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 static ssize_t fat_file_aio_write(struct kiocb *iocb, const char __user *buf,
  16                                   size_t count, loff_t pos)
  17 {
  18         struct inode *inode = iocb->ki_filp->f_dentry->d_inode;
  19         int retval;
  20
  21         retval = generic_file_aio_write(iocb, buf, count, pos);
  22         if (retval > 0) {
  23                 inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
  24                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
  25                 mark_inode_dirty(inode);
  26 //              check the locking rules
  27 //              if (IS_SYNC(inode))
  28 //                      fat_sync_inode(inode);
  29         }
  30         return retval;
  31 }
  32
  33 static ssize_t fat_file_writev(struct file *filp, const struct iovec *iov,
  34                                unsigned long nr_segs, loff_t *ppos)
  35 {
  36         struct inode *inode = filp->f_dentry->d_inode;
  37         int retval;
  38
  39         retval = generic_file_writev(filp, iov, nr_segs, ppos);
  40         if (retval > 0) {
  41                 inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
  42                 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
  43                 mark_inode_dirty(inode);
  44         }
  45         return retval;
  46 }
  47
  48 int fat_generic_ioctl(struct inode *inode, struct file *filp,
  49                       unsigned int cmd, unsigned long arg)
  50 {
  51         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  52         u32 __user *user_attr = (u32 __user *)arg;
  53
  54         switch (cmd) {
  55         case FAT_IOCTL_GET_ATTRIBUTES:
  56         {
  57                 u32 attr;
  58
  59                 if (inode->i_ino == MSDOS_ROOT_INO)
  60                         attr = ATTR_DIR;
  61                 else
  62                         attr = fat_attr(inode);
  63
  64                 return put_user(attr, user_attr);
  65         }
  66         case FAT_IOCTL_SET_ATTRIBUTES:
  67         {
  68                 u32 attr, oldattr;
  69                 int err, is_dir = S_ISDIR(inode->i_mode);
  70                 struct iattr ia;
  71
  72                 err = get_user(attr, user_attr);
  73                 if (err)
  74                         return err;
  75
  76                 down(&inode->i_sem);
  77
  78                 if (IS_RDONLY(inode)) {
  79                         err = -EROFS;
  80                         goto up;
  81                 }
  82
  83                 /*
  84                  * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  85                  * prevents the user from turning us into a VFAT
  86                  * longname entry.  Also, we obviously can't set
  87                  * any of the NTFS attributes in the high 24 bits.
  88                  */
  89                 attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  90                 /* Merge in ATTR_VOLUME and ATTR_DIR */
  91                 attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  92                         (is_dir ? ATTR_DIR : 0);
  93                 oldattr = fat_attr(inode);
  94
  95                 /* Equivalent to a chmod() */
  96                 ia.ia_valid = ATTR_MODE | ATTR_CTIME;
  97                 if (is_dir) {
  98                         ia.ia_mode = MSDOS_MKMODE(attr,
  99                                 S_IRWXUGO & ~sbi->options.fs_dmask)
 100                                 | S_IFDIR;
 101                 } else {
 102                         ia.ia_mode = MSDOS_MKMODE(attr,
 103                                 (S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO))
 104                                 & ~sbi->options.fs_fmask)
 105                                 | S_IFREG;
 106                 }
 107
 108                 /* The root directory has no attributes */
 109                 if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
 110                         err = -EINVAL;
 111                         goto up;
 112                 }
 113
 114                 if (sbi->options.sys_immutable) {
 115                         if ((attr | oldattr) & ATTR_SYS) {
 116                                 if (!capable(CAP_LINUX_IMMUTABLE)) {
 117                                         err = -EPERM;
 118                                         goto up;
 119                                 }
 120                         }
 121                 }
 122
 123                 /* This MUST be done before doing anything irreversible... */
 124                 err = notify_change(filp->f_dentry, &ia);
 125                 if (err)
 126                         goto up;
 127
 128                 if (sbi->options.sys_immutable) {
 129                         if (attr & ATTR_SYS)
 130                                 inode->i_flags |= S_IMMUTABLE;
 131                         else
 132                                 inode->i_flags &= S_IMMUTABLE;
 133                 }
 134
 135                 MSDOS_I(inode)->i_attrs = attr & ATTR_UNUSED;
 136                 mark_inode_dirty(inode);
 137         up:
 138                 up(&inode->i_sem);
 139                 return err;
 140         }
 141         default:
 142                 return -ENOTTY; /* Inappropriate ioctl for device */
 143         }
 144 }
 145
 146 struct file_operations fat_file_operations = {
 147         .llseek         = generic_file_llseek,
 148         .read           = do_sync_read,
 149         .write          = do_sync_write,
 150         .readv          = generic_file_readv,
 151         .writev         = fat_file_writev,
 152         .aio_read       = generic_file_aio_read,
 153         .aio_write      = fat_file_aio_write,
 154         .mmap           = generic_file_mmap,
 155         .ioctl          = fat_generic_ioctl,
 156         .fsync          = file_fsync,
 157         .sendfile       = generic_file_sendfile,
 158 };
 159
 160 int fat_notify_change(struct dentry *dentry, struct iattr *attr)
 161 {
 162         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 163         struct inode *inode = dentry->d_inode;
 164         int mask, error = 0;
 165
 166         lock_kernel();
 167
 168         /* FAT cannot truncate to a longer file */
 169         if (attr->ia_valid & ATTR_SIZE) {
 170                 if (attr->ia_size > inode->i_size) {
 171                         error = -EPERM;
 172                         goto out;
 173                 }
 174         }
 175
 176         error = inode_change_ok(inode, attr);
 177         if (error) {
 178                 if (sbi->options.quiet)
 179                         error = 0;
 180                 goto out;
 181         }
 182         if (((attr->ia_valid & ATTR_UID) &&
 183              (attr->ia_uid != sbi->options.fs_uid)) ||
 184             ((attr->ia_valid & ATTR_GID) &&
 185              (attr->ia_gid != sbi->options.fs_gid)) ||
 186             ((attr->ia_valid & ATTR_MODE) &&
 187              (attr->ia_mode & ~MSDOS_VALID_MODE)))
 188                 error = -EPERM;
 189
 190         if (error) {
 191                 if (sbi->options.quiet)
 192                         error = 0;
 193                 goto out;
 194         }
 195         error = inode_setattr(inode, attr);
 196         if (error)
 197                 goto out;
 198
 199         if (S_ISDIR(inode->i_mode))
 200                 mask = sbi->options.fs_dmask;
 201         else
 202                 mask = sbi->options.fs_fmask;
 203         inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask);
 204 out:
 205         unlock_kernel();
 206         return error;
 207 }
 208
 209 EXPORT_SYMBOL(fat_notify_change);
 210
 211 /* Free all clusters after the skip'th cluster. */
 212 static int fat_free(struct inode *inode, int skip)
 213 {
 214         struct super_block *sb = inode->i_sb;
 215         int err, wait, free_start, i_start, i_logstart;
 216
 217         if (MSDOS_I(inode)->i_start == 0)
 218                 return 0;
 219
 220         /*
 221          * Write a new EOF, and get the remaining cluster chain for freeing.
 222          */
 223         wait = IS_DIRSYNC(inode);
 224         if (skip) {
 225                 struct fat_entry fatent;
 226                 int ret, fclus, dclus;
 227
 228                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 229                 if (ret < 0)
 230                         return ret;
 231                 else if (ret == FAT_ENT_EOF)
 232                         return 0;
 233
 234                 fatent_init(&fatent);
 235                 ret = fat_ent_read(inode, &fatent, dclus);
 236                 if (ret == FAT_ENT_EOF) {
 237                         fatent_brelse(&fatent);
 238                         return 0;
 239                 } else if (ret == FAT_ENT_FREE) {
 240                         fat_fs_panic(sb,
 241                                      "%s: invalid cluster chain (i_pos %lld)",
 242                                      __FUNCTION__, MSDOS_I(inode)->i_pos);
 243                         ret = -EIO;
 244                 } else if (ret > 0) {
 245                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 246                         if (err)
 247                                 ret = err;
 248                 }
 249                 fatent_brelse(&fatent);
 250                 if (ret < 0)
 251                         return ret;
 252
 253                 free_start = ret;
 254                 i_start = i_logstart = 0;
 255                 fat_cache_inval_inode(inode);
 256         } else {
 257                 fat_cache_inval_inode(inode);
 258
 259                 i_start = free_start = MSDOS_I(inode)->i_start;
 260                 i_logstart = MSDOS_I(inode)->i_logstart;
 261                 MSDOS_I(inode)->i_start = 0;
 262                 MSDOS_I(inode)->i_logstart = 0;
 263         }
 264         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 265         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 266         if (wait) {
 267                 err = fat_sync_inode(inode);
 268                 if (err)
 269                         goto error;
 270         } else
 271                 mark_inode_dirty(inode);
 272         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 273
 274         /* Freeing the remained cluster chain */
 275         return fat_free_clusters(inode, free_start);
 276
 277 error:
 278         if (i_start) {
 279                 MSDOS_I(inode)->i_start = i_start;
 280                 MSDOS_I(inode)->i_logstart = i_logstart;
 281         }
 282         return err;
 283 }
 284
 285 void fat_truncate(struct inode *inode)
 286 {
 287         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 288         const unsigned int cluster_size = sbi->cluster_size;
 289         int nr_clusters;
 290
 291         /*
 292          * This protects against truncating a file bigger than it was then
 293          * trying to write into the hole.
 294          */
 295         if (MSDOS_I(inode)->mmu_private > inode->i_size)
 296                 MSDOS_I(inode)->mmu_private = inode->i_size;
 297
 298         nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits;
 299
 300         lock_kernel();
 301         fat_free(inode, nr_clusters);
 302         unlock_kernel();
 303 }
 304
 305 struct inode_operations fat_file_inode_operations = {
 306         .truncate       = fat_truncate,
 307         .setattr        = fat_notify_change,
 308 };