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 .ra_pages = 0, /* No readahead */ 55 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, 56 }; 57 58 static const struct inode_operations configfs_inode_operations ={ 59 .setattr = configfs_setattr, 60 }; 61 62 int configfs_setattr(struct dentry * dentry, struct iattr * iattr) 63 { 64 struct inode * inode = dentry->d_inode; 65 struct configfs_dirent * sd = dentry->d_fsdata; 66 struct iattr * sd_iattr; 67 unsigned int ia_valid = iattr->ia_valid; 68 int error; 69 70 if (!sd) 71 return -EINVAL; 72 73 sd_iattr = sd->s_iattr; 74 75 error = inode_change_ok(inode, iattr); 76 if (error) 77 return error; 78 79 error = inode_setattr(inode, iattr); 80 if (error) 81 return error; 82 83 if (!sd_iattr) { 84 /* setting attributes for the first time, allocate now */ 85 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 86 if (!sd_iattr) 87 return -ENOMEM; 88 /* assign default attributes */ 89 sd_iattr->ia_mode = sd->s_mode; 90 sd_iattr->ia_uid = 0; 91 sd_iattr->ia_gid = 0; 92 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 93 sd->s_iattr = sd_iattr; 94 } 95 96 /* attributes were changed atleast once in past */ 97 98 if (ia_valid & ATTR_UID) 99 sd_iattr->ia_uid = iattr->ia_uid; 100 if (ia_valid & ATTR_GID) 101 sd_iattr->ia_gid = iattr->ia_gid; 102 if (ia_valid & ATTR_ATIME) 103 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 104 inode->i_sb->s_time_gran); 105 if (ia_valid & ATTR_MTIME) 106 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 107 inode->i_sb->s_time_gran); 108 if (ia_valid & ATTR_CTIME) 109 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 110 inode->i_sb->s_time_gran); 111 if (ia_valid & ATTR_MODE) { 112 umode_t mode = iattr->ia_mode; 113 114 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 115 mode &= ~S_ISGID; 116 sd_iattr->ia_mode = sd->s_mode = mode; 117 } 118 119 return error; 120 } 121 122 static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 123 { 124 inode->i_mode = mode; 125 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 126 } 127 128 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 129 { 130 inode->i_mode = iattr->ia_mode; 131 inode->i_uid = iattr->ia_uid; 132 inode->i_gid = iattr->ia_gid; 133 inode->i_atime = iattr->ia_atime; 134 inode->i_mtime = iattr->ia_mtime; 135 inode->i_ctime = iattr->ia_ctime; 136 } 137 138 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd) 139 { 140 struct inode * inode = new_inode(configfs_sb); 141 if (inode) { 142 inode->i_mapping->a_ops = &configfs_aops; 143 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info; 144 inode->i_op = &configfs_inode_operations; 145 146 if (sd->s_iattr) { 147 /* sysfs_dirent has non-default attributes 148 * get them for the new inode from persistent copy 149 * in sysfs_dirent 150 */ 151 set_inode_attr(inode, sd->s_iattr); 152 } else 153 set_default_inode_attr(inode, mode); 154 } 155 return inode; 156 } 157 158 #ifdef CONFIG_LOCKDEP 159 160 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 161 struct inode *inode) 162 { 163 int depth = sd->s_depth; 164 165 if (depth > 0) { 166 if (depth <= ARRAY_SIZE(default_group_class)) { 167 lockdep_set_class(&inode->i_mutex, 168 &default_group_class[depth - 1]); 169 } else { 170 /* 171 * In practice the maximum level of locking depth is 172 * already reached. Just inform about possible reasons. 173 */ 174 printk(KERN_INFO "configfs: Too many levels of inodes" 175 " for the locking correctness validator.\n"); 176 printk(KERN_INFO "Spurious warnings may appear.\n"); 177 } 178 } 179 } 180 181 #else /* CONFIG_LOCKDEP */ 182 183 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 184 struct inode *inode) 185 { 186 } 187 188 #endif /* CONFIG_LOCKDEP */ 189 190 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) 191 { 192 int error = 0; 193 struct inode * inode = NULL; 194 if (dentry) { 195 if (!dentry->d_inode) { 196 struct configfs_dirent *sd = dentry->d_fsdata; 197 if ((inode = configfs_new_inode(mode, sd))) { 198 if (dentry->d_parent && dentry->d_parent->d_inode) { 199 struct inode *p_inode = dentry->d_parent->d_inode; 200 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 201 } 202 configfs_set_inode_lock_class(sd, inode); 203 goto Proceed; 204 } 205 else 206 error = -ENOMEM; 207 } else 208 error = -EEXIST; 209 } else 210 error = -ENOENT; 211 goto Done; 212 213 Proceed: 214 if (init) 215 error = init(inode); 216 if (!error) { 217 d_instantiate(dentry, inode); 218 if (S_ISDIR(mode) || S_ISLNK(mode)) 219 dget(dentry); /* pin link and directory dentries in core */ 220 } else 221 iput(inode); 222 Done: 223 return error; 224 } 225 226 /* 227 * Get the name for corresponding element represented by the given configfs_dirent 228 */ 229 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 230 { 231 struct configfs_attribute *attr; 232 233 BUG_ON(!sd || !sd->s_element); 234 235 /* These always have a dentry, so use that */ 236 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 237 return sd->s_dentry->d_name.name; 238 239 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 240 attr = sd->s_element; 241 return attr->ca_name; 242 } 243 return NULL; 244 } 245 246 247 /* 248 * Unhashes the dentry corresponding to given configfs_dirent 249 * Called with parent inode's i_mutex held. 250 */ 251 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 252 { 253 struct dentry * dentry = sd->s_dentry; 254 255 if (dentry) { 256 spin_lock(&dcache_lock); 257 spin_lock(&dentry->d_lock); 258 if (!(d_unhashed(dentry) && dentry->d_inode)) { 259 dget_locked(dentry); 260 __d_drop(dentry); 261 spin_unlock(&dentry->d_lock); 262 spin_unlock(&dcache_lock); 263 simple_unlink(parent->d_inode, dentry); 264 } else { 265 spin_unlock(&dentry->d_lock); 266 spin_unlock(&dcache_lock); 267 } 268 } 269 } 270 271 void configfs_hash_and_remove(struct dentry * dir, const char * name) 272 { 273 struct configfs_dirent * sd; 274 struct configfs_dirent * parent_sd = dir->d_fsdata; 275 276 if (dir->d_inode == NULL) 277 /* no inode means this hasn't been made visible yet */ 278 return; 279 280 mutex_lock(&dir->d_inode->i_mutex); 281 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 282 if (!sd->s_element) 283 continue; 284 if (!strcmp(configfs_get_name(sd), name)) { 285 spin_lock(&configfs_dirent_lock); 286 list_del_init(&sd->s_sibling); 287 spin_unlock(&configfs_dirent_lock); 288 configfs_drop_dentry(sd, dir); 289 configfs_put(sd); 290 break; 291 } 292 } 293 mutex_unlock(&dir->d_inode->i_mutex); 294 } 295 296 int __init configfs_inode_init(void) 297 { 298 return bdi_init(&configfs_backing_dev_info); 299 } 300 301 void __exit configfs_inode_exit(void) 302 { 303 bdi_destroy(&configfs_backing_dev_info); 304 } 305