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         .ra_pages       = 0,    /* No readahead */
  55         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
  56 };
  57
  58 static const struct inode_operations configfs_inode_operations ={
  59         .setattr        = configfs_setattr,
  60 };
  61
  62 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  63 {
  64         struct inode * inode = dentry->d_inode;
  65         struct configfs_dirent * sd = dentry->d_fsdata;
  66         struct iattr * sd_iattr;
  67         unsigned int ia_valid = iattr->ia_valid;
  68         int error;
  69
  70         if (!sd)
  71                 return -EINVAL;
  72
  73         sd_iattr = sd->s_iattr;
  74
  75         error = inode_change_ok(inode, iattr);
  76         if (error)
  77                 return error;
  78
  79         error = inode_setattr(inode, iattr);
  80         if (error)
  81                 return error;
  82
  83         if (!sd_iattr) {
  84                 /* setting attributes for the first time, allocate now */
  85                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  86                 if (!sd_iattr)
  87                         return -ENOMEM;
  88                 /* assign default attributes */
  89                 sd_iattr->ia_mode = sd->s_mode;
  90                 sd_iattr->ia_uid = 0;
  91                 sd_iattr->ia_gid = 0;
  92                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  93                 sd->s_iattr = sd_iattr;
  94         }
  95
  96         /* attributes were changed atleast once in past */
  97
  98         if (ia_valid & ATTR_UID)
  99                 sd_iattr->ia_uid = iattr->ia_uid;
 100         if (ia_valid & ATTR_GID)
 101                 sd_iattr->ia_gid = iattr->ia_gid;
 102         if (ia_valid & ATTR_ATIME)
 103                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 104                                                 inode->i_sb->s_time_gran);
 105         if (ia_valid & ATTR_MTIME)
 106                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 107                                                 inode->i_sb->s_time_gran);
 108         if (ia_valid & ATTR_CTIME)
 109                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 110                                                 inode->i_sb->s_time_gran);
 111         if (ia_valid & ATTR_MODE) {
 112                 umode_t mode = iattr->ia_mode;
 113
 114                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 115                         mode &= ~S_ISGID;
 116                 sd_iattr->ia_mode = sd->s_mode = mode;
 117         }
 118
 119         return error;
 120 }
 121
 122 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 123 {
 124         inode->i_mode = mode;
 125         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 126 }
 127
 128 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 129 {
 130         inode->i_mode = iattr->ia_mode;
 131         inode->i_uid = iattr->ia_uid;
 132         inode->i_gid = iattr->ia_gid;
 133         inode->i_atime = iattr->ia_atime;
 134         inode->i_mtime = iattr->ia_mtime;
 135         inode->i_ctime = iattr->ia_ctime;
 136 }
 137
 138 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
 139 {
 140         struct inode * inode = new_inode(configfs_sb);
 141         if (inode) {
 142                 inode->i_mapping->a_ops = &configfs_aops;
 143                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 144                 inode->i_op = &configfs_inode_operations;
 145
 146                 if (sd->s_iattr) {
 147                         /* sysfs_dirent has non-default attributes
 148                          * get them for the new inode from persistent copy
 149                          * in sysfs_dirent
 150                          */
 151                         set_inode_attr(inode, sd->s_iattr);
 152                 } else
 153                         set_default_inode_attr(inode, mode);
 154         }
 155         return inode;
 156 }
 157
 158 #ifdef CONFIG_LOCKDEP
 159
 160 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 161                                           struct inode *inode)
 162 {
 163         int depth = sd->s_depth;
 164
 165         if (depth > 0) {
 166                 if (depth <= ARRAY_SIZE(default_group_class)) {
 167                         lockdep_set_class(&inode->i_mutex,
 168                                           &default_group_class[depth - 1]);
 169                 } else {
 170                         /*
 171                          * In practice the maximum level of locking depth is
 172                          * already reached. Just inform about possible reasons.
 173                          */
 174                         printk(KERN_INFO "configfs: Too many levels of inodes"
 175                                " for the locking correctness validator.\n");
 176                         printk(KERN_INFO "Spurious warnings may appear.\n");
 177                 }
 178         }
 179 }
 180
 181 #else /* CONFIG_LOCKDEP */
 182
 183 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 184                                           struct inode *inode)
 185 {
 186 }
 187
 188 #endif /* CONFIG_LOCKDEP */
 189
 190 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 191 {
 192         int error = 0;
 193         struct inode * inode = NULL;
 194         if (dentry) {
 195                 if (!dentry->d_inode) {
 196                         struct configfs_dirent *sd = dentry->d_fsdata;
 197                         if ((inode = configfs_new_inode(mode, sd))) {
 198                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 199                                         struct inode *p_inode = dentry->d_parent->d_inode;
 200                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 201                                 }
 202                                 configfs_set_inode_lock_class(sd, inode);
 203                                 goto Proceed;
 204                         }
 205                         else
 206                                 error = -ENOMEM;
 207                 } else
 208                         error = -EEXIST;
 209         } else
 210                 error = -ENOENT;
 211         goto Done;
 212
 213  Proceed:
 214         if (init)
 215                 error = init(inode);
 216         if (!error) {
 217                 d_instantiate(dentry, inode);
 218                 if (S_ISDIR(mode) || S_ISLNK(mode))
 219                         dget(dentry);  /* pin link and directory dentries in core */
 220         } else
 221                 iput(inode);
 222  Done:
 223         return error;
 224 }
 225
 226 /*
 227  * Get the name for corresponding element represented by the given configfs_dirent
 228  */
 229 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 230 {
 231         struct configfs_attribute *attr;
 232
 233         BUG_ON(!sd || !sd->s_element);
 234
 235         /* These always have a dentry, so use that */
 236         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 237                 return sd->s_dentry->d_name.name;
 238
 239         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 240                 attr = sd->s_element;
 241                 return attr->ca_name;
 242         }
 243         return NULL;
 244 }
 245
 246
 247 /*
 248  * Unhashes the dentry corresponding to given configfs_dirent
 249  * Called with parent inode's i_mutex held.
 250  */
 251 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 252 {
 253         struct dentry * dentry = sd->s_dentry;
 254
 255         if (dentry) {
 256                 spin_lock(&dcache_lock);
 257                 spin_lock(&dentry->d_lock);
 258                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 259                         dget_locked(dentry);
 260                         __d_drop(dentry);
 261                         spin_unlock(&dentry->d_lock);
 262                         spin_unlock(&dcache_lock);
 263                         simple_unlink(parent->d_inode, dentry);
 264                 } else {
 265                         spin_unlock(&dentry->d_lock);
 266                         spin_unlock(&dcache_lock);
 267                 }
 268         }
 269 }
 270
 271 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 272 {
 273         struct configfs_dirent * sd;
 274         struct configfs_dirent * parent_sd = dir->d_fsdata;
 275
 276         if (dir->d_inode == NULL)
 277                 /* no inode means this hasn't been made visible yet */
 278                 return;
 279
 280         mutex_lock(&dir->d_inode->i_mutex);
 281         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 282                 if (!sd->s_element)
 283                         continue;
 284                 if (!strcmp(configfs_get_name(sd), name)) {
 285                         spin_lock(&configfs_dirent_lock);
 286                         list_del_init(&sd->s_sibling);
 287                         spin_unlock(&configfs_dirent_lock);
 288                         configfs_drop_dentry(sd, dir);
 289                         configfs_put(sd);
 290                         break;
 291                 }
 292         }
 293         mutex_unlock(&dir->d_inode->i_mutex);
 294 }
 295
 296 int __init configfs_inode_init(void)
 297 {
 298         return bdi_init(&configfs_backing_dev_info);
 299 }
 300
 301 void __exit configfs_inode_exit(void)
 302 {
 303         bdi_destroy(&configfs_backing_dev_info);
 304 }