release/src-rt-6.x/linux/linux-2.6/fs/fat/file.c

   1 /*
   2  *  linux/fs/fat/file.c
   3  *
   4  *  Written 1992,1993 by Werner Almesberger
   5  *
   6  *  regular file handling primitives for fat-based filesystems
   7  */
   8
   9 #include <linux/capability.h>
  10 #include <linux/module.h>
  11 #include <linux/time.h>
  12 #include <linux/msdos_fs.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/writeback.h>
  15 #include <linux/backing-dev.h>
  16 #include <linux/blkdev.h>
  17
  18 int fat_generic_ioctl(struct inode *inode, struct file *filp,
  19                       unsigned int cmd, unsigned long arg)
  20 {
  21         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  22         u32 __user *user_attr = (u32 __user *)arg;
  23
  24         switch (cmd) {
  25         case FAT_IOCTL_GET_ATTRIBUTES:
  26         {
  27                 u32 attr;
  28
  29                 if (inode->i_ino == MSDOS_ROOT_INO)
  30                         attr = ATTR_DIR;
  31                 else
  32                         attr = fat_attr(inode);
  33
  34                 return put_user(attr, user_attr);
  35         }
  36         case FAT_IOCTL_SET_ATTRIBUTES:
  37         {
  38                 u32 attr, oldattr;
  39                 int err, is_dir = S_ISDIR(inode->i_mode);
  40                 struct iattr ia;
  41
  42                 err = get_user(attr, user_attr);
  43                 if (err)
  44                         return err;
  45
  46                 mutex_lock(&inode->i_mutex);
  47
  48                 if (IS_RDONLY(inode)) {
  49                         err = -EROFS;
  50                         goto up;
  51                 }
  52
  53                 /*
  54                  * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  55                  * prevents the user from turning us into a VFAT
  56                  * longname entry.  Also, we obviously can't set
  57                  * any of the NTFS attributes in the high 24 bits.
  58                  */
  59                 attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  60                 /* Merge in ATTR_VOLUME and ATTR_DIR */
  61                 attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  62                         (is_dir ? ATTR_DIR : 0);
  63                 oldattr = fat_attr(inode);
  64
  65                 /* Equivalent to a chmod() */
  66                 ia.ia_valid = ATTR_MODE | ATTR_CTIME;
  67                 if (is_dir) {
  68                         ia.ia_mode = MSDOS_MKMODE(attr,
  69                                 S_IRWXUGO & ~sbi->options.fs_dmask)
  70                                 | S_IFDIR;
  71                 } else {
  72                         ia.ia_mode = MSDOS_MKMODE(attr,
  73                                 (S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO))
  74                                 & ~sbi->options.fs_fmask)
  75                                 | S_IFREG;
  76                 }
  77
  78                 /* The root directory has no attributes */
  79                 if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
  80                         err = -EINVAL;
  81                         goto up;
  82                 }
  83
  84                 if (sbi->options.sys_immutable) {
  85                         if ((attr | oldattr) & ATTR_SYS) {
  86                                 if (!capable(CAP_LINUX_IMMUTABLE)) {
  87                                         err = -EPERM;
  88                                         goto up;
  89                                 }
  90                         }
  91                 }
  92
  93                 /* This MUST be done before doing anything irreversible... */
  94                 err = notify_change(filp->f_path.dentry, &ia);
  95                 if (err)
  96                         goto up;
  97
  98                 if (sbi->options.sys_immutable) {
  99                         if (attr & ATTR_SYS)
 100                                 inode->i_flags |= S_IMMUTABLE;
 101                         else
 102                                 inode->i_flags &= S_IMMUTABLE;
 103                 }
 104
 105                 MSDOS_I(inode)->i_attrs = attr & ATTR_UNUSED;
 106                 mark_inode_dirty(inode);
 107         up:
 108                 mutex_unlock(&inode->i_mutex);
 109                 return err;
 110         }
 111         default:
 112                 return -ENOTTY; /* Inappropriate ioctl for device */
 113         }
 114 }
 115
 116 static int fat_file_release(struct inode *inode, struct file *filp)
 117 {
 118         if ((filp->f_mode & FMODE_WRITE) &&
 119              MSDOS_SB(inode->i_sb)->options.flush) {
 120                 fat_flush_inodes(inode->i_sb, inode, NULL);
 121                 congestion_wait(WRITE, HZ/10);
 122         }
 123         return 0;
 124 }
 125
 126 const struct file_operations fat_file_operations = {
 127         .llseek         = generic_file_llseek,
 128         .read           = do_sync_read,
 129         .write          = do_sync_write,
 130         .aio_read       = generic_file_aio_read,
 131         .aio_write      = generic_file_aio_write,
 132         .mmap           = generic_file_mmap,
 133         .release        = fat_file_release,
 134         .ioctl          = fat_generic_ioctl,
 135         .fsync          = file_fsync,
 136         .splice_read    = generic_file_splice_read,
 137 };
 138
 139 static int fat_cont_expand(struct inode *inode, loff_t size)
 140 {
 141         struct address_space *mapping = inode->i_mapping;
 142         loff_t start = inode->i_size, count = size - inode->i_size;
 143         int err;
 144
 145         err = generic_cont_expand_simple(inode, size);
 146         if (err)
 147                 goto out;
 148
 149         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 150         mark_inode_dirty(inode);
 151         if (IS_SYNC(inode))
 152                 err = sync_page_range_nolock(inode, mapping, start, count);
 153 out:
 154         return err;
 155 }
 156
 157 /* Free all clusters after the skip'th cluster. */
 158 static int fat_free(struct inode *inode, int skip)
 159 {
 160         struct super_block *sb = inode->i_sb;
 161         int err, wait, free_start, i_start, i_logstart;
 162
 163         if (MSDOS_I(inode)->i_start == 0)
 164                 return 0;
 165
 166         fat_cache_inval_inode(inode);
 167
 168         wait = IS_DIRSYNC(inode);
 169         i_start = free_start = MSDOS_I(inode)->i_start;
 170         i_logstart = MSDOS_I(inode)->i_logstart;
 171
 172         /* First, we write the new file size. */
 173         if (!skip) {
 174                 MSDOS_I(inode)->i_start = 0;
 175                 MSDOS_I(inode)->i_logstart = 0;
 176         }
 177         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 178         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 179         if (wait) {
 180                 err = fat_sync_inode(inode);
 181                 if (err) {
 182                         MSDOS_I(inode)->i_start = i_start;
 183                         MSDOS_I(inode)->i_logstart = i_logstart;
 184                         return err;
 185                 }
 186         } else
 187                 mark_inode_dirty(inode);
 188
 189         /* Write a new EOF, and get the remaining cluster chain for freeing. */
 190         if (skip) {
 191                 struct fat_entry fatent;
 192                 int ret, fclus, dclus;
 193
 194                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 195                 if (ret < 0)
 196                         return ret;
 197                 else if (ret == FAT_ENT_EOF)
 198                         return 0;
 199
 200                 fatent_init(&fatent);
 201                 ret = fat_ent_read(inode, &fatent, dclus);
 202                 if (ret == FAT_ENT_EOF) {
 203                         fatent_brelse(&fatent);
 204                         return 0;
 205                 } else if (ret == FAT_ENT_FREE) {
 206                         fat_fs_panic(sb,
 207                                      "%s: invalid cluster chain (i_pos %lld)",
 208                                      __FUNCTION__, MSDOS_I(inode)->i_pos);
 209                         ret = -EIO;
 210                 } else if (ret > 0) {
 211                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 212                         if (err)
 213                                 ret = err;
 214                 }
 215                 fatent_brelse(&fatent);
 216                 if (ret < 0)
 217                         return ret;
 218
 219                 free_start = ret;
 220         }
 221         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 222
 223         /* Freeing the remained cluster chain */
 224         return fat_free_clusters(inode, free_start);
 225 }
 226
 227 void fat_truncate(struct inode *inode)
 228 {
 229         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 230         const unsigned int cluster_size = sbi->cluster_size;
 231         int nr_clusters;
 232
 233         /*
 234          * This protects against truncating a file bigger than it was then
 235          * trying to write into the hole.
 236          */
 237         if (MSDOS_I(inode)->mmu_private > inode->i_size)
 238                 MSDOS_I(inode)->mmu_private = inode->i_size;
 239
 240         nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits;
 241
 242         fat_free(inode, nr_clusters);
 243         fat_flush_inodes(inode->i_sb, inode, NULL);
 244 }
 245
 246 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 247 {
 248         struct inode *inode = dentry->d_inode;
 249         generic_fillattr(inode, stat);
 250         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 251         return 0;
 252 }
 253 EXPORT_SYMBOL_GPL(fat_getattr);
 254
 255 static int fat_check_mode(const struct msdos_sb_info *sbi, struct inode *inode,
 256                           mode_t mode)
 257 {
 258         mode_t mask, req = mode & ~S_IFMT;
 259
 260         if (S_ISREG(mode))
 261                 mask = sbi->options.fs_fmask;
 262         else
 263                 mask = sbi->options.fs_dmask;
 264
 265         /*
 266          * Of the r and x bits, all (subject to umask) must be present. Of the
 267          * w bits, either all (subject to umask) or none must be present.
 268          */
 269         req &= ~mask;
 270         if ((req & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 271                 return -EPERM;
 272         if ((req & S_IWUGO) && ((req & S_IWUGO) != (S_IWUGO & ~mask)))
 273                 return -EPERM;
 274
 275         return 0;
 276 }
 277
 278 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 279 {
 280         mode_t allow_utime = sbi->options.allow_utime;
 281
 282         if (current->fsuid != inode->i_uid) {
 283                 if (in_group_p(inode->i_gid))
 284                         allow_utime >>= 3;
 285                 if (allow_utime & MAY_WRITE)
 286                         return 1;
 287         }
 288
 289         /* use a default check */
 290         return 0;
 291 }
 292
 293 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 294 {
 295         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 296         struct inode *inode = dentry->d_inode;
 297         int mask, error = 0;
 298         unsigned int ia_valid;
 299
 300         /*
 301          * Expand the file. Since inode_setattr() updates ->i_size
 302          * before calling the ->truncate(), but FAT needs to fill the
 303          * hole before it.
 304          */
 305         if (attr->ia_valid & ATTR_SIZE) {
 306                 if (attr->ia_size > inode->i_size) {
 307 #if 1
 308                         /* FAT cannot truncate to a longer file */
 309                         error = -EPERM;
 310                         goto out;
 311 #else
 312                         error = fat_cont_expand(inode, attr->ia_size);
 313                         if (error || attr->ia_valid == ATTR_SIZE)
 314                                 goto out;
 315                         attr->ia_valid &= ~ATTR_SIZE;
 316 #endif
 317                 }
 318         }
 319
 320         /* Check for setting the inode time. */
 321         ia_valid = attr->ia_valid;
 322         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
 323                 if (fat_allow_set_time(sbi, inode))
 324                         attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET);
 325         }
 326
 327         error = inode_change_ok(inode, attr);
 328         attr->ia_valid = ia_valid;
 329         if (error) {
 330                 if (sbi->options.quiet)
 331                         error = 0;
 332                 goto out;
 333         }
 334         if (((attr->ia_valid & ATTR_UID) &&
 335              (attr->ia_uid != sbi->options.fs_uid)) ||
 336             ((attr->ia_valid & ATTR_GID) &&
 337              (attr->ia_gid != sbi->options.fs_gid)) ||
 338             ((attr->ia_valid & ATTR_MODE) &&
 339              fat_check_mode(sbi, inode, attr->ia_mode) < 0))
 340                 error = -EPERM;
 341
 342         if (error) {
 343                 if (sbi->options.quiet)
 344                         error = 0;
 345                 goto out;
 346         }
 347
 348         error = inode_setattr(inode, attr);
 349         if (error)
 350                 goto out;
 351
 352         if (S_ISDIR(inode->i_mode))
 353                 mask = sbi->options.fs_dmask;
 354         else
 355                 mask = sbi->options.fs_fmask;
 356         inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask);
 357 out:
 358         return error;
 359 }
 360 EXPORT_SYMBOL_GPL(fat_setattr);
 361
 362 const struct inode_operations fat_file_inode_operations = {
 363         .truncate       = fat_truncate,
 364         .setattr        = fat_setattr,
 365         .getattr        = fat_getattr,
 366 };