[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);
	put_page(page);
}

/*
 * 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_SHIFT;
	if (last_byte > PAGE_SIZE)
		last_byte = PAGE_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_SIZE;
	struct nilfs_dir_entry *p;
	char *error;

	if ((dir->i_size >> PAGE_SHIFT) == page->index) {
		limit = dir->i_size & ~PAGE_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_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_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_MASK;
	unsigned long n = pos >> PAGE_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_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_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);
		put_page(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_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:
	put_page(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);
09cbfeaf	61	put_page(page);
2ba466d7 YA	62	}
2ba466d7 YA	63
2ba466d7 YA	64	/*
	65	* Return the offset into page `page_nr' of the last valid
	66	* byte in that page, plus one.
	67	*/
	68	static unsigned nilfs_last_byte(struct inode *inode, unsigned long page_nr)
	69	{
	70	unsigned last_byte = inode->i_size;
	71
09cbfeaf KS	72	last_byte -= page_nr << PAGE_SHIFT;
	73	if (last_byte > PAGE_SIZE)
	74	last_byte = PAGE_SIZE;
2ba466d7 YA	75	return last_byte;
	76	}
	77
f4e420dc	78	static int nilfs_prepare_chunk(struct page *page, unsigned from, unsigned to)
2ba466d7 YA	79	{
2ba466d7 YA	80	loff_t pos = page_offset(page) + from;
6e1db88d	81	return __block_write_begin(page, pos, to - from, nilfs_get_block);
2ba466d7 YA	82	}
2ba466d7 YA	83
2093abf9 JS	84	static void nilfs_commit_chunk(struct page *page,
	85	struct address_space *mapping,
	86	unsigned from, unsigned to)
2ba466d7 YA	87	{
2ba466d7 YA	88	struct inode *dir = mapping->host;
2ba466d7 YA	89	loff_t pos = page_offset(page) + from;
	90	unsigned len = to - from;
	91	unsigned nr_dirty, copied;
	92	int err;
	93
	94	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
	95	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
58d55471	96	if (pos + copied > dir->i_size)
2ba466d7	97	i_size_write(dir, pos + copied);
2ba466d7 YA	98	if (IS_DIRSYNC(dir))
2ba466d7 YA	99	nilfs_set_transaction_flag(NILFS_TI_SYNC);
bcbc8c64	100	err = nilfs_set_file_dirty(dir, nr_dirty);
2093abf9	101	WARN_ON(err); /* do not happen */
2ba466d7	102	unlock_page(page);
2ba466d7 YA	103	}
	104
	105	static void nilfs_check_page(struct page *page)
	106	{
	107	struct inode *dir = page->mapping->host;
	108	struct super_block *sb = dir->i_sb;
	109	unsigned chunk_size = nilfs_chunk_size(dir);
	110	char *kaddr = page_address(page);
	111	unsigned offs, rec_len;
09cbfeaf	112	unsigned limit = PAGE_SIZE;
2ba466d7 YA	113	struct nilfs_dir_entry *p;
	114	char *error;
	115
09cbfeaf KS	116	if ((dir->i_size >> PAGE_SHIFT) == page->index) {
09cbfeaf KS	117	limit = dir->i_size & ~PAGE_MASK;
2ba466d7 YA	118	if (limit & (chunk_size - 1))
	119	goto Ebadsize;
	120	if (!limit)
	121	goto out;
	122	}
	123	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
	124	p = (struct nilfs_dir_entry *)(kaddr + offs);
6cda9fa2	125	rec_len = nilfs_rec_len_from_disk(p->rec_len);
2ba466d7 YA	126
	127	if (rec_len < NILFS_DIR_REC_LEN(1))
	128	goto Eshort;
	129	if (rec_len & 3)
	130	goto Ealign;
	131	if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
	132	goto Enamelen;
	133	if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
	134	goto Espan;
	135	}
	136	if (offs != limit)
	137	goto Eend;
	138	out:
	139	SetPageChecked(page);
	140	return;
	141
	142	/* Too bad, we had an error */
	143
	144	Ebadsize:
	145	nilfs_error(sb, "nilfs_check_page",
	146	"size of directory #%lu is not a multiple of chunk size",
	147	dir->i_ino
	148	);
	149	goto fail;
	150	Eshort:
	151	error = "rec_len is smaller than minimal";
	152	goto bad_entry;
	153	Ealign:
	154	error = "unaligned directory entry";
	155	goto bad_entry;
	156	Enamelen:
	157	error = "rec_len is too small for name_len";
	158	goto bad_entry;
	159	Espan:
	160	error = "directory entry across blocks";
	161	bad_entry:
	162	nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
	163	"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
09cbfeaf	164	dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
2ba466d7 YA	165	(unsigned long) le64_to_cpu(p->inode),
	166	rec_len, p->name_len);
	167	goto fail;
	168	Eend:
	169	p = (struct nilfs_dir_entry *)(kaddr + offs);
	170	nilfs_error(sb, "nilfs_check_page",
	171	"entry in directory #%lu spans the page boundary"
	172	"offset=%lu, inode=%lu",
09cbfeaf	173	dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
2ba466d7 YA	174	(unsigned long) le64_to_cpu(p->inode));
	175	fail:
	176	SetPageChecked(page);
	177	SetPageError(page);
	178	}
	179
	180	static struct page nilfs_get_page(struct inode dir, unsigned long n)
	181	{
	182	struct address_space *mapping = dir->i_mapping;
c28e69d9 RK	183	struct page *page = read_mapping_page(mapping, n, NULL);
c28e69d9 RK	184
2ba466d7	185	if (!IS_ERR(page)) {
2ba466d7	186	kmap(page);
2ba466d7 YA	187	if (!PageChecked(page))
	188	nilfs_check_page(page);
	189	if (PageError(page))
	190	goto fail;
	191	}
	192	return page;
	193
	194	fail:
	195	nilfs_put_page(page);
	196	return ERR_PTR(-EIO);
	197	}
	198
	199	/*
	200	* NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
	201	*
	202	* len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
	203	*/
	204	static int
072f98b4	205	nilfs_match(int len, const unsigned char name, struct nilfs_dir_entry de)
2ba466d7 YA	206	{
	207	if (len != de->name_len)
	208	return 0;
	209	if (!de->inode)
	210	return 0;
	211	return !memcmp(name, de->name, len);
	212	}
	213
	214	/*
	215	* p is at least 6 bytes before the end of page
	216	*/
	217	static struct nilfs_dir_entry nilfs_next_entry(struct nilfs_dir_entry p)
	218	{
6cda9fa2 RK	219	return (struct nilfs_dir_entry )((char )p +
6cda9fa2 RK	220	nilfs_rec_len_from_disk(p->rec_len));
2ba466d7 YA	221	}
	222
	223	static unsigned char
	224	nilfs_filetype_table[NILFS_FT_MAX] = {
	225	[NILFS_FT_UNKNOWN] = DT_UNKNOWN,
	226	[NILFS_FT_REG_FILE] = DT_REG,
	227	[NILFS_FT_DIR] = DT_DIR,
	228	[NILFS_FT_CHRDEV] = DT_CHR,
	229	[NILFS_FT_BLKDEV] = DT_BLK,
	230	[NILFS_FT_FIFO] = DT_FIFO,
	231	[NILFS_FT_SOCK] = DT_SOCK,
	232	[NILFS_FT_SYMLINK] = DT_LNK,
	233	};
	234
	235	#define S_SHIFT 12
	236	static unsigned char
	237	nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
	238	[S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
	239	[S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
	240	[S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
	241	[S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
	242	[S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
	243	[S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
	244	[S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
	245	};
	246
	247	static void nilfs_set_de_type(struct nilfs_dir_entry de, struct inode inode)
	248	{
c6e49e3f	249	umode_t mode = inode->i_mode;
2ba466d7 YA	250
	251	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	252	}
	253
1616abe8	254	static int nilfs_readdir(struct file file, struct dir_context ctx)
2ba466d7	255	{
1616abe8 AV	256	loff_t pos = ctx->pos;
1616abe8 AV	257	struct inode *inode = file_inode(file);
2ba466d7	258	struct super_block *sb = inode->i_sb;
09cbfeaf KS	259	unsigned int offset = pos & ~PAGE_MASK;
09cbfeaf KS	260	unsigned long n = pos >> PAGE_SHIFT;
2ba466d7 YA	261	unsigned long npages = dir_pages(inode);
2ba466d7 YA	262	/* unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
2ba466d7 YA	263
2ba466d7 YA	264	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
1616abe8	265	return 0;
2ba466d7 YA	266
	267	for ( ; n < npages; n++, offset = 0) {
	268	char kaddr, limit;
	269	struct nilfs_dir_entry *de;
	270	struct page *page = nilfs_get_page(inode, n);
	271
	272	if (IS_ERR(page)) {
	273	nilfs_error(sb, __func__, "bad page in #%lu",
	274	inode->i_ino);
09cbfeaf	275	ctx->pos += PAGE_SIZE - offset;
1616abe8	276	return -EIO;
2ba466d7 YA	277	}
	278	kaddr = page_address(page);
	279	de = (struct nilfs_dir_entry *)(kaddr + offset);
	280	limit = kaddr + nilfs_last_byte(inode, n) -
	281	NILFS_DIR_REC_LEN(1);
	282	for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
	283	if (de->rec_len == 0) {
	284	nilfs_error(sb, __func__,
	285	"zero-length directory entry");
2ba466d7	286	nilfs_put_page(page);
1616abe8	287	return -EIO;
2ba466d7 YA	288	}
2ba466d7 YA	289	if (de->inode) {
1616abe8	290	unsigned char t;
2ba466d7	291
1616abe8 AV	292	if (de->file_type < NILFS_FT_MAX)
	293	t = nilfs_filetype_table[de->file_type];
	294	else
	295	t = DT_UNKNOWN;
2ba466d7	296
1616abe8 AV	297	if (!dir_emit(ctx, de->name, de->name_len,
1616abe8 AV	298	le64_to_cpu(de->inode), t)) {
2ba466d7	299	nilfs_put_page(page);
1616abe8	300	return 0;
2ba466d7 YA	301	}
2ba466d7 YA	302	}
1616abe8	303	ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	304	}
	305	nilfs_put_page(page);
	306	}
1616abe8	307	return 0;
2ba466d7 YA	308	}
	309
	310	/*
	311	* nilfs_find_entry()
	312	*
	313	* finds an entry in the specified directory with the wanted name. It
	314	* returns the page in which the entry was found, and the entry itself
	315	* (as a parameter - res_dir). Page is returned mapped and unlocked.
	316	* Entry is guaranteed to be valid.
	317	*/
	318	struct nilfs_dir_entry *
0319003d	319	nilfs_find_entry(struct inode dir, const struct qstr qstr,
2ba466d7 YA	320	struct page **res_page)
2ba466d7 YA	321	{
0319003d AV	322	const unsigned char *name = qstr->name;
0319003d AV	323	int namelen = qstr->len;
2ba466d7 YA	324	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
	325	unsigned long start, n;
	326	unsigned long npages = dir_pages(dir);
	327	struct page *page = NULL;
	328	struct nilfs_inode_info *ei = NILFS_I(dir);
	329	struct nilfs_dir_entry *de;
	330
	331	if (npages == 0)
	332	goto out;
	333
	334	/* OFFSET_CACHE */
	335	*res_page = NULL;
	336
	337	start = ei->i_dir_start_lookup;
	338	if (start >= npages)
	339	start = 0;
	340	n = start;
	341	do {
	342	char *kaddr;
	343	page = nilfs_get_page(dir, n);
	344	if (!IS_ERR(page)) {
	345	kaddr = page_address(page);
	346	de = (struct nilfs_dir_entry *)kaddr;
	347	kaddr += nilfs_last_byte(dir, n) - reclen;
	348	while ((char *) de <= kaddr) {
	349	if (de->rec_len == 0) {
	350	nilfs_error(dir->i_sb, __func__,
	351	"zero-length directory entry");
	352	nilfs_put_page(page);
	353	goto out;
	354	}
	355	if (nilfs_match(namelen, name, de))
	356	goto found;
	357	de = nilfs_next_entry(de);
	358	}
	359	nilfs_put_page(page);
	360	}
	361	if (++n >= npages)
	362	n = 0;
	363	/* next page is past the blocks we've got */
09cbfeaf	364	if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
2ba466d7	365	nilfs_error(dir->i_sb, __func__,
1621562b	366	"dir %lu size %lld exceeds block count %llu",
2ba466d7 YA	367	dir->i_ino, dir->i_size,
	368	(unsigned long long)dir->i_blocks);
	369	goto out;
	370	}
	371	} while (n != start);
	372	out:
	373	return NULL;
	374
	375	found:
	376	*res_page = page;
	377	ei->i_dir_start_lookup = n;
	378	return de;
	379	}
	380
	381	struct nilfs_dir_entry nilfs_dotdot(struct inode dir, struct page **p)
	382	{
	383	struct page *page = nilfs_get_page(dir, 0);
	384	struct nilfs_dir_entry *de = NULL;
	385
	386	if (!IS_ERR(page)) {
	387	de = nilfs_next_entry(
	388	(struct nilfs_dir_entry *)page_address(page));
	389	*p = page;
	390	}
	391	return de;
	392	}
	393
0319003d	394	ino_t nilfs_inode_by_name(struct inode dir, const struct qstr qstr)
2ba466d7 YA	395	{
	396	ino_t res = 0;
	397	struct nilfs_dir_entry *de;
	398	struct page *page;
	399
0319003d	400	de = nilfs_find_entry(dir, qstr, &page);
2ba466d7 YA	401	if (de) {
	402	res = le64_to_cpu(de->inode);
	403	kunmap(page);
09cbfeaf	404	put_page(page);
2ba466d7 YA	405	}
	406	return res;
	407	}
	408
	409	/* Releases the page */
	410	void nilfs_set_link(struct inode dir, struct nilfs_dir_entry de,
	411	struct page page, struct inode inode)
	412	{
	413	unsigned from = (char ) de - (char ) page_address(page);
6cda9fa2	414	unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	415	struct address_space *mapping = page->mapping;
	416	int err;
	417
	418	lock_page(page);
f4e420dc	419	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	420	BUG_ON(err);
	421	de->inode = cpu_to_le64(inode->i_ino);
	422	nilfs_set_de_type(de, inode);
2093abf9	423	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7 YA	424	nilfs_put_page(page);
2ba466d7 YA	425	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
2ba466d7 YA	426	}
	427
	428	/*
	429	* Parent is locked.
	430	*/
	431	int nilfs_add_link(struct dentry dentry, struct inode inode)
	432	{
2b0143b5	433	struct inode *dir = d_inode(dentry->d_parent);
072f98b4	434	const unsigned char *name = dentry->d_name.name;
2ba466d7 YA	435	int namelen = dentry->d_name.len;
	436	unsigned chunk_size = nilfs_chunk_size(dir);
	437	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
	438	unsigned short rec_len, name_len;
	439	struct page *page = NULL;
	440	struct nilfs_dir_entry *de;
	441	unsigned long npages = dir_pages(dir);
	442	unsigned long n;
	443	char *kaddr;
	444	unsigned from, to;
	445	int err;
	446
	447	/*
	448	* We take care of directory expansion in the same loop.
	449	* This code plays outside i_size, so it locks the page
	450	* to protect that region.
	451	*/
	452	for (n = 0; n <= npages; n++) {
	453	char *dir_end;
	454
	455	page = nilfs_get_page(dir, n);
	456	err = PTR_ERR(page);
	457	if (IS_ERR(page))
	458	goto out;
	459	lock_page(page);
	460	kaddr = page_address(page);
	461	dir_end = kaddr + nilfs_last_byte(dir, n);
	462	de = (struct nilfs_dir_entry *)kaddr;
09cbfeaf	463	kaddr += PAGE_SIZE - reclen;
2ba466d7 YA	464	while ((char *)de <= kaddr) {
	465	if ((char *)de == dir_end) {
	466	/* We hit i_size */
	467	name_len = 0;
	468	rec_len = chunk_size;
6cda9fa2	469	de->rec_len = nilfs_rec_len_to_disk(chunk_size);
2ba466d7 YA	470	de->inode = 0;
	471	goto got_it;
	472	}
	473	if (de->rec_len == 0) {
	474	nilfs_error(dir->i_sb, __func__,
	475	"zero-length directory entry");
	476	err = -EIO;
	477	goto out_unlock;
	478	}
	479	err = -EEXIST;
	480	if (nilfs_match(namelen, name, de))
	481	goto out_unlock;
	482	name_len = NILFS_DIR_REC_LEN(de->name_len);
6cda9fa2	483	rec_len = nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	484	if (!de->inode && rec_len >= reclen)
	485	goto got_it;
	486	if (rec_len >= name_len + reclen)
	487	goto got_it;
	488	de = (struct nilfs_dir_entry )((char )de + rec_len);
	489	}
	490	unlock_page(page);
	491	nilfs_put_page(page);
	492	}
	493	BUG();
	494	return -EINVAL;
	495
	496	got_it:
	497	from = (char )de - (char )page_address(page);
	498	to = from + rec_len;
f4e420dc	499	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	500	if (err)
	501	goto out_unlock;
	502	if (de->inode) {
	503	struct nilfs_dir_entry *de1;
	504
	505	de1 = (struct nilfs_dir_entry )((char )de + name_len);
6cda9fa2 RK	506	de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
6cda9fa2 RK	507	de->rec_len = nilfs_rec_len_to_disk(name_len);
2ba466d7 YA	508	de = de1;
	509	}
	510	de->name_len = namelen;
	511	memcpy(de->name, name, namelen);
	512	de->inode = cpu_to_le64(inode->i_ino);
	513	nilfs_set_de_type(de, inode);
2093abf9	514	nilfs_commit_chunk(page, page->mapping, from, to);
2ba466d7	515	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
abdb318b	516	nilfs_mark_inode_dirty(dir);
2ba466d7 YA	517	/* OFFSET_CACHE */
	518	out_put:
	519	nilfs_put_page(page);
	520	out:
	521	return err;
	522	out_unlock:
	523	unlock_page(page);
	524	goto out_put;
	525	}
	526
	527	/*
	528	* nilfs_delete_entry deletes a directory entry by merging it with the
	529	* previous entry. Page is up-to-date. Releases the page.
	530	*/
	531	int nilfs_delete_entry(struct nilfs_dir_entry dir, struct page page)
	532	{
	533	struct address_space *mapping = page->mapping;
	534	struct inode *inode = mapping->host;
	535	char *kaddr = page_address(page);
	536	unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
6cda9fa2 RK	537	unsigned to = ((char *)dir - kaddr) +
6cda9fa2 RK	538	nilfs_rec_len_from_disk(dir->rec_len);
2ba466d7 YA	539	struct nilfs_dir_entry *pde = NULL;
	540	struct nilfs_dir_entry de = (struct nilfs_dir_entry )(kaddr + from);
	541	int err;
	542
	543	while ((char )de < (char )dir) {
	544	if (de->rec_len == 0) {
	545	nilfs_error(inode->i_sb, __func__,
	546	"zero-length directory entry");
	547	err = -EIO;
	548	goto out;
	549	}
	550	pde = de;
	551	de = nilfs_next_entry(de);
	552	}
	553	if (pde)
	554	from = (char )pde - (char )page_address(page);
	555	lock_page(page);
f4e420dc	556	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	557	BUG_ON(err);
2ba466d7 YA	558	if (pde)
6cda9fa2	559	pde->rec_len = nilfs_rec_len_to_disk(to - from);
2ba466d7	560	dir->inode = 0;
2093abf9	561	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7	562	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
2ba466d7 YA	563	out:
	564	nilfs_put_page(page);
	565	return err;
	566	}
	567
	568	/*
	569	* Set the first fragment of directory.
	570	*/
	571	int nilfs_make_empty(struct inode inode, struct inode parent)
	572	{
	573	struct address_space *mapping = inode->i_mapping;
	574	struct page *page = grab_cache_page(mapping, 0);
	575	unsigned chunk_size = nilfs_chunk_size(inode);
	576	struct nilfs_dir_entry *de;
	577	int err;
	578	void *kaddr;
	579
	580	if (!page)
	581	return -ENOMEM;
	582
f4e420dc	583	err = nilfs_prepare_chunk(page, 0, chunk_size);
2ba466d7 YA	584	if (unlikely(err)) {
	585	unlock_page(page);
	586	goto fail;
	587	}
7b9c0976	588	kaddr = kmap_atomic(page);
2ba466d7 YA	589	memset(kaddr, 0, chunk_size);
	590	de = (struct nilfs_dir_entry *)kaddr;
	591	de->name_len = 1;
6cda9fa2	592	de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
2ba466d7 YA	593	memcpy(de->name, ".\0\0", 4);
	594	de->inode = cpu_to_le64(inode->i_ino);
	595	nilfs_set_de_type(de, inode);
	596
	597	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
	598	de->name_len = 2;
6cda9fa2	599	de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
2ba466d7 YA	600	de->inode = cpu_to_le64(parent->i_ino);
	601	memcpy(de->name, "..\0", 4);
	602	nilfs_set_de_type(de, inode);
7b9c0976	603	kunmap_atomic(kaddr);
2093abf9	604	nilfs_commit_chunk(page, mapping, 0, chunk_size);
2ba466d7	605	fail:
09cbfeaf	606	put_page(page);
2ba466d7 YA	607	return err;
	608	}
	609
	610	/*
	611	* routine to check that the specified directory is empty (for rmdir)
	612	*/
	613	int nilfs_empty_dir(struct inode *inode)
	614	{
	615	struct page *page = NULL;
	616	unsigned long i, npages = dir_pages(inode);
	617
	618	for (i = 0; i < npages; i++) {
	619	char *kaddr;
	620	struct nilfs_dir_entry *de;
	621
	622	page = nilfs_get_page(inode, i);
	623	if (IS_ERR(page))
	624	continue;
	625
	626	kaddr = page_address(page);
	627	de = (struct nilfs_dir_entry *)kaddr;
	628	kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
	629
	630	while ((char *)de <= kaddr) {
	631	if (de->rec_len == 0) {
	632	nilfs_error(inode->i_sb, __func__,
	633	"zero-length directory entry "
	634	"(kaddr=%p, de=%p)\n", kaddr, de);
	635	goto not_empty;
	636	}
	637	if (de->inode != 0) {
	638	/* check for . and .. */
	639	if (de->name[0] != '.')
	640	goto not_empty;
	641	if (de->name_len > 2)
	642	goto not_empty;
	643	if (de->name_len < 2) {
	644	if (de->inode !=
	645	cpu_to_le64(inode->i_ino))
	646	goto not_empty;
	647	} else if (de->name[1] != '.')
	648	goto not_empty;
	649	}
	650	de = nilfs_next_entry(de);
	651	}
	652	nilfs_put_page(page);
	653	}
	654	return 1;
	655
	656	not_empty:
	657	nilfs_put_page(page);
	658	return 0;
	659	}
	660
828c0950	661	const struct file_operations nilfs_dir_operations = {
2ba466d7 YA	662	.llseek = generic_file_llseek,
2ba466d7 YA	663	.read = generic_read_dir,
1616abe8	664	.iterate = nilfs_readdir,
7a946193	665	.unlocked_ioctl = nilfs_ioctl,
2ba466d7	666	#ifdef CONFIG_COMPAT
828b1c50	667	.compat_ioctl = nilfs_compat_ioctl,
2ba466d7 YA	668	#endif /* CONFIG_COMPAT */
	669	.fsync = nilfs_sync_file,
	670
	671	};