nilfs2: directory entry operations

This adds directory handling functions, most of which comes from the ext2
file system.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Yoshiji Amagai <amagai.yoshiji@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/nilfs2/dir.c

+/*
+ * dir.c - NILFS directory entry operations
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
+ */
+/*
+ *  linux/fs/ext2/dir.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * 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 (davem@caip.rutgers.edu), 1995
+ *
+ * All code that works with directory layout had been switched to pagecache
+ * and moved here. AV
+ */
+
+#include <linux/pagemap.h>
+#include <linux/smp_lock.h>
+#include "nilfs.h"
+#include "page.h"
+
+/*
+ * nilfs uses block-sized chunks. Arguably, sector-sized ones would be
+ * more robust, but we have what we have
+ */
+static inline unsigned nilfs_chunk_size(struct inode *inode)
+{
+	return inode->i_sb->s_blocksize;
+}
+
+static inline void nilfs_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 nilfs_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 nilfs_prepare_chunk_uninterruptible(struct page *page,
+					       struct address_space *mapping,
+					       unsigned from, unsigned to)
+{
+	loff_t pos = page_offset(page) + from;
+	return block_write_begin(NULL, mapping, pos, to - from,
+				 AOP_FLAG_UNINTERRUPTIBLE, &page,
+				 NULL, nilfs_get_block);
+}
+
+static int nilfs_prepare_chunk(struct page *page,
+			       struct address_space *mapping,
+			       unsigned from, unsigned to)
+{
+	loff_t pos = page_offset(page) + from;
+	return block_write_begin(NULL, mapping, pos, to - from, 0, &page,
+				 NULL, nilfs_get_block);
+}
+
+static int nilfs_commit_chunk(struct page *page,
+			      struct address_space *mapping,
+			      unsigned from, unsigned to)
+{
+	struct inode *dir = mapping->host;
+	struct nilfs_sb_info *sbi = NILFS_SB(dir->i_sb);
+	loff_t pos = page_offset(page) + from;
+	unsigned len = to - from;
+	unsigned nr_dirty, copied;
+	int err;
+
+	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
+	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
+	if (pos + copied > dir->i_size) {
+		i_size_write(dir, pos + copied);
+		mark_inode_dirty(dir);
+	}
+	if (IS_DIRSYNC(dir))
+		nilfs_set_transaction_flag(NILFS_TI_SYNC);
+	err = nilfs_set_file_dirty(sbi, dir, nr_dirty);
+	unlock_page(page);
+	return err;
+}
+
+static void nilfs_check_page(struct page *page)
+{
+	struct inode *dir = page->mapping->host;
+	struct super_block *sb = dir->i_sb;
+	unsigned chunk_size = nilfs_chunk_size(dir);
+	char *kaddr = page_address(page);
+	unsigned offs, rec_len;
+	unsigned limit = PAGE_CACHE_SIZE;
+	struct nilfs_dir_entry *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 - NILFS_DIR_REC_LEN(1); offs += rec_len) {
+		p = (struct nilfs_dir_entry *)(kaddr + offs);
+		rec_len = le16_to_cpu(p->rec_len);
+
+		if (rec_len < NILFS_DIR_REC_LEN(1))
+			goto Eshort;
+		if (rec_len & 3)
+			goto Ealign;
+		if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
+			goto Enamelen;
+		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
+			goto Espan;
+	}
+	if (offs != limit)
+		goto Eend;
+out:
+	SetPageChecked(page);
+	return;
+
+	/* Too bad, we had an error */
+
+Ebadsize:
+	nilfs_error(sb, "nilfs_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";
+bad_entry:
+	nilfs_error(sb, "nilfs_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) le64_to_cpu(p->inode),
+		    rec_len, p->name_len);
+	goto fail;
+Eend:
+	p = (struct nilfs_dir_entry *)(kaddr + offs);
+	nilfs_error(sb, "nilfs_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) le64_to_cpu(p->inode));
+fail:
+	SetPageChecked(page);
+	SetPageError(page);
+}
+
+static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
+{
+	struct address_space *mapping = dir->i_mapping;
+	struct page *page = read_cache_page(mapping, n,
+				(filler_t *)mapping->a_ops->readpage, NULL);
+	if (!IS_ERR(page)) {
+		wait_on_page_locked(page);
+		kmap(page);
+		if (!PageUptodate(page))
+			goto fail;
+		if (!PageChecked(page))
+			nilfs_check_page(page);
+		if (PageError(page))
+			goto fail;
+	}
+	return page;
+
+fail:
+	nilfs_put_page(page);
+	return ERR_PTR(-EIO);
+}
+
+/*
+ * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
+ *
+ * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
+ */
+static int
+nilfs_match(int len, const char * const name, struct nilfs_dir_entry *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 struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
+{
+	return (struct nilfs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
+}
+
+static unsigned char
+nilfs_filetype_table[NILFS_FT_MAX] = {
+	[NILFS_FT_UNKNOWN]	= DT_UNKNOWN,
+	[NILFS_FT_REG_FILE]	= DT_REG,
+	[NILFS_FT_DIR]		= DT_DIR,
+	[NILFS_FT_CHRDEV]	= DT_CHR,
+	[NILFS_FT_BLKDEV]	= DT_BLK,
+	[NILFS_FT_FIFO]		= DT_FIFO,
+	[NILFS_FT_SOCK]		= DT_SOCK,
+	[NILFS_FT_SYMLINK]	= DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char
+nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
+	[S_IFREG >> S_SHIFT]	= NILFS_FT_REG_FILE,
+	[S_IFDIR >> S_SHIFT]	= NILFS_FT_DIR,
+	[S_IFCHR >> S_SHIFT]	= NILFS_FT_CHRDEV,
+	[S_IFBLK >> S_SHIFT]	= NILFS_FT_BLKDEV,
+	[S_IFIFO >> S_SHIFT]	= NILFS_FT_FIFO,
+	[S_IFSOCK >> S_SHIFT]	= NILFS_FT_SOCK,
+	[S_IFLNK >> S_SHIFT]	= NILFS_FT_SYMLINK,
+};
+
+static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
+{
+	mode_t mode = inode->i_mode;
+
+	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
+}
+
+static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	loff_t pos = filp->f_pos;
+	struct inode *inode = filp->f_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 = ~(nilfs_chunk_size(inode)-1); */
+	unsigned char *types = NULL;
+	int ret;
+
+	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
+		goto success;
+
+	types = nilfs_filetype_table;
+
+	for ( ; n < npages; n++, offset = 0) {
+		char *kaddr, *limit;
+		struct nilfs_dir_entry *de;
+		struct page *page = nilfs_get_page(inode, n);
+
+		if (IS_ERR(page)) {
+			nilfs_error(sb, __func__, "bad page in #%lu",
+				    inode->i_ino);
+			filp->f_pos += PAGE_CACHE_SIZE - offset;
+			ret = -EIO;
+			goto done;
+		}
+		kaddr = page_address(page);
+		de = (struct nilfs_dir_entry *)(kaddr + offset);
+		limit = kaddr + nilfs_last_byte(inode, n) -
+			NILFS_DIR_REC_LEN(1);
+		for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
+			if (de->rec_len == 0) {
+				nilfs_error(sb, __func__,
+					    "zero-length directory entry");
+				ret = -EIO;
+				nilfs_put_page(page);
+				goto done;
+			}
+			if (de->inode) {
+				int over;
+				unsigned char d_type = DT_UNKNOWN;
+
+				if (types && de->file_type < NILFS_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,
+						le64_to_cpu(de->inode), d_type);
+				if (over) {
+					nilfs_put_page(page);
+					goto success;
+				}
+			}
+			filp->f_pos += le16_to_cpu(de->rec_len);
+		}
+		nilfs_put_page(page);
+	}
+
+success:
+	ret = 0;
+done:
+	return ret;
+}
+
+/*
+ *	nilfs_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 nilfs_dir_entry *
+nilfs_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 = NILFS_DIR_REC_LEN(namelen);
+	unsigned long start, n;
+	unsigned long npages = dir_pages(dir);
+	struct page *page = NULL;
+	struct nilfs_inode_info *ei = NILFS_I(dir);
+	struct nilfs_dir_entry *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 = nilfs_get_page(dir, n);
+		if (!IS_ERR(page)) {
+			kaddr = page_address(page);
+			de = (struct nilfs_dir_entry *)kaddr;
+			kaddr += nilfs_last_byte(dir, n) - reclen;
+			while ((char *) de <= kaddr) {
+				if (de->rec_len == 0) {
+					nilfs_error(dir->i_sb, __func__,
+						"zero-length directory entry");
+					nilfs_put_page(page);
+					goto out;
+				}
+				if (nilfs_match(namelen, name, de))
+					goto found;
+				de = nilfs_next_entry(de);
+			}
+			nilfs_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)))) {
+			nilfs_error(dir->i_sb, __func__,
+			       "dir %lu size %lld exceeds block cout %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 nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
+{
+	struct page *page = nilfs_get_page(dir, 0);
+	struct nilfs_dir_entry *de = NULL;
+
+	if (!IS_ERR(page)) {
+		de = nilfs_next_entry(
+			(struct nilfs_dir_entry *)page_address(page));
+		*p = page;
+	}
+	return de;
+}
+
+ino_t nilfs_inode_by_name(struct inode *dir, struct dentry *dentry)
+{
+	ino_t res = 0;
+	struct nilfs_dir_entry *de;
+	struct page *page;
+
+	de = nilfs_find_entry(dir, dentry, &page);
+	if (de) {
+		res = le64_to_cpu(de->inode);
+		kunmap(page);
+		page_cache_release(page);
+	}
+	return res;
+}
+
+/* Releases the page */
+void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
+		    struct page *page, struct inode *inode)
+{
+	unsigned from = (char *) de - (char *) page_address(page);
+	unsigned to = from + le16_to_cpu(de->rec_len);
+	struct address_space *mapping = page->mapping;
+	int err;
+
+	lock_page(page);
+	err = nilfs_prepare_chunk_uninterruptible(page, mapping, from, to);
+	BUG_ON(err);
+	de->inode = cpu_to_le64(inode->i_ino);
+	nilfs_set_de_type(de, inode);
+	err = nilfs_commit_chunk(page, mapping, from, to);
+	nilfs_put_page(page);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+/*	NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
+	mark_inode_dirty(dir);
+}
+
+/*
+ *	Parent is locked.
+ */
+int nilfs_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 = nilfs_chunk_size(dir);
+	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
+	unsigned short rec_len, name_len;
+	struct page *page = NULL;
+	struct nilfs_dir_entry *de;
+	unsigned long npages = dir_pages(dir);
+	unsigned long n;
+	char *kaddr;
+	unsigned from, to;
+	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 = nilfs_get_page(dir, n);
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto out;
+		lock_page(page);
+		kaddr = page_address(page);
+		dir_end = kaddr + nilfs_last_byte(dir, n);
+		de = (struct nilfs_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->rec_len = cpu_to_le16(chunk_size);
+				de->inode = 0;
+				goto got_it;
+			}
+			if (de->rec_len == 0) {
+				nilfs_error(dir->i_sb, __func__,
+					    "zero-length directory entry");
+				err = -EIO;
+				goto out_unlock;
+			}
+			err = -EEXIST;
+			if (nilfs_match(namelen, name, de))
+				goto out_unlock;
+			name_len = NILFS_DIR_REC_LEN(de->name_len);
+			rec_len = le16_to_cpu(de->rec_len);
+			if (!de->inode && rec_len >= reclen)
+				goto got_it;
+			if (rec_len >= name_len + reclen)
+				goto got_it;
+			de = (struct nilfs_dir_entry *)((char *)de + rec_len);
+		}
+		unlock_page(page);
+		nilfs_put_page(page);
+	}
+	BUG();
+	return -EINVAL;
+
+got_it:
+	from = (char *)de - (char *)page_address(page);
+	to = from + rec_len;
+	err = nilfs_prepare_chunk(page, page->mapping, from, to);
+	if (err)
+		goto out_unlock;
+	if (de->inode) {
+		struct nilfs_dir_entry *de1;
+
+		de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
+		de1->rec_len = cpu_to_le16(rec_len - name_len);
+		de->rec_len = cpu_to_le16(name_len);
+		de = de1;
+	}
+	de->name_len = namelen;
+	memcpy(de->name, name, namelen);
+	de->inode = cpu_to_le64(inode->i_ino);
+	nilfs_set_de_type(de, inode);
+	err = nilfs_commit_chunk(page, page->mapping, from, to);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+/*	NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
+	mark_inode_dirty(dir);
+	/* OFFSET_CACHE */
+out_put:
+	nilfs_put_page(page);
+out:
+	return err;
+out_unlock:
+	unlock_page(page);
+	goto out_put;
+}
+
+/*
+ * nilfs_delete_entry deletes a directory entry by merging it with the
+ * previous entry. Page is up-to-date. Releases the page.
+ */
+int nilfs_delete_entry(struct nilfs_dir_entry *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) & ~(nilfs_chunk_size(inode) - 1);
+	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
+	struct nilfs_dir_entry *pde = NULL;
+	struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
+	int err;
+
+	while ((char *)de < (char *)dir) {
+		if (de->rec_len == 0) {
+			nilfs_error(inode->i_sb, __func__,
+				    "zero-length directory entry");
+			err = -EIO;
+			goto out;
+		}
+		pde = de;
+		de = nilfs_next_entry(de);
+	}
+	if (pde)
+		from = (char *)pde - (char *)page_address(page);
+	lock_page(page);
+	err = nilfs_prepare_chunk(page, mapping, from, to);
+	BUG_ON(err);
+	if (pde)
+		pde->rec_len = cpu_to_le16(to - from);
+	dir->inode = 0;
+	err = nilfs_commit_chunk(page, mapping, from, to);
+	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+/*	NILFS_I(inode)->i_flags &= ~NILFS_BTREE_FL; */
+	mark_inode_dirty(inode);
+out:
+	nilfs_put_page(page);
+	return err;
+}
+
+/*
+ * Set the first fragment of directory.
+ */
+int nilfs_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 = nilfs_chunk_size(inode);
+	struct nilfs_dir_entry *de;
+	int err;
+	void *kaddr;
+
+	if (!page)
+		return -ENOMEM;
+
+	err = nilfs_prepare_chunk(page, mapping, 0, chunk_size);
+	if (unlikely(err)) {
+		unlock_page(page);
+		goto fail;
+	}
+	kaddr = kmap_atomic(page, KM_USER0);
+	memset(kaddr, 0, chunk_size);
+	de = (struct nilfs_dir_entry *)kaddr;
+	de->name_len = 1;
+	de->rec_len = cpu_to_le16(NILFS_DIR_REC_LEN(1));
+	memcpy(de->name, ".\0\0", 4);
+	de->inode = cpu_to_le64(inode->i_ino);
+	nilfs_set_de_type(de, inode);
+
+	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
+	de->name_len = 2;
+	de->rec_len = cpu_to_le16(chunk_size - NILFS_DIR_REC_LEN(1));
+	de->inode = cpu_to_le64(parent->i_ino);
+	memcpy(de->name, "..\0", 4);
+	nilfs_set_de_type(de, inode);
+	kunmap_atomic(kaddr, KM_USER0);
+	err = nilfs_commit_chunk(page, mapping, 0, chunk_size);
+fail:
+	page_cache_release(page);
+	return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int nilfs_empty_dir(struct inode *inode)
+{
+	struct page *page = NULL;
+	unsigned long i, npages = dir_pages(inode);
+
+	for (i = 0; i < npages; i++) {
+		char *kaddr;
+		struct nilfs_dir_entry *de;
+
+		page = nilfs_get_page(inode, i);
+		if (IS_ERR(page))
+			continue;
+
+		kaddr = page_address(page);
+		de = (struct nilfs_dir_entry *)kaddr;
+		kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
+
+		while ((char *)de <= kaddr) {
+			if (de->rec_len == 0) {
+				nilfs_error(inode->i_sb, __func__,
+					    "zero-length directory entry "
+					    "(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_le64(inode->i_ino))
+						goto not_empty;
+				} else if (de->name[1] != '.')
+					goto not_empty;
+			}
+			de = nilfs_next_entry(de);
+		}
+		nilfs_put_page(page);
+	}
+	return 1;
+
+not_empty:
+	nilfs_put_page(page);
+	return 0;
+}
+
+struct file_operations nilfs_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.readdir	= nilfs_readdir,
+	.ioctl		= nilfs_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= nilfs_compat_ioctl,
+#endif	/* CONFIG_COMPAT */
+	.fsync		= nilfs_sync_file,
+
+};