dir.c

UnixBSD、SunOs、FreeBSD、NetBSD、OpenBSD和NeXTStep文件系统源代码

	for (n = 0; n <= npages; n++) {
		char *dir_end;

		page = ufs_get_page(dir, n);
		err = PTR_ERR(page);
		if (IS_ERR(page))
			goto out;
		lock_page(page);
		kaddr = page_address(page);
		dir_end = kaddr + ufs_last_byte(dir, n);
		de = (struct ufs_dir_entry *)kaddr;
		kaddr += PAGE_CACHE_SIZE - reclen;
		while ((char *)de <= kaddr) {
			if ((char *)de == dir_end) {
				/* We hit i_size */
				name_len = 0;
				rec_len = chunk_size;
				de->d_reclen = cpu_to_fs16(sb, chunk_size);
				de->d_ino = 0;
				goto got_it;
			}
			if (de->d_reclen == 0) {
				ufs_error(dir->i_sb, __func__,
					  "zero-length directory entry");
				err = -EIO;
				goto out_unlock;
			}
			err = -EEXIST;
			if (ufs_match(sb, namelen, name, de))
				goto out_unlock;
			name_len = UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, de));
			rec_len = fs16_to_cpu(sb, de->d_reclen);
			if (!de->d_ino && rec_len >= reclen)
				goto got_it;
			if (rec_len >= name_len + reclen)
				goto got_it;
			de = (struct ufs_dir_entry *) ((char *) de + rec_len);
		}
		unlock_page(page);
		ufs_put_page(page);
	}
	BUG();
	return -EINVAL;

got_it:
	pos = page_offset(page) +
			(char*)de - (char*)page_address(page);
	err = __ufs_write_begin(NULL, page->mapping, pos, rec_len,
				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	if (err)
		goto out_unlock;
	if (de->d_ino) {
		struct ufs_dir_entry *de1 =
			(struct ufs_dir_entry *) ((char *) de + name_len);
		de1->d_reclen = cpu_to_fs16(sb, rec_len - name_len);
		de->d_reclen = cpu_to_fs16(sb, name_len);

		de = de1;
	}

	ufs_set_de_namlen(sb, de, namelen);
	memcpy(de->d_name, name, namelen + 1);
	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
	ufs_set_de_type(sb, de, inode->i_mode);

	err = ufs_commit_chunk(page, pos, rec_len);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;

	mark_inode_dirty(dir);
	/* OFFSET_CACHE */
out_put:
	ufs_put_page(page);
out:
	return err;
out_unlock:
	unlock_page(page);
	goto out_put;
}

static inline unsigned
ufs_validate_entry(struct super_block *sb, char *base,
		   unsigned offset, unsigned mask)
{
	struct ufs_dir_entry *de = (struct ufs_dir_entry*)(base + offset);
	struct ufs_dir_entry *p = (struct ufs_dir_entry*)(base + (offset&mask));
	while ((char*)p < (char*)de) {
		if (p->d_reclen == 0)
			break;
		p = ufs_next_entry(sb, p);
	}
	return (char *)p - base;
}


/*
 * This is blatantly stolen from ext2fs
 */
static int
ufs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
	loff_t pos = filp->f_pos;
	struct inode *inode = filp->f_path.dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	unsigned long npages = ufs_dir_pages(inode);
	unsigned chunk_mask = ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
	int need_revalidate = filp->f_version != inode->i_version;
	unsigned flags = UFS_SB(sb)->s_flags;

	UFSD("BEGIN\n");

	if (pos > inode->i_size - UFS_DIR_REC_LEN(1))
		return 0;

	for ( ; n < npages; n++, offset = 0) {
		char *kaddr, *limit;
		struct ufs_dir_entry *de;

		struct page *page = ufs_get_page(inode, n);

		if (IS_ERR(page)) {
			ufs_error(sb, __func__,
				  "bad page in #%lu",
				  inode->i_ino);
			filp->f_pos += PAGE_CACHE_SIZE - offset;
			return -EIO;
		}
		kaddr = page_address(page);
		if (unlikely(need_revalidate)) {
			if (offset) {
				offset = ufs_validate_entry(sb, kaddr, offset, chunk_mask);
				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
			}
			filp->f_version = inode->i_version;
			need_revalidate = 0;
		}
		de = (struct ufs_dir_entry *)(kaddr+offset);
		limit = kaddr + ufs_last_byte(inode, n) - UFS_DIR_REC_LEN(1);
		for ( ;(char*)de <= limit; de = ufs_next_entry(sb, de)) {
			if (de->d_reclen == 0) {
				ufs_error(sb, __func__,
					"zero-length directory entry");
				ufs_put_page(page);
				return -EIO;
			}
			if (de->d_ino) {
				int over;
				unsigned char d_type = DT_UNKNOWN;

				offset = (char *)de - kaddr;

				UFSD("filldir(%s,%u)\n", de->d_name,
				      fs32_to_cpu(sb, de->d_ino));
				UFSD("namlen %u\n", ufs_get_de_namlen(sb, de));

				if ((flags & UFS_DE_MASK) == UFS_DE_44BSD)
					d_type = de->d_u.d_44.d_type;

				over = filldir(dirent, de->d_name,
					       ufs_get_de_namlen(sb, de),
						(n<<PAGE_CACHE_SHIFT) | offset,
					       fs32_to_cpu(sb, de->d_ino), d_type);
				if (over) {
					ufs_put_page(page);
					return 0;
				}
			}
			filp->f_pos += fs16_to_cpu(sb, de->d_reclen);
		}
		ufs_put_page(page);
	}
	return 0;
}


/*
 * ufs_delete_entry deletes a directory entry by merging it with the
 * previous entry.
 */
int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
		     struct page * page)
{
	struct super_block *sb = inode->i_sb;
	struct address_space *mapping = page->mapping;
	char *kaddr = page_address(page);
	unsigned from = ((char*)dir - kaddr) & ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
	unsigned to = ((char*)dir - kaddr) + fs16_to_cpu(sb, dir->d_reclen);
	loff_t pos;
	struct ufs_dir_entry *pde = NULL;
	struct ufs_dir_entry *de = (struct ufs_dir_entry *) (kaddr + from);
	int err;

	UFSD("ENTER\n");

	UFSD("ino %u, reclen %u, namlen %u, name %s\n",
	      fs32_to_cpu(sb, de->d_ino),
	      fs16_to_cpu(sb, de->d_reclen),
	      ufs_get_de_namlen(sb, de), de->d_name);

	while ((char*)de < (char*)dir) {
		if (de->d_reclen == 0) {
			ufs_error(inode->i_sb, __func__,
				  "zero-length directory entry");
			err = -EIO;
			goto out;
		}
		pde = de;
		de = ufs_next_entry(sb, de);
	}
	if (pde)
		from = (char*)pde - (char*)page_address(page);

	pos = page_offset(page) + from;
	lock_page(page);
	err = __ufs_write_begin(NULL, mapping, pos, to - from,
				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	BUG_ON(err);
	if (pde)
		pde->d_reclen = cpu_to_fs16(sb, to - from);
	dir->d_ino = 0;
	err = ufs_commit_chunk(page, pos, to - from);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	mark_inode_dirty(inode);
out:
	ufs_put_page(page);
	UFSD("EXIT\n");
	return err;
}

int ufs_make_empty(struct inode * inode, struct inode *dir)
{
	struct super_block * sb = dir->i_sb;
	struct address_space *mapping = inode->i_mapping;
	struct page *page = grab_cache_page(mapping, 0);
	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
	struct ufs_dir_entry * de;
	char *base;
	int err;

	if (!page)
		return -ENOMEM;

	err = __ufs_write_begin(NULL, mapping, 0, chunk_size,
				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	if (err) {
		unlock_page(page);
		goto fail;
	}

	kmap(page);
	base = (char*)page_address(page);
	memset(base, 0, PAGE_CACHE_SIZE);

	de = (struct ufs_dir_entry *) base;

	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
	ufs_set_de_type(sb, de, inode->i_mode);
	ufs_set_de_namlen(sb, de, 1);
	de->d_reclen = cpu_to_fs16(sb, UFS_DIR_REC_LEN(1));
	strcpy (de->d_name, ".");
	de = (struct ufs_dir_entry *)
		((char *)de + fs16_to_cpu(sb, de->d_reclen));
	de->d_ino = cpu_to_fs32(sb, dir->i_ino);
	ufs_set_de_type(sb, de, dir->i_mode);
	de->d_reclen = cpu_to_fs16(sb, chunk_size - UFS_DIR_REC_LEN(1));
	ufs_set_de_namlen(sb, de, 2);
	strcpy (de->d_name, "..");
	kunmap(page);

	err = ufs_commit_chunk(page, 0, chunk_size);
fail:
	page_cache_release(page);
	return err;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int ufs_empty_dir(struct inode * inode)
{
	struct super_block *sb = inode->i_sb;
	struct page *page = NULL;
	unsigned long i, npages = ufs_dir_pages(inode);

	for (i = 0; i < npages; i++) {
		char *kaddr;
		struct ufs_dir_entry *de;
		page = ufs_get_page(inode, i);

		if (IS_ERR(page))
			continue;

		kaddr = page_address(page);
		de = (struct ufs_dir_entry *)kaddr;
		kaddr += ufs_last_byte(inode, i) - UFS_DIR_REC_LEN(1);

		while ((char *)de <= kaddr) {
			if (de->d_reclen == 0) {
				ufs_error(inode->i_sb, __func__,
					"zero-length directory entry: "
					"kaddr=%p, de=%p\n", kaddr, de);
				goto not_empty;
			}
			if (de->d_ino) {
				u16 namelen=ufs_get_de_namlen(sb, de);
				/* check for . and .. */
				if (de->d_name[0] != '.')
					goto not_empty;
				if (namelen > 2)
					goto not_empty;
				if (namelen < 2) {
					if (inode->i_ino !=
					    fs32_to_cpu(sb, de->d_ino))
						goto not_empty;
				} else if (de->d_name[1] != '.')
					goto not_empty;
			}
			de = ufs_next_entry(sb, de);
		}
		ufs_put_page(page);
	}
	return 1;

not_empty:
	ufs_put_page(page);
	return 0;
}

const struct file_operations ufs_dir_operations = {
	.read		= generic_read_dir,
	.readdir	= ufs_readdir,
	.fsync		= file_fsync,
	.llseek		= generic_file_llseek,
};