root/fs/ext2/dir.c

DEFINITIONS

1. ext2_rec_len_from_disk
2. ext2_rec_len_to_disk
3. ext2_chunk_size
4. ext2_put_page
5. ext2_last_byte
6. ext2_commit_chunk
7. ext2_check_page
8. ext2_get_page
9. ext2_match
10. ext2_next_entry
11. ext2_validate_entry
12. ext2_set_de_type
13. ext2_readdir
14. ext2_find_entry
15. ext2_dotdot
16. ext2_inode_by_name
17. ext2_prepare_chunk
18. ext2_set_link
19. ext2_add_link
20. ext2_delete_entry
21. ext2_make_empty
22. ext2_empty_dir

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext2/dir.c
   4  *
   5  * Copyright (C) 1992, 1993, 1994, 1995
   6  * Remy Card (card@masi.ibp.fr)
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  from
  11  *
  12  *  linux/fs/minix/dir.c
  13  *
  14  *  Copyright (C) 1991, 1992  Linus Torvalds
  15  *
  16  *  ext2 directory handling functions
  17  *
  18  *  Big-endian to little-endian byte-swapping/bitmaps by
  19  *        David S. Miller (davem@caip.rutgers.edu), 1995
  20  *
  21  * All code that works with directory layout had been switched to pagecache
  22  * and moved here. AV
  23  */
  24 
  25 #include "ext2.h"
  26 #include <linux/buffer_head.h>
  27 #include <linux/pagemap.h>
  28 #include <linux/swap.h>
  29 #include <linux/iversion.h>
  30 
  31 typedef struct ext2_dir_entry_2 ext2_dirent;
  32 
  33 /*
  34  * Tests against MAX_REC_LEN etc were put in place for 64k block
  35  * sizes; if that is not possible on this arch, we can skip
  36  * those tests and speed things up.
  37  */
  38 static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
  39 {
  40         unsigned len = le16_to_cpu(dlen);
  41 
  42 #if (PAGE_SIZE >= 65536)
  43         if (len == EXT2_MAX_REC_LEN)
  44                 return 1 << 16;
  45 #endif
  46         return len;
  47 }
  48 
  49 static inline __le16 ext2_rec_len_to_disk(unsigned len)
  50 {
  51 #if (PAGE_SIZE >= 65536)
  52         if (len == (1 << 16))
  53                 return cpu_to_le16(EXT2_MAX_REC_LEN);
  54         else
  55                 BUG_ON(len > (1 << 16));
  56 #endif
  57         return cpu_to_le16(len);
  58 }
  59 
  60 /*
  61  * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
  62  * more robust, but we have what we have
  63  */
  64 static inline unsigned ext2_chunk_size(struct inode *inode)
  65 {
  66         return inode->i_sb->s_blocksize;
  67 }
  68 
  69 static inline void ext2_put_page(struct page *page)
  70 {
  71         kunmap(page);
  72         put_page(page);
  73 }
  74 
  75 /*
  76  * Return the offset into page `page_nr' of the last valid
  77  * byte in that page, plus one.
  78  */
  79 static unsigned
  80 ext2_last_byte(struct inode *inode, unsigned long page_nr)
  81 {
  82         unsigned last_byte = inode->i_size;
  83 
  84         last_byte -= page_nr << PAGE_SHIFT;
  85         if (last_byte > PAGE_SIZE)
  86                 last_byte = PAGE_SIZE;
  87         return last_byte;
  88 }
  89 
  90 static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
  91 {
  92         struct address_space *mapping = page->mapping;
  93         struct inode *dir = mapping->host;
  94         int err = 0;
  95 
  96         inode_inc_iversion(dir);
  97         block_write_end(NULL, mapping, pos, len, len, page, NULL);
  98 
  99         if (pos+len > dir->i_size) {
 100                 i_size_write(dir, pos+len);
 101                 mark_inode_dirty(dir);
 102         }
 103 
 104         if (IS_DIRSYNC(dir)) {
 105                 err = write_one_page(page);
 106                 if (!err)
 107                         err = sync_inode_metadata(dir, 1);
 108         } else {
 109                 unlock_page(page);
 110         }
 111 
 112         return err;
 113 }
 114 
 115 static bool ext2_check_page(struct page *page, int quiet)
 116 {
 117         struct inode *dir = page->mapping->host;
 118         struct super_block *sb = dir->i_sb;
 119         unsigned chunk_size = ext2_chunk_size(dir);
 120         char *kaddr = page_address(page);
 121         u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
 122         unsigned offs, rec_len;
 123         unsigned limit = PAGE_SIZE;
 124         ext2_dirent *p;
 125         char *error;
 126 
 127         if ((dir->i_size >> PAGE_SHIFT) == page->index) {
 128                 limit = dir->i_size & ~PAGE_MASK;
 129                 if (limit & (chunk_size - 1))
 130                         goto Ebadsize;
 131                 if (!limit)
 132                         goto out;
 133         }
 134         for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
 135                 p = (ext2_dirent *)(kaddr + offs);
 136                 rec_len = ext2_rec_len_from_disk(p->rec_len);
 137 
 138                 if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
 139                         goto Eshort;
 140                 if (unlikely(rec_len & 3))
 141                         goto Ealign;
 142                 if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
 143                         goto Enamelen;
 144                 if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
 145                         goto Espan;
 146                 if (unlikely(le32_to_cpu(p->inode) > max_inumber))
 147                         goto Einumber;
 148         }
 149         if (offs != limit)
 150                 goto Eend;
 151 out:
 152         SetPageChecked(page);
 153         return true;
 154 
 155         /* Too bad, we had an error */
 156 
 157 Ebadsize:
 158         if (!quiet)
 159                 ext2_error(sb, __func__,
 160                         "size of directory #%lu is not a multiple "
 161                         "of chunk size", dir->i_ino);
 162         goto fail;
 163 Eshort:
 164         error = "rec_len is smaller than minimal";
 165         goto bad_entry;
 166 Ealign:
 167         error = "unaligned directory entry";
 168         goto bad_entry;
 169 Enamelen:
 170         error = "rec_len is too small for name_len";
 171         goto bad_entry;
 172 Espan:
 173         error = "directory entry across blocks";
 174         goto bad_entry;
 175 Einumber:
 176         error = "inode out of bounds";
 177 bad_entry:
 178         if (!quiet)
 179                 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
 180                         "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
 181                         dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
 182                         (unsigned long) le32_to_cpu(p->inode),
 183                         rec_len, p->name_len);
 184         goto fail;
 185 Eend:
 186         if (!quiet) {
 187                 p = (ext2_dirent *)(kaddr + offs);
 188                 ext2_error(sb, "ext2_check_page",
 189                         "entry in directory #%lu spans the page boundary"
 190                         "offset=%lu, inode=%lu",
 191                         dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
 192                         (unsigned long) le32_to_cpu(p->inode));
 193         }
 194 fail:
 195         SetPageError(page);
 196         return false;
 197 }
 198 
 199 static struct page * ext2_get_page(struct inode *dir, unsigned long n,
 200                                    int quiet)
 201 {
 202         struct address_space *mapping = dir->i_mapping;
 203         struct page *page = read_mapping_page(mapping, n, NULL);
 204         if (!IS_ERR(page)) {
 205                 kmap(page);
 206                 if (unlikely(!PageChecked(page))) {
 207                         if (PageError(page) || !ext2_check_page(page, quiet))
 208                                 goto fail;
 209                 }
 210         }
 211         return page;
 212 
 213 fail:
 214         ext2_put_page(page);
 215         return ERR_PTR(-EIO);
 216 }
 217 
 218 /*
 219  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 220  *
 221  * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
 222  */
 223 static inline int ext2_match (int len, const char * const name,
 224                                         struct ext2_dir_entry_2 * de)
 225 {
 226         if (len != de->name_len)
 227                 return 0;
 228         if (!de->inode)
 229                 return 0;
 230         return !memcmp(name, de->name, len);
 231 }
 232 
 233 /*
 234  * p is at least 6 bytes before the end of page
 235  */
 236 static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
 237 {
 238         return (ext2_dirent *)((char *)p +
 239                         ext2_rec_len_from_disk(p->rec_len));
 240 }
 241 
 242 static inline unsigned 
 243 ext2_validate_entry(char *base, unsigned offset, unsigned mask)
 244 {
 245         ext2_dirent *de = (ext2_dirent*)(base + offset);
 246         ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
 247         while ((char*)p < (char*)de) {
 248                 if (p->rec_len == 0)
 249                         break;
 250                 p = ext2_next_entry(p);
 251         }
 252         return (char *)p - base;
 253 }
 254 
 255 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
 256 {
 257         if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
 258                 de->file_type = fs_umode_to_ftype(inode->i_mode);
 259         else
 260                 de->file_type = 0;
 261 }
 262 
 263 static int
 264 ext2_readdir(struct file *file, struct dir_context *ctx)
 265 {
 266         loff_t pos = ctx->pos;
 267         struct inode *inode = file_inode(file);
 268         struct super_block *sb = inode->i_sb;
 269         unsigned int offset = pos & ~PAGE_MASK;
 270         unsigned long n = pos >> PAGE_SHIFT;
 271         unsigned long npages = dir_pages(inode);
 272         unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
 273         bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
 274         bool has_filetype;
 275 
 276         if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
 277                 return 0;
 278 
 279         has_filetype =
 280                 EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);
 281 
 282         for ( ; n < npages; n++, offset = 0) {
 283                 char *kaddr, *limit;
 284                 ext2_dirent *de;
 285                 struct page *page = ext2_get_page(inode, n, 0);
 286 
 287                 if (IS_ERR(page)) {
 288                         ext2_error(sb, __func__,
 289                                    "bad page in #%lu",
 290                                    inode->i_ino);
 291                         ctx->pos += PAGE_SIZE - offset;
 292                         return PTR_ERR(page);
 293                 }
 294                 kaddr = page_address(page);
 295                 if (unlikely(need_revalidate)) {
 296                         if (offset) {
 297                                 offset = ext2_validate_entry(kaddr, offset, chunk_mask);
 298                                 ctx->pos = (n<<PAGE_SHIFT) + offset;
 299                         }
 300                         file->f_version = inode_query_iversion(inode);
 301                         need_revalidate = false;
 302                 }
 303                 de = (ext2_dirent *)(kaddr+offset);
 304                 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
 305                 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
 306                         if (de->rec_len == 0) {
 307                                 ext2_error(sb, __func__,
 308                                         "zero-length directory entry");
 309                                 ext2_put_page(page);
 310                                 return -EIO;
 311                         }
 312                         if (de->inode) {
 313                                 unsigned char d_type = DT_UNKNOWN;
 314 
 315                                 if (has_filetype)
 316                                         d_type = fs_ftype_to_dtype(de->file_type);
 317 
 318                                 if (!dir_emit(ctx, de->name, de->name_len,
 319                                                 le32_to_cpu(de->inode),
 320                                                 d_type)) {
 321                                         ext2_put_page(page);
 322                                         return 0;
 323                                 }
 324                         }
 325                         ctx->pos += ext2_rec_len_from_disk(de->rec_len);
 326                 }
 327                 ext2_put_page(page);
 328         }
 329         return 0;
 330 }
 331 
 332 /*
 333  *      ext2_find_entry()
 334  *
 335  * finds an entry in the specified directory with the wanted name. It
 336  * returns the page in which the entry was found (as a parameter - res_page),
 337  * and the entry itself. Page is returned mapped and unlocked.
 338  * Entry is guaranteed to be valid.
 339  */
 340 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
 341                         const struct qstr *child, struct page **res_page)
 342 {
 343         const char *name = child->name;
 344         int namelen = child->len;
 345         unsigned reclen = EXT2_DIR_REC_LEN(namelen);
 346         unsigned long start, n;
 347         unsigned long npages = dir_pages(dir);
 348         struct page *page = NULL;
 349         struct ext2_inode_info *ei = EXT2_I(dir);
 350         ext2_dirent * de;
 351         int dir_has_error = 0;
 352 
 353         if (npages == 0)
 354                 goto out;
 355 
 356         /* OFFSET_CACHE */
 357         *res_page = NULL;
 358 
 359         start = ei->i_dir_start_lookup;
 360         if (start >= npages)
 361                 start = 0;
 362         n = start;
 363         do {
 364                 char *kaddr;
 365                 page = ext2_get_page(dir, n, dir_has_error);
 366                 if (!IS_ERR(page)) {
 367                         kaddr = page_address(page);
 368                         de = (ext2_dirent *) kaddr;
 369                         kaddr += ext2_last_byte(dir, n) - reclen;
 370                         while ((char *) de <= kaddr) {
 371                                 if (de->rec_len == 0) {
 372                                         ext2_error(dir->i_sb, __func__,
 373                                                 "zero-length directory entry");
 374                                         ext2_put_page(page);
 375                                         goto out;
 376                                 }
 377                                 if (ext2_match (namelen, name, de))
 378                                         goto found;
 379                                 de = ext2_next_entry(de);
 380                         }
 381                         ext2_put_page(page);
 382                 } else
 383                         dir_has_error = 1;
 384 
 385                 if (++n >= npages)
 386                         n = 0;
 387                 /* next page is past the blocks we've got */
 388                 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
 389                         ext2_error(dir->i_sb, __func__,
 390                                 "dir %lu size %lld exceeds block count %llu",
 391                                 dir->i_ino, dir->i_size,
 392                                 (unsigned long long)dir->i_blocks);
 393                         goto out;
 394                 }
 395         } while (n != start);
 396 out:
 397         return NULL;
 398 
 399 found:
 400         *res_page = page;
 401         ei->i_dir_start_lookup = n;
 402         return de;
 403 }
 404 
 405 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
 406 {
 407         struct page *page = ext2_get_page(dir, 0, 0);
 408         ext2_dirent *de = NULL;
 409 
 410         if (!IS_ERR(page)) {
 411                 de = ext2_next_entry((ext2_dirent *) page_address(page));
 412                 *p = page;
 413         }
 414         return de;
 415 }
 416 
 417 ino_t ext2_inode_by_name(struct inode *dir, const struct qstr *child)
 418 {
 419         ino_t res = 0;
 420         struct ext2_dir_entry_2 *de;
 421         struct page *page;
 422         
 423         de = ext2_find_entry (dir, child, &page);
 424         if (de) {
 425                 res = le32_to_cpu(de->inode);
 426                 ext2_put_page(page);
 427         }
 428         return res;
 429 }
 430 
 431 static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
 432 {
 433         return __block_write_begin(page, pos, len, ext2_get_block);
 434 }
 435 
 436 /* Releases the page */
 437 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
 438                    struct page *page, struct inode *inode, int update_times)
 439 {
 440         loff_t pos = page_offset(page) +
 441                         (char *) de - (char *) page_address(page);
 442         unsigned len = ext2_rec_len_from_disk(de->rec_len);
 443         int err;
 444 
 445         lock_page(page);
 446         err = ext2_prepare_chunk(page, pos, len);
 447         BUG_ON(err);
 448         de->inode = cpu_to_le32(inode->i_ino);
 449         ext2_set_de_type(de, inode);
 450         err = ext2_commit_chunk(page, pos, len);
 451         ext2_put_page(page);
 452         if (update_times)
 453                 dir->i_mtime = dir->i_ctime = current_time(dir);
 454         EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
 455         mark_inode_dirty(dir);
 456 }
 457 
 458 /*
 459  *      Parent is locked.
 460  */
 461 int ext2_add_link (struct dentry *dentry, struct inode *inode)
 462 {
 463         struct inode *dir = d_inode(dentry->d_parent);
 464         const char *name = dentry->d_name.name;
 465         int namelen = dentry->d_name.len;
 466         unsigned chunk_size = ext2_chunk_size(dir);
 467         unsigned reclen = EXT2_DIR_REC_LEN(namelen);
 468         unsigned short rec_len, name_len;
 469         struct page *page = NULL;
 470         ext2_dirent * de;
 471         unsigned long npages = dir_pages(dir);
 472         unsigned long n;
 473         char *kaddr;
 474         loff_t pos;
 475         int err;
 476 
 477         /*
 478          * We take care of directory expansion in the same loop.
 479          * This code plays outside i_size, so it locks the page
 480          * to protect that region.
 481          */
 482         for (n = 0; n <= npages; n++) {
 483                 char *dir_end;
 484 
 485                 page = ext2_get_page(dir, n, 0);
 486                 err = PTR_ERR(page);
 487                 if (IS_ERR(page))
 488                         goto out;
 489                 lock_page(page);
 490                 kaddr = page_address(page);
 491                 dir_end = kaddr + ext2_last_byte(dir, n);
 492                 de = (ext2_dirent *)kaddr;
 493                 kaddr += PAGE_SIZE - reclen;
 494                 while ((char *)de <= kaddr) {
 495                         if ((char *)de == dir_end) {
 496                                 /* We hit i_size */
 497                                 name_len = 0;
 498                                 rec_len = chunk_size;
 499                                 de->rec_len = ext2_rec_len_to_disk(chunk_size);
 500                                 de->inode = 0;
 501                                 goto got_it;
 502                         }
 503                         if (de->rec_len == 0) {
 504                                 ext2_error(dir->i_sb, __func__,
 505                                         "zero-length directory entry");
 506                                 err = -EIO;
 507                                 goto out_unlock;
 508                         }
 509                         err = -EEXIST;
 510                         if (ext2_match (namelen, name, de))
 511                                 goto out_unlock;
 512                         name_len = EXT2_DIR_REC_LEN(de->name_len);
 513                         rec_len = ext2_rec_len_from_disk(de->rec_len);
 514                         if (!de->inode && rec_len >= reclen)
 515                                 goto got_it;
 516                         if (rec_len >= name_len + reclen)
 517                                 goto got_it;
 518                         de = (ext2_dirent *) ((char *) de + rec_len);
 519                 }
 520                 unlock_page(page);
 521                 ext2_put_page(page);
 522         }
 523         BUG();
 524         return -EINVAL;
 525 
 526 got_it:
 527         pos = page_offset(page) +
 528                 (char*)de - (char*)page_address(page);
 529         err = ext2_prepare_chunk(page, pos, rec_len);
 530         if (err)
 531                 goto out_unlock;
 532         if (de->inode) {
 533                 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
 534                 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
 535                 de->rec_len = ext2_rec_len_to_disk(name_len);
 536                 de = de1;
 537         }
 538         de->name_len = namelen;
 539         memcpy(de->name, name, namelen);
 540         de->inode = cpu_to_le32(inode->i_ino);
 541         ext2_set_de_type (de, inode);
 542         err = ext2_commit_chunk(page, pos, rec_len);
 543         dir->i_mtime = dir->i_ctime = current_time(dir);
 544         EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
 545         mark_inode_dirty(dir);
 546         /* OFFSET_CACHE */
 547 out_put:
 548         ext2_put_page(page);
 549 out:
 550         return err;
 551 out_unlock:
 552         unlock_page(page);
 553         goto out_put;
 554 }
 555 
 556 /*
 557  * ext2_delete_entry deletes a directory entry by merging it with the
 558  * previous entry. Page is up-to-date. Releases the page.
 559  */
 560 int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
 561 {
 562         struct inode *inode = page->mapping->host;
 563         char *kaddr = page_address(page);
 564         unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
 565         unsigned to = ((char *)dir - kaddr) +
 566                                 ext2_rec_len_from_disk(dir->rec_len);
 567         loff_t pos;
 568         ext2_dirent * pde = NULL;
 569         ext2_dirent * de = (ext2_dirent *) (kaddr + from);
 570         int err;
 571 
 572         while ((char*)de < (char*)dir) {
 573                 if (de->rec_len == 0) {
 574                         ext2_error(inode->i_sb, __func__,
 575                                 "zero-length directory entry");
 576                         err = -EIO;
 577                         goto out;
 578                 }
 579                 pde = de;
 580                 de = ext2_next_entry(de);
 581         }
 582         if (pde)
 583                 from = (char*)pde - (char*)page_address(page);
 584         pos = page_offset(page) + from;
 585         lock_page(page);
 586         err = ext2_prepare_chunk(page, pos, to - from);
 587         BUG_ON(err);
 588         if (pde)
 589                 pde->rec_len = ext2_rec_len_to_disk(to - from);
 590         dir->inode = 0;
 591         err = ext2_commit_chunk(page, pos, to - from);
 592         inode->i_ctime = inode->i_mtime = current_time(inode);
 593         EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
 594         mark_inode_dirty(inode);
 595 out:
 596         ext2_put_page(page);
 597         return err;
 598 }
 599 
 600 /*
 601  * Set the first fragment of directory.
 602  */
 603 int ext2_make_empty(struct inode *inode, struct inode *parent)
 604 {
 605         struct page *page = grab_cache_page(inode->i_mapping, 0);
 606         unsigned chunk_size = ext2_chunk_size(inode);
 607         struct ext2_dir_entry_2 * de;
 608         int err;
 609         void *kaddr;
 610 
 611         if (!page)
 612                 return -ENOMEM;
 613 
 614         err = ext2_prepare_chunk(page, 0, chunk_size);
 615         if (err) {
 616                 unlock_page(page);
 617                 goto fail;
 618         }
 619         kaddr = kmap_atomic(page);
 620         memset(kaddr, 0, chunk_size);
 621         de = (struct ext2_dir_entry_2 *)kaddr;
 622         de->name_len = 1;
 623         de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
 624         memcpy (de->name, ".\0\0", 4);
 625         de->inode = cpu_to_le32(inode->i_ino);
 626         ext2_set_de_type (de, inode);
 627 
 628         de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
 629         de->name_len = 2;
 630         de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
 631         de->inode = cpu_to_le32(parent->i_ino);
 632         memcpy (de->name, "..\0", 4);
 633         ext2_set_de_type (de, inode);
 634         kunmap_atomic(kaddr);
 635         err = ext2_commit_chunk(page, 0, chunk_size);
 636 fail:
 637         put_page(page);
 638         return err;
 639 }
 640 
 641 /*
 642  * routine to check that the specified directory is empty (for rmdir)
 643  */
 644 int ext2_empty_dir (struct inode * inode)
 645 {
 646         struct page *page = NULL;
 647         unsigned long i, npages = dir_pages(inode);
 648         int dir_has_error = 0;
 649 
 650         for (i = 0; i < npages; i++) {
 651                 char *kaddr;
 652                 ext2_dirent * de;
 653                 page = ext2_get_page(inode, i, dir_has_error);
 654 
 655                 if (IS_ERR(page)) {
 656                         dir_has_error = 1;
 657                         continue;
 658                 }
 659 
 660                 kaddr = page_address(page);
 661                 de = (ext2_dirent *)kaddr;
 662                 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
 663 
 664                 while ((char *)de <= kaddr) {
 665                         if (de->rec_len == 0) {
 666                                 ext2_error(inode->i_sb, __func__,
 667                                         "zero-length directory entry");
 668                                 printk("kaddr=%p, de=%p\n", kaddr, de);
 669                                 goto not_empty;
 670                         }
 671                         if (de->inode != 0) {
 672                                 /* check for . and .. */
 673                                 if (de->name[0] != '.')
 674                                         goto not_empty;
 675                                 if (de->name_len > 2)
 676                                         goto not_empty;
 677                                 if (de->name_len < 2) {
 678                                         if (de->inode !=
 679                                             cpu_to_le32(inode->i_ino))
 680                                                 goto not_empty;
 681                                 } else if (de->name[1] != '.')
 682                                         goto not_empty;
 683                         }
 684                         de = ext2_next_entry(de);
 685                 }
 686                 ext2_put_page(page);
 687         }
 688         return 1;
 689 
 690 not_empty:
 691         ext2_put_page(page);
 692         return 0;
 693 }
 694 
 695 const struct file_operations ext2_dir_operations = {
 696         .llseek         = generic_file_llseek,
 697         .read           = generic_read_dir,
 698         .iterate_shared = ext2_readdir,
 699         .unlocked_ioctl = ext2_ioctl,
 700 #ifdef CONFIG_COMPAT
 701         .compat_ioctl   = ext2_compat_ioctl,
 702 #endif
 703         .fsync          = ext2_fsync,
 704 };