xref: /openbmc/linux/fs/fat/dir.c (revision 588b48ca)
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/module.h>
17 #include <linux/slab.h>
18 #include <linux/time.h>
19 #include <linux/buffer_head.h>
20 #include <linux/compat.h>
21 #include <linux/uaccess.h>
22 #include <linux/kernel.h>
23 #include "fat.h"
24 
25 /*
26  * Maximum buffer size of short name.
27  * [(MSDOS_NAME + '.') * max one char + nul]
28  * For msdos style, ['.' (hidden) + MSDOS_NAME + '.' + nul]
29  */
30 #define FAT_MAX_SHORT_SIZE	((MSDOS_NAME + 1) * NLS_MAX_CHARSET_SIZE + 1)
31 /*
32  * Maximum buffer size of unicode chars from slots.
33  * [(max longname slots * 13 (size in a slot) + nul) * sizeof(wchar_t)]
34  */
35 #define FAT_MAX_UNI_CHARS	((MSDOS_SLOTS - 1) * 13 + 1)
36 #define FAT_MAX_UNI_SIZE	(FAT_MAX_UNI_CHARS * sizeof(wchar_t))
37 
38 static inline unsigned char fat_tolower(unsigned char c)
39 {
40 	return ((c >= 'A') && (c <= 'Z')) ? c+32 : c;
41 }
42 
43 static inline loff_t fat_make_i_pos(struct super_block *sb,
44 				    struct buffer_head *bh,
45 				    struct msdos_dir_entry *de)
46 {
47 	return ((loff_t)bh->b_blocknr << MSDOS_SB(sb)->dir_per_block_bits)
48 		| (de - (struct msdos_dir_entry *)bh->b_data);
49 }
50 
51 static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
52 				     sector_t phys)
53 {
54 	struct super_block *sb = dir->i_sb;
55 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
56 	struct buffer_head *bh;
57 	int sec;
58 
59 	/* This is not a first sector of cluster, or sec_per_clus == 1 */
60 	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
61 		return;
62 	/* root dir of FAT12/FAT16 */
63 	if ((sbi->fat_bits != 32) && (dir->i_ino == MSDOS_ROOT_INO))
64 		return;
65 
66 	bh = sb_find_get_block(sb, phys);
67 	if (bh == NULL || !buffer_uptodate(bh)) {
68 		for (sec = 0; sec < sbi->sec_per_clus; sec++)
69 			sb_breadahead(sb, phys + sec);
70 	}
71 	brelse(bh);
72 }
73 
74 /* Returns the inode number of the directory entry at offset pos. If bh is
75    non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
76    returned in bh.
77    AV. Most often we do it item-by-item. Makes sense to optimize.
78    AV. OK, there we go: if both bh and de are non-NULL we assume that we just
79    AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
80    AV. It's done in fat_get_entry() (inlined), here the slow case lives.
81    AV. Additionally, when we return -1 (i.e. reached the end of directory)
82    AV. we make bh NULL.
83  */
84 static int fat__get_entry(struct inode *dir, loff_t *pos,
85 			  struct buffer_head **bh, struct msdos_dir_entry **de)
86 {
87 	struct super_block *sb = dir->i_sb;
88 	sector_t phys, iblock;
89 	unsigned long mapped_blocks;
90 	int err, offset;
91 
92 next:
93 	if (*bh)
94 		brelse(*bh);
95 
96 	*bh = NULL;
97 	iblock = *pos >> sb->s_blocksize_bits;
98 	err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0);
99 	if (err || !phys)
100 		return -1;	/* beyond EOF or error */
101 
102 	fat_dir_readahead(dir, iblock, phys);
103 
104 	*bh = sb_bread(sb, phys);
105 	if (*bh == NULL) {
106 		fat_msg_ratelimit(sb, KERN_ERR,
107 			"Directory bread(block %llu) failed", (llu)phys);
108 		/* skip this block */
109 		*pos = (iblock + 1) << sb->s_blocksize_bits;
110 		goto next;
111 	}
112 
113 	offset = *pos & (sb->s_blocksize - 1);
114 	*pos += sizeof(struct msdos_dir_entry);
115 	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
116 
117 	return 0;
118 }
119 
120 static inline int fat_get_entry(struct inode *dir, loff_t *pos,
121 				struct buffer_head **bh,
122 				struct msdos_dir_entry **de)
123 {
124 	/* Fast stuff first */
125 	if (*bh && *de &&
126 	   (*de - (struct msdos_dir_entry *)(*bh)->b_data) <
127 				MSDOS_SB(dir->i_sb)->dir_per_block - 1) {
128 		*pos += sizeof(struct msdos_dir_entry);
129 		(*de)++;
130 		return 0;
131 	}
132 	return fat__get_entry(dir, pos, bh, de);
133 }
134 
135 /*
136  * Convert Unicode 16 to UTF-8, translated Unicode, or ASCII.
137  * If uni_xlate is enabled and we can't get a 1:1 conversion, use a
138  * colon as an escape character since it is normally invalid on the vfat
139  * filesystem. The following four characters are the hexadecimal digits
140  * of Unicode value. This lets us do a full dump and restore of Unicode
141  * filenames. We could get into some trouble with long Unicode names,
142  * but ignore that right now.
143  * Ahem... Stack smashing in ring 0 isn't fun. Fixed.
144  */
145 static int uni16_to_x8(struct super_block *sb, unsigned char *ascii,
146 		       const wchar_t *uni, int len, struct nls_table *nls)
147 {
148 	int uni_xlate = MSDOS_SB(sb)->options.unicode_xlate;
149 	const wchar_t *ip;
150 	wchar_t ec;
151 	unsigned char *op;
152 	int charlen;
153 
154 	ip = uni;
155 	op = ascii;
156 
157 	while (*ip && ((len - NLS_MAX_CHARSET_SIZE) > 0)) {
158 		ec = *ip++;
159 		charlen = nls->uni2char(ec, op, NLS_MAX_CHARSET_SIZE);
160 		if (charlen > 0) {
161 			op += charlen;
162 			len -= charlen;
163 		} else {
164 			if (uni_xlate == 1) {
165 				*op++ = ':';
166 				op = hex_byte_pack(op, ec >> 8);
167 				op = hex_byte_pack(op, ec);
168 				len -= 5;
169 			} else {
170 				*op++ = '?';
171 				len--;
172 			}
173 		}
174 	}
175 
176 	if (unlikely(*ip)) {
177 		fat_msg(sb, KERN_WARNING,
178 			"filename was truncated while converting.");
179 	}
180 
181 	*op = 0;
182 	return op - ascii;
183 }
184 
185 static inline int fat_uni_to_x8(struct super_block *sb, const wchar_t *uni,
186 				unsigned char *buf, int size)
187 {
188 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
189 	if (sbi->options.utf8)
190 		return utf16s_to_utf8s(uni, FAT_MAX_UNI_CHARS,
191 				UTF16_HOST_ENDIAN, buf, size);
192 	else
193 		return uni16_to_x8(sb, buf, uni, size, sbi->nls_io);
194 }
195 
196 static inline int
197 fat_short2uni(struct nls_table *t, unsigned char *c, int clen, wchar_t *uni)
198 {
199 	int charlen;
200 
201 	charlen = t->char2uni(c, clen, uni);
202 	if (charlen < 0) {
203 		*uni = 0x003f;	/* a question mark */
204 		charlen = 1;
205 	}
206 	return charlen;
207 }
208 
209 static inline int
210 fat_short2lower_uni(struct nls_table *t, unsigned char *c,
211 		    int clen, wchar_t *uni)
212 {
213 	int charlen;
214 	wchar_t wc;
215 
216 	charlen = t->char2uni(c, clen, &wc);
217 	if (charlen < 0) {
218 		*uni = 0x003f;	/* a question mark */
219 		charlen = 1;
220 	} else if (charlen <= 1) {
221 		unsigned char nc = t->charset2lower[*c];
222 
223 		if (!nc)
224 			nc = *c;
225 
226 		charlen = t->char2uni(&nc, 1, uni);
227 		if (charlen < 0) {
228 			*uni = 0x003f;	/* a question mark */
229 			charlen = 1;
230 		}
231 	} else
232 		*uni = wc;
233 
234 	return charlen;
235 }
236 
237 static inline int
238 fat_shortname2uni(struct nls_table *nls, unsigned char *buf, int buf_size,
239 		  wchar_t *uni_buf, unsigned short opt, int lower)
240 {
241 	int len = 0;
242 
243 	if (opt & VFAT_SFN_DISPLAY_LOWER)
244 		len =  fat_short2lower_uni(nls, buf, buf_size, uni_buf);
245 	else if (opt & VFAT_SFN_DISPLAY_WIN95)
246 		len = fat_short2uni(nls, buf, buf_size, uni_buf);
247 	else if (opt & VFAT_SFN_DISPLAY_WINNT) {
248 		if (lower)
249 			len = fat_short2lower_uni(nls, buf, buf_size, uni_buf);
250 		else
251 			len = fat_short2uni(nls, buf, buf_size, uni_buf);
252 	} else
253 		len = fat_short2uni(nls, buf, buf_size, uni_buf);
254 
255 	return len;
256 }
257 
258 static inline int fat_name_match(struct msdos_sb_info *sbi,
259 				 const unsigned char *a, int a_len,
260 				 const unsigned char *b, int b_len)
261 {
262 	if (a_len != b_len)
263 		return 0;
264 
265 	if (sbi->options.name_check != 's')
266 		return !nls_strnicmp(sbi->nls_io, a, b, a_len);
267 	else
268 		return !memcmp(a, b, a_len);
269 }
270 
271 enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };
272 
273 /**
274  * fat_parse_long - Parse extended directory entry.
275  *
276  * This function returns zero on success, negative value on error, or one of
277  * the following:
278  *
279  * %PARSE_INVALID - Directory entry is invalid.
280  * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
281  * %PARSE_EOF - Directory has no more entries.
282  */
283 static int fat_parse_long(struct inode *dir, loff_t *pos,
284 			  struct buffer_head **bh, struct msdos_dir_entry **de,
285 			  wchar_t **unicode, unsigned char *nr_slots)
286 {
287 	struct msdos_dir_slot *ds;
288 	unsigned char id, slot, slots, alias_checksum;
289 
290 	if (!*unicode) {
291 		*unicode = __getname();
292 		if (!*unicode) {
293 			brelse(*bh);
294 			return -ENOMEM;
295 		}
296 	}
297 parse_long:
298 	slots = 0;
299 	ds = (struct msdos_dir_slot *)*de;
300 	id = ds->id;
301 	if (!(id & 0x40))
302 		return PARSE_INVALID;
303 	slots = id & ~0x40;
304 	if (slots > 20 || !slots)	/* ceil(256 * 2 / 26) */
305 		return PARSE_INVALID;
306 	*nr_slots = slots;
307 	alias_checksum = ds->alias_checksum;
308 
309 	slot = slots;
310 	while (1) {
311 		int offset;
312 
313 		slot--;
314 		offset = slot * 13;
315 		fat16_towchar(*unicode + offset, ds->name0_4, 5);
316 		fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
317 		fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);
318 
319 		if (ds->id & 0x40)
320 			(*unicode)[offset + 13] = 0;
321 		if (fat_get_entry(dir, pos, bh, de) < 0)
322 			return PARSE_EOF;
323 		if (slot == 0)
324 			break;
325 		ds = (struct msdos_dir_slot *)*de;
326 		if (ds->attr != ATTR_EXT)
327 			return PARSE_NOT_LONGNAME;
328 		if ((ds->id & ~0x40) != slot)
329 			goto parse_long;
330 		if (ds->alias_checksum != alias_checksum)
331 			goto parse_long;
332 	}
333 	if ((*de)->name[0] == DELETED_FLAG)
334 		return PARSE_INVALID;
335 	if ((*de)->attr == ATTR_EXT)
336 		goto parse_long;
337 	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
338 		return PARSE_INVALID;
339 	if (fat_checksum((*de)->name) != alias_checksum)
340 		*nr_slots = 0;
341 
342 	return 0;
343 }
344 
345 /**
346  * fat_parse_short - Parse MS-DOS (short) directory entry.
347  * @sb:		superblock
348  * @de:		directory entry to parse
349  * @name:	FAT_MAX_SHORT_SIZE array in which to place extracted name
350  * @dot_hidden:	Nonzero == prepend '.' to names with ATTR_HIDDEN
351  *
352  * Returns the number of characters extracted into 'name'.
353  */
354 static int fat_parse_short(struct super_block *sb,
355 			   const struct msdos_dir_entry *de,
356 			   unsigned char *name, int dot_hidden)
357 {
358 	const struct msdos_sb_info *sbi = MSDOS_SB(sb);
359 	int isvfat = sbi->options.isvfat;
360 	int nocase = sbi->options.nocase;
361 	unsigned short opt_shortname = sbi->options.shortname;
362 	struct nls_table *nls_disk = sbi->nls_disk;
363 	wchar_t uni_name[14];
364 	unsigned char c, work[MSDOS_NAME];
365 	unsigned char *ptname = name;
366 	int chi, chl, i, j, k;
367 	int dotoffset = 0;
368 	int name_len = 0, uni_len = 0;
369 
370 	if (!isvfat && dot_hidden && (de->attr & ATTR_HIDDEN)) {
371 		*ptname++ = '.';
372 		dotoffset = 1;
373 	}
374 
375 	memcpy(work, de->name, sizeof(work));
376 	/* see namei.c, msdos_format_name */
377 	if (work[0] == 0x05)
378 		work[0] = 0xE5;
379 
380 	/* Filename */
381 	for (i = 0, j = 0; i < 8;) {
382 		c = work[i];
383 		if (!c)
384 			break;
385 		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
386 					&uni_name[j++], opt_shortname,
387 					de->lcase & CASE_LOWER_BASE);
388 		if (chl <= 1) {
389 			if (!isvfat)
390 				ptname[i] = nocase ? c : fat_tolower(c);
391 			i++;
392 			if (c != ' ') {
393 				name_len = i;
394 				uni_len  = j;
395 			}
396 		} else {
397 			uni_len = j;
398 			if (isvfat)
399 				i += min(chl, 8-i);
400 			else {
401 				for (chi = 0; chi < chl && i < 8; chi++, i++)
402 					ptname[i] = work[i];
403 			}
404 			if (chl)
405 				name_len = i;
406 		}
407 	}
408 
409 	i = name_len;
410 	j = uni_len;
411 	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
412 	if (!isvfat)
413 		ptname[i] = '.';
414 	i++;
415 
416 	/* Extension */
417 	for (k = 8; k < MSDOS_NAME;) {
418 		c = work[k];
419 		if (!c)
420 			break;
421 		chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
422 					&uni_name[j++], opt_shortname,
423 					de->lcase & CASE_LOWER_EXT);
424 		if (chl <= 1) {
425 			k++;
426 			if (!isvfat)
427 				ptname[i] = nocase ? c : fat_tolower(c);
428 			i++;
429 			if (c != ' ') {
430 				name_len = i;
431 				uni_len  = j;
432 			}
433 		} else {
434 			uni_len = j;
435 			if (isvfat) {
436 				int offset = min(chl, MSDOS_NAME-k);
437 				k += offset;
438 				i += offset;
439 			} else {
440 				for (chi = 0; chi < chl && k < MSDOS_NAME;
441 				     chi++, i++, k++) {
442 						ptname[i] = work[k];
443 				}
444 			}
445 			if (chl)
446 				name_len = i;
447 		}
448 	}
449 
450 	if (name_len > 0) {
451 		name_len += dotoffset;
452 
453 		if (sbi->options.isvfat) {
454 			uni_name[uni_len] = 0x0000;
455 			name_len = fat_uni_to_x8(sb, uni_name, name,
456 						 FAT_MAX_SHORT_SIZE);
457 		}
458 	}
459 
460 	return name_len;
461 }
462 
463 /*
464  * Return values: negative -> error/not found, 0 -> found.
465  */
466 int fat_search_long(struct inode *inode, const unsigned char *name,
467 		    int name_len, struct fat_slot_info *sinfo)
468 {
469 	struct super_block *sb = inode->i_sb;
470 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
471 	struct buffer_head *bh = NULL;
472 	struct msdos_dir_entry *de;
473 	unsigned char nr_slots;
474 	wchar_t *unicode = NULL;
475 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
476 	loff_t cpos = 0;
477 	int err, len;
478 
479 	err = -ENOENT;
480 	while (1) {
481 		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
482 			goto end_of_dir;
483 parse_record:
484 		nr_slots = 0;
485 		if (de->name[0] == DELETED_FLAG)
486 			continue;
487 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
488 			continue;
489 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
490 			continue;
491 		if (de->attr == ATTR_EXT) {
492 			int status = fat_parse_long(inode, &cpos, &bh, &de,
493 						    &unicode, &nr_slots);
494 			if (status < 0) {
495 				err = status;
496 				goto end_of_dir;
497 			} else if (status == PARSE_INVALID)
498 				continue;
499 			else if (status == PARSE_NOT_LONGNAME)
500 				goto parse_record;
501 			else if (status == PARSE_EOF)
502 				goto end_of_dir;
503 		}
504 
505 		/* Never prepend '.' to hidden files here.
506 		 * That is done only for msdos mounts (and only when
507 		 * 'dotsOK=yes'); if we are executing here, it is in the
508 		 * context of a vfat mount.
509 		 */
510 		len = fat_parse_short(sb, de, bufname, 0);
511 		if (len == 0)
512 			continue;
513 
514 		/* Compare shortname */
515 		if (fat_name_match(sbi, name, name_len, bufname, len))
516 			goto found;
517 
518 		if (nr_slots) {
519 			void *longname = unicode + FAT_MAX_UNI_CHARS;
520 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
521 
522 			/* Compare longname */
523 			len = fat_uni_to_x8(sb, unicode, longname, size);
524 			if (fat_name_match(sbi, name, name_len, longname, len))
525 				goto found;
526 		}
527 	}
528 
529 found:
530 	nr_slots++;	/* include the de */
531 	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
532 	sinfo->nr_slots = nr_slots;
533 	sinfo->de = de;
534 	sinfo->bh = bh;
535 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
536 	err = 0;
537 end_of_dir:
538 	if (unicode)
539 		__putname(unicode);
540 
541 	return err;
542 }
543 EXPORT_SYMBOL_GPL(fat_search_long);
544 
545 struct fat_ioctl_filldir_callback {
546 	struct dir_context ctx;
547 	void __user *dirent;
548 	int result;
549 	/* for dir ioctl */
550 	const char *longname;
551 	int long_len;
552 	const char *shortname;
553 	int short_len;
554 };
555 
556 static int __fat_readdir(struct inode *inode, struct file *file,
557 			 struct dir_context *ctx, int short_only,
558 			 struct fat_ioctl_filldir_callback *both)
559 {
560 	struct super_block *sb = inode->i_sb;
561 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
562 	struct buffer_head *bh;
563 	struct msdos_dir_entry *de;
564 	unsigned char nr_slots;
565 	wchar_t *unicode = NULL;
566 	unsigned char bufname[FAT_MAX_SHORT_SIZE];
567 	int isvfat = sbi->options.isvfat;
568 	const char *fill_name = NULL;
569 	int fake_offset = 0;
570 	loff_t cpos;
571 	int short_len = 0, fill_len = 0;
572 	int ret = 0;
573 
574 	mutex_lock(&sbi->s_lock);
575 
576 	cpos = ctx->pos;
577 	/* Fake . and .. for the root directory. */
578 	if (inode->i_ino == MSDOS_ROOT_INO) {
579 		if (!dir_emit_dots(file, ctx))
580 			goto out;
581 		if (ctx->pos == 2) {
582 			fake_offset = 1;
583 			cpos = 0;
584 		}
585 	}
586 	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
587 		ret = -ENOENT;
588 		goto out;
589 	}
590 
591 	bh = NULL;
592 get_new:
593 	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
594 		goto end_of_dir;
595 parse_record:
596 	nr_slots = 0;
597 	/*
598 	 * Check for long filename entry, but if short_only, we don't
599 	 * need to parse long filename.
600 	 */
601 	if (isvfat && !short_only) {
602 		if (de->name[0] == DELETED_FLAG)
603 			goto record_end;
604 		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
605 			goto record_end;
606 		if (de->attr != ATTR_EXT && IS_FREE(de->name))
607 			goto record_end;
608 	} else {
609 		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
610 			goto record_end;
611 	}
612 
613 	if (isvfat && de->attr == ATTR_EXT) {
614 		int status = fat_parse_long(inode, &cpos, &bh, &de,
615 					    &unicode, &nr_slots);
616 		if (status < 0) {
617 			ctx->pos = cpos;
618 			ret = status;
619 			goto out;
620 		} else if (status == PARSE_INVALID)
621 			goto record_end;
622 		else if (status == PARSE_NOT_LONGNAME)
623 			goto parse_record;
624 		else if (status == PARSE_EOF)
625 			goto end_of_dir;
626 
627 		if (nr_slots) {
628 			void *longname = unicode + FAT_MAX_UNI_CHARS;
629 			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
630 			int len = fat_uni_to_x8(sb, unicode, longname, size);
631 
632 			fill_name = longname;
633 			fill_len = len;
634 			/* !both && !short_only, so we don't need shortname. */
635 			if (!both)
636 				goto start_filldir;
637 
638 			short_len = fat_parse_short(sb, de, bufname,
639 						    sbi->options.dotsOK);
640 			if (short_len == 0)
641 				goto record_end;
642 			/* hack for fat_ioctl_filldir() */
643 			both->longname = fill_name;
644 			both->long_len = fill_len;
645 			both->shortname = bufname;
646 			both->short_len = short_len;
647 			fill_name = NULL;
648 			fill_len = 0;
649 			goto start_filldir;
650 		}
651 	}
652 
653 	short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
654 	if (short_len == 0)
655 		goto record_end;
656 
657 	fill_name = bufname;
658 	fill_len = short_len;
659 
660 start_filldir:
661 	if (!fake_offset)
662 		ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
663 
664 	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
665 		if (!dir_emit_dot(file, ctx))
666 			goto fill_failed;
667 	} else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
668 		if (!dir_emit_dotdot(file, ctx))
669 			goto fill_failed;
670 	} else {
671 		unsigned long inum;
672 		loff_t i_pos = fat_make_i_pos(sb, bh, de);
673 		struct inode *tmp = fat_iget(sb, i_pos);
674 		if (tmp) {
675 			inum = tmp->i_ino;
676 			iput(tmp);
677 		} else
678 			inum = iunique(sb, MSDOS_ROOT_INO);
679 		if (!dir_emit(ctx, fill_name, fill_len, inum,
680 			    (de->attr & ATTR_DIR) ? DT_DIR : DT_REG))
681 			goto fill_failed;
682 	}
683 
684 record_end:
685 	fake_offset = 0;
686 	ctx->pos = cpos;
687 	goto get_new;
688 end_of_dir:
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 	return ret;
697 }
698 
699 static int fat_readdir(struct file *file, struct dir_context *ctx)
700 {
701 	return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
702 }
703 
704 #define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
705 static int func(void *__buf, const char *name, int name_len,		   \
706 			     loff_t offset, u64 ino, unsigned int d_type)  \
707 {									   \
708 	struct fat_ioctl_filldir_callback *buf = __buf;			   \
709 	struct dirent_type __user *d1 = buf->dirent;			   \
710 	struct dirent_type __user *d2 = d1 + 1;				   \
711 									   \
712 	if (buf->result)						   \
713 		return -EINVAL;						   \
714 	buf->result++;							   \
715 									   \
716 	if (name != NULL) {						   \
717 		/* dirent has only short name */			   \
718 		if (name_len >= sizeof(d1->d_name))			   \
719 			name_len = sizeof(d1->d_name) - 1;		   \
720 									   \
721 		if (put_user(0, d2->d_name)			||	   \
722 		    put_user(0, &d2->d_reclen)			||	   \
723 		    copy_to_user(d1->d_name, name, name_len)	||	   \
724 		    put_user(0, d1->d_name + name_len)		||	   \
725 		    put_user(name_len, &d1->d_reclen))			   \
726 			goto efault;					   \
727 	} else {							   \
728 		/* dirent has short and long name */			   \
729 		const char *longname = buf->longname;			   \
730 		int long_len = buf->long_len;				   \
731 		const char *shortname = buf->shortname;			   \
732 		int short_len = buf->short_len;				   \
733 									   \
734 		if (long_len >= sizeof(d1->d_name))			   \
735 			long_len = sizeof(d1->d_name) - 1;		   \
736 		if (short_len >= sizeof(d1->d_name))			   \
737 			short_len = sizeof(d1->d_name) - 1;		   \
738 									   \
739 		if (copy_to_user(d2->d_name, longname, long_len)	|| \
740 		    put_user(0, d2->d_name + long_len)			|| \
741 		    put_user(long_len, &d2->d_reclen)			|| \
742 		    put_user(ino, &d2->d_ino)				|| \
743 		    put_user(offset, &d2->d_off)			|| \
744 		    copy_to_user(d1->d_name, shortname, short_len)	|| \
745 		    put_user(0, d1->d_name + short_len)			|| \
746 		    put_user(short_len, &d1->d_reclen))			   \
747 			goto efault;					   \
748 	}								   \
749 	return 0;							   \
750 efault:									   \
751 	buf->result = -EFAULT;						   \
752 	return -EFAULT;							   \
753 }
754 
755 FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
756 
757 static int fat_ioctl_readdir(struct inode *inode, struct file *file,
758 			     void __user *dirent, filldir_t filldir,
759 			     int short_only, int both)
760 {
761 	struct fat_ioctl_filldir_callback buf = {
762 		.ctx.actor = filldir,
763 		.dirent = dirent
764 	};
765 	int ret;
766 
767 	buf.dirent = dirent;
768 	buf.result = 0;
769 	mutex_lock(&inode->i_mutex);
770 	buf.ctx.pos = file->f_pos;
771 	ret = -ENOENT;
772 	if (!IS_DEADDIR(inode)) {
773 		ret = __fat_readdir(inode, file, &buf.ctx,
774 				    short_only, both ? &buf : NULL);
775 		file->f_pos = buf.ctx.pos;
776 	}
777 	mutex_unlock(&inode->i_mutex);
778 	if (ret >= 0)
779 		ret = buf.result;
780 	return ret;
781 }
782 
783 static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
784 			  unsigned long arg)
785 {
786 	struct inode *inode = file_inode(filp);
787 	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
788 	int short_only, both;
789 
790 	switch (cmd) {
791 	case VFAT_IOCTL_READDIR_SHORT:
792 		short_only = 1;
793 		both = 0;
794 		break;
795 	case VFAT_IOCTL_READDIR_BOTH:
796 		short_only = 0;
797 		both = 1;
798 		break;
799 	default:
800 		return fat_generic_ioctl(filp, cmd, arg);
801 	}
802 
803 	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct __fat_dirent[2])))
804 		return -EFAULT;
805 	/*
806 	 * Yes, we don't need this put_user() absolutely. However old
807 	 * code didn't return the right value. So, app use this value,
808 	 * in order to check whether it is EOF.
809 	 */
810 	if (put_user(0, &d1->d_reclen))
811 		return -EFAULT;
812 
813 	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
814 				 short_only, both);
815 }
816 
817 #ifdef CONFIG_COMPAT
818 #define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
819 #define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])
820 
821 FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
822 
823 static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
824 				 unsigned long arg)
825 {
826 	struct inode *inode = file_inode(filp);
827 	struct compat_dirent __user *d1 = compat_ptr(arg);
828 	int short_only, both;
829 
830 	switch (cmd) {
831 	case VFAT_IOCTL_READDIR_SHORT32:
832 		short_only = 1;
833 		both = 0;
834 		break;
835 	case VFAT_IOCTL_READDIR_BOTH32:
836 		short_only = 0;
837 		both = 1;
838 		break;
839 	default:
840 		return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
841 	}
842 
843 	if (!access_ok(VERIFY_WRITE, d1, sizeof(struct compat_dirent[2])))
844 		return -EFAULT;
845 	/*
846 	 * Yes, we don't need this put_user() absolutely. However old
847 	 * code didn't return the right value. So, app use this value,
848 	 * in order to check whether it is EOF.
849 	 */
850 	if (put_user(0, &d1->d_reclen))
851 		return -EFAULT;
852 
853 	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
854 				 short_only, both);
855 }
856 #endif /* CONFIG_COMPAT */
857 
858 const struct file_operations fat_dir_operations = {
859 	.llseek		= generic_file_llseek,
860 	.read		= generic_read_dir,
861 	.iterate	= fat_readdir,
862 	.unlocked_ioctl	= fat_dir_ioctl,
863 #ifdef CONFIG_COMPAT
864 	.compat_ioctl	= fat_compat_dir_ioctl,
865 #endif
866 	.fsync		= fat_file_fsync,
867 };
868 
869 static int fat_get_short_entry(struct inode *dir, loff_t *pos,
870 			       struct buffer_head **bh,
871 			       struct msdos_dir_entry **de)
872 {
873 	while (fat_get_entry(dir, pos, bh, de) >= 0) {
874 		/* free entry or long name entry or volume label */
875 		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
876 			return 0;
877 	}
878 	return -ENOENT;
879 }
880 
881 /*
882  * The ".." entry can not provide the "struct fat_slot_info" information
883  * for inode, nor a usable i_pos. So, this function provides some information
884  * only.
885  *
886  * Since this function walks through the on-disk inodes within a directory,
887  * callers are responsible for taking any locks necessary to prevent the
888  * directory from changing.
889  */
890 int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
891 			 struct msdos_dir_entry **de)
892 {
893 	loff_t offset = 0;
894 
895 	*de = NULL;
896 	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
897 		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
898 			return 0;
899 	}
900 	return -ENOENT;
901 }
902 EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
903 
904 /* See if directory is empty */
905 int fat_dir_empty(struct inode *dir)
906 {
907 	struct buffer_head *bh;
908 	struct msdos_dir_entry *de;
909 	loff_t cpos;
910 	int result = 0;
911 
912 	bh = NULL;
913 	cpos = 0;
914 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
915 		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
916 		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
917 			result = -ENOTEMPTY;
918 			break;
919 		}
920 	}
921 	brelse(bh);
922 	return result;
923 }
924 EXPORT_SYMBOL_GPL(fat_dir_empty);
925 
926 /*
927  * fat_subdirs counts the number of sub-directories of dir. It can be run
928  * on directories being created.
929  */
930 int fat_subdirs(struct inode *dir)
931 {
932 	struct buffer_head *bh;
933 	struct msdos_dir_entry *de;
934 	loff_t cpos;
935 	int count = 0;
936 
937 	bh = NULL;
938 	cpos = 0;
939 	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
940 		if (de->attr & ATTR_DIR)
941 			count++;
942 	}
943 	brelse(bh);
944 	return count;
945 }
946 
947 /*
948  * Scans a directory for a given file (name points to its formatted name).
949  * Returns an error code or zero.
950  */
951 int fat_scan(struct inode *dir, const unsigned char *name,
952 	     struct fat_slot_info *sinfo)
953 {
954 	struct super_block *sb = dir->i_sb;
955 
956 	sinfo->slot_off = 0;
957 	sinfo->bh = NULL;
958 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
959 				   &sinfo->de) >= 0) {
960 		if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
961 			sinfo->slot_off -= sizeof(*sinfo->de);
962 			sinfo->nr_slots = 1;
963 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
964 			return 0;
965 		}
966 	}
967 	return -ENOENT;
968 }
969 EXPORT_SYMBOL_GPL(fat_scan);
970 
971 /*
972  * Scans a directory for a given logstart.
973  * Returns an error code or zero.
974  */
975 int fat_scan_logstart(struct inode *dir, int i_logstart,
976 		      struct fat_slot_info *sinfo)
977 {
978 	struct super_block *sb = dir->i_sb;
979 
980 	sinfo->slot_off = 0;
981 	sinfo->bh = NULL;
982 	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
983 				   &sinfo->de) >= 0) {
984 		if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
985 			sinfo->slot_off -= sizeof(*sinfo->de);
986 			sinfo->nr_slots = 1;
987 			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
988 			return 0;
989 		}
990 	}
991 	return -ENOENT;
992 }
993 
994 static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
995 {
996 	struct super_block *sb = dir->i_sb;
997 	struct buffer_head *bh;
998 	struct msdos_dir_entry *de, *endp;
999 	int err = 0, orig_slots;
1000 
1001 	while (nr_slots) {
1002 		bh = NULL;
1003 		if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1004 			err = -EIO;
1005 			break;
1006 		}
1007 
1008 		orig_slots = nr_slots;
1009 		endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1010 		while (nr_slots && de < endp) {
1011 			de->name[0] = DELETED_FLAG;
1012 			de++;
1013 			nr_slots--;
1014 		}
1015 		mark_buffer_dirty_inode(bh, dir);
1016 		if (IS_DIRSYNC(dir))
1017 			err = sync_dirty_buffer(bh);
1018 		brelse(bh);
1019 		if (err)
1020 			break;
1021 
1022 		/* pos is *next* de's position, so this does `- sizeof(de)' */
1023 		pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1024 	}
1025 
1026 	return err;
1027 }
1028 
1029 int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1030 {
1031 	struct super_block *sb = dir->i_sb;
1032 	struct msdos_dir_entry *de;
1033 	struct buffer_head *bh;
1034 	int err = 0, nr_slots;
1035 
1036 	/*
1037 	 * First stage: Remove the shortname. By this, the directory
1038 	 * entry is removed.
1039 	 */
1040 	nr_slots = sinfo->nr_slots;
1041 	de = sinfo->de;
1042 	sinfo->de = NULL;
1043 	bh = sinfo->bh;
1044 	sinfo->bh = NULL;
1045 	while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1046 		de->name[0] = DELETED_FLAG;
1047 		de--;
1048 		nr_slots--;
1049 	}
1050 	mark_buffer_dirty_inode(bh, dir);
1051 	if (IS_DIRSYNC(dir))
1052 		err = sync_dirty_buffer(bh);
1053 	brelse(bh);
1054 	if (err)
1055 		return err;
1056 	dir->i_version++;
1057 
1058 	if (nr_slots) {
1059 		/*
1060 		 * Second stage: remove the remaining longname slots.
1061 		 * (This directory entry is already removed, and so return
1062 		 * the success)
1063 		 */
1064 		err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1065 		if (err) {
1066 			fat_msg(sb, KERN_WARNING,
1067 			       "Couldn't remove the long name slots");
1068 		}
1069 	}
1070 
1071 	dir->i_mtime = dir->i_atime = CURRENT_TIME_SEC;
1072 	if (IS_DIRSYNC(dir))
1073 		(void)fat_sync_inode(dir);
1074 	else
1075 		mark_inode_dirty(dir);
1076 
1077 	return 0;
1078 }
1079 EXPORT_SYMBOL_GPL(fat_remove_entries);
1080 
1081 static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1082 			      struct buffer_head **bhs, int nr_bhs)
1083 {
1084 	struct super_block *sb = dir->i_sb;
1085 	sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1086 	int err, i, n;
1087 
1088 	/* Zeroing the unused blocks on this cluster */
1089 	blknr += nr_used;
1090 	n = nr_used;
1091 	while (blknr < last_blknr) {
1092 		bhs[n] = sb_getblk(sb, blknr);
1093 		if (!bhs[n]) {
1094 			err = -ENOMEM;
1095 			goto error;
1096 		}
1097 		memset(bhs[n]->b_data, 0, sb->s_blocksize);
1098 		set_buffer_uptodate(bhs[n]);
1099 		mark_buffer_dirty_inode(bhs[n], dir);
1100 
1101 		n++;
1102 		blknr++;
1103 		if (n == nr_bhs) {
1104 			if (IS_DIRSYNC(dir)) {
1105 				err = fat_sync_bhs(bhs, n);
1106 				if (err)
1107 					goto error;
1108 			}
1109 			for (i = 0; i < n; i++)
1110 				brelse(bhs[i]);
1111 			n = 0;
1112 		}
1113 	}
1114 	if (IS_DIRSYNC(dir)) {
1115 		err = fat_sync_bhs(bhs, n);
1116 		if (err)
1117 			goto error;
1118 	}
1119 	for (i = 0; i < n; i++)
1120 		brelse(bhs[i]);
1121 
1122 	return 0;
1123 
1124 error:
1125 	for (i = 0; i < n; i++)
1126 		bforget(bhs[i]);
1127 	return err;
1128 }
1129 
1130 int fat_alloc_new_dir(struct inode *dir, struct timespec *ts)
1131 {
1132 	struct super_block *sb = dir->i_sb;
1133 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1134 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1135 	struct msdos_dir_entry *de;
1136 	sector_t blknr;
1137 	__le16 date, time;
1138 	u8 time_cs;
1139 	int err, cluster;
1140 
1141 	err = fat_alloc_clusters(dir, &cluster, 1);
1142 	if (err)
1143 		goto error;
1144 
1145 	blknr = fat_clus_to_blknr(sbi, cluster);
1146 	bhs[0] = sb_getblk(sb, blknr);
1147 	if (!bhs[0]) {
1148 		err = -ENOMEM;
1149 		goto error_free;
1150 	}
1151 
1152 	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1153 
1154 	de = (struct msdos_dir_entry *)bhs[0]->b_data;
1155 	/* filling the new directory slots ("." and ".." entries) */
1156 	memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1157 	memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1158 	de->attr = de[1].attr = ATTR_DIR;
1159 	de[0].lcase = de[1].lcase = 0;
1160 	de[0].time = de[1].time = time;
1161 	de[0].date = de[1].date = date;
1162 	if (sbi->options.isvfat) {
1163 		/* extra timestamps */
1164 		de[0].ctime = de[1].ctime = time;
1165 		de[0].ctime_cs = de[1].ctime_cs = time_cs;
1166 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1167 	} else {
1168 		de[0].ctime = de[1].ctime = 0;
1169 		de[0].ctime_cs = de[1].ctime_cs = 0;
1170 		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1171 	}
1172 	fat_set_start(&de[0], cluster);
1173 	fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1174 	de[0].size = de[1].size = 0;
1175 	memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1176 	set_buffer_uptodate(bhs[0]);
1177 	mark_buffer_dirty_inode(bhs[0], dir);
1178 
1179 	err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1180 	if (err)
1181 		goto error_free;
1182 
1183 	return cluster;
1184 
1185 error_free:
1186 	fat_free_clusters(dir, cluster);
1187 error:
1188 	return err;
1189 }
1190 EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1191 
1192 static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1193 			       int *nr_cluster, struct msdos_dir_entry **de,
1194 			       struct buffer_head **bh, loff_t *i_pos)
1195 {
1196 	struct super_block *sb = dir->i_sb;
1197 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1198 	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1199 	sector_t blknr, start_blknr, last_blknr;
1200 	unsigned long size, copy;
1201 	int err, i, n, offset, cluster[2];
1202 
1203 	/*
1204 	 * The minimum cluster size is 512bytes, and maximum entry
1205 	 * size is 32*slots (672bytes).  So, iff the cluster size is
1206 	 * 512bytes, we may need two clusters.
1207 	 */
1208 	size = nr_slots * sizeof(struct msdos_dir_entry);
1209 	*nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1210 	BUG_ON(*nr_cluster > 2);
1211 
1212 	err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1213 	if (err)
1214 		goto error;
1215 
1216 	/*
1217 	 * First stage: Fill the directory entry.  NOTE: This cluster
1218 	 * is not referenced from any inode yet, so updates order is
1219 	 * not important.
1220 	 */
1221 	i = n = copy = 0;
1222 	do {
1223 		start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1224 		last_blknr = start_blknr + sbi->sec_per_clus;
1225 		while (blknr < last_blknr) {
1226 			bhs[n] = sb_getblk(sb, blknr);
1227 			if (!bhs[n]) {
1228 				err = -ENOMEM;
1229 				goto error_nomem;
1230 			}
1231 
1232 			/* fill the directory entry */
1233 			copy = min(size, sb->s_blocksize);
1234 			memcpy(bhs[n]->b_data, slots, copy);
1235 			slots += copy;
1236 			size -= copy;
1237 			set_buffer_uptodate(bhs[n]);
1238 			mark_buffer_dirty_inode(bhs[n], dir);
1239 			if (!size)
1240 				break;
1241 			n++;
1242 			blknr++;
1243 		}
1244 	} while (++i < *nr_cluster);
1245 
1246 	memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1247 	offset = copy - sizeof(struct msdos_dir_entry);
1248 	get_bh(bhs[n]);
1249 	*bh = bhs[n];
1250 	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1251 	*i_pos = fat_make_i_pos(sb, *bh, *de);
1252 
1253 	/* Second stage: clear the rest of cluster, and write outs */
1254 	err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1255 	if (err)
1256 		goto error_free;
1257 
1258 	return cluster[0];
1259 
1260 error_free:
1261 	brelse(*bh);
1262 	*bh = NULL;
1263 	n = 0;
1264 error_nomem:
1265 	for (i = 0; i < n; i++)
1266 		bforget(bhs[i]);
1267 	fat_free_clusters(dir, cluster[0]);
1268 error:
1269 	return err;
1270 }
1271 
1272 int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1273 		    struct fat_slot_info *sinfo)
1274 {
1275 	struct super_block *sb = dir->i_sb;
1276 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1277 	struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1278 	struct msdos_dir_entry *uninitialized_var(de);
1279 	int err, free_slots, i, nr_bhs;
1280 	loff_t pos, i_pos;
1281 
1282 	sinfo->nr_slots = nr_slots;
1283 
1284 	/* First stage: search free directory entries */
1285 	free_slots = nr_bhs = 0;
1286 	bh = prev = NULL;
1287 	pos = 0;
1288 	err = -ENOSPC;
1289 	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1290 		/* check the maximum size of directory */
1291 		if (pos >= FAT_MAX_DIR_SIZE)
1292 			goto error;
1293 
1294 		if (IS_FREE(de->name)) {
1295 			if (prev != bh) {
1296 				get_bh(bh);
1297 				bhs[nr_bhs] = prev = bh;
1298 				nr_bhs++;
1299 			}
1300 			free_slots++;
1301 			if (free_slots == nr_slots)
1302 				goto found;
1303 		} else {
1304 			for (i = 0; i < nr_bhs; i++)
1305 				brelse(bhs[i]);
1306 			prev = NULL;
1307 			free_slots = nr_bhs = 0;
1308 		}
1309 	}
1310 	if (dir->i_ino == MSDOS_ROOT_INO) {
1311 		if (sbi->fat_bits != 32)
1312 			goto error;
1313 	} else if (MSDOS_I(dir)->i_start == 0) {
1314 		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1315 		       MSDOS_I(dir)->i_pos);
1316 		err = -EIO;
1317 		goto error;
1318 	}
1319 
1320 found:
1321 	err = 0;
1322 	pos -= free_slots * sizeof(*de);
1323 	nr_slots -= free_slots;
1324 	if (free_slots) {
1325 		/*
1326 		 * Second stage: filling the free entries with new entries.
1327 		 * NOTE: If this slots has shortname, first, we write
1328 		 * the long name slots, then write the short name.
1329 		 */
1330 		int size = free_slots * sizeof(*de);
1331 		int offset = pos & (sb->s_blocksize - 1);
1332 		int long_bhs = nr_bhs - (nr_slots == 0);
1333 
1334 		/* Fill the long name slots. */
1335 		for (i = 0; i < long_bhs; i++) {
1336 			int copy = min_t(int, sb->s_blocksize - offset, size);
1337 			memcpy(bhs[i]->b_data + offset, slots, copy);
1338 			mark_buffer_dirty_inode(bhs[i], dir);
1339 			offset = 0;
1340 			slots += copy;
1341 			size -= copy;
1342 		}
1343 		if (long_bhs && IS_DIRSYNC(dir))
1344 			err = fat_sync_bhs(bhs, long_bhs);
1345 		if (!err && i < nr_bhs) {
1346 			/* Fill the short name slot. */
1347 			int copy = min_t(int, sb->s_blocksize - offset, size);
1348 			memcpy(bhs[i]->b_data + offset, slots, copy);
1349 			mark_buffer_dirty_inode(bhs[i], dir);
1350 			if (IS_DIRSYNC(dir))
1351 				err = sync_dirty_buffer(bhs[i]);
1352 		}
1353 		for (i = 0; i < nr_bhs; i++)
1354 			brelse(bhs[i]);
1355 		if (err)
1356 			goto error_remove;
1357 	}
1358 
1359 	if (nr_slots) {
1360 		int cluster, nr_cluster;
1361 
1362 		/*
1363 		 * Third stage: allocate the cluster for new entries.
1364 		 * And initialize the cluster with new entries, then
1365 		 * add the cluster to dir.
1366 		 */
1367 		cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1368 					      &de, &bh, &i_pos);
1369 		if (cluster < 0) {
1370 			err = cluster;
1371 			goto error_remove;
1372 		}
1373 		err = fat_chain_add(dir, cluster, nr_cluster);
1374 		if (err) {
1375 			fat_free_clusters(dir, cluster);
1376 			goto error_remove;
1377 		}
1378 		if (dir->i_size & (sbi->cluster_size - 1)) {
1379 			fat_fs_error(sb, "Odd directory size");
1380 			dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1381 				& ~((loff_t)sbi->cluster_size - 1);
1382 		}
1383 		dir->i_size += nr_cluster << sbi->cluster_bits;
1384 		MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1385 	}
1386 	sinfo->slot_off = pos;
1387 	sinfo->de = de;
1388 	sinfo->bh = bh;
1389 	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1390 
1391 	return 0;
1392 
1393 error:
1394 	brelse(bh);
1395 	for (i = 0; i < nr_bhs; i++)
1396 		brelse(bhs[i]);
1397 	return err;
1398 
1399 error_remove:
1400 	brelse(bh);
1401 	if (free_slots)
1402 		__fat_remove_entries(dir, pos, free_slots);
1403 	return err;
1404 }
1405 EXPORT_SYMBOL_GPL(fat_add_entries);
1406