dir.c

   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, 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, i);
  51
  52		/* end of name entry */
  53		if (exfat_get_entry_type(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, 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(&dir, ei->start_clu,
  86		EXFAT_B_TO_CLU(i_size_read(inode), sbi), 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(&clu, &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, &clu, i, &bh);
 119			if (!ep)
 120				return -EIO;
 121
 122			type = exfat_get_entry_type(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, &clu, i,
 138				uni_name.name);
 139			if (err) {
 140				brelse(bh);
 141				continue;
 142			}
 143			exfat_utf16_to_nls(sb, &uni_name,
 144				dir_entry->namebuf.lfn,
 145				dir_entry->namebuf.lfnbuf_len);
 146			brelse(bh);
 147
 148			ep = exfat_get_dentry(sb, &clu, i + 1, &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(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, &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(&EXFAT_SB(sb)->s_lock);
 271	if (!dir_emit(ctx, nb->lfn, strlen(nb->lfn), inum,
 272			(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(&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(clu, EXFAT_EOF_CLUSTER, 0, ALLOC_NO_FAT_CHAIN);
 308
 309	ret = exfat_alloc_cluster(inode, 1, clu, IS_DIRSYNC(inode));
 310	if (ret)
 311		return ret;
 312
 313	return exfat_zeroed_cluster(inode, 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			&ep->dentry.file.create_tz,
 447			&ep->dentry.file.create_time,
 448			&ep->dentry.file.create_date,
 449			&ep->dentry.file.create_time_cs);
 450	exfat_set_entry_time(sbi, ts,
 451			&ep->dentry.file.modify_tz,
 452			&ep->dentry.file.modify_time,
 453			&ep->dentry.file.modify_date,
 454			&ep->dentry.file.modify_time_cs);
 455	exfat_set_entry_time(sbi, ts,
 456			&ep->dentry.file.access_tz,
 457			&ep->dentry.file.access_time,
 458			&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(&dir, start_clu,
 479			EXFAT_B_TO_CLU_ROUND_UP(size, EXFAT_SB(sb)),
 480			flags);
 481	exfat_free_cluster(inode, &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, 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, 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, i);
 534		chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
 535					     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(es->bh, es->num_bh, sync);
 549
 550	for (i = 0; i < es->num_bh; i++)
 551		if (err)
 552			bforget(es->bh[i]);
 553		else
 554			brelse(es->bh[i]);
 555
 556	if (IS_DYNAMIC_ES(es))
 557		kfree(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, off, &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, 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, sec);
 649	if (!bh || !buffer_uptodate(bh)) {
 650		unsigned int i;
 651
 652		for (i = 0; i < ra_count; i++)
 653			sb_breadahead(sb, (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, &sec, &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, 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, &sec, &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, 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, clu);
 821		} else {
 822			sec++;
 823		}
 824
 825		bh = sb_bread(sb, 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, 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, i);
 853		if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
 854			goto put_es;
 855	}
 856	return 0;
 857
 858put_es:
 859	exfat_put_dentry_set(es, 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, 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, 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, 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(&clu, 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(&ei->hint_femp);
1020
1021rewind:
1022	order = 0;
1023	step = DIRENT_STEP_FILE;
1024	exfat_reset_empty_hint(&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, &clu, i, &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, &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(&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, entry_uniname);
1105				name_len += len;
1106
1107				unichar = *(uniname+len);
1108				*(uniname+len) = 0x0;
1109
1110				if (exfat_uniname_ncmp(sb, uniname,
1111					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(&clu, 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, &clu, i, &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(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(&clu, sbi->root_dir, 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, &clu, i, &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);
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, 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, 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, false);
1354unlock:
1355	mutex_unlock(&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);
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(root_inode, &clu, 1, &es);
1383	}
1384
1385	if (ret < 0)
1386		goto unlock;
1387
1388	ep = exfat_get_dentry_cached(&es, 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, 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, IS_DIRSYNC(root_inode));
1407
1408unlock:
1409	mutex_unlock(&sbi->s_lock);
1410	return ret;
1411}