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 .splice_read = generic_file_splice_read,
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 static int check_mode(const struct msdos_sb_info *sbi, mode_t mode)
159 {
160 mode_t req = mode & ~S_IFMT;
161
162 /*
163 * Of the r and x bits, all (subject to umask) must be present. Of the
164 * w bits, either all (subject to umask) or none must be present.
165 */
166
167 if (S_ISREG(mode)) {
168 req &= ~sbi->options.fs_fmask;
169
170 if ((req & (S_IRUGO | S_IXUGO)) !=
171 ((S_IRUGO | S_IXUGO) & ~sbi->options.fs_fmask))
172 return -EPERM;
173
174 if ((req & S_IWUGO) != 0 &&
175 (req & S_IWUGO) != (S_IWUGO & ~sbi->options.fs_fmask))
176 return -EPERM;
177 } else if (S_ISDIR(mode)) {
178 req &= ~sbi->options.fs_dmask;
179
180 if ((req & (S_IRUGO | S_IXUGO)) !=
181 ((S_IRUGO | S_IXUGO) & ~sbi->options.fs_dmask))
182 return -EPERM;
183
184 if ((req & S_IWUGO) != 0 &&
185 (req & S_IWUGO) != (S_IWUGO & ~sbi->options.fs_dmask))
186 return -EPERM;
187 } else {
188 return -EPERM;
189 }
190
191 return 0;
192 }
193
194 int fat_notify_change(struct dentry *dentry, struct iattr *attr)
195 {
196 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
197 struct inode *inode = dentry->d_inode;
198 int mask, error = 0;
199
200 lock_kernel();
201
202 /*
203 * Expand the file. Since inode_setattr() updates ->i_size
204 * before calling the ->truncate(), but FAT needs to fill the
205 * hole before it.
206 */
207 if (attr->ia_valid & ATTR_SIZE) {
208 if (attr->ia_size > inode->i_size) {
209 error = fat_cont_expand(inode, attr->ia_size);
210 if (error || attr->ia_valid == ATTR_SIZE)
211 goto out;
212 attr->ia_valid &= ~ATTR_SIZE;
213 }
214 }
215
216 error = inode_change_ok(inode, attr);
217 if (error) {
218 if (sbi->options.quiet)
219 error = 0;
220 goto out;
221 }
222 if (((attr->ia_valid & ATTR_UID) &&
223 (attr->ia_uid != sbi->options.fs_uid)) ||
224 ((attr->ia_valid & ATTR_GID) &&
225 (attr->ia_gid != sbi->options.fs_gid)))
226 error = -EPERM;
227
228 if (error) {
229 if (sbi->options.quiet)
230 error = 0;
231 goto out;
232 }
233
234 if (attr->ia_valid & ATTR_MODE) {
235 error = check_mode(sbi, attr->ia_mode);
236 if (error != 0 && !sbi->options.quiet)
237 goto out;
238 }
239
240 error = inode_setattr(inode, attr);
241 if (error)
242 goto out;
243
244 if (S_ISDIR(inode->i_mode))
245 mask = sbi->options.fs_dmask;
246 else
247 mask = sbi->options.fs_fmask;
248 inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask);
249 out:
250 unlock_kernel();
251 return error;
252 }
253
254 EXPORT_SYMBOL_GPL(fat_notify_change);
255
256 /* Free all clusters after the skip'th cluster. */
257 static int fat_free(struct inode *inode, int skip)
258 {
259 struct super_block *sb = inode->i_sb;
260 int err, wait, free_start, i_start, i_logstart;
261
262 if (MSDOS_I(inode)->i_start == 0)
263 return 0;
264
265 fat_cache_inval_inode(inode);
266
267 wait = IS_DIRSYNC(inode);
268 i_start = free_start = MSDOS_I(inode)->i_start;
269 i_logstart = MSDOS_I(inode)->i_logstart;
270
271 /* First, we write the new file size. */
272 if (!skip) {
273 MSDOS_I(inode)->i_start = 0;
274 MSDOS_I(inode)->i_logstart = 0;
275 }
276 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
277 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
278 if (wait) {
279 err = fat_sync_inode(inode);
280 if (err) {
281 MSDOS_I(inode)->i_start = i_start;
282 MSDOS_I(inode)->i_logstart = i_logstart;
283 return err;
284 }
285 } else
286 mark_inode_dirty(inode);
287
288 /* Write a new EOF, and get the remaining cluster chain for freeing. */
289 if (skip) {
290 struct fat_entry fatent;
291 int ret, fclus, dclus;
292
293 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
294 if (ret < 0)
295 return ret;
296 else if (ret == FAT_ENT_EOF)
297 return 0;
298
299 fatent_init(&fatent);
300 ret = fat_ent_read(inode, &fatent, dclus);
301 if (ret == FAT_ENT_EOF) {
302 fatent_brelse(&fatent);
303 return 0;
304 } else if (ret == FAT_ENT_FREE) {
305 fat_fs_panic(sb,
306 "%s: invalid cluster chain (i_pos %lld)",
307 __FUNCTION__, MSDOS_I(inode)->i_pos);
308 ret = -EIO;
309 } else if (ret > 0) {
310 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
311 if (err)
312 ret = err;
313 }
314 fatent_brelse(&fatent);
315 if (ret < 0)
316 return ret;
317
318 free_start = ret;
319 }
320 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
321
322 /* Freeing the remained cluster chain */
323 return fat_free_clusters(inode, free_start);
324 }
325
326 void fat_truncate(struct inode *inode)
327 {
328 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
329 const unsigned int cluster_size = sbi->cluster_size;
330 int nr_clusters;
331
332 /*
333 * This protects against truncating a file bigger than it was then
334 * trying to write into the hole.
335 */
336 if (MSDOS_I(inode)->mmu_private > inode->i_size)
337 MSDOS_I(inode)->mmu_private = inode->i_size;
338
339 nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits;
340
341 lock_kernel();
342 fat_free(inode, nr_clusters);
343 unlock_kernel();
344 fat_flush_inodes(inode->i_sb, inode, NULL);
345 }
346
347 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
348 {
349 struct inode *inode = dentry->d_inode;
350 generic_fillattr(inode, stat);
351 stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
352 return 0;
353 }
354 EXPORT_SYMBOL_GPL(fat_getattr);
355
356 const struct inode_operations fat_file_inode_operations = {
357 .truncate = fat_truncate,
358 .setattr = fat_notify_change,
359 .getattr = fat_getattr,
360 };
361
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