dir.c 17.7 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725
/*
 *  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 "ext2.h"
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/swap.h>

typedef struct ext2_dir_entry_2 ext2_dirent;

static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
{
	unsigned len = le16_to_cpu(dlen);

	if (len == EXT2_MAX_REC_LEN)
		return 1 << 16;
	return len;
}

static inline __le16 ext2_rec_len_to_disk(unsigned len)
{
	if (len == (1 << 16))
		return cpu_to_le16(EXT2_MAX_REC_LEN);
	else
		BUG_ON(len > (1 << 16));
	return cpu_to_le16(len);
}

/*
 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
 * more robust, but we have what we have
 */
static inline unsigned ext2_chunk_size(struct inode *inode)
{
	return inode->i_sb->s_blocksize;
}

static inline void ext2_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
ext2_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 ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
	struct address_space *mapping = page->mapping;
	struct inode *dir = mapping->host;
	int err = 0;

	dir->i_version++;
	block_write_end(NULL, mapping, pos, len, len, page, NULL);

	if (pos+len > dir->i_size) {
		i_size_write(dir, pos+len);
		mark_inode_dirty(dir);
	}

	if (IS_DIRSYNC(dir)) {
		err = write_one_page(page, 1);
		if (!err)
			err = ext2_sync_inode(dir);
	} else {
		unlock_page(page);
	}

	return err;
}

static void ext2_check_page(struct page *page, int quiet)
{
	struct inode *dir = page->mapping->host;
	struct super_block *sb = dir->i_sb;
	unsigned chunk_size = ext2_chunk_size(dir);
	char *kaddr = page_address(page);
	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
	unsigned offs, rec_len;
	unsigned limit = PAGE_CACHE_SIZE;
	ext2_dirent *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 - EXT2_DIR_REC_LEN(1); offs += rec_len) {
		p = (ext2_dirent *)(kaddr + offs);
		rec_len = ext2_rec_len_from_disk(p->rec_len);

		if (rec_len < EXT2_DIR_REC_LEN(1))
			goto Eshort;
		if (rec_len & 3)
			goto Ealign;
		if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
			goto Enamelen;
		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
			goto Espan;
		if (le32_to_cpu(p->inode) > max_inumber)
			goto Einumber;
	}
	if (offs != limit)
		goto Eend;
out:
	SetPageChecked(page);
	return;

	/* Too bad, we had an error */

Ebadsize:
	if (!quiet)
		ext2_error(sb, __func__,
			"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";
	goto bad_entry;
Einumber:
	error = "inode out of bounds";
bad_entry:
	if (!quiet)
		ext2_error(sb, __func__, "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) le32_to_cpu(p->inode),
			rec_len, p->name_len);
	goto fail;
Eend:
	if (!quiet) {
		p = (ext2_dirent *)(kaddr + offs);
		ext2_error(sb, "ext2_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) le32_to_cpu(p->inode));
	}
fail:
	SetPageChecked(page);
	SetPageError(page);
}

static struct page * ext2_get_page(struct inode *dir, unsigned long n,
				   int quiet)
{
	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))
			ext2_check_page(page, quiet);
		if (PageError(page))
			goto fail;
	}
	return page;

fail:
	ext2_put_page(page);
	return ERR_PTR(-EIO);
}

/*
 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 *
 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
 */
static inline int ext2_match (int len, const char * const name,
					struct ext2_dir_entry_2 * 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 inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
{
	return (ext2_dirent *)((char *)p +
			ext2_rec_len_from_disk(p->rec_len));
}

static inline unsigned 
ext2_validate_entry(char *base, unsigned offset, unsigned mask)
{
	ext2_dirent *de = (ext2_dirent*)(base + offset);
	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
	while ((char*)p < (char*)de) {
		if (p->rec_len == 0)
			break;
		p = ext2_next_entry(p);
	}
	return (char *)p - base;
}

static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
	[EXT2_FT_UNKNOWN]	= DT_UNKNOWN,
	[EXT2_FT_REG_FILE]	= DT_REG,
	[EXT2_FT_DIR]		= DT_DIR,
	[EXT2_FT_CHRDEV]	= DT_CHR,
	[EXT2_FT_BLKDEV]	= DT_BLK,
	[EXT2_FT_FIFO]		= DT_FIFO,
	[EXT2_FT_SOCK]		= DT_SOCK,
	[EXT2_FT_SYMLINK]	= DT_LNK,
};

#define S_SHIFT 12
static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
	[S_IFREG >> S_SHIFT]	= EXT2_FT_REG_FILE,
	[S_IFDIR >> S_SHIFT]	= EXT2_FT_DIR,
	[S_IFCHR >> S_SHIFT]	= EXT2_FT_CHRDEV,
	[S_IFBLK >> S_SHIFT]	= EXT2_FT_BLKDEV,
	[S_IFIFO >> S_SHIFT]	= EXT2_FT_FIFO,
	[S_IFSOCK >> S_SHIFT]	= EXT2_FT_SOCK,
	[S_IFLNK >> S_SHIFT]	= EXT2_FT_SYMLINK,
};

static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
{
	mode_t mode = inode->i_mode;
	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	else
		de->file_type = 0;
}

static int
ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
{
	loff_t pos = filp->f_pos;
	struct inode *inode = filp->f_path.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 = ~(ext2_chunk_size(inode)-1);
	unsigned char *types = NULL;
	int need_revalidate = filp->f_version != inode->i_version;

	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
		return 0;

	if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
		types = ext2_filetype_table;

	for ( ; n < npages; n++, offset = 0) {
		char *kaddr, *limit;
		ext2_dirent *de;
		struct page *page = ext2_get_page(inode, n, 0);

		if (IS_ERR(page)) {
			ext2_error(sb, __func__,
				   "bad page in #%lu",
				   inode->i_ino);
			filp->f_pos += PAGE_CACHE_SIZE - offset;
			return PTR_ERR(page);
		}
		kaddr = page_address(page);
		if (unlikely(need_revalidate)) {
			if (offset) {
				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
			}
			filp->f_version = inode->i_version;
			need_revalidate = 0;
		}
		de = (ext2_dirent *)(kaddr+offset);
		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
			if (de->rec_len == 0) {
				ext2_error(sb, __func__,
					"zero-length directory entry");
				ext2_put_page(page);
				return -EIO;
			}
			if (de->inode) {
				int over;
				unsigned char d_type = DT_UNKNOWN;

				if (types && de->file_type < EXT2_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,
						le32_to_cpu(de->inode), d_type);
				if (over) {
					ext2_put_page(page);
					return 0;
				}
			}
			filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
		}
		ext2_put_page(page);
	}
	return 0;
}

/*
 *	ext2_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 ext2_dir_entry_2 *ext2_find_entry (struct inode * dir,
			struct qstr *child, struct page ** res_page)
{
	const char *name = child->name;
	int namelen = child->len;
	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	unsigned long start, n;
	unsigned long npages = dir_pages(dir);
	struct page *page = NULL;
	struct ext2_inode_info *ei = EXT2_I(dir);
	ext2_dirent * de;
	int dir_has_error = 0;

	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 = ext2_get_page(dir, n, dir_has_error);
		if (!IS_ERR(page)) {
			kaddr = page_address(page);
			de = (ext2_dirent *) kaddr;
			kaddr += ext2_last_byte(dir, n) - reclen;
			while ((char *) de <= kaddr) {
				if (de->rec_len == 0) {
					ext2_error(dir->i_sb, __func__,
						"zero-length directory entry");
					ext2_put_page(page);
					goto out;
				}
				if (ext2_match (namelen, name, de))
					goto found;
				de = ext2_next_entry(de);
			}
			ext2_put_page(page);
		} else
			dir_has_error = 1;

		if (++n >= npages)
			n = 0;
		/* next page is past the blocks we've got */
		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
			ext2_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 ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
{
	struct page *page = ext2_get_page(dir, 0, 0);
	ext2_dirent *de = NULL;

	if (!IS_ERR(page)) {
		de = ext2_next_entry((ext2_dirent *) page_address(page));
		*p = page;
	}
	return de;
}

ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child)
{
	ino_t res = 0;
	struct ext2_dir_entry_2 *de;
	struct page *page;
	
	de = ext2_find_entry (dir, child, &page);
	if (de) {
		res = le32_to_cpu(de->inode);
		ext2_put_page(page);
	}
	return res;
}

/* Releases the page */
void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
		   struct page *page, struct inode *inode, int update_times)
{
	loff_t pos = page_offset(page) +
			(char *) de - (char *) page_address(page);
	unsigned len = ext2_rec_len_from_disk(de->rec_len);
	int err;

	lock_page(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, len,
				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	BUG_ON(err);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type(de, inode);
	err = ext2_commit_chunk(page, pos, len);
	ext2_put_page(page);
	if (update_times)
		dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
}

/*
 *	Parent is locked.
 */
int ext2_add_link (struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = dentry->d_parent->d_inode;
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned chunk_size = ext2_chunk_size(dir);
	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	unsigned short rec_len, name_len;
	struct page *page = NULL;
	ext2_dirent * de;
	unsigned long npages = dir_pages(dir);
	unsigned long n;
	char *kaddr;
	loff_t pos;
	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 = ext2_get_page(dir, n, 0);
		err = PTR_ERR(page);
		if (IS_ERR(page))
			goto out;
		lock_page(page);
		kaddr = page_address(page);
		dir_end = kaddr + ext2_last_byte(dir, n);
		de = (ext2_dirent *)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 = ext2_rec_len_to_disk(chunk_size);
				de->inode = 0;
				goto got_it;
			}
			if (de->rec_len == 0) {
				ext2_error(dir->i_sb, __func__,
					"zero-length directory entry");
				err = -EIO;
				goto out_unlock;
			}
			err = -EEXIST;
			if (ext2_match (namelen, name, de))
				goto out_unlock;
			name_len = EXT2_DIR_REC_LEN(de->name_len);
			rec_len = ext2_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 = (ext2_dirent *) ((char *) de + rec_len);
		}
		unlock_page(page);
		ext2_put_page(page);
	}
	BUG();
	return -EINVAL;

got_it:
	pos = page_offset(page) +
		(char*)de - (char*)page_address(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
							&page, NULL);
	if (err)
		goto out_unlock;
	if (de->inode) {
		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
		de->rec_len = ext2_rec_len_to_disk(name_len);
		de = de1;
	}
	de->name_len = namelen;
	memcpy(de->name, name, namelen);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type (de, inode);
	err = ext2_commit_chunk(page, pos, rec_len);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
	/* OFFSET_CACHE */
out_put:
	ext2_put_page(page);
out:
	return err;
out_unlock:
	unlock_page(page);
	goto out_put;
}

/*
 * ext2_delete_entry deletes a directory entry by merging it with the
 * previous entry. Page is up-to-date. Releases the page.
 */
int ext2_delete_entry (struct ext2_dir_entry_2 * 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) & ~(ext2_chunk_size(inode)-1);
	unsigned to = ((char *)dir - kaddr) +
				ext2_rec_len_from_disk(dir->rec_len);
	loff_t pos;
	ext2_dirent * pde = NULL;
	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
	int err;

	while ((char*)de < (char*)dir) {
		if (de->rec_len == 0) {
			ext2_error(inode->i_sb, __func__,
				"zero-length directory entry");
			err = -EIO;
			goto out;
		}
		pde = de;
		de = ext2_next_entry(de);
	}
	if (pde)
		from = (char*)pde - (char*)page_address(page);
	pos = page_offset(page) + from;
	lock_page(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, to - from, 0,
							&page, NULL);
	BUG_ON(err);
	if (pde)
		pde->rec_len = ext2_rec_len_to_disk(to - from);
	dir->inode = 0;
	err = ext2_commit_chunk(page, pos, to - from);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(inode);
out:
	ext2_put_page(page);
	return err;
}

/*
 * Set the first fragment of directory.
 */
int ext2_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 = ext2_chunk_size(inode);
	struct ext2_dir_entry_2 * de;
	int err;
	void *kaddr;

	if (!page)
		return -ENOMEM;

	err = __ext2_write_begin(NULL, page->mapping, 0, chunk_size, 0,
							&page, NULL);
	if (err) {
		unlock_page(page);
		goto fail;
	}
	kaddr = kmap_atomic(page, KM_USER0);
	memset(kaddr, 0, chunk_size);
	de = (struct ext2_dir_entry_2 *)kaddr;
	de->name_len = 1;
	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
	memcpy (de->name, ".\0\0", 4);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type (de, inode);

	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
	de->name_len = 2;
	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
	de->inode = cpu_to_le32(parent->i_ino);
	memcpy (de->name, "..\0", 4);
	ext2_set_de_type (de, inode);
	kunmap_atomic(kaddr, KM_USER0);
	err = ext2_commit_chunk(page, 0, chunk_size);
fail:
	page_cache_release(page);
	return err;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int ext2_empty_dir (struct inode * inode)
{
	struct page *page = NULL;
	unsigned long i, npages = dir_pages(inode);
	int dir_has_error = 0;

	for (i = 0; i < npages; i++) {
		char *kaddr;
		ext2_dirent * de;
		page = ext2_get_page(inode, i, dir_has_error);

		if (IS_ERR(page)) {
			dir_has_error = 1;
			continue;
		}

		kaddr = page_address(page);
		de = (ext2_dirent *)kaddr;
		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);

		while ((char *)de <= kaddr) {
			if (de->rec_len == 0) {
				ext2_error(inode->i_sb, __func__,
					"zero-length directory entry");
				printk("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_le32(inode->i_ino))
						goto not_empty;
				} else if (de->name[1] != '.')
					goto not_empty;
			}
			de = ext2_next_entry(de);
		}
		ext2_put_page(page);
	}
	return 1;

not_empty:
	ext2_put_page(page);
	return 0;
}

const struct file_operations ext2_dir_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.readdir	= ext2_readdir,
	.unlocked_ioctl = ext2_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= ext2_compat_ioctl,
#endif
	.fsync		= simple_fsync,
};