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 void __init sysfs_inode_init(void)
42 if (bdi_init(&sysfs_backing_dev_info))
43 panic("failed to init sysfs_backing_dev_info");
46 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
48 struct sysfs_inode_attrs *attrs;
51 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
54 iattrs = &attrs->ia_iattr;
56 /* assign default attributes */
57 iattrs->ia_mode = sd->s_mode;
58 iattrs->ia_uid = GLOBAL_ROOT_UID;
59 iattrs->ia_gid = GLOBAL_ROOT_GID;
60 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
65 static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
67 struct sysfs_inode_attrs *sd_attrs;
69 unsigned int ia_valid = iattr->ia_valid;
71 sd_attrs = sd->s_iattr;
74 /* setting attributes for the first time, allocate now */
75 sd_attrs = sysfs_init_inode_attrs(sd);
78 sd->s_iattr = sd_attrs;
80 /* attributes were changed at least once in past */
81 iattrs = &sd_attrs->ia_iattr;
83 if (ia_valid & ATTR_UID)
84 iattrs->ia_uid = iattr->ia_uid;
85 if (ia_valid & ATTR_GID)
86 iattrs->ia_gid = iattr->ia_gid;
87 if (ia_valid & ATTR_ATIME)
88 iattrs->ia_atime = iattr->ia_atime;
89 if (ia_valid & ATTR_MTIME)
90 iattrs->ia_mtime = iattr->ia_mtime;
91 if (ia_valid & ATTR_CTIME)
92 iattrs->ia_ctime = iattr->ia_ctime;
93 if (ia_valid & ATTR_MODE) {
94 umode_t mode = iattr->ia_mode;
95 iattrs->ia_mode = sd->s_mode = mode;
101 * kernfs_setattr - set iattr on a node
103 * @iattr: iattr to set
105 * Returns 0 on success, -errno on failure.
107 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
111 mutex_lock(&sysfs_mutex);
112 ret = __kernfs_setattr(sd, iattr);
113 mutex_unlock(&sysfs_mutex);
117 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
119 struct inode *inode = dentry->d_inode;
120 struct sysfs_dirent *sd = dentry->d_fsdata;
126 mutex_lock(&sysfs_mutex);
127 error = inode_change_ok(inode, iattr);
131 error = __kernfs_setattr(sd, iattr);
135 /* this ignores size changes */
136 setattr_copy(inode, iattr);
139 mutex_unlock(&sysfs_mutex);
143 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
146 struct sysfs_inode_attrs *iattrs;
148 size_t old_secdata_len;
151 sd->s_iattr = sysfs_init_inode_attrs(sd);
156 iattrs = sd->s_iattr;
157 old_secdata = iattrs->ia_secdata;
158 old_secdata_len = iattrs->ia_secdata_len;
160 iattrs->ia_secdata = *secdata;
161 iattrs->ia_secdata_len = *secdata_len;
163 *secdata = old_secdata;
164 *secdata_len = old_secdata_len;
168 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
169 size_t size, int flags)
171 struct sysfs_dirent *sd = dentry->d_fsdata;
179 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
180 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
181 error = security_inode_setsecurity(dentry->d_inode, suffix,
185 error = security_inode_getsecctx(dentry->d_inode,
186 &secdata, &secdata_len);
190 mutex_lock(&sysfs_mutex);
191 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
192 mutex_unlock(&sysfs_mutex);
195 security_release_secctx(secdata, secdata_len);
202 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
204 inode->i_mode = mode;
205 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
208 static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
210 inode->i_uid = iattr->ia_uid;
211 inode->i_gid = iattr->ia_gid;
212 inode->i_atime = iattr->ia_atime;
213 inode->i_mtime = iattr->ia_mtime;
214 inode->i_ctime = iattr->ia_ctime;
217 static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
219 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
221 inode->i_mode = sd->s_mode;
223 /* sysfs_dirent has non-default attributes
224 * get them from persistent copy in sysfs_dirent
226 set_inode_attr(inode, &iattrs->ia_iattr);
227 security_inode_notifysecctx(inode,
229 iattrs->ia_secdata_len);
232 if (sysfs_type(sd) == SYSFS_DIR)
233 set_nlink(inode, sd->s_dir.subdirs + 2);
236 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
239 struct sysfs_dirent *sd = dentry->d_fsdata;
240 struct inode *inode = dentry->d_inode;
242 mutex_lock(&sysfs_mutex);
243 sysfs_refresh_inode(sd, inode);
244 mutex_unlock(&sysfs_mutex);
246 generic_fillattr(inode, stat);
250 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
253 inode->i_private = sd;
254 inode->i_mapping->a_ops = &sysfs_aops;
255 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
256 inode->i_op = &sysfs_inode_operations;
258 set_default_inode_attr(inode, sd->s_mode);
259 sysfs_refresh_inode(sd, inode);
261 /* initialize inode according to type */
262 switch (sysfs_type(sd)) {
264 inode->i_op = &sysfs_dir_inode_operations;
265 inode->i_fop = &sysfs_dir_operations;
267 case SYSFS_KOBJ_ATTR:
268 inode->i_size = sd->s_attr.size;
269 inode->i_fop = &kernfs_file_operations;
271 case SYSFS_KOBJ_LINK:
272 inode->i_op = &sysfs_symlink_inode_operations;
278 unlock_new_inode(inode);
282 * sysfs_get_inode - get inode for sysfs_dirent
284 * @sd: sysfs_dirent to allocate inode for
286 * Get inode for @sd. If such inode doesn't exist, a new inode
287 * is allocated and basics are initialized. New inode is
291 * Kernel thread context (may sleep).
294 * Pointer to allocated inode on success, NULL on failure.
296 struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
300 inode = iget_locked(sb, sd->s_ino);
301 if (inode && (inode->i_state & I_NEW))
302 sysfs_init_inode(sd, inode);
308 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
309 * To prevent the sysfs inode numbers from being freed prematurely we take a
310 * reference to sysfs_dirent from the sysfs inode. A
311 * super_operations.evict_inode() implementation is needed to drop that
312 * reference upon inode destruction.
314 void sysfs_evict_inode(struct inode *inode)
316 struct sysfs_dirent *sd = inode->i_private;
318 truncate_inode_pages(&inode->i_data, 0);
323 int sysfs_permission(struct inode *inode, int mask)
325 struct sysfs_dirent *sd;
327 if (mask & MAY_NOT_BLOCK)
330 sd = inode->i_private;
332 mutex_lock(&sysfs_mutex);
333 sysfs_refresh_inode(sd, inode);
334 mutex_unlock(&sysfs_mutex);
336 return generic_permission(inode, mask);