dir.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/fat/dir.c
   4 *
   5 *  directory handling functions for fat-based filesystems
   6 *
   7 *  Written 1992,1993 by Werner Almesberger
   8 *
   9 *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
  10 *
  11 *  VFAT extensions by Gordon Chaffee <chaffee@plateau.cs.berkeley.edu>
  12 *  Merged with msdos fs by Henrik Storner <storner@osiris.ping.dk>
  13 *  Rewritten for constant inumbers. Plugged buffer overrun in readdir(). AV
  14 *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
  15 */
  16
  17#include <linux/slab.h>
  18#include <linux/compat.h>
  19#include <linux/uaccess.h>
  20#include <linux/iversion.h>
  21#include "fat.h"
  22
  23/*
  24 * Maximum buffer size of short name.
  25 * [(MSDOS_NAME + '.') * max one char + nul]
  26 * For msdos style, ['.' (hidden) + MSDOS_NAME + '.' + nul]
  27 */
  28#define FAT_MAX_SHORT_SIZE	((MSDOS_NAME + 1) * NLS_MAX_CHARSET_SIZE + 1)
  29/*
  30 * Maximum buffer size of unicode chars from slots.
  31 * [(max longname slots * 13 (size in a slot) + nul) * sizeof(wchar_t)]
  32 */
  33#define FAT_MAX_UNI_CHARS	((MSDOS_SLOTS - 1) * 13 + 1)
  34#define FAT_MAX_UNI_SIZE	(FAT_MAX_UNI_CHARS * sizeof(wchar_t))
  35
  36static inline unsigned char fat_tolower(unsigned char c)
  37{
  38	return ((c >= 'A') && (c <= 'Z')) ? c+32 : c;
  39}
  40
  41static inline loff_t fat_make_i_pos(struct super_block *sb,
  42				    struct buffer_head *bh,
  43				    struct msdos_dir_entry *de)
  44{
  45	return ((loff_t)bh->b_blocknr << MSDOS_SB(sb)->dir_per_block_bits)
  46		| (de - (struct msdos_dir_entry *)bh->b_data);
  47}
  48
  49static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
  50				     sector_t phys)
  51{
  52	struct super_block *sb = dir->i_sb;
  53	struct msdos_sb_info *sbi = MSDOS_SB(sb);
  54	struct buffer_head *bh;
  55	int sec;
  56
  57	/* This is not a first sector of cluster, or sec_per_clus == 1 */
  58	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
  59		return;
  60	/* root dir of FAT12/FAT16 */
  61	if (!is_fat32(sbi) && (dir->i_ino == MSDOS_ROOT_INO))
  62		return;
  63
  64	bh = sb_find_get_block(sb, phys);
  65	if (bh == NULL || !buffer_uptodate(bh)) {
  66		for (sec = 0; sec < sbi->sec_per_clus; sec++)
  67			sb_breadahead(sb, phys + sec);
  68	}
  69	brelse(bh);
  70}
  71
  72/* Returns the inode number of the directory entry at offset pos. If bh is
  73   non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
  74   returned in bh.
  75   AV. Most often we do it item-by-item. Makes sense to optimize.
  76   AV. OK, there we go: if both bh and de are non-NULL we assume that we just
  77   AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
  78   AV. It's done in fat_get_entry() (inlined), here the slow case lives.
  79   AV. Additionally, when we return -1 (i.e. reached the end of directory)
  80   AV. we make bh NULL.
  81 */
  82static int fat__get_entry(struct inode *dir, loff_t *pos,
  83			  struct buffer_head **bh, struct msdos_dir_entry **de)
  84{
  85	struct super_block *sb = dir->i_sb;
  86	sector_t phys, iblock;
  87	unsigned long mapped_blocks;
  88	int err, offset;
  89
  90next:
  91	brelse(*bh);
  92	*bh = NULL;
  93	iblock = *pos >> sb->s_blocksize_bits;
  94	err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0, false);
  95	if (err || !phys)
  96		return -1;	/* beyond EOF or error */
  97
  98	fat_dir_readahead(dir, iblock, phys);
  99
 100	*bh = sb_bread(sb, phys);
 101	if (*bh == NULL) {
 102		fat_msg_ratelimit(sb, KERN_ERR,
 103			"Directory bread(block %llu) failed", (llu)phys);
 104		/* skip this block */
 105		*pos = (iblock + 1) << sb->s_blocksize_bits;
 106		goto next;
 107	}
 108
 109	offset = *pos & (sb->s_blocksize - 1);
 110	*pos += sizeof(struct msdos_dir_entry);
 111	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
 112
 113	return 0;
 114}
 115
 116static inline int fat_get_entry(struct inode *dir, loff_t *pos,
 117				struct buffer_head **bh,
 118				struct msdos_dir_entry **de)
 119{
 120	/* Fast stuff first */
 121	if (*bh && *de &&
 122	   (*de - (struct msdos_dir_entry *)(*bh)->b_data) <
 123				MSDOS_SB(dir->i_sb)->dir_per_block - 1) {
 124		*pos += sizeof(struct msdos_dir_entry);
 125		(*de)++;
 126		return 0;
 127	}
 128	return fat__get_entry(dir, pos, bh, de);
 129}
 130
 131/*
 132 * Convert Unicode 16 to UTF-8, translated Unicode, or ASCII.
 133 * If uni_xlate is enabled and we can't get a 1:1 conversion, use a
 134 * colon as an escape character since it is normally invalid on the vfat
 135 * filesystem. The following four characters are the hexadecimal digits
 136 * of Unicode value. This lets us do a full dump and restore of Unicode
 137 * filenames. We could get into some trouble with long Unicode names,
 138 * but ignore that right now.
 139 * Ahem... Stack smashing in ring 0 isn't fun. Fixed.
 140 */
 141static int uni16_to_x8(struct super_block *sb, unsigned char *ascii,
 142		       const wchar_t *uni, int len, struct nls_table *nls)
 143{
 144	int uni_xlate = MSDOS_SB(sb)->options.unicode_xlate;
 145	const wchar_t *ip;
 146	wchar_t ec;
 147	unsigned char *op;
 148	int charlen;
 149
 150	ip = uni;
 151	op = ascii;
 152
 153	while (*ip && ((len - NLS_MAX_CHARSET_SIZE) > 0)) {
 154		ec = *ip++;
 155		charlen = nls->uni2char(ec, op, NLS_MAX_CHARSET_SIZE);
 156		if (charlen > 0) {
 157			op += charlen;
 158			len -= charlen;
 159		} else {
 160			if (uni_xlate == 1) {
 161				*op++ = ':';
 162				op = hex_byte_pack(op, ec >> 8);
 163				op = hex_byte_pack(op, ec);
 164				len -= 5;
 165			} else {
 166				*op++ = '?';
 167				len--;
 168			}
 169		}
 170	}
 171
 172	if (unlikely(*ip)) {
 173		fat_msg(sb, KERN_WARNING,
 174			"filename was truncated while converting.");
 175	}
 176
 177	*op = 0;
 178	return op - ascii;
 179}
 180
 181static inline int fat_uni_to_x8(struct super_block *sb, const wchar_t *uni,
 182				unsigned char *buf, int size)
 183{
 184	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 185	if (sbi->options.utf8)
 186		return utf16s_to_utf8s(uni, FAT_MAX_UNI_CHARS,
 187				UTF16_HOST_ENDIAN, buf, size);
 188	else
 189		return uni16_to_x8(sb, buf, uni, size, sbi->nls_io);
 190}
 191
 192static inline int
 193fat_short2uni(struct nls_table *t, unsigned char *c, int clen, wchar_t *uni)
 194{
 195	int charlen;
 196
 197	charlen = t->char2uni(c, clen, uni);
 198	if (charlen < 0) {
 199		*uni = 0x003f;	/* a question mark */
 200		charlen = 1;
 201	}
 202	return charlen;
 203}
 204
 205static inline int
 206fat_short2lower_uni(struct nls_table *t, unsigned char *c,
 207		    int clen, wchar_t *uni)
 208{
 209	int charlen;
 210	wchar_t wc;
 211
 212	charlen = t->char2uni(c, clen, &wc);
 213	if (charlen < 0) {
 214		*uni = 0x003f;	/* a question mark */
 215		charlen = 1;
 216	} else if (charlen <= 1) {
 217		unsigned char nc = t->charset2lower[*c];
 218
 219		if (!nc)
 220			nc = *c;
 221
 222		charlen = t->char2uni(&nc, 1, uni);
 223		if (charlen < 0) {
 224			*uni = 0x003f;	/* a question mark */
 225			charlen = 1;
 226		}
 227	} else
 228		*uni = wc;
 229
 230	return charlen;
 231}
 232
 233static inline int
 234fat_shortname2uni(struct nls_table *nls, unsigned char *buf, int buf_size,
 235		  wchar_t *uni_buf, unsigned short opt, int lower)
 236{
 237	int len = 0;
 238
 239	if (opt & VFAT_SFN_DISPLAY_LOWER)
 240		len =  fat_short2lower_uni(nls, buf, buf_size, uni_buf);
 241	else if (opt & VFAT_SFN_DISPLAY_WIN95)
 242		len = fat_short2uni(nls, buf, buf_size, uni_buf);
 243	else if (opt & VFAT_SFN_DISPLAY_WINNT) {
 244		if (lower)
 245			len = fat_short2lower_uni(nls, buf, buf_size, uni_buf);
 246		else
 247			len = fat_short2uni(nls, buf, buf_size, uni_buf);
 248	} else
 249		len = fat_short2uni(nls, buf, buf_size, uni_buf);
 250
 251	return len;
 252}
 253
 254static inline int fat_name_match(struct msdos_sb_info *sbi,
 255				 const unsigned char *a, int a_len,
 256				 const unsigned char *b, int b_len)
 257{
 258	if (a_len != b_len)
 259		return 0;
 260
 261	if (sbi->options.name_check != 's')
 262		return !nls_strnicmp(sbi->nls_io, a, b, a_len);
 263	else
 264		return !memcmp(a, b, a_len);
 265}
 266
 267enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };
 268
 269/**
 270 * fat_parse_long - Parse extended directory entry.
 271 *
 272 * @dir: Pointer to the inode that represents the directory.
 273 * @pos: On input, contains the starting position to read from.
 274 *       On output, updated with the new position.
 275 * @bh: Pointer to the buffer head that may be used for reading directory
 276 *	 entries. May be updated.
 277 * @de: On input, points to the current directory entry.
 278 *      On output, points to the next directory entry.
 279 * @unicode: Pointer to a buffer where the parsed Unicode long filename will be
 280 *	      stored.
 281 * @nr_slots: Pointer to a variable that will store the number of longname
 282 *	       slots found.
 283 *
 284 * This function returns zero on success, negative value on error, or one of
 285 * the following:
 286 *
 287 * %PARSE_INVALID - Directory entry is invalid.
 288 * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
 289 * %PARSE_EOF - Directory has no more entries.
 290 */
 291static int fat_parse_long(struct inode *dir, loff_t *pos,
 292			  struct buffer_head **bh, struct msdos_dir_entry **de,
 293			  wchar_t **unicode, unsigned char *nr_slots)
 294{
 295	struct msdos_dir_slot *ds;
 296	unsigned char id, slot, slots, alias_checksum;
 297
 298	if (!*unicode) {
 299		*unicode = __getname();
 300		if (!*unicode) {
 301			brelse(*bh);
 302			return -ENOMEM;
 303		}
 304	}
 305parse_long:
 306	ds = (struct msdos_dir_slot *)*de;
 307	id = ds->id;
 308	if (!(id & 0x40))
 309		return PARSE_INVALID;
 310	slots = id & ~0x40;
 311	if (slots > 20 || !slots)	/* ceil(256 * 2 / 26) */
 312		return PARSE_INVALID;
 313	*nr_slots = slots;
 314	alias_checksum = ds->alias_checksum;
 315
 316	slot = slots;
 317	while (1) {
 318		int offset;
 319
 320		slot--;
 321		offset = slot * 13;
 322		fat16_towchar(*unicode + offset, ds->name0_4, 5);
 323		fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
 324		fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);
 325
 326		if (ds->id & 0x40)
 327			(*unicode)[offset + 13] = 0;
 328		if (fat_get_entry(dir, pos, bh, de) < 0)
 329			return PARSE_EOF;
 330		if (slot == 0)
 331			break;
 332		ds = (struct msdos_dir_slot *)*de;
 333		if (ds->attr != ATTR_EXT)
 334			return PARSE_NOT_LONGNAME;
 335		if ((ds->id & ~0x40) != slot)
 336			goto parse_long;
 337		if (ds->alias_checksum != alias_checksum)
 338			goto parse_long;
 339	}
 340	if ((*de)->name[0] == DELETED_FLAG)
 341		return PARSE_INVALID;
 342	if ((*de)->attr == ATTR_EXT)
 343		goto parse_long;
 344	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
 345		return PARSE_INVALID;
 346	if (fat_checksum((*de)->name) != alias_checksum)
 347		*nr_slots = 0;
 348
 349	return 0;
 350}
 351
 352/**
 353 * fat_parse_short - Parse MS-DOS (short) directory entry.
 354 * @sb:		superblock
 355 * @de:		directory entry to parse
 356 * @name:	FAT_MAX_SHORT_SIZE array in which to place extracted name
 357 * @dot_hidden:	Nonzero == prepend '.' to names with ATTR_HIDDEN
 358 *
 359 * Returns the number of characters extracted into 'name'.
 360 */
 361static int fat_parse_short(struct super_block *sb,
 362			   const struct msdos_dir_entry *de,
 363			   unsigned char *name, int dot_hidden)
 364{
 365	const struct msdos_sb_info *sbi = MSDOS_SB(sb);
 366	int isvfat = sbi->options.isvfat;
 367	int nocase = sbi->options.nocase;
 368	unsigned short opt_shortname = sbi->options.shortname;
 369	struct nls_table *nls_disk = sbi->nls_disk;
 370	wchar_t uni_name[14];
 371	unsigned char c, work[MSDOS_NAME];
 372	unsigned char *ptname = name;
 373	int chi, chl, i, j, k;
 374	int dotoffset = 0;
 375	int name_len = 0, uni_len = 0;
 376
 377	if (!isvfat && dot_hidden && (de->attr & ATTR_HIDDEN)) {
 378		*ptname++ = '.';
 379		dotoffset = 1;
 380	}
 381
 382	memcpy(work, de->name, sizeof(work));
 383	/* For an explanation of the special treatment of 0x05 in
 384	 * filenames, see msdos_format_name in namei_msdos.c
 385	 */
 386	if (work[0] == 0x05)
 387		work[0] = 0xE5;
 388
 389	/* Filename */
 390	for (i = 0, j = 0; i < 8;) {
 391		c = work[i];
 392		if (!c)
 393			break;
 394		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
 395					&uni_name[j++], opt_shortname,
 396					de->lcase & CASE_LOWER_BASE);
 397		if (chl <= 1) {
 398			if (!isvfat)
 399				ptname[i] = nocase ? c : fat_tolower(c);
 400			i++;
 401			if (c != ' ') {
 402				name_len = i;
 403				uni_len  = j;
 404			}
 405		} else {
 406			uni_len = j;
 407			if (isvfat)
 408				i += min(chl, 8-i);
 409			else {
 410				for (chi = 0; chi < chl && i < 8; chi++, i++)
 411					ptname[i] = work[i];
 412			}
 413			if (chl)
 414				name_len = i;
 415		}
 416	}
 417
 418	i = name_len;
 419	j = uni_len;
 420	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
 421	if (!isvfat)
 422		ptname[i] = '.';
 423	i++;
 424
 425	/* Extension */
 426	for (k = 8; k < MSDOS_NAME;) {
 427		c = work[k];
 428		if (!c)
 429			break;
 430		chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
 431					&uni_name[j++], opt_shortname,
 432					de->lcase & CASE_LOWER_EXT);
 433		if (chl <= 1) {
 434			k++;
 435			if (!isvfat)
 436				ptname[i] = nocase ? c : fat_tolower(c);
 437			i++;
 438			if (c != ' ') {
 439				name_len = i;
 440				uni_len  = j;
 441			}
 442		} else {
 443			uni_len = j;
 444			if (isvfat) {
 445				int offset = min(chl, MSDOS_NAME-k);
 446				k += offset;
 447				i += offset;
 448			} else {
 449				for (chi = 0; chi < chl && k < MSDOS_NAME;
 450				     chi++, i++, k++) {
 451						ptname[i] = work[k];
 452				}
 453			}
 454			if (chl)
 455				name_len = i;
 456		}
 457	}
 458
 459	if (name_len > 0) {
 460		name_len += dotoffset;
 461
 462		if (sbi->options.isvfat) {
 463			uni_name[uni_len] = 0x0000;
 464			name_len = fat_uni_to_x8(sb, uni_name, name,
 465						 FAT_MAX_SHORT_SIZE);
 466		}
 467	}
 468
 469	return name_len;
 470}
 471
 472/*
 473 * Return values: negative -> error/not found, 0 -> found.
 474 */
 475int fat_search_long(struct inode *inode, const unsigned char *name,
 476		    int name_len, struct fat_slot_info *sinfo)
 477{
 478	struct super_block *sb = inode->i_sb;
 479	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 480	struct buffer_head *bh = NULL;
 481	struct msdos_dir_entry *de;
 482	unsigned char nr_slots;
 483	wchar_t *unicode = NULL;
 484	unsigned char bufname[FAT_MAX_SHORT_SIZE];
 485	loff_t cpos = 0;
 486	int err, len;
 487
 488	err = -ENOENT;
 489	while (1) {
 490		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
 491			goto end_of_dir;
 492parse_record:
 493		nr_slots = 0;
 494		if (de->name[0] == DELETED_FLAG)
 495			continue;
 496		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
 497			continue;
 498		if (de->attr != ATTR_EXT && IS_FREE(de->name))
 499			continue;
 500		if (de->attr == ATTR_EXT) {
 501			int status = fat_parse_long(inode, &cpos, &bh, &de,
 502						    &unicode, &nr_slots);
 503			if (status < 0) {
 504				err = status;
 505				goto end_of_dir;
 506			} else if (status == PARSE_INVALID)
 507				continue;
 508			else if (status == PARSE_NOT_LONGNAME)
 509				goto parse_record;
 510			else if (status == PARSE_EOF)
 511				goto end_of_dir;
 512		}
 513
 514		/* Never prepend '.' to hidden files here.
 515		 * That is done only for msdos mounts (and only when
 516		 * 'dotsOK=yes'); if we are executing here, it is in the
 517		 * context of a vfat mount.
 518		 */
 519		len = fat_parse_short(sb, de, bufname, 0);
 520		if (len == 0)
 521			continue;
 522
 523		/* Compare shortname */
 524		if (fat_name_match(sbi, name, name_len, bufname, len))
 525			goto found;
 526
 527		if (nr_slots) {
 528			void *longname = unicode + FAT_MAX_UNI_CHARS;
 529			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
 530
 531			/* Compare longname */
 532			len = fat_uni_to_x8(sb, unicode, longname, size);
 533			if (fat_name_match(sbi, name, name_len, longname, len))
 534				goto found;
 535		}
 536	}
 537
 538found:
 539	nr_slots++;	/* include the de */
 540	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
 541	sinfo->nr_slots = nr_slots;
 542	sinfo->de = de;
 543	sinfo->bh = bh;
 544	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
 545	err = 0;
 546end_of_dir:
 547	if (unicode)
 548		__putname(unicode);
 549
 550	return err;
 551}
 552EXPORT_SYMBOL_GPL(fat_search_long);
 553
 554struct fat_ioctl_filldir_callback {
 555	struct dir_context ctx;
 556	void __user *dirent;
 557	int result;
 558	/* for dir ioctl */
 559	const char *longname;
 560	int long_len;
 561	const char *shortname;
 562	int short_len;
 563};
 564
 565static int __fat_readdir(struct inode *inode, struct file *file,
 566			 struct dir_context *ctx, int short_only,
 567			 struct fat_ioctl_filldir_callback *both)
 568{
 569	struct super_block *sb = inode->i_sb;
 570	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 571	struct buffer_head *bh;
 572	struct msdos_dir_entry *de;
 573	unsigned char nr_slots;
 574	wchar_t *unicode = NULL;
 575	unsigned char bufname[FAT_MAX_SHORT_SIZE];
 576	int isvfat = sbi->options.isvfat;
 577	const char *fill_name = NULL;
 578	int fake_offset = 0;
 579	loff_t cpos;
 580	int short_len = 0, fill_len = 0;
 581	int ret = 0;
 582
 583	mutex_lock(&sbi->s_lock);
 584
 585	cpos = ctx->pos;
 586	/* Fake . and .. for the root directory. */
 587	if (inode->i_ino == MSDOS_ROOT_INO) {
 588		if (!dir_emit_dots(file, ctx))
 589			goto out;
 590		if (ctx->pos == 2) {
 591			fake_offset = 1;
 592			cpos = 0;
 593		}
 594	}
 595	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
 596		ret = -ENOENT;
 597		goto out;
 598	}
 599
 600	bh = NULL;
 601get_new:
 602	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
 603		goto end_of_dir;
 604parse_record:
 605	nr_slots = 0;
 606	/*
 607	 * Check for long filename entry, but if short_only, we don't
 608	 * need to parse long filename.
 609	 */
 610	if (isvfat && !short_only) {
 611		if (de->name[0] == DELETED_FLAG)
 612			goto record_end;
 613		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
 614			goto record_end;
 615		if (de->attr != ATTR_EXT && IS_FREE(de->name))
 616			goto record_end;
 617	} else {
 618		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
 619			goto record_end;
 620	}
 621
 622	if (isvfat && de->attr == ATTR_EXT) {
 623		int status = fat_parse_long(inode, &cpos, &bh, &de,
 624					    &unicode, &nr_slots);
 625		if (status < 0) {
 626			bh = NULL;
 627			ret = status;
 628			goto end_of_dir;
 629		} else if (status == PARSE_INVALID)
 630			goto record_end;
 631		else if (status == PARSE_NOT_LONGNAME)
 632			goto parse_record;
 633		else if (status == PARSE_EOF)
 634			goto end_of_dir;
 635
 636		if (nr_slots) {
 637			void *longname = unicode + FAT_MAX_UNI_CHARS;
 638			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
 639			int len = fat_uni_to_x8(sb, unicode, longname, size);
 640
 641			fill_name = longname;
 642			fill_len = len;
 643			/* !both && !short_only, so we don't need shortname. */
 644			if (!both)
 645				goto start_filldir;
 646
 647			short_len = fat_parse_short(sb, de, bufname,
 648						    sbi->options.dotsOK);
 649			if (short_len == 0)
 650				goto record_end;
 651			/* hack for fat_ioctl_filldir() */
 652			both->longname = fill_name;
 653			both->long_len = fill_len;
 654			both->shortname = bufname;
 655			both->short_len = short_len;
 656			fill_name = NULL;
 657			fill_len = 0;
 658			goto start_filldir;
 659		}
 660	}
 661
 662	short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
 663	if (short_len == 0)
 664		goto record_end;
 665
 666	fill_name = bufname;
 667	fill_len = short_len;
 668
 669start_filldir:
 670	ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
 671	if (fake_offset && ctx->pos < 2)
 672		ctx->pos = 2;
 673
 674	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
 675		if (!dir_emit_dot(file, ctx))
 676			goto fill_failed;
 677	} else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
 678		if (!dir_emit_dotdot(file, ctx))
 679			goto fill_failed;
 680	} else {
 681		unsigned long inum;
 682		loff_t i_pos = fat_make_i_pos(sb, bh, de);
 683		struct inode *tmp = fat_iget(sb, i_pos);
 684		if (tmp) {
 685			inum = tmp->i_ino;
 686			iput(tmp);
 687		} else
 688			inum = iunique(sb, MSDOS_ROOT_INO);
 689		if (!dir_emit(ctx, fill_name, fill_len, inum,
 690			    (de->attr & ATTR_DIR) ? DT_DIR : DT_REG))
 691			goto fill_failed;
 692	}
 693
 694record_end:
 695	fake_offset = 0;
 696	ctx->pos = cpos;
 697	goto get_new;
 698
 699end_of_dir:
 700	if (fake_offset && cpos < 2)
 701		ctx->pos = 2;
 702	else
 703		ctx->pos = cpos;
 704fill_failed:
 705	brelse(bh);
 706	if (unicode)
 707		__putname(unicode);
 708out:
 709	mutex_unlock(&sbi->s_lock);
 710
 711	return ret;
 712}
 713
 714static int fat_readdir(struct file *file, struct dir_context *ctx)
 715{
 716	return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
 717}
 718
 719#define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
 720static bool func(struct dir_context *ctx, const char *name, int name_len,  \
 721			     loff_t offset, u64 ino, unsigned int d_type)  \
 722{									   \
 723	struct fat_ioctl_filldir_callback *buf =			   \
 724		container_of(ctx, struct fat_ioctl_filldir_callback, ctx); \
 725	struct dirent_type __user *d1 = buf->dirent;			   \
 726	struct dirent_type __user *d2 = d1 + 1;				   \
 727									   \
 728	if (buf->result)						   \
 729		return false;						   \
 730	buf->result++;							   \
 731									   \
 732	if (name != NULL) {						   \
 733		/* dirent has only short name */			   \
 734		if (name_len >= sizeof(d1->d_name))			   \
 735			name_len = sizeof(d1->d_name) - 1;		   \
 736									   \
 737		if (put_user(0, &d2->d_name[0])			||	   \
 738		    put_user(0, &d2->d_reclen)			||	   \
 739		    copy_to_user(d1->d_name, name, name_len)	||	   \
 740		    put_user(0, d1->d_name + name_len)		||	   \
 741		    put_user(name_len, &d1->d_reclen))			   \
 742			goto efault;					   \
 743	} else {							   \
 744		/* dirent has short and long name */			   \
 745		const char *longname = buf->longname;			   \
 746		int long_len = buf->long_len;				   \
 747		const char *shortname = buf->shortname;			   \
 748		int short_len = buf->short_len;				   \
 749									   \
 750		if (long_len >= sizeof(d1->d_name))			   \
 751			long_len = sizeof(d1->d_name) - 1;		   \
 752		if (short_len >= sizeof(d1->d_name))			   \
 753			short_len = sizeof(d1->d_name) - 1;		   \
 754									   \
 755		if (copy_to_user(d2->d_name, longname, long_len)	|| \
 756		    put_user(0, d2->d_name + long_len)			|| \
 757		    put_user(long_len, &d2->d_reclen)			|| \
 758		    put_user(ino, &d2->d_ino)				|| \
 759		    put_user(offset, &d2->d_off)			|| \
 760		    copy_to_user(d1->d_name, shortname, short_len)	|| \
 761		    put_user(0, d1->d_name + short_len)			|| \
 762		    put_user(short_len, &d1->d_reclen))			   \
 763			goto efault;					   \
 764	}								   \
 765	return true;							   \
 766efault:									   \
 767	buf->result = -EFAULT;						   \
 768	return false;							   \
 769}
 770
 771FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
 772
 773static int fat_ioctl_readdir(struct inode *inode, struct file *file,
 774			     void __user *dirent, filldir_t filldir,
 775			     int short_only, int both)
 776{
 777	struct fat_ioctl_filldir_callback buf = {
 778		.ctx.actor = filldir,
 779		.dirent = dirent
 780	};
 781	int ret;
 782
 783	buf.dirent = dirent;
 784	buf.result = 0;
 785	inode_lock_shared(inode);
 786	buf.ctx.pos = file->f_pos;
 787	ret = -ENOENT;
 788	if (!IS_DEADDIR(inode)) {
 789		ret = __fat_readdir(inode, file, &buf.ctx,
 790				    short_only, both ? &buf : NULL);
 791		file->f_pos = buf.ctx.pos;
 792	}
 793	inode_unlock_shared(inode);
 794	if (ret >= 0)
 795		ret = buf.result;
 796	return ret;
 797}
 798
 799static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
 800			  unsigned long arg)
 801{
 802	struct inode *inode = file_inode(filp);
 803	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
 804	int short_only, both;
 805
 806	switch (cmd) {
 807	case VFAT_IOCTL_READDIR_SHORT:
 808		short_only = 1;
 809		both = 0;
 810		break;
 811	case VFAT_IOCTL_READDIR_BOTH:
 812		short_only = 0;
 813		both = 1;
 814		break;
 815	default:
 816		return fat_generic_ioctl(filp, cmd, arg);
 817	}
 818
 819	/*
 820	 * Yes, we don't need this put_user() absolutely. However old
 821	 * code didn't return the right value. So, app use this value,
 822	 * in order to check whether it is EOF.
 823	 */
 824	if (put_user(0, &d1->d_reclen))
 825		return -EFAULT;
 826
 827	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
 828				 short_only, both);
 829}
 830
 831#ifdef CONFIG_COMPAT
 832#define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
 833#define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])
 834
 835FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
 836
 837static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
 838				 unsigned long arg)
 839{
 840	struct inode *inode = file_inode(filp);
 841	struct compat_dirent __user *d1 = compat_ptr(arg);
 842	int short_only, both;
 843
 844	switch (cmd) {
 845	case VFAT_IOCTL_READDIR_SHORT32:
 846		short_only = 1;
 847		both = 0;
 848		break;
 849	case VFAT_IOCTL_READDIR_BOTH32:
 850		short_only = 0;
 851		both = 1;
 852		break;
 853	default:
 854		return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
 855	}
 856
 857	/*
 858	 * Yes, we don't need this put_user() absolutely. However old
 859	 * code didn't return the right value. So, app use this value,
 860	 * in order to check whether it is EOF.
 861	 */
 862	if (put_user(0, &d1->d_reclen))
 863		return -EFAULT;
 864
 865	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
 866				 short_only, both);
 867}
 868#endif /* CONFIG_COMPAT */
 869
 870const struct file_operations fat_dir_operations = {
 871	.llseek		= generic_file_llseek,
 872	.read		= generic_read_dir,
 873	.iterate_shared	= fat_readdir,
 874	.unlocked_ioctl	= fat_dir_ioctl,
 875#ifdef CONFIG_COMPAT
 876	.compat_ioctl	= fat_compat_dir_ioctl,
 877#endif
 878	.fsync		= fat_file_fsync,
 879};
 880
 881static int fat_get_short_entry(struct inode *dir, loff_t *pos,
 882			       struct buffer_head **bh,
 883			       struct msdos_dir_entry **de)
 884{
 885	while (fat_get_entry(dir, pos, bh, de) >= 0) {
 886		/* free entry or long name entry or volume label */
 887		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
 888			return 0;
 889	}
 890	return -ENOENT;
 891}
 892
 893/*
 894 * The ".." entry can not provide the "struct fat_slot_info" information
 895 * for inode, nor a usable i_pos. So, this function provides some information
 896 * only.
 897 *
 898 * Since this function walks through the on-disk inodes within a directory,
 899 * callers are responsible for taking any locks necessary to prevent the
 900 * directory from changing.
 901 */
 902int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
 903			 struct msdos_dir_entry **de)
 904{
 905	loff_t offset = 0;
 906
 907	*de = NULL;
 908	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
 909		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
 910			return 0;
 911	}
 912	return -ENOENT;
 913}
 914EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
 915
 916/* See if directory is empty */
 917int fat_dir_empty(struct inode *dir)
 918{
 919	struct buffer_head *bh;
 920	struct msdos_dir_entry *de;
 921	loff_t cpos;
 922	int result = 0;
 923
 924	bh = NULL;
 925	cpos = 0;
 926	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
 927		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
 928		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
 929			result = -ENOTEMPTY;
 930			break;
 931		}
 932	}
 933	brelse(bh);
 934	return result;
 935}
 936EXPORT_SYMBOL_GPL(fat_dir_empty);
 937
 938/*
 939 * fat_subdirs counts the number of sub-directories of dir. It can be run
 940 * on directories being created.
 941 */
 942int fat_subdirs(struct inode *dir)
 943{
 944	struct buffer_head *bh;
 945	struct msdos_dir_entry *de;
 946	loff_t cpos;
 947	int count = 0;
 948
 949	bh = NULL;
 950	cpos = 0;
 951	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
 952		if (de->attr & ATTR_DIR)
 953			count++;
 954	}
 955	brelse(bh);
 956	return count;
 957}
 958
 959/*
 960 * Scans a directory for a given file (name points to its formatted name).
 961 * Returns an error code or zero.
 962 */
 963int fat_scan(struct inode *dir, const unsigned char *name,
 964	     struct fat_slot_info *sinfo)
 965{
 966	struct super_block *sb = dir->i_sb;
 967
 968	sinfo->slot_off = 0;
 969	sinfo->bh = NULL;
 970	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
 971				   &sinfo->de) >= 0) {
 972		if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
 973			sinfo->slot_off -= sizeof(*sinfo->de);
 974			sinfo->nr_slots = 1;
 975			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
 976			return 0;
 977		}
 978	}
 979	return -ENOENT;
 980}
 981EXPORT_SYMBOL_GPL(fat_scan);
 982
 983/*
 984 * Scans a directory for a given logstart.
 985 * Returns an error code or zero.
 986 */
 987int fat_scan_logstart(struct inode *dir, int i_logstart,
 988		      struct fat_slot_info *sinfo)
 989{
 990	struct super_block *sb = dir->i_sb;
 991
 992	sinfo->slot_off = 0;
 993	sinfo->bh = NULL;
 994	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
 995				   &sinfo->de) >= 0) {
 996		if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
 997			sinfo->slot_off -= sizeof(*sinfo->de);
 998			sinfo->nr_slots = 1;
 999			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1000			return 0;
1001		}
1002	}
1003	return -ENOENT;
1004}
1005
1006static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
1007{
1008	struct super_block *sb = dir->i_sb;
1009	struct buffer_head *bh;
1010	struct msdos_dir_entry *de, *endp;
1011	int err = 0, orig_slots;
1012
1013	while (nr_slots) {
1014		bh = NULL;
1015		if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1016			err = -EIO;
1017			break;
1018		}
1019
1020		orig_slots = nr_slots;
1021		endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1022		while (nr_slots && de < endp) {
1023			de->name[0] = DELETED_FLAG;
1024			de++;
1025			nr_slots--;
1026		}
1027		mark_buffer_dirty_inode(bh, dir);
1028		if (IS_DIRSYNC(dir))
1029			err = sync_dirty_buffer(bh);
1030		brelse(bh);
1031		if (err)
1032			break;
1033
1034		/* pos is *next* de's position, so this does `- sizeof(de)' */
1035		pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1036	}
1037
1038	return err;
1039}
1040
1041int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1042{
1043	struct super_block *sb = dir->i_sb;
1044	struct msdos_dir_entry *de;
1045	struct buffer_head *bh;
1046	int err = 0, nr_slots;
1047
1048	/*
1049	 * First stage: Remove the shortname. By this, the directory
1050	 * entry is removed.
1051	 */
1052	nr_slots = sinfo->nr_slots;
1053	de = sinfo->de;
1054	sinfo->de = NULL;
1055	bh = sinfo->bh;
1056	sinfo->bh = NULL;
1057	while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1058		de->name[0] = DELETED_FLAG;
1059		de--;
1060		nr_slots--;
1061	}
1062	mark_buffer_dirty_inode(bh, dir);
1063	if (IS_DIRSYNC(dir))
1064		err = sync_dirty_buffer(bh);
1065	brelse(bh);
1066	if (err)
1067		return err;
1068	inode_inc_iversion(dir);
1069
1070	if (nr_slots) {
1071		/*
1072		 * Second stage: remove the remaining longname slots.
1073		 * (This directory entry is already removed, and so return
1074		 * the success)
1075		 */
1076		err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1077		if (err) {
1078			fat_msg(sb, KERN_WARNING,
1079			       "Couldn't remove the long name slots");
1080		}
1081	}
1082
1083	fat_truncate_time(dir, NULL, S_ATIME|S_MTIME);
1084	if (IS_DIRSYNC(dir))
1085		(void)fat_sync_inode(dir);
1086	else
1087		mark_inode_dirty(dir);
1088
1089	return 0;
1090}
1091EXPORT_SYMBOL_GPL(fat_remove_entries);
1092
1093static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1094			      struct buffer_head **bhs, int nr_bhs)
1095{
1096	struct super_block *sb = dir->i_sb;
1097	sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1098	int err, i, n;
1099
1100	/* Zeroing the unused blocks on this cluster */
1101	blknr += nr_used;
1102	n = nr_used;
1103	while (blknr < last_blknr) {
1104		bhs[n] = sb_getblk(sb, blknr);
1105		if (!bhs[n]) {
1106			err = -ENOMEM;
1107			goto error;
1108		}
1109		/* Avoid race with userspace read via bdev */
1110		lock_buffer(bhs[n]);
1111		memset(bhs[n]->b_data, 0, sb->s_blocksize);
1112		set_buffer_uptodate(bhs[n]);
1113		unlock_buffer(bhs[n]);
1114		mark_buffer_dirty_inode(bhs[n], dir);
1115
1116		n++;
1117		blknr++;
1118		if (n == nr_bhs) {
1119			if (IS_DIRSYNC(dir)) {
1120				err = fat_sync_bhs(bhs, n);
1121				if (err)
1122					goto error;
1123			}
1124			for (i = 0; i < n; i++)
1125				brelse(bhs[i]);
1126			n = 0;
1127		}
1128	}
1129	if (IS_DIRSYNC(dir)) {
1130		err = fat_sync_bhs(bhs, n);
1131		if (err)
1132			goto error;
1133	}
1134	for (i = 0; i < n; i++)
1135		brelse(bhs[i]);
1136
1137	return 0;
1138
1139error:
1140	for (i = 0; i < n; i++)
1141		bforget(bhs[i]);
1142	return err;
1143}
1144
1145int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts)
1146{
1147	struct super_block *sb = dir->i_sb;
1148	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1149	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1150	struct msdos_dir_entry *de;
1151	sector_t blknr;
1152	__le16 date, time;
1153	u8 time_cs;
1154	int err, cluster;
1155
1156	err = fat_alloc_clusters(dir, &cluster, 1);
1157	if (err)
1158		goto error;
1159
1160	blknr = fat_clus_to_blknr(sbi, cluster);
1161	bhs[0] = sb_getblk(sb, blknr);
1162	if (!bhs[0]) {
1163		err = -ENOMEM;
1164		goto error_free;
1165	}
1166
1167	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1168
1169	de = (struct msdos_dir_entry *)bhs[0]->b_data;
1170	/* Avoid race with userspace read via bdev */
1171	lock_buffer(bhs[0]);
1172	/* filling the new directory slots ("." and ".." entries) */
1173	memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1174	memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1175	de->attr = de[1].attr = ATTR_DIR;
1176	de[0].lcase = de[1].lcase = 0;
1177	de[0].time = de[1].time = time;
1178	de[0].date = de[1].date = date;
1179	if (sbi->options.isvfat) {
1180		/* extra timestamps */
1181		de[0].ctime = de[1].ctime = time;
1182		de[0].ctime_cs = de[1].ctime_cs = time_cs;
1183		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1184	} else {
1185		de[0].ctime = de[1].ctime = 0;
1186		de[0].ctime_cs = de[1].ctime_cs = 0;
1187		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1188	}
1189	fat_set_start(&de[0], cluster);
1190	fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1191	de[0].size = de[1].size = 0;
1192	memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1193	set_buffer_uptodate(bhs[0]);
1194	unlock_buffer(bhs[0]);
1195	mark_buffer_dirty_inode(bhs[0], dir);
1196
1197	err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1198	if (err)
1199		goto error_free;
1200
1201	return cluster;
1202
1203error_free:
1204	fat_free_clusters(dir, cluster);
1205error:
1206	return err;
1207}
1208EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1209
1210static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1211			       int *nr_cluster, struct msdos_dir_entry **de,
1212			       struct buffer_head **bh)
1213{
1214	struct super_block *sb = dir->i_sb;
1215	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1216	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1217	sector_t blknr, start_blknr, last_blknr;
1218	unsigned long size, copy;
1219	int err, i, n, offset, cluster[2];
1220
1221	/*
1222	 * The minimum cluster size is 512bytes, and maximum entry
1223	 * size is 32*slots (672bytes).  So, iff the cluster size is
1224	 * 512bytes, we may need two clusters.
1225	 */
1226	size = nr_slots * sizeof(struct msdos_dir_entry);
1227	*nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1228	BUG_ON(*nr_cluster > 2);
1229
1230	err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1231	if (err)
1232		goto error;
1233
1234	/*
1235	 * First stage: Fill the directory entry.  NOTE: This cluster
1236	 * is not referenced from any inode yet, so updates order is
1237	 * not important.
1238	 */
1239	i = n = copy = 0;
1240	do {
1241		start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1242		last_blknr = start_blknr + sbi->sec_per_clus;
1243		while (blknr < last_blknr) {
1244			bhs[n] = sb_getblk(sb, blknr);
1245			if (!bhs[n]) {
1246				err = -ENOMEM;
1247				goto error_nomem;
1248			}
1249
1250			/* fill the directory entry */
1251			copy = min(size, sb->s_blocksize);
1252			/* Avoid race with userspace read via bdev */
1253			lock_buffer(bhs[n]);
1254			memcpy(bhs[n]->b_data, slots, copy);
1255			set_buffer_uptodate(bhs[n]);
1256			unlock_buffer(bhs[n]);
1257			mark_buffer_dirty_inode(bhs[n], dir);
1258			slots += copy;
1259			size -= copy;
1260			if (!size)
1261				break;
1262			n++;
1263			blknr++;
1264		}
1265	} while (++i < *nr_cluster);
1266
1267	memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1268	offset = copy - sizeof(struct msdos_dir_entry);
1269	get_bh(bhs[n]);
1270	*bh = bhs[n];
1271	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1272
1273	/* Second stage: clear the rest of cluster, and write outs */
1274	err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1275	if (err)
1276		goto error_free;
1277
1278	return cluster[0];
1279
1280error_free:
1281	brelse(*bh);
1282	*bh = NULL;
1283	n = 0;
1284error_nomem:
1285	for (i = 0; i < n; i++)
1286		bforget(bhs[i]);
1287	fat_free_clusters(dir, cluster[0]);
1288error:
1289	return err;
1290}
1291
1292int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1293		    struct fat_slot_info *sinfo)
1294{
1295	struct super_block *sb = dir->i_sb;
1296	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1297	struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1298	struct msdos_dir_entry *de;
1299	int err, free_slots, i, nr_bhs;
1300	loff_t pos;
1301
1302	sinfo->nr_slots = nr_slots;
1303
1304	/* First stage: search free directory entries */
1305	free_slots = nr_bhs = 0;
1306	bh = prev = NULL;
1307	pos = 0;
1308	err = -ENOSPC;
1309	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1310		/* check the maximum size of directory */
1311		if (pos >= FAT_MAX_DIR_SIZE)
1312			goto error;
1313
1314		if (IS_FREE(de->name)) {
1315			if (prev != bh) {
1316				get_bh(bh);
1317				bhs[nr_bhs] = prev = bh;
1318				nr_bhs++;
1319			}
1320			free_slots++;
1321			if (free_slots == nr_slots)
1322				goto found;
1323		} else {
1324			for (i = 0; i < nr_bhs; i++)
1325				brelse(bhs[i]);
1326			prev = NULL;
1327			free_slots = nr_bhs = 0;
1328		}
1329	}
1330	if (dir->i_ino == MSDOS_ROOT_INO) {
1331		if (!is_fat32(sbi))
1332			goto error;
1333	} else if (MSDOS_I(dir)->i_start == 0) {
1334		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1335		       MSDOS_I(dir)->i_pos);
1336		err = -EIO;
1337		goto error;
1338	}
1339
1340found:
1341	err = 0;
1342	pos -= free_slots * sizeof(*de);
1343	nr_slots -= free_slots;
1344	if (free_slots) {
1345		/*
1346		 * Second stage: filling the free entries with new entries.
1347		 * NOTE: If this slots has shortname, first, we write
1348		 * the long name slots, then write the short name.
1349		 */
1350		int size = free_slots * sizeof(*de);
1351		int offset = pos & (sb->s_blocksize - 1);
1352		int long_bhs = nr_bhs - (nr_slots == 0);
1353
1354		/* Fill the long name slots. */
1355		for (i = 0; i < long_bhs; i++) {
1356			int copy = min_t(int, sb->s_blocksize - offset, size);
1357			memcpy(bhs[i]->b_data + offset, slots, copy);
1358			mark_buffer_dirty_inode(bhs[i], dir);
1359			offset = 0;
1360			slots += copy;
1361			size -= copy;
1362		}
1363		if (long_bhs && IS_DIRSYNC(dir))
1364			err = fat_sync_bhs(bhs, long_bhs);
1365		if (!err && i < nr_bhs) {
1366			/* Fill the short name slot. */
1367			int copy = min_t(int, sb->s_blocksize - offset, size);
1368			memcpy(bhs[i]->b_data + offset, slots, copy);
1369			mark_buffer_dirty_inode(bhs[i], dir);
1370			if (IS_DIRSYNC(dir))
1371				err = sync_dirty_buffer(bhs[i]);
1372		}
1373		for (i = 0; i < nr_bhs; i++)
1374			brelse(bhs[i]);
1375		if (err)
1376			goto error_remove;
1377	}
1378
1379	if (nr_slots) {
1380		int cluster, nr_cluster;
1381
1382		/*
1383		 * Third stage: allocate the cluster for new entries.
1384		 * And initialize the cluster with new entries, then
1385		 * add the cluster to dir.
1386		 */
1387		cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1388					      &de, &bh);
1389		if (cluster < 0) {
1390			err = cluster;
1391			goto error_remove;
1392		}
1393		err = fat_chain_add(dir, cluster, nr_cluster);
1394		if (err) {
1395			fat_free_clusters(dir, cluster);
1396			goto error_remove;
1397		}
1398		if (dir->i_size & (sbi->cluster_size - 1)) {
1399			fat_fs_error(sb, "Odd directory size");
1400			dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1401				& ~((loff_t)sbi->cluster_size - 1);
1402		}
1403		dir->i_size += nr_cluster << sbi->cluster_bits;
1404		MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1405	}
1406	sinfo->slot_off = pos;
1407	sinfo->de = de;
1408	sinfo->bh = bh;
1409	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1410
1411	return 0;
1412
1413error:
1414	brelse(bh);
1415	for (i = 0; i < nr_bhs; i++)
1416		brelse(bhs[i]);
1417	return err;
1418
1419error_remove:
1420	brelse(bh);
1421	if (free_slots)
1422		__fat_remove_entries(dir, pos, free_slots);
1423	return err;
1424}
1425EXPORT_SYMBOL_GPL(fat_add_entries);