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.txt for more information.
  27  */
  28
  29 #undef DEBUG
  30
  31 #include <linux/pagemap.h>
  32 #include <linux/namei.h>
  33 #include <linux/backing-dev.h>
  34 #include <linux/capability.h>
  35 #include <linux/sched.h>
  36 #include <linux/lockdep.h>
  37
  38 #include <linux/configfs.h>
  39 #include "configfs_internal.h"
  40
  41 #ifdef CONFIG_LOCKDEP
  42 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  43 #endif
  44
  45 extern struct super_block * configfs_sb;
  46
  47 static 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
  53 static 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
  59 static const struct inode_operations configfs_inode_operations ={
  60         .setattr        = configfs_setattr,
  61 };
  62
  63 int 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
  76         error = inode_change_ok(inode, iattr);
  77         if (error)
  78                 return error;
  79
  80         error = inode_setattr(inode, iattr);
  81         if (error)
  82                 return error;
  83
  84         if (!sd_iattr) {
  85                 /* setting attributes for the first time, allocate now */
  86                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  87                 if (!sd_iattr)
  88                         return -ENOMEM;
  89                 /* assign default attributes */
  90                 sd_iattr->ia_mode = sd->s_mode;
  91                 sd_iattr->ia_uid = 0;
  92                 sd_iattr->ia_gid = 0;
  93                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  94                 sd->s_iattr = sd_iattr;
  95         }
  96
  97         /* attributes were changed atleast once in past */
  98
  99         if (ia_valid & ATTR_UID)
 100                 sd_iattr->ia_uid = iattr->ia_uid;
 101         if (ia_valid & ATTR_GID)
 102                 sd_iattr->ia_gid = iattr->ia_gid;
 103         if (ia_valid & ATTR_ATIME)
 104                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 105                                                 inode->i_sb->s_time_gran);
 106         if (ia_valid & ATTR_MTIME)
 107                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 108                                                 inode->i_sb->s_time_gran);
 109         if (ia_valid & ATTR_CTIME)
 110                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 111                                                 inode->i_sb->s_time_gran);
 112         if (ia_valid & ATTR_MODE) {
 113                 umode_t mode = iattr->ia_mode;
 114
 115                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 116                         mode &= ~S_ISGID;
 117                 sd_iattr->ia_mode = sd->s_mode = mode;
 118         }
 119
 120         return error;
 121 }
 122
 123 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 124 {
 125         inode->i_mode = mode;
 126         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 127 }
 128
 129 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 130 {
 131         inode->i_mode = iattr->ia_mode;
 132         inode->i_uid = iattr->ia_uid;
 133         inode->i_gid = iattr->ia_gid;
 134         inode->i_atime = iattr->ia_atime;
 135         inode->i_mtime = iattr->ia_mtime;
 136         inode->i_ctime = iattr->ia_ctime;
 137 }
 138
 139 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
 140 {
 141         struct inode * inode = new_inode(configfs_sb);
 142         if (inode) {
 143                 inode->i_mapping->a_ops = &configfs_aops;
 144                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 145                 inode->i_op = &configfs_inode_operations;
 146
 147                 if (sd->s_iattr) {
 148                         /* sysfs_dirent has non-default attributes
 149                          * get them for the new inode from persistent copy
 150                          * in sysfs_dirent
 151                          */
 152                         set_inode_attr(inode, sd->s_iattr);
 153                 } else
 154                         set_default_inode_attr(inode, mode);
 155         }
 156         return inode;
 157 }
 158
 159 #ifdef CONFIG_LOCKDEP
 160
 161 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 162                                           struct inode *inode)
 163 {
 164         int depth = sd->s_depth;
 165
 166         if (depth > 0) {
 167                 if (depth <= ARRAY_SIZE(default_group_class)) {
 168                         lockdep_set_class(&inode->i_mutex,
 169                                           &default_group_class[depth - 1]);
 170                 } else {
 171                         /*
 172                          * In practice the maximum level of locking depth is
 173                          * already reached. Just inform about possible reasons.
 174                          */
 175                         printk(KERN_INFO "configfs: Too many levels of inodes"
 176                                " for the locking correctness validator.\n");
 177                         printk(KERN_INFO "Spurious warnings may appear.\n");
 178                 }
 179         }
 180 }
 181
 182 #else /* CONFIG_LOCKDEP */
 183
 184 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 185                                           struct inode *inode)
 186 {
 187 }
 188
 189 #endif /* CONFIG_LOCKDEP */
 190
 191 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 192 {
 193         int error = 0;
 194         struct inode * inode = NULL;
 195         if (dentry) {
 196                 if (!dentry->d_inode) {
 197                         struct configfs_dirent *sd = dentry->d_fsdata;
 198                         if ((inode = configfs_new_inode(mode, sd))) {
 199                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 200                                         struct inode *p_inode = dentry->d_parent->d_inode;
 201                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 202                                 }
 203                                 configfs_set_inode_lock_class(sd, inode);
 204                                 goto Proceed;
 205                         }
 206                         else
 207                                 error = -ENOMEM;
 208                 } else
 209                         error = -EEXIST;
 210         } else
 211                 error = -ENOENT;
 212         goto Done;
 213
 214  Proceed:
 215         if (init)
 216                 error = init(inode);
 217         if (!error) {
 218                 d_instantiate(dentry, inode);
 219                 if (S_ISDIR(mode) || S_ISLNK(mode))
 220                         dget(dentry);  /* pin link and directory dentries in core */
 221         } else
 222                 iput(inode);
 223  Done:
 224         return error;
 225 }
 226
 227 /*
 228  * Get the name for corresponding element represented by the given configfs_dirent
 229  */
 230 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 231 {
 232         struct configfs_attribute *attr;
 233
 234         BUG_ON(!sd || !sd->s_element);
 235
 236         /* These always have a dentry, so use that */
 237         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 238                 return sd->s_dentry->d_name.name;
 239
 240         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 241                 attr = sd->s_element;
 242                 return attr->ca_name;
 243         }
 244         return NULL;
 245 }
 246
 247
 248 /*
 249  * Unhashes the dentry corresponding to given configfs_dirent
 250  * Called with parent inode's i_mutex held.
 251  */
 252 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 253 {
 254         struct dentry * dentry = sd->s_dentry;
 255
 256         if (dentry) {
 257                 spin_lock(&dcache_lock);
 258                 spin_lock(&dentry->d_lock);
 259                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 260                         dget_locked(dentry);
 261                         __d_drop(dentry);
 262                         spin_unlock(&dentry->d_lock);
 263                         spin_unlock(&dcache_lock);
 264                         simple_unlink(parent->d_inode, dentry);
 265                 } else {
 266                         spin_unlock(&dentry->d_lock);
 267                         spin_unlock(&dcache_lock);
 268                 }
 269         }
 270 }
 271
 272 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 273 {
 274         struct configfs_dirent * sd;
 275         struct configfs_dirent * parent_sd = dir->d_fsdata;
 276
 277         if (dir->d_inode == NULL)
 278                 /* no inode means this hasn't been made visible yet */
 279                 return;
 280
 281         mutex_lock(&dir->d_inode->i_mutex);
 282         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 283                 if (!sd->s_element)
 284                         continue;
 285                 if (!strcmp(configfs_get_name(sd), name)) {
 286                         spin_lock(&configfs_dirent_lock);
 287                         list_del_init(&sd->s_sibling);
 288                         spin_unlock(&configfs_dirent_lock);
 289                         configfs_drop_dentry(sd, dir);
 290                         configfs_put(sd);
 291                         break;
 292                 }
 293         }
 294         mutex_unlock(&dir->d_inode->i_mutex);
 295 }
 296
 297 int __init configfs_inode_init(void)
 298 {
 299         return bdi_init(&configfs_backing_dev_info);
 300 }
 301
 302 void __exit configfs_inode_exit(void)
 303 {
 304         bdi_destroy(&configfs_backing_dev_info);
 305 }