1
// SPDX-License-Identifier: GPL-2.0-or-later
2
/*
3
 * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
4
 */
5

6
#include <linux/slab.h>
7
#include <linux/compat.h>
8
#include <linux/cred.h>
9
#include <linux/buffer_head.h>
10
#include <linux/blkdev.h>
11
#include <linux/fsnotify.h>
12
#include <linux/security.h>
13
#include <linux/msdos_fs.h>
14
#include <linux/writeback.h>
15

16
#include "exfat_raw.h"
17
#include "exfat_fs.h"
18

19
static int exfat_cont_expand(struct inode *inode, loff_t size)
20
{
21
	int ret;
22
	unsigned int num_clusters, new_num_clusters, last_clu;
23
	struct exfat_inode_info *ei = EXFAT_I(inode);
24
	struct super_block *sb = inode->i_sb;
25
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
26
	struct exfat_chain clu;
27

28
	ret = inode_newsize_ok(inode, size);
29
	if (ret)
30
		return ret;
31

32
	num_clusters = EXFAT_B_TO_CLU(exfat_ondisk_size(inode), sbi);
33
	new_num_clusters = EXFAT_B_TO_CLU_ROUND_UP(size, sbi);
34

35
	if (new_num_clusters == num_clusters)
36
		goto out;
37

38
	if (num_clusters) {
39
		exfat_chain_set(&clu, ei->start_clu, num_clusters, ei->flags);
40
		ret = exfat_find_last_cluster(sb, &clu, &last_clu);
41
		if (ret)
42
			return ret;
43

44
		clu.dir = last_clu + 1;
45
	} else {
46
		last_clu = EXFAT_EOF_CLUSTER;
47
		clu.dir = EXFAT_EOF_CLUSTER;
48
	}
49

50
	clu.size = 0;
51
	clu.flags = ei->flags;
52

53
	ret = exfat_alloc_cluster(inode, new_num_clusters - num_clusters,
54
			&clu, inode_needs_sync(inode));
55
	if (ret)
56
		return ret;
57

58
	/* Append new clusters to chain */
59
	if (num_clusters) {
60
		if (clu.flags != ei->flags)
61
			if (exfat_chain_cont_cluster(sb, ei->start_clu, num_clusters))
62
				goto free_clu;
63

64
		if (clu.flags == ALLOC_FAT_CHAIN)
65
			if (exfat_ent_set(sb, last_clu, clu.dir))
66
				goto free_clu;
67
	} else
68
		ei->start_clu = clu.dir;
69

70
	ei->flags = clu.flags;
71

72
out:
73
	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
74
	/* Expanded range not zeroed, do not update valid_size */
75
	i_size_write(inode, size);
76

77
	inode->i_blocks = round_up(size, sbi->cluster_size) >> 9;
78
	mark_inode_dirty(inode);
79

80
	if (IS_SYNC(inode))
81
		return write_inode_now(inode, 1);
82

83
	return 0;
84

85
free_clu:
86
	exfat_free_cluster(inode, &clu);
87
	return -EIO;
88
}
89

90
static bool exfat_allow_set_time(struct mnt_idmap *idmap,
91
				 struct exfat_sb_info *sbi, struct inode *inode)
92
{
93
	mode_t allow_utime = sbi->options.allow_utime;
94

95
	if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
96
			    current_fsuid())) {
97
		if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)))
98
			allow_utime >>= 3;
99
		if (allow_utime & MAY_WRITE)
100
			return true;
101
	}
102

103
	/* use a default check */
104
	return false;
105
}
106

107
static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,
108
		struct inode *inode, umode_t *mode_ptr)
109
{
110
	mode_t i_mode, mask, perm;
111

112
	i_mode = inode->i_mode;
113

114
	mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?
115
		sbi->options.fs_fmask : sbi->options.fs_dmask;
116
	perm = *mode_ptr & ~(S_IFMT | mask);
117

118
	/* Of the r and x bits, all (subject to umask) must be present.*/
119
	if ((perm & 0555) != (i_mode & 0555))
120
		return -EPERM;
121

122
	if (exfat_mode_can_hold_ro(inode)) {
123
		/*
124
		 * Of the w bits, either all (subject to umask) or none must
125
		 * be present.
126
		 */
127
		if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))
128
			return -EPERM;
129
	} else {
130
		/*
131
		 * If exfat_mode_can_hold_ro(inode) is false, can't change
132
		 * w bits.
133
		 */
134
		if ((perm & 0222) != (0222 & ~mask))
135
			return -EPERM;
136
	}
137

138
	*mode_ptr &= S_IFMT | perm;
139

140
	return 0;
141
}
142

143
/* resize the file length */
144
int __exfat_truncate(struct inode *inode)
145
{
146
	unsigned int num_clusters_new, num_clusters_phys;
147
	unsigned int last_clu = EXFAT_FREE_CLUSTER;
148
	struct exfat_chain clu;
149
	struct super_block *sb = inode->i_sb;
150
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
151
	struct exfat_inode_info *ei = EXFAT_I(inode);
152

153
	/* check if the given file ID is opened */
154
	if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)
155
		return -EPERM;
156

157
	exfat_set_volume_dirty(sb);
158

159
	num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);
160
	num_clusters_phys = EXFAT_B_TO_CLU(exfat_ondisk_size(inode), sbi);
161

162
	exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);
163

164
	if (i_size_read(inode) > 0) {
165
		/*
166
		 * Truncate FAT chain num_clusters after the first cluster
167
		 * num_clusters = min(new, phys);
168
		 */
169
		unsigned int num_clusters =
170
			min(num_clusters_new, num_clusters_phys);
171

172
		/*
173
		 * Follow FAT chain
174
		 * (defensive coding - works fine even with corrupted FAT table
175
		 */
176
		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
177
			clu.dir += num_clusters;
178
			clu.size -= num_clusters;
179
		} else {
180
			while (num_clusters > 0) {
181
				last_clu = clu.dir;
182
				if (exfat_get_next_cluster(sb, &(clu.dir)))
183
					return -EIO;
184

185
				num_clusters--;
186
				clu.size--;
187
			}
188
		}
189
	} else {
190
		ei->flags = ALLOC_NO_FAT_CHAIN;
191
		ei->start_clu = EXFAT_EOF_CLUSTER;
192
	}
193

194
	if (i_size_read(inode) < ei->valid_size)
195
		ei->valid_size = i_size_read(inode);
196

197
	if (ei->type == TYPE_FILE)
198
		ei->attr |= EXFAT_ATTR_ARCHIVE;
199

200
	/*
201
	 * update the directory entry
202
	 *
203
	 * If the directory entry is updated by mark_inode_dirty(), the
204
	 * directory entry will be written after a writeback cycle of
205
	 * updating the bitmap/FAT, which may result in clusters being
206
	 * freed but referenced by the directory entry in the event of a
207
	 * sudden power failure.
208
	 * __exfat_write_inode() is called for directory entry, bitmap
209
	 * and FAT to be written in a same writeback.
210
	 */
211
	if (__exfat_write_inode(inode, inode_needs_sync(inode)))
212
		return -EIO;
213

214
	/* cut off from the FAT chain */
215
	if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
216
			last_clu != EXFAT_EOF_CLUSTER) {
217
		if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
218
			return -EIO;
219
	}
220

221
	/* invalidate cache and free the clusters */
222
	/* clear exfat cache */
223
	exfat_cache_inval_inode(inode);
224

225
	/* hint information */
226
	ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
227
	ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;
228

229
	/* hint_stat will be used if this is directory. */
230
	ei->hint_stat.eidx = 0;
231
	ei->hint_stat.clu = ei->start_clu;
232
	ei->hint_femp.eidx = EXFAT_HINT_NONE;
233

234
	/* free the clusters */
235
	if (exfat_free_cluster(inode, &clu))
236
		return -EIO;
237

238
	return 0;
239
}
240

241
void exfat_truncate(struct inode *inode)
242
{
243
	struct super_block *sb = inode->i_sb;
244
	struct exfat_sb_info *sbi = EXFAT_SB(sb);
245
	struct exfat_inode_info *ei = EXFAT_I(inode);
246
	int err;
247

248
	mutex_lock(&sbi->s_lock);
249
	if (ei->start_clu == 0) {
250
		/*
251
		 * Empty start_clu != ~0 (not allocated)
252
		 */
253
		exfat_fs_error(sb, "tried to truncate zeroed cluster.");
254
		goto write_size;
255
	}
256

257
	err = __exfat_truncate(inode);
258
	if (err)
259
		goto write_size;
260

261
	inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >> 9;
262
write_size:
263
	mutex_unlock(&sbi->s_lock);
264
}
265

266
int exfat_getattr(struct mnt_idmap *idmap, const struct path *path,
267
		  struct kstat *stat, unsigned int request_mask,
268
		  unsigned int query_flags)
269
{
270
	struct inode *inode = d_backing_inode(path->dentry);
271
	struct exfat_inode_info *ei = EXFAT_I(inode);
272

273
	generic_fillattr(idmap, request_mask, inode, stat);
274
	exfat_truncate_atime(&stat->atime);
275
	stat->result_mask |= STATX_BTIME;
276
	stat->btime.tv_sec = ei->i_crtime.tv_sec;
277
	stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
278
	stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
279
	return 0;
280
}
281

282
int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
283
		  struct iattr *attr)
284
{
285
	struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
286
	struct inode *inode = dentry->d_inode;
287
	unsigned int ia_valid;
288
	int error;
289

290
	if (unlikely(exfat_forced_shutdown(inode->i_sb)))
291
		return -EIO;
292

293
	if ((attr->ia_valid & ATTR_SIZE) &&
294
	    attr->ia_size > i_size_read(inode)) {
295
		error = exfat_cont_expand(inode, attr->ia_size);
296
		if (error || attr->ia_valid == ATTR_SIZE)
297
			return error;
298
		attr->ia_valid &= ~ATTR_SIZE;
299
	}
300

301
	/* Check for setting the inode time. */
302
	ia_valid = attr->ia_valid;
303
	if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
304
	    exfat_allow_set_time(idmap, sbi, inode)) {
305
		attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
306
				ATTR_TIMES_SET);
307
	}
308

309
	error = setattr_prepare(idmap, dentry, attr);
310
	attr->ia_valid = ia_valid;
311
	if (error)
312
		goto out;
313

314
	if (((attr->ia_valid & ATTR_UID) &&
315
	      (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),
316
	       sbi->options.fs_uid))) ||
317
	    ((attr->ia_valid & ATTR_GID) &&
318
	      (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),
319
	       sbi->options.fs_gid))) ||
320
	    ((attr->ia_valid & ATTR_MODE) &&
321
	     (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {
322
		error = -EPERM;
323
		goto out;
324
	}
325

326
	/*
327
	 * We don't return -EPERM here. Yes, strange, but this is too
328
	 * old behavior.
329
	 */
330
	if (attr->ia_valid & ATTR_MODE) {
331
		if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
332
			attr->ia_valid &= ~ATTR_MODE;
333
	}
334

335
	if (attr->ia_valid & ATTR_SIZE)
336
		inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
337

338
	setattr_copy(idmap, inode, attr);
339
	exfat_truncate_inode_atime(inode);
340

341
	if (attr->ia_valid & ATTR_SIZE) {
342
		error = exfat_block_truncate_page(inode, attr->ia_size);
343
		if (error)
344
			goto out;
345

346
		down_write(&EXFAT_I(inode)->truncate_lock);
347
		truncate_setsize(inode, attr->ia_size);
348

349
		/*
350
		 * __exfat_write_inode() is called from exfat_truncate(), inode
351
		 * is already written by it, so mark_inode_dirty() is unneeded.
352
		 */
353
		exfat_truncate(inode);
354
		up_write(&EXFAT_I(inode)->truncate_lock);
355
	} else
356
		mark_inode_dirty(inode);
357

358
out:
359
	return error;
360
}
361

362
/*
363
 * modified ioctls from fat/file.c by Welmer Almesberger
364
 */
365
static int exfat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
366
{
367
	u32 attr;
368

369
	inode_lock_shared(inode);
370
	attr = exfat_make_attr(inode);
371
	inode_unlock_shared(inode);
372

373
	return put_user(attr, user_attr);
374
}
375

376
static int exfat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
377
{
378
	struct inode *inode = file_inode(file);
379
	struct exfat_sb_info *sbi = EXFAT_SB(inode->i_sb);
380
	int is_dir = S_ISDIR(inode->i_mode);
381
	u32 attr, oldattr;
382
	struct iattr ia;
383
	int err;
384

385
	err = get_user(attr, user_attr);
386
	if (err)
387
		goto out;
388

389
	err = mnt_want_write_file(file);
390
	if (err)
391
		goto out;
392
	inode_lock(inode);
393

394
	oldattr = exfat_make_attr(inode);
395

396
	/*
397
	 * Mask attributes so we don't set reserved fields.
398
	 */
399
	attr &= (EXFAT_ATTR_READONLY | EXFAT_ATTR_HIDDEN | EXFAT_ATTR_SYSTEM |
400
		 EXFAT_ATTR_ARCHIVE);
401
	attr |= (is_dir ? EXFAT_ATTR_SUBDIR : 0);
402

403
	/* Equivalent to a chmod() */
404
	ia.ia_valid = ATTR_MODE | ATTR_CTIME;
405
	ia.ia_ctime = current_time(inode);
406
	if (is_dir)
407
		ia.ia_mode = exfat_make_mode(sbi, attr, 0777);
408
	else
409
		ia.ia_mode = exfat_make_mode(sbi, attr, 0666 | (inode->i_mode & 0111));
410

411
	/* The root directory has no attributes */
412
	if (inode->i_ino == EXFAT_ROOT_INO && attr != EXFAT_ATTR_SUBDIR) {
413
		err = -EINVAL;
414
		goto out_unlock_inode;
415
	}
416

417
	if (((attr | oldattr) & EXFAT_ATTR_SYSTEM) &&
418
	    !capable(CAP_LINUX_IMMUTABLE)) {
419
		err = -EPERM;
420
		goto out_unlock_inode;
421
	}
422

423
	/*
424
	 * The security check is questionable...  We single
425
	 * out the RO attribute for checking by the security
426
	 * module, just because it maps to a file mode.
427
	 */
428
	err = security_inode_setattr(file_mnt_idmap(file),
429
				     file->f_path.dentry, &ia);
430
	if (err)
431
		goto out_unlock_inode;
432

433
	/* This MUST be done before doing anything irreversible... */
434
	err = exfat_setattr(file_mnt_idmap(file), file->f_path.dentry, &ia);
435
	if (err)
436
		goto out_unlock_inode;
437

438
	fsnotify_change(file->f_path.dentry, ia.ia_valid);
439

440
	exfat_save_attr(inode, attr);
441
	mark_inode_dirty(inode);
442
out_unlock_inode:
443
	inode_unlock(inode);
444
	mnt_drop_write_file(file);
445
out:
446
	return err;
447
}
448

449
static int exfat_ioctl_fitrim(struct inode *inode, unsigned long arg)
450
{
451
	struct fstrim_range range;
452
	int ret = 0;
453

454
	if (!capable(CAP_SYS_ADMIN))
455
		return -EPERM;
456

457
	if (!bdev_max_discard_sectors(inode->i_sb->s_bdev))
458
		return -EOPNOTSUPP;
459

460
	if (copy_from_user(&range, (struct fstrim_range __user *)arg, sizeof(range)))
461
		return -EFAULT;
462

463
	range.minlen = max_t(unsigned int, range.minlen,
464
				bdev_discard_granularity(inode->i_sb->s_bdev));
465

466
	ret = exfat_trim_fs(inode, &range);
467
	if (ret < 0)
468
		return ret;
469

470
	if (copy_to_user((struct fstrim_range __user *)arg, &range, sizeof(range)))
471
		return -EFAULT;
472

473
	return 0;
474
}
475

476
static int exfat_ioctl_shutdown(struct super_block *sb, unsigned long arg)
477
{
478
	u32 flags;
479

480
	if (!capable(CAP_SYS_ADMIN))
481
		return -EPERM;
482

483
	if (get_user(flags, (__u32 __user *)arg))
484
		return -EFAULT;
485

486
	return exfat_force_shutdown(sb, flags);
487
}
488

489
static int exfat_ioctl_get_volume_label(struct super_block *sb, unsigned long arg)
490
{
491
	int ret;
492
	char label[FSLABEL_MAX] = {0};
493
	struct exfat_uni_name uniname;
494

495
	ret = exfat_read_volume_label(sb, &uniname);
496
	if (ret < 0)
497
		return ret;
498

499
	ret = exfat_utf16_to_nls(sb, &uniname, label, uniname.name_len);
500
	if (ret < 0)
501
		return ret;
502

503
	if (copy_to_user((char __user *)arg, label, ret + 1))
504
		return -EFAULT;
505

506
	return 0;
507
}
508

509
static int exfat_ioctl_set_volume_label(struct super_block *sb,
510
					unsigned long arg)
511
{
512
	int ret = 0, lossy;
513
	char label[FSLABEL_MAX];
514
	struct exfat_uni_name uniname;
515

516
	if (!capable(CAP_SYS_ADMIN))
517
		return -EPERM;
518

519
	if (copy_from_user(label, (char __user *)arg, FSLABEL_MAX))
520
		return -EFAULT;
521

522
	memset(&uniname, 0, sizeof(uniname));
523
	if (label[0]) {
524
		ret = exfat_nls_to_utf16(sb, label, FSLABEL_MAX,
525
					 &uniname, &lossy);
526
		if (ret < 0)
527
			return ret;
528
		else if (lossy & NLS_NAME_LOSSY)
529
			return -EINVAL;
530
	}
531

532
	uniname.name_len = ret;
533

534
	return exfat_write_volume_label(sb, &uniname);
535
}
536

537
long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
538
{
539
	struct inode *inode = file_inode(filp);
540
	u32 __user *user_attr = (u32 __user *)arg;
541

542
	switch (cmd) {
543
	case FAT_IOCTL_GET_ATTRIBUTES:
544
		return exfat_ioctl_get_attributes(inode, user_attr);
545
	case FAT_IOCTL_SET_ATTRIBUTES:
546
		return exfat_ioctl_set_attributes(filp, user_attr);
547
	case EXFAT_IOC_SHUTDOWN:
548
		return exfat_ioctl_shutdown(inode->i_sb, arg);
549
	case FITRIM:
550
		return exfat_ioctl_fitrim(inode, arg);
551
	case FS_IOC_GETFSLABEL:
552
		return exfat_ioctl_get_volume_label(inode->i_sb, arg);
553
	case FS_IOC_SETFSLABEL:
554
		return exfat_ioctl_set_volume_label(inode->i_sb, arg);
555
	default:
556
		return -ENOTTY;
557
	}
558
}
559

560
#ifdef CONFIG_COMPAT
561
long exfat_compat_ioctl(struct file *filp, unsigned int cmd,
562
				unsigned long arg)
563
{
564
	return exfat_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
565
}
566
#endif
567

568
int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
569
{
570
	struct inode *inode = filp->f_mapping->host;
571
	int err;
572

573
	if (unlikely(exfat_forced_shutdown(inode->i_sb)))
574
		return -EIO;
575

576
	err = __generic_file_fsync(filp, start, end, datasync);
577
	if (err)
578
		return err;
579

580
	err = sync_blockdev(inode->i_sb->s_bdev);
581
	if (err)
582
		return err;
583

584
	return blkdev_issue_flush(inode->i_sb->s_bdev);
585
}
586

587
static int exfat_extend_valid_size(struct inode *inode, loff_t new_valid_size)
588
{
589
	int err;
590
	loff_t pos;
591
	struct exfat_inode_info *ei = EXFAT_I(inode);
592
	struct address_space *mapping = inode->i_mapping;
593
	const struct address_space_operations *ops = mapping->a_ops;
594

595
	pos = ei->valid_size;
596
	while (pos < new_valid_size) {
597
		u32 len;
598
		struct folio *folio;
599
		unsigned long off;
600

601
		len = PAGE_SIZE - (pos & (PAGE_SIZE - 1));
602
		if (pos + len > new_valid_size)
603
			len = new_valid_size - pos;
604

605
		err = ops->write_begin(NULL, mapping, pos, len, &folio, NULL);
606
		if (err)
607
			goto out;
608

609
		off = offset_in_folio(folio, pos);
610
		folio_zero_new_buffers(folio, off, off + len);
611

612
		err = ops->write_end(NULL, mapping, pos, len, len, folio, NULL);
613
		if (err < 0)
614
			goto out;
615
		pos += len;
616

617
		balance_dirty_pages_ratelimited(mapping);
618
		cond_resched();
619
	}
620

621
	return 0;
622

623
out:
624
	return err;
625
}
626

627
static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
628
{
629
	ssize_t ret;
630
	struct file *file = iocb->ki_filp;
631
	struct inode *inode = file_inode(file);
632
	struct exfat_inode_info *ei = EXFAT_I(inode);
633
	loff_t pos = iocb->ki_pos;
634
	loff_t valid_size;
635

636
	if (unlikely(exfat_forced_shutdown(inode->i_sb)))
637
		return -EIO;
638

639
	inode_lock(inode);
640

641
	valid_size = ei->valid_size;
642

643
	ret = generic_write_checks(iocb, iter);
644
	if (ret <= 0)
645
		goto unlock;
646

647
	if (iocb->ki_flags & IOCB_DIRECT) {
648
		unsigned long align = pos | iov_iter_alignment(iter);
649

650
		if (!IS_ALIGNED(align, i_blocksize(inode)) &&
651
		    !IS_ALIGNED(align, bdev_logical_block_size(inode->i_sb->s_bdev))) {
652
			ret = -EINVAL;
653
			goto unlock;
654
		}
655
	}
656

657
	if (pos > valid_size) {
658
		ret = exfat_extend_valid_size(inode, pos);
659
		if (ret < 0 && ret != -ENOSPC) {
660
			exfat_err(inode->i_sb,
661
				"write: fail to zero from %llu to %llu(%zd)",
662
				valid_size, pos, ret);
663
		}
664
		if (ret < 0)
665
			goto unlock;
666
	}
667

668
	ret = __generic_file_write_iter(iocb, iter);
669
	if (ret < 0)
670
		goto unlock;
671

672
	inode_unlock(inode);
673

674
	if (pos > valid_size)
675
		pos = valid_size;
676

677
	if (iocb->ki_pos > pos) {
678
		ssize_t err = generic_write_sync(iocb, iocb->ki_pos - pos);
679
		if (err < 0)
680
			return err;
681
	}
682

683
	return ret;
684

685
unlock:
686
	inode_unlock(inode);
687

688
	return ret;
689
}
690

691
static ssize_t exfat_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
692
{
693
	struct inode *inode = file_inode(iocb->ki_filp);
694

695
	if (unlikely(exfat_forced_shutdown(inode->i_sb)))
696
		return -EIO;
697

698
	return generic_file_read_iter(iocb, iter);
699
}
700

701
static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf)
702
{
703
	int err;
704
	struct vm_area_struct *vma = vmf->vma;
705
	struct file *file = vma->vm_file;
706
	struct inode *inode = file_inode(file);
707
	struct exfat_inode_info *ei = EXFAT_I(inode);
708
	loff_t start, end;
709

710
	if (!inode_trylock(inode))
711
		return VM_FAULT_RETRY;
712

713
	start = ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
714
	end = min_t(loff_t, i_size_read(inode),
715
			start + vma->vm_end - vma->vm_start);
716

717
	if (ei->valid_size < end) {
718
		err = exfat_extend_valid_size(inode, end);
719
		if (err < 0) {
720
			inode_unlock(inode);
721
			return vmf_fs_error(err);
722
		}
723
	}
724

725
	inode_unlock(inode);
726

727
	return filemap_page_mkwrite(vmf);
728
}
729

730
static const struct vm_operations_struct exfat_file_vm_ops = {
731
	.fault		= filemap_fault,
732
	.map_pages	= filemap_map_pages,
733
	.page_mkwrite	= exfat_page_mkwrite,
734
};
735

736
static int exfat_file_mmap_prepare(struct vm_area_desc *desc)
737
{
738
	struct file *file = desc->file;
739

740
	if (unlikely(exfat_forced_shutdown(file_inode(desc->file)->i_sb)))
741
		return -EIO;
742

743
	file_accessed(file);
744
	desc->vm_ops = &exfat_file_vm_ops;
745
	return 0;
746
}
747

748
static ssize_t exfat_splice_read(struct file *in, loff_t *ppos,
749
		struct pipe_inode_info *pipe, size_t len, unsigned int flags)
750
{
751
	if (unlikely(exfat_forced_shutdown(file_inode(in)->i_sb)))
752
		return -EIO;
753

754
	return filemap_splice_read(in, ppos, pipe, len, flags);
755
}
756

757
const struct file_operations exfat_file_operations = {
758
	.llseek		= generic_file_llseek,
759
	.read_iter	= exfat_file_read_iter,
760
	.write_iter	= exfat_file_write_iter,
761
	.unlocked_ioctl = exfat_ioctl,
762
#ifdef CONFIG_COMPAT
763
	.compat_ioctl = exfat_compat_ioctl,
764
#endif
765
	.mmap_prepare	= exfat_file_mmap_prepare,
766
	.fsync		= exfat_file_fsync,
767
	.splice_read	= exfat_splice_read,
768
	.splice_write	= iter_file_splice_write,
769
};
770

771
const struct inode_operations exfat_file_inode_operations = {
772
	.setattr     = exfat_setattr,
773
	.getattr     = exfat_getattr,
774
};
775

776