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 #include <linux/slab.h>
  38
  39 #include <linux/configfs.h>
  40 #include "configfs_internal.h"
  41
  42 #ifdef CONFIG_LOCKDEP
  43 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  44 #endif
  45
  46 extern struct super_block * configfs_sb;
  47
  48 static const struct address_space_operations configfs_aops = {
  49         .readpage       = simple_readpage,
  50         .write_begin    = simple_write_begin,
  51         .write_end      = simple_write_end,
  52 };
  53
  54 static struct backing_dev_info configfs_backing_dev_info = {
  55         .name           = "configfs",
  56         .ra_pages       = 0,    /* No readahead */
  57         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
  58 };
  59
  60 static const struct inode_operations configfs_inode_operations ={
  61         .setattr        = configfs_setattr,
  62 };
  63
  64 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  65 {
  66         struct inode * inode = dentry->d_inode;
  67         struct configfs_dirent * sd = dentry->d_fsdata;
  68         struct iattr * sd_iattr;
  69         unsigned int ia_valid = iattr->ia_valid;
  70         int error;
  71
  72         if (!sd)
  73                 return -EINVAL;
  74
  75         sd_iattr = sd->s_iattr;
  76         if (!sd_iattr) {
  77                 /* setting attributes for the first time, allocate now */
  78                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  79                 if (!sd_iattr)
  80                         return -ENOMEM;
  81                 /* assign default attributes */
  82                 sd_iattr->ia_mode = sd->s_mode;
  83                 sd_iattr->ia_uid = 0;
  84                 sd_iattr->ia_gid = 0;
  85                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  86                 sd->s_iattr = sd_iattr;
  87         }
  88         /* attributes were changed atleast once in past */
  89
  90         error = simple_setattr(dentry, iattr);
  91         if (error)
  92                 return error;
  93
  94         if (ia_valid & ATTR_UID)
  95                 sd_iattr->ia_uid = iattr->ia_uid;
  96         if (ia_valid & ATTR_GID)
  97                 sd_iattr->ia_gid = iattr->ia_gid;
  98         if (ia_valid & ATTR_ATIME)
  99                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 100                                                 inode->i_sb->s_time_gran);
 101         if (ia_valid & ATTR_MTIME)
 102                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 103                                                 inode->i_sb->s_time_gran);
 104         if (ia_valid & ATTR_CTIME)
 105                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 106                                                 inode->i_sb->s_time_gran);
 107         if (ia_valid & ATTR_MODE) {
 108                 umode_t mode = iattr->ia_mode;
 109
 110                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 111                         mode &= ~S_ISGID;
 112                 sd_iattr->ia_mode = sd->s_mode = mode;
 113         }
 114
 115         return error;
 116 }
 117
 118 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 119 {
 120         inode->i_mode = mode;
 121         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 122 }
 123
 124 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 125 {
 126         inode->i_mode = iattr->ia_mode;
 127         inode->i_uid = iattr->ia_uid;
 128         inode->i_gid = iattr->ia_gid;
 129         inode->i_atime = iattr->ia_atime;
 130         inode->i_mtime = iattr->ia_mtime;
 131         inode->i_ctime = iattr->ia_ctime;
 132 }
 133
 134 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
 135 {
 136         struct inode * inode = new_inode(configfs_sb);
 137         if (inode) {
 138                 inode->i_mapping->a_ops = &configfs_aops;
 139                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 140                 inode->i_op = &configfs_inode_operations;
 141
 142                 if (sd->s_iattr) {
 143                         /* sysfs_dirent has non-default attributes
 144                          * get them for the new inode from persistent copy
 145                          * in sysfs_dirent
 146                          */
 147                         set_inode_attr(inode, sd->s_iattr);
 148                 } else
 149                         set_default_inode_attr(inode, mode);
 150         }
 151         return inode;
 152 }
 153
 154 #ifdef CONFIG_LOCKDEP
 155
 156 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 157                                           struct inode *inode)
 158 {
 159         int depth = sd->s_depth;
 160
 161         if (depth > 0) {
 162                 if (depth <= ARRAY_SIZE(default_group_class)) {
 163                         lockdep_set_class(&inode->i_mutex,
 164                                           &default_group_class[depth - 1]);
 165                 } else {
 166                         /*
 167                          * In practice the maximum level of locking depth is
 168                          * already reached. Just inform about possible reasons.
 169                          */
 170                         printk(KERN_INFO "configfs: Too many levels of inodes"
 171                                " for the locking correctness validator.\n");
 172                         printk(KERN_INFO "Spurious warnings may appear.\n");
 173                 }
 174         }
 175 }
 176
 177 #else /* CONFIG_LOCKDEP */
 178
 179 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 180                                           struct inode *inode)
 181 {
 182 }
 183
 184 #endif /* CONFIG_LOCKDEP */
 185
 186 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 187 {
 188         int error = 0;
 189         struct inode * inode = NULL;
 190         if (dentry) {
 191                 if (!dentry->d_inode) {
 192                         struct configfs_dirent *sd = dentry->d_fsdata;
 193                         if ((inode = configfs_new_inode(mode, sd))) {
 194                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 195                                         struct inode *p_inode = dentry->d_parent->d_inode;
 196                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 197                                 }
 198                                 configfs_set_inode_lock_class(sd, inode);
 199                                 goto Proceed;
 200                         }
 201                         else
 202                                 error = -ENOMEM;
 203                 } else
 204                         error = -EEXIST;
 205         } else
 206                 error = -ENOENT;
 207         goto Done;
 208
 209  Proceed:
 210         if (init)
 211                 error = init(inode);
 212         if (!error) {
 213                 d_instantiate(dentry, inode);
 214                 if (S_ISDIR(mode) || S_ISLNK(mode))
 215                         dget(dentry);  /* pin link and directory dentries in core */
 216         } else
 217                 iput(inode);
 218  Done:
 219         return error;
 220 }
 221
 222 /*
 223  * Get the name for corresponding element represented by the given configfs_dirent
 224  */
 225 const 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  */
 247 void 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(&dcache_lock);
 253                 spin_lock(&dentry->d_lock);
 254                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 255                         dget_locked(dentry);
 256                         __d_drop(dentry);
 257                         spin_unlock(&dentry->d_lock);
 258                         spin_unlock(&dcache_lock);
 259                         simple_unlink(parent->d_inode, dentry);
 260                 } else {
 261                         spin_unlock(&dentry->d_lock);
 262                         spin_unlock(&dcache_lock);
 263                 }
 264         }
 265 }
 266
 267 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 268 {
 269         struct configfs_dirent * sd;
 270         struct configfs_dirent * parent_sd = dir->d_fsdata;
 271
 272         if (dir->d_inode == NULL)
 273                 /* no inode means this hasn't been made visible yet */
 274                 return;
 275
 276         mutex_lock(&dir->d_inode->i_mutex);
 277         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 278                 if (!sd->s_element)
 279                         continue;
 280                 if (!strcmp(configfs_get_name(sd), name)) {
 281                         spin_lock(&configfs_dirent_lock);
 282                         list_del_init(&sd->s_sibling);
 283                         spin_unlock(&configfs_dirent_lock);
 284                         configfs_drop_dentry(sd, dir);
 285                         configfs_put(sd);
 286                         break;
 287                 }
 288         }
 289         mutex_unlock(&dir->d_inode->i_mutex);
 290 }
 291
 292 int __init configfs_inode_init(void)
 293 {
 294         return bdi_init(&configfs_backing_dev_info);
 295 }
 296
 297 void __exit configfs_inode_exit(void)
 298 {
 299         bdi_destroy(&configfs_backing_dev_info);
 300 }