inode->i_blocks = 0;

	ei->i_format_parm[0] = 0;
	ei->i_format_parm[1] = 0;
	ei->i_format_parm[2] = 0;

	ei->i_section_size = isonum_733(de->size);
	if (de->flags[-high_sierra] & 0x80) {
		if(isofs_read_level3_size(inode))
			goto fail;
	} else {
		ei->i_next_section_block = 0;
		ei->i_next_section_offset = 0;
		inode->i_size = isonum_733(de->size);
	}

	/*
	 * Some dipshit decided to store some other bit of information
	 * in the high byte of the file length.  Truncate size in case
	 * this CDROM was mounted with the cruft option.
	 */

	if (sbi->s_cruft == 'y')
		inode->i_size &= 0x00ffffff;

	if (de->interleave[0]) {
		printk(KERN_DEBUG "ISOFS: Interleaved files not (yet) supported.\n");
		inode->i_size = 0;
	}

	/* I have no idea what file_unit_size is used for, so
	   we will flag it for now */
	if (de->file_unit_size[0] != 0) {
		printk(KERN_DEBUG "ISOFS: File unit size != 0 for ISO file (%ld).\n",
			inode->i_ino);
	}

	/* I have no idea what other flag bits are used for, so
	   we will flag it for now */
#ifdef DEBUG
	if((de->flags[-high_sierra] & ~2)!= 0){
		printk(KERN_DEBUG "ISOFS: Unusual flag settings for ISO file "
				"(%ld %x).\n",
			inode->i_ino, de->flags[-high_sierra]);
	}
#endif

	inode->i_mtime.tv_sec =
	inode->i_atime.tv_sec =
	inode->i_ctime.tv_sec = iso_date(de->date, high_sierra);
	inode->i_mtime.tv_nsec =
	inode->i_atime.tv_nsec =
	inode->i_ctime.tv_nsec = 0;

	ei->i_first_extent = (isonum_733(de->extent) +
			isonum_711(de->ext_attr_length));

	/* Set the number of blocks for stat() - should be done before RR */
	inode->i_blocks = (inode->i_size + 511) >> 9;

	/*
	 * Now test for possible Rock Ridge extensions which will override
	 * some of these numbers in the inode structure.
	 */

	if (!high_sierra) {
		parse_rock_ridge_inode(de, inode);
		/* if we want uid/gid set, override the rock ridge setting */
		test_and_set_uid(&inode->i_uid, sbi->s_uid);
		test_and_set_gid(&inode->i_gid, sbi->s_gid);
	}

	/* Install the inode operations vector */
	if (S_ISREG(inode->i_mode)) {
		inode->i_fop = &generic_ro_fops;
		switch (ei->i_file_format) {
#ifdef CONFIG_ZISOFS
		case isofs_file_compressed:
			inode->i_data.a_ops = &zisofs_aops;
			break;
#endif
		default:
			inode->i_data.a_ops = &isofs_aops;
			break;
		}
	} else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &isofs_dir_inode_operations;
		inode->i_fop = &isofs_dir_operations;
	} else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &page_symlink_inode_operations;
		inode->i_data.a_ops = &isofs_symlink_aops;
	} else
		/* XXX - parse_rock_ridge_inode() had already set i_rdev. */
		init_special_inode(inode, inode->i_mode, inode->i_rdev);

out:
	kfree(tmpde);
	if (bh)
		brelse(bh);
	return;

out_badread:
	printk(KERN_WARNING "ISOFS: unable to read i-node block\n");
fail:
	make_bad_inode(inode);
	goto out;
}

struct isofs_iget5_callback_data {
	unsigned long block;
	unsigned long offset;
};

static int isofs_iget5_test(struct inode *ino, void *data)
{
	struct iso_inode_info *i = ISOFS_I(ino);
	struct isofs_iget5_callback_data *d =
		(struct isofs_iget5_callback_data*)data;
	return (i->i_iget5_block == d->block)
		&& (i->i_iget5_offset == d->offset);
}

static int isofs_iget5_set(struct inode *ino, void *data)
{
	struct iso_inode_info *i = ISOFS_I(ino);
	struct isofs_iget5_callback_data *d =
		(struct isofs_iget5_callback_data*)data;
	i->i_iget5_block = d->block;
	i->i_iget5_offset = d->offset;
	return 0;
}

/* Store, in the inode's containing structure, the block and block
 * offset that point to the underlying meta-data for the inode.  The
 * code below is otherwise similar to the iget() code in
 * include/linux/fs.h */
struct inode *isofs_iget(struct super_block *sb,
			 unsigned long block,
			 unsigned long offset)
{
	unsigned long hashval;
	struct inode *inode;
	struct isofs_iget5_callback_data data;

	if (offset >= 1ul << sb->s_blocksize_bits)
		return NULL;

	data.block = block;
	data.offset = offset;

	hashval = (block << sb->s_blocksize_bits) | offset;

	inode = iget5_locked(sb, hashval, &isofs_iget5_test,
				&isofs_iget5_set, &data);

	if (inode && (inode->i_state & I_NEW)) {
		sb->s_op->read_inode(inode);
		unlock_new_inode(inode);
	}

	return inode;
}

static int isofs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
	return get_sb_bdev(fs_type, flags, dev_name, data, isofs_fill_super,
				mnt);
}

static struct file_system_type iso9660_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "iso9660",
	.get_sb		= isofs_get_sb,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};

static int __init init_iso9660_fs(void)
{
	int err = init_inodecache();
	if (err)
		goto out;
#ifdef CONFIG_ZISOFS
	err = zisofs_init();
	if (err)
		goto out1;
#endif
	err = register_filesystem(&iso9660_fs_type);
	if (err)
		goto out2;
	return 0;
out2:
#ifdef CONFIG_ZISOFS
	zisofs_cleanup();
out1:
#endif
	destroy_inodecache();
out:
	return err;
}

static void __exit exit_iso9660_fs(void)
{
        unregister_filesystem(&iso9660_fs_type);
#ifdef CONFIG_ZISOFS
	zisofs_cleanup();
#endif
	destroy_inodecache();
}

module_init(init_iso9660_fs)
module_exit(exit_iso9660_fs)
MODULE_LICENSE("GPL");
/* Actual filesystem name is iso9660, as requested in filesystems.c */
MODULE_ALIAS("iso9660");