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
  36 #include <linux/configfs.h>
  37 #include "configfs_internal.h"
  38
  39 extern struct super_block * configfs_sb;
  40
  41 static const struct address_space_operations configfs_aops = {
  42         .readpage       = simple_readpage,
  43         .prepare_write  = simple_prepare_write,
  44         .commit_write   = simple_commit_write
  45 };
  46
  47 static struct backing_dev_info configfs_backing_dev_info = {
  48         .ra_pages       = 0,    /* No readahead */
  49         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  50 };
  51
  52 static struct inode_operations configfs_inode_operations ={
  53         .setattr        = configfs_setattr,
  54 };
  55
  56 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  57 {
  58         struct inode * inode = dentry->d_inode;
  59         struct configfs_dirent * sd = dentry->d_fsdata;
  60         struct iattr * sd_iattr;
  61         unsigned int ia_valid = iattr->ia_valid;
  62         int error;
  63
  64         if (!sd)
  65                 return -EINVAL;
  66
  67         sd_iattr = sd->s_iattr;
  68
  69         error = inode_change_ok(inode, iattr);
  70         if (error)
  71                 return error;
  72
  73         error = inode_setattr(inode, iattr);
  74         if (error)
  75                 return error;
  76
  77         if (!sd_iattr) {
  78                 /* setting attributes for the first time, allocate now */
  79                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  80                 if (!sd_iattr)
  81                         return -ENOMEM;
  82                 /* assign default attributes */
  83                 sd_iattr->ia_mode = sd->s_mode;
  84                 sd_iattr->ia_uid = 0;
  85                 sd_iattr->ia_gid = 0;
  86                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  87                 sd->s_iattr = sd_iattr;
  88         }
  89
  90         /* attributes were changed atleast once in past */
  91
  92         if (ia_valid & ATTR_UID)
  93                 sd_iattr->ia_uid = iattr->ia_uid;
  94         if (ia_valid & ATTR_GID)
  95                 sd_iattr->ia_gid = iattr->ia_gid;
  96         if (ia_valid & ATTR_ATIME)
  97                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  98                                                 inode->i_sb->s_time_gran);
  99         if (ia_valid & ATTR_MTIME)
 100                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 101                                                 inode->i_sb->s_time_gran);
 102         if (ia_valid & ATTR_CTIME)
 103                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 104                                                 inode->i_sb->s_time_gran);
 105         if (ia_valid & ATTR_MODE) {
 106                 umode_t mode = iattr->ia_mode;
 107
 108                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 109                         mode &= ~S_ISGID;
 110                 sd_iattr->ia_mode = sd->s_mode = mode;
 111         }
 112
 113         return error;
 114 }
 115
 116 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 117 {
 118         inode->i_mode = mode;
 119         inode->i_uid = 0;
 120         inode->i_gid = 0;
 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_blocks = 0;
 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 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 156 {
 157         int error = 0;
 158         struct inode * inode = NULL;
 159         if (dentry) {
 160                 if (!dentry->d_inode) {
 161                         struct configfs_dirent *sd = dentry->d_fsdata;
 162                         if ((inode = configfs_new_inode(mode, sd))) {
 163                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 164                                         struct inode *p_inode = dentry->d_parent->d_inode;
 165                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 166                                 }
 167                                 goto Proceed;
 168                         }
 169                         else
 170                                 error = -ENOMEM;
 171                 } else
 172                         error = -EEXIST;
 173         } else
 174                 error = -ENOENT;
 175         goto Done;
 176
 177  Proceed:
 178         if (init)
 179                 error = init(inode);
 180         if (!error) {
 181                 d_instantiate(dentry, inode);
 182                 if (S_ISDIR(mode) || S_ISLNK(mode))
 183                         dget(dentry);  /* pin link and directory dentries in core */
 184         } else
 185                 iput(inode);
 186  Done:
 187         return error;
 188 }
 189
 190 /*
 191  * Get the name for corresponding element represented by the given configfs_dirent
 192  */
 193 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 194 {
 195         struct configfs_attribute *attr;
 196
 197         BUG_ON(!sd || !sd->s_element);
 198
 199         /* These always have a dentry, so use that */
 200         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 201                 return sd->s_dentry->d_name.name;
 202
 203         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 204                 attr = sd->s_element;
 205                 return attr->ca_name;
 206         }
 207         return NULL;
 208 }
 209
 210
 211 /*
 212  * Unhashes the dentry corresponding to given configfs_dirent
 213  * Called with parent inode's i_mutex held.
 214  */
 215 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 216 {
 217         struct dentry * dentry = sd->s_dentry;
 218
 219         if (dentry) {
 220                 spin_lock(&dcache_lock);
 221                 spin_lock(&dentry->d_lock);
 222                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 223                         dget_locked(dentry);
 224                         __d_drop(dentry);
 225                         spin_unlock(&dentry->d_lock);
 226                         spin_unlock(&dcache_lock);
 227                         simple_unlink(parent->d_inode, dentry);
 228                 } else {
 229                         spin_unlock(&dentry->d_lock);
 230                         spin_unlock(&dcache_lock);
 231                 }
 232         }
 233 }
 234
 235 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 236 {
 237         struct configfs_dirent * sd;
 238         struct configfs_dirent * parent_sd = dir->d_fsdata;
 239
 240         if (dir->d_inode == NULL)
 241                 /* no inode means this hasn't been made visible yet */
 242                 return;
 243
 244         mutex_lock(&dir->d_inode->i_mutex);
 245         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 246                 if (!sd->s_element)
 247                         continue;
 248                 if (!strcmp(configfs_get_name(sd), name)) {
 249                         list_del_init(&sd->s_sibling);
 250                         configfs_drop_dentry(sd, dir);
 251                         configfs_put(sd);
 252                         break;
 253                 }
 254         }
 255         mutex_unlock(&dir->d_inode->i_mutex);
 256 }
 257
 258