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