xref: /openbmc/linux/fs/fat/dir.c (revision 020c5260)
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 "fat.h"
20 
21 /*
22  * Maximum buffer size of short name.
23  * [(MSDOS_NAME + '.') * max one char + nul]
24  * For msdos style, ['.' (hidden) + MSDOS_NAME + '.' + nul]
25  */
26 #define FAT_MAX_SHORT_SIZE	((MSDOS_NAME + 1) * NLS_MAX_CHARSET_SIZE + 1)
27 /*
28  * Maximum buffer size of unicode chars from slots.
29  * [(max longname slots * 13 (size in a slot) + nul) * sizeof(wchar_t)]
30  */
31 #define FAT_MAX_UNI_CHARS	((MSDOS_SLOTS - 1) * 13 + 1)
32 #define FAT_MAX_UNI_SIZE	(FAT_MAX_UNI_CHARS * sizeof(wchar_t))
33 
34 static inline unsigned char fat_tolower(unsigned char c)
35 {
36 	return ((c >= 'A') && (c <= 'Z')) ? c+32 : c;
37 }
38 
39 static inline loff_t fat_make_i_pos(struct super_block *sb,
40 				    struct buffer_head *bh,
41 				    struct msdos_dir_entry *de)
42 {
43 	return ((loff_t)bh->b_blocknr << MSDOS_SB(sb)->dir_per_block_bits)
44 		| (de - (struct msdos_dir_entry *)bh->b_data);
45 }
46 
47 static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
48 				     sector_t phys)
49 {
50 	struct super_block *sb = dir->i_sb;
51 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
52 	struct buffer_head *bh;
53 	int sec;
54 
55 	/* This is not a first sector of cluster, or sec_per_clus == 1 */
56 	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
57 		return;
58 	/* root dir of FAT12/FAT16 */
59 	if ((sbi->fat_bits != 32) && (dir->i_ino == MSDOS_ROOT_INO))
60 		return;
61 
62 	bh = sb_find_get_block(sb, phys);
63 	if (bh == NULL || !buffer_uptodate(bh)) {
64 		for (sec = 0; sec < sbi->sec_per_clus; sec++)
65 			sb_breadahead(sb, phys + sec);
66 	}
67 	brelse(bh);
68 }
69 
70 /* Returns the inode number of the directory entry at offset pos. If bh is
71    non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
72    returned in bh.
73    AV. Most often we do it item-by-item. Makes sense to optimize.
74    AV. OK, there we go: if both bh and de are non-NULL we assume that we just
75    AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
76    AV. It's done in fat_get_entry() (inlined), here the slow case lives.
77    AV. Additionally, when we return -1 (i.e. reached the end of directory)
78    AV. we make bh NULL.
79  */
80 static int fat__get_entry(struct inode *dir, loff_t *pos,
81 			  struct buffer_head **bh, struct msdos_dir_entry **de)
82 {
83 	struct super_block *sb = dir->i_sb;
84 	sector_t phys, iblock;
85 	unsigned long mapped_blocks;
86 	int err, offset;
87 
88 next:
89 	if (*bh)
90 		brelse(*bh);
91 
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 
116 static 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  */
141 static 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 
181 static 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 
192 static inline int
193 fat_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 
205 static inline int
206 fat_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 
233 static inline int
234 fat_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 
254 static 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 
267 enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };
268 
269 /**
270  * fat_parse_long - Parse extended directory entry.
271  *
272  * This function returns zero on success, negative value on error, or one of
273  * the following:
274  *
275  * %PARSE_INVALID - Directory entry is invalid.
276  * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
277  * %PARSE_EOF - Directory has no more entries.
278  */
279 static int fat_parse_long(struct inode *dir, loff_t *pos,
280 			  struct buffer_head **bh, struct msdos_dir_entry **de,
281 			  wchar_t **unicode, unsigned char *nr_slots)
282 {
283 	struct msdos_dir_slot *ds;
284 	unsigned char id, slot, slots, alias_checksum;
285 
286 	if (!*unicode) {
287 		*unicode = __getname();
288 		if (!*unicode) {
289 			brelse(*bh);
290 			return -ENOMEM;
291 		}
292 	}
293 parse_long:
294 	slots = 0;
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 	/* see namei.c, msdos_format_name */
373 	if (work[0] == 0x05)
374 		work[0] = 0xE5;
375 
376 	/* Filename */
377 	for (i = 0, j = 0; i < 8;) {
378 		c = work[i];
379 		if (!c)
380 			break;
381 		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
382 					&uni_name[j++], opt_shortname,
383 					de->lcase & CASE_LOWER_BASE);
384 		if (chl <= 1) {
385 			if (!isvfat)
386 				ptname[i] = nocase ? c : fat_tolower(c);
387 			i++;
388 			if (c != ' ') {
389 				name_len = i;
390 				uni_len  = j;
391 			}
392 		} else {
393 			uni_len = j;
394 			if (isvfat)
395 				i += min(chl, 8-i);
396 			else {
397 				for (chi = 0; chi < chl && i < 8; chi++, i++)
398 					ptname[i] = work[i];
399 			}
400 			if (chl)
401 				name_len = i;
402 		}
403 	}
404 
405 	i = name_len;
406 	j = uni_len;
407 	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
408 	if (!isvfat)
409 		ptname[i] = '.';
410 	i++;
411 
412 	/* Extension */
413 	for (k = 8; k < MSDOS_NAME;) {
414 		c = work[k];
415 		if (!c)
416 			break;
417 		chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
418 					&uni_name[j++], opt_shortname,
419 					de->lcase & CASE_LOWER_EXT);
420 		if (chl <= 1) {
421 			k++;
422 			if (!isvfat)
423 				ptname[i] = nocase ? c : fat_tolower(c);
424 			i++;
425 			if (c != ' ') {
426 				name_len = i;
427 				uni_len  = j;
428 			}
429 		} else {
430 			uni_len = j;
431 			if (isvfat) {
432 				int offset = min(chl, MSDOS_NAME-k);
433 				k += offset;
434 				i += offset;
435 			} else {
436 				for (chi = 0; chi < chl && k < MSDOS_NAME;
437 				     chi++, i++, k++) {
438 						ptname[i] = work[k];
439 				}
440 			}
441 			if (chl)
442 				name_len = i;
443 		}
444 	}
445 
446 	if (name_len > 0) {
447 		name_len += dotoffset;
448 
449 		if (sbi->options.isvfat) {
450 			uni_name[uni_len] = 0x0000;
451 			name_len = fat_uni_to_x8(sb, uni_name, name,
452 						 FAT_MAX_SHORT_SIZE);
453 		}
454 	}
455 
456 	return name_len;
457 }
458 
459 /*
460  * Return values: negative -> error/not found, 0 -> found.
461  */
462 int fat_search_long(struct inode *inode, const unsigned char *name,
463 		    int name_len, struct fat_slot_info *sinfo)
464 {
465 	struct super_block *sb = inode->i_sb;
466 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
467 	struct buffer_head *bh = NULL;
468 	struct msdos_dir_entry *de;
469 	unsigned char nr_slots;
470 	wchar_t *unicode = NULL;
471 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
472 	loff_t cpos = 0;
473 	int err, len;
474 
475 	err = -ENOENT;
476 	while (1) {
477 		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
478 			goto end_of_dir;
479 parse_record:
480 		nr_slots = 0;
481 		if (de->name[0] == DELETED_FLAG)
482 			continue;
483 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
484 			continue;
485 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
486 			continue;
487 		if (de->attr == ATTR_EXT) {
488 			int status = fat_parse_long(inode, &cpos, &bh, &de,
489 						    &unicode, &nr_slots);
490 			if (status < 0) {
491 				err = status;
492 				goto end_of_dir;
493 			} else if (status == PARSE_INVALID)
494 				continue;
495 			else if (status == PARSE_NOT_LONGNAME)
496 				goto parse_record;
497 			else if (status == PARSE_EOF)
498 				goto end_of_dir;
499 		}
500 
501 		/* Never prepend '.' to hidden files here.
502 		 * That is done only for msdos mounts (and only when
503 		 * 'dotsOK=yes'); if we are executing here, it is in the
504 		 * context of a vfat mount.
505 		 */
506 		len = fat_parse_short(sb, de, bufname, 0);
507 		if (len == 0)
508 			continue;
509 
510 		/* Compare shortname */
511 		if (fat_name_match(sbi, name, name_len, bufname, len))
512 			goto found;
513 
514 		if (nr_slots) {
515 			void *longname = unicode + FAT_MAX_UNI_CHARS;
516 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
517 
518 			/* Compare longname */
519 			len = fat_uni_to_x8(sb, unicode, longname, size);
520 			if (fat_name_match(sbi, name, name_len, longname, len))
521 				goto found;
522 		}
523 	}
524 
525 found:
526 	nr_slots++;	/* include the de */
527 	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
528 	sinfo->nr_slots = nr_slots;
529 	sinfo->de = de;
530 	sinfo->bh = bh;
531 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
532 	err = 0;
533 end_of_dir:
534 	if (unicode)
535 		__putname(unicode);
536 
537 	return err;
538 }
539 EXPORT_SYMBOL_GPL(fat_search_long);
540 
541 struct fat_ioctl_filldir_callback {
542 	struct dir_context ctx;
543 	void __user *dirent;
544 	int result;
545 	/* for dir ioctl */
546 	const char *longname;
547 	int long_len;
548 	const char *shortname;
549 	int short_len;
550 };
551 
552 static int __fat_readdir(struct inode *inode, struct file *file,
553 			 struct dir_context *ctx, int short_only,
554 			 struct fat_ioctl_filldir_callback *both)
555 {
556 	struct super_block *sb = inode->i_sb;
557 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
558 	struct buffer_head *bh;
559 	struct msdos_dir_entry *de;
560 	unsigned char nr_slots;
561 	wchar_t *unicode = NULL;
562 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
563 	int isvfat = sbi->options.isvfat;
564 	const char *fill_name = NULL;
565 	int fake_offset = 0;
566 	loff_t cpos;
567 	int short_len = 0, fill_len = 0;
568 	int ret = 0;
569 
570 	mutex_lock(&sbi->s_lock);
571 
572 	cpos = ctx->pos;
573 	/* Fake . and .. for the root directory. */
574 	if (inode->i_ino == MSDOS_ROOT_INO) {
575 		if (!dir_emit_dots(file, ctx))
576 			goto out;
577 		if (ctx->pos == 2) {
578 			fake_offset = 1;
579 			cpos = 0;
580 		}
581 	}
582 	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
583 		ret = -ENOENT;
584 		goto out;
585 	}
586 
587 	bh = NULL;
588 get_new:
589 	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
590 		goto end_of_dir;
591 parse_record:
592 	nr_slots = 0;
593 	/*
594 	 * Check for long filename entry, but if short_only, we don't
595 	 * need to parse long filename.
596 	 */
597 	if (isvfat && !short_only) {
598 		if (de->name[0] == DELETED_FLAG)
599 			goto record_end;
600 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
601 			goto record_end;
602 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
603 			goto record_end;
604 	} else {
605 		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
606 			goto record_end;
607 	}
608 
609 	if (isvfat && de->attr == ATTR_EXT) {
610 		int status = fat_parse_long(inode, &cpos, &bh, &de,
611 					    &unicode, &nr_slots);
612 		if (status < 0) {
613 			bh = NULL;
614 			ret = status;
615 			goto end_of_dir;
616 		} else if (status == PARSE_INVALID)
617 			goto record_end;
618 		else if (status == PARSE_NOT_LONGNAME)
619 			goto parse_record;
620 		else if (status == PARSE_EOF)
621 			goto end_of_dir;
622 
623 		if (nr_slots) {
624 			void *longname = unicode + FAT_MAX_UNI_CHARS;
625 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
626 			int len = fat_uni_to_x8(sb, unicode, longname, size);
627 
628 			fill_name = longname;
629 			fill_len = len;
630 			/* !both && !short_only, so we don't need shortname. */
631 			if (!both)
632 				goto start_filldir;
633 
634 			short_len = fat_parse_short(sb, de, bufname,
635 						    sbi->options.dotsOK);
636 			if (short_len == 0)
637 				goto record_end;
638 			/* hack for fat_ioctl_filldir() */
639 			both->longname = fill_name;
640 			both->long_len = fill_len;
641 			both->shortname = bufname;
642 			both->short_len = short_len;
643 			fill_name = NULL;
644 			fill_len = 0;
645 			goto start_filldir;
646 		}
647 	}
648 
649 	short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
650 	if (short_len == 0)
651 		goto record_end;
652 
653 	fill_name = bufname;
654 	fill_len = short_len;
655 
656 start_filldir:
657 	ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
658 	if (fake_offset && ctx->pos < 2)
659 		ctx->pos = 2;
660 
661 	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
662 		if (!dir_emit_dot(file, ctx))
663 			goto fill_failed;
664 	} else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
665 		if (!dir_emit_dotdot(file, ctx))
666 			goto fill_failed;
667 	} else {
668 		unsigned long inum;
669 		loff_t i_pos = fat_make_i_pos(sb, bh, de);
670 		struct inode *tmp = fat_iget(sb, i_pos);
671 		if (tmp) {
672 			inum = tmp->i_ino;
673 			iput(tmp);
674 		} else
675 			inum = iunique(sb, MSDOS_ROOT_INO);
676 		if (!dir_emit(ctx, fill_name, fill_len, inum,
677 			    (de->attr & ATTR_DIR) ? DT_DIR : DT_REG))
678 			goto fill_failed;
679 	}
680 
681 record_end:
682 	fake_offset = 0;
683 	ctx->pos = cpos;
684 	goto get_new;
685 
686 end_of_dir:
687 	if (fake_offset && cpos < 2)
688 		ctx->pos = 2;
689 	else
690 		ctx->pos = cpos;
691 fill_failed:
692 	brelse(bh);
693 	if (unicode)
694 		__putname(unicode);
695 out:
696 	mutex_unlock(&sbi->s_lock);
697 
698 	return ret;
699 }
700 
701 static int fat_readdir(struct file *file, struct dir_context *ctx)
702 {
703 	return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
704 }
705 
706 #define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
707 static int func(struct dir_context *ctx, const char *name, int name_len,   \
708 			     loff_t offset, u64 ino, unsigned int d_type)  \
709 {									   \
710 	struct fat_ioctl_filldir_callback *buf =			   \
711 		container_of(ctx, struct fat_ioctl_filldir_callback, ctx); \
712 	struct dirent_type __user *d1 = buf->dirent;			   \
713 	struct dirent_type __user *d2 = d1 + 1;				   \
714 									   \
715 	if (buf->result)						   \
716 		return -EINVAL;						   \
717 	buf->result++;							   \
718 									   \
719 	if (name != NULL) {						   \
720 		/* dirent has only short name */			   \
721 		if (name_len >= sizeof(d1->d_name))			   \
722 			name_len = sizeof(d1->d_name) - 1;		   \
723 									   \
724 		if (put_user(0, d2->d_name)			||	   \
725 		    put_user(0, &d2->d_reclen)			||	   \
726 		    copy_to_user(d1->d_name, name, name_len)	||	   \
727 		    put_user(0, d1->d_name + name_len)		||	   \
728 		    put_user(name_len, &d1->d_reclen))			   \
729 			goto efault;					   \
730 	} else {							   \
731 		/* dirent has short and long name */			   \
732 		const char *longname = buf->longname;			   \
733 		int long_len = buf->long_len;				   \
734 		const char *shortname = buf->shortname;			   \
735 		int short_len = buf->short_len;				   \
736 									   \
737 		if (long_len >= sizeof(d1->d_name))			   \
738 			long_len = sizeof(d1->d_name) - 1;		   \
739 		if (short_len >= sizeof(d1->d_name))			   \
740 			short_len = sizeof(d1->d_name) - 1;		   \
741 									   \
742 		if (copy_to_user(d2->d_name, longname, long_len)	|| \
743 		    put_user(0, d2->d_name + long_len)			|| \
744 		    put_user(long_len, &d2->d_reclen)			|| \
745 		    put_user(ino, &d2->d_ino)				|| \
746 		    put_user(offset, &d2->d_off)			|| \
747 		    copy_to_user(d1->d_name, shortname, short_len)	|| \
748 		    put_user(0, d1->d_name + short_len)			|| \
749 		    put_user(short_len, &d1->d_reclen))			   \
750 			goto efault;					   \
751 	}								   \
752 	return 0;							   \
753 efault:									   \
754 	buf->result = -EFAULT;						   \
755 	return -EFAULT;							   \
756 }
757 
758 FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
759 
760 static int fat_ioctl_readdir(struct inode *inode, struct file *file,
761 			     void __user *dirent, filldir_t filldir,
762 			     int short_only, int both)
763 {
764 	struct fat_ioctl_filldir_callback buf = {
765 		.ctx.actor = filldir,
766 		.dirent = dirent
767 	};
768 	int ret;
769 
770 	buf.dirent = dirent;
771 	buf.result = 0;
772 	inode_lock_shared(inode);
773 	buf.ctx.pos = file->f_pos;
774 	ret = -ENOENT;
775 	if (!IS_DEADDIR(inode)) {
776 		ret = __fat_readdir(inode, file, &buf.ctx,
777 				    short_only, both ? &buf : NULL);
778 		file->f_pos = buf.ctx.pos;
779 	}
780 	inode_unlock_shared(inode);
781 	if (ret >= 0)
782 		ret = buf.result;
783 	return ret;
784 }
785 
786 static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
787 			  unsigned long arg)
788 {
789 	struct inode *inode = file_inode(filp);
790 	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
791 	int short_only, both;
792 
793 	switch (cmd) {
794 	case VFAT_IOCTL_READDIR_SHORT:
795 		short_only = 1;
796 		both = 0;
797 		break;
798 	case VFAT_IOCTL_READDIR_BOTH:
799 		short_only = 0;
800 		both = 1;
801 		break;
802 	default:
803 		return fat_generic_ioctl(filp, cmd, arg);
804 	}
805 
806 	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct __fat_dirent[2])))
807 		return -EFAULT;
808 	/*
809 	 * Yes, we don't need this put_user() absolutely. However old
810 	 * code didn't return the right value. So, app use this value,
811 	 * in order to check whether it is EOF.
812 	 */
813 	if (put_user(0, &d1->d_reclen))
814 		return -EFAULT;
815 
816 	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
817 				 short_only, both);
818 }
819 
820 #ifdef CONFIG_COMPAT
821 #define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
822 #define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])
823 
824 FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
825 
826 static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
827 				 unsigned long arg)
828 {
829 	struct inode *inode = file_inode(filp);
830 	struct compat_dirent __user *d1 = compat_ptr(arg);
831 	int short_only, both;
832 
833 	switch (cmd) {
834 	case VFAT_IOCTL_READDIR_SHORT32:
835 		short_only = 1;
836 		both = 0;
837 		break;
838 	case VFAT_IOCTL_READDIR_BOTH32:
839 		short_only = 0;
840 		both = 1;
841 		break;
842 	default:
843 		return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
844 	}
845 
846 	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct compat_dirent[2])))
847 		return -EFAULT;
848 	/*
849 	 * Yes, we don't need this put_user() absolutely. However old
850 	 * code didn't return the right value. So, app use this value,
851 	 * in order to check whether it is EOF.
852 	 */
853 	if (put_user(0, &d1->d_reclen))
854 		return -EFAULT;
855 
856 	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
857 				 short_only, both);
858 }
859 #endif /* CONFIG_COMPAT */
860 
861 const struct file_operations fat_dir_operations = {
862 	.llseek		= generic_file_llseek,
863 	.read		= generic_read_dir,
864 	.iterate_shared	= fat_readdir,
865 	.unlocked_ioctl	= fat_dir_ioctl,
866 #ifdef CONFIG_COMPAT
867 	.compat_ioctl	= fat_compat_dir_ioctl,
868 #endif
869 	.fsync		= fat_file_fsync,
870 };
871 
872 static int fat_get_short_entry(struct inode *dir, loff_t *pos,
873 			       struct buffer_head **bh,
874 			       struct msdos_dir_entry **de)
875 {
876 	while (fat_get_entry(dir, pos, bh, de) >= 0) {
877 		/* free entry or long name entry or volume label */
878 		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
879 			return 0;
880 	}
881 	return -ENOENT;
882 }
883 
884 /*
885  * The ".." entry can not provide the "struct fat_slot_info" information
886  * for inode, nor a usable i_pos. So, this function provides some information
887  * only.
888  *
889  * Since this function walks through the on-disk inodes within a directory,
890  * callers are responsible for taking any locks necessary to prevent the
891  * directory from changing.
892  */
893 int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
894 			 struct msdos_dir_entry **de)
895 {
896 	loff_t offset = 0;
897 
898 	*de = NULL;
899 	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
900 		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
901 			return 0;
902 	}
903 	return -ENOENT;
904 }
905 EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
906 
907 /* See if directory is empty */
908 int fat_dir_empty(struct inode *dir)
909 {
910 	struct buffer_head *bh;
911 	struct msdos_dir_entry *de;
912 	loff_t cpos;
913 	int result = 0;
914 
915 	bh = NULL;
916 	cpos = 0;
917 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
918 		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
919 		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
920 			result = -ENOTEMPTY;
921 			break;
922 		}
923 	}
924 	brelse(bh);
925 	return result;
926 }
927 EXPORT_SYMBOL_GPL(fat_dir_empty);
928 
929 /*
930  * fat_subdirs counts the number of sub-directories of dir. It can be run
931  * on directories being created.
932  */
933 int fat_subdirs(struct inode *dir)
934 {
935 	struct buffer_head *bh;
936 	struct msdos_dir_entry *de;
937 	loff_t cpos;
938 	int count = 0;
939 
940 	bh = NULL;
941 	cpos = 0;
942 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
943 		if (de->attr & ATTR_DIR)
944 			count++;
945 	}
946 	brelse(bh);
947 	return count;
948 }
949 
950 /*
951  * Scans a directory for a given file (name points to its formatted name).
952  * Returns an error code or zero.
953  */
954 int fat_scan(struct inode *dir, const unsigned char *name,
955 	     struct fat_slot_info *sinfo)
956 {
957 	struct super_block *sb = dir->i_sb;
958 
959 	sinfo->slot_off = 0;
960 	sinfo->bh = NULL;
961 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
962 				   &sinfo->de) >= 0) {
963 		if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
964 			sinfo->slot_off -= sizeof(*sinfo->de);
965 			sinfo->nr_slots = 1;
966 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
967 			return 0;
968 		}
969 	}
970 	return -ENOENT;
971 }
972 EXPORT_SYMBOL_GPL(fat_scan);
973 
974 /*
975  * Scans a directory for a given logstart.
976  * Returns an error code or zero.
977  */
978 int fat_scan_logstart(struct inode *dir, int i_logstart,
979 		      struct fat_slot_info *sinfo)
980 {
981 	struct super_block *sb = dir->i_sb;
982 
983 	sinfo->slot_off = 0;
984 	sinfo->bh = NULL;
985 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
986 				   &sinfo->de) >= 0) {
987 		if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
988 			sinfo->slot_off -= sizeof(*sinfo->de);
989 			sinfo->nr_slots = 1;
990 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
991 			return 0;
992 		}
993 	}
994 	return -ENOENT;
995 }
996 
997 static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
998 {
999 	struct super_block *sb = dir->i_sb;
1000 	struct buffer_head *bh;
1001 	struct msdos_dir_entry *de, *endp;
1002 	int err = 0, orig_slots;
1003 
1004 	while (nr_slots) {
1005 		bh = NULL;
1006 		if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1007 			err = -EIO;
1008 			break;
1009 		}
1010 
1011 		orig_slots = nr_slots;
1012 		endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1013 		while (nr_slots && de < endp) {
1014 			de->name[0] = DELETED_FLAG;
1015 			de++;
1016 			nr_slots--;
1017 		}
1018 		mark_buffer_dirty_inode(bh, dir);
1019 		if (IS_DIRSYNC(dir))
1020 			err = sync_dirty_buffer(bh);
1021 		brelse(bh);
1022 		if (err)
1023 			break;
1024 
1025 		/* pos is *next* de's position, so this does `- sizeof(de)' */
1026 		pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1027 	}
1028 
1029 	return err;
1030 }
1031 
1032 int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1033 {
1034 	struct super_block *sb = dir->i_sb;
1035 	struct msdos_dir_entry *de;
1036 	struct buffer_head *bh;
1037 	int err = 0, nr_slots;
1038 
1039 	/*
1040 	 * First stage: Remove the shortname. By this, the directory
1041 	 * entry is removed.
1042 	 */
1043 	nr_slots = sinfo->nr_slots;
1044 	de = sinfo->de;
1045 	sinfo->de = NULL;
1046 	bh = sinfo->bh;
1047 	sinfo->bh = NULL;
1048 	while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1049 		de->name[0] = DELETED_FLAG;
1050 		de--;
1051 		nr_slots--;
1052 	}
1053 	mark_buffer_dirty_inode(bh, dir);
1054 	if (IS_DIRSYNC(dir))
1055 		err = sync_dirty_buffer(bh);
1056 	brelse(bh);
1057 	if (err)
1058 		return err;
1059 	dir->i_version++;
1060 
1061 	if (nr_slots) {
1062 		/*
1063 		 * Second stage: remove the remaining longname slots.
1064 		 * (This directory entry is already removed, and so return
1065 		 * the success)
1066 		 */
1067 		err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1068 		if (err) {
1069 			fat_msg(sb, KERN_WARNING,
1070 			       "Couldn't remove the long name slots");
1071 		}
1072 	}
1073 
1074 	dir->i_mtime = dir->i_atime = current_time(dir);
1075 	if (IS_DIRSYNC(dir))
1076 		(void)fat_sync_inode(dir);
1077 	else
1078 		mark_inode_dirty(dir);
1079 
1080 	return 0;
1081 }
1082 EXPORT_SYMBOL_GPL(fat_remove_entries);
1083 
1084 static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1085 			      struct buffer_head **bhs, int nr_bhs)
1086 {
1087 	struct super_block *sb = dir->i_sb;
1088 	sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1089 	int err, i, n;
1090 
1091 	/* Zeroing the unused blocks on this cluster */
1092 	blknr += nr_used;
1093 	n = nr_used;
1094 	while (blknr < last_blknr) {
1095 		bhs[n] = sb_getblk(sb, blknr);
1096 		if (!bhs[n]) {
1097 			err = -ENOMEM;
1098 			goto error;
1099 		}
1100 		memset(bhs[n]->b_data, 0, sb->s_blocksize);
1101 		set_buffer_uptodate(bhs[n]);
1102 		mark_buffer_dirty_inode(bhs[n], dir);
1103 
1104 		n++;
1105 		blknr++;
1106 		if (n == nr_bhs) {
1107 			if (IS_DIRSYNC(dir)) {
1108 				err = fat_sync_bhs(bhs, n);
1109 				if (err)
1110 					goto error;
1111 			}
1112 			for (i = 0; i < n; i++)
1113 				brelse(bhs[i]);
1114 			n = 0;
1115 		}
1116 	}
1117 	if (IS_DIRSYNC(dir)) {
1118 		err = fat_sync_bhs(bhs, n);
1119 		if (err)
1120 			goto error;
1121 	}
1122 	for (i = 0; i < n; i++)
1123 		brelse(bhs[i]);
1124 
1125 	return 0;
1126 
1127 error:
1128 	for (i = 0; i < n; i++)
1129 		bforget(bhs[i]);
1130 	return err;
1131 }
1132 
1133 int fat_alloc_new_dir(struct inode *dir, struct timespec *ts)
1134 {
1135 	struct super_block *sb = dir->i_sb;
1136 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1137 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1138 	struct msdos_dir_entry *de;
1139 	sector_t blknr;
1140 	__le16 date, time;
1141 	u8 time_cs;
1142 	int err, cluster;
1143 
1144 	err = fat_alloc_clusters(dir, &cluster, 1);
1145 	if (err)
1146 		goto error;
1147 
1148 	blknr = fat_clus_to_blknr(sbi, cluster);
1149 	bhs[0] = sb_getblk(sb, blknr);
1150 	if (!bhs[0]) {
1151 		err = -ENOMEM;
1152 		goto error_free;
1153 	}
1154 
1155 	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1156 
1157 	de = (struct msdos_dir_entry *)bhs[0]->b_data;
1158 	/* filling the new directory slots ("." and ".." entries) */
1159 	memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1160 	memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1161 	de->attr = de[1].attr = ATTR_DIR;
1162 	de[0].lcase = de[1].lcase = 0;
1163 	de[0].time = de[1].time = time;
1164 	de[0].date = de[1].date = date;
1165 	if (sbi->options.isvfat) {
1166 		/* extra timestamps */
1167 		de[0].ctime = de[1].ctime = time;
1168 		de[0].ctime_cs = de[1].ctime_cs = time_cs;
1169 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1170 	} else {
1171 		de[0].ctime = de[1].ctime = 0;
1172 		de[0].ctime_cs = de[1].ctime_cs = 0;
1173 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1174 	}
1175 	fat_set_start(&de[0], cluster);
1176 	fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1177 	de[0].size = de[1].size = 0;
1178 	memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1179 	set_buffer_uptodate(bhs[0]);
1180 	mark_buffer_dirty_inode(bhs[0], dir);
1181 
1182 	err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1183 	if (err)
1184 		goto error_free;
1185 
1186 	return cluster;
1187 
1188 error_free:
1189 	fat_free_clusters(dir, cluster);
1190 error:
1191 	return err;
1192 }
1193 EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1194 
1195 static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1196 			       int *nr_cluster, struct msdos_dir_entry **de,
1197 			       struct buffer_head **bh, loff_t *i_pos)
1198 {
1199 	struct super_block *sb = dir->i_sb;
1200 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1201 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1202 	sector_t blknr, start_blknr, last_blknr;
1203 	unsigned long size, copy;
1204 	int err, i, n, offset, cluster[2];
1205 
1206 	/*
1207 	 * The minimum cluster size is 512bytes, and maximum entry
1208 	 * size is 32*slots (672bytes).  So, iff the cluster size is
1209 	 * 512bytes, we may need two clusters.
1210 	 */
1211 	size = nr_slots * sizeof(struct msdos_dir_entry);
1212 	*nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1213 	BUG_ON(*nr_cluster > 2);
1214 
1215 	err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1216 	if (err)
1217 		goto error;
1218 
1219 	/*
1220 	 * First stage: Fill the directory entry.  NOTE: This cluster
1221 	 * is not referenced from any inode yet, so updates order is
1222 	 * not important.
1223 	 */
1224 	i = n = copy = 0;
1225 	do {
1226 		start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1227 		last_blknr = start_blknr + sbi->sec_per_clus;
1228 		while (blknr < last_blknr) {
1229 			bhs[n] = sb_getblk(sb, blknr);
1230 			if (!bhs[n]) {
1231 				err = -ENOMEM;
1232 				goto error_nomem;
1233 			}
1234 
1235 			/* fill the directory entry */
1236 			copy = min(size, sb->s_blocksize);
1237 			memcpy(bhs[n]->b_data, slots, copy);
1238 			slots += copy;
1239 			size -= copy;
1240 			set_buffer_uptodate(bhs[n]);
1241 			mark_buffer_dirty_inode(bhs[n], dir);
1242 			if (!size)
1243 				break;
1244 			n++;
1245 			blknr++;
1246 		}
1247 	} while (++i < *nr_cluster);
1248 
1249 	memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1250 	offset = copy - sizeof(struct msdos_dir_entry);
1251 	get_bh(bhs[n]);
1252 	*bh = bhs[n];
1253 	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1254 	*i_pos = fat_make_i_pos(sb, *bh, *de);
1255 
1256 	/* Second stage: clear the rest of cluster, and write outs */
1257 	err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1258 	if (err)
1259 		goto error_free;
1260 
1261 	return cluster[0];
1262 
1263 error_free:
1264 	brelse(*bh);
1265 	*bh = NULL;
1266 	n = 0;
1267 error_nomem:
1268 	for (i = 0; i < n; i++)
1269 		bforget(bhs[i]);
1270 	fat_free_clusters(dir, cluster[0]);
1271 error:
1272 	return err;
1273 }
1274 
1275 int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1276 		    struct fat_slot_info *sinfo)
1277 {
1278 	struct super_block *sb = dir->i_sb;
1279 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1280 	struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1281 	struct msdos_dir_entry *uninitialized_var(de);
1282 	int err, free_slots, i, nr_bhs;
1283 	loff_t pos, i_pos;
1284 
1285 	sinfo->nr_slots = nr_slots;
1286 
1287 	/* First stage: search free directory entries */
1288 	free_slots = nr_bhs = 0;
1289 	bh = prev = NULL;
1290 	pos = 0;
1291 	err = -ENOSPC;
1292 	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1293 		/* check the maximum size of directory */
1294 		if (pos >= FAT_MAX_DIR_SIZE)
1295 			goto error;
1296 
1297 		if (IS_FREE(de->name)) {
1298 			if (prev != bh) {
1299 				get_bh(bh);
1300 				bhs[nr_bhs] = prev = bh;
1301 				nr_bhs++;
1302 			}
1303 			free_slots++;
1304 			if (free_slots == nr_slots)
1305 				goto found;
1306 		} else {
1307 			for (i = 0; i < nr_bhs; i++)
1308 				brelse(bhs[i]);
1309 			prev = NULL;
1310 			free_slots = nr_bhs = 0;
1311 		}
1312 	}
1313 	if (dir->i_ino == MSDOS_ROOT_INO) {
1314 		if (sbi->fat_bits != 32)
1315 			goto error;
1316 	} else if (MSDOS_I(dir)->i_start == 0) {
1317 		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1318 		       MSDOS_I(dir)->i_pos);
1319 		err = -EIO;
1320 		goto error;
1321 	}
1322 
1323 found:
1324 	err = 0;
1325 	pos -= free_slots * sizeof(*de);
1326 	nr_slots -= free_slots;
1327 	if (free_slots) {
1328 		/*
1329 		 * Second stage: filling the free entries with new entries.
1330 		 * NOTE: If this slots has shortname, first, we write
1331 		 * the long name slots, then write the short name.
1332 		 */
1333 		int size = free_slots * sizeof(*de);
1334 		int offset = pos & (sb->s_blocksize - 1);
1335 		int long_bhs = nr_bhs - (nr_slots == 0);
1336 
1337 		/* Fill the long name slots. */
1338 		for (i = 0; i < long_bhs; i++) {
1339 			int copy = min_t(int, sb->s_blocksize - offset, size);
1340 			memcpy(bhs[i]->b_data + offset, slots, copy);
1341 			mark_buffer_dirty_inode(bhs[i], dir);
1342 			offset = 0;
1343 			slots += copy;
1344 			size -= copy;
1345 		}
1346 		if (long_bhs && IS_DIRSYNC(dir))
1347 			err = fat_sync_bhs(bhs, long_bhs);
1348 		if (!err && i < nr_bhs) {
1349 			/* Fill the short name slot. */
1350 			int copy = min_t(int, sb->s_blocksize - offset, size);
1351 			memcpy(bhs[i]->b_data + offset, slots, copy);
1352 			mark_buffer_dirty_inode(bhs[i], dir);
1353 			if (IS_DIRSYNC(dir))
1354 				err = sync_dirty_buffer(bhs[i]);
1355 		}
1356 		for (i = 0; i < nr_bhs; i++)
1357 			brelse(bhs[i]);
1358 		if (err)
1359 			goto error_remove;
1360 	}
1361 
1362 	if (nr_slots) {
1363 		int cluster, nr_cluster;
1364 
1365 		/*
1366 		 * Third stage: allocate the cluster for new entries.
1367 		 * And initialize the cluster with new entries, then
1368 		 * add the cluster to dir.
1369 		 */
1370 		cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1371 					      &de, &bh, &i_pos);
1372 		if (cluster < 0) {
1373 			err = cluster;
1374 			goto error_remove;
1375 		}
1376 		err = fat_chain_add(dir, cluster, nr_cluster);
1377 		if (err) {
1378 			fat_free_clusters(dir, cluster);
1379 			goto error_remove;
1380 		}
1381 		if (dir->i_size & (sbi->cluster_size - 1)) {
1382 			fat_fs_error(sb, "Odd directory size");
1383 			dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1384 				& ~((loff_t)sbi->cluster_size - 1);
1385 		}
1386 		dir->i_size += nr_cluster << sbi->cluster_bits;
1387 		MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1388 	}
1389 	sinfo->slot_off = pos;
1390 	sinfo->de = de;
1391 	sinfo->bh = bh;
1392 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1393 
1394 	return 0;
1395 
1396 error:
1397 	brelse(bh);
1398 	for (i = 0; i < nr_bhs; i++)
1399 		brelse(bhs[i]);
1400 	return err;
1401 
1402 error_remove:
1403 	brelse(bh);
1404 	if (free_slots)
1405 		__fat_remove_entries(dir, pos, free_slots);
1406 	return err;
1407 }
1408 EXPORT_SYMBOL_GPL(fat_add_entries);
1409