[linux.git] / fs / nilfs2 / dir.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * dir.c - NILFS directory entry operations
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Modified for NILFS by Amagai Yoshiji.
 */
/*
 *  linux/fs/ext2/dir.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([email protected])
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext2 directory handling functions
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller ([email protected]), 1995
 *
 * All code that works with directory layout had been switched to pagecache
 * and moved here. AV
 */

#include <linux/pagemap.h>
#include "nilfs.h"
#include "page.h"

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

#if (PAGE_SIZE >= 65536)
	if (len == NILFS_MAX_REC_LEN)
		return 1 << 16;
#endif
	return len;
}

static inline __le16 nilfs_rec_len_to_disk(unsigned int len)
{
#if (PAGE_SIZE >= 65536)
	if (len == (1 << 16))
		return cpu_to_le16(NILFS_MAX_REC_LEN);

	BUG_ON(len > (1 << 16));
#endif
	return cpu_to_le16(len);
}

/*
 * nilfs uses block-sized chunks. Arguably, sector-sized ones would be
 * more robust, but we have what we have
 */
static inline unsigned int 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 int nilfs_last_byte(struct inode *inode, unsigned long page_nr)
{
	unsigned int 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 int from,
			       unsigned int 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 int from, unsigned int to)
{
	struct inode *dir = mapping->host;
	loff_t pos = page_offset(page) + from;
	unsigned int len = to - from;
	unsigned int 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 bool nilfs_check_page(struct page *page)
{
	struct inode *dir = page->mapping->host;
	struct super_block *sb = dir->i_sb;
	unsigned int chunk_size = nilfs_chunk_size(dir);
	char *kaddr = page_address(page);
	unsigned int offs, rec_len;
	unsigned int 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 true;

	/* Too bad, we had an error */

Ebadsize:
	nilfs_error(sb,
		    "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,
		    "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,
		    "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:
	SetPageError(page);
	return false;
}

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 (unlikely(!PageChecked(page))) {
			if (PageError(page) || !nilfs_check_page(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);

	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, "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, "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 int 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,
						"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,
			       "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 int from = (char *)de - (char *)page_address(page);
	unsigned int 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(dir);
}

/*
 *	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 int chunk_size = nilfs_chunk_size(dir);
	unsigned int 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 int 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,
					    "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(dir);
	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 int from, to;
	struct nilfs_dir_entry *de, *pde = NULL;
	int err;

	from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
	to = ((char *)dir - kaddr) + nilfs_rec_len_from_disk(dir->rec_len);
	de = (struct nilfs_dir_entry *)(kaddr + from);

	while ((char *)de < (char *)dir) {
		if (de->rec_len == 0) {
			nilfs_error(inode->i_sb,
				    "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(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 int 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,
					    "zero-length directory entry (kaddr=%p, de=%p)",
					    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_shared	= nilfs_readdir,
	.unlocked_ioctl	= nilfs_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= nilfs_compat_ioctl,
#endif	/* CONFIG_COMPAT */
	.fsync		= nilfs_sync_file,

};
Commit	Line	Data
ae98043f	1	// SPDX-License-Identifier: GPL-2.0+
2ba466d7 YA	2	/*
	3	* dir.c - NILFS directory entry operations
	4	*
	5	* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
	6	*
4b420ab4	7	* Modified for NILFS by Amagai Yoshiji.
2ba466d7 YA	8	*/
	9	/*
	10	* linux/fs/ext2/dir.c
	11	*
	12	* Copyright (C) 1992, 1993, 1994, 1995
	13	* Remy Card ([email protected])
	14	* Laboratoire MASI - Institut Blaise Pascal
	15	* Universite Pierre et Marie Curie (Paris VI)
	16	*
	17	* from
	18	*
	19	* linux/fs/minix/dir.c
	20	*
	21	* Copyright (C) 1991, 1992 Linus Torvalds
	22	*
	23	* ext2 directory handling functions
	24	*
	25	* Big-endian to little-endian byte-swapping/bitmaps by
	26	* David S. Miller ([email protected]), 1995
	27	*
	28	* All code that works with directory layout had been switched to pagecache
	29	* and moved here. AV
	30	*/
	31
	32	#include <linux/pagemap.h>
2ba466d7 YA	33	#include "nilfs.h"
	34	#include "page.h"
	35
e63e88bc RK	36	static inline unsigned int nilfs_rec_len_from_disk(__le16 dlen)
	37	{
	38	unsigned int len = le16_to_cpu(dlen);
	39
	40	#if (PAGE_SIZE >= 65536)
	41	if (len == NILFS_MAX_REC_LEN)
	42	return 1 << 16;
	43	#endif
	44	return len;
	45	}
	46
	47	static inline __le16 nilfs_rec_len_to_disk(unsigned int len)
	48	{
	49	#if (PAGE_SIZE >= 65536)
	50	if (len == (1 << 16))
	51	return cpu_to_le16(NILFS_MAX_REC_LEN);
	52
	53	BUG_ON(len > (1 << 16));
	54	#endif
	55	return cpu_to_le16(len);
	56	}
	57
2ba466d7 YA	58	/*
	59	* nilfs uses block-sized chunks. Arguably, sector-sized ones would be
	60	* more robust, but we have what we have
	61	*/
0c6c44cb	62	static inline unsigned int nilfs_chunk_size(struct inode *inode)
2ba466d7 YA	63	{
	64	return inode->i_sb->s_blocksize;
	65	}
	66
	67	static inline void nilfs_put_page(struct page *page)
	68	{
	69	kunmap(page);
09cbfeaf	70	put_page(page);
2ba466d7 YA	71	}
2ba466d7 YA	72
2ba466d7 YA	73	/*
	74	* Return the offset into page `page_nr' of the last valid
	75	* byte in that page, plus one.
	76	*/
0c6c44cb	77	static unsigned int nilfs_last_byte(struct inode *inode, unsigned long page_nr)
2ba466d7	78	{
0c6c44cb	79	unsigned int last_byte = inode->i_size;
2ba466d7	80
09cbfeaf KS	81	last_byte -= page_nr << PAGE_SHIFT;
	82	if (last_byte > PAGE_SIZE)
	83	last_byte = PAGE_SIZE;
2ba466d7 YA	84	return last_byte;
	85	}
	86
0c6c44cb RK	87	static int nilfs_prepare_chunk(struct page *page, unsigned int from,
0c6c44cb RK	88	unsigned int to)
2ba466d7 YA	89	{
2ba466d7 YA	90	loff_t pos = page_offset(page) + from;
4ad364ca	91
6e1db88d	92	return __block_write_begin(page, pos, to - from, nilfs_get_block);
2ba466d7 YA	93	}
2ba466d7 YA	94
2093abf9 JS	95	static void nilfs_commit_chunk(struct page *page,
2093abf9 JS	96	struct address_space *mapping,
0c6c44cb	97	unsigned int from, unsigned int to)
2ba466d7 YA	98	{
2ba466d7 YA	99	struct inode *dir = mapping->host;
2ba466d7	100	loff_t pos = page_offset(page) + from;
0c6c44cb RK	101	unsigned int len = to - from;
0c6c44cb RK	102	unsigned int nr_dirty, copied;
2ba466d7 YA	103	int err;
	104
	105	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
	106	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
58d55471	107	if (pos + copied > dir->i_size)
2ba466d7	108	i_size_write(dir, pos + copied);
2ba466d7 YA	109	if (IS_DIRSYNC(dir))
2ba466d7 YA	110	nilfs_set_transaction_flag(NILFS_TI_SYNC);
bcbc8c64	111	err = nilfs_set_file_dirty(dir, nr_dirty);
2093abf9	112	WARN_ON(err); /* do not happen */
2ba466d7	113	unlock_page(page);
2ba466d7 YA	114	}
2ba466d7 YA	115
be5b82db	116	static bool nilfs_check_page(struct page *page)
2ba466d7 YA	117	{
	118	struct inode *dir = page->mapping->host;
	119	struct super_block *sb = dir->i_sb;
0c6c44cb	120	unsigned int chunk_size = nilfs_chunk_size(dir);
2ba466d7	121	char *kaddr = page_address(page);
0c6c44cb RK	122	unsigned int offs, rec_len;
0c6c44cb RK	123	unsigned int limit = PAGE_SIZE;
2ba466d7 YA	124	struct nilfs_dir_entry *p;
	125	char *error;
	126
09cbfeaf KS	127	if ((dir->i_size >> PAGE_SHIFT) == page->index) {
09cbfeaf KS	128	limit = dir->i_size & ~PAGE_MASK;
2ba466d7 YA	129	if (limit & (chunk_size - 1))
	130	goto Ebadsize;
	131	if (!limit)
	132	goto out;
	133	}
	134	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
	135	p = (struct nilfs_dir_entry *)(kaddr + offs);
6cda9fa2	136	rec_len = nilfs_rec_len_from_disk(p->rec_len);
2ba466d7 YA	137
	138	if (rec_len < NILFS_DIR_REC_LEN(1))
	139	goto Eshort;
	140	if (rec_len & 3)
	141	goto Ealign;
	142	if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
	143	goto Enamelen;
	144	if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
	145	goto Espan;
	146	}
	147	if (offs != limit)
	148	goto Eend;
	149	out:
	150	SetPageChecked(page);
be5b82db	151	return true;
2ba466d7 YA	152
	153	/* Too bad, we had an error */
	154
	155	Ebadsize:
cae3d4ca	156	nilfs_error(sb,
2ba466d7	157	"size of directory #%lu is not a multiple of chunk size",
cae3d4ca	158	dir->i_ino);
2ba466d7 YA	159	goto fail;
	160	Eshort:
	161	error = "rec_len is smaller than minimal";
	162	goto bad_entry;
	163	Ealign:
	164	error = "unaligned directory entry";
	165	goto bad_entry;
	166	Enamelen:
	167	error = "rec_len is too small for name_len";
	168	goto bad_entry;
	169	Espan:
	170	error = "directory entry across blocks";
	171	bad_entry:
cae3d4ca RK	172	nilfs_error(sb,
	173	"bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
	174	dir->i_ino, error, (page->index << PAGE_SHIFT) + offs,
	175	(unsigned long)le64_to_cpu(p->inode),
2ba466d7 YA	176	rec_len, p->name_len);
	177	goto fail;
	178	Eend:
	179	p = (struct nilfs_dir_entry *)(kaddr + offs);
cae3d4ca RK	180	nilfs_error(sb,
	181	"entry in directory #%lu spans the page boundary offset=%lu, inode=%lu",
	182	dir->i_ino, (page->index << PAGE_SHIFT) + offs,
	183	(unsigned long)le64_to_cpu(p->inode));
2ba466d7	184	fail:
2ba466d7	185	SetPageError(page);
be5b82db	186	return false;
2ba466d7 YA	187	}
	188
	189	static struct page nilfs_get_page(struct inode dir, unsigned long n)
	190	{
	191	struct address_space *mapping = dir->i_mapping;
c28e69d9 RK	192	struct page *page = read_mapping_page(mapping, n, NULL);
c28e69d9 RK	193
2ba466d7	194	if (!IS_ERR(page)) {
2ba466d7	195	kmap(page);
be5b82db AV	196	if (unlikely(!PageChecked(page))) {
	197	if (PageError(page) \|\| !nilfs_check_page(page))
	198	goto fail;
	199	}
2ba466d7 YA	200	}
	201	return page;
	202
	203	fail:
	204	nilfs_put_page(page);
	205	return ERR_PTR(-EIO);
	206	}
	207
	208	/*
	209	* NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
	210	*
	211	* len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
	212	*/
	213	static int
072f98b4	214	nilfs_match(int len, const unsigned char name, struct nilfs_dir_entry de)
2ba466d7 YA	215	{
	216	if (len != de->name_len)
	217	return 0;
	218	if (!de->inode)
	219	return 0;
	220	return !memcmp(name, de->name, len);
	221	}
	222
	223	/*
	224	* p is at least 6 bytes before the end of page
	225	*/
	226	static struct nilfs_dir_entry nilfs_next_entry(struct nilfs_dir_entry p)
	227	{
6cda9fa2 RK	228	return (struct nilfs_dir_entry )((char )p +
6cda9fa2 RK	229	nilfs_rec_len_from_disk(p->rec_len));
2ba466d7 YA	230	}
	231
	232	static unsigned char
	233	nilfs_filetype_table[NILFS_FT_MAX] = {
	234	[NILFS_FT_UNKNOWN] = DT_UNKNOWN,
	235	[NILFS_FT_REG_FILE] = DT_REG,
	236	[NILFS_FT_DIR] = DT_DIR,
	237	[NILFS_FT_CHRDEV] = DT_CHR,
	238	[NILFS_FT_BLKDEV] = DT_BLK,
	239	[NILFS_FT_FIFO] = DT_FIFO,
	240	[NILFS_FT_SOCK] = DT_SOCK,
	241	[NILFS_FT_SYMLINK] = DT_LNK,
	242	};
	243
	244	#define S_SHIFT 12
	245	static unsigned char
	246	nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
	247	[S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
	248	[S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
	249	[S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
	250	[S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
	251	[S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
	252	[S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
	253	[S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
	254	};
	255
	256	static void nilfs_set_de_type(struct nilfs_dir_entry de, struct inode inode)
	257	{
c6e49e3f	258	umode_t mode = inode->i_mode;
2ba466d7 YA	259
	260	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	261	}
	262
1616abe8	263	static int nilfs_readdir(struct file file, struct dir_context ctx)
2ba466d7	264	{
1616abe8 AV	265	loff_t pos = ctx->pos;
1616abe8 AV	266	struct inode *inode = file_inode(file);
2ba466d7	267	struct super_block *sb = inode->i_sb;
09cbfeaf KS	268	unsigned int offset = pos & ~PAGE_MASK;
09cbfeaf KS	269	unsigned long n = pos >> PAGE_SHIFT;
2ba466d7	270	unsigned long npages = dir_pages(inode);
2ba466d7 YA	271
2ba466d7 YA	272	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
1616abe8	273	return 0;
2ba466d7 YA	274
	275	for ( ; n < npages; n++, offset = 0) {
	276	char kaddr, limit;
	277	struct nilfs_dir_entry *de;
	278	struct page *page = nilfs_get_page(inode, n);
	279
	280	if (IS_ERR(page)) {
cae3d4ca	281	nilfs_error(sb, "bad page in #%lu", inode->i_ino);
09cbfeaf	282	ctx->pos += PAGE_SIZE - offset;
1616abe8	283	return -EIO;
2ba466d7 YA	284	}
	285	kaddr = page_address(page);
	286	de = (struct nilfs_dir_entry *)(kaddr + offset);
	287	limit = kaddr + nilfs_last_byte(inode, n) -
	288	NILFS_DIR_REC_LEN(1);
	289	for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
	290	if (de->rec_len == 0) {
cae3d4ca	291	nilfs_error(sb, "zero-length directory entry");
2ba466d7	292	nilfs_put_page(page);
1616abe8	293	return -EIO;
2ba466d7 YA	294	}
2ba466d7 YA	295	if (de->inode) {
1616abe8	296	unsigned char t;
2ba466d7	297
1616abe8 AV	298	if (de->file_type < NILFS_FT_MAX)
	299	t = nilfs_filetype_table[de->file_type];
	300	else
	301	t = DT_UNKNOWN;
2ba466d7	302
1616abe8 AV	303	if (!dir_emit(ctx, de->name, de->name_len,
1616abe8 AV	304	le64_to_cpu(de->inode), t)) {
2ba466d7	305	nilfs_put_page(page);
1616abe8	306	return 0;
2ba466d7 YA	307	}
2ba466d7 YA	308	}
1616abe8	309	ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	310	}
	311	nilfs_put_page(page);
	312	}
1616abe8	313	return 0;
2ba466d7 YA	314	}
	315
	316	/*
	317	* nilfs_find_entry()
	318	*
	319	* finds an entry in the specified directory with the wanted name. It
	320	* returns the page in which the entry was found, and the entry itself
	321	* (as a parameter - res_dir). Page is returned mapped and unlocked.
	322	* Entry is guaranteed to be valid.
	323	*/
	324	struct nilfs_dir_entry *
0319003d	325	nilfs_find_entry(struct inode dir, const struct qstr qstr,
2ba466d7 YA	326	struct page **res_page)
2ba466d7 YA	327	{
0319003d AV	328	const unsigned char *name = qstr->name;
0319003d AV	329	int namelen = qstr->len;
0c6c44cb	330	unsigned int reclen = NILFS_DIR_REC_LEN(namelen);
2ba466d7 YA	331	unsigned long start, n;
	332	unsigned long npages = dir_pages(dir);
	333	struct page *page = NULL;
	334	struct nilfs_inode_info *ei = NILFS_I(dir);
	335	struct nilfs_dir_entry *de;
	336
	337	if (npages == 0)
	338	goto out;
	339
	340	/* OFFSET_CACHE */
	341	*res_page = NULL;
	342
	343	start = ei->i_dir_start_lookup;
	344	if (start >= npages)
	345	start = 0;
	346	n = start;
	347	do {
	348	char *kaddr;
4ad364ca	349
2ba466d7 YA	350	page = nilfs_get_page(dir, n);
	351	if (!IS_ERR(page)) {
	352	kaddr = page_address(page);
	353	de = (struct nilfs_dir_entry *)kaddr;
	354	kaddr += nilfs_last_byte(dir, n) - reclen;
	355	while ((char *) de <= kaddr) {
	356	if (de->rec_len == 0) {
cae3d4ca	357	nilfs_error(dir->i_sb,
2ba466d7 YA	358	"zero-length directory entry");
	359	nilfs_put_page(page);
	360	goto out;
	361	}
	362	if (nilfs_match(namelen, name, de))
	363	goto found;
	364	de = nilfs_next_entry(de);
	365	}
	366	nilfs_put_page(page);
	367	}
	368	if (++n >= npages)
	369	n = 0;
	370	/* next page is past the blocks we've got */
09cbfeaf	371	if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
cae3d4ca	372	nilfs_error(dir->i_sb,
1621562b	373	"dir %lu size %lld exceeds block count %llu",
2ba466d7 YA	374	dir->i_ino, dir->i_size,
	375	(unsigned long long)dir->i_blocks);
	376	goto out;
	377	}
	378	} while (n != start);
	379	out:
	380	return NULL;
	381
	382	found:
	383	*res_page = page;
	384	ei->i_dir_start_lookup = n;
	385	return de;
	386	}
	387
	388	struct nilfs_dir_entry nilfs_dotdot(struct inode dir, struct page **p)
	389	{
	390	struct page *page = nilfs_get_page(dir, 0);
	391	struct nilfs_dir_entry *de = NULL;
	392
	393	if (!IS_ERR(page)) {
	394	de = nilfs_next_entry(
	395	(struct nilfs_dir_entry *)page_address(page));
	396	*p = page;
	397	}
	398	return de;
	399	}
	400
0319003d	401	ino_t nilfs_inode_by_name(struct inode dir, const struct qstr qstr)
2ba466d7 YA	402	{
	403	ino_t res = 0;
	404	struct nilfs_dir_entry *de;
	405	struct page *page;
	406
0319003d	407	de = nilfs_find_entry(dir, qstr, &page);
2ba466d7 YA	408	if (de) {
	409	res = le64_to_cpu(de->inode);
	410	kunmap(page);
09cbfeaf	411	put_page(page);
2ba466d7 YA	412	}
	413	return res;
	414	}
	415
	416	/* Releases the page */
	417	void nilfs_set_link(struct inode dir, struct nilfs_dir_entry de,
	418	struct page page, struct inode inode)
	419	{
0c6c44cb RK	420	unsigned int from = (char )de - (char )page_address(page);
0c6c44cb RK	421	unsigned int to = from + nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	422	struct address_space *mapping = page->mapping;
	423	int err;
	424
	425	lock_page(page);
f4e420dc	426	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	427	BUG_ON(err);
	428	de->inode = cpu_to_le64(inode->i_ino);
	429	nilfs_set_de_type(de, inode);
2093abf9	430	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7	431	nilfs_put_page(page);
078cd827	432	dir->i_mtime = dir->i_ctime = current_time(dir);
2ba466d7 YA	433	}
	434
	435	/*
	436	* Parent is locked.
	437	*/
	438	int nilfs_add_link(struct dentry dentry, struct inode inode)
	439	{
2b0143b5	440	struct inode *dir = d_inode(dentry->d_parent);
072f98b4	441	const unsigned char *name = dentry->d_name.name;
2ba466d7	442	int namelen = dentry->d_name.len;
0c6c44cb RK	443	unsigned int chunk_size = nilfs_chunk_size(dir);
0c6c44cb RK	444	unsigned int reclen = NILFS_DIR_REC_LEN(namelen);
2ba466d7 YA	445	unsigned short rec_len, name_len;
	446	struct page *page = NULL;
	447	struct nilfs_dir_entry *de;
	448	unsigned long npages = dir_pages(dir);
	449	unsigned long n;
	450	char *kaddr;
0c6c44cb	451	unsigned int from, to;
2ba466d7 YA	452	int err;
	453
	454	/*
	455	* We take care of directory expansion in the same loop.
	456	* This code plays outside i_size, so it locks the page
	457	* to protect that region.
	458	*/
	459	for (n = 0; n <= npages; n++) {
	460	char *dir_end;
	461
	462	page = nilfs_get_page(dir, n);
	463	err = PTR_ERR(page);
	464	if (IS_ERR(page))
	465	goto out;
	466	lock_page(page);
	467	kaddr = page_address(page);
	468	dir_end = kaddr + nilfs_last_byte(dir, n);
	469	de = (struct nilfs_dir_entry *)kaddr;
09cbfeaf	470	kaddr += PAGE_SIZE - reclen;
2ba466d7 YA	471	while ((char *)de <= kaddr) {
	472	if ((char *)de == dir_end) {
	473	/* We hit i_size */
	474	name_len = 0;
	475	rec_len = chunk_size;
6cda9fa2	476	de->rec_len = nilfs_rec_len_to_disk(chunk_size);
2ba466d7 YA	477	de->inode = 0;
	478	goto got_it;
	479	}
	480	if (de->rec_len == 0) {
cae3d4ca	481	nilfs_error(dir->i_sb,
2ba466d7 YA	482	"zero-length directory entry");
	483	err = -EIO;
	484	goto out_unlock;
	485	}
	486	err = -EEXIST;
	487	if (nilfs_match(namelen, name, de))
	488	goto out_unlock;
	489	name_len = NILFS_DIR_REC_LEN(de->name_len);
6cda9fa2	490	rec_len = nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	491	if (!de->inode && rec_len >= reclen)
	492	goto got_it;
	493	if (rec_len >= name_len + reclen)
	494	goto got_it;
	495	de = (struct nilfs_dir_entry )((char )de + rec_len);
	496	}
	497	unlock_page(page);
	498	nilfs_put_page(page);
	499	}
	500	BUG();
	501	return -EINVAL;
	502
	503	got_it:
	504	from = (char )de - (char )page_address(page);
	505	to = from + rec_len;
f4e420dc	506	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	507	if (err)
	508	goto out_unlock;
	509	if (de->inode) {
	510	struct nilfs_dir_entry *de1;
	511
	512	de1 = (struct nilfs_dir_entry )((char )de + name_len);
6cda9fa2 RK	513	de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
6cda9fa2 RK	514	de->rec_len = nilfs_rec_len_to_disk(name_len);
2ba466d7 YA	515	de = de1;
	516	}
	517	de->name_len = namelen;
	518	memcpy(de->name, name, namelen);
	519	de->inode = cpu_to_le64(inode->i_ino);
	520	nilfs_set_de_type(de, inode);
2093abf9	521	nilfs_commit_chunk(page, page->mapping, from, to);
078cd827	522	dir->i_mtime = dir->i_ctime = current_time(dir);
abdb318b	523	nilfs_mark_inode_dirty(dir);
2ba466d7 YA	524	/* OFFSET_CACHE */
	525	out_put:
	526	nilfs_put_page(page);
	527	out:
	528	return err;
	529	out_unlock:
	530	unlock_page(page);
	531	goto out_put;
	532	}
	533
	534	/*
	535	* nilfs_delete_entry deletes a directory entry by merging it with the
	536	* previous entry. Page is up-to-date. Releases the page.
	537	*/
	538	int nilfs_delete_entry(struct nilfs_dir_entry dir, struct page page)
	539	{
	540	struct address_space *mapping = page->mapping;
	541	struct inode *inode = mapping->host;
	542	char *kaddr = page_address(page);
0c6c44cb RK	543	unsigned int from, to;
0c6c44cb RK	544	struct nilfs_dir_entry de, pde = NULL;
2ba466d7 YA	545	int err;
2ba466d7 YA	546
0c6c44cb RK	547	from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
	548	to = ((char *)dir - kaddr) + nilfs_rec_len_from_disk(dir->rec_len);
	549	de = (struct nilfs_dir_entry *)(kaddr + from);
	550
2ba466d7 YA	551	while ((char )de < (char )dir) {
2ba466d7 YA	552	if (de->rec_len == 0) {
cae3d4ca	553	nilfs_error(inode->i_sb,
2ba466d7 YA	554	"zero-length directory entry");
	555	err = -EIO;
	556	goto out;
	557	}
	558	pde = de;
	559	de = nilfs_next_entry(de);
	560	}
	561	if (pde)
	562	from = (char )pde - (char )page_address(page);
	563	lock_page(page);
f4e420dc	564	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	565	BUG_ON(err);
2ba466d7 YA	566	if (pde)
6cda9fa2	567	pde->rec_len = nilfs_rec_len_to_disk(to - from);
2ba466d7	568	dir->inode = 0;
2093abf9	569	nilfs_commit_chunk(page, mapping, from, to);
078cd827	570	inode->i_ctime = inode->i_mtime = current_time(inode);
2ba466d7 YA	571	out:
	572	nilfs_put_page(page);
	573	return err;
	574	}
	575
	576	/*
	577	* Set the first fragment of directory.
	578	*/
	579	int nilfs_make_empty(struct inode inode, struct inode parent)
	580	{
	581	struct address_space *mapping = inode->i_mapping;
	582	struct page *page = grab_cache_page(mapping, 0);
0c6c44cb	583	unsigned int chunk_size = nilfs_chunk_size(inode);
2ba466d7 YA	584	struct nilfs_dir_entry *de;
	585	int err;
	586	void *kaddr;
	587
	588	if (!page)
	589	return -ENOMEM;
	590
f4e420dc	591	err = nilfs_prepare_chunk(page, 0, chunk_size);
2ba466d7 YA	592	if (unlikely(err)) {
	593	unlock_page(page);
	594	goto fail;
	595	}
7b9c0976	596	kaddr = kmap_atomic(page);
2ba466d7 YA	597	memset(kaddr, 0, chunk_size);
	598	de = (struct nilfs_dir_entry *)kaddr;
	599	de->name_len = 1;
6cda9fa2	600	de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
2ba466d7 YA	601	memcpy(de->name, ".\0\0", 4);
	602	de->inode = cpu_to_le64(inode->i_ino);
	603	nilfs_set_de_type(de, inode);
	604
	605	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
	606	de->name_len = 2;
6cda9fa2	607	de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
2ba466d7 YA	608	de->inode = cpu_to_le64(parent->i_ino);
	609	memcpy(de->name, "..\0", 4);
	610	nilfs_set_de_type(de, inode);
7b9c0976	611	kunmap_atomic(kaddr);
2093abf9	612	nilfs_commit_chunk(page, mapping, 0, chunk_size);
2ba466d7	613	fail:
09cbfeaf	614	put_page(page);
2ba466d7 YA	615	return err;
	616	}
	617
	618	/*
	619	* routine to check that the specified directory is empty (for rmdir)
	620	*/
	621	int nilfs_empty_dir(struct inode *inode)
	622	{
	623	struct page *page = NULL;
	624	unsigned long i, npages = dir_pages(inode);
	625
	626	for (i = 0; i < npages; i++) {
	627	char *kaddr;
	628	struct nilfs_dir_entry *de;
	629
	630	page = nilfs_get_page(inode, i);
	631	if (IS_ERR(page))
	632	continue;
	633
	634	kaddr = page_address(page);
	635	de = (struct nilfs_dir_entry *)kaddr;
	636	kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
	637
	638	while ((char *)de <= kaddr) {
	639	if (de->rec_len == 0) {
cae3d4ca	640	nilfs_error(inode->i_sb,
06f4abf6 RK	641	"zero-length directory entry (kaddr=%p, de=%p)",
06f4abf6 RK	642	kaddr, de);
2ba466d7 YA	643	goto not_empty;
	644	}
	645	if (de->inode != 0) {
	646	/* check for . and .. */
	647	if (de->name[0] != '.')
	648	goto not_empty;
	649	if (de->name_len > 2)
	650	goto not_empty;
	651	if (de->name_len < 2) {
	652	if (de->inode !=
	653	cpu_to_le64(inode->i_ino))
	654	goto not_empty;
	655	} else if (de->name[1] != '.')
	656	goto not_empty;
	657	}
	658	de = nilfs_next_entry(de);
	659	}
	660	nilfs_put_page(page);
	661	}
	662	return 1;
	663
	664	not_empty:
	665	nilfs_put_page(page);
	666	return 0;
	667	}
	668
828c0950	669	const struct file_operations nilfs_dir_operations = {
2ba466d7 YA	670	.llseek = generic_file_llseek,
2ba466d7 YA	671	.read = generic_read_dir,
c51da20c	672	.iterate_shared = nilfs_readdir,
7a946193	673	.unlocked_ioctl = nilfs_ioctl,
2ba466d7	674	#ifdef CONFIG_COMPAT
828b1c50	675	.compat_ioctl = nilfs_compat_ioctl,
2ba466d7 YA	676	#endif /* CONFIG_COMPAT */
	677	.fsync = nilfs_sync_file,
	678
	679	};