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