/*
   * namei.c - NILFS pathname lookup operations.
   *
   * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   *
   * This program 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; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program 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 this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *
   * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>,
   *                       Ryusuke Konishi <ryusuke@osrg.net>
   */
  /*
   *  linux/fs/ext2/namei.c
   *
   * 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 "nilfs.h"

  #include "export.h"

  #define NILFS_FID_SIZE_NON_CONNECTABLE \
  	(offsetof(struct nilfs_fid, parent_gen) / 4)
  #define NILFS_FID_SIZE_CONNECTABLE	(sizeof(struct nilfs_fid) / 4)

  
  static inline int nilfs_add_nondir(struct dentry *dentry, struct inode *inode)
  {
  	int err = nilfs_add_link(dentry, inode);
  	if (!err) {
  		d_instantiate(dentry, inode);
  		return 0;
  	}
  	inode_dec_link_count(inode);
  	iput(inode);
  	return err;
  }
  
  /*
   * Methods themselves.
   */
  
  static struct dentry *
  nilfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
  {
  	struct inode *inode;
  	ino_t ino;
  
  	if (dentry->d_name.len > NILFS_NAME_LEN)
  		return ERR_PTR(-ENAMETOOLONG);

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

  	inode = ino ? nilfs_iget(dir->i_sb, NILFS_I(dir)->i_root, ino) : NULL;

  	return d_splice_alias(inode, dentry);
  }

  /*
   * 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 nilfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,

  			struct nameidata *nd)
  {
  	struct inode *inode;
  	struct nilfs_transaction_info ti;

  	int err;

  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
  	if (err)
  		return err;
  	inode = nilfs_new_inode(dir, mode);
  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {
  		inode->i_op = &nilfs_file_inode_operations;
  		inode->i_fop = &nilfs_file_operations;
  		inode->i_mapping->a_ops = &nilfs_aops;

  		nilfs_mark_inode_dirty(inode);

  		err = nilfs_add_nondir(dentry, inode);
  	}

  	if (!err)
  		err = nilfs_transaction_commit(dir->i_sb);
  	else
  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  }
  
  static int

  nilfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)

  {
  	struct inode *inode;
  	struct nilfs_transaction_info ti;

  	int err;

  
  	if (!new_valid_dev(rdev))
  		return -EINVAL;
  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
  	if (err)
  		return err;
  	inode = nilfs_new_inode(dir, mode);
  	err = PTR_ERR(inode);
  	if (!IS_ERR(inode)) {
  		init_special_inode(inode, inode->i_mode, rdev);

  		nilfs_mark_inode_dirty(inode);

  		err = nilfs_add_nondir(dentry, inode);
  	}

  	if (!err)
  		err = nilfs_transaction_commit(dir->i_sb);
  	else
  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  }
  
  static int nilfs_symlink(struct inode *dir, struct dentry *dentry,
  			 const char *symname)
  {
  	struct nilfs_transaction_info ti;
  	struct super_block *sb = dir->i_sb;
  	unsigned l = strlen(symname)+1;
  	struct inode *inode;

  	int err;

  
  	if (l > sb->s_blocksize)
  		return -ENAMETOOLONG;
  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
  	if (err)
  		return err;
  
  	inode = nilfs_new_inode(dir, S_IFLNK | S_IRWXUGO);
  	err = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out;
  
  	/* slow symlink */
  	inode->i_op = &nilfs_symlink_inode_operations;
  	inode->i_mapping->a_ops = &nilfs_aops;
  	err = page_symlink(inode, symname, l);
  	if (err)
  		goto out_fail;
  
  	/* mark_inode_dirty(inode); */

  	/* page_symlink() do this */

  
  	err = nilfs_add_nondir(dentry, inode);
  out:

  	if (!err)
  		err = nilfs_transaction_commit(dir->i_sb);
  	else
  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  
  out_fail:

  	drop_nlink(inode);

  	nilfs_mark_inode_dirty(inode);

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

  	int err;

  
  	if (inode->i_nlink >= NILFS_LINK_MAX)
  		return -EMLINK;
  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
  	if (err)
  		return err;
  
  	inode->i_ctime = CURRENT_TIME;
  	inode_inc_link_count(inode);

  	ihold(inode);

  
  	err = nilfs_add_nondir(dentry, inode);

  	if (!err)
  		err = nilfs_transaction_commit(dir->i_sb);
  	else
  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  }

  static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)

  {
  	struct inode *inode;
  	struct nilfs_transaction_info ti;

  	int err;

  
  	if (dir->i_nlink >= NILFS_LINK_MAX)
  		return -EMLINK;
  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
  	if (err)
  		return err;

  	inc_nlink(dir);

  
  	inode = nilfs_new_inode(dir, S_IFDIR | mode);
  	err = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out_dir;
  
  	inode->i_op = &nilfs_dir_inode_operations;
  	inode->i_fop = &nilfs_dir_operations;
  	inode->i_mapping->a_ops = &nilfs_aops;

  	inc_nlink(inode);

  
  	err = nilfs_make_empty(inode, dir);
  	if (err)
  		goto out_fail;
  
  	err = nilfs_add_link(dentry, inode);
  	if (err)
  		goto out_fail;

  	nilfs_mark_inode_dirty(inode);

  	d_instantiate(dentry, inode);
  out:

  	if (!err)
  		err = nilfs_transaction_commit(dir->i_sb);
  	else
  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  
  out_fail:

  	drop_nlink(inode);

  	drop_nlink(inode);

  	nilfs_mark_inode_dirty(inode);

  	iput(inode);
  out_dir:

  	drop_nlink(dir);

  	nilfs_mark_inode_dirty(dir);

  	goto out;
  }

  static int nilfs_do_unlink(struct inode *dir, struct dentry *dentry)

  {
  	struct inode *inode;
  	struct nilfs_dir_entry *de;
  	struct page *page;

  	int err;

  	err = -ENOENT;

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

  	if (!de)
  		goto out;
  
  	inode = dentry->d_inode;
  	err = -EIO;
  	if (le64_to_cpu(de->inode) != inode->i_ino)
  		goto out;
  
  	if (!inode->i_nlink) {
  		nilfs_warning(inode->i_sb, __func__,
  			      "deleting nonexistent file (%lu), %d
  ",
  			      inode->i_ino, inode->i_nlink);

  		set_nlink(inode, 1);

  	}
  	err = nilfs_delete_entry(de, page);
  	if (err)
  		goto out;
  
  	inode->i_ctime = dir->i_ctime;

  	drop_nlink(inode);

  	err = 0;
  out:

  	return err;
  }
  
  static int nilfs_unlink(struct inode *dir, struct dentry *dentry)
  {
  	struct nilfs_transaction_info ti;
  	int err;
  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
  	if (err)
  		return err;
  
  	err = nilfs_do_unlink(dir, dentry);
  
  	if (!err) {

  		nilfs_mark_inode_dirty(dir);
  		nilfs_mark_inode_dirty(dentry->d_inode);

  		err = nilfs_transaction_commit(dir->i_sb);

  	} else

  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  }
  
  static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
  {
  	struct inode *inode = dentry->d_inode;
  	struct nilfs_transaction_info ti;

  	int err;

  
  	err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
  	if (err)
  		return err;
  
  	err = -ENOTEMPTY;
  	if (nilfs_empty_dir(inode)) {

  		err = nilfs_do_unlink(dir, dentry);

  		if (!err) {
  			inode->i_size = 0;

  			drop_nlink(inode);

  			nilfs_mark_inode_dirty(inode);

  			drop_nlink(dir);

  			nilfs_mark_inode_dirty(dir);

  		}
  	}

  	if (!err)
  		err = nilfs_transaction_commit(dir->i_sb);
  	else
  		nilfs_transaction_abort(dir->i_sb);
  
  	return err;

  }
  
  static int nilfs_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 nilfs_dir_entry *dir_de = NULL;
  	struct page *old_page;
  	struct nilfs_dir_entry *old_de;
  	struct nilfs_transaction_info ti;
  	int err;
  
  	err = nilfs_transaction_begin(old_dir->i_sb, &ti, 1);
  	if (unlikely(err))
  		return err;
  
  	err = -ENOENT;

  	old_de = nilfs_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 = nilfs_dotdot(old_inode, &dir_page);
  		if (!dir_de)
  			goto out_old;
  	}
  
  	if (new_inode) {
  		struct page *new_page;
  		struct nilfs_dir_entry *new_de;
  
  		err = -ENOTEMPTY;
  		if (dir_de && !nilfs_empty_dir(new_inode))
  			goto out_dir;
  
  		err = -ENOENT;

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

  		if (!new_de)
  			goto out_dir;

  		nilfs_set_link(new_dir, new_de, new_page, old_inode);

  		nilfs_mark_inode_dirty(new_dir);

  		new_inode->i_ctime = CURRENT_TIME;
  		if (dir_de)
  			drop_nlink(new_inode);

  		drop_nlink(new_inode);

  		nilfs_mark_inode_dirty(new_inode);

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

  		err = nilfs_add_link(new_dentry, old_inode);

  		if (err)

  			goto out_dir;

  		if (dir_de) {
  			inc_nlink(new_dir);

  			nilfs_mark_inode_dirty(new_dir);

  		}

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

  	 */
  	old_inode->i_ctime = CURRENT_TIME;
  
  	nilfs_delete_entry(old_de, old_page);

  
  	if (dir_de) {
  		nilfs_set_link(old_inode, dir_de, dir_page, new_dir);

  		drop_nlink(old_dir);

  	}

  	nilfs_mark_inode_dirty(old_dir);
  	nilfs_mark_inode_dirty(old_inode);

  	err = nilfs_transaction_commit(old_dir->i_sb);

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

  	nilfs_transaction_abort(old_dir->i_sb);

  	return err;
  }

  /*
   * Export operations
   */
  static struct dentry *nilfs_get_parent(struct dentry *child)
  {
  	unsigned long ino;
  	struct inode *inode;
  	struct qstr dotdot = {.name = "..", .len = 2};
  	struct nilfs_root *root;
  
  	ino = nilfs_inode_by_name(child->d_inode, &dotdot);
  	if (!ino)
  		return ERR_PTR(-ENOENT);
  
  	root = NILFS_I(child->d_inode)->i_root;
  
  	inode = nilfs_iget(child->d_inode->i_sb, root, ino);
  	if (IS_ERR(inode))
  		return ERR_CAST(inode);
  
  	return d_obtain_alias(inode);
  }
  
  static struct dentry *nilfs_get_dentry(struct super_block *sb, u64 cno,
  				       u64 ino, u32 gen)
  {
  	struct nilfs_root *root;
  	struct inode *inode;
  
  	if (ino < NILFS_FIRST_INO(sb) && ino != NILFS_ROOT_INO)
  		return ERR_PTR(-ESTALE);

  	root = nilfs_lookup_root(sb->s_fs_info, cno);

  	if (!root)
  		return ERR_PTR(-ESTALE);
  
  	inode = nilfs_iget(sb, root, ino);
  	nilfs_put_root(root);
  
  	if (IS_ERR(inode))
  		return ERR_CAST(inode);
  	if (gen && inode->i_generation != gen) {
  		iput(inode);
  		return ERR_PTR(-ESTALE);
  	}
  	return d_obtain_alias(inode);
  }
  
  static struct dentry *nilfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
  					 int fh_len, int fh_type)
  {
  	struct nilfs_fid *fid = (struct nilfs_fid *)fh;
  
  	if ((fh_len != NILFS_FID_SIZE_NON_CONNECTABLE &&
  	     fh_len != NILFS_FID_SIZE_CONNECTABLE) ||
  	    (fh_type != FILEID_NILFS_WITH_PARENT &&
  	     fh_type != FILEID_NILFS_WITHOUT_PARENT))
  		return NULL;
  
  	return nilfs_get_dentry(sb, fid->cno, fid->ino, fid->gen);
  }
  
  static struct dentry *nilfs_fh_to_parent(struct super_block *sb, struct fid *fh,
  					 int fh_len, int fh_type)
  {
  	struct nilfs_fid *fid = (struct nilfs_fid *)fh;
  
  	if (fh_len != NILFS_FID_SIZE_CONNECTABLE ||
  	    fh_type != FILEID_NILFS_WITH_PARENT)
  		return NULL;
  
  	return nilfs_get_dentry(sb, fid->cno, fid->parent_ino, fid->parent_gen);
  }
  
  static int nilfs_encode_fh(struct dentry *dentry, __u32 *fh, int *lenp,
  			   int connectable)
  {
  	struct nilfs_fid *fid = (struct nilfs_fid *)fh;
  	struct inode *inode = dentry->d_inode;
  	struct nilfs_root *root = NILFS_I(inode)->i_root;
  	int type;
  
  	if (*lenp < NILFS_FID_SIZE_NON_CONNECTABLE ||
  	    (connectable && *lenp < NILFS_FID_SIZE_CONNECTABLE))
  		return 255;
  
  	fid->cno = root->cno;
  	fid->ino = inode->i_ino;
  	fid->gen = inode->i_generation;
  
  	if (connectable && !S_ISDIR(inode->i_mode)) {
  		struct inode *parent;
  
  		spin_lock(&dentry->d_lock);
  		parent = dentry->d_parent->d_inode;
  		fid->parent_ino = parent->i_ino;
  		fid->parent_gen = parent->i_generation;
  		spin_unlock(&dentry->d_lock);
  
  		type = FILEID_NILFS_WITH_PARENT;
  		*lenp = NILFS_FID_SIZE_CONNECTABLE;
  	} else {
  		type = FILEID_NILFS_WITHOUT_PARENT;
  		*lenp = NILFS_FID_SIZE_NON_CONNECTABLE;
  	}
  
  	return type;
  }

  const struct inode_operations nilfs_dir_inode_operations = {

  	.create		= nilfs_create,
  	.lookup		= nilfs_lookup,
  	.link		= nilfs_link,
  	.unlink		= nilfs_unlink,
  	.symlink	= nilfs_symlink,
  	.mkdir		= nilfs_mkdir,
  	.rmdir		= nilfs_rmdir,
  	.mknod		= nilfs_mknod,
  	.rename		= nilfs_rename,
  	.setattr	= nilfs_setattr,
  	.permission	= nilfs_permission,

  	.fiemap		= nilfs_fiemap,

  };

  const struct inode_operations nilfs_special_inode_operations = {

  	.setattr	= nilfs_setattr,
  	.permission	= nilfs_permission,
  };

  const struct inode_operations nilfs_symlink_inode_operations = {

  	.readlink	= generic_readlink,
  	.follow_link	= page_follow_link_light,
  	.put_link	= page_put_link,

  	.permission     = nilfs_permission,

  };

  
  const struct export_operations nilfs_export_ops = {
  	.encode_fh = nilfs_encode_fh,
  	.fh_to_dentry = nilfs_fh_to_dentry,
  	.fh_to_parent = nilfs_fh_to_parent,
  	.get_parent = nilfs_get_parent,
  };