xref: /openbmc/linux/fs/fat/dir.c (revision d8eabc37)
1 /*
2  *  linux/fs/fat/dir.c
3  *
4  *  directory handling functions for fat-based filesystems
5  *
6  *  Written 1992,1993 by Werner Almesberger
7  *
8  *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
9  *
10  *  VFAT extensions by Gordon Chaffee <chaffee@plateau.cs.berkeley.edu>
11  *  Merged with msdos fs by Henrik Storner <storner@osiris.ping.dk>
12  *  Rewritten for constant inumbers. Plugged buffer overrun in readdir(). AV
13  *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
14  */
15 
16 #include <linux/slab.h>
17 #include <linux/compat.h>
18 #include <linux/uaccess.h>
19 #include <linux/iversion.h>
20 #include "fat.h"
21 
22 /*
23  * Maximum buffer size of short name.
24  * [(MSDOS_NAME + '.') * max one char + nul]
25  * For msdos style, ['.' (hidden) + MSDOS_NAME + '.' + nul]
26  */
27 #define FAT_MAX_SHORT_SIZE	((MSDOS_NAME + 1) * NLS_MAX_CHARSET_SIZE + 1)
28 /*
29  * Maximum buffer size of unicode chars from slots.
30  * [(max longname slots * 13 (size in a slot) + nul) * sizeof(wchar_t)]
31  */
32 #define FAT_MAX_UNI_CHARS	((MSDOS_SLOTS - 1) * 13 + 1)
33 #define FAT_MAX_UNI_SIZE	(FAT_MAX_UNI_CHARS * sizeof(wchar_t))
34 
35 static inline unsigned char fat_tolower(unsigned char c)
36 {
37 	return ((c >= 'A') && (c <= 'Z')) ? c+32 : c;
38 }
39 
40 static inline loff_t fat_make_i_pos(struct super_block *sb,
41 				    struct buffer_head *bh,
42 				    struct msdos_dir_entry *de)
43 {
44 	return ((loff_t)bh->b_blocknr << MSDOS_SB(sb)->dir_per_block_bits)
45 		| (de - (struct msdos_dir_entry *)bh->b_data);
46 }
47 
48 static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
49 				     sector_t phys)
50 {
51 	struct super_block *sb = dir->i_sb;
52 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
53 	struct buffer_head *bh;
54 	int sec;
55 
56 	/* This is not a first sector of cluster, or sec_per_clus == 1 */
57 	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
58 		return;
59 	/* root dir of FAT12/FAT16 */
60 	if (!is_fat32(sbi) && (dir->i_ino == MSDOS_ROOT_INO))
61 		return;
62 
63 	bh = sb_find_get_block(sb, phys);
64 	if (bh == NULL || !buffer_uptodate(bh)) {
65 		for (sec = 0; sec < sbi->sec_per_clus; sec++)
66 			sb_breadahead(sb, phys + sec);
67 	}
68 	brelse(bh);
69 }
70 
71 /* Returns the inode number of the directory entry at offset pos. If bh is
72    non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
73    returned in bh.
74    AV. Most often we do it item-by-item. Makes sense to optimize.
75    AV. OK, there we go: if both bh and de are non-NULL we assume that we just
76    AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
77    AV. It's done in fat_get_entry() (inlined), here the slow case lives.
78    AV. Additionally, when we return -1 (i.e. reached the end of directory)
79    AV. we make bh NULL.
80  */
81 static int fat__get_entry(struct inode *dir, loff_t *pos,
82 			  struct buffer_head **bh, struct msdos_dir_entry **de)
83 {
84 	struct super_block *sb = dir->i_sb;
85 	sector_t phys, iblock;
86 	unsigned long mapped_blocks;
87 	int err, offset;
88 
89 next:
90 	if (*bh)
91 		brelse(*bh);
92 
93 	*bh = NULL;
94 	iblock = *pos >> sb->s_blocksize_bits;
95 	err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0, false);
96 	if (err || !phys)
97 		return -1;	/* beyond EOF or error */
98 
99 	fat_dir_readahead(dir, iblock, phys);
100 
101 	*bh = sb_bread(sb, phys);
102 	if (*bh == NULL) {
103 		fat_msg_ratelimit(sb, KERN_ERR,
104 			"Directory bread(block %llu) failed", (llu)phys);
105 		/* skip this block */
106 		*pos = (iblock + 1) << sb->s_blocksize_bits;
107 		goto next;
108 	}
109 
110 	offset = *pos & (sb->s_blocksize - 1);
111 	*pos += sizeof(struct msdos_dir_entry);
112 	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
113 
114 	return 0;
115 }
116 
117 static inline int fat_get_entry(struct inode *dir, loff_t *pos,
118 				struct buffer_head **bh,
119 				struct msdos_dir_entry **de)
120 {
121 	/* Fast stuff first */
122 	if (*bh && *de &&
123 	   (*de - (struct msdos_dir_entry *)(*bh)->b_data) <
124 				MSDOS_SB(dir->i_sb)->dir_per_block - 1) {
125 		*pos += sizeof(struct msdos_dir_entry);
126 		(*de)++;
127 		return 0;
128 	}
129 	return fat__get_entry(dir, pos, bh, de);
130 }
131 
132 /*
133  * Convert Unicode 16 to UTF-8, translated Unicode, or ASCII.
134  * If uni_xlate is enabled and we can't get a 1:1 conversion, use a
135  * colon as an escape character since it is normally invalid on the vfat
136  * filesystem. The following four characters are the hexadecimal digits
137  * of Unicode value. This lets us do a full dump and restore of Unicode
138  * filenames. We could get into some trouble with long Unicode names,
139  * but ignore that right now.
140  * Ahem... Stack smashing in ring 0 isn't fun. Fixed.
141  */
142 static int uni16_to_x8(struct super_block *sb, unsigned char *ascii,
143 		       const wchar_t *uni, int len, struct nls_table *nls)
144 {
145 	int uni_xlate = MSDOS_SB(sb)->options.unicode_xlate;
146 	const wchar_t *ip;
147 	wchar_t ec;
148 	unsigned char *op;
149 	int charlen;
150 
151 	ip = uni;
152 	op = ascii;
153 
154 	while (*ip && ((len - NLS_MAX_CHARSET_SIZE) > 0)) {
155 		ec = *ip++;
156 		charlen = nls->uni2char(ec, op, NLS_MAX_CHARSET_SIZE);
157 		if (charlen > 0) {
158 			op += charlen;
159 			len -= charlen;
160 		} else {
161 			if (uni_xlate == 1) {
162 				*op++ = ':';
163 				op = hex_byte_pack(op, ec >> 8);
164 				op = hex_byte_pack(op, ec);
165 				len -= 5;
166 			} else {
167 				*op++ = '?';
168 				len--;
169 			}
170 		}
171 	}
172 
173 	if (unlikely(*ip)) {
174 		fat_msg(sb, KERN_WARNING,
175 			"filename was truncated while converting.");
176 	}
177 
178 	*op = 0;
179 	return op - ascii;
180 }
181 
182 static inline int fat_uni_to_x8(struct super_block *sb, const wchar_t *uni,
183 				unsigned char *buf, int size)
184 {
185 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
186 	if (sbi->options.utf8)
187 		return utf16s_to_utf8s(uni, FAT_MAX_UNI_CHARS,
188 				UTF16_HOST_ENDIAN, buf, size);
189 	else
190 		return uni16_to_x8(sb, buf, uni, size, sbi->nls_io);
191 }
192 
193 static inline int
194 fat_short2uni(struct nls_table *t, unsigned char *c, int clen, wchar_t *uni)
195 {
196 	int charlen;
197 
198 	charlen = t->char2uni(c, clen, uni);
199 	if (charlen < 0) {
200 		*uni = 0x003f;	/* a question mark */
201 		charlen = 1;
202 	}
203 	return charlen;
204 }
205 
206 static inline int
207 fat_short2lower_uni(struct nls_table *t, unsigned char *c,
208 		    int clen, wchar_t *uni)
209 {
210 	int charlen;
211 	wchar_t wc;
212 
213 	charlen = t->char2uni(c, clen, &wc);
214 	if (charlen < 0) {
215 		*uni = 0x003f;	/* a question mark */
216 		charlen = 1;
217 	} else if (charlen <= 1) {
218 		unsigned char nc = t->charset2lower[*c];
219 
220 		if (!nc)
221 			nc = *c;
222 
223 		charlen = t->char2uni(&nc, 1, uni);
224 		if (charlen < 0) {
225 			*uni = 0x003f;	/* a question mark */
226 			charlen = 1;
227 		}
228 	} else
229 		*uni = wc;
230 
231 	return charlen;
232 }
233 
234 static inline int
235 fat_shortname2uni(struct nls_table *nls, unsigned char *buf, int buf_size,
236 		  wchar_t *uni_buf, unsigned short opt, int lower)
237 {
238 	int len = 0;
239 
240 	if (opt & VFAT_SFN_DISPLAY_LOWER)
241 		len =  fat_short2lower_uni(nls, buf, buf_size, uni_buf);
242 	else if (opt & VFAT_SFN_DISPLAY_WIN95)
243 		len = fat_short2uni(nls, buf, buf_size, uni_buf);
244 	else if (opt & VFAT_SFN_DISPLAY_WINNT) {
245 		if (lower)
246 			len = fat_short2lower_uni(nls, buf, buf_size, uni_buf);
247 		else
248 			len = fat_short2uni(nls, buf, buf_size, uni_buf);
249 	} else
250 		len = fat_short2uni(nls, buf, buf_size, uni_buf);
251 
252 	return len;
253 }
254 
255 static inline int fat_name_match(struct msdos_sb_info *sbi,
256 				 const unsigned char *a, int a_len,
257 				 const unsigned char *b, int b_len)
258 {
259 	if (a_len != b_len)
260 		return 0;
261 
262 	if (sbi->options.name_check != 's')
263 		return !nls_strnicmp(sbi->nls_io, a, b, a_len);
264 	else
265 		return !memcmp(a, b, a_len);
266 }
267 
268 enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };
269 
270 /**
271  * fat_parse_long - Parse extended directory entry.
272  *
273  * This function returns zero on success, negative value on error, or one of
274  * the following:
275  *
276  * %PARSE_INVALID - Directory entry is invalid.
277  * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
278  * %PARSE_EOF - Directory has no more entries.
279  */
280 static int fat_parse_long(struct inode *dir, loff_t *pos,
281 			  struct buffer_head **bh, struct msdos_dir_entry **de,
282 			  wchar_t **unicode, unsigned char *nr_slots)
283 {
284 	struct msdos_dir_slot *ds;
285 	unsigned char id, slot, slots, alias_checksum;
286 
287 	if (!*unicode) {
288 		*unicode = __getname();
289 		if (!*unicode) {
290 			brelse(*bh);
291 			return -ENOMEM;
292 		}
293 	}
294 parse_long:
295 	ds = (struct msdos_dir_slot *)*de;
296 	id = ds->id;
297 	if (!(id & 0x40))
298 		return PARSE_INVALID;
299 	slots = id & ~0x40;
300 	if (slots > 20 || !slots)	/* ceil(256 * 2 / 26) */
301 		return PARSE_INVALID;
302 	*nr_slots = slots;
303 	alias_checksum = ds->alias_checksum;
304 
305 	slot = slots;
306 	while (1) {
307 		int offset;
308 
309 		slot--;
310 		offset = slot * 13;
311 		fat16_towchar(*unicode + offset, ds->name0_4, 5);
312 		fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
313 		fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);
314 
315 		if (ds->id & 0x40)
316 			(*unicode)[offset + 13] = 0;
317 		if (fat_get_entry(dir, pos, bh, de) < 0)
318 			return PARSE_EOF;
319 		if (slot == 0)
320 			break;
321 		ds = (struct msdos_dir_slot *)*de;
322 		if (ds->attr != ATTR_EXT)
323 			return PARSE_NOT_LONGNAME;
324 		if ((ds->id & ~0x40) != slot)
325 			goto parse_long;
326 		if (ds->alias_checksum != alias_checksum)
327 			goto parse_long;
328 	}
329 	if ((*de)->name[0] == DELETED_FLAG)
330 		return PARSE_INVALID;
331 	if ((*de)->attr == ATTR_EXT)
332 		goto parse_long;
333 	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
334 		return PARSE_INVALID;
335 	if (fat_checksum((*de)->name) != alias_checksum)
336 		*nr_slots = 0;
337 
338 	return 0;
339 }
340 
341 /**
342  * fat_parse_short - Parse MS-DOS (short) directory entry.
343  * @sb:		superblock
344  * @de:		directory entry to parse
345  * @name:	FAT_MAX_SHORT_SIZE array in which to place extracted name
346  * @dot_hidden:	Nonzero == prepend '.' to names with ATTR_HIDDEN
347  *
348  * Returns the number of characters extracted into 'name'.
349  */
350 static int fat_parse_short(struct super_block *sb,
351 			   const struct msdos_dir_entry *de,
352 			   unsigned char *name, int dot_hidden)
353 {
354 	const struct msdos_sb_info *sbi = MSDOS_SB(sb);
355 	int isvfat = sbi->options.isvfat;
356 	int nocase = sbi->options.nocase;
357 	unsigned short opt_shortname = sbi->options.shortname;
358 	struct nls_table *nls_disk = sbi->nls_disk;
359 	wchar_t uni_name[14];
360 	unsigned char c, work[MSDOS_NAME];
361 	unsigned char *ptname = name;
362 	int chi, chl, i, j, k;
363 	int dotoffset = 0;
364 	int name_len = 0, uni_len = 0;
365 
366 	if (!isvfat && dot_hidden && (de->attr & ATTR_HIDDEN)) {
367 		*ptname++ = '.';
368 		dotoffset = 1;
369 	}
370 
371 	memcpy(work, de->name, sizeof(work));
372 	/* For an explanation of the special treatment of 0x05 in
373 	 * filenames, see msdos_format_name in namei_msdos.c
374 	 */
375 	if (work[0] == 0x05)
376 		work[0] = 0xE5;
377 
378 	/* Filename */
379 	for (i = 0, j = 0; i < 8;) {
380 		c = work[i];
381 		if (!c)
382 			break;
383 		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
384 					&uni_name[j++], opt_shortname,
385 					de->lcase & CASE_LOWER_BASE);
386 		if (chl <= 1) {
387 			if (!isvfat)
388 				ptname[i] = nocase ? c : fat_tolower(c);
389 			i++;
390 			if (c != ' ') {
391 				name_len = i;
392 				uni_len  = j;
393 			}
394 		} else {
395 			uni_len = j;
396 			if (isvfat)
397 				i += min(chl, 8-i);
398 			else {
399 				for (chi = 0; chi < chl && i < 8; chi++, i++)
400 					ptname[i] = work[i];
401 			}
402 			if (chl)
403 				name_len = i;
404 		}
405 	}
406 
407 	i = name_len;
408 	j = uni_len;
409 	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
410 	if (!isvfat)
411 		ptname[i] = '.';
412 	i++;
413 
414 	/* Extension */
415 	for (k = 8; k < MSDOS_NAME;) {
416 		c = work[k];
417 		if (!c)
418 			break;
419 		chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
420 					&uni_name[j++], opt_shortname,
421 					de->lcase & CASE_LOWER_EXT);
422 		if (chl <= 1) {
423 			k++;
424 			if (!isvfat)
425 				ptname[i] = nocase ? c : fat_tolower(c);
426 			i++;
427 			if (c != ' ') {
428 				name_len = i;
429 				uni_len  = j;
430 			}
431 		} else {
432 			uni_len = j;
433 			if (isvfat) {
434 				int offset = min(chl, MSDOS_NAME-k);
435 				k += offset;
436 				i += offset;
437 			} else {
438 				for (chi = 0; chi < chl && k < MSDOS_NAME;
439 				     chi++, i++, k++) {
440 						ptname[i] = work[k];
441 				}
442 			}
443 			if (chl)
444 				name_len = i;
445 		}
446 	}
447 
448 	if (name_len > 0) {
449 		name_len += dotoffset;
450 
451 		if (sbi->options.isvfat) {
452 			uni_name[uni_len] = 0x0000;
453 			name_len = fat_uni_to_x8(sb, uni_name, name,
454 						 FAT_MAX_SHORT_SIZE);
455 		}
456 	}
457 
458 	return name_len;
459 }
460 
461 /*
462  * Return values: negative -> error/not found, 0 -> found.
463  */
464 int fat_search_long(struct inode *inode, const unsigned char *name,
465 		    int name_len, struct fat_slot_info *sinfo)
466 {
467 	struct super_block *sb = inode->i_sb;
468 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
469 	struct buffer_head *bh = NULL;
470 	struct msdos_dir_entry *de;
471 	unsigned char nr_slots;
472 	wchar_t *unicode = NULL;
473 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
474 	loff_t cpos = 0;
475 	int err, len;
476 
477 	err = -ENOENT;
478 	while (1) {
479 		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
480 			goto end_of_dir;
481 parse_record:
482 		nr_slots = 0;
483 		if (de->name[0] == DELETED_FLAG)
484 			continue;
485 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
486 			continue;
487 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
488 			continue;
489 		if (de->attr == ATTR_EXT) {
490 			int status = fat_parse_long(inode, &cpos, &bh, &de,
491 						    &unicode, &nr_slots);
492 			if (status < 0) {
493 				err = status;
494 				goto end_of_dir;
495 			} else if (status == PARSE_INVALID)
496 				continue;
497 			else if (status == PARSE_NOT_LONGNAME)
498 				goto parse_record;
499 			else if (status == PARSE_EOF)
500 				goto end_of_dir;
501 		}
502 
503 		/* Never prepend '.' to hidden files here.
504 		 * That is done only for msdos mounts (and only when
505 		 * 'dotsOK=yes'); if we are executing here, it is in the
506 		 * context of a vfat mount.
507 		 */
508 		len = fat_parse_short(sb, de, bufname, 0);
509 		if (len == 0)
510 			continue;
511 
512 		/* Compare shortname */
513 		if (fat_name_match(sbi, name, name_len, bufname, len))
514 			goto found;
515 
516 		if (nr_slots) {
517 			void *longname = unicode + FAT_MAX_UNI_CHARS;
518 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
519 
520 			/* Compare longname */
521 			len = fat_uni_to_x8(sb, unicode, longname, size);
522 			if (fat_name_match(sbi, name, name_len, longname, len))
523 				goto found;
524 		}
525 	}
526 
527 found:
528 	nr_slots++;	/* include the de */
529 	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
530 	sinfo->nr_slots = nr_slots;
531 	sinfo->de = de;
532 	sinfo->bh = bh;
533 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
534 	err = 0;
535 end_of_dir:
536 	if (unicode)
537 		__putname(unicode);
538 
539 	return err;
540 }
541 EXPORT_SYMBOL_GPL(fat_search_long);
542 
543 struct fat_ioctl_filldir_callback {
544 	struct dir_context ctx;
545 	void __user *dirent;
546 	int result;
547 	/* for dir ioctl */
548 	const char *longname;
549 	int long_len;
550 	const char *shortname;
551 	int short_len;
552 };
553 
554 static int __fat_readdir(struct inode *inode, struct file *file,
555 			 struct dir_context *ctx, int short_only,
556 			 struct fat_ioctl_filldir_callback *both)
557 {
558 	struct super_block *sb = inode->i_sb;
559 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
560 	struct buffer_head *bh;
561 	struct msdos_dir_entry *de;
562 	unsigned char nr_slots;
563 	wchar_t *unicode = NULL;
564 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
565 	int isvfat = sbi->options.isvfat;
566 	const char *fill_name = NULL;
567 	int fake_offset = 0;
568 	loff_t cpos;
569 	int short_len = 0, fill_len = 0;
570 	int ret = 0;
571 
572 	mutex_lock(&sbi->s_lock);
573 
574 	cpos = ctx->pos;
575 	/* Fake . and .. for the root directory. */
576 	if (inode->i_ino == MSDOS_ROOT_INO) {
577 		if (!dir_emit_dots(file, ctx))
578 			goto out;
579 		if (ctx->pos == 2) {
580 			fake_offset = 1;
581 			cpos = 0;
582 		}
583 	}
584 	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
585 		ret = -ENOENT;
586 		goto out;
587 	}
588 
589 	bh = NULL;
590 get_new:
591 	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
592 		goto end_of_dir;
593 parse_record:
594 	nr_slots = 0;
595 	/*
596 	 * Check for long filename entry, but if short_only, we don't
597 	 * need to parse long filename.
598 	 */
599 	if (isvfat && !short_only) {
600 		if (de->name[0] == DELETED_FLAG)
601 			goto record_end;
602 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
603 			goto record_end;
604 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
605 			goto record_end;
606 	} else {
607 		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
608 			goto record_end;
609 	}
610 
611 	if (isvfat && de->attr == ATTR_EXT) {
612 		int status = fat_parse_long(inode, &cpos, &bh, &de,
613 					    &unicode, &nr_slots);
614 		if (status < 0) {
615 			bh = NULL;
616 			ret = status;
617 			goto end_of_dir;
618 		} else if (status == PARSE_INVALID)
619 			goto record_end;
620 		else if (status == PARSE_NOT_LONGNAME)
621 			goto parse_record;
622 		else if (status == PARSE_EOF)
623 			goto end_of_dir;
624 
625 		if (nr_slots) {
626 			void *longname = unicode + FAT_MAX_UNI_CHARS;
627 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
628 			int len = fat_uni_to_x8(sb, unicode, longname, size);
629 
630 			fill_name = longname;
631 			fill_len = len;
632 			/* !both && !short_only, so we don't need shortname. */
633 			if (!both)
634 				goto start_filldir;
635 
636 			short_len = fat_parse_short(sb, de, bufname,
637 						    sbi->options.dotsOK);
638 			if (short_len == 0)
639 				goto record_end;
640 			/* hack for fat_ioctl_filldir() */
641 			both->longname = fill_name;
642 			both->long_len = fill_len;
643 			both->shortname = bufname;
644 			both->short_len = short_len;
645 			fill_name = NULL;
646 			fill_len = 0;
647 			goto start_filldir;
648 		}
649 	}
650 
651 	short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
652 	if (short_len == 0)
653 		goto record_end;
654 
655 	fill_name = bufname;
656 	fill_len = short_len;
657 
658 start_filldir:
659 	ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
660 	if (fake_offset && ctx->pos < 2)
661 		ctx->pos = 2;
662 
663 	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
664 		if (!dir_emit_dot(file, ctx))
665 			goto fill_failed;
666 	} else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
667 		if (!dir_emit_dotdot(file, ctx))
668 			goto fill_failed;
669 	} else {
670 		unsigned long inum;
671 		loff_t i_pos = fat_make_i_pos(sb, bh, de);
672 		struct inode *tmp = fat_iget(sb, i_pos);
673 		if (tmp) {
674 			inum = tmp->i_ino;
675 			iput(tmp);
676 		} else
677 			inum = iunique(sb, MSDOS_ROOT_INO);
678 		if (!dir_emit(ctx, fill_name, fill_len, inum,
679 			    (de->attr & ATTR_DIR) ? DT_DIR : DT_REG))
680 			goto fill_failed;
681 	}
682 
683 record_end:
684 	fake_offset = 0;
685 	ctx->pos = cpos;
686 	goto get_new;
687 
688 end_of_dir:
689 	if (fake_offset && cpos < 2)
690 		ctx->pos = 2;
691 	else
692 		ctx->pos = cpos;
693 fill_failed:
694 	brelse(bh);
695 	if (unicode)
696 		__putname(unicode);
697 out:
698 	mutex_unlock(&sbi->s_lock);
699 
700 	return ret;
701 }
702 
703 static int fat_readdir(struct file *file, struct dir_context *ctx)
704 {
705 	return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
706 }
707 
708 #define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
709 static int func(struct dir_context *ctx, const char *name, int name_len,   \
710 			     loff_t offset, u64 ino, unsigned int d_type)  \
711 {									   \
712 	struct fat_ioctl_filldir_callback *buf =			   \
713 		container_of(ctx, struct fat_ioctl_filldir_callback, ctx); \
714 	struct dirent_type __user *d1 = buf->dirent;			   \
715 	struct dirent_type __user *d2 = d1 + 1;				   \
716 									   \
717 	if (buf->result)						   \
718 		return -EINVAL;						   \
719 	buf->result++;							   \
720 									   \
721 	if (name != NULL) {						   \
722 		/* dirent has only short name */			   \
723 		if (name_len >= sizeof(d1->d_name))			   \
724 			name_len = sizeof(d1->d_name) - 1;		   \
725 									   \
726 		if (put_user(0, d2->d_name)			||	   \
727 		    put_user(0, &d2->d_reclen)			||	   \
728 		    copy_to_user(d1->d_name, name, name_len)	||	   \
729 		    put_user(0, d1->d_name + name_len)		||	   \
730 		    put_user(name_len, &d1->d_reclen))			   \
731 			goto efault;					   \
732 	} else {							   \
733 		/* dirent has short and long name */			   \
734 		const char *longname = buf->longname;			   \
735 		int long_len = buf->long_len;				   \
736 		const char *shortname = buf->shortname;			   \
737 		int short_len = buf->short_len;				   \
738 									   \
739 		if (long_len >= sizeof(d1->d_name))			   \
740 			long_len = sizeof(d1->d_name) - 1;		   \
741 		if (short_len >= sizeof(d1->d_name))			   \
742 			short_len = sizeof(d1->d_name) - 1;		   \
743 									   \
744 		if (copy_to_user(d2->d_name, longname, long_len)	|| \
745 		    put_user(0, d2->d_name + long_len)			|| \
746 		    put_user(long_len, &d2->d_reclen)			|| \
747 		    put_user(ino, &d2->d_ino)				|| \
748 		    put_user(offset, &d2->d_off)			|| \
749 		    copy_to_user(d1->d_name, shortname, short_len)	|| \
750 		    put_user(0, d1->d_name + short_len)			|| \
751 		    put_user(short_len, &d1->d_reclen))			   \
752 			goto efault;					   \
753 	}								   \
754 	return 0;							   \
755 efault:									   \
756 	buf->result = -EFAULT;						   \
757 	return -EFAULT;							   \
758 }
759 
760 FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
761 
762 static int fat_ioctl_readdir(struct inode *inode, struct file *file,
763 			     void __user *dirent, filldir_t filldir,
764 			     int short_only, int both)
765 {
766 	struct fat_ioctl_filldir_callback buf = {
767 		.ctx.actor = filldir,
768 		.dirent = dirent
769 	};
770 	int ret;
771 
772 	buf.dirent = dirent;
773 	buf.result = 0;
774 	inode_lock_shared(inode);
775 	buf.ctx.pos = file->f_pos;
776 	ret = -ENOENT;
777 	if (!IS_DEADDIR(inode)) {
778 		ret = __fat_readdir(inode, file, &buf.ctx,
779 				    short_only, both ? &buf : NULL);
780 		file->f_pos = buf.ctx.pos;
781 	}
782 	inode_unlock_shared(inode);
783 	if (ret >= 0)
784 		ret = buf.result;
785 	return ret;
786 }
787 
788 static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
789 			  unsigned long arg)
790 {
791 	struct inode *inode = file_inode(filp);
792 	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
793 	int short_only, both;
794 
795 	switch (cmd) {
796 	case VFAT_IOCTL_READDIR_SHORT:
797 		short_only = 1;
798 		both = 0;
799 		break;
800 	case VFAT_IOCTL_READDIR_BOTH:
801 		short_only = 0;
802 		both = 1;
803 		break;
804 	default:
805 		return fat_generic_ioctl(filp, cmd, arg);
806 	}
807 
808 	if (!access_ok(d1, sizeof(struct __fat_dirent[2])))
809 		return -EFAULT;
810 	/*
811 	 * Yes, we don't need this put_user() absolutely. However old
812 	 * code didn't return the right value. So, app use this value,
813 	 * in order to check whether it is EOF.
814 	 */
815 	if (put_user(0, &d1->d_reclen))
816 		return -EFAULT;
817 
818 	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
819 				 short_only, both);
820 }
821 
822 #ifdef CONFIG_COMPAT
823 #define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
824 #define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])
825 
826 FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
827 
828 static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
829 				 unsigned long arg)
830 {
831 	struct inode *inode = file_inode(filp);
832 	struct compat_dirent __user *d1 = compat_ptr(arg);
833 	int short_only, both;
834 
835 	switch (cmd) {
836 	case VFAT_IOCTL_READDIR_SHORT32:
837 		short_only = 1;
838 		both = 0;
839 		break;
840 	case VFAT_IOCTL_READDIR_BOTH32:
841 		short_only = 0;
842 		both = 1;
843 		break;
844 	default:
845 		return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
846 	}
847 
848 	if (!access_ok(d1, sizeof(struct compat_dirent[2])))
849 		return -EFAULT;
850 	/*
851 	 * Yes, we don't need this put_user() absolutely. However old
852 	 * code didn't return the right value. So, app use this value,
853 	 * in order to check whether it is EOF.
854 	 */
855 	if (put_user(0, &d1->d_reclen))
856 		return -EFAULT;
857 
858 	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
859 				 short_only, both);
860 }
861 #endif /* CONFIG_COMPAT */
862 
863 const struct file_operations fat_dir_operations = {
864 	.llseek		= generic_file_llseek,
865 	.read		= generic_read_dir,
866 	.iterate_shared	= fat_readdir,
867 	.unlocked_ioctl	= fat_dir_ioctl,
868 #ifdef CONFIG_COMPAT
869 	.compat_ioctl	= fat_compat_dir_ioctl,
870 #endif
871 	.fsync		= fat_file_fsync,
872 };
873 
874 static int fat_get_short_entry(struct inode *dir, loff_t *pos,
875 			       struct buffer_head **bh,
876 			       struct msdos_dir_entry **de)
877 {
878 	while (fat_get_entry(dir, pos, bh, de) >= 0) {
879 		/* free entry or long name entry or volume label */
880 		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
881 			return 0;
882 	}
883 	return -ENOENT;
884 }
885 
886 /*
887  * The ".." entry can not provide the "struct fat_slot_info" information
888  * for inode, nor a usable i_pos. So, this function provides some information
889  * only.
890  *
891  * Since this function walks through the on-disk inodes within a directory,
892  * callers are responsible for taking any locks necessary to prevent the
893  * directory from changing.
894  */
895 int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
896 			 struct msdos_dir_entry **de)
897 {
898 	loff_t offset = 0;
899 
900 	*de = NULL;
901 	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
902 		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
903 			return 0;
904 	}
905 	return -ENOENT;
906 }
907 EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
908 
909 /* See if directory is empty */
910 int fat_dir_empty(struct inode *dir)
911 {
912 	struct buffer_head *bh;
913 	struct msdos_dir_entry *de;
914 	loff_t cpos;
915 	int result = 0;
916 
917 	bh = NULL;
918 	cpos = 0;
919 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
920 		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
921 		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
922 			result = -ENOTEMPTY;
923 			break;
924 		}
925 	}
926 	brelse(bh);
927 	return result;
928 }
929 EXPORT_SYMBOL_GPL(fat_dir_empty);
930 
931 /*
932  * fat_subdirs counts the number of sub-directories of dir. It can be run
933  * on directories being created.
934  */
935 int fat_subdirs(struct inode *dir)
936 {
937 	struct buffer_head *bh;
938 	struct msdos_dir_entry *de;
939 	loff_t cpos;
940 	int count = 0;
941 
942 	bh = NULL;
943 	cpos = 0;
944 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
945 		if (de->attr & ATTR_DIR)
946 			count++;
947 	}
948 	brelse(bh);
949 	return count;
950 }
951 
952 /*
953  * Scans a directory for a given file (name points to its formatted name).
954  * Returns an error code or zero.
955  */
956 int fat_scan(struct inode *dir, const unsigned char *name,
957 	     struct fat_slot_info *sinfo)
958 {
959 	struct super_block *sb = dir->i_sb;
960 
961 	sinfo->slot_off = 0;
962 	sinfo->bh = NULL;
963 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
964 				   &sinfo->de) >= 0) {
965 		if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
966 			sinfo->slot_off -= sizeof(*sinfo->de);
967 			sinfo->nr_slots = 1;
968 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
969 			return 0;
970 		}
971 	}
972 	return -ENOENT;
973 }
974 EXPORT_SYMBOL_GPL(fat_scan);
975 
976 /*
977  * Scans a directory for a given logstart.
978  * Returns an error code or zero.
979  */
980 int fat_scan_logstart(struct inode *dir, int i_logstart,
981 		      struct fat_slot_info *sinfo)
982 {
983 	struct super_block *sb = dir->i_sb;
984 
985 	sinfo->slot_off = 0;
986 	sinfo->bh = NULL;
987 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
988 				   &sinfo->de) >= 0) {
989 		if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
990 			sinfo->slot_off -= sizeof(*sinfo->de);
991 			sinfo->nr_slots = 1;
992 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
993 			return 0;
994 		}
995 	}
996 	return -ENOENT;
997 }
998 
999 static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
1000 {
1001 	struct super_block *sb = dir->i_sb;
1002 	struct buffer_head *bh;
1003 	struct msdos_dir_entry *de, *endp;
1004 	int err = 0, orig_slots;
1005 
1006 	while (nr_slots) {
1007 		bh = NULL;
1008 		if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1009 			err = -EIO;
1010 			break;
1011 		}
1012 
1013 		orig_slots = nr_slots;
1014 		endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1015 		while (nr_slots && de < endp) {
1016 			de->name[0] = DELETED_FLAG;
1017 			de++;
1018 			nr_slots--;
1019 		}
1020 		mark_buffer_dirty_inode(bh, dir);
1021 		if (IS_DIRSYNC(dir))
1022 			err = sync_dirty_buffer(bh);
1023 		brelse(bh);
1024 		if (err)
1025 			break;
1026 
1027 		/* pos is *next* de's position, so this does `- sizeof(de)' */
1028 		pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1029 	}
1030 
1031 	return err;
1032 }
1033 
1034 int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1035 {
1036 	struct super_block *sb = dir->i_sb;
1037 	struct msdos_dir_entry *de;
1038 	struct buffer_head *bh;
1039 	int err = 0, nr_slots;
1040 
1041 	/*
1042 	 * First stage: Remove the shortname. By this, the directory
1043 	 * entry is removed.
1044 	 */
1045 	nr_slots = sinfo->nr_slots;
1046 	de = sinfo->de;
1047 	sinfo->de = NULL;
1048 	bh = sinfo->bh;
1049 	sinfo->bh = NULL;
1050 	while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1051 		de->name[0] = DELETED_FLAG;
1052 		de--;
1053 		nr_slots--;
1054 	}
1055 	mark_buffer_dirty_inode(bh, dir);
1056 	if (IS_DIRSYNC(dir))
1057 		err = sync_dirty_buffer(bh);
1058 	brelse(bh);
1059 	if (err)
1060 		return err;
1061 	inode_inc_iversion(dir);
1062 
1063 	if (nr_slots) {
1064 		/*
1065 		 * Second stage: remove the remaining longname slots.
1066 		 * (This directory entry is already removed, and so return
1067 		 * the success)
1068 		 */
1069 		err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1070 		if (err) {
1071 			fat_msg(sb, KERN_WARNING,
1072 			       "Couldn't remove the long name slots");
1073 		}
1074 	}
1075 
1076 	fat_truncate_time(dir, NULL, S_ATIME|S_MTIME);
1077 	if (IS_DIRSYNC(dir))
1078 		(void)fat_sync_inode(dir);
1079 	else
1080 		mark_inode_dirty(dir);
1081 
1082 	return 0;
1083 }
1084 EXPORT_SYMBOL_GPL(fat_remove_entries);
1085 
1086 static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1087 			      struct buffer_head **bhs, int nr_bhs)
1088 {
1089 	struct super_block *sb = dir->i_sb;
1090 	sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1091 	int err, i, n;
1092 
1093 	/* Zeroing the unused blocks on this cluster */
1094 	blknr += nr_used;
1095 	n = nr_used;
1096 	while (blknr < last_blknr) {
1097 		bhs[n] = sb_getblk(sb, blknr);
1098 		if (!bhs[n]) {
1099 			err = -ENOMEM;
1100 			goto error;
1101 		}
1102 		memset(bhs[n]->b_data, 0, sb->s_blocksize);
1103 		set_buffer_uptodate(bhs[n]);
1104 		mark_buffer_dirty_inode(bhs[n], dir);
1105 
1106 		n++;
1107 		blknr++;
1108 		if (n == nr_bhs) {
1109 			if (IS_DIRSYNC(dir)) {
1110 				err = fat_sync_bhs(bhs, n);
1111 				if (err)
1112 					goto error;
1113 			}
1114 			for (i = 0; i < n; i++)
1115 				brelse(bhs[i]);
1116 			n = 0;
1117 		}
1118 	}
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 
1127 	return 0;
1128 
1129 error:
1130 	for (i = 0; i < n; i++)
1131 		bforget(bhs[i]);
1132 	return err;
1133 }
1134 
1135 int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts)
1136 {
1137 	struct super_block *sb = dir->i_sb;
1138 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1139 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1140 	struct msdos_dir_entry *de;
1141 	sector_t blknr;
1142 	__le16 date, time;
1143 	u8 time_cs;
1144 	int err, cluster;
1145 
1146 	err = fat_alloc_clusters(dir, &cluster, 1);
1147 	if (err)
1148 		goto error;
1149 
1150 	blknr = fat_clus_to_blknr(sbi, cluster);
1151 	bhs[0] = sb_getblk(sb, blknr);
1152 	if (!bhs[0]) {
1153 		err = -ENOMEM;
1154 		goto error_free;
1155 	}
1156 
1157 	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1158 
1159 	de = (struct msdos_dir_entry *)bhs[0]->b_data;
1160 	/* filling the new directory slots ("." and ".." entries) */
1161 	memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1162 	memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1163 	de->attr = de[1].attr = ATTR_DIR;
1164 	de[0].lcase = de[1].lcase = 0;
1165 	de[0].time = de[1].time = time;
1166 	de[0].date = de[1].date = date;
1167 	if (sbi->options.isvfat) {
1168 		/* extra timestamps */
1169 		de[0].ctime = de[1].ctime = time;
1170 		de[0].ctime_cs = de[1].ctime_cs = time_cs;
1171 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1172 	} else {
1173 		de[0].ctime = de[1].ctime = 0;
1174 		de[0].ctime_cs = de[1].ctime_cs = 0;
1175 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1176 	}
1177 	fat_set_start(&de[0], cluster);
1178 	fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1179 	de[0].size = de[1].size = 0;
1180 	memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1181 	set_buffer_uptodate(bhs[0]);
1182 	mark_buffer_dirty_inode(bhs[0], dir);
1183 
1184 	err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1185 	if (err)
1186 		goto error_free;
1187 
1188 	return cluster;
1189 
1190 error_free:
1191 	fat_free_clusters(dir, cluster);
1192 error:
1193 	return err;
1194 }
1195 EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1196 
1197 static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1198 			       int *nr_cluster, struct msdos_dir_entry **de,
1199 			       struct buffer_head **bh, loff_t *i_pos)
1200 {
1201 	struct super_block *sb = dir->i_sb;
1202 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1203 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1204 	sector_t blknr, start_blknr, last_blknr;
1205 	unsigned long size, copy;
1206 	int err, i, n, offset, cluster[2];
1207 
1208 	/*
1209 	 * The minimum cluster size is 512bytes, and maximum entry
1210 	 * size is 32*slots (672bytes).  So, iff the cluster size is
1211 	 * 512bytes, we may need two clusters.
1212 	 */
1213 	size = nr_slots * sizeof(struct msdos_dir_entry);
1214 	*nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1215 	BUG_ON(*nr_cluster > 2);
1216 
1217 	err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1218 	if (err)
1219 		goto error;
1220 
1221 	/*
1222 	 * First stage: Fill the directory entry.  NOTE: This cluster
1223 	 * is not referenced from any inode yet, so updates order is
1224 	 * not important.
1225 	 */
1226 	i = n = copy = 0;
1227 	do {
1228 		start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1229 		last_blknr = start_blknr + sbi->sec_per_clus;
1230 		while (blknr < last_blknr) {
1231 			bhs[n] = sb_getblk(sb, blknr);
1232 			if (!bhs[n]) {
1233 				err = -ENOMEM;
1234 				goto error_nomem;
1235 			}
1236 
1237 			/* fill the directory entry */
1238 			copy = min(size, sb->s_blocksize);
1239 			memcpy(bhs[n]->b_data, slots, copy);
1240 			slots += copy;
1241 			size -= copy;
1242 			set_buffer_uptodate(bhs[n]);
1243 			mark_buffer_dirty_inode(bhs[n], dir);
1244 			if (!size)
1245 				break;
1246 			n++;
1247 			blknr++;
1248 		}
1249 	} while (++i < *nr_cluster);
1250 
1251 	memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1252 	offset = copy - sizeof(struct msdos_dir_entry);
1253 	get_bh(bhs[n]);
1254 	*bh = bhs[n];
1255 	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1256 	*i_pos = fat_make_i_pos(sb, *bh, *de);
1257 
1258 	/* Second stage: clear the rest of cluster, and write outs */
1259 	err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1260 	if (err)
1261 		goto error_free;
1262 
1263 	return cluster[0];
1264 
1265 error_free:
1266 	brelse(*bh);
1267 	*bh = NULL;
1268 	n = 0;
1269 error_nomem:
1270 	for (i = 0; i < n; i++)
1271 		bforget(bhs[i]);
1272 	fat_free_clusters(dir, cluster[0]);
1273 error:
1274 	return err;
1275 }
1276 
1277 int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1278 		    struct fat_slot_info *sinfo)
1279 {
1280 	struct super_block *sb = dir->i_sb;
1281 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1282 	struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1283 	struct msdos_dir_entry *uninitialized_var(de);
1284 	int err, free_slots, i, nr_bhs;
1285 	loff_t pos, i_pos;
1286 
1287 	sinfo->nr_slots = nr_slots;
1288 
1289 	/* First stage: search free directory entries */
1290 	free_slots = nr_bhs = 0;
1291 	bh = prev = NULL;
1292 	pos = 0;
1293 	err = -ENOSPC;
1294 	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1295 		/* check the maximum size of directory */
1296 		if (pos >= FAT_MAX_DIR_SIZE)
1297 			goto error;
1298 
1299 		if (IS_FREE(de->name)) {
1300 			if (prev != bh) {
1301 				get_bh(bh);
1302 				bhs[nr_bhs] = prev = bh;
1303 				nr_bhs++;
1304 			}
1305 			free_slots++;
1306 			if (free_slots == nr_slots)
1307 				goto found;
1308 		} else {
1309 			for (i = 0; i < nr_bhs; i++)
1310 				brelse(bhs[i]);
1311 			prev = NULL;
1312 			free_slots = nr_bhs = 0;
1313 		}
1314 	}
1315 	if (dir->i_ino == MSDOS_ROOT_INO) {
1316 		if (!is_fat32(sbi))
1317 			goto error;
1318 	} else if (MSDOS_I(dir)->i_start == 0) {
1319 		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1320 		       MSDOS_I(dir)->i_pos);
1321 		err = -EIO;
1322 		goto error;
1323 	}
1324 
1325 found:
1326 	err = 0;
1327 	pos -= free_slots * sizeof(*de);
1328 	nr_slots -= free_slots;
1329 	if (free_slots) {
1330 		/*
1331 		 * Second stage: filling the free entries with new entries.
1332 		 * NOTE: If this slots has shortname, first, we write
1333 		 * the long name slots, then write the short name.
1334 		 */
1335 		int size = free_slots * sizeof(*de);
1336 		int offset = pos & (sb->s_blocksize - 1);
1337 		int long_bhs = nr_bhs - (nr_slots == 0);
1338 
1339 		/* Fill the long name slots. */
1340 		for (i = 0; i < long_bhs; i++) {
1341 			int copy = min_t(int, sb->s_blocksize - offset, size);
1342 			memcpy(bhs[i]->b_data + offset, slots, copy);
1343 			mark_buffer_dirty_inode(bhs[i], dir);
1344 			offset = 0;
1345 			slots += copy;
1346 			size -= copy;
1347 		}
1348 		if (long_bhs && IS_DIRSYNC(dir))
1349 			err = fat_sync_bhs(bhs, long_bhs);
1350 		if (!err && i < nr_bhs) {
1351 			/* Fill the short name slot. */
1352 			int copy = min_t(int, sb->s_blocksize - offset, size);
1353 			memcpy(bhs[i]->b_data + offset, slots, copy);
1354 			mark_buffer_dirty_inode(bhs[i], dir);
1355 			if (IS_DIRSYNC(dir))
1356 				err = sync_dirty_buffer(bhs[i]);
1357 		}
1358 		for (i = 0; i < nr_bhs; i++)
1359 			brelse(bhs[i]);
1360 		if (err)
1361 			goto error_remove;
1362 	}
1363 
1364 	if (nr_slots) {
1365 		int cluster, nr_cluster;
1366 
1367 		/*
1368 		 * Third stage: allocate the cluster for new entries.
1369 		 * And initialize the cluster with new entries, then
1370 		 * add the cluster to dir.
1371 		 */
1372 		cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1373 					      &de, &bh, &i_pos);
1374 		if (cluster < 0) {
1375 			err = cluster;
1376 			goto error_remove;
1377 		}
1378 		err = fat_chain_add(dir, cluster, nr_cluster);
1379 		if (err) {
1380 			fat_free_clusters(dir, cluster);
1381 			goto error_remove;
1382 		}
1383 		if (dir->i_size & (sbi->cluster_size - 1)) {
1384 			fat_fs_error(sb, "Odd directory size");
1385 			dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1386 				& ~((loff_t)sbi->cluster_size - 1);
1387 		}
1388 		dir->i_size += nr_cluster << sbi->cluster_bits;
1389 		MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1390 	}
1391 	sinfo->slot_off = pos;
1392 	sinfo->de = de;
1393 	sinfo->bh = bh;
1394 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1395 
1396 	return 0;
1397 
1398 error:
1399 	brelse(bh);
1400 	for (i = 0; i < nr_bhs; i++)
1401 		brelse(bhs[i]);
1402 	return err;
1403 
1404 error_remove:
1405 	brelse(bh);
1406 	if (free_slots)
1407 		__fat_remove_entries(dir, pos, free_slots);
1408 	return err;
1409 }
1410 EXPORT_SYMBOL_GPL(fat_add_entries);
1411