xref: /openbmc/linux/fs/f2fs/dir.c (revision af958a38)
1 /*
2  * fs/f2fs/dir.c
3  *
4  * Copyright (c) 2012 Samsung Electronics Co., Ltd.
5  *             http://www.samsung.com/
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11 #include <linux/fs.h>
12 #include <linux/f2fs_fs.h>
13 #include "f2fs.h"
14 #include "node.h"
15 #include "acl.h"
16 #include "xattr.h"
17 
18 static unsigned long dir_blocks(struct inode *inode)
19 {
20 	return ((unsigned long long) (i_size_read(inode) + PAGE_CACHE_SIZE - 1))
21 							>> PAGE_CACHE_SHIFT;
22 }
23 
24 static unsigned int dir_buckets(unsigned int level, int dir_level)
25 {
26 	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
27 		return 1 << (level + dir_level);
28 	else
29 		return MAX_DIR_BUCKETS;
30 }
31 
32 static unsigned int bucket_blocks(unsigned int level)
33 {
34 	if (level < MAX_DIR_HASH_DEPTH / 2)
35 		return 2;
36 	else
37 		return 4;
38 }
39 
40 static unsigned char f2fs_filetype_table[F2FS_FT_MAX] = {
41 	[F2FS_FT_UNKNOWN]	= DT_UNKNOWN,
42 	[F2FS_FT_REG_FILE]	= DT_REG,
43 	[F2FS_FT_DIR]		= DT_DIR,
44 	[F2FS_FT_CHRDEV]	= DT_CHR,
45 	[F2FS_FT_BLKDEV]	= DT_BLK,
46 	[F2FS_FT_FIFO]		= DT_FIFO,
47 	[F2FS_FT_SOCK]		= DT_SOCK,
48 	[F2FS_FT_SYMLINK]	= DT_LNK,
49 };
50 
51 #define S_SHIFT 12
52 static unsigned char f2fs_type_by_mode[S_IFMT >> S_SHIFT] = {
53 	[S_IFREG >> S_SHIFT]	= F2FS_FT_REG_FILE,
54 	[S_IFDIR >> S_SHIFT]	= F2FS_FT_DIR,
55 	[S_IFCHR >> S_SHIFT]	= F2FS_FT_CHRDEV,
56 	[S_IFBLK >> S_SHIFT]	= F2FS_FT_BLKDEV,
57 	[S_IFIFO >> S_SHIFT]	= F2FS_FT_FIFO,
58 	[S_IFSOCK >> S_SHIFT]	= F2FS_FT_SOCK,
59 	[S_IFLNK >> S_SHIFT]	= F2FS_FT_SYMLINK,
60 };
61 
62 static void set_de_type(struct f2fs_dir_entry *de, struct inode *inode)
63 {
64 	umode_t mode = inode->i_mode;
65 	de->file_type = f2fs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
66 }
67 
68 static unsigned long dir_block_index(unsigned int level,
69 				int dir_level, unsigned int idx)
70 {
71 	unsigned long i;
72 	unsigned long bidx = 0;
73 
74 	for (i = 0; i < level; i++)
75 		bidx += dir_buckets(i, dir_level) * bucket_blocks(i);
76 	bidx += idx * bucket_blocks(level);
77 	return bidx;
78 }
79 
80 static bool early_match_name(size_t namelen, f2fs_hash_t namehash,
81 				struct f2fs_dir_entry *de)
82 {
83 	if (le16_to_cpu(de->name_len) != namelen)
84 		return false;
85 
86 	if (de->hash_code != namehash)
87 		return false;
88 
89 	return true;
90 }
91 
92 static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
93 			struct qstr *name, int *max_slots,
94 			f2fs_hash_t namehash, struct page **res_page)
95 {
96 	struct f2fs_dir_entry *de;
97 	unsigned long bit_pos = 0;
98 	struct f2fs_dentry_block *dentry_blk = kmap(dentry_page);
99 	const void *dentry_bits = &dentry_blk->dentry_bitmap;
100 	int max_len = 0;
101 
102 	while (bit_pos < NR_DENTRY_IN_BLOCK) {
103 		if (!test_bit_le(bit_pos, dentry_bits)) {
104 			if (bit_pos == 0)
105 				max_len = 1;
106 			else if (!test_bit_le(bit_pos - 1, dentry_bits))
107 				max_len++;
108 			bit_pos++;
109 			continue;
110 		}
111 		de = &dentry_blk->dentry[bit_pos];
112 		if (early_match_name(name->len, namehash, de)) {
113 			if (!memcmp(dentry_blk->filename[bit_pos],
114 							name->name,
115 							name->len)) {
116 				*res_page = dentry_page;
117 				goto found;
118 			}
119 		}
120 		if (max_len > *max_slots) {
121 			*max_slots = max_len;
122 			max_len = 0;
123 		}
124 
125 		/*
126 		 * For the most part, it should be a bug when name_len is zero.
127 		 * We stop here for figuring out where the bugs has occurred.
128 		 */
129 		f2fs_bug_on(!de->name_len);
130 
131 		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
132 	}
133 
134 	de = NULL;
135 	kunmap(dentry_page);
136 found:
137 	if (max_len > *max_slots)
138 		*max_slots = max_len;
139 	return de;
140 }
141 
142 static struct f2fs_dir_entry *find_in_level(struct inode *dir,
143 			unsigned int level, struct qstr *name,
144 			f2fs_hash_t namehash, struct page **res_page)
145 {
146 	int s = GET_DENTRY_SLOTS(name->len);
147 	unsigned int nbucket, nblock;
148 	unsigned int bidx, end_block;
149 	struct page *dentry_page;
150 	struct f2fs_dir_entry *de = NULL;
151 	bool room = false;
152 	int max_slots = 0;
153 
154 	f2fs_bug_on(level > MAX_DIR_HASH_DEPTH);
155 
156 	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
157 	nblock = bucket_blocks(level);
158 
159 	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
160 					le32_to_cpu(namehash) % nbucket);
161 	end_block = bidx + nblock;
162 
163 	for (; bidx < end_block; bidx++) {
164 		/* no need to allocate new dentry pages to all the indices */
165 		dentry_page = find_data_page(dir, bidx, true);
166 		if (IS_ERR(dentry_page)) {
167 			room = true;
168 			continue;
169 		}
170 
171 		de = find_in_block(dentry_page, name, &max_slots,
172 					namehash, res_page);
173 		if (de)
174 			break;
175 
176 		if (max_slots >= s)
177 			room = true;
178 		f2fs_put_page(dentry_page, 0);
179 	}
180 
181 	if (!de && room && F2FS_I(dir)->chash != namehash) {
182 		F2FS_I(dir)->chash = namehash;
183 		F2FS_I(dir)->clevel = level;
184 	}
185 
186 	return de;
187 }
188 
189 /*
190  * Find an entry in the specified directory with the wanted name.
191  * It returns the page where the entry was found (as a parameter - res_page),
192  * and the entry itself. Page is returned mapped and unlocked.
193  * Entry is guaranteed to be valid.
194  */
195 struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
196 			struct qstr *child, struct page **res_page)
197 {
198 	unsigned long npages = dir_blocks(dir);
199 	struct f2fs_dir_entry *de = NULL;
200 	f2fs_hash_t name_hash;
201 	unsigned int max_depth;
202 	unsigned int level;
203 
204 	if (npages == 0)
205 		return NULL;
206 
207 	*res_page = NULL;
208 
209 	name_hash = f2fs_dentry_hash(child);
210 	max_depth = F2FS_I(dir)->i_current_depth;
211 
212 	for (level = 0; level < max_depth; level++) {
213 		de = find_in_level(dir, level, child, name_hash, res_page);
214 		if (de)
215 			break;
216 	}
217 	if (!de && F2FS_I(dir)->chash != name_hash) {
218 		F2FS_I(dir)->chash = name_hash;
219 		F2FS_I(dir)->clevel = level - 1;
220 	}
221 	return de;
222 }
223 
224 struct f2fs_dir_entry *f2fs_parent_dir(struct inode *dir, struct page **p)
225 {
226 	struct page *page;
227 	struct f2fs_dir_entry *de;
228 	struct f2fs_dentry_block *dentry_blk;
229 
230 	page = get_lock_data_page(dir, 0);
231 	if (IS_ERR(page))
232 		return NULL;
233 
234 	dentry_blk = kmap(page);
235 	de = &dentry_blk->dentry[1];
236 	*p = page;
237 	unlock_page(page);
238 	return de;
239 }
240 
241 ino_t f2fs_inode_by_name(struct inode *dir, struct qstr *qstr)
242 {
243 	ino_t res = 0;
244 	struct f2fs_dir_entry *de;
245 	struct page *page;
246 
247 	de = f2fs_find_entry(dir, qstr, &page);
248 	if (de) {
249 		res = le32_to_cpu(de->ino);
250 		kunmap(page);
251 		f2fs_put_page(page, 0);
252 	}
253 
254 	return res;
255 }
256 
257 void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
258 		struct page *page, struct inode *inode)
259 {
260 	lock_page(page);
261 	f2fs_wait_on_page_writeback(page, DATA);
262 	de->ino = cpu_to_le32(inode->i_ino);
263 	set_de_type(de, inode);
264 	kunmap(page);
265 	set_page_dirty(page);
266 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
267 	mark_inode_dirty(dir);
268 
269 	f2fs_put_page(page, 1);
270 }
271 
272 static void init_dent_inode(const struct qstr *name, struct page *ipage)
273 {
274 	struct f2fs_inode *ri;
275 
276 	f2fs_wait_on_page_writeback(ipage, NODE);
277 
278 	/* copy name info. to this inode page */
279 	ri = F2FS_INODE(ipage);
280 	ri->i_namelen = cpu_to_le32(name->len);
281 	memcpy(ri->i_name, name->name, name->len);
282 	set_page_dirty(ipage);
283 }
284 
285 int update_dent_inode(struct inode *inode, const struct qstr *name)
286 {
287 	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
288 	struct page *page;
289 
290 	page = get_node_page(sbi, inode->i_ino);
291 	if (IS_ERR(page))
292 		return PTR_ERR(page);
293 
294 	init_dent_inode(name, page);
295 	f2fs_put_page(page, 1);
296 
297 	return 0;
298 }
299 
300 static int make_empty_dir(struct inode *inode,
301 		struct inode *parent, struct page *page)
302 {
303 	struct page *dentry_page;
304 	struct f2fs_dentry_block *dentry_blk;
305 	struct f2fs_dir_entry *de;
306 
307 	dentry_page = get_new_data_page(inode, page, 0, true);
308 	if (IS_ERR(dentry_page))
309 		return PTR_ERR(dentry_page);
310 
311 
312 	dentry_blk = kmap_atomic(dentry_page);
313 
314 	de = &dentry_blk->dentry[0];
315 	de->name_len = cpu_to_le16(1);
316 	de->hash_code = 0;
317 	de->ino = cpu_to_le32(inode->i_ino);
318 	memcpy(dentry_blk->filename[0], ".", 1);
319 	set_de_type(de, inode);
320 
321 	de = &dentry_blk->dentry[1];
322 	de->hash_code = 0;
323 	de->name_len = cpu_to_le16(2);
324 	de->ino = cpu_to_le32(parent->i_ino);
325 	memcpy(dentry_blk->filename[1], "..", 2);
326 	set_de_type(de, inode);
327 
328 	test_and_set_bit_le(0, &dentry_blk->dentry_bitmap);
329 	test_and_set_bit_le(1, &dentry_blk->dentry_bitmap);
330 	kunmap_atomic(dentry_blk);
331 
332 	set_page_dirty(dentry_page);
333 	f2fs_put_page(dentry_page, 1);
334 	return 0;
335 }
336 
337 static struct page *init_inode_metadata(struct inode *inode,
338 		struct inode *dir, const struct qstr *name)
339 {
340 	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
341 	struct page *page;
342 	int err;
343 
344 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
345 		page = new_inode_page(inode);
346 		if (IS_ERR(page))
347 			return page;
348 
349 		if (S_ISDIR(inode->i_mode)) {
350 			err = make_empty_dir(inode, dir, page);
351 			if (err)
352 				goto error;
353 		}
354 
355 		err = f2fs_init_acl(inode, dir, page);
356 		if (err)
357 			goto put_error;
358 
359 		err = f2fs_init_security(inode, dir, name, page);
360 		if (err)
361 			goto put_error;
362 	} else {
363 		page = get_node_page(F2FS_SB(dir->i_sb), inode->i_ino);
364 		if (IS_ERR(page))
365 			return page;
366 
367 		set_cold_node(inode, page);
368 	}
369 
370 	if (name)
371 		init_dent_inode(name, page);
372 
373 	/*
374 	 * This file should be checkpointed during fsync.
375 	 * We lost i_pino from now on.
376 	 */
377 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
378 		file_lost_pino(inode);
379 		/*
380 		 * If link the tmpfile to alias through linkat path,
381 		 * we should remove this inode from orphan list.
382 		 */
383 		if (inode->i_nlink == 0)
384 			remove_orphan_inode(sbi, inode->i_ino);
385 		inc_nlink(inode);
386 	}
387 	return page;
388 
389 put_error:
390 	f2fs_put_page(page, 1);
391 error:
392 	/* once the failed inode becomes a bad inode, i_mode is S_IFREG */
393 	truncate_inode_pages(&inode->i_data, 0);
394 	truncate_blocks(inode, 0, false);
395 	remove_dirty_dir_inode(inode);
396 	remove_inode_page(inode);
397 	return ERR_PTR(err);
398 }
399 
400 static void update_parent_metadata(struct inode *dir, struct inode *inode,
401 						unsigned int current_depth)
402 {
403 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
404 		if (S_ISDIR(inode->i_mode)) {
405 			inc_nlink(dir);
406 			set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
407 		}
408 		clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
409 	}
410 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
411 	mark_inode_dirty(dir);
412 
413 	if (F2FS_I(dir)->i_current_depth != current_depth) {
414 		F2FS_I(dir)->i_current_depth = current_depth;
415 		set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
416 	}
417 
418 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
419 		clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
420 }
421 
422 static int room_for_filename(struct f2fs_dentry_block *dentry_blk, int slots)
423 {
424 	int bit_start = 0;
425 	int zero_start, zero_end;
426 next:
427 	zero_start = find_next_zero_bit_le(&dentry_blk->dentry_bitmap,
428 						NR_DENTRY_IN_BLOCK,
429 						bit_start);
430 	if (zero_start >= NR_DENTRY_IN_BLOCK)
431 		return NR_DENTRY_IN_BLOCK;
432 
433 	zero_end = find_next_bit_le(&dentry_blk->dentry_bitmap,
434 						NR_DENTRY_IN_BLOCK,
435 						zero_start);
436 	if (zero_end - zero_start >= slots)
437 		return zero_start;
438 
439 	bit_start = zero_end + 1;
440 
441 	if (zero_end + 1 >= NR_DENTRY_IN_BLOCK)
442 		return NR_DENTRY_IN_BLOCK;
443 	goto next;
444 }
445 
446 /*
447  * Caller should grab and release a rwsem by calling f2fs_lock_op() and
448  * f2fs_unlock_op().
449  */
450 int __f2fs_add_link(struct inode *dir, const struct qstr *name,
451 						struct inode *inode)
452 {
453 	unsigned int bit_pos;
454 	unsigned int level;
455 	unsigned int current_depth;
456 	unsigned long bidx, block;
457 	f2fs_hash_t dentry_hash;
458 	struct f2fs_dir_entry *de;
459 	unsigned int nbucket, nblock;
460 	size_t namelen = name->len;
461 	struct page *dentry_page = NULL;
462 	struct f2fs_dentry_block *dentry_blk = NULL;
463 	int slots = GET_DENTRY_SLOTS(namelen);
464 	struct page *page;
465 	int err = 0;
466 	int i;
467 
468 	dentry_hash = f2fs_dentry_hash(name);
469 	level = 0;
470 	current_depth = F2FS_I(dir)->i_current_depth;
471 	if (F2FS_I(dir)->chash == dentry_hash) {
472 		level = F2FS_I(dir)->clevel;
473 		F2FS_I(dir)->chash = 0;
474 	}
475 
476 start:
477 	if (unlikely(current_depth == MAX_DIR_HASH_DEPTH))
478 		return -ENOSPC;
479 
480 	/* Increase the depth, if required */
481 	if (level == current_depth)
482 		++current_depth;
483 
484 	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
485 	nblock = bucket_blocks(level);
486 
487 	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
488 				(le32_to_cpu(dentry_hash) % nbucket));
489 
490 	for (block = bidx; block <= (bidx + nblock - 1); block++) {
491 		dentry_page = get_new_data_page(dir, NULL, block, true);
492 		if (IS_ERR(dentry_page))
493 			return PTR_ERR(dentry_page);
494 
495 		dentry_blk = kmap(dentry_page);
496 		bit_pos = room_for_filename(dentry_blk, slots);
497 		if (bit_pos < NR_DENTRY_IN_BLOCK)
498 			goto add_dentry;
499 
500 		kunmap(dentry_page);
501 		f2fs_put_page(dentry_page, 1);
502 	}
503 
504 	/* Move to next level to find the empty slot for new dentry */
505 	++level;
506 	goto start;
507 add_dentry:
508 	f2fs_wait_on_page_writeback(dentry_page, DATA);
509 
510 	down_write(&F2FS_I(inode)->i_sem);
511 	page = init_inode_metadata(inode, dir, name);
512 	if (IS_ERR(page)) {
513 		err = PTR_ERR(page);
514 		goto fail;
515 	}
516 	de = &dentry_blk->dentry[bit_pos];
517 	de->hash_code = dentry_hash;
518 	de->name_len = cpu_to_le16(namelen);
519 	memcpy(dentry_blk->filename[bit_pos], name->name, name->len);
520 	de->ino = cpu_to_le32(inode->i_ino);
521 	set_de_type(de, inode);
522 	for (i = 0; i < slots; i++)
523 		test_and_set_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
524 	set_page_dirty(dentry_page);
525 
526 	/* we don't need to mark_inode_dirty now */
527 	F2FS_I(inode)->i_pino = dir->i_ino;
528 	update_inode(inode, page);
529 	f2fs_put_page(page, 1);
530 
531 	update_parent_metadata(dir, inode, current_depth);
532 fail:
533 	up_write(&F2FS_I(inode)->i_sem);
534 
535 	if (is_inode_flag_set(F2FS_I(dir), FI_UPDATE_DIR)) {
536 		update_inode_page(dir);
537 		clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
538 	}
539 	kunmap(dentry_page);
540 	f2fs_put_page(dentry_page, 1);
541 	return err;
542 }
543 
544 int f2fs_do_tmpfile(struct inode *inode, struct inode *dir)
545 {
546 	struct page *page;
547 	int err = 0;
548 
549 	down_write(&F2FS_I(inode)->i_sem);
550 	page = init_inode_metadata(inode, dir, NULL);
551 	if (IS_ERR(page)) {
552 		err = PTR_ERR(page);
553 		goto fail;
554 	}
555 	/* we don't need to mark_inode_dirty now */
556 	update_inode(inode, page);
557 	f2fs_put_page(page, 1);
558 
559 	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
560 fail:
561 	up_write(&F2FS_I(inode)->i_sem);
562 	return err;
563 }
564 
565 /*
566  * It only removes the dentry from the dentry page, corresponding name
567  * entry in name page does not need to be touched during deletion.
568  */
569 void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
570 						struct inode *inode)
571 {
572 	struct	f2fs_dentry_block *dentry_blk;
573 	unsigned int bit_pos;
574 	struct address_space *mapping = page->mapping;
575 	struct inode *dir = mapping->host;
576 	int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
577 	int i;
578 
579 	lock_page(page);
580 	f2fs_wait_on_page_writeback(page, DATA);
581 
582 	dentry_blk = page_address(page);
583 	bit_pos = dentry - dentry_blk->dentry;
584 	for (i = 0; i < slots; i++)
585 		test_and_clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
586 
587 	/* Let's check and deallocate this dentry page */
588 	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
589 			NR_DENTRY_IN_BLOCK,
590 			0);
591 	kunmap(page); /* kunmap - pair of f2fs_find_entry */
592 	set_page_dirty(page);
593 
594 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
595 
596 	if (inode) {
597 		struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
598 
599 		down_write(&F2FS_I(inode)->i_sem);
600 
601 		if (S_ISDIR(inode->i_mode)) {
602 			drop_nlink(dir);
603 			update_inode_page(dir);
604 		}
605 		inode->i_ctime = CURRENT_TIME;
606 		drop_nlink(inode);
607 		if (S_ISDIR(inode->i_mode)) {
608 			drop_nlink(inode);
609 			i_size_write(inode, 0);
610 		}
611 		up_write(&F2FS_I(inode)->i_sem);
612 		update_inode_page(inode);
613 
614 		if (inode->i_nlink == 0)
615 			add_orphan_inode(sbi, inode->i_ino);
616 		else
617 			release_orphan_inode(sbi);
618 	}
619 
620 	if (bit_pos == NR_DENTRY_IN_BLOCK) {
621 		truncate_hole(dir, page->index, page->index + 1);
622 		clear_page_dirty_for_io(page);
623 		ClearPageUptodate(page);
624 		inode_dec_dirty_dents(dir);
625 	}
626 	f2fs_put_page(page, 1);
627 }
628 
629 bool f2fs_empty_dir(struct inode *dir)
630 {
631 	unsigned long bidx;
632 	struct page *dentry_page;
633 	unsigned int bit_pos;
634 	struct	f2fs_dentry_block *dentry_blk;
635 	unsigned long nblock = dir_blocks(dir);
636 
637 	for (bidx = 0; bidx < nblock; bidx++) {
638 		dentry_page = get_lock_data_page(dir, bidx);
639 		if (IS_ERR(dentry_page)) {
640 			if (PTR_ERR(dentry_page) == -ENOENT)
641 				continue;
642 			else
643 				return false;
644 		}
645 
646 
647 		dentry_blk = kmap_atomic(dentry_page);
648 		if (bidx == 0)
649 			bit_pos = 2;
650 		else
651 			bit_pos = 0;
652 		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
653 						NR_DENTRY_IN_BLOCK,
654 						bit_pos);
655 		kunmap_atomic(dentry_blk);
656 
657 		f2fs_put_page(dentry_page, 1);
658 
659 		if (bit_pos < NR_DENTRY_IN_BLOCK)
660 			return false;
661 	}
662 	return true;
663 }
664 
665 static int f2fs_readdir(struct file *file, struct dir_context *ctx)
666 {
667 	struct inode *inode = file_inode(file);
668 	unsigned long npages = dir_blocks(inode);
669 	unsigned int bit_pos = 0;
670 	struct f2fs_dentry_block *dentry_blk = NULL;
671 	struct f2fs_dir_entry *de = NULL;
672 	struct page *dentry_page = NULL;
673 	struct file_ra_state *ra = &file->f_ra;
674 	unsigned int n = ((unsigned long)ctx->pos / NR_DENTRY_IN_BLOCK);
675 	unsigned char d_type = DT_UNKNOWN;
676 
677 	bit_pos = ((unsigned long)ctx->pos % NR_DENTRY_IN_BLOCK);
678 
679 	/* readahead for multi pages of dir */
680 	if (npages - n > 1 && !ra_has_index(ra, n))
681 		page_cache_sync_readahead(inode->i_mapping, ra, file, n,
682 				min(npages - n, (pgoff_t)MAX_DIR_RA_PAGES));
683 
684 	for (; n < npages; n++) {
685 		dentry_page = get_lock_data_page(inode, n);
686 		if (IS_ERR(dentry_page))
687 			continue;
688 
689 		dentry_blk = kmap(dentry_page);
690 		while (bit_pos < NR_DENTRY_IN_BLOCK) {
691 			bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
692 							NR_DENTRY_IN_BLOCK,
693 							bit_pos);
694 			if (bit_pos >= NR_DENTRY_IN_BLOCK)
695 				break;
696 
697 			de = &dentry_blk->dentry[bit_pos];
698 			if (de->file_type < F2FS_FT_MAX)
699 				d_type = f2fs_filetype_table[de->file_type];
700 			else
701 				d_type = DT_UNKNOWN;
702 			if (!dir_emit(ctx,
703 					dentry_blk->filename[bit_pos],
704 					le16_to_cpu(de->name_len),
705 					le32_to_cpu(de->ino), d_type))
706 				goto stop;
707 
708 			bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
709 			ctx->pos = n * NR_DENTRY_IN_BLOCK + bit_pos;
710 		}
711 		bit_pos = 0;
712 		ctx->pos = (n + 1) * NR_DENTRY_IN_BLOCK;
713 		kunmap(dentry_page);
714 		f2fs_put_page(dentry_page, 1);
715 		dentry_page = NULL;
716 	}
717 stop:
718 	if (dentry_page && !IS_ERR(dentry_page)) {
719 		kunmap(dentry_page);
720 		f2fs_put_page(dentry_page, 1);
721 	}
722 
723 	return 0;
724 }
725 
726 const struct file_operations f2fs_dir_operations = {
727 	.llseek		= generic_file_llseek,
728 	.read		= generic_read_dir,
729 	.iterate	= f2fs_readdir,
730 	.fsync		= f2fs_sync_file,
731 	.unlocked_ioctl	= f2fs_ioctl,
732 };
733