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 36 #include <linux/configfs.h> 37 #include "configfs_internal.h" 38 39 extern struct super_block * configfs_sb; 40 41 static const struct address_space_operations configfs_aops = { 42 .readpage = simple_readpage, 43 .prepare_write = simple_prepare_write, 44 .commit_write = simple_commit_write 45 }; 46 47 static struct backing_dev_info configfs_backing_dev_info = { 48 .ra_pages = 0, /* No readahead */ 49 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 50 }; 51 52 static const struct inode_operations configfs_inode_operations ={ 53 .setattr = configfs_setattr, 54 }; 55 56 int configfs_setattr(struct dentry * dentry, struct iattr * iattr) 57 { 58 struct inode * inode = dentry->d_inode; 59 struct configfs_dirent * sd = dentry->d_fsdata; 60 struct iattr * sd_iattr; 61 unsigned int ia_valid = iattr->ia_valid; 62 int error; 63 64 if (!sd) 65 return -EINVAL; 66 67 sd_iattr = sd->s_iattr; 68 69 error = inode_change_ok(inode, iattr); 70 if (error) 71 return error; 72 73 error = inode_setattr(inode, iattr); 74 if (error) 75 return error; 76 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 90 /* attributes were changed atleast once in past */ 91 92 if (ia_valid & ATTR_UID) 93 sd_iattr->ia_uid = iattr->ia_uid; 94 if (ia_valid & ATTR_GID) 95 sd_iattr->ia_gid = iattr->ia_gid; 96 if (ia_valid & ATTR_ATIME) 97 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 98 inode->i_sb->s_time_gran); 99 if (ia_valid & ATTR_MTIME) 100 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 101 inode->i_sb->s_time_gran); 102 if (ia_valid & ATTR_CTIME) 103 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 104 inode->i_sb->s_time_gran); 105 if (ia_valid & ATTR_MODE) { 106 umode_t mode = iattr->ia_mode; 107 108 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 109 mode &= ~S_ISGID; 110 sd_iattr->ia_mode = sd->s_mode = mode; 111 } 112 113 return error; 114 } 115 116 static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 117 { 118 inode->i_mode = mode; 119 inode->i_uid = 0; 120 inode->i_gid = 0; 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_blocks = 0; 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 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) 156 { 157 int error = 0; 158 struct inode * inode = NULL; 159 if (dentry) { 160 if (!dentry->d_inode) { 161 struct configfs_dirent *sd = dentry->d_fsdata; 162 if ((inode = configfs_new_inode(mode, sd))) { 163 if (dentry->d_parent && dentry->d_parent->d_inode) { 164 struct inode *p_inode = dentry->d_parent->d_inode; 165 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 166 } 167 goto Proceed; 168 } 169 else 170 error = -ENOMEM; 171 } else 172 error = -EEXIST; 173 } else 174 error = -ENOENT; 175 goto Done; 176 177 Proceed: 178 if (init) 179 error = init(inode); 180 if (!error) { 181 d_instantiate(dentry, inode); 182 if (S_ISDIR(mode) || S_ISLNK(mode)) 183 dget(dentry); /* pin link and directory dentries in core */ 184 } else 185 iput(inode); 186 Done: 187 return error; 188 } 189 190 /* 191 * Get the name for corresponding element represented by the given configfs_dirent 192 */ 193 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 194 { 195 struct configfs_attribute *attr; 196 197 BUG_ON(!sd || !sd->s_element); 198 199 /* These always have a dentry, so use that */ 200 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 201 return sd->s_dentry->d_name.name; 202 203 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 204 attr = sd->s_element; 205 return attr->ca_name; 206 } 207 return NULL; 208 } 209 210 211 /* 212 * Unhashes the dentry corresponding to given configfs_dirent 213 * Called with parent inode's i_mutex held. 214 */ 215 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 216 { 217 struct dentry * dentry = sd->s_dentry; 218 219 if (dentry) { 220 spin_lock(&dcache_lock); 221 spin_lock(&dentry->d_lock); 222 if (!(d_unhashed(dentry) && dentry->d_inode)) { 223 dget_locked(dentry); 224 __d_drop(dentry); 225 spin_unlock(&dentry->d_lock); 226 spin_unlock(&dcache_lock); 227 simple_unlink(parent->d_inode, dentry); 228 } else { 229 spin_unlock(&dentry->d_lock); 230 spin_unlock(&dcache_lock); 231 } 232 } 233 } 234 235 void configfs_hash_and_remove(struct dentry * dir, const char * name) 236 { 237 struct configfs_dirent * sd; 238 struct configfs_dirent * parent_sd = dir->d_fsdata; 239 240 if (dir->d_inode == NULL) 241 /* no inode means this hasn't been made visible yet */ 242 return; 243 244 mutex_lock(&dir->d_inode->i_mutex); 245 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 246 if (!sd->s_element) 247 continue; 248 if (!strcmp(configfs_get_name(sd), name)) { 249 list_del_init(&sd->s_sibling); 250 configfs_drop_dentry(sd, dir); 251 configfs_put(sd); 252 break; 253 } 254 } 255 mutex_unlock(&dir->d_inode->i_mutex); 256 } 257 258 259