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 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, umode_t mode, int (*init)(struct inode *)) 188 { 189 int error = 0; 190 struct inode *inode = NULL; 191 struct configfs_dirent *sd; 192 struct inode *p_inode; 193 194 if (!dentry) 195 return -ENOENT; 196 197 if (dentry->d_inode) 198 return -EEXIST; 199 200 sd = dentry->d_fsdata; 201 inode = configfs_new_inode(mode, sd, dentry->d_sb); 202 if (!inode) 203 return -ENOMEM; 204 205 p_inode = dentry->d_parent->d_inode; 206 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 207 configfs_set_inode_lock_class(sd, inode); 208 209 if (init) { 210 error = init(inode); 211 if (error) { 212 iput(inode); 213 return error; 214 } 215 } 216 d_instantiate(dentry, inode); 217 if (S_ISDIR(mode) || S_ISLNK(mode)) 218 dget(dentry); /* pin link and directory dentries in core */ 219 return error; 220 } 221 222 /* 223 * Get the name for corresponding element represented by the given configfs_dirent 224 */ 225 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 226 { 227 struct configfs_attribute *attr; 228 229 BUG_ON(!sd || !sd->s_element); 230 231 /* These always have a dentry, so use that */ 232 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 233 return sd->s_dentry->d_name.name; 234 235 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 236 attr = sd->s_element; 237 return attr->ca_name; 238 } 239 return NULL; 240 } 241 242 243 /* 244 * Unhashes the dentry corresponding to given configfs_dirent 245 * Called with parent inode's i_mutex held. 246 */ 247 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 248 { 249 struct dentry * dentry = sd->s_dentry; 250 251 if (dentry) { 252 spin_lock(&dentry->d_lock); 253 if (!(d_unhashed(dentry) && dentry->d_inode)) { 254 dget_dlock(dentry); 255 __d_drop(dentry); 256 spin_unlock(&dentry->d_lock); 257 simple_unlink(parent->d_inode, dentry); 258 } else 259 spin_unlock(&dentry->d_lock); 260 } 261 } 262 263 void configfs_hash_and_remove(struct dentry * dir, const char * name) 264 { 265 struct configfs_dirent * sd; 266 struct configfs_dirent * parent_sd = dir->d_fsdata; 267 268 if (dir->d_inode == NULL) 269 /* no inode means this hasn't been made visible yet */ 270 return; 271 272 mutex_lock(&dir->d_inode->i_mutex); 273 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 274 if (!sd->s_element) 275 continue; 276 if (!strcmp(configfs_get_name(sd), name)) { 277 spin_lock(&configfs_dirent_lock); 278 list_del_init(&sd->s_sibling); 279 spin_unlock(&configfs_dirent_lock); 280 configfs_drop_dentry(sd, dir); 281 configfs_put(sd); 282 break; 283 } 284 } 285 mutex_unlock(&dir->d_inode->i_mutex); 286 } 287 288 int __init configfs_inode_init(void) 289 { 290 return bdi_init(&configfs_backing_dev_info); 291 } 292 293 void configfs_inode_exit(void) 294 { 295 bdi_destroy(&configfs_backing_dev_info); 296 } 297