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Linux/fs/fat/file.c

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  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/compat.h>
 12 #include <linux/mount.h>
 13 #include <linux/blkdev.h>
 14 #include <linux/backing-dev.h>
 15 #include <linux/fsnotify.h>
 16 #include <linux/security.h>
 17 #include <linux/falloc.h>
 18 #include "fat.h"
 19 
 20 static long fat_fallocate(struct file *file, int mode,
 21                           loff_t offset, loff_t len);
 22 
 23 static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
 24 {
 25         u32 attr;
 26 
 27         inode_lock(inode);
 28         attr = fat_make_attrs(inode);
 29         inode_unlock(inode);
 30 
 31         return put_user(attr, user_attr);
 32 }
 33 
 34 static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
 35 {
 36         struct inode *inode = file_inode(file);
 37         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 38         int is_dir = S_ISDIR(inode->i_mode);
 39         u32 attr, oldattr;
 40         struct iattr ia;
 41         int err;
 42 
 43         err = get_user(attr, user_attr);
 44         if (err)
 45                 goto out;
 46 
 47         err = mnt_want_write_file(file);
 48         if (err)
 49                 goto out;
 50         inode_lock(inode);
 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_make_attrs(inode);
 63 
 64         /* Equivalent to a chmod() */
 65         ia.ia_valid = ATTR_MODE | ATTR_CTIME;
 66         ia.ia_ctime = current_time(inode);
 67         if (is_dir)
 68                 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
 69         else {
 70                 ia.ia_mode = fat_make_mode(sbi, attr,
 71                         S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
 72         }
 73 
 74         /* The root directory has no attributes */
 75         if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
 76                 err = -EINVAL;
 77                 goto out_unlock_inode;
 78         }
 79 
 80         if (sbi->options.sys_immutable &&
 81             ((attr | oldattr) & ATTR_SYS) &&
 82             !capable(CAP_LINUX_IMMUTABLE)) {
 83                 err = -EPERM;
 84                 goto out_unlock_inode;
 85         }
 86 
 87         /*
 88          * The security check is questionable...  We single
 89          * out the RO attribute for checking by the security
 90          * module, just because it maps to a file mode.
 91          */
 92         err = security_inode_setattr(file->f_path.dentry, &ia);
 93         if (err)
 94                 goto out_unlock_inode;
 95 
 96         /* This MUST be done before doing anything irreversible... */
 97         err = fat_setattr(file->f_path.dentry, &ia);
 98         if (err)
 99                 goto out_unlock_inode;
100 
101         fsnotify_change(file->f_path.dentry, ia.ia_valid);
102         if (sbi->options.sys_immutable) {
103                 if (attr & ATTR_SYS)
104                         inode->i_flags |= S_IMMUTABLE;
105                 else
106                         inode->i_flags &= ~S_IMMUTABLE;
107         }
108 
109         fat_save_attrs(inode, attr);
110         mark_inode_dirty(inode);
111 out_unlock_inode:
112         inode_unlock(inode);
113         mnt_drop_write_file(file);
114 out:
115         return err;
116 }
117 
118 static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
119 {
120         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
121         return put_user(sbi->vol_id, user_attr);
122 }
123 
124 static int fat_ioctl_fitrim(struct inode *inode, unsigned long arg)
125 {
126         struct super_block *sb = inode->i_sb;
127         struct fstrim_range __user *user_range;
128         struct fstrim_range range;
129         struct request_queue *q = bdev_get_queue(sb->s_bdev);
130         int err;
131 
132         if (!capable(CAP_SYS_ADMIN))
133                 return -EPERM;
134 
135         if (!blk_queue_discard(q))
136                 return -EOPNOTSUPP;
137 
138         user_range = (struct fstrim_range __user *)arg;
139         if (copy_from_user(&range, user_range, sizeof(range)))
140                 return -EFAULT;
141 
142         range.minlen = max_t(unsigned int, range.minlen,
143                              q->limits.discard_granularity);
144 
145         err = fat_trim_fs(inode, &range);
146         if (err < 0)
147                 return err;
148 
149         if (copy_to_user(user_range, &range, sizeof(range)))
150                 return -EFAULT;
151 
152         return 0;
153 }
154 
155 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
156 {
157         struct inode *inode = file_inode(filp);
158         u32 __user *user_attr = (u32 __user *)arg;
159 
160         switch (cmd) {
161         case FAT_IOCTL_GET_ATTRIBUTES:
162                 return fat_ioctl_get_attributes(inode, user_attr);
163         case FAT_IOCTL_SET_ATTRIBUTES:
164                 return fat_ioctl_set_attributes(filp, user_attr);
165         case FAT_IOCTL_GET_VOLUME_ID:
166                 return fat_ioctl_get_volume_id(inode, user_attr);
167         case FITRIM:
168                 return fat_ioctl_fitrim(inode, arg);
169         default:
170                 return -ENOTTY; /* Inappropriate ioctl for device */
171         }
172 }
173 
174 #ifdef CONFIG_COMPAT
175 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
176                                       unsigned long arg)
177 
178 {
179         return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
180 }
181 #endif
182 
183 static int fat_file_release(struct inode *inode, struct file *filp)
184 {
185         if ((filp->f_mode & FMODE_WRITE) &&
186              MSDOS_SB(inode->i_sb)->options.flush) {
187                 fat_flush_inodes(inode->i_sb, inode, NULL);
188                 congestion_wait(BLK_RW_ASYNC, HZ/10);
189         }
190         return 0;
191 }
192 
193 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
194 {
195         struct inode *inode = filp->f_mapping->host;
196         int res, err;
197 
198         res = generic_file_fsync(filp, start, end, datasync);
199         err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
200 
201         return res ? res : err;
202 }
203 
204 
205 const struct file_operations fat_file_operations = {
206         .llseek         = generic_file_llseek,
207         .read_iter      = generic_file_read_iter,
208         .write_iter     = generic_file_write_iter,
209         .mmap           = generic_file_mmap,
210         .release        = fat_file_release,
211         .unlocked_ioctl = fat_generic_ioctl,
212 #ifdef CONFIG_COMPAT
213         .compat_ioctl   = fat_generic_compat_ioctl,
214 #endif
215         .fsync          = fat_file_fsync,
216         .splice_read    = generic_file_splice_read,
217         .fallocate      = fat_fallocate,
218 };
219 
220 static int fat_cont_expand(struct inode *inode, loff_t size)
221 {
222         struct address_space *mapping = inode->i_mapping;
223         loff_t start = inode->i_size, count = size - inode->i_size;
224         int err;
225 
226         err = generic_cont_expand_simple(inode, size);
227         if (err)
228                 goto out;
229 
230         fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
231         mark_inode_dirty(inode);
232         if (IS_SYNC(inode)) {
233                 int err2;
234 
235                 /*
236                  * Opencode syncing since we don't have a file open to use
237                  * standard fsync path.
238                  */
239                 err = filemap_fdatawrite_range(mapping, start,
240                                                start + count - 1);
241                 err2 = sync_mapping_buffers(mapping);
242                 if (!err)
243                         err = err2;
244                 err2 = write_inode_now(inode, 1);
245                 if (!err)
246                         err = err2;
247                 if (!err) {
248                         err =  filemap_fdatawait_range(mapping, start,
249                                                        start + count - 1);
250                 }
251         }
252 out:
253         return err;
254 }
255 
256 /*
257  * Preallocate space for a file. This implements fat's fallocate file
258  * operation, which gets called from sys_fallocate system call. User
259  * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set
260  * we just allocate clusters without zeroing them out. Otherwise we
261  * allocate and zero out clusters via an expanding truncate.
262  */
263 static long fat_fallocate(struct file *file, int mode,
264                           loff_t offset, loff_t len)
265 {
266         int nr_cluster; /* Number of clusters to be allocated */
267         loff_t mm_bytes; /* Number of bytes to be allocated for file */
268         loff_t ondisksize; /* block aligned on-disk size in bytes*/
269         struct inode *inode = file->f_mapping->host;
270         struct super_block *sb = inode->i_sb;
271         struct msdos_sb_info *sbi = MSDOS_SB(sb);
272         int err = 0;
273 
274         /* No support for hole punch or other fallocate flags. */
275         if (mode & ~FALLOC_FL_KEEP_SIZE)
276                 return -EOPNOTSUPP;
277 
278         /* No support for dir */
279         if (!S_ISREG(inode->i_mode))
280                 return -EOPNOTSUPP;
281 
282         inode_lock(inode);
283         if (mode & FALLOC_FL_KEEP_SIZE) {
284                 ondisksize = inode->i_blocks << 9;
285                 if ((offset + len) <= ondisksize)
286                         goto error;
287 
288                 /* First compute the number of clusters to be allocated */
289                 mm_bytes = offset + len - ondisksize;
290                 nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >>
291                         sbi->cluster_bits;
292 
293                 /* Start the allocation.We are not zeroing out the clusters */
294                 while (nr_cluster-- > 0) {
295                         err = fat_add_cluster(inode);
296                         if (err)
297                                 goto error;
298                 }
299         } else {
300                 if ((offset + len) <= i_size_read(inode))
301                         goto error;
302 
303                 /* This is just an expanding truncate */
304                 err = fat_cont_expand(inode, (offset + len));
305         }
306 
307 error:
308         inode_unlock(inode);
309         return err;
310 }
311 
312 /* Free all clusters after the skip'th cluster. */
313 static int fat_free(struct inode *inode, int skip)
314 {
315         struct super_block *sb = inode->i_sb;
316         int err, wait, free_start, i_start, i_logstart;
317 
318         if (MSDOS_I(inode)->i_start == 0)
319                 return 0;
320 
321         fat_cache_inval_inode(inode);
322 
323         wait = IS_DIRSYNC(inode);
324         i_start = free_start = MSDOS_I(inode)->i_start;
325         i_logstart = MSDOS_I(inode)->i_logstart;
326 
327         /* First, we write the new file size. */
328         if (!skip) {
329                 MSDOS_I(inode)->i_start = 0;
330                 MSDOS_I(inode)->i_logstart = 0;
331         }
332         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
333         fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
334         if (wait) {
335                 err = fat_sync_inode(inode);
336                 if (err) {
337                         MSDOS_I(inode)->i_start = i_start;
338                         MSDOS_I(inode)->i_logstart = i_logstart;
339                         return err;
340                 }
341         } else
342                 mark_inode_dirty(inode);
343 
344         /* Write a new EOF, and get the remaining cluster chain for freeing. */
345         if (skip) {
346                 struct fat_entry fatent;
347                 int ret, fclus, dclus;
348 
349                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
350                 if (ret < 0)
351                         return ret;
352                 else if (ret == FAT_ENT_EOF)
353                         return 0;
354 
355                 fatent_init(&fatent);
356                 ret = fat_ent_read(inode, &fatent, dclus);
357                 if (ret == FAT_ENT_EOF) {
358                         fatent_brelse(&fatent);
359                         return 0;
360                 } else if (ret == FAT_ENT_FREE) {
361                         fat_fs_error(sb,
362                                      "%s: invalid cluster chain (i_pos %lld)",
363                                      __func__, MSDOS_I(inode)->i_pos);
364                         ret = -EIO;
365                 } else if (ret > 0) {
366                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
367                         if (err)
368                                 ret = err;
369                 }
370                 fatent_brelse(&fatent);
371                 if (ret < 0)
372                         return ret;
373 
374                 free_start = ret;
375         }
376         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
377 
378         /* Freeing the remained cluster chain */
379         return fat_free_clusters(inode, free_start);
380 }
381 
382 void fat_truncate_blocks(struct inode *inode, loff_t offset)
383 {
384         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
385         const unsigned int cluster_size = sbi->cluster_size;
386         int nr_clusters;
387 
388         /*
389          * This protects against truncating a file bigger than it was then
390          * trying to write into the hole.
391          */
392         if (MSDOS_I(inode)->mmu_private > offset)
393                 MSDOS_I(inode)->mmu_private = offset;
394 
395         nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
396 
397         fat_free(inode, nr_clusters);
398         fat_flush_inodes(inode->i_sb, inode, NULL);
399 }
400 
401 int fat_getattr(const struct path *path, struct kstat *stat,
402                 u32 request_mask, unsigned int flags)
403 {
404         struct inode *inode = d_inode(path->dentry);
405         generic_fillattr(inode, stat);
406         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
407 
408         if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
409                 /* Use i_pos for ino. This is used as fileid of nfs. */
410                 stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
411         }
412         return 0;
413 }
414 EXPORT_SYMBOL_GPL(fat_getattr);
415 
416 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
417                              struct inode *inode, umode_t *mode_ptr)
418 {
419         umode_t mask, perm;
420 
421         /*
422          * Note, the basic check is already done by a caller of
423          * (attr->ia_mode & ~FAT_VALID_MODE)
424          */
425 
426         if (S_ISREG(inode->i_mode))
427                 mask = sbi->options.fs_fmask;
428         else
429                 mask = sbi->options.fs_dmask;
430 
431         perm = *mode_ptr & ~(S_IFMT | mask);
432 
433         /*
434          * Of the r and x bits, all (subject to umask) must be present. Of the
435          * w bits, either all (subject to umask) or none must be present.
436          *
437          * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
438          */
439         if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
440                 return -EPERM;
441         if (fat_mode_can_hold_ro(inode)) {
442                 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
443                         return -EPERM;
444         } else {
445                 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
446                         return -EPERM;
447         }
448 
449         *mode_ptr &= S_IFMT | perm;
450 
451         return 0;
452 }
453 
454 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
455 {
456         umode_t allow_utime = sbi->options.allow_utime;
457 
458         if (!uid_eq(current_fsuid(), inode->i_uid)) {
459                 if (in_group_p(inode->i_gid))
460                         allow_utime >>= 3;
461                 if (allow_utime & MAY_WRITE)
462                         return 1;
463         }
464 
465         /* use a default check */
466         return 0;
467 }
468 
469 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
470 /* valid file mode bits */
471 #define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
472 
473 int fat_setattr(struct dentry *dentry, struct iattr *attr)
474 {
475         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
476         struct inode *inode = d_inode(dentry);
477         unsigned int ia_valid;
478         int error;
479 
480         /* Check for setting the inode time. */
481         ia_valid = attr->ia_valid;
482         if (ia_valid & TIMES_SET_FLAGS) {
483                 if (fat_allow_set_time(sbi, inode))
484                         attr->ia_valid &= ~TIMES_SET_FLAGS;
485         }
486 
487         error = setattr_prepare(dentry, attr);
488         attr->ia_valid = ia_valid;
489         if (error) {
490                 if (sbi->options.quiet)
491                         error = 0;
492                 goto out;
493         }
494 
495         /*
496          * Expand the file. Since inode_setattr() updates ->i_size
497          * before calling the ->truncate(), but FAT needs to fill the
498          * hole before it. XXX: this is no longer true with new truncate
499          * sequence.
500          */
501         if (attr->ia_valid & ATTR_SIZE) {
502                 inode_dio_wait(inode);
503 
504                 if (attr->ia_size > inode->i_size) {
505                         error = fat_cont_expand(inode, attr->ia_size);
506                         if (error || attr->ia_valid == ATTR_SIZE)
507                                 goto out;
508                         attr->ia_valid &= ~ATTR_SIZE;
509                 }
510         }
511 
512         if (((attr->ia_valid & ATTR_UID) &&
513              (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
514             ((attr->ia_valid & ATTR_GID) &&
515              (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
516             ((attr->ia_valid & ATTR_MODE) &&
517              (attr->ia_mode & ~FAT_VALID_MODE)))
518                 error = -EPERM;
519 
520         if (error) {
521                 if (sbi->options.quiet)
522                         error = 0;
523                 goto out;
524         }
525 
526         /*
527          * We don't return -EPERM here. Yes, strange, but this is too
528          * old behavior.
529          */
530         if (attr->ia_valid & ATTR_MODE) {
531                 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
532                         attr->ia_valid &= ~ATTR_MODE;
533         }
534 
535         if (attr->ia_valid & ATTR_SIZE) {
536                 error = fat_block_truncate_page(inode, attr->ia_size);
537                 if (error)
538                         goto out;
539                 down_write(&MSDOS_I(inode)->truncate_lock);
540                 truncate_setsize(inode, attr->ia_size);
541                 fat_truncate_blocks(inode, attr->ia_size);
542                 up_write(&MSDOS_I(inode)->truncate_lock);
543         }
544 
545         /*
546          * setattr_copy can't truncate these appropriately, so we'll
547          * copy them ourselves
548          */
549         if (attr->ia_valid & ATTR_ATIME)
550                 fat_truncate_time(inode, &attr->ia_atime, S_ATIME);
551         if (attr->ia_valid & ATTR_CTIME)
552                 fat_truncate_time(inode, &attr->ia_ctime, S_CTIME);
553         if (attr->ia_valid & ATTR_MTIME)
554                 fat_truncate_time(inode, &attr->ia_mtime, S_MTIME);
555         attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
556 
557         setattr_copy(inode, attr);
558         mark_inode_dirty(inode);
559 out:
560         return error;
561 }
562 EXPORT_SYMBOL_GPL(fat_setattr);
563 
564 const struct inode_operations fat_file_inode_operations = {
565         .setattr        = fat_setattr,
566         .getattr        = fat_getattr,
567         .update_time    = fat_update_time,
568 };
569 

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