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 #include <linux/slab.h> 38 39 #include <linux/configfs.h> 40 #include "configfs_internal.h" 41 42 #ifdef CONFIG_LOCKDEP 43 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH]; 44 #endif 45 46 extern struct super_block * configfs_sb; 47 48 static const struct address_space_operations configfs_aops = { 49 .readpage = simple_readpage, 50 .write_begin = simple_write_begin, 51 .write_end = simple_write_end, 52 }; 53 54 static struct backing_dev_info configfs_backing_dev_info = { 55 .name = "configfs", 56 .ra_pages = 0, /* No readahead */ 57 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, 58 }; 59 60 static const struct inode_operations configfs_inode_operations ={ 61 .setattr = configfs_setattr, 62 }; 63 64 int configfs_setattr(struct dentry * dentry, struct iattr * iattr) 65 { 66 struct inode * inode = dentry->d_inode; 67 struct configfs_dirent * sd = dentry->d_fsdata; 68 struct iattr * sd_iattr; 69 unsigned int ia_valid = iattr->ia_valid; 70 int error; 71 72 if (!sd) 73 return -EINVAL; 74 75 sd_iattr = sd->s_iattr; 76 if (!sd_iattr) { 77 /* setting attributes for the first time, allocate now */ 78 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 79 if (!sd_iattr) 80 return -ENOMEM; 81 /* assign default attributes */ 82 sd_iattr->ia_mode = sd->s_mode; 83 sd_iattr->ia_uid = 0; 84 sd_iattr->ia_gid = 0; 85 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 86 sd->s_iattr = sd_iattr; 87 } 88 /* attributes were changed atleast once in past */ 89 90 error = simple_setattr(dentry, iattr); 91 if (error) 92 return error; 93 94 if (ia_valid & ATTR_UID) 95 sd_iattr->ia_uid = iattr->ia_uid; 96 if (ia_valid & ATTR_GID) 97 sd_iattr->ia_gid = iattr->ia_gid; 98 if (ia_valid & ATTR_ATIME) 99 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 100 inode->i_sb->s_time_gran); 101 if (ia_valid & ATTR_MTIME) 102 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 103 inode->i_sb->s_time_gran); 104 if (ia_valid & ATTR_CTIME) 105 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 106 inode->i_sb->s_time_gran); 107 if (ia_valid & ATTR_MODE) { 108 umode_t mode = iattr->ia_mode; 109 110 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 111 mode &= ~S_ISGID; 112 sd_iattr->ia_mode = sd->s_mode = mode; 113 } 114 115 return error; 116 } 117 118 static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 119 { 120 inode->i_mode = mode; 121 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 122 } 123 124 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 125 { 126 inode->i_mode = iattr->ia_mode; 127 inode->i_uid = iattr->ia_uid; 128 inode->i_gid = iattr->ia_gid; 129 inode->i_atime = iattr->ia_atime; 130 inode->i_mtime = iattr->ia_mtime; 131 inode->i_ctime = iattr->ia_ctime; 132 } 133 134 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd) 135 { 136 struct inode * inode = new_inode(configfs_sb); 137 if (inode) { 138 inode->i_mapping->a_ops = &configfs_aops; 139 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info; 140 inode->i_op = &configfs_inode_operations; 141 142 if (sd->s_iattr) { 143 /* sysfs_dirent has non-default attributes 144 * get them for the new inode from persistent copy 145 * in sysfs_dirent 146 */ 147 set_inode_attr(inode, sd->s_iattr); 148 } else 149 set_default_inode_attr(inode, mode); 150 } 151 return inode; 152 } 153 154 #ifdef CONFIG_LOCKDEP 155 156 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 157 struct inode *inode) 158 { 159 int depth = sd->s_depth; 160 161 if (depth > 0) { 162 if (depth <= ARRAY_SIZE(default_group_class)) { 163 lockdep_set_class(&inode->i_mutex, 164 &default_group_class[depth - 1]); 165 } else { 166 /* 167 * In practice the maximum level of locking depth is 168 * already reached. Just inform about possible reasons. 169 */ 170 printk(KERN_INFO "configfs: Too many levels of inodes" 171 " for the locking correctness validator.\n"); 172 printk(KERN_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, int mode, int (*init)(struct inode *)) 187 { 188 int error = 0; 189 struct inode * inode = NULL; 190 if (dentry) { 191 if (!dentry->d_inode) { 192 struct configfs_dirent *sd = dentry->d_fsdata; 193 if ((inode = configfs_new_inode(mode, sd))) { 194 if (dentry->d_parent && dentry->d_parent->d_inode) { 195 struct inode *p_inode = dentry->d_parent->d_inode; 196 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 197 } 198 configfs_set_inode_lock_class(sd, inode); 199 goto Proceed; 200 } 201 else 202 error = -ENOMEM; 203 } else 204 error = -EEXIST; 205 } else 206 error = -ENOENT; 207 goto Done; 208 209 Proceed: 210 if (init) 211 error = init(inode); 212 if (!error) { 213 d_instantiate(dentry, inode); 214 if (S_ISDIR(mode) || S_ISLNK(mode)) 215 dget(dentry); /* pin link and directory dentries in core */ 216 } else 217 iput(inode); 218 Done: 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(&dcache_lock); 253 spin_lock(&dentry->d_lock); 254 if (!(d_unhashed(dentry) && dentry->d_inode)) { 255 dget_locked(dentry); 256 __d_drop(dentry); 257 spin_unlock(&dentry->d_lock); 258 spin_unlock(&dcache_lock); 259 simple_unlink(parent->d_inode, dentry); 260 } else { 261 spin_unlock(&dentry->d_lock); 262 spin_unlock(&dcache_lock); 263 } 264 } 265 } 266 267 void configfs_hash_and_remove(struct dentry * dir, const char * name) 268 { 269 struct configfs_dirent * sd; 270 struct configfs_dirent * parent_sd = dir->d_fsdata; 271 272 if (dir->d_inode == NULL) 273 /* no inode means this hasn't been made visible yet */ 274 return; 275 276 mutex_lock(&dir->d_inode->i_mutex); 277 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 278 if (!sd->s_element) 279 continue; 280 if (!strcmp(configfs_get_name(sd), name)) { 281 spin_lock(&configfs_dirent_lock); 282 list_del_init(&sd->s_sibling); 283 spin_unlock(&configfs_dirent_lock); 284 configfs_drop_dentry(sd, dir); 285 configfs_put(sd); 286 break; 287 } 288 } 289 mutex_unlock(&dir->d_inode->i_mutex); 290 } 291 292 int __init configfs_inode_init(void) 293 { 294 return bdi_init(&configfs_backing_dev_info); 295 } 296 297 void __exit configfs_inode_exit(void) 298 { 299 bdi_destroy(&configfs_backing_dev_info); 300 } 301