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_ino = get_next_ino();
 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 #ifdef CONFIG_LOCKDEP
 156
 157 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 158                                           struct inode *inode)
 159 {
 160         int depth = sd->s_depth;
 161
 162         if (depth > 0) {
 163                 if (depth <= ARRAY_SIZE(default_group_class)) {
 164                         lockdep_set_class(&inode->i_mutex,
 165                                           &default_group_class[depth - 1]);
 166                 } else {
 167                         /*
 168                          * In practice the maximum level of locking depth is
 169                          * already reached. Just inform about possible reasons.
 170                          */
 171                         printk(KERN_INFO "configfs: Too many levels of inodes"
 172                                " for the locking correctness validator.\n");
 173                         printk(KERN_INFO "Spurious warnings may appear.\n");
 174                 }
 175         }
 176 }
 177
 178 #else /* CONFIG_LOCKDEP */
 179
 180 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 181                                           struct inode *inode)
 182 {
 183 }
 184
 185 #endif /* CONFIG_LOCKDEP */
 186
 187 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
 188 {
 189         int error = 0;
 190         struct inode * inode = NULL;
 191         if (dentry) {
 192                 if (!dentry->d_inode) {
 193                         struct configfs_dirent *sd = dentry->d_fsdata;
 194                         if ((inode = configfs_new_inode(mode, sd))) {
 195                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 196                                         struct inode *p_inode = dentry->d_parent->d_inode;
 197                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 198                                 }
 199                                 configfs_set_inode_lock_class(sd, inode);
 200                                 goto Proceed;
 201                         }
 202                         else
 203                                 error = -ENOMEM;
 204                 } else
 205                         error = -EEXIST;
 206         } else
 207                 error = -ENOENT;
 208         goto Done;
 209
 210  Proceed:
 211         if (init)
 212                 error = init(inode);
 213         if (!error) {
 214                 d_instantiate(dentry, inode);
 215                 if (S_ISDIR(mode) || S_ISLNK(mode))
 216                         dget(dentry);  /* pin link and directory dentries in core */
 217         } else
 218                 iput(inode);
 219  Done:
 220         return error;
 221 }
 222
 223 /*
 224  * Get the name for corresponding element represented by the given configfs_dirent
 225  */
 226 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 227 {
 228         struct configfs_attribute *attr;
 229
 230         BUG_ON(!sd || !sd->s_element);
 231
 232         /* These always have a dentry, so use that */
 233         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 234                 return sd->s_dentry->d_name.name;
 235
 236         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 237                 attr = sd->s_element;
 238                 return attr->ca_name;
 239         }
 240         return NULL;
 241 }
 242
 243
 244 /*
 245  * Unhashes the dentry corresponding to given configfs_dirent
 246  * Called with parent inode's i_mutex held.
 247  */
 248 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 249 {
 250         struct dentry * dentry = sd->s_dentry;
 251
 252         if (dentry) {
 253                 spin_lock(&dcache_lock);
 254                 spin_lock(&dentry->d_lock);
 255                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 256                         dget_locked(dentry);
 257                         __d_drop(dentry);
 258                         spin_unlock(&dentry->d_lock);
 259                         spin_unlock(&dcache_lock);
 260                         simple_unlink(parent->d_inode, dentry);
 261                 } else {
 262                         spin_unlock(&dentry->d_lock);
 263                         spin_unlock(&dcache_lock);
 264                 }
 265         }
 266 }
 267
 268 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 269 {
 270         struct configfs_dirent * sd;
 271         struct configfs_dirent * parent_sd = dir->d_fsdata;
 272
 273         if (dir->d_inode == NULL)
 274                 /* no inode means this hasn't been made visible yet */
 275                 return;
 276
 277         mutex_lock(&dir->d_inode->i_mutex);
 278         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 279                 if (!sd->s_element)
 280                         continue;
 281                 if (!strcmp(configfs_get_name(sd), name)) {
 282                         spin_lock(&configfs_dirent_lock);
 283                         list_del_init(&sd->s_sibling);
 284                         spin_unlock(&configfs_dirent_lock);
 285                         configfs_drop_dentry(sd, dir);
 286                         configfs_put(sd);
 287                         break;
 288                 }
 289         }
 290         mutex_unlock(&dir->d_inode->i_mutex);
 291 }
 292
 293 int __init configfs_inode_init(void)
 294 {
 295         return bdi_init(&configfs_backing_dev_info);
 296 }
 297
 298 void __exit configfs_inode_exit(void)
 299 {
 300         bdi_destroy(&configfs_backing_dev_info);
 301 }