2 * inode.c - basic inode and dentry operations.
4 * sysfs is Copyright (c) 2001-3 Patrick Mochel
6 * Please see Documentation/filesystems/sysfs.txt for more information.
11 #include <linux/pagemap.h>
12 #include <linux/namei.h>
13 #include <linux/backing-dev.h>
14 #include <linux/capability.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
17 #include <asm/semaphore.h>
20 extern struct super_block * sysfs_sb;
22 static const struct address_space_operations sysfs_aops = {
23 .readpage = simple_readpage,
24 .prepare_write = simple_prepare_write,
25 .commit_write = simple_commit_write
28 static struct backing_dev_info sysfs_backing_dev_info = {
29 .ra_pages = 0, /* No readahead */
30 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
33 static const struct inode_operations sysfs_inode_operations ={
34 .setattr = sysfs_setattr,
37 void sysfs_delete_inode(struct inode *inode)
39 /* Free the shadowed directory inode operations */
40 if (sysfs_is_shadowed_inode(inode)) {
44 return generic_delete_inode(inode);
47 int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
49 struct inode * inode = dentry->d_inode;
50 struct sysfs_dirent * sd = dentry->d_fsdata;
51 struct iattr * sd_iattr;
52 unsigned int ia_valid = iattr->ia_valid;
58 sd_iattr = sd->s_iattr;
60 error = inode_change_ok(inode, iattr);
64 error = inode_setattr(inode, iattr);
69 /* setting attributes for the first time, allocate now */
70 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
73 /* assign default attributes */
74 sd_iattr->ia_mode = sd->s_mode;
77 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
78 sd->s_iattr = sd_iattr;
81 /* attributes were changed atleast once in past */
83 if (ia_valid & ATTR_UID)
84 sd_iattr->ia_uid = iattr->ia_uid;
85 if (ia_valid & ATTR_GID)
86 sd_iattr->ia_gid = iattr->ia_gid;
87 if (ia_valid & ATTR_ATIME)
88 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
89 inode->i_sb->s_time_gran);
90 if (ia_valid & ATTR_MTIME)
91 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
92 inode->i_sb->s_time_gran);
93 if (ia_valid & ATTR_CTIME)
94 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
95 inode->i_sb->s_time_gran);
96 if (ia_valid & ATTR_MODE) {
97 umode_t mode = iattr->ia_mode;
99 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
101 sd_iattr->ia_mode = sd->s_mode = mode;
107 static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
109 inode->i_mode = mode;
112 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
115 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
117 inode->i_mode = iattr->ia_mode;
118 inode->i_uid = iattr->ia_uid;
119 inode->i_gid = iattr->ia_gid;
120 inode->i_atime = iattr->ia_atime;
121 inode->i_mtime = iattr->ia_mtime;
122 inode->i_ctime = iattr->ia_ctime;
127 * sysfs has a different i_mutex lock order behavior for i_mutex than other
128 * filesystems; sysfs i_mutex is called in many places with subsystem locks
129 * held. At the same time, many of the VFS locking rules do not apply to
130 * sysfs at all (cross directory rename for example). To untangle this mess
131 * (which gives false positives in lockdep), we're giving sysfs inodes their
132 * own class for i_mutex.
134 static struct lock_class_key sysfs_inode_imutex_key;
136 struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
138 struct inode * inode = new_inode(sysfs_sb);
141 inode->i_mapping->a_ops = &sysfs_aops;
142 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
143 inode->i_op = &sysfs_inode_operations;
144 inode->i_ino = sd->s_ino;
145 lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
148 /* sysfs_dirent has non-default attributes
149 * get them for the new inode from persistent copy
152 set_inode_attr(inode, sd->s_iattr);
154 set_default_inode_attr(inode, mode);
159 int sysfs_create(struct sysfs_dirent *sd, struct dentry *dentry, int mode,
160 int (*init)(struct inode *))
163 struct inode * inode = NULL;
165 if (!dentry->d_inode) {
166 if ((inode = sysfs_new_inode(mode, sd))) {
167 if (dentry->d_parent && dentry->d_parent->d_inode) {
168 struct inode *p_inode = dentry->d_parent->d_inode;
169 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
185 d_instantiate(dentry, inode);
187 dget(dentry); /* pin only directory dentry in core */
195 * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
196 * @sd: target sysfs_dirent
198 * Drop dentry for @sd. @sd must have been unlinked from its
199 * parent on entry to this function such that it can't be looked
202 * @sd->s_dentry which is protected with sysfs_lock points to the
203 * currently associated dentry but we're not holding a reference
204 * to it and racing with dput(). Grab dcache_lock and verify
205 * dentry before dropping it. If @sd->s_dentry is NULL or dput()
206 * beats us, no need to bother.
208 void sysfs_drop_dentry(struct sysfs_dirent *sd)
210 struct dentry *dentry = NULL, *parent = NULL;
212 struct timespec curtime;
214 /* We're not holding a reference to ->s_dentry dentry but the
215 * field will stay valid as long as sysfs_lock is held.
217 spin_lock(&sysfs_lock);
218 spin_lock(&dcache_lock);
220 if (sd->s_dentry && sd->s_dentry->d_inode) {
221 /* get dentry if it's there and dput() didn't kill it yet */
222 dentry = dget_locked(sd->s_dentry);
223 parent = dentry->d_parent;
224 } else if (sd->s_parent->s_dentry->d_inode) {
225 /* We need to update the parent even if dentry for the
226 * victim itself doesn't exist.
228 parent = dget_locked(sd->s_parent->s_dentry);
233 spin_lock(&dentry->d_lock);
235 spin_unlock(&dentry->d_lock);
238 spin_unlock(&dcache_lock);
239 spin_unlock(&sysfs_lock);
241 /* nothing to do if the parent isn't in dcache */
245 /* adjust nlink and update timestamp */
246 dir = parent->d_inode;
247 mutex_lock(&dir->i_mutex);
249 curtime = CURRENT_TIME;
251 dir->i_ctime = dir->i_mtime = curtime;
254 dentry->d_inode->i_ctime = curtime;
255 drop_nlink(dentry->d_inode);
256 if (sd->s_type & SYSFS_DIR) {
257 drop_nlink(dentry->d_inode);
259 /* XXX: unpin if directory, this will go away soon */
264 mutex_unlock(&dir->i_mutex);
273 int sysfs_hash_and_remove(struct dentry * dir, const char * name)
275 struct sysfs_dirent * sd;
276 struct sysfs_dirent * parent_sd;
282 if (dir->d_inode == NULL)
283 /* no inode means this hasn't been made visible yet */
286 parent_sd = dir->d_fsdata;
287 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
288 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
291 if (!strcmp(sd->s_name, name)) {
292 list_del_init(&sd->s_sibling);
297 mutex_unlock(&dir->d_inode->i_mutex);
302 sysfs_drop_dentry(sd);
303 sysfs_deactivate(sd);