[linux-2.6-block.git] / 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 "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(struct page *page, unsigned from, unsigned to)
{
	loff_t pos = page_offset(page) + from;
	return __block_write_begin(page, pos, to - from, nilfs_get_block);
}

static void nilfs_commit_chunk(struct page *page,
			       struct address_space *mapping,
			       unsigned from, unsigned to)
{
	struct inode *dir = mapping->host;
	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);
	if (IS_DIRSYNC(dir))
		nilfs_set_transaction_flag(NILFS_TI_SYNC);
	err = nilfs_set_file_dirty(dir, nr_dirty);
	WARN_ON(err); /* do not happen */
	unlock_page(page);
}

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 = nilfs_rec_len_from_disk(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_mapping_page(mapping, n, NULL);

	if (!IS_ERR(page)) {
		kmap(page);
		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 unsigned char *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 +
					  nilfs_rec_len_from_disk(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)
{
	umode_t mode = inode->i_mode;

	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
}

static int nilfs_readdir(struct file *file, struct dir_context *ctx)
{
	loff_t pos = ctx->pos;
	struct inode *inode = file_inode(file);
	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); */

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

	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);
			ctx->pos += PAGE_CACHE_SIZE - offset;
			return -EIO;
		}
		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");
				nilfs_put_page(page);
				return -EIO;
			}
			if (de->inode) {
				unsigned char t;

				if (de->file_type < NILFS_FT_MAX)
					t = nilfs_filetype_table[de->file_type];
				else
					t = DT_UNKNOWN;

				if (!dir_emit(ctx, de->name, de->name_len,
						le64_to_cpu(de->inode), t)) {
					nilfs_put_page(page);
					return 0;
				}
			}
			ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
		}
		nilfs_put_page(page);
	}
	return 0;
}

/*
 *	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, const struct qstr *qstr,
		 struct page **res_page)
{
	const unsigned char *name = qstr->name;
	int namelen = qstr->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 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 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, const struct qstr *qstr)
{
	ino_t res = 0;
	struct nilfs_dir_entry *de;
	struct page *page;

	de = nilfs_find_entry(dir, qstr, &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 + nilfs_rec_len_from_disk(de->rec_len);
	struct address_space *mapping = page->mapping;
	int err;

	lock_page(page);
	err = nilfs_prepare_chunk(page, from, to);
	BUG_ON(err);
	de->inode = cpu_to_le64(inode->i_ino);
	nilfs_set_de_type(de, inode);
	nilfs_commit_chunk(page, mapping, from, to);
	nilfs_put_page(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
}

/*
 *	Parent is locked.
 */
int nilfs_add_link(struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = d_inode(dentry->d_parent);
	const unsigned 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 = nilfs_rec_len_to_disk(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 = nilfs_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 = (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, 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 = nilfs_rec_len_to_disk(rec_len - name_len);
		de->rec_len = nilfs_rec_len_to_disk(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);
	nilfs_commit_chunk(page, page->mapping, from, to);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	nilfs_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) +
		nilfs_rec_len_from_disk(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, from, to);
	BUG_ON(err);
	if (pde)
		pde->rec_len = nilfs_rec_len_to_disk(to - from);
	dir->inode = 0;
	nilfs_commit_chunk(page, mapping, from, to);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
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, 0, chunk_size);
	if (unlikely(err)) {
		unlock_page(page);
		goto fail;
	}
	kaddr = kmap_atomic(page);
	memset(kaddr, 0, chunk_size);
	de = (struct nilfs_dir_entry *)kaddr;
	de->name_len = 1;
	de->rec_len = nilfs_rec_len_to_disk(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 = nilfs_rec_len_to_disk(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);
	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;
}

const struct file_operations nilfs_dir_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.iterate	= nilfs_readdir,
	.unlocked_ioctl	= nilfs_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= nilfs_compat_ioctl,
#endif	/* CONFIG_COMPAT */
	.fsync		= nilfs_sync_file,

};
Commit	Line	Data
2ba466d7 YA	1	/*
	2	* dir.c - NILFS directory entry operations
	3	*
	4	* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	19	*
	20	* Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
	21	*/
	22	/*
	23	* linux/fs/ext2/dir.c
	24	*
	25	* Copyright (C) 1992, 1993, 1994, 1995
	26	* Remy Card (card@masi.ibp.fr)
	27	* Laboratoire MASI - Institut Blaise Pascal
	28	* Universite Pierre et Marie Curie (Paris VI)
	29	*
	30	* from
	31	*
	32	* linux/fs/minix/dir.c
	33	*
	34	* Copyright (C) 1991, 1992 Linus Torvalds
	35	*
	36	* ext2 directory handling functions
	37	*
	38	* Big-endian to little-endian byte-swapping/bitmaps by
	39	* David S. Miller (davem@caip.rutgers.edu), 1995
	40	*
	41	* All code that works with directory layout had been switched to pagecache
	42	* and moved here. AV
	43	*/
	44
	45	#include <linux/pagemap.h>
2ba466d7 YA	46	#include "nilfs.h"
	47	#include "page.h"
	48
	49	/*
	50	* nilfs uses block-sized chunks. Arguably, sector-sized ones would be
	51	* more robust, but we have what we have
	52	*/
	53	static inline unsigned nilfs_chunk_size(struct inode *inode)
	54	{
	55	return inode->i_sb->s_blocksize;
	56	}
	57
	58	static inline void nilfs_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 nilfs_last_byte(struct inode *inode, unsigned long page_nr)
	74	{
	75	unsigned last_byte = inode->i_size;
	76
	77	last_byte -= page_nr << PAGE_CACHE_SHIFT;
	78	if (last_byte > PAGE_CACHE_SIZE)
	79	last_byte = PAGE_CACHE_SIZE;
	80	return last_byte;
	81	}
	82
f4e420dc	83	static int nilfs_prepare_chunk(struct page *page, unsigned from, unsigned to)
2ba466d7 YA	84	{
2ba466d7 YA	85	loff_t pos = page_offset(page) + from;
6e1db88d	86	return __block_write_begin(page, pos, to - from, nilfs_get_block);
2ba466d7 YA	87	}
2ba466d7 YA	88
2093abf9 JS	89	static void nilfs_commit_chunk(struct page *page,
	90	struct address_space *mapping,
	91	unsigned from, unsigned to)
2ba466d7 YA	92	{
2ba466d7 YA	93	struct inode *dir = mapping->host;
2ba466d7 YA	94	loff_t pos = page_offset(page) + from;
	95	unsigned len = to - from;
	96	unsigned nr_dirty, copied;
	97	int err;
	98
	99	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
	100	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
58d55471	101	if (pos + copied > dir->i_size)
2ba466d7	102	i_size_write(dir, pos + copied);
2ba466d7 YA	103	if (IS_DIRSYNC(dir))
2ba466d7 YA	104	nilfs_set_transaction_flag(NILFS_TI_SYNC);
bcbc8c64	105	err = nilfs_set_file_dirty(dir, nr_dirty);
2093abf9	106	WARN_ON(err); /* do not happen */
2ba466d7	107	unlock_page(page);
2ba466d7 YA	108	}
	109
	110	static void nilfs_check_page(struct page *page)
	111	{
	112	struct inode *dir = page->mapping->host;
	113	struct super_block *sb = dir->i_sb;
	114	unsigned chunk_size = nilfs_chunk_size(dir);
	115	char *kaddr = page_address(page);
	116	unsigned offs, rec_len;
	117	unsigned limit = PAGE_CACHE_SIZE;
	118	struct nilfs_dir_entry *p;
	119	char *error;
	120
	121	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
	122	limit = dir->i_size & ~PAGE_CACHE_MASK;
	123	if (limit & (chunk_size - 1))
	124	goto Ebadsize;
	125	if (!limit)
	126	goto out;
	127	}
	128	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
	129	p = (struct nilfs_dir_entry *)(kaddr + offs);
6cda9fa2	130	rec_len = nilfs_rec_len_from_disk(p->rec_len);
2ba466d7 YA	131
	132	if (rec_len < NILFS_DIR_REC_LEN(1))
	133	goto Eshort;
	134	if (rec_len & 3)
	135	goto Ealign;
	136	if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
	137	goto Enamelen;
	138	if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
	139	goto Espan;
	140	}
	141	if (offs != limit)
	142	goto Eend;
	143	out:
	144	SetPageChecked(page);
	145	return;
	146
	147	/* Too bad, we had an error */
	148
	149	Ebadsize:
	150	nilfs_error(sb, "nilfs_check_page",
	151	"size of directory #%lu is not a multiple of chunk size",
	152	dir->i_ino
	153	);
	154	goto fail;
	155	Eshort:
	156	error = "rec_len is smaller than minimal";
	157	goto bad_entry;
	158	Ealign:
	159	error = "unaligned directory entry";
	160	goto bad_entry;
	161	Enamelen:
	162	error = "rec_len is too small for name_len";
	163	goto bad_entry;
	164	Espan:
	165	error = "directory entry across blocks";
	166	bad_entry:
	167	nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
	168	"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
	169	dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
	170	(unsigned long) le64_to_cpu(p->inode),
	171	rec_len, p->name_len);
	172	goto fail;
	173	Eend:
	174	p = (struct nilfs_dir_entry *)(kaddr + offs);
	175	nilfs_error(sb, "nilfs_check_page",
	176	"entry in directory #%lu spans the page boundary"
	177	"offset=%lu, inode=%lu",
	178	dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
	179	(unsigned long) le64_to_cpu(p->inode));
	180	fail:
	181	SetPageChecked(page);
	182	SetPageError(page);
	183	}
	184
	185	static struct page nilfs_get_page(struct inode dir, unsigned long n)
	186	{
	187	struct address_space *mapping = dir->i_mapping;
c28e69d9 RK	188	struct page *page = read_mapping_page(mapping, n, NULL);
c28e69d9 RK	189
2ba466d7	190	if (!IS_ERR(page)) {
2ba466d7	191	kmap(page);
2ba466d7 YA	192	if (!PageChecked(page))
	193	nilfs_check_page(page);
	194	if (PageError(page))
	195	goto fail;
	196	}
	197	return page;
	198
	199	fail:
	200	nilfs_put_page(page);
	201	return ERR_PTR(-EIO);
	202	}
	203
	204	/*
	205	* NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
	206	*
	207	* len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
	208	*/
	209	static int
072f98b4	210	nilfs_match(int len, const unsigned char name, struct nilfs_dir_entry de)
2ba466d7 YA	211	{
	212	if (len != de->name_len)
	213	return 0;
	214	if (!de->inode)
	215	return 0;
	216	return !memcmp(name, de->name, len);
	217	}
	218
	219	/*
	220	* p is at least 6 bytes before the end of page
	221	*/
	222	static struct nilfs_dir_entry nilfs_next_entry(struct nilfs_dir_entry p)
	223	{
6cda9fa2 RK	224	return (struct nilfs_dir_entry )((char )p +
6cda9fa2 RK	225	nilfs_rec_len_from_disk(p->rec_len));
2ba466d7 YA	226	}
	227
	228	static unsigned char
	229	nilfs_filetype_table[NILFS_FT_MAX] = {
	230	[NILFS_FT_UNKNOWN] = DT_UNKNOWN,
	231	[NILFS_FT_REG_FILE] = DT_REG,
	232	[NILFS_FT_DIR] = DT_DIR,
	233	[NILFS_FT_CHRDEV] = DT_CHR,
	234	[NILFS_FT_BLKDEV] = DT_BLK,
	235	[NILFS_FT_FIFO] = DT_FIFO,
	236	[NILFS_FT_SOCK] = DT_SOCK,
	237	[NILFS_FT_SYMLINK] = DT_LNK,
	238	};
	239
	240	#define S_SHIFT 12
	241	static unsigned char
	242	nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
	243	[S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
	244	[S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
	245	[S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
	246	[S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
	247	[S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
	248	[S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
	249	[S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
	250	};
	251
	252	static void nilfs_set_de_type(struct nilfs_dir_entry de, struct inode inode)
	253	{
c6e49e3f	254	umode_t mode = inode->i_mode;
2ba466d7 YA	255
	256	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	257	}
	258
1616abe8	259	static int nilfs_readdir(struct file file, struct dir_context ctx)
2ba466d7	260	{
1616abe8 AV	261	loff_t pos = ctx->pos;
1616abe8 AV	262	struct inode *inode = file_inode(file);
2ba466d7 YA	263	struct super_block *sb = inode->i_sb;
	264	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	265	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	266	unsigned long npages = dir_pages(inode);
	267	/* unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
2ba466d7 YA	268
2ba466d7 YA	269	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
1616abe8	270	return 0;
2ba466d7 YA	271
	272	for ( ; n < npages; n++, offset = 0) {
	273	char kaddr, limit;
	274	struct nilfs_dir_entry *de;
	275	struct page *page = nilfs_get_page(inode, n);
	276
	277	if (IS_ERR(page)) {
	278	nilfs_error(sb, __func__, "bad page in #%lu",
	279	inode->i_ino);
1616abe8 AV	280	ctx->pos += PAGE_CACHE_SIZE - offset;
1616abe8 AV	281	return -EIO;
2ba466d7 YA	282	}
	283	kaddr = page_address(page);
	284	de = (struct nilfs_dir_entry *)(kaddr + offset);
	285	limit = kaddr + nilfs_last_byte(inode, n) -
	286	NILFS_DIR_REC_LEN(1);
	287	for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
	288	if (de->rec_len == 0) {
	289	nilfs_error(sb, __func__,
	290	"zero-length directory entry");
2ba466d7	291	nilfs_put_page(page);
1616abe8	292	return -EIO;
2ba466d7 YA	293	}
2ba466d7 YA	294	if (de->inode) {
1616abe8	295	unsigned char t;
2ba466d7	296
1616abe8 AV	297	if (de->file_type < NILFS_FT_MAX)
	298	t = nilfs_filetype_table[de->file_type];
	299	else
	300	t = DT_UNKNOWN;
2ba466d7	301
1616abe8 AV	302	if (!dir_emit(ctx, de->name, de->name_len,
1616abe8 AV	303	le64_to_cpu(de->inode), t)) {
2ba466d7	304	nilfs_put_page(page);
1616abe8	305	return 0;
2ba466d7 YA	306	}
2ba466d7 YA	307	}
1616abe8	308	ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	309	}
	310	nilfs_put_page(page);
	311	}
1616abe8	312	return 0;
2ba466d7 YA	313	}
	314
	315	/*
	316	* nilfs_find_entry()
	317	*
	318	* finds an entry in the specified directory with the wanted name. It
	319	* returns the page in which the entry was found, and the entry itself
	320	* (as a parameter - res_dir). Page is returned mapped and unlocked.
	321	* Entry is guaranteed to be valid.
	322	*/
	323	struct nilfs_dir_entry *
0319003d	324	nilfs_find_entry(struct inode dir, const struct qstr qstr,
2ba466d7 YA	325	struct page **res_page)
2ba466d7 YA	326	{
0319003d AV	327	const unsigned char *name = qstr->name;
0319003d AV	328	int namelen = qstr->len;
2ba466d7 YA	329	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
	330	unsigned long start, n;
	331	unsigned long npages = dir_pages(dir);
	332	struct page *page = NULL;
	333	struct nilfs_inode_info *ei = NILFS_I(dir);
	334	struct nilfs_dir_entry *de;
	335
	336	if (npages == 0)
	337	goto out;
	338
	339	/* OFFSET_CACHE */
	340	*res_page = NULL;
	341
	342	start = ei->i_dir_start_lookup;
	343	if (start >= npages)
	344	start = 0;
	345	n = start;
	346	do {
	347	char *kaddr;
	348	page = nilfs_get_page(dir, n);
	349	if (!IS_ERR(page)) {
	350	kaddr = page_address(page);
	351	de = (struct nilfs_dir_entry *)kaddr;
	352	kaddr += nilfs_last_byte(dir, n) - reclen;
	353	while ((char *) de <= kaddr) {
	354	if (de->rec_len == 0) {
	355	nilfs_error(dir->i_sb, __func__,
	356	"zero-length directory entry");
	357	nilfs_put_page(page);
	358	goto out;
	359	}
	360	if (nilfs_match(namelen, name, de))
	361	goto found;
	362	de = nilfs_next_entry(de);
	363	}
	364	nilfs_put_page(page);
	365	}
	366	if (++n >= npages)
	367	n = 0;
	368	/* next page is past the blocks we've got */
	369	if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
	370	nilfs_error(dir->i_sb, __func__,
1621562b	371	"dir %lu size %lld exceeds block count %llu",
2ba466d7 YA	372	dir->i_ino, dir->i_size,
	373	(unsigned long long)dir->i_blocks);
	374	goto out;
	375	}
	376	} while (n != start);
	377	out:
	378	return NULL;
	379
	380	found:
	381	*res_page = page;
	382	ei->i_dir_start_lookup = n;
	383	return de;
	384	}
	385
	386	struct nilfs_dir_entry nilfs_dotdot(struct inode dir, struct page **p)
	387	{
	388	struct page *page = nilfs_get_page(dir, 0);
	389	struct nilfs_dir_entry *de = NULL;
	390
	391	if (!IS_ERR(page)) {
	392	de = nilfs_next_entry(
	393	(struct nilfs_dir_entry *)page_address(page));
	394	*p = page;
	395	}
	396	return de;
	397	}
	398
0319003d	399	ino_t nilfs_inode_by_name(struct inode dir, const struct qstr qstr)
2ba466d7 YA	400	{
	401	ino_t res = 0;
	402	struct nilfs_dir_entry *de;
	403	struct page *page;
	404
0319003d	405	de = nilfs_find_entry(dir, qstr, &page);
2ba466d7 YA	406	if (de) {
	407	res = le64_to_cpu(de->inode);
	408	kunmap(page);
	409	page_cache_release(page);
	410	}
	411	return res;
	412	}
	413
	414	/* Releases the page */
	415	void nilfs_set_link(struct inode dir, struct nilfs_dir_entry de,
	416	struct page page, struct inode inode)
	417	{
	418	unsigned from = (char ) de - (char ) page_address(page);
6cda9fa2	419	unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	420	struct address_space *mapping = page->mapping;
	421	int err;
	422
	423	lock_page(page);
f4e420dc	424	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	425	BUG_ON(err);
	426	de->inode = cpu_to_le64(inode->i_ino);
	427	nilfs_set_de_type(de, inode);
2093abf9	428	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7 YA	429	nilfs_put_page(page);
2ba466d7 YA	430	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
2ba466d7 YA	431	}
	432
	433	/*
	434	* Parent is locked.
	435	*/
	436	int nilfs_add_link(struct dentry dentry, struct inode inode)
	437	{
2b0143b5	438	struct inode *dir = d_inode(dentry->d_parent);
072f98b4	439	const unsigned char *name = dentry->d_name.name;
2ba466d7 YA	440	int namelen = dentry->d_name.len;
	441	unsigned chunk_size = nilfs_chunk_size(dir);
	442	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
	443	unsigned short rec_len, name_len;
	444	struct page *page = NULL;
	445	struct nilfs_dir_entry *de;
	446	unsigned long npages = dir_pages(dir);
	447	unsigned long n;
	448	char *kaddr;
	449	unsigned from, to;
	450	int err;
	451
	452	/*
	453	* We take care of directory expansion in the same loop.
	454	* This code plays outside i_size, so it locks the page
	455	* to protect that region.
	456	*/
	457	for (n = 0; n <= npages; n++) {
	458	char *dir_end;
	459
	460	page = nilfs_get_page(dir, n);
	461	err = PTR_ERR(page);
	462	if (IS_ERR(page))
	463	goto out;
	464	lock_page(page);
	465	kaddr = page_address(page);
	466	dir_end = kaddr + nilfs_last_byte(dir, n);
	467	de = (struct nilfs_dir_entry *)kaddr;
	468	kaddr += PAGE_CACHE_SIZE - reclen;
	469	while ((char *)de <= kaddr) {
	470	if ((char *)de == dir_end) {
	471	/* We hit i_size */
	472	name_len = 0;
	473	rec_len = chunk_size;
6cda9fa2	474	de->rec_len = nilfs_rec_len_to_disk(chunk_size);
2ba466d7 YA	475	de->inode = 0;
	476	goto got_it;
	477	}
	478	if (de->rec_len == 0) {
	479	nilfs_error(dir->i_sb, __func__,
	480	"zero-length directory entry");
	481	err = -EIO;
	482	goto out_unlock;
	483	}
	484	err = -EEXIST;
	485	if (nilfs_match(namelen, name, de))
	486	goto out_unlock;
	487	name_len = NILFS_DIR_REC_LEN(de->name_len);
6cda9fa2	488	rec_len = nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	489	if (!de->inode && rec_len >= reclen)
	490	goto got_it;
	491	if (rec_len >= name_len + reclen)
	492	goto got_it;
	493	de = (struct nilfs_dir_entry )((char )de + rec_len);
	494	}
	495	unlock_page(page);
	496	nilfs_put_page(page);
	497	}
	498	BUG();
	499	return -EINVAL;
	500
	501	got_it:
	502	from = (char )de - (char )page_address(page);
	503	to = from + rec_len;
f4e420dc	504	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	505	if (err)
	506	goto out_unlock;
	507	if (de->inode) {
	508	struct nilfs_dir_entry *de1;
	509
	510	de1 = (struct nilfs_dir_entry )((char )de + name_len);
6cda9fa2 RK	511	de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
6cda9fa2 RK	512	de->rec_len = nilfs_rec_len_to_disk(name_len);
2ba466d7 YA	513	de = de1;
	514	}
	515	de->name_len = namelen;
	516	memcpy(de->name, name, namelen);
	517	de->inode = cpu_to_le64(inode->i_ino);
	518	nilfs_set_de_type(de, inode);
2093abf9	519	nilfs_commit_chunk(page, page->mapping, from, to);
2ba466d7	520	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
abdb318b	521	nilfs_mark_inode_dirty(dir);
2ba466d7 YA	522	/* OFFSET_CACHE */
	523	out_put:
	524	nilfs_put_page(page);
	525	out:
	526	return err;
	527	out_unlock:
	528	unlock_page(page);
	529	goto out_put;
	530	}
	531
	532	/*
	533	* nilfs_delete_entry deletes a directory entry by merging it with the
	534	* previous entry. Page is up-to-date. Releases the page.
	535	*/
	536	int nilfs_delete_entry(struct nilfs_dir_entry dir, struct page page)
	537	{
	538	struct address_space *mapping = page->mapping;
	539	struct inode *inode = mapping->host;
	540	char *kaddr = page_address(page);
	541	unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
6cda9fa2 RK	542	unsigned to = ((char *)dir - kaddr) +
6cda9fa2 RK	543	nilfs_rec_len_from_disk(dir->rec_len);
2ba466d7 YA	544	struct nilfs_dir_entry *pde = NULL;
	545	struct nilfs_dir_entry de = (struct nilfs_dir_entry )(kaddr + from);
	546	int err;
	547
	548	while ((char )de < (char )dir) {
	549	if (de->rec_len == 0) {
	550	nilfs_error(inode->i_sb, __func__,
	551	"zero-length directory entry");
	552	err = -EIO;
	553	goto out;
	554	}
	555	pde = de;
	556	de = nilfs_next_entry(de);
	557	}
	558	if (pde)
	559	from = (char )pde - (char )page_address(page);
	560	lock_page(page);
f4e420dc	561	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	562	BUG_ON(err);
2ba466d7 YA	563	if (pde)
6cda9fa2	564	pde->rec_len = nilfs_rec_len_to_disk(to - from);
2ba466d7	565	dir->inode = 0;
2093abf9	566	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7	567	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
2ba466d7 YA	568	out:
	569	nilfs_put_page(page);
	570	return err;
	571	}
	572
	573	/*
	574	* Set the first fragment of directory.
	575	*/
	576	int nilfs_make_empty(struct inode inode, struct inode parent)
	577	{
	578	struct address_space *mapping = inode->i_mapping;
	579	struct page *page = grab_cache_page(mapping, 0);
	580	unsigned chunk_size = nilfs_chunk_size(inode);
	581	struct nilfs_dir_entry *de;
	582	int err;
	583	void *kaddr;
	584
	585	if (!page)
	586	return -ENOMEM;
	587
f4e420dc	588	err = nilfs_prepare_chunk(page, 0, chunk_size);
2ba466d7 YA	589	if (unlikely(err)) {
	590	unlock_page(page);
	591	goto fail;
	592	}
7b9c0976	593	kaddr = kmap_atomic(page);
2ba466d7 YA	594	memset(kaddr, 0, chunk_size);
	595	de = (struct nilfs_dir_entry *)kaddr;
	596	de->name_len = 1;
6cda9fa2	597	de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
2ba466d7 YA	598	memcpy(de->name, ".\0\0", 4);
	599	de->inode = cpu_to_le64(inode->i_ino);
	600	nilfs_set_de_type(de, inode);
	601
	602	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
	603	de->name_len = 2;
6cda9fa2	604	de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
2ba466d7 YA	605	de->inode = cpu_to_le64(parent->i_ino);
	606	memcpy(de->name, "..\0", 4);
	607	nilfs_set_de_type(de, inode);
7b9c0976	608	kunmap_atomic(kaddr);
2093abf9	609	nilfs_commit_chunk(page, mapping, 0, chunk_size);
2ba466d7 YA	610	fail:
	611	page_cache_release(page);
	612	return err;
	613	}
	614
	615	/*
	616	* routine to check that the specified directory is empty (for rmdir)
	617	*/
	618	int nilfs_empty_dir(struct inode *inode)
	619	{
	620	struct page *page = NULL;
	621	unsigned long i, npages = dir_pages(inode);
	622
	623	for (i = 0; i < npages; i++) {
	624	char *kaddr;
	625	struct nilfs_dir_entry *de;
	626
	627	page = nilfs_get_page(inode, i);
	628	if (IS_ERR(page))
	629	continue;
	630
	631	kaddr = page_address(page);
	632	de = (struct nilfs_dir_entry *)kaddr;
	633	kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
	634
	635	while ((char *)de <= kaddr) {
	636	if (de->rec_len == 0) {
	637	nilfs_error(inode->i_sb, __func__,
	638	"zero-length directory entry "
	639	"(kaddr=%p, de=%p)\n", kaddr, de);
	640	goto not_empty;
	641	}
	642	if (de->inode != 0) {
	643	/* check for . and .. */
	644	if (de->name[0] != '.')
	645	goto not_empty;
	646	if (de->name_len > 2)
	647	goto not_empty;
	648	if (de->name_len < 2) {
	649	if (de->inode !=
	650	cpu_to_le64(inode->i_ino))
	651	goto not_empty;
	652	} else if (de->name[1] != '.')
	653	goto not_empty;
	654	}
	655	de = nilfs_next_entry(de);
	656	}
	657	nilfs_put_page(page);
	658	}
	659	return 1;
	660
	661	not_empty:
	662	nilfs_put_page(page);
	663	return 0;
	664	}
	665
828c0950	666	const struct file_operations nilfs_dir_operations = {
2ba466d7 YA	667	.llseek = generic_file_llseek,
2ba466d7 YA	668	.read = generic_read_dir,
1616abe8	669	.iterate = nilfs_readdir,
7a946193	670	.unlocked_ioctl = nilfs_ioctl,
2ba466d7	671	#ifdef CONFIG_COMPAT
828b1c50	672	.compat_ioctl = nilfs_compat_ioctl,
2ba466d7 YA	673	#endif /* CONFIG_COMPAT */
	674	.fsync = nilfs_sync_file,
	675
	676	};