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