xref: /openbmc/linux/fs/fat/dir.c (revision 457c8996)
1  // SPDX-License-Identifier: GPL-2.0-only
2  /*
3   *  linux/fs/fat/dir.c
4   *
5   *  directory handling functions for fat-based filesystems
6   *
7   *  Written 1992,1993 by Werner Almesberger
8   *
9   *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
10   *
11   *  VFAT extensions by Gordon Chaffee <chaffee@plateau.cs.berkeley.edu>
12   *  Merged with msdos fs by Henrik Storner <storner@osiris.ping.dk>
13   *  Rewritten for constant inumbers. Plugged buffer overrun in readdir(). AV
14   *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
15   */
16  
17  #include <linux/slab.h>
18  #include <linux/compat.h>
19  #include <linux/uaccess.h>
20  #include <linux/iversion.h>
21  #include "fat.h"
22  
23  /*
24   * Maximum buffer size of short name.
25   * [(MSDOS_NAME + '.') * max one char + nul]
26   * For msdos style, ['.' (hidden) + MSDOS_NAME + '.' + nul]
27   */
28  #define FAT_MAX_SHORT_SIZE	((MSDOS_NAME + 1) * NLS_MAX_CHARSET_SIZE + 1)
29  /*
30   * Maximum buffer size of unicode chars from slots.
31   * [(max longname slots * 13 (size in a slot) + nul) * sizeof(wchar_t)]
32   */
33  #define FAT_MAX_UNI_CHARS	((MSDOS_SLOTS - 1) * 13 + 1)
34  #define FAT_MAX_UNI_SIZE	(FAT_MAX_UNI_CHARS * sizeof(wchar_t))
35  
36  static inline unsigned char fat_tolower(unsigned char c)
37  {
38  	return ((c >= 'A') && (c <= 'Z')) ? c+32 : c;
39  }
40  
41  static inline loff_t fat_make_i_pos(struct super_block *sb,
42  				    struct buffer_head *bh,
43  				    struct msdos_dir_entry *de)
44  {
45  	return ((loff_t)bh->b_blocknr << MSDOS_SB(sb)->dir_per_block_bits)
46  		| (de - (struct msdos_dir_entry *)bh->b_data);
47  }
48  
49  static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
50  				     sector_t phys)
51  {
52  	struct super_block *sb = dir->i_sb;
53  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
54  	struct buffer_head *bh;
55  	int sec;
56  
57  	/* This is not a first sector of cluster, or sec_per_clus == 1 */
58  	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
59  		return;
60  	/* root dir of FAT12/FAT16 */
61  	if (!is_fat32(sbi) && (dir->i_ino == MSDOS_ROOT_INO))
62  		return;
63  
64  	bh = sb_find_get_block(sb, phys);
65  	if (bh == NULL || !buffer_uptodate(bh)) {
66  		for (sec = 0; sec < sbi->sec_per_clus; sec++)
67  			sb_breadahead(sb, phys + sec);
68  	}
69  	brelse(bh);
70  }
71  
72  /* Returns the inode number of the directory entry at offset pos. If bh is
73     non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
74     returned in bh.
75     AV. Most often we do it item-by-item. Makes sense to optimize.
76     AV. OK, there we go: if both bh and de are non-NULL we assume that we just
77     AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
78     AV. It's done in fat_get_entry() (inlined), here the slow case lives.
79     AV. Additionally, when we return -1 (i.e. reached the end of directory)
80     AV. we make bh NULL.
81   */
82  static int fat__get_entry(struct inode *dir, loff_t *pos,
83  			  struct buffer_head **bh, struct msdos_dir_entry **de)
84  {
85  	struct super_block *sb = dir->i_sb;
86  	sector_t phys, iblock;
87  	unsigned long mapped_blocks;
88  	int err, offset;
89  
90  next:
91  	if (*bh)
92  		brelse(*bh);
93  
94  	*bh = NULL;
95  	iblock = *pos >> sb->s_blocksize_bits;
96  	err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0, false);
97  	if (err || !phys)
98  		return -1;	/* beyond EOF or error */
99  
100  	fat_dir_readahead(dir, iblock, phys);
101  
102  	*bh = sb_bread(sb, phys);
103  	if (*bh == NULL) {
104  		fat_msg_ratelimit(sb, KERN_ERR,
105  			"Directory bread(block %llu) failed", (llu)phys);
106  		/* skip this block */
107  		*pos = (iblock + 1) << sb->s_blocksize_bits;
108  		goto next;
109  	}
110  
111  	offset = *pos & (sb->s_blocksize - 1);
112  	*pos += sizeof(struct msdos_dir_entry);
113  	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
114  
115  	return 0;
116  }
117  
118  static inline int fat_get_entry(struct inode *dir, loff_t *pos,
119  				struct buffer_head **bh,
120  				struct msdos_dir_entry **de)
121  {
122  	/* Fast stuff first */
123  	if (*bh && *de &&
124  	   (*de - (struct msdos_dir_entry *)(*bh)->b_data) <
125  				MSDOS_SB(dir->i_sb)->dir_per_block - 1) {
126  		*pos += sizeof(struct msdos_dir_entry);
127  		(*de)++;
128  		return 0;
129  	}
130  	return fat__get_entry(dir, pos, bh, de);
131  }
132  
133  /*
134   * Convert Unicode 16 to UTF-8, translated Unicode, or ASCII.
135   * If uni_xlate is enabled and we can't get a 1:1 conversion, use a
136   * colon as an escape character since it is normally invalid on the vfat
137   * filesystem. The following four characters are the hexadecimal digits
138   * of Unicode value. This lets us do a full dump and restore of Unicode
139   * filenames. We could get into some trouble with long Unicode names,
140   * but ignore that right now.
141   * Ahem... Stack smashing in ring 0 isn't fun. Fixed.
142   */
143  static int uni16_to_x8(struct super_block *sb, unsigned char *ascii,
144  		       const wchar_t *uni, int len, struct nls_table *nls)
145  {
146  	int uni_xlate = MSDOS_SB(sb)->options.unicode_xlate;
147  	const wchar_t *ip;
148  	wchar_t ec;
149  	unsigned char *op;
150  	int charlen;
151  
152  	ip = uni;
153  	op = ascii;
154  
155  	while (*ip && ((len - NLS_MAX_CHARSET_SIZE) > 0)) {
156  		ec = *ip++;
157  		charlen = nls->uni2char(ec, op, NLS_MAX_CHARSET_SIZE);
158  		if (charlen > 0) {
159  			op += charlen;
160  			len -= charlen;
161  		} else {
162  			if (uni_xlate == 1) {
163  				*op++ = ':';
164  				op = hex_byte_pack(op, ec >> 8);
165  				op = hex_byte_pack(op, ec);
166  				len -= 5;
167  			} else {
168  				*op++ = '?';
169  				len--;
170  			}
171  		}
172  	}
173  
174  	if (unlikely(*ip)) {
175  		fat_msg(sb, KERN_WARNING,
176  			"filename was truncated while converting.");
177  	}
178  
179  	*op = 0;
180  	return op - ascii;
181  }
182  
183  static inline int fat_uni_to_x8(struct super_block *sb, const wchar_t *uni,
184  				unsigned char *buf, int size)
185  {
186  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
187  	if (sbi->options.utf8)
188  		return utf16s_to_utf8s(uni, FAT_MAX_UNI_CHARS,
189  				UTF16_HOST_ENDIAN, buf, size);
190  	else
191  		return uni16_to_x8(sb, buf, uni, size, sbi->nls_io);
192  }
193  
194  static inline int
195  fat_short2uni(struct nls_table *t, unsigned char *c, int clen, wchar_t *uni)
196  {
197  	int charlen;
198  
199  	charlen = t->char2uni(c, clen, uni);
200  	if (charlen < 0) {
201  		*uni = 0x003f;	/* a question mark */
202  		charlen = 1;
203  	}
204  	return charlen;
205  }
206  
207  static inline int
208  fat_short2lower_uni(struct nls_table *t, unsigned char *c,
209  		    int clen, wchar_t *uni)
210  {
211  	int charlen;
212  	wchar_t wc;
213  
214  	charlen = t->char2uni(c, clen, &wc);
215  	if (charlen < 0) {
216  		*uni = 0x003f;	/* a question mark */
217  		charlen = 1;
218  	} else if (charlen <= 1) {
219  		unsigned char nc = t->charset2lower[*c];
220  
221  		if (!nc)
222  			nc = *c;
223  
224  		charlen = t->char2uni(&nc, 1, uni);
225  		if (charlen < 0) {
226  			*uni = 0x003f;	/* a question mark */
227  			charlen = 1;
228  		}
229  	} else
230  		*uni = wc;
231  
232  	return charlen;
233  }
234  
235  static inline int
236  fat_shortname2uni(struct nls_table *nls, unsigned char *buf, int buf_size,
237  		  wchar_t *uni_buf, unsigned short opt, int lower)
238  {
239  	int len = 0;
240  
241  	if (opt & VFAT_SFN_DISPLAY_LOWER)
242  		len =  fat_short2lower_uni(nls, buf, buf_size, uni_buf);
243  	else if (opt & VFAT_SFN_DISPLAY_WIN95)
244  		len = fat_short2uni(nls, buf, buf_size, uni_buf);
245  	else if (opt & VFAT_SFN_DISPLAY_WINNT) {
246  		if (lower)
247  			len = fat_short2lower_uni(nls, buf, buf_size, uni_buf);
248  		else
249  			len = fat_short2uni(nls, buf, buf_size, uni_buf);
250  	} else
251  		len = fat_short2uni(nls, buf, buf_size, uni_buf);
252  
253  	return len;
254  }
255  
256  static inline int fat_name_match(struct msdos_sb_info *sbi,
257  				 const unsigned char *a, int a_len,
258  				 const unsigned char *b, int b_len)
259  {
260  	if (a_len != b_len)
261  		return 0;
262  
263  	if (sbi->options.name_check != 's')
264  		return !nls_strnicmp(sbi->nls_io, a, b, a_len);
265  	else
266  		return !memcmp(a, b, a_len);
267  }
268  
269  enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };
270  
271  /**
272   * fat_parse_long - Parse extended directory entry.
273   *
274   * This function returns zero on success, negative value on error, or one of
275   * the following:
276   *
277   * %PARSE_INVALID - Directory entry is invalid.
278   * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
279   * %PARSE_EOF - Directory has no more entries.
280   */
281  static int fat_parse_long(struct inode *dir, loff_t *pos,
282  			  struct buffer_head **bh, struct msdos_dir_entry **de,
283  			  wchar_t **unicode, unsigned char *nr_slots)
284  {
285  	struct msdos_dir_slot *ds;
286  	unsigned char id, slot, slots, alias_checksum;
287  
288  	if (!*unicode) {
289  		*unicode = __getname();
290  		if (!*unicode) {
291  			brelse(*bh);
292  			return -ENOMEM;
293  		}
294  	}
295  parse_long:
296  	ds = (struct msdos_dir_slot *)*de;
297  	id = ds->id;
298  	if (!(id & 0x40))
299  		return PARSE_INVALID;
300  	slots = id & ~0x40;
301  	if (slots > 20 || !slots)	/* ceil(256 * 2 / 26) */
302  		return PARSE_INVALID;
303  	*nr_slots = slots;
304  	alias_checksum = ds->alias_checksum;
305  
306  	slot = slots;
307  	while (1) {
308  		int offset;
309  
310  		slot--;
311  		offset = slot * 13;
312  		fat16_towchar(*unicode + offset, ds->name0_4, 5);
313  		fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
314  		fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);
315  
316  		if (ds->id & 0x40)
317  			(*unicode)[offset + 13] = 0;
318  		if (fat_get_entry(dir, pos, bh, de) < 0)
319  			return PARSE_EOF;
320  		if (slot == 0)
321  			break;
322  		ds = (struct msdos_dir_slot *)*de;
323  		if (ds->attr != ATTR_EXT)
324  			return PARSE_NOT_LONGNAME;
325  		if ((ds->id & ~0x40) != slot)
326  			goto parse_long;
327  		if (ds->alias_checksum != alias_checksum)
328  			goto parse_long;
329  	}
330  	if ((*de)->name[0] == DELETED_FLAG)
331  		return PARSE_INVALID;
332  	if ((*de)->attr == ATTR_EXT)
333  		goto parse_long;
334  	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
335  		return PARSE_INVALID;
336  	if (fat_checksum((*de)->name) != alias_checksum)
337  		*nr_slots = 0;
338  
339  	return 0;
340  }
341  
342  /**
343   * fat_parse_short - Parse MS-DOS (short) directory entry.
344   * @sb:		superblock
345   * @de:		directory entry to parse
346   * @name:	FAT_MAX_SHORT_SIZE array in which to place extracted name
347   * @dot_hidden:	Nonzero == prepend '.' to names with ATTR_HIDDEN
348   *
349   * Returns the number of characters extracted into 'name'.
350   */
351  static int fat_parse_short(struct super_block *sb,
352  			   const struct msdos_dir_entry *de,
353  			   unsigned char *name, int dot_hidden)
354  {
355  	const struct msdos_sb_info *sbi = MSDOS_SB(sb);
356  	int isvfat = sbi->options.isvfat;
357  	int nocase = sbi->options.nocase;
358  	unsigned short opt_shortname = sbi->options.shortname;
359  	struct nls_table *nls_disk = sbi->nls_disk;
360  	wchar_t uni_name[14];
361  	unsigned char c, work[MSDOS_NAME];
362  	unsigned char *ptname = name;
363  	int chi, chl, i, j, k;
364  	int dotoffset = 0;
365  	int name_len = 0, uni_len = 0;
366  
367  	if (!isvfat && dot_hidden && (de->attr & ATTR_HIDDEN)) {
368  		*ptname++ = '.';
369  		dotoffset = 1;
370  	}
371  
372  	memcpy(work, de->name, sizeof(work));
373  	/* For an explanation of the special treatment of 0x05 in
374  	 * filenames, see msdos_format_name in namei_msdos.c
375  	 */
376  	if (work[0] == 0x05)
377  		work[0] = 0xE5;
378  
379  	/* Filename */
380  	for (i = 0, j = 0; i < 8;) {
381  		c = work[i];
382  		if (!c)
383  			break;
384  		chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
385  					&uni_name[j++], opt_shortname,
386  					de->lcase & CASE_LOWER_BASE);
387  		if (chl <= 1) {
388  			if (!isvfat)
389  				ptname[i] = nocase ? c : fat_tolower(c);
390  			i++;
391  			if (c != ' ') {
392  				name_len = i;
393  				uni_len  = j;
394  			}
395  		} else {
396  			uni_len = j;
397  			if (isvfat)
398  				i += min(chl, 8-i);
399  			else {
400  				for (chi = 0; chi < chl && i < 8; chi++, i++)
401  					ptname[i] = work[i];
402  			}
403  			if (chl)
404  				name_len = i;
405  		}
406  	}
407  
408  	i = name_len;
409  	j = uni_len;
410  	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
411  	if (!isvfat)
412  		ptname[i] = '.';
413  	i++;
414  
415  	/* Extension */
416  	for (k = 8; k < MSDOS_NAME;) {
417  		c = work[k];
418  		if (!c)
419  			break;
420  		chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
421  					&uni_name[j++], opt_shortname,
422  					de->lcase & CASE_LOWER_EXT);
423  		if (chl <= 1) {
424  			k++;
425  			if (!isvfat)
426  				ptname[i] = nocase ? c : fat_tolower(c);
427  			i++;
428  			if (c != ' ') {
429  				name_len = i;
430  				uni_len  = j;
431  			}
432  		} else {
433  			uni_len = j;
434  			if (isvfat) {
435  				int offset = min(chl, MSDOS_NAME-k);
436  				k += offset;
437  				i += offset;
438  			} else {
439  				for (chi = 0; chi < chl && k < MSDOS_NAME;
440  				     chi++, i++, k++) {
441  						ptname[i] = work[k];
442  				}
443  			}
444  			if (chl)
445  				name_len = i;
446  		}
447  	}
448  
449  	if (name_len > 0) {
450  		name_len += dotoffset;
451  
452  		if (sbi->options.isvfat) {
453  			uni_name[uni_len] = 0x0000;
454  			name_len = fat_uni_to_x8(sb, uni_name, name,
455  						 FAT_MAX_SHORT_SIZE);
456  		}
457  	}
458  
459  	return name_len;
460  }
461  
462  /*
463   * Return values: negative -> error/not found, 0 -> found.
464   */
465  int fat_search_long(struct inode *inode, const unsigned char *name,
466  		    int name_len, struct fat_slot_info *sinfo)
467  {
468  	struct super_block *sb = inode->i_sb;
469  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
470  	struct buffer_head *bh = NULL;
471  	struct msdos_dir_entry *de;
472  	unsigned char nr_slots;
473  	wchar_t *unicode = NULL;
474  	unsigned char bufname[FAT_MAX_SHORT_SIZE];
475  	loff_t cpos = 0;
476  	int err, len;
477  
478  	err = -ENOENT;
479  	while (1) {
480  		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
481  			goto end_of_dir;
482  parse_record:
483  		nr_slots = 0;
484  		if (de->name[0] == DELETED_FLAG)
485  			continue;
486  		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
487  			continue;
488  		if (de->attr != ATTR_EXT && IS_FREE(de->name))
489  			continue;
490  		if (de->attr == ATTR_EXT) {
491  			int status = fat_parse_long(inode, &cpos, &bh, &de,
492  						    &unicode, &nr_slots);
493  			if (status < 0) {
494  				err = status;
495  				goto end_of_dir;
496  			} else if (status == PARSE_INVALID)
497  				continue;
498  			else if (status == PARSE_NOT_LONGNAME)
499  				goto parse_record;
500  			else if (status == PARSE_EOF)
501  				goto end_of_dir;
502  		}
503  
504  		/* Never prepend '.' to hidden files here.
505  		 * That is done only for msdos mounts (and only when
506  		 * 'dotsOK=yes'); if we are executing here, it is in the
507  		 * context of a vfat mount.
508  		 */
509  		len = fat_parse_short(sb, de, bufname, 0);
510  		if (len == 0)
511  			continue;
512  
513  		/* Compare shortname */
514  		if (fat_name_match(sbi, name, name_len, bufname, len))
515  			goto found;
516  
517  		if (nr_slots) {
518  			void *longname = unicode + FAT_MAX_UNI_CHARS;
519  			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
520  
521  			/* Compare longname */
522  			len = fat_uni_to_x8(sb, unicode, longname, size);
523  			if (fat_name_match(sbi, name, name_len, longname, len))
524  				goto found;
525  		}
526  	}
527  
528  found:
529  	nr_slots++;	/* include the de */
530  	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
531  	sinfo->nr_slots = nr_slots;
532  	sinfo->de = de;
533  	sinfo->bh = bh;
534  	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
535  	err = 0;
536  end_of_dir:
537  	if (unicode)
538  		__putname(unicode);
539  
540  	return err;
541  }
542  EXPORT_SYMBOL_GPL(fat_search_long);
543  
544  struct fat_ioctl_filldir_callback {
545  	struct dir_context ctx;
546  	void __user *dirent;
547  	int result;
548  	/* for dir ioctl */
549  	const char *longname;
550  	int long_len;
551  	const char *shortname;
552  	int short_len;
553  };
554  
555  static int __fat_readdir(struct inode *inode, struct file *file,
556  			 struct dir_context *ctx, int short_only,
557  			 struct fat_ioctl_filldir_callback *both)
558  {
559  	struct super_block *sb = inode->i_sb;
560  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
561  	struct buffer_head *bh;
562  	struct msdos_dir_entry *de;
563  	unsigned char nr_slots;
564  	wchar_t *unicode = NULL;
565  	unsigned char bufname[FAT_MAX_SHORT_SIZE];
566  	int isvfat = sbi->options.isvfat;
567  	const char *fill_name = NULL;
568  	int fake_offset = 0;
569  	loff_t cpos;
570  	int short_len = 0, fill_len = 0;
571  	int ret = 0;
572  
573  	mutex_lock(&sbi->s_lock);
574  
575  	cpos = ctx->pos;
576  	/* Fake . and .. for the root directory. */
577  	if (inode->i_ino == MSDOS_ROOT_INO) {
578  		if (!dir_emit_dots(file, ctx))
579  			goto out;
580  		if (ctx->pos == 2) {
581  			fake_offset = 1;
582  			cpos = 0;
583  		}
584  	}
585  	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
586  		ret = -ENOENT;
587  		goto out;
588  	}
589  
590  	bh = NULL;
591  get_new:
592  	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
593  		goto end_of_dir;
594  parse_record:
595  	nr_slots = 0;
596  	/*
597  	 * Check for long filename entry, but if short_only, we don't
598  	 * need to parse long filename.
599  	 */
600  	if (isvfat && !short_only) {
601  		if (de->name[0] == DELETED_FLAG)
602  			goto record_end;
603  		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
604  			goto record_end;
605  		if (de->attr != ATTR_EXT && IS_FREE(de->name))
606  			goto record_end;
607  	} else {
608  		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
609  			goto record_end;
610  	}
611  
612  	if (isvfat && de->attr == ATTR_EXT) {
613  		int status = fat_parse_long(inode, &cpos, &bh, &de,
614  					    &unicode, &nr_slots);
615  		if (status < 0) {
616  			bh = NULL;
617  			ret = status;
618  			goto end_of_dir;
619  		} else if (status == PARSE_INVALID)
620  			goto record_end;
621  		else if (status == PARSE_NOT_LONGNAME)
622  			goto parse_record;
623  		else if (status == PARSE_EOF)
624  			goto end_of_dir;
625  
626  		if (nr_slots) {
627  			void *longname = unicode + FAT_MAX_UNI_CHARS;
628  			int size = PATH_MAX - FAT_MAX_UNI_SIZE;
629  			int len = fat_uni_to_x8(sb, unicode, longname, size);
630  
631  			fill_name = longname;
632  			fill_len = len;
633  			/* !both && !short_only, so we don't need shortname. */
634  			if (!both)
635  				goto start_filldir;
636  
637  			short_len = fat_parse_short(sb, de, bufname,
638  						    sbi->options.dotsOK);
639  			if (short_len == 0)
640  				goto record_end;
641  			/* hack for fat_ioctl_filldir() */
642  			both->longname = fill_name;
643  			both->long_len = fill_len;
644  			both->shortname = bufname;
645  			both->short_len = short_len;
646  			fill_name = NULL;
647  			fill_len = 0;
648  			goto start_filldir;
649  		}
650  	}
651  
652  	short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
653  	if (short_len == 0)
654  		goto record_end;
655  
656  	fill_name = bufname;
657  	fill_len = short_len;
658  
659  start_filldir:
660  	ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
661  	if (fake_offset && ctx->pos < 2)
662  		ctx->pos = 2;
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  
689  end_of_dir:
690  	if (fake_offset && cpos < 2)
691  		ctx->pos = 2;
692  	else
693  		ctx->pos = cpos;
694  fill_failed:
695  	brelse(bh);
696  	if (unicode)
697  		__putname(unicode);
698  out:
699  	mutex_unlock(&sbi->s_lock);
700  
701  	return ret;
702  }
703  
704  static int fat_readdir(struct file *file, struct dir_context *ctx)
705  {
706  	return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
707  }
708  
709  #define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)			   \
710  static int func(struct dir_context *ctx, const char *name, int name_len,   \
711  			     loff_t offset, u64 ino, unsigned int d_type)  \
712  {									   \
713  	struct fat_ioctl_filldir_callback *buf =			   \
714  		container_of(ctx, struct fat_ioctl_filldir_callback, ctx); \
715  	struct dirent_type __user *d1 = buf->dirent;			   \
716  	struct dirent_type __user *d2 = d1 + 1;				   \
717  									   \
718  	if (buf->result)						   \
719  		return -EINVAL;						   \
720  	buf->result++;							   \
721  									   \
722  	if (name != NULL) {						   \
723  		/* dirent has only short name */			   \
724  		if (name_len >= sizeof(d1->d_name))			   \
725  			name_len = sizeof(d1->d_name) - 1;		   \
726  									   \
727  		if (put_user(0, d2->d_name)			||	   \
728  		    put_user(0, &d2->d_reclen)			||	   \
729  		    copy_to_user(d1->d_name, name, name_len)	||	   \
730  		    put_user(0, d1->d_name + name_len)		||	   \
731  		    put_user(name_len, &d1->d_reclen))			   \
732  			goto efault;					   \
733  	} else {							   \
734  		/* dirent has short and long name */			   \
735  		const char *longname = buf->longname;			   \
736  		int long_len = buf->long_len;				   \
737  		const char *shortname = buf->shortname;			   \
738  		int short_len = buf->short_len;				   \
739  									   \
740  		if (long_len >= sizeof(d1->d_name))			   \
741  			long_len = sizeof(d1->d_name) - 1;		   \
742  		if (short_len >= sizeof(d1->d_name))			   \
743  			short_len = sizeof(d1->d_name) - 1;		   \
744  									   \
745  		if (copy_to_user(d2->d_name, longname, long_len)	|| \
746  		    put_user(0, d2->d_name + long_len)			|| \
747  		    put_user(long_len, &d2->d_reclen)			|| \
748  		    put_user(ino, &d2->d_ino)				|| \
749  		    put_user(offset, &d2->d_off)			|| \
750  		    copy_to_user(d1->d_name, shortname, short_len)	|| \
751  		    put_user(0, d1->d_name + short_len)			|| \
752  		    put_user(short_len, &d1->d_reclen))			   \
753  			goto efault;					   \
754  	}								   \
755  	return 0;							   \
756  efault:									   \
757  	buf->result = -EFAULT;						   \
758  	return -EFAULT;							   \
759  }
760  
761  FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
762  
763  static int fat_ioctl_readdir(struct inode *inode, struct file *file,
764  			     void __user *dirent, filldir_t filldir,
765  			     int short_only, int both)
766  {
767  	struct fat_ioctl_filldir_callback buf = {
768  		.ctx.actor = filldir,
769  		.dirent = dirent
770  	};
771  	int ret;
772  
773  	buf.dirent = dirent;
774  	buf.result = 0;
775  	inode_lock_shared(inode);
776  	buf.ctx.pos = file->f_pos;
777  	ret = -ENOENT;
778  	if (!IS_DEADDIR(inode)) {
779  		ret = __fat_readdir(inode, file, &buf.ctx,
780  				    short_only, both ? &buf : NULL);
781  		file->f_pos = buf.ctx.pos;
782  	}
783  	inode_unlock_shared(inode);
784  	if (ret >= 0)
785  		ret = buf.result;
786  	return ret;
787  }
788  
789  static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
790  			  unsigned long arg)
791  {
792  	struct inode *inode = file_inode(filp);
793  	struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
794  	int short_only, both;
795  
796  	switch (cmd) {
797  	case VFAT_IOCTL_READDIR_SHORT:
798  		short_only = 1;
799  		both = 0;
800  		break;
801  	case VFAT_IOCTL_READDIR_BOTH:
802  		short_only = 0;
803  		both = 1;
804  		break;
805  	default:
806  		return fat_generic_ioctl(filp, cmd, arg);
807  	}
808  
809  	if (!access_ok(d1, sizeof(struct __fat_dirent[2])))
810  		return -EFAULT;
811  	/*
812  	 * Yes, we don't need this put_user() absolutely. However old
813  	 * code didn't return the right value. So, app use this value,
814  	 * in order to check whether it is EOF.
815  	 */
816  	if (put_user(0, &d1->d_reclen))
817  		return -EFAULT;
818  
819  	return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
820  				 short_only, both);
821  }
822  
823  #ifdef CONFIG_COMPAT
824  #define	VFAT_IOCTL_READDIR_BOTH32	_IOR('r', 1, struct compat_dirent[2])
825  #define	VFAT_IOCTL_READDIR_SHORT32	_IOR('r', 2, struct compat_dirent[2])
826  
827  FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
828  
829  static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
830  				 unsigned long arg)
831  {
832  	struct inode *inode = file_inode(filp);
833  	struct compat_dirent __user *d1 = compat_ptr(arg);
834  	int short_only, both;
835  
836  	switch (cmd) {
837  	case VFAT_IOCTL_READDIR_SHORT32:
838  		short_only = 1;
839  		both = 0;
840  		break;
841  	case VFAT_IOCTL_READDIR_BOTH32:
842  		short_only = 0;
843  		both = 1;
844  		break;
845  	default:
846  		return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
847  	}
848  
849  	if (!access_ok(d1, sizeof(struct compat_dirent[2])))
850  		return -EFAULT;
851  	/*
852  	 * Yes, we don't need this put_user() absolutely. However old
853  	 * code didn't return the right value. So, app use this value,
854  	 * in order to check whether it is EOF.
855  	 */
856  	if (put_user(0, &d1->d_reclen))
857  		return -EFAULT;
858  
859  	return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
860  				 short_only, both);
861  }
862  #endif /* CONFIG_COMPAT */
863  
864  const struct file_operations fat_dir_operations = {
865  	.llseek		= generic_file_llseek,
866  	.read		= generic_read_dir,
867  	.iterate_shared	= fat_readdir,
868  	.unlocked_ioctl	= fat_dir_ioctl,
869  #ifdef CONFIG_COMPAT
870  	.compat_ioctl	= fat_compat_dir_ioctl,
871  #endif
872  	.fsync		= fat_file_fsync,
873  };
874  
875  static int fat_get_short_entry(struct inode *dir, loff_t *pos,
876  			       struct buffer_head **bh,
877  			       struct msdos_dir_entry **de)
878  {
879  	while (fat_get_entry(dir, pos, bh, de) >= 0) {
880  		/* free entry or long name entry or volume label */
881  		if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
882  			return 0;
883  	}
884  	return -ENOENT;
885  }
886  
887  /*
888   * The ".." entry can not provide the "struct fat_slot_info" information
889   * for inode, nor a usable i_pos. So, this function provides some information
890   * only.
891   *
892   * Since this function walks through the on-disk inodes within a directory,
893   * callers are responsible for taking any locks necessary to prevent the
894   * directory from changing.
895   */
896  int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
897  			 struct msdos_dir_entry **de)
898  {
899  	loff_t offset = 0;
900  
901  	*de = NULL;
902  	while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
903  		if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
904  			return 0;
905  	}
906  	return -ENOENT;
907  }
908  EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
909  
910  /* See if directory is empty */
911  int fat_dir_empty(struct inode *dir)
912  {
913  	struct buffer_head *bh;
914  	struct msdos_dir_entry *de;
915  	loff_t cpos;
916  	int result = 0;
917  
918  	bh = NULL;
919  	cpos = 0;
920  	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
921  		if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
922  		    strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
923  			result = -ENOTEMPTY;
924  			break;
925  		}
926  	}
927  	brelse(bh);
928  	return result;
929  }
930  EXPORT_SYMBOL_GPL(fat_dir_empty);
931  
932  /*
933   * fat_subdirs counts the number of sub-directories of dir. It can be run
934   * on directories being created.
935   */
936  int fat_subdirs(struct inode *dir)
937  {
938  	struct buffer_head *bh;
939  	struct msdos_dir_entry *de;
940  	loff_t cpos;
941  	int count = 0;
942  
943  	bh = NULL;
944  	cpos = 0;
945  	while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
946  		if (de->attr & ATTR_DIR)
947  			count++;
948  	}
949  	brelse(bh);
950  	return count;
951  }
952  
953  /*
954   * Scans a directory for a given file (name points to its formatted name).
955   * Returns an error code or zero.
956   */
957  int fat_scan(struct inode *dir, const unsigned char *name,
958  	     struct fat_slot_info *sinfo)
959  {
960  	struct super_block *sb = dir->i_sb;
961  
962  	sinfo->slot_off = 0;
963  	sinfo->bh = NULL;
964  	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
965  				   &sinfo->de) >= 0) {
966  		if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
967  			sinfo->slot_off -= sizeof(*sinfo->de);
968  			sinfo->nr_slots = 1;
969  			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
970  			return 0;
971  		}
972  	}
973  	return -ENOENT;
974  }
975  EXPORT_SYMBOL_GPL(fat_scan);
976  
977  /*
978   * Scans a directory for a given logstart.
979   * Returns an error code or zero.
980   */
981  int fat_scan_logstart(struct inode *dir, int i_logstart,
982  		      struct fat_slot_info *sinfo)
983  {
984  	struct super_block *sb = dir->i_sb;
985  
986  	sinfo->slot_off = 0;
987  	sinfo->bh = NULL;
988  	while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
989  				   &sinfo->de) >= 0) {
990  		if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
991  			sinfo->slot_off -= sizeof(*sinfo->de);
992  			sinfo->nr_slots = 1;
993  			sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
994  			return 0;
995  		}
996  	}
997  	return -ENOENT;
998  }
999  
1000  static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
1001  {
1002  	struct super_block *sb = dir->i_sb;
1003  	struct buffer_head *bh;
1004  	struct msdos_dir_entry *de, *endp;
1005  	int err = 0, orig_slots;
1006  
1007  	while (nr_slots) {
1008  		bh = NULL;
1009  		if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1010  			err = -EIO;
1011  			break;
1012  		}
1013  
1014  		orig_slots = nr_slots;
1015  		endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1016  		while (nr_slots && de < endp) {
1017  			de->name[0] = DELETED_FLAG;
1018  			de++;
1019  			nr_slots--;
1020  		}
1021  		mark_buffer_dirty_inode(bh, dir);
1022  		if (IS_DIRSYNC(dir))
1023  			err = sync_dirty_buffer(bh);
1024  		brelse(bh);
1025  		if (err)
1026  			break;
1027  
1028  		/* pos is *next* de's position, so this does `- sizeof(de)' */
1029  		pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1030  	}
1031  
1032  	return err;
1033  }
1034  
1035  int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1036  {
1037  	struct super_block *sb = dir->i_sb;
1038  	struct msdos_dir_entry *de;
1039  	struct buffer_head *bh;
1040  	int err = 0, nr_slots;
1041  
1042  	/*
1043  	 * First stage: Remove the shortname. By this, the directory
1044  	 * entry is removed.
1045  	 */
1046  	nr_slots = sinfo->nr_slots;
1047  	de = sinfo->de;
1048  	sinfo->de = NULL;
1049  	bh = sinfo->bh;
1050  	sinfo->bh = NULL;
1051  	while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1052  		de->name[0] = DELETED_FLAG;
1053  		de--;
1054  		nr_slots--;
1055  	}
1056  	mark_buffer_dirty_inode(bh, dir);
1057  	if (IS_DIRSYNC(dir))
1058  		err = sync_dirty_buffer(bh);
1059  	brelse(bh);
1060  	if (err)
1061  		return err;
1062  	inode_inc_iversion(dir);
1063  
1064  	if (nr_slots) {
1065  		/*
1066  		 * Second stage: remove the remaining longname slots.
1067  		 * (This directory entry is already removed, and so return
1068  		 * the success)
1069  		 */
1070  		err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1071  		if (err) {
1072  			fat_msg(sb, KERN_WARNING,
1073  			       "Couldn't remove the long name slots");
1074  		}
1075  	}
1076  
1077  	fat_truncate_time(dir, NULL, S_ATIME|S_MTIME);
1078  	if (IS_DIRSYNC(dir))
1079  		(void)fat_sync_inode(dir);
1080  	else
1081  		mark_inode_dirty(dir);
1082  
1083  	return 0;
1084  }
1085  EXPORT_SYMBOL_GPL(fat_remove_entries);
1086  
1087  static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1088  			      struct buffer_head **bhs, int nr_bhs)
1089  {
1090  	struct super_block *sb = dir->i_sb;
1091  	sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1092  	int err, i, n;
1093  
1094  	/* Zeroing the unused blocks on this cluster */
1095  	blknr += nr_used;
1096  	n = nr_used;
1097  	while (blknr < last_blknr) {
1098  		bhs[n] = sb_getblk(sb, blknr);
1099  		if (!bhs[n]) {
1100  			err = -ENOMEM;
1101  			goto error;
1102  		}
1103  		memset(bhs[n]->b_data, 0, sb->s_blocksize);
1104  		set_buffer_uptodate(bhs[n]);
1105  		mark_buffer_dirty_inode(bhs[n], dir);
1106  
1107  		n++;
1108  		blknr++;
1109  		if (n == nr_bhs) {
1110  			if (IS_DIRSYNC(dir)) {
1111  				err = fat_sync_bhs(bhs, n);
1112  				if (err)
1113  					goto error;
1114  			}
1115  			for (i = 0; i < n; i++)
1116  				brelse(bhs[i]);
1117  			n = 0;
1118  		}
1119  	}
1120  	if (IS_DIRSYNC(dir)) {
1121  		err = fat_sync_bhs(bhs, n);
1122  		if (err)
1123  			goto error;
1124  	}
1125  	for (i = 0; i < n; i++)
1126  		brelse(bhs[i]);
1127  
1128  	return 0;
1129  
1130  error:
1131  	for (i = 0; i < n; i++)
1132  		bforget(bhs[i]);
1133  	return err;
1134  }
1135  
1136  int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts)
1137  {
1138  	struct super_block *sb = dir->i_sb;
1139  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1140  	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1141  	struct msdos_dir_entry *de;
1142  	sector_t blknr;
1143  	__le16 date, time;
1144  	u8 time_cs;
1145  	int err, cluster;
1146  
1147  	err = fat_alloc_clusters(dir, &cluster, 1);
1148  	if (err)
1149  		goto error;
1150  
1151  	blknr = fat_clus_to_blknr(sbi, cluster);
1152  	bhs[0] = sb_getblk(sb, blknr);
1153  	if (!bhs[0]) {
1154  		err = -ENOMEM;
1155  		goto error_free;
1156  	}
1157  
1158  	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1159  
1160  	de = (struct msdos_dir_entry *)bhs[0]->b_data;
1161  	/* filling the new directory slots ("." and ".." entries) */
1162  	memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1163  	memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1164  	de->attr = de[1].attr = ATTR_DIR;
1165  	de[0].lcase = de[1].lcase = 0;
1166  	de[0].time = de[1].time = time;
1167  	de[0].date = de[1].date = date;
1168  	if (sbi->options.isvfat) {
1169  		/* extra timestamps */
1170  		de[0].ctime = de[1].ctime = time;
1171  		de[0].ctime_cs = de[1].ctime_cs = time_cs;
1172  		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1173  	} else {
1174  		de[0].ctime = de[1].ctime = 0;
1175  		de[0].ctime_cs = de[1].ctime_cs = 0;
1176  		de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1177  	}
1178  	fat_set_start(&de[0], cluster);
1179  	fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1180  	de[0].size = de[1].size = 0;
1181  	memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1182  	set_buffer_uptodate(bhs[0]);
1183  	mark_buffer_dirty_inode(bhs[0], dir);
1184  
1185  	err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1186  	if (err)
1187  		goto error_free;
1188  
1189  	return cluster;
1190  
1191  error_free:
1192  	fat_free_clusters(dir, cluster);
1193  error:
1194  	return err;
1195  }
1196  EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1197  
1198  static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1199  			       int *nr_cluster, struct msdos_dir_entry **de,
1200  			       struct buffer_head **bh, loff_t *i_pos)
1201  {
1202  	struct super_block *sb = dir->i_sb;
1203  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1204  	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1205  	sector_t blknr, start_blknr, last_blknr;
1206  	unsigned long size, copy;
1207  	int err, i, n, offset, cluster[2];
1208  
1209  	/*
1210  	 * The minimum cluster size is 512bytes, and maximum entry
1211  	 * size is 32*slots (672bytes).  So, iff the cluster size is
1212  	 * 512bytes, we may need two clusters.
1213  	 */
1214  	size = nr_slots * sizeof(struct msdos_dir_entry);
1215  	*nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1216  	BUG_ON(*nr_cluster > 2);
1217  
1218  	err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1219  	if (err)
1220  		goto error;
1221  
1222  	/*
1223  	 * First stage: Fill the directory entry.  NOTE: This cluster
1224  	 * is not referenced from any inode yet, so updates order is
1225  	 * not important.
1226  	 */
1227  	i = n = copy = 0;
1228  	do {
1229  		start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1230  		last_blknr = start_blknr + sbi->sec_per_clus;
1231  		while (blknr < last_blknr) {
1232  			bhs[n] = sb_getblk(sb, blknr);
1233  			if (!bhs[n]) {
1234  				err = -ENOMEM;
1235  				goto error_nomem;
1236  			}
1237  
1238  			/* fill the directory entry */
1239  			copy = min(size, sb->s_blocksize);
1240  			memcpy(bhs[n]->b_data, slots, copy);
1241  			slots += copy;
1242  			size -= copy;
1243  			set_buffer_uptodate(bhs[n]);
1244  			mark_buffer_dirty_inode(bhs[n], dir);
1245  			if (!size)
1246  				break;
1247  			n++;
1248  			blknr++;
1249  		}
1250  	} while (++i < *nr_cluster);
1251  
1252  	memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1253  	offset = copy - sizeof(struct msdos_dir_entry);
1254  	get_bh(bhs[n]);
1255  	*bh = bhs[n];
1256  	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1257  	*i_pos = fat_make_i_pos(sb, *bh, *de);
1258  
1259  	/* Second stage: clear the rest of cluster, and write outs */
1260  	err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1261  	if (err)
1262  		goto error_free;
1263  
1264  	return cluster[0];
1265  
1266  error_free:
1267  	brelse(*bh);
1268  	*bh = NULL;
1269  	n = 0;
1270  error_nomem:
1271  	for (i = 0; i < n; i++)
1272  		bforget(bhs[i]);
1273  	fat_free_clusters(dir, cluster[0]);
1274  error:
1275  	return err;
1276  }
1277  
1278  int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1279  		    struct fat_slot_info *sinfo)
1280  {
1281  	struct super_block *sb = dir->i_sb;
1282  	struct msdos_sb_info *sbi = MSDOS_SB(sb);
1283  	struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1284  	struct msdos_dir_entry *uninitialized_var(de);
1285  	int err, free_slots, i, nr_bhs;
1286  	loff_t pos, i_pos;
1287  
1288  	sinfo->nr_slots = nr_slots;
1289  
1290  	/* First stage: search free directory entries */
1291  	free_slots = nr_bhs = 0;
1292  	bh = prev = NULL;
1293  	pos = 0;
1294  	err = -ENOSPC;
1295  	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1296  		/* check the maximum size of directory */
1297  		if (pos >= FAT_MAX_DIR_SIZE)
1298  			goto error;
1299  
1300  		if (IS_FREE(de->name)) {
1301  			if (prev != bh) {
1302  				get_bh(bh);
1303  				bhs[nr_bhs] = prev = bh;
1304  				nr_bhs++;
1305  			}
1306  			free_slots++;
1307  			if (free_slots == nr_slots)
1308  				goto found;
1309  		} else {
1310  			for (i = 0; i < nr_bhs; i++)
1311  				brelse(bhs[i]);
1312  			prev = NULL;
1313  			free_slots = nr_bhs = 0;
1314  		}
1315  	}
1316  	if (dir->i_ino == MSDOS_ROOT_INO) {
1317  		if (!is_fat32(sbi))
1318  			goto error;
1319  	} else if (MSDOS_I(dir)->i_start == 0) {
1320  		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1321  		       MSDOS_I(dir)->i_pos);
1322  		err = -EIO;
1323  		goto error;
1324  	}
1325  
1326  found:
1327  	err = 0;
1328  	pos -= free_slots * sizeof(*de);
1329  	nr_slots -= free_slots;
1330  	if (free_slots) {
1331  		/*
1332  		 * Second stage: filling the free entries with new entries.
1333  		 * NOTE: If this slots has shortname, first, we write
1334  		 * the long name slots, then write the short name.
1335  		 */
1336  		int size = free_slots * sizeof(*de);
1337  		int offset = pos & (sb->s_blocksize - 1);
1338  		int long_bhs = nr_bhs - (nr_slots == 0);
1339  
1340  		/* Fill the long name slots. */
1341  		for (i = 0; i < long_bhs; i++) {
1342  			int copy = min_t(int, sb->s_blocksize - offset, size);
1343  			memcpy(bhs[i]->b_data + offset, slots, copy);
1344  			mark_buffer_dirty_inode(bhs[i], dir);
1345  			offset = 0;
1346  			slots += copy;
1347  			size -= copy;
1348  		}
1349  		if (long_bhs && IS_DIRSYNC(dir))
1350  			err = fat_sync_bhs(bhs, long_bhs);
1351  		if (!err && i < nr_bhs) {
1352  			/* Fill the short name slot. */
1353  			int copy = min_t(int, sb->s_blocksize - offset, size);
1354  			memcpy(bhs[i]->b_data + offset, slots, copy);
1355  			mark_buffer_dirty_inode(bhs[i], dir);
1356  			if (IS_DIRSYNC(dir))
1357  				err = sync_dirty_buffer(bhs[i]);
1358  		}
1359  		for (i = 0; i < nr_bhs; i++)
1360  			brelse(bhs[i]);
1361  		if (err)
1362  			goto error_remove;
1363  	}
1364  
1365  	if (nr_slots) {
1366  		int cluster, nr_cluster;
1367  
1368  		/*
1369  		 * Third stage: allocate the cluster for new entries.
1370  		 * And initialize the cluster with new entries, then
1371  		 * add the cluster to dir.
1372  		 */
1373  		cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1374  					      &de, &bh, &i_pos);
1375  		if (cluster < 0) {
1376  			err = cluster;
1377  			goto error_remove;
1378  		}
1379  		err = fat_chain_add(dir, cluster, nr_cluster);
1380  		if (err) {
1381  			fat_free_clusters(dir, cluster);
1382  			goto error_remove;
1383  		}
1384  		if (dir->i_size & (sbi->cluster_size - 1)) {
1385  			fat_fs_error(sb, "Odd directory size");
1386  			dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1387  				& ~((loff_t)sbi->cluster_size - 1);
1388  		}
1389  		dir->i_size += nr_cluster << sbi->cluster_bits;
1390  		MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1391  	}
1392  	sinfo->slot_off = pos;
1393  	sinfo->de = de;
1394  	sinfo->bh = bh;
1395  	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1396  
1397  	return 0;
1398  
1399  error:
1400  	brelse(bh);
1401  	for (i = 0; i < nr_bhs; i++)
1402  		brelse(bhs[i]);
1403  	return err;
1404  
1405  error_remove:
1406  	brelse(bh);
1407  	if (free_slots)
1408  		__fat_remove_entries(dir, pos, free_slots);
1409  	return err;
1410  }
1411  EXPORT_SYMBOL_GPL(fat_add_entries);
1412