LXR linux/fs/configfs/inode.c

   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * inode.c - basic inode and dentry operations.
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2 of the License, or (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public
  17 * License along with this program; if not, write to the
  18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 * Boston, MA 021110-1307, USA.
  20 *
  21 * Based on sysfs:
  22 *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  23 *
  24 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  25 *
  26 * Please see Documentation/filesystems/configfs/configfs.txt for more
  27 * information.
  28 */
  29
  30#undef DEBUG
  31
  32#include <linux/pagemap.h>
  33#include <linux/namei.h>
  34#include <linux/backing-dev.h>
  35#include <linux/capability.h>
  36#include <linux/sched.h>
  37#include <linux/lockdep.h>
  38#include <linux/slab.h>
  39
  40#include <linux/configfs.h>
  41#include "configfs_internal.h"
  42
  43#ifdef CONFIG_LOCKDEP
  44static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  45#endif
  46
  47static const struct address_space_operations configfs_aops = {
  48        .readpage       = simple_readpage,
  49        .write_begin    = simple_write_begin,
  50        .write_end      = simple_write_end,
  51};
  52
  53static const struct inode_operations configfs_inode_operations ={
  54        .setattr        = configfs_setattr,
  55};
  56
  57int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  58{
  59        struct inode * inode = dentry->d_inode;
  60        struct configfs_dirent * sd = dentry->d_fsdata;
  61        struct iattr * sd_iattr;
  62        unsigned int ia_valid = iattr->ia_valid;
  63        int error;
  64
  65        if (!sd)
  66                return -EINVAL;
  67
  68        sd_iattr = sd->s_iattr;
  69        if (!sd_iattr) {
  70                /* setting attributes for the first time, allocate now */
  71                sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  72                if (!sd_iattr)
  73                        return -ENOMEM;
  74                /* assign default attributes */
  75                sd_iattr->ia_mode = sd->s_mode;
  76                sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  77                sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  78                sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  79                sd->s_iattr = sd_iattr;
  80        }
  81        /* attributes were changed atleast once in past */
  82
  83        error = simple_setattr(dentry, iattr);
  84        if (error)
  85                return error;
  86
  87        if (ia_valid & ATTR_UID)
  88                sd_iattr->ia_uid = iattr->ia_uid;
  89        if (ia_valid & ATTR_GID)
  90                sd_iattr->ia_gid = iattr->ia_gid;
  91        if (ia_valid & ATTR_ATIME)
  92                sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  93                                                inode->i_sb->s_time_gran);
  94        if (ia_valid & ATTR_MTIME)
  95                sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  96                                                inode->i_sb->s_time_gran);
  97        if (ia_valid & ATTR_CTIME)
  98                sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
  99                                                inode->i_sb->s_time_gran);
 100        if (ia_valid & ATTR_MODE) {
 101                umode_t mode = iattr->ia_mode;
 102
 103                if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 104                        mode &= ~S_ISGID;
 105                sd_iattr->ia_mode = sd->s_mode = mode;
 106        }
 107
 108        return error;
 109}
 110
 111static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
 112{
 113        inode->i_mode = mode;
 114        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 115}
 116
 117static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 118{
 119        inode->i_mode = iattr->ia_mode;
 120        inode->i_uid = iattr->ia_uid;
 121        inode->i_gid = iattr->ia_gid;
 122        inode->i_atime = iattr->ia_atime;
 123        inode->i_mtime = iattr->ia_mtime;
 124        inode->i_ctime = iattr->ia_ctime;
 125}
 126
 127struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 128                                 struct super_block *s)
 129{
 130        struct inode * inode = new_inode(s);
 131        if (inode) {
 132                inode->i_ino = get_next_ino();
 133                inode->i_mapping->a_ops = &configfs_aops;
 134                inode->i_op = &configfs_inode_operations;
 135
 136                if (sd->s_iattr) {
 137                        /* sysfs_dirent has non-default attributes
 138                         * get them for the new inode from persistent copy
 139                         * in sysfs_dirent
 140                         */
 141                        set_inode_attr(inode, sd->s_iattr);
 142                } else
 143                        set_default_inode_attr(inode, mode);
 144        }
 145        return inode;
 146}
 147
 148#ifdef CONFIG_LOCKDEP
 149
 150static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 151                                          struct inode *inode)
 152{
 153        int depth = sd->s_depth;
 154
 155        if (depth > 0) {
 156                if (depth <= ARRAY_SIZE(default_group_class)) {
 157                        lockdep_set_class(&inode->i_mutex,
 158                                          &default_group_class[depth - 1]);
 159                } else {
 160                        /*
 161                         * In practice the maximum level of locking depth is
 162                         * already reached. Just inform about possible reasons.
 163                         */
 164                        pr_info("Too many levels of inodes for the locking correctness validator.\n");
 165                        pr_info("Spurious warnings may appear.\n");
 166                }
 167        }
 168}
 169
 170#else /* CONFIG_LOCKDEP */
 171
 172static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 173                                          struct inode *inode)
 174{
 175}
 176
 177#endif /* CONFIG_LOCKDEP */
 178
 179int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
 180{
 181        int error = 0;
 182        struct inode *inode = NULL;
 183        struct configfs_dirent *sd;
 184        struct inode *p_inode;
 185
 186        if (!dentry)
 187                return -ENOENT;
 188
 189        if (dentry->d_inode)
 190                return -EEXIST;
 191
 192        sd = dentry->d_fsdata;
 193        inode = configfs_new_inode(mode, sd, dentry->d_sb);
 194        if (!inode)
 195                return -ENOMEM;
 196
 197        p_inode = dentry->d_parent->d_inode;
 198        p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 199        configfs_set_inode_lock_class(sd, inode);
 200
 201        init(inode);
 202        d_instantiate(dentry, inode);
 203        if (S_ISDIR(mode) || S_ISLNK(mode))
 204                dget(dentry);  /* pin link and directory dentries in core */
 205        return error;
 206}
 207
 208/*
 209 * Get the name for corresponding element represented by the given configfs_dirent
 210 */
 211const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 212{
 213        struct configfs_attribute *attr;
 214
 215        BUG_ON(!sd || !sd->s_element);
 216
 217        /* These always have a dentry, so use that */
 218        if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 219                return sd->s_dentry->d_name.name;
 220
 221        if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 222                attr = sd->s_element;
 223                return attr->ca_name;
 224        }
 225        return NULL;
 226}
 227
 228
 229/*
 230 * Unhashes the dentry corresponding to given configfs_dirent
 231 * Called with parent inode's i_mutex held.
 232 */
 233void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 234{
 235        struct dentry * dentry = sd->s_dentry;
 236
 237        if (dentry) {
 238                spin_lock(&dentry->d_lock);
 239                if (!d_unhashed(dentry) && dentry->d_inode) {
 240                        dget_dlock(dentry);
 241                        __d_drop(dentry);
 242                        spin_unlock(&dentry->d_lock);
 243                        simple_unlink(parent->d_inode, dentry);
 244                } else
 245                        spin_unlock(&dentry->d_lock);
 246        }
 247}
 248
 249void configfs_hash_and_remove(struct dentry * dir, const char * name)
 250{
 251        struct configfs_dirent * sd;
 252        struct configfs_dirent * parent_sd = dir->d_fsdata;
 253
 254        if (dir->d_inode == NULL)
 255                /* no inode means this hasn't been made visible yet */
 256                return;
 257
 258        mutex_lock(&dir->d_inode->i_mutex);
 259        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 260                if (!sd->s_element)
 261                        continue;
 262                if (!strcmp(configfs_get_name(sd), name)) {
 263                        spin_lock(&configfs_dirent_lock);
 264                        list_del_init(&sd->s_sibling);
 265                        spin_unlock(&configfs_dirent_lock);
 266                        configfs_drop_dentry(sd, dir);
 267                        configfs_put(sd);
 268                        break;
 269                }
 270        }
 271        mutex_unlock(&dir->d_inode->i_mutex);
 272}
 273