dir.c

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/* * 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"

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;
}

struct inode *ubifs_new_inode(struct ubifs_info *c, const struct inode *dir,
                  umode_t mode)
{
    struct inode *inode;
    struct ubifs_inode *ui;

    inode = new_inode(c->vfs_sb);
    ui = ubifs_inode(inode);
    if (!inode)
        return ERR_PTR(-ENOMEM);

    /*
     * Set 'S_NOCMTIME' to prevent VFS form updating [mc]time of inodes and
     * marking them dirty in file write path (see 'file_update_time()').
     * UBIFS has to fully control "clean <-> dirty" transitions of inodes
     * to make budgeting work.
     */
    inode->i_flags |= S_NOCMTIME;

    inode_init_owner(inode, dir, mode);
    inode->i_mtime = inode->i_atime = inode->i_ctime =
             ubifs_current_time(inode);
    inode->i_mapping->nrpages = 0;
    /* Disable readahead */
    inode->i_mapping->backing_dev_info = &c->bdi;

    switch (mode & S_IFMT) {
    case S_IFREG:
        inode->i_mapping->a_ops = &ubifs_file_address_operations;
        inode->i_op = &ubifs_file_inode_operations;
        inode->i_fop = &ubifs_file_operations;
        break;
    case S_IFDIR:
        inode->i_op  = &ubifs_dir_inode_operations;
        inode->i_fop = &ubifs_dir_operations;
        inode->i_size = ui->ui_size = UBIFS_INO_NODE_SZ;
        break;
    case S_IFLNK:
        inode->i_op = &ubifs_symlink_inode_operations;
        break;
    case S_IFSOCK:
    case S_IFIFO:
    case S_IFBLK:
    case S_IFCHR:
        inode->i_op  = &ubifs_file_inode_operations;
        break;
    default:
        BUG();
    }

    ui->flags = inherit_flags(dir, mode);
    ubifs_set_inode_flags(inode);
    if (S_ISREG(mode))
        ui->compr_type = c->default_compr;
    else
        ui->compr_type = UBIFS_COMPR_NONE;
    ui->synced_i_size = 0;

    spin_lock(&c->cnt_lock);
    /* Inode number overflow is currently not supported */
    if (c->highest_inum >= INUM_WARN_WATERMARK) {
        if (c->highest_inum >= INUM_WATERMARK) {
            spin_unlock(&c->cnt_lock);
            ubifs_err("out of inode numbers");
            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;
}

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

static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
                   unsigned int flags)
{
    int err;
    union ubifs_key key;
    struct inode *inode = NULL;
    struct ubifs_dent_node *dent;
    struct ubifs_info *c = dir->i_sb->s_fs_info;

    dbg_gen("'%.*s' in dir ino %lu",
        dentry->d_name.len, dentry->d_name.name, dir->i_ino);

    if (dentry->d_name.len > UBIFS_MAX_NLEN)
        return ERR_PTR(-ENAMETOOLONG);

    dent = kmalloc(UBIFS_MAX_DENT_NODE_SZ, GFP_NOFS);
    if (!dent)
        return ERR_PTR(-ENOMEM);

    dent_key_init(c, &key, dir->i_ino, &dentry->d_name);

    err = ubifs_tnc_lookup_nm(c, &key, dent, &dentry->d_name);
    if (err) {
        if (err == -ENOENT) {
            dbg_gen("not found");
            goto done;
        }
        goto out;
    }

    if (dbg_check_name(c, dent, &dentry->d_name)) {
        err = -EINVAL;
        goto out;
    }

    inode = ubifs_iget(dir->i_sb, le64_to_cpu(dent->inum));
    if (IS_ERR(inode)) {
        /*
         * This should not happen. Probably the file-system needs
         * checking.
         */
        err = PTR_ERR(inode);
        ubifs_err("dead directory entry '%.*s', error %d",
              dentry->d_name.len, dentry->d_name.name, err);
        ubifs_ro_mode(c, err);
        goto out;
    }

done:
    kfree(dent);
    /*
     * Note, d_splice_alias() would be required instead if we supported
     * NFS.
     */
    d_add(dentry, inode);
    return NULL;

out:
    kfree(dent);
    return ERR_PTR(err);
}

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

    /*
     * Budget request settings: new inode, new direntry, changing the
     * parent directory inode.
     */

    dbg_gen("dent '%.*s', mode %#hx in dir ino %lu",
        dentry->d_name.len, dentry->d_name.name, mode, dir->i_ino);

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

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

    mutex_lock(&dir_ui->ui_mutex);
    dir->i_size += sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
    if (err)
        goto out_cancel;
    mutex_unlock(&dir_ui->ui_mutex);

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

out_cancel:
    dir->i_size -= sz_change;
    dir_ui->ui_size = dir->i_size;
    mutex_unlock(&dir_ui->ui_mutex);
    make_bad_inode(inode);
    iput(inode);
out_budg:
    ubifs_release_budget(c, &req);
    ubifs_err("cannot create regular file, error %d", err);
    return err;
}

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;
}

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);
}

static void unlock_2_inodes(struct inode *inode1, struct inode *inode2)
{
    mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
    mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
}

static int ubifs_link(struct dentry *old_dentry, struct inode *dir,
              struct dentry *dentry)
{
    struct ubifs_info *c = dir->i_sb->s_fs_info;
    struct inode *inode = old_dentry->d_inode;
    struct ubifs_inode *ui = ubifs_inode(inode);
    struct ubifs_inode *dir_ui = ubifs_inode(dir);
    int err, sz_change = CALC_DENT_SIZE(dentry->d_name.len);
    struct ubifs_budget_req req = { .new_dent = 1, .dirtied_ino = 2,
                .dirtied_ino_d = ALIGN(ui->data_len, 8) };

    /*
     * Budget request settings: new direntry, changing the target inode,
     * changing the parent inode.
     */

    dbg_gen("dent '%.*s' to ino %lu (nlink %d) in dir ino %lu",
        dentry->d_name.len, dentry->d_name.name, inode->i_ino,
        inode->i_nlink, dir->i_ino);
    ubifs_assert(mutex_is_locked(&dir->i_mutex));
    ubifs_assert(mutex_is_locked(&inode->i_mutex));

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

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

    lock_2_inodes(dir, inode);
    inc_nlink(inode);
    ihold(inode);
    inode->i_ctime = ubifs_current_time(inode);
    dir->i_size += sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
    if (err)
        goto out_cancel;
    unlock_2_inodes(dir, inode);

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

out_cancel:
    dir->i_size -= sz_change;
    dir_ui->ui_size = dir->i_size;
    drop_nlink(inode);
    unlock_2_inodes(dir, inode);
    ubifs_release_budget(c, &req);
    iput(inode);
    return err;
}

static int ubifs_unlink(struct inode *dir, struct dentry *dentry)
{
    struct ubifs_info *c = dir->i_sb->s_fs_info;
    struct inode *inode = dentry->d_inode;
    struct ubifs_inode *dir_ui = ubifs_inode(dir);
    int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
    int err, budgeted = 1;
    struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };
    unsigned int saved_nlink = inode->i_nlink;

    /*
     * Budget request settings: deletion direntry, deletion inode (+1 for
     * @dirtied_ino), changing the parent directory inode. If budgeting
     * fails, go ahead anyway because we have extra space reserved for
     * deletions.
     */

    dbg_gen("dent '%.*s' from ino %lu (nlink %d) in dir ino %lu",
        dentry->d_name.len, dentry->d_name.name, inode->i_ino,
        inode->i_nlink, dir->i_ino);
    ubifs_assert(mutex_is_locked(&dir->i_mutex));
    ubifs_assert(mutex_is_locked(&inode->i_mutex));
    err = dbg_check_synced_i_size(c, inode);
    if (err)
        return err;

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

    lock_2_inodes(dir, inode);
    inode->i_ctime = ubifs_current_time(dir);
    drop_nlink(inode);
    dir->i_size -= sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 1, 0);
    if (err)
        goto out_cancel;
    unlock_2_inodes(dir, inode);

    if (budgeted)
        ubifs_release_budget(c, &req);
    else {
        /* We've deleted something - clean the "no space" flags */
        c->bi.nospace = c->bi.nospace_rp = 0;
        smp_wmb();
    }
    return 0;

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

static int check_dir_empty(struct ubifs_info *c, struct inode *dir)
{
    struct qstr nm = { .name = NULL };
    struct ubifs_dent_node *dent;
    union ubifs_key key;
    int err;

    lowest_dent_key(c, &key, dir->i_ino);
    dent = ubifs_tnc_next_ent(c, &key, &nm);
    if (IS_ERR(dent)) {
        err = PTR_ERR(dent);
        if (err == -ENOENT)
            err = 0;
    } else {
        kfree(dent);
        err = -ENOTEMPTY;
    }
    return err;
}

static int ubifs_rmdir(struct inode *dir, struct dentry *dentry)
{
    struct ubifs_info *c = dir->i_sb->s_fs_info;
    struct inode *inode = dentry->d_inode;
    int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
    int err, budgeted = 1;
    struct ubifs_inode *dir_ui = ubifs_inode(dir);
    struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };

    /*
     * Budget request settings: deletion direntry, deletion inode and
     * changing the parent inode. If budgeting fails, go ahead anyway
     * because we have extra space reserved for deletions.
     */

    dbg_gen("directory '%.*s', ino %lu in dir ino %lu", dentry->d_name.len,
        dentry->d_name.name, inode->i_ino, dir->i_ino);
    ubifs_assert(mutex_is_locked(&dir->i_mutex));
    ubifs_assert(mutex_is_locked(&inode->i_mutex));
    err = check_dir_empty(c, dentry->d_inode);
    if (err)
        return err;

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

    lock_2_inodes(dir, inode);
    inode->i_ctime = ubifs_current_time(dir);
    clear_nlink(inode);
    drop_nlink(dir);
    dir->i_size -= sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 1, 0);
    if (err)
        goto out_cancel;
    unlock_2_inodes(dir, inode);

    if (budgeted)
        ubifs_release_budget(c, &req);
    else {
        /* We've deleted something - clean the "no space" flags */
        c->bi.nospace = c->bi.nospace_rp = 0;
        smp_wmb();
    }
    return 0;

out_cancel:
    dir->i_size += sz_change;
    dir_ui->ui_size = dir->i_size;
    inc_nlink(dir);
    set_nlink(inode, 2);
    unlock_2_inodes(dir, inode);
    if (budgeted)
        ubifs_release_budget(c, &req);
    return err;
}

static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
    struct inode *inode;
    struct ubifs_inode *dir_ui = ubifs_inode(dir);
    struct ubifs_info *c = dir->i_sb->s_fs_info;
    int err, sz_change = CALC_DENT_SIZE(dentry->d_name.len);
    struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1 };

    /*
     * Budget request settings: new inode, new direntry and changing parent
     * directory inode.
     */

    dbg_gen("dent '%.*s', mode %#hx in dir ino %lu",
        dentry->d_name.len, dentry->d_name.name, mode, dir->i_ino);

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

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

    mutex_lock(&dir_ui->ui_mutex);
    insert_inode_hash(inode);
    inc_nlink(inode);
    inc_nlink(dir);
    dir->i_size += sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
    if (err) {
        ubifs_err("cannot create directory, error %d", err);
        goto out_cancel;
    }
    mutex_unlock(&dir_ui->ui_mutex);

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

out_cancel:
    dir->i_size -= sz_change;
    dir_ui->ui_size = dir->i_size;
    drop_nlink(dir);
    mutex_unlock(&dir_ui->ui_mutex);
    make_bad_inode(inode);
    iput(inode);
out_budg:
    ubifs_release_budget(c, &req);
    return err;
}

static int ubifs_mknod(struct inode *dir, struct dentry *dentry,
               umode_t mode, dev_t rdev)
{
    struct inode *inode;
    struct ubifs_inode *ui;
    struct ubifs_inode *dir_ui = ubifs_inode(dir);
    struct ubifs_info *c = dir->i_sb->s_fs_info;
    union ubifs_dev_desc *dev = NULL;
    int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
    int err, devlen = 0;
    struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                    .new_ino_d = ALIGN(devlen, 8),
                    .dirtied_ino = 1 };

    /*
     * Budget request settings: new inode, new direntry and changing parent
     * directory inode.
     */

    dbg_gen("dent '%.*s' in dir ino %lu",
        dentry->d_name.len, dentry->d_name.name, dir->i_ino);

    if (!new_valid_dev(rdev))
        return -EINVAL;

    if (S_ISBLK(mode) || S_ISCHR(mode)) {
        dev = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
        if (!dev)
            return -ENOMEM;
        devlen = ubifs_encode_dev(dev, rdev);
    }

    err = ubifs_budget_space(c, &req);
    if (err) {
        kfree(dev);
        return err;
    }

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

    init_special_inode(inode, inode->i_mode, rdev);
    inode->i_size = ubifs_inode(inode)->ui_size = devlen;
    ui = ubifs_inode(inode);
    ui->data = dev;
    ui->data_len = devlen;

    mutex_lock(&dir_ui->ui_mutex);
    dir->i_size += sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
    if (err)
        goto out_cancel;
    mutex_unlock(&dir_ui->ui_mutex);

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

out_cancel:
    dir->i_size -= sz_change;
    dir_ui->ui_size = dir->i_size;
    mutex_unlock(&dir_ui->ui_mutex);
    make_bad_inode(inode);
    iput(inode);
out_budg:
    ubifs_release_budget(c, &req);
    return err;
}

static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
             const char *symname)
{
    struct inode *inode;
    struct ubifs_inode *ui;
    struct ubifs_inode *dir_ui = ubifs_inode(dir);
    struct ubifs_info *c = dir->i_sb->s_fs_info;
    int err, len = strlen(symname);
    int sz_change = CALC_DENT_SIZE(dentry->d_name.len);
    struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
                    .new_ino_d = ALIGN(len, 8),
                    .dirtied_ino = 1 };

    /*
     * Budget request settings: new inode, new direntry and changing parent
     * directory inode.
     */

    dbg_gen("dent '%.*s', target '%s' in dir ino %lu", dentry->d_name.len,
        dentry->d_name.name, symname, dir->i_ino);

    if (len > UBIFS_MAX_INO_DATA)
        return -ENAMETOOLONG;

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

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

    ui = ubifs_inode(inode);
    ui->data = kmalloc(len + 1, GFP_NOFS);
    if (!ui->data) {
        err = -ENOMEM;
        goto out_inode;
    }

    memcpy(ui->data, symname, len);
    ((char *)ui->data)[len] = '\0';
    /*
     * The terminating zero byte is not written to the flash media and it
     * is put just to make later in-memory string processing simpler. Thus,
     * data length is @len, not @len + %1.
     */
    ui->data_len = len;
    inode->i_size = ubifs_inode(inode)->ui_size = len;

    mutex_lock(&dir_ui->ui_mutex);
    dir->i_size += sz_change;
    dir_ui->ui_size = dir->i_size;
    dir->i_mtime = dir->i_ctime = inode->i_ctime;
    err = ubifs_jnl_update(c, dir, &dentry->d_name, inode, 0, 0);
    if (err)
        goto out_cancel;
    mutex_unlock(&dir_ui->ui_mutex);

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

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

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);
}

static void unlock_3_inodes(struct inode *inode1, struct inode *inode2,
                struct inode *inode3)
{
    if (inode3)
        mutex_unlock(&ubifs_inode(inode3)->ui_mutex);
    if (inode1 != inode2)
        mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
    mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
}

static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry,
            struct inode *new_dir, struct dentry *new_dentry)
{
    struct ubifs_info *c = old_dir->i_sb->s_fs_info;
    struct inode *old_inode = old_dentry->d_inode;
    struct inode *new_inode = new_dentry->d_inode;
    struct ubifs_inode *old_inode_ui = ubifs_inode(old_inode);
    int err, release, sync = 0, move = (new_dir != old_dir);
    int is_dir = S_ISDIR(old_inode->i_mode);
    int unlink = !!new_inode;
    int new_sz = CALC_DENT_SIZE(new_dentry->d_name.len);
    int old_sz = CALC_DENT_SIZE(old_dentry->d_name.len);
    struct ubifs_budget_req req = { .new_dent = 1, .mod_dent = 1,
                    .dirtied_ino = 3 };
    struct ubifs_budget_req ino_req = { .dirtied_ino = 1,
            .dirtied_ino_d = ALIGN(old_inode_ui->data_len, 8) };
    struct timespec time;
    unsigned int uninitialized_var(saved_nlink);

    /*
     * Budget request settings: deletion direntry, new direntry, removing
     * the old inode, and changing old and new parent directory inodes.
     *
     * However, this operation also marks the target inode as dirty and
     * does not write it, so we allocate budget for the target inode
     * separately.
     */

    dbg_gen("dent '%.*s' ino %lu in dir ino %lu to dent '%.*s' in dir ino %lu",
        old_dentry->d_name.len, old_dentry->d_name.name,
        old_inode->i_ino, old_dir->i_ino, new_dentry->d_name.len,
        new_dentry->d_name.name, new_dir->i_ino);
    ubifs_assert(mutex_is_locked(&old_dir->i_mutex));
    ubifs_assert(mutex_is_locked(&new_dir->i_mutex));
    if (unlink)
        ubifs_assert(mutex_is_locked(&new_inode->i_mutex));


    if (unlink && is_dir) {
        err = check_dir_empty(c, new_inode);
        if (err)
            return err;
    }

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

    lock_3_inodes(old_dir, new_dir, new_inode);

    /*
     * Like most other Unix systems, set the @i_ctime for inodes on a
     * rename.
     */
    time = ubifs_current_time(old_dir);
    old_inode->i_ctime = time;

    /* We must adjust parent link count when renaming directories */
    if (is_dir) {
        if (move) {
            /*
             * @old_dir loses a link because we are moving
             * @old_inode to a different directory.
             */
            drop_nlink(old_dir);
            /*
             * @new_dir only gains a link if we are not also
             * overwriting an existing directory.
             */
            if (!unlink)
                inc_nlink(new_dir);
        } else {
            /*
             * @old_inode is not moving to a different directory,
             * but @old_dir still loses a link if we are
             * overwriting an existing directory.
             */
            if (unlink)
                drop_nlink(old_dir);
        }
    }

    old_dir->i_size -= old_sz;
    ubifs_inode(old_dir)->ui_size = old_dir->i_size;
    old_dir->i_mtime = old_dir->i_ctime = time;
    new_dir->i_mtime = new_dir->i_ctime = time;

    /*
     * And finally, if we unlinked a direntry which happened to have the
     * same name as the moved direntry, we have to decrement @i_nlink of
     * the unlinked inode and change its ctime.
     */
    if (unlink) {
        /*
         * Directories cannot have hard-links, so if this is a
         * directory, just clear @i_nlink.
         */
        saved_nlink = new_inode->i_nlink;
        if (is_dir)
            clear_nlink(new_inode);
        else
            drop_nlink(new_inode);
        new_inode->i_ctime = time;
    } else {
        new_dir->i_size += new_sz;
        ubifs_inode(new_dir)->ui_size = new_dir->i_size;
    }

    /*
     * Do not ask 'ubifs_jnl_rename()' to flush write-buffer if @old_inode
     * is dirty, because this will be done later on at the end of
     * 'ubifs_rename()'.
     */
    if (IS_SYNC(old_inode)) {
        sync = IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir);
        if (unlink && IS_SYNC(new_inode))
            sync = 1;
    }
    err = ubifs_jnl_rename(c, old_dir, old_dentry, new_dir, new_dentry,
                   sync);
    if (err)
        goto out_cancel;

    unlock_3_inodes(old_dir, new_dir, new_inode);
    ubifs_release_budget(c, &req);

    mutex_lock(&old_inode_ui->ui_mutex);
    release = old_inode_ui->dirty;
    mark_inode_dirty_sync(old_inode);
    mutex_unlock(&old_inode_ui->ui_mutex);

    if (release)
        ubifs_release_budget(c, &ino_req);
    if (IS_SYNC(old_inode))
        err = old_inode->i_sb->s_op->write_inode(old_inode, NULL);
    return err;

out_cancel:
    if (unlink) {
        set_nlink(new_inode, saved_nlink);
    } else {
        new_dir->i_size -= new_sz;
        ubifs_inode(new_dir)->ui_size = new_dir->i_size;
    }
    old_dir->i_size += old_sz;
    ubifs_inode(old_dir)->ui_size = old_dir->i_size;
    if (is_dir) {
        if (move) {
            inc_nlink(old_dir);
            if (!unlink)
                drop_nlink(new_dir);
        } else {
            if (unlink)
                inc_nlink(old_dir);
        }
    }
    unlock_3_inodes(old_dir, new_dir, new_inode);
    ubifs_release_budget(c, &ino_req);
    ubifs_release_budget(c, &req);
    return err;
}

int ubifs_getattr(struct vfsmount *mnt, struct dentry *dentry,
          struct kstat *stat)
{
    loff_t size;
    struct inode *inode = dentry->d_inode;
    struct ubifs_inode *ui = ubifs_inode(inode);

    mutex_lock(&ui->ui_mutex);
    generic_fillattr(inode, stat);
    stat->blksize = UBIFS_BLOCK_SIZE;
    stat->size = ui->ui_size;

    /*
     * Unfortunately, the 'stat()' system call was designed for block
     * device based file systems, and it is not appropriate for UBIFS,
     * because UBIFS does not have notion of "block". For example, it is
     * difficult to tell how many block a directory takes - it actually
     * takes less than 300 bytes, but we have to round it to block size,
     * which introduces large mistake. This makes utilities like 'du' to
     * report completely senseless numbers. This is the reason why UBIFS
     * goes the same way as JFFS2 - it reports zero blocks for everything
     * but regular files, which makes more sense than reporting completely
     * wrong sizes.
     */
    if (S_ISREG(inode->i_mode)) {
        size = ui->xattr_size;
        size += stat->size;
        size = ALIGN(size, UBIFS_BLOCK_SIZE);
        /*
         * Note, user-space expects 512-byte blocks count irrespectively
         * of what was reported in @stat->size.
         */
        stat->blocks = size >> 9;
    } else
        stat->blocks = 0;
    mutex_unlock(&ui->ui_mutex);
    return 0;
}

const struct inode_operations ubifs_dir_inode_operations = {
    .lookup      = ubifs_lookup,
    .create      = ubifs_create,
    .link        = ubifs_link,
    .symlink     = ubifs_symlink,
    .unlink      = ubifs_unlink,
    .mkdir       = ubifs_mkdir,
    .rmdir       = ubifs_rmdir,
    .mknod       = ubifs_mknod,
    .rename      = ubifs_rename,
    .setattr     = ubifs_setattr,
    .getattr     = ubifs_getattr,
    .setxattr    = ubifs_setxattr,
    .getxattr    = ubifs_getxattr,
    .listxattr   = ubifs_listxattr,
    .removexattr = ubifs_removexattr,
};

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