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 37 #include <linux/configfs.h> 38 #include "configfs_internal.h" 39 40 extern struct super_block * configfs_sb; 41 42 static const struct address_space_operations configfs_aops = { 43 .readpage = simple_readpage, 44 .write_begin = simple_write_begin, 45 .write_end = simple_write_end, 46 }; 47 48 static struct backing_dev_info configfs_backing_dev_info = { 49 .ra_pages = 0, /* No readahead */ 50 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, 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 = dentry->d_inode; 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 70 error = inode_change_ok(inode, iattr); 71 if (error) 72 return error; 73 74 error = inode_setattr(inode, iattr); 75 if (error) 76 return error; 77 78 if (!sd_iattr) { 79 /* setting attributes for the first time, allocate now */ 80 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 81 if (!sd_iattr) 82 return -ENOMEM; 83 /* assign default attributes */ 84 sd_iattr->ia_mode = sd->s_mode; 85 sd_iattr->ia_uid = 0; 86 sd_iattr->ia_gid = 0; 87 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 88 sd->s_iattr = sd_iattr; 89 } 90 91 /* attributes were changed atleast once in past */ 92 93 if (ia_valid & ATTR_UID) 94 sd_iattr->ia_uid = iattr->ia_uid; 95 if (ia_valid & ATTR_GID) 96 sd_iattr->ia_gid = iattr->ia_gid; 97 if (ia_valid & ATTR_ATIME) 98 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 99 inode->i_sb->s_time_gran); 100 if (ia_valid & ATTR_MTIME) 101 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 102 inode->i_sb->s_time_gran); 103 if (ia_valid & ATTR_CTIME) 104 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 105 inode->i_sb->s_time_gran); 106 if (ia_valid & ATTR_MODE) { 107 umode_t mode = iattr->ia_mode; 108 109 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 110 mode &= ~S_ISGID; 111 sd_iattr->ia_mode = sd->s_mode = mode; 112 } 113 114 return error; 115 } 116 117 static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 118 { 119 inode->i_mode = mode; 120 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 121 } 122 123 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 124 { 125 inode->i_mode = iattr->ia_mode; 126 inode->i_uid = iattr->ia_uid; 127 inode->i_gid = iattr->ia_gid; 128 inode->i_atime = iattr->ia_atime; 129 inode->i_mtime = iattr->ia_mtime; 130 inode->i_ctime = iattr->ia_ctime; 131 } 132 133 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd) 134 { 135 struct inode * inode = new_inode(configfs_sb); 136 if (inode) { 137 inode->i_mapping->a_ops = &configfs_aops; 138 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info; 139 inode->i_op = &configfs_inode_operations; 140 141 if (sd->s_iattr) { 142 /* sysfs_dirent has non-default attributes 143 * get them for the new inode from persistent copy 144 * in sysfs_dirent 145 */ 146 set_inode_attr(inode, sd->s_iattr); 147 } else 148 set_default_inode_attr(inode, mode); 149 } 150 return inode; 151 } 152 153 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) 154 { 155 int error = 0; 156 struct inode * inode = NULL; 157 if (dentry) { 158 if (!dentry->d_inode) { 159 struct configfs_dirent *sd = dentry->d_fsdata; 160 if ((inode = configfs_new_inode(mode, sd))) { 161 if (dentry->d_parent && dentry->d_parent->d_inode) { 162 struct inode *p_inode = dentry->d_parent->d_inode; 163 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 164 } 165 goto Proceed; 166 } 167 else 168 error = -ENOMEM; 169 } else 170 error = -EEXIST; 171 } else 172 error = -ENOENT; 173 goto Done; 174 175 Proceed: 176 if (init) 177 error = init(inode); 178 if (!error) { 179 d_instantiate(dentry, inode); 180 if (S_ISDIR(mode) || S_ISLNK(mode)) 181 dget(dentry); /* pin link and directory dentries in core */ 182 } else 183 iput(inode); 184 Done: 185 return error; 186 } 187 188 /* 189 * Get the name for corresponding element represented by the given configfs_dirent 190 */ 191 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 192 { 193 struct configfs_attribute *attr; 194 195 BUG_ON(!sd || !sd->s_element); 196 197 /* These always have a dentry, so use that */ 198 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 199 return sd->s_dentry->d_name.name; 200 201 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 202 attr = sd->s_element; 203 return attr->ca_name; 204 } 205 return NULL; 206 } 207 208 209 /* 210 * Unhashes the dentry corresponding to given configfs_dirent 211 * Called with parent inode's i_mutex held. 212 */ 213 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 214 { 215 struct dentry * dentry = sd->s_dentry; 216 217 if (dentry) { 218 spin_lock(&dcache_lock); 219 spin_lock(&dentry->d_lock); 220 if (!(d_unhashed(dentry) && dentry->d_inode)) { 221 dget_locked(dentry); 222 __d_drop(dentry); 223 spin_unlock(&dentry->d_lock); 224 spin_unlock(&dcache_lock); 225 simple_unlink(parent->d_inode, dentry); 226 } else { 227 spin_unlock(&dentry->d_lock); 228 spin_unlock(&dcache_lock); 229 } 230 } 231 } 232 233 void configfs_hash_and_remove(struct dentry * dir, const char * name) 234 { 235 struct configfs_dirent * sd; 236 struct configfs_dirent * parent_sd = dir->d_fsdata; 237 238 if (dir->d_inode == NULL) 239 /* no inode means this hasn't been made visible yet */ 240 return; 241 242 mutex_lock(&dir->d_inode->i_mutex); 243 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 244 if (!sd->s_element) 245 continue; 246 if (!strcmp(configfs_get_name(sd), name)) { 247 spin_lock(&configfs_dirent_lock); 248 list_del_init(&sd->s_sibling); 249 spin_unlock(&configfs_dirent_lock); 250 configfs_drop_dentry(sd, dir); 251 configfs_put(sd); 252 break; 253 } 254 } 255 mutex_unlock(&dir->d_inode->i_mutex); 256 } 257 258 int __init configfs_inode_init(void) 259 { 260 return bdi_init(&configfs_backing_dev_info); 261 } 262 263 void __exit configfs_inode_exit(void) 264 { 265 bdi_destroy(&configfs_backing_dev_info); 266 } 267