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