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