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/configfs.txt for more
  27  * information.
  28  */
  29
  30 #undef DEBUG
  31
  32 #include <linux/pagemap.h>
  33 #include <linux/namei.h>
  34 #include <linux/backing-dev.h>
  35 #include <linux/capability.h>
  36 #include <linux/sched.h>
  37 #include <linux/lockdep.h>
  38 #include <linux/slab.h>
  39
  40 #include <linux/configfs.h>
  41 #include "configfs_internal.h"
  42
  43 #ifdef CONFIG_LOCKDEP
  44 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
  45 #endif
  46
  47 static const struct address_space_operations configfs_aops = {
  48         .readpage       = simple_readpage,
  49         .write_begin    = simple_write_begin,
  50         .write_end      = simple_write_end,
  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 = d_inode(dentry);
  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         if (!sd_iattr) {
  70                 /* setting attributes for the first time, allocate now */
  71                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  72                 if (!sd_iattr)
  73                         return -ENOMEM;
  74                 /* assign default attributes */
  75                 sd_iattr->ia_mode = sd->s_mode;
  76                 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  77                 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  78                 sd_iattr->ia_atime = sd_iattr->ia_mtime =
  79                         sd_iattr->ia_ctime = current_time(inode);
  80                 sd->s_iattr = sd_iattr;
  81         }
  82         /* attributes were changed atleast once in past */
  83
  84         error = simple_setattr(dentry, iattr);
  85         if (error)
  86                 return error;
  87
  88         if (ia_valid & ATTR_UID)
  89                 sd_iattr->ia_uid = iattr->ia_uid;
  90         if (ia_valid & ATTR_GID)
  91                 sd_iattr->ia_gid = iattr->ia_gid;
  92         if (ia_valid & ATTR_ATIME)
  93                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
  94                                                 inode->i_sb->s_time_gran);
  95         if (ia_valid & ATTR_MTIME)
  96                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
  97                                                 inode->i_sb->s_time_gran);
  98         if (ia_valid & ATTR_CTIME)
  99                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 100                                                 inode->i_sb->s_time_gran);
 101         if (ia_valid & ATTR_MODE) {
 102                 umode_t mode = iattr->ia_mode;
 103
 104                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 105                         mode &= ~S_ISGID;
 106                 sd_iattr->ia_mode = sd->s_mode = mode;
 107         }
 108
 109         return error;
 110 }
 111
 112 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
 113 {
 114         inode->i_mode = mode;
 115         inode->i_atime = inode->i_mtime =
 116                 inode->i_ctime = current_time(inode);
 117 }
 118
 119 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 120 {
 121         inode->i_mode = iattr->ia_mode;
 122         inode->i_uid = iattr->ia_uid;
 123         inode->i_gid = iattr->ia_gid;
 124         inode->i_atime = iattr->ia_atime;
 125         inode->i_mtime = iattr->ia_mtime;
 126         inode->i_ctime = iattr->ia_ctime;
 127 }
 128
 129 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 130                                  struct super_block *s)
 131 {
 132         struct inode * inode = new_inode(s);
 133         if (inode) {
 134                 inode->i_ino = get_next_ino();
 135                 inode->i_mapping->a_ops = &configfs_aops;
 136                 inode->i_op = &configfs_inode_operations;
 137
 138                 if (sd->s_iattr) {
 139                         /* sysfs_dirent has non-default attributes
 140                          * get them for the new inode from persistent copy
 141                          * in sysfs_dirent
 142                          */
 143                         set_inode_attr(inode, sd->s_iattr);
 144                 } else
 145                         set_default_inode_attr(inode, mode);
 146         }
 147         return inode;
 148 }
 149
 150 #ifdef CONFIG_LOCKDEP
 151
 152 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 153                                           struct inode *inode)
 154 {
 155         int depth = sd->s_depth;
 156
 157         if (depth > 0) {
 158                 if (depth <= ARRAY_SIZE(default_group_class)) {
 159                         lockdep_set_class(&inode->i_rwsem,
 160                                           &default_group_class[depth - 1]);
 161                 } else {
 162                         /*
 163                          * In practice the maximum level of locking depth is
 164                          * already reached. Just inform about possible reasons.
 165                          */
 166                         pr_info("Too many levels of inodes for the locking correctness validator.\n");
 167                         pr_info("Spurious warnings may appear.\n");
 168                 }
 169         }
 170 }
 171
 172 #else /* CONFIG_LOCKDEP */
 173
 174 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 175                                           struct inode *inode)
 176 {
 177 }
 178
 179 #endif /* CONFIG_LOCKDEP */
 180
 181 int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
 182 {
 183         int error = 0;
 184         struct inode *inode = NULL;
 185         struct configfs_dirent *sd;
 186         struct inode *p_inode;
 187
 188         if (!dentry)
 189                 return -ENOENT;
 190
 191         if (d_really_is_positive(dentry))
 192                 return -EEXIST;
 193
 194         sd = dentry->d_fsdata;
 195         inode = configfs_new_inode(mode, sd, dentry->d_sb);
 196         if (!inode)
 197                 return -ENOMEM;
 198
 199         p_inode = d_inode(dentry->d_parent);
 200         p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
 201         configfs_set_inode_lock_class(sd, inode);
 202
 203         init(inode);
 204         if (S_ISDIR(mode) || S_ISLNK(mode)) {
 205                 /*
 206                  * ->symlink(), ->mkdir(), configfs_register_subsystem() or
 207                  * create_default_group() - already hashed.
 208                  */
 209                 d_instantiate(dentry, inode);
 210                 dget(dentry);  /* pin link and directory dentries in core */
 211         } else {
 212                 /* ->lookup() */
 213                 d_add(dentry, inode);
 214         }
 215         return error;
 216 }
 217
 218 /*
 219  * Get the name for corresponding element represented by the given configfs_dirent
 220  */
 221 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 222 {
 223         struct configfs_attribute *attr;
 224
 225         BUG_ON(!sd || !sd->s_element);
 226
 227         /* These always have a dentry, so use that */
 228         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 229                 return sd->s_dentry->d_name.name;
 230
 231         if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
 232                 attr = sd->s_element;
 233                 return attr->ca_name;
 234         }
 235         return NULL;
 236 }
 237
 238
 239 /*
 240  * Unhashes the dentry corresponding to given configfs_dirent
 241  * Called with parent inode's i_mutex held.
 242  */
 243 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 244 {
 245         struct dentry * dentry = sd->s_dentry;
 246
 247         if (dentry) {
 248                 spin_lock(&dentry->d_lock);
 249                 if (simple_positive(dentry)) {
 250                         dget_dlock(dentry);
 251                         __d_drop(dentry);
 252                         spin_unlock(&dentry->d_lock);
 253                         simple_unlink(d_inode(parent), dentry);
 254                 } else
 255                         spin_unlock(&dentry->d_lock);
 256         }
 257 }
 258
 259 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 260 {
 261         struct configfs_dirent * sd;
 262         struct configfs_dirent * parent_sd = dir->d_fsdata;
 263
 264         if (d_really_is_negative(dir))
 265                 /* no inode means this hasn't been made visible yet */
 266                 return;
 267
 268         inode_lock(d_inode(dir));
 269         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 270                 if (!sd->s_element)
 271                         continue;
 272                 if (!strcmp(configfs_get_name(sd), name)) {
 273                         spin_lock(&configfs_dirent_lock);
 274                         list_del_init(&sd->s_sibling);
 275                         spin_unlock(&configfs_dirent_lock);
 276                         configfs_drop_dentry(sd, dir);
 277                         configfs_put(sd);
 278                         break;
 279                 }
 280         }
 281         inode_unlock(d_inode(dir));
 282 }