Merge tag 'x86-urgent-2025-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git...

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

// SPDX-License-Identifier: GPL-2.0-only
/* * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 * Copyright (C) 2006, 2007 University of Szeged, Hungary
 *
 * 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
 * @is_xattr: whether the inode is xattr inode
 *
 * This function finds an unused inode number, allocates new inode and
 * initializes it. Non-xattr new inode may be written with xattrs(selinux/
 * encryption) before writing dentry, which could cause inconsistent problem
 * when powercut happens between two operations. To deal with it, non-xattr
 * new inode is initialized with zero-nlink and added into orphan list, caller
 * should make sure that inode is relinked later, and make sure that orphan
 * removing and journal writing into an committing atomic operation. 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, bool is_xattr)
{
        int err;
        struct inode *inode;
        struct ubifs_inode *ui;
        bool encrypted = false;

        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(&nop_mnt_idmap, inode, dir, mode);
        simple_inode_init_ts(inode);
        inode->i_mapping->nrpages = 0;

        if (!is_xattr) {
                err = fscrypt_prepare_new_inode(dir, inode, &encrypted);
                if (err) {
                        ubifs_err(c, "fscrypt_prepare_new_inode failed: %i", err);
                        goto out_iput;
                }
        }

        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");
                        err = -EINVAL;
                        goto out_iput;
                }
                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 (!is_xattr) {
                set_nlink(inode, 0);
                err = ubifs_add_orphan(c, inode->i_ino);
                if (err) {
                        ubifs_err(c, "ubifs_add_orphan failed: %i", err);
                        goto out_iput;
                }
                down_read(&c->commit_sem);
                ui->del_cmtno = c->cmt_no;
                up_read(&c->commit_sem);
        }

        if (encrypted) {
                err = fscrypt_set_context(inode, NULL);
                if (err) {
                        if (!is_xattr) {
                                set_nlink(inode, 1);
                                ubifs_delete_orphan(c, inode->i_ino);
                        }
                        ubifs_err(c, "fscrypt_set_context failed: %i", err);
                        goto out_iput;
                }
        }

        return inode;

out_iput:
        make_bad_inode(inode);
        iput(inode);
        return ERR_PTR(err);
}

static int dbg_check_name(const struct ubifs_info *c,
                          const struct ubifs_dent_node *dent,
                          const struct fscrypt_name *nm)
{
        if (!dbg_is_chk_gen(c))
                return 0;
        if (le16_to_cpu(dent->nlen) != fname_len(nm))
                return -EINVAL;
        if (memcmp(dent->name, fname_name(nm), fname_len(nm)))
                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 = NULL;
        struct ubifs_info *c = dir->i_sb->s_fs_info;
        struct fscrypt_name nm;

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

        err = fscrypt_prepare_lookup(dir, dentry, &nm);
        if (err == -ENOENT)
                return d_splice_alias(NULL, dentry);
        if (err)
                return ERR_PTR(err);

        if (fname_len(&nm) > UBIFS_MAX_NLEN) {
                inode = ERR_PTR(-ENAMETOOLONG);
                goto done;
        }

        dent = kmalloc(UBIFS_MAX_DENT_NODE_SZ, GFP_NOFS);
        if (!dent) {
                inode = ERR_PTR(-ENOMEM);
                goto done;
        }

        if (fname_name(&nm) == NULL) {
                if (nm.hash & ~UBIFS_S_KEY_HASH_MASK)
                        goto done; /* ENOENT */
                dent_key_init_hash(c, &key, dir->i_ino, nm.hash);
                err = ubifs_tnc_lookup_dh(c, &key, dent, nm.minor_hash);
        } else {
                dent_key_init(c, &key, dir->i_ino, &nm);
                err = ubifs_tnc_lookup_nm(c, &key, dent, &nm);
        }

        if (err) {
                if (err == -ENOENT)
                        dbg_gen("not found");
                else
                        inode = ERR_PTR(err);
                goto done;
        }

        if (dbg_check_name(c, dent, &nm)) {
                inode = ERR_PTR(-EINVAL);
                goto done;
        }

        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 done;
        }

        if (IS_ENCRYPTED(dir) &&
            (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) &&
            !fscrypt_has_permitted_context(dir, inode)) {
                ubifs_warn(c, "Inconsistent encryption contexts: %lu/%lu",
                           dir->i_ino, inode->i_ino);
                iput(inode);
                inode = ERR_PTR(-EPERM);
        }

done:
        kfree(dent);
        fscrypt_free_filename(&nm);
        return d_splice_alias(inode, dentry);
}

static int ubifs_prepare_create(struct inode *dir, struct dentry *dentry,
                                struct fscrypt_name *nm)
{
        if (fscrypt_is_nokey_name(dentry))
                return -ENOKEY;

        return fscrypt_setup_filename(dir, &dentry->d_name, 0, nm);
}

static int ubifs_create(struct mnt_idmap *idmap, struct inode *dir,
                        struct dentry *dentry, umode_t mode, bool excl)
{
        struct inode *inode;
        struct ubifs_info *c = dir->i_sb->s_fs_info;
        struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                                        .dirtied_ino = 1 };
        struct ubifs_inode *dir_ui = ubifs_inode(dir);
        struct fscrypt_name nm;
        int err, sz_change;

        /*
         * 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;

        err = ubifs_prepare_create(dir, dentry, &nm);
        if (err)
                goto out_budg;

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        inode = ubifs_new_inode(c, dir, mode, false);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                goto out_fname;
        }

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

        set_nlink(inode, 1);
        mutex_lock(&dir_ui->ui_mutex);
        dir->i_size += sz_change;
        dir_ui->ui_size = dir->i_size;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 0, 0, 1);
        if (err)
                goto out_cancel;
        mutex_unlock(&dir_ui->ui_mutex);

        ubifs_release_budget(c, &req);
        fscrypt_free_filename(&nm);
        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);
        set_nlink(inode, 0);
out_inode:
        iput(inode);
out_fname:
        fscrypt_free_filename(&nm);
out_budg:
        ubifs_release_budget(c, &req);
        ubifs_err(c, "cannot create regular file, error %d", err);
        return err;
}

static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
{
        int err;
        umode_t mode = S_IFCHR | WHITEOUT_MODE;
        struct inode *inode;
        struct ubifs_info *c = dir->i_sb->s_fs_info;

        /*
         * Create an inode('nlink = 1') for whiteout without updating journal,
         * let ubifs_jnl_rename() store it on flash to complete rename whiteout
         * atomically.
         */

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

        inode = ubifs_new_inode(c, dir, mode, false);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                goto out_free;
        }

        init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
        ubifs_assert(c, inode->i_op == &ubifs_file_inode_operations);

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

        /* The dir size is updated by do_rename. */
        insert_inode_hash(inode);

        return inode;

out_inode:
        iput(inode);
out_free:
        ubifs_err(c, "cannot create whiteout file, error %d", err);
        return ERR_PTR(err);
}

/**
 * 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_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
                         struct file *file, umode_t mode)
{
        struct dentry *dentry = file->f_path.dentry;
        struct inode *inode;
        struct ubifs_info *c = dir->i_sb->s_fs_info;
        struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                                        .dirtied_ino = 1};
        struct ubifs_budget_req ino_req = { .dirtied_ino = 1 };
        struct ubifs_inode *ui;
        int err, instantiated = 0;
        struct fscrypt_name nm;

        /*
         * Budget request settings: new inode, new direntry, changing the
         * parent directory inode.
         * Allocate budget separately for new dirtied inode, the budget will
         * be released via writeback.
         */

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

        err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
        if (err)
                return err;

        err = ubifs_budget_space(c, &req);
        if (err) {
                fscrypt_free_filename(&nm);
                return err;
        }

        err = ubifs_budget_space(c, &ino_req);
        if (err) {
                ubifs_release_budget(c, &req);
                fscrypt_free_filename(&nm);
                return err;
        }

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

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

        set_nlink(inode, 1);
        mutex_lock(&ui->ui_mutex);
        insert_inode_hash(inode);
        d_tmpfile(file, inode);
        ubifs_assert(c, ui->dirty);

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

        lock_2_inodes(dir, inode);
        err = ubifs_jnl_update(c, dir, &nm, inode, 1, 0, 1);
        if (err)
                goto out_cancel;
        unlock_2_inodes(dir, inode);

        ubifs_release_budget(c, &req);
        fscrypt_free_filename(&nm);

        return finish_open_simple(file, 0);

out_cancel:
        unlock_2_inodes(dir, inode);
out_inode:
        if (!instantiated)
                iput(inode);
out_budg:
        ubifs_release_budget(c, &req);
        if (!instantiated)
                ubifs_release_budget(c, &ino_req);
        fscrypt_free_filename(&nm);
        ubifs_err(c, "cannot create temporary 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;
}

struct ubifs_dir_data {
        struct ubifs_dent_node *dent;
        u64 cookie;
};

/*
 * 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 fstr_real_len = 0, err = 0;
        struct fscrypt_name nm;
        struct fscrypt_str fstr = {0};
        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;
        bool encrypted = IS_ENCRYPTED(dir);
        struct ubifs_dir_data *data = file->private_data;

        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 (encrypted) {
                err = fscrypt_prepare_readdir(dir);
                if (err)
                        return err;

                err = fscrypt_fname_alloc_buffer(UBIFS_MAX_NLEN, &fstr);
                if (err)
                        return err;

                fstr_real_len = fstr.len;
        }

        if (data->cookie == 0) {
                /*
                 * The file was seek'ed, which means that @data->dent
                 * is now invalid. This may also be just the first
                 * 'ubifs_readdir()' invocation, in which case
                 * @data->dent is NULL, and the below code is
                 * basically a no-op.
                 */
                kfree(data->dent);
                data->dent = NULL;
        }

        /*
         * 'ubifs_dir_llseek()' sets @data->cookie to zero, and we use this
         * for detecting whether the file was seek'ed.
         */
        data->cookie = 1;

        /* File positions 0 and 1 correspond to "." and ".." */
        if (ctx->pos < 2) {
                ubifs_assert(c, !data->dent);
                if (!dir_emit_dots(file, ctx)) {
                        if (encrypted)
                                fscrypt_fname_free_buffer(&fstr);
                        return 0;
                }

                /* Find the first entry in TNC and save it */
                lowest_dent_key(c, &key, dir->i_ino);
                fname_len(&nm) = 0;
                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);
                data->dent = dent;
        }

        dent = data->dent;
        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);
                fname_len(&nm) = 0;
                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);
                data->dent = dent;
        }

        while (1) {
                dbg_gen("ino %llu, new f_pos %#x",
                        (unsigned long long)le64_to_cpu(dent->inum),
                        key_hash_flash(c, &dent->key));
                ubifs_assert(c, le64_to_cpu(dent->ch.sqnum) >
                             ubifs_inode(dir)->creat_sqnum);

                fname_len(&nm) = le16_to_cpu(dent->nlen);
                fname_name(&nm) = dent->name;

                if (encrypted) {
                        fstr.len = fstr_real_len;

                        err = fscrypt_fname_disk_to_usr(dir, key_hash_flash(c,
                                                        &dent->key),
                                                        le32_to_cpu(dent->cookie),
                                                        &nm.disk_name, &fstr);
                        if (err)
                                goto out;
                } else {
                        fstr.len = fname_len(&nm);
                        fstr.name = fname_name(&nm);
                }

                if (!dir_emit(ctx, fstr.name, fstr.len,
                               le64_to_cpu(dent->inum),
                               vfs_dent_type(dent->type))) {
                        if (encrypted)
                                fscrypt_fname_free_buffer(&fstr);
                        return 0;
                }

                /* Switch to the next entry */
                key_read(c, &dent->key, &key);
                dent = ubifs_tnc_next_ent(c, &key, &nm);
                if (IS_ERR(dent)) {
                        err = PTR_ERR(dent);
                        goto out;
                }

                kfree(data->dent);
                ctx->pos = key_hash_flash(c, &dent->key);
                data->dent = dent;
                cond_resched();
        }

out:
        kfree(data->dent);
        data->dent = NULL;

        if (encrypted)
                fscrypt_fname_free_buffer(&fstr);

        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)
{
        struct ubifs_dir_data *data = file->private_data;

        kfree(data->dent);
        kfree(data);
        file->private_data = NULL;
        return 0;
}

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;
        struct ubifs_budget_req req = { .new_dent = 1, .dirtied_ino = 2,
                                .dirtied_ino_d = ALIGN(ui->data_len, 8) };
        struct fscrypt_name nm;

        /*
         * 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(c, inode_is_locked(dir));
        ubifs_assert(c, inode_is_locked(inode));

        err = fscrypt_prepare_link(old_dentry, dir, dentry);
        if (err)
                return err;

        err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
        if (err)
                return err;

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        err = dbg_check_synced_i_size(c, inode);
        if (err)
                goto out_fname;

        err = ubifs_budget_space(c, &req);
        if (err)
                goto out_fname;

        lock_2_inodes(dir, inode);

        inc_nlink(inode);
        ihold(inode);
        inode_set_ctime_current(inode);
        dir->i_size += sz_change;
        dir_ui->ui_size = dir->i_size;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 0, 0, inode->i_nlink == 1);
        if (err)
                goto out_cancel;
        unlock_2_inodes(dir, inode);

        ubifs_release_budget(c, &req);
        d_instantiate(dentry, inode);
        fscrypt_free_filename(&nm);
        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);
out_fname:
        fscrypt_free_filename(&nm);
        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 err, sz_change, budgeted = 1;
        struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };
        unsigned int saved_nlink = inode->i_nlink;
        struct fscrypt_name nm;

        /*
         * 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);

        err = fscrypt_setup_filename(dir, &dentry->d_name, 1, &nm);
        if (err)
                return err;

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

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        ubifs_assert(c, inode_is_locked(dir));
        ubifs_assert(c, inode_is_locked(inode));
        err = dbg_check_synced_i_size(c, inode);
        if (err)
                goto out_fname;

        err = ubifs_budget_space(c, &req);
        if (err) {
                if (err != -ENOSPC)
                        goto out_fname;
                budgeted = 0;
        }

        lock_2_inodes(dir, inode);
        inode_set_ctime_current(inode);
        drop_nlink(inode);
        dir->i_size -= sz_change;
        dir_ui->ui_size = dir->i_size;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 1, 0, 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();
        }
        fscrypt_free_filename(&nm);
        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);
out_fname:
        fscrypt_free_filename(&nm);
        return err;
}

/**
 * ubifs_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 errors.
 */
int ubifs_check_dir_empty(struct inode *dir)
{
        struct ubifs_info *c = dir->i_sb->s_fs_info;
        struct fscrypt_name nm = { 0 };
        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 err, sz_change, budgeted = 1;
        struct ubifs_inode *dir_ui = ubifs_inode(dir);
        struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };
        struct fscrypt_name nm;

        /*
         * 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(c, inode_is_locked(dir));
        ubifs_assert(c, inode_is_locked(inode));
        err = ubifs_check_dir_empty(d_inode(dentry));
        if (err)
                return err;

        err = fscrypt_setup_filename(dir, &dentry->d_name, 1, &nm);
        if (err)
                return err;

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

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        err = ubifs_budget_space(c, &req);
        if (err) {
                if (err != -ENOSPC)
                        goto out_fname;
                budgeted = 0;
        }

        lock_2_inodes(dir, inode);
        inode_set_ctime_current(inode);
        clear_nlink(inode);
        drop_nlink(dir);
        dir->i_size -= sz_change;
        dir_ui->ui_size = dir->i_size;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 1, 0, 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();
        }
        fscrypt_free_filename(&nm);
        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);
out_fname:
        fscrypt_free_filename(&nm);
        return err;
}

static int ubifs_mkdir(struct mnt_idmap *idmap, 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;
        struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                                        .dirtied_ino = 1};
        struct fscrypt_name nm;

        /*
         * 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;

        err = ubifs_prepare_create(dir, dentry, &nm);
        if (err)
                goto out_budg;

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        inode = ubifs_new_inode(c, dir, S_IFDIR | mode, false);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                goto out_fname;
        }

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

        set_nlink(inode, 1);
        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;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 0, 0, 1);
        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);
        fscrypt_free_filename(&nm);
        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);
        set_nlink(inode, 0);
out_inode:
        iput(inode);
out_fname:
        fscrypt_free_filename(&nm);
out_budg:
        ubifs_release_budget(c, &req);
        return err;
}

static int ubifs_mknod(struct mnt_idmap *idmap, 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;
        int err, devlen = 0;
        struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                                        .dirtied_ino = 1 };
        struct fscrypt_name nm;

        /*
         * 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);
        }

        req.new_ino_d = ALIGN(devlen, 8);
        err = ubifs_budget_space(c, &req);
        if (err) {
                kfree(dev);
                return err;
        }

        err = ubifs_prepare_create(dir, dentry, &nm);
        if (err) {
                kfree(dev);
                goto out_budg;
        }

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        inode = ubifs_new_inode(c, dir, mode, false);
        if (IS_ERR(inode)) {
                kfree(dev);
                err = PTR_ERR(inode);
                goto out_fname;
        }

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

        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;
        set_nlink(inode, 1);

        mutex_lock(&dir_ui->ui_mutex);
        dir->i_size += sz_change;
        dir_ui->ui_size = dir->i_size;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 0, 0, 1);
        if (err)
                goto out_cancel;
        mutex_unlock(&dir_ui->ui_mutex);

        ubifs_release_budget(c, &req);
        insert_inode_hash(inode);
        d_instantiate(dentry, inode);
        fscrypt_free_filename(&nm);
        return 0;

out_cancel:
        dir->i_size -= sz_change;
        dir_ui->ui_size = dir->i_size;
        mutex_unlock(&dir_ui->ui_mutex);
        set_nlink(inode, 0);
out_inode:
        iput(inode);
out_fname:
        fscrypt_free_filename(&nm);
out_budg:
        ubifs_release_budget(c, &req);
        return err;
}

static int ubifs_symlink(struct mnt_idmap *idmap, 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, sz_change, len = strlen(symname);
        struct fscrypt_str disk_link;
        struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                                        .dirtied_ino = 1 };
        struct fscrypt_name nm;

        dbg_gen("dent '%pd', target '%s' in dir ino %lu", dentry,
                symname, dir->i_ino);

        err = fscrypt_prepare_symlink(dir, symname, len, UBIFS_MAX_INO_DATA,
                                      &disk_link);
        if (err)
                return err;

        /*
         * Budget request settings: new inode, new direntry and changing parent
         * directory inode.
         */
        req.new_ino_d = ALIGN(disk_link.len - 1, 8);
        err = ubifs_budget_space(c, &req);
        if (err)
                return err;

        err = ubifs_prepare_create(dir, dentry, &nm);
        if (err)
                goto out_budg;

        sz_change = CALC_DENT_SIZE(fname_len(&nm));

        inode = ubifs_new_inode(c, dir, S_IFLNK | S_IRWXUGO, false);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                goto out_fname;
        }

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

        ui = ubifs_inode(inode);
        ui->data = kmalloc(disk_link.len, GFP_NOFS);
        if (!ui->data) {
                err = -ENOMEM;
                goto out_inode;
        }

        if (IS_ENCRYPTED(inode)) {
                disk_link.name = ui->data; /* encrypt directly into ui->data */
                err = fscrypt_encrypt_symlink(inode, symname, len, &disk_link);
                if (err)
                        goto out_inode;
        } else {
                memcpy(ui->data, disk_link.name, disk_link.len);
                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 @disk_link.len - 1, not @disk_link.len.
         */
        ui->data_len = disk_link.len - 1;
        inode->i_size = ubifs_inode(inode)->ui_size = disk_link.len - 1;
        set_nlink(inode, 1);

        mutex_lock(&dir_ui->ui_mutex);
        dir->i_size += sz_change;
        dir_ui->ui_size = dir->i_size;
        inode_set_mtime_to_ts(dir,
                              inode_set_ctime_to_ts(dir, inode_get_ctime(inode)));
        err = ubifs_jnl_update(c, dir, &nm, inode, 0, 0, 1);
        if (err)
                goto out_cancel;
        mutex_unlock(&dir_ui->ui_mutex);

        insert_inode_hash(inode);
        d_instantiate(dentry, inode);
        err = 0;
        goto out_fname;

out_cancel:
        dir->i_size -= sz_change;
        dir_ui->ui_size = dir->i_size;
        mutex_unlock(&dir_ui->ui_mutex);
        set_nlink(inode, 0);
out_inode:
        /* Free inode->i_link before inode is marked as bad. */
        fscrypt_free_inode(inode);
        iput(inode);
out_fname:
        fscrypt_free_filename(&nm);
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: fourth 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: fourth 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, new_sz, old_sz;
        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 ubifs_budget_req wht_req;
        unsigned int saved_nlink;
        struct fscrypt_name old_nm, new_nm;

        /*
         * Budget request settings:
         *   req: deletion direntry, new direntry, removing the old inode,
         *   and changing old and new parent directory inodes.
         *
         *   wht_req: new whiteout inode for RENAME_WHITEOUT.
         *
         *   ino_req: marks the target inode as dirty and does not write it.
         */

        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(c, inode_is_locked(new_inode));

                /* Budget for old inode's data when its nlink > 1. */
                req.dirtied_ino_d = ALIGN(ubifs_inode(new_inode)->data_len, 8);
                err = ubifs_purge_xattrs(new_inode);
                if (err)
                        return err;
        }

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

        err = fscrypt_setup_filename(old_dir, &old_dentry->d_name, 0, &old_nm);
        if (err)
                return err;

        err = fscrypt_setup_filename(new_dir, &new_dentry->d_name, 0, &new_nm);
        if (err) {
                fscrypt_free_filename(&old_nm);
                return err;
        }

        new_sz = CALC_DENT_SIZE(fname_len(&new_nm));
        old_sz = CALC_DENT_SIZE(fname_len(&old_nm));

        err = ubifs_budget_space(c, &req);
        if (err) {
                fscrypt_free_filename(&old_nm);
                fscrypt_free_filename(&new_nm);
                return err;
        }
        err = ubifs_budget_space(c, &ino_req);
        if (err) {
                fscrypt_free_filename(&old_nm);
                fscrypt_free_filename(&new_nm);
                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) {
                        err = -ENOMEM;
                        goto out_release;
                }

                /*
                 * The whiteout inode without dentry is pinned in memory,
                 * umount won't happen during rename process because we
                 * got parent dentry.
                 */
                whiteout = create_whiteout(old_dir, old_dentry);
                if (IS_ERR(whiteout)) {
                        err = PTR_ERR(whiteout);
                        kfree(dev);
                        goto out_release;
                }

                whiteout_ui = ubifs_inode(whiteout);
                whiteout_ui->data = dev;
                whiteout_ui->data_len = ubifs_encode_dev(dev, MKDEV(0, 0));
                ubifs_assert(c, !whiteout_ui->dirty);

                memset(&wht_req, 0, sizeof(struct ubifs_budget_req));
                wht_req.new_ino = 1;
                wht_req.new_ino_d = ALIGN(whiteout_ui->data_len, 8);
                /*
                 * To avoid deadlock between space budget (holds ui_mutex and
                 * waits wb work) and writeback work(waits ui_mutex), do space
                 * budget before ubifs inodes locked.
                 */
                err = ubifs_budget_space(c, &wht_req);
                if (err) {
                        iput(whiteout);
                        goto out_release;
                }
                set_nlink(whiteout, 1);

                /* Add the old_dentry size to the old_dir size. */
                old_sz -= CALC_DENT_SIZE(fname_len(&old_nm));
        }

        lock_4_inodes(old_dir, new_dir, new_inode, whiteout);

        /*
         * Like most other Unix systems, set the @i_ctime for inodes on a
         * rename.
         */
        simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);

        /* 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;

        /*
         * 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.
         */
        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);
        } 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;
                /*
                 * S_SYNC flag of whiteout inherits from the old_dir, and we
                 * have already checked the old dir inode. So there is no need
                 * to check whiteout.
                 */
        }

        err = ubifs_jnl_rename(c, old_dir, old_inode, &old_nm, new_dir,
                               new_inode, &new_nm, whiteout, sync, !!whiteout);
        if (err)
                goto out_cancel;

        unlock_4_inodes(old_dir, new_dir, new_inode, whiteout);
        ubifs_release_budget(c, &req);

        if (whiteout) {
                ubifs_release_budget(c, &wht_req);
                iput(whiteout);
        }

        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))
                /*
                 * Rename finished here. Although old inode cannot be updated
                 * on flash, old ctime is not a big problem, don't return err
                 * code to userspace.
                 */
                old_inode->i_sb->s_op->write_inode(old_inode, NULL);

        fscrypt_free_filename(&old_nm);
        fscrypt_free_filename(&new_nm);
        return 0;

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_4_inodes(old_dir, new_dir, new_inode, whiteout);
        if (whiteout) {
                ubifs_release_budget(c, &wht_req);
                set_nlink(whiteout, 0);
                iput(whiteout);
        }
out_release:
        ubifs_release_budget(c, &ino_req);
        ubifs_release_budget(c, &req);
        fscrypt_free_filename(&old_nm);
        fscrypt_free_filename(&new_nm);
        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);
        int err;
        struct fscrypt_name fst_nm, snd_nm;

        ubifs_assert(c, fst_inode && snd_inode);

        /*
         * Budget request settings: changing two direntries, changing the two
         * parent directory inodes.
         */

        dbg_gen("dent '%pd' ino %lu in dir ino %lu exchange dent '%pd' ino %lu in dir ino %lu",
                old_dentry, fst_inode->i_ino, old_dir->i_ino,
                new_dentry, snd_inode->i_ino, new_dir->i_ino);

        err = fscrypt_setup_filename(old_dir, &old_dentry->d_name, 0, &fst_nm);
        if (err)
                return err;

        err = fscrypt_setup_filename(new_dir, &new_dentry->d_name, 0, &snd_nm);
        if (err) {
                fscrypt_free_filename(&fst_nm);
                return err;
        }

        err = ubifs_budget_space(c, &req);
        if (err)
                goto out;

        lock_4_inodes(old_dir, new_dir, NULL, NULL);

        simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);

        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, fst_inode, &fst_nm, new_dir,
                                snd_inode, &snd_nm, sync);

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

out:
        fscrypt_free_filename(&fst_nm);
        fscrypt_free_filename(&snd_nm);
        return err;
}

static int ubifs_rename(struct mnt_idmap *idmap,
                        struct inode *old_dir, struct dentry *old_dentry,
                        struct inode *new_dir, struct dentry *new_dentry,
                        unsigned int flags)
{
        int err;
        struct ubifs_info *c = old_dir->i_sb->s_fs_info;

        if (flags & ~(RENAME_NOREPLACE | RENAME_WHITEOUT | RENAME_EXCHANGE))
                return -EINVAL;

        ubifs_assert(c, inode_is_locked(old_dir));
        ubifs_assert(c, inode_is_locked(new_dir));

        err = fscrypt_prepare_rename(old_dir, old_dentry, new_dir, new_dentry,
                                     flags);
        if (err)
                return err;

        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 mnt_idmap *idmap, const struct path *path,
                  struct kstat *stat, u32 request_mask, unsigned int flags)
{
        loff_t size;
        struct inode *inode = d_inode(path->dentry);
        struct ubifs_inode *ui = ubifs_inode(inode);

        mutex_lock(&ui->ui_mutex);

        if (ui->flags & UBIFS_APPEND_FL)
                stat->attributes |= STATX_ATTR_APPEND;
        if (ui->flags & UBIFS_COMPR_FL)
                stat->attributes |= STATX_ATTR_COMPRESSED;
        if (ui->flags & UBIFS_CRYPT_FL)
                stat->attributes |= STATX_ATTR_ENCRYPTED;
        if (ui->flags & UBIFS_IMMUTABLE_FL)
                stat->attributes |= STATX_ATTR_IMMUTABLE;

        stat->attributes_mask |= (STATX_ATTR_APPEND |
                                STATX_ATTR_COMPRESSED |
                                STATX_ATTR_ENCRYPTED |
                                STATX_ATTR_IMMUTABLE);

        generic_fillattr(&nop_mnt_idmap, request_mask, 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;
}

static int ubifs_dir_open(struct inode *inode, struct file *file)
{
        struct ubifs_dir_data *data;

        data = kzalloc(sizeof(struct ubifs_dir_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;
        file->private_data = data;
        return 0;
}

static loff_t ubifs_dir_llseek(struct file *file, loff_t offset, int whence)
{
        struct ubifs_dir_data *data = file->private_data;

        return generic_llseek_cookie(file, offset, whence, &data->cookie);
}

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,
        .update_time = ubifs_update_time,
        .tmpfile     = ubifs_tmpfile,
        .fileattr_get = ubifs_fileattr_get,
        .fileattr_set = ubifs_fileattr_set,
};

const struct file_operations ubifs_dir_operations = {
        .open           = ubifs_dir_open,
        .llseek         = ubifs_dir_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
};