/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger (avishay@gmail.com)
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <bharrosh@panasas.com>
 *
 * Copyrights for code taken from ext2:
 *     Copyright (C) 1992, 1993, 1994, 1995
 *     Remy Card (card@masi.ibp.fr)
 *     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,
                                   struct nameidata *nd)
{
        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 = NULL;
        if (ino) {
                inode = exofs_iget(dir->i_sb, ino);
                if (IS_ERR(inode))
                        return ERR_CAST(inode);
        }
        return d_splice_alias(inode, dentry);
}

static int exofs_create(struct inode *dir, struct dentry *dentry, int mode,
                         struct nameidata *nd)
{
        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, int 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;

        if (inode->i_nlink >= EXOFS_LINK_MAX)
                return -EMLINK;

        inode->i_ctime = CURRENT_TIME;
        inode_inc_link_count(inode);
        atomic_inc(&inode->i_count);

        return exofs_add_nondir(dentry, inode);
}

static int exofs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        struct inode *inode;
        int err = -EMLINK;

        if (dir->i_nlink >= EXOFS_LINK_MAX)
                goto out;

        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;
                inode_inc_link_count(old_inode);
                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 {
                if (dir_de) {
                        err = -EMLINK;
                        if (new_dir->i_nlink >= EXOFS_LINK_MAX)
                                goto out_dir;
                }
                inode_inc_link_count(old_inode);
                err = exofs_add_link(new_dentry, old_inode);
                if (err) {
                        inode_dec_link_count(old_inode);
                        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);
        inode_dec_link_count(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,
};