linux/fs/ext2/dir.c
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   1/*
   2 *  linux/fs/ext2/dir.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 *
   9 *  from
  10 *
  11 *  linux/fs/minix/dir.c
  12 *
  13 *  Copyright (C) 1991, 1992  Linus Torvalds
  14 *
  15 *  ext2 directory handling functions
  16 *
  17 *  Big-endian to little-endian byte-swapping/bitmaps by
  18 *        David S. Miller (davem@caip.rutgers.edu), 1995
  19 *
  20 * All code that works with directory layout had been switched to pagecache
  21 * and moved here. AV
  22 */
  23
  24#include "ext2.h"
  25#include <linux/buffer_head.h>
  26#include <linux/pagemap.h>
  27#include <linux/swap.h>
  28
  29typedef struct ext2_dir_entry_2 ext2_dirent;
  30
  31/*
  32 * Tests against MAX_REC_LEN etc were put in place for 64k block
  33 * sizes; if that is not possible on this arch, we can skip
  34 * those tests and speed things up.
  35 */
  36static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
  37{
  38        unsigned len = le16_to_cpu(dlen);
  39
  40#if (PAGE_CACHE_SIZE >= 65536)
  41        if (len == EXT2_MAX_REC_LEN)
  42                return 1 << 16;
  43#endif
  44        return len;
  45}
  46
  47static inline __le16 ext2_rec_len_to_disk(unsigned len)
  48{
  49#if (PAGE_CACHE_SIZE >= 65536)
  50        if (len == (1 << 16))
  51                return cpu_to_le16(EXT2_MAX_REC_LEN);
  52        else
  53                BUG_ON(len > (1 << 16));
  54#endif
  55        return cpu_to_le16(len);
  56}
  57
  58/*
  59 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
  60 * more robust, but we have what we have
  61 */
  62static inline unsigned ext2_chunk_size(struct inode *inode)
  63{
  64        return inode->i_sb->s_blocksize;
  65}
  66
  67static inline void ext2_put_page(struct page *page)
  68{
  69        kunmap(page);
  70        page_cache_release(page);
  71}
  72
  73static inline unsigned long dir_pages(struct inode *inode)
  74{
  75        return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
  76}
  77
  78/*
  79 * Return the offset into page `page_nr' of the last valid
  80 * byte in that page, plus one.
  81 */
  82static unsigned
  83ext2_last_byte(struct inode *inode, unsigned long page_nr)
  84{
  85        unsigned last_byte = inode->i_size;
  86
  87        last_byte -= page_nr << PAGE_CACHE_SHIFT;
  88        if (last_byte > PAGE_CACHE_SIZE)
  89                last_byte = PAGE_CACHE_SIZE;
  90        return last_byte;
  91}
  92
  93static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
  94{
  95        struct address_space *mapping = page->mapping;
  96        struct inode *dir = mapping->host;
  97        int err = 0;
  98
  99        dir->i_version++;
 100        block_write_end(NULL, mapping, pos, len, len, page, NULL);
 101
 102        if (pos+len > dir->i_size) {
 103                i_size_write(dir, pos+len);
 104                mark_inode_dirty(dir);
 105        }
 106
 107        if (IS_DIRSYNC(dir)) {
 108                err = write_one_page(page, 1);
 109                if (!err)
 110                        err = sync_inode_metadata(dir, 1);
 111        } else {
 112                unlock_page(page);
 113        }
 114
 115        return err;
 116}
 117
 118static void ext2_check_page(struct page *page, int quiet)
 119{
 120        struct inode *dir = page->mapping->host;
 121        struct super_block *sb = dir->i_sb;
 122        unsigned chunk_size = ext2_chunk_size(dir);
 123        char *kaddr = page_address(page);
 124        u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
 125        unsigned offs, rec_len;
 126        unsigned limit = PAGE_CACHE_SIZE;
 127        ext2_dirent *p;
 128        char *error;
 129
 130        if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
 131                limit = dir->i_size & ~PAGE_CACHE_MASK;
 132                if (limit & (chunk_size - 1))
 133                        goto Ebadsize;
 134                if (!limit)
 135                        goto out;
 136        }
 137        for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
 138                p = (ext2_dirent *)(kaddr + offs);
 139                rec_len = ext2_rec_len_from_disk(p->rec_len);
 140
 141                if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
 142                        goto Eshort;
 143                if (unlikely(rec_len & 3))
 144                        goto Ealign;
 145                if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
 146                        goto Enamelen;
 147                if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
 148                        goto Espan;
 149                if (unlikely(le32_to_cpu(p->inode) > max_inumber))
 150                        goto Einumber;
 151        }
 152        if (offs != limit)
 153                goto Eend;
 154out:
 155        SetPageChecked(page);
 156        return;
 157
 158        /* Too bad, we had an error */
 159
 160Ebadsize:
 161        if (!quiet)
 162                ext2_error(sb, __func__,
 163                        "size of directory #%lu is not a multiple "
 164                        "of chunk size", dir->i_ino);
 165        goto fail;
 166Eshort:
 167        error = "rec_len is smaller than minimal";
 168        goto bad_entry;
 169Ealign:
 170        error = "unaligned directory entry";
 171        goto bad_entry;
 172Enamelen:
 173        error = "rec_len is too small for name_len";
 174        goto bad_entry;
 175Espan:
 176        error = "directory entry across blocks";
 177        goto bad_entry;
 178Einumber:
 179        error = "inode out of bounds";
 180bad_entry:
 181        if (!quiet)
 182                ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
 183                        "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
 184                        dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
 185                        (unsigned long) le32_to_cpu(p->inode),
 186                        rec_len, p->name_len);
 187        goto fail;
 188Eend:
 189        if (!quiet) {
 190                p = (ext2_dirent *)(kaddr + offs);
 191                ext2_error(sb, "ext2_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) le32_to_cpu(p->inode));
 196        }
 197fail:
 198        SetPageChecked(page);
 199        SetPageError(page);
 200}
 201
 202static struct page * ext2_get_page(struct inode *dir, unsigned long n,
 203                                   int quiet)
 204{
 205        struct address_space *mapping = dir->i_mapping;
 206        struct page *page = read_mapping_page(mapping, n, NULL);
 207        if (!IS_ERR(page)) {
 208                kmap(page);
 209                if (!PageChecked(page))
 210                        ext2_check_page(page, quiet);
 211                if (PageError(page))
 212                        goto fail;
 213        }
 214        return page;
 215
 216fail:
 217        ext2_put_page(page);
 218        return ERR_PTR(-EIO);
 219}
 220
 221/*
 222 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 223 *
 224 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
 225 */
 226static inline int ext2_match (int len, const char * const name,
 227                                        struct ext2_dir_entry_2 * 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 */
 239static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
 240{
 241        return (ext2_dirent *)((char *)p +
 242                        ext2_rec_len_from_disk(p->rec_len));
 243}
 244
 245static inline unsigned 
 246ext2_validate_entry(char *base, unsigned offset, unsigned mask)
 247{
 248        ext2_dirent *de = (ext2_dirent*)(base + offset);
 249        ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
 250        while ((char*)p < (char*)de) {
 251                if (p->rec_len == 0)
 252                        break;
 253                p = ext2_next_entry(p);
 254        }
 255        return (char *)p - base;
 256}
 257
 258static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
 259        [EXT2_FT_UNKNOWN]       = DT_UNKNOWN,
 260        [EXT2_FT_REG_FILE]      = DT_REG,
 261        [EXT2_FT_DIR]           = DT_DIR,
 262        [EXT2_FT_CHRDEV]        = DT_CHR,
 263        [EXT2_FT_BLKDEV]        = DT_BLK,
 264        [EXT2_FT_FIFO]          = DT_FIFO,
 265        [EXT2_FT_SOCK]          = DT_SOCK,
 266        [EXT2_FT_SYMLINK]       = DT_LNK,
 267};
 268
 269#define S_SHIFT 12
 270static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
 271        [S_IFREG >> S_SHIFT]    = EXT2_FT_REG_FILE,
 272        [S_IFDIR >> S_SHIFT]    = EXT2_FT_DIR,
 273        [S_IFCHR >> S_SHIFT]    = EXT2_FT_CHRDEV,
 274        [S_IFBLK >> S_SHIFT]    = EXT2_FT_BLKDEV,
 275        [S_IFIFO >> S_SHIFT]    = EXT2_FT_FIFO,
 276        [S_IFSOCK >> S_SHIFT]   = EXT2_FT_SOCK,
 277        [S_IFLNK >> S_SHIFT]    = EXT2_FT_SYMLINK,
 278};
 279
 280static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
 281{
 282        umode_t mode = inode->i_mode;
 283        if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
 284                de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
 285        else
 286                de->file_type = 0;
 287}
 288
 289static int
 290ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
 291{
 292        loff_t pos = filp->f_pos;
 293        struct inode *inode = filp->f_path.dentry->d_inode;
 294        struct super_block *sb = inode->i_sb;
 295        unsigned int offset = pos & ~PAGE_CACHE_MASK;
 296        unsigned long n = pos >> PAGE_CACHE_SHIFT;
 297        unsigned long npages = dir_pages(inode);
 298        unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
 299        unsigned char *types = NULL;
 300        int need_revalidate = filp->f_version != inode->i_version;
 301
 302        if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
 303                return 0;
 304
 305        if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
 306                types = ext2_filetype_table;
 307
 308        for ( ; n < npages; n++, offset = 0) {
 309                char *kaddr, *limit;
 310                ext2_dirent *de;
 311                struct page *page = ext2_get_page(inode, n, 0);
 312
 313                if (IS_ERR(page)) {
 314                        ext2_error(sb, __func__,
 315                                   "bad page in #%lu",
 316                                   inode->i_ino);
 317                        filp->f_pos += PAGE_CACHE_SIZE - offset;
 318                        return PTR_ERR(page);
 319                }
 320                kaddr = page_address(page);
 321                if (unlikely(need_revalidate)) {
 322                        if (offset) {
 323                                offset = ext2_validate_entry(kaddr, offset, chunk_mask);
 324                                filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
 325                        }
 326                        filp->f_version = inode->i_version;
 327                        need_revalidate = 0;
 328                }
 329                de = (ext2_dirent *)(kaddr+offset);
 330                limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
 331                for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
 332                        if (de->rec_len == 0) {
 333                                ext2_error(sb, __func__,
 334                                        "zero-length directory entry");
 335                                ext2_put_page(page);
 336                                return -EIO;
 337                        }
 338                        if (de->inode) {
 339                                int over;
 340                                unsigned char d_type = DT_UNKNOWN;
 341
 342                                if (types && de->file_type < EXT2_FT_MAX)
 343                                        d_type = types[de->file_type];
 344
 345                                offset = (char *)de - kaddr;
 346                                over = filldir(dirent, de->name, de->name_len,
 347                                                (n<<PAGE_CACHE_SHIFT) | offset,
 348                                                le32_to_cpu(de->inode), d_type);
 349                                if (over) {
 350                                        ext2_put_page(page);
 351                                        return 0;
 352                                }
 353                        }
 354                        filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
 355                }
 356                ext2_put_page(page);
 357        }
 358        return 0;
 359}
 360
 361/*
 362 *      ext2_find_entry()
 363 *
 364 * finds an entry in the specified directory with the wanted name. It
 365 * returns the page in which the entry was found (as a parameter - res_page),
 366 * and the entry itself. Page is returned mapped and unlocked.
 367 * Entry is guaranteed to be valid.
 368 */
 369struct ext2_dir_entry_2 *ext2_find_entry (struct inode * dir,
 370                        struct qstr *child, struct page ** res_page)
 371{
 372        const char *name = child->name;
 373        int namelen = child->len;
 374        unsigned reclen = EXT2_DIR_REC_LEN(namelen);
 375        unsigned long start, n;
 376        unsigned long npages = dir_pages(dir);
 377        struct page *page = NULL;
 378        struct ext2_inode_info *ei = EXT2_I(dir);
 379        ext2_dirent * de;
 380        int dir_has_error = 0;
 381
 382        if (npages == 0)
 383                goto out;
 384
 385        /* OFFSET_CACHE */
 386        *res_page = NULL;
 387
 388        start = ei->i_dir_start_lookup;
 389        if (start >= npages)
 390                start = 0;
 391        n = start;
 392        do {
 393                char *kaddr;
 394                page = ext2_get_page(dir, n, dir_has_error);
 395                if (!IS_ERR(page)) {
 396                        kaddr = page_address(page);
 397                        de = (ext2_dirent *) kaddr;
 398                        kaddr += ext2_last_byte(dir, n) - reclen;
 399                        while ((char *) de <= kaddr) {
 400                                if (de->rec_len == 0) {
 401                                        ext2_error(dir->i_sb, __func__,
 402                                                "zero-length directory entry");
 403                                        ext2_put_page(page);
 404                                        goto out;
 405                                }
 406                                if (ext2_match (namelen, name, de))
 407                                        goto found;
 408                                de = ext2_next_entry(de);
 409                        }
 410                        ext2_put_page(page);
 411                } else
 412                        dir_has_error = 1;
 413
 414                if (++n >= npages)
 415                        n = 0;
 416                /* next page is past the blocks we've got */
 417                if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
 418                        ext2_error(dir->i_sb, __func__,
 419                                "dir %lu size %lld exceeds block count %llu",
 420                                dir->i_ino, dir->i_size,
 421                                (unsigned long long)dir->i_blocks);
 422                        goto out;
 423                }
 424        } while (n != start);
 425out:
 426        return NULL;
 427
 428found:
 429        *res_page = page;
 430        ei->i_dir_start_lookup = n;
 431        return de;
 432}
 433
 434struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
 435{
 436        struct page *page = ext2_get_page(dir, 0, 0);
 437        ext2_dirent *de = NULL;
 438
 439        if (!IS_ERR(page)) {
 440                de = ext2_next_entry((ext2_dirent *) page_address(page));
 441                *p = page;
 442        }
 443        return de;
 444}
 445
 446ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child)
 447{
 448        ino_t res = 0;
 449        struct ext2_dir_entry_2 *de;
 450        struct page *page;
 451        
 452        de = ext2_find_entry (dir, child, &page);
 453        if (de) {
 454                res = le32_to_cpu(de->inode);
 455                ext2_put_page(page);
 456        }
 457        return res;
 458}
 459
 460static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
 461{
 462        return __block_write_begin(page, pos, len, ext2_get_block);
 463}
 464
 465/* Releases the page */
 466void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
 467                   struct page *page, struct inode *inode, int update_times)
 468{
 469        loff_t pos = page_offset(page) +
 470                        (char *) de - (char *) page_address(page);
 471        unsigned len = ext2_rec_len_from_disk(de->rec_len);
 472        int err;
 473
 474        lock_page(page);
 475        err = ext2_prepare_chunk(page, pos, len);
 476        BUG_ON(err);
 477        de->inode = cpu_to_le32(inode->i_ino);
 478        ext2_set_de_type(de, inode);
 479        err = ext2_commit_chunk(page, pos, len);
 480        ext2_put_page(page);
 481        if (update_times)
 482                dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 483        EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
 484        mark_inode_dirty(dir);
 485}
 486
 487/*
 488 *      Parent is locked.
 489 */
 490int ext2_add_link (struct dentry *dentry, struct inode *inode)
 491{
 492        struct inode *dir = dentry->d_parent->d_inode;
 493        const char *name = dentry->d_name.name;
 494        int namelen = dentry->d_name.len;
 495        unsigned chunk_size = ext2_chunk_size(dir);
 496        unsigned reclen = EXT2_DIR_REC_LEN(namelen);
 497        unsigned short rec_len, name_len;
 498        struct page *page = NULL;
 499        ext2_dirent * de;
 500        unsigned long npages = dir_pages(dir);
 501        unsigned long n;
 502        char *kaddr;
 503        loff_t pos;
 504        int err;
 505
 506        /*
 507         * We take care of directory expansion in the same loop.
 508         * This code plays outside i_size, so it locks the page
 509         * to protect that region.
 510         */
 511        for (n = 0; n <= npages; n++) {
 512                char *dir_end;
 513
 514                page = ext2_get_page(dir, n, 0);
 515                err = PTR_ERR(page);
 516                if (IS_ERR(page))
 517                        goto out;
 518                lock_page(page);
 519                kaddr = page_address(page);
 520                dir_end = kaddr + ext2_last_byte(dir, n);
 521                de = (ext2_dirent *)kaddr;
 522                kaddr += PAGE_CACHE_SIZE - reclen;
 523                while ((char *)de <= kaddr) {
 524                        if ((char *)de == dir_end) {
 525                                /* We hit i_size */
 526                                name_len = 0;
 527                                rec_len = chunk_size;
 528                                de->rec_len = ext2_rec_len_to_disk(chunk_size);
 529                                de->inode = 0;
 530                                goto got_it;
 531                        }
 532                        if (de->rec_len == 0) {
 533                                ext2_error(dir->i_sb, __func__,
 534                                        "zero-length directory entry");
 535                                err = -EIO;
 536                                goto out_unlock;
 537                        }
 538                        err = -EEXIST;
 539                        if (ext2_match (namelen, name, de))
 540                                goto out_unlock;
 541                        name_len = EXT2_DIR_REC_LEN(de->name_len);
 542                        rec_len = ext2_rec_len_from_disk(de->rec_len);
 543                        if (!de->inode && rec_len >= reclen)
 544                                goto got_it;
 545                        if (rec_len >= name_len + reclen)
 546                                goto got_it;
 547                        de = (ext2_dirent *) ((char *) de + rec_len);
 548                }
 549                unlock_page(page);
 550                ext2_put_page(page);
 551        }
 552        BUG();
 553        return -EINVAL;
 554
 555got_it:
 556        pos = page_offset(page) +
 557                (char*)de - (char*)page_address(page);
 558        err = ext2_prepare_chunk(page, pos, rec_len);
 559        if (err)
 560                goto out_unlock;
 561        if (de->inode) {
 562                ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
 563                de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
 564                de->rec_len = ext2_rec_len_to_disk(name_len);
 565                de = de1;
 566        }
 567        de->name_len = namelen;
 568        memcpy(de->name, name, namelen);
 569        de->inode = cpu_to_le32(inode->i_ino);
 570        ext2_set_de_type (de, inode);
 571        err = ext2_commit_chunk(page, pos, rec_len);
 572        dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 573        EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
 574        mark_inode_dirty(dir);
 575        /* OFFSET_CACHE */
 576out_put:
 577        ext2_put_page(page);
 578out:
 579        return err;
 580out_unlock:
 581        unlock_page(page);
 582        goto out_put;
 583}
 584
 585/*
 586 * ext2_delete_entry deletes a directory entry by merging it with the
 587 * previous entry. Page is up-to-date. Releases the page.
 588 */
 589int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
 590{
 591        struct inode *inode = page->mapping->host;
 592        char *kaddr = page_address(page);
 593        unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
 594        unsigned to = ((char *)dir - kaddr) +
 595                                ext2_rec_len_from_disk(dir->rec_len);
 596        loff_t pos;
 597        ext2_dirent * pde = NULL;
 598        ext2_dirent * de = (ext2_dirent *) (kaddr + from);
 599        int err;
 600
 601        while ((char*)de < (char*)dir) {
 602                if (de->rec_len == 0) {
 603                        ext2_error(inode->i_sb, __func__,
 604                                "zero-length directory entry");
 605                        err = -EIO;
 606                        goto out;
 607                }
 608                pde = de;
 609                de = ext2_next_entry(de);
 610        }
 611        if (pde)
 612                from = (char*)pde - (char*)page_address(page);
 613        pos = page_offset(page) + from;
 614        lock_page(page);
 615        err = ext2_prepare_chunk(page, pos, to - from);
 616        BUG_ON(err);
 617        if (pde)
 618                pde->rec_len = ext2_rec_len_to_disk(to - from);
 619        dir->inode = 0;
 620        err = ext2_commit_chunk(page, pos, to - from);
 621        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 622        EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
 623        mark_inode_dirty(inode);
 624out:
 625        ext2_put_page(page);
 626        return err;
 627}
 628
 629/*
 630 * Set the first fragment of directory.
 631 */
 632int ext2_make_empty(struct inode *inode, struct inode *parent)
 633{
 634        struct page *page = grab_cache_page(inode->i_mapping, 0);
 635        unsigned chunk_size = ext2_chunk_size(inode);
 636        struct ext2_dir_entry_2 * de;
 637        int err;
 638        void *kaddr;
 639
 640        if (!page)
 641                return -ENOMEM;
 642
 643        err = ext2_prepare_chunk(page, 0, chunk_size);
 644        if (err) {
 645                unlock_page(page);
 646                goto fail;
 647        }
 648        kaddr = kmap_atomic(page);
 649        memset(kaddr, 0, chunk_size);
 650        de = (struct ext2_dir_entry_2 *)kaddr;
 651        de->name_len = 1;
 652        de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
 653        memcpy (de->name, ".\0\0", 4);
 654        de->inode = cpu_to_le32(inode->i_ino);
 655        ext2_set_de_type (de, inode);
 656
 657        de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
 658        de->name_len = 2;
 659        de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
 660        de->inode = cpu_to_le32(parent->i_ino);
 661        memcpy (de->name, "..\0", 4);
 662        ext2_set_de_type (de, inode);
 663        kunmap_atomic(kaddr);
 664        err = ext2_commit_chunk(page, 0, chunk_size);
 665fail:
 666        page_cache_release(page);
 667        return err;
 668}
 669
 670/*
 671 * routine to check that the specified directory is empty (for rmdir)
 672 */
 673int ext2_empty_dir (struct inode * inode)
 674{
 675        struct page *page = NULL;
 676        unsigned long i, npages = dir_pages(inode);
 677        int dir_has_error = 0;
 678
 679        for (i = 0; i < npages; i++) {
 680                char *kaddr;
 681                ext2_dirent * de;
 682                page = ext2_get_page(inode, i, dir_has_error);
 683
 684                if (IS_ERR(page)) {
 685                        dir_has_error = 1;
 686                        continue;
 687                }
 688
 689                kaddr = page_address(page);
 690                de = (ext2_dirent *)kaddr;
 691                kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
 692
 693                while ((char *)de <= kaddr) {
 694                        if (de->rec_len == 0) {
 695                                ext2_error(inode->i_sb, __func__,
 696                                        "zero-length directory entry");
 697                                printk("kaddr=%p, de=%p\n", kaddr, de);
 698                                goto not_empty;
 699                        }
 700                        if (de->inode != 0) {
 701                                /* check for . and .. */
 702                                if (de->name[0] != '.')
 703                                        goto not_empty;
 704                                if (de->name_len > 2)
 705                                        goto not_empty;
 706                                if (de->name_len < 2) {
 707                                        if (de->inode !=
 708                                            cpu_to_le32(inode->i_ino))
 709                                                goto not_empty;
 710                                } else if (de->name[1] != '.')
 711                                        goto not_empty;
 712                        }
 713                        de = ext2_next_entry(de);
 714                }
 715                ext2_put_page(page);
 716        }
 717        return 1;
 718
 719not_empty:
 720        ext2_put_page(page);
 721        return 0;
 722}
 723
 724const struct file_operations ext2_dir_operations = {
 725        .llseek         = generic_file_llseek,
 726        .read           = generic_read_dir,
 727        .readdir        = ext2_readdir,
 728        .unlocked_ioctl = ext2_ioctl,
 729#ifdef CONFIG_COMPAT
 730        .compat_ioctl   = ext2_compat_ioctl,
 731#endif
 732        .fsync          = ext2_fsync,
 733};
 734
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