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
  37 #include <linux/configfs.h>
  38 #include "configfs_internal.h"
  39
  40 extern struct super_block * configfs_sb;
  41
  42 static const struct address_space_operations configfs_aops = {
  43         .readpage       = simple_readpage,
  44         .write_begin    = simple_write_begin,
  45         .write_end      = simple_write_end,
  46 };
  47
  48 static struct backing_dev_info configfs_backing_dev_info = {
  49         .ra_pages       = 0,    /* No readahead */
  50         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  51 };
  52
  53 static const struct inode_operations configfs_inode_operations ={
  54         .setattr        = configfs_setattr,
  55 };
  56
  57 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  58 {
  59         struct inode * inode = dentry->d_inode;
  60         struct configfs_dirent * sd = dentry->d_fsdata;
  61         struct iattr * sd_iattr;
  62         unsigned int ia_valid = iattr->ia_valid;
  63         int error;
  64
  65         if (!sd)
  66                 return -EINVAL;
  67
  68         sd_iattr = sd->s_iattr;
  69
  70         error = inode_change_ok(inode, iattr);
  71         if (error)
  72                 return error;
  73
  74         error = inode_setattr(inode, iattr);
  75         if (error)
  76                 return error;
  77
  78         if (!sd_iattr) {
  79                 /* setting attributes for the first time, allocate now */
  80                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  81                 if (!sd_iattr)
  82                         return -ENOMEM;
  83                 /* assign default attributes */
  84                 sd_iattr->ia_mode = sd->s_mode;
  85                 sd_iattr->ia_uid = 0;
  86                 sd_iattr->ia_gid = 0;
  87                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  88                 sd->s_iattr = sd_iattr;
  89         }
  90
  91         /* attributes were changed atleast once in past */
  92
  93         if (ia_valid & ATTR_UID)
  94                 sd_iattr->ia_uid = iattr->ia_uid;
  95         if (ia_valid & ATTR_GID)
  96                 sd_iattr->ia_gid = iattr->ia_gid;
  97         if (ia_valid & ATTR_ATIME)
  98                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  99                                                 inode->i_sb->s_time_gran);
 100         if (ia_valid & ATTR_MTIME)
 101                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 102                                                 inode->i_sb->s_time_gran);
 103         if (ia_valid & ATTR_CTIME)
 104                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 105                                                 inode->i_sb->s_time_gran);
 106         if (ia_valid & ATTR_MODE) {
 107                 umode_t mode = iattr->ia_mode;
 108
 109                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 110                         mode &= ~S_ISGID;
 111                 sd_iattr->ia_mode = sd->s_mode = mode;
 112         }
 113
 114         return error;
 115 }
 116
 117 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
 118 {
 119         inode->i_mode = mode;
 120         inode->i_uid = 0;
 121         inode->i_gid = 0;
 122         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 123 }
 124
 125 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 126 {
 127         inode->i_mode = iattr->ia_mode;
 128         inode->i_uid = iattr->ia_uid;
 129         inode->i_gid = iattr->ia_gid;
 130         inode->i_atime = iattr->ia_atime;
 131         inode->i_mtime = iattr->ia_mtime;
 132         inode->i_ctime = iattr->ia_ctime;
 133 }
 134
 135 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd)
 136 {
 137         struct inode * inode = new_inode(configfs_sb);
 138         if (inode) {
 139                 inode->i_blocks = 0;
 140                 inode->i_mapping->a_ops = &configfs_aops;
 141                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 142                 inode->i_op = &configfs_inode_operations;
 143
 144                 if (sd->s_iattr) {
 145                         /* sysfs_dirent has non-default attributes
 146                          * get them for the new inode from persistent copy
 147                          * in sysfs_dirent
 148                          */
 149                         set_inode_attr(inode, sd->s_iattr);
 150                 } else
 151                         set_default_inode_attr(inode, mode);
 152         }
 153         return inode;
 154 }
 155
 156 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 157 {
 158         int error = 0;
 159         struct inode * inode = NULL;
 160         if (dentry) {
 161                 if (!dentry->d_inode) {
 162                         struct configfs_dirent *sd = dentry->d_fsdata;
 163                         if ((inode = configfs_new_inode(mode, sd))) {
 164                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 165                                         struct inode *p_inode = dentry->d_parent->d_inode;
 166                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 167                                 }
 168                                 goto Proceed;
 169                         }
 170                         else
 171                                 error = -ENOMEM;
 172                 } else
 173                         error = -EEXIST;
 174         } else
 175                 error = -ENOENT;
 176         goto Done;
 177
 178  Proceed:
 179         if (init)
 180                 error = init(inode);
 181         if (!error) {
 182                 d_instantiate(dentry, inode);
 183                 if (S_ISDIR(mode) || S_ISLNK(mode))
 184                         dget(dentry);  /* pin link and directory dentries in core */
 185         } else
 186                 iput(inode);
 187  Done:
 188         return error;
 189 }
 190
 191 /*
 192  * Get the name for corresponding element represented by the given configfs_dirent
 193  */
 194 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 195 {
 196         struct configfs_attribute *attr;
 197
 198         BUG_ON(!sd || !sd->s_element);
 199
 200         /* These always have a dentry, so use that */
 201         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 202                 return sd->s_dentry->d_name.name;
 203
 204         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 205                 attr = sd->s_element;
 206                 return attr->ca_name;
 207         }
 208         return NULL;
 209 }
 210
 211
 212 /*
 213  * Unhashes the dentry corresponding to given configfs_dirent
 214  * Called with parent inode's i_mutex held.
 215  */
 216 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 217 {
 218         struct dentry * dentry = sd->s_dentry;
 219
 220         if (dentry) {
 221                 spin_lock(&dcache_lock);
 222                 spin_lock(&dentry->d_lock);
 223                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 224                         dget_locked(dentry);
 225                         __d_drop(dentry);
 226                         spin_unlock(&dentry->d_lock);
 227                         spin_unlock(&dcache_lock);
 228                         simple_unlink(parent->d_inode, dentry);
 229                 } else {
 230                         spin_unlock(&dentry->d_lock);
 231                         spin_unlock(&dcache_lock);
 232                 }
 233         }
 234 }
 235
 236 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 237 {
 238         struct configfs_dirent * sd;
 239         struct configfs_dirent * parent_sd = dir->d_fsdata;
 240
 241         if (dir->d_inode == NULL)
 242                 /* no inode means this hasn't been made visible yet */
 243                 return;
 244
 245         mutex_lock(&dir->d_inode->i_mutex);
 246         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 247                 if (!sd->s_element)
 248                         continue;
 249                 if (!strcmp(configfs_get_name(sd), name)) {
 250                         list_del_init(&sd->s_sibling);
 251                         configfs_drop_dentry(sd, dir);
 252                         configfs_put(sd);
 253                         break;
 254                 }
 255         }
 256         mutex_unlock(&dir->d_inode->i_mutex);
 257 }
 258
 259 int __init configfs_inode_init(void)
 260 {
 261         return bdi_init(&configfs_backing_dev_info);
 262 }
 263
 264 void __exit configfs_inode_exit(void)
 265 {
 266         bdi_destroy(&configfs_backing_dev_info);
 267 }