/*
 *  linux/fs/sysv/namei.c
 *
 *  minix/namei.c
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  coh/namei.c
 *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 *
 *  sysv/namei.c
 *  Copyright (C) 1993  Bruno Haible
 *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
 */

#include <linux/fs.h>
#include <linux/sysv_fs.h>
#include <linux/pagemap.h>

static inline void inc_count(struct inode *inode)
{
        inode->i_nlink++;
        mark_inode_dirty(inode);
}

static inline void dec_count(struct inode *inode)
{
        inode->i_nlink--;
        mark_inode_dirty(inode);
}

static int add_nondir(struct dentry *dentry, struct inode *inode)
{
        int err = sysv_add_link(dentry, inode);
        if (!err) {
                d_instantiate(dentry, inode);
                return 0;
        }
        dec_count(inode);
        iput(inode);
        return err;
}

static int sysv_hash(struct dentry *dentry, struct qstr *qstr)
{
        unsigned long hash;
        int i;
        const unsigned char *name;

        i = SYSV_NAMELEN;
        if (i >= qstr->len)
                return 0;
        /* Truncate the name in place, avoids having to define a compare
           function. */
        qstr->len = i;
        name = qstr->name;
        hash = init_name_hash();
        while (i--)
                hash = partial_name_hash(*name++, hash);
        qstr->hash = end_name_hash(hash);
        return 0;
}

struct dentry_operations sysv_dentry_operations = {
        d_hash:         sysv_hash,
};

static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry)
{
        struct inode * inode = NULL;
        ino_t ino;

        dentry->d_op = dir->i_sb->s_root->d_op;
        if (dentry->d_name.len > SYSV_NAMELEN)
                return ERR_PTR(-ENAMETOOLONG);
        ino = sysv_inode_by_name(dentry);

        if (ino) {
                inode = iget(dir->i_sb, ino);
                if (!inode) 
                        return ERR_PTR(-EACCES);
        }
        d_add(dentry, inode);
        return NULL;
}

static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, int rdev)
{
        struct inode * inode = sysv_new_inode(dir, mode);
        int err = PTR_ERR(inode);

        if (!IS_ERR(inode)) {
                sysv_set_inode(inode, rdev);
                mark_inode_dirty(inode);
                err = add_nondir(dentry, inode);
        }
        return err;
}

static int sysv_create(struct inode * dir, struct dentry * dentry, int mode)
{
        return sysv_mknod(dir, dentry, mode, 0);
}

static int sysv_symlink(struct inode * dir, struct dentry * dentry, 
        const char * symname)
{
        int err = -ENAMETOOLONG;
        int l = strlen(symname)+1;
        struct inode * inode;

        if (l > dir->i_sb->s_blocksize)
                goto out;

        inode = sysv_new_inode(dir, S_IFLNK|0777);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
                goto out;
        
        sysv_set_inode(inode, 0);
        err = block_symlink(inode, symname, l);
        if (err)
                goto out_fail;

        mark_inode_dirty(inode);
        err = add_nondir(dentry, inode);
out:
        return err;

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

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

        if (S_ISDIR(inode->i_mode))
                return -EPERM;

        if (inode->i_nlink >= inode->i_sb->sv_link_max)
                return -EMLINK;

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

        return add_nondir(dentry, inode);
}

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

        if (dir->i_nlink >= dir->i_sb->sv_link_max) 
                goto out;
        inc_count(dir);

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

        sysv_set_inode(inode, 0);

        inc_count(inode);

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

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

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

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

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

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

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

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

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

        if (sysv_empty_dir(inode)) {
                err = sysv_unlink(dir, dentry);
                if (!err) {
                        inode->i_size = 0;
                        dec_count(inode);
                        dec_count(dir);
                }
        }
        return err;
}

/*
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
static int sysv_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 sysv_dir_entry * dir_de = NULL;
        struct page * old_page;
        struct sysv_dir_entry * old_de;
        int err = -ENOENT;

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

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

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

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

                err = -ENOENT;
                new_de = sysv_find_entry(new_dentry, &new_page);
                if (!new_de)
                        goto out_dir;
                inc_count(old_inode);
                sysv_set_link(new_de, new_page, old_inode);
                new_inode->i_ctime = CURRENT_TIME;
                if (dir_de)
                        new_inode->i_nlink--;
                dec_count(new_inode);
        } else {
                if (dir_de) {
                        err = -EMLINK;
                        if (new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
                                goto out_dir;
                }
                inc_count(old_inode);
                err = sysv_add_link(new_dentry, old_inode);
                if (err) {
                        dec_count(old_inode);
                        goto out_dir;
                }
                if (dir_de)
                        inc_count(new_dir);
        }

        sysv_delete_entry(old_de, old_page);
        dec_count(old_inode);

        if (dir_de) {
                sysv_set_link(dir_de, dir_page, new_dir);
                dec_count(old_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;
}

/*
 * directories can handle most operations...
 */
struct inode_operations sysv_dir_inode_operations = {
        create:         sysv_create,
        lookup:         sysv_lookup,
        link:           sysv_link,
        unlink:         sysv_unlink,
        symlink:        sysv_symlink,
        mkdir:          sysv_mkdir,
        rmdir:          sysv_rmdir,
        mknod:          sysv_mknod,
        rename:         sysv_rename,
};