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 } 299