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 .listxattr = kernfs_iop_listxattr,
34 static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
36 static DEFINE_MUTEX(iattr_mutex);
37 struct kernfs_iattrs *ret;
39 mutex_lock(&iattr_mutex);
41 if (kn->iattr || !alloc)
44 kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
48 /* assign default attributes */
49 kn->iattr->ia_uid = GLOBAL_ROOT_UID;
50 kn->iattr->ia_gid = GLOBAL_ROOT_GID;
52 ktime_get_real_ts64(&kn->iattr->ia_atime);
53 kn->iattr->ia_mtime = kn->iattr->ia_atime;
54 kn->iattr->ia_ctime = kn->iattr->ia_atime;
56 simple_xattrs_init(&kn->iattr->xattrs);
59 mutex_unlock(&iattr_mutex);
63 static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
65 return __kernfs_iattrs(kn, 1);
68 static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
70 return __kernfs_iattrs(kn, 0);
73 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
75 struct kernfs_iattrs *attrs;
76 unsigned int ia_valid = iattr->ia_valid;
78 attrs = kernfs_iattrs(kn);
82 if (ia_valid & ATTR_UID)
83 attrs->ia_uid = iattr->ia_uid;
84 if (ia_valid & ATTR_GID)
85 attrs->ia_gid = iattr->ia_gid;
86 if (ia_valid & ATTR_ATIME)
87 attrs->ia_atime = iattr->ia_atime;
88 if (ia_valid & ATTR_MTIME)
89 attrs->ia_mtime = iattr->ia_mtime;
90 if (ia_valid & ATTR_CTIME)
91 attrs->ia_ctime = iattr->ia_ctime;
92 if (ia_valid & ATTR_MODE)
93 kn->mode = iattr->ia_mode;
98 * kernfs_setattr - set iattr on a node
100 * @iattr: iattr to set
102 * Returns 0 on success, -errno on failure.
104 int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
108 mutex_lock(&kernfs_mutex);
109 ret = __kernfs_setattr(kn, iattr);
110 mutex_unlock(&kernfs_mutex);
114 int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
116 struct inode *inode = d_inode(dentry);
117 struct kernfs_node *kn = inode->i_private;
123 mutex_lock(&kernfs_mutex);
124 error = setattr_prepare(dentry, iattr);
128 error = __kernfs_setattr(kn, iattr);
132 /* this ignores size changes */
133 setattr_copy(inode, iattr);
136 mutex_unlock(&kernfs_mutex);
140 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
142 struct kernfs_node *kn = kernfs_dentry_node(dentry);
143 struct kernfs_iattrs *attrs;
145 attrs = kernfs_iattrs(kn);
149 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
152 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
154 inode->i_mode = mode;
155 inode->i_atime = inode->i_mtime =
156 inode->i_ctime = current_time(inode);
159 static inline void set_inode_attr(struct inode *inode,
160 struct kernfs_iattrs *attrs)
162 struct super_block *sb = inode->i_sb;
163 inode->i_uid = attrs->ia_uid;
164 inode->i_gid = attrs->ia_gid;
165 inode->i_atime = timespec64_trunc(attrs->ia_atime, sb->s_time_gran);
166 inode->i_mtime = timespec64_trunc(attrs->ia_mtime, sb->s_time_gran);
167 inode->i_ctime = timespec64_trunc(attrs->ia_ctime, sb->s_time_gran);
170 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
172 struct kernfs_iattrs *attrs = kn->iattr;
174 inode->i_mode = kn->mode;
177 * kernfs_node has non-default attributes get them from
178 * persistent copy in kernfs_node.
180 set_inode_attr(inode, attrs);
182 if (kernfs_type(kn) == KERNFS_DIR)
183 set_nlink(inode, kn->dir.subdirs + 2);
186 int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
187 u32 request_mask, unsigned int query_flags)
189 struct inode *inode = d_inode(path->dentry);
190 struct kernfs_node *kn = inode->i_private;
192 mutex_lock(&kernfs_mutex);
193 kernfs_refresh_inode(kn, inode);
194 mutex_unlock(&kernfs_mutex);
196 generic_fillattr(inode, stat);
200 static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
203 inode->i_private = kn;
204 inode->i_mapping->a_ops = &kernfs_aops;
205 inode->i_op = &kernfs_iops;
206 inode->i_generation = kn->id.generation;
208 set_default_inode_attr(inode, kn->mode);
209 kernfs_refresh_inode(kn, inode);
211 /* initialize inode according to type */
212 switch (kernfs_type(kn)) {
214 inode->i_op = &kernfs_dir_iops;
215 inode->i_fop = &kernfs_dir_fops;
216 if (kn->flags & KERNFS_EMPTY_DIR)
217 make_empty_dir_inode(inode);
220 inode->i_size = kn->attr.size;
221 inode->i_fop = &kernfs_file_fops;
224 inode->i_op = &kernfs_symlink_iops;
230 unlock_new_inode(inode);
234 * kernfs_get_inode - get inode for kernfs_node
236 * @kn: kernfs_node to allocate inode for
238 * Get inode for @kn. If such inode doesn't exist, a new inode is
239 * allocated and basics are initialized. New inode is returned
243 * Kernel thread context (may sleep).
246 * Pointer to allocated inode on success, NULL on failure.
248 struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
252 inode = iget_locked(sb, kn->id.ino);
253 if (inode && (inode->i_state & I_NEW))
254 kernfs_init_inode(kn, inode);
260 * The kernfs_node serves as both an inode and a directory entry for
261 * kernfs. To prevent the kernfs inode numbers from being freed
262 * prematurely we take a reference to kernfs_node from the kernfs inode. A
263 * super_operations.evict_inode() implementation is needed to drop that
264 * reference upon inode destruction.
266 void kernfs_evict_inode(struct inode *inode)
268 struct kernfs_node *kn = inode->i_private;
270 truncate_inode_pages_final(&inode->i_data);
275 int kernfs_iop_permission(struct inode *inode, int mask)
277 struct kernfs_node *kn;
279 if (mask & MAY_NOT_BLOCK)
282 kn = inode->i_private;
284 mutex_lock(&kernfs_mutex);
285 kernfs_refresh_inode(kn, inode);
286 mutex_unlock(&kernfs_mutex);
288 return generic_permission(inode, mask);
291 int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
292 void *value, size_t size)
294 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
298 return simple_xattr_get(&attrs->xattrs, name, value, size);
301 int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
302 const void *value, size_t size, int flags)
304 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
308 return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
311 static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
312 struct dentry *unused, struct inode *inode,
313 const char *suffix, void *value, size_t size)
315 const char *name = xattr_full_name(handler, suffix);
316 struct kernfs_node *kn = inode->i_private;
318 return kernfs_xattr_get(kn, name, value, size);
321 static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
322 struct dentry *unused, struct inode *inode,
323 const char *suffix, const void *value,
324 size_t size, int flags)
326 const char *name = xattr_full_name(handler, suffix);
327 struct kernfs_node *kn = inode->i_private;
329 return kernfs_xattr_set(kn, name, value, size, flags);
332 static const struct xattr_handler kernfs_trusted_xattr_handler = {
333 .prefix = XATTR_TRUSTED_PREFIX,
334 .get = kernfs_vfs_xattr_get,
335 .set = kernfs_vfs_xattr_set,
338 static const struct xattr_handler kernfs_security_xattr_handler = {
339 .prefix = XATTR_SECURITY_PREFIX,
340 .get = kernfs_vfs_xattr_get,
341 .set = kernfs_vfs_xattr_set,
344 const struct xattr_handler *kernfs_xattr_handlers[] = {
345 &kernfs_trusted_xattr_handler,
346 &kernfs_security_xattr_handler,