ubifs: Massage ubifs_listxattr() for encryption context

[linux-block.git] / fs / ubifs / dir.c

/* * 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, struct inode *dir,
			      umode_t mode)
{
	int err;
	struct inode *inode;
	struct ubifs_inode *ui;
	bool encrypted = false;

	if (ubifs_crypt_is_encrypted(dir)) {
		err = fscrypt_get_encryption_info(dir);
		if (err) {
			ubifs_err(c, "fscrypt_get_encryption_info failed: %i", err);
			return ERR_PTR(err);
		}

		if (!fscrypt_has_encryption_key(dir))
			return ERR_PTR(-EPERM);

		encrypted = true;
	}

	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;

	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(c, "out of inode numbers");
			make_bad_inode(inode);
			iput(inode);
			return ERR_PTR(-EINVAL);
		}
		ubifs_warn(c, "running out of inode numbers (current %lu, max %u)",
			   (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);

	if (encrypted) {
		err = fscrypt_inherit_context(dir, inode, &encrypted, true);
		if (err) {
			ubifs_err(c, "fscrypt_inherit_context failed: %i", err);
			make_bad_inode(inode);
			iput(inode);
			return ERR_PTR(err);
		}
	}

	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("'%pd' in dir ino %lu", dentry, 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(c, "dead directory entry '%pd', error %d",
			  dentry, 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 '%pd', mode %#hx in dir ino %lu",
		dentry, 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;
	}

	err = ubifs_init_security(dir, inode, &dentry->d_name);
	if (err)
		goto out_inode;

	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);
	ubifs_err(c, "cannot create regular file, error %d", err);
	return err;
}

static int do_tmpfile(struct inode *dir, struct dentry *dentry,
		      umode_t mode, struct inode **whiteout)
{
	struct inode *inode;
	struct ubifs_info *c = dir->i_sb->s_fs_info;
	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1};
	struct ubifs_budget_req ino_req = { .dirtied_ino = 1 };
	struct ubifs_inode *ui, *dir_ui = ubifs_inode(dir);
	int err, instantiated = 0;

	/*
	 * Budget request settings: new dirty inode, new direntry,
	 * budget for dirtied inode will be released via writeback.
	 */

	dbg_gen("dent '%pd', mode %#hx in dir ino %lu",
		dentry, mode, dir->i_ino);

	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;
	}

	inode = ubifs_new_inode(c, dir, mode);
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto out_budg;
	}
	ui = ubifs_inode(inode);

	if (whiteout) {
		init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
		ubifs_assert(inode->i_op == &ubifs_file_inode_operations);
	}

	err = ubifs_init_security(dir, inode, &dentry->d_name);
	if (err)
		goto out_inode;

	mutex_lock(&ui->ui_mutex);
	insert_inode_hash(inode);

	if (whiteout) {
		mark_inode_dirty(inode);
		drop_nlink(inode);
		*whiteout = inode;
	} else {
		d_tmpfile(dentry, inode);
	}
	ubifs_assert(ui->dirty);

	instantiated = 1;
	mutex_unlock(&ui->ui_mutex);

	mutex_lock(&dir_ui->ui_mutex);
	err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 1, 0);
	if (err)
		goto out_cancel;
	mutex_unlock(&dir_ui->ui_mutex);

	ubifs_release_budget(c, &req);

	return 0;

out_cancel:
	mutex_unlock(&dir_ui->ui_mutex);
out_inode:
	make_bad_inode(inode);
	if (!instantiated)
		iput(inode);
out_budg:
	ubifs_release_budget(c, &req);
	if (!instantiated)
		ubifs_release_budget(c, &ino_req);
	ubifs_err(c, "cannot create temporary file, error %d", err);
	return err;
}

static int ubifs_tmpfile(struct inode *dir, struct dentry *dentry,
			 umode_t mode)
{
	return do_tmpfile(dir, dentry, mode, NULL);
}

/**
 * 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, struct dir_context *ctx)
{
	int err = 0;
	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, ctx->pos);

	if (ctx->pos > UBIFS_S_KEY_HASH_MASK || ctx->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 (ctx->pos < 2) {
		ubifs_assert(!file->private_data);
		if (!dir_emit_dots(file, ctx))
			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;
		}

		ctx->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 @ctx->pos or the closest one.
		 */
		dent_key_init_hash(c, &key, dir->i_ino, ctx->pos);
		nm.name = NULL;
		dent = ubifs_tnc_next_ent(c, &key, &nm);
		if (IS_ERR(dent)) {
			err = PTR_ERR(dent);
			goto out;
		}
		ctx->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);
		if (!dir_emit(ctx, dent->name, nm.len,
			       le64_to_cpu(dent->inum),
			       vfs_dent_type(dent->type)))
			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);
		ctx->pos = key_hash_flash(c, &dent->key);
		file->private_data = dent;
		cond_resched();
	}

out:
	kfree(file->private_data);
	file->private_data = NULL;

	if (err != -ENOENT)
		ubifs_err(c, "cannot find next direntry, error %d", err);
	else
		/*
		 * -ENOENT is a non-fatal error in this context, the TNC uses
		 * it to indicate that the cursor moved past the current directory
		 * and readdir() has to stop.
		 */
		err = 0;


	/* 2 is a special value indicating that there are no more direntries */
	ctx->pos = 2;
	return err;
}

/* 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 = d_inode(old_dentry);
	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 '%pd' to ino %lu (nlink %d) in dir ino %lu",
		dentry, inode->i_ino,
		inode->i_nlink, dir->i_ino);
	ubifs_assert(inode_is_locked(dir));
	ubifs_assert(inode_is_locked(inode));

	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 = d_inode(dentry);
	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 '%pd' from ino %lu (nlink %d) in dir ino %lu",
		dentry, inode->i_ino,
		inode->i_nlink, dir->i_ino);
	ubifs_assert(inode_is_locked(dir));
	ubifs_assert(inode_is_locked(inode));
	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.
 * @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.
 */
int ubifs_check_dir_empty(struct inode *dir)
{
	struct ubifs_info *c = dir->i_sb->s_fs_info;
	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 = d_inode(dentry);
	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 '%pd', ino %lu in dir ino %lu", dentry,
		inode->i_ino, dir->i_ino);
	ubifs_assert(inode_is_locked(dir));
	ubifs_assert(inode_is_locked(inode));
	err = ubifs_check_dir_empty(d_inode(dentry));
	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 '%pd', mode %#hx in dir ino %lu",
		dentry, 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;
	}

	err = ubifs_init_security(dir, inode, &dentry->d_name);
	if (err)
		goto out_inode;

	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(c, "cannot create directory, error %d", 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);
out_inode:
	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 '%pd' in dir ino %lu", dentry, dir->i_ino);

	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;

	err = ubifs_init_security(dir, inode, &dentry->d_name);
	if (err)
		goto out_inode;

	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;
}

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 '%pd', target '%s' in dir ino %lu", dentry,
		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';
	inode->i_link = ui->data;
	/*
	 * 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;

	err = ubifs_init_security(dir, inode, &dentry->d_name);
	if (err)
		goto out_inode;

	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_4_inodes - a wrapper for locking three UBIFS inodes.
 * @inode1: first inode
 * @inode2: second inode
 * @inode3: third inode
 * @inode4: fouth inode
 *
 * This function is used for 'ubifs_rename()' and @inode1 may be the same as
 * @inode2 whereas @inode3 and @inode4 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_4_inodes(struct inode *inode1, struct inode *inode2,
			  struct inode *inode3, struct inode *inode4)
{
	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);
	if (inode4)
		mutex_lock_nested(&ubifs_inode(inode4)->ui_mutex, WB_MUTEX_4);
}

/**
 * unlock_4_inodes - a wrapper for unlocking three UBIFS inodes for rename.
 * @inode1: first inode
 * @inode2: second inode
 * @inode3: third inode
 * @inode4: fouth inode
 */
static void unlock_4_inodes(struct inode *inode1, struct inode *inode2,
			    struct inode *inode3, struct inode *inode4)
{
	if (inode4)
		mutex_unlock(&ubifs_inode(inode4)->ui_mutex);
	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 do_rename(struct inode *old_dir, struct dentry *old_dentry,
		     struct inode *new_dir, struct dentry *new_dentry,
		     unsigned int flags)
{
	struct ubifs_info *c = old_dir->i_sb->s_fs_info;
	struct inode *old_inode = d_inode(old_dentry);
	struct inode *new_inode = d_inode(new_dentry);
	struct inode *whiteout = NULL;
	struct ubifs_inode *old_inode_ui = ubifs_inode(old_inode);
	struct ubifs_inode *whiteout_ui = NULL;
	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);

	if (flags & ~RENAME_NOREPLACE)
		return -EINVAL;

	/*
	 * 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 '%pd' ino %lu in dir ino %lu to dent '%pd' in dir ino %lu flags 0x%x",
		old_dentry, old_inode->i_ino, old_dir->i_ino,
		new_dentry, new_dir->i_ino, flags);

	if (unlink)
		ubifs_assert(inode_is_locked(new_inode));

	if (unlink && is_dir) {
		err = ubifs_check_dir_empty(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;
	}

	if (flags & RENAME_WHITEOUT) {
		union ubifs_dev_desc *dev = NULL;

		dev = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
		if (!dev) {
			ubifs_release_budget(c, &req);
			ubifs_release_budget(c, &ino_req);
			return -ENOMEM;
		}

		err = do_tmpfile(old_dir, old_dentry, S_IFCHR | WHITEOUT_MODE, &whiteout);
		if (err) {
			ubifs_release_budget(c, &req);
			ubifs_release_budget(c, &ino_req);
			kfree(dev);
			return err;
		}

		whiteout->i_state |= I_LINKABLE;
		whiteout_ui = ubifs_inode(whiteout);
		whiteout_ui->data = dev;
		whiteout_ui->data_len = ubifs_encode_dev(dev, MKDEV(0, 0));
		ubifs_assert(!whiteout_ui->dirty);
	}

	lock_4_inodes(old_dir, new_dir, new_inode, whiteout);

	/*
	 * 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;
	}

	if (whiteout) {
		struct ubifs_budget_req wht_req = { .dirtied_ino = 1,
				.dirtied_ino_d = \
				ALIGN(ubifs_inode(whiteout)->data_len, 8) };

		err = ubifs_budget_space(c, &wht_req);
		if (err) {
			ubifs_release_budget(c, &req);
			ubifs_release_budget(c, &ino_req);
			kfree(whiteout_ui->data);
			whiteout_ui->data_len = 0;
			iput(whiteout);
			return err;
		}

		inc_nlink(whiteout);
		mark_inode_dirty(whiteout);
		whiteout->i_state &= ~I_LINKABLE;
		iput(whiteout);
	}

	err = ubifs_jnl_rename(c, old_dir, old_dentry, new_dir, new_dentry, whiteout,
			       sync);
	if (err)
		goto out_cancel;

	unlock_4_inodes(old_dir, new_dir, new_inode, whiteout);
	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);
		}
	}
	if (whiteout) {
		drop_nlink(whiteout);
		iput(whiteout);
	}
	unlock_4_inodes(old_dir, new_dir, new_inode, whiteout);
	ubifs_release_budget(c, &ino_req);
	ubifs_release_budget(c, &req);
	return err;
}

static int ubifs_xrename(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 ubifs_budget_req req = { .new_dent = 1, .mod_dent = 1,
				.dirtied_ino = 2 };
	int sync = IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir);
	struct inode *fst_inode = d_inode(old_dentry);
	struct inode *snd_inode = d_inode(new_dentry);
	struct timespec time;
	int err;

	ubifs_assert(fst_inode && snd_inode);

	lock_4_inodes(old_dir, new_dir, NULL, NULL);

	time = ubifs_current_time(old_dir);
	fst_inode->i_ctime = time;
	snd_inode->i_ctime = time;
	old_dir->i_mtime = old_dir->i_ctime = time;
	new_dir->i_mtime = new_dir->i_ctime = time;

	if (old_dir != new_dir) {
		if (S_ISDIR(fst_inode->i_mode) && !S_ISDIR(snd_inode->i_mode)) {
			inc_nlink(new_dir);
			drop_nlink(old_dir);
		}
		else if (!S_ISDIR(fst_inode->i_mode) && S_ISDIR(snd_inode->i_mode)) {
			drop_nlink(new_dir);
			inc_nlink(old_dir);
		}
	}

	err = ubifs_jnl_xrename(c, old_dir, old_dentry, new_dir, new_dentry,
				sync);

	unlock_4_inodes(old_dir, new_dir, NULL, NULL);
	ubifs_release_budget(c, &req);

	return err;
}

static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry,
			struct inode *new_dir, struct dentry *new_dentry,
			unsigned int flags)
{
	if (flags & ~(RENAME_NOREPLACE | RENAME_WHITEOUT | RENAME_EXCHANGE))
		return -EINVAL;

	ubifs_assert(inode_is_locked(old_dir));
	ubifs_assert(inode_is_locked(new_dir));

	if (flags & RENAME_EXCHANGE)
		return ubifs_xrename(old_dir, old_dentry, new_dir, new_dentry);

	return do_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
}

int ubifs_getattr(struct vfsmount *mnt, struct dentry *dentry,
		  struct kstat *stat)
{
	loff_t size;
	struct inode *inode = d_inode(dentry);
	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,
	.listxattr   = ubifs_listxattr,
#ifdef CONFIG_UBIFS_ATIME_SUPPORT
	.update_time = ubifs_update_time,
#endif
	.tmpfile     = ubifs_tmpfile,
};

const struct file_operations ubifs_dir_operations = {
	.llseek         = generic_file_llseek,
	.release        = ubifs_dir_release,
	.read           = generic_read_dir,
	.iterate_shared = ubifs_readdir,
	.fsync          = ubifs_fsync,
	.unlocked_ioctl = ubifs_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl   = ubifs_compat_ioctl,
#endif
};