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/xattr.h>
22 #include <linux/security.h>
25 extern struct super_block * sysfs_sb;
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;
65 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
70 int sysfs_sd_setattr(struct sysfs_dirent *sd, 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 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
108 struct inode *inode = dentry->d_inode;
109 struct sysfs_dirent *sd = dentry->d_fsdata;
115 error = inode_change_ok(inode, iattr);
119 iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
120 if (iattr->ia_valid & ATTR_MODE) {
121 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
122 iattr->ia_mode &= ~S_ISGID;
125 error = inode_setattr(inode, iattr);
129 mutex_lock(&sysfs_mutex);
130 error = sysfs_sd_setattr(sd, iattr);
131 mutex_unlock(&sysfs_mutex);
136 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)
138 struct sysfs_inode_attrs *iattrs;
140 size_t old_secdata_len;
142 iattrs = sd->s_iattr;
144 iattrs = sysfs_init_inode_attrs(sd);
148 old_secdata = iattrs->ia_secdata;
149 old_secdata_len = iattrs->ia_secdata_len;
151 iattrs->ia_secdata = *secdata;
152 iattrs->ia_secdata_len = *secdata_len;
154 *secdata = old_secdata;
155 *secdata_len = old_secdata_len;
159 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
160 size_t size, int flags)
162 struct sysfs_dirent *sd = dentry->d_fsdata;
170 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
171 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
172 error = security_inode_setsecurity(dentry->d_inode, suffix,
176 error = security_inode_getsecctx(dentry->d_inode,
177 &secdata, &secdata_len);
181 mutex_lock(&sysfs_mutex);
182 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
183 mutex_unlock(&sysfs_mutex);
186 security_release_secctx(secdata, secdata_len);
193 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
195 inode->i_mode = mode;
196 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
199 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
201 inode->i_uid = iattr->ia_uid;
202 inode->i_gid = iattr->ia_gid;
203 inode->i_atime = iattr->ia_atime;
204 inode->i_mtime = iattr->ia_mtime;
205 inode->i_ctime = iattr->ia_ctime;
210 * sysfs has a different i_mutex lock order behavior for i_mutex than other
211 * filesystems; sysfs i_mutex is called in many places with subsystem locks
212 * held. At the same time, many of the VFS locking rules do not apply to
213 * sysfs at all (cross directory rename for example). To untangle this mess
214 * (which gives false positives in lockdep), we're giving sysfs inodes their
215 * own class for i_mutex.
217 static struct lock_class_key sysfs_inode_imutex_key;
219 static int sysfs_count_nlink(struct sysfs_dirent *sd)
221 struct sysfs_dirent *child;
224 for (child = sd->s_dir.children; child; child = child->s_sibling)
225 if (sysfs_type(child) == SYSFS_DIR)
231 static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
233 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
235 inode->i_mode = sd->s_mode;
237 /* sysfs_dirent has non-default attributes
238 * get them from persistent copy in sysfs_dirent
240 set_inode_attr(inode, &iattrs->ia_iattr);
241 security_inode_notifysecctx(inode,
243 iattrs->ia_secdata_len);
246 if (sysfs_type(sd) == SYSFS_DIR)
247 inode->i_nlink = sysfs_count_nlink(sd);
250 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
252 struct sysfs_dirent *sd = dentry->d_fsdata;
253 struct inode *inode = dentry->d_inode;
255 mutex_lock(&sysfs_mutex);
256 sysfs_refresh_inode(sd, inode);
257 mutex_unlock(&sysfs_mutex);
259 generic_fillattr(inode, stat);
263 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
265 struct bin_attribute *bin_attr;
267 inode->i_private = sysfs_get(sd);
268 inode->i_mapping->a_ops = &sysfs_aops;
269 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
270 inode->i_op = &sysfs_inode_operations;
271 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
273 set_default_inode_attr(inode, sd->s_mode);
274 sysfs_refresh_inode(sd, inode);
276 /* initialize inode according to type */
277 switch (sysfs_type(sd)) {
279 inode->i_op = &sysfs_dir_inode_operations;
280 inode->i_fop = &sysfs_dir_operations;
282 case SYSFS_KOBJ_ATTR:
283 inode->i_size = PAGE_SIZE;
284 inode->i_fop = &sysfs_file_operations;
286 case SYSFS_KOBJ_BIN_ATTR:
287 bin_attr = sd->s_bin_attr.bin_attr;
288 inode->i_size = bin_attr->size;
289 inode->i_fop = &bin_fops;
291 case SYSFS_KOBJ_LINK:
292 inode->i_op = &sysfs_symlink_inode_operations;
298 unlock_new_inode(inode);
302 * sysfs_get_inode - get inode for sysfs_dirent
303 * @sd: sysfs_dirent to allocate inode for
305 * Get inode for @sd. If such inode doesn't exist, a new inode
306 * is allocated and basics are initialized. New inode is
310 * Kernel thread context (may sleep).
313 * Pointer to allocated inode on success, NULL on failure.
315 struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
319 inode = iget_locked(sysfs_sb, sd->s_ino);
320 if (inode && (inode->i_state & I_NEW))
321 sysfs_init_inode(sd, inode);
327 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
328 * To prevent the sysfs inode numbers from being freed prematurely we take a
329 * reference to sysfs_dirent from the sysfs inode. A
330 * super_operations.delete_inode() implementation is needed to drop that
331 * reference upon inode destruction.
333 void sysfs_delete_inode(struct inode *inode)
335 struct sysfs_dirent *sd = inode->i_private;
337 truncate_inode_pages(&inode->i_data, 0);
342 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
344 struct sysfs_addrm_cxt acxt;
345 struct sysfs_dirent *sd;
350 sysfs_addrm_start(&acxt, dir_sd);
352 sd = sysfs_find_dirent(dir_sd, name);
354 sysfs_remove_one(&acxt, sd);
356 sysfs_addrm_finish(&acxt);
364 int sysfs_permission(struct inode *inode, int mask)
366 struct sysfs_dirent *sd = inode->i_private;
368 mutex_lock(&sysfs_mutex);
369 sysfs_refresh_inode(sd, inode);
370 mutex_unlock(&sysfs_mutex);
372 return generic_permission(inode, mask, NULL);