Linux 2.6.35-rc2

[linux/fpc-iii.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, int 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,
                              int 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");
                        make_bad_inode(inode);
                        iput(inode);
                        return ERR_PTR(-EINVAL);
                }
                ubifs_warn("running out of inode numbers (current %lu, max %d)",
                           (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;
}

#ifdef CONFIG_UBIFS_FS_DEBUG

static int dbg_check_name(struct ubifs_dent_node *dent, struct qstr *nm)
{
        if (!(ubifs_chk_flags & UBIFS_CHK_GEN))
                return 0;
        if (le16_to_cpu(dent->nlen) != nm->len)
                return -EINVAL;
        if (memcmp(dent->name, nm->name, nm->len))
                return -EINVAL;
        return 0;
}

#else

#define dbg_check_name(dent, nm) 0

#endif

static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
                                   struct nameidata *nd)
{
        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(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",
                          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, int mode,
                        struct nameidata *nd)
{
        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 %#x 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", 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;
        struct qstr nm;
        union ubifs_key key;
        struct ubifs_dent_node *dent;
        struct inode *dir = file->f_path.dentry->d_inode;
        struct ubifs_info *c = dir->i_sb->s_fs_info;

        dbg_gen("dir ino %lu, f_pos %#llx", dir->i_ino, file->f_pos);

        if (file->f_pos > UBIFS_S_KEY_HASH_MASK || file->f_pos == 2)
                /*
                 * The directory was seek'ed to a senseless position or there
                 * are no more entries.
                 */
                return 0;

        /* File positions 0 and 1 correspond to "." and ".." */
        if (file->f_pos == 0) {
                ubifs_assert(!file->private_data);
                over = filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR);
                if (over)
                        return 0;
                file->f_pos = 1;
        }

        if (file->f_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 = 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 @file->f_pos or the
                 * closest one.
                 */
                dent_key_init_hash(c, &key, dir->i_ino, file->f_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 = 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, file->f_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 = key_hash_flash(c, &dent->key);
                file->private_data = dent;
                cond_resched();
        }

out:
        if (err != -ENOENT) {
                ubifs_err("cannot find next direntry, error %d", err);
                return err;
        }

        kfree(file->private_data);
        file->private_data = NULL;
        file->f_pos = 2;
        return 0;
}

/* If a directory is seeked, we have to free saved readdir() state */
static loff_t ubifs_dir_llseek(struct file *file, loff_t offset, int origin)
{
        kfree(file->private_data);
        file->private_data = NULL;
        return generic_file_llseek(file, offset, origin);
}

/* 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));

        /*
         * Return -ENOENT if we've raced with unlink and i_nlink is 0.  Doing
         * otherwise has the potential to corrupt the orphan inode list.
         *
         * Indeed, consider a scenario when 'vfs_link(dirA/fileA)' and
         * 'vfs_unlink(dirA/fileA, dirB/fileB)' race. 'vfs_link()' does not
         * lock 'dirA->i_mutex', so this is possible. Both of the functions
         * lock 'fileA->i_mutex' though. Suppose 'vfs_unlink()' wins, and takes
         * 'fileA->i_mutex' mutex first. Suppose 'fileA->i_nlink' is 1. In this
         * case 'ubifs_unlink()' will drop the last reference, and put 'inodeA'
         * to the list of orphans. After this, 'vfs_link()' will link
         * 'dirB/fileB' to 'inodeA'. This is a problem because, for example,
         * the subsequent 'vfs_unlink(dirB/fileB)' will add the same inode
         * to the list of orphans.
         */
         if (inode->i_nlink == 0)
                 return -ENOENT;

        err = dbg_check_synced_i_size(inode);
        if (err)
                return err;

        err = ubifs_budget_space(c, &req);
        if (err)
                return err;

        lock_2_inodes(dir, inode);
        inc_nlink(inode);
        atomic_inc(&inode->i_count);
        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 };

        /*
         * 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(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->nospace = c->nospace_rp = 0;
                smp_wmb();
        }
        return 0;

out_cancel:
        dir->i_size += sz_change;
        dir_ui->ui_size = dir->i_size;
        inc_nlink(inode);
        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->nospace = c->nospace_rp = 0;
                smp_wmb();
        }
        return 0;

out_cancel:
        dir->i_size += sz_change;
        dir_ui->ui_size = dir->i_size;
        inc_nlink(dir);
        inc_nlink(inode);
        inc_nlink(inode);
        unlock_2_inodes(dir, inode);
        if (budgeted)
                ubifs_release_budget(c, &req);
        return err;
}

static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, int 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 %#x 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", 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,
                       int 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;

        /*
         * 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, decrement its @i_nlink twice because an empty
                 * directory has @i_nlink 2.
                 */
                if (is_dir)
                        drop_nlink(new_inode);
                new_inode->i_ctime = time;
                drop_nlink(new_inode);
        } 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) {
                if (is_dir)
                        inc_nlink(new_inode);
                inc_nlink(new_inode);
        } 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);
        stat->dev = inode->i_sb->s_dev;
        stat->ino = inode->i_ino;
        stat->mode = inode->i_mode;
        stat->nlink = inode->i_nlink;
        stat->uid = inode->i_uid;
        stat->gid = inode->i_gid;
        stat->rdev = inode->i_rdev;
        stat->atime = inode->i_atime;
        stat->mtime = inode->i_mtime;
        stat->ctime = inode->i_ctime;
        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,
#ifdef CONFIG_UBIFS_FS_XATTR
        .setxattr    = ubifs_setxattr,
        .getxattr    = ubifs_getxattr,
        .listxattr   = ubifs_listxattr,
        .removexattr = ubifs_removexattr,
#endif
};

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
};