/* -*- 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/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/lockdep.h>
  #include <linux/slab.h>
  
  #include <linux/configfs.h>
  #include "configfs_internal.h"
  
  #ifdef CONFIG_LOCKDEP
  static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  #endif
  
  static const struct address_space_operations configfs_aops = {
  	.readpage	= simple_readpage,
  	.write_begin	= simple_write_begin,
  	.write_end	= simple_write_end,
  };
  
  static struct backing_dev_info configfs_backing_dev_info = {
  	.name		= "configfs",
  	.ra_pages	= 0,	/* No readahead */
  	.capabilities	= BDI_CAP_NO_ACCT_AND_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;
  	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 = GLOBAL_ROOT_UID;
  		sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  		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 */
  
  	error = simple_setattr(dentry, iattr);
  	if (error)
  		return error;
  
  	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, umode_t mode)
  {
  	inode->i_mode = mode;
  	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(umode_t mode, struct configfs_dirent *sd,
  				 struct super_block *s)
  {
  	struct inode * inode = new_inode(s);
  	if (inode) {
  		inode->i_ino = get_next_ino();
  		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;
  }
  
  #ifdef CONFIG_LOCKDEP
  
  static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
  					  struct inode *inode)
  {
  	int depth = sd->s_depth;
  
  	if (depth > 0) {
  		if (depth <= ARRAY_SIZE(default_group_class)) {
  			lockdep_set_class(&inode->i_mutex,
  					  &default_group_class[depth - 1]);
  		} else {
  			/*
  			 * In practice the maximum level of locking depth is
  			 * already reached. Just inform about possible reasons.
  			 */
  			printk(KERN_INFO "configfs: Too many levels of inodes"
  			       " for the locking correctness validator.
  ");
  			printk(KERN_INFO "Spurious warnings may appear.
  ");
  		}
  	}
  }
  
  #else /* CONFIG_LOCKDEP */
  
  static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
  					  struct inode *inode)
  {
  }
  
  #endif /* CONFIG_LOCKDEP */
  
  int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
  {
  	int error = 0;
  	struct inode *inode = NULL;
  	struct configfs_dirent *sd;
  	struct inode *p_inode;
  
  	if (!dentry)
  		return -ENOENT;
  
  	if (dentry->d_inode)
  		return -EEXIST;
  
  	sd = dentry->d_fsdata;
  	inode = configfs_new_inode(mode, sd, dentry->d_sb);
  	if (!inode)
  		return -ENOMEM;
  
  	p_inode = dentry->d_parent->d_inode;
  	p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
  	configfs_set_inode_lock_class(sd, inode);
  
  	if (init) {
  		error = init(inode);
  		if (error) {
  			iput(inode);
  			return error;
  		}
  	}
  	d_instantiate(dentry, inode);
  	if (S_ISDIR(mode) || S_ISLNK(mode))
  		dget(dentry);  /* pin link and directory dentries in core */
  	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(&dentry->d_lock);
  		if (!(d_unhashed(dentry) && dentry->d_inode)) {
  			dget_dlock(dentry);
  			__d_drop(dentry);
  			spin_unlock(&dentry->d_lock);
  			simple_unlink(parent->d_inode, dentry);
  		} else
  			spin_unlock(&dentry->d_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)) {
  			spin_lock(&configfs_dirent_lock);
  			list_del_init(&sd->s_sibling);
  			spin_unlock(&configfs_dirent_lock);
  			configfs_drop_dentry(sd, dir);
  			configfs_put(sd);
  			break;
  		}
  	}
  	mutex_unlock(&dir->d_inode->i_mutex);
  }
  
  int __init configfs_inode_init(void)
  {
  	return bdi_init(&configfs_backing_dev_info);
  }
  
  void configfs_inode_exit(void)
  {
  	bdi_destroy(&configfs_backing_dev_info);
  }