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 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;
67 int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
69 struct inode * inode = dentry->d_inode;
70 struct sysfs_dirent * sd = dentry->d_fsdata;
71 struct sysfs_inode_attrs *sd_attrs;
73 unsigned int ia_valid = iattr->ia_valid;
79 sd_attrs = sd->s_iattr;
81 error = inode_change_ok(inode, iattr);
85 iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
87 error = inode_setattr(inode, iattr);
92 /* setting attributes for the first time, allocate now */
93 sd_attrs = sysfs_init_inode_attrs(sd);
96 sd->s_iattr = sd_attrs;
98 /* attributes were changed at least once in past */
99 iattrs = &sd_attrs->ia_iattr;
101 if (ia_valid & ATTR_UID)
102 iattrs->ia_uid = iattr->ia_uid;
103 if (ia_valid & ATTR_GID)
104 iattrs->ia_gid = iattr->ia_gid;
105 if (ia_valid & ATTR_ATIME)
106 iattrs->ia_atime = timespec_trunc(iattr->ia_atime,
107 inode->i_sb->s_time_gran);
108 if (ia_valid & ATTR_MTIME)
109 iattrs->ia_mtime = timespec_trunc(iattr->ia_mtime,
110 inode->i_sb->s_time_gran);
111 if (ia_valid & ATTR_CTIME)
112 iattrs->ia_ctime = timespec_trunc(iattr->ia_ctime,
113 inode->i_sb->s_time_gran);
114 if (ia_valid & ATTR_MODE) {
115 umode_t mode = iattr->ia_mode;
117 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
119 iattrs->ia_mode = sd->s_mode = mode;
125 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
126 size_t size, int flags)
128 struct sysfs_dirent *sd = dentry->d_fsdata;
129 struct sysfs_inode_attrs *iattrs;
137 sd->s_iattr = sysfs_init_inode_attrs(sd);
141 iattrs = sd->s_iattr;
143 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
144 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
145 error = security_inode_setsecurity(dentry->d_inode, suffix,
149 error = security_inode_getsecctx(dentry->d_inode,
150 &secdata, &secdata_len);
153 if (iattrs->ia_secdata)
154 security_release_secctx(iattrs->ia_secdata,
155 iattrs->ia_secdata_len);
156 iattrs->ia_secdata = secdata;
157 iattrs->ia_secdata_len = secdata_len;
165 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
167 inode->i_mode = mode;
168 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
171 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
173 inode->i_mode = iattr->ia_mode;
174 inode->i_uid = iattr->ia_uid;
175 inode->i_gid = iattr->ia_gid;
176 inode->i_atime = iattr->ia_atime;
177 inode->i_mtime = iattr->ia_mtime;
178 inode->i_ctime = iattr->ia_ctime;
183 * sysfs has a different i_mutex lock order behavior for i_mutex than other
184 * filesystems; sysfs i_mutex is called in many places with subsystem locks
185 * held. At the same time, many of the VFS locking rules do not apply to
186 * sysfs at all (cross directory rename for example). To untangle this mess
187 * (which gives false positives in lockdep), we're giving sysfs inodes their
188 * own class for i_mutex.
190 static struct lock_class_key sysfs_inode_imutex_key;
192 static int sysfs_count_nlink(struct sysfs_dirent *sd)
194 struct sysfs_dirent *child;
197 for (child = sd->s_dir.children; child; child = child->s_sibling)
198 if (sysfs_type(child) == SYSFS_DIR)
204 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
206 struct bin_attribute *bin_attr;
207 struct sysfs_inode_attrs *iattrs;
209 inode->i_private = sysfs_get(sd);
210 inode->i_mapping->a_ops = &sysfs_aops;
211 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
212 inode->i_op = &sysfs_inode_operations;
213 inode->i_ino = sd->s_ino;
214 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
216 iattrs = sd->s_iattr;
218 /* sysfs_dirent has non-default attributes
219 * get them for the new inode from persistent copy
222 set_inode_attr(inode, &iattrs->ia_iattr);
223 if (iattrs->ia_secdata)
224 security_inode_notifysecctx(inode,
226 iattrs->ia_secdata_len);
228 set_default_inode_attr(inode, sd->s_mode);
230 /* initialize inode according to type */
231 switch (sysfs_type(sd)) {
233 inode->i_op = &sysfs_dir_inode_operations;
234 inode->i_fop = &sysfs_dir_operations;
235 inode->i_nlink = sysfs_count_nlink(sd);
237 case SYSFS_KOBJ_ATTR:
238 inode->i_size = PAGE_SIZE;
239 inode->i_fop = &sysfs_file_operations;
241 case SYSFS_KOBJ_BIN_ATTR:
242 bin_attr = sd->s_bin_attr.bin_attr;
243 inode->i_size = bin_attr->size;
244 inode->i_fop = &bin_fops;
246 case SYSFS_KOBJ_LINK:
247 inode->i_op = &sysfs_symlink_inode_operations;
253 unlock_new_inode(inode);
257 * sysfs_get_inode - get inode for sysfs_dirent
258 * @sd: sysfs_dirent to allocate inode for
260 * Get inode for @sd. If such inode doesn't exist, a new inode
261 * is allocated and basics are initialized. New inode is
265 * Kernel thread context (may sleep).
268 * Pointer to allocated inode on success, NULL on failure.
270 struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
274 inode = iget_locked(sysfs_sb, sd->s_ino);
275 if (inode && (inode->i_state & I_NEW))
276 sysfs_init_inode(sd, inode);
282 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
283 * To prevent the sysfs inode numbers from being freed prematurely we take a
284 * reference to sysfs_dirent from the sysfs inode. A
285 * super_operations.delete_inode() implementation is needed to drop that
286 * reference upon inode destruction.
288 void sysfs_delete_inode(struct inode *inode)
290 struct sysfs_dirent *sd = inode->i_private;
292 truncate_inode_pages(&inode->i_data, 0);
297 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
299 struct sysfs_addrm_cxt acxt;
300 struct sysfs_dirent *sd;
305 sysfs_addrm_start(&acxt, dir_sd);
307 sd = sysfs_find_dirent(dir_sd, name);
309 sysfs_remove_one(&acxt, sd);
311 sysfs_addrm_finish(&acxt);