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TOMOYO Linux Cross Reference
Linux/fs/fat/dir.c

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  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         brelse(*bh);
 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         /* For an explanation of the special treatment of 0x05 in
372          * filenames, see msdos_format_name in namei_msdos.c
373          */
374         if (work[0] == 0x05)
375                 work[0] = 0xE5;
376 
377         /* Filename */
378         for (i = 0, j = 0; i < 8;) {
379                 c = work[i];
380                 if (!c)
381                         break;
382                 chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
383                                         &uni_name[j++], opt_shortname,
384                                         de->lcase & CASE_LOWER_BASE);
385                 if (chl <= 1) {
386                         if (!isvfat)
387                                 ptname[i] = nocase ? c : fat_tolower(c);
388                         i++;
389                         if (c != ' ') {
390                                 name_len = i;
391                                 uni_len  = j;
392                         }
393                 } else {
394                         uni_len = j;
395                         if (isvfat)
396                                 i += min(chl, 8-i);
397                         else {
398                                 for (chi = 0; chi < chl && i < 8; chi++, i++)
399                                         ptname[i] = work[i];
400                         }
401                         if (chl)
402                                 name_len = i;
403                 }
404         }
405 
406         i = name_len;
407         j = uni_len;
408         fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
409         if (!isvfat)
410                 ptname[i] = '.';
411         i++;
412 
413         /* Extension */
414         for (k = 8; k < MSDOS_NAME;) {
415                 c = work[k];
416                 if (!c)
417                         break;
418                 chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
419                                         &uni_name[j++], opt_shortname,
420                                         de->lcase & CASE_LOWER_EXT);
421                 if (chl <= 1) {
422                         k++;
423                         if (!isvfat)
424                                 ptname[i] = nocase ? c : fat_tolower(c);
425                         i++;
426                         if (c != ' ') {
427                                 name_len = i;
428                                 uni_len  = j;
429                         }
430                 } else {
431                         uni_len = j;
432                         if (isvfat) {
433                                 int offset = min(chl, MSDOS_NAME-k);
434                                 k += offset;
435                                 i += offset;
436                         } else {
437                                 for (chi = 0; chi < chl && k < MSDOS_NAME;
438                                      chi++, i++, k++) {
439                                                 ptname[i] = work[k];
440                                 }
441                         }
442                         if (chl)
443                                 name_len = i;
444                 }
445         }
446 
447         if (name_len > 0) {
448                 name_len += dotoffset;
449 
450                 if (sbi->options.isvfat) {
451                         uni_name[uni_len] = 0x0000;
452                         name_len = fat_uni_to_x8(sb, uni_name, name,
453                                                  FAT_MAX_SHORT_SIZE);
454                 }
455         }
456 
457         return name_len;
458 }
459 
460 /*
461  * Return values: negative -> error/not found, 0 -> found.
462  */
463 int fat_search_long(struct inode *inode, const unsigned char *name,
464                     int name_len, struct fat_slot_info *sinfo)
465 {
466         struct super_block *sb = inode->i_sb;
467         struct msdos_sb_info *sbi = MSDOS_SB(sb);
468         struct buffer_head *bh = NULL;
469         struct msdos_dir_entry *de;
470         unsigned char nr_slots;
471         wchar_t *unicode = NULL;
472         unsigned char bufname[FAT_MAX_SHORT_SIZE];
473         loff_t cpos = 0;
474         int err, len;
475 
476         err = -ENOENT;
477         while (1) {
478                 if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
479                         goto end_of_dir;
480 parse_record:
481                 nr_slots = 0;
482                 if (de->name[0] == DELETED_FLAG)
483                         continue;
484                 if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
485                         continue;
486                 if (de->attr != ATTR_EXT && IS_FREE(de->name))
487                         continue;
488                 if (de->attr == ATTR_EXT) {
489                         int status = fat_parse_long(inode, &cpos, &bh, &de,
490                                                     &unicode, &nr_slots);
491                         if (status < 0) {
492                                 err = status;
493                                 goto end_of_dir;
494                         } else if (status == PARSE_INVALID)
495                                 continue;
496                         else if (status == PARSE_NOT_LONGNAME)
497                                 goto parse_record;
498                         else if (status == PARSE_EOF)
499                                 goto end_of_dir;
500                 }
501 
502                 /* Never prepend '.' to hidden files here.
503                  * That is done only for msdos mounts (and only when
504                  * 'dotsOK=yes'); if we are executing here, it is in the
505                  * context of a vfat mount.
506                  */
507                 len = fat_parse_short(sb, de, bufname, 0);
508                 if (len == 0)
509                         continue;
510 
511                 /* Compare shortname */
512                 if (fat_name_match(sbi, name, name_len, bufname, len))
513                         goto found;
514 
515                 if (nr_slots) {
516                         void *longname = unicode + FAT_MAX_UNI_CHARS;
517                         int size = PATH_MAX - FAT_MAX_UNI_SIZE;
518 
519                         /* Compare longname */
520                         len = fat_uni_to_x8(sb, unicode, longname, size);
521                         if (fat_name_match(sbi, name, name_len, longname, len))
522                                 goto found;
523                 }
524         }
525 
526 found:
527         nr_slots++;     /* include the de */
528         sinfo->slot_off = cpos - nr_slots * sizeof(*de);
529         sinfo->nr_slots = nr_slots;
530         sinfo->de = de;
531         sinfo->bh = bh;
532         sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
533         err = 0;
534 end_of_dir:
535         if (unicode)
536                 __putname(unicode);
537 
538         return err;
539 }
540 EXPORT_SYMBOL_GPL(fat_search_long);
541 
542 struct fat_ioctl_filldir_callback {
543         struct dir_context ctx;
544         void __user *dirent;
545         int result;
546         /* for dir ioctl */
547         const char *longname;
548         int long_len;
549         const char *shortname;
550         int short_len;
551 };
552 
553 static int __fat_readdir(struct inode *inode, struct file *file,
554                          struct dir_context *ctx, int short_only,
555                          struct fat_ioctl_filldir_callback *both)
556 {
557         struct super_block *sb = inode->i_sb;
558         struct msdos_sb_info *sbi = MSDOS_SB(sb);
559         struct buffer_head *bh;
560         struct msdos_dir_entry *de;
561         unsigned char nr_slots;
562         wchar_t *unicode = NULL;
563         unsigned char bufname[FAT_MAX_SHORT_SIZE];
564         int isvfat = sbi->options.isvfat;
565         const char *fill_name = NULL;
566         int fake_offset = 0;
567         loff_t cpos;
568         int short_len = 0, fill_len = 0;
569         int ret = 0;
570 
571         mutex_lock(&sbi->s_lock);
572 
573         cpos = ctx->pos;
574         /* Fake . and .. for the root directory. */
575         if (inode->i_ino == MSDOS_ROOT_INO) {
576                 if (!dir_emit_dots(file, ctx))
577                         goto out;
578                 if (ctx->pos == 2) {
579                         fake_offset = 1;
580                         cpos = 0;
581                 }
582         }
583         if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
584                 ret = -ENOENT;
585                 goto out;
586         }
587 
588         bh = NULL;
589 get_new:
590         if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
591                 goto end_of_dir;
592 parse_record:
593         nr_slots = 0;
594         /*
595          * Check for long filename entry, but if short_only, we don't
596          * need to parse long filename.
597          */
598         if (isvfat && !short_only) {
599                 if (de->name[0] == DELETED_FLAG)
600                         goto record_end;
601                 if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
602                         goto record_end;
603                 if (de->attr != ATTR_EXT && IS_FREE(de->name))
604                         goto record_end;
605         } else {
606                 if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
607                         goto record_end;
608         }
609 
610         if (isvfat && de->attr == ATTR_EXT) {
611                 int status = fat_parse_long(inode, &cpos, &bh, &de,
612                                             &unicode, &nr_slots);
613                 if (status < 0) {
614                         bh = NULL;
615                         ret = status;
616                         goto end_of_dir;
617                 } else if (status == PARSE_INVALID)
618                         goto record_end;
619                 else if (status == PARSE_NOT_LONGNAME)
620                         goto parse_record;
621                 else if (status == PARSE_EOF)
622                         goto end_of_dir;
623 
624                 if (nr_slots) {
625                         void *longname = unicode + FAT_MAX_UNI_CHARS;
626                         int size = PATH_MAX - FAT_MAX_UNI_SIZE;
627                         int len = fat_uni_to_x8(sb, unicode, longname, size);
628 
629                         fill_name = longname;
630                         fill_len = len;
631                         /* !both && !short_only, so we don't need shortname. */
632                         if (!both)
633                                 goto start_filldir;
634 
635                         short_len = fat_parse_short(sb, de, bufname,
636                                                     sbi->options.dotsOK);
637                         if (short_len == 0)
638                                 goto record_end;
639                         /* hack for fat_ioctl_filldir() */
640                         both->longname = fill_name;
641                         both->long_len = fill_len;
642                         both->shortname = bufname;
643                         both->short_len = short_len;
644                         fill_name = NULL;
645                         fill_len = 0;
646                         goto start_filldir;
647                 }
648         }
649 
650         short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
651         if (short_len == 0)
652                 goto record_end;
653 
654         fill_name = bufname;
655         fill_len = short_len;
656 
657 start_filldir:
658         ctx->pos = cpos - (nr_slots + 1) * sizeof(struct msdos_dir_entry);
659         if (fake_offset && ctx->pos < 2)
660                 ctx->pos = 2;
661 
662         if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
663                 if (!dir_emit_dot(file, ctx))
664                         goto fill_failed;
665         } else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
666                 if (!dir_emit_dotdot(file, ctx))
667                         goto fill_failed;
668         } else {
669                 unsigned long inum;
670                 loff_t i_pos = fat_make_i_pos(sb, bh, de);
671                 struct inode *tmp = fat_iget(sb, i_pos);
672                 if (tmp) {
673                         inum = tmp->i_ino;
674                         iput(tmp);
675                 } else
676                         inum = iunique(sb, MSDOS_ROOT_INO);
677                 if (!dir_emit(ctx, fill_name, fill_len, inum,
678                             (de->attr & ATTR_DIR) ? DT_DIR : DT_REG))
679                         goto fill_failed;
680         }
681 
682 record_end:
683         fake_offset = 0;
684         ctx->pos = cpos;
685         goto get_new;
686 
687 end_of_dir:
688         if (fake_offset && cpos < 2)
689                 ctx->pos = 2;
690         else
691                 ctx->pos = cpos;
692 fill_failed:
693         brelse(bh);
694         if (unicode)
695                 __putname(unicode);
696 out:
697         mutex_unlock(&sbi->s_lock);
698 
699         return ret;
700 }
701 
702 static int fat_readdir(struct file *file, struct dir_context *ctx)
703 {
704         return __fat_readdir(file_inode(file), file, ctx, 0, NULL);
705 }
706 
707 #define FAT_IOCTL_FILLDIR_FUNC(func, dirent_type)                          \
708 static int func(struct dir_context *ctx, const char *name, int name_len,   \
709                              loff_t offset, u64 ino, unsigned int d_type)  \
710 {                                                                          \
711         struct fat_ioctl_filldir_callback *buf =                           \
712                 container_of(ctx, struct fat_ioctl_filldir_callback, ctx); \
713         struct dirent_type __user *d1 = buf->dirent;                       \
714         struct dirent_type __user *d2 = d1 + 1;                            \
715                                                                            \
716         if (buf->result)                                                   \
717                 return -EINVAL;                                            \
718         buf->result++;                                                     \
719                                                                            \
720         if (name != NULL) {                                                \
721                 /* dirent has only short name */                           \
722                 if (name_len >= sizeof(d1->d_name))                        \
723                         name_len = sizeof(d1->d_name) - 1;                 \
724                                                                            \
725                 if (put_user(0, d2->d_name)                     ||         \
726                     put_user(0, &d2->d_reclen)                  ||         \
727                     copy_to_user(d1->d_name, name, name_len)    ||         \
728                     put_user(0, d1->d_name + name_len)          ||         \
729                     put_user(name_len, &d1->d_reclen))                     \
730                         goto efault;                                       \
731         } else {                                                           \
732                 /* dirent has short and long name */                       \
733                 const char *longname = buf->longname;                      \
734                 int long_len = buf->long_len;                              \
735                 const char *shortname = buf->shortname;                    \
736                 int short_len = buf->short_len;                            \
737                                                                            \
738                 if (long_len >= sizeof(d1->d_name))                        \
739                         long_len = sizeof(d1->d_name) - 1;                 \
740                 if (short_len >= sizeof(d1->d_name))                       \
741                         short_len = sizeof(d1->d_name) - 1;                \
742                                                                            \
743                 if (copy_to_user(d2->d_name, longname, long_len)        || \
744                     put_user(0, d2->d_name + long_len)                  || \
745                     put_user(long_len, &d2->d_reclen)                   || \
746                     put_user(ino, &d2->d_ino)                           || \
747                     put_user(offset, &d2->d_off)                        || \
748                     copy_to_user(d1->d_name, shortname, short_len)      || \
749                     put_user(0, d1->d_name + short_len)                 || \
750                     put_user(short_len, &d1->d_reclen))                    \
751                         goto efault;                                       \
752         }                                                                  \
753         return 0;                                                          \
754 efault:                                                                    \
755         buf->result = -EFAULT;                                             \
756         return -EFAULT;                                                    \
757 }
758 
759 FAT_IOCTL_FILLDIR_FUNC(fat_ioctl_filldir, __fat_dirent)
760 
761 static int fat_ioctl_readdir(struct inode *inode, struct file *file,
762                              void __user *dirent, filldir_t filldir,
763                              int short_only, int both)
764 {
765         struct fat_ioctl_filldir_callback buf = {
766                 .ctx.actor = filldir,
767                 .dirent = dirent
768         };
769         int ret;
770 
771         buf.dirent = dirent;
772         buf.result = 0;
773         inode_lock_shared(inode);
774         buf.ctx.pos = file->f_pos;
775         ret = -ENOENT;
776         if (!IS_DEADDIR(inode)) {
777                 ret = __fat_readdir(inode, file, &buf.ctx,
778                                     short_only, both ? &buf : NULL);
779                 file->f_pos = buf.ctx.pos;
780         }
781         inode_unlock_shared(inode);
782         if (ret >= 0)
783                 ret = buf.result;
784         return ret;
785 }
786 
787 static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
788                           unsigned long arg)
789 {
790         struct inode *inode = file_inode(filp);
791         struct __fat_dirent __user *d1 = (struct __fat_dirent __user *)arg;
792         int short_only, both;
793 
794         switch (cmd) {
795         case VFAT_IOCTL_READDIR_SHORT:
796                 short_only = 1;
797                 both = 0;
798                 break;
799         case VFAT_IOCTL_READDIR_BOTH:
800                 short_only = 0;
801                 both = 1;
802                 break;
803         default:
804                 return fat_generic_ioctl(filp, cmd, arg);
805         }
806 
807         if (!access_ok(d1, sizeof(struct __fat_dirent[2])))
808                 return -EFAULT;
809         /*
810          * Yes, we don't need this put_user() absolutely. However old
811          * code didn't return the right value. So, app use this value,
812          * in order to check whether it is EOF.
813          */
814         if (put_user(0, &d1->d_reclen))
815                 return -EFAULT;
816 
817         return fat_ioctl_readdir(inode, filp, d1, fat_ioctl_filldir,
818                                  short_only, both);
819 }
820 
821 #ifdef CONFIG_COMPAT
822 #define VFAT_IOCTL_READDIR_BOTH32       _IOR('r', 1, struct compat_dirent[2])
823 #define VFAT_IOCTL_READDIR_SHORT32      _IOR('r', 2, struct compat_dirent[2])
824 
825 FAT_IOCTL_FILLDIR_FUNC(fat_compat_ioctl_filldir, compat_dirent)
826 
827 static long fat_compat_dir_ioctl(struct file *filp, unsigned cmd,
828                                  unsigned long arg)
829 {
830         struct inode *inode = file_inode(filp);
831         struct compat_dirent __user *d1 = compat_ptr(arg);
832         int short_only, both;
833 
834         switch (cmd) {
835         case VFAT_IOCTL_READDIR_SHORT32:
836                 short_only = 1;
837                 both = 0;
838                 break;
839         case VFAT_IOCTL_READDIR_BOTH32:
840                 short_only = 0;
841                 both = 1;
842                 break;
843         default:
844                 return fat_generic_ioctl(filp, cmd, (unsigned long)arg);
845         }
846 
847         if (!access_ok(d1, sizeof(struct compat_dirent[2])))
848                 return -EFAULT;
849         /*
850          * Yes, we don't need this put_user() absolutely. However old
851          * code didn't return the right value. So, app use this value,
852          * in order to check whether it is EOF.
853          */
854         if (put_user(0, &d1->d_reclen))
855                 return -EFAULT;
856 
857         return fat_ioctl_readdir(inode, filp, d1, fat_compat_ioctl_filldir,
858                                  short_only, both);
859 }
860 #endif /* CONFIG_COMPAT */
861 
862 const struct file_operations fat_dir_operations = {
863         .llseek         = generic_file_llseek,
864         .read           = generic_read_dir,
865         .iterate_shared = fat_readdir,
866         .unlocked_ioctl = fat_dir_ioctl,
867 #ifdef CONFIG_COMPAT
868         .compat_ioctl   = fat_compat_dir_ioctl,
869 #endif
870         .fsync          = fat_file_fsync,
871 };
872 
873 static int fat_get_short_entry(struct inode *dir, loff_t *pos,
874                                struct buffer_head **bh,
875                                struct msdos_dir_entry **de)
876 {
877         while (fat_get_entry(dir, pos, bh, de) >= 0) {
878                 /* free entry or long name entry or volume label */
879                 if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME))
880                         return 0;
881         }
882         return -ENOENT;
883 }
884 
885 /*
886  * The ".." entry can not provide the "struct fat_slot_info" information
887  * for inode, nor a usable i_pos. So, this function provides some information
888  * only.
889  *
890  * Since this function walks through the on-disk inodes within a directory,
891  * callers are responsible for taking any locks necessary to prevent the
892  * directory from changing.
893  */
894 int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
895                          struct msdos_dir_entry **de)
896 {
897         loff_t offset = 0;
898 
899         *de = NULL;
900         while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
901                 if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
902                         return 0;
903         }
904         return -ENOENT;
905 }
906 EXPORT_SYMBOL_GPL(fat_get_dotdot_entry);
907 
908 /* See if directory is empty */
909 int fat_dir_empty(struct inode *dir)
910 {
911         struct buffer_head *bh;
912         struct msdos_dir_entry *de;
913         loff_t cpos;
914         int result = 0;
915 
916         bh = NULL;
917         cpos = 0;
918         while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
919                 if (strncmp(de->name, MSDOS_DOT   , MSDOS_NAME) &&
920                     strncmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
921                         result = -ENOTEMPTY;
922                         break;
923                 }
924         }
925         brelse(bh);
926         return result;
927 }
928 EXPORT_SYMBOL_GPL(fat_dir_empty);
929 
930 /*
931  * fat_subdirs counts the number of sub-directories of dir. It can be run
932  * on directories being created.
933  */
934 int fat_subdirs(struct inode *dir)
935 {
936         struct buffer_head *bh;
937         struct msdos_dir_entry *de;
938         loff_t cpos;
939         int count = 0;
940 
941         bh = NULL;
942         cpos = 0;
943         while (fat_get_short_entry(dir, &cpos, &bh, &de) >= 0) {
944                 if (de->attr & ATTR_DIR)
945                         count++;
946         }
947         brelse(bh);
948         return count;
949 }
950 
951 /*
952  * Scans a directory for a given file (name points to its formatted name).
953  * Returns an error code or zero.
954  */
955 int fat_scan(struct inode *dir, const unsigned char *name,
956              struct fat_slot_info *sinfo)
957 {
958         struct super_block *sb = dir->i_sb;
959 
960         sinfo->slot_off = 0;
961         sinfo->bh = NULL;
962         while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
963                                    &sinfo->de) >= 0) {
964                 if (!strncmp(sinfo->de->name, name, MSDOS_NAME)) {
965                         sinfo->slot_off -= sizeof(*sinfo->de);
966                         sinfo->nr_slots = 1;
967                         sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
968                         return 0;
969                 }
970         }
971         return -ENOENT;
972 }
973 EXPORT_SYMBOL_GPL(fat_scan);
974 
975 /*
976  * Scans a directory for a given logstart.
977  * Returns an error code or zero.
978  */
979 int fat_scan_logstart(struct inode *dir, int i_logstart,
980                       struct fat_slot_info *sinfo)
981 {
982         struct super_block *sb = dir->i_sb;
983 
984         sinfo->slot_off = 0;
985         sinfo->bh = NULL;
986         while (fat_get_short_entry(dir, &sinfo->slot_off, &sinfo->bh,
987                                    &sinfo->de) >= 0) {
988                 if (fat_get_start(MSDOS_SB(sb), sinfo->de) == i_logstart) {
989                         sinfo->slot_off -= sizeof(*sinfo->de);
990                         sinfo->nr_slots = 1;
991                         sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
992                         return 0;
993                 }
994         }
995         return -ENOENT;
996 }
997 
998 static int __fat_remove_entries(struct inode *dir, loff_t pos, int nr_slots)
999 {
1000         struct super_block *sb = dir->i_sb;
1001         struct buffer_head *bh;
1002         struct msdos_dir_entry *de, *endp;
1003         int err = 0, orig_slots;
1004 
1005         while (nr_slots) {
1006                 bh = NULL;
1007                 if (fat_get_entry(dir, &pos, &bh, &de) < 0) {
1008                         err = -EIO;
1009                         break;
1010                 }
1011 
1012                 orig_slots = nr_slots;
1013                 endp = (struct msdos_dir_entry *)(bh->b_data + sb->s_blocksize);
1014                 while (nr_slots && de < endp) {
1015                         de->name[0] = DELETED_FLAG;
1016                         de++;
1017                         nr_slots--;
1018                 }
1019                 mark_buffer_dirty_inode(bh, dir);
1020                 if (IS_DIRSYNC(dir))
1021                         err = sync_dirty_buffer(bh);
1022                 brelse(bh);
1023                 if (err)
1024                         break;
1025 
1026                 /* pos is *next* de's position, so this does `- sizeof(de)' */
1027                 pos += ((orig_slots - nr_slots) * sizeof(*de)) - sizeof(*de);
1028         }
1029 
1030         return err;
1031 }
1032 
1033 int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
1034 {
1035         struct super_block *sb = dir->i_sb;
1036         struct msdos_dir_entry *de;
1037         struct buffer_head *bh;
1038         int err = 0, nr_slots;
1039 
1040         /*
1041          * First stage: Remove the shortname. By this, the directory
1042          * entry is removed.
1043          */
1044         nr_slots = sinfo->nr_slots;
1045         de = sinfo->de;
1046         sinfo->de = NULL;
1047         bh = sinfo->bh;
1048         sinfo->bh = NULL;
1049         while (nr_slots && de >= (struct msdos_dir_entry *)bh->b_data) {
1050                 de->name[0] = DELETED_FLAG;
1051                 de--;
1052                 nr_slots--;
1053         }
1054         mark_buffer_dirty_inode(bh, dir);
1055         if (IS_DIRSYNC(dir))
1056                 err = sync_dirty_buffer(bh);
1057         brelse(bh);
1058         if (err)
1059                 return err;
1060         inode_inc_iversion(dir);
1061 
1062         if (nr_slots) {
1063                 /*
1064                  * Second stage: remove the remaining longname slots.
1065                  * (This directory entry is already removed, and so return
1066                  * the success)
1067                  */
1068                 err = __fat_remove_entries(dir, sinfo->slot_off, nr_slots);
1069                 if (err) {
1070                         fat_msg(sb, KERN_WARNING,
1071                                "Couldn't remove the long name slots");
1072                 }
1073         }
1074 
1075         fat_truncate_time(dir, NULL, S_ATIME|S_MTIME);
1076         if (IS_DIRSYNC(dir))
1077                 (void)fat_sync_inode(dir);
1078         else
1079                 mark_inode_dirty(dir);
1080 
1081         return 0;
1082 }
1083 EXPORT_SYMBOL_GPL(fat_remove_entries);
1084 
1085 static int fat_zeroed_cluster(struct inode *dir, sector_t blknr, int nr_used,
1086                               struct buffer_head **bhs, int nr_bhs)
1087 {
1088         struct super_block *sb = dir->i_sb;
1089         sector_t last_blknr = blknr + MSDOS_SB(sb)->sec_per_clus;
1090         int err, i, n;
1091 
1092         /* Zeroing the unused blocks on this cluster */
1093         blknr += nr_used;
1094         n = nr_used;
1095         while (blknr < last_blknr) {
1096                 bhs[n] = sb_getblk(sb, blknr);
1097                 if (!bhs[n]) {
1098                         err = -ENOMEM;
1099                         goto error;
1100                 }
1101                 /* Avoid race with userspace read via bdev */
1102                 lock_buffer(bhs[n]);
1103                 memset(bhs[n]->b_data, 0, sb->s_blocksize);
1104                 set_buffer_uptodate(bhs[n]);
1105                 unlock_buffer(bhs[n]);
1106                 mark_buffer_dirty_inode(bhs[n], dir);
1107 
1108                 n++;
1109                 blknr++;
1110                 if (n == nr_bhs) {
1111                         if (IS_DIRSYNC(dir)) {
1112                                 err = fat_sync_bhs(bhs, n);
1113                                 if (err)
1114                                         goto error;
1115                         }
1116                         for (i = 0; i < n; i++)
1117                                 brelse(bhs[i]);
1118                         n = 0;
1119                 }
1120         }
1121         if (IS_DIRSYNC(dir)) {
1122                 err = fat_sync_bhs(bhs, n);
1123                 if (err)
1124                         goto error;
1125         }
1126         for (i = 0; i < n; i++)
1127                 brelse(bhs[i]);
1128 
1129         return 0;
1130 
1131 error:
1132         for (i = 0; i < n; i++)
1133                 bforget(bhs[i]);
1134         return err;
1135 }
1136 
1137 int fat_alloc_new_dir(struct inode *dir, struct timespec64 *ts)
1138 {
1139         struct super_block *sb = dir->i_sb;
1140         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1141         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1142         struct msdos_dir_entry *de;
1143         sector_t blknr;
1144         __le16 date, time;
1145         u8 time_cs;
1146         int err, cluster;
1147 
1148         err = fat_alloc_clusters(dir, &cluster, 1);
1149         if (err)
1150                 goto error;
1151 
1152         blknr = fat_clus_to_blknr(sbi, cluster);
1153         bhs[0] = sb_getblk(sb, blknr);
1154         if (!bhs[0]) {
1155                 err = -ENOMEM;
1156                 goto error_free;
1157         }
1158 
1159         fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
1160 
1161         de = (struct msdos_dir_entry *)bhs[0]->b_data;
1162         /* Avoid race with userspace read via bdev */
1163         lock_buffer(bhs[0]);
1164         /* filling the new directory slots ("." and ".." entries) */
1165         memcpy(de[0].name, MSDOS_DOT, MSDOS_NAME);
1166         memcpy(de[1].name, MSDOS_DOTDOT, MSDOS_NAME);
1167         de->attr = de[1].attr = ATTR_DIR;
1168         de[0].lcase = de[1].lcase = 0;
1169         de[0].time = de[1].time = time;
1170         de[0].date = de[1].date = date;
1171         if (sbi->options.isvfat) {
1172                 /* extra timestamps */
1173                 de[0].ctime = de[1].ctime = time;
1174                 de[0].ctime_cs = de[1].ctime_cs = time_cs;
1175                 de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = date;
1176         } else {
1177                 de[0].ctime = de[1].ctime = 0;
1178                 de[0].ctime_cs = de[1].ctime_cs = 0;
1179                 de[0].adate = de[0].cdate = de[1].adate = de[1].cdate = 0;
1180         }
1181         fat_set_start(&de[0], cluster);
1182         fat_set_start(&de[1], MSDOS_I(dir)->i_logstart);
1183         de[0].size = de[1].size = 0;
1184         memset(de + 2, 0, sb->s_blocksize - 2 * sizeof(*de));
1185         set_buffer_uptodate(bhs[0]);
1186         unlock_buffer(bhs[0]);
1187         mark_buffer_dirty_inode(bhs[0], dir);
1188 
1189         err = fat_zeroed_cluster(dir, blknr, 1, bhs, MAX_BUF_PER_PAGE);
1190         if (err)
1191                 goto error_free;
1192 
1193         return cluster;
1194 
1195 error_free:
1196         fat_free_clusters(dir, cluster);
1197 error:
1198         return err;
1199 }
1200 EXPORT_SYMBOL_GPL(fat_alloc_new_dir);
1201 
1202 static int fat_add_new_entries(struct inode *dir, void *slots, int nr_slots,
1203                                int *nr_cluster, struct msdos_dir_entry **de,
1204                                struct buffer_head **bh, loff_t *i_pos)
1205 {
1206         struct super_block *sb = dir->i_sb;
1207         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1208         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
1209         sector_t blknr, start_blknr, last_blknr;
1210         unsigned long size, copy;
1211         int err, i, n, offset, cluster[2];
1212 
1213         /*
1214          * The minimum cluster size is 512bytes, and maximum entry
1215          * size is 32*slots (672bytes).  So, iff the cluster size is
1216          * 512bytes, we may need two clusters.
1217          */
1218         size = nr_slots * sizeof(struct msdos_dir_entry);
1219         *nr_cluster = (size + (sbi->cluster_size - 1)) >> sbi->cluster_bits;
1220         BUG_ON(*nr_cluster > 2);
1221 
1222         err = fat_alloc_clusters(dir, cluster, *nr_cluster);
1223         if (err)
1224                 goto error;
1225 
1226         /*
1227          * First stage: Fill the directory entry.  NOTE: This cluster
1228          * is not referenced from any inode yet, so updates order is
1229          * not important.
1230          */
1231         i = n = copy = 0;
1232         do {
1233                 start_blknr = blknr = fat_clus_to_blknr(sbi, cluster[i]);
1234                 last_blknr = start_blknr + sbi->sec_per_clus;
1235                 while (blknr < last_blknr) {
1236                         bhs[n] = sb_getblk(sb, blknr);
1237                         if (!bhs[n]) {
1238                                 err = -ENOMEM;
1239                                 goto error_nomem;
1240                         }
1241 
1242                         /* fill the directory entry */
1243                         copy = min(size, sb->s_blocksize);
1244                         /* Avoid race with userspace read via bdev */
1245                         lock_buffer(bhs[n]);
1246                         memcpy(bhs[n]->b_data, slots, copy);
1247                         set_buffer_uptodate(bhs[n]);
1248                         unlock_buffer(bhs[n]);
1249                         mark_buffer_dirty_inode(bhs[n], dir);
1250                         slots += copy;
1251                         size -= copy;
1252                         if (!size)
1253                                 break;
1254                         n++;
1255                         blknr++;
1256                 }
1257         } while (++i < *nr_cluster);
1258 
1259         memset(bhs[n]->b_data + copy, 0, sb->s_blocksize - copy);
1260         offset = copy - sizeof(struct msdos_dir_entry);
1261         get_bh(bhs[n]);
1262         *bh = bhs[n];
1263         *de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
1264         *i_pos = fat_make_i_pos(sb, *bh, *de);
1265 
1266         /* Second stage: clear the rest of cluster, and write outs */
1267         err = fat_zeroed_cluster(dir, start_blknr, ++n, bhs, MAX_BUF_PER_PAGE);
1268         if (err)
1269                 goto error_free;
1270 
1271         return cluster[0];
1272 
1273 error_free:
1274         brelse(*bh);
1275         *bh = NULL;
1276         n = 0;
1277 error_nomem:
1278         for (i = 0; i < n; i++)
1279                 bforget(bhs[i]);
1280         fat_free_clusters(dir, cluster[0]);
1281 error:
1282         return err;
1283 }
1284 
1285 int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
1286                     struct fat_slot_info *sinfo)
1287 {
1288         struct super_block *sb = dir->i_sb;
1289         struct msdos_sb_info *sbi = MSDOS_SB(sb);
1290         struct buffer_head *bh, *prev, *bhs[3]; /* 32*slots (672bytes) */
1291         struct msdos_dir_entry *uninitialized_var(de);
1292         int err, free_slots, i, nr_bhs;
1293         loff_t pos, i_pos;
1294 
1295         sinfo->nr_slots = nr_slots;
1296 
1297         /* First stage: search free directory entries */
1298         free_slots = nr_bhs = 0;
1299         bh = prev = NULL;
1300         pos = 0;
1301         err = -ENOSPC;
1302         while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
1303                 /* check the maximum size of directory */
1304                 if (pos >= FAT_MAX_DIR_SIZE)
1305                         goto error;
1306 
1307                 if (IS_FREE(de->name)) {
1308                         if (prev != bh) {
1309                                 get_bh(bh);
1310                                 bhs[nr_bhs] = prev = bh;
1311                                 nr_bhs++;
1312                         }
1313                         free_slots++;
1314                         if (free_slots == nr_slots)
1315                                 goto found;
1316                 } else {
1317                         for (i = 0; i < nr_bhs; i++)
1318                                 brelse(bhs[i]);
1319                         prev = NULL;
1320                         free_slots = nr_bhs = 0;
1321                 }
1322         }
1323         if (dir->i_ino == MSDOS_ROOT_INO) {
1324                 if (!is_fat32(sbi))
1325                         goto error;
1326         } else if (MSDOS_I(dir)->i_start == 0) {
1327                 fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",
1328                        MSDOS_I(dir)->i_pos);
1329                 err = -EIO;
1330                 goto error;
1331         }
1332 
1333 found:
1334         err = 0;
1335         pos -= free_slots * sizeof(*de);
1336         nr_slots -= free_slots;
1337         if (free_slots) {
1338                 /*
1339                  * Second stage: filling the free entries with new entries.
1340                  * NOTE: If this slots has shortname, first, we write
1341                  * the long name slots, then write the short name.
1342                  */
1343                 int size = free_slots * sizeof(*de);
1344                 int offset = pos & (sb->s_blocksize - 1);
1345                 int long_bhs = nr_bhs - (nr_slots == 0);
1346 
1347                 /* Fill the long name slots. */
1348                 for (i = 0; i < long_bhs; i++) {
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                         offset = 0;
1353                         slots += copy;
1354                         size -= copy;
1355                 }
1356                 if (long_bhs && IS_DIRSYNC(dir))
1357                         err = fat_sync_bhs(bhs, long_bhs);
1358                 if (!err && i < nr_bhs) {
1359                         /* Fill the short name slot. */
1360                         int copy = min_t(int, sb->s_blocksize - offset, size);
1361                         memcpy(bhs[i]->b_data + offset, slots, copy);
1362                         mark_buffer_dirty_inode(bhs[i], dir);
1363                         if (IS_DIRSYNC(dir))
1364                                 err = sync_dirty_buffer(bhs[i]);
1365                 }
1366                 for (i = 0; i < nr_bhs; i++)
1367                         brelse(bhs[i]);
1368                 if (err)
1369                         goto error_remove;
1370         }
1371 
1372         if (nr_slots) {
1373                 int cluster, nr_cluster;
1374 
1375                 /*
1376                  * Third stage: allocate the cluster for new entries.
1377                  * And initialize the cluster with new entries, then
1378                  * add the cluster to dir.
1379                  */
1380                 cluster = fat_add_new_entries(dir, slots, nr_slots, &nr_cluster,
1381                                               &de, &bh, &i_pos);
1382                 if (cluster < 0) {
1383                         err = cluster;
1384                         goto error_remove;
1385                 }
1386                 err = fat_chain_add(dir, cluster, nr_cluster);
1387                 if (err) {
1388                         fat_free_clusters(dir, cluster);
1389                         goto error_remove;
1390                 }
1391                 if (dir->i_size & (sbi->cluster_size - 1)) {
1392                         fat_fs_error(sb, "Odd directory size");
1393                         dir->i_size = (dir->i_size + sbi->cluster_size - 1)
1394                                 & ~((loff_t)sbi->cluster_size - 1);
1395                 }
1396                 dir->i_size += nr_cluster << sbi->cluster_bits;
1397                 MSDOS_I(dir)->mmu_private += nr_cluster << sbi->cluster_bits;
1398         }
1399         sinfo->slot_off = pos;
1400         sinfo->de = de;
1401         sinfo->bh = bh;
1402         sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
1403 
1404         return 0;
1405 
1406 error:
1407         brelse(bh);
1408         for (i = 0; i < nr_bhs; i++)
1409                 brelse(bhs[i]);
1410         return err;
1411 
1412 error_remove:
1413         brelse(bh);
1414         if (free_slots)
1415                 __fat_remove_entries(dir, pos, free_slots);
1416         return err;
1417 }
1418 EXPORT_SYMBOL_GPL(fat_add_entries);
1419 

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