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.txt for more information. 27 */ 28 29 #undef DEBUG 30 31 #include <linux/pagemap.h> 32 #include <linux/namei.h> 33 #include <linux/backing-dev.h> 34 #include <linux/capability.h> 35 #include <linux/sched.h> 36 #include <linux/lockdep.h> 37 38 #include <linux/configfs.h> 39 #include "configfs_internal.h" 40 41 #ifdef CONFIG_LOCKDEP 42 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH]; 43 #endif 44 45 extern struct super_block * configfs_sb; 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 76 error = inode_change_ok(inode, iattr); 77 if (error) 78 return error; 79 80 error = inode_setattr(inode, iattr); 81 if (error) 82 return error; 83 84 if (!sd_iattr) { 85 /* setting attributes for the first time, allocate now */ 86 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 87 if (!sd_iattr) 88 return -ENOMEM; 89 /* assign default attributes */ 90 sd_iattr->ia_mode = sd->s_mode; 91 sd_iattr->ia_uid = 0; 92 sd_iattr->ia_gid = 0; 93 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 94 sd->s_iattr = sd_iattr; 95 } 96 97 /* attributes were changed atleast once in past */ 98 99 if (ia_valid & ATTR_UID) 100 sd_iattr->ia_uid = iattr->ia_uid; 101 if (ia_valid & ATTR_GID) 102 sd_iattr->ia_gid = iattr->ia_gid; 103 if (ia_valid & ATTR_ATIME) 104 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 105 inode->i_sb->s_time_gran); 106 if (ia_valid & ATTR_MTIME) 107 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 108 inode->i_sb->s_time_gran); 109 if (ia_valid & ATTR_CTIME) 110 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 111 inode->i_sb->s_time_gran); 112 if (ia_valid & ATTR_MODE) { 113 umode_t mode = iattr->ia_mode; 114 115 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 116 mode &= ~S_ISGID; 117 sd_iattr->ia_mode = sd->s_mode = mode; 118 } 119 120 return error; 121 } 122 123 static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 124 { 125 inode->i_mode = mode; 126 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 127 } 128 129 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 130 { 131 inode->i_mode = iattr->ia_mode; 132 inode->i_uid = iattr->ia_uid; 133 inode->i_gid = iattr->ia_gid; 134 inode->i_atime = iattr->ia_atime; 135 inode->i_mtime = iattr->ia_mtime; 136 inode->i_ctime = iattr->ia_ctime; 137 } 138 139 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd) 140 { 141 struct inode * inode = new_inode(configfs_sb); 142 if (inode) { 143 inode->i_mapping->a_ops = &configfs_aops; 144 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info; 145 inode->i_op = &configfs_inode_operations; 146 147 if (sd->s_iattr) { 148 /* sysfs_dirent has non-default attributes 149 * get them for the new inode from persistent copy 150 * in sysfs_dirent 151 */ 152 set_inode_attr(inode, sd->s_iattr); 153 } else 154 set_default_inode_attr(inode, mode); 155 } 156 return inode; 157 } 158 159 #ifdef CONFIG_LOCKDEP 160 161 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 162 struct inode *inode) 163 { 164 int depth = sd->s_depth; 165 166 if (depth > 0) { 167 if (depth <= ARRAY_SIZE(default_group_class)) { 168 lockdep_set_class(&inode->i_mutex, 169 &default_group_class[depth - 1]); 170 } else { 171 /* 172 * In practice the maximum level of locking depth is 173 * already reached. Just inform about possible reasons. 174 */ 175 printk(KERN_INFO "configfs: Too many levels of inodes" 176 " for the locking correctness validator.\n"); 177 printk(KERN_INFO "Spurious warnings may appear.\n"); 178 } 179 } 180 } 181 182 #else /* CONFIG_LOCKDEP */ 183 184 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 185 struct inode *inode) 186 { 187 } 188 189 #endif /* CONFIG_LOCKDEP */ 190 191 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) 192 { 193 int error = 0; 194 struct inode * inode = NULL; 195 if (dentry) { 196 if (!dentry->d_inode) { 197 struct configfs_dirent *sd = dentry->d_fsdata; 198 if ((inode = configfs_new_inode(mode, sd))) { 199 if (dentry->d_parent && dentry->d_parent->d_inode) { 200 struct inode *p_inode = dentry->d_parent->d_inode; 201 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 202 } 203 configfs_set_inode_lock_class(sd, inode); 204 goto Proceed; 205 } 206 else 207 error = -ENOMEM; 208 } else 209 error = -EEXIST; 210 } else 211 error = -ENOENT; 212 goto Done; 213 214 Proceed: 215 if (init) 216 error = init(inode); 217 if (!error) { 218 d_instantiate(dentry, inode); 219 if (S_ISDIR(mode) || S_ISLNK(mode)) 220 dget(dentry); /* pin link and directory dentries in core */ 221 } else 222 iput(inode); 223 Done: 224 return error; 225 } 226 227 /* 228 * Get the name for corresponding element represented by the given configfs_dirent 229 */ 230 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 231 { 232 struct configfs_attribute *attr; 233 234 BUG_ON(!sd || !sd->s_element); 235 236 /* These always have a dentry, so use that */ 237 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 238 return sd->s_dentry->d_name.name; 239 240 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 241 attr = sd->s_element; 242 return attr->ca_name; 243 } 244 return NULL; 245 } 246 247 248 /* 249 * Unhashes the dentry corresponding to given configfs_dirent 250 * Called with parent inode's i_mutex held. 251 */ 252 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 253 { 254 struct dentry * dentry = sd->s_dentry; 255 256 if (dentry) { 257 spin_lock(&dcache_lock); 258 spin_lock(&dentry->d_lock); 259 if (!(d_unhashed(dentry) && dentry->d_inode)) { 260 dget_locked(dentry); 261 __d_drop(dentry); 262 spin_unlock(&dentry->d_lock); 263 spin_unlock(&dcache_lock); 264 simple_unlink(parent->d_inode, dentry); 265 } else { 266 spin_unlock(&dentry->d_lock); 267 spin_unlock(&dcache_lock); 268 } 269 } 270 } 271 272 void configfs_hash_and_remove(struct dentry * dir, const char * name) 273 { 274 struct configfs_dirent * sd; 275 struct configfs_dirent * parent_sd = dir->d_fsdata; 276 277 if (dir->d_inode == NULL) 278 /* no inode means this hasn't been made visible yet */ 279 return; 280 281 mutex_lock(&dir->d_inode->i_mutex); 282 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 283 if (!sd->s_element) 284 continue; 285 if (!strcmp(configfs_get_name(sd), name)) { 286 spin_lock(&configfs_dirent_lock); 287 list_del_init(&sd->s_sibling); 288 spin_unlock(&configfs_dirent_lock); 289 configfs_drop_dentry(sd, dir); 290 configfs_put(sd); 291 break; 292 } 293 } 294 mutex_unlock(&dir->d_inode->i_mutex); 295 } 296 297 int __init configfs_inode_init(void) 298 { 299 return bdi_init(&configfs_backing_dev_info); 300 } 301 302 void __exit configfs_inode_exit(void) 303 { 304 bdi_destroy(&configfs_backing_dev_info); 305 } 306