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/xattr.h>
23 #include <linux/security.h>
26 extern struct super_block * sysfs_sb;
28 static const struct address_space_operations sysfs_aops = {
29 .readpage = simple_readpage,
30 .write_begin = simple_write_begin,
31 .write_end = simple_write_end,
34 static struct backing_dev_info sysfs_backing_dev_info = {
36 .ra_pages = 0, /* No readahead */
37 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
40 static const struct inode_operations sysfs_inode_operations ={
41 .permission = sysfs_permission,
42 .setattr = sysfs_setattr,
43 .getattr = sysfs_getattr,
44 .setxattr = sysfs_setxattr,
47 int __init sysfs_inode_init(void)
49 return bdi_init(&sysfs_backing_dev_info);
52 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
54 struct sysfs_inode_attrs *attrs;
57 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
60 iattrs = &attrs->ia_iattr;
62 /* assign default attributes */
63 iattrs->ia_mode = sd->s_mode;
66 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
71 int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
73 struct sysfs_inode_attrs *sd_attrs;
75 unsigned int ia_valid = iattr->ia_valid;
77 sd_attrs = sd->s_iattr;
80 /* setting attributes for the first time, allocate now */
81 sd_attrs = sysfs_init_inode_attrs(sd);
84 sd->s_iattr = sd_attrs;
86 /* attributes were changed at least once in past */
87 iattrs = &sd_attrs->ia_iattr;
89 if (ia_valid & ATTR_UID)
90 iattrs->ia_uid = iattr->ia_uid;
91 if (ia_valid & ATTR_GID)
92 iattrs->ia_gid = iattr->ia_gid;
93 if (ia_valid & ATTR_ATIME)
94 iattrs->ia_atime = iattr->ia_atime;
95 if (ia_valid & ATTR_MTIME)
96 iattrs->ia_mtime = iattr->ia_mtime;
97 if (ia_valid & ATTR_CTIME)
98 iattrs->ia_ctime = iattr->ia_ctime;
99 if (ia_valid & ATTR_MODE) {
100 umode_t mode = iattr->ia_mode;
101 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 mutex_lock(&sysfs_mutex);
116 error = inode_change_ok(inode, iattr);
120 /* this ignores size changes */
121 generic_setattr(inode, iattr);
123 error = sysfs_sd_setattr(sd, iattr);
126 mutex_unlock(&sysfs_mutex);
130 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)
132 struct sysfs_inode_attrs *iattrs;
134 size_t old_secdata_len;
136 iattrs = sd->s_iattr;
138 iattrs = sysfs_init_inode_attrs(sd);
142 old_secdata = iattrs->ia_secdata;
143 old_secdata_len = iattrs->ia_secdata_len;
145 iattrs->ia_secdata = *secdata;
146 iattrs->ia_secdata_len = *secdata_len;
148 *secdata = old_secdata;
149 *secdata_len = old_secdata_len;
153 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
154 size_t size, int flags)
156 struct sysfs_dirent *sd = dentry->d_fsdata;
164 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
165 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
166 error = security_inode_setsecurity(dentry->d_inode, suffix,
170 error = security_inode_getsecctx(dentry->d_inode,
171 &secdata, &secdata_len);
175 mutex_lock(&sysfs_mutex);
176 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
177 mutex_unlock(&sysfs_mutex);
180 security_release_secctx(secdata, secdata_len);
187 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
189 inode->i_mode = mode;
190 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
193 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
195 inode->i_uid = iattr->ia_uid;
196 inode->i_gid = iattr->ia_gid;
197 inode->i_atime = iattr->ia_atime;
198 inode->i_mtime = iattr->ia_mtime;
199 inode->i_ctime = iattr->ia_ctime;
202 static int sysfs_count_nlink(struct sysfs_dirent *sd)
204 struct sysfs_dirent *child;
207 for (child = sd->s_dir.children; child; child = child->s_sibling)
208 if (sysfs_type(child) == SYSFS_DIR)
214 static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
216 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
218 inode->i_mode = sd->s_mode;
220 /* sysfs_dirent has non-default attributes
221 * get them from persistent copy in sysfs_dirent
223 set_inode_attr(inode, &iattrs->ia_iattr);
224 security_inode_notifysecctx(inode,
226 iattrs->ia_secdata_len);
229 if (sysfs_type(sd) == SYSFS_DIR)
230 inode->i_nlink = sysfs_count_nlink(sd);
233 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
235 struct sysfs_dirent *sd = dentry->d_fsdata;
236 struct inode *inode = dentry->d_inode;
238 mutex_lock(&sysfs_mutex);
239 sysfs_refresh_inode(sd, inode);
240 mutex_unlock(&sysfs_mutex);
242 generic_fillattr(inode, stat);
246 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
248 struct bin_attribute *bin_attr;
250 inode->i_private = sysfs_get(sd);
251 inode->i_mapping->a_ops = &sysfs_aops;
252 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
253 inode->i_op = &sysfs_inode_operations;
255 set_default_inode_attr(inode, sd->s_mode);
256 sysfs_refresh_inode(sd, inode);
258 /* initialize inode according to type */
259 switch (sysfs_type(sd)) {
261 inode->i_op = &sysfs_dir_inode_operations;
262 inode->i_fop = &sysfs_dir_operations;
264 case SYSFS_KOBJ_ATTR:
265 inode->i_size = PAGE_SIZE;
266 inode->i_fop = &sysfs_file_operations;
268 case SYSFS_KOBJ_BIN_ATTR:
269 bin_attr = sd->s_bin_attr.bin_attr;
270 inode->i_size = bin_attr->size;
271 inode->i_fop = &bin_fops;
273 case SYSFS_KOBJ_LINK:
274 inode->i_op = &sysfs_symlink_inode_operations;
280 unlock_new_inode(inode);
284 * sysfs_get_inode - get inode for sysfs_dirent
286 * @sd: sysfs_dirent to allocate inode for
288 * Get inode for @sd. If such inode doesn't exist, a new inode
289 * is allocated and basics are initialized. New inode is
293 * Kernel thread context (may sleep).
296 * Pointer to allocated inode on success, NULL on failure.
298 struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
302 inode = iget_locked(sb, sd->s_ino);
303 if (inode && (inode->i_state & I_NEW))
304 sysfs_init_inode(sd, inode);
310 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
311 * To prevent the sysfs inode numbers from being freed prematurely we take a
312 * reference to sysfs_dirent from the sysfs inode. A
313 * super_operations.delete_inode() implementation is needed to drop that
314 * reference upon inode destruction.
316 void sysfs_delete_inode(struct inode *inode)
318 struct sysfs_dirent *sd = inode->i_private;
320 truncate_inode_pages(&inode->i_data, 0);
325 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const void *ns, const char *name)
327 struct sysfs_addrm_cxt acxt;
328 struct sysfs_dirent *sd;
333 sysfs_addrm_start(&acxt, dir_sd);
335 sd = sysfs_find_dirent(dir_sd, ns, name);
336 if (sd && (sd->s_ns != ns))
339 sysfs_remove_one(&acxt, sd);
341 sysfs_addrm_finish(&acxt);
349 int sysfs_permission(struct inode *inode, int mask)
351 struct sysfs_dirent *sd = inode->i_private;
353 mutex_lock(&sysfs_mutex);
354 sysfs_refresh_inode(sd, inode);
355 mutex_unlock(&sysfs_mutex);
357 return generic_permission(inode, mask, NULL);