fs/nilfs2/dir.c

   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>
  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
  83 static int nilfs_prepare_chunk_uninterruptible(struct page *page,
  84                                                struct address_space *mapping,
  85                                                unsigned from, unsigned to)
  86 {
  87         loff_t pos = page_offset(page) + from;
  88         return block_write_begin(NULL, mapping, pos, to - from,
  89                                  AOP_FLAG_UNINTERRUPTIBLE, &page,
  90                                  NULL, nilfs_get_block);
  91 }
  92
  93 static int nilfs_prepare_chunk(struct page *page,
  94                                struct address_space *mapping,
  95                                unsigned from, unsigned to)
  96 {
  97         loff_t pos = page_offset(page) + from;
  98         return block_write_begin(NULL, mapping, pos, to - from, 0, &page,
  99                                  NULL, nilfs_get_block);
 100 }
 101
 102 static int nilfs_commit_chunk(struct page *page,
 103                               struct address_space *mapping,
 104                               unsigned from, unsigned to)
 105 {
 106         struct inode *dir = mapping->host;
 107         struct nilfs_sb_info *sbi = NILFS_SB(dir->i_sb);
 108         loff_t pos = page_offset(page) + from;
 109         unsigned len = to - from;
 110         unsigned nr_dirty, copied;
 111         int err;
 112
 113         nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
 114         copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
 115         if (pos + copied > dir->i_size) {
 116                 i_size_write(dir, pos + copied);
 117                 mark_inode_dirty(dir);
 118         }
 119         if (IS_DIRSYNC(dir))
 120                 nilfs_set_transaction_flag(NILFS_TI_SYNC);
 121         err = nilfs_set_file_dirty(sbi, dir, nr_dirty);
 122         unlock_page(page);
 123         return err;
 124 }
 125
 126 static void nilfs_check_page(struct page *page)
 127 {
 128         struct inode *dir = page->mapping->host;
 129         struct super_block *sb = dir->i_sb;
 130         unsigned chunk_size = nilfs_chunk_size(dir);
 131         char *kaddr = page_address(page);
 132         unsigned offs, rec_len;
 133         unsigned limit = PAGE_CACHE_SIZE;
 134         struct nilfs_dir_entry *p;
 135         char *error;
 136
 137         if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
 138                 limit = dir->i_size & ~PAGE_CACHE_MASK;
 139                 if (limit & (chunk_size - 1))
 140                         goto Ebadsize;
 141                 if (!limit)
 142                         goto out;
 143         }
 144         for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
 145                 p = (struct nilfs_dir_entry *)(kaddr + offs);
 146                 rec_len = le16_to_cpu(p->rec_len);
 147
 148                 if (rec_len < NILFS_DIR_REC_LEN(1))
 149                         goto Eshort;
 150                 if (rec_len & 3)
 151                         goto Ealign;
 152                 if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
 153                         goto Enamelen;
 154                 if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
 155                         goto Espan;
 156         }
 157         if (offs != limit)
 158                 goto Eend;
 159 out:
 160         SetPageChecked(page);
 161         return;
 162
 163         /* Too bad, we had an error */
 164
 165 Ebadsize:
 166         nilfs_error(sb, "nilfs_check_page",
 167                     "size of directory #%lu is not a multiple of chunk size",
 168                     dir->i_ino
 169         );
 170         goto fail;
 171 Eshort:
 172         error = "rec_len is smaller than minimal";
 173         goto bad_entry;
 174 Ealign:
 175         error = "unaligned directory entry";
 176         goto bad_entry;
 177 Enamelen:
 178         error = "rec_len is too small for name_len";
 179         goto bad_entry;
 180 Espan:
 181         error = "directory entry across blocks";
 182 bad_entry:
 183         nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
 184                     "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
 185                     dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
 186                     (unsigned long) le64_to_cpu(p->inode),
 187                     rec_len, p->name_len);
 188         goto fail;
 189 Eend:
 190         p = (struct nilfs_dir_entry *)(kaddr + offs);
 191         nilfs_error(sb, "nilfs_check_page",
 192                     "entry in directory #%lu spans the page boundary"
 193                     "offset=%lu, inode=%lu",
 194                     dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
 195                     (unsigned long) le64_to_cpu(p->inode));
 196 fail:
 197         SetPageChecked(page);
 198         SetPageError(page);
 199 }
 200
 201 static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
 202 {
 203         struct address_space *mapping = dir->i_mapping;
 204         struct page *page = read_cache_page(mapping, n,
 205                                 (filler_t *)mapping->a_ops->readpage, NULL);
 206         if (!IS_ERR(page)) {
 207                 wait_on_page_locked(page);
 208                 kmap(page);
 209                 if (!PageUptodate(page))
 210                         goto fail;
 211                 if (!PageChecked(page))
 212                         nilfs_check_page(page);
 213                 if (PageError(page))
 214                         goto fail;
 215         }
 216         return page;
 217
 218 fail:
 219         nilfs_put_page(page);
 220         return ERR_PTR(-EIO);
 221 }
 222
 223 /*
 224  * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
 225  *
 226  * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
 227  */
 228 static int
 229 nilfs_match(int len, const char * const name, struct nilfs_dir_entry *de)
 230 {
 231         if (len != de->name_len)
 232                 return 0;
 233         if (!de->inode)
 234                 return 0;
 235         return !memcmp(name, de->name, len);
 236 }
 237
 238 /*
 239  * p is at least 6 bytes before the end of page
 240  */
 241 static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
 242 {
 243         return (struct nilfs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
 244 }
 245
 246 static unsigned char
 247 nilfs_filetype_table[NILFS_FT_MAX] = {
 248         [NILFS_FT_UNKNOWN]      = DT_UNKNOWN,
 249         [NILFS_FT_REG_FILE]     = DT_REG,
 250         [NILFS_FT_DIR]          = DT_DIR,
 251         [NILFS_FT_CHRDEV]       = DT_CHR,
 252         [NILFS_FT_BLKDEV]       = DT_BLK,
 253         [NILFS_FT_FIFO]         = DT_FIFO,
 254         [NILFS_FT_SOCK]         = DT_SOCK,
 255         [NILFS_FT_SYMLINK]      = DT_LNK,
 256 };
 257
 258 #define S_SHIFT 12
 259 static unsigned char
 260 nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
 261         [S_IFREG >> S_SHIFT]    = NILFS_FT_REG_FILE,
 262         [S_IFDIR >> S_SHIFT]    = NILFS_FT_DIR,
 263         [S_IFCHR >> S_SHIFT]    = NILFS_FT_CHRDEV,
 264         [S_IFBLK >> S_SHIFT]    = NILFS_FT_BLKDEV,
 265         [S_IFIFO >> S_SHIFT]    = NILFS_FT_FIFO,
 266         [S_IFSOCK >> S_SHIFT]   = NILFS_FT_SOCK,
 267         [S_IFLNK >> S_SHIFT]    = NILFS_FT_SYMLINK,
 268 };
 269
 270 static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
 271 {
 272         mode_t mode = inode->i_mode;
 273
 274         de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
 275 }
 276
 277 static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 278 {
 279         loff_t pos = filp->f_pos;
 280         struct inode *inode = filp->f_dentry->d_inode;
 281         struct super_block *sb = inode->i_sb;
 282         unsigned int offset = pos & ~PAGE_CACHE_MASK;
 283         unsigned long n = pos >> PAGE_CACHE_SHIFT;
 284         unsigned long npages = dir_pages(inode);
 285 /*      unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
 286         unsigned char *types = NULL;
 287         int ret;
 288
 289         if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
 290                 goto success;
 291
 292         types = nilfs_filetype_table;
 293
 294         for ( ; n < npages; n++, offset = 0) {
 295                 char *kaddr, *limit;
 296                 struct nilfs_dir_entry *de;
 297                 struct page *page = nilfs_get_page(inode, n);
 298
 299                 if (IS_ERR(page)) {
 300                         nilfs_error(sb, __func__, "bad page in #%lu",
 301                                     inode->i_ino);
 302                         filp->f_pos += PAGE_CACHE_SIZE - offset;
 303                         ret = -EIO;
 304                         goto done;
 305                 }
 306                 kaddr = page_address(page);
 307                 de = (struct nilfs_dir_entry *)(kaddr + offset);
 308                 limit = kaddr + nilfs_last_byte(inode, n) -
 309                         NILFS_DIR_REC_LEN(1);
 310                 for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
 311                         if (de->rec_len == 0) {
 312                                 nilfs_error(sb, __func__,
 313                                             "zero-length directory entry");
 314                                 ret = -EIO;
 315                                 nilfs_put_page(page);
 316                                 goto done;
 317                         }
 318                         if (de->inode) {
 319                                 int over;
 320                                 unsigned char d_type = DT_UNKNOWN;
 321
 322                                 if (types && de->file_type < NILFS_FT_MAX)
 323                                         d_type = types[de->file_type];
 324
 325                                 offset = (char *)de - kaddr;
 326                                 over = filldir(dirent, de->name, de->name_len,
 327                                                 (n<<PAGE_CACHE_SHIFT) | offset,
 328                                                 le64_to_cpu(de->inode), d_type);
 329                                 if (over) {
 330                                         nilfs_put_page(page);
 331                                         goto success;
 332                                 }
 333                         }
 334                         filp->f_pos += le16_to_cpu(de->rec_len);
 335                 }
 336                 nilfs_put_page(page);
 337         }
 338
 339 success:
 340         ret = 0;
 341 done:
 342         return ret;
 343 }
 344
 345 /*
 346  *      nilfs_find_entry()
 347  *
 348  * finds an entry in the specified directory with the wanted name. It
 349  * returns the page in which the entry was found, and the entry itself
 350  * (as a parameter - res_dir). Page is returned mapped and unlocked.
 351  * Entry is guaranteed to be valid.
 352  */
 353 struct nilfs_dir_entry *
 354 nilfs_find_entry(struct inode *dir, struct dentry *dentry,
 355                  struct page **res_page)
 356 {
 357         const char *name = dentry->d_name.name;
 358         int namelen = dentry->d_name.len;
 359         unsigned reclen = NILFS_DIR_REC_LEN(namelen);
 360         unsigned long start, n;
 361         unsigned long npages = dir_pages(dir);
 362         struct page *page = NULL;
 363         struct nilfs_inode_info *ei = NILFS_I(dir);
 364         struct nilfs_dir_entry *de;
 365
 366         if (npages == 0)
 367                 goto out;
 368
 369         /* OFFSET_CACHE */
 370         *res_page = NULL;
 371
 372         start = ei->i_dir_start_lookup;
 373         if (start >= npages)
 374                 start = 0;
 375         n = start;
 376         do {
 377                 char *kaddr;
 378                 page = nilfs_get_page(dir, n);
 379                 if (!IS_ERR(page)) {
 380                         kaddr = page_address(page);
 381                         de = (struct nilfs_dir_entry *)kaddr;
 382                         kaddr += nilfs_last_byte(dir, n) - reclen;
 383                         while ((char *) de <= kaddr) {
 384                                 if (de->rec_len == 0) {
 385                                         nilfs_error(dir->i_sb, __func__,
 386                                                 "zero-length directory entry");
 387                                         nilfs_put_page(page);
 388                                         goto out;
 389                                 }
 390                                 if (nilfs_match(namelen, name, de))
 391                                         goto found;
 392                                 de = nilfs_next_entry(de);
 393                         }
 394                         nilfs_put_page(page);
 395                 }
 396                 if (++n >= npages)
 397                         n = 0;
 398                 /* next page is past the blocks we've got */
 399                 if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
 400                         nilfs_error(dir->i_sb, __func__,
 401                                "dir %lu size %lld exceeds block cout %llu",
 402                                dir->i_ino, dir->i_size,
 403                                (unsigned long long)dir->i_blocks);
 404                         goto out;
 405                 }
 406         } while (n != start);
 407 out:
 408         return NULL;
 409
 410 found:
 411         *res_page = page;
 412         ei->i_dir_start_lookup = n;
 413         return de;
 414 }
 415
 416 struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
 417 {
 418         struct page *page = nilfs_get_page(dir, 0);
 419         struct nilfs_dir_entry *de = NULL;
 420
 421         if (!IS_ERR(page)) {
 422                 de = nilfs_next_entry(
 423                         (struct nilfs_dir_entry *)page_address(page));
 424                 *p = page;
 425         }
 426         return de;
 427 }
 428
 429 ino_t nilfs_inode_by_name(struct inode *dir, struct dentry *dentry)
 430 {
 431         ino_t res = 0;
 432         struct nilfs_dir_entry *de;
 433         struct page *page;
 434
 435         de = nilfs_find_entry(dir, dentry, &page);
 436         if (de) {
 437                 res = le64_to_cpu(de->inode);
 438                 kunmap(page);
 439                 page_cache_release(page);
 440         }
 441         return res;
 442 }
 443
 444 /* Releases the page */
 445 void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
 446                     struct page *page, struct inode *inode)
 447 {
 448         unsigned from = (char *) de - (char *) page_address(page);
 449         unsigned to = from + le16_to_cpu(de->rec_len);
 450         struct address_space *mapping = page->mapping;
 451         int err;
 452
 453         lock_page(page);
 454         err = nilfs_prepare_chunk_uninterruptible(page, mapping, from, to);
 455         BUG_ON(err);
 456         de->inode = cpu_to_le64(inode->i_ino);
 457         nilfs_set_de_type(de, inode);
 458         err = nilfs_commit_chunk(page, mapping, from, to);
 459         nilfs_put_page(page);
 460         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 461 /*      NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
 462         mark_inode_dirty(dir);
 463 }
 464
 465 /*
 466  *      Parent is locked.
 467  */
 468 int nilfs_add_link(struct dentry *dentry, struct inode *inode)
 469 {
 470         struct inode *dir = dentry->d_parent->d_inode;
 471         const char *name = dentry->d_name.name;
 472         int namelen = dentry->d_name.len;
 473         unsigned chunk_size = nilfs_chunk_size(dir);
 474         unsigned reclen = NILFS_DIR_REC_LEN(namelen);
 475         unsigned short rec_len, name_len;
 476         struct page *page = NULL;
 477         struct nilfs_dir_entry *de;
 478         unsigned long npages = dir_pages(dir);
 479         unsigned long n;
 480         char *kaddr;
 481         unsigned from, to;
 482         int err;
 483
 484         /*
 485          * We take care of directory expansion in the same loop.
 486          * This code plays outside i_size, so it locks the page
 487          * to protect that region.
 488          */
 489         for (n = 0; n <= npages; n++) {
 490                 char *dir_end;
 491
 492                 page = nilfs_get_page(dir, n);
 493                 err = PTR_ERR(page);
 494                 if (IS_ERR(page))
 495                         goto out;
 496                 lock_page(page);
 497                 kaddr = page_address(page);
 498                 dir_end = kaddr + nilfs_last_byte(dir, n);
 499                 de = (struct nilfs_dir_entry *)kaddr;
 500                 kaddr += PAGE_CACHE_SIZE - reclen;
 501                 while ((char *)de <= kaddr) {
 502                         if ((char *)de == dir_end) {
 503                                 /* We hit i_size */
 504                                 name_len = 0;
 505                                 rec_len = chunk_size;
 506                                 de->rec_len = cpu_to_le16(chunk_size);
 507                                 de->inode = 0;
 508                                 goto got_it;
 509                         }
 510                         if (de->rec_len == 0) {
 511                                 nilfs_error(dir->i_sb, __func__,
 512                                             "zero-length directory entry");
 513                                 err = -EIO;
 514                                 goto out_unlock;
 515                         }
 516                         err = -EEXIST;
 517                         if (nilfs_match(namelen, name, de))
 518                                 goto out_unlock;
 519                         name_len = NILFS_DIR_REC_LEN(de->name_len);
 520                         rec_len = le16_to_cpu(de->rec_len);
 521                         if (!de->inode && rec_len >= reclen)
 522                                 goto got_it;
 523                         if (rec_len >= name_len + reclen)
 524                                 goto got_it;
 525                         de = (struct nilfs_dir_entry *)((char *)de + rec_len);
 526                 }
 527                 unlock_page(page);
 528                 nilfs_put_page(page);
 529         }
 530         BUG();
 531         return -EINVAL;
 532
 533 got_it:
 534         from = (char *)de - (char *)page_address(page);
 535         to = from + rec_len;
 536         err = nilfs_prepare_chunk(page, page->mapping, from, to);
 537         if (err)
 538                 goto out_unlock;
 539         if (de->inode) {
 540                 struct nilfs_dir_entry *de1;
 541
 542                 de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
 543                 de1->rec_len = cpu_to_le16(rec_len - name_len);
 544                 de->rec_len = cpu_to_le16(name_len);
 545                 de = de1;
 546         }
 547         de->name_len = namelen;
 548         memcpy(de->name, name, namelen);
 549         de->inode = cpu_to_le64(inode->i_ino);
 550         nilfs_set_de_type(de, inode);
 551         err = nilfs_commit_chunk(page, page->mapping, from, to);
 552         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 553 /*      NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
 554         mark_inode_dirty(dir);
 555         /* OFFSET_CACHE */
 556 out_put:
 557         nilfs_put_page(page);
 558 out:
 559         return err;
 560 out_unlock:
 561         unlock_page(page);
 562         goto out_put;
 563 }
 564
 565 /*
 566  * nilfs_delete_entry deletes a directory entry by merging it with the
 567  * previous entry. Page is up-to-date. Releases the page.
 568  */
 569 int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
 570 {
 571         struct address_space *mapping = page->mapping;
 572         struct inode *inode = mapping->host;
 573         char *kaddr = page_address(page);
 574         unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
 575         unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
 576         struct nilfs_dir_entry *pde = NULL;
 577         struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
 578         int err;
 579
 580         while ((char *)de < (char *)dir) {
 581                 if (de->rec_len == 0) {
 582                         nilfs_error(inode->i_sb, __func__,
 583                                     "zero-length directory entry");
 584                         err = -EIO;
 585                         goto out;
 586                 }
 587                 pde = de;
 588                 de = nilfs_next_entry(de);
 589         }
 590         if (pde)
 591                 from = (char *)pde - (char *)page_address(page);
 592         lock_page(page);
 593         err = nilfs_prepare_chunk(page, mapping, from, to);
 594         BUG_ON(err);
 595         if (pde)
 596                 pde->rec_len = cpu_to_le16(to - from);
 597         dir->inode = 0;
 598         err = nilfs_commit_chunk(page, mapping, from, to);
 599         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 600 /*      NILFS_I(inode)->i_flags &= ~NILFS_BTREE_FL; */
 601         mark_inode_dirty(inode);
 602 out:
 603         nilfs_put_page(page);
 604         return err;
 605 }
 606
 607 /*
 608  * Set the first fragment of directory.
 609  */
 610 int nilfs_make_empty(struct inode *inode, struct inode *parent)
 611 {
 612         struct address_space *mapping = inode->i_mapping;
 613         struct page *page = grab_cache_page(mapping, 0);
 614         unsigned chunk_size = nilfs_chunk_size(inode);
 615         struct nilfs_dir_entry *de;
 616         int err;
 617         void *kaddr;
 618
 619         if (!page)
 620                 return -ENOMEM;
 621
 622         err = nilfs_prepare_chunk(page, mapping, 0, chunk_size);
 623         if (unlikely(err)) {
 624                 unlock_page(page);
 625                 goto fail;
 626         }
 627         kaddr = kmap_atomic(page, KM_USER0);
 628         memset(kaddr, 0, chunk_size);
 629         de = (struct nilfs_dir_entry *)kaddr;
 630         de->name_len = 1;
 631         de->rec_len = cpu_to_le16(NILFS_DIR_REC_LEN(1));
 632         memcpy(de->name, ".\0\0", 4);
 633         de->inode = cpu_to_le64(inode->i_ino);
 634         nilfs_set_de_type(de, inode);
 635
 636         de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
 637         de->name_len = 2;
 638         de->rec_len = cpu_to_le16(chunk_size - NILFS_DIR_REC_LEN(1));
 639         de->inode = cpu_to_le64(parent->i_ino);
 640         memcpy(de->name, "..\0", 4);
 641         nilfs_set_de_type(de, inode);
 642         kunmap_atomic(kaddr, KM_USER0);
 643         err = nilfs_commit_chunk(page, mapping, 0, chunk_size);
 644 fail:
 645         page_cache_release(page);
 646         return err;
 647 }
 648
 649 /*
 650  * routine to check that the specified directory is empty (for rmdir)
 651  */
 652 int nilfs_empty_dir(struct inode *inode)
 653 {
 654         struct page *page = NULL;
 655         unsigned long i, npages = dir_pages(inode);
 656
 657         for (i = 0; i < npages; i++) {
 658                 char *kaddr;
 659                 struct nilfs_dir_entry *de;
 660
 661                 page = nilfs_get_page(inode, i);
 662                 if (IS_ERR(page))
 663                         continue;
 664
 665                 kaddr = page_address(page);
 666                 de = (struct nilfs_dir_entry *)kaddr;
 667                 kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
 668
 669                 while ((char *)de <= kaddr) {
 670                         if (de->rec_len == 0) {
 671                                 nilfs_error(inode->i_sb, __func__,
 672                                             "zero-length directory entry "
 673                                             "(kaddr=%p, de=%p)\n", kaddr, de);
 674                                 goto not_empty;
 675                         }
 676                         if (de->inode != 0) {
 677                                 /* check for . and .. */
 678                                 if (de->name[0] != '.')
 679                                         goto not_empty;
 680                                 if (de->name_len > 2)
 681                                         goto not_empty;
 682                                 if (de->name_len < 2) {
 683                                         if (de->inode !=
 684                                             cpu_to_le64(inode->i_ino))
 685                                                 goto not_empty;
 686                                 } else if (de->name[1] != '.')
 687                                         goto not_empty;
 688                         }
 689                         de = nilfs_next_entry(de);
 690                 }
 691                 nilfs_put_page(page);
 692         }
 693         return 1;
 694
 695 not_empty:
 696         nilfs_put_page(page);
 697         return 0;
 698 }
 699
 700 struct file_operations nilfs_dir_operations = {
 701         .llseek         = generic_file_llseek,
 702         .read           = generic_read_dir,
 703         .readdir        = nilfs_readdir,
 704         .unlocked_ioctl = nilfs_ioctl,
 705 #ifdef CONFIG_COMPAT
 706         .compat_ioctl   = nilfs_ioctl,
 707 #endif  /* CONFIG_COMPAT */
 708         .fsync          = nilfs_sync_file,
 709
 710 };