xref: /linux/fs/f2fs/dir.c (revision 27ffaeb0ab160852c87e2dfa505594020e9a3a06)
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(F2FS_P_SB(dentry_page), !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(F2FS_I_SB(dir), 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 page *page;
288 
289 	page = get_node_page(F2FS_I_SB(inode), inode->i_ino);
290 	if (IS_ERR(page))
291 		return PTR_ERR(page);
292 
293 	init_dent_inode(name, page);
294 	f2fs_put_page(page, 1);
295 
296 	return 0;
297 }
298 
299 static int make_empty_dir(struct inode *inode,
300 		struct inode *parent, struct page *page)
301 {
302 	struct page *dentry_page;
303 	struct f2fs_dentry_block *dentry_blk;
304 	struct f2fs_dir_entry *de;
305 
306 	dentry_page = get_new_data_page(inode, page, 0, true);
307 	if (IS_ERR(dentry_page))
308 		return PTR_ERR(dentry_page);
309 
310 
311 	dentry_blk = kmap_atomic(dentry_page);
312 
313 	de = &dentry_blk->dentry[0];
314 	de->name_len = cpu_to_le16(1);
315 	de->hash_code = 0;
316 	de->ino = cpu_to_le32(inode->i_ino);
317 	memcpy(dentry_blk->filename[0], ".", 1);
318 	set_de_type(de, inode);
319 
320 	de = &dentry_blk->dentry[1];
321 	de->hash_code = 0;
322 	de->name_len = cpu_to_le16(2);
323 	de->ino = cpu_to_le32(parent->i_ino);
324 	memcpy(dentry_blk->filename[1], "..", 2);
325 	set_de_type(de, inode);
326 
327 	test_and_set_bit_le(0, &dentry_blk->dentry_bitmap);
328 	test_and_set_bit_le(1, &dentry_blk->dentry_bitmap);
329 	kunmap_atomic(dentry_blk);
330 
331 	set_page_dirty(dentry_page);
332 	f2fs_put_page(dentry_page, 1);
333 	return 0;
334 }
335 
336 static struct page *init_inode_metadata(struct inode *inode,
337 		struct inode *dir, const struct qstr *name)
338 {
339 	struct page *page;
340 	int err;
341 
342 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
343 		page = new_inode_page(inode);
344 		if (IS_ERR(page))
345 			return page;
346 
347 		if (S_ISDIR(inode->i_mode)) {
348 			err = make_empty_dir(inode, dir, page);
349 			if (err)
350 				goto error;
351 		}
352 
353 		err = f2fs_init_acl(inode, dir, page);
354 		if (err)
355 			goto put_error;
356 
357 		err = f2fs_init_security(inode, dir, name, page);
358 		if (err)
359 			goto put_error;
360 	} else {
361 		page = get_node_page(F2FS_I_SB(dir), inode->i_ino);
362 		if (IS_ERR(page))
363 			return page;
364 
365 		set_cold_node(inode, page);
366 	}
367 
368 	if (name)
369 		init_dent_inode(name, page);
370 
371 	/*
372 	 * This file should be checkpointed during fsync.
373 	 * We lost i_pino from now on.
374 	 */
375 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
376 		file_lost_pino(inode);
377 		/*
378 		 * If link the tmpfile to alias through linkat path,
379 		 * we should remove this inode from orphan list.
380 		 */
381 		if (inode->i_nlink == 0)
382 			remove_orphan_inode(F2FS_I_SB(dir), inode->i_ino);
383 		inc_nlink(inode);
384 	}
385 	return page;
386 
387 put_error:
388 	f2fs_put_page(page, 1);
389 error:
390 	/* once the failed inode becomes a bad inode, i_mode is S_IFREG */
391 	truncate_inode_pages(&inode->i_data, 0);
392 	truncate_blocks(inode, 0, false);
393 	remove_dirty_dir_inode(inode);
394 	remove_inode_page(inode);
395 	return ERR_PTR(err);
396 }
397 
398 static void update_parent_metadata(struct inode *dir, struct inode *inode,
399 						unsigned int current_depth)
400 {
401 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
402 		if (S_ISDIR(inode->i_mode)) {
403 			inc_nlink(dir);
404 			set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
405 		}
406 		clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
407 	}
408 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
409 	mark_inode_dirty(dir);
410 
411 	if (F2FS_I(dir)->i_current_depth != current_depth) {
412 		F2FS_I(dir)->i_current_depth = current_depth;
413 		set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
414 	}
415 
416 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
417 		clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
418 }
419 
420 static int room_for_filename(struct f2fs_dentry_block *dentry_blk, int slots)
421 {
422 	int bit_start = 0;
423 	int zero_start, zero_end;
424 next:
425 	zero_start = find_next_zero_bit_le(&dentry_blk->dentry_bitmap,
426 						NR_DENTRY_IN_BLOCK,
427 						bit_start);
428 	if (zero_start >= NR_DENTRY_IN_BLOCK)
429 		return NR_DENTRY_IN_BLOCK;
430 
431 	zero_end = find_next_bit_le(&dentry_blk->dentry_bitmap,
432 						NR_DENTRY_IN_BLOCK,
433 						zero_start);
434 	if (zero_end - zero_start >= slots)
435 		return zero_start;
436 
437 	bit_start = zero_end + 1;
438 
439 	if (zero_end + 1 >= NR_DENTRY_IN_BLOCK)
440 		return NR_DENTRY_IN_BLOCK;
441 	goto next;
442 }
443 
444 /*
445  * Caller should grab and release a rwsem by calling f2fs_lock_op() and
446  * f2fs_unlock_op().
447  */
448 int __f2fs_add_link(struct inode *dir, const struct qstr *name,
449 						struct inode *inode)
450 {
451 	unsigned int bit_pos;
452 	unsigned int level;
453 	unsigned int current_depth;
454 	unsigned long bidx, block;
455 	f2fs_hash_t dentry_hash;
456 	struct f2fs_dir_entry *de;
457 	unsigned int nbucket, nblock;
458 	size_t namelen = name->len;
459 	struct page *dentry_page = NULL;
460 	struct f2fs_dentry_block *dentry_blk = NULL;
461 	int slots = GET_DENTRY_SLOTS(namelen);
462 	struct page *page;
463 	int err = 0;
464 	int i;
465 
466 	dentry_hash = f2fs_dentry_hash(name);
467 	level = 0;
468 	current_depth = F2FS_I(dir)->i_current_depth;
469 	if (F2FS_I(dir)->chash == dentry_hash) {
470 		level = F2FS_I(dir)->clevel;
471 		F2FS_I(dir)->chash = 0;
472 	}
473 
474 start:
475 	if (unlikely(current_depth == MAX_DIR_HASH_DEPTH))
476 		return -ENOSPC;
477 
478 	/* Increase the depth, if required */
479 	if (level == current_depth)
480 		++current_depth;
481 
482 	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
483 	nblock = bucket_blocks(level);
484 
485 	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
486 				(le32_to_cpu(dentry_hash) % nbucket));
487 
488 	for (block = bidx; block <= (bidx + nblock - 1); block++) {
489 		dentry_page = get_new_data_page(dir, NULL, block, true);
490 		if (IS_ERR(dentry_page))
491 			return PTR_ERR(dentry_page);
492 
493 		dentry_blk = kmap(dentry_page);
494 		bit_pos = room_for_filename(dentry_blk, slots);
495 		if (bit_pos < NR_DENTRY_IN_BLOCK)
496 			goto add_dentry;
497 
498 		kunmap(dentry_page);
499 		f2fs_put_page(dentry_page, 1);
500 	}
501 
502 	/* Move to next level to find the empty slot for new dentry */
503 	++level;
504 	goto start;
505 add_dentry:
506 	f2fs_wait_on_page_writeback(dentry_page, DATA);
507 
508 	down_write(&F2FS_I(inode)->i_sem);
509 	page = init_inode_metadata(inode, dir, name);
510 	if (IS_ERR(page)) {
511 		err = PTR_ERR(page);
512 		goto fail;
513 	}
514 	de = &dentry_blk->dentry[bit_pos];
515 	de->hash_code = dentry_hash;
516 	de->name_len = cpu_to_le16(namelen);
517 	memcpy(dentry_blk->filename[bit_pos], name->name, name->len);
518 	de->ino = cpu_to_le32(inode->i_ino);
519 	set_de_type(de, inode);
520 	for (i = 0; i < slots; i++)
521 		test_and_set_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
522 	set_page_dirty(dentry_page);
523 
524 	/* we don't need to mark_inode_dirty now */
525 	F2FS_I(inode)->i_pino = dir->i_ino;
526 	update_inode(inode, page);
527 	f2fs_put_page(page, 1);
528 
529 	update_parent_metadata(dir, inode, current_depth);
530 fail:
531 	up_write(&F2FS_I(inode)->i_sem);
532 
533 	if (is_inode_flag_set(F2FS_I(dir), FI_UPDATE_DIR)) {
534 		update_inode_page(dir);
535 		clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
536 	}
537 	kunmap(dentry_page);
538 	f2fs_put_page(dentry_page, 1);
539 	return err;
540 }
541 
542 int f2fs_do_tmpfile(struct inode *inode, struct inode *dir)
543 {
544 	struct page *page;
545 	int err = 0;
546 
547 	down_write(&F2FS_I(inode)->i_sem);
548 	page = init_inode_metadata(inode, dir, NULL);
549 	if (IS_ERR(page)) {
550 		err = PTR_ERR(page);
551 		goto fail;
552 	}
553 	/* we don't need to mark_inode_dirty now */
554 	update_inode(inode, page);
555 	f2fs_put_page(page, 1);
556 
557 	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
558 fail:
559 	up_write(&F2FS_I(inode)->i_sem);
560 	return err;
561 }
562 
563 /*
564  * It only removes the dentry from the dentry page, corresponding name
565  * entry in name page does not need to be touched during deletion.
566  */
567 void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
568 						struct inode *inode)
569 {
570 	struct	f2fs_dentry_block *dentry_blk;
571 	unsigned int bit_pos;
572 	struct inode *dir = page->mapping->host;
573 	int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
574 	int i;
575 
576 	lock_page(page);
577 	f2fs_wait_on_page_writeback(page, DATA);
578 
579 	dentry_blk = page_address(page);
580 	bit_pos = dentry - dentry_blk->dentry;
581 	for (i = 0; i < slots; i++)
582 		test_and_clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
583 
584 	/* Let's check and deallocate this dentry page */
585 	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
586 			NR_DENTRY_IN_BLOCK,
587 			0);
588 	kunmap(page); /* kunmap - pair of f2fs_find_entry */
589 	set_page_dirty(page);
590 
591 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
592 
593 	if (inode) {
594 		struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
595 
596 		down_write(&F2FS_I(inode)->i_sem);
597 
598 		if (S_ISDIR(inode->i_mode)) {
599 			drop_nlink(dir);
600 			update_inode_page(dir);
601 		}
602 		inode->i_ctime = CURRENT_TIME;
603 		drop_nlink(inode);
604 		if (S_ISDIR(inode->i_mode)) {
605 			drop_nlink(inode);
606 			i_size_write(inode, 0);
607 		}
608 		up_write(&F2FS_I(inode)->i_sem);
609 		update_inode_page(inode);
610 
611 		if (inode->i_nlink == 0)
612 			add_orphan_inode(sbi, inode->i_ino);
613 		else
614 			release_orphan_inode(sbi);
615 	}
616 
617 	if (bit_pos == NR_DENTRY_IN_BLOCK) {
618 		truncate_hole(dir, page->index, page->index + 1);
619 		clear_page_dirty_for_io(page);
620 		ClearPageUptodate(page);
621 		inode_dec_dirty_pages(dir);
622 	}
623 	f2fs_put_page(page, 1);
624 }
625 
626 bool f2fs_empty_dir(struct inode *dir)
627 {
628 	unsigned long bidx;
629 	struct page *dentry_page;
630 	unsigned int bit_pos;
631 	struct	f2fs_dentry_block *dentry_blk;
632 	unsigned long nblock = dir_blocks(dir);
633 
634 	for (bidx = 0; bidx < nblock; bidx++) {
635 		dentry_page = get_lock_data_page(dir, bidx);
636 		if (IS_ERR(dentry_page)) {
637 			if (PTR_ERR(dentry_page) == -ENOENT)
638 				continue;
639 			else
640 				return false;
641 		}
642 
643 
644 		dentry_blk = kmap_atomic(dentry_page);
645 		if (bidx == 0)
646 			bit_pos = 2;
647 		else
648 			bit_pos = 0;
649 		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
650 						NR_DENTRY_IN_BLOCK,
651 						bit_pos);
652 		kunmap_atomic(dentry_blk);
653 
654 		f2fs_put_page(dentry_page, 1);
655 
656 		if (bit_pos < NR_DENTRY_IN_BLOCK)
657 			return false;
658 	}
659 	return true;
660 }
661 
662 static int f2fs_readdir(struct file *file, struct dir_context *ctx)
663 {
664 	struct inode *inode = file_inode(file);
665 	unsigned long npages = dir_blocks(inode);
666 	unsigned int bit_pos = 0;
667 	struct f2fs_dentry_block *dentry_blk = NULL;
668 	struct f2fs_dir_entry *de = NULL;
669 	struct page *dentry_page = NULL;
670 	struct file_ra_state *ra = &file->f_ra;
671 	unsigned int n = ((unsigned long)ctx->pos / NR_DENTRY_IN_BLOCK);
672 	unsigned char d_type = DT_UNKNOWN;
673 
674 	bit_pos = ((unsigned long)ctx->pos % NR_DENTRY_IN_BLOCK);
675 
676 	/* readahead for multi pages of dir */
677 	if (npages - n > 1 && !ra_has_index(ra, n))
678 		page_cache_sync_readahead(inode->i_mapping, ra, file, n,
679 				min(npages - n, (pgoff_t)MAX_DIR_RA_PAGES));
680 
681 	for (; n < npages; n++) {
682 		dentry_page = get_lock_data_page(inode, n);
683 		if (IS_ERR(dentry_page))
684 			continue;
685 
686 		dentry_blk = kmap(dentry_page);
687 		while (bit_pos < NR_DENTRY_IN_BLOCK) {
688 			bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
689 							NR_DENTRY_IN_BLOCK,
690 							bit_pos);
691 			if (bit_pos >= NR_DENTRY_IN_BLOCK)
692 				break;
693 
694 			de = &dentry_blk->dentry[bit_pos];
695 			if (de->file_type < F2FS_FT_MAX)
696 				d_type = f2fs_filetype_table[de->file_type];
697 			else
698 				d_type = DT_UNKNOWN;
699 			if (!dir_emit(ctx,
700 					dentry_blk->filename[bit_pos],
701 					le16_to_cpu(de->name_len),
702 					le32_to_cpu(de->ino), d_type))
703 				goto stop;
704 
705 			bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
706 			ctx->pos = n * NR_DENTRY_IN_BLOCK + bit_pos;
707 		}
708 		bit_pos = 0;
709 		ctx->pos = (n + 1) * NR_DENTRY_IN_BLOCK;
710 		kunmap(dentry_page);
711 		f2fs_put_page(dentry_page, 1);
712 		dentry_page = NULL;
713 	}
714 stop:
715 	if (dentry_page && !IS_ERR(dentry_page)) {
716 		kunmap(dentry_page);
717 		f2fs_put_page(dentry_page, 1);
718 	}
719 
720 	return 0;
721 }
722 
723 const struct file_operations f2fs_dir_operations = {
724 	.llseek		= generic_file_llseek,
725 	.read		= generic_read_dir,
726 	.iterate	= f2fs_readdir,
727 	.fsync		= f2fs_sync_file,
728 	.unlocked_ioctl	= f2fs_ioctl,
729 };
730