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 extern struct super_block * configfs_sb;
  48
  49 static const struct address_space_operations configfs_aops = {
  50         .readpage       = simple_readpage,
  51         .write_begin    = simple_write_begin,
  52         .write_end      = simple_write_end,
  53 };
  54
  55 static struct backing_dev_info configfs_backing_dev_info = {
  56         .name           = "configfs",
  57         .ra_pages       = 0,    /* No readahead */
  58         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
  59 };
  60
  61 static const struct inode_operations configfs_inode_operations ={
  62         .setattr        = configfs_setattr,
  63 };
  64
  65 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
  66 {
  67         struct inode * inode = dentry->d_inode;
  68         struct configfs_dirent * sd = dentry->d_fsdata;
  69         struct iattr * sd_iattr;
  70         unsigned int ia_valid = iattr->ia_valid;
  71         int error;
  72
  73         if (!sd)
  74                 return -EINVAL;
  75
  76         sd_iattr = sd->s_iattr;
  77         if (!sd_iattr) {
  78                 /* setting attributes for the first time, allocate now */
  79                 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
  80                 if (!sd_iattr)
  81                         return -ENOMEM;
  82                 /* assign default attributes */
  83                 sd_iattr->ia_mode = sd->s_mode;
  84                 sd_iattr->ia_uid = 0;
  85                 sd_iattr->ia_gid = 0;
  86                 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
  87                 sd->s_iattr = sd_iattr;
  88         }
  89         /* attributes were changed atleast once in past */
  90
  91         error = simple_setattr(dentry, iattr);
  92         if (error)
  93                 return error;
  94
  95         if (ia_valid & ATTR_UID)
  96                 sd_iattr->ia_uid = iattr->ia_uid;
  97         if (ia_valid & ATTR_GID)
  98                 sd_iattr->ia_gid = iattr->ia_gid;
  99         if (ia_valid & ATTR_ATIME)
 100                 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
 101                                                 inode->i_sb->s_time_gran);
 102         if (ia_valid & ATTR_MTIME)
 103                 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
 104                                                 inode->i_sb->s_time_gran);
 105         if (ia_valid & ATTR_CTIME)
 106                 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
 107                                                 inode->i_sb->s_time_gran);
 108         if (ia_valid & ATTR_MODE) {
 109                 umode_t mode = iattr->ia_mode;
 110
 111                 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
 112                         mode &= ~S_ISGID;
 113                 sd_iattr->ia_mode = sd->s_mode = mode;
 114         }
 115
 116         return error;
 117 }
 118
 119 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
 120 {
 121         inode->i_mode = mode;
 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(umode_t mode, struct configfs_dirent * sd)
 136 {
 137         struct inode * inode = new_inode(configfs_sb);
 138         if (inode) {
 139                 inode->i_ino = get_next_ino();
 140                 inode->i_mapping->a_ops = &configfs_aops;
 141                 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
 142                 inode->i_op = &configfs_inode_operations;
 143
 144                 if (sd->s_iattr) {
 145                         /* sysfs_dirent has non-default attributes
 146                          * get them for the new inode from persistent copy
 147                          * in sysfs_dirent
 148                          */
 149                         set_inode_attr(inode, sd->s_iattr);
 150                 } else
 151                         set_default_inode_attr(inode, mode);
 152         }
 153         return inode;
 154 }
 155
 156 #ifdef CONFIG_LOCKDEP
 157
 158 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 159                                           struct inode *inode)
 160 {
 161         int depth = sd->s_depth;
 162
 163         if (depth > 0) {
 164                 if (depth <= ARRAY_SIZE(default_group_class)) {
 165                         lockdep_set_class(&inode->i_mutex,
 166                                           &default_group_class[depth - 1]);
 167                 } else {
 168                         /*
 169                          * In practice the maximum level of locking depth is
 170                          * already reached. Just inform about possible reasons.
 171                          */
 172                         printk(KERN_INFO "configfs: Too many levels of inodes"
 173                                " for the locking correctness validator.\n");
 174                         printk(KERN_INFO "Spurious warnings may appear.\n");
 175                 }
 176         }
 177 }
 178
 179 #else /* CONFIG_LOCKDEP */
 180
 181 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 182                                           struct inode *inode)
 183 {
 184 }
 185
 186 #endif /* CONFIG_LOCKDEP */
 187
 188 int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
 189 {
 190         int error = 0;
 191         struct inode * inode = NULL;
 192         if (dentry) {
 193                 if (!dentry->d_inode) {
 194                         struct configfs_dirent *sd = dentry->d_fsdata;
 195                         if ((inode = configfs_new_inode(mode, sd))) {
 196                                 if (dentry->d_parent && dentry->d_parent->d_inode) {
 197                                         struct inode *p_inode = dentry->d_parent->d_inode;
 198                                         p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 199                                 }
 200                                 configfs_set_inode_lock_class(sd, inode);
 201                                 goto Proceed;
 202                         }
 203                         else
 204                                 error = -ENOMEM;
 205                 } else
 206                         error = -EEXIST;
 207         } else
 208                 error = -ENOENT;
 209         goto Done;
 210
 211  Proceed:
 212         if (init)
 213                 error = init(inode);
 214         if (!error) {
 215                 d_instantiate(dentry, inode);
 216                 if (S_ISDIR(mode) || S_ISLNK(mode))
 217                         dget(dentry);  /* pin link and directory dentries in core */
 218         } else
 219                 iput(inode);
 220  Done:
 221         return error;
 222 }
 223
 224 /*
 225  * Get the name for corresponding element represented by the given configfs_dirent
 226  */
 227 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 228 {
 229         struct configfs_attribute *attr;
 230
 231         BUG_ON(!sd || !sd->s_element);
 232
 233         /* These always have a dentry, so use that */
 234         if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 235                 return sd->s_dentry->d_name.name;
 236
 237         if (sd->s_type & CONFIGFS_ITEM_ATTR) {
 238                 attr = sd->s_element;
 239                 return attr->ca_name;
 240         }
 241         return NULL;
 242 }
 243
 244
 245 /*
 246  * Unhashes the dentry corresponding to given configfs_dirent
 247  * Called with parent inode's i_mutex held.
 248  */
 249 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 250 {
 251         struct dentry * dentry = sd->s_dentry;
 252
 253         if (dentry) {
 254                 spin_lock(&dentry->d_lock);
 255                 if (!(d_unhashed(dentry) && dentry->d_inode)) {
 256                         dget_dlock(dentry);
 257                         __d_drop(dentry);
 258                         spin_unlock(&dentry->d_lock);
 259                         simple_unlink(parent->d_inode, dentry);
 260                 } else
 261                         spin_unlock(&dentry->d_lock);
 262         }
 263 }
 264
 265 void configfs_hash_and_remove(struct dentry * dir, const char * name)
 266 {
 267         struct configfs_dirent * sd;
 268         struct configfs_dirent * parent_sd = dir->d_fsdata;
 269
 270         if (dir->d_inode == NULL)
 271                 /* no inode means this hasn't been made visible yet */
 272                 return;
 273
 274         mutex_lock(&dir->d_inode->i_mutex);
 275         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 276                 if (!sd->s_element)
 277                         continue;
 278                 if (!strcmp(configfs_get_name(sd), name)) {
 279                         spin_lock(&configfs_dirent_lock);
 280                         list_del_init(&sd->s_sibling);
 281                         spin_unlock(&configfs_dirent_lock);
 282                         configfs_drop_dentry(sd, dir);
 283                         configfs_put(sd);
 284                         break;
 285                 }
 286         }
 287         mutex_unlock(&dir->d_inode->i_mutex);
 288 }
 289
 290 int __init configfs_inode_init(void)
 291 {
 292         return bdi_init(&configfs_backing_dev_info);
 293 }
 294
 295 void configfs_inode_exit(void)
 296 {
 297         bdi_destroy(&configfs_backing_dev_info);
 298 }