linux/fs/configfs/inode.c
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   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 struct backing_dev_info configfs_backing_dev_info = {
  54        .name           = "configfs",
  55        .ra_pages       = 0,    /* No readahead */
  56        .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
  57};
  58
  59static const struct inode_operations configfs_inode_operations ={
  60        .setattr        = configfs_setattr,
  61};
  62
  63int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  64{
  65        struct inode * inode = dentry->d_inode;
  66        struct configfs_dirent * sd = dentry->d_fsdata;
  67        struct iattr * sd_iattr;
  68        unsigned int ia_valid = iattr->ia_valid;
  69        int error;
  70
  71        if (!sd)
  72                return -EINVAL;
  73
  74        sd_iattr = sd->s_iattr;
  75        if (!sd_iattr) {
  76                /* setting attributes for the first time, allocate now */
  77                sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  78                if (!sd_iattr)
  79                        return -ENOMEM;
  80                /* assign default attributes */
  81                sd_iattr->ia_mode = sd->s_mode;
  82                sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  83                sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  84                sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  85                sd->s_iattr = sd_iattr;
  86        }
  87        /* attributes were changed atleast once in past */
  88
  89        error = simple_setattr(dentry, iattr);
  90        if (error)
  91                return error;
  92
  93        if (ia_valid & ATTR_UID)
  94                sd_iattr->ia_uid = iattr->ia_uid;
  95        if (ia_valid & ATTR_GID)
  96                sd_iattr->ia_gid = iattr->ia_gid;
  97        if (ia_valid & ATTR_ATIME)
  98                sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  99                                                inode->i_sb->s_time_gran);
 100        if (ia_valid & ATTR_MTIME)
 101                sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 102                                                inode->i_sb->s_time_gran);
 103        if (ia_valid & ATTR_CTIME)
 104                sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 105                                                inode->i_sb->s_time_gran);
 106        if (ia_valid & ATTR_MODE) {
 107                umode_t mode = iattr->ia_mode;
 108
 109                if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 110                        mode &= ~S_ISGID;
 111                sd_iattr->ia_mode = sd->s_mode = mode;
 112        }
 113
 114        return error;
 115}
 116
 117static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
 118{
 119        inode->i_mode = mode;
 120        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 121}
 122
 123static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 124{
 125        inode->i_mode = iattr->ia_mode;
 126        inode->i_uid = iattr->ia_uid;
 127        inode->i_gid = iattr->ia_gid;
 128        inode->i_atime = iattr->ia_atime;
 129        inode->i_mtime = iattr->ia_mtime;
 130        inode->i_ctime = iattr->ia_ctime;
 131}
 132
 133struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 134                                 struct super_block *s)
 135{
 136        struct inode * inode = new_inode(s);
 137        if (inode) {
 138                inode->i_ino = get_next_ino();
 139                inode->i_mapping->a_ops = &configfs_aops;
 140                inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 141                inode->i_op = &configfs_inode_operations;
 142
 143                if (sd->s_iattr) {
 144                        /* sysfs_dirent has non-default attributes
 145                         * get them for the new inode from persistent copy
 146                         * in sysfs_dirent
 147                         */
 148                        set_inode_attr(inode, sd->s_iattr);
 149                } else
 150                        set_default_inode_attr(inode, mode);
 151        }
 152        return inode;
 153}
 154
 155#ifdef CONFIG_LOCKDEP
 156
 157static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 158                                          struct inode *inode)
 159{
 160        int depth = sd->s_depth;
 161
 162        if (depth > 0) {
 163                if (depth <= ARRAY_SIZE(default_group_class)) {
 164                        lockdep_set_class(&inode->i_mutex,
 165                                          &default_group_class[depth - 1]);
 166                } else {
 167                        /*
 168                         * In practice the maximum level of locking depth is
 169                         * already reached. Just inform about possible reasons.
 170                         */
 171                        printk(KERN_INFO "configfs: Too many levels of inodes"
 172                               " for the locking correctness validator.\n");
 173                        printk(KERN_INFO "Spurious warnings may appear.\n");
 174                }
 175        }
 176}
 177
 178#else /* CONFIG_LOCKDEP */
 179
 180static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 181                                          struct inode *inode)
 182{
 183}
 184
 185#endif /* CONFIG_LOCKDEP */
 186
 187int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
 188{
 189        int error = 0;
 190        struct inode *inode = NULL;
 191        struct configfs_dirent *sd;
 192        struct inode *p_inode;
 193
 194        if (!dentry)
 195                return -ENOENT;
 196
 197        if (dentry->d_inode)
 198                return -EEXIST;
 199
 200        sd = dentry->d_fsdata;
 201        inode = configfs_new_inode(mode, sd, dentry->d_sb);
 202        if (!inode)
 203                return -ENOMEM;
 204
 205        p_inode = dentry->d_parent->d_inode;
 206        p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 207        configfs_set_inode_lock_class(sd, inode);
 208
 209        if (init) {
 210                error = init(inode);
 211                if (error) {
 212                        iput(inode);
 213                        return error;
 214                }
 215        }
 216        d_instantiate(dentry, inode);
 217        if (S_ISDIR(mode) || S_ISLNK(mode))
 218                dget(dentry);  /* pin link and directory dentries in core */
 219        return error;
 220}
 221
 222/*
 223 * Get the name for corresponding element represented by the given configfs_dirent
 224 */
 225const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 226{
 227        struct configfs_attribute *attr;
 228
 229        BUG_ON(!sd || !sd->s_element);
 230
 231        /* These always have a dentry, so use that */
 232        if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 233                return sd->s_dentry->d_name.name;
 234
 235        if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 236                attr = sd->s_element;
 237                return attr->ca_name;
 238        }
 239        return NULL;
 240}
 241
 242
 243/*
 244 * Unhashes the dentry corresponding to given configfs_dirent
 245 * Called with parent inode's i_mutex held.
 246 */
 247void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 248{
 249        struct dentry * dentry = sd->s_dentry;
 250
 251        if (dentry) {
 252                spin_lock(&dentry->d_lock);
 253                if (!(d_unhashed(dentry) && dentry->d_inode)) {
 254                        dget_dlock(dentry);
 255                        __d_drop(dentry);
 256                        spin_unlock(&dentry->d_lock);
 257                        simple_unlink(parent->d_inode, dentry);
 258                } else
 259                        spin_unlock(&dentry->d_lock);
 260        }
 261}
 262
 263void configfs_hash_and_remove(struct dentry * dir, const char * name)
 264{
 265        struct configfs_dirent * sd;
 266        struct configfs_dirent * parent_sd = dir->d_fsdata;
 267
 268        if (dir->d_inode == NULL)
 269                /* no inode means this hasn't been made visible yet */
 270                return;
 271
 272        mutex_lock(&dir->d_inode->i_mutex);
 273        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 274                if (!sd->s_element)
 275                        continue;
 276                if (!strcmp(configfs_get_name(sd), name)) {
 277                        spin_lock(&configfs_dirent_lock);
 278                        list_del_init(&sd->s_sibling);
 279                        spin_unlock(&configfs_dirent_lock);
 280                        configfs_drop_dentry(sd, dir);
 281                        configfs_put(sd);
 282                        break;
 283                }
 284        }
 285        mutex_unlock(&dir->d_inode->i_mutex);
 286}
 287
 288int __init configfs_inode_init(void)
 289{
 290        return bdi_init(&configfs_backing_dev_info);
 291}
 292
 293void configfs_inode_exit(void)
 294{
 295        bdi_destroy(&configfs_backing_dev_info);
 296}
 297
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