[PATCH 12/17] f2fs: add core directory operations

[Jaegeuk Kim <jaegeuk.kim@samsung.com>]

This adds core functions to find, add, delete, and link dentries.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
---
 fs/f2fs/dir.c  |  674 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/f2fs/hash.c |   98 ++++++++
 2 files changed, 772 insertions(+)
 create mode 100644 fs/f2fs/dir.c
 create mode 100644 fs/f2fs/hash.c

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
new file mode 100644
index 0000000..94eddf2
--- /dev/null
+++ b/fs/f2fs/dir.c
@@ -0,0 +1,674 @@
+/**
+ * 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 "acl.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)
+{
+	if (level < MAX_DIR_HASH_DEPTH / 2)
+		return 1 << level;
+	else
+		return 1 << ((MAX_DIR_HASH_DEPTH / 2) - 1);
+}
+
+static unsigned int bucket_blocks(unsigned int level)
+{
+	if (level < MAX_DIR_HASH_DEPTH / 2)
+		return 2;
+	else
+		return 4;
+}
+
+static 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,
+};
+
+static void set_de_type(struct f2fs_dir_entry *de, struct inode *inode)
+{
+	mode_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, unsigned int idx)
+{
+	unsigned long i;
+	unsigned long bidx = 0;
+
+	for (i = 0; i < level; i++)
+		bidx += dir_buckets(i) * bucket_blocks(i);
+	bidx += idx * bucket_blocks(level);
+	return bidx;
+}
+
+static bool early_match_name(const char *name, int namelen,
+			f2fs_hash_t namehash, struct f2fs_dir_entry *de)
+{
+	if (le16_to_cpu(de->name_len) != namelen)
+		return false;
+
+	if (le32_to_cpu(de->hash_code) != namehash)
+		return false;
+
+	return true;
+}
+
+static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
+			const char *name, int namelen, int *max_slots,
+			f2fs_hash_t namehash, struct page **res_page)
+{
+	struct f2fs_dir_entry *de;
+	unsigned long bit_pos, end_pos, next_pos;
+	struct f2fs_dentry_block *dentry_blk = kmap(dentry_page);
+	int slots;
+
+	bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+					NR_DENTRY_IN_BLOCK, 0);
+	while (bit_pos < NR_DENTRY_IN_BLOCK) {
+		de = &dentry_blk->dentry[bit_pos];
+		slots = (le16_to_cpu(de->name_len) + F2FS_NAME_LEN - 1) /
+							F2FS_NAME_LEN;
+
+		if (early_match_name(name, namelen, namehash, de)) {
+			if (!memcmp(dentry_blk->filename[bit_pos],
+							name, namelen)) {
+				*res_page = dentry_page;
+				goto found;
+			}
+		}
+		next_pos = bit_pos + slots;
+		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+				NR_DENTRY_IN_BLOCK, next_pos);
+		if (bit_pos >= NR_DENTRY_IN_BLOCK)
+			end_pos = NR_DENTRY_IN_BLOCK;
+		else
+			end_pos = bit_pos;
+		if (*max_slots < end_pos - next_pos)
+			*max_slots = end_pos - next_pos;
+	}
+
+	de = NULL;
+	kunmap(dentry_page);
+found:
+	return de;
+}
+
+static struct f2fs_dir_entry *find_in_level(struct inode *dir,
+		unsigned int level, const char *name, int namelen,
+			f2fs_hash_t namehash, struct page **res_page)
+{
+	int s = (namelen + F2FS_NAME_LEN - 1) / F2FS_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 = 0;
+
+	BUG_ON(level > MAX_DIR_HASH_DEPTH);
+
+	nbucket = dir_buckets(level);
+	nblock = bucket_blocks(level);
+
+	bidx = dir_block_index(level, 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);
+		if (IS_ERR(dentry_page)) {
+			room = true;
+			continue;
+		}
+
+		de = find_in_block(dentry_page, name, namelen,
+					&max_slots, namehash, 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)
+{
+	const char *name = child->name;
+	int namelen = child->len;
+	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 (npages == 0)
+		return NULL;
+
+	*res_page = NULL;
+
+	name_hash = f2fs_dentry_hash(name, namelen);
+	max_depth = F2FS_I(dir)->i_current_depth;
+
+	for (level = 0; level < max_depth; level++) {
+		de = find_in_level(dir, level, name,
+				namelen, 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 = NULL;
+	struct f2fs_dir_entry *de = NULL;
+	struct f2fs_dentry_block *dentry_blk = NULL;
+
+	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);
+		kunmap(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)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+
+	mutex_lock_op(sbi, DENTRY_OPS);
+	lock_page(page);
+	wait_on_page_writeback(page);
+	de->ino = cpu_to_le32(inode->i_ino);
+	set_de_type(de, inode);
+	kunmap(page);
+	set_page_dirty(page);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	mark_inode_dirty(dir);
+	f2fs_put_page(page, 1);
+	mutex_unlock_op(sbi, DENTRY_OPS);
+}
+
+void init_dent_inode(struct dentry *dentry, struct page *ipage)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct f2fs_node *rn;
+
+	if (IS_ERR(ipage))
+		return;
+
+	wait_on_page_writeback(ipage);
+
+	/* copy dentry info. to this inode page */
+	rn = (struct f2fs_node *)page_address(ipage);
+	rn->i.i_pino = cpu_to_le32(dir->i_ino);
+	rn->i.i_namelen = cpu_to_le32(dentry->d_name.len);
+	memcpy(rn->i.i_name, dentry->d_name.name, dentry->d_name.len);
+	set_page_dirty(ipage);
+}
+
+static int init_inode_metadata(struct inode *inode, struct dentry *dentry)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
+		int err;
+		err = new_inode_page(inode, dentry);
+		if (err)
+			return err;
+
+		if (S_ISDIR(inode->i_mode)) {
+			err = f2fs_make_empty(inode, dir);
+			if (err) {
+				remove_inode_page(inode);
+				return err;
+			}
+		}
+
+		err = f2fs_init_acl(inode, dir);
+		if (err) {
+			remove_inode_page(inode);
+			return err;
+		}
+	} else {
+		struct page *ipage;
+		ipage = get_node_page(F2FS_SB(dir->i_sb), inode->i_ino);
+		if (IS_ERR(ipage))
+			return PTR_ERR(ipage);
+		init_dent_inode(dentry, ipage);
+		f2fs_put_page(ipage, 1);
+	}
+	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
+		inc_nlink(inode);
+		f2fs_write_inode(inode, NULL);
+	}
+	return 0;
+}
+
+static void update_parent_metadata(struct inode *dir, struct inode *inode,
+						unsigned int current_depth)
+{
+	bool need_dir_update = false;
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
+		if (S_ISDIR(inode->i_mode)) {
+			inc_nlink(dir);
+			need_dir_update = true;
+		}
+		clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
+	}
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	if (F2FS_I(dir)->i_current_depth != current_depth) {
+		F2FS_I(dir)->i_current_depth = current_depth;
+		need_dir_update = true;
+	}
+
+	if (need_dir_update)
+		f2fs_write_inode(dir, NULL);
+	else
+		mark_inode_dirty(dir);
+
+	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
+		clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
+}
+
+static int room_for_filename(struct f2fs_dentry_block *dentry_blk, int slots)
+{
+	int bit_start = 0;
+	int zero_start, zero_end;
+next:
+	zero_start = find_next_zero_bit_le(&dentry_blk->dentry_bitmap,
+						NR_DENTRY_IN_BLOCK,
+						bit_start);
+	if (zero_start >= NR_DENTRY_IN_BLOCK)
+		return NR_DENTRY_IN_BLOCK;
+
+	zero_end = find_next_bit_le(&dentry_blk->dentry_bitmap,
+						NR_DENTRY_IN_BLOCK,
+						zero_start);
+	if (zero_end - zero_start >= slots)
+		return zero_start;
+
+	bit_start = zero_end + 1;
+
+	if (zero_end + 1 >= NR_DENTRY_IN_BLOCK)
+		return NR_DENTRY_IN_BLOCK;
+	goto next;
+}
+
+int f2fs_add_link(struct dentry *dentry, 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;
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	struct page *dentry_page = NULL;
+	struct f2fs_dentry_block *dentry_blk = NULL;
+	int slots = (namelen + F2FS_NAME_LEN - 1) / F2FS_NAME_LEN;
+	int err = 0;
+	int i;
+
+	dentry_hash = f2fs_dentry_hash(name, dentry->d_name.len);
+	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 (current_depth == MAX_DIR_HASH_DEPTH)
+		return -ENOSPC;
+
+	/* Increase the depth, if required */
+	if (level == current_depth)
+		++current_depth;
+
+	nbucket = dir_buckets(level);
+	nblock = bucket_blocks(level);
+
+	bidx = dir_block_index(level, (dentry_hash % nbucket));
+
+	for (block = bidx; block <= (bidx + nblock - 1); block++) {
+		mutex_lock_op(sbi, DENTRY_OPS);
+		dentry_page = get_new_data_page(dir, block, true);
+		if (IS_ERR(dentry_page)) {
+			mutex_unlock_op(sbi, DENTRY_OPS);
+			return PTR_ERR(dentry_page);
+		}
+
+		dentry_blk = kmap(dentry_page);
+		bit_pos = room_for_filename(dentry_blk, slots);
+		if (bit_pos < NR_DENTRY_IN_BLOCK)
+			goto add_dentry;
+
+		kunmap(dentry_page);
+		f2fs_put_page(dentry_page, 1);
+		mutex_unlock_op(sbi, DENTRY_OPS);
+	}
+
+	/* Move to next level to find the empty slot for new dentry */
+	++level;
+	goto start;
+add_dentry:
+	err = init_inode_metadata(inode, dentry);
+	if (err)
+		goto fail;
+
+	wait_on_page_writeback(dentry_page);
+
+	de = &dentry_blk->dentry[bit_pos];
+	de->hash_code = cpu_to_le32(dentry_hash);
+	de->name_len = cpu_to_le16(namelen);
+	memcpy(dentry_blk->filename[bit_pos], name, namelen);
+	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);
+	update_parent_metadata(dir, inode, current_depth);
+fail:
+	kunmap(dentry_page);
+	f2fs_put_page(dentry_page, 1);
+	mutex_unlock_op(sbi, DENTRY_OPS);
+	return err;
+}
+
+/**
+ * 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 *inode)
+{
+	struct	f2fs_dentry_block *dentry_blk;
+	unsigned int bit_pos;
+	struct address_space *mapping = page->mapping;
+	struct inode *dir = mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
+	int slots = (le16_to_cpu(dentry->name_len) + F2FS_NAME_LEN - 1) /
+							F2FS_NAME_LEN;
+	void *kaddr = page_address(page);
+	int i;
+
+	mutex_lock_op(sbi, DENTRY_OPS);
+
+	lock_page(page);
+	wait_on_page_writeback(page);
+
+	dentry_blk = (struct f2fs_dentry_block *)kaddr;
+	bit_pos = dentry - (struct f2fs_dir_entry *)dentry_blk->dentry;
+	for (i = 0; i < slots; i++)
+		test_and_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 && S_ISDIR(inode->i_mode)) {
+		drop_nlink(dir);
+		f2fs_write_inode(dir, NULL);
+	} else {
+		mark_inode_dirty(dir);
+	}
+
+	if (inode) {
+		inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+		drop_nlink(inode);
+		if (S_ISDIR(inode->i_mode)) {
+			drop_nlink(inode);
+			i_size_write(inode, 0);
+		}
+		f2fs_write_inode(inode, NULL);
+		if (inode->i_nlink == 0)
+			add_orphan_inode(sbi, inode->i_ino);
+	}
+
+	if (bit_pos == NR_DENTRY_IN_BLOCK) {
+		loff_t page_offset;
+		truncate_hole(dir, page->index, page->index + 1);
+		clear_page_dirty_for_io(page);
+		ClearPageUptodate(page);
+		dec_page_count(sbi, F2FS_DIRTY_DENTS);
+		inode_dec_dirty_dents(dir);
+		page_offset = page->index << PAGE_CACHE_SHIFT;
+		f2fs_put_page(page, 1);
+	} else {
+		f2fs_put_page(page, 1);
+	}
+	mutex_unlock_op(sbi, DENTRY_OPS);
+}
+
+int f2fs_make_empty(struct inode *inode, struct inode *parent)
+{
+	struct page *dentry_page;
+	struct f2fs_dentry_block *dentry_blk;
+	struct f2fs_dir_entry *de;
+	void *kaddr;
+
+	dentry_page = get_new_data_page(inode, 0, true);
+	if (IS_ERR(dentry_page))
+		return PTR_ERR(dentry_page);
+
+	kaddr = kmap_atomic(dentry_page);
+	dentry_blk = (struct f2fs_dentry_block *)kaddr;
+
+	de = &dentry_blk->dentry[0];
+	de->name_len = cpu_to_le16(1);
+	de->hash_code = 0;
+	de->ino = cpu_to_le32(inode->i_ino);
+	memcpy(dentry_blk->filename[0], ".", 1);
+	set_de_type(de, inode);
+
+	de = &dentry_blk->dentry[1];
+	de->hash_code = 0;
+	de->name_len = cpu_to_le16(2);
+	de->ino = cpu_to_le32(parent->i_ino);
+	memcpy(dentry_blk->filename[1], "..", 2);
+	set_de_type(de, inode);
+
+	test_and_set_bit_le(0, &dentry_blk->dentry_bitmap);
+	test_and_set_bit_le(1, &dentry_blk->dentry_bitmap);
+	kunmap_atomic(kaddr);
+
+	set_page_dirty(dentry_page);
+	f2fs_put_page(dentry_page, 1);
+	return 0;
+}
+
+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);
+
+	for (bidx = 0; bidx < nblock; bidx++) {
+		void *kaddr;
+		dentry_page = get_lock_data_page(dir, bidx);
+		if (IS_ERR(dentry_page)) {
+			if (PTR_ERR(dentry_page) == -ENOENT)
+				continue;
+			else
+				return false;
+		}
+
+		kaddr = kmap_atomic(dentry_page);
+		dentry_blk = (struct f2fs_dentry_block *)kaddr;
+		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(kaddr);
+
+		f2fs_put_page(dentry_page, 1);
+
+		if (bit_pos < NR_DENTRY_IN_BLOCK)
+			return false;
+	}
+	return true;
+}
+
+static int f2fs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+	unsigned long pos = file->f_pos;
+	struct inode *inode = file->f_dentry->d_inode;
+	unsigned long npages = dir_blocks(inode);
+	unsigned char *types = NULL;
+	unsigned int bit_pos = 0, start_bit_pos = 0;
+	int over = 0;
+	struct f2fs_dentry_block *dentry_blk = NULL;
+	struct f2fs_dir_entry *de = NULL;
+	struct page *dentry_page = NULL;
+	unsigned int n = 0;
+	unsigned char *ptr = NULL;
+	unsigned char d_type = DT_UNKNOWN;
+	int slots;
+
+	types = f2fs_filetype_table;
+	bit_pos = (pos % NR_DENTRY_IN_BLOCK);
+	n = (pos / NR_DENTRY_IN_BLOCK);
+
+	for ( ; n < npages; n++) {
+		dentry_page = get_lock_data_page(inode, n);
+		if (IS_ERR(dentry_page))
+			continue;
+
+		start_bit_pos = bit_pos;
+		dentry_blk = kmap(dentry_page);
+		while (bit_pos < NR_DENTRY_IN_BLOCK) {
+			d_type = DT_UNKNOWN;
+			bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
+							NR_DENTRY_IN_BLOCK,
+							bit_pos);
+			if (bit_pos >= NR_DENTRY_IN_BLOCK)
+				break;
+
+			de = &dentry_blk->dentry[bit_pos];
+			if (types && de->file_type < F2FS_FT_MAX)
+				d_type = types[de->file_type];
+
+			ptr = dentry_blk->filename[bit_pos];
+			over = filldir(dirent,
+					dentry_blk->filename[bit_pos],
+					le16_to_cpu(de->name_len),
+					(n * NR_DENTRY_IN_BLOCK) + bit_pos,
+					le32_to_cpu(de->ino), d_type);
+			if (over) {
+				file->f_pos += bit_pos - start_bit_pos;
+				goto success;
+			}
+			slots = (le16_to_cpu(de->name_len) + F2FS_NAME_LEN - 1)
+								/ F2FS_NAME_LEN;
+			bit_pos += slots;
+		}
+		bit_pos = 0;
+		file->f_pos = (n + 1) * NR_DENTRY_IN_BLOCK;
+		kunmap(dentry_page);
+		f2fs_put_page(dentry_page, 1);
+		dentry_page = NULL;
+	}
+success:
+	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,
+	.readdir	= f2fs_readdir,
+	.fsync		= f2fs_sync_file,
+	.unlocked_ioctl	= f2fs_ioctl,
+};
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
new file mode 100644
index 0000000..098a196
--- /dev/null
+++ b/fs/f2fs/hash.c
@@ -0,0 +1,98 @@
+/**
+ * fs/f2fs/hash.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext3/hash.c
+ *
+ * Copyright (C) 2002 by Theodore Ts'o
+ *
+ * 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/types.h>
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/cryptohash.h>
+#include <linux/pagemap.h>
+
+#include "f2fs.h"
+
+/*
+ * Hashing code copied from ext3
+ */
+#define DELTA 0x9E3779B9
+
+static void TEA_transform(unsigned int buf[4], unsigned int const in[])
+{
+	__u32 sum = 0;
+	__u32 b0 = buf[0], b1 = buf[1];
+	__u32 a = in[0], b = in[1], c = in[2], d = in[3];
+	int n = 16;
+
+	do {
+		sum += DELTA;
+		b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
+		b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
+	} while (--n);
+
+	buf[0] += b0;
+	buf[1] += b1;
+}
+
+static void str2hashbuf(const char *msg, int len, unsigned int *buf, int num)
+{
+	unsigned pad, val;
+	int i;
+
+	pad = (__u32)len | ((__u32)len << 8);
+	pad |= pad << 16;
+
+	val = pad;
+	if (len > num * 4)
+		len = num * 4;
+	for (i = 0; i < len; i++) {
+		if ((i % 4) == 0)
+			val = pad;
+		val = msg[i] + (val << 8);
+		if ((i % 4) == 3) {
+			*buf++ = val;
+			val = pad;
+			num--;
+		}
+	}
+	if (--num >= 0)
+		*buf++ = val;
+	while (--num >= 0)
+		*buf++ = pad;
+}
+
+f2fs_hash_t f2fs_dentry_hash(const char *name, int len)
+{
+	__u32 hash, minor_hash;
+	f2fs_hash_t f2fs_hash;
+	const char *p;
+	__u32 in[8], buf[4];
+
+	/* Initialize the default seed for the hash checksum functions */
+	buf[0] = 0x67452301;
+	buf[1] = 0xefcdab89;
+	buf[2] = 0x98badcfe;
+	buf[3] = 0x10325476;
+
+	p = name;
+	while (len > 0) {
+		str2hashbuf(p, len, in, 4);
+		TEA_transform(buf, in);
+		len -= 16;
+		p += 16;
+	}
+	hash = buf[0];
+	minor_hash = buf[1];
+
+	f2fs_hash = hash;
+	f2fs_hash &= ~F2FS_HASH_COL_BIT;
+	return f2fs_hash;
+}
-- 
1.7.9.5




---
Jaegeuk Kim
Samsung