1/* 2 * inode.c - basic inode and dentry operations. 3 * 4 * sysfs is Copyright (c) 2001-3 Patrick Mochel 5 * 6 * Please see Documentation/filesystems/sysfs.txt for more information. 7 */ 8 9#undef DEBUG 10 11#include <linux/pagemap.h> 12#include <linux/namei.h> 13#include <linux/backing-dev.h> 14#include <linux/capability.h> 15#include <linux/errno.h> 16#include <linux/sched.h> 17#include <asm/semaphore.h> 18#include "sysfs.h" 19 20extern struct super_block * sysfs_sb; 21 22static const struct address_space_operations sysfs_aops = { 23 .readpage = simple_readpage, 24 .prepare_write = simple_prepare_write, 25 .commit_write = simple_commit_write 26}; 27 28static struct backing_dev_info sysfs_backing_dev_info = { 29 .ra_pages = 0, /* No readahead */ 30 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 31}; 32 33static const struct inode_operations sysfs_inode_operations ={ 34 .setattr = sysfs_setattr, 35}; 36 37void sysfs_delete_inode(struct inode *inode) 38{ 39 /* Free the shadowed directory inode operations */ 40 if (sysfs_is_shadowed_inode(inode)) { 41 kfree(inode->i_op); 42 inode->i_op = NULL; 43 } 44 return generic_delete_inode(inode); 45} 46 47int sysfs_setattr(struct dentry * dentry, struct iattr * iattr) 48{ 49 struct inode * inode = dentry->d_inode; 50 struct sysfs_dirent * sd = dentry->d_fsdata; 51 struct iattr * sd_iattr; 52 unsigned int ia_valid = iattr->ia_valid; 53 int error; 54 55 if (!sd) 56 return -EINVAL; 57 58 sd_iattr = sd->s_iattr; 59 60 error = inode_change_ok(inode, iattr); 61 if (error) 62 return error; 63 64 error = inode_setattr(inode, iattr); 65 if (error) 66 return error; 67 68 if (!sd_iattr) { 69 /* setting attributes for the first time, allocate now */ 70 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 71 if (!sd_iattr) 72 return -ENOMEM; 73 /* assign default attributes */ 74 sd_iattr->ia_mode = sd->s_mode; 75 sd_iattr->ia_uid = 0; 76 sd_iattr->ia_gid = 0; 77 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 78 sd->s_iattr = sd_iattr; 79 } 80 81 /* attributes were changed atleast once in past */ 82 83 if (ia_valid & ATTR_UID) 84 sd_iattr->ia_uid = iattr->ia_uid; 85 if (ia_valid & ATTR_GID) 86 sd_iattr->ia_gid = iattr->ia_gid; 87 if (ia_valid & ATTR_ATIME) 88 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 89 inode->i_sb->s_time_gran); 90 if (ia_valid & ATTR_MTIME) 91 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 92 inode->i_sb->s_time_gran); 93 if (ia_valid & ATTR_CTIME) 94 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 95 inode->i_sb->s_time_gran); 96 if (ia_valid & ATTR_MODE) { 97 umode_t mode = iattr->ia_mode; 98 99 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 100 mode &= ~S_ISGID; 101 sd_iattr->ia_mode = sd->s_mode = mode; 102 } 103 104 return error; 105} 106 107static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 108{ 109 inode->i_mode = mode; 110 inode->i_uid = 0; 111 inode->i_gid = 0; 112 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 113} 114 115static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 116{ 117 inode->i_mode = iattr->ia_mode; 118 inode->i_uid = iattr->ia_uid; 119 inode->i_gid = iattr->ia_gid; 120 inode->i_atime = iattr->ia_atime; 121 inode->i_mtime = iattr->ia_mtime; 122 inode->i_ctime = iattr->ia_ctime; 123} 124 125 126/* 127 * sysfs has a different i_mutex lock order behavior for i_mutex than other 128 * filesystems; sysfs i_mutex is called in many places with subsystem locks 129 * held. At the same time, many of the VFS locking rules do not apply to 130 * sysfs at all (cross directory rename for example). To untangle this mess 131 * (which gives false positives in lockdep), we're giving sysfs inodes their 132 * own class for i_mutex. 133 */ 134static struct lock_class_key sysfs_inode_imutex_key; 135 136struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd) 137{ 138 struct inode * inode = new_inode(sysfs_sb); 139 if (inode) { 140 inode->i_blocks = 0; 141 inode->i_mapping->a_ops = &sysfs_aops; 142 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info; 143 inode->i_op = &sysfs_inode_operations; 144 inode->i_ino = sd->s_ino; 145 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key); 146 147 if (sd->s_iattr) { 148 /* sysfs_dirent has non-default attributes 149 * get them for the new inode from persistent copy 150 * in sysfs_dirent 151 */ 152 set_inode_attr(inode, sd->s_iattr); 153 } else 154 set_default_inode_attr(inode, mode); 155 } 156 return inode; 157} 158 159int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) 160{ 161 int error = 0; 162 struct inode * inode = NULL; 163 if (dentry) { 164 if (!dentry->d_inode) { 165 struct sysfs_dirent * sd = dentry->d_fsdata; 166 if ((inode = sysfs_new_inode(mode, sd))) { 167 if (dentry->d_parent && dentry->d_parent->d_inode) { 168 struct inode *p_inode = dentry->d_parent->d_inode; 169 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 170 } 171 goto Proceed; 172 } 173 else 174 error = -ENOMEM; 175 } else 176 error = -EEXIST; 177 } else 178 error = -ENOENT; 179 goto Done; 180 181 Proceed: 182 if (init) 183 error = init(inode); 184 if (!error) { 185 d_instantiate(dentry, inode); 186 if (S_ISDIR(mode)) 187 dget(dentry); /* pin only directory dentry in core */ 188 } else 189 iput(inode); 190 Done: 191 return error; 192} 193 194/* 195 * Get the name for corresponding element represented by the given sysfs_dirent 196 */ 197const unsigned char * sysfs_get_name(struct sysfs_dirent *sd) 198{ 199 struct attribute * attr; 200 struct bin_attribute * bin_attr; 201 struct sysfs_symlink * sl; 202 203 BUG_ON(!sd || !sd->s_element); 204 205 switch (sd->s_type) { 206 case SYSFS_DIR: 207 /* Always have a dentry so use that */ 208 return sd->s_dentry->d_name.name; 209 210 case SYSFS_KOBJ_ATTR: 211 attr = sd->s_element; 212 return attr->name; 213 214 case SYSFS_KOBJ_BIN_ATTR: 215 bin_attr = sd->s_element; 216 return bin_attr->attr.name; 217 218 case SYSFS_KOBJ_LINK: 219 sl = sd->s_element; 220 return sl->link_name; 221 } 222 return NULL; 223} 224 225static inline void orphan_all_buffers(struct inode *node) 226{ 227 struct sysfs_buffer_collection *set; 228 struct sysfs_buffer *buf; 229 230 mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD); 231 set = node->i_private; 232 if (set) { 233 list_for_each_entry(buf, &set->associates, associates) { 234 down(&buf->sem); 235 buf->orphaned = 1; 236 up(&buf->sem); 237 } 238 } 239 mutex_unlock(&node->i_mutex); 240} 241 242 243/* 244 * Unhashes the dentry corresponding to given sysfs_dirent 245 * Called with parent inode's i_mutex held. 246 */ 247void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent) 248{ 249 struct dentry *dentry = NULL; 250 struct inode *inode; 251 252 /* We're not holding a reference to ->s_dentry dentry but the 253 * field will stay valid as long as sysfs_lock is held. 254 */ 255 spin_lock(&sysfs_lock); 256 spin_lock(&dcache_lock); 257 258 /* dget dentry if it's still alive */ 259 if (sd->s_dentry && sd->s_dentry->d_inode) 260 dentry = dget_locked(sd->s_dentry); 261 262 spin_unlock(&dcache_lock); 263 spin_unlock(&sysfs_lock); 264 265 /* drop dentry */ 266 if (dentry) { 267 spin_lock(&dcache_lock); 268 spin_lock(&dentry->d_lock); 269 if (!d_unhashed(dentry) && dentry->d_inode) { 270 inode = dentry->d_inode; 271 spin_lock(&inode->i_lock); 272 __iget(inode); 273 spin_unlock(&inode->i_lock); 274 dget_locked(dentry); 275 __d_drop(dentry); 276 spin_unlock(&dentry->d_lock); 277 spin_unlock(&dcache_lock); 278 simple_unlink(parent->d_inode, dentry); 279 orphan_all_buffers(inode); 280 iput(inode); 281 } else { 282 spin_unlock(&dentry->d_lock); 283 spin_unlock(&dcache_lock); 284 } 285 286 dput(dentry); 287 } 288} 289 290int sysfs_hash_and_remove(struct dentry * dir, const char * name) 291{ 292 struct sysfs_dirent * sd; 293 struct sysfs_dirent * parent_sd; 294 int found = 0; 295 296 if (!dir) 297 return -ENOENT; 298 299 if (dir->d_inode == NULL) 300 /* no inode means this hasn't been made visible yet */ 301 return -ENOENT; 302 303 parent_sd = dir->d_fsdata; 304 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT); 305 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 306 if (!sd->s_element) 307 continue; 308 if (!strcmp(sysfs_get_name(sd), name)) { 309 list_del_init(&sd->s_sibling); 310 sysfs_drop_dentry(sd, dir); 311 sysfs_put(sd); 312 found = 1; 313 break; 314 } 315 } 316 mutex_unlock(&dir->d_inode->i_mutex); 317 318 return found ? 0 : -ENOENT; 319} 320