[linux.git] / fs / ext2 / dir.c

/*
 *  linux/fs/ext2/dir.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([email protected])
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext2 directory handling functions
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller ([email protected]), 1995
 *
 * All code that works with directory layout had been switched to pagecache
 * and moved here. AV
 */

#include "ext2.h"
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/swap.h>

typedef struct ext2_dir_entry_2 ext2_dirent;

static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
{
	unsigned len = le16_to_cpu(dlen);

	if (len == EXT2_MAX_REC_LEN)
		return 1 << 16;
	return len;
}

static inline __le16 ext2_rec_len_to_disk(unsigned len)
{
	if (len == (1 << 16))
		return cpu_to_le16(EXT2_MAX_REC_LEN);
	else
		BUG_ON(len > (1 << 16));
	return cpu_to_le16(len);
}

/*
 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
 * more robust, but we have what we have
 */
static inline unsigned ext2_chunk_size(struct inode *inode)
{
	return inode->i_sb->s_blocksize;
}

static inline void ext2_put_page(struct page *page)
{
	kunmap(page);
	page_cache_release(page);
}

static inline unsigned long dir_pages(struct inode *inode)
{
	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}

/*
 * Return the offset into page `page_nr' of the last valid
 * byte in that page, plus one.
 */
static unsigned
ext2_last_byte(struct inode *inode, unsigned long page_nr)
{
	unsigned last_byte = inode->i_size;

	last_byte -= page_nr << PAGE_CACHE_SHIFT;
	if (last_byte > PAGE_CACHE_SIZE)
		last_byte = PAGE_CACHE_SIZE;
	return last_byte;
}

static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
	struct address_space *mapping = page->mapping;
	struct inode *dir = mapping->host;
	int err = 0;

	dir->i_version++;
	block_write_end(NULL, mapping, pos, len, len, page, NULL);

	if (pos+len > dir->i_size) {
		i_size_write(dir, pos+len);
		mark_inode_dirty(dir);
	}

	if (IS_DIRSYNC(dir))
		err = write_one_page(page, 1);
	else
		unlock_page(page);

	return err;
}

static void ext2_check_page(struct page *page)
{
	struct inode *dir = page->mapping->host;
	struct super_block *sb = dir->i_sb;
	unsigned chunk_size = ext2_chunk_size(dir);
	char *kaddr = page_address(page);
	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
	unsigned offs, rec_len;
	unsigned limit = PAGE_CACHE_SIZE;
	ext2_dirent *p;
	char *error;

	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
		limit = dir->i_size & ~PAGE_CACHE_MASK;
		if (limit & (chunk_size - 1))
			goto Ebadsize;
		if (!limit)
			goto out;
	}
	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
		p = (ext2_dirent *)(kaddr + offs);
		rec_len = ext2_rec_len_from_disk(p->rec_len);

		if (rec_len < EXT2_DIR_REC_LEN(1))
			goto Eshort;
		if (rec_len & 3)
			goto Ealign;
		if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
			goto Enamelen;
		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
			goto Espan;
		if (le32_to_cpu(p->inode) > max_inumber)
			goto Einumber;
	}
	if (offs != limit)
		goto Eend;
out:
	SetPageChecked(page);
	return;

	/* Too bad, we had an error */

Ebadsize:
	ext2_error(sb, "ext2_check_page",
		"size of directory #%lu is not a multiple of chunk size",
		dir->i_ino
	);
	goto fail;
Eshort:
	error = "rec_len is smaller than minimal";
	goto bad_entry;
Ealign:
	error = "unaligned directory entry";
	goto bad_entry;
Enamelen:
	error = "rec_len is too small for name_len";
	goto bad_entry;
Espan:
	error = "directory entry across blocks";
	goto bad_entry;
Einumber:
	error = "inode out of bounds";
bad_entry:
	ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
		"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
		(unsigned long) le32_to_cpu(p->inode),
		rec_len, p->name_len);
	goto fail;
Eend:
	p = (ext2_dirent *)(kaddr + offs);
	ext2_error (sb, "ext2_check_page",
		"entry in directory #%lu spans the page boundary"
		"offset=%lu, inode=%lu",
		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
		(unsigned long) le32_to_cpu(p->inode));
fail:
	SetPageChecked(page);
	SetPageError(page);
}

static struct page * ext2_get_page(struct inode *dir, unsigned long n)
{
	struct address_space *mapping = dir->i_mapping;
	struct page *page = read_mapping_page(mapping, n, NULL);
	if (!IS_ERR(page)) {
		kmap(page);
		if (!PageChecked(page))
			ext2_check_page(page);
		if (PageError(page))
			goto fail;
	}
	return page;

fail:
	ext2_put_page(page);
	return ERR_PTR(-EIO);
}

/*
 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 *
 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
 */
static inline int ext2_match (int len, const char * const name,
					struct ext2_dir_entry_2 * de)
{
	if (len != de->name_len)
		return 0;
	if (!de->inode)
		return 0;
	return !memcmp(name, de->name, len);
}

/*
 * p is at least 6 bytes before the end of page
 */
static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
{
	return (ext2_dirent *)((char *)p +
			ext2_rec_len_from_disk(p->rec_len));
}

static inline unsigned 
ext2_validate_entry(char *base, unsigned offset, unsigned mask)
{
	ext2_dirent *de = (ext2_dirent*)(base + offset);
	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
	while ((char*)p < (char*)de) {
		if (p->rec_len == 0)
			break;
		p = ext2_next_entry(p);
	}
	return (char *)p - base;
}

static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
	[EXT2_FT_UNKNOWN]	= DT_UNKNOWN,
	[EXT2_FT_REG_FILE]	= DT_REG,
	[EXT2_FT_DIR]		= DT_DIR,
	[EXT2_FT_CHRDEV]	= DT_CHR,
	[EXT2_FT_BLKDEV]	= DT_BLK,
	[EXT2_FT_FIFO]		= DT_FIFO,
	[EXT2_FT_SOCK]		= DT_SOCK,
	[EXT2_FT_SYMLINK]	= DT_LNK,
};

#define S_SHIFT 12
static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
	[S_IFREG >> S_SHIFT]	= EXT2_FT_REG_FILE,
	[S_IFDIR >> S_SHIFT]	= EXT2_FT_DIR,
	[S_IFCHR >> S_SHIFT]	= EXT2_FT_CHRDEV,
	[S_IFBLK >> S_SHIFT]	= EXT2_FT_BLKDEV,
	[S_IFIFO >> S_SHIFT]	= EXT2_FT_FIFO,
	[S_IFSOCK >> S_SHIFT]	= EXT2_FT_SOCK,
	[S_IFLNK >> S_SHIFT]	= EXT2_FT_SYMLINK,
};

static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
{
	mode_t mode = inode->i_mode;
	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	else
		de->file_type = 0;
}

static int
ext2_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 = dir_pages(inode);
	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
	unsigned char *types = NULL;
	int need_revalidate = filp->f_version != inode->i_version;

	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
		return 0;

	if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
		types = ext2_filetype_table;

	for ( ; n < npages; n++, offset = 0) {
		char *kaddr, *limit;
		ext2_dirent *de;
		struct page *page = ext2_get_page(inode, n);

		if (IS_ERR(page)) {
			ext2_error(sb, __func__,
				   "bad page in #%lu",
				   inode->i_ino);
			filp->f_pos += PAGE_CACHE_SIZE - offset;
			return PTR_ERR(page);
		}
		kaddr = page_address(page);
		if (unlikely(need_revalidate)) {
			if (offset) {
				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
			}
			filp->f_version = inode->i_version;
			need_revalidate = 0;
		}
		de = (ext2_dirent *)(kaddr+offset);
		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
			if (de->rec_len == 0) {
				ext2_error(sb, __func__,
					"zero-length directory entry");
				ext2_put_page(page);
				return -EIO;
			}
			if (de->inode) {
				int over;
				unsigned char d_type = DT_UNKNOWN;

				if (types && de->file_type < EXT2_FT_MAX)
					d_type = types[de->file_type];

				offset = (char *)de - kaddr;
				over = filldir(dirent, de->name, de->name_len,
						(n<<PAGE_CACHE_SHIFT) | offset,
						le32_to_cpu(de->inode), d_type);
				if (over) {
					ext2_put_page(page);
					return 0;
				}
			}
			filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
		}
		ext2_put_page(page);
	}
	return 0;
}

/*
 *	ext2_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the page in which the entry was found, and the entry itself
 * (as a parameter - res_dir). Page is returned mapped and unlocked.
 * Entry is guaranteed to be valid.
 */
struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
			struct dentry *dentry, struct page ** res_page)
{
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	unsigned long start, n;
	unsigned long npages = dir_pages(dir);
	struct page *page = NULL;
	struct ext2_inode_info *ei = EXT2_I(dir);
	ext2_dirent * de;

	if (npages == 0)
		goto out;

	/* OFFSET_CACHE */
	*res_page = NULL;

	start = ei->i_dir_start_lookup;
	if (start >= npages)
		start = 0;
	n = start;
	do {
		char *kaddr;
		page = ext2_get_page(dir, n);
		if (!IS_ERR(page)) {
			kaddr = page_address(page);
			de = (ext2_dirent *) kaddr;
			kaddr += ext2_last_byte(dir, n) - reclen;
			while ((char *) de <= kaddr) {
				if (de->rec_len == 0) {
					ext2_error(dir->i_sb, __func__,
						"zero-length directory entry");
					ext2_put_page(page);
					goto out;
				}
				if (ext2_match (namelen, name, de))
					goto found;
				de = ext2_next_entry(de);
			}
			ext2_put_page(page);
		}
		if (++n >= npages)
			n = 0;
		/* next page is past the blocks we've got */
		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
			ext2_error(dir->i_sb, __func__,
				"dir %lu size %lld exceeds block count %llu",
				dir->i_ino, dir->i_size,
				(unsigned long long)dir->i_blocks);
			goto out;
		}
	} while (n != start);
out:
	return NULL;

found:
	*res_page = page;
	ei->i_dir_start_lookup = n;
	return de;
}

struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
{
	struct page *page = ext2_get_page(dir, 0);
	ext2_dirent *de = NULL;

	if (!IS_ERR(page)) {
		de = ext2_next_entry((ext2_dirent *) page_address(page));
		*p = page;
	}
	return de;
}

ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
{
	ino_t res = 0;
	struct ext2_dir_entry_2 * de;
	struct page *page;
	
	de = ext2_find_entry (dir, dentry, &page);
	if (de) {
		res = le32_to_cpu(de->inode);
		ext2_put_page(page);
	}
	return res;
}

/* Releases the page */
void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
			struct page *page, struct inode *inode)
{
	loff_t pos = page_offset(page) +
			(char *) de - (char *) page_address(page);
	unsigned len = ext2_rec_len_from_disk(de->rec_len);
	int err;

	lock_page(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, len,
				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	BUG_ON(err);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type(de, inode);
	err = ext2_commit_chunk(page, pos, len);
	ext2_put_page(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
}

/*
 *	Parent is locked.
 */
int ext2_add_link (struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = dentry->d_parent->d_inode;
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned chunk_size = ext2_chunk_size(dir);
	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	unsigned short rec_len, name_len;
	struct page *page = NULL;
	ext2_dirent * de;
	unsigned long npages = dir_pages(dir);
	unsigned long n;
	char *kaddr;
	loff_t pos;
	int err;

	/*
	 * We take care of directory expansion in the same loop.
	 * This code plays outside i_size, so it locks the page
	 * to protect that region.
	 */
	for (n = 0; n <= npages; n++) {
		char *dir_end;

		page = ext2_get_page(dir, n);
		err = PTR_ERR(page);
		if (IS_ERR(page))
			goto out;
		lock_page(page);
		kaddr = page_address(page);
		dir_end = kaddr + ext2_last_byte(dir, n);
		de = (ext2_dirent *)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->rec_len = ext2_rec_len_to_disk(chunk_size);
				de->inode = 0;
				goto got_it;
			}
			if (de->rec_len == 0) {
				ext2_error(dir->i_sb, __func__,
					"zero-length directory entry");
				err = -EIO;
				goto out_unlock;
			}
			err = -EEXIST;
			if (ext2_match (namelen, name, de))
				goto out_unlock;
			name_len = EXT2_DIR_REC_LEN(de->name_len);
			rec_len = ext2_rec_len_from_disk(de->rec_len);
			if (!de->inode && rec_len >= reclen)
				goto got_it;
			if (rec_len >= name_len + reclen)
				goto got_it;
			de = (ext2_dirent *) ((char *) de + rec_len);
		}
		unlock_page(page);
		ext2_put_page(page);
	}
	BUG();
	return -EINVAL;

got_it:
	pos = page_offset(page) +
		(char*)de - (char*)page_address(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
							&page, NULL);
	if (err)
		goto out_unlock;
	if (de->inode) {
		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
		de->rec_len = ext2_rec_len_to_disk(name_len);
		de = de1;
	}
	de->name_len = namelen;
	memcpy(de->name, name, namelen);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type (de, inode);
	err = ext2_commit_chunk(page, pos, rec_len);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
	/* OFFSET_CACHE */
out_put:
	ext2_put_page(page);
out:
	return err;
out_unlock:
	unlock_page(page);
	goto out_put;
}

/*
 * ext2_delete_entry deletes a directory entry by merging it with the
 * previous entry. Page is up-to-date. Releases the page.
 */
int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
{
	struct address_space *mapping = page->mapping;
	struct inode *inode = mapping->host;
	char *kaddr = page_address(page);
	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
	unsigned to = ((char *)dir - kaddr) +
				ext2_rec_len_from_disk(dir->rec_len);
	loff_t pos;
	ext2_dirent * pde = NULL;
	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
	int err;

	while ((char*)de < (char*)dir) {
		if (de->rec_len == 0) {
			ext2_error(inode->i_sb, __func__,
				"zero-length directory entry");
			err = -EIO;
			goto out;
		}
		pde = de;
		de = ext2_next_entry(de);
	}
	if (pde)
		from = (char*)pde - (char*)page_address(page);
	pos = page_offset(page) + from;
	lock_page(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, to - from, 0,
							&page, NULL);
	BUG_ON(err);
	if (pde)
		pde->rec_len = ext2_rec_len_to_disk(to - from);
	dir->inode = 0;
	err = ext2_commit_chunk(page, pos, to - from);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(inode);
out:
	ext2_put_page(page);
	return err;
}

/*
 * Set the first fragment of directory.
 */
int ext2_make_empty(struct inode *inode, struct inode *parent)
{
	struct address_space *mapping = inode->i_mapping;
	struct page *page = grab_cache_page(mapping, 0);
	unsigned chunk_size = ext2_chunk_size(inode);
	struct ext2_dir_entry_2 * de;
	int err;
	void *kaddr;

	if (!page)
		return -ENOMEM;

	err = __ext2_write_begin(NULL, page->mapping, 0, chunk_size, 0,
							&page, NULL);
	if (err) {
		unlock_page(page);
		goto fail;
	}
	kaddr = kmap_atomic(page, KM_USER0);
	memset(kaddr, 0, chunk_size);
	de = (struct ext2_dir_entry_2 *)kaddr;
	de->name_len = 1;
	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
	memcpy (de->name, ".\0\0", 4);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type (de, inode);

	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
	de->name_len = 2;
	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
	de->inode = cpu_to_le32(parent->i_ino);
	memcpy (de->name, "..\0", 4);
	ext2_set_de_type (de, inode);
	kunmap_atomic(kaddr, KM_USER0);
	err = ext2_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 ext2_empty_dir (struct inode * inode)
{
	struct page *page = NULL;
	unsigned long i, npages = dir_pages(inode);

	for (i = 0; i < npages; i++) {
		char *kaddr;
		ext2_dirent * de;
		page = ext2_get_page(inode, i);

		if (IS_ERR(page))
			continue;

		kaddr = page_address(page);
		de = (ext2_dirent *)kaddr;
		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);

		while ((char *)de <= kaddr) {
			if (de->rec_len == 0) {
				ext2_error(inode->i_sb, __func__,
					"zero-length directory entry");
				printk("kaddr=%p, de=%p\n", kaddr, de);
				goto not_empty;
			}
			if (de->inode != 0) {
				/* check for . and .. */
				if (de->name[0] != '.')
					goto not_empty;
				if (de->name_len > 2)
					goto not_empty;
				if (de->name_len < 2) {
					if (de->inode !=
					    cpu_to_le32(inode->i_ino))
						goto not_empty;
				} else if (de->name[1] != '.')
					goto not_empty;
			}
			de = ext2_next_entry(de);
		}
		ext2_put_page(page);
	}
	return 1;

not_empty:
	ext2_put_page(page);
	return 0;
}

const struct file_operations ext2_dir_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.readdir	= ext2_readdir,
	.unlocked_ioctl = ext2_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= ext2_compat_ioctl,
#endif
	.fsync		= ext2_sync_file,
};
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/ext2/dir.c
	3	*
	4	* Copyright (C) 1992, 1993, 1994, 1995
	5	* Remy Card ([email protected])
	6	* Laboratoire MASI - Institut Blaise Pascal
	7	* Universite Pierre et Marie Curie (Paris VI)
	8	*
	9	* from
	10	*
	11	* linux/fs/minix/dir.c
	12	*
	13	* Copyright (C) 1991, 1992 Linus Torvalds
	14	*
	15	* ext2 directory handling functions
	16	*
	17	* Big-endian to little-endian byte-swapping/bitmaps by
	18	* David S. Miller ([email protected]), 1995
	19	*
	20	* All code that works with directory layout had been switched to pagecache
	21	* and moved here. AV
	22	*/
	23
	24	#include "ext2.h"
f34fb6ec	25	#include <linux/buffer_head.h>
1da177e4	26	#include <linux/pagemap.h>
f34fb6ec	27	#include <linux/swap.h>
1da177e4 LT	28
	29	typedef struct ext2_dir_entry_2 ext2_dirent;
	30
89910ccc JK	31	static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
	32	{
	33	unsigned len = le16_to_cpu(dlen);
	34
	35	if (len == EXT2_MAX_REC_LEN)
	36	return 1 << 16;
	37	return len;
	38	}
	39
	40	static inline __le16 ext2_rec_len_to_disk(unsigned len)
	41	{
	42	if (len == (1 << 16))
	43	return cpu_to_le16(EXT2_MAX_REC_LEN);
2c11619a JL	44	else
2c11619a JL	45	BUG_ON(len > (1 << 16));
89910ccc JK	46	return cpu_to_le16(len);
	47	}
	48
1da177e4 LT	49	/*
	50	* ext2 uses block-sized chunks. Arguably, sector-sized ones would be
	51	* more robust, but we have what we have
	52	*/
	53	static inline unsigned ext2_chunk_size(struct inode *inode)
	54	{
	55	return inode->i_sb->s_blocksize;
	56	}
	57
	58	static inline void ext2_put_page(struct page *page)
	59	{
	60	kunmap(page);
	61	page_cache_release(page);
	62	}
	63
	64	static inline unsigned long dir_pages(struct inode *inode)
	65	{
	66	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
	67	}
	68
	69	/*
	70	* Return the offset into page `page_nr' of the last valid
	71	* byte in that page, plus one.
	72	*/
	73	static unsigned
	74	ext2_last_byte(struct inode *inode, unsigned long page_nr)
	75	{
	76	unsigned last_byte = inode->i_size;
	77
	78	last_byte -= page_nr << PAGE_CACHE_SHIFT;
	79	if (last_byte > PAGE_CACHE_SIZE)
	80	last_byte = PAGE_CACHE_SIZE;
	81	return last_byte;
	82	}
	83
f34fb6ec	84	static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
1da177e4	85	{
f34fb6ec NP	86	struct address_space *mapping = page->mapping;
f34fb6ec NP	87	struct inode *dir = mapping->host;
1da177e4	88	int err = 0;
f34fb6ec	89
1da177e4	90	dir->i_version++;
f34fb6ec NP	91	block_write_end(NULL, mapping, pos, len, len, page, NULL);
	92
	93	if (pos+len > dir->i_size) {
	94	i_size_write(dir, pos+len);
	95	mark_inode_dirty(dir);
	96	}
	97
1da177e4 LT	98	if (IS_DIRSYNC(dir))
	99	err = write_one_page(page, 1);
	100	else
	101	unlock_page(page);
f34fb6ec	102
1da177e4 LT	103	return err;
	104	}
	105
	106	static void ext2_check_page(struct page *page)
	107	{
	108	struct inode *dir = page->mapping->host;
	109	struct super_block *sb = dir->i_sb;
	110	unsigned chunk_size = ext2_chunk_size(dir);
	111	char *kaddr = page_address(page);
	112	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
	113	unsigned offs, rec_len;
	114	unsigned limit = PAGE_CACHE_SIZE;
	115	ext2_dirent *p;
	116	char *error;
	117
	118	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
	119	limit = dir->i_size & ~PAGE_CACHE_MASK;
	120	if (limit & (chunk_size - 1))
	121	goto Ebadsize;
	122	if (!limit)
	123	goto out;
	124	}
	125	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
	126	p = (ext2_dirent *)(kaddr + offs);
89910ccc	127	rec_len = ext2_rec_len_from_disk(p->rec_len);
1da177e4 LT	128
	129	if (rec_len < EXT2_DIR_REC_LEN(1))
	130	goto Eshort;
	131	if (rec_len & 3)
	132	goto Ealign;
	133	if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
	134	goto Enamelen;
	135	if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
	136	goto Espan;
	137	if (le32_to_cpu(p->inode) > max_inumber)
	138	goto Einumber;
	139	}
	140	if (offs != limit)
	141	goto Eend;
	142	out:
	143	SetPageChecked(page);
	144	return;
	145
	146	/* Too bad, we had an error */
	147
	148	Ebadsize:
	149	ext2_error(sb, "ext2_check_page",
	150	"size of directory #%lu is not a multiple of chunk size",
	151	dir->i_ino
	152	);
	153	goto fail;
	154	Eshort:
	155	error = "rec_len is smaller than minimal";
	156	goto bad_entry;
	157	Ealign:
	158	error = "unaligned directory entry";
	159	goto bad_entry;
	160	Enamelen:
	161	error = "rec_len is too small for name_len";
	162	goto bad_entry;
	163	Espan:
	164	error = "directory entry across blocks";
	165	goto bad_entry;
	166	Einumber:
	167	error = "inode out of bounds";
	168	bad_entry:
	169	ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
	170	"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
	171	dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
	172	(unsigned long) le32_to_cpu(p->inode),
	173	rec_len, p->name_len);
	174	goto fail;
	175	Eend:
	176	p = (ext2_dirent *)(kaddr + offs);
	177	ext2_error (sb, "ext2_check_page",
	178	"entry in directory #%lu spans the page boundary"
	179	"offset=%lu, inode=%lu",
	180	dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
	181	(unsigned long) le32_to_cpu(p->inode));
	182	fail:
	183	SetPageChecked(page);
	184	SetPageError(page);
	185	}
	186
	187	static struct page * ext2_get_page(struct inode *dir, unsigned long n)
	188	{
	189	struct address_space *mapping = dir->i_mapping;
090d2b18	190	struct page *page = read_mapping_page(mapping, n, NULL);
1da177e4	191	if (!IS_ERR(page)) {
1da177e4	192	kmap(page);
1da177e4 LT	193	if (!PageChecked(page))
	194	ext2_check_page(page);
	195	if (PageError(page))
	196	goto fail;
	197	}
	198	return page;
	199
	200	fail:
	201	ext2_put_page(page);
	202	return ERR_PTR(-EIO);
	203	}
	204
	205	/*
	206	* NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
	207	*
	208	* len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
	209	*/
	210	static inline int ext2_match (int len, const char * const name,
	211	struct ext2_dir_entry_2 * de)
	212	{
	213	if (len != de->name_len)
	214	return 0;
	215	if (!de->inode)
	216	return 0;
	217	return !memcmp(name, de->name, len);
	218	}
	219
	220	/*
	221	* p is at least 6 bytes before the end of page
	222	*/
	223	static inline ext2_dirent ext2_next_entry(ext2_dirent p)
	224	{
89910ccc JK	225	return (ext2_dirent )((char )p +
89910ccc JK	226	ext2_rec_len_from_disk(p->rec_len));
1da177e4 LT	227	}
	228
	229	static inline unsigned
	230	ext2_validate_entry(char *base, unsigned offset, unsigned mask)
	231	{
	232	ext2_dirent de = (ext2_dirent)(base + offset);
	233	ext2_dirent p = (ext2_dirent)(base + (offset&mask));
	234	while ((char)p < (char)de) {
	235	if (p->rec_len == 0)
	236	break;
	237	p = ext2_next_entry(p);
	238	}
	239	return (char *)p - base;
	240	}
	241
	242	static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
	243	[EXT2_FT_UNKNOWN] = DT_UNKNOWN,
	244	[EXT2_FT_REG_FILE] = DT_REG,
	245	[EXT2_FT_DIR] = DT_DIR,
	246	[EXT2_FT_CHRDEV] = DT_CHR,
	247	[EXT2_FT_BLKDEV] = DT_BLK,
	248	[EXT2_FT_FIFO] = DT_FIFO,
	249	[EXT2_FT_SOCK] = DT_SOCK,
	250	[EXT2_FT_SYMLINK] = DT_LNK,
	251	};
	252
	253	#define S_SHIFT 12
	254	static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
	255	[S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
	256	[S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
	257	[S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
	258	[S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
	259	[S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
	260	[S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
	261	[S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
	262	};
	263
	264	static inline void ext2_set_de_type(ext2_dirent de, struct inode inode)
	265	{
	266	mode_t mode = inode->i_mode;
	267	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
	268	de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	269	else
	270	de->file_type = 0;
	271	}
	272
	273	static int
	274	ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
	275	{
	276	loff_t pos = filp->f_pos;
c29c6934	277	struct inode *inode = filp->f_path.dentry->d_inode;
1da177e4 LT	278	struct super_block *sb = inode->i_sb;
	279	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	280	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	281	unsigned long npages = dir_pages(inode);
	282	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
	283	unsigned char *types = NULL;
2d7f2ea9	284	int need_revalidate = filp->f_version != inode->i_version;
1da177e4 LT	285
1da177e4 LT	286	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
2d7f2ea9	287	return 0;
1da177e4 LT	288
	289	if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
	290	types = ext2_filetype_table;
	291
	292	for ( ; n < npages; n++, offset = 0) {
	293	char kaddr, limit;
	294	ext2_dirent *de;
	295	struct page *page = ext2_get_page(inode, n);
	296
	297	if (IS_ERR(page)) {
605afd60	298	ext2_error(sb, __func__,
1da177e4 LT	299	"bad page in #%lu",
	300	inode->i_ino);
	301	filp->f_pos += PAGE_CACHE_SIZE - offset;
bbff2860	302	return PTR_ERR(page);
1da177e4 LT	303	}
1da177e4 LT	304	kaddr = page_address(page);
2d7f2ea9 AV	305	if (unlikely(need_revalidate)) {
	306	if (offset) {
	307	offset = ext2_validate_entry(kaddr, offset, chunk_mask);
	308	filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
	309	}
	310	filp->f_version = inode->i_version;
1da177e4 LT	311	need_revalidate = 0;
	312	}
	313	de = (ext2_dirent *)(kaddr+offset);
	314	limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
	315	for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
	316	if (de->rec_len == 0) {
605afd60	317	ext2_error(sb, __func__,
1da177e4	318	"zero-length directory entry");
1da177e4	319	ext2_put_page(page);
2d7f2ea9	320	return -EIO;
1da177e4 LT	321	}
	322	if (de->inode) {
	323	int over;
	324	unsigned char d_type = DT_UNKNOWN;
	325
	326	if (types && de->file_type < EXT2_FT_MAX)
	327	d_type = types[de->file_type];
	328
	329	offset = (char *)de - kaddr;
	330	over = filldir(dirent, de->name, de->name_len,
	331	(n<<PAGE_CACHE_SHIFT) \| offset,
	332	le32_to_cpu(de->inode), d_type);
	333	if (over) {
	334	ext2_put_page(page);
2d7f2ea9	335	return 0;
1da177e4 LT	336	}
1da177e4 LT	337	}
89910ccc	338	filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
1da177e4 LT	339	}
	340	ext2_put_page(page);
	341	}
2d7f2ea9	342	return 0;
1da177e4 LT	343	}
	344
	345	/*
	346	* ext2_find_entry()
	347	*
	348	* finds an entry in the specified directory with the wanted name. It
	349	* returns the page in which the entry was found, and the entry itself
	350	* (as a parameter - res_dir). Page is returned mapped and unlocked.
	351	* Entry is guaranteed to be valid.
	352	*/
	353	struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
	354	struct dentry dentry, struct page * res_page)
	355	{
	356	const char *name = dentry->d_name.name;
	357	int namelen = dentry->d_name.len;
	358	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	359	unsigned long start, n;
	360	unsigned long npages = dir_pages(dir);
	361	struct page *page = NULL;
	362	struct ext2_inode_info *ei = EXT2_I(dir);
	363	ext2_dirent * de;
	364
	365	if (npages == 0)
	366	goto out;
	367
	368	/* OFFSET_CACHE */
	369	*res_page = NULL;
	370
	371	start = ei->i_dir_start_lookup;
	372	if (start >= npages)
	373	start = 0;
	374	n = start;
	375	do {
	376	char *kaddr;
	377	page = ext2_get_page(dir, n);
	378	if (!IS_ERR(page)) {
	379	kaddr = page_address(page);
	380	de = (ext2_dirent *) kaddr;
	381	kaddr += ext2_last_byte(dir, n) - reclen;
	382	while ((char *) de <= kaddr) {
	383	if (de->rec_len == 0) {
605afd60	384	ext2_error(dir->i_sb, __func__,
1da177e4 LT	385	"zero-length directory entry");
	386	ext2_put_page(page);
	387	goto out;
	388	}
	389	if (ext2_match (namelen, name, de))
	390	goto found;
	391	de = ext2_next_entry(de);
	392	}
	393	ext2_put_page(page);
	394	}
	395	if (++n >= npages)
	396	n = 0;
d8adb9ce ES	397	/* next page is past the blocks we've got */
d8adb9ce ES	398	if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
605afd60	399	ext2_error(dir->i_sb, __func__,
d8adb9ce ES	400	"dir %lu size %lld exceeds block count %llu",
	401	dir->i_ino, dir->i_size,
	402	(unsigned long long)dir->i_blocks);
	403	goto out;
	404	}
1da177e4 LT	405	} while (n != start);
	406	out:
	407	return NULL;
	408
	409	found:
	410	*res_page = page;
	411	ei->i_dir_start_lookup = n;
	412	return de;
	413	}
	414
	415	struct ext2_dir_entry_2 * ext2_dotdot (struct inode dir, struct page *p)
	416	{
	417	struct page *page = ext2_get_page(dir, 0);
	418	ext2_dirent *de = NULL;
	419
	420	if (!IS_ERR(page)) {
	421	de = ext2_next_entry((ext2_dirent *) page_address(page));
	422	*p = page;
	423	}
	424	return de;
	425	}
	426
	427	ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
	428	{
	429	ino_t res = 0;
	430	struct ext2_dir_entry_2 * de;
	431	struct page *page;
	432
	433	de = ext2_find_entry (dir, dentry, &page);
	434	if (de) {
	435	res = le32_to_cpu(de->inode);
7d93a1a5	436	ext2_put_page(page);
1da177e4 LT	437	}
	438	return res;
	439	}
	440
	441	/* Releases the page */
	442	void ext2_set_link(struct inode dir, struct ext2_dir_entry_2 de,
	443	struct page page, struct inode inode)
	444	{
f34fb6ec NP	445	loff_t pos = page_offset(page) +
f34fb6ec NP	446	(char ) de - (char ) page_address(page);
89910ccc	447	unsigned len = ext2_rec_len_from_disk(de->rec_len);
1da177e4 LT	448	int err;
	449
	450	lock_page(page);
f34fb6ec NP	451	err = __ext2_write_begin(NULL, page->mapping, pos, len,
f34fb6ec NP	452	AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
309be53d	453	BUG_ON(err);
1da177e4	454	de->inode = cpu_to_le32(inode->i_ino);
f34fb6ec NP	455	ext2_set_de_type(de, inode);
f34fb6ec NP	456	err = ext2_commit_chunk(page, pos, len);
1da177e4 LT	457	ext2_put_page(page);
	458	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	459	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	460	mark_inode_dirty(dir);
	461	}
	462
	463	/*
	464	* Parent is locked.
	465	*/
	466	int ext2_add_link (struct dentry dentry, struct inode inode)
	467	{
	468	struct inode *dir = dentry->d_parent->d_inode;
	469	const char *name = dentry->d_name.name;
	470	int namelen = dentry->d_name.len;
	471	unsigned chunk_size = ext2_chunk_size(dir);
	472	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	473	unsigned short rec_len, name_len;
	474	struct page *page = NULL;
	475	ext2_dirent * de;
	476	unsigned long npages = dir_pages(dir);
	477	unsigned long n;
	478	char *kaddr;
f34fb6ec	479	loff_t pos;
1da177e4 LT	480	int err;
	481
	482	/*
	483	* We take care of directory expansion in the same loop.
	484	* This code plays outside i_size, so it locks the page
	485	* to protect that region.
	486	*/
	487	for (n = 0; n <= npages; n++) {
	488	char *dir_end;
	489
	490	page = ext2_get_page(dir, n);
	491	err = PTR_ERR(page);
	492	if (IS_ERR(page))
	493	goto out;
	494	lock_page(page);
	495	kaddr = page_address(page);
	496	dir_end = kaddr + ext2_last_byte(dir, n);
	497	de = (ext2_dirent *)kaddr;
	498	kaddr += PAGE_CACHE_SIZE - reclen;
	499	while ((char *)de <= kaddr) {
	500	if ((char *)de == dir_end) {
	501	/* We hit i_size */
	502	name_len = 0;
	503	rec_len = chunk_size;
89910ccc	504	de->rec_len = ext2_rec_len_to_disk(chunk_size);
1da177e4 LT	505	de->inode = 0;
	506	goto got_it;
	507	}
	508	if (de->rec_len == 0) {
605afd60	509	ext2_error(dir->i_sb, __func__,
1da177e4 LT	510	"zero-length directory entry");
	511	err = -EIO;
	512	goto out_unlock;
	513	}
	514	err = -EEXIST;
	515	if (ext2_match (namelen, name, de))
	516	goto out_unlock;
	517	name_len = EXT2_DIR_REC_LEN(de->name_len);
89910ccc	518	rec_len = ext2_rec_len_from_disk(de->rec_len);
1da177e4 LT	519	if (!de->inode && rec_len >= reclen)
	520	goto got_it;
	521	if (rec_len >= name_len + reclen)
	522	goto got_it;
	523	de = (ext2_dirent ) ((char ) de + rec_len);
	524	}
	525	unlock_page(page);
	526	ext2_put_page(page);
	527	}
	528	BUG();
	529	return -EINVAL;
	530
	531	got_it:
f34fb6ec NP	532	pos = page_offset(page) +
	533	(char)de - (char)page_address(page);
	534	err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
	535	&page, NULL);
1da177e4 LT	536	if (err)
	537	goto out_unlock;
	538	if (de->inode) {
	539	ext2_dirent de1 = (ext2_dirent ) ((char *) de + name_len);
89910ccc JK	540	de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
89910ccc JK	541	de->rec_len = ext2_rec_len_to_disk(name_len);
1da177e4 LT	542	de = de1;
	543	}
	544	de->name_len = namelen;
f34fb6ec	545	memcpy(de->name, name, namelen);
1da177e4 LT	546	de->inode = cpu_to_le32(inode->i_ino);
1da177e4 LT	547	ext2_set_de_type (de, inode);
f34fb6ec	548	err = ext2_commit_chunk(page, pos, rec_len);
1da177e4 LT	549	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	550	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	551	mark_inode_dirty(dir);
	552	/* OFFSET_CACHE */
	553	out_put:
	554	ext2_put_page(page);
	555	out:
	556	return err;
	557	out_unlock:
	558	unlock_page(page);
	559	goto out_put;
	560	}
	561
	562	/*
	563	* ext2_delete_entry deletes a directory entry by merging it with the
	564	* previous entry. Page is up-to-date. Releases the page.
	565	*/
	566	int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
	567	{
	568	struct address_space *mapping = page->mapping;
	569	struct inode *inode = mapping->host;
	570	char *kaddr = page_address(page);
	571	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
89910ccc JK	572	unsigned to = ((char *)dir - kaddr) +
89910ccc JK	573	ext2_rec_len_from_disk(dir->rec_len);
f34fb6ec	574	loff_t pos;
1da177e4 LT	575	ext2_dirent * pde = NULL;
	576	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
	577	int err;
	578
	579	while ((char)de < (char)dir) {
	580	if (de->rec_len == 0) {
605afd60	581	ext2_error(inode->i_sb, __func__,
1da177e4 LT	582	"zero-length directory entry");
	583	err = -EIO;
	584	goto out;
	585	}
	586	pde = de;
	587	de = ext2_next_entry(de);
	588	}
	589	if (pde)
	590	from = (char)pde - (char)page_address(page);
f34fb6ec	591	pos = page_offset(page) + from;
1da177e4	592	lock_page(page);
f34fb6ec NP	593	err = __ext2_write_begin(NULL, page->mapping, pos, to - from, 0,
f34fb6ec NP	594	&page, NULL);
309be53d	595	BUG_ON(err);
1da177e4	596	if (pde)
89910ccc	597	pde->rec_len = ext2_rec_len_to_disk(to - from);
1da177e4	598	dir->inode = 0;
f34fb6ec	599	err = ext2_commit_chunk(page, pos, to - from);
1da177e4 LT	600	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	601	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
	602	mark_inode_dirty(inode);
	603	out:
	604	ext2_put_page(page);
	605	return err;
	606	}
	607
	608	/*
	609	* Set the first fragment of directory.
	610	*/
	611	int ext2_make_empty(struct inode inode, struct inode parent)
	612	{
	613	struct address_space *mapping = inode->i_mapping;
	614	struct page *page = grab_cache_page(mapping, 0);
	615	unsigned chunk_size = ext2_chunk_size(inode);
	616	struct ext2_dir_entry_2 * de;
	617	int err;
	618	void *kaddr;
	619
	620	if (!page)
	621	return -ENOMEM;
f34fb6ec NP	622
	623	err = __ext2_write_begin(NULL, page->mapping, 0, chunk_size, 0,
	624	&page, NULL);
1da177e4 LT	625	if (err) {
	626	unlock_page(page);
	627	goto fail;
	628	}
	629	kaddr = kmap_atomic(page, KM_USER0);
7823c7c1	630	memset(kaddr, 0, chunk_size);
1da177e4 LT	631	de = (struct ext2_dir_entry_2 *)kaddr;
1da177e4 LT	632	de->name_len = 1;
89910ccc	633	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
1da177e4 LT	634	memcpy (de->name, ".\0\0", 4);
	635	de->inode = cpu_to_le32(inode->i_ino);
	636	ext2_set_de_type (de, inode);
	637
	638	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
	639	de->name_len = 2;
89910ccc	640	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
1da177e4 LT	641	de->inode = cpu_to_le32(parent->i_ino);
	642	memcpy (de->name, "..\0", 4);
	643	ext2_set_de_type (de, inode);
	644	kunmap_atomic(kaddr, KM_USER0);
	645	err = ext2_commit_chunk(page, 0, chunk_size);
	646	fail:
	647	page_cache_release(page);
	648	return err;
	649	}
	650
	651	/*
	652	* routine to check that the specified directory is empty (for rmdir)
	653	*/
	654	int ext2_empty_dir (struct inode * inode)
	655	{
	656	struct page *page = NULL;
	657	unsigned long i, npages = dir_pages(inode);
	658
	659	for (i = 0; i < npages; i++) {
	660	char *kaddr;
	661	ext2_dirent * de;
	662	page = ext2_get_page(inode, i);
	663
	664	if (IS_ERR(page))
	665	continue;
	666
	667	kaddr = page_address(page);
	668	de = (ext2_dirent *)kaddr;
	669	kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
	670
	671	while ((char *)de <= kaddr) {
	672	if (de->rec_len == 0) {
605afd60	673	ext2_error(inode->i_sb, __func__,
1da177e4 LT	674	"zero-length directory entry");
	675	printk("kaddr=%p, de=%p\n", kaddr, de);
	676	goto not_empty;
	677	}
	678	if (de->inode != 0) {
	679	/* check for . and .. */
	680	if (de->name[0] != '.')
	681	goto not_empty;
	682	if (de->name_len > 2)
	683	goto not_empty;
	684	if (de->name_len < 2) {
	685	if (de->inode !=
	686	cpu_to_le32(inode->i_ino))
	687	goto not_empty;
	688	} else if (de->name[1] != '.')
	689	goto not_empty;
	690	}
	691	de = ext2_next_entry(de);
	692	}
	693	ext2_put_page(page);
	694	}
	695	return 1;
	696
	697	not_empty:
	698	ext2_put_page(page);
	699	return 0;
	700	}
	701
4b6f5d20	702	const struct file_operations ext2_dir_operations = {
1da177e4 LT	703	.llseek = generic_file_llseek,
	704	.read = generic_read_dir,
	705	.readdir = ext2_readdir,
14f9f7b2	706	.unlocked_ioctl = ext2_ioctl,
e322ff07 DH	707	#ifdef CONFIG_COMPAT
	708	.compat_ioctl = ext2_compat_ioctl,
	709	#endif
1da177e4 LT	710	.fsync = ext2_sync_file,
1da177e4 LT	711	};