namei.c

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/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger ([email protected])
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <[email protected]>
 *
 * Copyrights for code taken from ext2:
 *     Copyright (C) 1992, 1993, 1994, 1995
 *     Remy Card ([email protected])
 *     Laboratoire MASI - Institut Blaise Pascal
 *     Universite Pierre et Marie Curie (Paris VI)
 *     from
 *     linux/fs/minix/inode.c
 *     Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is part of exofs.
 *
 * exofs is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.  Since it is based on ext2, and the only
 * valid version of GPL for the Linux kernel is version 2, the only valid
 * version of GPL for exofs is version 2.
 *
 * exofs 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 exofs; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "exofs.h"

static inline int exofs_add_nondir(struct dentry *dentry, struct inode *inode)
{
    int err = exofs_add_link(dentry, inode);
    if (!err) {
        d_instantiate(dentry, inode);
        return 0;
    }
    inode_dec_link_count(inode);
    iput(inode);
    return err;
}

static struct dentry *exofs_lookup(struct inode *dir, struct dentry *dentry,
                   unsigned int flags)
{
    struct inode *inode;
    ino_t ino;

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

    ino = exofs_inode_by_name(dir, dentry);
    inode = ino ? exofs_iget(dir->i_sb, ino) : NULL;
    return d_splice_alias(inode, dentry);
}

static int exofs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
             bool excl)
{
    struct inode *inode = exofs_new_inode(dir, mode);
    int err = PTR_ERR(inode);
    if (!IS_ERR(inode)) {
        inode->i_op = &exofs_file_inode_operations;
        inode->i_fop = &exofs_file_operations;
        inode->i_mapping->a_ops = &exofs_aops;
        mark_inode_dirty(inode);
        err = exofs_add_nondir(dentry, inode);
    }
    return err;
}

static int exofs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
               dev_t rdev)
{
    struct inode *inode;
    int err;

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

    inode = exofs_new_inode(dir, mode);
    err = PTR_ERR(inode);
    if (!IS_ERR(inode)) {
        init_special_inode(inode, inode->i_mode, rdev);
        mark_inode_dirty(inode);
        err = exofs_add_nondir(dentry, inode);
    }
    return err;
}

static int exofs_symlink(struct inode *dir, struct dentry *dentry,
              const char *symname)
{
    struct super_block *sb = dir->i_sb;
    int err = -ENAMETOOLONG;
    unsigned l = strlen(symname)+1;
    struct inode *inode;
    struct exofs_i_info *oi;

    if (l > sb->s_blocksize)
        goto out;

    inode = exofs_new_inode(dir, S_IFLNK | S_IRWXUGO);
    err = PTR_ERR(inode);
    if (IS_ERR(inode))
        goto out;

    oi = exofs_i(inode);
    if (l > sizeof(oi->i_data)) {
        /* slow symlink */
        inode->i_op = &exofs_symlink_inode_operations;
        inode->i_mapping->a_ops = &exofs_aops;
        memset(oi->i_data, 0, sizeof(oi->i_data));

        err = page_symlink(inode, symname, l);
        if (err)
            goto out_fail;
    } else {
        /* fast symlink */
        inode->i_op = &exofs_fast_symlink_inode_operations;
        memcpy(oi->i_data, symname, l);
        inode->i_size = l-1;
    }
    mark_inode_dirty(inode);

    err = exofs_add_nondir(dentry, inode);
out:
    return err;

out_fail:
    inode_dec_link_count(inode);
    iput(inode);
    goto out;
}

static int exofs_link(struct dentry *old_dentry, struct inode *dir,
        struct dentry *dentry)
{
    struct inode *inode = old_dentry->d_inode;

    inode->i_ctime = CURRENT_TIME;
    inode_inc_link_count(inode);
    ihold(inode);

    return exofs_add_nondir(dentry, inode);
}

static int exofs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
    struct inode *inode;
    int err;

    inode_inc_link_count(dir);

    inode = exofs_new_inode(dir, S_IFDIR | mode);
    err = PTR_ERR(inode);
    if (IS_ERR(inode))
        goto out_dir;

    inode->i_op = &exofs_dir_inode_operations;
    inode->i_fop = &exofs_dir_operations;
    inode->i_mapping->a_ops = &exofs_aops;

    inode_inc_link_count(inode);

    err = exofs_make_empty(inode, dir);
    if (err)
        goto out_fail;

    err = exofs_add_link(dentry, inode);
    if (err)
        goto out_fail;

    d_instantiate(dentry, inode);
out:
    return err;

out_fail:
    inode_dec_link_count(inode);
    inode_dec_link_count(inode);
    iput(inode);
out_dir:
    inode_dec_link_count(dir);
    goto out;
}

static int exofs_unlink(struct inode *dir, struct dentry *dentry)
{
    struct inode *inode = dentry->d_inode;
    struct exofs_dir_entry *de;
    struct page *page;
    int err = -ENOENT;

    de = exofs_find_entry(dir, dentry, &page);
    if (!de)
        goto out;

    err = exofs_delete_entry(de, page);
    if (err)
        goto out;

    inode->i_ctime = dir->i_ctime;
    inode_dec_link_count(inode);
    err = 0;
out:
    return err;
}

static int exofs_rmdir(struct inode *dir, struct dentry *dentry)
{
    struct inode *inode = dentry->d_inode;
    int err = -ENOTEMPTY;

    if (exofs_empty_dir(inode)) {
        err = exofs_unlink(dir, dentry);
        if (!err) {
            inode->i_size = 0;
            inode_dec_link_count(inode);
            inode_dec_link_count(dir);
        }
    }
    return err;
}

static int exofs_rename(struct inode *old_dir, struct dentry *old_dentry,
        struct inode *new_dir, struct dentry *new_dentry)
{
    struct inode *old_inode = old_dentry->d_inode;
    struct inode *new_inode = new_dentry->d_inode;
    struct page *dir_page = NULL;
    struct exofs_dir_entry *dir_de = NULL;
    struct page *old_page;
    struct exofs_dir_entry *old_de;
    int err = -ENOENT;

    old_de = exofs_find_entry(old_dir, old_dentry, &old_page);
    if (!old_de)
        goto out;

    if (S_ISDIR(old_inode->i_mode)) {
        err = -EIO;
        dir_de = exofs_dotdot(old_inode, &dir_page);
        if (!dir_de)
            goto out_old;
    }

    if (new_inode) {
        struct page *new_page;
        struct exofs_dir_entry *new_de;

        err = -ENOTEMPTY;
        if (dir_de && !exofs_empty_dir(new_inode))
            goto out_dir;

        err = -ENOENT;
        new_de = exofs_find_entry(new_dir, new_dentry, &new_page);
        if (!new_de)
            goto out_dir;
        err = exofs_set_link(new_dir, new_de, new_page, old_inode);
        new_inode->i_ctime = CURRENT_TIME;
        if (dir_de)
            drop_nlink(new_inode);
        inode_dec_link_count(new_inode);
        if (err)
            goto out_dir;
    } else {
        err = exofs_add_link(new_dentry, old_inode);
        if (err)
            goto out_dir;
        if (dir_de)
            inode_inc_link_count(new_dir);
    }

    old_inode->i_ctime = CURRENT_TIME;

    exofs_delete_entry(old_de, old_page);
    mark_inode_dirty(old_inode);

    if (dir_de) {
        err = exofs_set_link(old_inode, dir_de, dir_page, new_dir);
        inode_dec_link_count(old_dir);
        if (err)
            goto out_dir;
    }
    return 0;


out_dir:
    if (dir_de) {
        kunmap(dir_page);
        page_cache_release(dir_page);
    }
out_old:
    kunmap(old_page);
    page_cache_release(old_page);
out:
    return err;
}

const struct inode_operations exofs_dir_inode_operations = {
    .create     = exofs_create,
    .lookup     = exofs_lookup,
    .link       = exofs_link,
    .unlink     = exofs_unlink,
    .symlink    = exofs_symlink,
    .mkdir      = exofs_mkdir,
    .rmdir      = exofs_rmdir,
    .mknod      = exofs_mknod,
    .rename     = exofs_rename,
    .setattr    = exofs_setattr,
};

const struct inode_operations exofs_special_inode_operations = {
    .setattr    = exofs_setattr,
};