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/bio.h>
9#include <linux/buffer_head.h>
10
11#include "exfat_raw.h"
12#include "exfat_fs.h"
13
14static int exfat_extract_uni_name(struct exfat_dentry *ep,
15 unsigned short *uniname)
16{
17 int i, len = 0;
18
19 for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
20 *uniname = le16_to_cpu(ep->dentry.name.unicode_0_14[i]);
21 if (*uniname == 0x0)
22 return len;
23 uniname++;
24 len++;
25 }
26
27 *uniname = 0x0;
28 return len;
29
30}
31
32static int exfat_get_uniname_from_ext_entry(struct super_block *sb,
33 struct exfat_chain *p_dir, int entry, unsigned short *uniname)
34{
35 int i, err;
36 struct exfat_entry_set_cache es;
37 unsigned int uni_len = 0, len;
38
39 err = exfat_get_dentry_set(es: &es, sb, p_dir, entry, ES_ALL_ENTRIES);
40 if (err)
41 return err;
42
43 /*
44 * First entry : file entry
45 * Second entry : stream-extension entry
46 * Third entry : first file-name entry
47 * So, the index of first file-name dentry should start from 2.
48 */
49 for (i = ES_IDX_FIRST_FILENAME; i < es.num_entries; i++) {
50 struct exfat_dentry *ep = exfat_get_dentry_cached(es: &es, num: i);
51
52 /* end of name entry */
53 if (exfat_get_entry_type(p_entry: ep) != TYPE_EXTEND)
54 break;
55
56 len = exfat_extract_uni_name(ep, uniname);
57 uni_len += len;
58 if (len != EXFAT_FILE_NAME_LEN || uni_len >= MAX_NAME_LENGTH)
59 break;
60 uniname += EXFAT_FILE_NAME_LEN;
61 }
62
63 exfat_put_dentry_set(es: &es, sync: false);
64 return 0;
65}
66
67/* read a directory entry from the opened directory */
68static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_entry *dir_entry)
69{
70 int i, dentries_per_clu, num_ext, err;
71 unsigned int type, clu_offset, max_dentries;
72 struct exfat_chain dir, clu;
73 struct exfat_uni_name uni_name;
74 struct exfat_dentry *ep;
75 struct super_block *sb = inode->i_sb;
76 struct exfat_sb_info *sbi = EXFAT_SB(sb);
77 struct exfat_inode_info *ei = EXFAT_I(inode);
78 unsigned int dentry = EXFAT_B_TO_DEN(*cpos) & 0xFFFFFFFF;
79 struct buffer_head *bh;
80
81 /* check if the given file ID is opened */
82 if (ei->type != TYPE_DIR)
83 return -EPERM;
84
85 exfat_chain_set(ec: &dir, dir: ei->start_clu,
86 EXFAT_B_TO_CLU(i_size_read(inode), sbi), flags: ei->flags);
87
88 dentries_per_clu = sbi->dentries_per_clu;
89 max_dentries = (unsigned int)min_t(u64, MAX_EXFAT_DENTRIES,
90 (u64)EXFAT_CLU_TO_DEN(sbi->num_clusters, sbi));
91
92 clu_offset = EXFAT_DEN_TO_CLU(dentry, sbi);
93 exfat_chain_dup(dup: &clu, ec: &dir);
94
95 if (clu.flags == ALLOC_NO_FAT_CHAIN) {
96 clu.dir += clu_offset;
97 clu.size -= clu_offset;
98 } else {
99 /* hint_information */
100 if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&
101 ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {
102 clu_offset -= ei->hint_bmap.off;
103 clu.dir = ei->hint_bmap.clu;
104 }
105
106 while (clu_offset > 0 && clu.dir != EXFAT_EOF_CLUSTER) {
107 if (exfat_get_next_cluster(sb, &(clu.dir)))
108 return -EIO;
109
110 clu_offset--;
111 }
112 }
113
114 while (clu.dir != EXFAT_EOF_CLUSTER && dentry < max_dentries) {
115 i = dentry & (dentries_per_clu - 1);
116
117 for ( ; i < dentries_per_clu; i++, dentry++) {
118 ep = exfat_get_dentry(sb, p_dir: &clu, entry: i, bh: &bh);
119 if (!ep)
120 return -EIO;
121
122 type = exfat_get_entry_type(p_entry: ep);
123 if (type == TYPE_UNUSED) {
124 brelse(bh);
125 goto out;
126 }
127
128 if (type != TYPE_FILE && type != TYPE_DIR) {
129 brelse(bh);
130 continue;
131 }
132
133 num_ext = ep->dentry.file.num_ext;
134 dir_entry->attr = le16_to_cpu(ep->dentry.file.attr);
135
136 *uni_name.name = 0x0;
137 err = exfat_get_uniname_from_ext_entry(sb, p_dir: &clu, entry: i,
138 uniname: uni_name.name);
139 if (err) {
140 brelse(bh);
141 continue;
142 }
143 exfat_utf16_to_nls(sb, uniname: &uni_name,
144 p_cstring: dir_entry->namebuf.lfn,
145 len: dir_entry->namebuf.lfnbuf_len);
146 brelse(bh);
147
148 ep = exfat_get_dentry(sb, p_dir: &clu, entry: i + 1, bh: &bh);
149 if (!ep)
150 return -EIO;
151 dir_entry->entry = i;
152 dir_entry->dir = clu;
153 brelse(bh);
154
155 ei->hint_bmap.off = EXFAT_DEN_TO_CLU(dentry, sbi);
156 ei->hint_bmap.clu = clu.dir;
157
158 *cpos = EXFAT_DEN_TO_B(dentry + 1 + num_ext);
159 return 0;
160 }
161
162 if (clu.flags == ALLOC_NO_FAT_CHAIN) {
163 if (--clu.size > 0)
164 clu.dir++;
165 else
166 clu.dir = EXFAT_EOF_CLUSTER;
167 } else {
168 if (exfat_get_next_cluster(sb, &(clu.dir)))
169 return -EIO;
170 }
171 }
172
173out:
174 dir_entry->namebuf.lfn[0] = '\0';
175 *cpos = EXFAT_DEN_TO_B(dentry);
176 return 0;
177}
178
179static void exfat_init_namebuf(struct exfat_dentry_namebuf *nb)
180{
181 nb->lfn = NULL;
182 nb->lfnbuf_len = 0;
183}
184
185static int exfat_alloc_namebuf(struct exfat_dentry_namebuf *nb)
186{
187 nb->lfn = __getname();
188 if (!nb->lfn)
189 return -ENOMEM;
190 nb->lfnbuf_len = MAX_VFSNAME_BUF_SIZE;
191 return 0;
192}
193
194static void exfat_free_namebuf(struct exfat_dentry_namebuf *nb)
195{
196 if (!nb->lfn)
197 return;
198
199 __putname(nb->lfn);
200 exfat_init_namebuf(nb);
201}
202
203/*
204 * Before calling dir_emit*(), sbi->s_lock should be released
205 * because page fault can occur in dir_emit*().
206 */
207#define ITER_POS_FILLED_DOTS (2)
208static int exfat_iterate(struct file *file, struct dir_context *ctx)
209{
210 struct inode *inode = file_inode(f: file);
211 struct super_block *sb = inode->i_sb;
212 struct inode *tmp;
213 struct exfat_dir_entry de;
214 struct exfat_dentry_namebuf *nb = &(de.namebuf);
215 struct exfat_inode_info *ei = EXFAT_I(inode);
216 unsigned long inum;
217 loff_t cpos, i_pos;
218 int err = 0, fake_offset = 0;
219
220 exfat_init_namebuf(nb);
221
222 cpos = ctx->pos;
223 if (!dir_emit_dots(file, ctx))
224 goto out;
225
226 if (ctx->pos == ITER_POS_FILLED_DOTS) {
227 cpos = 0;
228 fake_offset = 1;
229 }
230
231 cpos = round_up(cpos, DENTRY_SIZE);
232
233 /* name buffer should be allocated before use */
234 err = exfat_alloc_namebuf(nb);
235 if (err)
236 goto out;
237get_new:
238 mutex_lock(&EXFAT_SB(sb)->s_lock);
239
240 if (ei->flags == ALLOC_NO_FAT_CHAIN && cpos >= i_size_read(inode))
241 goto end_of_dir;
242
243 err = exfat_readdir(inode, cpos: &cpos, dir_entry: &de);
244 if (err) {
245 /*
246 * At least we tried to read a sector.
247 * Move cpos to next sector position (should be aligned).
248 */
249 if (err == -EIO) {
250 cpos += 1 << (sb->s_blocksize_bits);
251 cpos &= ~(sb->s_blocksize - 1);
252 }
253
254 err = -EIO;
255 goto end_of_dir;
256 }
257
258 if (!nb->lfn[0])
259 goto end_of_dir;
260
261 i_pos = ((loff_t)de.dir.dir << 32) | (de.entry & 0xffffffff);
262 tmp = exfat_iget(sb, i_pos);
263 if (tmp) {
264 inum = tmp->i_ino;
265 iput(tmp);
266 } else {
267 inum = iunique(sb, EXFAT_ROOT_INO);
268 }
269
270 mutex_unlock(lock: &EXFAT_SB(sb)->s_lock);
271 if (!dir_emit(ctx, name: nb->lfn, strlen(nb->lfn), ino: inum,
272 type: (de.attr & EXFAT_ATTR_SUBDIR) ? DT_DIR : DT_REG))
273 goto out;
274 ctx->pos = cpos;
275 goto get_new;
276
277end_of_dir:
278 if (!cpos && fake_offset)
279 cpos = ITER_POS_FILLED_DOTS;
280 ctx->pos = cpos;
281 mutex_unlock(lock: &EXFAT_SB(sb)->s_lock);
282out:
283 /*
284 * To improve performance, free namebuf after unlock sb_lock.
285 * If namebuf is not allocated, this function do nothing
286 */
287 exfat_free_namebuf(nb);
288 return err;
289}
290
291WRAP_DIR_ITER(exfat_iterate) // FIXME!
292const struct file_operations exfat_dir_operations = {
293 .llseek = generic_file_llseek,
294 .read = generic_read_dir,
295 .iterate_shared = shared_exfat_iterate,
296 .unlocked_ioctl = exfat_ioctl,
297#ifdef CONFIG_COMPAT
298 .compat_ioctl = exfat_compat_ioctl,
299#endif
300 .fsync = exfat_file_fsync,
301};
302
303int exfat_alloc_new_dir(struct inode *inode, struct exfat_chain *clu)
304{
305 int ret;
306
307 exfat_chain_set(ec: clu, EXFAT_EOF_CLUSTER, size: 0, ALLOC_NO_FAT_CHAIN);
308
309 ret = exfat_alloc_cluster(inode, num_alloc: 1, p_chain: clu, IS_DIRSYNC(inode));
310 if (ret)
311 return ret;
312
313 return exfat_zeroed_cluster(dir: inode, clu: clu->dir);
314}
315
316int exfat_calc_num_entries(struct exfat_uni_name *p_uniname)
317{
318 int len;
319
320 len = p_uniname->name_len;
321 if (len == 0)
322 return -EINVAL;
323
324 /* 1 file entry + 1 stream entry + name entries */
325 return ES_ENTRY_NUM(len);
326}
327
328unsigned int exfat_get_entry_type(struct exfat_dentry *ep)
329{
330 if (ep->type == EXFAT_UNUSED)
331 return TYPE_UNUSED;
332 if (IS_EXFAT_DELETED(ep->type))
333 return TYPE_DELETED;
334 if (ep->type == EXFAT_INVAL)
335 return TYPE_INVALID;
336 if (IS_EXFAT_CRITICAL_PRI(ep->type)) {
337 if (ep->type == EXFAT_BITMAP)
338 return TYPE_BITMAP;
339 if (ep->type == EXFAT_UPCASE)
340 return TYPE_UPCASE;
341 if (ep->type == EXFAT_VOLUME)
342 return TYPE_VOLUME;
343 if (ep->type == EXFAT_FILE) {
344 if (le16_to_cpu(ep->dentry.file.attr) & EXFAT_ATTR_SUBDIR)
345 return TYPE_DIR;
346 return TYPE_FILE;
347 }
348 return TYPE_CRITICAL_PRI;
349 }
350 if (IS_EXFAT_BENIGN_PRI(ep->type)) {
351 if (ep->type == EXFAT_GUID)
352 return TYPE_GUID;
353 if (ep->type == EXFAT_PADDING)
354 return TYPE_PADDING;
355 if (ep->type == EXFAT_ACLTAB)
356 return TYPE_ACLTAB;
357 return TYPE_BENIGN_PRI;
358 }
359 if (IS_EXFAT_CRITICAL_SEC(ep->type)) {
360 if (ep->type == EXFAT_STREAM)
361 return TYPE_STREAM;
362 if (ep->type == EXFAT_NAME)
363 return TYPE_EXTEND;
364 if (ep->type == EXFAT_ACL)
365 return TYPE_ACL;
366 return TYPE_CRITICAL_SEC;
367 }
368
369 if (ep->type == EXFAT_VENDOR_EXT)
370 return TYPE_VENDOR_EXT;
371 if (ep->type == EXFAT_VENDOR_ALLOC)
372 return TYPE_VENDOR_ALLOC;
373
374 return TYPE_BENIGN_SEC;
375}
376
377static void exfat_set_entry_type(struct exfat_dentry *ep, unsigned int type)
378{
379 if (type == TYPE_UNUSED) {
380 ep->type = EXFAT_UNUSED;
381 } else if (type == TYPE_DELETED) {
382 ep->type &= EXFAT_DELETE;
383 } else if (type == TYPE_STREAM) {
384 ep->type = EXFAT_STREAM;
385 } else if (type == TYPE_EXTEND) {
386 ep->type = EXFAT_NAME;
387 } else if (type == TYPE_BITMAP) {
388 ep->type = EXFAT_BITMAP;
389 } else if (type == TYPE_UPCASE) {
390 ep->type = EXFAT_UPCASE;
391 } else if (type == TYPE_VOLUME) {
392 ep->type = EXFAT_VOLUME;
393 } else if (type == TYPE_DIR) {
394 ep->type = EXFAT_FILE;
395 ep->dentry.file.attr = cpu_to_le16(EXFAT_ATTR_SUBDIR);
396 } else if (type == TYPE_FILE) {
397 ep->type = EXFAT_FILE;
398 ep->dentry.file.attr = cpu_to_le16(EXFAT_ATTR_ARCHIVE);
399 }
400}
401
402static void exfat_init_stream_entry(struct exfat_dentry *ep,
403 unsigned int start_clu, unsigned long long size)
404{
405 memset(ep, 0, sizeof(*ep));
406 exfat_set_entry_type(ep, TYPE_STREAM);
407 if (size == 0)
408 ep->dentry.stream.flags = ALLOC_FAT_CHAIN;
409 else
410 ep->dentry.stream.flags = ALLOC_NO_FAT_CHAIN;
411 ep->dentry.stream.start_clu = cpu_to_le32(start_clu);
412 ep->dentry.stream.valid_size = cpu_to_le64(size);
413 ep->dentry.stream.size = cpu_to_le64(size);
414}
415
416static void exfat_init_name_entry(struct exfat_dentry *ep,
417 unsigned short *uniname)
418{
419 int i;
420
421 exfat_set_entry_type(ep, TYPE_EXTEND);
422 ep->dentry.name.flags = 0x0;
423
424 for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
425 if (*uniname != 0x0) {
426 ep->dentry.name.unicode_0_14[i] = cpu_to_le16(*uniname);
427 uniname++;
428 } else {
429 ep->dentry.name.unicode_0_14[i] = 0x0;
430 }
431 }
432}
433
434void exfat_init_dir_entry(struct exfat_entry_set_cache *es,
435 unsigned int type, unsigned int start_clu,
436 unsigned long long size, struct timespec64 *ts)
437{
438 struct super_block *sb = es->sb;
439 struct exfat_sb_info *sbi = EXFAT_SB(sb);
440 struct exfat_dentry *ep;
441
442 ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
443 memset(ep, 0, sizeof(*ep));
444 exfat_set_entry_type(ep, type);
445 exfat_set_entry_time(sbi, ts,
446 tz: &ep->dentry.file.create_tz,
447 time: &ep->dentry.file.create_time,
448 date: &ep->dentry.file.create_date,
449 time_cs: &ep->dentry.file.create_time_cs);
450 exfat_set_entry_time(sbi, ts,
451 tz: &ep->dentry.file.modify_tz,
452 time: &ep->dentry.file.modify_time,
453 date: &ep->dentry.file.modify_date,
454 time_cs: &ep->dentry.file.modify_time_cs);
455 exfat_set_entry_time(sbi, ts,
456 tz: &ep->dentry.file.access_tz,
457 time: &ep->dentry.file.access_time,
458 date: &ep->dentry.file.access_date,
459 NULL);
460
461 ep = exfat_get_dentry_cached(es, ES_IDX_STREAM);
462 exfat_init_stream_entry(ep, start_clu, size);
463}
464
465static void exfat_free_benign_secondary_clusters(struct inode *inode,
466 struct exfat_dentry *ep)
467{
468 struct super_block *sb = inode->i_sb;
469 struct exfat_chain dir;
470 unsigned int start_clu =
471 le32_to_cpu(ep->dentry.generic_secondary.start_clu);
472 u64 size = le64_to_cpu(ep->dentry.generic_secondary.size);
473 unsigned char flags = ep->dentry.generic_secondary.flags;
474
475 if (!(flags & ALLOC_POSSIBLE) || !start_clu || !size)
476 return;
477
478 exfat_chain_set(ec: &dir, dir: start_clu,
479 EXFAT_B_TO_CLU_ROUND_UP(size, EXFAT_SB(sb)),
480 flags);
481 exfat_free_cluster(inode, p_chain: &dir);
482}
483
484void exfat_init_ext_entry(struct exfat_entry_set_cache *es, int num_entries,
485 struct exfat_uni_name *p_uniname)
486{
487 int i;
488 unsigned short *uniname = p_uniname->name;
489 struct exfat_dentry *ep;
490
491 ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
492 ep->dentry.file.num_ext = (unsigned char)(num_entries - 1);
493
494 ep = exfat_get_dentry_cached(es, ES_IDX_STREAM);
495 ep->dentry.stream.name_len = p_uniname->name_len;
496 ep->dentry.stream.name_hash = cpu_to_le16(p_uniname->name_hash);
497
498 for (i = ES_IDX_FIRST_FILENAME; i < num_entries; i++) {
499 ep = exfat_get_dentry_cached(es, num: i);
500 exfat_init_name_entry(ep, uniname);
501 uniname += EXFAT_FILE_NAME_LEN;
502 }
503
504 exfat_update_dir_chksum(es);
505}
506
507void exfat_remove_entries(struct inode *inode, struct exfat_entry_set_cache *es,
508 int order)
509{
510 int i;
511 struct exfat_dentry *ep;
512
513 for (i = order; i < es->num_entries; i++) {
514 ep = exfat_get_dentry_cached(es, num: i);
515
516 if (exfat_get_entry_type(ep) & TYPE_BENIGN_SEC)
517 exfat_free_benign_secondary_clusters(inode, ep);
518
519 exfat_set_entry_type(ep, TYPE_DELETED);
520 }
521
522 if (order < es->num_entries)
523 es->modified = true;
524}
525
526void exfat_update_dir_chksum(struct exfat_entry_set_cache *es)
527{
528 int chksum_type = CS_DIR_ENTRY, i;
529 unsigned short chksum = 0;
530 struct exfat_dentry *ep;
531
532 for (i = ES_IDX_FILE; i < es->num_entries; i++) {
533 ep = exfat_get_dentry_cached(es, num: i);
534 chksum = exfat_calc_chksum16(data: ep, DENTRY_SIZE, chksum,
535 type: chksum_type);
536 chksum_type = CS_DEFAULT;
537 }
538 ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
539 ep->dentry.file.checksum = cpu_to_le16(chksum);
540 es->modified = true;
541}
542
543int exfat_put_dentry_set(struct exfat_entry_set_cache *es, int sync)
544{
545 int i, err = 0;
546
547 if (es->modified)
548 err = exfat_update_bhs(bhs: es->bh, nr_bhs: es->num_bh, sync);
549
550 for (i = 0; i < es->num_bh; i++)
551 if (err)
552 bforget(bh: es->bh[i]);
553 else
554 brelse(bh: es->bh[i]);
555
556 if (IS_DYNAMIC_ES(es))
557 kfree(objp: es->bh);
558
559 return err;
560}
561
562static int exfat_walk_fat_chain(struct super_block *sb,
563 struct exfat_chain *p_dir, unsigned int byte_offset,
564 unsigned int *clu)
565{
566 struct exfat_sb_info *sbi = EXFAT_SB(sb);
567 unsigned int clu_offset;
568 unsigned int cur_clu;
569
570 clu_offset = EXFAT_B_TO_CLU(byte_offset, sbi);
571 cur_clu = p_dir->dir;
572
573 if (p_dir->flags == ALLOC_NO_FAT_CHAIN) {
574 cur_clu += clu_offset;
575 } else {
576 while (clu_offset > 0) {
577 if (exfat_get_next_cluster(sb, &cur_clu))
578 return -EIO;
579 if (cur_clu == EXFAT_EOF_CLUSTER) {
580 exfat_fs_error(sb,
581 "invalid dentry access beyond EOF (clu : %u, eidx : %d)",
582 p_dir->dir,
583 EXFAT_B_TO_DEN(byte_offset));
584 return -EIO;
585 }
586 clu_offset--;
587 }
588 }
589
590 *clu = cur_clu;
591 return 0;
592}
593
594static int exfat_find_location(struct super_block *sb, struct exfat_chain *p_dir,
595 int entry, sector_t *sector, int *offset)
596{
597 int ret;
598 unsigned int off, clu = 0;
599 struct exfat_sb_info *sbi = EXFAT_SB(sb);
600
601 off = EXFAT_DEN_TO_B(entry);
602
603 ret = exfat_walk_fat_chain(sb, p_dir, byte_offset: off, clu: &clu);
604 if (ret)
605 return ret;
606
607 if (!exfat_test_bitmap(sb, clu)) {
608 exfat_err(sb, "failed to test cluster bit(%u)", clu);
609 return -EIO;
610 }
611
612 /* byte offset in cluster */
613 off = EXFAT_CLU_OFFSET(off, sbi);
614
615 /* byte offset in sector */
616 *offset = EXFAT_BLK_OFFSET(off, sb);
617
618 /* sector offset in cluster */
619 *sector = EXFAT_B_TO_BLK(off, sb);
620 *sector += exfat_cluster_to_sector(sbi, clus: clu);
621 return 0;
622}
623
624#define EXFAT_MAX_RA_SIZE (128*1024)
625static int exfat_dir_readahead(struct super_block *sb, sector_t sec)
626{
627 struct exfat_sb_info *sbi = EXFAT_SB(sb);
628 struct buffer_head *bh;
629 unsigned int max_ra_count = EXFAT_MAX_RA_SIZE >> sb->s_blocksize_bits;
630 unsigned int page_ra_count = PAGE_SIZE >> sb->s_blocksize_bits;
631 unsigned int adj_ra_count = max(sbi->sect_per_clus, page_ra_count);
632 unsigned int ra_count = min(adj_ra_count, max_ra_count);
633
634 /* Read-ahead is not required */
635 if (sbi->sect_per_clus == 1)
636 return 0;
637
638 if (sec < sbi->data_start_sector) {
639 exfat_err(sb, "requested sector is invalid(sect:%llu, root:%llu)",
640 (unsigned long long)sec, sbi->data_start_sector);
641 return -EIO;
642 }
643
644 /* Not sector aligned with ra_count, resize ra_count to page size */
645 if ((sec - sbi->data_start_sector) & (ra_count - 1))
646 ra_count = page_ra_count;
647
648 bh = sb_find_get_block(sb, block: sec);
649 if (!bh || !buffer_uptodate(bh)) {
650 unsigned int i;
651
652 for (i = 0; i < ra_count; i++)
653 sb_breadahead(sb, block: (sector_t)(sec + i));
654 }
655 brelse(bh);
656 return 0;
657}
658
659struct exfat_dentry *exfat_get_dentry(struct super_block *sb,
660 struct exfat_chain *p_dir, int entry, struct buffer_head **bh)
661{
662 unsigned int dentries_per_page = EXFAT_B_TO_DEN(PAGE_SIZE);
663 int off;
664 sector_t sec;
665
666 if (p_dir->dir == DIR_DELETED) {
667 exfat_err(sb, "abnormal access to deleted dentry");
668 return NULL;
669 }
670
671 if (exfat_find_location(sb, p_dir, entry, sector: &sec, offset: &off))
672 return NULL;
673
674 if (p_dir->dir != EXFAT_FREE_CLUSTER &&
675 !(entry & (dentries_per_page - 1)))
676 exfat_dir_readahead(sb, sec);
677
678 *bh = sb_bread(sb, block: sec);
679 if (!*bh)
680 return NULL;
681
682 return (struct exfat_dentry *)((*bh)->b_data + off);
683}
684
685enum exfat_validate_dentry_mode {
686 ES_MODE_GET_FILE_ENTRY,
687 ES_MODE_GET_STRM_ENTRY,
688 ES_MODE_GET_NAME_ENTRY,
689 ES_MODE_GET_CRITICAL_SEC_ENTRY,
690 ES_MODE_GET_BENIGN_SEC_ENTRY,
691};
692
693static bool exfat_validate_entry(unsigned int type,
694 enum exfat_validate_dentry_mode *mode)
695{
696 if (type == TYPE_UNUSED || type == TYPE_DELETED)
697 return false;
698
699 switch (*mode) {
700 case ES_MODE_GET_FILE_ENTRY:
701 if (type != TYPE_STREAM)
702 return false;
703 *mode = ES_MODE_GET_STRM_ENTRY;
704 break;
705 case ES_MODE_GET_STRM_ENTRY:
706 if (type != TYPE_EXTEND)
707 return false;
708 *mode = ES_MODE_GET_NAME_ENTRY;
709 break;
710 case ES_MODE_GET_NAME_ENTRY:
711 if (type & TYPE_BENIGN_SEC)
712 *mode = ES_MODE_GET_BENIGN_SEC_ENTRY;
713 else if (type != TYPE_EXTEND)
714 return false;
715 break;
716 case ES_MODE_GET_BENIGN_SEC_ENTRY:
717 /* Assume unreconized benign secondary entry */
718 if (!(type & TYPE_BENIGN_SEC))
719 return false;
720 break;
721 default:
722 return false;
723 }
724
725 return true;
726}
727
728struct exfat_dentry *exfat_get_dentry_cached(
729 struct exfat_entry_set_cache *es, int num)
730{
731 int off = es->start_off + num * DENTRY_SIZE;
732 struct buffer_head *bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
733 char *p = bh->b_data + EXFAT_BLK_OFFSET(off, es->sb);
734
735 return (struct exfat_dentry *)p;
736}
737
738/*
739 * Returns a set of dentries.
740 *
741 * Note It provides a direct pointer to bh->data via exfat_get_dentry_cached().
742 * User should call exfat_get_dentry_set() after setting 'modified' to apply
743 * changes made in this entry set to the real device.
744 *
745 * in:
746 * sb+p_dir+entry: indicates a file/dir
747 * num_entries: specifies how many dentries should be included.
748 * It will be set to es->num_entries if it is not 0.
749 * If num_entries is 0, es->num_entries will be obtained
750 * from the first dentry.
751 * out:
752 * es: pointer of entry set on success.
753 * return:
754 * 0 on success
755 * -error code on failure
756 */
757static int __exfat_get_dentry_set(struct exfat_entry_set_cache *es,
758 struct super_block *sb, struct exfat_chain *p_dir, int entry,
759 unsigned int num_entries)
760{
761 int ret, i, num_bh;
762 unsigned int off;
763 sector_t sec;
764 struct exfat_sb_info *sbi = EXFAT_SB(sb);
765 struct buffer_head *bh;
766
767 if (p_dir->dir == DIR_DELETED) {
768 exfat_err(sb, "access to deleted dentry");
769 return -EIO;
770 }
771
772 ret = exfat_find_location(sb, p_dir, entry, sector: &sec, offset: &off);
773 if (ret)
774 return ret;
775
776 memset(es, 0, sizeof(*es));
777 es->sb = sb;
778 es->modified = false;
779 es->start_off = off;
780 es->bh = es->__bh;
781
782 bh = sb_bread(sb, block: sec);
783 if (!bh)
784 return -EIO;
785 es->bh[es->num_bh++] = bh;
786
787 if (num_entries == ES_ALL_ENTRIES) {
788 struct exfat_dentry *ep;
789
790 ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
791 if (ep->type != EXFAT_FILE) {
792 brelse(bh);
793 return -EIO;
794 }
795
796 num_entries = ep->dentry.file.num_ext + 1;
797 }
798
799 es->num_entries = num_entries;
800
801 num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
802 if (num_bh > ARRAY_SIZE(es->__bh)) {
803 es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_NOFS);
804 if (!es->bh) {
805 brelse(bh);
806 return -ENOMEM;
807 }
808 es->bh[0] = bh;
809 }
810
811 for (i = 1; i < num_bh; i++) {
812 /* get the next sector */
813 if (exfat_is_last_sector_in_cluster(sbi, sec)) {
814 unsigned int clu = exfat_sector_to_cluster(sbi, sec);
815
816 if (p_dir->flags == ALLOC_NO_FAT_CHAIN)
817 clu++;
818 else if (exfat_get_next_cluster(sb, &clu))
819 goto put_es;
820 sec = exfat_cluster_to_sector(sbi, clus: clu);
821 } else {
822 sec++;
823 }
824
825 bh = sb_bread(sb, block: sec);
826 if (!bh)
827 goto put_es;
828 es->bh[es->num_bh++] = bh;
829 }
830
831 return 0;
832
833put_es:
834 exfat_put_dentry_set(es, sync: false);
835 return -EIO;
836}
837
838int exfat_get_dentry_set(struct exfat_entry_set_cache *es,
839 struct super_block *sb, struct exfat_chain *p_dir,
840 int entry, unsigned int num_entries)
841{
842 int ret, i;
843 struct exfat_dentry *ep;
844 enum exfat_validate_dentry_mode mode = ES_MODE_GET_FILE_ENTRY;
845
846 ret = __exfat_get_dentry_set(es, sb, p_dir, entry, num_entries);
847 if (ret < 0)
848 return ret;
849
850 /* validate cached dentries */
851 for (i = ES_IDX_STREAM; i < es->num_entries; i++) {
852 ep = exfat_get_dentry_cached(es, num: i);
853 if (!exfat_validate_entry(type: exfat_get_entry_type(ep), mode: &mode))
854 goto put_es;
855 }
856 return 0;
857
858put_es:
859 exfat_put_dentry_set(es, sync: false);
860 return -EIO;
861}
862
863static int exfat_validate_empty_dentry_set(struct exfat_entry_set_cache *es)
864{
865 struct exfat_dentry *ep;
866 struct buffer_head *bh;
867 int i, off;
868 bool unused_hit = false;
869
870 /*
871 * ONLY UNUSED OR DELETED DENTRIES ARE ALLOWED:
872 * Although it violates the specification for a deleted entry to
873 * follow an unused entry, some exFAT implementations could work
874 * like this. Therefore, to improve compatibility, let's allow it.
875 */
876 for (i = 0; i < es->num_entries; i++) {
877 ep = exfat_get_dentry_cached(es, num: i);
878 if (ep->type == EXFAT_UNUSED) {
879 unused_hit = true;
880 } else if (!IS_EXFAT_DELETED(ep->type)) {
881 if (unused_hit)
882 goto err_used_follow_unused;
883 i++;
884 goto count_skip_entries;
885 }
886 }
887
888 return 0;
889
890err_used_follow_unused:
891 off = es->start_off + (i << DENTRY_SIZE_BITS);
892 bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
893
894 exfat_fs_error(es->sb,
895 "in sector %lld, dentry %d should be unused, but 0x%x",
896 bh->b_blocknr, off >> DENTRY_SIZE_BITS, ep->type);
897
898 return -EIO;
899
900count_skip_entries:
901 es->num_entries = EXFAT_B_TO_DEN(EXFAT_BLK_TO_B(es->num_bh, es->sb) - es->start_off);
902 for (; i < es->num_entries; i++) {
903 ep = exfat_get_dentry_cached(es, num: i);
904 if (IS_EXFAT_DELETED(ep->type))
905 break;
906 }
907
908 return i;
909}
910
911/*
912 * Get an empty dentry set.
913 *
914 * in:
915 * sb+p_dir+entry: indicates the empty dentry location
916 * num_entries: specifies how many empty dentries should be included.
917 * out:
918 * es: pointer of empty dentry set on success.
919 * return:
920 * 0 : on success
921 * >0 : the dentries are not empty, the return value is the number of
922 * dentries to be skipped for the next lookup.
923 * <0 : on failure
924 */
925int exfat_get_empty_dentry_set(struct exfat_entry_set_cache *es,
926 struct super_block *sb, struct exfat_chain *p_dir,
927 int entry, unsigned int num_entries)
928{
929 int ret;
930
931 ret = __exfat_get_dentry_set(es, sb, p_dir, entry, num_entries);
932 if (ret < 0)
933 return ret;
934
935 ret = exfat_validate_empty_dentry_set(es);
936 if (ret)
937 exfat_put_dentry_set(es, sync: false);
938
939 return ret;
940}
941
942static inline void exfat_reset_empty_hint(struct exfat_hint_femp *hint_femp)
943{
944 hint_femp->eidx = EXFAT_HINT_NONE;
945 hint_femp->count = 0;
946}
947
948static inline void exfat_set_empty_hint(struct exfat_inode_info *ei,
949 struct exfat_hint_femp *candi_empty, struct exfat_chain *clu,
950 int dentry, int num_entries, int entry_type)
951{
952 if (ei->hint_femp.eidx == EXFAT_HINT_NONE ||
953 ei->hint_femp.eidx > dentry) {
954 int total_entries = EXFAT_B_TO_DEN(i_size_read(&ei->vfs_inode));
955
956 if (candi_empty->count == 0) {
957 candi_empty->cur = *clu;
958 candi_empty->eidx = dentry;
959 }
960
961 if (entry_type == TYPE_UNUSED)
962 candi_empty->count += total_entries - dentry;
963 else
964 candi_empty->count++;
965
966 if (candi_empty->count == num_entries ||
967 candi_empty->count + candi_empty->eidx == total_entries)
968 ei->hint_femp = *candi_empty;
969 }
970}
971
972enum {
973 DIRENT_STEP_FILE,
974 DIRENT_STEP_STRM,
975 DIRENT_STEP_NAME,
976 DIRENT_STEP_SECD,
977};
978
979/*
980 * @ei: inode info of parent directory
981 * @p_dir: directory structure of parent directory
982 * @num_entries:entry size of p_uniname
983 * @hint_opt: If p_uniname is found, filled with optimized dir/entry
984 * for traversing cluster chain.
985 * @return:
986 * >= 0: file directory entry position where the name exists
987 * -ENOENT: entry with the name does not exist
988 * -EIO: I/O error
989 */
990int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
991 struct exfat_chain *p_dir, struct exfat_uni_name *p_uniname,
992 struct exfat_hint *hint_opt)
993{
994 int i, rewind = 0, dentry = 0, end_eidx = 0, num_ext = 0, len;
995 int order, step, name_len = 0;
996 int dentries_per_clu;
997 unsigned int entry_type;
998 unsigned short *uniname = NULL;
999 struct exfat_chain clu;
1000 struct exfat_hint *hint_stat = &ei->hint_stat;
1001 struct exfat_hint_femp candi_empty;
1002 struct exfat_sb_info *sbi = EXFAT_SB(sb);
1003 int num_entries = exfat_calc_num_entries(p_uniname);
1004 unsigned int clu_count = 0;
1005
1006 if (num_entries < 0)
1007 return num_entries;
1008
1009 dentries_per_clu = sbi->dentries_per_clu;
1010
1011 exfat_chain_dup(dup: &clu, ec: p_dir);
1012
1013 if (hint_stat->eidx) {
1014 clu.dir = hint_stat->clu;
1015 dentry = hint_stat->eidx;
1016 end_eidx = dentry;
1017 }
1018
1019 exfat_reset_empty_hint(hint_femp: &ei->hint_femp);
1020
1021rewind:
1022 order = 0;
1023 step = DIRENT_STEP_FILE;
1024 exfat_reset_empty_hint(hint_femp: &candi_empty);
1025
1026 while (clu.dir != EXFAT_EOF_CLUSTER) {
1027 i = dentry & (dentries_per_clu - 1);
1028 for (; i < dentries_per_clu; i++, dentry++) {
1029 struct exfat_dentry *ep;
1030 struct buffer_head *bh;
1031
1032 if (rewind && dentry == end_eidx)
1033 goto not_found;
1034
1035 ep = exfat_get_dentry(sb, p_dir: &clu, entry: i, bh: &bh);
1036 if (!ep)
1037 return -EIO;
1038
1039 entry_type = exfat_get_entry_type(ep);
1040
1041 if (entry_type == TYPE_UNUSED ||
1042 entry_type == TYPE_DELETED) {
1043 step = DIRENT_STEP_FILE;
1044
1045 exfat_set_empty_hint(ei, candi_empty: &candi_empty, clu: &clu,
1046 dentry, num_entries,
1047 entry_type);
1048
1049 brelse(bh);
1050 if (entry_type == TYPE_UNUSED)
1051 goto not_found;
1052 continue;
1053 }
1054
1055 exfat_reset_empty_hint(hint_femp: &candi_empty);
1056
1057 if (entry_type == TYPE_FILE || entry_type == TYPE_DIR) {
1058 step = DIRENT_STEP_FILE;
1059 hint_opt->clu = clu.dir;
1060 hint_opt->eidx = i;
1061 num_ext = ep->dentry.file.num_ext;
1062 step = DIRENT_STEP_STRM;
1063 brelse(bh);
1064 continue;
1065 }
1066
1067 if (entry_type == TYPE_STREAM) {
1068 u16 name_hash;
1069
1070 if (step != DIRENT_STEP_STRM) {
1071 step = DIRENT_STEP_FILE;
1072 brelse(bh);
1073 continue;
1074 }
1075 step = DIRENT_STEP_FILE;
1076 name_hash = le16_to_cpu(
1077 ep->dentry.stream.name_hash);
1078 if (p_uniname->name_hash == name_hash &&
1079 p_uniname->name_len ==
1080 ep->dentry.stream.name_len) {
1081 step = DIRENT_STEP_NAME;
1082 order = 1;
1083 name_len = 0;
1084 }
1085 brelse(bh);
1086 continue;
1087 }
1088
1089 brelse(bh);
1090 if (entry_type == TYPE_EXTEND) {
1091 unsigned short entry_uniname[16], unichar;
1092
1093 if (step != DIRENT_STEP_NAME ||
1094 name_len >= MAX_NAME_LENGTH) {
1095 step = DIRENT_STEP_FILE;
1096 continue;
1097 }
1098
1099 if (++order == 2)
1100 uniname = p_uniname->name;
1101 else
1102 uniname += EXFAT_FILE_NAME_LEN;
1103
1104 len = exfat_extract_uni_name(ep, uniname: entry_uniname);
1105 name_len += len;
1106
1107 unichar = *(uniname+len);
1108 *(uniname+len) = 0x0;
1109
1110 if (exfat_uniname_ncmp(sb, a: uniname,
1111 b: entry_uniname, len)) {
1112 step = DIRENT_STEP_FILE;
1113 } else if (p_uniname->name_len == name_len) {
1114 if (order == num_ext)
1115 goto found;
1116 step = DIRENT_STEP_SECD;
1117 }
1118
1119 *(uniname+len) = unichar;
1120 continue;
1121 }
1122
1123 if (entry_type &
1124 (TYPE_CRITICAL_SEC | TYPE_BENIGN_SEC)) {
1125 if (step == DIRENT_STEP_SECD) {
1126 if (++order == num_ext)
1127 goto found;
1128 continue;
1129 }
1130 }
1131 step = DIRENT_STEP_FILE;
1132 }
1133
1134 if (clu.flags == ALLOC_NO_FAT_CHAIN) {
1135 if (--clu.size > 0)
1136 clu.dir++;
1137 else
1138 clu.dir = EXFAT_EOF_CLUSTER;
1139 } else {
1140 if (exfat_get_next_cluster(sb, &clu.dir))
1141 return -EIO;
1142
1143 /* break if the cluster chain includes a loop */
1144 if (unlikely(++clu_count > EXFAT_DATA_CLUSTER_COUNT(sbi)))
1145 goto not_found;
1146 }
1147 }
1148
1149not_found:
1150 /*
1151 * We started at not 0 index,so we should try to find target
1152 * from 0 index to the index we started at.
1153 */
1154 if (!rewind && end_eidx) {
1155 rewind = 1;
1156 dentry = 0;
1157 clu.dir = p_dir->dir;
1158 goto rewind;
1159 }
1160
1161 /*
1162 * set the EXFAT_EOF_CLUSTER flag to avoid search
1163 * from the beginning again when allocated a new cluster
1164 */
1165 if (ei->hint_femp.eidx == EXFAT_HINT_NONE) {
1166 ei->hint_femp.cur.dir = EXFAT_EOF_CLUSTER;
1167 ei->hint_femp.eidx = p_dir->size * dentries_per_clu;
1168 ei->hint_femp.count = 0;
1169 }
1170
1171 /* initialized hint_stat */
1172 hint_stat->clu = p_dir->dir;
1173 hint_stat->eidx = 0;
1174 return -ENOENT;
1175
1176found:
1177 /* next dentry we'll find is out of this cluster */
1178 if (!((dentry + 1) & (dentries_per_clu - 1))) {
1179 int ret = 0;
1180
1181 if (clu.flags == ALLOC_NO_FAT_CHAIN) {
1182 if (--clu.size > 0)
1183 clu.dir++;
1184 else
1185 clu.dir = EXFAT_EOF_CLUSTER;
1186 } else {
1187 ret = exfat_get_next_cluster(sb, &clu.dir);
1188 }
1189
1190 if (ret || clu.dir == EXFAT_EOF_CLUSTER) {
1191 /* just initialized hint_stat */
1192 hint_stat->clu = p_dir->dir;
1193 hint_stat->eidx = 0;
1194 return (dentry - num_ext);
1195 }
1196 }
1197
1198 hint_stat->clu = clu.dir;
1199 hint_stat->eidx = dentry + 1;
1200 return dentry - num_ext;
1201}
1202
1203int exfat_count_dir_entries(struct super_block *sb, struct exfat_chain *p_dir)
1204{
1205 int i, count = 0;
1206 int dentries_per_clu;
1207 unsigned int entry_type;
1208 unsigned int clu_count = 0;
1209 struct exfat_chain clu;
1210 struct exfat_dentry *ep;
1211 struct exfat_sb_info *sbi = EXFAT_SB(sb);
1212 struct buffer_head *bh;
1213
1214 dentries_per_clu = sbi->dentries_per_clu;
1215
1216 exfat_chain_dup(dup: &clu, ec: p_dir);
1217
1218 while (clu.dir != EXFAT_EOF_CLUSTER) {
1219 for (i = 0; i < dentries_per_clu; i++) {
1220 ep = exfat_get_dentry(sb, p_dir: &clu, entry: i, bh: &bh);
1221 if (!ep)
1222 return -EIO;
1223 entry_type = exfat_get_entry_type(ep);
1224 brelse(bh);
1225
1226 if (entry_type == TYPE_UNUSED)
1227 return count;
1228 if (entry_type != TYPE_DIR)
1229 continue;
1230 count++;
1231 }
1232
1233 if (clu.flags == ALLOC_NO_FAT_CHAIN) {
1234 if (--clu.size > 0)
1235 clu.dir++;
1236 else
1237 clu.dir = EXFAT_EOF_CLUSTER;
1238 } else {
1239 if (exfat_get_next_cluster(sb, &(clu.dir)))
1240 return -EIO;
1241
1242 if (unlikely(++clu_count > sbi->used_clusters)) {
1243 exfat_fs_error(sb, "FAT or bitmap is corrupted");
1244 return -EIO;
1245 }
1246
1247 }
1248 }
1249
1250 return count;
1251}
1252
1253static int exfat_get_volume_label_dentry(struct super_block *sb,
1254 struct exfat_entry_set_cache *es)
1255{
1256 int i;
1257 int dentry = 0;
1258 unsigned int type;
1259 struct exfat_sb_info *sbi = EXFAT_SB(sb);
1260 struct exfat_hint_femp hint_femp;
1261 struct exfat_inode_info *ei = EXFAT_I(inode: sb->s_root->d_inode);
1262 struct exfat_chain clu;
1263 struct exfat_dentry *ep;
1264 struct buffer_head *bh;
1265
1266 hint_femp.eidx = EXFAT_HINT_NONE;
1267 exfat_chain_set(ec: &clu, dir: sbi->root_dir, size: 0, ALLOC_FAT_CHAIN);
1268
1269 while (clu.dir != EXFAT_EOF_CLUSTER) {
1270 for (i = 0; i < sbi->dentries_per_clu; i++, dentry++) {
1271 ep = exfat_get_dentry(sb, p_dir: &clu, entry: i, bh: &bh);
1272 if (!ep)
1273 return -EIO;
1274
1275 type = exfat_get_entry_type(ep);
1276 if (hint_femp.eidx == EXFAT_HINT_NONE) {
1277 if (type == TYPE_DELETED || type == TYPE_UNUSED) {
1278 hint_femp.cur = clu;
1279 hint_femp.eidx = dentry;
1280 hint_femp.count = 1;
1281 }
1282 }
1283
1284 if (type == TYPE_UNUSED) {
1285 brelse(bh);
1286 goto not_found;
1287 }
1288
1289 if (type != TYPE_VOLUME) {
1290 brelse(bh);
1291 continue;
1292 }
1293
1294 memset(es, 0, sizeof(*es));
1295 es->sb = sb;
1296 es->bh = es->__bh;
1297 es->bh[0] = bh;
1298 es->num_bh = 1;
1299 es->start_off = EXFAT_DEN_TO_B(i) % sb->s_blocksize;
1300
1301 return 0;
1302 }
1303
1304 if (exfat_get_next_cluster(sb, &(clu.dir)))
1305 return -EIO;
1306 }
1307
1308not_found:
1309 if (hint_femp.eidx == EXFAT_HINT_NONE) {
1310 hint_femp.cur.dir = EXFAT_EOF_CLUSTER;
1311 hint_femp.eidx = dentry;
1312 hint_femp.count = 0;
1313 }
1314
1315 ei->hint_femp = hint_femp;
1316
1317 return -ENOENT;
1318}
1319
1320int exfat_read_volume_label(struct super_block *sb, struct exfat_uni_name *label_out)
1321{
1322 int ret, i;
1323 struct exfat_sb_info *sbi = EXFAT_SB(sb);
1324 struct exfat_entry_set_cache es;
1325 struct exfat_dentry *ep;
1326
1327 mutex_lock(&sbi->s_lock);
1328
1329 memset(label_out, 0, sizeof(*label_out));
1330 ret = exfat_get_volume_label_dentry(sb, es: &es);
1331 if (ret < 0) {
1332 /*
1333 * ENOENT signifies that a volume label dentry doesn't exist
1334 * We will treat this as an empty volume label and not fail.
1335 */
1336 if (ret == -ENOENT)
1337 ret = 0;
1338
1339 goto unlock;
1340 }
1341
1342 ep = exfat_get_dentry_cached(es: &es, num: 0);
1343 label_out->name_len = ep->dentry.volume_label.char_count;
1344 if (label_out->name_len > EXFAT_VOLUME_LABEL_LEN) {
1345 ret = -EIO;
1346 exfat_put_dentry_set(es: &es, sync: false);
1347 goto unlock;
1348 }
1349
1350 for (i = 0; i < label_out->name_len; i++)
1351 label_out->name[i] = le16_to_cpu(ep->dentry.volume_label.volume_label[i]);
1352
1353 exfat_put_dentry_set(es: &es, sync: false);
1354unlock:
1355 mutex_unlock(lock: &sbi->s_lock);
1356 return ret;
1357}
1358
1359int exfat_write_volume_label(struct super_block *sb,
1360 struct exfat_uni_name *label)
1361{
1362 int ret, i;
1363 struct exfat_sb_info *sbi = EXFAT_SB(sb);
1364 struct inode *root_inode = sb->s_root->d_inode;
1365 struct exfat_entry_set_cache es;
1366 struct exfat_chain clu;
1367 struct exfat_dentry *ep;
1368
1369 if (label->name_len > EXFAT_VOLUME_LABEL_LEN)
1370 return -EINVAL;
1371
1372 mutex_lock(&sbi->s_lock);
1373
1374 ret = exfat_get_volume_label_dentry(sb, es: &es);
1375 if (ret == -ENOENT) {
1376 if (label->name_len == 0) {
1377 /* No volume label dentry, no need to clear */
1378 ret = 0;
1379 goto unlock;
1380 }
1381
1382 ret = exfat_find_empty_entry(inode: root_inode, p_dir: &clu, num_entries: 1, es: &es);
1383 }
1384
1385 if (ret < 0)
1386 goto unlock;
1387
1388 ep = exfat_get_dentry_cached(es: &es, num: 0);
1389
1390 if (label->name_len == 0 && ep->dentry.volume_label.char_count == 0) {
1391 /* volume label had been cleared */
1392 exfat_put_dentry_set(es: &es, sync: 0);
1393 goto unlock;
1394 }
1395
1396 memset(ep, 0, sizeof(*ep));
1397 ep->type = EXFAT_VOLUME;
1398
1399 for (i = 0; i < label->name_len; i++)
1400 ep->dentry.volume_label.volume_label[i] =
1401 cpu_to_le16(label->name[i]);
1402
1403 ep->dentry.volume_label.char_count = label->name_len;
1404 es.modified = true;
1405
1406 ret = exfat_put_dentry_set(es: &es, IS_DIRSYNC(root_inode));
1407
1408unlock:
1409 mutex_unlock(lock: &sbi->s_lock);
1410 return ret;
1411}
1412

source code of linux/fs/exfat/dir.c