2 * fs/kernfs/inode.c - kernfs inode implementation
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
8 * This file is released under the GPLv2.
11 #include <linux/pagemap.h>
12 #include <linux/backing-dev.h>
13 #include <linux/capability.h>
14 #include <linux/errno.h>
15 #include <linux/slab.h>
16 #include <linux/xattr.h>
17 #include <linux/security.h>
19 #include "kernfs-internal.h"
21 static const struct address_space_operations sysfs_aops = {
22 .readpage = simple_readpage,
23 .write_begin = simple_write_begin,
24 .write_end = simple_write_end,
27 static struct backing_dev_info sysfs_backing_dev_info = {
29 .ra_pages = 0, /* No readahead */
30 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
33 static const struct inode_operations sysfs_inode_operations = {
34 .permission = sysfs_permission,
35 .setattr = sysfs_setattr,
36 .getattr = sysfs_getattr,
37 .setxattr = sysfs_setxattr,
40 int __init sysfs_inode_init(void)
42 return bdi_init(&sysfs_backing_dev_info);
45 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
47 struct sysfs_inode_attrs *attrs;
50 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
53 iattrs = &attrs->ia_iattr;
55 /* assign default attributes */
56 iattrs->ia_mode = sd->s_mode;
57 iattrs->ia_uid = GLOBAL_ROOT_UID;
58 iattrs->ia_gid = GLOBAL_ROOT_GID;
59 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
64 static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
66 struct sysfs_inode_attrs *sd_attrs;
68 unsigned int ia_valid = iattr->ia_valid;
70 sd_attrs = sd->s_iattr;
73 /* setting attributes for the first time, allocate now */
74 sd_attrs = sysfs_init_inode_attrs(sd);
77 sd->s_iattr = sd_attrs;
79 /* attributes were changed at least once in past */
80 iattrs = &sd_attrs->ia_iattr;
82 if (ia_valid & ATTR_UID)
83 iattrs->ia_uid = iattr->ia_uid;
84 if (ia_valid & ATTR_GID)
85 iattrs->ia_gid = iattr->ia_gid;
86 if (ia_valid & ATTR_ATIME)
87 iattrs->ia_atime = iattr->ia_atime;
88 if (ia_valid & ATTR_MTIME)
89 iattrs->ia_mtime = iattr->ia_mtime;
90 if (ia_valid & ATTR_CTIME)
91 iattrs->ia_ctime = iattr->ia_ctime;
92 if (ia_valid & ATTR_MODE) {
93 umode_t mode = iattr->ia_mode;
94 iattrs->ia_mode = sd->s_mode = mode;
100 * kernfs_setattr - set iattr on a node
102 * @iattr: iattr to set
104 * Returns 0 on success, -errno on failure.
106 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
110 mutex_lock(&sysfs_mutex);
111 ret = __kernfs_setattr(sd, iattr);
112 mutex_unlock(&sysfs_mutex);
116 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
118 struct inode *inode = dentry->d_inode;
119 struct sysfs_dirent *sd = dentry->d_fsdata;
125 mutex_lock(&sysfs_mutex);
126 error = inode_change_ok(inode, iattr);
130 error = __kernfs_setattr(sd, iattr);
134 /* this ignores size changes */
135 setattr_copy(inode, iattr);
138 mutex_unlock(&sysfs_mutex);
142 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
145 struct sysfs_inode_attrs *iattrs;
147 size_t old_secdata_len;
150 sd->s_iattr = sysfs_init_inode_attrs(sd);
155 iattrs = sd->s_iattr;
156 old_secdata = iattrs->ia_secdata;
157 old_secdata_len = iattrs->ia_secdata_len;
159 iattrs->ia_secdata = *secdata;
160 iattrs->ia_secdata_len = *secdata_len;
162 *secdata = old_secdata;
163 *secdata_len = old_secdata_len;
167 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
168 size_t size, int flags)
170 struct sysfs_dirent *sd = dentry->d_fsdata;
178 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
179 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
180 error = security_inode_setsecurity(dentry->d_inode, suffix,
184 error = security_inode_getsecctx(dentry->d_inode,
185 &secdata, &secdata_len);
189 mutex_lock(&sysfs_mutex);
190 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
191 mutex_unlock(&sysfs_mutex);
194 security_release_secctx(secdata, secdata_len);
201 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
203 inode->i_mode = mode;
204 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
207 static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
209 inode->i_uid = iattr->ia_uid;
210 inode->i_gid = iattr->ia_gid;
211 inode->i_atime = iattr->ia_atime;
212 inode->i_mtime = iattr->ia_mtime;
213 inode->i_ctime = iattr->ia_ctime;
216 static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
218 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
220 inode->i_mode = sd->s_mode;
222 /* sysfs_dirent has non-default attributes
223 * get them from persistent copy in sysfs_dirent
225 set_inode_attr(inode, &iattrs->ia_iattr);
226 security_inode_notifysecctx(inode,
228 iattrs->ia_secdata_len);
231 if (sysfs_type(sd) == SYSFS_DIR)
232 set_nlink(inode, sd->s_dir.subdirs + 2);
235 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
238 struct sysfs_dirent *sd = dentry->d_fsdata;
239 struct inode *inode = dentry->d_inode;
241 mutex_lock(&sysfs_mutex);
242 sysfs_refresh_inode(sd, inode);
243 mutex_unlock(&sysfs_mutex);
245 generic_fillattr(inode, stat);
249 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
252 inode->i_private = sd;
253 inode->i_mapping->a_ops = &sysfs_aops;
254 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
255 inode->i_op = &sysfs_inode_operations;
257 set_default_inode_attr(inode, sd->s_mode);
258 sysfs_refresh_inode(sd, inode);
260 /* initialize inode according to type */
261 switch (sysfs_type(sd)) {
263 inode->i_op = &sysfs_dir_inode_operations;
264 inode->i_fop = &sysfs_dir_operations;
266 case SYSFS_KOBJ_ATTR:
267 inode->i_size = sd->s_attr.size;
268 inode->i_fop = &kernfs_file_operations;
270 case SYSFS_KOBJ_LINK:
271 inode->i_op = &sysfs_symlink_inode_operations;
277 unlock_new_inode(inode);
281 * sysfs_get_inode - get inode for sysfs_dirent
283 * @sd: sysfs_dirent to allocate inode for
285 * Get inode for @sd. If such inode doesn't exist, a new inode
286 * is allocated and basics are initialized. New inode is
290 * Kernel thread context (may sleep).
293 * Pointer to allocated inode on success, NULL on failure.
295 struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
299 inode = iget_locked(sb, sd->s_ino);
300 if (inode && (inode->i_state & I_NEW))
301 sysfs_init_inode(sd, inode);
307 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
308 * To prevent the sysfs inode numbers from being freed prematurely we take a
309 * reference to sysfs_dirent from the sysfs inode. A
310 * super_operations.evict_inode() implementation is needed to drop that
311 * reference upon inode destruction.
313 void sysfs_evict_inode(struct inode *inode)
315 struct sysfs_dirent *sd = inode->i_private;
317 truncate_inode_pages(&inode->i_data, 0);
322 int sysfs_permission(struct inode *inode, int mask)
324 struct sysfs_dirent *sd;
326 if (mask & MAY_NOT_BLOCK)
329 sd = inode->i_private;
331 mutex_lock(&sysfs_mutex);
332 sysfs_refresh_inode(sd, inode);
333 mutex_unlock(&sysfs_mutex);
335 return generic_permission(inode, mask);