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 struct backing_dev_info configfs_backing_dev_info = {
  54         .name           = "configfs",
  55         .ra_pages       = 0,    /* No readahead */
  56         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
  57 };
  58
  59 static const struct inode_operations configfs_inode_operations ={
  60         .setattr        = configfs_setattr,
  61 };
  62
  63 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  64 {
  65         struct inode * inode = dentry->d_inode;
  66         struct configfs_dirent * sd = dentry->d_fsdata;
  67         struct iattr * sd_iattr;
  68         unsigned int ia_valid = iattr->ia_valid;
  69         int error;
  70
  71         if (!sd)
  72                 return -EINVAL;
  73
  74         sd_iattr = sd->s_iattr;
  75         if (!sd_iattr) {
  76                 /* setting attributes for the first time, allocate now */
  77                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  78                 if (!sd_iattr)
  79                         return -ENOMEM;
  80                 /* assign default attributes */
  81                 sd_iattr->ia_mode = sd->s_mode;
  82                 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
  83                 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
  84                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  85                 sd->s_iattr = sd_iattr;
  86         }
  87         /* attributes were changed atleast once in past */
  88
  89         error = simple_setattr(dentry, iattr);
  90         if (error)
  91                 return error;
  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, umode_t mode)
 118 {
 119         inode->i_mode = mode;
 120         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 121 }
 122
 123 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
 124 {
 125         inode->i_mode = iattr->ia_mode;
 126         inode->i_uid = iattr->ia_uid;
 127         inode->i_gid = iattr->ia_gid;
 128         inode->i_atime = iattr->ia_atime;
 129         inode->i_mtime = iattr->ia_mtime;
 130         inode->i_ctime = iattr->ia_ctime;
 131 }
 132
 133 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
 134                                  struct super_block *s)
 135 {
 136         struct inode * inode = new_inode(s);
 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                         pr_info("Too many levels of inodes for the locking correctness validator.\n");
 172                         pr_info("Spurious warnings may appear.\n");
 173                 }
 174         }
 175 }
 176
 177 #else /* CONFIG_LOCKDEP */
 178
 179 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 180                                           struct inode *inode)
 181 {
 182 }
 183
 184 #endif /* CONFIG_LOCKDEP */
 185
 186 int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
 187 {
 188         int error = 0;
 189         struct inode *inode = NULL;
 190         struct configfs_dirent *sd;
 191         struct inode *p_inode;
 192
 193         if (!dentry)
 194                 return -ENOENT;
 195
 196         if (dentry->d_inode)
 197                 return -EEXIST;
 198
 199         sd = dentry->d_fsdata;
 200         inode = configfs_new_inode(mode, sd, dentry->d_sb);
 201         if (!inode)
 202                 return -ENOMEM;
 203
 204         p_inode = dentry->d_parent->d_inode;
 205         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 206         configfs_set_inode_lock_class(sd, inode);
 207
 208         if (init) {
 209                 error = init(inode);
 210                 if (error) {
 211                         iput(inode);
 212                         return error;
 213                 }
 214         }
 215         d_instantiate(dentry, inode);
 216         if (S_ISDIR(mode) || S_ISLNK(mode))
 217                 dget(dentry);  /* pin link and directory dentries in core */
 218         return error;
 219 }
 220
 221 /*
 222  * Get the name for corresponding element represented by the given configfs_dirent
 223  */
 224 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 225 {
 226         struct configfs_attribute *attr;
 227
 228         BUG_ON(!sd || !sd->s_element);
 229
 230         /* These always have a dentry, so use that */
 231         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 232                 return sd->s_dentry->d_name.name;
 233
 234         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 235                 attr = sd->s_element;
 236                 return attr->ca_name;
 237         }
 238         return NULL;
 239 }
 240
 241
 242 /*
 243  * Unhashes the dentry corresponding to given configfs_dirent
 244  * Called with parent inode's i_mutex held.
 245  */
 246 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 247 {
 248         struct dentry * dentry = sd->s_dentry;
 249
 250         if (dentry) {
 251                 spin_lock(&dentry->d_lock);
 252                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 253                         dget_dlock(dentry);
 254                         __d_drop(dentry);
 255                         spin_unlock(&dentry->d_lock);
 256                         simple_unlink(parent->d_inode, dentry);
 257                 } else
 258                         spin_unlock(&dentry->d_lock);
 259         }
 260 }
 261
 262 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 263 {
 264         struct configfs_dirent * sd;
 265         struct configfs_dirent * parent_sd = dir->d_fsdata;
 266
 267         if (dir->d_inode == NULL)
 268                 /* no inode means this hasn't been made visible yet */
 269                 return;
 270
 271         mutex_lock(&dir->d_inode->i_mutex);
 272         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 273                 if (!sd->s_element)
 274                         continue;
 275                 if (!strcmp(configfs_get_name(sd), name)) {
 276                         spin_lock(&configfs_dirent_lock);
 277                         list_del_init(&sd->s_sibling);
 278                         spin_unlock(&configfs_dirent_lock);
 279                         configfs_drop_dentry(sd, dir);
 280                         configfs_put(sd);
 281                         break;
 282                 }
 283         }
 284         mutex_unlock(&dir->d_inode->i_mutex);
 285 }
 286
 287 int __init configfs_inode_init(void)
 288 {
 289         return bdi_init(&configfs_backing_dev_info);
 290 }
 291
 292 void configfs_inode_exit(void)
 293 {
 294         bdi_destroy(&configfs_backing_dev_info);
 295 }