text: /* * This file is part of UBIFS.
   *
   * Copyright (C) 2006-2008 Nokia Corporation.
   * Copyright (C) 2006, 2007 University of Szeged, Hungary
   *
   * 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.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
   *
   * Authors: Artem Bityutskiy (Битюцкий Артём)
   *          Adrian Hunter
   *          Zoltan Sogor
   */
  
  /*
   * This file implements directory operations.
   *
   * All FS operations in this file allocate budget before writing anything to the
   * media. If they fail to allocate it, the error is returned. The only
   * exceptions are 'ubifs_unlink()' and 'ubifs_rmdir()' which keep working even
   * if they unable to allocate the budget, because deletion %-ENOSPC failure is
   * not what users are usually ready to get. UBIFS budgeting subsystem has some
   * space reserved for these purposes.
   *
   * All operations in this file write all inodes which they change straight
   * away, instead of marking them dirty. For example, 'ubifs_link()' changes
   * @i_size of the parent inode and writes the parent inode together with the
   * target inode. This was done to simplify file-system recovery which would
   * otherwise be very difficult to do. The only exception is rename which marks
   * the re-named inode dirty (because its @i_ctime is updated) but does not
   * write it, but just marks it as dirty.
   */
  
  #include "ubifs.h"
  
  /**
   * inherit_flags - inherit flags of the parent inode.
   * @dir: parent inode
   * @mode: new inode mode flags
   *
   * This is a helper function for 'ubifs_new_inode()' which inherits flag of the
   * parent directory inode @dir. UBIFS inodes inherit the following flags:
   * o %UBIFS_COMPR_FL, which is useful to switch compression on/of on
   *   sub-directory basis;
   * o %UBIFS_SYNC_FL - useful for the same reasons;
   * o %UBIFS_DIRSYNC_FL - similar, but relevant only to directories.
   *
   * This function returns the inherited flags.
   */
  static int inherit_flags(const struct inode *dir, umode_t mode)
  {
  	int flags;
  	const struct ubifs_inode *ui = ubifs_inode(dir);
  
  	if (!S_ISDIR(dir->i_mode))
  		/*
  		 * The parent is not a directory, which means that an extended
  		 * attribute inode is being created. No flags.
  		 */
  		return 0;
  
  	flags = ui->flags & (UBIFS_COMPR_FL | UBIFS_SYNC_FL | UBIFS_DIRSYNC_FL);
  	if (!S_ISDIR(mode))
  		/* The "DIRSYNC" flag only applies to directories */
  		flags &= ~UBIFS_DIRSYNC_FL;
  	return flags;
  }
  
  /**
   * ubifs_new_inode - allocate new UBIFS inode object.
   * @c: UBIFS file-system description object
   * @dir: parent directory inode
   * @mode: inode mode flags
   *
   * This function finds an unused inode number, allocates new inode and
   * initializes it. Returns new inode in case of success and an error code in
   * case of failure.
   */
  struct inode *ubifs_new_inode(struct ubifs_info *c, const struct inode *dir,
  			      umode_t mode)
  {
  	struct inode *inode;
  	struct ubifs_inode *ui;
  
  	inode = new_inode(c->vfs_sb);
  	ui = ubifs_inode(inode);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  
  	/*
  	 * Set 'S_NOCMTIME' to prevent VFS form updating [mc]time of inodes and
  	 * marking them dirty in file write path (see 'file_update_time()').
  	 * UBIFS has to fully control "clean <-> dirty" transitions of inodes
  	 * to make budgeting work.
  	 */
  	inode->i_flags |= S_NOCMTIME;
  
  	inode_init_owner(inode, dir, mode);
  	inode->i_mtime = inode->i_atime = inode->i_ctime =
  			 ubifs_current_time(inode);
  	inode->i_mapping->nrpages = 0;
  	/* Disable readahead */
  	inode->i_mapping->backing_dev_info = &c->bdi;
  
  	switch (mode & S_IFMT) {
  	case S_IFREG:
  		inode->i_mapping->a_ops = &ubifs_file_address_operations;
  		inode->i_op = &ubifs_file_inode_operations;
  		inode->i_fop = &ubifs_file_operations;
  		break;
  	case S_IFDIR:
  		inode->i_op  = &ubifs_dir_inode_operations;
  		inode->i_fop = &ubifs_dir_operations;
  		inode->i_size = ui->ui_size = UBIFS_INO_NODE_SZ;
  		break;
  	case S_IFLNK:
  		inode->i_op = &ubifs_symlink_inode_operations;
  		break;
  	case S_IFSOCK:
  	case S_IFIFO:
  	case S_IFBLK:
  	case S_IFCHR:
  		inode->i_op  = &ubifs_file_inode_operations;
  		break;
  	default:
  		BUG();
  	}
  
  	ui->flags = inherit_flags(dir, mode);
  	ubifs_set_inode_flags(inode);
  	if (S_ISREG(mode))
  		ui->compr_type = c->default_compr;
  	else
  		ui->compr_type = UBIFS_COMPR_NONE;
  	ui->synced_i_size = 0;
  
  	spin_lock(&c->cnt_lock);
  	/* Inode number overflow is currently not supported */
  	if (c->highest_inum >= INUM_WARN_WATERMARK) {
  		if (c->highest_inum >= INUM_WATERMARK) {
  			spin_unlock(&c->cnt_lock);
  			ubifs_err("out of inode numbers", c->vi.ubi_num);
  			make_bad_inode(inode);
  			iput(inode);
  			return ERR_PTR(-EINVAL);
  		}
  		ubifs_warn("running out of inode numbers (current %lu, max %d)",
  				c->vi.ubi_num, (unsigned long)c->highest_inum,
  				INUM_WATERMARK);
  	}
  
  	inode->i_ino = ++c->highest_inum;
  	/*
  	 * The creation sequence number remains with this inode for its
  	 * lifetime. All nodes for this inode have a greater sequence number,
  	 * and so it is possible to distinguish obsolete nodes belonging to a
  	 * previous incarnation of the same inode number - for example, for the
  	 * purpose of rebuilding the index.
  	 */
  	ui->creat_sqnum = ++c->max_sqnum;
  	spin_unlock(&c->cnt_lock);
  	return inode;
  }
  
  static int dbg_check_name(const struct ubifs_info *c,
  			  const struct ubifs_dent_node *dent,
  			  const struct qstr *nm)
  {
  	if (!dbg_is_chk_gen(c))
  		return 0;
  	if (le16_to_cpu(dent->nlen) != nm->len)
  		return -EINVAL;
  	if (memcmp(dent->name, nm->name, nm->len))
  		return -EINVAL;
  	return 0;
  }
  
  static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
  				   unsigned int flags)
  {
  	int err;
  	union ubifs_key key;
  	struct inode *inode = NULL;
  	struct ubifs_dent_node *dent;
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  
  	dbg_gen("'%.*s' in dir ino %lu",
  		dentry->d_name.len, dentry->d_name.name, dir->i_ino);
  
  	if (dentry->d_name.len > UBIFS_MAX_NLEN)
  		return ERR_PTR(-ENAMETOOLONG);
  
  	dent = kmalloc(UBIFS_MAX_DENT_NODE_SZ, GFP_NOFS);
  	if (!dent)
  		return ERR_PTR(-ENOMEM);
  
  	dent_key_init(c, &key, dir->i_ino, &dentry->d_name);
  
  	err = ubifs_tnc_lookup_nm(c, &key, dent, &dentry->d_name);
  	if (err) {
  		if (err == -ENOENT) {
  			dbg_gen("not found");
  			goto done;
  		}
  		goto out;
  	}
  
  	if (dbg_check_name(c, dent, &dentry->d_name)) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	inode = ubifs_iget(dir->i_sb, le64_to_cpu(dent->inum));
  	if (IS_ERR(inode)) {
  		/*
  		 * This should not happen. Probably the file-system needs
  		 * checking.
  		 */
  		err = PTR_ERR(inode);
  		ubifs_err("dead directory entry '%.*s', error %d",
  			  c->vi.ubi_num, dentry->d_name.len,
  			  dentry->d_name.name, err);
  		ubifs_ro_mode(c, err);
  		goto out;
  	}
  
  done:
  	kfree(dent);
  	/*
  	 * Note, d_splice_alias() would be required instead if we supported
  	 * NFS.
  	 */
  	d_add(dentry, inode);
  	return NULL;
  
  out:
  	kfree(dent);
  	return ERR_PTR(err);
  }
  
  static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
  			bool excl)
  {
  	struct inode *inode;
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	int err, sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
  					.dirtied_ino = 1 };
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  
  	/*
  	 * Budget request settings: new inode, new direntry, changing the
  	 * parent directory inode.
  	 */
  
  	dbg_gen("dent '%.*s', mode %#hx in dir ino %lu",
  		dentry->d_name.len, dentry->d_name.name, mode, dir->i_ino);
  
  	err = ubifs_budget_space(c, &req);
  	if (err)
  		return err;
  
  	inode = ubifs_new_inode(c, dir, mode);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		goto out_budg;
  	}
  
  	mutex_lock(&dir_ui->ui_mutex);
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
  	if (err)
  		goto out_cancel;
  	mutex_unlock(&dir_ui->ui_mutex);
  
  	ubifs_release_budget(c, &req);
  	insert_inode_hash(inode);
  	d_instantiate(dentry, inode);
  	return 0;
  
  out_cancel:
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	mutex_unlock(&dir_ui->ui_mutex);
  	make_bad_inode(inode);
  	iput(inode);
  out_budg:
  	ubifs_release_budget(c, &req);
  	ubifs_err("cannot create regular file, error %d", c->vi.ubi_num, err);
  	return err;
  }
  
  /**
   * vfs_dent_type - get VFS directory entry type.
   * @type: UBIFS directory entry type
   *
   * This function converts UBIFS directory entry type into VFS directory entry
   * type.
   */
  static unsigned int vfs_dent_type(uint8_t type)
  {
  	switch (type) {
  	case UBIFS_ITYPE_REG:
  		return DT_REG;
  	case UBIFS_ITYPE_DIR:
  		return DT_DIR;
  	case UBIFS_ITYPE_LNK:
  		return DT_LNK;
  	case UBIFS_ITYPE_BLK:
  		return DT_BLK;
  	case UBIFS_ITYPE_CHR:
  		return DT_CHR;
  	case UBIFS_ITYPE_FIFO:
  		return DT_FIFO;
  	case UBIFS_ITYPE_SOCK:
  		return DT_SOCK;
  	default:
  		BUG();
  	}
  	return 0;
  }
  
  /*
   * The classical Unix view for directory is that it is a linear array of
   * (name, inode number) entries. Linux/VFS assumes this model as well.
   * Particularly, 'readdir()' call wants us to return a directory entry offset
   * which later may be used to continue 'readdir()'ing the directory or to
   * 'seek()' to that specific direntry. Obviously UBIFS does not really fit this
   * model because directory entries are identified by keys, which may collide.
   *
   * UBIFS uses directory entry hash value for directory offsets, so
   * 'seekdir()'/'telldir()' may not always work because of possible key
   * collisions. But UBIFS guarantees that consecutive 'readdir()' calls work
   * properly by means of saving full directory entry name in the private field
   * of the file description object.
   *
   * This means that UBIFS cannot support NFS which requires full
   * 'seekdir()'/'telldir()' support.
   */
  static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir)
  {
  	int err, over = 0;
  	loff_t pos = file->f_pos;
  	struct qstr nm;
  	union ubifs_key key;
  	struct ubifs_dent_node *dent;
  	struct inode *dir = file_inode(file);
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  
  	dbg_gen("dir ino %lu, f_pos %#llx", dir->i_ino, pos);
  
  	if (pos > UBIFS_S_KEY_HASH_MASK || pos == 2)
  		/*
  		 * The directory was seek'ed to a senseless position or there
  		 * are no more entries.
  		 */
  		return 0;
  
  	if (file->f_version == 0) {
  		/*
  		 * The file was seek'ed, which means that @file->private_data
  		 * is now invalid. This may also be just the first
  		 * 'ubifs_readdir()' invocation, in which case
  		 * @file->private_data is NULL, and the below code is
  		 * basically a no-op.
  		 */
  		kfree(file->private_data);
  		file->private_data = NULL;
  	}
  
  	/*
  	 * 'generic_file_llseek()' unconditionally sets @file->f_version to
  	 * zero, and we use this for detecting whether the file was seek'ed.
  	 */
  	file->f_version = 1;
  
  	/* File positions 0 and 1 correspond to "." and ".." */
  	if (pos == 0) {
  		ubifs_assert(!file->private_data);
  		over = filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR);
  		if (over)
  			return 0;
  		file->f_pos = pos = 1;
  	}
  
  	if (pos == 1) {
  		ubifs_assert(!file->private_data);
  		over = filldir(dirent, "..", 2, 1,
  			       parent_ino(file->f_path.dentry), DT_DIR);
  		if (over)
  			return 0;
  
  		/* Find the first entry in TNC and save it */
  		lowest_dent_key(c, &key, dir->i_ino);
  		nm.name = NULL;
  		dent = ubifs_tnc_next_ent(c, &key, &nm);
  		if (IS_ERR(dent)) {
  			err = PTR_ERR(dent);
  			goto out;
  		}
  
  		file->f_pos = pos = key_hash_flash(c, &dent->key);
  		file->private_data = dent;
  	}
  
  	dent = file->private_data;
  	if (!dent) {
  		/*
  		 * The directory was seek'ed to and is now readdir'ed.
  		 * Find the entry corresponding to @pos or the closest one.
  		 */
  		dent_key_init_hash(c, &key, dir->i_ino, pos);
  		nm.name = NULL;
  		dent = ubifs_tnc_next_ent(c, &key, &nm);
  		if (IS_ERR(dent)) {
  			err = PTR_ERR(dent);
  			goto out;
  		}
  		file->f_pos = pos = key_hash_flash(c, &dent->key);
  		file->private_data = dent;
  	}
  
  	while (1) {
  		dbg_gen("feed '%s', ino %llu, new f_pos %#x",
  			dent->name, (unsigned long long)le64_to_cpu(dent->inum),
  			key_hash_flash(c, &dent->key));
  		ubifs_assert(le64_to_cpu(dent->ch.sqnum) >
  			     ubifs_inode(dir)->creat_sqnum);
  
  		nm.len = le16_to_cpu(dent->nlen);
  		over = filldir(dirent, dent->name, nm.len, pos,
  			       le64_to_cpu(dent->inum),
  			       vfs_dent_type(dent->type));
  		if (over)
  			return 0;
  
  		/* Switch to the next entry */
  		key_read(c, &dent->key, &key);
  		nm.name = dent->name;
  		dent = ubifs_tnc_next_ent(c, &key, &nm);
  		if (IS_ERR(dent)) {
  			err = PTR_ERR(dent);
  			goto out;
  		}
  
  		kfree(file->private_data);
  		file->f_pos = pos = key_hash_flash(c, &dent->key);
  		file->private_data = dent;
  		cond_resched();
  
  		if (file->f_version == 0)
  			/*
  			 * The file was seek'ed meanwhile, lets return and start
  			 * reading direntries from the new position on the next
  			 * invocation.
  			 */
  			return 0;
  	}
  
  out:
  	if (err != -ENOENT) {
  		ubifs_err("cannot find next direntry, error %d", c->vi.ubi_num,
  				err);
  		return err;
  	}
  
  	kfree(file->private_data);
  	file->private_data = NULL;
  	/* 2 is a special value indicating that there are no more direntries */
  	file->f_pos = 2;
  	return 0;
  }
  
  static loff_t ubifs_dir_llseek(struct file *file, loff_t offset, int whence)
  {
  	return generic_file_llseek(file, offset, whence);
  }
  
  /* Free saved readdir() state when the directory is closed */
  static int ubifs_dir_release(struct inode *dir, struct file *file)
  {
  	kfree(file->private_data);
  	file->private_data = NULL;
  	return 0;
  }
  
  /**
   * lock_2_inodes - a wrapper for locking two UBIFS inodes.
   * @inode1: first inode
   * @inode2: second inode
   *
   * We do not implement any tricks to guarantee strict lock ordering, because
   * VFS has already done it for us on the @i_mutex. So this is just a simple
   * wrapper function.
   */
  static void lock_2_inodes(struct inode *inode1, struct inode *inode2)
  {
  	mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
  	mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
  }
  
  /**
   * unlock_2_inodes - a wrapper for unlocking two UBIFS inodes.
   * @inode1: first inode
   * @inode2: second inode
   */
  static void unlock_2_inodes(struct inode *inode1, struct inode *inode2)
  {
  	mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
  	mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
  }
  
  static int ubifs_link(struct dentry *old_dentry, struct inode *dir,
  		      struct dentry *dentry)
  {
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	struct inode *inode = old_dentry->d_inode;
  	struct ubifs_inode *ui = ubifs_inode(inode);
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  	int err, sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	struct ubifs_budget_req req = { .new_dent = 1, .dirtied_ino = 2,
  				.dirtied_ino_d = ALIGN(ui->data_len, 8) };
  
  	/*
  	 * Budget request settings: new direntry, changing the target inode,
  	 * changing the parent inode.
  	 */
  
  	dbg_gen("dent '%.*s' to ino %lu (nlink %d) in dir ino %lu",
  		dentry->d_name.len, dentry->d_name.name, inode->i_ino,
  		inode->i_nlink, dir->i_ino);
  	ubifs_assert(mutex_is_locked(&dir->i_mutex));
  	ubifs_assert(mutex_is_locked(&inode->i_mutex));
  
  	err = dbg_check_synced_i_size(c, inode);
  	if (err)
  		return err;
  
  	err = ubifs_budget_space(c, &req);
  	if (err)
  		return err;
  
  	lock_2_inodes(dir, inode);
  	inc_nlink(inode);
  	ihold(inode);
  	inode->i_ctime = ubifs_current_time(inode);
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
  	if (err)
  		goto out_cancel;
  	unlock_2_inodes(dir, inode);
  
  	ubifs_release_budget(c, &req);
  	d_instantiate(dentry, inode);
  	return 0;
  
  out_cancel:
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	drop_nlink(inode);
  	unlock_2_inodes(dir, inode);
  	ubifs_release_budget(c, &req);
  	iput(inode);
  	return err;
  }
  
  static int ubifs_unlink(struct inode *dir, struct dentry *dentry)
  {
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	struct inode *inode = dentry->d_inode;
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  	int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	int err, budgeted = 1;
  	struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };
  	unsigned int saved_nlink = inode->i_nlink;
  
  	/*
  	 * Budget request settings: deletion direntry, deletion inode (+1 for
  	 * @dirtied_ino), changing the parent directory inode. If budgeting
  	 * fails, go ahead anyway because we have extra space reserved for
  	 * deletions.
  	 */
  
  	dbg_gen("dent '%.*s' from ino %lu (nlink %d) in dir ino %lu",
  		dentry->d_name.len, dentry->d_name.name, inode->i_ino,
  		inode->i_nlink, dir->i_ino);
  	ubifs_assert(mutex_is_locked(&dir->i_mutex));
  	ubifs_assert(mutex_is_locked(&inode->i_mutex));
  	err = dbg_check_synced_i_size(c, inode);
  	if (err)
  		return err;
  
  	err = ubifs_budget_space(c, &req);
  	if (err) {
  		if (err != -ENOSPC)
  			return err;
  		budgeted = 0;
  	}
  
  	lock_2_inodes(dir, inode);
  	inode->i_ctime = ubifs_current_time(dir);
  	drop_nlink(inode);
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 1, 0);
  	if (err)
  		goto out_cancel;
  	unlock_2_inodes(dir, inode);
  
  	if (budgeted)
  		ubifs_release_budget(c, &req);
  	else {
  		/* We've deleted something - clean the "no space" flags */
  		c->bi.nospace = c->bi.nospace_rp = 0;
  		smp_wmb();
  	}
  	return 0;
  
  out_cancel:
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	set_nlink(inode, saved_nlink);
  	unlock_2_inodes(dir, inode);
  	if (budgeted)
  		ubifs_release_budget(c, &req);
  	return err;
  }
  
  /**
   * check_dir_empty - check if a directory is empty or not.
   * @c: UBIFS file-system description object
   * @dir: VFS inode object of the directory to check
   *
   * This function checks if directory @dir is empty. Returns zero if the
   * directory is empty, %-ENOTEMPTY if it is not, and other negative error codes
   * in case of of errors.
   */
  static int check_dir_empty(struct ubifs_info *c, struct inode *dir)
  {
  	struct qstr nm = { .name = NULL };
  	struct ubifs_dent_node *dent;
  	union ubifs_key key;
  	int err;
  
  	lowest_dent_key(c, &key, dir->i_ino);
  	dent = ubifs_tnc_next_ent(c, &key, &nm);
  	if (IS_ERR(dent)) {
  		err = PTR_ERR(dent);
  		if (err == -ENOENT)
  			err = 0;
  	} else {
  		kfree(dent);
  		err = -ENOTEMPTY;
  	}
  	return err;
  }
  
  static int ubifs_rmdir(struct inode *dir, struct dentry *dentry)
  {
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	struct inode *inode = dentry->d_inode;
  	int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	int err, budgeted = 1;
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  	struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };
  
  	/*
  	 * Budget request settings: deletion direntry, deletion inode and
  	 * changing the parent inode. If budgeting fails, go ahead anyway
  	 * because we have extra space reserved for deletions.
  	 */
  
  	dbg_gen("directory '%.*s', ino %lu in dir ino %lu", dentry->d_name.len,
  		dentry->d_name.name, inode->i_ino, dir->i_ino);
  	ubifs_assert(mutex_is_locked(&dir->i_mutex));
  	ubifs_assert(mutex_is_locked(&inode->i_mutex));
  	err = check_dir_empty(c, dentry->d_inode);
  	if (err)
  		return err;
  
  	err = ubifs_budget_space(c, &req);
  	if (err) {
  		if (err != -ENOSPC)
  			return err;
  		budgeted = 0;
  	}
  
  	lock_2_inodes(dir, inode);
  	inode->i_ctime = ubifs_current_time(dir);
  	clear_nlink(inode);
  	drop_nlink(dir);
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 1, 0);
  	if (err)
  		goto out_cancel;
  	unlock_2_inodes(dir, inode);
  
  	if (budgeted)
  		ubifs_release_budget(c, &req);
  	else {
  		/* We've deleted something - clean the "no space" flags */
  		c->bi.nospace = c->bi.nospace_rp = 0;
  		smp_wmb();
  	}
  	return 0;
  
  out_cancel:
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	inc_nlink(dir);
  	set_nlink(inode, 2);
  	unlock_2_inodes(dir, inode);
  	if (budgeted)
  		ubifs_release_budget(c, &req);
  	return err;
  }
  
  static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
  {
  	struct inode *inode;
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	int err, sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1 };
  
  	/*
  	 * Budget request settings: new inode, new direntry and changing parent
  	 * directory inode.
  	 */
  
  	dbg_gen("dent '%.*s', mode %#hx in dir ino %lu",
  		dentry->d_name.len, dentry->d_name.name, mode, dir->i_ino);
  
  	err = ubifs_budget_space(c, &req);
  	if (err)
  		return err;
  
  	inode = ubifs_new_inode(c, dir, S_IFDIR | mode);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		goto out_budg;
  	}
  
  	mutex_lock(&dir_ui->ui_mutex);
  	insert_inode_hash(inode);
  	inc_nlink(inode);
  	inc_nlink(dir);
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
  	if (err) {
  		ubifs_err("cannot create directory, error %d", c->vi.ubi_num,
  				err);
  		goto out_cancel;
  	}
  	mutex_unlock(&dir_ui->ui_mutex);
  
  	ubifs_release_budget(c, &req);
  	d_instantiate(dentry, inode);
  	return 0;
  
  out_cancel:
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	drop_nlink(dir);
  	mutex_unlock(&dir_ui->ui_mutex);
  	make_bad_inode(inode);
  	iput(inode);
  out_budg:
  	ubifs_release_budget(c, &req);
  	return err;
  }
  
  static int ubifs_mknod(struct inode *dir, struct dentry *dentry,
  		       umode_t mode, dev_t rdev)
  {
  	struct inode *inode;
  	struct ubifs_inode *ui;
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	union ubifs_dev_desc *dev = NULL;
  	int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	int err, devlen = 0;
  	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
  					.new_ino_d = ALIGN(devlen, 8),
  					.dirtied_ino = 1 };
  
  	/*
  	 * Budget request settings: new inode, new direntry and changing parent
  	 * directory inode.
  	 */
  
  	dbg_gen("dent '%.*s' in dir ino %lu",
  		dentry->d_name.len, dentry->d_name.name, dir->i_ino);
  
  	if (!new_valid_dev(rdev))
  		return -EINVAL;
  
  	if (S_ISBLK(mode) || S_ISCHR(mode)) {
  		dev = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
  		if (!dev)
  			return -ENOMEM;
  		devlen = ubifs_encode_dev(dev, rdev);
  	}
  
  	err = ubifs_budget_space(c, &req);
  	if (err) {
  		kfree(dev);
  		return err;
  	}
  
  	inode = ubifs_new_inode(c, dir, mode);
  	if (IS_ERR(inode)) {
  		kfree(dev);
  		err = PTR_ERR(inode);
  		goto out_budg;
  	}
  
  	init_special_inode(inode, inode->i_mode, rdev);
  	inode->i_size = ubifs_inode(inode)->ui_size = devlen;
  	ui = ubifs_inode(inode);
  	ui->data = dev;
  	ui->data_len = devlen;
  
  	mutex_lock(&dir_ui->ui_mutex);
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
  	if (err)
  		goto out_cancel;
  	mutex_unlock(&dir_ui->ui_mutex);
  
  	ubifs_release_budget(c, &req);
  	insert_inode_hash(inode);
  	d_instantiate(dentry, inode);
  	return 0;
  
  out_cancel:
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	mutex_unlock(&dir_ui->ui_mutex);
  	make_bad_inode(inode);
  	iput(inode);
  out_budg:
  	ubifs_release_budget(c, &req);
  	return err;
  }
  
  static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
  			 const char *symname)
  {
  	struct inode *inode;
  	struct ubifs_inode *ui;
  	struct ubifs_inode *dir_ui = ubifs_inode(dir);
  	struct ubifs_info *c = dir->i_sb->s_fs_info;
  	int err, len = strlen(symname);
  	int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
  	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
  					.new_ino_d = ALIGN(len, 8),
  					.dirtied_ino = 1 };
  
  	/*
  	 * Budget request settings: new inode, new direntry and changing parent
  	 * directory inode.
  	 */
  
  	dbg_gen("dent '%.*s', target '%s' in dir ino %lu", dentry->d_name.len,
  		dentry->d_name.name, symname, dir->i_ino);
  
  	if (len > UBIFS_MAX_INO_DATA)
  		return -ENAMETOOLONG;
  
  	err = ubifs_budget_space(c, &req);
  	if (err)
  		return err;
  
  	inode = ubifs_new_inode(c, dir, S_IFLNK | S_IRWXUGO);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		goto out_budg;
  	}
  
  	ui = ubifs_inode(inode);
  	ui->data = kmalloc(len + 1, GFP_NOFS);
  	if (!ui->data) {
  		err = -ENOMEM;
  		goto out_inode;
  	}
  
  	memcpy(ui->data, symname, len);
  	((char *)ui->data)[len] = '\0';
  	/*
  	 * The terminating zero byte is not written to the flash media and it
  	 * is put just to make later in-memory string processing simpler. Thus,
  	 * data length is @len, not @len + %1.
  	 */
  	ui->data_len = len;
  	inode->i_size = ubifs_inode(inode)->ui_size = len;
  
  	mutex_lock(&dir_ui->ui_mutex);
  	dir->i_size += sz_change;
  	dir_ui->ui_size = dir->i_size;
  	dir->i_mtime = dir->i_ctime = inode->i_ctime;
  	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
  	if (err)
  		goto out_cancel;
  	mutex_unlock(&dir_ui->ui_mutex);
  
  	ubifs_release_budget(c, &req);
  	insert_inode_hash(inode);
  	d_instantiate(dentry, inode);
  	return 0;
  
  out_cancel:
  	dir->i_size -= sz_change;
  	dir_ui->ui_size = dir->i_size;
  	mutex_unlock(&dir_ui->ui_mutex);
  out_inode:
  	make_bad_inode(inode);
  	iput(inode);
  out_budg:
  	ubifs_release_budget(c, &req);
  	return err;
  }
  
  /**
   * lock_3_inodes - a wrapper for locking three UBIFS inodes.
   * @inode1: first inode
   * @inode2: second inode
   * @inode3: third inode
   *
   * This function is used for 'ubifs_rename()' and @inode1 may be the same as
   * @inode2 whereas @inode3 may be %NULL.
   *
   * We do not implement any tricks to guarantee strict lock ordering, because
   * VFS has already done it for us on the @i_mutex. So this is just a simple
   * wrapper function.
   */
  static void lock_3_inodes(struct inode *inode1, struct inode *inode2,
  			  struct inode *inode3)
  {
  	mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
  	if (inode2 != inode1)
  		mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
  	if (inode3)
  		mutex_lock_nested(&ubifs_inode(inode3)->ui_mutex, WB_MUTEX_3);
  }
  
  /**
   * unlock_3_inodes - a wrapper for unlocking three UBIFS inodes for rename.
   * @inode1: first inode
   * @inode2: second inode
   * @inode3: third inode
   */
  static void unlock_3_inodes(struct inode *inode1, struct inode *inode2,
  			    struct inode *inode3)
  {
  	if (inode3)
  		mutex_unlock(&ubifs_inode(inode3)->ui_mutex);
  	if (inode1 != inode2)
  		mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
  	mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
  }
  
  static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry,
  			struct inode *new_dir, struct dentry *new_dentry)
  {
  	struct ubifs_info *c = old_dir->i_sb->s_fs_info;
  	struct inode *old_inode = old_dentry->d_inode;
  	struct inode *new_inode = new_dentry->d_inode;
  	struct ubifs_inode *old_inode_ui = ubifs_inode(old_inode);
  	int err, release, sync = 0, move = (new_dir != old_dir);
  	int is_dir = S_ISDIR(old_inode->i_mode);
  	int unlink = !!new_inode;
  	int new_sz = CALC_DENT_SIZE(new_dentry->d_name.len);
  	int old_sz = CALC_DENT_SIZE(old_dentry->d_name.len);
  	struct ubifs_budget_req req = { .new_dent = 1, .mod_dent = 1,
  					.dirtied_ino = 3 };
  	struct ubifs_budget_req ino_req = { .dirtied_ino = 1,
  			.dirtied_ino_d = ALIGN(old_inode_ui->data_len, 8) };
  	struct timespec time;
  	unsigned int uninitialized_var(saved_nlink);
  
  	/*
  	 * Budget request settings: deletion direntry, new direntry, removing
  	 * the old inode, and changing old and new parent directory inodes.
  	 *
  	 * However, this operation also marks the target inode as dirty and
  	 * does not write it, so we allocate budget for the target inode
  	 * separately.
  	 */
  
  	dbg_gen("dent '%.*s' ino %lu in dir ino %lu to dent '%.*s' in dir ino %lu",
  		old_dentry->d_name.len, old_dentry->d_name.name,
  		old_inode->i_ino, old_dir->i_ino, new_dentry->d_name.len,
  		new_dentry->d_name.name, new_dir->i_ino);
  	ubifs_assert(mutex_is_locked(&old_dir->i_mutex));
  	ubifs_assert(mutex_is_locked(&new_dir->i_mutex));
  	if (unlink)
  		ubifs_assert(mutex_is_locked(&new_inode->i_mutex));
  
  
  	if (unlink && is_dir) {
  		err = check_dir_empty(c, new_inode);
  		if (err)
  			return err;
  	}
  
  	err = ubifs_budget_space(c, &req);
  	if (err)
  		return err;
  	err = ubifs_budget_space(c, &ino_req);
  	if (err) {
  		ubifs_release_budget(c, &req);
  		return err;
  	}
  
  	lock_3_inodes(old_dir, new_dir, new_inode);
  
  	/*
  	 * Like most other Unix systems, set the @i_ctime for inodes on a
  	 * rename.
  	 */
  	time = ubifs_current_time(old_dir);
  	old_inode->i_ctime = time;
  
  	/* We must adjust parent link count when renaming directories */
  	if (is_dir) {
  		if (move) {
  			/*
  			 * @old_dir loses a link because we are moving
  			 * @old_inode to a different directory.
  			 */
  			drop_nlink(old_dir);
  			/*
  			 * @new_dir only gains a link if we are not also
  			 * overwriting an existing directory.
  			 */
  			if (!unlink)
  				inc_nlink(new_dir);
  		} else {
  			/*
  			 * @old_inode is not moving to a different directory,
  			 * but @old_dir still loses a link if we are
  			 * overwriting an existing directory.
  			 */
  			if (unlink)
  				drop_nlink(old_dir);
  		}
  	}
  
  	old_dir->i_size -= old_sz;
  	ubifs_inode(old_dir)->ui_size = old_dir->i_size;
  	old_dir->i_mtime = old_dir->i_ctime = time;
  	new_dir->i_mtime = new_dir->i_ctime = time;
  
  	/*
  	 * And finally, if we unlinked a direntry which happened to have the
  	 * same name as the moved direntry, we have to decrement @i_nlink of
  	 * the unlinked inode and change its ctime.
  	 */
  	if (unlink) {
  		/*
  		 * Directories cannot have hard-links, so if this is a
  		 * directory, just clear @i_nlink.
  		 */
  		saved_nlink = new_inode->i_nlink;
  		if (is_dir)
  			clear_nlink(new_inode);
  		else
  			drop_nlink(new_inode);
  		new_inode->i_ctime = time;
  	} else {
  		new_dir->i_size += new_sz;
  		ubifs_inode(new_dir)->ui_size = new_dir->i_size;
  	}
  
  	/*
  	 * Do not ask 'ubifs_jnl_rename()' to flush write-buffer if @old_inode
  	 * is dirty, because this will be done later on at the end of
  	 * 'ubifs_rename()'.
  	 */
  	if (IS_SYNC(old_inode)) {
  		sync = IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir);
  		if (unlink && IS_SYNC(new_inode))
  			sync = 1;
  	}
  	err = ubifs_jnl_rename(c, old_dir, old_dentry, new_dir, new_dentry,
  			       sync);
  	if (err)
  		goto out_cancel;
  
  	unlock_3_inodes(old_dir, new_dir, new_inode);
  	ubifs_release_budget(c, &req);
  
  	mutex_lock(&old_inode_ui->ui_mutex);
  	release = old_inode_ui->dirty;
  	mark_inode_dirty_sync(old_inode);
  	mutex_unlock(&old_inode_ui->ui_mutex);
  
  	if (release)
  		ubifs_release_budget(c, &ino_req);
  	if (IS_SYNC(old_inode))
  		err = old_inode->i_sb->s_op->write_inode(old_inode, NULL);
  	return err;
  
  out_cancel:
  	if (unlink) {
  		set_nlink(new_inode, saved_nlink);
  	} else {
  		new_dir->i_size -= new_sz;
  		ubifs_inode(new_dir)->ui_size = new_dir->i_size;
  	}
  	old_dir->i_size += old_sz;
  	ubifs_inode(old_dir)->ui_size = old_dir->i_size;
  	if (is_dir) {
  		if (move) {
  			inc_nlink(old_dir);
  			if (!unlink)
  				drop_nlink(new_dir);
  		} else {
  			if (unlink)
  				inc_nlink(old_dir);
  		}
  	}
  	unlock_3_inodes(old_dir, new_dir, new_inode);
  	ubifs_release_budget(c, &ino_req);
  	ubifs_release_budget(c, &req);
  	return err;
  }
  
  int ubifs_getattr(struct vfsmount *mnt, struct dentry *dentry,
  		  struct kstat *stat)
  {
  	loff_t size;
  	struct inode *inode = dentry->d_inode;
  	struct ubifs_inode *ui = ubifs_inode(inode);
  
  	mutex_lock(&ui->ui_mutex);
  	generic_fillattr(inode, stat);
  	stat->blksize = UBIFS_BLOCK_SIZE;
  	stat->size = ui->ui_size;
  
  	/*
  	 * Unfortunately, the 'stat()' system call was designed for block
  	 * device based file systems, and it is not appropriate for UBIFS,
  	 * because UBIFS does not have notion of "block". For example, it is
  	 * difficult to tell how many block a directory takes - it actually
  	 * takes less than 300 bytes, but we have to round it to block size,
  	 * which introduces large mistake. This makes utilities like 'du' to
  	 * report completely senseless numbers. This is the reason why UBIFS
  	 * goes the same way as JFFS2 - it reports zero blocks for everything
  	 * but regular files, which makes more sense than reporting completely
  	 * wrong sizes.
  	 */
  	if (S_ISREG(inode->i_mode)) {
  		size = ui->xattr_size;
  		size += stat->size;
  		size = ALIGN(size, UBIFS_BLOCK_SIZE);
  		/*
  		 * Note, user-space expects 512-byte blocks count irrespectively
  		 * of what was reported in @stat->size.
  		 */
  		stat->blocks = size >> 9;
  	} else
  		stat->blocks = 0;
  	mutex_unlock(&ui->ui_mutex);
  	return 0;
  }
  
  const struct inode_operations ubifs_dir_inode_operations = {
  	.lookup      = ubifs_lookup,
  	.create      = ubifs_create,
  	.link        = ubifs_link,
  	.symlink     = ubifs_symlink,
  	.unlink      = ubifs_unlink,
  	.mkdir       = ubifs_mkdir,
  	.rmdir       = ubifs_rmdir,
  	.mknod       = ubifs_mknod,
  	.rename      = ubifs_rename,
  	.setattr     = ubifs_setattr,
  	.getattr     = ubifs_getattr,
  	.setxattr    = ubifs_setxattr,
  	.getxattr    = ubifs_getxattr,
  	.listxattr   = ubifs_listxattr,
  	.removexattr = ubifs_removexattr,
  };
  
  const struct file_operations ubifs_dir_operations = {
  	.llseek         = ubifs_dir_llseek,
  	.release        = ubifs_dir_release,
  	.read           = generic_read_dir,
  	.readdir        = ubifs_readdir,
  	.fsync          = ubifs_fsync,
  	.unlocked_ioctl = ubifs_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl   = ubifs_compat_ioctl,
  #endif
  };
  