--- /dev/null
+/**
+ * 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 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];
+
+ 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,
+};
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / commitdiff