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 = {
34 .ra_pages = 0, /* No readahead */
35 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
38 static const struct inode_operations sysfs_inode_operations ={
39 .setattr = sysfs_setattr,
40 .setxattr = sysfs_setxattr,
43 int __init sysfs_inode_init(void)
45 return bdi_init(&sysfs_backing_dev_info);
48 struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
50 struct sysfs_inode_attrs *attrs;
53 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
56 iattrs = &attrs->ia_iattr;
58 /* assign default attributes */
59 iattrs->ia_mode = sd->s_mode;
62 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
66 int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
68 struct inode * inode = dentry->d_inode;
69 struct sysfs_dirent * sd = dentry->d_fsdata;
70 struct sysfs_inode_attrs *sd_attrs;
72 unsigned int ia_valid = iattr->ia_valid;
78 sd_attrs = sd->s_iattr;
80 error = inode_change_ok(inode, iattr);
84 iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
86 error = inode_setattr(inode, iattr);
91 /* setting attributes for the first time, allocate now */
92 sd_attrs = sysfs_init_inode_attrs(sd);
95 sd->s_iattr = sd_attrs;
97 /* attributes were changed at least once in past */
98 iattrs = &sd_attrs->ia_iattr;
100 if (ia_valid & ATTR_UID)
101 iattrs->ia_uid = iattr->ia_uid;
102 if (ia_valid & ATTR_GID)
103 iattrs->ia_gid = iattr->ia_gid;
104 if (ia_valid & ATTR_ATIME)
105 iattrs->ia_atime = timespec_trunc(iattr->ia_atime,
106 inode->i_sb->s_time_gran);
107 if (ia_valid & ATTR_MTIME)
108 iattrs->ia_mtime = timespec_trunc(iattr->ia_mtime,
109 inode->i_sb->s_time_gran);
110 if (ia_valid & ATTR_CTIME)
111 iattrs->ia_ctime = timespec_trunc(iattr->ia_ctime,
112 inode->i_sb->s_time_gran);
113 if (ia_valid & ATTR_MODE) {
114 umode_t mode = iattr->ia_mode;
116 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
118 iattrs->ia_mode = sd->s_mode = mode;
124 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
125 size_t size, int flags)
127 struct sysfs_dirent *sd = dentry->d_fsdata;
128 struct sysfs_inode_attrs *iattrs;
136 sd->s_iattr = sysfs_init_inode_attrs(sd);
140 iattrs = sd->s_iattr;
142 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
143 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
144 error = security_inode_setsecurity(dentry->d_inode, suffix,
148 error = security_inode_getsecctx(dentry->d_inode,
149 &secdata, &secdata_len);
152 if (iattrs->ia_secdata)
153 security_release_secctx(iattrs->ia_secdata,
154 iattrs->ia_secdata_len);
155 iattrs->ia_secdata = secdata;
156 iattrs->ia_secdata_len = secdata_len;
164 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
166 inode->i_mode = mode;
167 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
170 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
172 inode->i_mode = iattr->ia_mode;
173 inode->i_uid = iattr->ia_uid;
174 inode->i_gid = iattr->ia_gid;
175 inode->i_atime = iattr->ia_atime;
176 inode->i_mtime = iattr->ia_mtime;
177 inode->i_ctime = iattr->ia_ctime;
182 * sysfs has a different i_mutex lock order behavior for i_mutex than other
183 * filesystems; sysfs i_mutex is called in many places with subsystem locks
184 * held. At the same time, many of the VFS locking rules do not apply to
185 * sysfs at all (cross directory rename for example). To untangle this mess
186 * (which gives false positives in lockdep), we're giving sysfs inodes their
187 * own class for i_mutex.
189 static struct lock_class_key sysfs_inode_imutex_key;
191 static int sysfs_count_nlink(struct sysfs_dirent *sd)
193 struct sysfs_dirent *child;
196 for (child = sd->s_dir.children; child; child = child->s_sibling)
197 if (sysfs_type(child) == SYSFS_DIR)
203 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
205 struct bin_attribute *bin_attr;
206 struct sysfs_inode_attrs *iattrs;
208 inode->i_private = sysfs_get(sd);
209 inode->i_mapping->a_ops = &sysfs_aops;
210 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
211 inode->i_op = &sysfs_inode_operations;
212 inode->i_ino = sd->s_ino;
213 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
215 iattrs = sd->s_iattr;
217 /* sysfs_dirent has non-default attributes
218 * get them for the new inode from persistent copy
221 set_inode_attr(inode, &iattrs->ia_iattr);
222 if (iattrs->ia_secdata)
223 security_inode_notifysecctx(inode,
225 iattrs->ia_secdata_len);
227 set_default_inode_attr(inode, sd->s_mode);
229 /* initialize inode according to type */
230 switch (sysfs_type(sd)) {
232 inode->i_op = &sysfs_dir_inode_operations;
233 inode->i_fop = &sysfs_dir_operations;
234 inode->i_nlink = sysfs_count_nlink(sd);
236 case SYSFS_KOBJ_ATTR:
237 inode->i_size = PAGE_SIZE;
238 inode->i_fop = &sysfs_file_operations;
240 case SYSFS_KOBJ_BIN_ATTR:
241 bin_attr = sd->s_bin_attr.bin_attr;
242 inode->i_size = bin_attr->size;
243 inode->i_fop = &bin_fops;
245 case SYSFS_KOBJ_LINK:
246 inode->i_op = &sysfs_symlink_inode_operations;
252 unlock_new_inode(inode);
256 * sysfs_get_inode - get inode for sysfs_dirent
257 * @sd: sysfs_dirent to allocate inode for
259 * Get inode for @sd. If such inode doesn't exist, a new inode
260 * is allocated and basics are initialized. New inode is
264 * Kernel thread context (may sleep).
267 * Pointer to allocated inode on success, NULL on failure.
269 struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
273 inode = iget_locked(sysfs_sb, sd->s_ino);
274 if (inode && (inode->i_state & I_NEW))
275 sysfs_init_inode(sd, inode);
281 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
282 * To prevent the sysfs inode numbers from being freed prematurely we take a
283 * reference to sysfs_dirent from the sysfs inode. A
284 * super_operations.delete_inode() implementation is needed to drop that
285 * reference upon inode destruction.
287 void sysfs_delete_inode(struct inode *inode)
289 struct sysfs_dirent *sd = inode->i_private;
291 truncate_inode_pages(&inode->i_data, 0);
296 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
298 struct sysfs_addrm_cxt acxt;
299 struct sysfs_dirent *sd;
304 sysfs_addrm_start(&acxt, dir_sd);
306 sd = sysfs_find_dirent(dir_sd, name);
308 sysfs_remove_one(&acxt, sd);
310 sysfs_addrm_finish(&acxt);