linux/fs/nilfs2/dir.c
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   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 */
  53static inline unsigned nilfs_chunk_size(struct inode *inode)
  54{
  55        return inode->i_sb->s_blocksize;
  56}
  57
  58static inline void nilfs_put_page(struct page *page)
  59{
  60        kunmap(page);
  61        page_cache_release(page);
  62}
  63
  64static 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 */
  73static 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
  83static int nilfs_prepare_chunk(struct page *page, unsigned from, unsigned to)
  84{
  85        loff_t pos = page_offset(page) + from;
  86        return __block_write_begin(page, pos, to - from, nilfs_get_block);
  87}
  88
  89static void nilfs_commit_chunk(struct page *page,
  90                               struct address_space *mapping,
  91                               unsigned from, unsigned to)
  92{
  93        struct inode *dir = mapping->host;
  94        loff_t pos = page_offset(page) + from;
  95        unsigned len = to - from;
  96        unsigned nr_dirty, copied;
  97        int err;
  98
  99        nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
 100        copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
 101        if (pos + copied > dir->i_size)
 102                i_size_write(dir, pos + copied);
 103        if (IS_DIRSYNC(dir))
 104                nilfs_set_transaction_flag(NILFS_TI_SYNC);
 105        err = nilfs_set_file_dirty(dir, nr_dirty);
 106        WARN_ON(err); /* do not happen */
 107        unlock_page(page);
 108}
 109
 110static void nilfs_check_page(struct page *page)
 111{
 112        struct inode *dir = page->mapping->host;
 113        struct super_block *sb = dir->i_sb;
 114        unsigned chunk_size = nilfs_chunk_size(dir);
 115        char *kaddr = page_address(page);
 116        unsigned offs, rec_len;
 117        unsigned limit = PAGE_CACHE_SIZE;
 118        struct nilfs_dir_entry *p;
 119        char *error;
 120
 121        if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
 122                limit = dir->i_size & ~PAGE_CACHE_MASK;
 123                if (limit & (chunk_size - 1))
 124                        goto Ebadsize;
 125                if (!limit)
 126                        goto out;
 127        }
 128        for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
 129                p = (struct nilfs_dir_entry *)(kaddr + offs);
 130                rec_len = nilfs_rec_len_from_disk(p->rec_len);
 131
 132                if (rec_len < NILFS_DIR_REC_LEN(1))
 133                        goto Eshort;
 134                if (rec_len & 3)
 135                        goto Ealign;
 136                if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
 137                        goto Enamelen;
 138                if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
 139                        goto Espan;
 140        }
 141        if (offs != limit)
 142                goto Eend;
 143out:
 144        SetPageChecked(page);
 145        return;
 146
 147        /* Too bad, we had an error */
 148
 149Ebadsize:
 150        nilfs_error(sb, "nilfs_check_page",
 151                    "size of directory #%lu is not a multiple of chunk size",
 152                    dir->i_ino
 153        );
 154        goto fail;
 155Eshort:
 156        error = "rec_len is smaller than minimal";
 157        goto bad_entry;
 158Ealign:
 159        error = "unaligned directory entry";
 160        goto bad_entry;
 161Enamelen:
 162        error = "rec_len is too small for name_len";
 163        goto bad_entry;
 164Espan:
 165        error = "directory entry across blocks";
 166bad_entry:
 167        nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
 168                    "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
 169                    dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
 170                    (unsigned long) le64_to_cpu(p->inode),
 171                    rec_len, p->name_len);
 172        goto fail;
 173Eend:
 174        p = (struct nilfs_dir_entry *)(kaddr + offs);
 175        nilfs_error(sb, "nilfs_check_page",
 176                    "entry in directory #%lu spans the page boundary"
 177                    "offset=%lu, inode=%lu",
 178                    dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
 179                    (unsigned long) le64_to_cpu(p->inode));
 180fail:
 181        SetPageChecked(page);
 182        SetPageError(page);
 183}
 184
 185static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
 186{
 187        struct address_space *mapping = dir->i_mapping;
 188        struct page *page = read_mapping_page(mapping, n, NULL);
 189
 190        if (!IS_ERR(page)) {
 191                kmap(page);
 192                if (!PageChecked(page))
 193                        nilfs_check_page(page);
 194                if (PageError(page))
 195                        goto fail;
 196        }
 197        return page;
 198
 199fail:
 200        nilfs_put_page(page);
 201        return ERR_PTR(-EIO);
 202}
 203
 204/*
 205 * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
 206 *
 207 * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
 208 */
 209static int
 210nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *de)
 211{
 212        if (len != de->name_len)
 213                return 0;
 214        if (!de->inode)
 215                return 0;
 216        return !memcmp(name, de->name, len);
 217}
 218
 219/*
 220 * p is at least 6 bytes before the end of page
 221 */
 222static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
 223{
 224        return (struct nilfs_dir_entry *)((char *)p +
 225                                          nilfs_rec_len_from_disk(p->rec_len));
 226}
 227
 228static unsigned char
 229nilfs_filetype_table[NILFS_FT_MAX] = {
 230        [NILFS_FT_UNKNOWN]      = DT_UNKNOWN,
 231        [NILFS_FT_REG_FILE]     = DT_REG,
 232        [NILFS_FT_DIR]          = DT_DIR,
 233        [NILFS_FT_CHRDEV]       = DT_CHR,
 234        [NILFS_FT_BLKDEV]       = DT_BLK,
 235        [NILFS_FT_FIFO]         = DT_FIFO,
 236        [NILFS_FT_SOCK]         = DT_SOCK,
 237        [NILFS_FT_SYMLINK]      = DT_LNK,
 238};
 239
 240#define S_SHIFT 12
 241static unsigned char
 242nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
 243        [S_IFREG >> S_SHIFT]    = NILFS_FT_REG_FILE,
 244        [S_IFDIR >> S_SHIFT]    = NILFS_FT_DIR,
 245        [S_IFCHR >> S_SHIFT]    = NILFS_FT_CHRDEV,
 246        [S_IFBLK >> S_SHIFT]    = NILFS_FT_BLKDEV,
 247        [S_IFIFO >> S_SHIFT]    = NILFS_FT_FIFO,
 248        [S_IFSOCK >> S_SHIFT]   = NILFS_FT_SOCK,
 249        [S_IFLNK >> S_SHIFT]    = NILFS_FT_SYMLINK,
 250};
 251
 252static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
 253{
 254        umode_t mode = inode->i_mode;
 255
 256        de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
 257}
 258
 259static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 260{
 261        loff_t pos = filp->f_pos;
 262        struct inode *inode = filp->f_dentry->d_inode;
 263        struct super_block *sb = inode->i_sb;
 264        unsigned int offset = pos & ~PAGE_CACHE_MASK;
 265        unsigned long n = pos >> PAGE_CACHE_SHIFT;
 266        unsigned long npages = dir_pages(inode);
 267/*      unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
 268        unsigned char *types = NULL;
 269        int ret;
 270
 271        if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
 272                goto success;
 273
 274        types = nilfs_filetype_table;
 275
 276        for ( ; n < npages; n++, offset = 0) {
 277                char *kaddr, *limit;
 278                struct nilfs_dir_entry *de;
 279                struct page *page = nilfs_get_page(inode, n);
 280
 281                if (IS_ERR(page)) {
 282                        nilfs_error(sb, __func__, "bad page in #%lu",
 283                                    inode->i_ino);
 284                        filp->f_pos += PAGE_CACHE_SIZE - offset;
 285                        ret = -EIO;
 286                        goto done;
 287                }
 288                kaddr = page_address(page);
 289                de = (struct nilfs_dir_entry *)(kaddr + offset);
 290                limit = kaddr + nilfs_last_byte(inode, n) -
 291                        NILFS_DIR_REC_LEN(1);
 292                for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
 293                        if (de->rec_len == 0) {
 294                                nilfs_error(sb, __func__,
 295                                            "zero-length directory entry");
 296                                ret = -EIO;
 297                                nilfs_put_page(page);
 298                                goto done;
 299                        }
 300                        if (de->inode) {
 301                                int over;
 302                                unsigned char d_type = DT_UNKNOWN;
 303
 304                                if (types && de->file_type < NILFS_FT_MAX)
 305                                        d_type = types[de->file_type];
 306
 307                                offset = (char *)de - kaddr;
 308                                over = filldir(dirent, de->name, de->name_len,
 309                                                (n<<PAGE_CACHE_SHIFT) | offset,
 310                                                le64_to_cpu(de->inode), d_type);
 311                                if (over) {
 312                                        nilfs_put_page(page);
 313                                        goto success;
 314                                }
 315                        }
 316                        filp->f_pos += nilfs_rec_len_from_disk(de->rec_len);
 317                }
 318                nilfs_put_page(page);
 319        }
 320
 321success:
 322        ret = 0;
 323done:
 324        return ret;
 325}
 326
 327/*
 328 *      nilfs_find_entry()
 329 *
 330 * finds an entry in the specified directory with the wanted name. It
 331 * returns the page in which the entry was found, and the entry itself
 332 * (as a parameter - res_dir). Page is returned mapped and unlocked.
 333 * Entry is guaranteed to be valid.
 334 */
 335struct nilfs_dir_entry *
 336nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
 337                 struct page **res_page)
 338{
 339        const unsigned char *name = qstr->name;
 340        int namelen = qstr->len;
 341        unsigned reclen = NILFS_DIR_REC_LEN(namelen);
 342        unsigned long start, n;
 343        unsigned long npages = dir_pages(dir);
 344        struct page *page = NULL;
 345        struct nilfs_inode_info *ei = NILFS_I(dir);
 346        struct nilfs_dir_entry *de;
 347
 348        if (npages == 0)
 349                goto out;
 350
 351        /* OFFSET_CACHE */
 352        *res_page = NULL;
 353
 354        start = ei->i_dir_start_lookup;
 355        if (start >= npages)
 356                start = 0;
 357        n = start;
 358        do {
 359                char *kaddr;
 360                page = nilfs_get_page(dir, n);
 361                if (!IS_ERR(page)) {
 362                        kaddr = page_address(page);
 363                        de = (struct nilfs_dir_entry *)kaddr;
 364                        kaddr += nilfs_last_byte(dir, n) - reclen;
 365                        while ((char *) de <= kaddr) {
 366                                if (de->rec_len == 0) {
 367                                        nilfs_error(dir->i_sb, __func__,
 368                                                "zero-length directory entry");
 369                                        nilfs_put_page(page);
 370                                        goto out;
 371                                }
 372                                if (nilfs_match(namelen, name, de))
 373                                        goto found;
 374                                de = nilfs_next_entry(de);
 375                        }
 376                        nilfs_put_page(page);
 377                }
 378                if (++n >= npages)
 379                        n = 0;
 380                /* next page is past the blocks we've got */
 381                if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
 382                        nilfs_error(dir->i_sb, __func__,
 383                               "dir %lu size %lld exceeds block count %llu",
 384                               dir->i_ino, dir->i_size,
 385                               (unsigned long long)dir->i_blocks);
 386                        goto out;
 387                }
 388        } while (n != start);
 389out:
 390        return NULL;
 391
 392found:
 393        *res_page = page;
 394        ei->i_dir_start_lookup = n;
 395        return de;
 396}
 397
 398struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
 399{
 400        struct page *page = nilfs_get_page(dir, 0);
 401        struct nilfs_dir_entry *de = NULL;
 402
 403        if (!IS_ERR(page)) {
 404                de = nilfs_next_entry(
 405                        (struct nilfs_dir_entry *)page_address(page));
 406                *p = page;
 407        }
 408        return de;
 409}
 410
 411ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
 412{
 413        ino_t res = 0;
 414        struct nilfs_dir_entry *de;
 415        struct page *page;
 416
 417        de = nilfs_find_entry(dir, qstr, &page);
 418        if (de) {
 419                res = le64_to_cpu(de->inode);
 420                kunmap(page);
 421                page_cache_release(page);
 422        }
 423        return res;
 424}
 425
 426/* Releases the page */
 427void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
 428                    struct page *page, struct inode *inode)
 429{
 430        unsigned from = (char *) de - (char *) page_address(page);
 431        unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
 432        struct address_space *mapping = page->mapping;
 433        int err;
 434
 435        lock_page(page);
 436        err = nilfs_prepare_chunk(page, from, to);
 437        BUG_ON(err);
 438        de->inode = cpu_to_le64(inode->i_ino);
 439        nilfs_set_de_type(de, inode);
 440        nilfs_commit_chunk(page, mapping, from, to);
 441        nilfs_put_page(page);
 442        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 443}
 444
 445/*
 446 *      Parent is locked.
 447 */
 448int nilfs_add_link(struct dentry *dentry, struct inode *inode)
 449{
 450        struct inode *dir = dentry->d_parent->d_inode;
 451        const unsigned char *name = dentry->d_name.name;
 452        int namelen = dentry->d_name.len;
 453        unsigned chunk_size = nilfs_chunk_size(dir);
 454        unsigned reclen = NILFS_DIR_REC_LEN(namelen);
 455        unsigned short rec_len, name_len;
 456        struct page *page = NULL;
 457        struct nilfs_dir_entry *de;
 458        unsigned long npages = dir_pages(dir);
 459        unsigned long n;
 460        char *kaddr;
 461        unsigned from, to;
 462        int err;
 463
 464        /*
 465         * We take care of directory expansion in the same loop.
 466         * This code plays outside i_size, so it locks the page
 467         * to protect that region.
 468         */
 469        for (n = 0; n <= npages; n++) {
 470                char *dir_end;
 471
 472                page = nilfs_get_page(dir, n);
 473                err = PTR_ERR(page);
 474                if (IS_ERR(page))
 475                        goto out;
 476                lock_page(page);
 477                kaddr = page_address(page);
 478                dir_end = kaddr + nilfs_last_byte(dir, n);
 479                de = (struct nilfs_dir_entry *)kaddr;
 480                kaddr += PAGE_CACHE_SIZE - reclen;
 481                while ((char *)de <= kaddr) {
 482                        if ((char *)de == dir_end) {
 483                                /* We hit i_size */
 484                                name_len = 0;
 485                                rec_len = chunk_size;
 486                                de->rec_len = nilfs_rec_len_to_disk(chunk_size);
 487                                de->inode = 0;
 488                                goto got_it;
 489                        }
 490                        if (de->rec_len == 0) {
 491                                nilfs_error(dir->i_sb, __func__,
 492                                            "zero-length directory entry");
 493                                err = -EIO;
 494                                goto out_unlock;
 495                        }
 496                        err = -EEXIST;
 497                        if (nilfs_match(namelen, name, de))
 498                                goto out_unlock;
 499                        name_len = NILFS_DIR_REC_LEN(de->name_len);
 500                        rec_len = nilfs_rec_len_from_disk(de->rec_len);
 501                        if (!de->inode && rec_len >= reclen)
 502                                goto got_it;
 503                        if (rec_len >= name_len + reclen)
 504                                goto got_it;
 505                        de = (struct nilfs_dir_entry *)((char *)de + rec_len);
 506                }
 507                unlock_page(page);
 508                nilfs_put_page(page);
 509        }
 510        BUG();
 511        return -EINVAL;
 512
 513got_it:
 514        from = (char *)de - (char *)page_address(page);
 515        to = from + rec_len;
 516        err = nilfs_prepare_chunk(page, from, to);
 517        if (err)
 518                goto out_unlock;
 519        if (de->inode) {
 520                struct nilfs_dir_entry *de1;
 521
 522                de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
 523                de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
 524                de->rec_len = nilfs_rec_len_to_disk(name_len);
 525                de = de1;
 526        }
 527        de->name_len = namelen;
 528        memcpy(de->name, name, namelen);
 529        de->inode = cpu_to_le64(inode->i_ino);
 530        nilfs_set_de_type(de, inode);
 531        nilfs_commit_chunk(page, page->mapping, from, to);
 532        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 533        nilfs_mark_inode_dirty(dir);
 534        /* OFFSET_CACHE */
 535out_put:
 536        nilfs_put_page(page);
 537out:
 538        return err;
 539out_unlock:
 540        unlock_page(page);
 541        goto out_put;
 542}
 543
 544/*
 545 * nilfs_delete_entry deletes a directory entry by merging it with the
 546 * previous entry. Page is up-to-date. Releases the page.
 547 */
 548int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
 549{
 550        struct address_space *mapping = page->mapping;
 551        struct inode *inode = mapping->host;
 552        char *kaddr = page_address(page);
 553        unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
 554        unsigned to = ((char *)dir - kaddr) +
 555                nilfs_rec_len_from_disk(dir->rec_len);
 556        struct nilfs_dir_entry *pde = NULL;
 557        struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
 558        int err;
 559
 560        while ((char *)de < (char *)dir) {
 561                if (de->rec_len == 0) {
 562                        nilfs_error(inode->i_sb, __func__,
 563                                    "zero-length directory entry");
 564                        err = -EIO;
 565                        goto out;
 566                }
 567                pde = de;
 568                de = nilfs_next_entry(de);
 569        }
 570        if (pde)
 571                from = (char *)pde - (char *)page_address(page);
 572        lock_page(page);
 573        err = nilfs_prepare_chunk(page, from, to);
 574        BUG_ON(err);
 575        if (pde)
 576                pde->rec_len = nilfs_rec_len_to_disk(to - from);
 577        dir->inode = 0;
 578        nilfs_commit_chunk(page, mapping, from, to);
 579        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 580out:
 581        nilfs_put_page(page);
 582        return err;
 583}
 584
 585/*
 586 * Set the first fragment of directory.
 587 */
 588int nilfs_make_empty(struct inode *inode, struct inode *parent)
 589{
 590        struct address_space *mapping = inode->i_mapping;
 591        struct page *page = grab_cache_page(mapping, 0);
 592        unsigned chunk_size = nilfs_chunk_size(inode);
 593        struct nilfs_dir_entry *de;
 594        int err;
 595        void *kaddr;
 596
 597        if (!page)
 598                return -ENOMEM;
 599
 600        err = nilfs_prepare_chunk(page, 0, chunk_size);
 601        if (unlikely(err)) {
 602                unlock_page(page);
 603                goto fail;
 604        }
 605        kaddr = kmap_atomic(page);
 606        memset(kaddr, 0, chunk_size);
 607        de = (struct nilfs_dir_entry *)kaddr;
 608        de->name_len = 1;
 609        de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
 610        memcpy(de->name, ".\0\0", 4);
 611        de->inode = cpu_to_le64(inode->i_ino);
 612        nilfs_set_de_type(de, inode);
 613
 614        de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
 615        de->name_len = 2;
 616        de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
 617        de->inode = cpu_to_le64(parent->i_ino);
 618        memcpy(de->name, "..\0", 4);
 619        nilfs_set_de_type(de, inode);
 620        kunmap_atomic(kaddr);
 621        nilfs_commit_chunk(page, mapping, 0, chunk_size);
 622fail:
 623        page_cache_release(page);
 624        return err;
 625}
 626
 627/*
 628 * routine to check that the specified directory is empty (for rmdir)
 629 */
 630int nilfs_empty_dir(struct inode *inode)
 631{
 632        struct page *page = NULL;
 633        unsigned long i, npages = dir_pages(inode);
 634
 635        for (i = 0; i < npages; i++) {
 636                char *kaddr;
 637                struct nilfs_dir_entry *de;
 638
 639                page = nilfs_get_page(inode, i);
 640                if (IS_ERR(page))
 641                        continue;
 642
 643                kaddr = page_address(page);
 644                de = (struct nilfs_dir_entry *)kaddr;
 645                kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
 646
 647                while ((char *)de <= kaddr) {
 648                        if (de->rec_len == 0) {
 649                                nilfs_error(inode->i_sb, __func__,
 650                                            "zero-length directory entry "
 651                                            "(kaddr=%p, de=%p)\n", kaddr, de);
 652                                goto not_empty;
 653                        }
 654                        if (de->inode != 0) {
 655                                /* check for . and .. */
 656                                if (de->name[0] != '.')
 657                                        goto not_empty;
 658                                if (de->name_len > 2)
 659                                        goto not_empty;
 660                                if (de->name_len < 2) {
 661                                        if (de->inode !=
 662                                            cpu_to_le64(inode->i_ino))
 663                                                goto not_empty;
 664                                } else if (de->name[1] != '.')
 665                                        goto not_empty;
 666                        }
 667                        de = nilfs_next_entry(de);
 668                }
 669                nilfs_put_page(page);
 670        }
 671        return 1;
 672
 673not_empty:
 674        nilfs_put_page(page);
 675        return 0;
 676}
 677
 678const struct file_operations nilfs_dir_operations = {
 679        .llseek         = generic_file_llseek,
 680        .read           = generic_read_dir,
 681        .readdir        = nilfs_readdir,
 682        .unlocked_ioctl = nilfs_ioctl,
 683#ifdef CONFIG_COMPAT
 684        .compat_ioctl   = nilfs_compat_ioctl,
 685#endif  /* CONFIG_COMPAT */
 686        .fsync          = nilfs_sync_file,
 687
 688};
 689
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