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 = kernfs_iop_setxattr,
32 .removexattr = kernfs_iop_removexattr,
33 .getxattr = kernfs_iop_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_node *kn, void **secdata,
144 struct kernfs_iattrs *attrs;
146 size_t old_secdata_len;
148 attrs = kernfs_iattrs(kn);
152 old_secdata = attrs->ia_secdata;
153 old_secdata_len = attrs->ia_secdata_len;
155 attrs->ia_secdata = *secdata;
156 attrs->ia_secdata_len = *secdata_len;
158 *secdata = old_secdata;
159 *secdata_len = old_secdata_len;
163 int kernfs_iop_setxattr(struct dentry *dentry, const char *name,
164 const void *value, size_t size, int flags)
166 struct kernfs_node *kn = dentry->d_fsdata;
167 struct kernfs_iattrs *attrs;
172 attrs = kernfs_iattrs(kn);
176 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
177 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
178 error = security_inode_setsecurity(d_inode(dentry), suffix,
182 error = security_inode_getsecctx(d_inode(dentry),
183 &secdata, &secdata_len);
187 mutex_lock(&kernfs_mutex);
188 error = kernfs_node_setsecdata(kn, &secdata, &secdata_len);
189 mutex_unlock(&kernfs_mutex);
192 security_release_secctx(secdata, secdata_len);
194 } else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
195 return simple_xattr_set(&attrs->xattrs, name, value, size,
202 int kernfs_iop_removexattr(struct dentry *dentry, const char *name)
204 struct kernfs_node *kn = dentry->d_fsdata;
205 struct kernfs_iattrs *attrs;
207 attrs = kernfs_iattrs(kn);
211 return simple_xattr_set(&attrs->xattrs, name, NULL, 0, XATTR_REPLACE);
214 ssize_t kernfs_iop_getxattr(struct dentry *unused, struct inode *inode,
215 const char *name, void *buf, size_t size)
217 struct kernfs_node *kn = inode->i_private;
218 struct kernfs_iattrs *attrs;
220 attrs = kernfs_iattrs(kn);
224 return simple_xattr_get(&attrs->xattrs, name, buf, size);
227 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
229 struct kernfs_node *kn = dentry->d_fsdata;
230 struct kernfs_iattrs *attrs;
232 attrs = kernfs_iattrs(kn);
236 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
239 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
241 inode->i_mode = mode;
242 inode->i_atime = inode->i_mtime =
243 inode->i_ctime = current_fs_time(inode->i_sb);
246 static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
248 struct super_block *sb = inode->i_sb;
249 inode->i_uid = iattr->ia_uid;
250 inode->i_gid = iattr->ia_gid;
251 inode->i_atime = timespec_trunc(iattr->ia_atime, sb->s_time_gran);
252 inode->i_mtime = timespec_trunc(iattr->ia_mtime, sb->s_time_gran);
253 inode->i_ctime = timespec_trunc(iattr->ia_ctime, sb->s_time_gran);
256 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
258 struct kernfs_iattrs *attrs = kn->iattr;
260 inode->i_mode = kn->mode;
263 * kernfs_node has non-default attributes get them from
264 * persistent copy in kernfs_node.
266 set_inode_attr(inode, &attrs->ia_iattr);
267 security_inode_notifysecctx(inode, attrs->ia_secdata,
268 attrs->ia_secdata_len);
271 if (kernfs_type(kn) == KERNFS_DIR)
272 set_nlink(inode, kn->dir.subdirs + 2);
275 int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
278 struct kernfs_node *kn = dentry->d_fsdata;
279 struct inode *inode = d_inode(dentry);
281 mutex_lock(&kernfs_mutex);
282 kernfs_refresh_inode(kn, inode);
283 mutex_unlock(&kernfs_mutex);
285 generic_fillattr(inode, stat);
289 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
292 inode->i_private = kn;
293 inode->i_mapping->a_ops = &kernfs_aops;
294 inode->i_op = &kernfs_iops;
296 set_default_inode_attr(inode, kn->mode);
297 kernfs_refresh_inode(kn, inode);
299 /* initialize inode according to type */
300 switch (kernfs_type(kn)) {
302 inode->i_op = &kernfs_dir_iops;
303 inode->i_fop = &kernfs_dir_fops;
304 if (kn->flags & KERNFS_EMPTY_DIR)
305 make_empty_dir_inode(inode);
308 inode->i_size = kn->attr.size;
309 inode->i_fop = &kernfs_file_fops;
312 inode->i_op = &kernfs_symlink_iops;
318 unlock_new_inode(inode);
322 * kernfs_get_inode - get inode for kernfs_node
324 * @kn: kernfs_node to allocate inode for
326 * Get inode for @kn. If such inode doesn't exist, a new inode is
327 * allocated and basics are initialized. New inode is returned
331 * Kernel thread context (may sleep).
334 * Pointer to allocated inode on success, NULL on failure.
336 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
340 inode = iget_locked(sb, kn->ino);
341 if (inode && (inode->i_state & I_NEW))
342 kernfs_init_inode(kn, inode);
348 * The kernfs_node serves as both an inode and a directory entry for
349 * kernfs. To prevent the kernfs inode numbers from being freed
350 * prematurely we take a reference to kernfs_node from the kernfs inode. A
351 * super_operations.evict_inode() implementation is needed to drop that
352 * reference upon inode destruction.
354 void kernfs_evict_inode(struct inode *inode)
356 struct kernfs_node *kn = inode->i_private;
358 truncate_inode_pages_final(&inode->i_data);
363 int kernfs_iop_permission(struct inode *inode, int mask)
365 struct kernfs_node *kn;
367 if (mask & MAY_NOT_BLOCK)
370 kn = inode->i_private;
372 mutex_lock(&kernfs_mutex);
373 kernfs_refresh_inode(kn, inode);
374 mutex_unlock(&kernfs_mutex);
376 return generic_permission(inode, mask);