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 }; 298