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 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 const struct inode_operations configfs_inode_operations ={ 54 .setattr = configfs_setattr, 55 }; 56 57 int configfs_setattr(struct dentry * dentry, struct iattr * iattr) 58 { 59 struct inode * inode = d_inode(dentry); 60 struct configfs_dirent * sd = dentry->d_fsdata; 61 struct iattr * sd_iattr; 62 unsigned int ia_valid = iattr->ia_valid; 63 int error; 64 65 if (!sd) 66 return -EINVAL; 67 68 sd_iattr = sd->s_iattr; 69 if (!sd_iattr) { 70 /* setting attributes for the first time, allocate now */ 71 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 72 if (!sd_iattr) 73 return -ENOMEM; 74 /* assign default attributes */ 75 sd_iattr->ia_mode = sd->s_mode; 76 sd_iattr->ia_uid = GLOBAL_ROOT_UID; 77 sd_iattr->ia_gid = GLOBAL_ROOT_GID; 78 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 79 sd->s_iattr = sd_iattr; 80 } 81 /* attributes were changed atleast once in past */ 82 83 error = simple_setattr(dentry, iattr); 84 if (error) 85 return error; 86 87 if (ia_valid & ATTR_UID) 88 sd_iattr->ia_uid = iattr->ia_uid; 89 if (ia_valid & ATTR_GID) 90 sd_iattr->ia_gid = iattr->ia_gid; 91 if (ia_valid & ATTR_ATIME) 92 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 93 inode->i_sb->s_time_gran); 94 if (ia_valid & ATTR_MTIME) 95 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 96 inode->i_sb->s_time_gran); 97 if (ia_valid & ATTR_CTIME) 98 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 99 inode->i_sb->s_time_gran); 100 if (ia_valid & ATTR_MODE) { 101 umode_t mode = iattr->ia_mode; 102 103 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 104 mode &= ~S_ISGID; 105 sd_iattr->ia_mode = sd->s_mode = mode; 106 } 107 108 return error; 109 } 110 111 static inline void set_default_inode_attr(struct inode * inode, umode_t mode) 112 { 113 inode->i_mode = mode; 114 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 115 } 116 117 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 118 { 119 inode->i_mode = iattr->ia_mode; 120 inode->i_uid = iattr->ia_uid; 121 inode->i_gid = iattr->ia_gid; 122 inode->i_atime = iattr->ia_atime; 123 inode->i_mtime = iattr->ia_mtime; 124 inode->i_ctime = iattr->ia_ctime; 125 } 126 127 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd, 128 struct super_block *s) 129 { 130 struct inode * inode = new_inode(s); 131 if (inode) { 132 inode->i_ino = get_next_ino(); 133 inode->i_mapping->a_ops = &configfs_aops; 134 inode->i_op = &configfs_inode_operations; 135 136 if (sd->s_iattr) { 137 /* sysfs_dirent has non-default attributes 138 * get them for the new inode from persistent copy 139 * in sysfs_dirent 140 */ 141 set_inode_attr(inode, sd->s_iattr); 142 } else 143 set_default_inode_attr(inode, mode); 144 } 145 return inode; 146 } 147 148 #ifdef CONFIG_LOCKDEP 149 150 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 151 struct inode *inode) 152 { 153 int depth = sd->s_depth; 154 155 if (depth > 0) { 156 if (depth <= ARRAY_SIZE(default_group_class)) { 157 lockdep_set_class(&inode->i_mutex, 158 &default_group_class[depth - 1]); 159 } else { 160 /* 161 * In practice the maximum level of locking depth is 162 * already reached. Just inform about possible reasons. 163 */ 164 pr_info("Too many levels of inodes for the locking correctness validator.\n"); 165 pr_info("Spurious warnings may appear.\n"); 166 } 167 } 168 } 169 170 #else /* CONFIG_LOCKDEP */ 171 172 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 173 struct inode *inode) 174 { 175 } 176 177 #endif /* CONFIG_LOCKDEP */ 178 179 int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *)) 180 { 181 int error = 0; 182 struct inode *inode = NULL; 183 struct configfs_dirent *sd; 184 struct inode *p_inode; 185 186 if (!dentry) 187 return -ENOENT; 188 189 if (d_really_is_positive(dentry)) 190 return -EEXIST; 191 192 sd = dentry->d_fsdata; 193 inode = configfs_new_inode(mode, sd, dentry->d_sb); 194 if (!inode) 195 return -ENOMEM; 196 197 p_inode = d_inode(dentry->d_parent); 198 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 199 configfs_set_inode_lock_class(sd, inode); 200 201 init(inode); 202 d_instantiate(dentry, inode); 203 if (S_ISDIR(mode) || S_ISLNK(mode)) 204 dget(dentry); /* pin link and directory dentries in core */ 205 return error; 206 } 207 208 /* 209 * Get the name for corresponding element represented by the given configfs_dirent 210 */ 211 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 212 { 213 struct configfs_attribute *attr; 214 215 BUG_ON(!sd || !sd->s_element); 216 217 /* These always have a dentry, so use that */ 218 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 219 return sd->s_dentry->d_name.name; 220 221 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 222 attr = sd->s_element; 223 return attr->ca_name; 224 } 225 return NULL; 226 } 227 228 229 /* 230 * Unhashes the dentry corresponding to given configfs_dirent 231 * Called with parent inode's i_mutex held. 232 */ 233 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 234 { 235 struct dentry * dentry = sd->s_dentry; 236 237 if (dentry) { 238 spin_lock(&dentry->d_lock); 239 if (!d_unhashed(dentry) && d_really_is_positive(dentry)) { 240 dget_dlock(dentry); 241 __d_drop(dentry); 242 spin_unlock(&dentry->d_lock); 243 simple_unlink(d_inode(parent), dentry); 244 } else 245 spin_unlock(&dentry->d_lock); 246 } 247 } 248 249 void configfs_hash_and_remove(struct dentry * dir, const char * name) 250 { 251 struct configfs_dirent * sd; 252 struct configfs_dirent * parent_sd = dir->d_fsdata; 253 254 if (d_really_is_negative(dir)) 255 /* no inode means this hasn't been made visible yet */ 256 return; 257 258 mutex_lock(&d_inode(dir)->i_mutex); 259 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 260 if (!sd->s_element) 261 continue; 262 if (!strcmp(configfs_get_name(sd), name)) { 263 spin_lock(&configfs_dirent_lock); 264 list_del_init(&sd->s_sibling); 265 spin_unlock(&configfs_dirent_lock); 266 configfs_drop_dentry(sd, dir); 267 configfs_put(sd); 268 break; 269 } 270 } 271 mutex_unlock(&d_inode(dir)->i_mutex); 272 } 273