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 kernfs_aops = {
22 .readpage = simple_readpage,
23 .write_begin = simple_write_begin,
24 .write_end = simple_write_end,
27 static const struct inode_operations kernfs_iops = {
28 .permission = kernfs_iop_permission,
29 .setattr = kernfs_iop_setattr,
30 .getattr = kernfs_iop_getattr,
31 .setxattr = generic_setxattr,
32 .removexattr = generic_removexattr,
33 .getxattr = generic_getxattr,
34 .listxattr = kernfs_iop_listxattr,
37 static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
39 static DEFINE_MUTEX(iattr_mutex);
40 struct kernfs_iattrs *ret;
43 mutex_lock(&iattr_mutex);
48 kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL);
51 iattrs = &kn->iattr->ia_iattr;
53 /* assign default attributes */
54 iattrs->ia_mode = kn->mode;
55 iattrs->ia_uid = GLOBAL_ROOT_UID;
56 iattrs->ia_gid = GLOBAL_ROOT_GID;
58 ktime_get_real_ts(&iattrs->ia_atime);
59 iattrs->ia_mtime = iattrs->ia_atime;
60 iattrs->ia_ctime = iattrs->ia_atime;
62 simple_xattrs_init(&kn->iattr->xattrs);
65 mutex_unlock(&iattr_mutex);
69 static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
71 struct kernfs_iattrs *attrs;
73 unsigned int ia_valid = iattr->ia_valid;
75 attrs = kernfs_iattrs(kn);
79 iattrs = &attrs->ia_iattr;
81 if (ia_valid & ATTR_UID)
82 iattrs->ia_uid = iattr->ia_uid;
83 if (ia_valid & ATTR_GID)
84 iattrs->ia_gid = iattr->ia_gid;
85 if (ia_valid & ATTR_ATIME)
86 iattrs->ia_atime = iattr->ia_atime;
87 if (ia_valid & ATTR_MTIME)
88 iattrs->ia_mtime = iattr->ia_mtime;
89 if (ia_valid & ATTR_CTIME)
90 iattrs->ia_ctime = iattr->ia_ctime;
91 if (ia_valid & ATTR_MODE) {
92 umode_t mode = iattr->ia_mode;
93 iattrs->ia_mode = kn->mode = mode;
99 * kernfs_setattr - set iattr on a node
101 * @iattr: iattr to set
103 * Returns 0 on success, -errno on failure.
105 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
109 mutex_lock(&kernfs_mutex);
110 ret = __kernfs_setattr(kn, iattr);
111 mutex_unlock(&kernfs_mutex);
115 int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
117 struct inode *inode = d_inode(dentry);
118 struct kernfs_node *kn = dentry->d_fsdata;
124 mutex_lock(&kernfs_mutex);
125 error = inode_change_ok(inode, iattr);
129 error = __kernfs_setattr(kn, iattr);
133 /* this ignores size changes */
134 setattr_copy(inode, iattr);
137 mutex_unlock(&kernfs_mutex);
141 static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
145 size_t old_secdata_len;
147 old_secdata = attrs->ia_secdata;
148 old_secdata_len = attrs->ia_secdata_len;
150 attrs->ia_secdata = *secdata;
151 attrs->ia_secdata_len = *secdata_len;
153 *secdata = old_secdata;
154 *secdata_len = old_secdata_len;
158 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
160 struct kernfs_node *kn = dentry->d_fsdata;
161 struct kernfs_iattrs *attrs;
163 attrs = kernfs_iattrs(kn);
167 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
170 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
172 inode->i_mode = mode;
173 inode->i_atime = inode->i_mtime =
174 inode->i_ctime = current_fs_time(inode->i_sb);
177 static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
179 struct super_block *sb = inode->i_sb;
180 inode->i_uid = iattr->ia_uid;
181 inode->i_gid = iattr->ia_gid;
182 inode->i_atime = timespec_trunc(iattr->ia_atime, sb->s_time_gran);
183 inode->i_mtime = timespec_trunc(iattr->ia_mtime, sb->s_time_gran);
184 inode->i_ctime = timespec_trunc(iattr->ia_ctime, sb->s_time_gran);
187 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
189 struct kernfs_iattrs *attrs = kn->iattr;
191 inode->i_mode = kn->mode;
194 * kernfs_node has non-default attributes get them from
195 * persistent copy in kernfs_node.
197 set_inode_attr(inode, &attrs->ia_iattr);
198 security_inode_notifysecctx(inode, attrs->ia_secdata,
199 attrs->ia_secdata_len);
202 if (kernfs_type(kn) == KERNFS_DIR)
203 set_nlink(inode, kn->dir.subdirs + 2);
206 int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
209 struct kernfs_node *kn = dentry->d_fsdata;
210 struct inode *inode = d_inode(dentry);
212 mutex_lock(&kernfs_mutex);
213 kernfs_refresh_inode(kn, inode);
214 mutex_unlock(&kernfs_mutex);
216 generic_fillattr(inode, stat);
220 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
223 inode->i_private = kn;
224 inode->i_mapping->a_ops = &kernfs_aops;
225 inode->i_op = &kernfs_iops;
227 set_default_inode_attr(inode, kn->mode);
228 kernfs_refresh_inode(kn, inode);
230 /* initialize inode according to type */
231 switch (kernfs_type(kn)) {
233 inode->i_op = &kernfs_dir_iops;
234 inode->i_fop = &kernfs_dir_fops;
235 if (kn->flags & KERNFS_EMPTY_DIR)
236 make_empty_dir_inode(inode);
239 inode->i_size = kn->attr.size;
240 inode->i_fop = &kernfs_file_fops;
243 inode->i_op = &kernfs_symlink_iops;
249 unlock_new_inode(inode);
253 * kernfs_get_inode - get inode for kernfs_node
255 * @kn: kernfs_node to allocate inode for
257 * Get inode for @kn. If such inode doesn't exist, a new inode is
258 * allocated and basics are initialized. New inode is returned
262 * Kernel thread context (may sleep).
265 * Pointer to allocated inode on success, NULL on failure.
267 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
271 inode = iget_locked(sb, kn->ino);
272 if (inode && (inode->i_state & I_NEW))
273 kernfs_init_inode(kn, inode);
279 * The kernfs_node serves as both an inode and a directory entry for
280 * kernfs. To prevent the kernfs inode numbers from being freed
281 * prematurely we take a reference to kernfs_node from the kernfs inode. A
282 * super_operations.evict_inode() implementation is needed to drop that
283 * reference upon inode destruction.
285 void kernfs_evict_inode(struct inode *inode)
287 struct kernfs_node *kn = inode->i_private;
289 truncate_inode_pages_final(&inode->i_data);
294 int kernfs_iop_permission(struct inode *inode, int mask)
296 struct kernfs_node *kn;
298 if (mask & MAY_NOT_BLOCK)
301 kn = inode->i_private;
303 mutex_lock(&kernfs_mutex);
304 kernfs_refresh_inode(kn, inode);
305 mutex_unlock(&kernfs_mutex);
307 return generic_permission(inode, mask);
310 static int kernfs_xattr_get(const struct xattr_handler *handler,
311 struct dentry *unused, struct inode *inode,
312 const char *suffix, void *value, size_t size)
314 const char *name = xattr_full_name(handler, suffix);
315 struct kernfs_node *kn = inode->i_private;
316 struct kernfs_iattrs *attrs;
318 attrs = kernfs_iattrs(kn);
322 return simple_xattr_get(&attrs->xattrs, name, value, size);
325 static int kernfs_xattr_set(const struct xattr_handler *handler,
326 struct dentry *unused, struct inode *inode,
327 const char *suffix, const void *value,
328 size_t size, int flags)
330 const char *name = xattr_full_name(handler, suffix);
331 struct kernfs_node *kn = inode->i_private;
332 struct kernfs_iattrs *attrs;
334 attrs = kernfs_iattrs(kn);
338 return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
341 const struct xattr_handler kernfs_trusted_xattr_handler = {
342 .prefix = XATTR_TRUSTED_PREFIX,
343 .get = kernfs_xattr_get,
344 .set = kernfs_xattr_set,
347 static int kernfs_security_xattr_set(const struct xattr_handler *handler,
348 struct dentry *unused, struct inode *inode,
349 const char *suffix, const void *value,
350 size_t size, int flags)
352 struct kernfs_node *kn = inode->i_private;
353 struct kernfs_iattrs *attrs;
358 attrs = kernfs_iattrs(kn);
362 error = security_inode_setsecurity(inode, suffix, value, size, flags);
365 error = security_inode_getsecctx(inode, &secdata, &secdata_len);
369 mutex_lock(&kernfs_mutex);
370 error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
371 mutex_unlock(&kernfs_mutex);
374 security_release_secctx(secdata, secdata_len);
378 const struct xattr_handler kernfs_security_xattr_handler = {
379 .prefix = XATTR_SECURITY_PREFIX,
380 .get = kernfs_xattr_get,
381 .set = kernfs_security_xattr_set,
384 const struct xattr_handler *kernfs_xattr_handlers[] = {
385 &kernfs_trusted_xattr_handler,
386 &kernfs_security_xattr_handler,