blob: 1719649d7ad78378d01df519a77888853e69adfe [file] [log] [blame]
Tejun Heob8441ed2013-11-24 09:54:58 -05001/*
2 * fs/kernfs/inode.c - kernfs inode implementation
3 *
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>
7 *
8 * This file is released under the GPLv2.
9 */
Tejun Heoffed24e2013-11-28 14:54:32 -050010
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>
18
19#include "kernfs-internal.h"
20
Tejun Heoa797bfc2013-12-11 14:11:57 -050021static const struct address_space_operations kernfs_aops = {
Tejun Heoffed24e2013-11-28 14:54:32 -050022 .readpage = simple_readpage,
23 .write_begin = simple_write_begin,
24 .write_end = simple_write_end,
25};
26
Tejun Heoa797bfc2013-12-11 14:11:57 -050027static const struct inode_operations kernfs_iops = {
Tejun Heoc637b8a2013-12-11 14:11:58 -050028 .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,
Tejun Heoffed24e2013-11-28 14:54:32 -050035};
36
Tejun Heoc525aad2013-12-11 14:11:55 -050037static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
Tejun Heoffed24e2013-11-28 14:54:32 -050038{
Tejun Heo4afddd62014-04-02 16:40:52 -040039 static DEFINE_MUTEX(iattr_mutex);
40 struct kernfs_iattrs *ret;
Tejun Heoffed24e2013-11-28 14:54:32 -050041 struct iattr *iattrs;
42
Tejun Heo4afddd62014-04-02 16:40:52 -040043 mutex_lock(&iattr_mutex);
44
Tejun Heoadc5e8b2013-12-11 14:11:54 -050045 if (kn->iattr)
Tejun Heo4afddd62014-04-02 16:40:52 -040046 goto out_unlock;
Tejun Heo9a8049a2013-11-23 17:40:01 -050047
Tejun Heoc525aad2013-12-11 14:11:55 -050048 kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL);
Tejun Heoadc5e8b2013-12-11 14:11:54 -050049 if (!kn->iattr)
Tejun Heo4afddd62014-04-02 16:40:52 -040050 goto out_unlock;
Tejun Heoadc5e8b2013-12-11 14:11:54 -050051 iattrs = &kn->iattr->ia_iattr;
Tejun Heoffed24e2013-11-28 14:54:32 -050052
53 /* assign default attributes */
Tejun Heoadc5e8b2013-12-11 14:11:54 -050054 iattrs->ia_mode = kn->mode;
Tejun Heoffed24e2013-11-28 14:54:32 -050055 iattrs->ia_uid = GLOBAL_ROOT_UID;
56 iattrs->ia_gid = GLOBAL_ROOT_GID;
Deepa Dinamani3a3a5fe2016-02-22 07:17:53 -080057
58 ktime_get_real_ts(&iattrs->ia_atime);
59 iattrs->ia_mtime = iattrs->ia_atime;
60 iattrs->ia_ctime = iattrs->ia_atime;
Tejun Heoffed24e2013-11-28 14:54:32 -050061
Tejun Heoadc5e8b2013-12-11 14:11:54 -050062 simple_xattrs_init(&kn->iattr->xattrs);
Tejun Heo4afddd62014-04-02 16:40:52 -040063out_unlock:
64 ret = kn->iattr;
65 mutex_unlock(&iattr_mutex);
66 return ret;
Tejun Heoffed24e2013-11-28 14:54:32 -050067}
68
Tejun Heo324a56e2013-12-11 14:11:53 -050069static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
Tejun Heoffed24e2013-11-28 14:54:32 -050070{
Tejun Heoc525aad2013-12-11 14:11:55 -050071 struct kernfs_iattrs *attrs;
Tejun Heoffed24e2013-11-28 14:54:32 -050072 struct iattr *iattrs;
73 unsigned int ia_valid = iattr->ia_valid;
74
Tejun Heoc525aad2013-12-11 14:11:55 -050075 attrs = kernfs_iattrs(kn);
Tejun Heo9a8049a2013-11-23 17:40:01 -050076 if (!attrs)
77 return -ENOMEM;
Tejun Heoffed24e2013-11-28 14:54:32 -050078
Tejun Heo9a8049a2013-11-23 17:40:01 -050079 iattrs = &attrs->ia_iattr;
Tejun Heoffed24e2013-11-28 14:54:32 -050080
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;
Tejun Heoadc5e8b2013-12-11 14:11:54 -050093 iattrs->ia_mode = kn->mode = mode;
Tejun Heoffed24e2013-11-28 14:54:32 -050094 }
95 return 0;
96}
97
98/**
99 * kernfs_setattr - set iattr on a node
Tejun Heo324a56e2013-12-11 14:11:53 -0500100 * @kn: target node
Tejun Heoffed24e2013-11-28 14:54:32 -0500101 * @iattr: iattr to set
102 *
103 * Returns 0 on success, -errno on failure.
104 */
Tejun Heo324a56e2013-12-11 14:11:53 -0500105int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
Tejun Heoffed24e2013-11-28 14:54:32 -0500106{
107 int ret;
108
Tejun Heoa797bfc2013-12-11 14:11:57 -0500109 mutex_lock(&kernfs_mutex);
Tejun Heo324a56e2013-12-11 14:11:53 -0500110 ret = __kernfs_setattr(kn, iattr);
Tejun Heoa797bfc2013-12-11 14:11:57 -0500111 mutex_unlock(&kernfs_mutex);
Tejun Heoffed24e2013-11-28 14:54:32 -0500112 return ret;
113}
114
Tejun Heoc637b8a2013-12-11 14:11:58 -0500115int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
Tejun Heoffed24e2013-11-28 14:54:32 -0500116{
David Howells2b0143b2015-03-17 22:25:59 +0000117 struct inode *inode = d_inode(dentry);
Tejun Heo324a56e2013-12-11 14:11:53 -0500118 struct kernfs_node *kn = dentry->d_fsdata;
Tejun Heoffed24e2013-11-28 14:54:32 -0500119 int error;
120
Tejun Heo324a56e2013-12-11 14:11:53 -0500121 if (!kn)
Tejun Heoffed24e2013-11-28 14:54:32 -0500122 return -EINVAL;
123
Tejun Heoa797bfc2013-12-11 14:11:57 -0500124 mutex_lock(&kernfs_mutex);
Tejun Heoffed24e2013-11-28 14:54:32 -0500125 error = inode_change_ok(inode, iattr);
126 if (error)
127 goto out;
128
Tejun Heo324a56e2013-12-11 14:11:53 -0500129 error = __kernfs_setattr(kn, iattr);
Tejun Heoffed24e2013-11-28 14:54:32 -0500130 if (error)
131 goto out;
132
133 /* this ignores size changes */
134 setattr_copy(inode, iattr);
135
136out:
Tejun Heoa797bfc2013-12-11 14:11:57 -0500137 mutex_unlock(&kernfs_mutex);
Tejun Heoffed24e2013-11-28 14:54:32 -0500138 return error;
139}
140
Tejun Heoc637b8a2013-12-11 14:11:58 -0500141static int kernfs_node_setsecdata(struct kernfs_node *kn, void **secdata,
142 u32 *secdata_len)
Tejun Heoffed24e2013-11-28 14:54:32 -0500143{
Tejun Heoc525aad2013-12-11 14:11:55 -0500144 struct kernfs_iattrs *attrs;
Tejun Heoffed24e2013-11-28 14:54:32 -0500145 void *old_secdata;
146 size_t old_secdata_len;
147
Tejun Heoc525aad2013-12-11 14:11:55 -0500148 attrs = kernfs_iattrs(kn);
Tejun Heo9a8049a2013-11-23 17:40:01 -0500149 if (!attrs)
150 return -ENOMEM;
Tejun Heoffed24e2013-11-28 14:54:32 -0500151
Tejun Heo9a8049a2013-11-23 17:40:01 -0500152 old_secdata = attrs->ia_secdata;
153 old_secdata_len = attrs->ia_secdata_len;
Tejun Heoffed24e2013-11-28 14:54:32 -0500154
Tejun Heo9a8049a2013-11-23 17:40:01 -0500155 attrs->ia_secdata = *secdata;
156 attrs->ia_secdata_len = *secdata_len;
Tejun Heoffed24e2013-11-28 14:54:32 -0500157
158 *secdata = old_secdata;
159 *secdata_len = old_secdata_len;
160 return 0;
161}
162
Tejun Heoc637b8a2013-12-11 14:11:58 -0500163int kernfs_iop_setxattr(struct dentry *dentry, const char *name,
164 const void *value, size_t size, int flags)
Tejun Heoffed24e2013-11-28 14:54:32 -0500165{
Tejun Heo324a56e2013-12-11 14:11:53 -0500166 struct kernfs_node *kn = dentry->d_fsdata;
Tejun Heoc525aad2013-12-11 14:11:55 -0500167 struct kernfs_iattrs *attrs;
Tejun Heoffed24e2013-11-28 14:54:32 -0500168 void *secdata;
169 int error;
170 u32 secdata_len = 0;
171
Tejun Heoc525aad2013-12-11 14:11:55 -0500172 attrs = kernfs_iattrs(kn);
Tejun Heo23223922013-11-23 17:40:02 -0500173 if (!attrs)
174 return -ENOMEM;
Tejun Heoffed24e2013-11-28 14:54:32 -0500175
176 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
177 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
David Howells2b0143b2015-03-17 22:25:59 +0000178 error = security_inode_setsecurity(d_inode(dentry), suffix,
Tejun Heoffed24e2013-11-28 14:54:32 -0500179 value, size, flags);
180 if (error)
Tejun Heo23223922013-11-23 17:40:02 -0500181 return error;
David Howells2b0143b2015-03-17 22:25:59 +0000182 error = security_inode_getsecctx(d_inode(dentry),
Tejun Heoffed24e2013-11-28 14:54:32 -0500183 &secdata, &secdata_len);
184 if (error)
Tejun Heo23223922013-11-23 17:40:02 -0500185 return error;
Tejun Heoffed24e2013-11-28 14:54:32 -0500186
Tejun Heoa797bfc2013-12-11 14:11:57 -0500187 mutex_lock(&kernfs_mutex);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500188 error = kernfs_node_setsecdata(kn, &secdata, &secdata_len);
Tejun Heoa797bfc2013-12-11 14:11:57 -0500189 mutex_unlock(&kernfs_mutex);
Tejun Heoffed24e2013-11-28 14:54:32 -0500190
191 if (secdata)
192 security_release_secctx(secdata, secdata_len);
Tejun Heo23223922013-11-23 17:40:02 -0500193 return error;
194 } else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
195 return simple_xattr_set(&attrs->xattrs, name, value, size,
196 flags);
197 }
198
199 return -EINVAL;
200}
201
Tejun Heoc637b8a2013-12-11 14:11:58 -0500202int kernfs_iop_removexattr(struct dentry *dentry, const char *name)
Tejun Heo23223922013-11-23 17:40:02 -0500203{
Tejun Heo324a56e2013-12-11 14:11:53 -0500204 struct kernfs_node *kn = dentry->d_fsdata;
Tejun Heoc525aad2013-12-11 14:11:55 -0500205 struct kernfs_iattrs *attrs;
Tejun Heo23223922013-11-23 17:40:02 -0500206
Tejun Heoc525aad2013-12-11 14:11:55 -0500207 attrs = kernfs_iattrs(kn);
Tejun Heo23223922013-11-23 17:40:02 -0500208 if (!attrs)
209 return -ENOMEM;
210
Andreas Gruenbacheraa7c5242015-12-02 14:44:38 +0100211 return simple_xattr_set(&attrs->xattrs, name, NULL, 0, XATTR_REPLACE);
Tejun Heo23223922013-11-23 17:40:02 -0500212}
213
Al Viroce23e642016-04-11 00:48:00 -0400214ssize_t kernfs_iop_getxattr(struct dentry *unused, struct inode *inode,
215 const char *name, void *buf, size_t size)
Tejun Heo23223922013-11-23 17:40:02 -0500216{
Al Viroce23e642016-04-11 00:48:00 -0400217 struct kernfs_node *kn = inode->i_private;
Tejun Heoc525aad2013-12-11 14:11:55 -0500218 struct kernfs_iattrs *attrs;
Tejun Heo23223922013-11-23 17:40:02 -0500219
Tejun Heoc525aad2013-12-11 14:11:55 -0500220 attrs = kernfs_iattrs(kn);
Tejun Heo23223922013-11-23 17:40:02 -0500221 if (!attrs)
222 return -ENOMEM;
223
224 return simple_xattr_get(&attrs->xattrs, name, buf, size);
225}
226
Tejun Heoc637b8a2013-12-11 14:11:58 -0500227ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
Tejun Heo23223922013-11-23 17:40:02 -0500228{
Tejun Heo324a56e2013-12-11 14:11:53 -0500229 struct kernfs_node *kn = dentry->d_fsdata;
Tejun Heoc525aad2013-12-11 14:11:55 -0500230 struct kernfs_iattrs *attrs;
Tejun Heo23223922013-11-23 17:40:02 -0500231
Tejun Heoc525aad2013-12-11 14:11:55 -0500232 attrs = kernfs_iattrs(kn);
Tejun Heo23223922013-11-23 17:40:02 -0500233 if (!attrs)
234 return -ENOMEM;
235
Andreas Gruenbacher786534b2015-12-02 14:44:39 +0100236 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
Tejun Heoffed24e2013-11-28 14:54:32 -0500237}
238
239static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
240{
241 inode->i_mode = mode;
Deepa Dinamani3a3a5fe2016-02-22 07:17:53 -0800242 inode->i_atime = inode->i_mtime =
243 inode->i_ctime = current_fs_time(inode->i_sb);
Tejun Heoffed24e2013-11-28 14:54:32 -0500244}
245
246static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
247{
Deepa Dinamani3a3a5fe2016-02-22 07:17:53 -0800248 struct super_block *sb = inode->i_sb;
Tejun Heoffed24e2013-11-28 14:54:32 -0500249 inode->i_uid = iattr->ia_uid;
250 inode->i_gid = iattr->ia_gid;
Deepa Dinamani3a3a5fe2016-02-22 07:17:53 -0800251 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);
Tejun Heoffed24e2013-11-28 14:54:32 -0500254}
255
Tejun Heoc637b8a2013-12-11 14:11:58 -0500256static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
Tejun Heoffed24e2013-11-28 14:54:32 -0500257{
Tejun Heoc525aad2013-12-11 14:11:55 -0500258 struct kernfs_iattrs *attrs = kn->iattr;
Tejun Heoffed24e2013-11-28 14:54:32 -0500259
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500260 inode->i_mode = kn->mode;
Tejun Heo9a8049a2013-11-23 17:40:01 -0500261 if (attrs) {
Tejun Heo324a56e2013-12-11 14:11:53 -0500262 /*
263 * kernfs_node has non-default attributes get them from
264 * persistent copy in kernfs_node.
Tejun Heoffed24e2013-11-28 14:54:32 -0500265 */
Tejun Heo9a8049a2013-11-23 17:40:01 -0500266 set_inode_attr(inode, &attrs->ia_iattr);
267 security_inode_notifysecctx(inode, attrs->ia_secdata,
268 attrs->ia_secdata_len);
Tejun Heoffed24e2013-11-28 14:54:32 -0500269 }
270
Tejun Heodf23fc32013-12-11 14:11:56 -0500271 if (kernfs_type(kn) == KERNFS_DIR)
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500272 set_nlink(inode, kn->dir.subdirs + 2);
Tejun Heoffed24e2013-11-28 14:54:32 -0500273}
274
Tejun Heoc637b8a2013-12-11 14:11:58 -0500275int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
276 struct kstat *stat)
Tejun Heoffed24e2013-11-28 14:54:32 -0500277{
Tejun Heo324a56e2013-12-11 14:11:53 -0500278 struct kernfs_node *kn = dentry->d_fsdata;
David Howells2b0143b2015-03-17 22:25:59 +0000279 struct inode *inode = d_inode(dentry);
Tejun Heoffed24e2013-11-28 14:54:32 -0500280
Tejun Heoa797bfc2013-12-11 14:11:57 -0500281 mutex_lock(&kernfs_mutex);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500282 kernfs_refresh_inode(kn, inode);
Tejun Heoa797bfc2013-12-11 14:11:57 -0500283 mutex_unlock(&kernfs_mutex);
Tejun Heoffed24e2013-11-28 14:54:32 -0500284
285 generic_fillattr(inode, stat);
286 return 0;
287}
288
Tejun Heoc637b8a2013-12-11 14:11:58 -0500289static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
Tejun Heoffed24e2013-11-28 14:54:32 -0500290{
Tejun Heo324a56e2013-12-11 14:11:53 -0500291 kernfs_get(kn);
292 inode->i_private = kn;
Tejun Heoa797bfc2013-12-11 14:11:57 -0500293 inode->i_mapping->a_ops = &kernfs_aops;
Tejun Heoa797bfc2013-12-11 14:11:57 -0500294 inode->i_op = &kernfs_iops;
Tejun Heoffed24e2013-11-28 14:54:32 -0500295
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500296 set_default_inode_attr(inode, kn->mode);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500297 kernfs_refresh_inode(kn, inode);
Tejun Heoffed24e2013-11-28 14:54:32 -0500298
299 /* initialize inode according to type */
Tejun Heodf23fc32013-12-11 14:11:56 -0500300 switch (kernfs_type(kn)) {
301 case KERNFS_DIR:
Tejun Heoa797bfc2013-12-11 14:11:57 -0500302 inode->i_op = &kernfs_dir_iops;
303 inode->i_fop = &kernfs_dir_fops;
Eric W. Biedermanea015212015-05-13 16:09:29 -0500304 if (kn->flags & KERNFS_EMPTY_DIR)
305 make_empty_dir_inode(inode);
Tejun Heoffed24e2013-11-28 14:54:32 -0500306 break;
Tejun Heodf23fc32013-12-11 14:11:56 -0500307 case KERNFS_FILE:
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500308 inode->i_size = kn->attr.size;
Tejun Heoa797bfc2013-12-11 14:11:57 -0500309 inode->i_fop = &kernfs_file_fops;
Tejun Heoffed24e2013-11-28 14:54:32 -0500310 break;
Tejun Heodf23fc32013-12-11 14:11:56 -0500311 case KERNFS_LINK:
Tejun Heoa797bfc2013-12-11 14:11:57 -0500312 inode->i_op = &kernfs_symlink_iops;
Tejun Heoffed24e2013-11-28 14:54:32 -0500313 break;
314 default:
315 BUG();
316 }
317
318 unlock_new_inode(inode);
319}
320
321/**
Tejun Heoc637b8a2013-12-11 14:11:58 -0500322 * kernfs_get_inode - get inode for kernfs_node
Tejun Heoffed24e2013-11-28 14:54:32 -0500323 * @sb: super block
Tejun Heo324a56e2013-12-11 14:11:53 -0500324 * @kn: kernfs_node to allocate inode for
Tejun Heoffed24e2013-11-28 14:54:32 -0500325 *
Tejun Heo324a56e2013-12-11 14:11:53 -0500326 * Get inode for @kn. If such inode doesn't exist, a new inode is
327 * allocated and basics are initialized. New inode is returned
328 * locked.
Tejun Heoffed24e2013-11-28 14:54:32 -0500329 *
330 * LOCKING:
331 * Kernel thread context (may sleep).
332 *
333 * RETURNS:
334 * Pointer to allocated inode on success, NULL on failure.
335 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500336struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
Tejun Heoffed24e2013-11-28 14:54:32 -0500337{
338 struct inode *inode;
339
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500340 inode = iget_locked(sb, kn->ino);
Tejun Heoffed24e2013-11-28 14:54:32 -0500341 if (inode && (inode->i_state & I_NEW))
Tejun Heoc637b8a2013-12-11 14:11:58 -0500342 kernfs_init_inode(kn, inode);
Tejun Heoffed24e2013-11-28 14:54:32 -0500343
344 return inode;
345}
346
347/*
Tejun Heoc637b8a2013-12-11 14:11:58 -0500348 * 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
Tejun Heoffed24e2013-11-28 14:54:32 -0500351 * super_operations.evict_inode() implementation is needed to drop that
352 * reference upon inode destruction.
353 */
Tejun Heoc637b8a2013-12-11 14:11:58 -0500354void kernfs_evict_inode(struct inode *inode)
Tejun Heoffed24e2013-11-28 14:54:32 -0500355{
Tejun Heo324a56e2013-12-11 14:11:53 -0500356 struct kernfs_node *kn = inode->i_private;
Tejun Heoffed24e2013-11-28 14:54:32 -0500357
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700358 truncate_inode_pages_final(&inode->i_data);
Tejun Heoffed24e2013-11-28 14:54:32 -0500359 clear_inode(inode);
Tejun Heo324a56e2013-12-11 14:11:53 -0500360 kernfs_put(kn);
Tejun Heoffed24e2013-11-28 14:54:32 -0500361}
362
Tejun Heoc637b8a2013-12-11 14:11:58 -0500363int kernfs_iop_permission(struct inode *inode, int mask)
Tejun Heoffed24e2013-11-28 14:54:32 -0500364{
Tejun Heo324a56e2013-12-11 14:11:53 -0500365 struct kernfs_node *kn;
Tejun Heoffed24e2013-11-28 14:54:32 -0500366
367 if (mask & MAY_NOT_BLOCK)
368 return -ECHILD;
369
Tejun Heo324a56e2013-12-11 14:11:53 -0500370 kn = inode->i_private;
Tejun Heoffed24e2013-11-28 14:54:32 -0500371
Tejun Heoa797bfc2013-12-11 14:11:57 -0500372 mutex_lock(&kernfs_mutex);
Tejun Heoc637b8a2013-12-11 14:11:58 -0500373 kernfs_refresh_inode(kn, inode);
Tejun Heoa797bfc2013-12-11 14:11:57 -0500374 mutex_unlock(&kernfs_mutex);
Tejun Heoffed24e2013-11-28 14:54:32 -0500375
376 return generic_permission(inode, mask);
377}