/*
   *  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/pagemap.h>
  #include "sysv.h"
  
  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;
  	}
  	inode_dec_link_count(inode);
  	iput(inode);
  	return err;
  }
  
  static int sysv_hash(const struct dentry *dentry, struct qstr *qstr)
  {
  	/* Truncate the name in place, avoids having to define a compare
  	   function. */
  	if (qstr->len > SYSV_NAMELEN) {
  		qstr->len = SYSV_NAMELEN;
  		qstr->hash = full_name_hash(qstr->name, qstr->len);
  	}
  	return 0;
  }
  
  const struct dentry_operations sysv_dentry_operations = {
  	.d_hash		= sysv_hash,
  };
  
  static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
  {
  	struct inode * inode = NULL;
  	ino_t ino;
  
  	if (dentry->d_name.len > SYSV_NAMELEN)
  		return ERR_PTR(-ENAMETOOLONG);
  	ino = sysv_inode_by_name(dentry);
  
  	if (ino) {
  		inode = sysv_iget(dir->i_sb, ino);
  		if (IS_ERR(inode))
  			return ERR_CAST(inode);
  	}
  	d_add(dentry, inode);
  	return NULL;
  }
  
  static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode, dev_t rdev)
  {
  	struct inode * inode;
  	int err;
  
  	if (!old_valid_dev(rdev))
  		return -EINVAL;
  
  	inode = sysv_new_inode(dir, mode);
  	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, umode_t mode, bool excl)
  {
  	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 = page_symlink(inode, symname, l);
  	if (err)
  		goto out_fail;
  
  	mark_inode_dirty(inode);
  	err = add_nondir(dentry, inode);
  out:
  	return err;
  
  out_fail:
  	inode_dec_link_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;
  
  	inode->i_ctime = CURRENT_TIME_SEC;
  	inode_inc_link_count(inode);
  	ihold(inode);
  
  	return add_nondir(dentry, inode);
  }
  
  static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
  {
  	struct inode * inode;
  	int err;
  
  	inode_inc_link_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);
  
  	inode_inc_link_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:
  	inode_dec_link_count(inode);
  	inode_dec_link_count(inode);
  	iput(inode);
  out_dir:
  	inode_dec_link_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;
  	inode_dec_link_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;
  			inode_dec_link_count(inode);
  			inode_dec_link_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;
  		sysv_set_link(new_de, new_page, old_inode);
  		new_inode->i_ctime = CURRENT_TIME_SEC;
  		if (dir_de)
  			drop_nlink(new_inode);
  		inode_dec_link_count(new_inode);
  	} else {
  		err = sysv_add_link(new_dentry, old_inode);
  		if (err)
  			goto out_dir;
  		if (dir_de)
  			inode_inc_link_count(new_dir);
  	}
  
  	sysv_delete_entry(old_de, old_page);
  	mark_inode_dirty(old_inode);
  
  	if (dir_de) {
  		sysv_set_link(dir_de, dir_page, new_dir);
  		inode_dec_link_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...
   */
  const 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,
  	.getattr	= sysv_getattr,
  };