fs/f2fs/dir.c - linux - Git at Google

 /*
  * fs/f2fs/dir.c
  *
  * Copyright (c) 2012 Samsung Electronics Co., Ltd.
  *             http://www.samsung.com/
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/fs.h>
 #include <linux/f2fs_fs.h>
 #include "f2fs.h"
 #include "node.h"
 #include "acl.h"
 #include "xattr.h"

 static unsigned long dir_blocks(struct inode *inode)
 {
 	return ((unsigned long long) (i_size_read(inode) + PAGE_CACHE_SIZE - 1))
 							>> PAGE_CACHE_SHIFT;
 }

 static unsigned int dir_buckets(unsigned int level, int dir_level)
 {
 	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
 		return 1 << (level + dir_level);
 	else
 		return MAX_DIR_BUCKETS;
 }

 static unsigned int bucket_blocks(unsigned int level)
 {
 	if (level < MAX_DIR_HASH_DEPTH / 2)
 		return 2;
 	else
 		return 4;
 }

 unsigned char f2fs_filetype_table[F2FS_FT_MAX] = {
 	[F2FS_FT_UNKNOWN]	= DT_UNKNOWN,
 	[F2FS_FT_REG_FILE]	= DT_REG,
 	[F2FS_FT_DIR]		= DT_DIR,
 	[F2FS_FT_CHRDEV]	= DT_CHR,
 	[F2FS_FT_BLKDEV]	= DT_BLK,
 	[F2FS_FT_FIFO]		= DT_FIFO,
 	[F2FS_FT_SOCK]		= DT_SOCK,
 	[F2FS_FT_SYMLINK]	= DT_LNK,
 };

 #define S_SHIFT 12
 static unsigned char f2fs_type_by_mode[S_IFMT >> S_SHIFT] = {
 	[S_IFREG >> S_SHIFT]	= F2FS_FT_REG_FILE,
 	[S_IFDIR >> S_SHIFT]	= F2FS_FT_DIR,
 	[S_IFCHR >> S_SHIFT]	= F2FS_FT_CHRDEV,
 	[S_IFBLK >> S_SHIFT]	= F2FS_FT_BLKDEV,
 	[S_IFIFO >> S_SHIFT]	= F2FS_FT_FIFO,
 	[S_IFSOCK >> S_SHIFT]	= F2FS_FT_SOCK,
 	[S_IFLNK >> S_SHIFT]	= F2FS_FT_SYMLINK,
 };

 void set_de_type(struct f2fs_dir_entry *de, struct inode *inode)
 {
 	umode_t mode = inode->i_mode;
 	de->file_type = f2fs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
 }

 static unsigned long dir_block_index(unsigned int level,
 				int dir_level, unsigned int idx)
 {
 	unsigned long i;
 	unsigned long bidx = 0;

 	for (i = 0; i < level; i++)
 		bidx += dir_buckets(i, dir_level) * bucket_blocks(i);
 	bidx += idx * bucket_blocks(level);
 	return bidx;
 }

 static bool early_match_name(size_t namelen, f2fs_hash_t namehash,
 				struct f2fs_dir_entry *de)
 {
 	if (le16_to_cpu(de->name_len) != namelen)
 		return false;

 	if (de->hash_code != namehash)
 		return false;

 	return true;
 }

 static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
 				struct qstr *name, int *max_slots,
 				struct page **res_page)
 {
 	struct f2fs_dentry_block *dentry_blk;
 	struct f2fs_dir_entry *de;
 	struct f2fs_dentry_ptr d;

 	dentry_blk = (struct f2fs_dentry_block *)kmap(dentry_page);

 	make_dentry_ptr(&d, (void *)dentry_blk, 1);
 	de = find_target_dentry(name, max_slots, &d);

 	if (de)
 		*res_page = dentry_page;
 	else
 		kunmap(dentry_page);

 	/*
 	 * For the most part, it should be a bug when name_len is zero.
 	 * We stop here for figuring out where the bugs has occurred.
 	 */
 	f2fs_bug_on(F2FS_P_SB(dentry_page), d.max < 0);
 	return de;
 }

 struct f2fs_dir_entry *find_target_dentry(struct qstr *name, int *max_slots,
 						struct f2fs_dentry_ptr *d)
 {
 	struct f2fs_dir_entry *de;
 	unsigned long bit_pos = 0;
 	f2fs_hash_t namehash = f2fs_dentry_hash(name);
 	int max_len = 0;

 	if (max_slots)
 		*max_slots = 0;
 	while (bit_pos < d->max) {
 		if (!test_bit_le(bit_pos, d->bitmap)) {
 			if (bit_pos == 0)
 				max_len = 1;
 			else if (!test_bit_le(bit_pos - 1, d->bitmap))
 				max_len++;
 			bit_pos++;
 			continue;
 		}
 		de = &d->dentry[bit_pos];
 		if (early_match_name(name->len, namehash, de) &&
 			!memcmp(d->filename[bit_pos], name->name, name->len))
 			goto found;

 		if (max_slots && *max_slots >= 0 && max_len > *max_slots) {
 			*max_slots = max_len;
 			max_len = 0;
 		}

 		/* remain bug on condition */
 		if (unlikely(!de->name_len))
 			d->max = -1;

 		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
 	}

 	de = NULL;
 found:
 	if (max_slots && max_len > *max_slots)
 		*max_slots = max_len;
 	return de;
 }

 static struct f2fs_dir_entry *find_in_level(struct inode *dir,
 			unsigned int level, struct qstr *name,
 			f2fs_hash_t namehash, struct page **res_page)
 {
 	int s = GET_DENTRY_SLOTS(name->len);
 	unsigned int nbucket, nblock;
 	unsigned int bidx, end_block;
 	struct page *dentry_page;
 	struct f2fs_dir_entry *de = NULL;
 	bool room = false;
 	int max_slots;

 	f2fs_bug_on(F2FS_I_SB(dir), level > MAX_DIR_HASH_DEPTH);

 	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
 	nblock = bucket_blocks(level);

 	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
 					le32_to_cpu(namehash) % nbucket);
 	end_block = bidx + nblock;

 	for (; bidx < end_block; bidx++) {
 		/* no need to allocate new dentry pages to all the indices */
 		dentry_page = find_data_page(dir, bidx, true);
 		if (IS_ERR(dentry_page)) {
 			room = true;
 			continue;
 		}

 		de = find_in_block(dentry_page, name, &max_slots, res_page);
 		if (de)
 			break;

 		if (max_slots >= s)
 			room = true;
 		f2fs_put_page(dentry_page, 0);
 	}

 	if (!de && room && F2FS_I(dir)->chash != namehash) {
 		F2FS_I(dir)->chash = namehash;
 		F2FS_I(dir)->clevel = level;
 	}

 	return de;
 }

 /*
  * Find an entry in the specified directory with the wanted name.
  * It returns the page where the entry was found (as a parameter - res_page),
  * and the entry itself. Page is returned mapped and unlocked.
  * Entry is guaranteed to be valid.
  */
 struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
 			struct qstr *child, struct page **res_page)
 {
 	unsigned long npages = dir_blocks(dir);
 	struct f2fs_dir_entry *de = NULL;
 	f2fs_hash_t name_hash;
 	unsigned int max_depth;
 	unsigned int level;

 	if (f2fs_has_inline_dentry(dir))
 		return find_in_inline_dir(dir, child, res_page);

 	if (npages == 0)
 		return NULL;

 	*res_page = NULL;

 	name_hash = f2fs_dentry_hash(child);
 	max_depth = F2FS_I(dir)->i_current_depth;

 	for (level = 0; level < max_depth; level++) {
 		de = find_in_level(dir, level, child, name_hash, res_page);
 		if (de)
 			break;
 	}
 	if (!de && F2FS_I(dir)->chash != name_hash) {
 		F2FS_I(dir)->chash = name_hash;
 		F2FS_I(dir)->clevel = level - 1;
 	}
 	return de;
 }

 struct f2fs_dir_entry *f2fs_parent_dir(struct inode *dir, struct page **p)
 {
 	struct page *page;
 	struct f2fs_dir_entry *de;
 	struct f2fs_dentry_block *dentry_blk;

 	if (f2fs_has_inline_dentry(dir))
 		return f2fs_parent_inline_dir(dir, p);

 	page = get_lock_data_page(dir, 0);
 	if (IS_ERR(page))
 		return NULL;

 	dentry_blk = kmap(page);
 	de = &dentry_blk->dentry[1];
 	*p = page;
 	unlock_page(page);
 	return de;
 }

 ino_t f2fs_inode_by_name(struct inode *dir, struct qstr *qstr)
 {
 	ino_t res = 0;
 	struct f2fs_dir_entry *de;
 	struct page *page;

 	de = f2fs_find_entry(dir, qstr, &page);
 	if (de) {
 		res = le32_to_cpu(de->ino);
 		f2fs_dentry_kunmap(dir, page);
 		f2fs_put_page(page, 0);
 	}

 	return res;
 }

 void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
 		struct page *page, struct inode *inode)
 {
 	enum page_type type = f2fs_has_inline_dentry(dir) ? NODE : DATA;
 	lock_page(page);
 	f2fs_wait_on_page_writeback(page, type);
 	de->ino = cpu_to_le32(inode->i_ino);
 	set_de_type(de, inode);
 	f2fs_dentry_kunmap(dir, page);
 	set_page_dirty(page);
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 	mark_inode_dirty(dir);

 	f2fs_put_page(page, 1);
 }

 static void init_dent_inode(const struct qstr *name, struct page *ipage)
 {
 	struct f2fs_inode *ri;

 	f2fs_wait_on_page_writeback(ipage, NODE);

 	/* copy name info. to this inode page */
 	ri = F2FS_INODE(ipage);
 	ri->i_namelen = cpu_to_le32(name->len);
 	memcpy(ri->i_name, name->name, name->len);
 	set_page_dirty(ipage);
 }

 int update_dent_inode(struct inode *inode, const struct qstr *name)
 {
 	struct page *page;

 	page = get_node_page(F2FS_I_SB(inode), inode->i_ino);
 	if (IS_ERR(page))
 		return PTR_ERR(page);

 	init_dent_inode(name, page);
 	f2fs_put_page(page, 1);

 	return 0;
 }

 void do_make_empty_dir(struct inode *inode, struct inode *parent,
 					struct f2fs_dentry_ptr *d)
 {
 	struct f2fs_dir_entry *de;

 	de = &d->dentry[0];
 	de->name_len = cpu_to_le16(1);
 	de->hash_code = 0;
 	de->ino = cpu_to_le32(inode->i_ino);
 	memcpy(d->filename[0], ".", 1);
 	set_de_type(de, inode);

 	de = &d->dentry[1];
 	de->hash_code = 0;
 	de->name_len = cpu_to_le16(2);
 	de->ino = cpu_to_le32(parent->i_ino);
 	memcpy(d->filename[1], "..", 2);
 	set_de_type(de, inode);

 	test_and_set_bit_le(0, (void *)d->bitmap);
 	test_and_set_bit_le(1, (void *)d->bitmap);
 }

 static int make_empty_dir(struct inode *inode,
 		struct inode *parent, struct page *page)
 {
 	struct page *dentry_page;
 	struct f2fs_dentry_block *dentry_blk;
 	struct f2fs_dentry_ptr d;

 	if (f2fs_has_inline_dentry(inode))
 		return make_empty_inline_dir(inode, parent, page);

 	dentry_page = get_new_data_page(inode, page, 0, true);
 	if (IS_ERR(dentry_page))
 		return PTR_ERR(dentry_page);

 	dentry_blk = kmap_atomic(dentry_page);

 	make_dentry_ptr(&d, (void *)dentry_blk, 1);
 	do_make_empty_dir(inode, parent, &d);

 	kunmap_atomic(dentry_blk);

 	set_page_dirty(dentry_page);
 	f2fs_put_page(dentry_page, 1);
 	return 0;
 }

 struct page *init_inode_metadata(struct inode *inode, struct inode *dir,
 			const struct qstr *name, struct page *dpage)
 {
 	struct page *page;
 	int err;

 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
 		page = new_inode_page(inode);
 		if (IS_ERR(page))
 			return page;

 		if (S_ISDIR(inode->i_mode)) {
 			err = make_empty_dir(inode, dir, page);
 			if (err)
 				goto error;
 		}

 		err = f2fs_init_acl(inode, dir, page, dpage);
 		if (err)
 			goto put_error;

 		err = f2fs_init_security(inode, dir, name, page);
 		if (err)
 			goto put_error;
 	} else {
 		page = get_node_page(F2FS_I_SB(dir), inode->i_ino);
 		if (IS_ERR(page))
 			return page;

 		set_cold_node(inode, page);
 	}

 	if (name)
 		init_dent_inode(name, page);

 	/*
 	 * This file should be checkpointed during fsync.
 	 * We lost i_pino from now on.
 	 */
 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
 		file_lost_pino(inode);
 		/*
 		 * If link the tmpfile to alias through linkat path,
 		 * we should remove this inode from orphan list.
 		 */
 		if (inode->i_nlink == 0)
 			remove_orphan_inode(F2FS_I_SB(dir), inode->i_ino);
 		inc_nlink(inode);
 	}
 	return page;

 put_error:
 	f2fs_put_page(page, 1);
 error:
 	/* once the failed inode becomes a bad inode, i_mode is S_IFREG */
 	truncate_inode_pages(&inode->i_data, 0);
 	truncate_blocks(inode, 0, false);
 	remove_dirty_dir_inode(inode);
 	remove_inode_page(inode);
 	return ERR_PTR(err);
 }

 void update_parent_metadata(struct inode *dir, struct inode *inode,
 						unsigned int current_depth)
 {
 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
 		if (S_ISDIR(inode->i_mode)) {
 			inc_nlink(dir);
 			set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
 		}
 		clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
 	}
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 	mark_inode_dirty(dir);

 	if (F2FS_I(dir)->i_current_depth != current_depth) {
 		F2FS_I(dir)->i_current_depth = current_depth;
 		set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
 	}

 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
 		clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
 }

 int room_for_filename(const void *bitmap, int slots, int max_slots)
 {
 	int bit_start = 0;
 	int zero_start, zero_end;
 next:
 	zero_start = find_next_zero_bit_le(bitmap, max_slots, bit_start);
 	if (zero_start >= max_slots)
 		return max_slots;

 	zero_end = find_next_bit_le(bitmap, max_slots, zero_start);
 	if (zero_end - zero_start >= slots)
 		return zero_start;

 	bit_start = zero_end + 1;

 	if (zero_end + 1 >= max_slots)
 		return max_slots;
 	goto next;
 }

 /*
  * Caller should grab and release a rwsem by calling f2fs_lock_op() and
  * f2fs_unlock_op().
  */
 int __f2fs_add_link(struct inode *dir, const struct qstr *name,
 						struct inode *inode)
 {
 	unsigned int bit_pos;
 	unsigned int level;
 	unsigned int current_depth;
 	unsigned long bidx, block;
 	f2fs_hash_t dentry_hash;
 	struct f2fs_dir_entry *de;
 	unsigned int nbucket, nblock;
 	size_t namelen = name->len;
 	struct page *dentry_page = NULL;
 	struct f2fs_dentry_block *dentry_blk = NULL;
 	int slots = GET_DENTRY_SLOTS(namelen);
 	struct page *page;
 	int err = 0;
 	int i;

 	if (f2fs_has_inline_dentry(dir)) {
 		err = f2fs_add_inline_entry(dir, name, inode);
 		if (!err || err != -EAGAIN)
 			return err;
 		else
 			err = 0;
 	}

 	dentry_hash = f2fs_dentry_hash(name);
 	level = 0;
 	current_depth = F2FS_I(dir)->i_current_depth;
 	if (F2FS_I(dir)->chash == dentry_hash) {
 		level = F2FS_I(dir)->clevel;
 		F2FS_I(dir)->chash = 0;
 	}

 start:
 	if (unlikely(current_depth == MAX_DIR_HASH_DEPTH))
 		return -ENOSPC;

 	/* Increase the depth, if required */
 	if (level == current_depth)
 		++current_depth;

 	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
 	nblock = bucket_blocks(level);

 	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
 				(le32_to_cpu(dentry_hash) % nbucket));

 	for (block = bidx; block <= (bidx + nblock - 1); block++) {
 		dentry_page = get_new_data_page(dir, NULL, block, true);
 		if (IS_ERR(dentry_page))
 			return PTR_ERR(dentry_page);

 		dentry_blk = kmap(dentry_page);
 		bit_pos = room_for_filename(&dentry_blk->dentry_bitmap,
 						slots, NR_DENTRY_IN_BLOCK);
 		if (bit_pos < NR_DENTRY_IN_BLOCK)
 			goto add_dentry;

 		kunmap(dentry_page);
 		f2fs_put_page(dentry_page, 1);
 	}

 	/* Move to next level to find the empty slot for new dentry */
 	++level;
 	goto start;
 add_dentry:
 	f2fs_wait_on_page_writeback(dentry_page, DATA);

 	down_write(&F2FS_I(inode)->i_sem);
 	page = init_inode_metadata(inode, dir, name, NULL);
 	if (IS_ERR(page)) {
 		err = PTR_ERR(page);
 		goto fail;
 	}
 	de = &dentry_blk->dentry[bit_pos];
 	de->hash_code = dentry_hash;
 	de->name_len = cpu_to_le16(namelen);
 	memcpy(dentry_blk->filename[bit_pos], name->name, name->len);
 	de->ino = cpu_to_le32(inode->i_ino);
 	set_de_type(de, inode);
 	for (i = 0; i < slots; i++)
 		test_and_set_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
 	set_page_dirty(dentry_page);

 	/* we don't need to mark_inode_dirty now */
 	F2FS_I(inode)->i_pino = dir->i_ino;
 	update_inode(inode, page);
 	f2fs_put_page(page, 1);

 	update_parent_metadata(dir, inode, current_depth);
 fail:
 	up_write(&F2FS_I(inode)->i_sem);

 	if (is_inode_flag_set(F2FS_I(dir), FI_UPDATE_DIR)) {
 		update_inode_page(dir);
 		clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
 	}
 	kunmap(dentry_page);
 	f2fs_put_page(dentry_page, 1);
 	return err;
 }

 int f2fs_do_tmpfile(struct inode *inode, struct inode *dir)
 {
 	struct page *page;
 	int err = 0;

 	down_write(&F2FS_I(inode)->i_sem);
 	page = init_inode_metadata(inode, dir, NULL, NULL);
 	if (IS_ERR(page)) {
 		err = PTR_ERR(page);
 		goto fail;
 	}
 	/* we don't need to mark_inode_dirty now */
 	update_inode(inode, page);
 	f2fs_put_page(page, 1);

 	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
 fail:
 	up_write(&F2FS_I(inode)->i_sem);
 	return err;
 }

 void f2fs_drop_nlink(struct inode *dir, struct inode *inode, struct page *page)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);

 	down_write(&F2FS_I(inode)->i_sem);

 	if (S_ISDIR(inode->i_mode)) {
 		drop_nlink(dir);
 		if (page)
 			update_inode(dir, page);
 		else
 			update_inode_page(dir);
 	}
 	inode->i_ctime = CURRENT_TIME;

 	drop_nlink(inode);
 	if (S_ISDIR(inode->i_mode)) {
 		drop_nlink(inode);
 		i_size_write(inode, 0);
 	}
 	up_write(&F2FS_I(inode)->i_sem);
 	update_inode_page(inode);

 	if (inode->i_nlink == 0)
 		add_orphan_inode(sbi, inode->i_ino);
 	else
 		release_orphan_inode(sbi);
 }

 /*
  * It only removes the dentry from the dentry page, corresponding name
  * entry in name page does not need to be touched during deletion.
  */
 void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
 					struct inode *dir, struct inode *inode)
 {
 	struct	f2fs_dentry_block *dentry_blk;
 	unsigned int bit_pos;
 	int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
 	int i;

 	if (f2fs_has_inline_dentry(dir))
 		return f2fs_delete_inline_entry(dentry, page, dir, inode);

 	lock_page(page);
 	f2fs_wait_on_page_writeback(page, DATA);

 	dentry_blk = page_address(page);
 	bit_pos = dentry - dentry_blk->dentry;
 	for (i = 0; i < slots; i++)
 		clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);

 	/* Let's check and deallocate this dentry page */
 	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
 			NR_DENTRY_IN_BLOCK,
 			0);
 	kunmap(page); /* kunmap - pair of f2fs_find_entry */
 	set_page_dirty(page);

 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;

 	if (inode)
 		f2fs_drop_nlink(dir, inode, NULL);

 	if (bit_pos == NR_DENTRY_IN_BLOCK) {
 		truncate_hole(dir, page->index, page->index + 1);
 		clear_page_dirty_for_io(page);
 		ClearPageUptodate(page);
 		inode_dec_dirty_pages(dir);
 	}
 	f2fs_put_page(page, 1);
 }

 bool f2fs_empty_dir(struct inode *dir)
 {
 	unsigned long bidx;
 	struct page *dentry_page;
 	unsigned int bit_pos;
 	struct f2fs_dentry_block *dentry_blk;
 	unsigned long nblock = dir_blocks(dir);

 	if (f2fs_has_inline_dentry(dir))
 		return f2fs_empty_inline_dir(dir);

 	for (bidx = 0; bidx < nblock; bidx++) {
 		dentry_page = get_lock_data_page(dir, bidx);
 		if (IS_ERR(dentry_page)) {
 			if (PTR_ERR(dentry_page) == -ENOENT)
 				continue;
 			else
 				return false;
 		}

 		dentry_blk = kmap_atomic(dentry_page);
 		if (bidx == 0)
 			bit_pos = 2;
 		else
 			bit_pos = 0;
 		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
 						NR_DENTRY_IN_BLOCK,
 						bit_pos);
 		kunmap_atomic(dentry_blk);

 		f2fs_put_page(dentry_page, 1);

 		if (bit_pos < NR_DENTRY_IN_BLOCK)
 			return false;
 	}
 	return true;
 }

 bool f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 						unsigned int start_pos)
 {
 	unsigned char d_type = DT_UNKNOWN;
 	unsigned int bit_pos;
 	struct f2fs_dir_entry *de = NULL;

 	bit_pos = ((unsigned long)ctx->pos % d->max);

 	while (bit_pos < d->max) {
 		bit_pos = find_next_bit_le(d->bitmap, d->max, bit_pos);
 		if (bit_pos >= d->max)
 			break;

 		de = &d->dentry[bit_pos];
 		if (de->file_type < F2FS_FT_MAX)
 			d_type = f2fs_filetype_table[de->file_type];
 		else
 			d_type = DT_UNKNOWN;
 		if (!dir_emit(ctx, d->filename[bit_pos],
 					le16_to_cpu(de->name_len),
 					le32_to_cpu(de->ino), d_type))
 			return true;

 		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
 		ctx->pos = start_pos + bit_pos;
 	}
 	return false;
 }

 static int f2fs_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct inode *inode = file_inode(file);
 	unsigned long npages = dir_blocks(inode);
 	struct f2fs_dentry_block *dentry_blk = NULL;
 	struct page *dentry_page = NULL;
 	struct file_ra_state *ra = &file->f_ra;
 	unsigned int n = ((unsigned long)ctx->pos / NR_DENTRY_IN_BLOCK);
 	struct f2fs_dentry_ptr d;

 	if (f2fs_has_inline_dentry(inode))
 		return f2fs_read_inline_dir(file, ctx);

 	/* readahead for multi pages of dir */
 	if (npages - n > 1 && !ra_has_index(ra, n))
 		page_cache_sync_readahead(inode->i_mapping, ra, file, n,
 				min(npages - n, (pgoff_t)MAX_DIR_RA_PAGES));

 	for (; n < npages; n++) {
 		dentry_page = get_lock_data_page(inode, n);
 		if (IS_ERR(dentry_page))
 			continue;

 		dentry_blk = kmap(dentry_page);

 		make_dentry_ptr(&d, (void *)dentry_blk, 1);

 		if (f2fs_fill_dentries(ctx, &d, n * NR_DENTRY_IN_BLOCK))
 			goto stop;

 		ctx->pos = (n + 1) * NR_DENTRY_IN_BLOCK;
 		kunmap(dentry_page);
 		f2fs_put_page(dentry_page, 1);
 		dentry_page = NULL;
 	}
 stop:
 	if (dentry_page && !IS_ERR(dentry_page)) {
 		kunmap(dentry_page);
 		f2fs_put_page(dentry_page, 1);
 	}

 	return 0;
 }

 const struct file_operations f2fs_dir_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
 	.iterate	= f2fs_readdir,
 	.fsync		= f2fs_sync_file,
 	.unlocked_ioctl	= f2fs_ioctl,
 };
	/*
	* fs/f2fs/dir.c
	*
	* Copyright (c) 2012 Samsung Electronics Co., Ltd.
	* http://www.samsung.com/
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/fs.h>
	#include <linux/f2fs_fs.h>
	#include "f2fs.h"
	#include "node.h"
	#include "acl.h"
	#include "xattr.h"

	static unsigned long dir_blocks(struct inode *inode)
	{
	return ((unsigned long long) (i_size_read(inode) + PAGE_CACHE_SIZE - 1))
	>> PAGE_CACHE_SHIFT;
	}

	static unsigned int dir_buckets(unsigned int level, int dir_level)
	{
	if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
	return 1 << (level + dir_level);
	else
	return MAX_DIR_BUCKETS;
	}

	static unsigned int bucket_blocks(unsigned int level)
	{
	if (level < MAX_DIR_HASH_DEPTH / 2)
	return 2;
	else
	return 4;
	}

	unsigned char f2fs_filetype_table[F2FS_FT_MAX] = {
	[F2FS_FT_UNKNOWN] = DT_UNKNOWN,
	[F2FS_FT_REG_FILE] = DT_REG,
	[F2FS_FT_DIR] = DT_DIR,
	[F2FS_FT_CHRDEV] = DT_CHR,
	[F2FS_FT_BLKDEV] = DT_BLK,
	[F2FS_FT_FIFO] = DT_FIFO,
	[F2FS_FT_SOCK] = DT_SOCK,
	[F2FS_FT_SYMLINK] = DT_LNK,
	};

	#define S_SHIFT 12
	static unsigned char f2fs_type_by_mode[S_IFMT >> S_SHIFT] = {
	[S_IFREG >> S_SHIFT] = F2FS_FT_REG_FILE,
	[S_IFDIR >> S_SHIFT] = F2FS_FT_DIR,
	[S_IFCHR >> S_SHIFT] = F2FS_FT_CHRDEV,
	[S_IFBLK >> S_SHIFT] = F2FS_FT_BLKDEV,
	[S_IFIFO >> S_SHIFT] = F2FS_FT_FIFO,
	[S_IFSOCK >> S_SHIFT] = F2FS_FT_SOCK,
	[S_IFLNK >> S_SHIFT] = F2FS_FT_SYMLINK,
	};

	void set_de_type(struct f2fs_dir_entry de, struct inode inode)
	{
	umode_t mode = inode->i_mode;
	de->file_type = f2fs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
	}

	static unsigned long dir_block_index(unsigned int level,
	int dir_level, unsigned int idx)
	{
	unsigned long i;
	unsigned long bidx = 0;

	for (i = 0; i < level; i++)
	bidx += dir_buckets(i, dir_level) * bucket_blocks(i);
	bidx += idx * bucket_blocks(level);
	return bidx;
	}

	static bool early_match_name(size_t namelen, f2fs_hash_t namehash,
	struct f2fs_dir_entry *de)
	{
	if (le16_to_cpu(de->name_len) != namelen)
	return false;

	if (de->hash_code != namehash)
	return false;

	return true;
	}

	static struct f2fs_dir_entry find_in_block(struct page dentry_page,
	struct qstr name, int max_slots,
	struct page **res_page)
	{
	struct f2fs_dentry_block *dentry_blk;
	struct f2fs_dir_entry *de;
	struct f2fs_dentry_ptr d;

	dentry_blk = (struct f2fs_dentry_block *)kmap(dentry_page);

	make_dentry_ptr(&d, (void *)dentry_blk, 1);
	de = find_target_dentry(name, max_slots, &d);

	if (de)
	*res_page = dentry_page;
	else
	kunmap(dentry_page);

	/*
	* For the most part, it should be a bug when name_len is zero.
	* We stop here for figuring out where the bugs has occurred.
	*/
	f2fs_bug_on(F2FS_P_SB(dentry_page), d.max < 0);
	return de;
	}

	struct f2fs_dir_entry find_target_dentry(struct qstr name, int *max_slots,
	struct f2fs_dentry_ptr *d)
	{
	struct f2fs_dir_entry *de;
	unsigned long bit_pos = 0;
	f2fs_hash_t namehash = f2fs_dentry_hash(name);
	int max_len = 0;

	if (max_slots)
	*max_slots = 0;
	while (bit_pos < d->max) {
	if (!test_bit_le(bit_pos, d->bitmap)) {
	if (bit_pos == 0)
	max_len = 1;
	else if (!test_bit_le(bit_pos - 1, d->bitmap))
	max_len++;
	bit_pos++;
	continue;
	}
	de = &d->dentry[bit_pos];
	if (early_match_name(name->len, namehash, de) &&
	!memcmp(d->filename[bit_pos], name->name, name->len))
	goto found;

	if (max_slots && max_slots >= 0 && max_len > max_slots) {
	*max_slots = max_len;
	max_len = 0;
	}

	/* remain bug on condition */
	if (unlikely(!de->name_len))
	d->max = -1;

	bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
	}

	de = NULL;
	found:
	if (max_slots && max_len > *max_slots)
	*max_slots = max_len;
	return de;
	}

	static struct f2fs_dir_entry find_in_level(struct inode dir,
	unsigned int level, struct qstr *name,
	f2fs_hash_t namehash, struct page **res_page)
	{
	int s = GET_DENTRY_SLOTS(name->len);
	unsigned int nbucket, nblock;
	unsigned int bidx, end_block;
	struct page *dentry_page;
	struct f2fs_dir_entry *de = NULL;
	bool room = false;
	int max_slots;

	f2fs_bug_on(F2FS_I_SB(dir), level > MAX_DIR_HASH_DEPTH);

	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
	nblock = bucket_blocks(level);

	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
	le32_to_cpu(namehash) % nbucket);
	end_block = bidx + nblock;

	for (; bidx < end_block; bidx++) {
	/* no need to allocate new dentry pages to all the indices */
	dentry_page = find_data_page(dir, bidx, true);
	if (IS_ERR(dentry_page)) {
	room = true;
	continue;
	}

	de = find_in_block(dentry_page, name, &max_slots, res_page);
	if (de)
	break;

	if (max_slots >= s)
	room = true;
	f2fs_put_page(dentry_page, 0);
	}

	if (!de && room && F2FS_I(dir)->chash != namehash) {
	F2FS_I(dir)->chash = namehash;
	F2FS_I(dir)->clevel = level;
	}

	return de;
	}

	/*
	* Find an entry in the specified directory with the wanted name.
	* It returns the page where the entry was found (as a parameter - res_page),
	* and the entry itself. Page is returned mapped and unlocked.
	* Entry is guaranteed to be valid.
	*/
	struct f2fs_dir_entry f2fs_find_entry(struct inode dir,
	struct qstr child, struct page *res_page)
	{
	unsigned long npages = dir_blocks(dir);
	struct f2fs_dir_entry *de = NULL;
	f2fs_hash_t name_hash;
	unsigned int max_depth;
	unsigned int level;

	if (f2fs_has_inline_dentry(dir))
	return find_in_inline_dir(dir, child, res_page);

	if (npages == 0)
	return NULL;

	*res_page = NULL;

	name_hash = f2fs_dentry_hash(child);
	max_depth = F2FS_I(dir)->i_current_depth;

	for (level = 0; level < max_depth; level++) {
	de = find_in_level(dir, level, child, name_hash, res_page);
	if (de)
	break;
	}
	if (!de && F2FS_I(dir)->chash != name_hash) {
	F2FS_I(dir)->chash = name_hash;
	F2FS_I(dir)->clevel = level - 1;
	}
	return de;
	}

	struct f2fs_dir_entry f2fs_parent_dir(struct inode dir, struct page **p)
	{
	struct page *page;
	struct f2fs_dir_entry *de;
	struct f2fs_dentry_block *dentry_blk;

	if (f2fs_has_inline_dentry(dir))
	return f2fs_parent_inline_dir(dir, p);

	page = get_lock_data_page(dir, 0);
	if (IS_ERR(page))
	return NULL;

	dentry_blk = kmap(page);
	de = &dentry_blk->dentry[1];
	*p = page;
	unlock_page(page);
	return de;
	}

	ino_t f2fs_inode_by_name(struct inode dir, struct qstr qstr)
	{
	ino_t res = 0;
	struct f2fs_dir_entry *de;
	struct page *page;

	de = f2fs_find_entry(dir, qstr, &page);
	if (de) {
	res = le32_to_cpu(de->ino);
	f2fs_dentry_kunmap(dir, page);
	f2fs_put_page(page, 0);
	}

	return res;
	}

	void f2fs_set_link(struct inode dir, struct f2fs_dir_entry de,
	struct page page, struct inode inode)
	{
	enum page_type type = f2fs_has_inline_dentry(dir) ? NODE : DATA;
	lock_page(page);
	f2fs_wait_on_page_writeback(page, type);
	de->ino = cpu_to_le32(inode->i_ino);
	set_de_type(de, inode);
	f2fs_dentry_kunmap(dir, page);
	set_page_dirty(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	mark_inode_dirty(dir);

	f2fs_put_page(page, 1);
	}

	static void init_dent_inode(const struct qstr name, struct page ipage)
	{
	struct f2fs_inode *ri;

	f2fs_wait_on_page_writeback(ipage, NODE);

	/* copy name info. to this inode page */
	ri = F2FS_INODE(ipage);
	ri->i_namelen = cpu_to_le32(name->len);
	memcpy(ri->i_name, name->name, name->len);
	set_page_dirty(ipage);
	}

	int update_dent_inode(struct inode inode, const struct qstr name)
	{
	struct page *page;

	page = get_node_page(F2FS_I_SB(inode), inode->i_ino);
	if (IS_ERR(page))
	return PTR_ERR(page);

	init_dent_inode(name, page);
	f2fs_put_page(page, 1);

	return 0;
	}

	void do_make_empty_dir(struct inode inode, struct inode parent,
	struct f2fs_dentry_ptr *d)
	{
	struct f2fs_dir_entry *de;

	de = &d->dentry[0];
	de->name_len = cpu_to_le16(1);
	de->hash_code = 0;
	de->ino = cpu_to_le32(inode->i_ino);
	memcpy(d->filename[0], ".", 1);
	set_de_type(de, inode);

	de = &d->dentry[1];
	de->hash_code = 0;
	de->name_len = cpu_to_le16(2);
	de->ino = cpu_to_le32(parent->i_ino);
	memcpy(d->filename[1], "..", 2);
	set_de_type(de, inode);

	test_and_set_bit_le(0, (void *)d->bitmap);
	test_and_set_bit_le(1, (void *)d->bitmap);
	}

	static int make_empty_dir(struct inode *inode,
	struct inode parent, struct page page)
	{
	struct page *dentry_page;
	struct f2fs_dentry_block *dentry_blk;
	struct f2fs_dentry_ptr d;

	if (f2fs_has_inline_dentry(inode))
	return make_empty_inline_dir(inode, parent, page);

	dentry_page = get_new_data_page(inode, page, 0, true);
	if (IS_ERR(dentry_page))
	return PTR_ERR(dentry_page);

	dentry_blk = kmap_atomic(dentry_page);

	make_dentry_ptr(&d, (void *)dentry_blk, 1);
	do_make_empty_dir(inode, parent, &d);

	kunmap_atomic(dentry_blk);

	set_page_dirty(dentry_page);
	f2fs_put_page(dentry_page, 1);
	return 0;
	}

	struct page init_inode_metadata(struct inode inode, struct inode *dir,
	const struct qstr name, struct page dpage)
	{
	struct page *page;
	int err;

	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
	page = new_inode_page(inode);
	if (IS_ERR(page))
	return page;

	if (S_ISDIR(inode->i_mode)) {
	err = make_empty_dir(inode, dir, page);
	if (err)
	goto error;
	}

	err = f2fs_init_acl(inode, dir, page, dpage);
	if (err)
	goto put_error;

	err = f2fs_init_security(inode, dir, name, page);
	if (err)
	goto put_error;
	} else {
	page = get_node_page(F2FS_I_SB(dir), inode->i_ino);
	if (IS_ERR(page))
	return page;

	set_cold_node(inode, page);
	}

	if (name)
	init_dent_inode(name, page);

	/*
	* This file should be checkpointed during fsync.
	* We lost i_pino from now on.
	*/
	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
	file_lost_pino(inode);
	/*
	* If link the tmpfile to alias through linkat path,
	* we should remove this inode from orphan list.
	*/
	if (inode->i_nlink == 0)
	remove_orphan_inode(F2FS_I_SB(dir), inode->i_ino);
	inc_nlink(inode);
	}
	return page;

	put_error:
	f2fs_put_page(page, 1);
	error:
	/* once the failed inode becomes a bad inode, i_mode is S_IFREG */
	truncate_inode_pages(&inode->i_data, 0);
	truncate_blocks(inode, 0, false);
	remove_dirty_dir_inode(inode);
	remove_inode_page(inode);
	return ERR_PTR(err);
	}

	void update_parent_metadata(struct inode dir, struct inode inode,
	unsigned int current_depth)
	{
	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
	if (S_ISDIR(inode->i_mode)) {
	inc_nlink(dir);
	set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
	}
	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
	}
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	mark_inode_dirty(dir);

	if (F2FS_I(dir)->i_current_depth != current_depth) {
	F2FS_I(dir)->i_current_depth = current_depth;
	set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
	}

	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
	clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
	}

	int room_for_filename(const void *bitmap, int slots, int max_slots)
	{
	int bit_start = 0;
	int zero_start, zero_end;
	next:
	zero_start = find_next_zero_bit_le(bitmap, max_slots, bit_start);
	if (zero_start >= max_slots)
	return max_slots;

	zero_end = find_next_bit_le(bitmap, max_slots, zero_start);
	if (zero_end - zero_start >= slots)
	return zero_start;

	bit_start = zero_end + 1;

	if (zero_end + 1 >= max_slots)
	return max_slots;
	goto next;
	}

	/*
	* Caller should grab and release a rwsem by calling f2fs_lock_op() and
	* f2fs_unlock_op().
	*/
	int __f2fs_add_link(struct inode dir, const struct qstr name,
	struct inode *inode)
	{
	unsigned int bit_pos;
	unsigned int level;
	unsigned int current_depth;
	unsigned long bidx, block;
	f2fs_hash_t dentry_hash;
	struct f2fs_dir_entry *de;
	unsigned int nbucket, nblock;
	size_t namelen = name->len;
	struct page *dentry_page = NULL;
	struct f2fs_dentry_block *dentry_blk = NULL;
	int slots = GET_DENTRY_SLOTS(namelen);
	struct page *page;
	int err = 0;
	int i;

	if (f2fs_has_inline_dentry(dir)) {
	err = f2fs_add_inline_entry(dir, name, inode);
	if (!err \|\| err != -EAGAIN)
	return err;
	else
	err = 0;
	}

	dentry_hash = f2fs_dentry_hash(name);
	level = 0;
	current_depth = F2FS_I(dir)->i_current_depth;
	if (F2FS_I(dir)->chash == dentry_hash) {
	level = F2FS_I(dir)->clevel;
	F2FS_I(dir)->chash = 0;
	}

	start:
	if (unlikely(current_depth == MAX_DIR_HASH_DEPTH))
	return -ENOSPC;

	/* Increase the depth, if required */
	if (level == current_depth)
	++current_depth;

	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
	nblock = bucket_blocks(level);

	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
	(le32_to_cpu(dentry_hash) % nbucket));

	for (block = bidx; block <= (bidx + nblock - 1); block++) {
	dentry_page = get_new_data_page(dir, NULL, block, true);
	if (IS_ERR(dentry_page))
	return PTR_ERR(dentry_page);

	dentry_blk = kmap(dentry_page);
	bit_pos = room_for_filename(&dentry_blk->dentry_bitmap,
	slots, NR_DENTRY_IN_BLOCK);
	if (bit_pos < NR_DENTRY_IN_BLOCK)
	goto add_dentry;

	kunmap(dentry_page);
	f2fs_put_page(dentry_page, 1);
	}

	/* Move to next level to find the empty slot for new dentry */
	++level;
	goto start;
	add_dentry:
	f2fs_wait_on_page_writeback(dentry_page, DATA);

	down_write(&F2FS_I(inode)->i_sem);
	page = init_inode_metadata(inode, dir, name, NULL);
	if (IS_ERR(page)) {
	err = PTR_ERR(page);
	goto fail;
	}
	de = &dentry_blk->dentry[bit_pos];
	de->hash_code = dentry_hash;
	de->name_len = cpu_to_le16(namelen);
	memcpy(dentry_blk->filename[bit_pos], name->name, name->len);
	de->ino = cpu_to_le32(inode->i_ino);
	set_de_type(de, inode);
	for (i = 0; i < slots; i++)
	test_and_set_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
	set_page_dirty(dentry_page);

	/* we don't need to mark_inode_dirty now */
	F2FS_I(inode)->i_pino = dir->i_ino;
	update_inode(inode, page);
	f2fs_put_page(page, 1);

	update_parent_metadata(dir, inode, current_depth);
	fail:
	up_write(&F2FS_I(inode)->i_sem);

	if (is_inode_flag_set(F2FS_I(dir), FI_UPDATE_DIR)) {
	update_inode_page(dir);
	clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
	}
	kunmap(dentry_page);
	f2fs_put_page(dentry_page, 1);
	return err;
	}

	int f2fs_do_tmpfile(struct inode inode, struct inode dir)
	{
	struct page *page;
	int err = 0;

	down_write(&F2FS_I(inode)->i_sem);
	page = init_inode_metadata(inode, dir, NULL, NULL);
	if (IS_ERR(page)) {
	err = PTR_ERR(page);
	goto fail;
	}
	/* we don't need to mark_inode_dirty now */
	update_inode(inode, page);
	f2fs_put_page(page, 1);

	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
	fail:
	up_write(&F2FS_I(inode)->i_sem);
	return err;
	}

	void f2fs_drop_nlink(struct inode dir, struct inode inode, struct page *page)
	{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);

	down_write(&F2FS_I(inode)->i_sem);

	if (S_ISDIR(inode->i_mode)) {
	drop_nlink(dir);
	if (page)
	update_inode(dir, page);
	else
	update_inode_page(dir);
	}
	inode->i_ctime = CURRENT_TIME;

	drop_nlink(inode);
	if (S_ISDIR(inode->i_mode)) {
	drop_nlink(inode);
	i_size_write(inode, 0);
	}
	up_write(&F2FS_I(inode)->i_sem);
	update_inode_page(inode);

	if (inode->i_nlink == 0)
	add_orphan_inode(sbi, inode->i_ino);
	else
	release_orphan_inode(sbi);
	}

	/*
	* It only removes the dentry from the dentry page, corresponding name
	* entry in name page does not need to be touched during deletion.
	*/
	void f2fs_delete_entry(struct f2fs_dir_entry dentry, struct page page,
	struct inode dir, struct inode inode)
	{
	struct f2fs_dentry_block *dentry_blk;
	unsigned int bit_pos;
	int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
	int i;

	if (f2fs_has_inline_dentry(dir))
	return f2fs_delete_inline_entry(dentry, page, dir, inode);

	lock_page(page);
	f2fs_wait_on_page_writeback(page, DATA);

	dentry_blk = page_address(page);
	bit_pos = dentry - dentry_blk->dentry;
	for (i = 0; i < slots; i++)
	clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);

	/* Let's check and deallocate this dentry page */
	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
	NR_DENTRY_IN_BLOCK,
	0);
	kunmap(page); /* kunmap - pair of f2fs_find_entry */
	set_page_dirty(page);

	dir->i_ctime = dir->i_mtime = CURRENT_TIME;

	if (inode)
	f2fs_drop_nlink(dir, inode, NULL);

	if (bit_pos == NR_DENTRY_IN_BLOCK) {
	truncate_hole(dir, page->index, page->index + 1);
	clear_page_dirty_for_io(page);
	ClearPageUptodate(page);
	inode_dec_dirty_pages(dir);
	}
	f2fs_put_page(page, 1);
	}

	bool f2fs_empty_dir(struct inode *dir)
	{
	unsigned long bidx;
	struct page *dentry_page;
	unsigned int bit_pos;
	struct f2fs_dentry_block *dentry_blk;
	unsigned long nblock = dir_blocks(dir);

	if (f2fs_has_inline_dentry(dir))
	return f2fs_empty_inline_dir(dir);

	for (bidx = 0; bidx < nblock; bidx++) {
	dentry_page = get_lock_data_page(dir, bidx);
	if (IS_ERR(dentry_page)) {
	if (PTR_ERR(dentry_page) == -ENOENT)
	continue;
	else
	return false;
	}

	dentry_blk = kmap_atomic(dentry_page);
	if (bidx == 0)
	bit_pos = 2;
	else
	bit_pos = 0;
	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
	NR_DENTRY_IN_BLOCK,
	bit_pos);
	kunmap_atomic(dentry_blk);

	f2fs_put_page(dentry_page, 1);

	if (bit_pos < NR_DENTRY_IN_BLOCK)
	return false;
	}
	return true;
	}

	bool f2fs_fill_dentries(struct dir_context ctx, struct f2fs_dentry_ptr d,
	unsigned int start_pos)
	{
	unsigned char d_type = DT_UNKNOWN;
	unsigned int bit_pos;
	struct f2fs_dir_entry *de = NULL;

	bit_pos = ((unsigned long)ctx->pos % d->max);

	while (bit_pos < d->max) {
	bit_pos = find_next_bit_le(d->bitmap, d->max, bit_pos);
	if (bit_pos >= d->max)
	break;

	de = &d->dentry[bit_pos];
	if (de->file_type < F2FS_FT_MAX)
	d_type = f2fs_filetype_table[de->file_type];
	else
	d_type = DT_UNKNOWN;
	if (!dir_emit(ctx, d->filename[bit_pos],
	le16_to_cpu(de->name_len),
	le32_to_cpu(de->ino), d_type))
	return true;

	bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
	ctx->pos = start_pos + bit_pos;
	}
	return false;
	}

	static int f2fs_readdir(struct file file, struct dir_context ctx)
	{
	struct inode *inode = file_inode(file);
	unsigned long npages = dir_blocks(inode);
	struct f2fs_dentry_block *dentry_blk = NULL;
	struct page *dentry_page = NULL;
	struct file_ra_state *ra = &file->f_ra;
	unsigned int n = ((unsigned long)ctx->pos / NR_DENTRY_IN_BLOCK);
	struct f2fs_dentry_ptr d;

	if (f2fs_has_inline_dentry(inode))
	return f2fs_read_inline_dir(file, ctx);

	/* readahead for multi pages of dir */
	if (npages - n > 1 && !ra_has_index(ra, n))
	page_cache_sync_readahead(inode->i_mapping, ra, file, n,
	min(npages - n, (pgoff_t)MAX_DIR_RA_PAGES));

	for (; n < npages; n++) {
	dentry_page = get_lock_data_page(inode, n);
	if (IS_ERR(dentry_page))
	continue;

	dentry_blk = kmap(dentry_page);

	make_dentry_ptr(&d, (void *)dentry_blk, 1);

	if (f2fs_fill_dentries(ctx, &d, n * NR_DENTRY_IN_BLOCK))
	goto stop;

	ctx->pos = (n + 1) * NR_DENTRY_IN_BLOCK;
	kunmap(dentry_page);
	f2fs_put_page(dentry_page, 1);
	dentry_page = NULL;
	}
	stop:
	if (dentry_page && !IS_ERR(dentry_page)) {
	kunmap(dentry_page);
	f2fs_put_page(dentry_page, 1);
	}

	return 0;
	}

	const struct file_operations f2fs_dir_operations = {
	.llseek = generic_file_llseek,
	.read = generic_read_dir,
	.iterate = f2fs_readdir,
	.fsync = f2fs_sync_file,
	.unlocked_ioctl = f2fs_ioctl,
	};