2 * fs/sysfs/inode.c - basic sysfs inode and dentry operations
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 * This file is released under the GPLv2.
10 * Please see Documentation/filesystems/sysfs.txt for more information.
15 #include <linux/pagemap.h>
16 #include <linux/namei.h>
17 #include <linux/backing-dev.h>
18 #include <linux/capability.h>
19 #include <linux/errno.h>
20 #include <linux/sched.h>
21 #include <linux/slab.h>
22 #include <linux/sysfs.h>
23 #include <linux/xattr.h>
24 #include <linux/security.h>
27 static const struct address_space_operations sysfs_aops = {
28 .readpage = simple_readpage,
29 .write_begin = simple_write_begin,
30 .write_end = simple_write_end,
33 static struct backing_dev_info sysfs_backing_dev_info = {
35 .ra_pages = 0, /* No readahead */
36 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
39 static const struct inode_operations sysfs_inode_operations = {
40 .permission = sysfs_permission,
41 .setattr = sysfs_setattr,
42 .getattr = sysfs_getattr,
43 .setxattr = sysfs_setxattr,
46 int __init sysfs_inode_init(void)
48 return bdi_init(&sysfs_backing_dev_info);
51 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
53 struct sysfs_inode_attrs *attrs;
56 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
59 iattrs = &attrs->ia_iattr;
61 /* assign default attributes */
62 iattrs->ia_mode = sd->s_mode;
63 iattrs->ia_uid = GLOBAL_ROOT_UID;
64 iattrs->ia_gid = GLOBAL_ROOT_GID;
65 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
70 static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
72 struct sysfs_inode_attrs *sd_attrs;
74 unsigned int ia_valid = iattr->ia_valid;
76 sd_attrs = sd->s_iattr;
79 /* setting attributes for the first time, allocate now */
80 sd_attrs = sysfs_init_inode_attrs(sd);
83 sd->s_iattr = sd_attrs;
85 /* attributes were changed at least once in past */
86 iattrs = &sd_attrs->ia_iattr;
88 if (ia_valid & ATTR_UID)
89 iattrs->ia_uid = iattr->ia_uid;
90 if (ia_valid & ATTR_GID)
91 iattrs->ia_gid = iattr->ia_gid;
92 if (ia_valid & ATTR_ATIME)
93 iattrs->ia_atime = iattr->ia_atime;
94 if (ia_valid & ATTR_MTIME)
95 iattrs->ia_mtime = iattr->ia_mtime;
96 if (ia_valid & ATTR_CTIME)
97 iattrs->ia_ctime = iattr->ia_ctime;
98 if (ia_valid & ATTR_MODE) {
99 umode_t mode = iattr->ia_mode;
100 iattrs->ia_mode = sd->s_mode = mode;
106 * kernfs_setattr - set iattr on a node
108 * @iattr: iattr to set
110 * Returns 0 on success, -errno on failure.
112 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
116 mutex_lock(&sysfs_mutex);
117 ret = __kernfs_setattr(sd, iattr);
118 mutex_unlock(&sysfs_mutex);
122 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
124 struct inode *inode = dentry->d_inode;
125 struct sysfs_dirent *sd = dentry->d_fsdata;
131 mutex_lock(&sysfs_mutex);
132 error = inode_change_ok(inode, iattr);
136 error = __kernfs_setattr(sd, iattr);
140 /* this ignores size changes */
141 setattr_copy(inode, iattr);
144 mutex_unlock(&sysfs_mutex);
148 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
151 struct sysfs_inode_attrs *iattrs;
153 size_t old_secdata_len;
156 sd->s_iattr = sysfs_init_inode_attrs(sd);
161 iattrs = sd->s_iattr;
162 old_secdata = iattrs->ia_secdata;
163 old_secdata_len = iattrs->ia_secdata_len;
165 iattrs->ia_secdata = *secdata;
166 iattrs->ia_secdata_len = *secdata_len;
168 *secdata = old_secdata;
169 *secdata_len = old_secdata_len;
173 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
174 size_t size, int flags)
176 struct sysfs_dirent *sd = dentry->d_fsdata;
184 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
185 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
186 error = security_inode_setsecurity(dentry->d_inode, suffix,
190 error = security_inode_getsecctx(dentry->d_inode,
191 &secdata, &secdata_len);
195 mutex_lock(&sysfs_mutex);
196 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
197 mutex_unlock(&sysfs_mutex);
200 security_release_secctx(secdata, secdata_len);
207 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
209 inode->i_mode = mode;
210 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
213 static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
215 inode->i_uid = iattr->ia_uid;
216 inode->i_gid = iattr->ia_gid;
217 inode->i_atime = iattr->ia_atime;
218 inode->i_mtime = iattr->ia_mtime;
219 inode->i_ctime = iattr->ia_ctime;
222 static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
224 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
226 inode->i_mode = sd->s_mode;
228 /* sysfs_dirent has non-default attributes
229 * get them from persistent copy in sysfs_dirent
231 set_inode_attr(inode, &iattrs->ia_iattr);
232 security_inode_notifysecctx(inode,
234 iattrs->ia_secdata_len);
237 if (sysfs_type(sd) == SYSFS_DIR)
238 set_nlink(inode, sd->s_dir.subdirs + 2);
241 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
244 struct sysfs_dirent *sd = dentry->d_fsdata;
245 struct inode *inode = dentry->d_inode;
247 mutex_lock(&sysfs_mutex);
248 sysfs_refresh_inode(sd, inode);
249 mutex_unlock(&sysfs_mutex);
251 generic_fillattr(inode, stat);
255 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
258 inode->i_private = sd;
259 inode->i_mapping->a_ops = &sysfs_aops;
260 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
261 inode->i_op = &sysfs_inode_operations;
263 set_default_inode_attr(inode, sd->s_mode);
264 sysfs_refresh_inode(sd, inode);
266 /* initialize inode according to type */
267 switch (sysfs_type(sd)) {
269 inode->i_op = &sysfs_dir_inode_operations;
270 inode->i_fop = &sysfs_dir_operations;
272 case SYSFS_KOBJ_ATTR:
273 inode->i_size = sd->s_attr.size;
274 inode->i_fop = &kernfs_file_operations;
276 case SYSFS_KOBJ_LINK:
277 inode->i_op = &sysfs_symlink_inode_operations;
283 unlock_new_inode(inode);
287 * sysfs_get_inode - get inode for sysfs_dirent
289 * @sd: sysfs_dirent to allocate inode for
291 * Get inode for @sd. If such inode doesn't exist, a new inode
292 * is allocated and basics are initialized. New inode is
296 * Kernel thread context (may sleep).
299 * Pointer to allocated inode on success, NULL on failure.
301 struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
305 inode = iget_locked(sb, sd->s_ino);
306 if (inode && (inode->i_state & I_NEW))
307 sysfs_init_inode(sd, inode);
313 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
314 * To prevent the sysfs inode numbers from being freed prematurely we take a
315 * reference to sysfs_dirent from the sysfs inode. A
316 * super_operations.evict_inode() implementation is needed to drop that
317 * reference upon inode destruction.
319 void sysfs_evict_inode(struct inode *inode)
321 struct sysfs_dirent *sd = inode->i_private;
323 truncate_inode_pages(&inode->i_data, 0);
328 int sysfs_permission(struct inode *inode, int mask)
330 struct sysfs_dirent *sd;
332 if (mask & MAY_NOT_BLOCK)
335 sd = inode->i_private;
337 mutex_lock(&sysfs_mutex);
338 sysfs_refresh_inode(sd, inode);
339 mutex_unlock(&sysfs_mutex);
341 return generic_permission(inode, mask);