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