/*
   * linux/fs/ext2/namei.c
   *
   * Rewrite to pagecache. Almost all code had been changed, so blame me
   * if the things go wrong. Please, send bug reports to
   * viro@parcelfarce.linux.theplanet.co.uk
   *
   * Stuff here is basically a glue between the VFS and generic UNIXish
   * filesystem that keeps everything in pagecache. All knowledge of the
   * directory layout is in fs/ext2/dir.c - it turned out to be easily separatable
   * and it's easier to debug that way. In principle we might want to
   * generalize that a bit and turn it into a library. Or not.
   *
   * The only non-static object here is ext2_dir_inode_operations.
   *
   * TODO: get rid of kmap() use, add readahead.
   *
   * 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/namei.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *
   *  Big-endian to little-endian byte-swapping/bitmaps by
   *        David S. Miller (davem@caip.rutgers.edu), 1995
   */
  
  #include <linux/pagemap.h>

  #include <linux/quotaops.h>

  #include "ext2.h"
  #include "xattr.h"
  #include "acl.h"

  #include "xip.h"

  static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
  {
  	int err = ext2_add_link(dentry, inode);
  	if (!err) {
  		d_instantiate(dentry, inode);

  		unlock_new_inode(inode);

  		return 0;
  	}

  	inode_dec_link_count(inode);

  	unlock_new_inode(inode);

  	iput(inode);
  	return err;
  }
  
  /*
   * Methods themselves.
   */
  
  static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
  {
  	struct inode * inode;
  	ino_t ino;
  	
  	if (dentry->d_name.len > EXT2_NAME_LEN)
  		return ERR_PTR(-ENAMETOOLONG);

  	ino = ext2_inode_by_name(dir, &dentry->d_name);

  	inode = NULL;
  	if (ino) {

  		inode = ext2_iget(dir->i_sb, ino);

  		if (IS_ERR(inode)) {

  			if (PTR_ERR(inode) == -ESTALE) {
  				ext2_error(dir->i_sb, __func__,
  						"deleted inode referenced: %lu",

  						(unsigned long) ino);

  				return ERR_PTR(-EIO);
  			} else {
  				return ERR_CAST(inode);
  			}
  		}

  	}

  	return d_splice_alias(inode, dentry);

  }
  
  struct dentry *ext2_get_parent(struct dentry *child)
  {

  	struct qstr dotdot = {.name = "..", .len = 2};
  	unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);

  	if (!ino)
  		return ERR_PTR(-ENOENT);

  	return d_obtain_alias(ext2_iget(child->d_inode->i_sb, ino));

  } 
  
  /*
   * By the time this is called, we already have created
   * the directory cache entry for the new file, but it
   * is so far negative - it has no inode.
   *
   * If the create succeeds, we fill in the inode information
   * with d_instantiate(). 
   */
  static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
  {

  	struct inode *inode;

  	dquot_initialize(dir);

  	inode = ext2_new_inode(dir, mode, &dentry->d_name);

  	if (IS_ERR(inode))
  		return PTR_ERR(inode);
  
  	inode->i_op = &ext2_file_inode_operations;
  	if (ext2_use_xip(inode->i_sb)) {
  		inode->i_mapping->a_ops = &ext2_aops_xip;
  		inode->i_fop = &ext2_xip_file_operations;
  	} else if (test_opt(inode->i_sb, NOBH)) {
  		inode->i_mapping->a_ops = &ext2_nobh_aops;
  		inode->i_fop = &ext2_file_operations;
  	} else {
  		inode->i_mapping->a_ops = &ext2_aops;
  		inode->i_fop = &ext2_file_operations;

  	}

  	mark_inode_dirty(inode);
  	return ext2_add_nondir(dentry, inode);

  }
  
  static int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, dev_t rdev)
  {
  	struct inode * inode;
  	int err;
  
  	if (!new_valid_dev(rdev))
  		return -EINVAL;

  	dquot_initialize(dir);

  	inode = ext2_new_inode (dir, mode, &dentry->d_name);

  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {
  		init_special_inode(inode, inode->i_mode, rdev);
  #ifdef CONFIG_EXT2_FS_XATTR
  		inode->i_op = &ext2_special_inode_operations;
  #endif
  		mark_inode_dirty(inode);
  		err = ext2_add_nondir(dentry, inode);
  	}
  	return err;
  }
  
  static int ext2_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;
  
  	if (l > sb->s_blocksize)
  		goto out;

  	dquot_initialize(dir);

  	inode = ext2_new_inode (dir, S_IFLNK | S_IRWXUGO, &dentry->d_name);

  	err = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out;
  
  	if (l > sizeof (EXT2_I(inode)->i_data)) {
  		/* slow symlink */
  		inode->i_op = &ext2_symlink_inode_operations;
  		if (test_opt(inode->i_sb, NOBH))
  			inode->i_mapping->a_ops = &ext2_nobh_aops;
  		else
  			inode->i_mapping->a_ops = &ext2_aops;
  		err = page_symlink(inode, symname, l);
  		if (err)
  			goto out_fail;
  	} else {
  		/* fast symlink */
  		inode->i_op = &ext2_fast_symlink_inode_operations;
  		memcpy((char*)(EXT2_I(inode)->i_data),symname,l);
  		inode->i_size = l-1;
  	}
  	mark_inode_dirty(inode);
  
  	err = ext2_add_nondir(dentry, inode);
  out:
  	return err;
  
  out_fail:

  	inode_dec_link_count(inode);

  	unlock_new_inode(inode);

  	iput (inode);
  	goto out;
  }
  
  static int ext2_link (struct dentry * old_dentry, struct inode * dir,
  	struct dentry *dentry)
  {
  	struct inode *inode = old_dentry->d_inode;

  	int err;

  
  	if (inode->i_nlink >= EXT2_LINK_MAX)
  		return -EMLINK;

  	dquot_initialize(dir);

  	inode->i_ctime = CURRENT_TIME_SEC;

  	inode_inc_link_count(inode);

  	ihold(inode);

  	err = ext2_add_link(dentry, inode);
  	if (!err) {
  		d_instantiate(dentry, inode);
  		return 0;
  	}
  	inode_dec_link_count(inode);
  	iput(inode);
  	return err;

  }
  
  static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
  {
  	struct inode * inode;
  	int err = -EMLINK;
  
  	if (dir->i_nlink >= EXT2_LINK_MAX)
  		goto out;

  	dquot_initialize(dir);

  	inode_inc_link_count(dir);

  	inode = ext2_new_inode(dir, S_IFDIR | mode, &dentry->d_name);

  	err = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out_dir;
  
  	inode->i_op = &ext2_dir_inode_operations;
  	inode->i_fop = &ext2_dir_operations;
  	if (test_opt(inode->i_sb, NOBH))
  		inode->i_mapping->a_ops = &ext2_nobh_aops;
  	else
  		inode->i_mapping->a_ops = &ext2_aops;

  	inode_inc_link_count(inode);

  
  	err = ext2_make_empty(inode, dir);
  	if (err)
  		goto out_fail;
  
  	err = ext2_add_link(dentry, inode);
  	if (err)
  		goto out_fail;
  
  	d_instantiate(dentry, inode);

  	unlock_new_inode(inode);

  out:
  	return err;
  
  out_fail:

  	inode_dec_link_count(inode);
  	inode_dec_link_count(inode);

  	unlock_new_inode(inode);

  	iput(inode);
  out_dir:

  	inode_dec_link_count(dir);

  	goto out;
  }
  
  static int ext2_unlink(struct inode * dir, struct dentry *dentry)
  {
  	struct inode * inode = dentry->d_inode;
  	struct ext2_dir_entry_2 * de;
  	struct page * page;
  	int err = -ENOENT;

  	dquot_initialize(dir);

  	de = ext2_find_entry (dir, &dentry->d_name, &page);

  	if (!de)
  		goto out;
  
  	err = ext2_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 ext2_rmdir (struct inode * dir, struct dentry *dentry)
  {
  	struct inode * inode = dentry->d_inode;
  	int err = -ENOTEMPTY;
  
  	if (ext2_empty_dir(inode)) {
  		err = ext2_unlink(dir, dentry);
  		if (!err) {
  			inode->i_size = 0;

  			inode_dec_link_count(inode);
  			inode_dec_link_count(dir);

  		}
  	}
  	return err;
  }
  
  static int ext2_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 ext2_dir_entry_2 * dir_de = NULL;
  	struct page * old_page;
  	struct ext2_dir_entry_2 * old_de;
  	int err = -ENOENT;

  	dquot_initialize(old_dir);
  	dquot_initialize(new_dir);

  	old_de = ext2_find_entry (old_dir, &old_dentry->d_name, &old_page);

  	if (!old_de)
  		goto out;
  
  	if (S_ISDIR(old_inode->i_mode)) {
  		err = -EIO;
  		dir_de = ext2_dotdot(old_inode, &dir_page);
  		if (!dir_de)
  			goto out_old;
  	}
  
  	if (new_inode) {
  		struct page *new_page;
  		struct ext2_dir_entry_2 *new_de;
  
  		err = -ENOTEMPTY;
  		if (dir_de && !ext2_empty_dir (new_inode))
  			goto out_dir;
  
  		err = -ENOENT;

  		new_de = ext2_find_entry (new_dir, &new_dentry->d_name, &new_page);

  		if (!new_de)
  			goto out_dir;

  		ext2_set_link(new_dir, new_de, new_page, old_inode, 1);

  		new_inode->i_ctime = CURRENT_TIME_SEC;
  		if (dir_de)

  			drop_nlink(new_inode);

  		inode_dec_link_count(new_inode);

  	} else {
  		if (dir_de) {
  			err = -EMLINK;
  			if (new_dir->i_nlink >= EXT2_LINK_MAX)
  				goto out_dir;
  		}

  		err = ext2_add_link(new_dentry, old_inode);

  		if (err)

  			goto out_dir;

  		if (dir_de)

  			inode_inc_link_count(new_dir);

  	}
  
  	/*
  	 * Like most other Unix systems, set the ctime for inodes on a
   	 * rename.

  	 */
  	old_inode->i_ctime = CURRENT_TIME_SEC;

  	mark_inode_dirty(old_inode);

  
  	ext2_delete_entry (old_de, old_page);

  
  	if (dir_de) {

  		if (old_dir != new_dir)
  			ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);

  		else {
  			kunmap(dir_page);
  			page_cache_release(dir_page);
  		}

  		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;
  }

  const struct inode_operations ext2_dir_inode_operations = {

  	.create		= ext2_create,
  	.lookup		= ext2_lookup,
  	.link		= ext2_link,
  	.unlink		= ext2_unlink,
  	.symlink	= ext2_symlink,
  	.mkdir		= ext2_mkdir,
  	.rmdir		= ext2_rmdir,
  	.mknod		= ext2_mknod,
  	.rename		= ext2_rename,
  #ifdef CONFIG_EXT2_FS_XATTR
  	.setxattr	= generic_setxattr,
  	.getxattr	= generic_getxattr,
  	.listxattr	= ext2_listxattr,
  	.removexattr	= generic_removexattr,
  #endif
  	.setattr	= ext2_setattr,

  	.check_acl	= ext2_check_acl,

  };

  const struct inode_operations ext2_special_inode_operations = {

  #ifdef CONFIG_EXT2_FS_XATTR
  	.setxattr	= generic_setxattr,
  	.getxattr	= generic_getxattr,
  	.listxattr	= ext2_listxattr,
  	.removexattr	= generic_removexattr,
  #endif
  	.setattr	= ext2_setattr,

  	.check_acl	= ext2_check_acl,

  };