/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * inode.c - basic inode and dentry operations.
   *
   * 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., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   *
   * Based on sysfs:
   * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
   *
   * configfs Copyright (C) 2005 Oracle.  All rights reserved.
   *
   * Please see Documentation/filesystems/configfs.txt for more information.
   */
  
  #undef DEBUG
  
  #include <linux/pagemap.h>
  #include <linux/namei.h>
  #include <linux/backing-dev.h>

  #include <linux/capability.h>

  #include <linux/sched.h>

  
  #include <linux/configfs.h>
  #include "configfs_internal.h"
  
  extern struct super_block * configfs_sb;

  static const struct address_space_operations configfs_aops = {

  	.readpage	= simple_readpage,
  	.prepare_write	= simple_prepare_write,
  	.commit_write	= simple_commit_write
  };
  
  static struct backing_dev_info configfs_backing_dev_info = {
  	.ra_pages	= 0,	/* No readahead */
  	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  };

  static const struct inode_operations configfs_inode_operations ={

  	.setattr	= configfs_setattr,
  };
  
  int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  {
  	struct inode * inode = dentry->d_inode;
  	struct configfs_dirent * sd = dentry->d_fsdata;
  	struct iattr * sd_iattr;
  	unsigned int ia_valid = iattr->ia_valid;
  	int error;
  
  	if (!sd)
  		return -EINVAL;
  
  	sd_iattr = sd->s_iattr;
  
  	error = inode_change_ok(inode, iattr);
  	if (error)
  		return error;
  
  	error = inode_setattr(inode, iattr);
  	if (error)
  		return error;
  
  	if (!sd_iattr) {
  		/* setting attributes for the first time, allocate now */

  		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);

  		if (!sd_iattr)
  			return -ENOMEM;
  		/* assign default attributes */

  		sd_iattr->ia_mode = sd->s_mode;
  		sd_iattr->ia_uid = 0;
  		sd_iattr->ia_gid = 0;
  		sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  		sd->s_iattr = sd_iattr;
  	}
  
  	/* attributes were changed atleast once in past */
  
  	if (ia_valid & ATTR_UID)
  		sd_iattr->ia_uid = iattr->ia_uid;
  	if (ia_valid & ATTR_GID)
  		sd_iattr->ia_gid = iattr->ia_gid;
  	if (ia_valid & ATTR_ATIME)
  		sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  						inode->i_sb->s_time_gran);
  	if (ia_valid & ATTR_MTIME)
  		sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  						inode->i_sb->s_time_gran);
  	if (ia_valid & ATTR_CTIME)
  		sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
  						inode->i_sb->s_time_gran);
  	if (ia_valid & ATTR_MODE) {
  		umode_t mode = iattr->ia_mode;
  
  		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
  			mode &= ~S_ISGID;
  		sd_iattr->ia_mode = sd->s_mode = mode;
  	}
  
  	return error;
  }
  
  static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
  {
  	inode->i_mode = mode;
  	inode->i_uid = 0;
  	inode->i_gid = 0;
  	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  }
  
  static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
  {
  	inode->i_mode = iattr->ia_mode;
  	inode->i_uid = iattr->ia_uid;
  	inode->i_gid = iattr->ia_gid;
  	inode->i_atime = iattr->ia_atime;
  	inode->i_mtime = iattr->ia_mtime;
  	inode->i_ctime = iattr->ia_ctime;
  }
  
  struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)

  {
  	struct inode * inode = new_inode(configfs_sb);
  	if (inode) {

  		inode->i_blocks = 0;

  		inode->i_mapping->a_ops = &configfs_aops;
  		inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;

  		inode->i_op = &configfs_inode_operations;
  
  		if (sd->s_iattr) {
  			/* sysfs_dirent has non-default attributes
  			 * get them for the new inode from persistent copy
  			 * in sysfs_dirent
  			 */
  			set_inode_attr(inode, sd->s_iattr);
  		} else
  			set_default_inode_attr(inode, mode);

  	}
  	return inode;
  }
  
  int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
  {
  	int error = 0;
  	struct inode * inode = NULL;
  	if (dentry) {
  		if (!dentry->d_inode) {

  			struct configfs_dirent *sd = dentry->d_fsdata;
  			if ((inode = configfs_new_inode(mode, sd))) {

  				if (dentry->d_parent && dentry->d_parent->d_inode) {
  					struct inode *p_inode = dentry->d_parent->d_inode;
  					p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
  				}
  				goto Proceed;
  			}
  			else
  				error = -ENOMEM;
  		} else
  			error = -EEXIST;
  	} else
  		error = -ENOENT;
  	goto Done;
  
   Proceed:
  	if (init)
  		error = init(inode);
  	if (!error) {
  		d_instantiate(dentry, inode);
  		if (S_ISDIR(mode) || S_ISLNK(mode))
  			dget(dentry);  /* pin link and directory dentries in core */
  	} else
  		iput(inode);
   Done:
  	return error;
  }
  
  /*
   * Get the name for corresponding element represented by the given configfs_dirent
   */
  const unsigned char * configfs_get_name(struct configfs_dirent *sd)
  {

  	struct configfs_attribute *attr;

  	BUG_ON(!sd || !sd->s_element);

  
  	/* These always have a dentry, so use that */
  	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
  		return sd->s_dentry->d_name.name;
  
  	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
  		attr = sd->s_element;

  		return attr->ca_name;

  	}
  	return NULL;
  }
  
  
  /*
   * Unhashes the dentry corresponding to given configfs_dirent

   * Called with parent inode's i_mutex held.

   */
  void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
  {
  	struct dentry * dentry = sd->s_dentry;
  
  	if (dentry) {
  		spin_lock(&dcache_lock);

  		spin_lock(&dentry->d_lock);

  		if (!(d_unhashed(dentry) && dentry->d_inode)) {
  			dget_locked(dentry);
  			__d_drop(dentry);

  			spin_unlock(&dentry->d_lock);

  			spin_unlock(&dcache_lock);
  			simple_unlink(parent->d_inode, dentry);

  		} else {
  			spin_unlock(&dentry->d_lock);

  			spin_unlock(&dcache_lock);

  		}

  	}
  }
  
  void configfs_hash_and_remove(struct dentry * dir, const char * name)
  {
  	struct configfs_dirent * sd;
  	struct configfs_dirent * parent_sd = dir->d_fsdata;

  	if (dir->d_inode == NULL)
  		/* no inode means this hasn't been made visible yet */
  		return;

  	mutex_lock(&dir->d_inode->i_mutex);

  	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
  		if (!sd->s_element)
  			continue;
  		if (!strcmp(configfs_get_name(sd), name)) {
  			list_del_init(&sd->s_sibling);
  			configfs_drop_dentry(sd, dir);
  			configfs_put(sd);
  			break;
  		}
  	}

  	mutex_unlock(&dir->d_inode->i_mutex);

  }