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         .sendfile       = generic_file_sendfile,
 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 int fat_notify_change(struct dentry *dentry, struct iattr *attr)
 159 {
 160         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 161         struct inode *inode = dentry->d_inode;
 162         int mask, error = 0;
 163
 164         lock_kernel();
 165
 166         /*
 167          * Expand the file. Since inode_setattr() updates ->i_size
 168          * before calling the ->truncate(), but FAT needs to fill the
 169          * hole before it.
 170          */
 171         if (attr->ia_valid & ATTR_SIZE) {
 172                 if (attr->ia_size > inode->i_size) {
 173                         error = fat_cont_expand(inode, attr->ia_size);
 174                         if (error || attr->ia_valid == ATTR_SIZE)
 175                                 goto out;
 176                         attr->ia_valid &= ~ATTR_SIZE;
 177                 }
 178         }
 179
 180         error = inode_change_ok(inode, attr);
 181         if (error) {
 182                 if (sbi->options.quiet)
 183                         error = 0;
 184                 goto out;
 185         }
 186         if (((attr->ia_valid & ATTR_UID) &&
 187              (attr->ia_uid != sbi->options.fs_uid)) ||
 188             ((attr->ia_valid & ATTR_GID) &&
 189              (attr->ia_gid != sbi->options.fs_gid)) ||
 190             ((attr->ia_valid & ATTR_MODE) &&
 191              (attr->ia_mode & ~MSDOS_VALID_MODE)))
 192                 error = -EPERM;
 193
 194         if (error) {
 195                 if (sbi->options.quiet)
 196                         error = 0;
 197                 goto out;
 198         }
 199         error = inode_setattr(inode, attr);
 200         if (error)
 201                 goto out;
 202
 203         if (S_ISDIR(inode->i_mode))
 204                 mask = sbi->options.fs_dmask;
 205         else
 206                 mask = sbi->options.fs_fmask;
 207         inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask);
 208 out:
 209         unlock_kernel();
 210         return error;
 211 }
 212
 213 EXPORT_SYMBOL_GPL(fat_notify_change);
 214
 215 /* Free all clusters after the skip'th cluster. */
 216 static int fat_free(struct inode *inode, int skip)
 217 {
 218         struct super_block *sb = inode->i_sb;
 219         int err, wait, free_start, i_start, i_logstart;
 220
 221         if (MSDOS_I(inode)->i_start == 0)
 222                 return 0;
 223
 224         fat_cache_inval_inode(inode);
 225
 226         wait = IS_DIRSYNC(inode);
 227         i_start = free_start = MSDOS_I(inode)->i_start;
 228         i_logstart = MSDOS_I(inode)->i_logstart;
 229
 230         /* First, we write the new file size. */
 231         if (!skip) {
 232                 MSDOS_I(inode)->i_start = 0;
 233                 MSDOS_I(inode)->i_logstart = 0;
 234         }
 235         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 236         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 237         if (wait) {
 238                 err = fat_sync_inode(inode);
 239                 if (err) {
 240                         MSDOS_I(inode)->i_start = i_start;
 241                         MSDOS_I(inode)->i_logstart = i_logstart;
 242                         return err;
 243                 }
 244         } else
 245                 mark_inode_dirty(inode);
 246
 247         /* Write a new EOF, and get the remaining cluster chain for freeing. */
 248         if (skip) {
 249                 struct fat_entry fatent;
 250                 int ret, fclus, dclus;
 251
 252                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 253                 if (ret < 0)
 254                         return ret;
 255                 else if (ret == FAT_ENT_EOF)
 256                         return 0;
 257
 258                 fatent_init(&fatent);
 259                 ret = fat_ent_read(inode, &fatent, dclus);
 260                 if (ret == FAT_ENT_EOF) {
 261                         fatent_brelse(&fatent);
 262                         return 0;
 263                 } else if (ret == FAT_ENT_FREE) {
 264                         fat_fs_panic(sb,
 265                                      "%s: invalid cluster chain (i_pos %lld)",
 266                                      __FUNCTION__, MSDOS_I(inode)->i_pos);
 267                         ret = -EIO;
 268                 } else if (ret > 0) {
 269                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 270                         if (err)
 271                                 ret = err;
 272                 }
 273                 fatent_brelse(&fatent);
 274                 if (ret < 0)
 275                         return ret;
 276
 277                 free_start = ret;
 278         }
 279         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 280
 281         /* Freeing the remained cluster chain */
 282         return fat_free_clusters(inode, free_start);
 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         fat_flush_inodes(inode->i_sb, inode, NULL);
 304 }
 305
 306 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 307 {
 308         struct inode *inode = dentry->d_inode;
 309         generic_fillattr(inode, stat);
 310         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 311         return 0;
 312 }
 313 EXPORT_SYMBOL_GPL(fat_getattr);
 314
 315 const struct inode_operations fat_file_inode_operations = {
 316         .truncate       = fat_truncate,
 317         .setattr        = fat_notify_change,
 318         .getattr        = fat_getattr,
 319 };