/*
   * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
   */

  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/reiserfs_fs.h>
  #include <linux/stat.h>

  #include <linux/buffer_head.h>

  #include <linux/slab.h>

  #include <asm/uaccess.h>

  extern const struct reiserfs_key MIN_KEY;

  static int reiserfs_readdir(struct file *, void *, filldir_t);

  static int reiserfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
  			      int datasync);

  const struct file_operations reiserfs_dir_operations = {

  	.llseek = generic_file_llseek,

  	.read = generic_read_dir,
  	.readdir = reiserfs_readdir,
  	.fsync = reiserfs_dir_fsync,

  	.unlocked_ioctl = reiserfs_ioctl,

  #ifdef CONFIG_COMPAT
  	.compat_ioctl = reiserfs_compat_ioctl,
  #endif

  };

  static int reiserfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
  			      int datasync)

  {

  	struct inode *inode = filp->f_mapping->host;

  	int err;

  
  	err = filemap_write_and_wait_range(inode->i_mapping, start, end);
  	if (err)
  		return err;
  
  	mutex_lock(&inode->i_mutex);

  	reiserfs_write_lock(inode->i_sb);
  	err = reiserfs_commit_for_inode(inode);
  	reiserfs_write_unlock(inode->i_sb);

  	mutex_unlock(&inode->i_mutex);

  	if (err < 0)
  		return err;
  	return 0;

  }

  #define store_ih(where,what) copy_item_head (where, what)

  static inline bool is_privroot_deh(struct dentry *dir,
  				   struct reiserfs_de_head *deh)
  {

  	struct dentry *privroot = REISERFS_SB(dir->d_sb)->priv_root;

  	return (dir == dir->d_parent && privroot->d_inode &&
  	        deh->deh_objectid == INODE_PKEY(privroot->d_inode)->k_objectid);

  }

  int reiserfs_readdir_dentry(struct dentry *dentry, void *dirent,
  			   filldir_t filldir, loff_t *pos)

  {

  	struct inode *inode = dentry->d_inode;

  	struct cpu_key pos_key;	/* key of current position in the directory (key of directory entry) */
  	INITIALIZE_PATH(path_to_entry);
  	struct buffer_head *bh;
  	int item_num, entry_num;
  	const struct reiserfs_key *rkey;
  	struct item_head *ih, tmp_ih;
  	int search_res;
  	char *local_buf;
  	loff_t next_pos;
  	char small_buf[32];	/* avoid kmalloc if we can */
  	struct reiserfs_dir_entry de;
  	int ret = 0;
  
  	reiserfs_write_lock(inode->i_sb);
  
  	reiserfs_check_lock_depth(inode->i_sb, "readdir");
  
  	/* form key for search the next directory entry using f_pos field of
  	   file structure */

  	make_cpu_key(&pos_key, inode, *pos ?: DOT_OFFSET, TYPE_DIRENTRY, 3);

  	next_pos = cpu_key_k_offset(&pos_key);

  	path_to_entry.reada = PATH_READA;
  	while (1) {
  	      research:
  		/* search the directory item, containing entry with specified key */
  		search_res =
  		    search_by_entry_key(inode->i_sb, &pos_key, &path_to_entry,
  					&de);
  		if (search_res == IO_ERROR) {
  			// FIXME: we could just skip part of directory which could
  			// not be read
  			ret = -EIO;

  			goto out;

  		}

  		entry_num = de.de_entry_num;
  		bh = de.de_bh;
  		item_num = de.de_item_num;
  		ih = de.de_ih;
  		store_ih(&tmp_ih, ih);
  
  		/* we must have found item, that is item of this directory, */
  		RFALSE(COMP_SHORT_KEYS(&(ih->ih_key), &pos_key),
  		       "vs-9000: found item %h does not match to dir we readdir %K",
  		       ih, &pos_key);
  		RFALSE(item_num > B_NR_ITEMS(bh) - 1,
  		       "vs-9005 item_num == %d, item amount == %d",
  		       item_num, B_NR_ITEMS(bh));
  
  		/* and entry must be not more than number of entries in the item */
  		RFALSE(I_ENTRY_COUNT(ih) < entry_num,
  		       "vs-9010: entry number is too big %d (%d)",
  		       entry_num, I_ENTRY_COUNT(ih));
  
  		if (search_res == POSITION_FOUND
  		    || entry_num < I_ENTRY_COUNT(ih)) {
  			/* go through all entries in the directory item beginning from the entry, that has been found */
  			struct reiserfs_de_head *deh =
  			    B_I_DEH(bh, ih) + entry_num;
  
  			for (; entry_num < I_ENTRY_COUNT(ih);
  			     entry_num++, deh++) {
  				int d_reclen;
  				char *d_name;
  				off_t d_off;
  				ino_t d_ino;
  
  				if (!de_visible(deh))
  					/* it is hidden entry */
  					continue;
  				d_reclen = entry_length(bh, ih, entry_num);
  				d_name = B_I_DEH_ENTRY_FILE_NAME(bh, ih, deh);

  
  				if (d_reclen <= 0 ||
  				    d_name + d_reclen > bh->b_data + bh->b_size) {
  					/* There is corrupted data in entry,
  					 * We'd better stop here */
  					pathrelse(&path_to_entry);
  					ret = -EIO;
  					goto out;
  				}

  				if (!d_name[d_reclen - 1])
  					d_reclen = strlen(d_name);
  
  				if (d_reclen >
  				    REISERFS_MAX_NAME(inode->i_sb->
  						      s_blocksize)) {
  					/* too big to send back to VFS */
  					continue;
  				}
  
  				/* Ignore the .reiserfs_priv entry */

  				if (is_privroot_deh(dentry, deh))

  					continue;

  
  				d_off = deh_offset(deh);

  				*pos = d_off;

  				d_ino = deh_objectid(deh);
  				if (d_reclen <= 32) {
  					local_buf = small_buf;
  				} else {

  					local_buf = kmalloc(d_reclen,
  							    GFP_NOFS);

  					if (!local_buf) {
  						pathrelse(&path_to_entry);
  						ret = -ENOMEM;
  						goto out;
  					}
  					if (item_moved(&tmp_ih, &path_to_entry)) {

  						kfree(local_buf);

  						goto research;
  					}
  				}
  				// Note, that we copy name to user space via temporary
  				// buffer (local_buf) because filldir will block if
  				// user space buffer is swapped out. At that time
  				// entry can move to somewhere else
  				memcpy(local_buf, d_name, d_reclen);

  
  				/*
  				 * Since filldir might sleep, we can release
  				 * the write lock here for other waiters
  				 */
  				reiserfs_write_unlock(inode->i_sb);

  				if (filldir
  				    (dirent, local_buf, d_reclen, d_off, d_ino,
  				     DT_UNKNOWN) < 0) {

  					reiserfs_write_lock(inode->i_sb);

  					if (local_buf != small_buf) {

  						kfree(local_buf);

  					}
  					goto end;
  				}

  				reiserfs_write_lock(inode->i_sb);

  				if (local_buf != small_buf) {

  					kfree(local_buf);

  				}
  				// next entry should be looked for with such offset
  				next_pos = deh_offset(deh) + 1;
  
  				if (item_moved(&tmp_ih, &path_to_entry)) {
  					goto research;
  				}
  			}	/* for */

  		}

  		if (item_num != B_NR_ITEMS(bh) - 1)
  			// end of directory has been reached
  			goto end;
  
  		/* item we went through is last item of node. Using right
  		   delimiting key check is it directory end */
  		rkey = get_rkey(&path_to_entry, inode->i_sb);
  		if (!comp_le_keys(rkey, &MIN_KEY)) {
  			/* set pos_key to key, that is the smallest and greater
  			   that key of the last entry in the item */
  			set_cpu_key_k_offset(&pos_key, next_pos);
  			continue;
  		}

  		if (COMP_SHORT_KEYS(rkey, &pos_key)) {
  			// end of directory has been reached
  			goto end;

  		}

  
  		/* directory continues in the right neighboring block */
  		set_cpu_key_k_offset(&pos_key,
  				     le_key_k_offset(KEY_FORMAT_3_5, rkey));
  
  	}			/* while */

  end:
  	*pos = next_pos;

  	pathrelse(&path_to_entry);
  	reiserfs_check_path(&path_to_entry);

  out:

  	reiserfs_write_unlock(inode->i_sb);
  	return ret;

  }

  static int reiserfs_readdir(struct file *file, void *dirent, filldir_t filldir)
  {
  	struct dentry *dentry = file->f_path.dentry;
  	return reiserfs_readdir_dentry(dentry, dirent, filldir, &file->f_pos);
  }

  /* compose directory item containing "." and ".." entries (entries are
     not aligned to 4 byte boundary) */
  /* the last four params are LE */

  void make_empty_dir_item_v1(char *body, __le32 dirid, __le32 objid,
  			    __le32 par_dirid, __le32 par_objid)

  {

  	struct reiserfs_de_head *deh;
  
  	memset(body, 0, EMPTY_DIR_SIZE_V1);
  	deh = (struct reiserfs_de_head *)body;
  
  	/* direntry header of "." */
  	put_deh_offset(&(deh[0]), DOT_OFFSET);
  	/* these two are from make_le_item_head, and are are LE */
  	deh[0].deh_dir_id = dirid;
  	deh[0].deh_objectid = objid;
  	deh[0].deh_state = 0;	/* Endian safe if 0 */
  	put_deh_location(&(deh[0]), EMPTY_DIR_SIZE_V1 - strlen("."));
  	mark_de_visible(&(deh[0]));
  
  	/* direntry header of ".." */
  	put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
  	/* key of ".." for the root directory */
  	/* these two are from the inode, and are are LE */
  	deh[1].deh_dir_id = par_dirid;
  	deh[1].deh_objectid = par_objid;
  	deh[1].deh_state = 0;	/* Endian safe if 0 */
  	put_deh_location(&(deh[1]), deh_location(&(deh[0])) - strlen(".."));
  	mark_de_visible(&(deh[1]));
  
  	/* copy ".." and "." */
  	memcpy(body + deh_location(&(deh[0])), ".", 1);
  	memcpy(body + deh_location(&(deh[1])), "..", 2);

  }
  
  /* compose directory item containing "." and ".." entries */

  void make_empty_dir_item(char *body, __le32 dirid, __le32 objid,
  			 __le32 par_dirid, __le32 par_objid)

  {

  	struct reiserfs_de_head *deh;
  
  	memset(body, 0, EMPTY_DIR_SIZE);
  	deh = (struct reiserfs_de_head *)body;
  
  	/* direntry header of "." */
  	put_deh_offset(&(deh[0]), DOT_OFFSET);
  	/* these two are from make_le_item_head, and are are LE */
  	deh[0].deh_dir_id = dirid;
  	deh[0].deh_objectid = objid;
  	deh[0].deh_state = 0;	/* Endian safe if 0 */
  	put_deh_location(&(deh[0]), EMPTY_DIR_SIZE - ROUND_UP(strlen(".")));
  	mark_de_visible(&(deh[0]));
  
  	/* direntry header of ".." */
  	put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
  	/* key of ".." for the root directory */
  	/* these two are from the inode, and are are LE */
  	deh[1].deh_dir_id = par_dirid;
  	deh[1].deh_objectid = par_objid;
  	deh[1].deh_state = 0;	/* Endian safe if 0 */
  	put_deh_location(&(deh[1]),
  			 deh_location(&(deh[0])) - ROUND_UP(strlen("..")));
  	mark_de_visible(&(deh[1]));
  
  	/* copy ".." and "." */
  	memcpy(body + deh_location(&(deh[0])), ".", 1);
  	memcpy(body + deh_location(&(deh[1])), "..", 2);

  }