xref: /openbmc/linux/fs/fat/dir.c (revision 4a3fad70)
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 	ds = (struct msdos_dir_slot *)*de;
295 	id = ds->id;
296 	if (!(id & 0x40))
297 		return PARSE_INVALID;
298 	slots = id & ~0x40;
299 	if (slots > 20 || !slots)	/* ceil(256 * 2 / 26) */
300 		return PARSE_INVALID;
301 	*nr_slots = slots;
302 	alias_checksum = ds->alias_checksum;
303 
304 	slot = slots;
305 	while (1) {
306 		int offset;
307 
308 		slot--;
309 		offset = slot * 13;
310 		fat16_towchar(*unicode + offset, ds->name0_4, 5);
311 		fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
312 		fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);
313 
314 		if (ds->id & 0x40)
315 			(*unicode)[offset + 13] = 0;
316 		if (fat_get_entry(dir, pos, bh, de) < 0)
317 			return PARSE_EOF;
318 		if (slot == 0)
319 			break;
320 		ds = (struct msdos_dir_slot *)*de;
321 		if (ds->attr != ATTR_EXT)
322 			return PARSE_NOT_LONGNAME;
323 		if ((ds->id & ~0x40) != slot)
324 			goto parse_long;
325 		if (ds->alias_checksum != alias_checksum)
326 			goto parse_long;
327 	}
328 	if ((*de)->name[0] == DELETED_FLAG)
329 		return PARSE_INVALID;
330 	if ((*de)->attr == ATTR_EXT)
331 		goto parse_long;
332 	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
333 		return PARSE_INVALID;
334 	if (fat_checksum((*de)->name) != alias_checksum)
335 		*nr_slots = 0;
336 
337 	return 0;
338 }
339 
340 /**
341  * fat_parse_short - Parse MS-DOS (short) directory entry.
342  * @sb:		superblock
343  * @de:		directory entry to parse
344  * @name:	FAT_MAX_SHORT_SIZE array in which to place extracted name
345  * @dot_hidden:	Nonzero == prepend '.' to names with ATTR_HIDDEN
346  *
347  * Returns the number of characters extracted into 'name'.
348  */
349 static int fat_parse_short(struct super_block *sb,
350 			   const struct msdos_dir_entry *de,
351 			   unsigned char *name, int dot_hidden)
352 {
353 	const struct msdos_sb_info *sbi = MSDOS_SB(sb);
354 	int isvfat = sbi->options.isvfat;
355 	int nocase = sbi->options.nocase;
356 	unsigned short opt_shortname = sbi->options.shortname;
357 	struct nls_table *nls_disk = sbi->nls_disk;
358 	wchar_t uni_name[14];
359 	unsigned char c, work[MSDOS_NAME];
360 	unsigned char *ptname = name;
361 	int chi, chl, i, j, k;
362 	int dotoffset = 0;
363 	int name_len = 0, uni_len = 0;
364 
365 	if (!isvfat && dot_hidden && (de->attr & ATTR_HIDDEN)) {
366 		*ptname++ = '.';
367 		dotoffset = 1;
368 	}
369 
370 	memcpy(work, de->name, sizeof(work));
371 	/* see namei.c, msdos_format_name */
372 	if (work[0] == 0x05)
373 		work[0] = 0xE5;
374 
375 	/* Filename */
376 	for (i = 0, j = 0; i < 8;) {
377 		c = work[i];
378 		if (!c)
379 			break;
380 		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
381 					&uni_name[j++], opt_shortname,
382 					de->lcase & CASE_LOWER_BASE);
383 		if (chl <= 1) {
384 			if (!isvfat)
385 				ptname[i] = nocase ? c : fat_tolower(c);
386 			i++;
387 			if (c != ' ') {
388 				name_len = i;
389 				uni_len  = j;
390 			}
391 		} else {
392 			uni_len = j;
393 			if (isvfat)
394 				i += min(chl, 8-i);
395 			else {
396 				for (chi = 0; chi < chl && i < 8; chi++, i++)
397 					ptname[i] = work[i];
398 			}
399 			if (chl)
400 				name_len = i;
401 		}
402 	}
403 
404 	i = name_len;
405 	j = uni_len;
406 	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
407 	if (!isvfat)
408 		ptname[i] = '.';
409 	i++;
410 
411 	/* Extension */
412 	for (k = 8; k < MSDOS_NAME;) {
413 		c = work[k];
414 		if (!c)
415 			break;
416 		chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
417 					&uni_name[j++], opt_shortname,
418 					de->lcase & CASE_LOWER_EXT);
419 		if (chl <= 1) {
420 			k++;
421 			if (!isvfat)
422 				ptname[i] = nocase ? c : fat_tolower(c);
423 			i++;
424 			if (c != ' ') {
425 				name_len = i;
426 				uni_len  = j;
427 			}
428 		} else {
429 			uni_len = j;
430 			if (isvfat) {
431 				int offset = min(chl, MSDOS_NAME-k);
432 				k += offset;
433 				i += offset;
434 			} else {
435 				for (chi = 0; chi < chl && k < MSDOS_NAME;
436 				     chi++, i++, k++) {
437 						ptname[i] = work[k];
438 				}
439 			}
440 			if (chl)
441 				name_len = i;
442 		}
443 	}
444 
445 	if (name_len > 0) {
446 		name_len += dotoffset;
447 
448 		if (sbi->options.isvfat) {
449 			uni_name[uni_len] = 0x0000;
450 			name_len = fat_uni_to_x8(sb, uni_name, name,
451 						 FAT_MAX_SHORT_SIZE);
452 		}
453 	}
454 
455 	return name_len;
456 }
457 
458 /*
459  * Return values: negative -> error/not found, 0 -> found.
460  */
461 int fat_search_long(struct inode *inode, const unsigned char *name,
462 		    int name_len, struct fat_slot_info *sinfo)
463 {
464 	struct super_block *sb = inode->i_sb;
465 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
466 	struct buffer_head *bh = NULL;
467 	struct msdos_dir_entry *de;
468 	unsigned char nr_slots;
469 	wchar_t *unicode = NULL;
470 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
471 	loff_t cpos = 0;
472 	int err, len;
473 
474 	err = -ENOENT;
475 	while (1) {
476 		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
477 			goto end_of_dir;
478 parse_record:
479 		nr_slots = 0;
480 		if (de->name[0] == DELETED_FLAG)
481 			continue;
482 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
483 			continue;
484 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
485 			continue;
486 		if (de->attr == ATTR_EXT) {
487 			int status = fat_parse_long(inode, &cpos, &bh, &de,
488 						    &unicode, &nr_slots);
489 			if (status < 0) {
490 				err = status;
491 				goto end_of_dir;
492 			} else if (status == PARSE_INVALID)
493 				continue;
494 			else if (status == PARSE_NOT_LONGNAME)
495 				goto parse_record;
496 			else if (status == PARSE_EOF)
497 				goto end_of_dir;
498 		}
499 
500 		/* Never prepend '.' to hidden files here.
501 		 * That is done only for msdos mounts (and only when
502 		 * 'dotsOK=yes'); if we are executing here, it is in the
503 		 * context of a vfat mount.
504 		 */
505 		len = fat_parse_short(sb, de, bufname, 0);
506 		if (len == 0)
507 			continue;
508 
509 		/* Compare shortname */
510 		if (fat_name_match(sbi, name, name_len, bufname, len))
511 			goto found;
512 
513 		if (nr_slots) {
514 			void *longname = unicode + FAT_MAX_UNI_CHARS;
515 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
516 
517 			/* Compare longname */
518 			len = fat_uni_to_x8(sb, unicode, longname, size);
519 			if (fat_name_match(sbi, name, name_len, longname, len))
520 				goto found;
521 		}
522 	}
523 
524 found:
525 	nr_slots++;	/* include the de */
526 	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
527 	sinfo->nr_slots = nr_slots;
528 	sinfo->de = de;
529 	sinfo->bh = bh;
530 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
531 	err = 0;
532 end_of_dir:
533 	if (unicode)
534 		__putname(unicode);
535 
536 	return err;
537 }
538 EXPORT_SYMBOL_GPL(fat_search_long);
539 
540 struct fat_ioctl_filldir_callback {
541 	struct dir_context ctx;
542 	void __user *dirent;
543 	int result;
544 	/* for dir ioctl */
545 	const char *longname;
546 	int long_len;
547 	const char *shortname;
548 	int short_len;
549 };
550 
551 static int __fat_readdir(struct inode *inode, struct file *file,
552 			 struct dir_context *ctx, int short_only,
553 			 struct fat_ioctl_filldir_callback *both)
554 {
555 	struct super_block *sb = inode->i_sb;
556 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
557 	struct buffer_head *bh;
558 	struct msdos_dir_entry *de;
559 	unsigned char nr_slots;
560 	wchar_t *unicode = NULL;
561 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
562 	int isvfat = sbi->options.isvfat;
563 	const char *fill_name = NULL;
564 	int fake_offset = 0;
565 	loff_t cpos;
566 	int short_len = 0, fill_len = 0;
567 	int ret = 0;
568 
569 	mutex_lock(&sbi->s_lock);
570 
571 	cpos = ctx->pos;
572 	/* Fake . and .. for the root directory. */
573 	if (inode->i_ino == MSDOS_ROOT_INO) {
574 		if (!dir_emit_dots(file, ctx))
575 			goto out;
576 		if (ctx->pos == 2) {
577 			fake_offset = 1;
578 			cpos = 0;
579 		}
580 	}
581 	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
582 		ret = -ENOENT;
583 		goto out;
584 	}
585 
586 	bh = NULL;
587 get_new:
588 	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
589 		goto end_of_dir;
590 parse_record:
591 	nr_slots = 0;
592 	/*
593 	 * Check for long filename entry, but if short_only, we don't
594 	 * need to parse long filename.
595 	 */
596 	if (isvfat && !short_only) {
597 		if (de->name[0] == DELETED_FLAG)
598 			goto record_end;
599 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
600 			goto record_end;
601 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
602 			goto record_end;
603 	} else {
604 		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
605 			goto record_end;
606 	}
607 
608 	if (isvfat && de->attr == ATTR_EXT) {
609 		int status = fat_parse_long(inode, &cpos, &bh, &de,
610 					    &unicode, &nr_slots);
611 		if (status < 0) {
612 			bh = NULL;
613 			ret = status;
614 			goto end_of_dir;
615 		} else if (status == PARSE_INVALID)
616 			goto record_end;
617 		else if (status == PARSE_NOT_LONGNAME)
618 			goto parse_record;
619 		else if (status == PARSE_EOF)
620 			goto end_of_dir;
621 
622 		if (nr_slots) {
623 			void *longname = unicode + FAT_MAX_UNI_CHARS;
624 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
625 			int len = fat_uni_to_x8(sb, unicode, longname, size);
626 
627 			fill_name = longname;
628 			fill_len = len;
629 			/* !both && !short_only, so we don't need shortname. */
630 			if (!both)
631 				goto start_filldir;
632 
633 			short_len = fat_parse_short(sb, de, bufname,
634 						    sbi->options.dotsOK);
635 			if (short_len == 0)
636 				goto record_end;
637 			/* hack for fat_ioctl_filldir() */
638 			both->longname = fill_name;
639 			both->long_len = fill_len;
640 			both->shortname = bufname;
641 			both->short_len = short_len;
642 			fill_name = NULL;
643 			fill_len = 0;
644 			goto start_filldir;
645 		}
646 	}
647 
648 	short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
649 	if (short_len == 0)
650 		goto record_end;
651 
652 	fill_name = bufname;
653 	fill_len = short_len;
654 
655 start_filldir:
656 	ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
657 	if (fake_offset && ctx->pos < 2)
658 		ctx->pos = 2;
659 
660 	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
661 		if (!dir_emit_dot(file, ctx))
662 			goto fill_failed;
663 	} else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
664 		if (!dir_emit_dotdot(file, ctx))
665 			goto fill_failed;
666 	} else {
667 		unsigned long inum;
668 		loff_t i_pos = fat_make_i_pos(sb, bh, de);
669 		struct inode *tmp = fat_iget(sb, i_pos);
670 		if (tmp) {
671 			inum = tmp->i_ino;
672 			iput(tmp);
673 		} else
674 			inum = iunique(sb, MSDOS_ROOT_INO);
675 		if (!dir_emit(ctx, fill_name, fill_len, inum,
676 			    (de->attr & ATTR_DIR) ? DT_DIR : DT_REG))
677 			goto fill_failed;
678 	}
679 
680 record_end:
681 	fake_offset = 0;
682 	ctx->pos = cpos;
683 	goto get_new;
684 
685 end_of_dir:
686 	if (fake_offset && cpos < 2)
687 		ctx->pos = 2;
688 	else
689 		ctx->pos = cpos;
690 fill_failed:
691 	brelse(bh);
692 	if (unicode)
693 		__putname(unicode);
694 out:
695 	mutex_unlock(&sbi->s_lock);
696 
697 	return ret;
698 }
699 
700 static int fat_readdir(struct file *file, struct dir_context *ctx)
701 {
702 	return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
703 }
704 
705 #define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
706 static int func(struct dir_context *ctx, const char *name, int name_len,   \
707 			     loff_t offset, u64 ino, unsigned int d_type)  \
708 {									   \
709 	struct fat_ioctl_filldir_callback *buf =			   \
710 		container_of(ctx, struct fat_ioctl_filldir_callback, ctx); \
711 	struct dirent_type __user *d1 = buf->dirent;			   \
712 	struct dirent_type __user *d2 = d1 + 1;				   \
713 									   \
714 	if (buf->result)						   \
715 		return -EINVAL;						   \
716 	buf->result++;							   \
717 									   \
718 	if (name != NULL) {						   \
719 		/* dirent has only short name */			   \
720 		if (name_len >= sizeof(d1->d_name))			   \
721 			name_len = sizeof(d1->d_name) - 1;		   \
722 									   \
723 		if (put_user(0, d2->d_name)			||	   \
724 		    put_user(0, &d2->d_reclen)			||	   \
725 		    copy_to_user(d1->d_name, name, name_len)	||	   \
726 		    put_user(0, d1->d_name + name_len)		||	   \
727 		    put_user(name_len, &d1->d_reclen))			   \
728 			goto efault;					   \
729 	} else {							   \
730 		/* dirent has short and long name */			   \
731 		const char *longname = buf->longname;			   \
732 		int long_len = buf->long_len;				   \
733 		const char *shortname = buf->shortname;			   \
734 		int short_len = buf->short_len;				   \
735 									   \
736 		if (long_len >= sizeof(d1->d_name))			   \
737 			long_len = sizeof(d1->d_name) - 1;		   \
738 		if (short_len >= sizeof(d1->d_name))			   \
739 			short_len = sizeof(d1->d_name) - 1;		   \
740 									   \
741 		if (copy_to_user(d2->d_name, longname, long_len)	|| \
742 		    put_user(0, d2->d_name + long_len)			|| \
743 		    put_user(long_len, &d2->d_reclen)			|| \
744 		    put_user(ino, &d2->d_ino)				|| \
745 		    put_user(offset, &d2->d_off)			|| \
746 		    copy_to_user(d1->d_name, shortname, short_len)	|| \
747 		    put_user(0, d1->d_name + short_len)			|| \
748 		    put_user(short_len, &d1->d_reclen))			   \
749 			goto efault;					   \
750 	}								   \
751 	return 0;							   \
752 efault:									   \
753 	buf->result = -EFAULT;						   \
754 	return -EFAULT;							   \
755 }
756 
757 FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
758 
759 static int fat_ioctl_readdir(struct inode *inode, struct file *file,
760 			     void __user *dirent, filldir_t filldir,
761 			     int short_only, int both)
762 {
763 	struct fat_ioctl_filldir_callback buf = {
764 		.ctx.actor = filldir,
765 		.dirent = dirent
766 	};
767 	int ret;
768 
769 	buf.dirent = dirent;
770 	buf.result = 0;
771 	inode_lock_shared(inode);
772 	buf.ctx.pos = file->f_pos;
773 	ret = -ENOENT;
774 	if (!IS_DEADDIR(inode)) {
775 		ret = __fat_readdir(inode, file, &buf.ctx,
776 				    short_only, both ? &buf : NULL);
777 		file->f_pos = buf.ctx.pos;
778 	}
779 	inode_unlock_shared(inode);
780 	if (ret >= 0)
781 		ret = buf.result;
782 	return ret;
783 }
784 
785 static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
786 			  unsigned long arg)
787 {
788 	struct inode *inode = file_inode(filp);
789 	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
790 	int short_only, both;
791 
792 	switch (cmd) {
793 	case VFAT_IOCTL_READDIR_SHORT:
794 		short_only = 1;
795 		both = 0;
796 		break;
797 	case VFAT_IOCTL_READDIR_BOTH:
798 		short_only = 0;
799 		both = 1;
800 		break;
801 	default:
802 		return fat_generic_ioctl(filp, cmd, arg);
803 	}
804 
805 	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct __fat_dirent[2])))
806 		return -EFAULT;
807 	/*
808 	 * Yes, we don't need this put_user() absolutely. However old
809 	 * code didn't return the right value. So, app use this value,
810 	 * in order to check whether it is EOF.
811 	 */
812 	if (put_user(0, &d1->d_reclen))
813 		return -EFAULT;
814 
815 	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
816 				 short_only, both);
817 }
818 
819 #ifdef CONFIG_COMPAT
820 #define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
821 #define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])
822 
823 FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
824 
825 static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
826 				 unsigned long arg)
827 {
828 	struct inode *inode = file_inode(filp);
829 	struct compat_dirent __user *d1 = compat_ptr(arg);
830 	int short_only, both;
831 
832 	switch (cmd) {
833 	case VFAT_IOCTL_READDIR_SHORT32:
834 		short_only = 1;
835 		both = 0;
836 		break;
837 	case VFAT_IOCTL_READDIR_BOTH32:
838 		short_only = 0;
839 		both = 1;
840 		break;
841 	default:
842 		return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
843 	}
844 
845 	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct compat_dirent[2])))
846 		return -EFAULT;
847 	/*
848 	 * Yes, we don't need this put_user() absolutely. However old
849 	 * code didn't return the right value. So, app use this value,
850 	 * in order to check whether it is EOF.
851 	 */
852 	if (put_user(0, &d1->d_reclen))
853 		return -EFAULT;
854 
855 	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
856 				 short_only, both);
857 }
858 #endif /* CONFIG_COMPAT */
859 
860 const struct file_operations fat_dir_operations = {
861 	.llseek		= generic_file_llseek,
862 	.read		= generic_read_dir,
863 	.iterate_shared	= fat_readdir,
864 	.unlocked_ioctl	= fat_dir_ioctl,
865 #ifdef CONFIG_COMPAT
866 	.compat_ioctl	= fat_compat_dir_ioctl,
867 #endif
868 	.fsync		= fat_file_fsync,
869 };
870 
871 static int fat_get_short_entry(struct inode *dir, loff_t *pos,
872 			       struct buffer_head **bh,
873 			       struct msdos_dir_entry **de)
874 {
875 	while (fat_get_entry(dir, pos, bh, de) >= 0) {
876 		/* free entry or long name entry or volume label */
877 		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
878 			return 0;
879 	}
880 	return -ENOENT;
881 }
882 
883 /*
884  * The ".." entry can not provide the "struct fat_slot_info" information
885  * for inode, nor a usable i_pos. So, this function provides some information
886  * only.
887  *
888  * Since this function walks through the on-disk inodes within a directory,
889  * callers are responsible for taking any locks necessary to prevent the
890  * directory from changing.
891  */
892 int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
893 			 struct msdos_dir_entry **de)
894 {
895 	loff_t offset = 0;
896 
897 	*de = NULL;
898 	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
899 		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
900 			return 0;
901 	}
902 	return -ENOENT;
903 }
904 EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
905 
906 /* See if directory is empty */
907 int fat_dir_empty(struct inode *dir)
908 {
909 	struct buffer_head *bh;
910 	struct msdos_dir_entry *de;
911 	loff_t cpos;
912 	int result = 0;
913 
914 	bh = NULL;
915 	cpos = 0;
916 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
917 		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
918 		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
919 			result = -ENOTEMPTY;
920 			break;
921 		}
922 	}
923 	brelse(bh);
924 	return result;
925 }
926 EXPORT_SYMBOL_GPL(fat_dir_empty);
927 
928 /*
929  * fat_subdirs counts the number of sub-directories of dir. It can be run
930  * on directories being created.
931  */
932 int fat_subdirs(struct inode *dir)
933 {
934 	struct buffer_head *bh;
935 	struct msdos_dir_entry *de;
936 	loff_t cpos;
937 	int count = 0;
938 
939 	bh = NULL;
940 	cpos = 0;
941 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
942 		if (de->attr & ATTR_DIR)
943 			count++;
944 	}
945 	brelse(bh);
946 	return count;
947 }
948 
949 /*
950  * Scans a directory for a given file (name points to its formatted name).
951  * Returns an error code or zero.
952  */
953 int fat_scan(struct inode *dir, const unsigned char *name,
954 	     struct fat_slot_info *sinfo)
955 {
956 	struct super_block *sb = dir->i_sb;
957 
958 	sinfo->slot_off = 0;
959 	sinfo->bh = NULL;
960 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
961 				   &sinfo->de) >= 0) {
962 		if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
963 			sinfo->slot_off -= sizeof(*sinfo->de);
964 			sinfo->nr_slots = 1;
965 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
966 			return 0;
967 		}
968 	}
969 	return -ENOENT;
970 }
971 EXPORT_SYMBOL_GPL(fat_scan);
972 
973 /*
974  * Scans a directory for a given logstart.
975  * Returns an error code or zero.
976  */
977 int fat_scan_logstart(struct inode *dir, int i_logstart,
978 		      struct fat_slot_info *sinfo)
979 {
980 	struct super_block *sb = dir->i_sb;
981 
982 	sinfo->slot_off = 0;
983 	sinfo->bh = NULL;
984 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
985 				   &sinfo->de) >= 0) {
986 		if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
987 			sinfo->slot_off -= sizeof(*sinfo->de);
988 			sinfo->nr_slots = 1;
989 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
990 			return 0;
991 		}
992 	}
993 	return -ENOENT;
994 }
995 
996 static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
997 {
998 	struct super_block *sb = dir->i_sb;
999 	struct buffer_head *bh;
1000 	struct msdos_dir_entry *de, *endp;
1001 	int err = 0, orig_slots;
1002 
1003 	while (nr_slots) {
1004 		bh = NULL;
1005 		if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1006 			err = -EIO;
1007 			break;
1008 		}
1009 
1010 		orig_slots = nr_slots;
1011 		endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1012 		while (nr_slots && de < endp) {
1013 			de->name[0] = DELETED_FLAG;
1014 			de++;
1015 			nr_slots--;
1016 		}
1017 		mark_buffer_dirty_inode(bh, dir);
1018 		if (IS_DIRSYNC(dir))
1019 			err = sync_dirty_buffer(bh);
1020 		brelse(bh);
1021 		if (err)
1022 			break;
1023 
1024 		/* pos is *next* de's position, so this does `- sizeof(de)' */
1025 		pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1026 	}
1027 
1028 	return err;
1029 }
1030 
1031 int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1032 {
1033 	struct super_block *sb = dir->i_sb;
1034 	struct msdos_dir_entry *de;
1035 	struct buffer_head *bh;
1036 	int err = 0, nr_slots;
1037 
1038 	/*
1039 	 * First stage: Remove the shortname. By this, the directory
1040 	 * entry is removed.
1041 	 */
1042 	nr_slots = sinfo->nr_slots;
1043 	de = sinfo->de;
1044 	sinfo->de = NULL;
1045 	bh = sinfo->bh;
1046 	sinfo->bh = NULL;
1047 	while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1048 		de->name[0] = DELETED_FLAG;
1049 		de--;
1050 		nr_slots--;
1051 	}
1052 	mark_buffer_dirty_inode(bh, dir);
1053 	if (IS_DIRSYNC(dir))
1054 		err = sync_dirty_buffer(bh);
1055 	brelse(bh);
1056 	if (err)
1057 		return err;
1058 	dir->i_version++;
1059 
1060 	if (nr_slots) {
1061 		/*
1062 		 * Second stage: remove the remaining longname slots.
1063 		 * (This directory entry is already removed, and so return
1064 		 * the success)
1065 		 */
1066 		err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1067 		if (err) {
1068 			fat_msg(sb, KERN_WARNING,
1069 			       "Couldn't remove the long name slots");
1070 		}
1071 	}
1072 
1073 	dir->i_mtime = dir->i_atime = current_time(dir);
1074 	if (IS_DIRSYNC(dir))
1075 		(void)fat_sync_inode(dir);
1076 	else
1077 		mark_inode_dirty(dir);
1078 
1079 	return 0;
1080 }
1081 EXPORT_SYMBOL_GPL(fat_remove_entries);
1082 
1083 static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1084 			      struct buffer_head **bhs, int nr_bhs)
1085 {
1086 	struct super_block *sb = dir->i_sb;
1087 	sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1088 	int err, i, n;
1089 
1090 	/* Zeroing the unused blocks on this cluster */
1091 	blknr += nr_used;
1092 	n = nr_used;
1093 	while (blknr < last_blknr) {
1094 		bhs[n] = sb_getblk(sb, blknr);
1095 		if (!bhs[n]) {
1096 			err = -ENOMEM;
1097 			goto error;
1098 		}
1099 		memset(bhs[n]->b_data, 0, sb->s_blocksize);
1100 		set_buffer_uptodate(bhs[n]);
1101 		mark_buffer_dirty_inode(bhs[n], dir);
1102 
1103 		n++;
1104 		blknr++;
1105 		if (n == nr_bhs) {
1106 			if (IS_DIRSYNC(dir)) {
1107 				err = fat_sync_bhs(bhs, n);
1108 				if (err)
1109 					goto error;
1110 			}
1111 			for (i = 0; i < n; i++)
1112 				brelse(bhs[i]);
1113 			n = 0;
1114 		}
1115 	}
1116 	if (IS_DIRSYNC(dir)) {
1117 		err = fat_sync_bhs(bhs, n);
1118 		if (err)
1119 			goto error;
1120 	}
1121 	for (i = 0; i < n; i++)
1122 		brelse(bhs[i]);
1123 
1124 	return 0;
1125 
1126 error:
1127 	for (i = 0; i < n; i++)
1128 		bforget(bhs[i]);
1129 	return err;
1130 }
1131 
1132 int fat_alloc_new_dir(struct inode *dir, struct timespec *ts)
1133 {
1134 	struct super_block *sb = dir->i_sb;
1135 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1136 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1137 	struct msdos_dir_entry *de;
1138 	sector_t blknr;
1139 	__le16 date, time;
1140 	u8 time_cs;
1141 	int err, cluster;
1142 
1143 	err = fat_alloc_clusters(dir, &cluster, 1);
1144 	if (err)
1145 		goto error;
1146 
1147 	blknr = fat_clus_to_blknr(sbi, cluster);
1148 	bhs[0] = sb_getblk(sb, blknr);
1149 	if (!bhs[0]) {
1150 		err = -ENOMEM;
1151 		goto error_free;
1152 	}
1153 
1154 	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1155 
1156 	de = (struct msdos_dir_entry *)bhs[0]->b_data;
1157 	/* filling the new directory slots ("." and ".." entries) */
1158 	memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1159 	memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1160 	de->attr = de[1].attr = ATTR_DIR;
1161 	de[0].lcase = de[1].lcase = 0;
1162 	de[0].time = de[1].time = time;
1163 	de[0].date = de[1].date = date;
1164 	if (sbi->options.isvfat) {
1165 		/* extra timestamps */
1166 		de[0].ctime = de[1].ctime = time;
1167 		de[0].ctime_cs = de[1].ctime_cs = time_cs;
1168 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1169 	} else {
1170 		de[0].ctime = de[1].ctime = 0;
1171 		de[0].ctime_cs = de[1].ctime_cs = 0;
1172 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1173 	}
1174 	fat_set_start(&de[0], cluster);
1175 	fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1176 	de[0].size = de[1].size = 0;
1177 	memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1178 	set_buffer_uptodate(bhs[0]);
1179 	mark_buffer_dirty_inode(bhs[0], dir);
1180 
1181 	err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1182 	if (err)
1183 		goto error_free;
1184 
1185 	return cluster;
1186 
1187 error_free:
1188 	fat_free_clusters(dir, cluster);
1189 error:
1190 	return err;
1191 }
1192 EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1193 
1194 static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1195 			       int *nr_cluster, struct msdos_dir_entry **de,
1196 			       struct buffer_head **bh, loff_t *i_pos)
1197 {
1198 	struct super_block *sb = dir->i_sb;
1199 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1200 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1201 	sector_t blknr, start_blknr, last_blknr;
1202 	unsigned long size, copy;
1203 	int err, i, n, offset, cluster[2];
1204 
1205 	/*
1206 	 * The minimum cluster size is 512bytes, and maximum entry
1207 	 * size is 32*slots (672bytes).  So, iff the cluster size is
1208 	 * 512bytes, we may need two clusters.
1209 	 */
1210 	size = nr_slots * sizeof(struct msdos_dir_entry);
1211 	*nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1212 	BUG_ON(*nr_cluster > 2);
1213 
1214 	err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1215 	if (err)
1216 		goto error;
1217 
1218 	/*
1219 	 * First stage: Fill the directory entry.  NOTE: This cluster
1220 	 * is not referenced from any inode yet, so updates order is
1221 	 * not important.
1222 	 */
1223 	i = n = copy = 0;
1224 	do {
1225 		start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1226 		last_blknr = start_blknr + sbi->sec_per_clus;
1227 		while (blknr < last_blknr) {
1228 			bhs[n] = sb_getblk(sb, blknr);
1229 			if (!bhs[n]) {
1230 				err = -ENOMEM;
1231 				goto error_nomem;
1232 			}
1233 
1234 			/* fill the directory entry */
1235 			copy = min(size, sb->s_blocksize);
1236 			memcpy(bhs[n]->b_data, slots, copy);
1237 			slots += copy;
1238 			size -= copy;
1239 			set_buffer_uptodate(bhs[n]);
1240 			mark_buffer_dirty_inode(bhs[n], dir);
1241 			if (!size)
1242 				break;
1243 			n++;
1244 			blknr++;
1245 		}
1246 	} while (++i < *nr_cluster);
1247 
1248 	memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1249 	offset = copy - sizeof(struct msdos_dir_entry);
1250 	get_bh(bhs[n]);
1251 	*bh = bhs[n];
1252 	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1253 	*i_pos = fat_make_i_pos(sb, *bh, *de);
1254 
1255 	/* Second stage: clear the rest of cluster, and write outs */
1256 	err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1257 	if (err)
1258 		goto error_free;
1259 
1260 	return cluster[0];
1261 
1262 error_free:
1263 	brelse(*bh);
1264 	*bh = NULL;
1265 	n = 0;
1266 error_nomem:
1267 	for (i = 0; i < n; i++)
1268 		bforget(bhs[i]);
1269 	fat_free_clusters(dir, cluster[0]);
1270 error:
1271 	return err;
1272 }
1273 
1274 int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1275 		    struct fat_slot_info *sinfo)
1276 {
1277 	struct super_block *sb = dir->i_sb;
1278 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1279 	struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1280 	struct msdos_dir_entry *uninitialized_var(de);
1281 	int err, free_slots, i, nr_bhs;
1282 	loff_t pos, i_pos;
1283 
1284 	sinfo->nr_slots = nr_slots;
1285 
1286 	/* First stage: search free directory entries */
1287 	free_slots = nr_bhs = 0;
1288 	bh = prev = NULL;
1289 	pos = 0;
1290 	err = -ENOSPC;
1291 	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1292 		/* check the maximum size of directory */
1293 		if (pos >= FAT_MAX_DIR_SIZE)
1294 			goto error;
1295 
1296 		if (IS_FREE(de->name)) {
1297 			if (prev != bh) {
1298 				get_bh(bh);
1299 				bhs[nr_bhs] = prev = bh;
1300 				nr_bhs++;
1301 			}
1302 			free_slots++;
1303 			if (free_slots == nr_slots)
1304 				goto found;
1305 		} else {
1306 			for (i = 0; i < nr_bhs; i++)
1307 				brelse(bhs[i]);
1308 			prev = NULL;
1309 			free_slots = nr_bhs = 0;
1310 		}
1311 	}
1312 	if (dir->i_ino == MSDOS_ROOT_INO) {
1313 		if (sbi->fat_bits != 32)
1314 			goto error;
1315 	} else if (MSDOS_I(dir)->i_start == 0) {
1316 		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1317 		       MSDOS_I(dir)->i_pos);
1318 		err = -EIO;
1319 		goto error;
1320 	}
1321 
1322 found:
1323 	err = 0;
1324 	pos -= free_slots * sizeof(*de);
1325 	nr_slots -= free_slots;
1326 	if (free_slots) {
1327 		/*
1328 		 * Second stage: filling the free entries with new entries.
1329 		 * NOTE: If this slots has shortname, first, we write
1330 		 * the long name slots, then write the short name.
1331 		 */
1332 		int size = free_slots * sizeof(*de);
1333 		int offset = pos & (sb->s_blocksize - 1);
1334 		int long_bhs = nr_bhs - (nr_slots == 0);
1335 
1336 		/* Fill the long name slots. */
1337 		for (i = 0; i < long_bhs; i++) {
1338 			int copy = min_t(int, sb->s_blocksize - offset, size);
1339 			memcpy(bhs[i]->b_data + offset, slots, copy);
1340 			mark_buffer_dirty_inode(bhs[i], dir);
1341 			offset = 0;
1342 			slots += copy;
1343 			size -= copy;
1344 		}
1345 		if (long_bhs && IS_DIRSYNC(dir))
1346 			err = fat_sync_bhs(bhs, long_bhs);
1347 		if (!err && i < nr_bhs) {
1348 			/* Fill the short name slot. */
1349 			int copy = min_t(int, sb->s_blocksize - offset, size);
1350 			memcpy(bhs[i]->b_data + offset, slots, copy);
1351 			mark_buffer_dirty_inode(bhs[i], dir);
1352 			if (IS_DIRSYNC(dir))
1353 				err = sync_dirty_buffer(bhs[i]);
1354 		}
1355 		for (i = 0; i < nr_bhs; i++)
1356 			brelse(bhs[i]);
1357 		if (err)
1358 			goto error_remove;
1359 	}
1360 
1361 	if (nr_slots) {
1362 		int cluster, nr_cluster;
1363 
1364 		/*
1365 		 * Third stage: allocate the cluster for new entries.
1366 		 * And initialize the cluster with new entries, then
1367 		 * add the cluster to dir.
1368 		 */
1369 		cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1370 					      &de, &bh, &i_pos);
1371 		if (cluster < 0) {
1372 			err = cluster;
1373 			goto error_remove;
1374 		}
1375 		err = fat_chain_add(dir, cluster, nr_cluster);
1376 		if (err) {
1377 			fat_free_clusters(dir, cluster);
1378 			goto error_remove;
1379 		}
1380 		if (dir->i_size & (sbi->cluster_size - 1)) {
1381 			fat_fs_error(sb, "Odd directory size");
1382 			dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1383 				& ~((loff_t)sbi->cluster_size - 1);
1384 		}
1385 		dir->i_size += nr_cluster << sbi->cluster_bits;
1386 		MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1387 	}
1388 	sinfo->slot_off = pos;
1389 	sinfo->de = de;
1390 	sinfo->bh = bh;
1391 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1392 
1393 	return 0;
1394 
1395 error:
1396 	brelse(bh);
1397 	for (i = 0; i < nr_bhs; i++)
1398 		brelse(bhs[i]);
1399 	return err;
1400 
1401 error_remove:
1402 	brelse(bh);
1403 	if (free_slots)
1404 		__fat_remove_entries(dir, pos, free_slots);
1405 	return err;
1406 }
1407 EXPORT_SYMBOL_GPL(fat_add_entries);
1408