2 * fs/sysfs/inode.c - basic sysfs inode and dentry operations
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 * This file is released under the GPLv2.
10 * Please see Documentation/filesystems/sysfs.txt for more information.
15 #include <linux/pagemap.h>
16 #include <linux/namei.h>
17 #include <linux/backing-dev.h>
18 #include <linux/capability.h>
19 #include <linux/errno.h>
20 #include <linux/sched.h>
21 #include <linux/xattr.h>
22 #include <linux/security.h>
25 extern struct super_block * sysfs_sb;
27 static const struct address_space_operations sysfs_aops = {
28 .readpage = simple_readpage,
29 .write_begin = simple_write_begin,
30 .write_end = simple_write_end,
33 static struct backing_dev_info sysfs_backing_dev_info = {
35 .ra_pages = 0, /* No readahead */
36 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
39 static const struct inode_operations sysfs_inode_operations ={
40 .setattr = sysfs_setattr,
41 .setxattr = sysfs_setxattr,
44 int __init sysfs_inode_init(void)
46 return bdi_init(&sysfs_backing_dev_info);
49 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
51 struct sysfs_inode_attrs *attrs;
54 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
57 iattrs = &attrs->ia_iattr;
59 /* assign default attributes */
60 iattrs->ia_mode = sd->s_mode;
63 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
68 int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
70 struct sysfs_inode_attrs *sd_attrs;
72 unsigned int ia_valid = iattr->ia_valid;
74 sd_attrs = sd->s_iattr;
77 /* setting attributes for the first time, allocate now */
78 sd_attrs = sysfs_init_inode_attrs(sd);
81 sd->s_iattr = sd_attrs;
83 /* attributes were changed at least once in past */
84 iattrs = &sd_attrs->ia_iattr;
86 if (ia_valid & ATTR_UID)
87 iattrs->ia_uid = iattr->ia_uid;
88 if (ia_valid & ATTR_GID)
89 iattrs->ia_gid = iattr->ia_gid;
90 if (ia_valid & ATTR_ATIME)
91 iattrs->ia_atime = iattr->ia_atime;
92 if (ia_valid & ATTR_MTIME)
93 iattrs->ia_mtime = iattr->ia_mtime;
94 if (ia_valid & ATTR_CTIME)
95 iattrs->ia_ctime = iattr->ia_ctime;
96 if (ia_valid & ATTR_MODE) {
97 umode_t mode = iattr->ia_mode;
98 iattrs->ia_mode = sd->s_mode = mode;
104 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
106 struct inode *inode = dentry->d_inode;
107 struct sysfs_dirent *sd = dentry->d_fsdata;
113 error = inode_change_ok(inode, iattr);
117 iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
118 if (iattr->ia_valid & ATTR_MODE) {
119 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
120 iattr->ia_mode &= ~S_ISGID;
123 error = inode_setattr(inode, iattr);
127 mutex_lock(&sysfs_mutex);
128 error = sysfs_sd_setattr(sd, iattr);
129 mutex_unlock(&sysfs_mutex);
134 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)
136 struct sysfs_inode_attrs *iattrs;
138 size_t old_secdata_len;
140 iattrs = sd->s_iattr;
142 iattrs = sysfs_init_inode_attrs(sd);
146 old_secdata = iattrs->ia_secdata;
147 old_secdata_len = iattrs->ia_secdata_len;
149 iattrs->ia_secdata = *secdata;
150 iattrs->ia_secdata_len = *secdata_len;
152 *secdata = old_secdata;
153 *secdata_len = old_secdata_len;
157 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
158 size_t size, int flags)
160 struct sysfs_dirent *sd = dentry->d_fsdata;
168 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
169 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
170 error = security_inode_setsecurity(dentry->d_inode, suffix,
174 error = security_inode_getsecctx(dentry->d_inode,
175 &secdata, &secdata_len);
179 mutex_lock(&sysfs_mutex);
180 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
181 mutex_unlock(&sysfs_mutex);
184 security_release_secctx(secdata, secdata_len);
191 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
193 inode->i_mode = mode;
194 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
197 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
199 inode->i_mode = iattr->ia_mode;
200 inode->i_uid = iattr->ia_uid;
201 inode->i_gid = iattr->ia_gid;
202 inode->i_atime = iattr->ia_atime;
203 inode->i_mtime = iattr->ia_mtime;
204 inode->i_ctime = iattr->ia_ctime;
209 * sysfs has a different i_mutex lock order behavior for i_mutex than other
210 * filesystems; sysfs i_mutex is called in many places with subsystem locks
211 * held. At the same time, many of the VFS locking rules do not apply to
212 * sysfs at all (cross directory rename for example). To untangle this mess
213 * (which gives false positives in lockdep), we're giving sysfs inodes their
214 * own class for i_mutex.
216 static struct lock_class_key sysfs_inode_imutex_key;
218 static int sysfs_count_nlink(struct sysfs_dirent *sd)
220 struct sysfs_dirent *child;
223 for (child = sd->s_dir.children; child; child = child->s_sibling)
224 if (sysfs_type(child) == SYSFS_DIR)
230 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
232 struct bin_attribute *bin_attr;
233 struct sysfs_inode_attrs *iattrs;
235 inode->i_private = sysfs_get(sd);
236 inode->i_mapping->a_ops = &sysfs_aops;
237 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
238 inode->i_op = &sysfs_inode_operations;
239 inode->i_ino = sd->s_ino;
240 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
242 iattrs = sd->s_iattr;
244 /* sysfs_dirent has non-default attributes
245 * get them for the new inode from persistent copy
248 set_inode_attr(inode, &iattrs->ia_iattr);
249 if (iattrs->ia_secdata)
250 security_inode_notifysecctx(inode,
252 iattrs->ia_secdata_len);
254 set_default_inode_attr(inode, sd->s_mode);
256 /* initialize inode according to type */
257 switch (sysfs_type(sd)) {
259 inode->i_op = &sysfs_dir_inode_operations;
260 inode->i_fop = &sysfs_dir_operations;
261 inode->i_nlink = sysfs_count_nlink(sd);
263 case SYSFS_KOBJ_ATTR:
264 inode->i_size = PAGE_SIZE;
265 inode->i_fop = &sysfs_file_operations;
267 case SYSFS_KOBJ_BIN_ATTR:
268 bin_attr = sd->s_bin_attr.bin_attr;
269 inode->i_size = bin_attr->size;
270 inode->i_fop = &bin_fops;
272 case SYSFS_KOBJ_LINK:
273 inode->i_op = &sysfs_symlink_inode_operations;
279 unlock_new_inode(inode);
283 * 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 sysfs_dirent *sd)
300 inode = iget_locked(sysfs_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.delete_inode() implementation is needed to drop that
312 * reference upon inode destruction.
314 void sysfs_delete_inode(struct inode *inode)
316 struct sysfs_dirent *sd = inode->i_private;
318 truncate_inode_pages(&inode->i_data, 0);
323 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
325 struct sysfs_addrm_cxt acxt;
326 struct sysfs_dirent *sd;
331 sysfs_addrm_start(&acxt, dir_sd);
333 sd = sysfs_find_dirent(dir_sd, name);
335 sysfs_remove_one(&acxt, sd);
337 sysfs_addrm_finish(&acxt);