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 = kmalloc(sizeof(struct iattr), GFP_KERNEL);
  80                 if (!sd_iattr)
  81                         return -ENOMEM;
  82                 /* assign default attributes */
  83                 memset(sd_iattr, 0, sizeof(struct iattr));
  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_blksize = PAGE_CACHE_SIZE;
 140                 inode->i_blocks = 0;
 141                 inode->i_mapping->a_ops = &configfs_aops;
 142                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 143                 inode->i_op = &configfs_inode_operations;
 144
 145                 if (sd->s_iattr) {
 146                         /* sysfs_dirent has non-default attributes
 147                          * get them for the new inode from persistent copy
 148                          * in sysfs_dirent
 149                          */
 150                         set_inode_attr(inode, sd->s_iattr);
 151                 } else
 152                         set_default_inode_attr(inode, mode);
 153         }
 154         return inode;
 155 }
 156
 157 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 158 {
 159         int error = 0;
 160         struct inode * inode = NULL;
 161         if (dentry) {
 162                 if (!dentry->d_inode) {
 163                         struct configfs_dirent *sd = dentry->d_fsdata;
 164                         if ((inode = configfs_new_inode(mode, sd))) {
 165                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 166                                         struct inode *p_inode = dentry->d_parent->d_inode;
 167                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 168                                 }
 169                                 goto Proceed;
 170                         }
 171                         else
 172                                 error = -ENOMEM;
 173                 } else
 174                         error = -EEXIST;
 175         } else
 176                 error = -ENOENT;
 177         goto Done;
 178
 179  Proceed:
 180         if (init)
 181                 error = init(inode);
 182         if (!error) {
 183                 d_instantiate(dentry, inode);
 184                 if (S_ISDIR(mode) || S_ISLNK(mode))
 185                         dget(dentry);  /* pin link and directory dentries in core */
 186         } else
 187                 iput(inode);
 188  Done:
 189         return error;
 190 }
 191
 192 /*
 193  * Get the name for corresponding element represented by the given configfs_dirent
 194  */
 195 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 196 {
 197         struct configfs_attribute *attr;
 198
 199         BUG_ON(!sd || !sd->s_element);
 200
 201         /* These always have a dentry, so use that */
 202         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 203                 return sd->s_dentry->d_name.name;
 204
 205         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 206                 attr = sd->s_element;
 207                 return attr->ca_name;
 208         }
 209         return NULL;
 210 }
 211
 212
 213 /*
 214  * Unhashes the dentry corresponding to given configfs_dirent
 215  * Called with parent inode's i_mutex held.
 216  */
 217 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 218 {
 219         struct dentry * dentry = sd->s_dentry;
 220
 221         if (dentry) {
 222                 spin_lock(&dcache_lock);
 223                 spin_lock(&dentry->d_lock);
 224                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 225                         dget_locked(dentry);
 226                         __d_drop(dentry);
 227                         spin_unlock(&dentry->d_lock);
 228                         spin_unlock(&dcache_lock);
 229                         simple_unlink(parent->d_inode, dentry);
 230                 } else {
 231                         spin_unlock(&dentry->d_lock);
 232                         spin_unlock(&dcache_lock);
 233                 }
 234         }
 235 }
 236
 237 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 238 {
 239         struct configfs_dirent * sd;
 240         struct configfs_dirent * parent_sd = dir->d_fsdata;
 241
 242         if (dir->d_inode == NULL)
 243                 /* no inode means this hasn't been made visible yet */
 244                 return;
 245
 246         mutex_lock(&dir->d_inode->i_mutex);
 247         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 248                 if (!sd->s_element)
 249                         continue;
 250                 if (!strcmp(configfs_get_name(sd), name)) {
 251                         list_del_init(&sd->s_sibling);
 252                         configfs_drop_dentry(sd, dir);
 253                         configfs_put(sd);
 254                         break;
 255                 }
 256         }
 257         mutex_unlock(&dir->d_inode->i_mutex);
 258 }
 259
 260