linux/fs/fat/namei_vfat.c
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   1/*
   2 *  linux/fs/vfat/namei.c
   3 *
   4 *  Written 1992,1993 by Werner Almesberger
   5 *
   6 *  Windows95/Windows NT compatible extended MSDOS filesystem
   7 *    by Gordon Chaffee Copyright (C) 1995.  Send bug reports for the
   8 *    VFAT filesystem to <chaffee@cs.berkeley.edu>.  Specify
   9 *    what file operation caused you trouble and if you can duplicate
  10 *    the problem, send a script that demonstrates it.
  11 *
  12 *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
  13 *
  14 *  Support Multibyte characters and cleanup by
  15 *                              OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
  16 */
  17
  18#include <linux/module.h>
  19#include <linux/jiffies.h>
  20#include <linux/ctype.h>
  21#include <linux/slab.h>
  22#include <linux/buffer_head.h>
  23#include <linux/namei.h>
  24#include "fat.h"
  25
  26/*
  27 * If new entry was created in the parent, it could create the 8.3
  28 * alias (the shortname of logname).  So, the parent may have the
  29 * negative-dentry which matches the created 8.3 alias.
  30 *
  31 * If it happened, the negative dentry isn't actually negative
  32 * anymore.  So, drop it.
  33 */
  34static int vfat_revalidate_shortname(struct dentry *dentry)
  35{
  36        int ret = 1;
  37        spin_lock(&dentry->d_lock);
  38        if (dentry->d_time != dentry->d_parent->d_inode->i_version)
  39                ret = 0;
  40        spin_unlock(&dentry->d_lock);
  41        return ret;
  42}
  43
  44static int vfat_revalidate(struct dentry *dentry, unsigned int flags)
  45{
  46        if (flags & LOOKUP_RCU)
  47                return -ECHILD;
  48
  49        /* This is not negative dentry. Always valid. */
  50        if (dentry->d_inode)
  51                return 1;
  52        return vfat_revalidate_shortname(dentry);
  53}
  54
  55static int vfat_revalidate_ci(struct dentry *dentry, unsigned int flags)
  56{
  57        if (flags & LOOKUP_RCU)
  58                return -ECHILD;
  59
  60        /*
  61         * This is not negative dentry. Always valid.
  62         *
  63         * Note, rename() to existing directory entry will have ->d_inode,
  64         * and will use existing name which isn't specified name by user.
  65         *
  66         * We may be able to drop this positive dentry here. But dropping
  67         * positive dentry isn't good idea. So it's unsupported like
  68         * rename("filename", "FILENAME") for now.
  69         */
  70        if (dentry->d_inode)
  71                return 1;
  72
  73        /*
  74         * This may be nfsd (or something), anyway, we can't see the
  75         * intent of this. So, since this can be for creation, drop it.
  76         */
  77        if (!flags)
  78                return 0;
  79
  80        /*
  81         * Drop the negative dentry, in order to make sure to use the
  82         * case sensitive name which is specified by user if this is
  83         * for creation.
  84         */
  85        if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
  86                return 0;
  87
  88        return vfat_revalidate_shortname(dentry);
  89}
  90
  91/* returns the length of a struct qstr, ignoring trailing dots */
  92static unsigned int __vfat_striptail_len(unsigned int len, const char *name)
  93{
  94        while (len && name[len - 1] == '.')
  95                len--;
  96        return len;
  97}
  98
  99static unsigned int vfat_striptail_len(const struct qstr *qstr)
 100{
 101        return __vfat_striptail_len(qstr->len, qstr->name);
 102}
 103
 104/*
 105 * Compute the hash for the vfat name corresponding to the dentry.
 106 * Note: if the name is invalid, we leave the hash code unchanged so
 107 * that the existing dentry can be used. The vfat fs routines will
 108 * return ENOENT or EINVAL as appropriate.
 109 */
 110static int vfat_hash(const struct dentry *dentry, struct qstr *qstr)
 111{
 112        qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
 113        return 0;
 114}
 115
 116/*
 117 * Compute the hash for the vfat name corresponding to the dentry.
 118 * Note: if the name is invalid, we leave the hash code unchanged so
 119 * that the existing dentry can be used. The vfat fs routines will
 120 * return ENOENT or EINVAL as appropriate.
 121 */
 122static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
 123{
 124        struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
 125        const unsigned char *name;
 126        unsigned int len;
 127        unsigned long hash;
 128
 129        name = qstr->name;
 130        len = vfat_striptail_len(qstr);
 131
 132        hash = init_name_hash();
 133        while (len--)
 134                hash = partial_name_hash(nls_tolower(t, *name++), hash);
 135        qstr->hash = end_name_hash(hash);
 136
 137        return 0;
 138}
 139
 140/*
 141 * Case insensitive compare of two vfat names.
 142 */
 143static int vfat_cmpi(const struct dentry *parent, const struct dentry *dentry,
 144                unsigned int len, const char *str, const struct qstr *name)
 145{
 146        struct nls_table *t = MSDOS_SB(parent->d_sb)->nls_io;
 147        unsigned int alen, blen;
 148
 149        /* A filename cannot end in '.' or we treat it like it has none */
 150        alen = vfat_striptail_len(name);
 151        blen = __vfat_striptail_len(len, str);
 152        if (alen == blen) {
 153                if (nls_strnicmp(t, name->name, str, alen) == 0)
 154                        return 0;
 155        }
 156        return 1;
 157}
 158
 159/*
 160 * Case sensitive compare of two vfat names.
 161 */
 162static int vfat_cmp(const struct dentry *parent, const struct dentry *dentry,
 163                unsigned int len, const char *str, const struct qstr *name)
 164{
 165        unsigned int alen, blen;
 166
 167        /* A filename cannot end in '.' or we treat it like it has none */
 168        alen = vfat_striptail_len(name);
 169        blen = __vfat_striptail_len(len, str);
 170        if (alen == blen) {
 171                if (strncmp(name->name, str, alen) == 0)
 172                        return 0;
 173        }
 174        return 1;
 175}
 176
 177static const struct dentry_operations vfat_ci_dentry_ops = {
 178        .d_revalidate   = vfat_revalidate_ci,
 179        .d_hash         = vfat_hashi,
 180        .d_compare      = vfat_cmpi,
 181};
 182
 183static const struct dentry_operations vfat_dentry_ops = {
 184        .d_revalidate   = vfat_revalidate,
 185        .d_hash         = vfat_hash,
 186        .d_compare      = vfat_cmp,
 187};
 188
 189/* Characters that are undesirable in an MS-DOS file name */
 190
 191static inline wchar_t vfat_bad_char(wchar_t w)
 192{
 193        return (w < 0x0020)
 194            || (w == '*') || (w == '?') || (w == '<') || (w == '>')
 195            || (w == '|') || (w == '"') || (w == ':') || (w == '/')
 196            || (w == '\\');
 197}
 198
 199static inline wchar_t vfat_replace_char(wchar_t w)
 200{
 201        return (w == '[') || (w == ']') || (w == ';') || (w == ',')
 202            || (w == '+') || (w == '=');
 203}
 204
 205static wchar_t vfat_skip_char(wchar_t w)
 206{
 207        return (w == '.') || (w == ' ');
 208}
 209
 210static inline int vfat_is_used_badchars(const wchar_t *s, int len)
 211{
 212        int i;
 213
 214        for (i = 0; i < len; i++)
 215                if (vfat_bad_char(s[i]))
 216                        return -EINVAL;
 217
 218        if (s[i - 1] == ' ') /* last character cannot be space */
 219                return -EINVAL;
 220
 221        return 0;
 222}
 223
 224static int vfat_find_form(struct inode *dir, unsigned char *name)
 225{
 226        struct fat_slot_info sinfo;
 227        int err = fat_scan(dir, name, &sinfo);
 228        if (err)
 229                return -ENOENT;
 230        brelse(sinfo.bh);
 231        return 0;
 232}
 233
 234/*
 235 * 1) Valid characters for the 8.3 format alias are any combination of
 236 * letters, uppercase alphabets, digits, any of the
 237 * following special characters:
 238 *     $ % ' ` - @ { } ~ ! # ( ) & _ ^
 239 * In this case Longfilename is not stored in disk.
 240 *
 241 * WinNT's Extension:
 242 * File name and extension name is contain uppercase/lowercase
 243 * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
 244 *
 245 * 2) File name is 8.3 format, but it contain the uppercase and
 246 * lowercase char, muliti bytes char, etc. In this case numtail is not
 247 * added, but Longfilename is stored.
 248 *
 249 * 3) When the one except for the above, or the following special
 250 * character are contained:
 251 *        .   [ ] ; , + =
 252 * numtail is added, and Longfilename must be stored in disk .
 253 */
 254struct shortname_info {
 255        unsigned char lower:1,
 256                      upper:1,
 257                      valid:1;
 258};
 259#define INIT_SHORTNAME_INFO(x)  do {            \
 260        (x)->lower = 1;                         \
 261        (x)->upper = 1;                         \
 262        (x)->valid = 1;                         \
 263} while (0)
 264
 265static inline int to_shortname_char(struct nls_table *nls,
 266                                    unsigned char *buf, int buf_size,
 267                                    wchar_t *src, struct shortname_info *info)
 268{
 269        int len;
 270
 271        if (vfat_skip_char(*src)) {
 272                info->valid = 0;
 273                return 0;
 274        }
 275        if (vfat_replace_char(*src)) {
 276                info->valid = 0;
 277                buf[0] = '_';
 278                return 1;
 279        }
 280
 281        len = nls->uni2char(*src, buf, buf_size);
 282        if (len <= 0) {
 283                info->valid = 0;
 284                buf[0] = '_';
 285                len = 1;
 286        } else if (len == 1) {
 287                unsigned char prev = buf[0];
 288
 289                if (buf[0] >= 0x7F) {
 290                        info->lower = 0;
 291                        info->upper = 0;
 292                }
 293
 294                buf[0] = nls_toupper(nls, buf[0]);
 295                if (isalpha(buf[0])) {
 296                        if (buf[0] == prev)
 297                                info->lower = 0;
 298                        else
 299                                info->upper = 0;
 300                }
 301        } else {
 302                info->lower = 0;
 303                info->upper = 0;
 304        }
 305
 306        return len;
 307}
 308
 309/*
 310 * Given a valid longname, create a unique shortname.  Make sure the
 311 * shortname does not exist
 312 * Returns negative number on error, 0 for a normal
 313 * return, and 1 for valid shortname
 314 */
 315static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
 316                                 wchar_t *uname, int ulen,
 317                                 unsigned char *name_res, unsigned char *lcase)
 318{
 319        struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options;
 320        wchar_t *ip, *ext_start, *end, *name_start;
 321        unsigned char base[9], ext[4], buf[5], *p;
 322        unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
 323        int chl, chi;
 324        int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
 325        int is_shortname;
 326        struct shortname_info base_info, ext_info;
 327
 328        is_shortname = 1;
 329        INIT_SHORTNAME_INFO(&base_info);
 330        INIT_SHORTNAME_INFO(&ext_info);
 331
 332        /* Now, we need to create a shortname from the long name */
 333        ext_start = end = &uname[ulen];
 334        while (--ext_start >= uname) {
 335                if (*ext_start == 0x002E) {     /* is `.' */
 336                        if (ext_start == end - 1) {
 337                                sz = ulen;
 338                                ext_start = NULL;
 339                        }
 340                        break;
 341                }
 342        }
 343
 344        if (ext_start == uname - 1) {
 345                sz = ulen;
 346                ext_start = NULL;
 347        } else if (ext_start) {
 348                /*
 349                 * Names which start with a dot could be just
 350                 * an extension eg. "...test".  In this case Win95
 351                 * uses the extension as the name and sets no extension.
 352                 */
 353                name_start = &uname[0];
 354                while (name_start < ext_start) {
 355                        if (!vfat_skip_char(*name_start))
 356                                break;
 357                        name_start++;
 358                }
 359                if (name_start != ext_start) {
 360                        sz = ext_start - uname;
 361                        ext_start++;
 362                } else {
 363                        sz = ulen;
 364                        ext_start = NULL;
 365                }
 366        }
 367
 368        numtail_baselen = 6;
 369        numtail2_baselen = 2;
 370        for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
 371                chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
 372                                        ip, &base_info);
 373                if (chl == 0)
 374                        continue;
 375
 376                if (baselen < 2 && (baselen + chl) > 2)
 377                        numtail2_baselen = baselen;
 378                if (baselen < 6 && (baselen + chl) > 6)
 379                        numtail_baselen = baselen;
 380                for (chi = 0; chi < chl; chi++) {
 381                        *p++ = charbuf[chi];
 382                        baselen++;
 383                        if (baselen >= 8)
 384                                break;
 385                }
 386                if (baselen >= 8) {
 387                        if ((chi < chl - 1) || (ip + 1) - uname < sz)
 388                                is_shortname = 0;
 389                        break;
 390                }
 391        }
 392        if (baselen == 0) {
 393                return -EINVAL;
 394        }
 395
 396        extlen = 0;
 397        if (ext_start) {
 398                for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
 399                        chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
 400                                                ip, &ext_info);
 401                        if (chl == 0)
 402                                continue;
 403
 404                        if ((extlen + chl) > 3) {
 405                                is_shortname = 0;
 406                                break;
 407                        }
 408                        for (chi = 0; chi < chl; chi++) {
 409                                *p++ = charbuf[chi];
 410                                extlen++;
 411                        }
 412                        if (extlen >= 3) {
 413                                if (ip + 1 != end)
 414                                        is_shortname = 0;
 415                                break;
 416                        }
 417                }
 418        }
 419        ext[extlen] = '\0';
 420        base[baselen] = '\0';
 421
 422        /* Yes, it can happen. ".\xe5" would do it. */
 423        if (base[0] == DELETED_FLAG)
 424                base[0] = 0x05;
 425
 426        /* OK, at this point we know that base is not longer than 8 symbols,
 427         * ext is not longer than 3, base is nonempty, both don't contain
 428         * any bad symbols (lowercase transformed to uppercase).
 429         */
 430
 431        memset(name_res, ' ', MSDOS_NAME);
 432        memcpy(name_res, base, baselen);
 433        memcpy(name_res + 8, ext, extlen);
 434        *lcase = 0;
 435        if (is_shortname && base_info.valid && ext_info.valid) {
 436                if (vfat_find_form(dir, name_res) == 0)
 437                        return -EEXIST;
 438
 439                if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
 440                        return (base_info.upper && ext_info.upper);
 441                } else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
 442                        if ((base_info.upper || base_info.lower) &&
 443                            (ext_info.upper || ext_info.lower)) {
 444                                if (!base_info.upper && base_info.lower)
 445                                        *lcase |= CASE_LOWER_BASE;
 446                                if (!ext_info.upper && ext_info.lower)
 447                                        *lcase |= CASE_LOWER_EXT;
 448                                return 1;
 449                        }
 450                        return 0;
 451                } else {
 452                        BUG();
 453                }
 454        }
 455
 456        if (opts->numtail == 0)
 457                if (vfat_find_form(dir, name_res) < 0)
 458                        return 0;
 459
 460        /*
 461         * Try to find a unique extension.  This used to
 462         * iterate through all possibilities sequentially,
 463         * but that gave extremely bad performance.  Windows
 464         * only tries a few cases before using random
 465         * values for part of the base.
 466         */
 467
 468        if (baselen > 6) {
 469                baselen = numtail_baselen;
 470                name_res[7] = ' ';
 471        }
 472        name_res[baselen] = '~';
 473        for (i = 1; i < 10; i++) {
 474                name_res[baselen + 1] = i + '0';
 475                if (vfat_find_form(dir, name_res) < 0)
 476                        return 0;
 477        }
 478
 479        i = jiffies;
 480        sz = (jiffies >> 16) & 0x7;
 481        if (baselen > 2) {
 482                baselen = numtail2_baselen;
 483                name_res[7] = ' ';
 484        }
 485        name_res[baselen + 4] = '~';
 486        name_res[baselen + 5] = '1' + sz;
 487        while (1) {
 488                snprintf(buf, sizeof(buf), "%04X", i & 0xffff);
 489                memcpy(&name_res[baselen], buf, 4);
 490                if (vfat_find_form(dir, name_res) < 0)
 491                        break;
 492                i -= 11;
 493        }
 494        return 0;
 495}
 496
 497/* Translate a string, including coded sequences into Unicode */
 498static int
 499xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
 500             int *longlen, int *outlen, int escape, int utf8,
 501             struct nls_table *nls)
 502{
 503        const unsigned char *ip;
 504        unsigned char nc;
 505        unsigned char *op;
 506        unsigned int ec;
 507        int i, k, fill;
 508        int charlen;
 509
 510        if (utf8) {
 511                *outlen = utf8s_to_utf16s(name, len, UTF16_HOST_ENDIAN,
 512                                (wchar_t *) outname, FAT_LFN_LEN + 2);
 513                if (*outlen < 0)
 514                        return *outlen;
 515                else if (*outlen > FAT_LFN_LEN)
 516                        return -ENAMETOOLONG;
 517
 518                op = &outname[*outlen * sizeof(wchar_t)];
 519        } else {
 520                for (i = 0, ip = name, op = outname, *outlen = 0;
 521                         i < len && *outlen < FAT_LFN_LEN;
 522                         *outlen += 1) {
 523                        if (escape && (*ip == ':')) {
 524                                if (i > len - 5)
 525                                        return -EINVAL;
 526                                ec = 0;
 527                                for (k = 1; k < 5; k++) {
 528                                        nc = ip[k];
 529                                        ec <<= 4;
 530                                        if (nc >= '0' && nc <= '9') {
 531                                                ec |= nc - '0';
 532                                                continue;
 533                                        }
 534                                        if (nc >= 'a' && nc <= 'f') {
 535                                                ec |= nc - ('a' - 10);
 536                                                continue;
 537                                        }
 538                                        if (nc >= 'A' && nc <= 'F') {
 539                                                ec |= nc - ('A' - 10);
 540                                                continue;
 541                                        }
 542                                        return -EINVAL;
 543                                }
 544                                *op++ = ec & 0xFF;
 545                                *op++ = ec >> 8;
 546                                ip += 5;
 547                                i += 5;
 548                        } else {
 549                                charlen = nls->char2uni(ip, len - i,
 550                                                                        (wchar_t *)op);
 551                                if (charlen < 0)
 552                                        return -EINVAL;
 553                                ip += charlen;
 554                                i += charlen;
 555                                op += 2;
 556                        }
 557                }
 558                if (i < len)
 559                        return -ENAMETOOLONG;
 560        }
 561
 562        *longlen = *outlen;
 563        if (*outlen % 13) {
 564                *op++ = 0;
 565                *op++ = 0;
 566                *outlen += 1;
 567                if (*outlen % 13) {
 568                        fill = 13 - (*outlen % 13);
 569                        for (i = 0; i < fill; i++) {
 570                                *op++ = 0xff;
 571                                *op++ = 0xff;
 572                        }
 573                        *outlen += fill;
 574                }
 575        }
 576
 577        return 0;
 578}
 579
 580static int vfat_build_slots(struct inode *dir, const unsigned char *name,
 581                            int len, int is_dir, int cluster,
 582                            struct timespec *ts,
 583                            struct msdos_dir_slot *slots, int *nr_slots)
 584{
 585        struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
 586        struct fat_mount_options *opts = &sbi->options;
 587        struct msdos_dir_slot *ps;
 588        struct msdos_dir_entry *de;
 589        unsigned char cksum, lcase;
 590        unsigned char msdos_name[MSDOS_NAME];
 591        wchar_t *uname;
 592        __le16 time, date;
 593        u8 time_cs;
 594        int err, ulen, usize, i;
 595        loff_t offset;
 596
 597        *nr_slots = 0;
 598
 599        uname = __getname();
 600        if (!uname)
 601                return -ENOMEM;
 602
 603        err = xlate_to_uni(name, len, (unsigned char *)uname, &ulen, &usize,
 604                           opts->unicode_xlate, opts->utf8, sbi->nls_io);
 605        if (err)
 606                goto out_free;
 607
 608        err = vfat_is_used_badchars(uname, ulen);
 609        if (err)
 610                goto out_free;
 611
 612        err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
 613                                    msdos_name, &lcase);
 614        if (err < 0)
 615                goto out_free;
 616        else if (err == 1) {
 617                de = (struct msdos_dir_entry *)slots;
 618                err = 0;
 619                goto shortname;
 620        }
 621
 622        /* build the entry of long file name */
 623        cksum = fat_checksum(msdos_name);
 624
 625        *nr_slots = usize / 13;
 626        for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
 627                ps->id = i;
 628                ps->attr = ATTR_EXT;
 629                ps->reserved = 0;
 630                ps->alias_checksum = cksum;
 631                ps->start = 0;
 632                offset = (i - 1) * 13;
 633                fatwchar_to16(ps->name0_4, uname + offset, 5);
 634                fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
 635                fatwchar_to16(ps->name11_12, uname + offset + 11, 2);
 636        }
 637        slots[0].id |= 0x40;
 638        de = (struct msdos_dir_entry *)ps;
 639
 640shortname:
 641        /* build the entry of 8.3 alias name */
 642        (*nr_slots)++;
 643        memcpy(de->name, msdos_name, MSDOS_NAME);
 644        de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
 645        de->lcase = lcase;
 646        fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
 647        de->time = de->ctime = time;
 648        de->date = de->cdate = de->adate = date;
 649        de->ctime_cs = time_cs;
 650        fat_set_start(de, cluster);
 651        de->size = 0;
 652out_free:
 653        __putname(uname);
 654        return err;
 655}
 656
 657static int vfat_add_entry(struct inode *dir, struct qstr *qname, int is_dir,
 658                          int cluster, struct timespec *ts,
 659                          struct fat_slot_info *sinfo)
 660{
 661        struct msdos_dir_slot *slots;
 662        unsigned int len;
 663        int err, nr_slots;
 664
 665        len = vfat_striptail_len(qname);
 666        if (len == 0)
 667                return -ENOENT;
 668
 669        slots = kmalloc(sizeof(*slots) * MSDOS_SLOTS, GFP_NOFS);
 670        if (slots == NULL)
 671                return -ENOMEM;
 672
 673        err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
 674                               slots, &nr_slots);
 675        if (err)
 676                goto cleanup;
 677
 678        err = fat_add_entries(dir, slots, nr_slots, sinfo);
 679        if (err)
 680                goto cleanup;
 681
 682        /* update timestamp */
 683        dir->i_ctime = dir->i_mtime = dir->i_atime = *ts;
 684        if (IS_DIRSYNC(dir))
 685                (void)fat_sync_inode(dir);
 686        else
 687                mark_inode_dirty(dir);
 688cleanup:
 689        kfree(slots);
 690        return err;
 691}
 692
 693static int vfat_find(struct inode *dir, struct qstr *qname,
 694                     struct fat_slot_info *sinfo)
 695{
 696        unsigned int len = vfat_striptail_len(qname);
 697        if (len == 0)
 698                return -ENOENT;
 699        return fat_search_long(dir, qname->name, len, sinfo);
 700}
 701
 702/*
 703 * (nfsd's) anonymous disconnected dentry?
 704 * NOTE: !IS_ROOT() is not anonymous (I.e. d_splice_alias() did the job).
 705 */
 706static int vfat_d_anon_disconn(struct dentry *dentry)
 707{
 708        return IS_ROOT(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED);
 709}
 710
 711static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
 712                                  unsigned int flags)
 713{
 714        struct super_block *sb = dir->i_sb;
 715        struct fat_slot_info sinfo;
 716        struct inode *inode;
 717        struct dentry *alias;
 718        int err;
 719
 720        mutex_lock(&MSDOS_SB(sb)->s_lock);
 721
 722        err = vfat_find(dir, &dentry->d_name, &sinfo);
 723        if (err) {
 724                if (err == -ENOENT) {
 725                        inode = NULL;
 726                        goto out;
 727                }
 728                goto error;
 729        }
 730
 731        inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 732        brelse(sinfo.bh);
 733        if (IS_ERR(inode)) {
 734                err = PTR_ERR(inode);
 735                goto error;
 736        }
 737
 738        alias = d_find_alias(inode);
 739        if (alias && !vfat_d_anon_disconn(alias)) {
 740                /*
 741                 * This inode has non anonymous-DCACHE_DISCONNECTED
 742                 * dentry. This means, the user did ->lookup() by an
 743                 * another name (longname vs 8.3 alias of it) in past.
 744                 *
 745                 * Switch to new one for reason of locality if possible.
 746                 */
 747                BUG_ON(d_unhashed(alias));
 748                if (!S_ISDIR(inode->i_mode))
 749                        d_move(alias, dentry);
 750                iput(inode);
 751                mutex_unlock(&MSDOS_SB(sb)->s_lock);
 752                return alias;
 753        } else
 754                dput(alias);
 755
 756out:
 757        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 758        dentry->d_time = dentry->d_parent->d_inode->i_version;
 759        dentry = d_splice_alias(inode, dentry);
 760        if (dentry)
 761                dentry->d_time = dentry->d_parent->d_inode->i_version;
 762        return dentry;
 763
 764error:
 765        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 766        return ERR_PTR(err);
 767}
 768
 769static int vfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 770                       bool excl)
 771{
 772        struct super_block *sb = dir->i_sb;
 773        struct inode *inode;
 774        struct fat_slot_info sinfo;
 775        struct timespec ts;
 776        int err;
 777
 778        mutex_lock(&MSDOS_SB(sb)->s_lock);
 779
 780        ts = CURRENT_TIME_SEC;
 781        err = vfat_add_entry(dir, &dentry->d_name, 0, 0, &ts, &sinfo);
 782        if (err)
 783                goto out;
 784        dir->i_version++;
 785
 786        inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 787        brelse(sinfo.bh);
 788        if (IS_ERR(inode)) {
 789                err = PTR_ERR(inode);
 790                goto out;
 791        }
 792        inode->i_version++;
 793        inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
 794        /* timestamp is already written, so mark_inode_dirty() is unneeded. */
 795
 796        dentry->d_time = dentry->d_parent->d_inode->i_version;
 797        d_instantiate(dentry, inode);
 798out:
 799        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 800        return err;
 801}
 802
 803static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
 804{
 805        struct inode *inode = dentry->d_inode;
 806        struct super_block *sb = dir->i_sb;
 807        struct fat_slot_info sinfo;
 808        int err;
 809
 810        mutex_lock(&MSDOS_SB(sb)->s_lock);
 811
 812        err = fat_dir_empty(inode);
 813        if (err)
 814                goto out;
 815        err = vfat_find(dir, &dentry->d_name, &sinfo);
 816        if (err)
 817                goto out;
 818
 819        err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
 820        if (err)
 821                goto out;
 822        drop_nlink(dir);
 823
 824        clear_nlink(inode);
 825        inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
 826        fat_detach(inode);
 827out:
 828        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 829
 830        return err;
 831}
 832
 833static int vfat_unlink(struct inode *dir, struct dentry *dentry)
 834{
 835        struct inode *inode = dentry->d_inode;
 836        struct super_block *sb = dir->i_sb;
 837        struct fat_slot_info sinfo;
 838        int err;
 839
 840        mutex_lock(&MSDOS_SB(sb)->s_lock);
 841
 842        err = vfat_find(dir, &dentry->d_name, &sinfo);
 843        if (err)
 844                goto out;
 845
 846        err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
 847        if (err)
 848                goto out;
 849        clear_nlink(inode);
 850        inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
 851        fat_detach(inode);
 852out:
 853        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 854
 855        return err;
 856}
 857
 858static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 859{
 860        struct super_block *sb = dir->i_sb;
 861        struct inode *inode;
 862        struct fat_slot_info sinfo;
 863        struct timespec ts;
 864        int err, cluster;
 865
 866        mutex_lock(&MSDOS_SB(sb)->s_lock);
 867
 868        ts = CURRENT_TIME_SEC;
 869        cluster = fat_alloc_new_dir(dir, &ts);
 870        if (cluster < 0) {
 871                err = cluster;
 872                goto out;
 873        }
 874        err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
 875        if (err)
 876                goto out_free;
 877        dir->i_version++;
 878        inc_nlink(dir);
 879
 880        inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 881        brelse(sinfo.bh);
 882        if (IS_ERR(inode)) {
 883                err = PTR_ERR(inode);
 884                /* the directory was completed, just return a error */
 885                goto out;
 886        }
 887        inode->i_version++;
 888        set_nlink(inode, 2);
 889        inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
 890        /* timestamp is already written, so mark_inode_dirty() is unneeded. */
 891
 892        dentry->d_time = dentry->d_parent->d_inode->i_version;
 893        d_instantiate(dentry, inode);
 894
 895        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 896        return 0;
 897
 898out_free:
 899        fat_free_clusters(dir, cluster);
 900out:
 901        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 902        return err;
 903}
 904
 905static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
 906                       struct inode *new_dir, struct dentry *new_dentry)
 907{
 908        struct buffer_head *dotdot_bh;
 909        struct msdos_dir_entry *dotdot_de;
 910        struct inode *old_inode, *new_inode;
 911        struct fat_slot_info old_sinfo, sinfo;
 912        struct timespec ts;
 913        loff_t new_i_pos;
 914        int err, is_dir, update_dotdot, corrupt = 0;
 915        struct super_block *sb = old_dir->i_sb;
 916
 917        old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
 918        old_inode = old_dentry->d_inode;
 919        new_inode = new_dentry->d_inode;
 920        mutex_lock(&MSDOS_SB(sb)->s_lock);
 921        err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
 922        if (err)
 923                goto out;
 924
 925        is_dir = S_ISDIR(old_inode->i_mode);
 926        update_dotdot = (is_dir && old_dir != new_dir);
 927        if (update_dotdot) {
 928                if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
 929                        err = -EIO;
 930                        goto out;
 931                }
 932        }
 933
 934        ts = CURRENT_TIME_SEC;
 935        if (new_inode) {
 936                if (is_dir) {
 937                        err = fat_dir_empty(new_inode);
 938                        if (err)
 939                                goto out;
 940                }
 941                new_i_pos = MSDOS_I(new_inode)->i_pos;
 942                fat_detach(new_inode);
 943        } else {
 944                err = vfat_add_entry(new_dir, &new_dentry->d_name, is_dir, 0,
 945                                     &ts, &sinfo);
 946                if (err)
 947                        goto out;
 948                new_i_pos = sinfo.i_pos;
 949        }
 950        new_dir->i_version++;
 951
 952        fat_detach(old_inode);
 953        fat_attach(old_inode, new_i_pos);
 954        if (IS_DIRSYNC(new_dir)) {
 955                err = fat_sync_inode(old_inode);
 956                if (err)
 957                        goto error_inode;
 958        } else
 959                mark_inode_dirty(old_inode);
 960
 961        if (update_dotdot) {
 962                fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart);
 963                mark_buffer_dirty_inode(dotdot_bh, old_inode);
 964                if (IS_DIRSYNC(new_dir)) {
 965                        err = sync_dirty_buffer(dotdot_bh);
 966                        if (err)
 967                                goto error_dotdot;
 968                }
 969                drop_nlink(old_dir);
 970                if (!new_inode)
 971                        inc_nlink(new_dir);
 972        }
 973
 974        err = fat_remove_entries(old_dir, &old_sinfo);  /* and releases bh */
 975        old_sinfo.bh = NULL;
 976        if (err)
 977                goto error_dotdot;
 978        old_dir->i_version++;
 979        old_dir->i_ctime = old_dir->i_mtime = ts;
 980        if (IS_DIRSYNC(old_dir))
 981                (void)fat_sync_inode(old_dir);
 982        else
 983                mark_inode_dirty(old_dir);
 984
 985        if (new_inode) {
 986                drop_nlink(new_inode);
 987                if (is_dir)
 988                        drop_nlink(new_inode);
 989                new_inode->i_ctime = ts;
 990        }
 991out:
 992        brelse(sinfo.bh);
 993        brelse(dotdot_bh);
 994        brelse(old_sinfo.bh);
 995        mutex_unlock(&MSDOS_SB(sb)->s_lock);
 996
 997        return err;
 998
 999error_dotdot:
1000        /* data cluster is shared, serious corruption */
1001        corrupt = 1;
1002
1003        if (update_dotdot) {
1004                fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart);
1005                mark_buffer_dirty_inode(dotdot_bh, old_inode);
1006                corrupt |= sync_dirty_buffer(dotdot_bh);
1007        }
1008error_inode:
1009        fat_detach(old_inode);
1010        fat_attach(old_inode, old_sinfo.i_pos);
1011        if (new_inode) {
1012                fat_attach(new_inode, new_i_pos);
1013                if (corrupt)
1014                        corrupt |= fat_sync_inode(new_inode);
1015        } else {
1016                /*
1017                 * If new entry was not sharing the data cluster, it
1018                 * shouldn't be serious corruption.
1019                 */
1020                int err2 = fat_remove_entries(new_dir, &sinfo);
1021                if (corrupt)
1022                        corrupt |= err2;
1023                sinfo.bh = NULL;
1024        }
1025        if (corrupt < 0) {
1026                fat_fs_error(new_dir->i_sb,
1027                             "%s: Filesystem corrupted (i_pos %lld)",
1028                             __func__, sinfo.i_pos);
1029        }
1030        goto out;
1031}
1032
1033static const struct inode_operations vfat_dir_inode_operations = {
1034        .create         = vfat_create,
1035        .lookup         = vfat_lookup,
1036        .unlink         = vfat_unlink,
1037        .mkdir          = vfat_mkdir,
1038        .rmdir          = vfat_rmdir,
1039        .rename         = vfat_rename,
1040        .setattr        = fat_setattr,
1041        .getattr        = fat_getattr,
1042};
1043
1044static void setup(struct super_block *sb)
1045{
1046        MSDOS_SB(sb)->dir_ops = &vfat_dir_inode_operations;
1047        if (MSDOS_SB(sb)->options.name_check != 's')
1048                sb->s_d_op = &vfat_ci_dentry_ops;
1049        else
1050                sb->s_d_op = &vfat_dentry_ops;
1051}
1052
1053static int vfat_fill_super(struct super_block *sb, void *data, int silent)
1054{
1055        return fat_fill_super(sb, data, silent, 1, setup);
1056}
1057
1058static struct dentry *vfat_mount(struct file_system_type *fs_type,
1059                       int flags, const char *dev_name,
1060                       void *data)
1061{
1062        return mount_bdev(fs_type, flags, dev_name, data, vfat_fill_super);
1063}
1064
1065static struct file_system_type vfat_fs_type = {
1066        .owner          = THIS_MODULE,
1067        .name           = "vfat",
1068        .mount          = vfat_mount,
1069        .kill_sb        = kill_block_super,
1070        .fs_flags       = FS_REQUIRES_DEV,
1071};
1072MODULE_ALIAS_FS("vfat");
1073
1074static int __init init_vfat_fs(void)
1075{
1076        return register_filesystem(&vfat_fs_type);
1077}
1078
1079static void __exit exit_vfat_fs(void)
1080{
1081        unregister_filesystem(&vfat_fs_type);
1082}
1083
1084MODULE_LICENSE("GPL");
1085MODULE_DESCRIPTION("VFAT filesystem support");
1086MODULE_AUTHOR("Gordon Chaffee");
1087
1088module_init(init_vfat_fs)
1089module_exit(exit_vfat_fs)
1090
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