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_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, int mode, int (*init)(struct inode *)) 188 { 189 int error = 0; 190 struct inode * inode = NULL; 191 if (dentry) { 192 if (!dentry->d_inode) { 193 struct configfs_dirent *sd = dentry->d_fsdata; 194 if ((inode = configfs_new_inode(mode, sd))) { 195 if (dentry->d_parent && dentry->d_parent->d_inode) { 196 struct inode *p_inode = dentry->d_parent->d_inode; 197 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 198 } 199 configfs_set_inode_lock_class(sd, inode); 200 goto Proceed; 201 } 202 else 203 error = -ENOMEM; 204 } else 205 error = -EEXIST; 206 } else 207 error = -ENOENT; 208 goto Done; 209 210 Proceed: 211 if (init) 212 error = init(inode); 213 if (!error) { 214 d_instantiate(dentry, inode); 215 if (S_ISDIR(mode) || S_ISLNK(mode)) 216 dget(dentry); /* pin link and directory dentries in core */ 217 } else 218 iput(inode); 219 Done: 220 return error; 221 } 222 223 /* 224 * Get the name for corresponding element represented by the given configfs_dirent 225 */ 226 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 227 { 228 struct configfs_attribute *attr; 229 230 BUG_ON(!sd || !sd->s_element); 231 232 /* These always have a dentry, so use that */ 233 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 234 return sd->s_dentry->d_name.name; 235 236 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 237 attr = sd->s_element; 238 return attr->ca_name; 239 } 240 return NULL; 241 } 242 243 244 /* 245 * Unhashes the dentry corresponding to given configfs_dirent 246 * Called with parent inode's i_mutex held. 247 */ 248 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 249 { 250 struct dentry * dentry = sd->s_dentry; 251 252 if (dentry) { 253 spin_lock(&dentry->d_lock); 254 if (!(d_unhashed(dentry) && dentry->d_inode)) { 255 dget_dlock(dentry); 256 __d_drop(dentry); 257 spin_unlock(&dentry->d_lock); 258 simple_unlink(parent->d_inode, dentry); 259 } else 260 spin_unlock(&dentry->d_lock); 261 } 262 } 263 264 void configfs_hash_and_remove(struct dentry * dir, const char * name) 265 { 266 struct configfs_dirent * sd; 267 struct configfs_dirent * parent_sd = dir->d_fsdata; 268 269 if (dir->d_inode == NULL) 270 /* no inode means this hasn't been made visible yet */ 271 return; 272 273 mutex_lock(&dir->d_inode->i_mutex); 274 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 275 if (!sd->s_element) 276 continue; 277 if (!strcmp(configfs_get_name(sd), name)) { 278 spin_lock(&configfs_dirent_lock); 279 list_del_init(&sd->s_sibling); 280 spin_unlock(&configfs_dirent_lock); 281 configfs_drop_dentry(sd, dir); 282 configfs_put(sd); 283 break; 284 } 285 } 286 mutex_unlock(&dir->d_inode->i_mutex); 287 } 288 289 int __init configfs_inode_init(void) 290 { 291 return bdi_init(&configfs_backing_dev_info); 292 } 293 294 void __exit configfs_inode_exit(void) 295 { 296 bdi_destroy(&configfs_backing_dev_info); 297 } 298