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
  77         error = inode_change_ok(inode, iattr);
  78         if (error)
  79                 return error;
  80
  81         error = inode_setattr(inode, iattr);
  82         if (error)
  83                 return error;
  84
  85         if (!sd_iattr) {
  86                 /* setting attributes for the first time, allocate now */
  87                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  88                 if (!sd_iattr)
  89                         return -ENOMEM;
  90                 /* assign default attributes */
  91                 sd_iattr->ia_mode = sd->s_mode;
  92                 sd_iattr->ia_uid = 0;
  93                 sd_iattr->ia_gid = 0;
  94                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  95                 sd->s_iattr = sd_iattr;
  96         }
  97
  98         /* attributes were changed atleast once in past */
  99
 100         if (ia_valid & ATTR_UID)
 101                 sd_iattr->ia_uid = iattr->ia_uid;
 102         if (ia_valid & ATTR_GID)
 103                 sd_iattr->ia_gid = iattr->ia_gid;
 104         if (ia_valid & ATTR_ATIME)
 105                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 106                                                 inode->i_sb->s_time_gran);
 107         if (ia_valid & ATTR_MTIME)
 108                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 109                                                 inode->i_sb->s_time_gran);
 110         if (ia_valid & ATTR_CTIME)
 111                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 112                                                 inode->i_sb->s_time_gran);
 113         if (ia_valid & ATTR_MODE) {
 114                 umode_t mode = iattr->ia_mode;
 115
 116                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 117                         mode &= ~S_ISGID;
 118                 sd_iattr->ia_mode = sd->s_mode = mode;
 119         }
 120
 121         return error;
 122 }
 123
 124 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 125 {
 126         inode->i_mode = mode;
 127         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 128 }
 129
 130 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 131 {
 132         inode->i_mode = iattr->ia_mode;
 133         inode->i_uid = iattr->ia_uid;
 134         inode->i_gid = iattr->ia_gid;
 135         inode->i_atime = iattr->ia_atime;
 136         inode->i_mtime = iattr->ia_mtime;
 137         inode->i_ctime = iattr->ia_ctime;
 138 }
 139
 140 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
 141 {
 142         struct inode * inode = new_inode(configfs_sb);
 143         if (inode) {
 144                 inode->i_mapping->a_ops = &configfs_aops;
 145                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 146                 inode->i_op = &configfs_inode_operations;
 147
 148                 if (sd->s_iattr) {
 149                         /* sysfs_dirent has non-default attributes
 150                          * get them for the new inode from persistent copy
 151                          * in sysfs_dirent
 152                          */
 153                         set_inode_attr(inode, sd->s_iattr);
 154                 } else
 155                         set_default_inode_attr(inode, mode);
 156         }
 157         return inode;
 158 }
 159
 160 #ifdef CONFIG_LOCKDEP
 161
 162 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 163                                           struct inode *inode)
 164 {
 165         int depth = sd->s_depth;
 166
 167         if (depth > 0) {
 168                 if (depth <= ARRAY_SIZE(default_group_class)) {
 169                         lockdep_set_class(&inode->i_mutex,
 170                                           &default_group_class[depth - 1]);
 171                 } else {
 172                         /*
 173                          * In practice the maximum level of locking depth is
 174                          * already reached. Just inform about possible reasons.
 175                          */
 176                         printk(KERN_INFO "configfs: Too many levels of inodes"
 177                                " for the locking correctness validator.\n");
 178                         printk(KERN_INFO "Spurious warnings may appear.\n");
 179                 }
 180         }
 181 }
 182
 183 #else /* CONFIG_LOCKDEP */
 184
 185 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 186                                           struct inode *inode)
 187 {
 188 }
 189
 190 #endif /* CONFIG_LOCKDEP */
 191
 192 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 193 {
 194         int error = 0;
 195         struct inode * inode = NULL;
 196         if (dentry) {
 197                 if (!dentry->d_inode) {
 198                         struct configfs_dirent *sd = dentry->d_fsdata;
 199                         if ((inode = configfs_new_inode(mode, sd))) {
 200                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 201                                         struct inode *p_inode = dentry->d_parent->d_inode;
 202                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 203                                 }
 204                                 configfs_set_inode_lock_class(sd, inode);
 205                                 goto Proceed;
 206                         }
 207                         else
 208                                 error = -ENOMEM;
 209                 } else
 210                         error = -EEXIST;
 211         } else
 212                 error = -ENOENT;
 213         goto Done;
 214
 215  Proceed:
 216         if (init)
 217                 error = init(inode);
 218         if (!error) {
 219                 d_instantiate(dentry, inode);
 220                 if (S_ISDIR(mode) || S_ISLNK(mode))
 221                         dget(dentry);  /* pin link and directory dentries in core */
 222         } else
 223                 iput(inode);
 224  Done:
 225         return error;
 226 }
 227
 228 /*
 229  * Get the name for corresponding element represented by the given configfs_dirent
 230  */
 231 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 232 {
 233         struct configfs_attribute *attr;
 234
 235         BUG_ON(!sd || !sd->s_element);
 236
 237         /* These always have a dentry, so use that */
 238         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 239                 return sd->s_dentry->d_name.name;
 240
 241         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 242                 attr = sd->s_element;
 243                 return attr->ca_name;
 244         }
 245         return NULL;
 246 }
 247
 248
 249 /*
 250  * Unhashes the dentry corresponding to given configfs_dirent
 251  * Called with parent inode's i_mutex held.
 252  */
 253 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 254 {
 255         struct dentry * dentry = sd->s_dentry;
 256
 257         if (dentry) {
 258                 spin_lock(&dcache_lock);
 259                 spin_lock(&dentry->d_lock);
 260                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 261                         dget_locked(dentry);
 262                         __d_drop(dentry);
 263                         spin_unlock(&dentry->d_lock);
 264                         spin_unlock(&dcache_lock);
 265                         simple_unlink(parent->d_inode, dentry);
 266                 } else {
 267                         spin_unlock(&dentry->d_lock);
 268                         spin_unlock(&dcache_lock);
 269                 }
 270         }
 271 }
 272
 273 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 274 {
 275         struct configfs_dirent * sd;
 276         struct configfs_dirent * parent_sd = dir->d_fsdata;
 277
 278         if (dir->d_inode == NULL)
 279                 /* no inode means this hasn't been made visible yet */
 280                 return;
 281
 282         mutex_lock(&dir->d_inode->i_mutex);
 283         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 284                 if (!sd->s_element)
 285                         continue;
 286                 if (!strcmp(configfs_get_name(sd), name)) {
 287                         spin_lock(&configfs_dirent_lock);
 288                         list_del_init(&sd->s_sibling);
 289                         spin_unlock(&configfs_dirent_lock);
 290                         configfs_drop_dentry(sd, dir);
 291                         configfs_put(sd);
 292                         break;
 293                 }
 294         }
 295         mutex_unlock(&dir->d_inode->i_mutex);
 296 }
 297
 298 int __init configfs_inode_init(void)
 299 {
 300         return bdi_init(&configfs_backing_dev_info);
 301 }
 302
 303 void __exit configfs_inode_exit(void)
 304 {
 305         bdi_destroy(&configfs_backing_dev_info);
 306 }