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namei.c

/*
 *  linux/fs/vfat/namei.c
 *
 *  Written 1992,1993 by Werner Almesberger
 *
 *  Windows95/Windows NT compatible extended MSDOS filesystem
 *    by Gordon Chaffee Copyright (C) 1995.  Send bug reports for the
 *    VFAT filesystem to <chaffee@cs.berkeley.edu>.  Specify
 *    what file operation caused you trouble and if you can duplicate
 *    the problem, send a script that demonstrates it.
 *
 *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
 *
 *  Support Multibyte characters and cleanup by
 *                      OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
 */

#include <linux/module.h>

#include <linux/jiffies.h>
#include <linux/msdos_fs.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/namei.h>

static int vfat_revalidate(struct dentry *dentry, struct nameidata *nd)
{
      int ret = 1;

      if (!dentry->d_inode &&
          nd && !(nd->flags & LOOKUP_CONTINUE) && (nd->flags & LOOKUP_CREATE))
            /*
             * negative dentry is dropped, in order to make sure
             * to use the name which a user desires if this is
             * create path.
             */
            ret = 0;
      else {
            spin_lock(&dentry->d_lock);
            if (dentry->d_time != dentry->d_parent->d_inode->i_version)
                  ret = 0;
            spin_unlock(&dentry->d_lock);
      }
      return ret;
}

/* returns the length of a struct qstr, ignoring trailing dots */
static unsigned int vfat_striptail_len(struct qstr *qstr)
{
      unsigned int len = qstr->len;

      while (len && qstr->name[len - 1] == '.')
            len--;
      return len;
}

/*
 * Compute the hash for the vfat name corresponding to the dentry.
 * Note: if the name is invalid, we leave the hash code unchanged so
 * that the existing dentry can be used. The vfat fs routines will
 * return ENOENT or EINVAL as appropriate.
 */
static int vfat_hash(struct dentry *dentry, struct qstr *qstr)
{
      qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
      return 0;
}

/*
 * Compute the hash for the vfat name corresponding to the dentry.
 * Note: if the name is invalid, we leave the hash code unchanged so
 * that the existing dentry can be used. The vfat fs routines will
 * return ENOENT or EINVAL as appropriate.
 */
static int vfat_hashi(struct dentry *dentry, struct qstr *qstr)
{
      struct nls_table *t = MSDOS_SB(dentry->d_inode->i_sb)->nls_io;
      const unsigned char *name;
      unsigned int len;
      unsigned long hash;

      name = qstr->name;
      len = vfat_striptail_len(qstr);

      hash = init_name_hash();
      while (len--)
            hash = partial_name_hash(nls_tolower(t, *name++), hash);
      qstr->hash = end_name_hash(hash);

      return 0;
}

/*
 * Case insensitive compare of two vfat names.
 */
static int vfat_cmpi(struct dentry *dentry, struct qstr *a, struct qstr *b)
{
      struct nls_table *t = MSDOS_SB(dentry->d_inode->i_sb)->nls_io;
      unsigned int alen, blen;

      /* A filename cannot end in '.' or we treat it like it has none */
      alen = vfat_striptail_len(a);
      blen = vfat_striptail_len(b);
      if (alen == blen) {
            if (nls_strnicmp(t, a->name, b->name, alen) == 0)
                  return 0;
      }
      return 1;
}

/*
 * Case sensitive compare of two vfat names.
 */
static int vfat_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b)
{
      unsigned int alen, blen;

      /* A filename cannot end in '.' or we treat it like it has none */
      alen = vfat_striptail_len(a);
      blen = vfat_striptail_len(b);
      if (alen == blen) {
            if (strncmp(a->name, b->name, alen) == 0)
                  return 0;
      }
      return 1;
}

static struct dentry_operations vfat_dentry_ops[4] = {
      {
            .d_hash           = vfat_hashi,
            .d_compare  = vfat_cmpi,
      },
      {
            .d_revalidate     = vfat_revalidate,
            .d_hash           = vfat_hashi,
            .d_compare  = vfat_cmpi,
      },
      {
            .d_hash           = vfat_hash,
            .d_compare  = vfat_cmp,
      },
      {
            .d_revalidate     = vfat_revalidate,
            .d_hash           = vfat_hash,
            .d_compare  = vfat_cmp,
      }
};

/* Characters that are undesirable in an MS-DOS file name */

static inline wchar_t vfat_bad_char(wchar_t w)
{
      return (w < 0x0020)
          || (w == '*') || (w == '?') || (w == '<') || (w == '>')
          || (w == '|') || (w == '"') || (w == ':') || (w == '/')
          || (w == '\\');
}

static inline wchar_t vfat_replace_char(wchar_t w)
{
      return (w == '[') || (w == ']') || (w == ';') || (w == ',')
          || (w == '+') || (w == '=');
}

static wchar_t vfat_skip_char(wchar_t w)
{
      return (w == '.') || (w == ' ');
}

static inline int vfat_is_used_badchars(const wchar_t *s, int len)
{
      int i;

      for (i = 0; i < len; i++)
            if (vfat_bad_char(s[i]))
                  return -EINVAL;
      return 0;
}

static int vfat_valid_longname(const unsigned char *name, unsigned int len)
{
      if (name[len - 1] == ' ')
            return -EINVAL;
      if (len >= 256)
            return -ENAMETOOLONG;
      return 0;
}

static int vfat_find_form(struct inode *dir, unsigned char *name)
{
      struct fat_slot_info sinfo;
      int err = fat_scan(dir, name, &sinfo);
      if (err)
            return -ENOENT;
      brelse(sinfo.bh);
      return 0;
}

/*
 * 1) Valid characters for the 8.3 format alias are any combination of
 * letters, uppercase alphabets, digits, any of the
 * following special characters:
 *     $ % ' ` - @ { } ~ ! # ( ) & _ ^
 * In this case Longfilename is not stored in disk.
 *
 * WinNT's Extension:
 * File name and extension name is contain uppercase/lowercase
 * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
 *
 * 2) File name is 8.3 format, but it contain the uppercase and
 * lowercase char, muliti bytes char, etc. In this case numtail is not
 * added, but Longfilename is stored.
 *
 * 3) When the one except for the above, or the following special
 * character are contained:
 *        .   [ ] ; , + =
 * numtail is added, and Longfilename must be stored in disk .
 */
struct shortname_info {
      unsigned char lower:1,
                  upper:1,
                  valid:1;
};
#define INIT_SHORTNAME_INFO(x)      do {        \
      (x)->lower = 1;                     \
      (x)->upper = 1;                     \
      (x)->valid = 1;                     \
} while (0)

static inline int to_shortname_char(struct nls_table *nls,
                            unsigned char *buf, int buf_size,
                            wchar_t *src, struct shortname_info *info)
{
      int len;

      if (vfat_skip_char(*src)) {
            info->valid = 0;
            return 0;
      }
      if (vfat_replace_char(*src)) {
            info->valid = 0;
            buf[0] = '_';
            return 1;
      }

      len = nls->uni2char(*src, buf, buf_size);
      if (len <= 0) {
            info->valid = 0;
            buf[0] = '_';
            len = 1;
      } else if (len == 1) {
            unsigned char prev = buf[0];

            if (buf[0] >= 0x7F) {
                  info->lower = 0;
                  info->upper = 0;
            }

            buf[0] = nls_toupper(nls, buf[0]);
            if (isalpha(buf[0])) {
                  if (buf[0] == prev)
                        info->lower = 0;
                  else
                        info->upper = 0;
            }
      } else {
            info->lower = 0;
            info->upper = 0;
      }

      return len;
}

/*
 * Given a valid longname, create a unique shortname.  Make sure the
 * shortname does not exist
 * Returns negative number on error, 0 for a normal
 * return, and 1 for valid shortname
 */
static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
                         wchar_t *uname, int ulen,
                         unsigned char *name_res, unsigned char *lcase)
{
      struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options;
      wchar_t *ip, *ext_start, *end, *name_start;
      unsigned char base[9], ext[4], buf[8], *p;
      unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
      int chl, chi;
      int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
      int is_shortname;
      struct shortname_info base_info, ext_info;

      is_shortname = 1;
      INIT_SHORTNAME_INFO(&base_info);
      INIT_SHORTNAME_INFO(&ext_info);

      /* Now, we need to create a shortname from the long name */
      ext_start = end = &uname[ulen];
      while (--ext_start >= uname) {
            if (*ext_start == 0x002E) {   /* is `.' */
                  if (ext_start == end - 1) {
                        sz = ulen;
                        ext_start = NULL;
                  }
                  break;
            }
      }

      if (ext_start == uname - 1) {
            sz = ulen;
            ext_start = NULL;
      } else if (ext_start) {
            /*
             * Names which start with a dot could be just
             * an extension eg. "...test".  In this case Win95
             * uses the extension as the name and sets no extension.
             */
            name_start = &uname[0];
            while (name_start < ext_start) {
                  if (!vfat_skip_char(*name_start))
                        break;
                  name_start++;
            }
            if (name_start != ext_start) {
                  sz = ext_start - uname;
                  ext_start++;
            } else {
                  sz = ulen;
                  ext_start = NULL;
            }
      }

      numtail_baselen = 6;
      numtail2_baselen = 2;
      for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
            chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
                              ip, &base_info);
            if (chl == 0)
                  continue;

            if (baselen < 2 && (baselen + chl) > 2)
                  numtail2_baselen = baselen;
            if (baselen < 6 && (baselen + chl) > 6)
                  numtail_baselen = baselen;
            for (chi = 0; chi < chl; chi++) {
                  *p++ = charbuf[chi];
                  baselen++;
                  if (baselen >= 8)
                        break;
            }
            if (baselen >= 8) {
                  if ((chi < chl - 1) || (ip + 1) - uname < sz)
                        is_shortname = 0;
                  break;
            }
      }
      if (baselen == 0) {
            return -EINVAL;
      }

      extlen = 0;
      if (ext_start) {
            for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
                  chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
                                    ip, &ext_info);
                  if (chl == 0)
                        continue;

                  if ((extlen + chl) > 3) {
                        is_shortname = 0;
                        break;
                  }
                  for (chi = 0; chi < chl; chi++) {
                        *p++ = charbuf[chi];
                        extlen++;
                  }
                  if (extlen >= 3) {
                        if (ip + 1 != end)
                              is_shortname = 0;
                        break;
                  }
            }
      }
      ext[extlen] = '\0';
      base[baselen] = '\0';

      /* Yes, it can happen. ".\xe5" would do it. */
      if (base[0] == DELETED_FLAG)
            base[0] = 0x05;

      /* OK, at this point we know that base is not longer than 8 symbols,
       * ext is not longer than 3, base is nonempty, both don't contain
       * any bad symbols (lowercase transformed to uppercase).
       */

      memset(name_res, ' ', MSDOS_NAME);
      memcpy(name_res, base, baselen);
      memcpy(name_res + 8, ext, extlen);
      *lcase = 0;
      if (is_shortname && base_info.valid && ext_info.valid) {
            if (vfat_find_form(dir, name_res) == 0)
                  return -EEXIST;

            if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
                  return (base_info.upper && ext_info.upper);
            } else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
                  if ((base_info.upper || base_info.lower) &&
                      (ext_info.upper || ext_info.lower)) {
                        if (!base_info.upper && base_info.lower)
                              *lcase |= CASE_LOWER_BASE;
                        if (!ext_info.upper && ext_info.lower)
                              *lcase |= CASE_LOWER_EXT;
                        return 1;
                  }
                  return 0;
            } else {
                  BUG();
            }
      }

      if (opts->numtail == 0)
            if (vfat_find_form(dir, name_res) < 0)
                  return 0;

      /*
       * Try to find a unique extension.  This used to
       * iterate through all possibilities sequentially,
       * but that gave extremely bad performance.  Windows
       * only tries a few cases before using random
       * values for part of the base.
       */

      if (baselen > 6) {
            baselen = numtail_baselen;
            name_res[7] = ' ';
      }
      name_res[baselen] = '~';
      for (i = 1; i < 10; i++) {
            name_res[baselen + 1] = i + '0';
            if (vfat_find_form(dir, name_res) < 0)
                  return 0;
      }

      i = jiffies & 0xffff;
      sz = (jiffies >> 16) & 0x7;
      if (baselen > 2) {
            baselen = numtail2_baselen;
            name_res[7] = ' ';
      }
      name_res[baselen + 4] = '~';
      name_res[baselen + 5] = '1' + sz;
      while (1) {
            sprintf(buf, "%04X", i);
            memcpy(&name_res[baselen], buf, 4);
            if (vfat_find_form(dir, name_res) < 0)
                  break;
            i -= 11;
      }
      return 0;
}

/* Translate a string, including coded sequences into Unicode */
static int
xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
           int *longlen, int *outlen, int escape, int utf8,
           struct nls_table *nls)
{
      const unsigned char *ip;
      unsigned char nc;
      unsigned char *op;
      unsigned int ec;
      int i, k, fill;
      int charlen;

      if (utf8) {
            int name_len = strlen(name);

            *outlen = utf8_mbstowcs((wchar_t *)outname, name, PAGE_SIZE);

            /*
             * We stripped '.'s before and set len appropriately,
             * but utf8_mbstowcs doesn't care about len
             */
            *outlen -= (name_len - len);

            op = &outname[*outlen * sizeof(wchar_t)];
      } else {
            if (nls) {
                  for (i = 0, ip = name, op = outname, *outlen = 0;
                       i < len && *outlen <= 260;
                       *outlen += 1)
                  {
                        if (escape && (*ip == ':')) {
                              if (i > len - 5)
                                    return -EINVAL;
                              ec = 0;
                              for (k = 1; k < 5; k++) {
                                    nc = ip[k];
                                    ec <<= 4;
                                    if (nc >= '0' && nc <= '9') {
                                          ec |= nc - '0';
                                          continue;
                                    }
                                    if (nc >= 'a' && nc <= 'f') {
                                          ec |= nc - ('a' - 10);
                                          continue;
                                    }
                                    if (nc >= 'A' && nc <= 'F') {
                                          ec |= nc - ('A' - 10);
                                          continue;
                                    }
                                    return -EINVAL;
                              }
                              *op++ = ec & 0xFF;
                              *op++ = ec >> 8;
                              ip += 5;
                              i += 5;
                        } else {
                              if ((charlen = nls->char2uni(ip, len - i, (wchar_t *)op)) < 0)
                                    return -EINVAL;
                              ip += charlen;
                              i += charlen;
                              op += 2;
                        }
                  }
            } else {
                  for (i = 0, ip = name, op = outname, *outlen = 0;
                       i < len && *outlen <= 260;
                       i++, *outlen += 1)
                  {
                        *op++ = *ip++;
                        *op++ = 0;
                  }
            }
      }
      if (*outlen > 260)
            return -ENAMETOOLONG;

      *longlen = *outlen;
      if (*outlen % 13) {
            *op++ = 0;
            *op++ = 0;
            *outlen += 1;
            if (*outlen % 13) {
                  fill = 13 - (*outlen % 13);
                  for (i = 0; i < fill; i++) {
                        *op++ = 0xff;
                        *op++ = 0xff;
                  }
                  *outlen += fill;
            }
      }

      return 0;
}

static int vfat_build_slots(struct inode *dir, const unsigned char *name,
                      int len, int is_dir, int cluster,
                      struct timespec *ts,
                      struct msdos_dir_slot *slots, int *nr_slots)
{
      struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
      struct fat_mount_options *opts = &sbi->options;
      struct msdos_dir_slot *ps;
      struct msdos_dir_entry *de;
      unsigned long page;
      unsigned char cksum, lcase;
      unsigned char msdos_name[MSDOS_NAME];
      wchar_t *uname;
      __le16 time, date;
      int err, ulen, usize, i;
      loff_t offset;

      *nr_slots = 0;
      err = vfat_valid_longname(name, len);
      if (err)
            return err;

      page = __get_free_page(GFP_KERNEL);
      if (!page)
            return -ENOMEM;

      uname = (wchar_t *)page;
      err = xlate_to_uni(name, len, (unsigned char *)uname, &ulen, &usize,
                     opts->unicode_xlate, opts->utf8, sbi->nls_io);
      if (err)
            goto out_free;

      err = vfat_is_used_badchars(uname, ulen);
      if (err)
            goto out_free;

      err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
                            msdos_name, &lcase);
      if (err < 0)
            goto out_free;
      else if (err == 1) {
            de = (struct msdos_dir_entry *)slots;
            err = 0;
            goto shortname;
      }

      /* build the entry of long file name */
      cksum = fat_checksum(msdos_name);

      *nr_slots = usize / 13;
      for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
            ps->id = i;
            ps->attr = ATTR_EXT;
            ps->reserved = 0;
            ps->alias_checksum = cksum;
            ps->start = 0;
            offset = (i - 1) * 13;
            fatwchar_to16(ps->name0_4, uname + offset, 5);
            fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
            fatwchar_to16(ps->name11_12, uname + offset + 11, 2);
      }
      slots[0].id |= 0x40;
      de = (struct msdos_dir_entry *)ps;

shortname:
      /* build the entry of 8.3 alias name */
      (*nr_slots)++;
      memcpy(de->name, msdos_name, MSDOS_NAME);
      de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
      de->lcase = lcase;
      fat_date_unix2dos(ts->tv_sec, &time, &date);
      de->time = de->ctime = time;
      de->date = de->cdate = de->adate = date;
      de->ctime_cs = 0;
      de->start = cpu_to_le16(cluster);
      de->starthi = cpu_to_le16(cluster >> 16);
      de->size = 0;
out_free:
      free_page(page);
      return err;
}

static int vfat_add_entry(struct inode *dir, struct qstr *qname, int is_dir,
                    int cluster, struct timespec *ts,
                    struct fat_slot_info *sinfo)
{
      struct msdos_dir_slot *slots;
      unsigned int len;
      int err, nr_slots;

      len = vfat_striptail_len(qname);
      if (len == 0)
            return -ENOENT;

      slots = kmalloc(sizeof(*slots) * MSDOS_SLOTS, GFP_KERNEL);
      if (slots == NULL)
            return -ENOMEM;

      err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
                         slots, &nr_slots);
      if (err)
            goto cleanup;

      err = fat_add_entries(dir, slots, nr_slots, sinfo);
      if (err)
            goto cleanup;

      /* update timestamp */
      dir->i_ctime = dir->i_mtime = dir->i_atime = *ts;
      if (IS_DIRSYNC(dir))
            (void)fat_sync_inode(dir);
      else
            mark_inode_dirty(dir);
cleanup:
      kfree(slots);
      return err;
}

static int vfat_find(struct inode *dir, struct qstr *qname,
                 struct fat_slot_info *sinfo)
{
      unsigned int len = vfat_striptail_len(qname);
      if (len == 0)
            return -ENOENT;
      return fat_search_long(dir, qname->name, len, sinfo);
}

static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
                          struct nameidata *nd)
{
      struct super_block *sb = dir->i_sb;
      struct fat_slot_info sinfo;
      struct inode *inode = NULL;
      struct dentry *alias;
      int err, table;

      lock_kernel();
      table = (MSDOS_SB(sb)->options.name_check == 's') ? 2 : 0;
      dentry->d_op = &vfat_dentry_ops[table];

      err = vfat_find(dir, &dentry->d_name, &sinfo);
      if (err) {
            table++;
            goto error;
      }
      inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
      brelse(sinfo.bh);
      if (IS_ERR(inode)) {
            unlock_kernel();
            return ERR_PTR(PTR_ERR(inode));
      }
      alias = d_find_alias(inode);
      if (alias) {
            if (d_invalidate(alias) == 0)
                  dput(alias);
            else {
                  iput(inode);
                  unlock_kernel();
                  return alias;
            }

      }
error:
      unlock_kernel();
      dentry->d_op = &vfat_dentry_ops[table];
      dentry->d_time = dentry->d_parent->d_inode->i_version;
      dentry = d_splice_alias(inode, dentry);
      if (dentry) {
            dentry->d_op = &vfat_dentry_ops[table];
            dentry->d_time = dentry->d_parent->d_inode->i_version;
      }
      return dentry;
}

static int vfat_create(struct inode *dir, struct dentry *dentry, int mode,
                   struct nameidata *nd)
{
      struct super_block *sb = dir->i_sb;
      struct inode *inode;
      struct fat_slot_info sinfo;
      struct timespec ts;
      int err;

      lock_kernel();

      ts = CURRENT_TIME_SEC;
      err = vfat_add_entry(dir, &dentry->d_name, 0, 0, &ts, &sinfo);
      if (err)
            goto out;
      dir->i_version++;

      inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
      brelse(sinfo.bh);
      if (IS_ERR(inode)) {
            err = PTR_ERR(inode);
            goto out;
      }
      inode->i_version++;
      inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
      /* timestamp is already written, so mark_inode_dirty() is unneeded. */

      dentry->d_time = dentry->d_parent->d_inode->i_version;
      d_instantiate(dentry, inode);
out:
      unlock_kernel();
      return err;
}

static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
{
      struct inode *inode = dentry->d_inode;
      struct fat_slot_info sinfo;
      int err;

      lock_kernel();

      err = fat_dir_empty(inode);
      if (err)
            goto out;
      err = vfat_find(dir, &dentry->d_name, &sinfo);
      if (err)
            goto out;

      err = fat_remove_entries(dir, &sinfo);    /* and releases bh */
      if (err)
            goto out;
      drop_nlink(dir);

      clear_nlink(inode);
      inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
      fat_detach(inode);
out:
      unlock_kernel();

      return err;
}

static int vfat_unlink(struct inode *dir, struct dentry *dentry)
{
      struct inode *inode = dentry->d_inode;
      struct fat_slot_info sinfo;
      int err;

      lock_kernel();

      err = vfat_find(dir, &dentry->d_name, &sinfo);
      if (err)
            goto out;

      err = fat_remove_entries(dir, &sinfo);    /* and releases bh */
      if (err)
            goto out;
      clear_nlink(inode);
      inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
      fat_detach(inode);
out:
      unlock_kernel();

      return err;
}

static int vfat_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
      struct super_block *sb = dir->i_sb;
      struct inode *inode;
      struct fat_slot_info sinfo;
      struct timespec ts;
      int err, cluster;

      lock_kernel();

      ts = CURRENT_TIME_SEC;
      cluster = fat_alloc_new_dir(dir, &ts);
      if (cluster < 0) {
            err = cluster;
            goto out;
      }
      err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
      if (err)
            goto out_free;
      dir->i_version++;
      inc_nlink(dir);

      inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
      brelse(sinfo.bh);
      if (IS_ERR(inode)) {
            err = PTR_ERR(inode);
            /* the directory was completed, just return a error */
            goto out;
      }
      inode->i_version++;
      inode->i_nlink = 2;
      inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
      /* timestamp is already written, so mark_inode_dirty() is unneeded. */

      dentry->d_time = dentry->d_parent->d_inode->i_version;
      d_instantiate(dentry, inode);

      unlock_kernel();
      return 0;

out_free:
      fat_free_clusters(dir, cluster);
out:
      unlock_kernel();
      return err;
}

static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
                   struct inode *new_dir, struct dentry *new_dentry)
{
      struct buffer_head *dotdot_bh;
      struct msdos_dir_entry *dotdot_de;
      struct inode *old_inode, *new_inode;
      struct fat_slot_info old_sinfo, sinfo;
      struct timespec ts;
      loff_t dotdot_i_pos, new_i_pos;
      int err, is_dir, update_dotdot, corrupt = 0;

      old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
      old_inode = old_dentry->d_inode;
      new_inode = new_dentry->d_inode;
      lock_kernel();
      err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
      if (err)
            goto out;

      is_dir = S_ISDIR(old_inode->i_mode);
      update_dotdot = (is_dir && old_dir != new_dir);
      if (update_dotdot) {
            if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
                               &dotdot_i_pos) < 0) {
                  err = -EIO;
                  goto out;
            }
      }

      ts = CURRENT_TIME_SEC;
      if (new_inode) {
            if (is_dir) {
                  err = fat_dir_empty(new_inode);
                  if (err)
                        goto out;
            }
            new_i_pos = MSDOS_I(new_inode)->i_pos;
            fat_detach(new_inode);
      } else {
            err = vfat_add_entry(new_dir, &new_dentry->d_name, is_dir, 0,
                             &ts, &sinfo);
            if (err)
                  goto out;
            new_i_pos = sinfo.i_pos;
      }
      new_dir->i_version++;

      fat_detach(old_inode);
      fat_attach(old_inode, new_i_pos);
      if (IS_DIRSYNC(new_dir)) {
            err = fat_sync_inode(old_inode);
            if (err)
                  goto error_inode;
      } else
            mark_inode_dirty(old_inode);

      if (update_dotdot) {
            int start = MSDOS_I(new_dir)->i_logstart;
            dotdot_de->start = cpu_to_le16(start);
            dotdot_de->starthi = cpu_to_le16(start >> 16);
            mark_buffer_dirty(dotdot_bh);
            if (IS_DIRSYNC(new_dir)) {
                  err = sync_dirty_buffer(dotdot_bh);
                  if (err)
                        goto error_dotdot;
            }
            drop_nlink(old_dir);
            if (!new_inode)
                  inc_nlink(new_dir);
      }

      err = fat_remove_entries(old_dir, &old_sinfo);  /* and releases bh */
      old_sinfo.bh = NULL;
      if (err)
            goto error_dotdot;
      old_dir->i_version++;
      old_dir->i_ctime = old_dir->i_mtime = ts;
      if (IS_DIRSYNC(old_dir))
            (void)fat_sync_inode(old_dir);
      else
            mark_inode_dirty(old_dir);

      if (new_inode) {
            drop_nlink(new_inode);
            if (is_dir)
                  drop_nlink(new_inode);
            new_inode->i_ctime = ts;
      }
out:
      brelse(sinfo.bh);
      brelse(dotdot_bh);
      brelse(old_sinfo.bh);
      unlock_kernel();

      return err;

error_dotdot:
      /* data cluster is shared, serious corruption */
      corrupt = 1;

      if (update_dotdot) {
            int start = MSDOS_I(old_dir)->i_logstart;
            dotdot_de->start = cpu_to_le16(start);
            dotdot_de->starthi = cpu_to_le16(start >> 16);
            mark_buffer_dirty(dotdot_bh);
            corrupt |= sync_dirty_buffer(dotdot_bh);
      }
error_inode:
      fat_detach(old_inode);
      fat_attach(old_inode, old_sinfo.i_pos);
      if (new_inode) {
            fat_attach(new_inode, new_i_pos);
            if (corrupt)
                  corrupt |= fat_sync_inode(new_inode);
      } else {
            /*
             * If new entry was not sharing the data cluster, it
             * shouldn't be serious corruption.
             */
            int err2 = fat_remove_entries(new_dir, &sinfo);
            if (corrupt)
                  corrupt |= err2;
            sinfo.bh = NULL;
      }
      if (corrupt < 0) {
            fat_fs_panic(new_dir->i_sb,
                       "%s: Filesystem corrupted (i_pos %lld)",
                       __FUNCTION__, sinfo.i_pos);
      }
      goto out;
}

static const struct inode_operations vfat_dir_inode_operations = {
      .create           = vfat_create,
      .lookup           = vfat_lookup,
      .unlink           = vfat_unlink,
      .mkdir            = vfat_mkdir,
      .rmdir            = vfat_rmdir,
      .rename           = vfat_rename,
      .setattr    = fat_notify_change,
      .getattr    = fat_getattr,
};

static int vfat_fill_super(struct super_block *sb, void *data, int silent)
{
      int res;

      res = fat_fill_super(sb, data, silent, &vfat_dir_inode_operations, 1);
      if (res)
            return res;

      if (MSDOS_SB(sb)->options.name_check != 's')
            sb->s_root->d_op = &vfat_dentry_ops[0];
      else
            sb->s_root->d_op = &vfat_dentry_ops[2];

      return 0;
}

static int vfat_get_sb(struct file_system_type *fs_type,
                   int flags, const char *dev_name,
                   void *data, struct vfsmount *mnt)
{
      return get_sb_bdev(fs_type, flags, dev_name, data, vfat_fill_super,
                     mnt);
}

static struct file_system_type vfat_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "vfat",
      .get_sb           = vfat_get_sb,
      .kill_sb    = kill_block_super,
      .fs_flags   = FS_REQUIRES_DEV,
};

static int __init init_vfat_fs(void)
{
      return register_filesystem(&vfat_fs_type);
}

static void __exit exit_vfat_fs(void)
{
      unregister_filesystem(&vfat_fs_type);
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("VFAT filesystem support");
MODULE_AUTHOR("Gordon Chaffee");

module_init(init_vfat_fs)
module_exit(exit_vfat_fs)

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