xref: /openbmc/linux/fs/exfat/dir.c (revision c4f7ac64)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
4  */
5 
6 #include <linux/slab.h>
7 #include <linux/compat.h>
8 #include <linux/bio.h>
9 #include <linux/buffer_head.h>
10 
11 #include "exfat_raw.h"
12 #include "exfat_fs.h"
13 
14 static int exfat_extract_uni_name(struct exfat_dentry *ep,
15 		unsigned short *uniname)
16 {
17 	int i, len = 0;
18 
19 	for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
20 		*uniname = le16_to_cpu(ep->dentry.name.unicode_0_14[i]);
21 		if (*uniname == 0x0)
22 			return len;
23 		uniname++;
24 		len++;
25 	}
26 
27 	*uniname = 0x0;
28 	return len;
29 
30 }
31 
32 static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
33 		struct exfat_chain *p_dir, int entry, unsigned short *uniname)
34 {
35 	int i;
36 	struct exfat_entry_set_cache *es;
37 
38 	es = exfat_get_dentry_set(sb, p_dir, entry, ES_ALL_ENTRIES);
39 	if (!es)
40 		return;
41 
42 	/*
43 	 * First entry  : file entry
44 	 * Second entry : stream-extension entry
45 	 * Third entry  : first file-name entry
46 	 * So, the index of first file-name dentry should start from 2.
47 	 */
48 	for (i = 2; i < es->num_entries; i++) {
49 		struct exfat_dentry *ep = exfat_get_dentry_cached(es, i);
50 
51 		/* end of name entry */
52 		if (exfat_get_entry_type(ep) != TYPE_EXTEND)
53 			break;
54 
55 		exfat_extract_uni_name(ep, uniname);
56 		uniname += EXFAT_FILE_NAME_LEN;
57 	}
58 
59 	exfat_free_dentry_set(es, false);
60 }
61 
62 /* read a directory entry from the opened directory */
63 static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_entry *dir_entry)
64 {
65 	int i, dentries_per_clu, dentries_per_clu_bits = 0, num_ext;
66 	unsigned int type, clu_offset;
67 	sector_t sector;
68 	struct exfat_chain dir, clu;
69 	struct exfat_uni_name uni_name;
70 	struct exfat_dentry *ep;
71 	struct super_block *sb = inode->i_sb;
72 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
73 	struct exfat_inode_info *ei = EXFAT_I(inode);
74 	unsigned int dentry = EXFAT_B_TO_DEN(*cpos) & 0xFFFFFFFF;
75 	struct buffer_head *bh;
76 
77 	/* check if the given file ID is opened */
78 	if (ei->type != TYPE_DIR)
79 		return -EPERM;
80 
81 	if (ei->entry == -1)
82 		exfat_chain_set(&dir, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
83 	else
84 		exfat_chain_set(&dir, ei->start_clu,
85 			EXFAT_B_TO_CLU(i_size_read(inode), sbi), ei->flags);
86 
87 	dentries_per_clu = sbi->dentries_per_clu;
88 	dentries_per_clu_bits = ilog2(dentries_per_clu);
89 
90 	clu_offset = dentry >> dentries_per_clu_bits;
91 	exfat_chain_dup(&clu, &dir);
92 
93 	if (clu.flags == ALLOC_NO_FAT_CHAIN) {
94 		clu.dir += clu_offset;
95 		clu.size -= clu_offset;
96 	} else {
97 		/* hint_information */
98 		if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&
99 		    ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {
100 			clu_offset -= ei->hint_bmap.off;
101 			clu.dir = ei->hint_bmap.clu;
102 		}
103 
104 		while (clu_offset > 0) {
105 			if (exfat_get_next_cluster(sb, &(clu.dir)))
106 				return -EIO;
107 
108 			clu_offset--;
109 		}
110 	}
111 
112 	while (clu.dir != EXFAT_EOF_CLUSTER) {
113 		i = dentry & (dentries_per_clu - 1);
114 
115 		for ( ; i < dentries_per_clu; i++, dentry++) {
116 			ep = exfat_get_dentry(sb, &clu, i, &bh, &sector);
117 			if (!ep)
118 				return -EIO;
119 
120 			type = exfat_get_entry_type(ep);
121 			if (type == TYPE_UNUSED) {
122 				brelse(bh);
123 				break;
124 			}
125 
126 			if (type != TYPE_FILE && type != TYPE_DIR) {
127 				brelse(bh);
128 				continue;
129 			}
130 
131 			num_ext = ep->dentry.file.num_ext;
132 			dir_entry->attr = le16_to_cpu(ep->dentry.file.attr);
133 			exfat_get_entry_time(sbi, &dir_entry->crtime,
134 					ep->dentry.file.create_tz,
135 					ep->dentry.file.create_time,
136 					ep->dentry.file.create_date,
137 					ep->dentry.file.create_time_cs);
138 			exfat_get_entry_time(sbi, &dir_entry->mtime,
139 					ep->dentry.file.modify_tz,
140 					ep->dentry.file.modify_time,
141 					ep->dentry.file.modify_date,
142 					ep->dentry.file.modify_time_cs);
143 			exfat_get_entry_time(sbi, &dir_entry->atime,
144 					ep->dentry.file.access_tz,
145 					ep->dentry.file.access_time,
146 					ep->dentry.file.access_date,
147 					0);
148 
149 			*uni_name.name = 0x0;
150 			exfat_get_uniname_from_ext_entry(sb, &clu, i,
151 				uni_name.name);
152 			exfat_utf16_to_nls(sb, &uni_name,
153 				dir_entry->namebuf.lfn,
154 				dir_entry->namebuf.lfnbuf_len);
155 			brelse(bh);
156 
157 			ep = exfat_get_dentry(sb, &clu, i + 1, &bh, NULL);
158 			if (!ep)
159 				return -EIO;
160 			dir_entry->size =
161 				le64_to_cpu(ep->dentry.stream.valid_size);
162 			dir_entry->entry = dentry;
163 			brelse(bh);
164 
165 			ei->hint_bmap.off = dentry >> dentries_per_clu_bits;
166 			ei->hint_bmap.clu = clu.dir;
167 
168 			*cpos = EXFAT_DEN_TO_B(dentry + 1 + num_ext);
169 			return 0;
170 		}
171 
172 		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
173 			if (--clu.size > 0)
174 				clu.dir++;
175 			else
176 				clu.dir = EXFAT_EOF_CLUSTER;
177 		} else {
178 			if (exfat_get_next_cluster(sb, &(clu.dir)))
179 				return -EIO;
180 		}
181 	}
182 
183 	dir_entry->namebuf.lfn[0] = '\0';
184 	*cpos = EXFAT_DEN_TO_B(dentry);
185 	return 0;
186 }
187 
188 static void exfat_init_namebuf(struct exfat_dentry_namebuf *nb)
189 {
190 	nb->lfn = NULL;
191 	nb->lfnbuf_len = 0;
192 }
193 
194 static int exfat_alloc_namebuf(struct exfat_dentry_namebuf *nb)
195 {
196 	nb->lfn = __getname();
197 	if (!nb->lfn)
198 		return -ENOMEM;
199 	nb->lfnbuf_len = MAX_VFSNAME_BUF_SIZE;
200 	return 0;
201 }
202 
203 static void exfat_free_namebuf(struct exfat_dentry_namebuf *nb)
204 {
205 	if (!nb->lfn)
206 		return;
207 
208 	__putname(nb->lfn);
209 	exfat_init_namebuf(nb);
210 }
211 
212 /* skip iterating emit_dots when dir is empty */
213 #define ITER_POS_FILLED_DOTS    (2)
214 static int exfat_iterate(struct file *filp, struct dir_context *ctx)
215 {
216 	struct inode *inode = filp->f_path.dentry->d_inode;
217 	struct super_block *sb = inode->i_sb;
218 	struct inode *tmp;
219 	struct exfat_dir_entry de;
220 	struct exfat_dentry_namebuf *nb = &(de.namebuf);
221 	struct exfat_inode_info *ei = EXFAT_I(inode);
222 	unsigned long inum;
223 	loff_t cpos, i_pos;
224 	int err = 0, fake_offset = 0;
225 
226 	exfat_init_namebuf(nb);
227 	mutex_lock(&EXFAT_SB(sb)->s_lock);
228 
229 	cpos = ctx->pos;
230 	if (!dir_emit_dots(filp, ctx))
231 		goto unlock;
232 
233 	if (ctx->pos == ITER_POS_FILLED_DOTS) {
234 		cpos = 0;
235 		fake_offset = 1;
236 	}
237 
238 	if (cpos & (DENTRY_SIZE - 1)) {
239 		err = -ENOENT;
240 		goto unlock;
241 	}
242 
243 	/* name buffer should be allocated before use */
244 	err = exfat_alloc_namebuf(nb);
245 	if (err)
246 		goto unlock;
247 get_new:
248 	if (cpos >= i_size_read(inode))
249 		goto end_of_dir;
250 
251 	err = exfat_readdir(inode, &cpos, &de);
252 	if (err) {
253 		/*
254 		 * At least we tried to read a sector.  Move cpos to next sector
255 		 * position (should be aligned).
256 		 */
257 		if (err == -EIO) {
258 			cpos += 1 << (sb->s_blocksize_bits);
259 			cpos &= ~(sb->s_blocksize - 1);
260 		}
261 
262 		err = -EIO;
263 		goto end_of_dir;
264 	}
265 
266 	if (!nb->lfn[0])
267 		goto end_of_dir;
268 
269 	i_pos = ((loff_t)ei->start_clu << 32) |	(de.entry & 0xffffffff);
270 	tmp = exfat_iget(sb, i_pos);
271 	if (tmp) {
272 		inum = tmp->i_ino;
273 		iput(tmp);
274 	} else {
275 		inum = iunique(sb, EXFAT_ROOT_INO);
276 	}
277 
278 	/*
279 	 * Before calling dir_emit(), sb_lock should be released.
280 	 * Because page fault can occur in dir_emit() when the size
281 	 * of buffer given from user is larger than one page size.
282 	 */
283 	mutex_unlock(&EXFAT_SB(sb)->s_lock);
284 	if (!dir_emit(ctx, nb->lfn, strlen(nb->lfn), inum,
285 			(de.attr & ATTR_SUBDIR) ? DT_DIR : DT_REG))
286 		goto out_unlocked;
287 	mutex_lock(&EXFAT_SB(sb)->s_lock);
288 	ctx->pos = cpos;
289 	goto get_new;
290 
291 end_of_dir:
292 	if (!cpos && fake_offset)
293 		cpos = ITER_POS_FILLED_DOTS;
294 	ctx->pos = cpos;
295 unlock:
296 	mutex_unlock(&EXFAT_SB(sb)->s_lock);
297 out_unlocked:
298 	/*
299 	 * To improve performance, free namebuf after unlock sb_lock.
300 	 * If namebuf is not allocated, this function do nothing
301 	 */
302 	exfat_free_namebuf(nb);
303 	return err;
304 }
305 
306 const struct file_operations exfat_dir_operations = {
307 	.llseek		= generic_file_llseek,
308 	.read		= generic_read_dir,
309 	.iterate	= exfat_iterate,
310 	.unlocked_ioctl = exfat_ioctl,
311 #ifdef CONFIG_COMPAT
312 	.compat_ioctl = exfat_compat_ioctl,
313 #endif
314 	.fsync		= exfat_file_fsync,
315 };
316 
317 int exfat_alloc_new_dir(struct inode *inode, struct exfat_chain *clu)
318 {
319 	int ret;
320 
321 	exfat_chain_set(clu, EXFAT_EOF_CLUSTER, 0, ALLOC_NO_FAT_CHAIN);
322 
323 	ret = exfat_alloc_cluster(inode, 1, clu, IS_DIRSYNC(inode));
324 	if (ret)
325 		return ret;
326 
327 	return exfat_zeroed_cluster(inode, clu->dir);
328 }
329 
330 int exfat_calc_num_entries(struct exfat_uni_name *p_uniname)
331 {
332 	int len;
333 
334 	len = p_uniname->name_len;
335 	if (len == 0)
336 		return -EINVAL;
337 
338 	/* 1 file entry + 1 stream entry + name entries */
339 	return ((len - 1) / EXFAT_FILE_NAME_LEN + 3);
340 }
341 
342 unsigned int exfat_get_entry_type(struct exfat_dentry *ep)
343 {
344 	if (ep->type == EXFAT_UNUSED)
345 		return TYPE_UNUSED;
346 	if (IS_EXFAT_DELETED(ep->type))
347 		return TYPE_DELETED;
348 	if (ep->type == EXFAT_INVAL)
349 		return TYPE_INVALID;
350 	if (IS_EXFAT_CRITICAL_PRI(ep->type)) {
351 		if (ep->type == EXFAT_BITMAP)
352 			return TYPE_BITMAP;
353 		if (ep->type == EXFAT_UPCASE)
354 			return TYPE_UPCASE;
355 		if (ep->type == EXFAT_VOLUME)
356 			return TYPE_VOLUME;
357 		if (ep->type == EXFAT_FILE) {
358 			if (le16_to_cpu(ep->dentry.file.attr) & ATTR_SUBDIR)
359 				return TYPE_DIR;
360 			return TYPE_FILE;
361 		}
362 		return TYPE_CRITICAL_PRI;
363 	}
364 	if (IS_EXFAT_BENIGN_PRI(ep->type)) {
365 		if (ep->type == EXFAT_GUID)
366 			return TYPE_GUID;
367 		if (ep->type == EXFAT_PADDING)
368 			return TYPE_PADDING;
369 		if (ep->type == EXFAT_ACLTAB)
370 			return TYPE_ACLTAB;
371 		return TYPE_BENIGN_PRI;
372 	}
373 	if (IS_EXFAT_CRITICAL_SEC(ep->type)) {
374 		if (ep->type == EXFAT_STREAM)
375 			return TYPE_STREAM;
376 		if (ep->type == EXFAT_NAME)
377 			return TYPE_EXTEND;
378 		if (ep->type == EXFAT_ACL)
379 			return TYPE_ACL;
380 		return TYPE_CRITICAL_SEC;
381 	}
382 	return TYPE_BENIGN_SEC;
383 }
384 
385 static void exfat_set_entry_type(struct exfat_dentry *ep, unsigned int type)
386 {
387 	if (type == TYPE_UNUSED) {
388 		ep->type = EXFAT_UNUSED;
389 	} else if (type == TYPE_DELETED) {
390 		ep->type &= EXFAT_DELETE;
391 	} else if (type == TYPE_STREAM) {
392 		ep->type = EXFAT_STREAM;
393 	} else if (type == TYPE_EXTEND) {
394 		ep->type = EXFAT_NAME;
395 	} else if (type == TYPE_BITMAP) {
396 		ep->type = EXFAT_BITMAP;
397 	} else if (type == TYPE_UPCASE) {
398 		ep->type = EXFAT_UPCASE;
399 	} else if (type == TYPE_VOLUME) {
400 		ep->type = EXFAT_VOLUME;
401 	} else if (type == TYPE_DIR) {
402 		ep->type = EXFAT_FILE;
403 		ep->dentry.file.attr = cpu_to_le16(ATTR_SUBDIR);
404 	} else if (type == TYPE_FILE) {
405 		ep->type = EXFAT_FILE;
406 		ep->dentry.file.attr = cpu_to_le16(ATTR_ARCHIVE);
407 	}
408 }
409 
410 static void exfat_init_stream_entry(struct exfat_dentry *ep,
411 		unsigned char flags, unsigned int start_clu,
412 		unsigned long long size)
413 {
414 	exfat_set_entry_type(ep, TYPE_STREAM);
415 	ep->dentry.stream.flags = flags;
416 	ep->dentry.stream.start_clu = cpu_to_le32(start_clu);
417 	ep->dentry.stream.valid_size = cpu_to_le64(size);
418 	ep->dentry.stream.size = cpu_to_le64(size);
419 }
420 
421 static void exfat_init_name_entry(struct exfat_dentry *ep,
422 		unsigned short *uniname)
423 {
424 	int i;
425 
426 	exfat_set_entry_type(ep, TYPE_EXTEND);
427 	ep->dentry.name.flags = 0x0;
428 
429 	for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
430 		if (*uniname != 0x0) {
431 			ep->dentry.name.unicode_0_14[i] = cpu_to_le16(*uniname);
432 			uniname++;
433 		} else {
434 			ep->dentry.name.unicode_0_14[i] = 0x0;
435 		}
436 	}
437 }
438 
439 int exfat_init_dir_entry(struct inode *inode, struct exfat_chain *p_dir,
440 		int entry, unsigned int type, unsigned int start_clu,
441 		unsigned long long size)
442 {
443 	struct super_block *sb = inode->i_sb;
444 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
445 	struct timespec64 ts = current_time(inode);
446 	sector_t sector;
447 	struct exfat_dentry *ep;
448 	struct buffer_head *bh;
449 
450 	/*
451 	 * We cannot use exfat_get_dentry_set here because file ep is not
452 	 * initialized yet.
453 	 */
454 	ep = exfat_get_dentry(sb, p_dir, entry, &bh, &sector);
455 	if (!ep)
456 		return -EIO;
457 
458 	exfat_set_entry_type(ep, type);
459 	exfat_set_entry_time(sbi, &ts,
460 			&ep->dentry.file.create_tz,
461 			&ep->dentry.file.create_time,
462 			&ep->dentry.file.create_date,
463 			&ep->dentry.file.create_time_cs);
464 	exfat_set_entry_time(sbi, &ts,
465 			&ep->dentry.file.modify_tz,
466 			&ep->dentry.file.modify_time,
467 			&ep->dentry.file.modify_date,
468 			&ep->dentry.file.modify_time_cs);
469 	exfat_set_entry_time(sbi, &ts,
470 			&ep->dentry.file.access_tz,
471 			&ep->dentry.file.access_time,
472 			&ep->dentry.file.access_date,
473 			NULL);
474 
475 	exfat_update_bh(bh, IS_DIRSYNC(inode));
476 	brelse(bh);
477 
478 	ep = exfat_get_dentry(sb, p_dir, entry + 1, &bh, &sector);
479 	if (!ep)
480 		return -EIO;
481 
482 	exfat_init_stream_entry(ep,
483 		(type == TYPE_FILE) ? ALLOC_FAT_CHAIN : ALLOC_NO_FAT_CHAIN,
484 		start_clu, size);
485 	exfat_update_bh(bh, IS_DIRSYNC(inode));
486 	brelse(bh);
487 
488 	return 0;
489 }
490 
491 int exfat_update_dir_chksum(struct inode *inode, struct exfat_chain *p_dir,
492 		int entry)
493 {
494 	struct super_block *sb = inode->i_sb;
495 	int ret = 0;
496 	int i, num_entries;
497 	sector_t sector;
498 	u16 chksum;
499 	struct exfat_dentry *ep, *fep;
500 	struct buffer_head *fbh, *bh;
501 
502 	fep = exfat_get_dentry(sb, p_dir, entry, &fbh, &sector);
503 	if (!fep)
504 		return -EIO;
505 
506 	num_entries = fep->dentry.file.num_ext + 1;
507 	chksum = exfat_calc_chksum16(fep, DENTRY_SIZE, 0, CS_DIR_ENTRY);
508 
509 	for (i = 1; i < num_entries; i++) {
510 		ep = exfat_get_dentry(sb, p_dir, entry + i, &bh, NULL);
511 		if (!ep) {
512 			ret = -EIO;
513 			goto release_fbh;
514 		}
515 		chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
516 				CS_DEFAULT);
517 		brelse(bh);
518 	}
519 
520 	fep->dentry.file.checksum = cpu_to_le16(chksum);
521 	exfat_update_bh(fbh, IS_DIRSYNC(inode));
522 release_fbh:
523 	brelse(fbh);
524 	return ret;
525 }
526 
527 int exfat_init_ext_entry(struct inode *inode, struct exfat_chain *p_dir,
528 		int entry, int num_entries, struct exfat_uni_name *p_uniname)
529 {
530 	struct super_block *sb = inode->i_sb;
531 	int i;
532 	sector_t sector;
533 	unsigned short *uniname = p_uniname->name;
534 	struct exfat_dentry *ep;
535 	struct buffer_head *bh;
536 	int sync = IS_DIRSYNC(inode);
537 
538 	ep = exfat_get_dentry(sb, p_dir, entry, &bh, &sector);
539 	if (!ep)
540 		return -EIO;
541 
542 	ep->dentry.file.num_ext = (unsigned char)(num_entries - 1);
543 	exfat_update_bh(bh, sync);
544 	brelse(bh);
545 
546 	ep = exfat_get_dentry(sb, p_dir, entry + 1, &bh, &sector);
547 	if (!ep)
548 		return -EIO;
549 
550 	ep->dentry.stream.name_len = p_uniname->name_len;
551 	ep->dentry.stream.name_hash = cpu_to_le16(p_uniname->name_hash);
552 	exfat_update_bh(bh, sync);
553 	brelse(bh);
554 
555 	for (i = EXFAT_FIRST_CLUSTER; i < num_entries; i++) {
556 		ep = exfat_get_dentry(sb, p_dir, entry + i, &bh, &sector);
557 		if (!ep)
558 			return -EIO;
559 
560 		exfat_init_name_entry(ep, uniname);
561 		exfat_update_bh(bh, sync);
562 		brelse(bh);
563 		uniname += EXFAT_FILE_NAME_LEN;
564 	}
565 
566 	exfat_update_dir_chksum(inode, p_dir, entry);
567 	return 0;
568 }
569 
570 int exfat_remove_entries(struct inode *inode, struct exfat_chain *p_dir,
571 		int entry, int order, int num_entries)
572 {
573 	struct super_block *sb = inode->i_sb;
574 	int i;
575 	sector_t sector;
576 	struct exfat_dentry *ep;
577 	struct buffer_head *bh;
578 
579 	for (i = order; i < num_entries; i++) {
580 		ep = exfat_get_dentry(sb, p_dir, entry + i, &bh, &sector);
581 		if (!ep)
582 			return -EIO;
583 
584 		exfat_set_entry_type(ep, TYPE_DELETED);
585 		exfat_update_bh(bh, IS_DIRSYNC(inode));
586 		brelse(bh);
587 	}
588 
589 	return 0;
590 }
591 
592 void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
593 {
594 	int chksum_type = CS_DIR_ENTRY, i;
595 	unsigned short chksum = 0;
596 	struct exfat_dentry *ep;
597 
598 	for (i = 0; i < es->num_entries; i++) {
599 		ep = exfat_get_dentry_cached(es, i);
600 		chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
601 					     chksum_type);
602 		chksum_type = CS_DEFAULT;
603 	}
604 	ep = exfat_get_dentry_cached(es, 0);
605 	ep->dentry.file.checksum = cpu_to_le16(chksum);
606 	es->modified = true;
607 }
608 
609 int exfat_free_dentry_set(struct exfat_entry_set_cache *es, int sync)
610 {
611 	int i, err = 0;
612 
613 	if (es->modified)
614 		err = exfat_update_bhs(es->bh, es->num_bh, sync);
615 
616 	for (i = 0; i < es->num_bh; i++)
617 		if (err)
618 			bforget(es->bh[i]);
619 		else
620 			brelse(es->bh[i]);
621 	kfree(es);
622 	return err;
623 }
624 
625 static int exfat_walk_fat_chain(struct super_block *sb,
626 		struct exfat_chain *p_dir, unsigned int byte_offset,
627 		unsigned int *clu)
628 {
629 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
630 	unsigned int clu_offset;
631 	unsigned int cur_clu;
632 
633 	clu_offset = EXFAT_B_TO_CLU(byte_offset, sbi);
634 	cur_clu = p_dir->dir;
635 
636 	if (p_dir->flags == ALLOC_NO_FAT_CHAIN) {
637 		cur_clu += clu_offset;
638 	} else {
639 		while (clu_offset > 0) {
640 			if (exfat_get_next_cluster(sb, &cur_clu))
641 				return -EIO;
642 			if (cur_clu == EXFAT_EOF_CLUSTER) {
643 				exfat_fs_error(sb,
644 					"invalid dentry access beyond EOF (clu : %u, eidx : %d)",
645 					p_dir->dir,
646 					EXFAT_B_TO_DEN(byte_offset));
647 				return -EIO;
648 			}
649 			clu_offset--;
650 		}
651 	}
652 
653 	*clu = cur_clu;
654 	return 0;
655 }
656 
657 int exfat_find_location(struct super_block *sb, struct exfat_chain *p_dir,
658 		int entry, sector_t *sector, int *offset)
659 {
660 	int ret;
661 	unsigned int off, clu = 0;
662 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
663 
664 	off = EXFAT_DEN_TO_B(entry);
665 
666 	ret = exfat_walk_fat_chain(sb, p_dir, off, &clu);
667 	if (ret)
668 		return ret;
669 
670 	/* byte offset in cluster */
671 	off = EXFAT_CLU_OFFSET(off, sbi);
672 
673 	/* byte offset in sector    */
674 	*offset = EXFAT_BLK_OFFSET(off, sb);
675 
676 	/* sector offset in cluster */
677 	*sector = EXFAT_B_TO_BLK(off, sb);
678 	*sector += exfat_cluster_to_sector(sbi, clu);
679 	return 0;
680 }
681 
682 #define EXFAT_MAX_RA_SIZE     (128*1024)
683 static int exfat_dir_readahead(struct super_block *sb, sector_t sec)
684 {
685 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
686 	struct buffer_head *bh;
687 	unsigned int max_ra_count = EXFAT_MAX_RA_SIZE >> sb->s_blocksize_bits;
688 	unsigned int page_ra_count = PAGE_SIZE >> sb->s_blocksize_bits;
689 	unsigned int adj_ra_count = max(sbi->sect_per_clus, page_ra_count);
690 	unsigned int ra_count = min(adj_ra_count, max_ra_count);
691 
692 	/* Read-ahead is not required */
693 	if (sbi->sect_per_clus == 1)
694 		return 0;
695 
696 	if (sec < sbi->data_start_sector) {
697 		exfat_err(sb, "requested sector is invalid(sect:%llu, root:%llu)",
698 			  (unsigned long long)sec, sbi->data_start_sector);
699 		return -EIO;
700 	}
701 
702 	/* Not sector aligned with ra_count, resize ra_count to page size */
703 	if ((sec - sbi->data_start_sector) & (ra_count - 1))
704 		ra_count = page_ra_count;
705 
706 	bh = sb_find_get_block(sb, sec);
707 	if (!bh || !buffer_uptodate(bh)) {
708 		unsigned int i;
709 
710 		for (i = 0; i < ra_count; i++)
711 			sb_breadahead(sb, (sector_t)(sec + i));
712 	}
713 	brelse(bh);
714 	return 0;
715 }
716 
717 struct exfat_dentry *exfat_get_dentry(struct super_block *sb,
718 		struct exfat_chain *p_dir, int entry, struct buffer_head **bh,
719 		sector_t *sector)
720 {
721 	unsigned int dentries_per_page = EXFAT_B_TO_DEN(PAGE_SIZE);
722 	int off;
723 	sector_t sec;
724 
725 	if (p_dir->dir == DIR_DELETED) {
726 		exfat_err(sb, "abnormal access to deleted dentry");
727 		return NULL;
728 	}
729 
730 	if (exfat_find_location(sb, p_dir, entry, &sec, &off))
731 		return NULL;
732 
733 	if (p_dir->dir != EXFAT_FREE_CLUSTER &&
734 			!(entry & (dentries_per_page - 1)))
735 		exfat_dir_readahead(sb, sec);
736 
737 	*bh = sb_bread(sb, sec);
738 	if (!*bh)
739 		return NULL;
740 
741 	if (sector)
742 		*sector = sec;
743 	return (struct exfat_dentry *)((*bh)->b_data + off);
744 }
745 
746 enum exfat_validate_dentry_mode {
747 	ES_MODE_STARTED,
748 	ES_MODE_GET_FILE_ENTRY,
749 	ES_MODE_GET_STRM_ENTRY,
750 	ES_MODE_GET_NAME_ENTRY,
751 	ES_MODE_GET_CRITICAL_SEC_ENTRY,
752 };
753 
754 static bool exfat_validate_entry(unsigned int type,
755 		enum exfat_validate_dentry_mode *mode)
756 {
757 	if (type == TYPE_UNUSED || type == TYPE_DELETED)
758 		return false;
759 
760 	switch (*mode) {
761 	case ES_MODE_STARTED:
762 		if  (type != TYPE_FILE && type != TYPE_DIR)
763 			return false;
764 		*mode = ES_MODE_GET_FILE_ENTRY;
765 		return true;
766 	case ES_MODE_GET_FILE_ENTRY:
767 		if (type != TYPE_STREAM)
768 			return false;
769 		*mode = ES_MODE_GET_STRM_ENTRY;
770 		return true;
771 	case ES_MODE_GET_STRM_ENTRY:
772 		if (type != TYPE_EXTEND)
773 			return false;
774 		*mode = ES_MODE_GET_NAME_ENTRY;
775 		return true;
776 	case ES_MODE_GET_NAME_ENTRY:
777 		if (type == TYPE_STREAM)
778 			return false;
779 		if (type != TYPE_EXTEND) {
780 			if (!(type & TYPE_CRITICAL_SEC))
781 				return false;
782 			*mode = ES_MODE_GET_CRITICAL_SEC_ENTRY;
783 		}
784 		return true;
785 	case ES_MODE_GET_CRITICAL_SEC_ENTRY:
786 		if (type == TYPE_EXTEND || type == TYPE_STREAM)
787 			return false;
788 		if ((type & TYPE_CRITICAL_SEC) != TYPE_CRITICAL_SEC)
789 			return false;
790 		return true;
791 	default:
792 		WARN_ON_ONCE(1);
793 		return false;
794 	}
795 }
796 
797 struct exfat_dentry *exfat_get_dentry_cached(
798 	struct exfat_entry_set_cache *es, int num)
799 {
800 	int off = es->start_off + num * DENTRY_SIZE;
801 	struct buffer_head *bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
802 	char *p = bh->b_data + EXFAT_BLK_OFFSET(off, es->sb);
803 
804 	return (struct exfat_dentry *)p;
805 }
806 
807 /*
808  * Returns a set of dentries for a file or dir.
809  *
810  * Note It provides a direct pointer to bh->data via exfat_get_dentry_cached().
811  * User should call exfat_get_dentry_set() after setting 'modified' to apply
812  * changes made in this entry set to the real device.
813  *
814  * in:
815  *   sb+p_dir+entry: indicates a file/dir
816  *   type:  specifies how many dentries should be included.
817  * return:
818  *   pointer of entry set on success,
819  *   NULL on failure.
820  */
821 struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
822 		struct exfat_chain *p_dir, int entry, unsigned int type)
823 {
824 	int ret, i, num_bh;
825 	unsigned int off, byte_offset, clu = 0;
826 	sector_t sec;
827 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
828 	struct exfat_entry_set_cache *es;
829 	struct exfat_dentry *ep;
830 	int num_entries;
831 	enum exfat_validate_dentry_mode mode = ES_MODE_STARTED;
832 	struct buffer_head *bh;
833 
834 	if (p_dir->dir == DIR_DELETED) {
835 		exfat_err(sb, "access to deleted dentry");
836 		return NULL;
837 	}
838 
839 	byte_offset = EXFAT_DEN_TO_B(entry);
840 	ret = exfat_walk_fat_chain(sb, p_dir, byte_offset, &clu);
841 	if (ret)
842 		return NULL;
843 
844 	es = kzalloc(sizeof(*es), GFP_KERNEL);
845 	if (!es)
846 		return NULL;
847 	es->sb = sb;
848 	es->modified = false;
849 
850 	/* byte offset in cluster */
851 	byte_offset = EXFAT_CLU_OFFSET(byte_offset, sbi);
852 
853 	/* byte offset in sector */
854 	off = EXFAT_BLK_OFFSET(byte_offset, sb);
855 	es->start_off = off;
856 
857 	/* sector offset in cluster */
858 	sec = EXFAT_B_TO_BLK(byte_offset, sb);
859 	sec += exfat_cluster_to_sector(sbi, clu);
860 
861 	bh = sb_bread(sb, sec);
862 	if (!bh)
863 		goto free_es;
864 	es->bh[es->num_bh++] = bh;
865 
866 	ep = exfat_get_dentry_cached(es, 0);
867 	if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
868 		goto free_es;
869 
870 	num_entries = type == ES_ALL_ENTRIES ?
871 		ep->dentry.file.num_ext + 1 : type;
872 	es->num_entries = num_entries;
873 
874 	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
875 	for (i = 1; i < num_bh; i++) {
876 		/* get the next sector */
877 		if (exfat_is_last_sector_in_cluster(sbi, sec)) {
878 			if (p_dir->flags == ALLOC_NO_FAT_CHAIN)
879 				clu++;
880 			else if (exfat_get_next_cluster(sb, &clu))
881 				goto free_es;
882 			sec = exfat_cluster_to_sector(sbi, clu);
883 		} else {
884 			sec++;
885 		}
886 
887 		bh = sb_bread(sb, sec);
888 		if (!bh)
889 			goto free_es;
890 		es->bh[es->num_bh++] = bh;
891 	}
892 
893 	/* validiate cached dentries */
894 	for (i = 1; i < num_entries; i++) {
895 		ep = exfat_get_dentry_cached(es, i);
896 		if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
897 			goto free_es;
898 	}
899 	return es;
900 
901 free_es:
902 	exfat_free_dentry_set(es, false);
903 	return NULL;
904 }
905 
906 enum {
907 	DIRENT_STEP_FILE,
908 	DIRENT_STEP_STRM,
909 	DIRENT_STEP_NAME,
910 	DIRENT_STEP_SECD,
911 };
912 
913 /*
914  * @ei:         inode info of parent directory
915  * @p_dir:      directory structure of parent directory
916  * @num_entries:entry size of p_uniname
917  * @hint_opt:   If p_uniname is found, filled with optimized dir/entry
918  *              for traversing cluster chain.
919  * @return:
920  *   >= 0:      file directory entry position where the name exists
921  *   -ENOENT:   entry with the name does not exist
922  *   -EIO:      I/O error
923  */
924 int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
925 		struct exfat_chain *p_dir, struct exfat_uni_name *p_uniname,
926 		int num_entries, unsigned int type, struct exfat_hint *hint_opt)
927 {
928 	int i, rewind = 0, dentry = 0, end_eidx = 0, num_ext = 0, len;
929 	int order, step, name_len = 0;
930 	int dentries_per_clu, num_empty = 0;
931 	unsigned int entry_type;
932 	unsigned short *uniname = NULL;
933 	struct exfat_chain clu;
934 	struct exfat_hint *hint_stat = &ei->hint_stat;
935 	struct exfat_hint_femp candi_empty;
936 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
937 
938 	dentries_per_clu = sbi->dentries_per_clu;
939 
940 	exfat_chain_dup(&clu, p_dir);
941 
942 	if (hint_stat->eidx) {
943 		clu.dir = hint_stat->clu;
944 		dentry = hint_stat->eidx;
945 		end_eidx = dentry;
946 	}
947 
948 	candi_empty.eidx = EXFAT_HINT_NONE;
949 rewind:
950 	order = 0;
951 	step = DIRENT_STEP_FILE;
952 	while (clu.dir != EXFAT_EOF_CLUSTER) {
953 		i = dentry & (dentries_per_clu - 1);
954 		for (; i < dentries_per_clu; i++, dentry++) {
955 			struct exfat_dentry *ep;
956 			struct buffer_head *bh;
957 
958 			if (rewind && dentry == end_eidx)
959 				goto not_found;
960 
961 			ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
962 			if (!ep)
963 				return -EIO;
964 
965 			entry_type = exfat_get_entry_type(ep);
966 
967 			if (entry_type == TYPE_UNUSED ||
968 			    entry_type == TYPE_DELETED) {
969 				step = DIRENT_STEP_FILE;
970 
971 				num_empty++;
972 				if (candi_empty.eidx == EXFAT_HINT_NONE &&
973 						num_empty == 1) {
974 					exfat_chain_set(&candi_empty.cur,
975 						clu.dir, clu.size, clu.flags);
976 				}
977 
978 				if (candi_empty.eidx == EXFAT_HINT_NONE &&
979 						num_empty >= num_entries) {
980 					candi_empty.eidx =
981 						dentry - (num_empty - 1);
982 					WARN_ON(candi_empty.eidx < 0);
983 					candi_empty.count = num_empty;
984 
985 					if (ei->hint_femp.eidx ==
986 							EXFAT_HINT_NONE ||
987 						candi_empty.eidx <=
988 							 ei->hint_femp.eidx)
989 						ei->hint_femp = candi_empty;
990 				}
991 
992 				brelse(bh);
993 				if (entry_type == TYPE_UNUSED)
994 					goto not_found;
995 				continue;
996 			}
997 
998 			num_empty = 0;
999 			candi_empty.eidx = EXFAT_HINT_NONE;
1000 
1001 			if (entry_type == TYPE_FILE || entry_type == TYPE_DIR) {
1002 				step = DIRENT_STEP_FILE;
1003 				hint_opt->clu = clu.dir;
1004 				hint_opt->eidx = i;
1005 				if (type == TYPE_ALL || type == entry_type) {
1006 					num_ext = ep->dentry.file.num_ext;
1007 					step = DIRENT_STEP_STRM;
1008 				}
1009 				brelse(bh);
1010 				continue;
1011 			}
1012 
1013 			if (entry_type == TYPE_STREAM) {
1014 				u16 name_hash;
1015 
1016 				if (step != DIRENT_STEP_STRM) {
1017 					step = DIRENT_STEP_FILE;
1018 					brelse(bh);
1019 					continue;
1020 				}
1021 				step = DIRENT_STEP_FILE;
1022 				name_hash = le16_to_cpu(
1023 						ep->dentry.stream.name_hash);
1024 				if (p_uniname->name_hash == name_hash &&
1025 				    p_uniname->name_len ==
1026 						ep->dentry.stream.name_len) {
1027 					step = DIRENT_STEP_NAME;
1028 					order = 1;
1029 					name_len = 0;
1030 				}
1031 				brelse(bh);
1032 				continue;
1033 			}
1034 
1035 			brelse(bh);
1036 			if (entry_type == TYPE_EXTEND) {
1037 				unsigned short entry_uniname[16], unichar;
1038 
1039 				if (step != DIRENT_STEP_NAME) {
1040 					step = DIRENT_STEP_FILE;
1041 					continue;
1042 				}
1043 
1044 				if (++order == 2)
1045 					uniname = p_uniname->name;
1046 				else
1047 					uniname += EXFAT_FILE_NAME_LEN;
1048 
1049 				len = exfat_extract_uni_name(ep, entry_uniname);
1050 				name_len += len;
1051 
1052 				unichar = *(uniname+len);
1053 				*(uniname+len) = 0x0;
1054 
1055 				if (exfat_uniname_ncmp(sb, uniname,
1056 					entry_uniname, len)) {
1057 					step = DIRENT_STEP_FILE;
1058 				} else if (p_uniname->name_len == name_len) {
1059 					if (order == num_ext)
1060 						goto found;
1061 					step = DIRENT_STEP_SECD;
1062 				}
1063 
1064 				*(uniname+len) = unichar;
1065 				continue;
1066 			}
1067 
1068 			if (entry_type &
1069 					(TYPE_CRITICAL_SEC | TYPE_BENIGN_SEC)) {
1070 				if (step == DIRENT_STEP_SECD) {
1071 					if (++order == num_ext)
1072 						goto found;
1073 					continue;
1074 				}
1075 			}
1076 			step = DIRENT_STEP_FILE;
1077 		}
1078 
1079 		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
1080 			if (--clu.size > 0)
1081 				clu.dir++;
1082 			else
1083 				clu.dir = EXFAT_EOF_CLUSTER;
1084 		} else {
1085 			if (exfat_get_next_cluster(sb, &clu.dir))
1086 				return -EIO;
1087 		}
1088 	}
1089 
1090 not_found:
1091 	/*
1092 	 * We started at not 0 index,so we should try to find target
1093 	 * from 0 index to the index we started at.
1094 	 */
1095 	if (!rewind && end_eidx) {
1096 		rewind = 1;
1097 		dentry = 0;
1098 		clu.dir = p_dir->dir;
1099 		/* reset empty hint */
1100 		num_empty = 0;
1101 		candi_empty.eidx = EXFAT_HINT_NONE;
1102 		goto rewind;
1103 	}
1104 
1105 	/* initialized hint_stat */
1106 	hint_stat->clu = p_dir->dir;
1107 	hint_stat->eidx = 0;
1108 	return -ENOENT;
1109 
1110 found:
1111 	/* next dentry we'll find is out of this cluster */
1112 	if (!((dentry + 1) & (dentries_per_clu - 1))) {
1113 		int ret = 0;
1114 
1115 		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
1116 			if (--clu.size > 0)
1117 				clu.dir++;
1118 			else
1119 				clu.dir = EXFAT_EOF_CLUSTER;
1120 		} else {
1121 			ret = exfat_get_next_cluster(sb, &clu.dir);
1122 		}
1123 
1124 		if (ret || clu.dir == EXFAT_EOF_CLUSTER) {
1125 			/* just initialized hint_stat */
1126 			hint_stat->clu = p_dir->dir;
1127 			hint_stat->eidx = 0;
1128 			return (dentry - num_ext);
1129 		}
1130 	}
1131 
1132 	hint_stat->clu = clu.dir;
1133 	hint_stat->eidx = dentry + 1;
1134 	return dentry - num_ext;
1135 }
1136 
1137 int exfat_count_ext_entries(struct super_block *sb, struct exfat_chain *p_dir,
1138 		int entry, struct exfat_dentry *ep)
1139 {
1140 	int i, count = 0;
1141 	unsigned int type;
1142 	struct exfat_dentry *ext_ep;
1143 	struct buffer_head *bh;
1144 
1145 	for (i = 0, entry++; i < ep->dentry.file.num_ext; i++, entry++) {
1146 		ext_ep = exfat_get_dentry(sb, p_dir, entry, &bh, NULL);
1147 		if (!ext_ep)
1148 			return -EIO;
1149 
1150 		type = exfat_get_entry_type(ext_ep);
1151 		brelse(bh);
1152 		if (type == TYPE_EXTEND || type == TYPE_STREAM)
1153 			count++;
1154 		else
1155 			break;
1156 	}
1157 	return count;
1158 }
1159 
1160 int exfat_count_dir_entries(struct super_block *sb, struct exfat_chain *p_dir)
1161 {
1162 	int i, count = 0;
1163 	int dentries_per_clu;
1164 	unsigned int entry_type;
1165 	struct exfat_chain clu;
1166 	struct exfat_dentry *ep;
1167 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
1168 	struct buffer_head *bh;
1169 
1170 	dentries_per_clu = sbi->dentries_per_clu;
1171 
1172 	exfat_chain_dup(&clu, p_dir);
1173 
1174 	while (clu.dir != EXFAT_EOF_CLUSTER) {
1175 		for (i = 0; i < dentries_per_clu; i++) {
1176 			ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
1177 			if (!ep)
1178 				return -EIO;
1179 			entry_type = exfat_get_entry_type(ep);
1180 			brelse(bh);
1181 
1182 			if (entry_type == TYPE_UNUSED)
1183 				return count;
1184 			if (entry_type != TYPE_DIR)
1185 				continue;
1186 			count++;
1187 		}
1188 
1189 		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
1190 			if (--clu.size > 0)
1191 				clu.dir++;
1192 			else
1193 				clu.dir = EXFAT_EOF_CLUSTER;
1194 		} else {
1195 			if (exfat_get_next_cluster(sb, &(clu.dir)))
1196 				return -EIO;
1197 		}
1198 	}
1199 
1200 	return count;
1201 }
1202