[net-next-2.6.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;
	struct nilfs_sb_info *sbi = NILFS_SB(dir->i_sb);
	loff_t pos = page_offset(page) + from;
	unsigned len = to - from;
	unsigned nr_dirty, copied;
	int err;

	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
	if (pos + copied > dir->i_size)
		i_size_write(dir, pos + copied);
	if (IS_DIRSYNC(dir))
		nilfs_set_transaction_flag(NILFS_TI_SYNC);
	err = nilfs_set_file_dirty(sbi, 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)
{
	mode_t mode = inode->i_mode;

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

static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
	loff_t pos = filp->f_pos;
	struct inode *inode = filp->f_dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	unsigned long npages = dir_pages(inode);
/*	unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
	unsigned char *types = NULL;
	int ret;

	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
		goto success;

	types = nilfs_filetype_table;

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

		if (IS_ERR(page)) {
			nilfs_error(sb, __func__, "bad page in #%lu",
				    inode->i_ino);
			filp->f_pos += PAGE_CACHE_SIZE - offset;
			ret = -EIO;
			goto done;
		}
		kaddr = page_address(page);
		de = (struct nilfs_dir_entry *)(kaddr + offset);
		limit = kaddr + nilfs_last_byte(inode, n) -
			NILFS_DIR_REC_LEN(1);
		for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
			if (de->rec_len == 0) {
				nilfs_error(sb, __func__,
					    "zero-length directory entry");
				ret = -EIO;
				nilfs_put_page(page);
				goto done;
			}
			if (de->inode) {
				int over;
				unsigned char d_type = DT_UNKNOWN;

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

				offset = (char *)de - kaddr;
				over = filldir(dirent, de->name, de->name_len,
						(n<<PAGE_CACHE_SHIFT) | offset,
						le64_to_cpu(de->inode), d_type);
				if (over) {
					nilfs_put_page(page);
					goto success;
				}
			}
			filp->f_pos += nilfs_rec_len_from_disk(de->rec_len);
		}
		nilfs_put_page(page);
	}

success:
	ret = 0;
done:
	return ret;
}

/*
 *	nilfs_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the page in which the entry was found, and the entry itself
 * (as a parameter - res_dir). Page is returned mapped and unlocked.
 * Entry is guaranteed to be valid.
 */
struct nilfs_dir_entry *
nilfs_find_entry(struct inode *dir, 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;
/*	NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
}

/*
 *	Parent is locked.
 */
int nilfs_add_link(struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = dentry->d_parent->d_inode;
	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_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
	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;
/*	NILFS_I(inode)->i_flags &= ~NILFS_BTREE_FL; */
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, KM_USER0);
	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, KM_USER0);
	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,
	.readdir	= nilfs_readdir,
	.unlocked_ioctl	= nilfs_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= nilfs_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	{
	93	struct inode *dir = mapping->host;
	94	struct nilfs_sb_info *sbi = NILFS_SB(dir->i_sb);
	95	loff_t pos = page_offset(page) + from;
	96	unsigned len = to - from;
	97	unsigned nr_dirty, copied;
	98	int err;
	99
	100	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
	101	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
58d55471	102	if (pos + copied > dir->i_size)
2ba466d7	103	i_size_write(dir, pos + copied);
2ba466d7 YA	104	if (IS_DIRSYNC(dir))
	105	nilfs_set_transaction_flag(NILFS_TI_SYNC);
	106	err = nilfs_set_file_dirty(sbi, dir, nr_dirty);
2093abf9	107	WARN_ON(err); /* do not happen */
2ba466d7	108	unlock_page(page);
2ba466d7 YA	109	}
	110
	111	static void nilfs_check_page(struct page *page)
	112	{
	113	struct inode *dir = page->mapping->host;
	114	struct super_block *sb = dir->i_sb;
	115	unsigned chunk_size = nilfs_chunk_size(dir);
	116	char *kaddr = page_address(page);
	117	unsigned offs, rec_len;
	118	unsigned limit = PAGE_CACHE_SIZE;
	119	struct nilfs_dir_entry *p;
	120	char *error;
	121
	122	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
	123	limit = dir->i_size & ~PAGE_CACHE_MASK;
	124	if (limit & (chunk_size - 1))
	125	goto Ebadsize;
	126	if (!limit)
	127	goto out;
	128	}
	129	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
	130	p = (struct nilfs_dir_entry *)(kaddr + offs);
6cda9fa2	131	rec_len = nilfs_rec_len_from_disk(p->rec_len);
2ba466d7 YA	132
	133	if (rec_len < NILFS_DIR_REC_LEN(1))
	134	goto Eshort;
	135	if (rec_len & 3)
	136	goto Ealign;
	137	if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
	138	goto Enamelen;
	139	if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
	140	goto Espan;
	141	}
	142	if (offs != limit)
	143	goto Eend;
	144	out:
	145	SetPageChecked(page);
	146	return;
	147
	148	/* Too bad, we had an error */
	149
	150	Ebadsize:
	151	nilfs_error(sb, "nilfs_check_page",
	152	"size of directory #%lu is not a multiple of chunk size",
	153	dir->i_ino
	154	);
	155	goto fail;
	156	Eshort:
	157	error = "rec_len is smaller than minimal";
	158	goto bad_entry;
	159	Ealign:
	160	error = "unaligned directory entry";
	161	goto bad_entry;
	162	Enamelen:
	163	error = "rec_len is too small for name_len";
	164	goto bad_entry;
	165	Espan:
	166	error = "directory entry across blocks";
	167	bad_entry:
	168	nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
	169	"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
	170	dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
	171	(unsigned long) le64_to_cpu(p->inode),
	172	rec_len, p->name_len);
	173	goto fail;
	174	Eend:
	175	p = (struct nilfs_dir_entry *)(kaddr + offs);
	176	nilfs_error(sb, "nilfs_check_page",
	177	"entry in directory #%lu spans the page boundary"
	178	"offset=%lu, inode=%lu",
	179	dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
	180	(unsigned long) le64_to_cpu(p->inode));
	181	fail:
	182	SetPageChecked(page);
	183	SetPageError(page);
	184	}
	185
	186	static struct page nilfs_get_page(struct inode dir, unsigned long n)
	187	{
	188	struct address_space *mapping = dir->i_mapping;
c28e69d9 RK	189	struct page *page = read_mapping_page(mapping, n, NULL);
c28e69d9 RK	190
2ba466d7	191	if (!IS_ERR(page)) {
2ba466d7	192	kmap(page);
2ba466d7 YA	193	if (!PageChecked(page))
	194	nilfs_check_page(page);
	195	if (PageError(page))
	196	goto fail;
	197	}
	198	return page;
	199
	200	fail:
	201	nilfs_put_page(page);
	202	return ERR_PTR(-EIO);
	203	}
	204
	205	/*
	206	* NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
	207	*
	208	* len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
	209	*/
	210	static int
072f98b4	211	nilfs_match(int len, const unsigned char name, struct nilfs_dir_entry de)
2ba466d7 YA	212	{
	213	if (len != de->name_len)
	214	return 0;
	215	if (!de->inode)
	216	return 0;
	217	return !memcmp(name, de->name, len);
	218	}
	219
	220	/*
	221	* p is at least 6 bytes before the end of page
	222	*/
	223	static struct nilfs_dir_entry nilfs_next_entry(struct nilfs_dir_entry p)
	224	{
6cda9fa2 RK	225	return (struct nilfs_dir_entry )((char )p +
6cda9fa2 RK	226	nilfs_rec_len_from_disk(p->rec_len));
2ba466d7 YA	227	}
	228
	229	static unsigned char
	230	nilfs_filetype_table[NILFS_FT_MAX] = {
	231	[NILFS_FT_UNKNOWN] = DT_UNKNOWN,
	232	[NILFS_FT_REG_FILE] = DT_REG,
	233	[NILFS_FT_DIR] = DT_DIR,
	234	[NILFS_FT_CHRDEV] = DT_CHR,
	235	[NILFS_FT_BLKDEV] = DT_BLK,
	236	[NILFS_FT_FIFO] = DT_FIFO,
	237	[NILFS_FT_SOCK] = DT_SOCK,
	238	[NILFS_FT_SYMLINK] = DT_LNK,
	239	};
	240
	241	#define S_SHIFT 12
	242	static unsigned char
	243	nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
	244	[S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
	245	[S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
	246	[S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
	247	[S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
	248	[S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
	249	[S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
	250	[S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
	251	};
	252
	253	static void nilfs_set_de_type(struct nilfs_dir_entry de, struct inode inode)
	254	{
	255	mode_t mode = inode->i_mode;
	256
	257	de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	258	}
	259
	260	static int nilfs_readdir(struct file filp, void dirent, filldir_t filldir)
	261	{
	262	loff_t pos = filp->f_pos;
	263	struct inode *inode = filp->f_dentry->d_inode;
	264	struct super_block *sb = inode->i_sb;
	265	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	266	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	267	unsigned long npages = dir_pages(inode);
	268	/* unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
	269	unsigned char *types = NULL;
	270	int ret;
	271
	272	if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
	273	goto success;
	274
	275	types = nilfs_filetype_table;
	276
	277	for ( ; n < npages; n++, offset = 0) {
	278	char kaddr, limit;
	279	struct nilfs_dir_entry *de;
	280	struct page *page = nilfs_get_page(inode, n);
	281
	282	if (IS_ERR(page)) {
	283	nilfs_error(sb, __func__, "bad page in #%lu",
	284	inode->i_ino);
	285	filp->f_pos += PAGE_CACHE_SIZE - offset;
	286	ret = -EIO;
	287	goto done;
	288	}
	289	kaddr = page_address(page);
	290	de = (struct nilfs_dir_entry *)(kaddr + offset);
291	limit = kaddr + nilfs_last_byte(inode, n) -
292	NILFS_DIR_REC_LEN(1);
293	for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
294	if (de->rec_len == 0) {
295	nilfs_error(sb, __func__,
296	"zero-length directory entry");
297	ret = -EIO;
298	nilfs_put_page(page);
299	goto done;
300	}
301	if (de->inode) {
302	int over;
303	unsigned char d_type = DT_UNKNOWN;
304
305	if (types && de->file_type < NILFS_FT_MAX)
306	d_type = types[de->file_type];
307
308	offset = (char *)de - kaddr;
309	over = filldir(dirent, de->name, de->name_len,
310	(n<<PAGE_CACHE_SHIFT) \| offset,
311	le64_to_cpu(de->inode), d_type);
312	if (over) {
313	nilfs_put_page(page);
314	goto success;
315	}
316	}
6cda9fa2	317	filp->f_pos += nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	318	}
	319	nilfs_put_page(page);
	320	}
	321
	322	success:
	323	ret = 0;
	324	done:
	325	return ret;
	326	}
	327
	328	/*
	329	* nilfs_find_entry()
	330	*
	331	* finds an entry in the specified directory with the wanted name. It
	332	* returns the page in which the entry was found, and the entry itself
	333	* (as a parameter - res_dir). Page is returned mapped and unlocked.
	334	* Entry is guaranteed to be valid.
	335	*/
	336	struct nilfs_dir_entry *
0319003d	337	nilfs_find_entry(struct inode dir, const struct qstr qstr,
2ba466d7 YA	338	struct page **res_page)
2ba466d7 YA	339	{
0319003d AV	340	const unsigned char *name = qstr->name;
0319003d AV	341	int namelen = qstr->len;
2ba466d7 YA	342	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
	343	unsigned long start, n;
	344	unsigned long npages = dir_pages(dir);
	345	struct page *page = NULL;
	346	struct nilfs_inode_info *ei = NILFS_I(dir);
	347	struct nilfs_dir_entry *de;
	348
	349	if (npages == 0)
	350	goto out;
	351
	352	/* OFFSET_CACHE */
	353	*res_page = NULL;
	354
	355	start = ei->i_dir_start_lookup;
	356	if (start >= npages)
	357	start = 0;
	358	n = start;
	359	do {
	360	char *kaddr;
	361	page = nilfs_get_page(dir, n);
	362	if (!IS_ERR(page)) {
	363	kaddr = page_address(page);
	364	de = (struct nilfs_dir_entry *)kaddr;
	365	kaddr += nilfs_last_byte(dir, n) - reclen;
	366	while ((char *) de <= kaddr) {
	367	if (de->rec_len == 0) {
	368	nilfs_error(dir->i_sb, __func__,
	369	"zero-length directory entry");
	370	nilfs_put_page(page);
	371	goto out;
	372	}
	373	if (nilfs_match(namelen, name, de))
	374	goto found;
	375	de = nilfs_next_entry(de);
	376	}
	377	nilfs_put_page(page);
	378	}
	379	if (++n >= npages)
	380	n = 0;
	381	/* next page is past the blocks we've got */
	382	if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
	383	nilfs_error(dir->i_sb, __func__,
1621562b	384	"dir %lu size %lld exceeds block count %llu",
2ba466d7 YA	385	dir->i_ino, dir->i_size,
	386	(unsigned long long)dir->i_blocks);
	387	goto out;
	388	}
	389	} while (n != start);
	390	out:
	391	return NULL;
	392
	393	found:
	394	*res_page = page;
	395	ei->i_dir_start_lookup = n;
	396	return de;
	397	}
	398
	399	struct nilfs_dir_entry nilfs_dotdot(struct inode dir, struct page **p)
	400	{
	401	struct page *page = nilfs_get_page(dir, 0);
	402	struct nilfs_dir_entry *de = NULL;
	403
	404	if (!IS_ERR(page)) {
	405	de = nilfs_next_entry(
	406	(struct nilfs_dir_entry *)page_address(page));
	407	*p = page;
	408	}
	409	return de;
	410	}
	411
0319003d	412	ino_t nilfs_inode_by_name(struct inode dir, const struct qstr qstr)
2ba466d7 YA	413	{
	414	ino_t res = 0;
	415	struct nilfs_dir_entry *de;
	416	struct page *page;
	417
0319003d	418	de = nilfs_find_entry(dir, qstr, &page);
2ba466d7 YA	419	if (de) {
	420	res = le64_to_cpu(de->inode);
	421	kunmap(page);
	422	page_cache_release(page);
	423	}
	424	return res;
	425	}
	426
	427	/* Releases the page */
	428	void nilfs_set_link(struct inode dir, struct nilfs_dir_entry de,
	429	struct page page, struct inode inode)
	430	{
	431	unsigned from = (char ) de - (char ) page_address(page);
6cda9fa2	432	unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	433	struct address_space *mapping = page->mapping;
	434	int err;
	435
	436	lock_page(page);
f4e420dc	437	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	438	BUG_ON(err);
	439	de->inode = cpu_to_le64(inode->i_ino);
	440	nilfs_set_de_type(de, inode);
2093abf9	441	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7 YA	442	nilfs_put_page(page);
	443	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	444	/* NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
2ba466d7 YA	445	}
	446
	447	/*
	448	* Parent is locked.
	449	*/
	450	int nilfs_add_link(struct dentry dentry, struct inode inode)
	451	{
	452	struct inode *dir = dentry->d_parent->d_inode;
072f98b4	453	const unsigned char *name = dentry->d_name.name;
2ba466d7 YA	454	int namelen = dentry->d_name.len;
	455	unsigned chunk_size = nilfs_chunk_size(dir);
	456	unsigned reclen = NILFS_DIR_REC_LEN(namelen);
	457	unsigned short rec_len, name_len;
	458	struct page *page = NULL;
	459	struct nilfs_dir_entry *de;
	460	unsigned long npages = dir_pages(dir);
	461	unsigned long n;
	462	char *kaddr;
	463	unsigned from, to;
	464	int err;
	465
	466	/*
	467	* We take care of directory expansion in the same loop.
	468	* This code plays outside i_size, so it locks the page
	469	* to protect that region.
	470	*/
	471	for (n = 0; n <= npages; n++) {
	472	char *dir_end;
	473
	474	page = nilfs_get_page(dir, n);
	475	err = PTR_ERR(page);
	476	if (IS_ERR(page))
	477	goto out;
	478	lock_page(page);
	479	kaddr = page_address(page);
	480	dir_end = kaddr + nilfs_last_byte(dir, n);
	481	de = (struct nilfs_dir_entry *)kaddr;
	482	kaddr += PAGE_CACHE_SIZE - reclen;
	483	while ((char *)de <= kaddr) {
	484	if ((char *)de == dir_end) {
	485	/* We hit i_size */
	486	name_len = 0;
	487	rec_len = chunk_size;
6cda9fa2	488	de->rec_len = nilfs_rec_len_to_disk(chunk_size);
2ba466d7 YA	489	de->inode = 0;
	490	goto got_it;
	491	}
	492	if (de->rec_len == 0) {
	493	nilfs_error(dir->i_sb, __func__,
	494	"zero-length directory entry");
	495	err = -EIO;
	496	goto out_unlock;
	497	}
	498	err = -EEXIST;
	499	if (nilfs_match(namelen, name, de))
	500	goto out_unlock;
	501	name_len = NILFS_DIR_REC_LEN(de->name_len);
6cda9fa2	502	rec_len = nilfs_rec_len_from_disk(de->rec_len);
2ba466d7 YA	503	if (!de->inode && rec_len >= reclen)
	504	goto got_it;
	505	if (rec_len >= name_len + reclen)
	506	goto got_it;
	507	de = (struct nilfs_dir_entry )((char )de + rec_len);
	508	}
	509	unlock_page(page);
	510	nilfs_put_page(page);
	511	}
	512	BUG();
	513	return -EINVAL;
	514
	515	got_it:
	516	from = (char )de - (char )page_address(page);
	517	to = from + rec_len;
f4e420dc	518	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	519	if (err)
	520	goto out_unlock;
	521	if (de->inode) {
	522	struct nilfs_dir_entry *de1;
	523
	524	de1 = (struct nilfs_dir_entry )((char )de + name_len);
6cda9fa2 RK	525	de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
6cda9fa2 RK	526	de->rec_len = nilfs_rec_len_to_disk(name_len);
2ba466d7 YA	527	de = de1;
	528	}
	529	de->name_len = namelen;
	530	memcpy(de->name, name, namelen);
	531	de->inode = cpu_to_le64(inode->i_ino);
	532	nilfs_set_de_type(de, inode);
2093abf9	533	nilfs_commit_chunk(page, page->mapping, from, to);
2ba466d7 YA	534	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
2ba466d7 YA	535	/* NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
abdb318b	536	nilfs_mark_inode_dirty(dir);
2ba466d7 YA	537	/* OFFSET_CACHE */
	538	out_put:
	539	nilfs_put_page(page);
	540	out:
	541	return err;
	542	out_unlock:
	543	unlock_page(page);
	544	goto out_put;
	545	}
	546
	547	/*
	548	* nilfs_delete_entry deletes a directory entry by merging it with the
	549	* previous entry. Page is up-to-date. Releases the page.
	550	*/
	551	int nilfs_delete_entry(struct nilfs_dir_entry dir, struct page page)
	552	{
	553	struct address_space *mapping = page->mapping;
	554	struct inode *inode = mapping->host;
	555	char *kaddr = page_address(page);
	556	unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
6cda9fa2 RK	557	unsigned to = ((char *)dir - kaddr) +
6cda9fa2 RK	558	nilfs_rec_len_from_disk(dir->rec_len);
2ba466d7 YA	559	struct nilfs_dir_entry *pde = NULL;
	560	struct nilfs_dir_entry de = (struct nilfs_dir_entry )(kaddr + from);
	561	int err;
	562
	563	while ((char )de < (char )dir) {
	564	if (de->rec_len == 0) {
	565	nilfs_error(inode->i_sb, __func__,
	566	"zero-length directory entry");
	567	err = -EIO;
	568	goto out;
	569	}
	570	pde = de;
	571	de = nilfs_next_entry(de);
	572	}
	573	if (pde)
	574	from = (char )pde - (char )page_address(page);
	575	lock_page(page);
f4e420dc	576	err = nilfs_prepare_chunk(page, from, to);
2ba466d7 YA	577	BUG_ON(err);
2ba466d7 YA	578	if (pde)
6cda9fa2	579	pde->rec_len = nilfs_rec_len_to_disk(to - from);
2ba466d7	580	dir->inode = 0;
2093abf9	581	nilfs_commit_chunk(page, mapping, from, to);
2ba466d7 YA	582	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
2ba466d7 YA	583	/* NILFS_I(inode)->i_flags &= ~NILFS_BTREE_FL; */
2ba466d7 YA	584	out:
	585	nilfs_put_page(page);
	586	return err;
	587	}
	588
	589	/*
	590	* Set the first fragment of directory.
	591	*/
	592	int nilfs_make_empty(struct inode inode, struct inode parent)
	593	{
	594	struct address_space *mapping = inode->i_mapping;
	595	struct page *page = grab_cache_page(mapping, 0);
	596	unsigned chunk_size = nilfs_chunk_size(inode);
	597	struct nilfs_dir_entry *de;
	598	int err;
	599	void *kaddr;
	600
	601	if (!page)
	602	return -ENOMEM;
	603
f4e420dc	604	err = nilfs_prepare_chunk(page, 0, chunk_size);
2ba466d7 YA	605	if (unlikely(err)) {
	606	unlock_page(page);
	607	goto fail;
	608	}
	609	kaddr = kmap_atomic(page, KM_USER0);
	610	memset(kaddr, 0, chunk_size);
	611	de = (struct nilfs_dir_entry *)kaddr;
	612	de->name_len = 1;
6cda9fa2	613	de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
2ba466d7 YA	614	memcpy(de->name, ".\0\0", 4);
	615	de->inode = cpu_to_le64(inode->i_ino);
	616	nilfs_set_de_type(de, inode);
	617
	618	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
	619	de->name_len = 2;
6cda9fa2	620	de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
2ba466d7 YA	621	de->inode = cpu_to_le64(parent->i_ino);
	622	memcpy(de->name, "..\0", 4);
	623	nilfs_set_de_type(de, inode);
	624	kunmap_atomic(kaddr, KM_USER0);
2093abf9	625	nilfs_commit_chunk(page, mapping, 0, chunk_size);
2ba466d7 YA	626	fail:
	627	page_cache_release(page);
	628	return err;
	629	}
	630
	631	/*
	632	* routine to check that the specified directory is empty (for rmdir)
	633	*/
	634	int nilfs_empty_dir(struct inode *inode)
	635	{
	636	struct page *page = NULL;
	637	unsigned long i, npages = dir_pages(inode);
	638
	639	for (i = 0; i < npages; i++) {
	640	char *kaddr;
	641	struct nilfs_dir_entry *de;
	642
	643	page = nilfs_get_page(inode, i);
	644	if (IS_ERR(page))
	645	continue;
	646
	647	kaddr = page_address(page);
	648	de = (struct nilfs_dir_entry *)kaddr;
	649	kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
	650
	651	while ((char *)de <= kaddr) {
	652	if (de->rec_len == 0) {
	653	nilfs_error(inode->i_sb, __func__,
	654	"zero-length directory entry "
	655	"(kaddr=%p, de=%p)\n", kaddr, de);
	656	goto not_empty;
	657	}
	658	if (de->inode != 0) {
	659	/* check for . and .. */
	660	if (de->name[0] != '.')
	661	goto not_empty;
	662	if (de->name_len > 2)
	663	goto not_empty;
	664	if (de->name_len < 2) {
	665	if (de->inode !=
	666	cpu_to_le64(inode->i_ino))
	667	goto not_empty;
	668	} else if (de->name[1] != '.')
	669	goto not_empty;
	670	}
	671	de = nilfs_next_entry(de);
	672	}
	673	nilfs_put_page(page);
	674	}
	675	return 1;
	676
	677	not_empty:
	678	nilfs_put_page(page);
	679	return 0;
	680	}
	681
828c0950	682	const struct file_operations nilfs_dir_operations = {
2ba466d7 YA	683	.llseek = generic_file_llseek,
	684	.read = generic_read_dir,
	685	.readdir = nilfs_readdir,
7a946193	686	.unlocked_ioctl = nilfs_ioctl,
2ba466d7	687	#ifdef CONFIG_COMPAT
8082d36a	688	.compat_ioctl = nilfs_ioctl,
2ba466d7 YA	689	#endif /* CONFIG_COMPAT */
	690	.fsync = nilfs_sync_file,
	691
	692	};